Optical implementation of artificial neural nets (ANNs) with electronically addressable liquid crystal televisions (LCTVs) are presented. The major advantages of the proposed ANNs must be the low cost and the flexibility to operate. To test the performance, several artificial neural net models have been implemented in the LCTV ANNs. These models include the Hopfield, Interpattern Association, Hetero-association, and Unsupervised ANNs. System design considerations and experimental demonstrates are provided.

Dual nonlinear correlation (DNC) is a general operation in optical pattern recognition involving linear and nonlinear filtering methods. Computer controlled DNC processor is based on a two-step optoelectronic joint transform correlator with the power-law nonlinearities introduced in both channels. The DNC optoelectronic processor is sensitive to the value of power-law nonlinearities and can be adapted to the recognition task on various levels of discrimination capability. A CCD camera and a spatial light modulator are the two basic components of the processor that performs the DNC. Their characteristics such as saturation effect and limited number of quantization levels have strong influence on the correlation signal. In this paper we analyze the performance of the DNC processor and present some applications to textured and color pattern recognition with variable discrimination capability.

A subtracted joint transform correlator, a kind of nonlinear joint transform correlator, was investigated and constructed using only optical components. In the correlator, a holographic interferometer was used for subtracting an obstructive power spectrum from the joint power spectrum of the input image that consisted of an object pattern and multiple reference patterns. A photorefractive crystal was used as a hologram recorder. At the same time, in a hybrid nonlinear joint transform correlator, demands for the dynamic ranges of a spatial light modulator and a photometric measurement device were investigated by computer simulations.

A wavelet feature-based generalized FAJTC has been proposed to improve the performance of fringe-adjusted type JTCs in the presence of noise in the input scene. Computer simulation results are produced for test images containing single as well as multiple targets and synthetic textured input scene noise. The results illustrate the effectiveness of wavelet processing in reducing the detrimental effect of noise and enhancing pattern discrimination ability of conventional generalized FAJTCs.

A technique for realizing an all-optical non-zero order JTC has been proposed and investigated using computer simulation studies. A simple contrast reversal operation forms the basis of the proposed scheme. Effect of quantization and device nonlinearity has been studied to draw closer resemblance to a practical non-zero order image recognition system.

A simple space-variant correlation technique has been proposed using fractional correlation. Phase-only fractional correlation has been proposed for improved target discrimination and light efficiency. Design of fractional matched filters for space-variant detection of single and multiple objects has been discussed and demonstrated. The effect of object scale variation on the performance of fractional correlation has also been studied.

We propose a new technique to eliminate zero order in a joint transform correlator (JTC). In the proposed technique, the input target and reference images in a JTC are modulated by identical random phase functions. This results in a sharpening of the zero order as well as the correlation peak in the correlation phase. The zero order can be eliminated by subtracting a constant value from the joint power spectrum. The proposed non-zero order JTC has better discrimination ability than a conventional JTC. A computer simulation study is presented to support the proposed technique.

An improved optical matrix-vector multiplication is performed by convolution process. The multiplicated binary numbers are represented by on/off states of light sources and the multiplier binary numbers are recorded on a spatial light modulator. Cylindrical optics is used as free space interconnection. The convolution coefficients are recorded on a CCD array. The output of the CCD array are added in a computer to yield the result of multiplication. The operation is completely digital and needs no analog to digital conversion. Because of parallel operation in two dimensions, the processing speed is greatly increased.

A newly optically addressed spatial light modulator using a GaAs crystal plate has been developed for incoherent-to- coherent optical conversions of images. The device has the same structure as the Pockels readout optical modulator. The basic characteristics of the device were as follows: halfwave voltage, 10.5 kV; sensitivity, 0.65 (mu) J/cm² at visible light; resolution, 5.6 line pairs/mm. Its high frame rate operation (larger than 500 Hz) and high contrast ratio (larger than 700:1) were experimentally confirmed, and its applications to Fourier transform of images and joint transform correlations between images were also demonstrated.

This paper reports the outcome of research studies carried out by us in the area of Optical Pattern Recognition. A hybrid JTC architecture has been used to evaluate correlation performance of four different types of JTCs in a non-cooperative situation. A non-zero order JTC has been proposed based on the principle of differential processing of joint power spectrum and its sensitivity to illumination variation has been investigated. A hybrid wavelet transform based JTC has been proposed and demonstrated to achieve high image discrimination. Hartley transform has been introduced in joint-transform correlation. Chirp modulation in HJTC has been demonstrated to extract information on object correlation and absolute object position from correlation output. A discrimination sensitive rotation-invariant JTC has been proposed based on gradient preprocessing and circular harmonic decomposition.

