Optical Computing With Nonlinear Optics
Author(s):
Galina Khitrova;
Hyatt Gibbs;
Nasser Peyghambarian
Show Abstract
Nonlinear optics is becoming a new thrust in the field of optical computing and signal processing.14 Optical nonlinearity makes the device's transmission intensity dependent, so one can obtain the thresholding needed for logic decisionmaking. Thresholding is essential to digital optical computing, neural nets, and associative memories. GaAs etalons exhibit many of the characteristics desirable for the nonlinear devices including high speed (picosecond) and diode-laser compatability. However, demonstrations of the use of nonlinear decisionmaking for optical computing have used ZnS or ZnSe interference filters. They are slow (millisecond), but they can be used with the visible 514.5-nm output of an argon laser. We have used such filters to demonstrate all-optical logic operations, one-bit addition by symbolic substitution, and recognition of a three-spot pattern in an arbitrary 2 x 8 array of input beams. The application to associative memories is under study.
GaAs-AlAs Monolithic Microresonator Arrays
Author(s):
J. L. Jewell;
A. Scherer;
S. L. McCall;
A. C. Gossard;
J. H. English
Show Abstract
Miniaturization of optical logic devices has long been considered to be a key to minimizing their energy requirements but was also considered difficult to achievel-4 .. We demonstrate a straightforward technique for fabricating arrays of GaAs,'"Fabry-Perot etalon devices (microrronators) as small as 1.5 μm in diameter. The growth of integrated GaAs-AlAs nonlinear etalons by molecular beam epitaxy (MBE) offers much improved manufacturability and uniformity over previous fabrication techniques From From the sample of reference' 5 we have formed close-packed arrays of monolithic "posts" or microresonators 1.5- 5 μm across by ion-beam assisted etching and have performed optical NOR/OR gating experiments on them using picosecond. pump and probe pulses. These microresonators represent a qualitative advance over the GaAs devices reported by Lee et al .8. In that work peels 9x 9 μm square were formed in the active material only, and then sandwiched between dielectric mirrors in the usual way Growth of integrated devices by 'epitaxial. techniques such as MBE allows us to etch right through both mirrors and the active material. This is critical since in an optimized nonlinear etalon the dielectric mirrors comprise most of the total thickness. The lateral optical confi.nement in these waveguidiv ttructures allows efficient operation with diameters as small as one can focus the light. Elimination of carrier diffusion. "1 out of the devices permits very close spacig. Reduction of energy requirements is expected d e to the decreased volume of interaction. Finally, surface recombination ".' on the aidewalla of the microresonators should produce fast relaxation times. Our experiments show more than an order of magnitude reducion in energy requirements, essentially uniform response over small arrays, practically no crosstalk with 3-μm center-center ,spacing, 150 ps full recovery time, and thermal stability at 82 Mllz operating frequency.
Low Loss Polarization-Based Optical Logic Gates
Author(s):
W. T. Cathey;
R. A. Schmidt
Show Abstract
The gate design reported here is an outgrowth of a study of the use of optical computing for artificial intelligence1,2. The particular area chosen for study was mathematical resolution,3,4 a method of reasoning using boolean algebra. In common with other non-arithmetic uses of optical computing, the operations involved in the process of mathematical resolution require the cascading of multiple levels of logic. For example, the basic operation in resolution, resolvent formation, requires on the order of log2 (n) levels of logic to validate the resolvent of two clauses each containing n terms. Since in a real system, n might easily be 1024, and each level of logic might require two levels of optical gates, on the order of 20 gates might have to be cascaded in order to generate an output.
Phase Measuring Interferometry With A Tunable Semiconductor Laser
Author(s):
Y. Ishii;
J. Chen;
K. Murata
Show Abstract
Several authors1'2) have developed a digital heterodyne or a fringe-scanning interferometry employing the phase shifter such as a piezoelectric transducer (PZT). Recently semiconductor lasers (LD's) are usable and potentially reliable for key devices in optics. One of the features of LD is tunability, in which the wavelength of a single-mode laser can be changed continuously by the variation of the injection current and/or the temperature of active region. Therefore, it is possible to consider that a phase measuring interferometry can be realized by changing the relative phase difference between the two beams of the interferometer with the frequency modulation of
Two-Wavelength Laser Interferometry Using Super-Heterodyne Detection
Author(s):
R. Dandliker;
R. Thalmann;
D. Prongue
Show Abstract
Two-wavelength interferometry is well known since years and often used for ranging and contouring at reduced sensitivity 1. Recently, two-wavelength heterodyne interferometry has been reported, which can be applied for both, smooth and rough surfaces 2. However, this method is limited to large wavelength differences, which can be optically separated (prism, grating). By the availability of tunable diode-lasers as light sources, multiple wavelength interferometry with small wavelength differences is getting increased practical interest 3. It is the purpose of this paper to present a novel method, based on super-heterod e detection, which allows to make high resolution measurements at 241-- I effective difference wavelengths Λ = λ1 λ2λ1- shorter than 30 cm, without being obliged to have interferometric stability at the optical wavelengths Xi and1. itse and to separate these wavelengths optically. This is of great importance for range finding and industrial distance measuring with submillimeter resolution.
Digital Phase-Shifting Interferometry
Author(s):
P. Hariharan
Show Abstract
Interferometry is a very powerful tool for making accurate measurements. However, conventional interferometric methods have some serious limitations. With two-beam interference, the accuracy with which the centre of a fringe can be located is limited by the sinusoidal intensity distribution in the fringe pattern. In addition, quantitative information on the shape of a surface is available only along the intensity minima and maxima. Data at other points can be obtained only by interpolation or by introducing a number of fringes across the field. Finally, it is often difficult to identify the sense of a slope and ambiguities can arise. This is particularly true when the fringes are irregular and unequally spaced. Various methods have been explored to solve these problems.' One of the earliest was the use of a television camera linked to a digital computer to store and process the intensity distribution in the fringes to locate the maxima and minima. A commonly used method is heterodyne interferometry, in which a frequency difference is introduced between the beams. However, the technique most widely used currently is digital phase-shifting interferometry.
Optical Modeling Of The Aging Human Eye
Author(s):
J. Warren Blaker
Show Abstract
There are a number of models for the human eye developed principally to aid in the understanding of ijefraction and accommodation or the aberrations of the eye system. These use either a uniform lens , a small number of constant index layers as in the Gullstrand mode12, or a gradient index structure.3 However, none of these have addressed themselves to the question of the aging eye as far as we have been able to determine.
Ultrashort IR Laser Pulse Isomerization Of All-Trans Retinal To 11 CIS Retinal
Author(s):
J. Taboada;
J. Liegner;
A. T.C. Tsin
Show Abstract
The mammalian ocular system possesses a significant IR transmission window between the longest visually detectable light wavelength at 700 nm and the cut off water absorption band at 1400 nm. This near IR optical band may provide a channel for controlling vision processes. Of particular interest is the regeneration process which involves the re -Wmerization of all-trans retinal to 11-cis retinal and the molecular recoupling of retinal with opsin.". This re-isomerization, moving against potential energy gradient, is the rate limiting step is assumed to involve either a vitamin A intermediate or a directly applied enzyme, "isomerase"). The concept investigated in this study concerns the possibility of directly influencing the isomerization process by ultrashort IR laser pulses.
Macroscopic Response Of The Retinal Mosaic To The Light Stimulus: Linear Array Model
Author(s):
P. K. Mondal;
M. L. Calvo
Show Abstract
It is known that the cones and rods of the retina have directional sensitivity. For a normal observer, in the absence of aberrations like myopia, astigmatism, etc. the light entering the pupil of the eye is directly focussed on the retinal plane by the optical system of the eye. There, in the retina, the cones and the rods are regularly distributed in different retinal regions forming a mosaic structure. It is very well established from the earlier works of Enoch, (1), that both types of optical photoreceptors act as optical waveguides. This behaviour can be accounted for due to their special optical properties allowing conditions for total internal reflections inside its structure. At the time of the confinement of the energy inside each single receptor an important phenomenon of orientation takes place as well. In this work, we wish to establish that the various effects arising out of this phenomenon can be interpreted in terms of a possible apodising action of the eye.It will be shown that an improvement in the resolution of the retinal image detection is possible by comparing the human visual system with an apodised optical system. For that purpose we have established a linear array model for a section of the fovea, ( all receptors having the same geometry and optical properties ), then, we have calculated the distribution of the density of energy captured in this particular section of the retina, by assuming that the receptors are acting as monomode optical waveguides.The orientation mechanism is also considered, by including an inclination factor affecting each single receptor. We have compared the so obtained distribution to the one associated to a single receptor
Optical Turing Machines
Author(s):
R. Arrathoon
Show Abstract
The architecture for two classes of optical Turing machines based on optoelectronic programmable logic arrays and on reconfigurable optoelectronic programmable logic arrays is presented. The potential capabilities of the optical machines are compared to those of existing electronic logic.
Reversible Optical Computing Circuits
Author(s):
Robert Cuykendall;
David R. Andersen
Show Abstract
The theory of reversible computing is based upon composition of invertible primitives. In a conventional computer the computation is locally organized around computing primitives, such as the NAND gate, which are noninvertible. Thus, when performing the AND operation a certain amount of information about the system's past is generally erased. This loss of information or damping associated with an irreversible process must be acc9mpanied by the thermalization of an amount kg of energy per bit. Interest in reversible computation thus arises from the desire to reduce heat dissipation in computing circuits, thereby allowing higher density and speed.
Implementations Of Optical Parallel Logic Using Magneto-Optic Spatial Light Modulators, Liquid Crystal Televisions And Microchannel Spatial Light Modulator
Author(s):
F. T. S. Yu;
S. Jutamulia;
T. Lu;
J. S. Jin;
Q. Song;
X. J. Lu;
Don A. Gregory
Show Abstract
Optical and electro-optical switches have been extensively studied for applications such as optical computing, opto-digital circuit, and optical communication networks. As complement to the rapidly emerging photonic devices, many optical parallel logic gates have been successfully implemented using current technology. This paper demonstrates three implementations of optical parellel logic using magneto-optic spatial light modulators (MOSLMs), liquid crystal televisions (LCTVs) and microchannel spatial light modulator (MSLM), respectively.
An Extension Of The Hopfield Model Suitable For Optical Implementation
Author(s):
Ph. Lalanne;
J. Taboury;
J. C. Saget;
P. Chavel
Show Abstract
The analysis of neural models as associative memories has proven a fruitful domain of research. Two principal directions may be put forward : models tending to investigate learning processes in the human brain, and algorithms tending to increase the efficiency of associative memories.
A Class of Continuous Level Neural Nets
Author(s):
Robert J. Marks II;
Les E. Atlas;
Kwan F. Cheung
Show Abstract
A neural net capable of restoring continuous level library vectors from memory is considered. The vectors in the memory library are used to program the neural interconnects. Given a portion of one of the library vectors, the net extrapolates the remainder. Sufficient conditions for unique convergence are stated. An architecture for optical implementation of the network is proposed.
Heterodyne Interferometry With A Frequency Modulation Of A Laser Diode
Author(s):
J. Chen;
Y. Ishii;
K. Murata
Show Abstract
Over the last few years, a heterodyne or a fringe-scanning interferometry12) has been widely used in optical testing because of its fast and accurate phase-measurement. One can perform direct phase measurement by obtaining three or more intensity readings of fringe patterns when the phase difference between the two interfering beams is varied in some known manner either changing in discrete steps or charging linearly in respect to time. As a frequency shifter, a piezoelectric shifter, rotating gratings etc. have been employed. In contrast to using such mechanical moving Darts, frequency modulation of a laser diode by changing the injection current is very simple). We propose a heterodyne interferometer with a frequency-modulated laser diode source, which is based on a integrated-bucket method with continuous wavelength change by linear variation of injection current. The method is described and some experimental results are shown.
Real-Time Fringe Processing by Hybrid Analog-Digital System
Author(s):
S. Toyooka;
K. Ohashi;
K. Yamada;
K. Kobayashi
Show Abstract
Two-dimensional fringe pattern such as interference fringes or incoherent grating-like pattern are widely used to measure surface configuration, roughness, and deformation. Recently several methods of automatic fringe processing have been developed. These methods are on the basis of Fourier analysis and then have high precision. They can be classified into two typed in which a desired phase modulation is treated (1) on temporally varying carrier such as fringe scanning method (2) on spatially varying carrier such as Fourier transform method":). In the later, whole field of phase distribution can be determined by analyzing only one fringe pattern, and then real-time processing is possible In our present paper, we propose real-time fringe processing system by using an analog-digital hybrid system.
Interferometric Data Fitting On Zernike Like Orthogonal Basis.
Author(s):
D. Malacara;
J. M. Carpio-Valadez;
J. J. Sanchez-Mondragon
Show Abstract
We present a data fitting method that uses the near orthogonality of the Circular Zernike Polynomials 41(r,9) on the data collected on an interferogram in order to obtain the best rms fit. This is obtained through the generation of an orthogonal basis from the 4(r,9) on the discrete and irregular interferometric data set give by the experimental circular pupil. The rms fit with this basis is comparable to analogous methods to a fraction of computational time, cost and requirements.
Applications Of A Spatial Filtering Detector To Dynamic Interferometry
Author(s):
Ichirou Yamaguchi
Show Abstract
Interferometry has recently shown great advances in practical applications owing to progress and utility of electrooptic devices and computers. For objects of interferometry it is now strongly desired to measure such dynamic quantities as displacement, vibration, strain, and temperature. In this case rapid movement of interference fringes or speckle patterns has to be detected. However, the conventional image processing techniques using digital computers are not quick enough for this purpose. For reducing computation time it is necessary to endow the detector with a preprocessing function. One of the solutions is a spatial filtering detector with electronic scanning facility which has been used for three dimensional displacement meter [1] and for accerelating a laser speckle strain gauge [2]. This detector, which consists of a photodiode array and its control circuit, delivers a voltage that is proportional to speckle displacement normal to the array. This paper reports applications of this detector to catch the movement of speckles and interference fringes obtained from optical fiber interferometers.
Automatic Processing Of Fringes Obtained By Shearography
Author(s):
J Takezaki;
S. Toyooka;
H. Nishida;
H. Kobayash
Show Abstract
Strains in a flexed plate are directly related to the second derivatives of plate deflection. Shearography[1] measures the first derivative of deflections. Therefore, it still requires one more differentiation to obtain the flexural strains. Furthermore, a fringe pattern by shearography is a contour derivative fringe pattern. Automatic fringe analysis is, therefore. required since differentiation or the analysis of the fringe pattern for whole-field is not only laborious but also causes a majore source of error. In order to carry out automatic fringe processing. a "fictious fringe carrier" is introduced to shearography[2]. A fictious frige carrier processes linear fringes of equal spacing in the shearing direction. A perturbed linear fringe carrier is obtained when a flexed plate is deformed. The local perturbation depends on the local deflection gradients. This paper describes the fringe analysis of shearography by making use of spatial phase detection[3]. A deformed carrier fringe pattern is regarded as the phase modulated pattern with a constant spatial carrier. To retrieve phase modulation, the aquired data by TV systems are sinusoidally fitted by using a phase detection algorithm.
Hybrid Interferometers: A Study Of The Coupling Of Optical Surfaces In Incoherent Light
Author(s):
W. Ward;
W. A . Gault;
R. Wiens;
G. G. Shepherd
Show Abstract
Two studies (Ward et. al.(1985), Ward et. al.(1987)) have been undertaken to analyse the cause of secondary fringes in a wide angle Michelson interferometer (Shepherd et. al.(1985)) and determine methods for their elimination. Out of these studies some general considerations on the coupling of optical surfaces in incoherent light have been developed. Surfaces which are coupled in such a way that the fringe form must be calculated from amplitude considerations are considered to be coherently coupled whereas surfaces coupled in such a way that the fringe form can be calculated from intensity calculations are considered to be incoherently coupled. Since the observed fringe form of the interferometers considered in the above studies were neither that of a Michelson interferometer nor that of traditional multi-reflection devices such as the Fabry-Perot interferometer, the phrase 'hybrid interferometer' was coined to describe them. In this paper these considerations on the coupling of optical surfaces are summarized. In addition the conditions under which orthogonal polarization states can be used to provide independent sets of fringes is noted. These theoretical considerations are illustrated with examples of several 'hybrid interferometers'.
Optical Quality Of The Embryonic Human Lens
Author(s):
J. G. Sivak;
A. Dovrat
Show Abstract
In all vertebrates the ocular lens is a cellar structure that develops initially as a hollow spherical invagination of the surface ectoderm. ' The hollow sphere becomes filled by elongating posterior cells, the primary lens fibers. Subsequent growth takes place at the periphery through the anterior-posterior growth of new cells formed at the equator, the secondary lens fibers. The continued peripheral growth of the lens, resulting in the compression of the older tissue toward the centre, has the important optical consequence of producing a lens of variable refractive index, the index being highest at the centre. This variation in index is an important means by which lens spherical aberration is controlled.
3D Imaging Of The Human Eye Using The Laser Tomographic Scanner Lts
Author(s):
J. F. Bille;
S. I. Brown
Show Abstract
The Laser Tomographic Scanner LTS is an instrument for contact-free measurement of curvature, thick-ness and incision profiles of the human cornea and of topographic features of the human retina. A line-shaped laser beam is focused onto the eye via special optics. The intensity of the reflected light is detected only if it originates from a very small region around the focal plane of the special optics. Consequently, images with high spatial resolution in all directions are obtained. The line-shaped beam is imaged on the eye with arbitrary direction of the line. At the same time, the focal plane of the special optics is moved periodically. This results in real-time section images of the cornea as well as the retina perpendicular to its surface. System functions are computer-controlled. The instrument is equipped with a powerful computer image processor which produces operator-independent results with high accuracy within seconds.
The Influence Of The Crystalline Lens On The Image Quality Of The Eye
Author(s):
Melanie C. W. Campbell
Show Abstract
The refractive index distribution within the crystalline lens is important in determining the image quality of the lens and eye. Postulated advantages of a gradient refractive index (GRIN) which increases from the edge of the lens to the centre include al increase in overall lens power, a decryse in spherical aberration, a decrease in off-axis astigmatism and a decrease in chromatic aberration of the lens and eye.
Visual Sensitivity To Temporal Change In Focus And Its Relevance To The Accommodation Response
Author(s):
W. N. Charman;
G. Walsh
Show Abstract
It is well known that the steady-state accommodation response varies with the spatial frequency content of the observed object: in general the response does not exactly match the stimulus and small 'lags' and 'leads' in accommodation are found, depending upon the stimulus level, the observer and the observing conditions. It has been hypothesisedl-J that the establishment and maintenance of the steady-state response may depend upon the temporal changes in the retinal image caused by the small temporal changes, or fluctuations, in accommodation which are known to be an intrinsic part of the system and which have frequencies up to a few Herz and amplitudes of about 0.1 dioptre. To establish the feasibility of such hypotheses it is necessary to determine the sensitivity of observers to temporal change in the focus of the retinal image, as a function of the mean position of focus. Campbell 4 provided some early evidence that sensitivity to temporal focus change was of the right order of magnitude to support the general concept and the present study sought to explore such sensitivity in more detail.
Determination Of The Wave Aberration Of The Human Eye Using A Phase Retrieval Algorithm.
Author(s):
Pablo Artel;
Javier Santamaria;
Julian Bescos
Show Abstract
Generally, the optical quality of the dioptrics of the human eye has been described in terms of the unidimensional modulation transfer function (M.T.F.) usually obtained from measurements of aerial images of lines test formed by the double pass through the optical medial). But due to the assimetries of the wave aberration of the eye, bidimensional information should be obtained for a complete evaluation. So, recently a hybrid optical-digital method for the determination of the bidimensional point spread function (P.S.F. and optical transfer function (O.T.F.) of the human eye has been presented293/. These functions although being of great utility for evaluation purposes do not carry all the optical information about the system as does the wave aberration. This is specially important in the case of the human eye, which always shows assymetries and irregular aberrations even in emmetropized eyes.
Multiple Aperture Telescopes And Adaptive Optics In Astronomy
Author(s):
Jacques M. Beckers
Show Abstract
With the advance of image reconstruction techniques, adaptive optics and telescope arrays, optical and infrared astronomy are going through a rapid evolution which in many ways compares with the developments in radio astronomy of the last decades. Whereas many optical and infrared astronomers still view large telescopes as devices to collect large number of photons, an increasing number are anticipating their use for diffraction-limited high angular resolution observations. This short overview will emphasize the latter.
Optical Long-Baseline Interferometry And Aperture Synthesis On Earth And In Space
Author(s):
G. Weigelt;
K. H. Hofmann;
T. Reinheimer
Show Abstract
During the last few years it has been shown that speckle masking observations with large telescopes can yield diffraction-limited images in spite of image degradation by the atmosphere and by telescope aberrations1-4. Much higher resolution can be obtained if the Coude beams of many telescopes are combined coherently in a central station and if the obtained long-baseline speckle interferograms are evaluated by speckle masking5,6. For example, a 10-km array on earth can yield images with the fasci-nating resolution of 10-5 arcsec. Labeyrie has for the first time shown that it is possible to combine the Coude beams of two telescopes coherently.
Precise Measurement Of Pzt Mirror Movement Using Fft Method
Author(s):
Toyohiko Yatagai;
Masaya Kobayashi
Show Abstract
Recently smart algorithms for interferometric fringe analysis have been developed, including the fringe scanning or the phase shifting method, the subfringe integration method, the FFT method and so on. Some of them cover the measurement ranges from 1/1000 wavelength to 10 wavelength with very high accuracy and repeatability.
Measurement Of The Mean Surface Velocity Of River Flow By Use Of An Optoelectrical Speed Sensor
Author(s):
Yasumasa Itakura;
Shin-ichi Taniguchi
Show Abstract
An image-velocity sensor with a parallel-slit reticle, a kind of spatial filter, is useful in measuring a surface velocity of a flow with rapid variations, such as a river flow') or a debris flow z). As well known, the image-velocity sensing is made use of the fact that the center frequency of the output electrical signal of the sensor is propotional to the surface velocity of the flow.1 The modulation of the output signal corresponds to the change of light intensity transmitted by the reticle, on which the focused optical image of the flow-surface is moving. Owing to the random distribution of brightness of the flow-surface, the output signal of the sensor is a stochastic signal. Accordingly, the main subject of this sensing is to extract the mean frequency of the output signal with randomness.