The significant progress which has been made in the development of differential pairs and arrays of differential pairs of light-emitting thyristors has made the construction of optical computing systems with high speed interconnections a realistic possibility. In this paper we review our work on the practical implementation of these optoelectronic transceiver devices in systems and demonstrate most of the basic functionalities necessary to build a primitive digital parallel optical processor. We demonstrate the transcription of digital optical data between cascaded single elements and between 8 X 8 arrays of completely-depleted optical thyristor differential pairs. We also show results of digital optical logic NAND, NOR, AND, OR, NOT operations, logic plane to logic plane imaging with a diffractive fan-out and parallel digital data input with a computer controlled liquid crystal micro-display. As an example of a sub-system module which has reasonable complexity we focus on a demonstrator platform which combines optical thyristor logic planes, polarization- selective diffractive optical elements, liquid crystal variable retarders and large diameter gradient index lenses, and successfully demonstrate dynamically reconfigurable nearest neighbor interconnects. We conclude by discussing the future system performances in the light of system scalability.

Electrically-controlled 64 X 64 ferroelectric liquid crystal spatial light modulators (FLC-SLMs) were fabricated with a quick response, high contrast ratio and good bistability at the resolution of 10 lmm. The special polymer films aligned SLMs have a quite long operation life. A 1.6 inch 64 X 80 FLC device for the display aim was fabricated, which e-o properties have been improved by the modification of the aligning layers and a large area FLC alignment with uniformity can be obtained. A FLC light shutter at the aperture of 30 mm X 30 mm was also fabricated and used as a phase-sensitive image system for the investigation of fluorescence lifetime.

We have proposed the use of polychromatic light based photorefractive correlator for 3D motion measurement. The double exposures of speckle patterns can be recorded in a BaTiO₃ crystal, thus providing a set of interference fringes due to the polychromaticity of the light source and the 3D displacement. Due to the fringes corresponding to the two illuminating wavelengths used in our experiment, a set of correlation output is generated which helps in a better averaging of the results of measurement. This technique further contributes to the enhancement of accuracy and range of displacement measurements.

The kernel associated with Fresnel diffraction, which is an exponential chirp function, has recently been shown to possess the shifting and scaling properties of wavelet functions. However, these scaling chirp functions do not satisfy the commonly used admissibility conditions. We propose to synthesize a class of quasi-wavelet filter functions by taking difference of two such chirp functions with two different scaling depths and term these filters as difference-of-chirps (DOC). The Fourier transform of DOC functions have zero values at the origin, and can be used for edge feature extraction. Computer simulations as well as some experimental results have been presented.

The paper presents a review of the Wigner distribution function--its definition and its most important properties-- and of some of its applications to optical problems, in particular to the description of partially coherent light beams and to the propagation of such light beams through first-order optical ABCD-systems. Special attention is paid to Gaussian beams and to second-order moments of general, partially coherent light.

The effect of truncating a light beam is expressed as a convolution of the Wigner distribution function of the light beam and the Wigner distribution function of the truncating aperture. The Wigner distribution function of a circular truncating aperture is derived and an approximate expression is presented. The approximation not only has the properties that it is exact in the spatial origin and in the spatial- frequency origin, but also that the integral over all spatial frequencies takes the exact value.

A measure for the twist of Gaussian light is expressed in terms of the second-order moments of the Wigner distribution function. The propagation law for these second-order moments between the input plane and the output plane of a first- order optical system is used to express the twist in one plane in terms of moments in the other plane. Although in general the twist in one plane is determined not only by the twist in the other plane, but also by other combinations of the moments, several special cases are considered for which a direct relationship between the twists can be formulated. In particular it is shown under what conditions zero twist is preserved in a first-order optical system.

The structure and main properties of coherent and partially coherent optical fields that are self-reproducible under propagation through a first-order optical system are investigated. A phase space description of self-imaging in first-order optical systems is presented.

The Radon-Wigner transform, associated with the intensity distribution in the fractional Fourier transform system, is used for the analysis of complex structures of coherent as well as partially coherent optical fields. The application of the Radon-Wigner transform to the analysis of fractal fields is presented.