Measurement Of Position And Shape Using An Optical Fiber And A Frequency Modulated Semiconductor Laser
Author(s):
Hajime Hattori;
Takashi Takeo
Show Abstract
The analytic method of variable density image is generally used to recognize the shape of an object by visual processing. On the other hand, by using the data of the distance from the object, the accurate sampling of the shape which is independent of the contrast between objects and others is realized and the shape recognition is simplified. Therefore, the effective method for measuring a distance is required in fields of computer aided design and automatic measurement. Recently, the measurement of a distance using the principle of triangulation and the laser beam has been put to practical use. 1)
1-D Mark Direction Sensing Method With Parallel Mirror Tunnel For 3-D Position Measuring System
Author(s):
Masanori Idesawa
Show Abstract
Optical position measuring methods can provide an effective tool for non-contact measurement of shape, deformation, movement and so forth. Many of them are based on the trianguration in the wide sense. In order to remove the correspondence problem in the triangulation, light beam projecting method has been used widely. In the light beam projecting method, surface of an object to be measured is swept by a bright spot and image positions of the bright spot are detected by the several mark position detecting apparatuses. Then the 3-D position of a bright spot is determined based on the principle of triangulation. In this method, the measuring accuracy of 3-D position is influenced considerably by the detecting accuracy of image position on the observation plane.
Analysis Of Rotating Component Strains Using Pulsed Espi
Author(s):
Richard W.T. Preater
Show Abstract
A large proportion of the experimental stress analysis performed is carried out under laboratory conditions. A non-contact method of analysis which may be used under service operating conditions, requiring only minor component surface preparation and little or no plant shut-down, is therefore particularly attractive. Electronic Speckle Pattern Interferometry ( ESP') , a technique for the measurement of in-plane displacements on static components, was pioneered at Loughborough University by Butters and Leendertz 1). Using a pulsed laser with a pulse width of 20 ns in place of the c/w laser will not only remove environmental vibration of the system but will also freeze component movement and widen the scope of the technique to dynamic applications. The development of pulsed laser ESPI for the analysis of rotating component strains is being undertaken at The City University.
Image Transmission And Self-Oscillation In An Active Phase-Conjugated Ring Resonator Using BaTiO[sub]3[/sub]
Author(s):
T Tschudi;
H Klumb;
T. Kobialka;
A Herden;
F. Laeri;
T H Darmstadt;
J. Albers
Show Abstract
Applications of active feedback in optics have been discussed by several authors. For example cohe-rent optical systems have been proposed for analog optical computing /1/. Recently progress has been made in the field of holographic associative memories /2/ and several coherent optical feedback configurations have been realized /3/. So far in those experiments the apertures were limited in diameter as well as angle and also the achieved amplification factors were not suitable enough for applications. In our work we studied a feedback system with ring structure together with photorefractive amplifiers. An increase of the space-bandwidth product of former systems was realized with the use of the aberration compensating properties of the phase conjugating element. Moreover this phase conjugating element allowed a gain in the feedback loop of > 50. We studied further possibilities of incorporating even higher gain in the loop (up to several thousands). Both amplifier types were realized with photorefractive crystals of BaTiO3 /4,5/. Injection of a spatially modulated beam into this active feedback system causes image bearing os-cillation. Experimental results concerning image transmission and self oscillation are reported.
Optical Phase Conjugation With Liquid Crystal Light Valves
Author(s):
E. Marom;
U. Efron
Show Abstract
Optical phase conjugation' has been extensively investigated due to its capability of generating a beam whose wavefront has an envelope proportional to the complex conjugate of another beam and which propagates in a direction opposite to the first one. Such beams are generated primarily by four-wave mixing processes 2 or by using deformable mirrors. In the latter method, some combination of a wave front sensor and a deformable mirror is used to imprint the spatial phase modulation obtained from the wavefront sensor onto the deformable mirror in a closed loop operation. The deformable mirror action can be achieved either by mechanical means3 (piezoelectric activation) or by refractive index modulation.4
Opto-Optical Switch With A Spatially Modulated Gain Medium
Author(s):
I. Golub
Show Abstract
The diffraction of light by periodic structure results in light deflection and modulation and is the basis of many optical devices.1 Periodic structures due to periodic refraction index variation produced by optical beam interference are of particular interest. In the case of a gain modulated grating the diffraction beam intensity may exceed the incident beam intensity. In the present work Bragg scattering off a spatially modulated gain grating, which is the basis of a distributed feedback dye laser (DFDL) operationh, is used to construct a light controlled optical switch.
Generalized Large Signal Theory Of Phase Conjugation In Four-Wave Interactions
Author(s):
C. J. Roberts;
H. Hsu
Show Abstract
Large signal analysis of phase conjugation in nonlinear four-wave interactions has been described by H. Hsu [1] for the special case of a forward pump which is backward reflected to provide the counterpropagating pump. This theory provides an explicit mathematical description of four-wave interaction which is valid not only below the threshold of oscillation, but is also valid above the oscillation threshold where the undepleted pumps approximation of small signal theory breaks down. For this paper, the analysis has been generalized to encompass two separate counterpropagating pumps with an independently variable ratio of incident intensities. Thus a more thorough description of the interaction process. is provided, allowing broader application.
Lightwave Interaction In Space-Time Periodic Anisotropic Media
Author(s):
Katsu Rokushima;
Jiro Yamakita;
Shizuo Mori
Show Abstract
Periodic dielectric structures play an important role in applications such as deflectors, filters, switches, modulators and many other devices in integrated optics. A rigorous analysis of wave interaction in an anisotropic medium with tensor permittivity which is modulated periodically with respect to space and time is presented as an electromagnetic boundary value problem. Such a type of structures exist in a birefringent crystal traversed by a traveling acoustic wave. Similar space-periodic structures are also induced in an anisotropic slab waveguide by a voltage applied to interdigitated electrodes over the waveguide. Because of the complexity of the problem, the general periodic anisotropic media have been analyzed only by approximate methodsl),2) that often require a priori accurate result against which the approximation can be judged. The present method applies to any anisotropic lossy or lossless media, any polarization of the wave and any orientation of the grating vector in three dimensions. The wave propagation in such media is described by coupled-wave equations in a unified matrix form and the general wave characteristics can be obtained straightforwardly by systematic matrix calculations in any arbitrary level of accuracy. Numerical examples of both scattering and guiding properties peculiar to anisotropic waveguides are given.
High-Resolution Astronomical Imaging By Photon-Counting Triple Correlation Techniques
Author(s):
G. Baier;
K. H. Hofmann;
D. Schertl;
G. Weigelt
Show Abstract
Speckle masking1-4 is a triple correlation method that can overcome image degradation caused by the atmosphere, by telescope aberrations and by image motion of the speckle interferograms (guiding errors etc.). True images are obtained since it is possible to reconstruct both the modulus and the phase of the object Fourier transform. In other words, speckle masking is a solution of the phase problem in speckle interferometry.5 Other speckle methods are described in Ref. 6.
Direct Phase-Gradient Estimation For Stellar Speckle-Image Reconstruction
Author(s):
G. J .M. Aitken;
R. Johnson
Show Abstract
The primary problem in reconstructing diffraction-limited stellar images from their measured spatial spectra has been the accurate determination of phase. Modulus is readily obtained by means of the speckle-interferometric processing [1,2] of a large number of short-exposure speckle images. While the severity of atmospheric perturbations precludes the direct measurement of phase, the gradient of the phase can be accurately estimated, and then integrated to obtain the phase. The Knox-Thompson (KT) algorithm [3] approximates the phase gradient by computing the 2-D array of phase differences between adjacent spatial-frequency components. The phase-gradient (PG) process [4] described here determines the true phase gradient directly from the series of speckle images, and gives better performance than the KT process at low light levels.
Two-Dimensional Phase Retrieval Using The Fourier Series Expansion
Author(s):
N. Nakajima
Show Abstract
The phase-retrieval problem is of importance in areas of diverse application such as imaging through the turbulent atmosphere, x-ray crystallography, and electron microscopy. Various studies of the phase-retrieval method have been performed. Previously we presented that a phase distribution at the Fourier-transform plane of an object in one dimension can be retrieved by solving linear equations consisting of unknown coefficients in the Fourier series expansion of the phase and two moduli obtained with and without the exponential filter at the object plane.1) In this paper it is shown that a two-dimensional phase distribution can be also retrieved by using the Fourier series expansion and the algorithm2) for applying the one-dimensional method to the two-dimensional case. The validity of the present method is shown in computer simulations, reconstructing a two-dimensional object function.
Heterodyne Sensors Using Retardation At- Total Reflection --Displacement Sensor-
Author(s):
T. Yoshino;
T. Hashimoto
Show Abstract
Noncontact and high sensitivity are the most important abilities of optical metrology. To achieve high sensitivity interference systems are most usually used, but they are generally unstable. In this paper we present a new optical sensing scheme which can sensitively and stably measure various quantities.
Spectral Analysis Of The Partially Coherent Transfer Application To Linewidth Measurement On Wafers
Author(s):
D. Charraut;
D. Couiljon;
G. Bou Debs;
M. Guillaltme;
J. L. Buevoz;
N. Alcouffe;
P. Livrozet
Show Abstract
The need of measuring the linewidths on wafers more and more precisely imposes the improvement of the optical methods like microscopy by taking into account the various parameters which define the system. In this way, several techniques have been developed in order to simulate the transfer with accuracy (1,2). This modelling allows one to carry out comparative methods, simulation-experiment, for retrieving the desired object parameters.
Digital Phase-Shifting Photoelasticity
Author(s):
F W. Hecker;
H. Abeln
Show Abstract
Digital phase-shifting photoelasticity 1)2) can be regarded as an extension of recently introduced computer-aided phase-shifting methods, the objective of which is the detection of one phase (e.g. 3)4)), to a two-phase problem. The two phases governing, in a general case, intensity distributions of photo-elastic patterns of planely stressed bodies are: relative retardation S(xl,x2), which is related to the difference of local principal stresses, and isoclinic parameter a(x1,x2), which describes the angular position of local principal axes belonging to principal stresses ai ?ooli. It is known from photoelastic point methods (compensation and ac-phase measurement techniques5)) that phase-shifting of photoelastic patterns is achieved by independent rotation of two polarizing components of a polariscope.
Reticule Scanned And Pulse Modulated Laser Beam Spatial Coordinate System Design
Author(s):
Ming-Wen Chang
Show Abstract
Projectiles as large as space vehicle and as small as cannon projectile have some way to communicate with their ground station or launcher. Presented is a simple way to generate a modified polar coordinate in space. A projectile can sense its position in the spatial coordinate very easily.
High Accuracy Alignment And Range Measurement
Author(s):
J. Ojeda-Castaneda;
P. Andres;
E. Jara
Show Abstract
Coarse gratings with unit mark-space ratio (tcnu:ii rulings) are suitable masks for detecting lateral or longitudinal displacements.
Fluctuations In Phase-Conjugate Fabry-Perot Resonators
Author(s):
Ari T. Friberg;
Rainer Salomaa
Show Abstract
Recently a host of devices have been discovered in which resonators containing nonlinear phase-conjugating elements play a key role.' Examples include improved laser-cavity designs, new types of interferometers, and associative memories for image processing and optical computing. The importance of the phase-conjugate mirrors (PCM) in many of these constructions stems from their inherent capability of real-time distortion correction with fully coherent waves.2 Phase-conjugate resonators also exhibit several nonlinear features such as bistability, self-oscillations, and chaos.
Time Domain Operations Using Degenerate Four-Wave Mixing
Author(s):
M. Piche;
C. Pare;
P. A. Belanger
Show Abstract
Degenerate four-wave mixing (DPW) has found a variety of applications in optics such as phase conjugation, adaptive optics, image processing and interferometryl. These applications involve the spatial properties of this nonlinear process. O'MEARA et alt have reviewed other applications exploiting the temporal properties of DFWM, such as pulse reshaping, optical gating, temporal convolution and compensation for pulse spreading effects. In this paper, we describe the following two processes based on the spatiotemporal properties of DFWM: conversion of frequency modulated to amplitude modulated signal; conversion of a short laser pulse in a continuous laser beam.
Optical Feedback By Four Wave Mixing In Optical Processing Systems
Author(s):
Xinbing Liu;
Jian Wang;
Jianquan Yao
Show Abstract
The advantage of optical signal processing and computing is mainly due to its two-dimensional complex computing ability with the fastest speed. Of computation algorithms, quite a few are iterative or recursive, such as vector or matrix multiplication over a given matrix for many times, and the computation of derivatives of much high order, etc. These algorithms are also suitable for optical computing . To perform iterative algorithms, the output from a computation step reenters the system as the input for the next step, therefore a feedback loop is needed. Many optical signal processing systems have spatial light modulators that are electrically addressed, and the photon-to-electron and electron-to-photon conversions reduce the processing speed and increase the system complexity. In this paper we propose an all-optical signal processing system for performing the iterative algorithms by using a four wave mixing material which introduces a feedback loop in the system. We believe that this system may also be used as an optical two-dimensional dynamic memory device.
Observation Of Optical Wave Phase And Wave-Front-Correcting In Photorefractive Two-Wave Nixing
Author(s):
Xu Kai-Ying;
Xu Ke-Bin;
Hong Jing
Show Abstract
Recently,trasient and stationary beam coupling in two-wave nixing using photorefractive crystals and its applications such as coherent light amptification",vibrationat analysis", and self-oscillation" have attracted such attention. Chiou at al." reported the experimental results on the absence of phase cross talk in photorefractive two-wave aixing.But little attention has been paid to the observation of the coupled optical wave phase variations affecting the quality of images in photorefractive two-wave nixing.
Squeezed States
Author(s):
Bernard Yurke
Show Abstract
Recently a number of laboratories have demonstrated the generation of squeezed light, a new kind of light which in some of its aspects exhibits less quantum noise then coherent light. Here a description will be given of how such light is generated and detected. With the successful generation and detection of squeezed light by a number of laboratories1-5 a new degree of control over the quantum statistics of light has been achieved. Light can now be generated which, in some of its aspects, has less quantum noise than coherent light. Such light may find applications in optical communications and in sensitive and precision measurement. Here a description will be given of how squeezed light is generated and detected.6-8 The discussion will be restricted to what is called "quadrature squeezing". The electric field operator for a single mode of the electromagnetic field can be written in the form
Localisation Of Photon States In Quantum Optics
Author(s):
E. R. Pike;
Sarben Sarkar
Show Abstract
Non-classical light sources are now being developed in more and more laboratories. Their noise reduction properties are potentially important for technology. Examples are squeezed and antibunched light sources. It is tempting to picture in some of these processes single photons flying through space. In non-relativistic quantum mechanics it is easy to discuss the properties of particle localisation in a general context without recourse to a particular experimental configuration. A position operator exists and the localised states are just the eigenstates of this operator. The situation in relativistic quantum mechanics (or field theory) is not as straightforward. The photon is relativistic and it has the addi-tional property of being massless. It has no position operator associated with it. Yet, nevertheless, it is possible to pose the question of finding a generic construction for a wave packet for the photon which is localised as far as possible in some (imaginary) box in space. The difficulty of the construction follows from the fact that in an electromagnetic wave the polarisation is perpendicular to the direction of propagation. Thus we need to construct a vector field which is localised and has this transverse property related to the masslessness of the photon.
Photon Statistics Of Visible Laser Diodes
Author(s):
R. G. W. Brown;
R. Grant
Show Abstract
Until recently, HeNe and Ar+ visible CW output gas lasers in TEMJ mode have been standard devices for photon correlation measurements in the study of macromolecules and velocity1). We have examined in detail the photon statistical performance characteristics of some visible output CW laser diodes as alternative lasers for such studies2).
Determination Of The Inner Scale Of Atmospheric Turbulence Through Laser Beam Wandering
Author(s):
A. Consortini;
K. A. O'donnell;
G. Conforti
Show Abstract
The inner scale of atmospheric turbulence is important in atmospheric optics and in particular in laser propagation. Values of the inner scale can be obtained through measurements either of differential angle-of-arrival fluctuations1,2) or of intensity fluctuations3,4)of laser radiation propagated through the atmosphere. Here we propose a method to determine the value of the inner scale based on measurements of laser beam wandering. Laser beam wandering has the advantage of a higher sensitivity as compared with differential angle-of-arrival and seems particularly attractive over short paths. In addition, unlike intensity fluctuations, beam wandering is also sensitive to anisotropy of the turbulence.
Effective Radius In Grin Lenses With Revolution Symmetry
Author(s):
E. Acosta;
J. R. Flores;
C. Gomez-Reino;
J. Linares
Show Abstract
When a GRIN lens is illuminated with a point source, losses are caused when the emitted light is restricted by the effective radius (or equivalently, the effective numerical aperture) of the lens. Our purpose is to find a general expression for the effective radius of GRIN lenses with revolution symmetry.
A Comparison Between Toroidal And Conic Surfaces That Best Fit An Off-Axis Conic Section
Author(s):
O. Cardona-Nuilez;
A. Cornejo-Rodriguez;
R Diaz-Uribe;
A. Cordero-Davila;
J. Pedraza-Contreras
Show Abstract
Since the off-axis conic surfaces in optics have played an important role in the construction of spectometers, concentrators, etc; and as a continuation of the work to find the surface that best fits an off-axis conic section, but that also can be constructed by conventional neans,we present a similar method to the one developed already for conics 1, but now for the toroidal surfaces. Also a comparison is made between the fittings of conics and toroids.
Process Of Microptics
Author(s):
Kenichi Iga
Show Abstract
In this paper. first. recent progress of microoptics will be reviewed. Then we Look at some of applied microoptic systems for lightwave communications. Laser memory disc systems. and electrooptic applications. Two-dimensionally arrayed lightwave components by the use of planar microlenses will be included.
Absorption And Excitation Spectroscopy Of The Vibronic Laser KZnF[sub]3[/sub]:Co
Author(s):
D, J. Lockwood;
H. J. Labbe
Show Abstract
Tunable lasers in the near-infrared spectral region have attracted considerable attention recently because of potential applications in, for example, photochemistry, spectroscopy and optical communications. Vibronic solid state lasers form one class of tunable laser that are actively under development at present. We present here results ,of a detailed optical study of the vibronic laser material KZn1-xCoxF3' which has been demonstrated') to exhibit tunable single-frequency continuous-wave laser action in the wavelength range 1.75 to 2.15 μm.
Picosecond Transient Spectroscopy Of Luminescence In Semimagnetic Semiconductors
Author(s):
H. Fujisaki;
Y. Oka;
K. Nakamura;
I. Souma
Show Abstract
The dynamics of luminescence of exciton interacting with d-electron of the Mn ions have been studied by measuring transient behavior of luminescence with excitation of Laser pulse of mode-lock system at low temperature and magnetic field in semimagnetic semiconductor of Cd1-xMnxTe, Cd1-xMnxSe (x;0.1 /. 0.6).
Off-Resonance Behavior Of Atomic Interaction With Cavity Fields Of Arbitrary Detunings
Author(s):
D. L. Lin;
Xiao-Shen Li
Show Abstract
The Jaynes-Cummings (JC) model has been studied extensively because of its simple and realistic representation of the dipole interaction between an atom and the quantized radiation field. It exhibits, without perturbative expansions or statistical decorrelations, many quantum mechanical effects in the case of strong or weak interaction, long or short time regime, on or off the resonance. The model is extended to a three-level atom for the investigation of physical phenomena associated with two-photon processes.
Laser Raman Spectroscopic Studies On 2-Amino 4 -Methyl Pyrimidine
Author(s):
S. Mohan;
Feridoun Payami
Show Abstract
Amino acids are of great biological significance as they form basic constituents of protein. Although N-hetrocyclic molecules like pyrimidine, cytosine, uracil and their derivatives are of considerable biological importance, no complete spectroscopic data are available in the literature. The study of their vibrational spectra is important to get information on their molecular conformation. Due to their complexity and low symmetry it is difficult to interpret the spectra of such biological molecules with only infrared or Raman spectroscopy. By keeping this in mind, the study of Laser Raman spectrum of 2-amino 4-methyl pyrimidine has been undertaken in the present investigation in addition to infrared spectrum. Since all the fundamentals are active both in Raman and Infrared spectra, the present study aims to assign all the vibrational fundamentals of this molecule.
A "Splitting Source" Model For The Statistics Of Irradiance Scintillations
Author(s):
N. Ben-Yosef;
E. Goldner
Show Abstract
The problem of the probability density function (PDF) of the irradiance fluctuations of an electromagnetic wave propagating through a turbulent atmosphere is being investigated for several decades. Tatarskii and deWolf succesfully investigated the cases of weak and very strong turbulence. The intermediate regime still imposes a number of physical questions in spite of considerable progress in the last few years. Many models have been proposed and studied [1-7], none is complete and some of them impose difficulties in understanding the physics of the process.
Acousto-Optic Coherence Control And Its Application To Image Shaping
Author(s):
Y. Ohtsuka;
S. Nakamura;
K. Itoh
Show Abstract
The coherence control of object illumination is of particular interest for the improvement of the image quality of a small-scale object. In the past, however, it was almost impossible to get at a practically available, strong, coherence-controllable illumination source. In this context[1,2] acousto-optic coherence modification using a laser beam has been examined to yield a spatially coherence-controllable illumination. The intent of this paper is to present its principle and to see how the image reshaping of an edge object is made, depending on the illumination condition of spatial coherence.
Photon Noise Reduction In Phase Sensing Interferometers
Author(s):
E. Bernabeu;
L. L. Sanchez-Soto
Show Abstract
The search for gravitational radiation has driven important improvements in a variety of technologies for detecting very weak forces. These improvements have renewed the interest for the problem of quantum noise reduction. The use of squeezed fields was considered by Caves' and Bondurant and Shapiro2, who showed that a squeezed state interferometer requires substantially fewer photons than does a conventional (coherent-state) interferometer to reach the standard quantum limit. This note reanalyzes the problem, pointing out the importance of the coherence properties of the squeezed fields for the evaluation of photon noise reduction3.
Second Harmonic Generation Using Fluoride Copolymers And Its Control By Dc Field
Author(s):
Heihachi Sato;
Kazuo Oka;
Takashi Yamamoto
Show Abstract
Organic polymers are recently becoming important for harmonic generation, Raman scattering, down conversion and so on. 1) Theirpiezo- and pyroelectric properties have been extensively studied, though, their nonlinear behaviorpckl as second harmonic generation(SHG) has been li4 mited only to PVDF polymer by McFee and Bergman et al z,3) and VDF/TrFE copolymer by one of the authors.) In the present paper we shall report new SHG observation in vinylidene fluoride/tetra-fluoroethylene(VDF(TeFE)copolymer using a pulsed Nd : YAG laser, in comparison with that of VDF/TrFE copolymer. Additionally, the poling-field dependence on the SHG output power and its control by dc electric field will be also experimentally demonstrated with some discussions. 11
Theoretical And Experimental Study Of Surface Enhanced Second Harmonic Generation From Silver Gratings
Author(s):
J. L . Coutaz;
D. Maystre;
M. Neviere;
R. Reinisch
Show Abstract
Gratings are known to be very efficient optical couplers to excite surface plasmons (SP). The resonant excitation of SP increases the electromagnetic (EM) field amplitude at the metal surface. This leads to an enhancement of the efficiency of various surface nonlinear (NL) optical effects, such as Raman scattering [1], luminescence of metals [2], second harmonic generation (SHG) [3]...
Properties And Applications Of Photorefractive Crystals
Author(s):
Gerald Roosen;
J. P. Huignard
Show Abstract
Coherent optics offers very unique advantages for information processing and transmission with a high parallelism and a strong data rate. The implementation of these idea requires non linear materials permitting efficient interactions between optical beams.
Microscopic Holographic Ihterferometry Of Optical Fibers And Torus Abel Inversion
Author(s):
S. Himeno;
M. Seki;
Y Hamamoto;
H Mochizuki
Show Abstract
This paper describes microscopic holographic interferometry of optical fibers and a new numerical method for determining refractive index profiles. In end-on(axial) holographic interferometry of an optical fiber,we must polish the end-planes optically flat. So,we bent the optical fiber toroidally and measured it by injecting a laser beam toroidally without polishing the end-planes. Furthermore,we developed a numerical method,'TORUS Abel Inversion',for determining refractive index profiles of the whole optical fiber plane.
The Role Of The Form And Position Of The Detector In Confocal Imaging Systems.
Author(s):
T. Wilson
Show Abstract
The optical sectioning property of confocal imaging systems is perhaps a more important feature than the enhanced lateral resolution which these systems possess. This property permits the in-focus imaging of sections of a thick object. The introduction of axial scanning leads to the ability to produce high resolution images with arbitrary, tunable, depth of field. It is also possible to operate the system as a non contacting surface profilometer. The optical arrangement is shown in the figure and the principle of the depth discrimination is shown by the dashed lines.
Superresolution In Confocal Imaging
Author(s):
Z. S. Hegedus
Show Abstract
The resolving power of an image-forming instrument is limited by the highest spatial frequency transmitted by the system. In a more traditional definition the resolution limit is determined to the shape of the point-spread function of the instrument. Diffraction does not constitute a fundamental limit to resolution. For example, when the image is built up point by point, the contribution of each image element can be separated from the other in time, so that, in principle, more information can be obtained about the spatial characteristics of a stationary object. This has been demonstrated in near-field optical scanning microscopy, where a tenfold resolution gain has been achieved over the half-wavelength limit'.
Determining The Phase Function In Two Dimensional Fourier Spectrum
Author(s):
Xu Ke-shu;
Xu Xiang-dong
Show Abstract
By using a Fourier-optical system with two orthogonal polarization channels we have separated the real part and the imaginary-part and measured the phase function of the Fourier spectrum. For a real asymmetrical object function f(x,y);(Fig. la), its Four-ier spectrum is a complex function of the spatial frequency and the phase function is the goal for us to measure experimentally. First, related to the original function f(x,y) we construct a new function f'(x,y) (Fig. lb) which is symmetrical with respect to the origin of the coordiate axes
Information Capacity Of Opto-Electronic Transducers
Author(s):
Yajun Li
Show Abstract
This paper deals with the question of how to evaluate the performance of opto-electronic transducers for precision dimensional metrology, such as laser interferometers and linear scale systems, etc. For this purpose, the opto-electronic transducers are considered as a kind of communication system, and the concept of information capacity is used to summarize the basic technical data of the transducer. These data are usually listed in the operation manual of a transducer to show its warranted performance in various aspects.
Influence Of Non-Uniform Amplitude On The OTF
Author(s):
C. S. Chung
Show Abstract
The optical transfer function (OTF) can be calculated from the design data, but their calculations have so far mainly restricted to the cases where the image forming wavefront is of uniform amplitude. In practice, this is not always the case, because the real amplitude can vary according to a polynomial in the pupil coordinate, which will be analogous to the wavefront aberration polynomial, and can vary with a radial gaussian distribution as in the intensity distribution across a laser( 1?eam Recently, a considerable amount of work has been carried out about this problem But the mathematical difficulties of evaluating the OTF in the general cases of an aberrated optical system with any kind of transmission function in exit pupil have limited the analytical results obtained in this field.
Fringe-Contrast Interferometry
Author(s):
Marek J. Matczak
Show Abstract
The name "FRINGE-CONTRAST DITERFEROMETRY" /FCl/ is proposed for such measuring techniques and interpretation methods which are based on information contained in the fringe-visibility distribution in interference images. In general, the fringe-visibility distribution depends on kind and direction of object illumination, shape and microstructure of object surface, such parameters of imaging system as focusing distance, aperture size, as well as shape and orientation of diaphragm, and - on differences between two states of object surface being compared using an interferometry technique. The early papers on this subject have concerned the case of imaging system focused exactly on the object surface, with circularly [1,2,3] and arbitrarily Du shaped diaphragm. In this case, the fringe visibility depends on the differences described only by the displacement components perpendicular to viewing and/or illumination directions. The recent works [5,6,7, and unpublished yet] have been based on the general equations describing the fringe visibility formed by imaging system focused on the object plane which is arbitrarily situated with respect to the object surface. These equations allow to apply FCI to arbitrarily-shaped object surfaces for automated determination of the shape of object surface, the fringe-order distribution, 3-D dis-placement field, as well as the surface-strain and rotation tensor fields - directly from fringe-contrast measurement, without differentiating the displacement field.
Power-Dependent Attenuation And Power Transfer Effects In Optical Nonlinear Waveguides
Author(s):
Z. Jakubczyk;
H. Jerominek;
S. Patela;
R. Tremblay;
C. Delisle
Show Abstract
We present a theoretical analysis of some new properties of TE waves in waveguides consisting of an optical linear thin film deposited onto the surface of a substrate exhibiting both positive and negative nonlinearities at two different wavelengths. The semi-infinite substrate is characterized by an intensity dependent refractive index ns= nso+ n2S, where S is the local power density and n2 is the nonlinear coefficient. The data set used in our calculations concerns a particular structure consisting of a film of Corning 7059 glass deposited onto the surface of a Schott GG 495 glass filter. Color filters made with glasses doped with crystallites of the mixed semiconductor CdSxSel_x exhibit third order nonlinearity with n2 of about 10-14m2/W. It is also known1 that the sign of the nonlinearity in these glasses changes in the vicinity of a band gap. The material parameters for positive nonlinearity at λ = 0.4765 pm and negative nonlinearity at λ= 0.4880 mm are the following: Corning glass film refractive indices nf= 1.597 and 1.595; substrate refractive indices nse 1.573 and 1.569; imaginary parts of dielectric constant of the substrate c" = 2.8 x 10 and 6.5 x 10-5 respectively.
Important Cultural Properties Recorded By Means Of Holography
Author(s):
Hidetoshi Katsuma;
Koki Sato
Show Abstract
There are many important properties in Japan. A teacup for tea ceremony in ancient time is shown in Fig.l. This one is easily recorded on Fresnel and Lippman holograms. Especially,color Lippman holography1)12) is good example. But wooden startue of Buda in Fig.2 is not removed to record. Reflection holographic stereograms(R.H.S)3)are used for one. This R.H.S is very interesting because of this ability to render a wide renge of input formates,such as photographic,video,computer-graphic,and movie images.Our experiments are made this R.H.S into color one.Red image is necessary to use He-Ne laser, blue and green is Ar laser.The flat type of R.H.S4) is useful for this experiment.To repair these properties will be remarkable progressive advanced by making use of computer-graphics and this R.H.S.
Propagation Of The Spectrum Of Light In The Paraxial Domain
Author(s):
Zagorka Dacic;
Emil Wolf
Show Abstract
It was shown not long ago that the normalized spectrum of light generated by a secondary, planar quasi-homogeneous source will, in general, change on propagation1,2. In this paper we study how the normalized spectrum changes throughout the paraxial domain.
Direct Measurement Of The Nonlinear Refractive Index Of Sf 6 Around 10 µm
Author(s):
Y. Beaudoin;
I. Golub;
S. L. Chin
Show Abstract
For many applications related to high power laser propagation such as laser isotope separation or parametric wave mixing, knowledge of the refractive index n in the infrared (IR) is very important to obtain maximum efficiency in these processes. We present here a simple technique to measure directly the nonlinear refractive index n2 of a molecular gas in the IR. We use CO2 laser propagation in SF6 as an example. SPE, is a well-studied molecule exhibiting nonlinear properties such as self-focusing (S.F.), self-defocusing (S.D.) and four-wave mixing of a CO2 laser radiation around 10.6 pm. However, n2 and the related nonlinear susceptibility x(3) of SF6 were derived from indirect experiments by measuring the reflectivity of phase-conjugated signall or from the self-focused beam diameter dependence on laser intensity2. In our case the technique allows to measure directly n2 and to tell the occurence of S.D. or S.F. without having to take into account intensity dependent absorption.
The Study On The Small Solar Heat Engine That Was Driven By The Segment Type Parabolic Mirror
Author(s):
Koro Shishido;
Masao Sugiura
Show Abstract
A small solar heat engine designed by the authors consisted of a small solar furnace and a Stirling engine; the fabricating apparatus for the parabolic mirror was reported in the last conference of 13th 'Ea") In this paper, the construction for this solar furnace and the efficiency of the Stirling engine are reported.
An Arrangement Of Apparatuses To Get Controlled Impact And Exact Triggering For Ruby Laser Holographic Interferometry
Author(s):
V. V . K . Karppinen;
T. Hartikainen;
H. Karppinen
Show Abstract
Ruby laser holographic interferometry is widely used in engineering measurements even in industrial environments. The pockel-cell of the resonator produces short laser pulses and double-pulses, too. These can be used to study the effect of impacts on examined structures. The only problem is suitable triggering of the laser synchoronized with the impact. As impact generators have been used pendulums, hammers and air guns for example. We have built an impact generator (Fig. 1.) based on the steel bullet coming from the rotational axis of the wheel. The triggering electronics have been built up, too.
Quantitative Analysis Of The Diffraction Efficiency And The Crrokinance Of Silver-Salim-Bleach:Nd Psecdochronatic Encoding
Author(s):
Jianing Hua
Show Abstract
For the quantitative analysis of diffraction efficiency of all kinds of grating modulation phase pseudochromatic encoding plates, the present paper initiates an elementary method whereby the diffraction efficiency of encoding plates of any picture can be figured out with the aid of compater.Qtantitativeliy, the paper analyzes the chromatic difference and metamerism of pseudochromatio encoding and therein are presented the results of quantitative analysis for the chromatic repeating, the chromatic resolving power of encoding and the chromatic characteristics of zereth-order and fist order diffrao-Um.
Holography Techniques In The Color Reproduction Of Two-Dimensional Images
Author(s):
R. Rodriguez-Vera;
L. R. Berriel;
A. A. Morales
Show Abstract
The two main problems in color holography have been the presence of cross talk images and the field of view reduction in the vertical direction of the holographic images. Techniques have been proposed in order to reduce these effects like recording of three holograms on the same holographic plate using diferents wavelengths, other make methods use of color masks and/or spatial filtering [1]. Other authors [2] reported a pseudocolor technique in which only one wavelength, has been used to record the hologram, the reference beams impinge the holographic plate at different angles, however in these methods the problem of a narrow field of view is still present. Tamura [3], using the two step rainbow hologram technique, recorded three holograms in the conventional way, using a rectangular slit. He uses this holograms as objects for a fourth holographic plate on which they are recorded using reference beams at three different angles. Tamura's technique requires only one wavelength and four holographic plates which give a good color image but it requires too much care and more than one holographic plate. In this paper we describe a holographic pseudocolor technique which is based on the recording of three image holograms on the same holographic plate, using a single wavelength He-Ne laser, and three reference beams at different angles. Fixing one of the angles of the reference beams the other two can be calculated in such a way that upon reconstruction with white light, each hologram is reconstructed in a primary color. Using a ground glass during the recording step, diffused laser light illuminates the object increasing this way the vertical vision angle. On the other side, the cross talk image problem is solved by coding the reference beams using diffusing screens. A hologram is obtained which gives a pseudocolor image, with colors very close to the real object's, but with loss in resolution.
Guided Waves In Symmetric Periodic Stratified Dielectric Media
Author(s):
Yi-Fan Li;
John W. Y. Lit
Show Abstract
In a previous paper, we presented general eigenvalue equations for both transverse-electric (TE) and transverse-magnetic (TM) modes in multilayer slab waveguides. Here, those formulas are applied to symmetric periodic stratified media. The results obtained are compared with those of Yeh et al,2 which were obtained by using matrix method. The eigenvalue equations for even and odd-modes are also obtained.
Thermal Expulsion As A New Mechanism For Optical Bistability In Prism Coupling Into Planar Wavegaides
Author(s):
P. Pirani;
V. Briguet;
W. Lukosz
Show Abstract
We investigated theoretically and experimentally a new type of cptical bistability (0B) in prism coupling into absorbing planar waveguides. Origin of this (B is the thermal expansion of the substrate (and the waveguiding film) and of the prism, due to heating by the part P = P of the incoupled power which is absorbed in the incoupling region. This expansion causes a reduction in the width d of the air gap between the prism coupler and the waveguide in the ompling region. Since the incoupling efficiency is a function of d, positive feedback, and therefore as, can occur. At the same input power Pa, the system has two bistable states, which differ in gap width d, in absorbed power Pa, and consequently in output (reflected) power PR. (see Fig. 1).
Phase Conjugation By Methylred Fixed In Gelatin Or Pmma Matrix
Author(s):
H. Fujiwara;
K. Nakagawa
Show Abstract
With a conventional degenerate four-wave mixing (um) configuration, the gelatin film containing fluorescein, erythrosin or eosin produces the phase conjugate CPC1 wave by not only the DFWM process but also the holographic process at the intensity of lower than 0.5 w/cm2 of light emitted by a cw Arion laser1). The holographic process differs from the DFWMprocess in the respect that light incident on a dye-doped film induces permanent photochemical changes in the absorption and/or the refractive index. The distinction between the two process is more clearly brought out in the response time of the PC wave by each process: the DFWM component with a fast response time of the order of milliseconds and the holographic component with a slow response time of the order of minutes2),3) Our aim is to demonstrate that a gelatin film containing methylreds can generate the PC wave only by the DFWM process, but a PMMA film containing methylreds can generate the PC waves by the DFWM and holographic processes.
Color Image Correlation: Principle And Application
Author(s):
E. Badique;
Y. Komiya;
N. Ohyama;
J. Tsujiuchi;
T. Honda
Show Abstract
Despite evidences from human vision research (1) that spatial and color characteristics of images are strongly related, the use of color for recognition purposes has received little attention. However,in the framework of the development of increasingly versatile machine vision systems, the introduction of the color feature seems to be a rather natural step. A color approach is obviously not always possible and justified and therefore we are interested in cases where color images are at hand and where recognition accuracy is more important than processing speed. In this work we extend the concepts introduced earlier (2) andpropose to find an optimal generalized color plane in which to carry out the correlation operation. The optimality is defined in terms of the maximization of the peak-to-deviation ratio in the correlation plane. As an application we consider the retrieval of the mucosal surface structure from stereo pairs taken through an endoscope.
A Least Square Filter For Color Image Restoration
Author(s):
Masuyoshi Yachida;
Nasaaki Ohyama;
Toshio Honda;
Jumpei Tsujiuchi
Show Abstract
A lot of researches have been done in the field of image processing, but most of them are mainly for monochromatic images and they have no attention on color informations. If they are directly applied to color images, they might produce different artifacts in each primary color images. So, we think, it is necessary to study the color image processing methods taking account of color informations of the images.
Holographic 3D Display Of Medical X-Ray Images
Author(s):
Jumpei Tsujiuchi;
Toshio Honda;
Nagaaki Ohyama
Show Abstract
A holographic stereogram synthesized from a series of ordinary photographs is very convenient to make a hologram of an object whose hologram is very difficult or impossible to take in conventional techniques. The most popular one is a cylindrical holographic stereogram with white light reconstruction known as multiplex hologram. Reconstructed images from the multiplex hologram seem very attractive to display 3D images because they are very bright and of wide viewing angle to be observed by many people at the same time. This technique is capable of displaying medical X-ray images in 3D, and offers many advantages to medical doctors.
A Fibre-Optic Based System For Chemical In Vivo Mapping Of The Human Body
Author(s):
B. Hougham;
R. S. Brown;
U. J. Krull
Show Abstract
In vivo chemical mapping of the human body could be very useful in the treatment of patients undergoing surgery such as heart surgery, with acute conditions such as hepatitis, or chronic conditions such as diabetes. Chemical mapping would be a continuous analytical profile of physical parameters such as blood pressure, chemical parameters such as pH, pCO2 and p02, simple molecules such as glucose and large biomolecules such as serum glutamate-oxoloacetate trans-aminase (SGOT), serum glutamate-pyruvate transaminase (SGPT) and billirubin. The advantage of a particular mapping strategy employing fibre-optic sensors is that all these different chemical signals arriving from different sensors can be multiplexed and detected concurrently. Although physical sensors for parameters such as temperature, pressure and blood viscosity have not yet found their way into routine use, those which employ fibre-optics do already exist. Fibre-optic chemical sensors (FOCS) have been developed for pH, pCO2, p02 and 3lucose (for review see Ref. 1). The existing FOCS utilize absorption, reflectance and fluorescence spectro-photometry. An integrated system for chemical mapping could utilize FOCS which exclusively use fluorescence probes which have a high signal to noise ratio and are sensitive to trace amounts of chemicals and biochemicals. One proposed strategy for detecting physiological analytes is the use of fluorescently labelled immunochemicals. These are useful in that the antibodies can be tailored to selectively bind almost any antigen conceivable (2) but are limited in that these reactions are mainly irreversible which is an important consideration for in vivo probes. A second strategy proposed is a receptor-based system (3). While agonist-receptor systems are slightly less selective than antigen-antibody systems, these reactions are reversible which is an important consideration for in vivo probes. Using existing FOCS and a new family of fluorescent chemical sensors that use evanescence, it is possible to multiplex different chemical sensors at different parts of the body to gain a more complete picture of the patient.
Protection Of Multimode Optical Fiber Communication
Author(s):
Chung-Yee Leung;
Cheng-Hao Huang;
I-Fan Chang
Show Abstract
One important advantage of fiberoptic communication is security. Compared with conventional electric cables, optical fiber cables are very hard to tap on information because no elctric or magnetic fields are generated from the cables. However, it is still possible to make an optical fiber to leak some of its power by peeling the jacket and bending the fiber or removing the cladding. Methods to pro-tect fiberoptic communication from tapping has been proposedl). In this paper we propose a new, simple but effective method bases on intermodal interference to protect multimode fiberoptic communication. The optical fiber detects any mechanical distortion of itself, which unavoidably occurs in an attempt to tap information. Although the lightwave carries both communication and security informations, we demonstrate that there is no degradation in communication quality.
On Collimation Of A Laser Beam
Author(s):
R. S. Sirohi;
M. P. Kothiyal
Show Abstract
1-3) Several schemes for testiag the collithation of a laser beam based on Talbot imaging and Murty shearing interferometer have been reported. We present here two variations of these techniques.
Pulse Density Modulation: Synthetic Formation Of Binary Images And Holograms
Author(s):
M. Broja;
S. Weissbach;
F. Wyrowski;
O. Bryngdahl
Show Abstract
A large portion of our world concerned with manipulation and communication of information has turned binary. A consequence has been hardware with improved SNR. A demand and interest for binary coding procedures has arisen from this trend. Several 1-0 schemes in electronics like PWM, PPM, and PCM have been extended to 2-D optical counterparts in a straightforward way. In contrast to these cases with equidistant sampling we will also discuss situations with nonequidistant sampling where the information is coded by the positions of the pulses in such a way that the two dimensions are inseparable. This implies that no constant carrier frequency is introduced. In pulse density modu-lation (POM) the pulse separations are inversely proportional to the local signal level. Characteristic for POM is that a large number of degrees of freedom exists. They have to be handled by the coding algorithm. We will show examples how these degrees of freedom can be coupled to certain directional properties of the 2-0 signal.
Laser Speckle Metrology Using Holo-Lens Imaging System And Its Application In Fracture Mechanics
Author(s):
Chandra Shakher;
G. Venkata Rao;
Heera Lal Yadav;
B. N. Gupta
Show Abstract
It has already been shown 1,2 that by using proper recording and playback geometries, almost diffraction limited performance in speckle metrology can be achieved over the entire object field which can be imaged by two hololens configuration. Because of the complexities encountered in closed form or numerical solutions in the area of theoretical fracture mechanics, carefully controlled experiment which can provide more accurate data is essential for validating the theoretical results. Therefore use of holographic optics in fracture mechanics has an edge over conventional optics. This paper concentrates on the study of crack opening problem, in a beam specimen having central edge crack subjected to three point bending (Fig.1), using focused plane speckle photography and two holo-lens imaging configuration. Fig. 2 shows the schematic of the typical imaging system used in the experiment. The lenses used in the experiment were all recorded using di vering spherical and plane waves. The recording and play back geometries are discussed elsewhere (See Ref. 2).
Inversion And Folding Shear Interferometers Using Holographic Optical Elements
Author(s):
V. Parthiban;
C. Joenathan;
R. S. Sirohi
Show Abstract
In the field of optical testing, the use of shear interferometers has a distinct advantage over other techniques due to the fact that the number of fringes in the interferogram can be controlled by changing the amount of shearl). Many schemes for lateral and radial shear interferometers have been proposed utilizing holo-optics2-4). In this paper, we propose two more schemes for shear interferometers using holographic optical elements.