The novel optical space-to-time-to-space conversion technique for image transmission with an ultra-fast pulse laser is proposed. The proposed technique consists of combined uses of the concepts of time-space conversion, the time-frequency transform, and their inverses. To verify the proposed technique, preliminary experimental results are shown.

We present an extended Kalman filter (EKF) based approach to the reconstruction problem in curved ray optical tomography. A state variable model describing the tomographic process is set up, and an EKF is applied to the model to estimate the refractive index distribution of an optically transparent refracting object from noisy optical path-length difference data. Preliminary results of reconstructions of a synthetic time-invariant refractive index distribution from projection data of various noise levels are comparable with those obtained from a typically used deterministic approach, the average correction per projection method.

We develop a nonlinear thin-film theory. By using a superposition of plane waves with a thin-layer approximation the Kerr-Maxwell equation is solved exactly within a thin slab. The characteristic matrix of the Kerr-medium resembles the corresponding linear matrix, but the wave vectors now are field dependent. The linear result is recovered in the limit of vanishing nonlinearity. We also discuss alternative theories for fields in nonlinear Kerr-media, based on variational principles and on perturbative Hamilton-Jacobi formalism.

Laser-based ultrasonic systems for non destructive testing and evaluation rely on the coherent detection of phase modulation imprinted on the beam by the vibrating surface. As this detection principle requires an exact superposition of the wave issued from the target with a plane reference wave, these devices only operate with a plane wave signal beam. This constraint strongly limits the spread of laser ultrasonic systems in industry. We will show how the use of dynamic holographic materials allows to implement adaptive interferometers with a large light gathering power. Two different systems that have recently led to industrial developments, will be presented and compared. Requirements for the dynamic material to be used will be discussed. Performances for ultrasound detection will be finally given.

Some proposals on Lau and Talbot fringes formation based on a grating registered as birefringence modulation in a photorefractive crystal, will be presented. In the Talbot case, the stored grating can be replicated if read-out with coherent light. The system for the Lau arrangement behaves as a combination of an amplitude and a birefringence phase grating. In both cases, it is possible to control the visibility and to produce a contrast reversion of fringes by using an analyzer. Besides, Lau and Talbot interferometers based on the mentioned approach and their alternative experimental arrangements will be discussed.

Photorefractive beam coupling in barium titanate crystals is characterized experimentally by measuring the signal beam gain and the exponential gain coefficient at 440 nm, 632.8 nm and 780 nm. The figure of merit parameters such as the change in refractive index, the space charge field and the trap density are estimated using Kukhtarev's theory. A comparative study at multiple wavelengths is presented. The signal beam gain is found to be maximum at 440 nm.

PMMA and PET thin films doped with (t-Bu)₄VOPc {(t- Bu)₄VOPc PMMA and (t-Bu)₄VOPc PET} and PMMA thin film doped with (t-bu)₁. ₄VOPc {(t-Bu)₁. ₄ VOPc PMMA} were prepared on glass substrate by coating (t-Bu)₄VOPc PMMA and (t-Bu)₄VOPcPET were treated with dichloroethane vapor in a desiccator at room temperature. On the other hand, (t-Bu)₁. ₄VOPc PMMA was treated with dichloroethane and chloroform vapor in the desiccator at room temperature. The (t-Bu)₁. ₄VOPc PMMA and (t-Bu)₄VOPc PMMA thin films showed SHG and THG after vapor treatment but (t-Bu)₄VOPc PET thin film did not. These suggest that the degree of swelling by dichloroethane vapor are different between PMMA and PET. In other words, the aggregation of (t-Bu₄) VOPc occurs more easily in PMMA than in PET. The THG of (t-Bu)₁. ₄VOPc PMMA thin film is larger than that of a (t-Bu)₄VOPc PMMA thin film. This means that the molecular size of (t-Bu)₁. ₄VOPc is smaller than that of the size of (t-Bu)₄VOPc.

Exciton interactions in ZnSe-based thin layers and quantum wells have been studied using ultrafast four-wave-mixing. We present results to show the influence of quantum confinement on the exciton-acoustic-phonon scattering rate, and compare the coherence lifetimes of excitons and biexcitons. Using a thin ZnSe layer, we reveal a new signature of quantum beating, namely polarization-state beating, which in turn reveals the role of excitation-induced dephasing in exciton interactions.

Diffractive optical elements are rapidly finding their way into many practical optical systems, and this has given rise to a spurt of research and developmental activities in this area. IN this paper, the history of these elements is first traced to get a perspective on their current state-of-the- art. The important features of this rapidly advancing field are then identified so that one does not get lost and can easily stick to one's guns while browsing through the maze of publications. Finally a glimpse of the fascinating future trends is given to stimulate further interest in the area.