Coherent Image Processing With Coupled Prisms
Author(s):
C. Bhan;
P. C. Mehta;
R. Hradaynath
Show Abstract
Total internal reflection phenomenon and coupled prisms through evanescent waves have been used 1] for a number of applications such as imaging of finger prints, surface profile measurement, beam splitting,waveguide coupling etc. We report here the results of experiments carried out to use coupled prisms in the context of several image processing requirements.
Some Advantages Of Using Scatter Plate Interferometer In Testing Aspheric Surfaces
Author(s):
Der-chin Su;
Toshio Honda;
Jumpei Tsujiuchi
Show Abstract
The scatter plate interferometer a simple structure and is very conventient for measuring the surface errors of a concave mirror. In this interferometer, unlike all the others, there is no one-to-one point correlation between the mirror to be tested and the scatter plate which acts as a beam splitter. Using this feature, we show that a scatter plate interferometer is more stable than any other interferometer. In addition, a new convenient method, which can realize the null test of aspheric surfaces, is proposed by some modifications of optical setup, without using any special optical elements.
Pulse Propagation In A Gaseous Laser Amplifier
Author(s):
V. Aboites;
G. E. Torres-Cisneros
Show Abstract
The propagation of a laser pulse through a gas amplifier is an important practical problem. In particular, in discharge-pumped gas amplifiers it is known that the amplification coefficient of the lasing medium is a function of the longitudinal and transversal coordinates inside the cavity. This is a consequence of practical aspects such as the position an shape of the electrodes inside the cavity [1]. Also, for long enough laser pulses, diffusion of the active centers take place during the amplification of the pulse.
A New Parameter In The ATR Technique For Optical Constants Determination
Author(s):
L. E. Regalado;
R. Machorro
Show Abstract
The Attenuated Total Reflection (ATR) method has shown to be a powerful tool for optical characterization of metal surfaces /1/. The effect of a double interface /2/ and the modification of surface electromagnetic waves (SEW) by very thin layers /3/ have also been studied using this technique.
The Lateral Waves In Anisotropic Optical Waveguide
Author(s):
M. Wabia
Show Abstract
The here considered anisotropic waveguide constitutes a two-dimensional, uniaxial structure with three anisotropic layers. The geometry of the system is shown in 3). The relative - permittivity tensors in the j-region (j = 1,2,3) of the guide coresponding to the optic axis in the x, z plane, are all of the following form...
Three-Dimensional Pseudocolor Reconstruction By Multislit Rainbow Holography
Author(s):
J. Wang;
Z.-M. Li;
J.-Q. Wang;
G.-G. Mu
Show Abstract
One very often needs to obtain a three-dimensional (3-D) image from serial two-dimensional (2-D) information of biological organs or tissues in biological research. Due to the invention of holography in the early 1960's, a large amount of information could be permanently and accurately recorded on t)plate. A real 3-D image could be displayed when the hologram was reconstructed. Thus, Redman ' predicted that a 3-D image could be synthesizing if 2-D projections of various depths of an object were holographically recorded. From then on, a number of holographically synthesizing techniques have been proposed. In this paper, we present a new experimental tecloqique, based on the one-step multislit rainbow holography proposed by P. T. S. YU and his colleagues2), of holographically synthesizing 2-D projections of serial sections at various depths into 3-D image.
Dwehmination Of Grain Size Distribution In A Silver Emulsion An Applied Problem In Inverse Optics
Author(s):
J. Wang;
J.-Q. Wang
Show Abstract
In addition to the extensively-studied problems in inverse optics, such as inverse scattering and phase reconstruction, there are some other problems that may be included in this field of study, the determination of grain size distribution in a silver emulsion is one of these. A microdensitometer is needed for the determination. The statistical properties of the emulsion transmittance T(x,y) are derived from that of the "combined" transmittance Ta(x4y) of the emulsion with the aperture function of the microdensitometer.
Depth Pseudocolor Of 3-D Scenes Using Image Holography
Author(s):
A. Olivares-Perez;
L. R. Berriel-Valdos;
A. A. Morales
Show Abstract
The color code obtained during image hologram reconstruction is a function of the source's spectral emission, the colour distribution obtained depends on the particular geometry used on the recording step. The recording geometry employed in this work involves several reference beams, at different angles, and sectional illumination of the object, using a slit during the recording step. We shall analize the parameters involved in recording 3-D scenes such that a color depth code is inscribed in the hologram.
Adaptive Real-Time Pattern Recognition Using Liquid Crystal Televisions
Author(s):
F. T.S. Yu;
S. Jutamulia;
T. W. Lin;
R. Yelamarty;
Don A. Gregory
Show Abstract
Recently many applications of the liquid crystal television (LCTV) to real-time signal processing have been reported. A basic description of the application of the LCTV to real-time pattern recognition was first reported by Liu et al. [1]. Gregory [2] later also showed a successful space invariant correlation using a LCTV as a spatial light modulator. Both methods were based on the use of a VanderLugt type complex matched spatial filter. The joint transform architecture is an alternative approach to optical pattern recognition [3]. In this paper, a new implementation of the real-time monochromatic and polychromatic joint transform correlator architecture using inexpensive LCTVs will be discussed.
A Two-Beam-Compensation Of The Error Of The Laser Alignment
Author(s):
Yi -mo Zhang;
Fu-gen Zhang
Show Abstract
By its temperal characteristics, the error of the laser alignment could be divided into two parts, the random fluctuation with high frequencies and the slow drift. The former is originated from the atmospheric turbulence and can be alleviated by means of low-pass-filtering and/or many-time-averaging since its variance with time is unbiassed as well as random and of high frequencies. The latter results from the thermal deformation of the laser and of other related optical devices in the alignment system, and the change in the gradient of the atmosphere refraction index. Up to now, many methods to eliminate the error from the thermal deformation have been suggested and some satisfing tesults have achieved, however, there is no effective method to the error from the change in the gradient to be publicated. In this paper the authors present a method to synthetically alleviate the error from both the thermal deformation and the index gradient. See figure 1. The light beam from the laser is, first, collimated, then splitted into two parallel beams whose intensities are approximately equal. It is apparent that the drift of one beam caused by the thermal deformation is theoreticall identical to that of the other, and that the drift of one beam by the index gradient is approximately identical to that of the other when the distance between two beams is small enough. Therefore, if we choose any one of the two beams to be reference beam whose drift can be detected and the other to be alignment beam whose drift can be known through the former, the error of alignment caused by drift could be eliminated. In order to verify this a tentative experiment has been carried out.
Dye Laser Pulse Compression And Multi-Peak Phenomenon
Author(s):
Zhou Dingwen;
Zhang Yimo;
Wang Xiaochun
Show Abstract
Using stimulated Brillouin scattering (SBS) to compress the laser pulse became more attractive in the past several years. With this method, the pulse width of ruby laser and double-frequency YAG laser output can be squeezed efficiently[1]-(3]. We used the 5600X output pulse from a dye laser as the pump beam for SBS, the dye laser is pumped by a double-frequency YAG laser. The compressed pulse of SBS was obtained and the compression ratio is approximately 20:1. In addition, the multi-peak process of SBS was observed as well. For explanation of this phenomenon, M.J.Damzen[4] suggests that the multi-peak effect is caused by the coupling between SBS wave and pump wave. According to this explanation, the multi-peak should be depleted one peak after another. But it is contrary to our experimental result. Other authors[5] suggested that the main reason of the effect resulted from the amplifier and feedback of the laser. Unfortunatly this theory can not explain the situnation where no laser amplifier exists. In our opinion, this phenomenon is caused by the oscillatory character of the transient SBS process, when the squeezed pulse width is almost equal to the response time of the SBS medium.
Light Scattering Measurement Of Particle Size And Velocity Using Overlapping Optical Field
Author(s):
Yimo Zhang;
Gongwei Xie
Show Abstract
One of the most difficullties in the measurement of particles using Mie theory is the property of nonuniformity of the laser intensity distribution in the cross section of laser beam. Many techniques have been developed to obtain uniform optical field1)2),3),4). When these techniques are used much laser energy have lost and the optical field with high degree of uniformity is difficult to obtained. By using following novel Overlapping Optical Field Technique (OOFT) for measuring nonintrusively, simultaneously, and in real time, the size and velocity of particles, these weakness above can be overcome.
Enhanced Second Harmonic Generation In Corrugated Waveguides Linked With The Resonant Excitation Of Surface Waves
Author(s):
H. Akhouayri;
M. Neviere;
P. Vincent;
R. Reinisch
Show Abstract
The device studied here consists of a corrugated waveguide filled with a nonlinear dielectric (ZnS), and bounded by a metal (silver) on one of its sides. We concentrate on the second harmonic signal produced when a high energy laser beam impinges the device, and we try to enhance the signal intensity through the resonant excitation of a guided mode. Indeed, it has been established [1] that this electromagnetic resonance is a good candidate to increase the local field and, thus the sources for various nonlinear effects [2, 3]. It is shown that a convenient optimization of the grating groove depth can lead for signal enhancements as high as 105, compared to a nonlinear slab.
Measurement Of The MTF Of Photographic Emulsions By Means Of A Fiber-Optic Interferometer
Author(s):
Janusz W. Sadowski
Show Abstract
The performance of a photographic film as a recording medium can be characterized, in part, by its modulation transfer function (MTF). The MTF is giving us the dependence of image contrast on the structure of the imaged object which is expressed by its spatial frequencies. For the measurement of the MTF we can generate test signals either by an optical projection of a test chart, or by direct creation of signals on a film. In this paper we demonstrate a new method for the MTF measurement, based on a principle of forming a sine grating test directly on the film by means of a fiber-optic interferometer.
Hybrid Optical Computing, Architecture And Design
Author(s):
Francis T.S. Yu
Show Abstract
Optical signal processor has been shown to perform a myriad of complicated processing operations. It is primarily due to the profound diffraction phenomena of light. The essential merit of an optical signal processor must be the capability of processing the signal in complex amplitude, parallelism, large capacity, high speed and wavelength density. There are several processing operations that have been shown to be more efficient with optical techniques than their electronic counterparts. These operations are: Fourier transformation, convolution and correlation operations, spectrum analysis, and others. However, optical signal processors are still very inflexible as compared with the electronic computers.
Four-Dimensional Chromaticity For Distinguishing Efficiently Metamerism
Author(s):
Q. Tang;
L. R. Guo;
Z. H. Wang
Show Abstract
In the measurement of color, such as interference colors of birefringent crystal and color of the pseudocolor encoded output image(1),metamerism is a very widespread phenomenon, which influences directly practical applications of the meauement"and discrimination of color. In this paper, in order to research a one-to-one relation between color and object to be recognized, a 4-D generalized chromaticity space is presented and "the machine color" of birefringent crystal is measured and calculated. The results show that the metamerism can be distinguished efficiently by this method, which would be of significance in real-time automatic color discrimination.
Bismuth Germanate (BGO) Growth And Properties
Author(s):
G. P. Pazzi;
P. Fabeni;
R. Linari
Show Abstract
1. GENERALITY ON EGO PROPERTIES AND APPLICATIONS Bismuth Germanate Ei4Ge3012 (known as EGO) is a synthetic crystal grown as a replacement for the rare natural mineral Bismuth Silicon Oxide (eulytite) Ei4S13012 (ESO). It is a cubic crystal (symmetry 43m, with a tetramolecular cell) with the 6i3+ site coordinated by a distorted octahedron of oxigens. EGO monocrystals were grown by Nitsche in 1965 pulled from a pool of molten material contained in its own powder (other authors synthesized EGO since 1957). Bigger crystals by the Czochralski method were grown in platinum crucibles. Since that time, these monocrystals have been investigated for their electro-optical, electromechanical and luminescence properties, and for use as laser host material for rare earth elements. It presents high density (7.13 g/cm3), hardness of 5 (Mhos scale), melting point of 1050 C and a nearly flat transparent region between 0.3 and 6 um. EGO is an intrisic scintillator and the 480 nm emission band (FWHM = 160 nm) is obtained by excitation at 290 nm or by collision between y-rays and the atoms within the crystals. Around 1980 new interest on EGO arose due to its physical properties which make it suitable to replace for the traditional scintillators as NaI(T1). EGO crystals present many advantages as greater stopping power, much smaller afterglow, smaller radiation damage, nonhygroscopicity, physical ruggedness, so to allow setting-up more compact detectors (volume reduction of a factor 12) and handling much easier. Even if the integrated light output of EGO is one tenth with respect to NaI(T1), this light is still sufficient for readout by photodiodes. Although the energy resolution of EGO at 662 keV is one half of NaI(T1) resolution, its high peak-to-Compton ratio and high full-energy-to-escape-peak ratio is advantageous.
Radiation Force And Torque On A Stratified Sphere Levitated In The Circularly Polarized Tem81 Mode Laser Beam
Author(s):
Soo Chang;
Sang Soo Lee
Show Abstract
The radiation force on a sphere illuminated by the TEM81 mode laser beam was ray-optically treated by Roosen, Louvent and Slanskyl, and Kim and Lee2 developed a theory of radiation force on a homogeneous sphere in the Hermite-Gaussian mode laser beam by using the incident field, of which the expression is an exact solution of the wave equation. The radiation torque on a sphere in the circularly polarized plane electromagnetic field was theoretically worked out by Marston and Crichton3 and Chang and Lee 4 derived the formulas of radiation torque on a homogeneous sphere levitated in the circularly polarized TEM00 mode laser beam. However, for a stratified sphere illuminated by the focused TEMoi mode laser beam a further development of the formulas of radiation force and torque is required and the light scattering theory by a stratified sphere needs to be extended.
Coherent Resonant Pulse Propagation In A Nonlinear Absorber
Author(s):
G. E. Torres-Cisneros;
J. J. Sanchez-Mondragon
Show Abstract
The nonresonant propagation of a laser pulse through a nonlinear dielectric is now a well studied subjet because its extensive and direct applications mainly in communications by means of optical fibers and in spectroscopy. On the other hand, the coherent resonant interaction between high intense laser pulses and atoms or molecules is an intrinsic nonlinear phenomena that have received a great deal of attention since the discovery of Self Induced Transparency (SIT). However, the simultaneous consideration of both sources of nonlinearities, that may represent more realistic and important experimental situations, have not been yet studied in a systematic way.
Lau Rings: Circular Consonance
Author(s):
J. Oieda-Castafieda;
P. Andres;
E. Tepichin
Show Abstract
Interference fringes with very high contrast can be produced with certain spatially incoherent sources. The central idea in this kind of experiment is the incoherent in-register, or consonance, superposition of the same pattern/1,2/.
Lau Effect With High Throughput
Author(s):
J. Ojeda-Castafieda;
P. Andres;
J. Ibarra
Show Abstract
The self-imaging phenomenon can be applied to implement simple, and yet powerful optical devices. Furthermore, in many of this kind of applications, the signal-to-noise ratio can be increased substantially by using a laterally periodic, incoherent source.
Continuously Variable Periodic Test Target
Author(s):
P. Andres;
J . Ojeda-Castareda;
J. C. Barreiro
Show Abstract
The modulus of the optical transfer function (MTF) of the eye or any other optical system is usually evaluated by imaging either several gratings each with different spatial frequency, or a single test target having patterns with different frequencies (USAF resolution chart). In any of these two usual procedures, the measurement of the MTF is made at discrete values of the spatial frequency. Here we describe a method based on the self-imaging phenomenon for producing periodic patterns with a continuous variation, within a certain interval, of the spatial frequency.
Digital Data Reduction Of Rotationally Invariant Interferograms.
Author(s):
J. J. Sanchez-Mondragon;
D. Malacara;
A. Davila
Show Abstract
We present a method that makes use of the symmetry of rotational invariant interferograms, easy availability of digitalization equipment, FFT and efficient integration methods, in order to carry out the reduction of interferometric data.
Resonant Pulse Propagation In Near Degenerated Atomic Medium.
Author(s):
Oracio C. Barbosa;
J. J. Sanchez-Mondragon;
G. E. Torres-Cisneros
Show Abstract
The problem of pulse propagation in a resonant multilevel atomic medium, where interference among different channels of interaction occurs, has been studied mainly from the point of view that each interaction channel is independent and carry a different pulse [1] or in partially degenerated systems, like the Zeeman laser, where the problem is basically reduced to compiting modes in steady conditions [2]. The interference between different couplings is a well known feature in spectroscopy, like level crossing and depolarization [3], which have been known for long and received renewed attention as nonlinear process due to the laser [4].
Non-Conventional Tunable Spatial Filtering
Author(s):
P. Andres;
A. Pons;
J. Ojeda-Castaneda
Show Abstract
A virtual display of the Fraunhofer diffraction pattern of any object is formed in the transverse source plane by theyirtual diffracted rays extqn0ing in the region to the left of the screen containing the transparencyl),2). Except for a few cases '')"°), the concept of virtual Fourier transform appears not to have been made use of. The main idea of this paper is, bearing in mind the property referred to in the above paragraph, to describe a novel spatial filtering technique. In this way, one can obtain different filtered images, by simply moving the point source along the optical axis. The basic theory is described below.
Coupling Condition For Irradiance Focal Symmetry
Author(s):
J. Ojeda-Castarleda;
P. Andres
Show Abstract
The symmetry properties of focused fields are relevant either when considering fundamental properties related with phase conjugacy /1/, or when implementing experimental procedures for automatic focussing /2/.
Mass Replication Of Optically Recorded Holographic Optical Elements
Author(s):
M. L. Rizzi;
P. Delvo
Show Abstract
This paper deals with the application to HOE's of the experience acquired by CISE Holographic Labora-tory in the embossing technique of 3D or 2D images. The embossing of HOE's in plastic transparent materials is not able, up to this time, of performing the high diffraction efficiencies associated with HOE's recorded by DCG or photopolymers. However a large number of applications requires the production of great quantity, medium standard, low cost special optical elements to be used in rather complex instruments. Some notes about the embossing process and example of industrial components under development are reported.
Design Of A Compact Catadioptric Lens For Star Mappers
Author(s):
D. V.B. Rao;
Y. K. Jain;
T. K. Alex
Show Abstract
Star mappers are used for high accuracy attitude determination of spacecrafts. The light collecting optical system is either a catadioptric lens or a refractive lens. The catadioptric lens has the advantage of wider spectral coverage. For this type of application a constant and symmetric blur diameter over the entire field of view of the lens is required. A compact catadioptric lens was designed which covers a total field of 8 degrees. The design was compact, easy-to-align and does not involve any aspheric surfaces. The constancy of blur diameter with FOV was very good at +10 micron defocus plane.
Interferential Metrology Of Optical Frequencies
Author(s):
P. Bouchareine;
O. Cabon;
P. Juncar;
R. Goebel;
Y. Millerioux;
A. Razet
Show Abstract
Interferometrical methods have long been a very precise way to measure optical wavelength. The development, since now almost 20 years, of highly stabilized laser sources has permit to undertake interferometric measurements of wavelength ratios to an accuracy level which was not accessible to the wavelength standard of the previous definition of the meter based on the value of the krypton orange line. Since October 20th 1983 the meter is defined as following : "Le metre est la longueur du trajet parcouru par la lumiere dans le vide en une duree de 1/299792458 de seconde."
Optical Processing Methods Of Image Information Compression ---A Research Of The ODPCM Method
Author(s):
Lin Ning;
Wu Changfa;
Ye Jiaxiong
Show Abstract
The differential pulse code modulation (DPCM)1) method is a kind of digital processing methods of the image information compression. A digital DPCM compression system consists of a time feedback loop and a predictor. Its salient points can be summarized in the following three properties: 1) after prediction and difference steps, the low-frequency information of the image removed, and it may be recreated in the reconstruction process by the predictor; 2) if the prediction is accurate, the difference will be much smaller than the incoming data, also, the coding bits must be much less; 3) the DPCM process is causal.Simulating the digital processing with optical methods, much work has been done, e.g., interpolated DPCM (IDPCM) 2), which showed theoretically that an optical interpolator could be used to replace the linear predictor in the DPCM and an incoherent optical processing systme replace the time feedback system. However, the IDPCM method concerned only with the digital simulation of the DPCM, on any real optical compression processing system has been reported until now. In this paper, we propose and design a practical optical system of image information compression based on the IDPCM theory. A complete optical system of the DPCM was first realized in our laboratory. A series of experiments of image compression processing, in which a binary image is taken as the input, have been done in the ODPCM system and their results show the feasibility of the ODPCM method.
Experimental Study Of A Zno Modulator Using Guided Wave Resonance
Author(s):
D. Persegol;
E. Pic;
J. Plantier
Show Abstract
The theorical possibility of realizing an integrated electrooptic (EO) modulator using a grating to incite resonantly the guided modes of a multilayer structure, have been studied by Reinisch et al. 1). This new type of modulator, using the Pockels effect and the resonant excitation of a guided mode,allows the simultaneous modulation of a free and of a guided optical wave. In this communication, we present experimental and theoretical results concerning the modulation of the free beam and the calculation of the values of the EO tensor coefficients of the waveguide.
Rotation Invariant Pattern Recognition
Author(s):
Henri H. Arsenault
Show Abstract
This paper reports on recent progress on invariant pattern recognition. Circular harmonic component (CHC) matched filters allow pattern recognition that is invariant under translations and rotations of the objects, and does not require segmentation of the object from its background. Now that the problem of the proper center for expansion of the filter has been solved, it has become easier to use such filters. The performance of the filter may be improved without using multiple filters by using composite CHC filters. When both target discrimination and sidelobe reduction are required, a composite filter that is an average between two composite filters must be used. The use of other invariant features is discussed.
Composite Phase Filters For Distortion Invariant Pattern Recognition
Author(s):
Joseph Rosen;
Joseph Shamir
Show Abstract
Conventional methods of optical pattern recognition suffer from the requirement of high resolution recording materials and distortion sensitivity. In some recent publications1-3 a new, general procedure was introduced that may be employed for generating spatial filters with reduced resolution requirements. Partial- and complete rotation-invariance was demonstrated in computer simulations with phase- and bipolar amplitude-filters, respectively.