High-efficiency resonance coupling effects in zero-order diffractive multilayer structures have applications in fields such as optical filtering and laser technology. These resonance effects arise on phase matching of an incident laser beam to a leaky waveguide mode. Then, in theory, complete energy exchange between the input wave and a reflected wave can take place within narrow ranges in wavelength, angle of incidence, index of refraction, or layer thickness. This paper addresses theoretical modeling, experimental realization, and applications of this so-called guided-mode resonance (GMR) effect. In particular, the achievable GMR-filter efficiencies, spectral linewidths, sideband levels, and polarization characteristics are treated with a plane-wave model and a Gaussian-beam model. Resonance bandpass filters operating in reflection and transmission are shown to exhibit high efficiencies and extended low sidebands. Genetic algorithms are applied to solve inverse resonance-filter design problems. Applications including GMR laser mirrors, electro-optic modulators, and resonant Brewster filters are presented. Experimental results are shown to agree well with theoretical calculations.

The field of light structuring in extended 3D regions of space is making significant progress in the design, implementation and applications. Some of the physical principles and algorithmic aspects will be indicated and several applications will be discussed. Applications related to fundamental aspects of light propagation include the generation of non-expanding beams and beam-arrays. While several technological applications of the above mentioned light distributions can be foreseen, some were also investigated. These include surface profile measurements with resolution exceeding classical diffraction limits. Another area of application is in special lithography where the possibility of extending the depth of focus of light structures can be utilized. The algorithms used in this work are designed to exploit the information content of the recording device in an optimized way. This enables the generation of diffractive optical elements on low resolution devices, such as presently available spatial light modulators. Accordingly, dynamically programmable light distributions can be implemented for various applications such as free-space interconnections, display and measuring procedures.

Photocrosslinkable recording materials are used for long time as one of the best materials to fabricate diffractive optical elements and holographic optics. Dichromated gelatin is the most widely used materials for those applications. Research was done for replacing the dichromated gelatin by some metal doped polymers. We will make a review of materials and applications as well as some results regarding the photophysics and photochemistry of metal doped systems.

Dynamic holography in photorefractive quantum well heterostructures has opened a wide new range of optical applications that utilize the ability of the hologram to adapt to environmental disturbances or to changes in the signal of interest. Examples of applications include 3D imaging through turbid media, femtosecond pulse processing and compensation, and adaptive laser-based ultrasound detection.

Standard approaches of lithographic process simulation have been applied to the simulation of holographically exposed photoresist gratings. Fine tuning of the photoresist development parameters results in a good agreement of simulated and experimentally obtained photoresist profiles. Several conclusions with respect to the optimization of process and photoresist parameters for the fabrication of user defined photoresist profiles are drawn.

In present paper the lightsensitive properties and application in diffractive optics of As-S-Se inorganic resists are reviewed. Basic characteristics of As-S-Se layers are considered. Among them are optical properties, Raman spectra and their evolution under various treatments. Investigations of chemical properties have shown the good resistive properties of As-S-Se layers in various amine based etching solutions. The lightsensitivity properties (characteristic curves) are presented. The surface relief formation was investigated by means of numerical simulation and experimental investigations. Ways of optimizing media parameters, exposure and treatment processes are shown. Good mechanical strength and thermostability of As-S-Se layers enabled to use the obtained relief patterns after additional treatment for the production of high quality copies. Phase- relief holographic optical elements (HOE), recorded by using such resists, may be used as lithographic mask for the relief transfer into the substrates material by wet or dry etching, that enables to form HOE (Fresnel lenses, gratings) in glass, quartz, etc. Characteristics of the obtained holographic optical elements are examined. Diffraction efficiency values of the holographic gratings were close to the theoretical ones.

A solid-state laser cavity is studied where the laser crystal aberrations are corrected by a diffractive optic element. The type of aberration and the location of the correction plate are found to influence the modal performance of the cavity significantly. The largest modal discrimination is obtained for axicon-like crystal aberrations and when the correction is performed close to the end mirror. An experiment is performed with a laser- diode-pumped Nd:YVO₄ laser. With no correction, a thermally induced aberration of approximately two waves is measured across the crystal. By using a diffractive corrector plate, the single-mode slope efficiency is increased by a factor of 4, and the total single-mode output power is increased by a factor of 3.

With this publication we would like to present a high precision triangulation sensor for residual shorts measurement of coiling materials. The sensor is a stand- alone system. A FPGA and DSP are responsible for the timing and reading of the linear CCD-sensors. A microcontroller handles the in- and outputs and does some desired calculating. The basic element of the sensor is a symmetrical arrangement of two laser emitters and their receiving optics. Due to this arrangement we get a stable thermal behavior of the sensor. Furthermore this paper gives some detailed information about the accuracy, resolution and the measuring range of the sensor. One cases of industrial application are listed at the end of this paper.

Two methods of losses measurements: Findlay-Clay's method and relaxation frequency method were verified for two types of diode pumped lasers. In case of Nd:YAG laser with changeable output coupler the results obtained in both methods were in good agreement. However there was observed the contradictory between the relatively high losses (about 10% for transmission losses of 5%) and very high slope efficiency (approximately 50%) of this laser. The measurements of cavity losses via relaxation method were carried for several types of microlasers made of Nd:YAG, Ng:GGG, Nd:YAP crystals and Nd:phosphate glass. There were obtained total losses (including transmission ones) in the range from 7% to 30%.

A kinetic model for a discharge-pumped ArF excimer laser has been developed. The electrical circuit loss, collision loss of electrons and atoms in plasma, and photon absorption loss were calculated. The energy loss process from the electrical input to the laser output is discussed. It was found that 34% of the electrical input is lost in the electrical circuit, 30% of the deposited energy is lost as a elastic collision loss. Since there are large quenching losses and photo absorptions, the laser output energy is several percent of the input energy.

Dynamic laser light scattering technique (DLLS) has been used to investigate a grid generated 3D turbulent fluid flow. The probability distribution function of relative velocity fluctuations in the flow, P(V(R,t)) is obtained from the measurements of intensity autocorrelation function, g((tau) ) of the light scattered from the turbulent medium. The intermittent nature of turbulence and the presence of small scale coherent structures in the flow field is investigated from the changes in decay rate of g((tau) ) and functional form of P(V(R,t)). DLLS is also employed to study the turbulent drag reducing properties of certain interesting linear, high molecular weight polymers like polyacrylamide. By using the Laser Doppler Velocimetry technique, we also investigated a 2D turbulent flow in a soap film flowing under gravity.

Serious eye hazard is posed by lasers operating at a wavelength below 1.4 micrometers . The vision impairment results largely from burn spots and thermal lesions in the active part of the retina or damage to the eye lens depending on the laser wavelength and light intensity reaching the eye. At present, most range finders for military use are based on the neodymium laser, which operates at 1.06 micrometers . In order to enhance the safety of such instruments, the operating wavelength can be shifted to 1.54 micrometers by using erbium laser or techniques such as parametric down conversion in nonlinear crystals or Stokes shift in pressurized methane cells. These options are reviewed and the current status of their technology is presented.

A new generation of InP based 50 nm gate-length pseudomorphic high electron mobility transistors was employed in continuous wave optical mixing experiments to generate millimeter waves to extremely high frequencies. Direct radiation of optical mixed signals was demonstrated at 212 GHz. This, to our knowledge, is the highest frequency optically generated millimeter wave radiation ever reported for three terminal devices. Newly developed G-band probes and a horn antenna were used for radiation measurements. A signal to noise ratio of approximately 20 dB was obtained that indicates significant response of our devices at these frequencies. A broadband three wave detection scheme was used to further extend optical mixing to 238 and 267 GHz. Optical time domain and electrical characterization were carried out to reveal the high frequency capabilities of these devices. A photoresponse time of 6.9 psec was measured using a picosecond electrooptic sampling setup. Cut-off frequencies of 228 GHz and maximum oscillation frequencies of 124 GHz were obtained in S-parameter measurements. Specific examples of applications in communications and spectroscopy were investigated.

The size of particles dispersed in a dense disordered medium is estimated from the transport mean free path-length by using the coherent backscattering effect. The influence of the particle aggregation is also clarified. It is concluded that this method is available to measure simultaneously the averaged particle size and the dispersion state of particles in the dense colloidal suspension.

A passively mode-locked fiber laser is developed to generate stable tunable pulses with duration of 270 - 325 fs pumped by a semiconductor laser diode. The lasing wavelength is tuned continuously over a wavelength range of 60 nm by rotating a bulk band-pass filter inserted in the cavity. We reduce the phase noise by minimizing the intensity fluctuation of the pump source, and by controlling the influence of airflow and temperature fluctuation of the cavity. The estimated jitters is to be below 31 X 10^-6 (0.7 ps) at a center wavelength of 1.558 micrometers , and to be below 86 X 10^-6 (1.8 ps) over a 25 nm wavelength tuning range, using a power spectrum technique.