Pattern Recognition Based On The Triple Correlation
Author(s):
Adolf W. Lohmann
Show Abstract
In ordinary pattern recognition systems the input image is sent through a linear filter, such as a matched filter. The presence of the search pattern is identified as a peak in the output image. In some of the newer pattern recognition systems it is not the input image itself which is filtered. Instead, a "secondary signal" is tested by a suitable filtering process. A typical "secondary signal" is the power spectrum of the original input image. The power spectrum has lost the information of the location of the search pattern within the input. This loss of location information makes the job of signal processing easier, since the irrelevant data has been supressed. Hence, working with the power spectrum as a secondary signal is advantageous, provided the location of the search pattern is of no interest. Only the presence or absence of the search pattern has to be decided upon.
Pattern Recognition Using Tandem Component Filter
Author(s):
K. Chalasinska-Macukow;
H. H. Arsenault
Show Abstract
The tandem component system consisting of two elements with pure phase structures, allows to carry out a general wave front modification with a theoretical light efficiency of 100%, independently of the object function (1). One of the applications of the tandem component are correlation type measurements (2,3). With the tandem component filter (TCF) it is possible to obtain an almost perfect peak in the out-put plane of the recognition system, with a 100% light efficiency. This filter does not give an exact correlation function. Similarly to the conventional matched spatial filtering (MSF), all information about Fourier transform of an object is used to recognize a target, but this operation is space-variant. Our goal was to analyse digitally the discrimination capability of the tandem component filter (TCF), compare the results with the results obtained with the use of the classical matched spatial filter (MSF) and the phase-only filter (POF), and to decide whether to place the tandem component filter in the class of filters with enhanced discrimination capability (like, for example, the phase-only filter), or not.
Image Recognition By A Display System Of Three-Dimensional Image Data And Its Application To Image Diagnosis Of Holographic Under-Snow Radar
Author(s):
Yoshinao Aoki;
Yuji Sakamoto;
Yoshinari Takahashi
Show Abstract
A holographic radar is one of the promissing techniques to detect objects buried in piled-snow and investigations on developing such a radar system -- called under-snow radar -- have been reported 1),2). The purpose of under-snow radar is not only to identify the locations of an object but to recognize the shape of the object. Therefore diagnosis of image is often necessary to recognize the original object in such an imaging radar. In this paper we propose a new technique combined with the technique of computer graphics to diagnose images of under-snow radar using a memory system which stores three-dimensional information.
Motion Blur Compensation Of CCD Endoscope Images By Color Deviation Method
Author(s):
S Kikuchi;
N. Ohyama;
E. Badique;
J. Tsujiuchi;
T. Honda
Show Abstract
Recently, medical endoscopes with CCD camera devices have been developed and aroused great interest because of a larger number of picture elements than conventional endoscopes with optical fiber bundles. One type of image acquisition system is such that color images are sequentially taken with red (R), green (G) and blue (B) illuminations. This type has the merit of a good spatial resolution but constructed images are sometimes blurred or color shifted because of a rapid object motion while recording three primary color images. Since three primary color images have strong correlation, this problem can be solved by a compensation method using phase correlation l). This paper shows an advanced technique named the color deviation method which is much simpler than the previous method.
Particle Analyzer Using Fourier Techniques
Author(s):
C. Gorecki
Show Abstract
Fourier techniques are often used in optical processing for determining information about the diffracting objects. Many industrial powders are quasicircular and their diffraction patterns have a rotational symmetry. To classify automatically such diffracting samples we present an optical/digital spectrum analyzer which uses a Wedge Ring Detector. A procedure based on least-squares inversion of measurements is implemented to estimate particle-size distribution. A scene of three classes of varying sizes of Fe203, Fe0 particle substrate is analyzed and experimental results are given.
Distributed Photorefractometer Using The Total Reflective Phenomena Of An Optical Fiber
Author(s):
Hajime Hattori;
Takashi Takeo
Show Abstract
Recently, research and development in optical fibers has made rapid progress. Many studies of the application of optical fibers to the analysis of liquid or monitoring sensors in fields of chemical processing plant have been carried out. Formerly, for measuring a liquid refractive index, Abbe's refractometer and others have been used. The authors have developed an optical fiber photorefractometer as a compact measuring method of a refractive index 1,2) and have made studies of its application and its improvements.
Differential Heterodyne Optical Probe Using A Zeeman-Laser
Author(s):
S. Komatsu;
H. Suhara;
H. Ohzu
Show Abstract
Optical scanning microscopy has been widely used to detect light scattering particles or lattice defects in crystals1'2). On the other hand, optical heterodyne technique using a local heterodyne optical system has been adopted by some authors for aberration free image formation3,4). In this study we developed a light scattering microscope with a differential heterodyne optical system simplified in its configuration by the use of a Zeeman laser, and the feasibility of the system was examined experimentally. Differential heterodyne optical system has the advantage of gaining strong scattered light, simple congiguration, and applicability to the detection of other kinds of physical quantities such as acoustic waves and optically induced electric currents.
Design And Characterization Of Solid-State Cameras For Machine Vision
Author(s):
Tuan-Kay Lim
Show Abstract
Solid-state imaging technology is widely used in machine vision systems for industrial applications such as parts recognition and automatic inspection. In this paper we present a systematic, comprehensive analysis on the design and characterization of line-scan solid-state camera which consists of an imaging lens and a linear imaging sensor.
Quantum Limited Imaging
Author(s):
J. C. Dainty
Show Abstract
Optical imaging at high light levels is adequately described by the diffraction or wave theory of image formation as, for example, expounded in Reference 1. The directly observable quantity in this case is the wave intensity. At low light levels, however, the intensity is not measurable: real detectors respond to the light field by emitting phot2-electrons randomly in space and time. According to the semi-classical model, due originally to Mandel , the photo-electrons form a doubly stochastic point process which embodies the statistics of the classical intensity and those of the detection process. In particular, the probability of photo-electron emission in the region of the space-time coordinate (x,t) is simply proportional to the intensity averaged over the same space-time region. This semi-classical model is sufficient for most purposes in low light level imaging and in the following we shall refer to the photo-electrons as detected photons or quanta.
Measurements of Light Scattering by Randomly Rough Surfaces of Known Statistics
Author(s):
A. S. Harley;
M-J. Kim;
J. C. Dainty
Show Abstract
Over the past few decades, a very large number of theoretical studies of the scattering of electromagnetic waves by rough surfaces have been published'. Unfortunately, no satisfactory theory is available for surfaces of arbitrary statistical properties. Only solutions for certain surfaces and scattering geometries are available, e.g. Kirchhoff or physical optics theory (after Beckmann2) for surfaces of very low slope and long correlation length relative to the wavelength. Although experimental studies have been made, the surface statistics in the experiments have rarely been matched to the assumptions of theory, rendering the results of little value for verifying theories. The aim of the present study is to measure the angular distribution of light scattered by surfaces that are very well characterised and whose statistics closely approximate the theoretical assumptions.
Optical Scattering From Rough Surfaces : Recent Progress Of The Theory
Author(s):
D. Maystre;
A. Roger;
M. Saillard;
H. Faure-Geors
Show Abstract
In the recent years, many theoretical and experimental investigations have dealt with the feasability of using light scattering as a means to measure microgeometry of surfaces quantitatively. Motivation for this new direction is the increasing efforts to use light scattering rather than the traditional stylus instrument for quality control and inspection of the surface finish of manufactured parts.
Multiple Light Scattering From Perfectly Conducting Rough Surfaces
Author(s):
M. Nieto-Vesperinas;
J. M. Soto-Crespo
Show Abstract
We present Monte Carlo numerical calculations of multiple scattering of E.M. waves by computer simulated 1 D perfectly conducting random rough surfaces by making use of the extinction theoreml .2'3. The computations are performed by taking ensamble averages of sets of scattering amplitudes obtained for surfaces profiles generated by a sequence of random numbers with Normal statistics and Gaussian correlation function. (See e.g. Ref. 4).
Frequency Stability Of Simple Commercial He-Ne Laser For Practical Length Standard
Author(s):
Keiichi Tanaka;
Seiichi Kakuma
Show Abstract
Very rapid development of micro-electronics and optics, which stems from computer engineering or optical communication technology, has activate people, who engage in laser metrology or nanometer technology. Recently, several simple commercial wavelength stabilized gas lasers have been developed and widely used for scientific research and production engineering. Under the present situation, some people, who are developing stabilized lasers or using a length measuring laser interferometer, seriously feel necessity of absolute wavelength calibration of their stabilized lasers or to own their wavelength standards.
Surface Quality Assessment By Image Comparison
Author(s):
L. R. Baker
Show Abstract
The final stages in the process of surface generation are often the most critical in determining product quality. Ideally the end point in the generation of surface shape or form should be reached at the same time as the desired quality of texture, roughness or polish. In practice, however, this situation is difficult to achieve because although form can usually be measured objectively, for example by the use of an interferometer, there is as yet no non-contacting means for measuring roughness and flaws post-process on-machine.
Solc Birefrengent Filter And Monomode Fiber-Optic Filter
Author(s):
Zhou Yan-Xun;
Xu Sen-Lu;
Guo Cheng-Shan;
Sheng Lie-Yi
Show Abstract
Birefrengent filter is a kind of interference filters based on the medium birefren-gence property and the polarization interference principle. The typical birefrengent filters are Lyot's and Solc's models. Recently, Solc filter and its fiber-optic system have much interests for such potential applications as astrophotography,tunable elements in dye laser, submarine communication and in-line monomode fiber-optic birefrengentfilter which can be used to create multichannel communication lines from a monomode fiber [1-4]. In this paper, we will analyse an equivalent structure of Solc filters by using Jones calculus [5] of polarized optics. Moreover, we consider the influence of the imperfection of the polarizers on Sole filter and give a general formula of the spectral transmittance of Sole filter. Finally, the practical design and manufacture of equiva-lent Solc filter in monomode fiber is presented.
Statistical-Image-Surface Conception In Analysis Of Electrostatic Electron-Optical Imaging Systems
Author(s):
J. M. Woznicki
Show Abstract
Progress of computational methods in electron optics makes possible to determine focusing properties of real electron-optical systems by means of electron trajectories analysis (e.g.U] ). These problems have essential practical meaning in optics in general. For real optical systems the rays method of the image properties analysis seems to be useful.
A Method For The Latrix Detector Alignment
Author(s):
Gyorgy Abraham
Show Abstract
It's known that,lhe Spacelabs Vega I and Vega II took pictures of the comet Halley on the 6th and 9th March 1986. These pictures were recorded by a TV-camera which contained two optical systems with 2-2 CCD-s in their focal-plane. One of these optical systems was an 15o mu wide-angle objective and the other was an 1200 mm reflecting telephoto objective.
Advances In Lightwave Systems Research
Author(s):
Tingye Li
Show Abstract
Twenty years have passed since the first serious proposal was made to employ a glass fiber waveguide as a telecommunications transmission medium. Vigorous research and development efforts have led to widespread applications of optical-fiber communication throughout the telecommunications industry. Current lightwave systems research is motivated to explore the vast potential bandwidth of low-loss single-mode fibers for long-haul and local-networking applications. Laboratory systems employing experimental single-frequency lasers and low-noise avalanche photodiodes have attained high-speed transmission at multigigabit-per-second data rates in single-mode fibers well over 100-km long. Coherent technology promises high receiver sensitivity and offers an efficient means for channel selection in a densely-packed wavelength-multiplexed system. First coherent systems experiments have confirmed theoretical expectations but many challenges lie ahead. Other novel systems for local distribution and networking are also under study. This paper will consider the limits imposed by the single-mode fiber, discuss the requirements of the relevant devices, and report the results of the latest systems experiments.
Rare-Earth Doped Fibre Lasers And Amplifiers For Optical Communications
Author(s):
I. D. Miller;
C. A. Millar;
B. J. Ainslie;
D. B. Mortimore;
J. R. Armitage
Show Abstract
Recently, the widespread use of single-mode fibres has demonstrated the need for a range of optical components which perform useful optical functions such as routeing, modulation, amplification, and carrier generation. The benefits of achieving these in all-fibre form are considerable. Interest in the latter functions was generated by the pioneering work at SouthamptonVniversity on the fabrication (1) and demonstration of efficient fibre lasers using Pr3+, Nd3+ and Erif as the rare-earth dopants (2), pumped using a variety of sources including inexpensive GaAs semiconductor lasers. Line-narrowed, tuned, mode-locked and Q-switched operation have been reported in these fibre lasers.
Automated Fabrication Of Customized Compact Multi-Cycle Directional Taper Couplers
Author(s):
S. Faucher;
K. O. Hill;
F. Bilodeau;
D. C. Johnson
Show Abstract
An automated jig designed to fabricate fused monomode-fiber taper couplers is reported. The high level of fabrication control achieved permits the observation of new coupler properties: the flexing response of polarizing couplers, anti-symmetric supermode cutoff and the pull-signature of asymmetric couplers.
2-D Colour Image Transmission Through Optical Fibers
Author(s):
A. A. Tagliaferri;
J. Calatroni;
C. C. Lopes;
J. M. Nagai
Show Abstract
The transmission of a 2-0 coloured image (i.e. a 3-0 information), through an optical fiber, needs a process of codification in order to adapt the signal to be transmitted to the channel of transmission. This codification can be done in real time, by pure optical means, using the process of chromatic codification.
Temporal Versus Spatial Carrier Techniques For Heterodyne Interferometery
Author(s):
Mitsuo Takeda
Show Abstract
Two different types of interferograms and their analysis techniques are being used in precision interferometry. The heterodyne interferometry proposed by Massie et al.1) uses a time-varying interferogram i(x,y;t) with a temporal carrier frequency fa generated by an acousto-optic modulator; g(x,y;t) = a(x,y) + b(x,y)cos(2,rfet +0(x,y)]. (1)
A New Type Of Holographic Shearing Interferometer For Measurement Of The Lateral Aberration Of Lens
Author(s):
K. Matsuda;
Y. Minami
Show Abstract
A shearing interferometer produces the differential interference fringes of a wavefront, so that it is useful in measuring the lateral aberrations of lenses. Recently holographic shearing interferometer has been applied to the measurement of lateral aberrations of lenses owing to several advantages 1)2). However, when we obtain an aberration curve from a shearing interferogram, the differential equation must be solved numerically. To overcome this disadvantage, a new type of holographic shearing interferometer is proposed here. The interference fringes obtained by this interferometer can directly represent the lateral aberration curve of a lens.
A Holographic Interferometer Using An Oil Surface As A Reference Plane
Author(s):
K. Matsuda;
H. Shimazutsu
Show Abstract
When the measurement of a surface flatness over a large circular area of an object is made with interferometers, it is imperative to use a highly polished large surface area as a reflecting reference plane. However, supplying such a plane is a difficult thing. To overcome this difficulty, an oil surface on the object to be studied has been used as its reference plane. In this method, the object under investigation was completely immersed in a tilted container filled with oil, and thus the arrangement of a Fizeautype interferometer was able to produce the interference fringes between two beams; one reflecting from the oil and the other from the object surface 1).
Stroboscopic Holographic Interferometry Application Of Digital Techniques To The Study Of Vibrating Objects
Author(s):
P. Hariharan;
B. F. Oreb
Show Abstract
Stroboscopic holographic interferometry is a very powerful tool for the study of vibrating objects1-3). Typically, a hologram of the stationary object is recorded with continuous illumination and processed in situ. The vibrating object is then viewed through the hologram using pulsed illumination at the vibration frequency. Real-time fringes are seen correponding to the deformation of the surface relative to its rest position. However, quantitative information is available only along the fringe maxima and minima. If the fringes are far apart and unequally spaced, determination of the actual amplitude distribution over the surface of the object is quite laborious and subject to errors. Ambiguities can also arise if some parts of the surface are vibrating in antiphase.
Holographic Interferometry In Fourier Plane Using Digital Image Processing
Author(s):
V. I. Vlad;
D. Popa;
I. Apostol
Show Abstract
The holographic interferograms in Fourier plane are characterized by the fact that the fringes are always localized in the hologram (Fourier) plane and occur in two patterns only: stright parallel or circular lines. Thus, measuring the decentering, tilting and spacing in the'fringe pattern, it is possible to obtain simultaneously all components of the displacement/vibrations amplitude vector from one hologram1). Taking into consideration these advantages, a hybrid holographic-digital processing system for 3D displacement measurement was developed2).
Biomedical Image Processing Using Soft Pulsed X-Ray Source
Author(s):
H. Isobe;
E. Sato;
T. Yanagisawa
Show Abstract
The pulsed x-ray technique can be used in high speed image technology, and several different types of the FX sources used in the radiography of various objects have been reported1).
Error Reduction In Two-Dimensional Pulse-Area Modulation, With Application To Computer-Generated Transparencies
Author(s):
Martin J. Bastiaans
Show Abstract
The paper deals with the analysis of computer-generated half-tone transparencies that are realised as a regular array of area-modulated unit-height pulses and with the help of which we want to generate [via low-pass filtering] band-limited space functions by optical means. The mathematical basis for such transparencies is, of course, the well-known sampling theorem [1], which says that a band-limited func-tion y(x), say, [with x a two-dimensional spatial column vector] can be generated by properly low-pass filtering a regular array of Dirac functions whose weights are proportional to the required sample values yey(Xm) [with X the sampling matrix and m=(mi,m2)t an integer-valued column vector; the superscript t denotes transposition].
3-D Microscope Imaging By Optical 3-D CT
Author(s):
S. Minami;
O. Nakamura;
S. Kawata
Show Abstract
The success of X-ray CT (Computed Tomography) in clinical medicine has motivated studies of nondestructive three-dimensional (3-D) observation of samples by light wave propagation through 3-D samples. The optical CT technique has been applied to 3-D measurements of refractive index, air pollutants, flow, plasma density, and birefringence. We have proposed a new method of optical 3-D CT for microscopic 3-D imaging with a conventional transmission-microscope optics and an advanced computer algorithm. By this method, inside 3-D structures of alive biological samples can be reconstructed without slicing-preparation of samples. In this paper, we describe the principle of the developed optical projeciton system with the analysis of its 3-D OTF, and the reconstruction algorithm with constraints. An experimental example of multispectral 3-D reconstruction is shown for a pollen of pine.
Geometry-Free X-Ray Reconstruction Using The Theory Of Convex Projections
Author(s):
Peyma Oskoui-Fard;
Henry Stark
Show Abstract
In problems involving inspection by x-ray tomography, it may not always be possible to obtain a full set of parallel-beam or fan-beam views from which to reconstruct an image. This may occur because of: 1) external obstructions; 2) internal obstruction; and 3) restricted data acquisition times. Yet typical reconstruction algorithms such as convolution-back projection (CBP) or the direct Fourier method (DFM) are based on specific geometries and a full set of views.
Automated Optical Testing
Author(s):
H. J. Tiziani
Show Abstract
Interferometry, holographic interferometry and speckle techniques are becoming useful tools for precision measurements in research and for industrial applications. Computer analysis ist increasingly important for the fringe analysis. The use of solid state detector-arrays, image memory boards together with microprocessors and computers for the extraction of the information from the interferograms and high resolution graphic boards find important application in optical metrology. Much more information can be extracted from the interferograms leading to higher sensitivities and accuracies.
Shape Measurement Of Deep Aspheric Optical Surfaces By Radial Shear Interferometry
Author(s):
T. Honda;
J. Huang;
J. Tsujiuchi;
J. C. Wyant
Show Abstract
Nowadays, mirrors and lenses are used that have surfaces with a deep asphericity of rotational symmetry, and there is a strong need for the precise shape measurement of these surfaces. It is not easy to measure this kind of surface by using the common interferometric method becatm the fringes are too dense to be observed. For decreasing the fringe number, a radial shear method1 is adopted.
Aspheric Measurement Using Phase-Shifting Interferometry
Author(s):
Katherine Creath;
James C. Wyant
Show Abstract
Aspheric optical surfaces are difficult to test because these surfaces generally depart too much from a sphere for a conventional interferometer to resolve the interference fringes and allow reconstruction of the test surface. A large number of detector points can provide a brute force approach to measuring these surfaces. More elegant techniques such as using multiple wavelengths or a priori information about the wavefront can enable wavefront reconstruction.1-3 Once the necessary information has been detected, corrections are needed to account for the propagation of aberrations through the optical system from the test surface to the detector. Combining fringe analysis with lens design software will allow this correction to take place. This paper examines these techniques, and compares them to currently utilized techniques.
Profile Measurement Of Aspheric Surfaces By Laser Beam Reflection
Author(s):
R. Diaz-Uribe;
R. Pastrana-Sanchez;
A. Cornejo-Rodriguez
Show Abstract
By observing the reflection of a laser beam from an optical surface, it is possible to infer certain geometrical properties of the surface, such as its radius of curvature, its conic constant, its profile and some errors of fabrication; the method depends on the type of surface. With this approach, we have developed a method for measuring the longitudinal aberration, X, and the angle, g, with respect to the optical axis, of the normals of a conic surface1). Although this information is sufficient to describe the surface, it was necessary to develop a formulation for calculating, from those parameters, more evident variables such as the sagitta, Z, and the semidiameter, S (see figure).
Analysis And Discussion Of An Important Concept In Testing Aspheric Surfaces With CGH
Author(s):
Wu Ji-Zong;
DAI Xiao -fang;
CAI Zhen-Xianq
Show Abstract
When some authors describe the testing of aspheric surfaces with CGH, they simply define the general expression of wave aberration as the behavior of light wave reflected from the ideal mirror surface and acting upon the surface of CGH. Taking the paraboloidal mirror as an example, they simply adopt the following equationl) without any mathematical processing to express the wave aberration reflected from the mirror to be tested:
Noise Response Of Birefringent Single-Mode Optical Fibers Exposed To External Perturbations
Author(s):
Y. Ohtsuka;
Y. Imai;
M. Tsukada
Show Abstract
In the potential areas in which the wave characteristics of an optical eigenmode guided in the optical fiber plays an important role, it is substantially required to have the state of polarization (SOP) of the propagating mode stabilized. The birefringence induced externally in the fiber causes a change in the SOP and impairs the function of fiber-optic systems, such as coherent optical communications and interferometric sensors. To overcome this undesirable problem, there have been developed birefringent single-mode fibers capable of maintaining the SOP of the guided mode. Such a fiber has been fabricated to have a highly anisotropic residual stress in the direction of its cross-section in order that a particulary high birefringence is induced in the propagation direction of light. Nevertheless, the SOP can no longer be preserved in the presence of some external perturbations such as pressure and temperature changes even if any kind of such fibers may be employed. This effect will be a factor of phase and amplitude fluctuations for the propagating modes in the fiber. Since the resulting noise effect would be in a close relation to the ultimate performance limitation in the fiber-optic coherent systems, it is invoked to examine how the birefringent single-mode fiber suffers from such external perturbations. The intent of this paper is to present a correlation processing of the phase and amplitude fluctuations for the orthogonal eigenmodes guided in an externally perturbed birefringent single-mode fiber.