The paper presents results of investigations of three nonlinear absorbers; U²⁺:CaF₂ and Er³⁺YAG used in generation systems of monopulses of laser radiation of wavelength 1.5 micrometers and V³⁺:YAG crystals used in systems generating radiation monopulses of wavelength 1.3 micrometers . The transmission changes of the examined absorbers with increase in power density of the passing diagnostic radiation have been determined. There were estimated the following parameters: non-active losses, absorption cross- section, saturation energy, concentration of active centers, relaxation time, and energy losses caused by absorber bleaching. Generation characteristics of erbium-glass laser (1535 nm) with U²⁺:CaF₂ modulator and Nd:YAG laser (1318 nm) with V³⁺:YAG modulator were investigated.

Two methods of frequency stabilization of RF excited CO₂ lasers are presented. First of them is based on reference absorption peak in deuterized ammonia (NH₂D) and assures high resulting short-term stability of laser. The second, simple and cheap method is based on optogalvanic effect in RF plasma.

Dual beam transient thermal lens studies were carried out in aqueous solutions of rhodamine 6G using 532 nm pulses from a frequency doubled Nd:YAG laser. Analysis of thermal lens signal shows the existence of different nonlinear processes like two photon absorption and three photon absorption phenomena along with one photon absorption as well as excited state absorption. Concentration of the dye in the solution has been found to influence the occurrence of the different processes in a significant way.

The present paper describes the design, fabrication and calibration of a stand alone IR sensor which can remotely sense the radiations emitted by the snow surface. The sensor is capable of measuring temperatures from 0 degree(s)C to -30 degree(s)C. The sensor essentially comprises of three major constituents: (1) the IR optics which collects the radiation emitted by the snow surface and focuses them onto the detector, (2) the detector that converts IR radiation into an electrical signal and finally, (3) the electronics module and display that processes and displays the measured snow surface temperature. The sensor design is based on a single element lithium tantalate pyroelectric detector and uses a DLC coated Ge optics operating at F/1, with an effective aperture of 57.3 mm. The output of the sensor gives the instantaneously measured snow surface temperature with an accuracy of +/- 1 degree(s)C.

Interferometry using a single wavelength delivers the surface topography and surface heights of optically polished surfaces. However, discrete steps and holes cannot be determined, the sensitivity is fixed, and the analysis of optically rough surfaces is not possible. Some of these limitations can be overcome by using two or more wavelengths. In wavelength scanning interferometry, the frequency of the modulation induced by the wavelength change is determined independently for each image pixel. The tuning range determines the resolution of measurements, while the tuning step limits the range of the measurements. Laser diodes can be tuned, but an external cavity is needed for a larger mode hop free wavelength variation. Polished and optically rough surfaces can be analyzed in the same manner. In a new development, the application of temporal evaluation of speckles for deformation and shape measurement will be discussed. It turns out that spectral and temporal phase analysis can be very useful for many applications in optical metrology. Experimental results will support the methods discussed.

Applications of ordinary two-beam shearing interferometry to (1) aberration measurements of an optical system, (2) aberration correction of an optical system, and of Multiple Beam Shearing Interferometry (MBSI), (3) beam collimation, (4) focal length measurements, and (5) a position magnifying sensor, are described. For two-beam shearing interferometry, a holographic shearing interferometer with two separated three-beam holograms, is used. For MBSI, a shear plate with two flat surfaces of glass, wedged at a small angle and coated to obtain high reflectivity, is used. Theoretical and experimental results are presented for both situations.

Speckle Phenomenon has been used for the measurement of surface roughness, deformation and shape of the object. Electronic speckle pattern interferometry can deliver the measurement data at the video rate. Some applications of ESPI like defect detection, residual stress measurement etc. are presented.

A new method is proposed for determining the coherence properties of the wave fields, produced by a broadband source, from the spectral changes produced an interference. The knowledge of spectral degree of coherence obtained experimentally combined with the space-frequency equivalence principle is used to determine the angular diameters of stars which is the source of the field. This is the first experiment which shows the application of spatial coherence spectroscopy in astronomy.