Ultrasonic Sensor Using Polarization-Maintaining Optical Fiber
Author(s):
H. Takahara;
F. Togashi;
T. Aragaki
Show Abstract
The interaction between acoustic wave and the laser light passing through an optical fiber has been studied by several workers.1)-4) The detection of acoustic wave using an optical fiber carried out5)6), also. The receiving sensitivity of optical fiber hydrophone is determined by the rate of change in the optical path length of the sensing fiber with respect to changes in the external pressure on the fiber. These changes in the optical path length are results of the induced changes in index of refraction of the fiber and changes in the length of the fiber. There are the hydrophone of an interference using two optical fibers and a non-interference using a polarization-maintaining optical fiber. In this paper, an ultrasonic sensor using a polarization-maintaining optical fiber based on a. non-interference has been studied.
Detection Of Discrete Faults With Very Low Reflectivity Along Optical Fibers
Author(s):
Mehdi Shadaram
Show Abstract
Optical Frequency Domain Reflectometer (OFDR) has shown certain advantages over the Optical Time Domain Reflectometer (OTDR) for the detection of discrete faults along optical fibers (1-4). An OFDR usually employs a cw optical carrier modulated by a constant amplitude rf signal with a periodic linear frequency sweep (shown in Fig. 1). The detected optical echoes are delayed by propagation in the fiber to produce a delay in the sweep phase of the modulation. In this paper, OFDR has been employed for the detection of discrete faults with very low reflectivity along optical fibers by taking Fourier transform of the complex envelope of the echoes.
Optical Fiber Line-Sensor Based On Intermodal Interference
Author(s):
Chung-Yee Leung;
I-Fan Chang
Show Abstract
Modal noise : distortion of signal caused by interference between different modes, is a well-knownproblem in multimode fiberoptic communication192). Being sensitive to mechanical distortion of the fiber, however, this phenomenon has been used to advantage in the sensing of sound3) and liquid flow4). In this paper, results of our experimental studies on a kilometer-long fiberoptic line sensor based on intermodal interference are presented. It is shown that practical distributed sensing system, useful in security applications, can be easily constructed from such lengthy line sensors.
Stabilization Of Fiber Interferometric Sensors With Double-Loop Phase Compensation
Author(s):
Ton Ko;
Chung-Ho Hsia;
Ming-Wen Chang
Show Abstract
One of the conventional methods to improve the operational stabilization of the Mach-Zehnder fiber interferometer is using the single-loop-feedback (SLF) compensation for the phase drift between the signal and reference arm of the interferometer"2"3). However, the random variation of the wave polarization state in the single-mode fiber of the two arms will affect the stability of the mixing efficiency when the two beams combine, unless polarization-maintaining fibers are used. Without the special fiber, one may apply automatic gain control MGC) circuit4) in the detection to stabilize the amplitude of the detected signal but the signal-to-noise performance of the system can not be promoted, especially in the presence of severe polarization fading 5).
The SDF Method In Optical Power Spectrum Recognition
Author(s):
L. R. Guo;
X. Y. Su;
G. S. Zhang
Show Abstract
Filtering by synthetic discriminant function (SDF) is an effective method to achieve distortion invariant optical pattern recognition(1). In this paper, the fundamental algorithm of SDF is applied to optical power spectrum recognition and classification in optical frequency spectrum analytical system, and an optical implementation of SDF method for the classification is presented and rather good results are obtained.
Component Pattern Analysis Of Multiband Images
Author(s):
S. Kawata;
K. Sasaki;
S. Minami
Show Abstract
Various computerized image-processing methods have been developed for analyzing spatial patterns of specific components in given images. In pattern recognition studies, patterns are classified into different components in the feature space by comparing component features, for example, shape, size, density, histogram, direction, etc. However, it often happens that the components can not be classified in the feature hyperspace because of their mutual dependency in spatial domain. We calim that, in such a case we should use spectral (optical frequency) information of components. Different materials must have different spectroscopic responses to electromagnetic waves of a certain energy band.
3-D Rotation And Scale Invariant Object Recognition From Multiple Views
Author(s):
Rong-Hwang Wu;
Henry Stark
Show Abstract
Rotation invariant recognition of two-dimensional objects (e.g., images) can be done robustly using circular harmonic function (CHF) expansion coefficients.1-4 Scale (size) invariant recognition can be done using Mellin transforms.5 The two activities together can be combined into a single algorithm that efficiently enables scale and rotation invariant recognition. Such algorithms, whether based on CHF's or other methods, are described in the literature.6-7 The method used by the authors involves computing the Mellin transform of the CHF coefficients, generating an appropriate feature vector based on these objects, and comparing these vectors with a reference. If the test feature vector is near enough the reference then a match is declared. The procedure seems to be quite robust.
Multiple Matched Spatial Filter Performed With Nonsymmetrical Fourier Transformers
Author(s):
Carlos Ferreira;
Carmen Vazquez
Show Abstract
Classical matched spatial filters (CMSF) have been successfully employed for optical pattern recog-nition. To detect different signals, multiple matched spatial filters can be synthesized and several methods to perform the filters have been developed. Based on the sensitivity to input orientation of CMSF, we proposed a filter [1] where the signals to be detected were rotated by different angles when recording the hologram. Thus, the recognition of a signal is only achieved when the input in the filtering system has been suitably rotated. The number of signals simultaneously recorded was limited by the angular tolerance of symmetrical correlators, of the order of ten degrees [2] for CMSF.
Local Image Filtering And Texture Classification Through The Wigner Distribution Function
Author(s):
J. Bescos;
G. Cristobal;
J. Santamaria
Show Abstract
The Wigner Distribution (WD) introduced by Wigner in 1932 as a phase representation in Quantum Mechanics gives a simultaneous representation of a signal in space and spatial frequency variables [1-2]. The WD might be interpreted as a local or regional spatial-frequency representation of a signal. However, it presents two main advantages with respect to other local representations. First, the WD is a real valued function and encodes directly the Fourier phase information. Second, the election of the appropriate window size which depends upon the kind of the analyzed information, is not required for the computation of the WD.
A New Technique For Pattern Recognition Using VFHF In White-Light Lensless Optical System
Author(s):
Mu Guoguang;
Wang Zhaoqi;
Wang Kemei;
Wang Xuming
Show Abstract
The advance in pattern recognition is achieved by the uses of Fresnel holographic filter (FHF) and extended source in a lensless correlator 1). This technique gains several advantages such as little effects of a displacement error in the alignment of the FRP and nonsensitivity to changes in scale and rotation of the detected object. In this paper, we present an improved technique by which the optical pattern recognition can be performed with white-light source and a volume Fresnel holographic filter (VFHF) in a lensless intensity correlator. The VFHF serves three functions: phase transformation, reconstructed wavelength selection as well as spatial filtering.
Short Laser Pulses ; Optical Applications
Author(s):
C. Froehly
Show Abstract
Optical processing of optical signals involves beam interactions through materials : mixing of signals Si and S., by the material non-linear susceptibility may generate new waves S3, of amplitude proportional to the product of the interfering beams amplitudes. Combination of beam multiplications with usual linear beam superposition (addition) achieved by conventional interferometers is the general basis of all-optical operations. Unfortunately optical materials often exhibit very weak non-linear susceptibilities : generation of the S3 component frequently taluirT5 that the product of the interaction length by the intensity of the co-propagating waves lies in the range 10 -10 W.m. It is clearly not possible to work at such levels of continuous laser power. Thus very active research is presently devoted to new highly non-linear materials where wave interactions may occur at moderate c.w. power. But stronger non-linearities appear generally connected with slower responses to field excitations. SHORT LASER PUL-SES, on the subnano- to subpicosecond time scales, offer another effective alternative to high-speed "opto-optical" signal processing : indeed one picosecond pulse ofi5nanojole energy focused onto the Airy disk of minimum area (one squared wavelength) shines the focus by a 10 W.m illumination. Then, despite low pulse energy, the above "interaction product" reaches the threshold of non-linear susceptibilities after transmission through less than one millimeter of conventional optical material. For instance such pulses will be produced at 100 MHz repetition rat! in the "mode-locked" emission of 1.5 m long Laser cavity, with moderate average power (1 W) and linewidth (10 Hz, i.e. 3 nm around 1000 nm average wavelength).
First Observation Of Higher Order Planar Soliton Beams
Author(s):
S. Maneuf;
F. Reynaud
Show Abstract
Transmission of quasi-monochromatic powerful laser beams through materials exhibiting intensity dependence of their refractive index (optical Kerr nonlinearity) frequently results in chaotic breakdown of the propagated beams. This corresponds to recognized instabilities of the solutions of the three-dimensional propagation equation (cubic nonlinear Schreidinger equation). Two-dimensional stable "soliton" solutions were found theoretically by Zakharov and Shabat in 1972 [1]. These solutions describe ,for the fundamental order stable self-trapping of single mode, two-dimensional monochromatic beams through homogeneous nonlinear slab. Higher orders solutions consist in periodical narrowings and spreadings of the guided beam. We experimentally demonstrated the existence of the "first order (fundamental) soliton beam" in 1985 [2].
"Soliton Beam" Self Trapping Applied To Passive Mode Locking Of Lasers.
Author(s):
A. Barthelemy;
C. Froehly;
S. Maneuf;
G. Sheng
Show Abstract
Soliton phenomena in optics usely refers to light field distributions that propagates without perturbations through Kerr type nonlinear transparent media. That happens at specified intensity levels when the nonlinearity cancels the group velocity dispersion effects on guided pulses or the diffraction effects on monochromatic beams.
Soliton Phase Conjugation In Four-Wave Nonlinear Interactions
Author(s):
H. Hsu;
C. C. Shang
Show Abstract
The theory of four wave interactions is extended to lend insight in interpreting physical wave relationships of solitons in finite nonlinear media. The coupled mode equations are solved in terms of Jacobian elliptic functions, and it is found that four-wave interaction processes produce a phase conjugate pair of bright solitons and a single dark soliton.
Electron-Beam Fabricated Computer-Generated Holograms (GGH) For Aberration Correction Of Holographic Optical Elements (HOE)
Author(s):
H. Buczek
Show Abstract
Holographic optical elements (HOE) are of interest as focussing or collimating lenses with monochromatic sources because they are very light and compact. HOEs used with sources in the infrared (e.g. laser diodes) have to be fabricated at a wavelength which is different from the application wavelength, since there are no holographic materials available for the infrared. The wavelength change between holographic recording and reconstruction causes aberrations which could be eliminated by using aspheric waves for the HOE formation [1],[2]. The aspheric waves needed for HOE recording can be obtained by computer-generated holograms (CGH) [3],[4].
The Zone Plate: A New Lease Of Life?
Author(s):
M. C. Hutley
Show Abstract
It has long been known that zone plates can be used to form an image but they have been little used in practice because a lens generally performs better. Since a zone plate distributes light into several diffracted orders the efficiency is low and since the focal length is inversely proportional to wave-length the chromatic aberration is enormous. However, despite these drawbacks the zone plate does possess some attractive features: it is a thin structure so it produces no distortion in the image; it is less bulky and lighter than a lens (which would be particularly important for many infrared applications), and can be replicated so it is amenable to inexpensive mass production. We suggest that there are 3 main reasons why zone plates might become more widely used: a change of requirements; improvements in manufacturing technology; and new applications which take advantage of the unique features of the zone plates.
Optimum Design Of Holographic Optical Scanning Elements
Author(s):
H. P. Herzig;
R. Dandliker
Show Abstract
Holographic optical elements (HOE) can serve as deflecting and focussing elements in laser scanners. They have been incorporated into supermarket point of sale systems [1], laser-beam printers [2] and are foreseen for far wider applications.
An Overview Of Quantization In Detour Phase Binary Holograms
Author(s):
V. V. Krishna;
P. S. Naidu
Show Abstract
Computer-generated holograms have many applications in diverse areas such as storage, processing and display of information, creation of difficult to obtain reference wavefronts, as logic-switching elements in optical computing etc. A majority of digital holograms evolved over the past two decades have been specifically designed to record information in the Fourier plane. One particularly important class of such holograms is based on the 'detour phase' principle developed by Lohmann and his co-workers [1]. These are mainly binary transimittance Fourier transform holograms with the most notable ones being the Lohmann, Lee and Burckhardt formulations [1], as also the double phase hologram (DPH) devised by Hsueh and Sawchuk [2] etc. Our interest in this paer will be confined to evaluating the image fidelity of these four holograms, and some of their variations as well.
Holography Of Speckle-Field Emitted From A Multimode Fiber-Optic Bundle
Author(s):
Y. Zhang;
Y. K. Sun;
J. Du
Show Abstract
In holographic and holographic interferometric system, the low lossy single multimode optical fiber (SMF) or incoherent multimode fiber-optic bundle (MFB) if used to guide laser beams for the object illuminated wave, or the coherent fiber-optic bundle is used to transmit the object information or holographic interference fringes to the hologram materially, a speckle field with quasi-homogeneous or inhomogeneous spatial structure must appear in the recorded object wave. This is due to the fact that the output field of a SMF or MFB coherently excited (bylaser) can be regarded as a quasi-homogeneous monochromatic speckle field (QHMSF)2). B.Ya.Zel'dovich, et al studied the theory of construction of those kinds of holograms3). The present study will develope the theory of the specklefield holograms of which the object illuminated and reference waves are both the QHMSF emitted from a MFB based on the B.Ya.Zel'dovic's theory. The experimental results that agree with the theory have been given.
Effects Of Correlation Between Two Fluctuating Sources On The Spectrum Of The Emitted Light
Author(s):
Emil Wolf
Show Abstract
It has recently been demonstrated both theoretically1-3 and experimentally4 that contrary to general belief, the spectrum of light emitted by a steady-state source depends, in general, not only on the source spectrum but also on the degree of correlation between the source fluctuations. When the source spectrum consists of a single line centered at frequency wo , the source correlation may cause the spectrum of the emitted light to be a line centered on a lower frequency < wo or at a higher frequency w'o > wA, depending on the particular form of the degree of correla?ion. Thus source correlations provide a new physical mechanism for redshifts or blueshifts of spectral lines. This newly discovered phenomenon is obviously-of particular interest for astronomy, where line shifts observed in the spectra of radiation from stellar objects have up to now always been assumed to be caused either by the motion of the stellar object relative to the observer (the Doppler effect) or as being due to gravitation. Examples of redshifted lines due to source correlations are shown in Fig. 1.
Rigorous Analysis Of Diffraction By Thin Gratings
Author(s):
Timo Jaaskelainen;
Teuvo Hytonen
Show Abstract
The most common methods of analyzing diffraction by dielectric gratings are the modal approach and the coupled wave approach, both of which can be exactly formulated. In their rigorous forms these theories are equivalent
Scattering Of Electromagnetic Radiation By A Hexagonal Ice Crystal
Author(s):
Frederick E. Alzofon
Show Abstract
This paper indicates a method of obtaining a rigorous solution of the electromagnetic wave equation for a plane wave incident on a hexagonal ice cylinder of the kind often observed in ice clouds"). A generalization of the method of solution, to a wider class of boundary surfaces, valid for differential equations other than the electromagnetic field equations appears possible. The latter surfaces are either cylindrical or closed, in distinction to surfaces spanning curves embedded in three-dimensional space. Rigorous solutions for surfaces which span curves have already been obtained by an extension of Sommerfeld's method2-4).
On The Theoretical And Numerical Study Of Diffraction Gratings Coated With Anisotropic Layers
Author(s):
G. Tayeb;
R. Petit;
M. Cadilhac
Show Abstract
It is known that a stack of anisotropic films lying on a plane substrate and illuminated with a linearly polarized plane wave generally gives rise to an elliptically polarized reflected field. With a view of application in optical data storage (the anisotropy being for example created by a static magnetic field), we may wonder whether this change in polarization can be enhanced by modulating the interface between the substrate and the layers. The following theoretical and numerical considerations have been developed in our laboratory while some measurements were performed in PA Cambridge Laboratory in the framework of a contract.
Phase Visualization Of Diffraction Patterns And Its Application
Author(s):
Motoki Yonemura
Show Abstract
In non-contact particle characterization in-line holography has played an important role. There are two methods for obtaining the information of particles, one is the optical reconstruction of real images and another is the calculation from the photographic recording of diffraction patterns. In the former, errors are introduced by focusing error, the nonlinearity of the recording media, aberration, etc. In the latter, from the diffraction patterns containing shape, size and position information it is difficult to extract each separately and the accurate measurement of light intensity data from the photographic record of diffraction patterns is also difficult.
Progress In Optical Memory Technology
Author(s):
Yoshito Tsunoda
Show Abstract
More than 20 years have passed since the concept of optical memory was first proposed in 1966. Since then considerable progress has been made in this area together with the creation of completely new markets of optical memory in consumer and computer application areas. The first generation of optical memory was mainly developed with holographic recording technology in late 1960s and early 1970s. Considerable number of developments have been done in both analog and digital memory applications. Unfortunately, these technologies did not meet a chance to be a commercial product. The second generation of optical memory started at the beginning of 1970s with bit by bit recording technology. Read-only type optical memories such as video disks and compact audio disks have extensively investigated. Since laser diodes were first applied to optical video disk read out in 1976, there have been extensive developments of laser diode pick-ups for optical disk memory systems. The third generation of optical memory started in 1978 with bit by bit read/write technology using laser diodes. Developments of recording materials including both write-once and erasable have been actively pursued at several research institutes. These technologies are mainly focused on the optical memory systems for computer application. Such practical applications of optical memory technology has resulted in the creation of such new products as compact audio disks and computer file memories.
Low Bit-Error-Rate Optical Read-Only Memory Card Reader
Author(s):
F. Kimura;
S. Izawa;
S. Takahashi;
Y. Okada;
K. Kodate;
T. Kamiya
Show Abstract
High density digital memory with megabyte storage capacity in the size of credit-card is very attractive lc' prious application fields because of its compactness, versatility and relatively high performance " 1. We have stccessfully developed a reading machine which realizes the reduced bit-error-rate as low as 10 without adding too_Timplex servo control mechanism. Based on their achieved hardware BER of 10-6, overall BER of 10 is anticipated with the help of error correction code technique.
Optical Recording Characteristics Of Hydrogen-Implanted Tellurium Films
Author(s):
A. Singh;
P. Galarneau;
E. J. Knystautas;
R. A. Lessard
Show Abstract
Optical data storage technology which has developed rapidly in the last few years has encouraged new research efforts into different materials that can be used as erasable media. Amoung various other materials, chalcogenide thin films such as selenium, tellurium and their alloys have drawn wide attention.1-4 One may use a laser beam to photothermally switch between the crystalline and amorphous phase of such materials and thus use the difference in the optical constant of the two phases to store information.
Influence Of Optical Disk And Laser Diode Imperfections On 3-D Intensity Distribution Near Focus Of The Memory Pick-Up Objective Lens
Author(s):
I. Prikryl;
L. J. Wei
Show Abstract
The basic functions of the optical memory pick-up are: (1) to focus sufficient light energy for writing, reading or erasure to a spot of roughly 1 pm diameter located on a track of a rotating optical data storage disk, (2) to provide focus and tracking error signals and (3) to provide read signal. Disk tilt, variation of optical thickness of the disk cover layer, laser diode astigmatism and defocusing due to focus servo loop offsets caused by initial misalignment, material thermal expansion, laser diode thermal wavelength drift, age, etc. result in changes of the intensity distribution projected onto the disk surface and affect information spot forming, the amplitude of read signal, or erasure efficiency. The extent to which these imperfections affect the focused beam and consequently, the size of a written spot and the read signal is numerically investigated.
Optimization Design Of An Astigmatic Focusing System
Author(s):
Zhang Wei;
Lu Da;
Wu Minxian;
Chin Kou-Fan
Show Abstract
The astigmatic off-focus detection is one of the commonly used automatic focusing techniques. Generally, the astigmatism is introduced by means of cylindrical lens.Take the optical disc autofocusing system as an example0), the light spot on the detector, which normally is circular, will suffer elliptical deformation if the information plane of the disc changes its distance from the objective (see Fig.1). The amounts of light impinging on the four quadrants are no longer equal and a difference signal can be derived
The Soliton Laser: A Simplified Model
Author(s):
P. A. Belanger
Show Abstract
The soliton laser oscillation, as described by Mollenauer and Stolenl, is achieved by reinjecting into the main cavity a pulse that has been compressed after its passage through an optical fiber. This pulse, being extracted from the preceding mode locked pulse, is thus coherent with the existing pulse in the laser cavity. Moreover, the parameters are adjusted in order that the reinjected pulse coincides precisely with the laser pulse.
Dark Soliton Pulses. Generation And Propagation Through Single Mode Fibers At A= 0.6 µm
Author(s):
Ph. Emplit;
J. P. Hamaide;
F. Reynaud;
A. Barthelemy;
B. Colombeau
Show Abstract
Picosecond pulses propagating through single mode optical fiber suffer dispersion and self phase modulation below Raman threshold. Their evolution is theoretically described by the nonlinear Schrodinger equation. This equation is known to possess a discrete set of stable analytical solutions called solitons .(1, 2).
Stability Of Mode-Locked Lasers To Linear And Nonlinear Perturbations
Author(s):
M. Morin;
M. Piche;
R. Tremblay
Show Abstract
Phase-locking of the modes of a laser results in the emission of a train of short pulses. These pulses are essential for basic physics experiments as well as for electronic and opto-electronic technologies. The most reliable method to phase-lock laser modes is active mode-locking, achieved by inserting a phase or amplitude modulator in the laser cavity. In this paper, we study the stability of actively mode-locked lasers to linear and nonlinear perturbations.