In this study, an optical system to generate contrast- enhanced speckles from ordinary rough surface object is proposed. Its statistical properties are studied as a function of the surface roughness and the defocusing distance in detail with special attention to its application to the determination of the roughness. It is revealed that the contrast of contrast-enhanced speckles depends only on the rms roughness of the rough surface object. Usefulness of the contrast-enhanced speckles on the measurement of surface roughness of the object is experimentally confirmed.

The recording and read-out of a volume speckle pattern is investigated for transmission geometry. The modulation of the 3D speckle grains appears when the image of a coherently illuminated random diffusor is formed onto the crystal by an optical system whose pupil consists of two identical holes. The intensity distribution of the speckle pattern imaged onto the BSO crystal leads to a space-charge field by drift of photocarriers, resulting in a refractive index modulation. The main features of diffracted read-out light at the Fourier plane are discussed.

In this paper we first survey non-contacting measurement of thickness and refractive index of transparent plates and films. Especially, the separation of these two quantities are focused on. Then we explain the principle and the apparatus for separate measurement of refractive index and geometrical thickness, which are also applicable to multiple layers. In addition, several application examples of this method are also presented.

In this paper, Fizeau interferometry is introduced in conjunction with confocal laser scanning microscope as a new interferential method. In this preliminary investigation interference fringes formation was studied. A theoretical model of the method is presented and a comparative analysis with the experimental and theoretical results was performed.

A spectral interferometer incorporating a Kosters prism is constructed to offer an excellent instrument for making a stable and precision measurement of material dispersion and absorption. Simultaneous measurements of the dispersion and absorption for a test sample, rhodamine in ethanol, are successfully made by use of the interferometer.

A new compact system is proposed and instrumentated for directly measuring in-plane strain using a high frequency grating and two Position Sensor Detectors (PSDs). The grating with a frequency of 1200 lines/mm attached on the surface of a specimen is illuminated by a focused laser beam. The spatial resolution for strain measurement, i.e. illuminating area on the specimen is about 0.4 mm. The centroids of diffracted beam spots from the grating is automatically determined with two PSD sensors connected to a personal computer. The shift of diffracted beam spots due to the specimen deformation is then detected. Several measures for improving strain sensitivity are taken. Strain sensitivity of 1 micro-strain can be obtained. The residual strain error is analyzed due to the misalignment of laser and grating. The system can be used for both static and dynamic test.

Modifications of the basic Twyman Green Interferometer for the testing of the a cylindrical surface are described in this paper. A CGH cylindrical lens of f equals 45.0 mm is put in the test arm of the interferometer to serve as a null lens. Polarizing components are used to provide for adjustments of the intensities of the two beams. The resulting interferograms have a strong bright patch in the middle which does not allow the unwrapping of the phase. A modification of the CGH cylindrical element makes this patch to disappear making possible the application of phase shifting technique for measurement of these surfaces.

A scheme for combining a common path triangular interferometer with a standard polariscope has been proposed which will enable one to obtain normal photoelastic fringe pattern as well as the first derivative of the stress pattern from the same setup. The results under different conditions of testing are represented along with basic mathematical formulation for the same.

The propagation and interaction of shock waves generated by exploding point charges inside an open ended rectangular glass tube (inner size 29 mm X 16.5 mm and length 248 mm) were observed using Mach-Zehnder interferometry in conjunction with high-speed photography. The shock wave velocity in the air was determined using high-speed photographic data and it was found that the shock wave velocity decreases as the radial distance from the explosion center increases. From the determined shock wave velocity data the shock mach number was calculated and the corresponding shock front peak overpressure was determined. The shock reflections from the walls of the tube were also visualized and the reflection coefficient was calculated.

Novel liquid crystal devices originally developed for photonic information processing and optical communication have found new applications in photonic sensing and metrology. The paper reviews our recent studies on real-time vibrometry using a fast ferroelectric liquid crystal spatial light modulator, and 3D micro shape measurements using a frequency-tunable liquid crystal Fabry-Perot interferometer.

The photoelastic or birefringent coating technique is a unique tool for quick and reliable estimation of wholefield stress/strain distribution at any locations in a loaded structural component. This technique can also be used as a powerful NDT tool. This requires loading of the component to a sufficient level (straining to about 300 microstrain) to obtain enough response in the photoelastic coating. Use of `reverse loading concept/method' enables overcoming this problem to a great extent. This paves way for extensive application of this method with its advantages of high reliability and simplicity. Demonstrative examples for validating this concept along with the discussion of the related experimental/test parameters are presented.