Superradiant Pulse And Amplified Spontaneous Emission From The Flash Pumped Atomic Iodine System Undergoing The Laser Transition Of [sup]2[/sup]P [sub]1/2[/sub]- [sup]2[/sup]P[sub]3/2[/sub]
Author(s):
Jae Won Hahn;
Gyu Ug Kim;
Sang Soo Lee
Show Abstract
Recently, Jaroszynski and King found superradiance(SR) occurring in photodissociatively created systems using NaI and n-C3F7I moleculesl) , and Hahn and Lee have performe2)d the amplified spontaneous emission(ASE) experiment in an iodine photodissociation laser(IPL) amplifier . In general, to observe SR experimentally, a very short intense pumping pulse of which FWHM is about a few tens of nanoseconds, is used for making a totally inverted system. But in this work, the amplifier is pumped with conventional flashlamps of FWHM=3us, yet we have detected a output pulse which is a superposition of ASE and SR. The temporal behaviour of the pulse is investigated in detail, and the experimental results are compared with theoretical results.
Actively-Quenched Silicon Avalanche Photodiode Detectors For Photon Correlation Measurements
Author(s):
R. G.W. Brown;
R. Jones;
J. G. Rarity;
K. D. Ridley
Show Abstract
Until recently, photon-counting photomultipliers have been standard detectors for photon correlation measurements in the study of macromolecules, velocity and speckle l) etc. We have examined in detail the performance characteristics of silicon avalanche photodiodes (AM's) as alternative detectors for such studies 2,3).
Field Correlations And Spectra Produced By Locally Incoherent Primary Sources
Author(s):
J. T. Foley;
G. S. Agarwal;
E. Wolf
Show Abstract
In this paper the correlation properties (in the space-frequency domain) and spectra of wavefields produced by a class of sources which occupy a finite domain and are locally incoherent, i.e., by finite sources which are correlated only over distances which are small compared to the wavelengths of interest, are investigated. For points inside the source the complex degree of spectral coherence and the spectrum of the field are investigated. For points in the far zone of the source the spectrum of the field is studied.
Test Of The Fresnel Relations For A Chiral Medium
Author(s):
M. P. Silverman;
T. C. Black
Show Abstract
Natural optical activity is a uniquely sensitive probe of molecu-lar stereochemistry capable of yielding fine details of the three-dimensional structure of molecules in their individual environments. It is ordinarily manifested by optical rotation or circular dichroism of light that has propagated through a chiral medium. Observation is consequently limited to transparent samples or to samples that can be made transparent through dilute solution.
Two Point Resolution Criterion For Multi-Aperture Telescopes
Author(s):
Steven M. Watson;
James P. Mills;
Steven K. Rogers
Show Abstract
The next generation of large telescopes may involve designs which use multiple parallel apertures. The two-point resolution criteria (Rayleighl or Sparrow2) is the classic way of comparing telescopes. However, there is no standard two-point resolution criterion for multi-aperture systems. The authors propose a new resolution criterion which accounts for the unique characteristics of a multi-aperture impulse response. The impulse response of a multi-aperture system is characterized by a primary peak and side-peaks which are dependent on the spacing of the individual subapertures which comprise the multi-aperture system. As the spacing between the subapertures increase, the intensity of the side-peaks increase. To illustrate the difference between two-point source diffraction patterns from a single aperture and a six-aperture system of an equivalent diameter, refer to Figure 1.
Optimization Of The Axial And Extra-Axial Strehl Ratio In Aberrant Systems By Apodization Filters
Author(s):
J. Campos;
M. J. Yzuel
Show Abstract
The effect of the amplitude and phase filters on the response of the optical systems with residual aberrations has been studied during the last years i.e. 1,2) . In these works the results for axial and extra-axial aberrations are considered separately. A study of the effect of the filter on the optimization of the axial and extra-axial images has not been carried out as a whole in tese papers.
Iterative Synthesis Of Fourier Transform Pairs In Computer Holography
Author(s):
F. Wyrowski;
O. Bryngdahl
Show Abstract
Computer-generated Fourier holograms (CGH's) can be used to carry information in data storage, display, and incoherent image processing situations. The reconstructed intensity I(x,y) represents the data in case of data storage and display and the desired impulse response function in case of incoherent image processing. The Fourier transformation (FT) fr(v,p) of a complex amplitude u(x,y) = VI(x,y) exp(i0(x,y)) is the basic distribution needed to produce CGH's which reconstruct the intensity I(x,y). The phase 0(x,y) of the complex amplitude u(x,y) does not affect the intensity I(x,y) and in this sense it is a free parameter. This freedom can be used to increase the diffraction efficiency and the redundancy of the CGH and to reduce quantization errors introduced by the hologram generation process.A powerful method to achieve these aims is " pp smooth the power spectrum of u(x,y) by superimposing a suitable phase distribution onto 1u(x,y)1.However, it is not possible to use any arbitrary phase distribution. The resulting complex amplitude has to be bandlimited because the size of the CGH is finite. Disregard of this requirement will lead to defects in the reconstructed intensity, e.g., the introduction of a random phase (diffuser) in computer and optical holography leads to speckles in the reconstruction. We want to use an iterative FT algorithm') to obtain a bandlimited complex amplitude u(x,y) with a smooth power spectrum. Such a complex amplitude is the basis for elimination of speckles in the reconstructed image.
Characteristics Of Computer Generated Hologram By Direct Laser Recording
Author(s):
Koki Sato
Show Abstract
When the computer generated hologram ( CGH ) is applied for the optial memory, it is necessary to make CGH in real time and to reconstruct the image in the original place. For this purpose some kinds of direct laser recording system for making CGH were proposed by now but these procedures were so complicated that it was difficult to construct these systems. On the other hand electron beam recording methoewas proposed for the direct recording of CGH. In this case special setup such as the vacuum equipment is necessary to use the electron beam, so it is not easy to make CGH and to reconstruct the image in the original place.
A Novel TFEL/LC Display Device
Author(s):
A. Fuh
Show Abstract
Recently, a new electro-optic effect involving a liquid crystal compound was introduced by several groups- 3). The key material is a nematic liquid crystal (NLC) dispersed as microdroplets in a polymer matrix.
3-D Light Distribution Within The Focused Spot By Large Aperture Objectives For Optical Data Storage
Author(s):
Ruan Yu;
Wang Congjun;
Lu Naiguang
Show Abstract
Since its emergence in early 1970s, optical disk has been playing a main role in data storage. The most attractive features of the optical disk such as high information density and large storage capacity are all made possible by the large aperture recording objective. As the aperture of the objective increases, however, one problem arises in studying the exact light distribution within the focused spot--the conventional scalar diffraction theory would introduce intolerable error to the results. Therefore, the vectorial properties of light must be taken into consideration. For this purpose, we developed 3-D optical diffraction integrals for focusing optical systems with a different method from those used by H. Hopkinsl) AND B. Richards and E. Wolf2). This method is simple and has proved effective in dealing with systems with and without aberrations.
Fiberoptic Active Elements For Optical Computing
Author(s):
M. P. Petrov;
V. I. Belotitskii;
E. A. Kuzin;
V. V. Spirin;
A. A. Fotiadi
Show Abstract
We report our recent results which show that stimulated Brillouin scattering (SBS) and stimulated Raman scattering (SRS) in an optical fiber can be successfully used for development of a number of elements for optical data processing, such as a logic gate, a commutator, an amplifier etc.
Optical Signal Processing Using The Surface Acousto-Electro-Optic Effect
Author(s):
D. M. Litynski;
P. Das
Show Abstract
The diffraction of light through the acousto-optic (AO) and electro-optic (EO) effects provides the mechanism for optical signal processing and has been investigated by several authors [1]. However, the same crystals can often be used for either effect which offers the possibility of simultaneous acousto-electro-optic (AEO) interaction and points to an additional signal processing capability. Studies have been done in bulk wave devices and in the Raman-Nath regime of surface acoustic wave (SAW) devices [2]. We present new results in the Bragg regime of SAW AEO devices.
Dynamic Decoding For Shadow-Casting System
Author(s):
M. H. Wu;
Y. Suzuki
Show Abstract
The shadow-casting system is a method of performing optical binary logic operation in parallel for two of two-dimensional variables. The basic principle and operationalprocedures for this system have been described in detail in a series of papers by Tanida and Ichiokal-5). The system entails 3 key steps to accomplish an intended binary logic operation. These steps are:
Performance Of Optical System Employing Polarisation Masks Under Partially Polarised Light Illumination
Author(s):
S. D. Gupta
Show Abstract
It sometimes becomes necessary to modify the imaging characteristics of an optical system to achieve better performance for certain applications. In the present paper, the modifications in the imaging characteristics achieved by employing linear and circular polarisation masks at different zones of the optical system is considered. This modification technique is comparatively easy to realise into practice and is based on the principle that if the pupil transmission function of an optical system is made polarisation dependent, then the contribution to the diffraction pattern from different zones will be different. In case of linear polarisation masks, apodisation has been achieved by placing linear polarisation masks at different orientations in the zones while for circular polarisation masks, it is achieved by placing circular polarisation masks with different attenuation ratios. Moreover with an analyser at the image plane, the performnce may be continuously modified.
Dynamic Properties Of Nonstationary Speckled Images Transmitted By Laser Light Through An Image Fiber
Author(s):
N. Takai;
S. Kimura;
T. Asakura
Show Abstract
Low-loss silica glass image fibers suitable for long-distance image transmission have recently been developed and expected to become a powerful tool for monitoring the object existing under specific circumstances, such as high pressure, high temperature and heavy radiation fields". An image fiber has a closed-packed structure consisting of a large number of elementary fibers which typically have a core of several microns and a cladding of ten or more microns in diameter. An object image is transmitted independently through each elementary fiber. Therefore, the incoherent light from a thermal source is used in usual cases for illumination. However, if the laser light that is coherent in a temporal sense is used instead of the incoherent thermal light, the laser speckles appear over the transmitted image due to random interference between waves emerging from different elementary fibers. In this report, the dynamic statistical properties of image-plane speckles produced through an image fiber by a moving non-stationary object are investigated.
Monomode Optical Fibre Dynamic Light Scattering
Author(s):
R. G. W. Brown
Show Abstract
Dynamic light scattering (DLS) is a well established, widely practised research technique for the non-invasive study of macromolecules such as proteins, enzymes and viruses. Commercial apparatus is readily available at considerable size and cost. Recently, various multimode optical fibre DLS schemes have been published2), but in this paper we explore the potential of monomode optical fibre DLS.
Heterodyne Fiber-Optic Gyroscope Using Orthogonal Polarizations With Different Frequencies
Author(s):
Y. Imai;
H. Koseki;
Y. Ohtsuka
Show Abstract
A heterodyne detection scheme used in a fiber-optic gyroscope (FOG) provides a stable scale factor and a wide dynamic range in a phase output. 1) The output, however, is open to the influence on environmental fluctuations, since the output contains a bias phase caused by a frequency difference between two counterpropagating beams in a fiber coil. In order to overcome this, the heterodyne FOG has been improved by using a reference beam different in frequency from that of the counterpropagating beams of an identical frequency,213) or by shifting the frequency in one of the counterpropagating beams after emerging from the fiber coi1.4) However, these approaches lead to alternative problems such as Rayleigh backscattering or a phase fluctuation caused by a frequency shifter (AOM). In this paper, we present a novel approach capable of canceling inherently the noise sources appeared in the conventional heterodyne FOGs.
Metal Dielectric Films As Materials For Infrared Hollow Fibers
Author(s):
N. Croitoru;
J. Dror;
E. Goldenberg;
D. Mendlovic;
S. Ruschin
Show Abstract
In recent years, because of important applications in medicine and communications that require fibers of a wavelength longer than 2 μm, most intensive investigation of materials for this purpose has begun. An important group of materials that we have investigated is that of chalcogenide glasses1'2' suitable for drawn fibers that can be used for transmission of the CO2 laser radiation (10.6 um). This material, however, has some disadvantages preventing it from practical application. We have devised a new type of hollow fiber made from plastic tubes and covered on the inside wall with metallic and dielectric films. This double film enables the fiber to have a very low attenuation even when being bent. A theoretical ray model that simulated the laser beam propagation through a hollow fiber covered with these films has been made to devise the waveguide behaviour. This model took into account parameters such as: radius of curvature (R); cross-section radius (r); influence of dielectric film (on top of the inner metal film), and influence of light polarization.
A Scanning Wide-Angle Michelson Interferometer For The Visible Region
Author(s):
Z. J. Lu;
R. A. Koehler;
W. A. Gault;
F. C. Liang
Show Abstract
The construction of scanning wide-angle Michelson interferometers using existing field compensation methods1)2) is difficult and costly, especially in the visible region 3)4). The new stigmatic field-compensation method5)used in the current scanning wide-angle Michelson interferometer, overcomes the barrier of the high degree of synchronized motions that are required by Mertz's First Method- 5). A dynamic alignment system was also developed for the instrument to keep the two mirrors of the interferometer parallel during a scan. The operation of the instrument is controlled by a computer in real time.
Doppler Imaging With Field-Widened Michelson Interferometers
Author(s):
G. G. Shepherd;
W. A. Gault;
R. H. Wiens;
W. Ward
Show Abstract
Under the sponsorship of the Space Division of the National Research Council, Canada is building two wide angle Michelson interferometers for the imaging of upper atmospheric temperatures and winds using the naturally occuring airglow and auroral emissions. The Wide Angle Michelson Doppler Imaging Interferometer (WAMDII) is built to fly on the Space Shuttle. Launch time is at present undeter-mined. The Wind Imaging Interferometer (WINDII) will fly aboard NASA's Upper Atmosphere Research Satellite, expected to be launched in 1991.
Digital Measurement Of Dispersion Curves From White Light Interferograms
Author(s):
C. Sainz;
G. Tribillon;
J . Calatroni
Show Abstract
We present an experimental system which allows recording of the dispersion curve n= n(σ) of a sample,n being the refractive index and a the wavenumber . The system consistsicin a Michelson interferometer in one of whose arms the sample is placed. A white light source ( Xe 150 watt ) is used to illuminate the interferometer. A spectroscopic de-vice is placed in series with the interferometer in order to get the channelled spectrum produced by the sample. The intensity distribution 1(a). 21o(1+cos2rane) stores the function n(a) .
Realizing Pseudocolor Image By Using Reflectance Property Of Grating Encoded Plate
Author(s):
Mu Guo-Guang;
Ding Pei-Jun;
Fang Zhi-Liang
Show Abstract
The Tepanism of photogrphio relief images of silver halide plate and its applications have been reported ' 1. In this paper we describe an interesting phase modulation phenomenon of the reflected light from the relief images and propose a new pseudocolor encoding technique with a white-light reflective processor. It consists of two main steps: 1) a grating encoded plate of a blaok,white image should be made by contact printing; 2) the pseudocolor image is obtained by placing the encoded plate at input plane and spatial filtering at Fourier plane in a reflective white-light processor. This technique offers the advantage that the colors of the output image vary with the incident angle of the illuminating light.
Pattern Recognition With Incoherent Holographic Correlators
Author(s):
I. Glaser;
Michael Cohen;
V. Weiss;
H. Bernstein;
A. A. Friesem
Show Abstract
Pattern recognition with spatially incoherent holographic correlators is described. Their performance is improved by optimizing the optical layout and preprocessing the reference image. Compared with coherent holographic correlators the incoherent ones are much more tolerant of mechanical errors, optical aberrations and dust; also, they work without spatial light modulators.
Optical Polynomial Vector Processing
Author(s):
Shing Hong Lin;
Thomas F. Krile;
John F. Walkup
Show Abstract
Polynomial processing can be applied to a number of potential applications, including general nonlinear operations using the Volterra series, eigenvalue computations via solutions to polynomial characteristic equations, pattern recognition, and polynomial neural networks[1]. Since most of these applications use vector-valued inputs (i.e., multiple-variable inputs), an optical polynomial vector processor is investigated and implemented here.
Invariant Pattern Recognition Using Fourieir-Mellin Descriptors Of Images Spectra
Author(s):
Yunlong Sheng;
Claude Lejeune;
E. H. Arsenault
Show Abstract
Geometrical moments are attractive for image-distortion invariant pattern recognition. Orientation scale and position of the image are readily determined by its moments. Rotation-, scale- and shift-invariant features can also be extracted using moment invariants. Some optical methods for generating image moments have been proposed and a single-chip VLSI implementation for generating real-time 2-dimensional image moments has recently been achieved. The applications of the moment method will be further expanded.
Optimization Of Fiber-Coupled Type Laser : Application To A Co2 Laser
Author(s):
Heihachi Sato;
Shirou Kamioka
Show Abstract
A high power laser available at midinfrared(MIR) region is much expected for machinery, welding and medical uses,combining with optical fibers transparent at the corresponding wavelengths. In order to couple intense beam into a tiny fiber effectively, extremely careful alignment of optics such as lens and mirror is indispensable in a conventional scheme. Thus, one of the authors has proposed a new method in which the optical fiber is directly inserted into the coupling-hole of the resonator mirrors in intra-cavity laser, and called it the fiber-coupled or Dynamite laser.1)However, since the coupling hole on the mirror disturbs the field distribution by itself, it is very important to take account of the field disturbance for optimum coupling to provide the maximum output power.
Transient Properties Of Small-Signal Gain In A Fast Axial-Flow Type Co[sub]2 [/sub]Laser Amplifier
Author(s):
Eiichi Tsuchida;
Heihachi Sato
Show Abstract
A fast axial-flow type (FAF) CO2 laser is much expected for applications towards machinery, welding and medical uses. So far, extensive efforts have been devoted into enhancement of its oscillation power and efficiency from rather practical point of view.1)Its laser parameters such as small-signal gain, saturation irradiance and linewidth have not been investigated too much in detail. In the present paper we shall, thus, report the theoretical analysis of transient properties in small-signal gain, which have been experimentally observed for a FAF CO2 laser amplifier modified from the CW 500 W class oscillator. Taking account of thermal diffusion, dissociation of CO2 molecules and saturation effect into the gain constant, temporal properties of the small-signal gain and output power will be theoretically treated, and the experimental results will be explained by the theoretical estimates.
Doped Alkali Halides As Active Media For Tunable Solid State Laser
Author(s):
P. Fabeni;
R. Linari;
G. P . Pazzi;
A. Ranfagni
Show Abstract
Since the early days of the laser discovery, wideband optical gain in any region of the electro-magnetic spectrum has suggested to the spectroscopists immediate applications. Laser tunability, presently offered by a few laser types, allows for an easy radiation-matter interaction, useful for linear and non-linar spectroscopy. On the other hand wideband tunable lasers in the visible such as dye lasers show photochemical degradation (bleaching) which reduces to some extent their applications. Furthermore the ultraviolet region is covered essentially by second-harmonic generation with a large expense of intensity. These considerations justify for a search of other types of laser materials capable of wideband optical gain in the visible'and uv regions, and not suffering the over-mentioned limitations.
Mode Ahd Supermode Calculations For Diode Lasers And Arrays Wits Variable Reflectivity Or Phase-Conjugate Mirrors
Author(s):
N. McCarthy;
Y. Champagne
Show Abstract
Diode lasers and arrays are the most promising coherent sources for wide scale applications such as fiber-optic communications and optical pumping of other lasers. Many sophisticated fabrication techniques have been realized to produce diode lasers providing an output beam with a narrow, single-lobe far-field pattern. Our proposal consists in modifying the output facet properties of a common commer-cial diode laser to improve the optical quality of the beam. Numerical simulations was performed to predict the effects of replacing the standard output facet by a spatially varying reflectivity facet, a phase-conjugate and a spherical facet.
Modelling Of Atmospheric Propagation Of High Energy Laser Radiation
Author(s):
Naresh C. Mehta;
Robert S. Benson
Show Abstract
There recently has been renewed interest in the non-linear effects of atmospheric propagation of High Energy Laser (HEL) radiation. Three important physical phenomena affecting the HEL propagation are optical turbulence, thermal blooming and Stimulated Raman Scattering (SRS). Not only do these phenomena individually cause distortions in the HEL wavefront passing through the atmosphere, but a non-linear interplay between these effects has a larger impact on the HEL wavefront degradation. For example, wavefront aberrations caused by a turbulent atmosphere produce non-uniform heating leading to scintillations which are difficult to correct with conventional adaptive optics systems. No systematic study has been reported of these non-linear effects and particularly of their mutual interactions.
Dynamic Holography
Author(s):
S. I. Stepanov
Show Abstract
The history of dynamic holography is very short, but nevertheless several specific periods of its development can be distinguished. The main purpose of this paper is to illustrate them using the experimental evidence obtained for photorefractive crystals and to give an idea of salient properties of photorefractive crystals related to their use in dynamic holography.
Nonreciprocal Effects In Photorefractive Materials
Author(s):
D. Erbschloe;
L. Solymar;
J. Takacs;
T. Wilson
Show Abstract
Two wave mixing in photorefractive materials has been widely investigated in the last decade. In particulor it has been shown that noneciprocal transmission may be obtained using the reflection geometry". and it has been proposed o that nonreciprocal phase shift should be achievable.
Electrooptic Properties Of Langmuir-Blodgett Multilayers
Author(s):
J. C. Loulergue;
M. Dumont;
Y. Levy
Show Abstract
The linear electrooptic properties of centrosymmetric and noncentrosymmetric Langmuir-Blodgett (LB) multilayers of an azobenzene derivative (DPNA) are determined by attenuated total reflection technique.
Density Matrix Treatments Of The Four Level System For Photodarkening Kinetics In Amorphous AS2S3
Author(s):
Chong Hoon Kwak;
Seung Gol Lee;
Sang Soo Lee
Show Abstract
Recently, photoinduced effects such as photodarkening in amorphous chalcogenide thip ,films have received renewed attention, because of their potential applications in phase conjugation kl), optical holography (2) and other related optical devices.(3) In this work, the density matrix formalism is adapted to explain the complicated time and intensity dependent nonlinear optical absorption changes in amorphous chalcogenide AS2S3 thin films.
Temporal Instabilities Of Spatially Stable Counterpropagating Vector Fields
Author(s):
Alexander L. Gaeta;
Robert W. Boyd
Show Abstract
The simple optical interaction of two counterpropagating waves in a nonlinear medium with no exter-nal feedback has been shown to exhibit complicated behavior. Silberberg and Bar-Joseph [1] have shown that that in the scalar approximation the output of two waves counterpropagating in a nonlinear Kerr medium whose response time is approximately equal to the transit time of the light through the medium can exhibit oscillatory and chaotic behavior in time. The origin of this instability arises from gain at the sidemodes of the two strong waves which in turn experience distributed feedback (DFB) due to the standing-wave pattern created by the two strong waves. The steady-state behavior of the polarizations of counterpropagating waves in a nonlinear Kerr medium has been shown to be quite complex [2,3]. However, for an isotropic Kerr medium there exist in steady-state four polarization configurations for the two beams that do not change upon propagation through the material [4]. Wabnitz and Gregori [5] have shown that only two of these these eigenpolarizations will be spatially stable in steady-state; the stable polarizations are those in which both fields are linearly polarized with parallel polarizations and in which the fields are circularly polarized and corotating. In this paper we will demonstrate that one these spatially stable eigenpolarizations is actually temporally unstable.