In this review paper, the geometrical point-spread function (PSF) of an optical imaging system aberrated by a primary aberration is discussed and compared with the corresponding diffraction PSF. The defocused PSF of an otherwise aberration-free system is also discussed briefly.

We present the observation results of a single string DNA (deoxy ribo nucleic acid) obtained by collection mode near- field optical microscopy operated under constant distance mode with the optical near field intensity as the feedback signal. The observed width of the narrowest string is 4 nm. To our knowledge, this is not only the successful optical observation of a single string DNA by purely optical means but also under such high resolving capability. These are attributed to the special care taken during the sample preparation to avoid unwanted scattered light and to the probe which were specially designed to enhance the local near field interaction. All these factors make the probe picks up efficiently the high spatial frequency components of the scattered near field at the same time rejecting effectively the lower spatial frequency components.

It is discussed zooming loci of movable components in several types of mechanically compensated zoom lenses. They are a fundamental type (a variable afocal converter), a basic two-component type and a standard four-component type. A simultaneous zoom equation for each type, which satisfies simultaneously two paraxial requirements for zooming, namely, variation of paraxial value and stationary distance between an object and its image is derived. A set of analytical solutions to each type is obtained together with a numerical example. More general discussion is also added.

The effects of a finite value for Fresnel number in focusing systems are discussed. For an aperture illuminated by a convergent spherical wave, a shift of the maximum intensity towards the aperture results, associated with a coordinate scaling with regions further from the aperture stretched. There is also a dependence on the numerical aperture of the system, the focal shift decreasing with apertures. For high apertures, the focal field can be expressed in terms of a scaled Debye integral. An alternative geometry is that of a focusing system with an aperture stop at an arbitrary position. If the stop is situated in the front focal plane of the lens, the amplitude in the back focal plane is given by the Fourier transform of the aperture amplitude, and the effective Fresnel number is infinite. For positions further from the lens it is negative, so that the maximum in intensity is shifted further from the lens, and the scaling is such that regions closer to the lens are stretched. A high aperture system can be modeled using the concept of the equivalent refractive locus. The field in the front focal plane is transformed into an angular spectrum of plane waves with an appropriate apodization term, so that if the aperture stop is in the front focal plane the effective Fresnel number is infinite.

A beam profile monitoring system for the synchrotron radiation is designed to evaluate distribution of a cross section of the electron beam in a high-energy accelerator storage ring in real-time. The Shack-Hartmann wavefront sensor is adopted for the measurement of the wavefront error caused by deformation of an extraction beryllium mirror for the visible synchrotron radiation. The correction of the measured wavefront distortion is also described.

Simulation of photolithographic processes is widely used in semiconductor research and industry. The paper reviews physical models and capabilities of modern lithography simulators. Application of these simulation techniques to the manufacturing of microelectronic, optical and micro- optical components are discussed.

Design of image intensifier night vision systems involves meeting the typical requirements of a high aperture and high-speed objective with high contrast at low frequencies throughout the image field. Use of conventional homogeneous lenses in such systems often gives rise to bulky structures in size and weight. In this paper, we describe the availability and use of gradient index (GRIN) materials that have a great potential to reduce the size and weight of such complex systems. However, we restrict ourselves to the use of commercially available axial GRIN materials for the current application in order to demonstrate realizable GRIN night vision systems.

In this paper a new whole field technique for determination of characteristic parameters in integrated photoelasticity using phase-shifting methodology is proposed. Appropriate optical arrangements necessary for this are presented and the intensity equations are obtained by Jones' calculus. The new methodology is verified experimentally for the problem of a circular disk under diametral compression viewed in oblique incidence.

In many optical applications of anisotropic crystals birefringence dispersion (BD) is at least so important as birefringence spatial inhomogeneity itself. In this work a new technique of 2D mapping of parameters related to BD in plane-parallel wafers of optical materials is reported. A computer-controlled imaging spectro-polarimeter is used for recording the wafers' images for consecutively varying wavelengths. Examples of practical measurements carried out on undoped and Cu-doped LiNbO₃ are presented.

Paraxial imaging equations are derived to determine the image position and magnification of light emitting semiconductor chip of a clear Tl3/4 LED lamp and a positive lens coupling optics. The energy density distribution in the image space of the coupling lens is studied with the help of non-sequential ray trace methodology by generating a computer aided 3D model. Finally the energy density distribution in the image space of the coupling lens is observed experimentally and the results are discussed.