The Application Of Spatial Light Modulators To Real-Time Opto-Electronic Inspection Of Manufactured Glass Jars
Author(s):
R. Cormack;
K. M. Johnson;
W. T. Cathey;
F. Dolder
Show Abstract
Defects in machine-blown glassware, known as stuck glass, are caused by flying glass particles falling into red-hot bottles on an assembly line during manufacturing. These defects can potentially become dislodged when removing food from the glass container. Current inspection machines easily locate gross defects which are larger than the mold marks and lettering on the bottom of glass jars. Inspection of smaller defects, on the order of several mm, is generally performed manually. In this paper we present a real-time opto-electronic inspection machine which uses successfully images small glass defects while suppressing the image of the jar.
Superresolution By Differential-Scanning
Author(s):
A. Glindemann
Show Abstract
We are proposing a new principle of measurement that repeals the restriction in resolution caused by the scanning slit. With the boundary condition that scanning is started or ended in a region of known signal level the resolution is limited by the step width only. As the step width may be arbitrarily small the only limitation of resolution is given by the detector sensitivity. In our experiments the resolution was enlarged by a factor of 10 compared with a normal scan process.
The Cormack - Walsh Transform
Author(s):
Joseph Ben Uri
Show Abstract
Recent developments in computerized tomography (CT), be it by means of X-rays or nuclear magnetic resonance (NMR), was possible due to very thorough mathematical groundwork done by many authors. The great importance of CT and NMR systems especially for medical purposes is obvious.
Multiple Imaging Using Two 1-D Phase Gratings With Uniformly Diffracted Spots
Author(s):
Zhen Wu;
Ping Zhang;
Yu Ruan
Show Abstract
Optical system that can produce multiple images of an object are specially useful for the microelectronics industry. It may replace costly and time-consuming step and repeat cameras. For this kind of optical system, the major problems are in achieving a high resolving power in images that can be a large size while keeping the distortion less than 2 %. Meanwhile, the positions of the multiple images in the array must be within submicron tolerances.
Fourier-Transform Spectral Imaging With Variable Magnification
Author(s):
Kazuyoshi Itoh;
Takashi Inoue;
Yoshiki Ichioka
Show Abstract
Recently an interferometric method has been propped for studying simultaneously the spatial and spectral structures of polychromatic incoherent objects '. Since the spatial and spectral information of an object is dealt with in a unified and efficient manner, the method (FI'SI) is attractive in both theoretical and practical view points. The FTSI is applicable to diverse fields such as astronomy, remote sensing, biology, and material sciences. We demonstrate in this paper a new and simple technique for utilizing full capacities of the method and consider SNRs and other related parameters.
Effects Of The Atmospheric Air In Interferometric Distance Measurement Using A CO2 Laser
Author(s):
Hirokazu Matsumoto
Show Abstract
At present, the high-accuracy measurements of absolute distances up to several tens of meters are required in the many fields of science and industry. Recently, we have developed a new infrared laser interferometer (SIDM) which uses a 10.6-μm-0O2 laser as a light source [1]. In this wavelength region, the laser light is not very absorbed by the atmospheric air and the CO2 laser can emit many laser lines which are necessary for multi-wavelength interferometry. However, for determining the distance with an accuracy of better than 1x10-7, the refractive index of air under length measurement is required with a high accuracy. In this paper, the effects of the atmospheric air is described on the infrared interferometric length-measurement.
Highly Sensitive Optical Sensings Using A Phase Detection Of Young's Fringes
Author(s):
Suezou Nakadate
Show Abstract
An equidistant and straight fringe pattern, for example, Young's fringes, is a most fundamental and simplest fringe pattern in optics, but the measurements of the fringe profile, spacing, and its movement allow us many instrumentations. In optical sensings, various types of fiber sensors have been presented for detecting physical perturbations such as displacement, electric and magnetic fields, pressure, temperature, rotation velocity, and so on.l) Hocker used Young's fringes in a fiber-optic Mach-Zehnder interferometer and measured a fringe shift of an interferogram, which is proportional to a phase change of the light.2) However, a general method for detecting the fringe shift was not presented, which may provide highly sensitive optical sensings similar to that using a heterodyne detection. In this paper, a method for detecting a shift of Young's fringes is presented, which is based on an arctangent calculation with Fourier cosine and sine integrals of the fringes. In the phase detection, phase errors caused by a spatial truncation of the fringe, a nonlinearity of a detector, a sampling of the fringe, and a random intesity noise are analyzed theoretically. To demonstrate the present phase detection, experimental results for measurements of displacements of a PZT device are presented using non-polarized and polarized Michelson interferometers. As applications of the present phase detection, highly sensitive optical sensors for pressure, temperature, and displacement are proposed.
Moire -Holographic Analysis Of Bent Plates With Non-Uniform Thickness
Author(s):
G. DI Chirico;
F. Ginesu
Show Abstract
The moire-holographic technique utilized for this investigation basically consists of filtering, in a Fourier optical system, pairs of wave-fronts diffracted by the model grating and of reconstructing the interference fringes frozen in the holograms obtained by double exposure, i.e. before and after the defor-mation [1],[2]. It has been shown that moire holograms can even be reconstructed with white light; furthermore, optical differentiation of the fringes is readily accomplished, during the reconstruction process, by direct observation of the shapes taken on by the strain components [3]. This paper describes a new extension of moire-holography to the analysis of plates with non-uniform thickness, in particular orthotropic plates. It is known that with transparent models of variable thick-ness, through which a beam of light passes, it is necessary to reconstruct the flatness of the optical surface by immersing them in auxiliary liquids with corresponding refraction indices. The authors observed, however, that moire-holographic analysis resolves this problem also, simply and rapidly, provided the surface containing the grating is uniformly flat (Fig.l).
Real-Time Interferometry By Degenerate Four-Wave Mixing And Holography In Eosin Film
Author(s):
K. Nakagawa;
H. Fujiwara
Show Abstract
Recently there has been some interest in the phase conjugation by the degenerate four-wave mixing in organic materials1) Xanthene dyes such as eosin, erythrosin and fluorescein, having a strong ab-sorption at the wavelengths of an Arion laser and a relatively long lifetime of their triplet states, can generate cw phase conjugate (PC) wave at the intensity of less than 0.5 w/cm2. On the other hand, these dye-doped films have been used as holographic recording materials for self-development because of photochemically induced changes in absorption and/or refractive index under the action of light2),3) We revealed that the xanthene dyes fixed in gelatin can generate simultaneously the PC waves by not only the DFWM process with a fast response time (5msec) but also the holographic process with a slow response time (40 sec) and then can store the light information as a hologram4)'5).
Advances In Integrated Optics
Author(s):
R. Normandin;
D. C. Houghton;
M. Simard-Normandin
Show Abstract
Advances in optically nonlinear materials and single mode fiber technology have led to a renewed interest in integrated optics. For coherent communication fiber systems, integrated optics offer the possibility of an entirely monolithic implementation with narrow linewidth lasers, modulators, detectors, frequency shifters and optical switches. With III-V semiconductors, optical functions and associated electronics for drivers and detectors can be on the same opto-electronic chip. Recent advances in nonlinear integrated optics also hold promises for applications in ALL-OPTICAL processing and interfacing of fiber signals. Power dependent nonlinear couplers, nonlinear distributed feedback gratings, optically tunable filters, bistable integrated gratings and logic gates are all possible applications of integrated optics in communication systems resulting from a better understanding of nonlinear guided mode behavior. New organic (such as liquid crystals) or semiconductor materials (multiple quantum wells (MQW) for example) in an integrated optics context may provide the properties needed to make all-optical processing viable in the next generation devices. As an example we present some of our work on all-optical modulation and logic gates in silicon based channel waveguides at wavelengths of 1.32 and 1.55 micrometers. PicoJoule switching energies and subpicosecond initiation times make these waveguide devices attractive for single fiber systems since the lack of resonators ensures good stability in actual operation.
Optical Bistability In Corrugaten Waveguides : Lowering Of The Threshold Intensity By The Use Of Resonant' Excitation Of Surface Waves
Author(s):
H. Aichouayri;
P. Vincent;
M. Neviere
Show Abstract
It has been previously established [1] on a theoretical basis that a grating ruled on a nonlinear (Kerr) material and lighted with a T.E. polarized plane wave can have a bistable behavior inside a convenient range of incident power and incidence angle. We establish here that a similar phenomenon occurs for T.M. polarization [2] for which delocalized surface plasmons can be resonantly excited. We study here the merits of both surface plasmon resonance and guided wave resonance inside a corrugated waveguide to increase the local field and thus, to decrease the threshold intensity necessary for bistable operation.
Self-Pulsing in Prism Coupling into Planar Absorbing SiO2-T1O2 Waveguides
Author(s):
V. Briguet;
P. Pirani;
W. Lukosz
Show Abstract
Self-pulsing optical systems produce at constant input power P an output power PR (t)varying periodically with time t. Self-pulsing (SP) in nonlinear Fabry Perots and hybrid systems is well known. We reported the first known observation of SP in prism coupling into planar waveguides [1]. Recently we identified the physical mechanism of the SP and we shaved that SP occurs in a wider class of waveguide materials [2]. We also demonstrated that the same prism-waveguide system can exhibit SP, optical bistability (0B), and a special form of bistability (0B/SP), where at the same constant input power P the output power P is either constant in time or self-pulsing. In the present paper we present more experimental material and discuss the physical effects determining the system's behaviour.
Optical Nonlinear Waveguiding Structures Based On Thin Films Of Glass Doped With Cds[sub]X[/sub]Se[sub]1-x[/sub]
Author(s):
H. Jerominek;
S. Patela;
Z. Jakubczyk;
R. Tremblay;
C. Delisle
Show Abstract
A new class of materials, three dimensional microscopic crystals of CdSxSel_x grown in the interior of a silicate glass matrix1 has been emerging with great promise for application in room temperature nonlinear signal processing, based on guided-wave or etalon devices. Semiconductor-doped lasses commercially available as color-glass filters combine relatively large nonlinearity (n2 = 10-1' m2/W) and rapid response time in the picosecond region (T < 10-11 s). Evidence of quantum size effects both at room temperatures2 and low temperatures3 has been also reported.
Simulation Of Integrated Optical Devices Over An Extensive Wavelength
Author(s):
Wei - Yu Lee;
Way-Seen Wang;
Yuan-Kuang Tu
Show Abstract
A simpler but very actural formula is used in this paper to get the refractive indices of LiNb03 from Ti concentration and input optical wavelength. This method combined with beam propagation method and effective index method can be used to simulate Ti-indiffused LiNbO, integrated optical devices over an extensive wavelength. In this d paper, we simulate ome Mach-Zehnder modulators and display the field distribution patterns between different input optical wavelengths.
The Design Of Three-Dimensional Optical Interconnection Networks Using Ferroelectric Liquid Crystals
Author(s):
Joe Shamir;
Kristina M. Johnson
Show Abstract
Optical computing systems offer potentially three advantages over electronic computing systems: speed, parallelism and highly interconnected architectures. Optics is well suited for performing interconnections because photons pass through one another without interacting. Therefore the density of interconnections in optical implementations can be quite high compared to those achieved in electronics (1). This is particularly exciting for neuromorphic computers, whose architectures require a large number of interconnections between processors, and for building programmable optical crossbars for high speed communications.
Phase-Space-Like Constraints On Optical Networks
Author(s):
I. M. Bassett
Show Abstract
Consider a linear, lossless, passive optical system, with light flowing steadily in and out (fig. 1). There are constraints on the power flows which follol)w from (i) conservation of energy, (ii) reversibility, (iii) Liouville's theorem, conservation of gtendueor, more generally, unitarity.
Similar-Paths Free-Space Optical Interconnections
Author(s):
M. E. Marhic
Show Abstract
Free-space optical beams are increasingly being considered to interconnect arrays of processors [1]; for instance, researchers have proposed such optical means to implement the perfect shuffle [2,3,4]. So far the main aspect which has been studied is connectivity, i.e. how to achieve a particular interconnection pattern with adequate signal-to-noise ratio, and little attention has been paid to such aspects as time delays and beam diffraction, which can play major roles in the design of coherent optical processors [5,6,7].
3-D Optical Interconnection Networks
Author(s):
Alexander A. Sawchuk
Show Abstract
Introduction, Network Design and Applications - This paper describes 3-D dynamic optical interconnection networks that interconnect a 2-D array consisting of N x N input lines with a similar 2-D array of N x N output lines. These 3-D networks make specific use of the volume (non-planar) nature of optics and permit the design of interconnections that are extremely difficult or impossible to implement with planar electronic VLSI technology.
Holographic Speckle Correlation Technique And Its Applications
Author(s):
Yan-Xun Zhou;
Rong-Cai Miao;
Yin-Ke Zhang
Show Abstract
The statistical properties and correlation properties(1,2J of speckle patterns have been extensively studied and widely used to measure the parameters of rough-surface[3,41 Asakura[51,Vorbuger and Teague (6:J and Ruff ing(71 reviewed optical measurement techniques of surface topography, including the two main groups of speckle methoda using average contrast and the degree of correlation of speckle patterns, respectively as roughness-dependent parameters, These methods are all based on the intensity properties of speckle patterns,this makes the theoretical analysis and experiment complicate and timeconsuming By comparing the holography and speckle correlation technique, we propose a technique---holographic speckle correlation technique---based on the correlation of the complex amplitudes of speckle fields and use it to measure the roughness of diffuser.
Statistical Analysis Of Optical Filtering Of Shearing Speckle Interferometry
Author(s):
Jiabi Chen;
Weizheng Zhou;
Min Pei
Show Abstract
Optical filtering is one of the basic process in photomechanics and speckle metrology, since it is the most convenient method to form high-quality visible fringes for the mesurements. In this paper, we utilize statistical approanh to analyse the formation of displacement gradiant fringes created by shearing speckle interferometry which is much different from other speckle interferometry and holo-speckle inter-ferometry discussed before. 1) 2)
Modal And Diffusion Characterization Of K+Na+ Exchanged Glass Waveguides
Author(s):
S. I. Najafi;
J. Lapierre;
R. Maciejko;
F. Seguin;
A. Champagne;
F. Blaha
Show Abstract
Glass waveguides are prime candidates for fabrication of passive integrated optical components such as couplers, tapers, multiplexers and sensors. Thorough theoretical and experimental investigation is required for manufacturing high performance devices. An example of the theoretical study of glass waveguide devices is given in the present conference (paper no. A17.2). Another example is depicted in Fig. 1.
Wavelength Dependent Analysis Of Two Branch Separating Waveguides
Author(s):
S. I. Najafi;
M. Belanger;
R. Maciejko;
J. Lapierre;
J. F. Currie
Show Abstract
Directional couplers can be formed by two identical (symmetrical couplers) or nonidentical (asymmetrical coulers) waveguides. The overlap of their evanescent field causes transfer of guided energy from one waveguide to the other. Complete energy transfer can take place if the propagation constant of modes is the same in both waveguides. Directional couplers form the basis for many devices such as wavelength filters, switches, modulators and power dividers. In this work we have analyzed symmetrical and asymmetrical slab directional couplers in glass and GaAs substrates. Here, we report on the study of performance of these devices as wavelength filters. Analysis of directional coupler switches and power dividers will be also presented in the conference.
Fabrication And Performance Tolerances Of A Thin-Film Optical Waveguide Lens
Author(s):
D. W. Hewak;
J. W.Y. Lit
Show Abstract
The optical waveguide lens is an important and basic component in many integrated optical devices, performing such functions as focussing and collimating, Fourier transformation and optical signal processing. For many applications of the optical waveguide lens, diffraction-limited performance is required. Such a stringent focussing criterion necessitates careful control of the design parameters and fabrication procedure, as well as the in situ variables which may affect the lens performance. The design and performance of geodesic lenses and grating lenses have been treated in the past. However, for the mode-index lens, among which the Luneburg lens' shown in Fig. 1, is perhaps the most common, no complete examination of the fabrication tolerances has been made.
KTiOPO4:(KTP): A New And Superior Electrooptic Material For Guided Wave Optics
Author(s):
John D. Bierlein;
August Ferretti;
Lothar H. Brixner;
Wiliam Y. Hsu
Show Abstract
Electrooptic modulation is the changing of the phase or amplitude of an optical beam by an applied electric field. This phenomenon is inherently nonlinear and can only be observed in crystals that do not have an inversion symmetry. The modulation, when effected in a waveguide, is the foundation of many guided wave optical devices, such as: Mach-tender interferometers, channel switches and directional couplers, etc. which are particularly useful for fiber optics communication)
Speckle Pattern Direct Photographic Correlation For Measuring Surface Roughness
Author(s):
M. S. Sthel;
J. J. Lunazzi;
E. N. Hogert;
N. G. Gaggioli
Show Abstract
The absolute measurement of the intensity correlation of a speckle pattern was previously demonstrated by using a photographic real-time technique (1). In this paper we demonstrate its use for the measurement of surface roughness in the 1-30,μm range, achieving many practical advantages over the two versions of a previous similar technique (2)(3).
Novel Speckle Lengthmeter Using The Double Clipping Cross-Correlation Method
Author(s):
T. Yoshida;
H. Kitajima;
N. Nakatsuka;
T. Yamashita
Show Abstract
Various methods for velocity measurements have been proposed'', as applications of dynamic speckles to metrology. Up to now we have developed a speckle velocimeter using the zero-crossing counting method. This method is used to measuring the average velocity of particles suspended in a flowing fluid2'3'. However, with this method, absolute velocity cannot in principle be measured because the zero-crossing numbers depend upon the speckle intensity. On the other hand, with the cross-correlation method, absolute velocity can be measured. In addition, high-speed cross-correlation is achieved by using double clipped speckle signals, which determine the peak position of the correlation function4'. The technique of signal clipping has been applied to many fields5'. In this paper we present a new instrument, which measures the length and the velocity of continuously moving objects, with features such as a compact and flexible optical fiber probe coupled with a laser diode, and the real-time signal processing using a double clipping cross-correlation method operated by tracking frequency.
Automatic Processing Of Speckle Photography Fringes: Comparison Of Two Methods
Author(s):
G. H. Kaufmann;
H. D. Navone
Show Abstract
Speckle photography is a powerful method for measuring in-plane displacement and surface rotation. Quantitative evaluation is performed using a pointwise approach based in the analysis of cosine square fringes which modulate a diffraction halo. The fringe spacing is inversely proportional to the displacement of the speckle pattern and the fringes are perpendicular to the displacement vector. Complete analysis of a 2-D strain field involves the measurement of the spacing and the direction of the fringe pattern on a square mesh covering the specklegram. However, this manual procedure becomes impractical when a large number of measurements are needed.
Two Paraxial Models Of An Optical System
Author(s):
Kazuo Tanaka
Show Abstract
Paraxial theory is a significant notion in geometrical optics. Among several treatments of the paraxial theory, a Gaussian brackets method is considered to be one of the most versatile toolst It was first introduced into optics by Herzbergerl) and has been developed by Tanaka2).
Double Annular Aperture Type Catadioptric System
Author(s):
Kyung Hee Hong;
Seung Yu Rah
Show Abstract
Previous researches(1)(2)disclosed two aperture modulation effects - a spatial frequency filtering effect and an aberration campansation effect. The spatial frequency filtering effect was found when aperture modulation was used with an aberration free system, and aberration compansation effect when aperture modulation was used with the large aberrations. The filtering effect was found by computing theoretical MTF, and compansation effect by computing the MTF from design data. Another important discovery was that the MTF could be improved by proper aperture modulation(3)(4). This discovery was made by measuring the MTF of a binocular objective experimentally. In this work, a double annular aperture type catadioptric system (DAA), which would have those two modulation effects, was designed to be sure the possibility of its practical use. The DAA system is composed of an outer annular aperture type catadioptric system and an inner small circular full aperture type refracting system. The ray aberration and MTF were compared those of a full aperture type refracting system and an annular aperture type catadioptric system. In this comparison, the effective f-number and the focal lengths of the three systems were the same.
Aberration Analyses Of Four-Spherical Mirror System Corrected For Three Seidel Aberrations
Author(s):
Jong Ung Lee;
Sang Soo Lee
Show Abstract
We have much interest in four-spherical mirror system as an infrared imagery because mirror system employing spherical surfaces can be fabrii4ted easily with low cost. Aplanatic Cassegrainian-inverse Cassegrainian system have been suggested. ' But the performance of the system is limited by off-axial aberrations, while the use of Germanium lens for correction of off-axial aberrations introduces inevitably chromatic aberrations, so that the four-spherical mirror system which satisfies the aplanatic conditions and is corrected for off-axial aberrations has been required. We introduce the four-spherical mirror systems corrected for three Seidel aberrations such as anastigmatic aplanat, flat field aplanat and zero distortion aplanat.
Phase Edge Effect In Amici Prisms
Author(s):
G . Rodriguez-Zurita;
R. Diaz-Uribe
Show Abstract
The Amici roof prisms are used in optical instrumentation as beam deviators and erecting image devices. These prisms are right angle prisms are right angle prisms with a roof in place of the reflecting hypotenuse plane (see fig. 1). The roof gives to the prisms its main properties. All the rays entering to an Amici prism carry out two total internal reflections, each reflection on each face of the roof. Some of these rays incide by first time on the upper face of the roof and leaves the prism after reflecting on the lower face; the other rays reflects in reversed order. We will call type one rays to the first ones, and type two rays to the second ones. This difference between the rays causes a division of the field of view, the boundary being a straight line coincident with the edge of the roof. Some authors'2'3) have investigated how the images are affected when the prism is used with polarized light and how to improve the performance of the prism. As far as we know, nobody has used these prisms as polarizing elements in an optical instrument or setup. In this work we analyze the polarizing properties of such prisms and explore their usage as a phase and amplitude edge spatial filter.
