Radiometry in military applications
Author(s):
Krzysztof Chrzanowski
Show Abstract
Missiles guided using optoelectronic methods, optoelectronic imaging systems (thermal imaging systems, night vision devices, LLLTV cameras, TV cameras), and optoelectronic countermeasures (smoke screens, camouflage paints and nets, IR flares, decoys, jamming systems, warning systems) are one of the most important components of modern military armament. There are numerous military standards, some of them secret, that precise radiometric parameters to be measured and the testing methods to be used. There is also much literature on the subject of testing of the systems mentioned above, although mostly on subject of testing of the thermal imaging systems. In spite of this apparently numerous literature, there still significant confusion in this area due to secrecy of some parameters and testing methods, differences in recommendations of different military standards, fast progress in military optoelectronics, and also due to enormous number of different types of optoelectronics systems used in the military armament. A review of testing methods of the three basic groups of optoelectronics systems used in modern military armament: the missiles guided using optoelectronics methods, the optoelectronic imaging systems, and the optoelectronic countermeasures is presented in this paper. Trends in the measuring sets.
Simple method of laser beam quality analysis
Author(s):
Anatol A. Ryzhevich;
Nikolai S. Kazak;
Nikolay A. Khilo;
A. N. Khilo
Show Abstract
A method for determining the mode composition a of laser radiation with Bessel mode structure is developed, which includes measurement of intensity distribution and solution of systems of the algebraic equations for amplitudes and phases of partial beams corresponding to different Bessel modes. A method of laser beam quality analysis utilizing a simple optical scheme composed of a telescope, axicon, and microscope is proposed and verified experimentally.
Method of measuring spatial intensity of laser beams
Author(s):
Romuald Synak
Show Abstract
A method of checking the laser beam spatial intensity is described. It is based on the measurement of the radiation power density of the light entering the ring area whose diameters are changeable. From derived power density distribution the usefulness of the tested laser for a given application can be concluded and the value of the laser beam diameter, estimated as a function of the radiation power level, can be calculated. A practical measurement set-up and its use for investigations of diode laser modules is presented. Because of its simplicity and low operation cost, the described approach can be particularly suitable for testing lasers destined for such proposes as alignment, medium transmittance measurements and others.
Measurement capabilities of a compact thermal-type standard of energy unit of pulse laser radiation
Author(s):
Wojciech Skrzeczanowski
Show Abstract
New instrument for measurements of laser pulse energy is described. Due to its parameters it can be used as a standard for unit of energy of pulse laser radiation. The instrument consists of a control unit, three sources of laser radiation, two receivers of optical signal, and a laptop. The whole system can be easily transported enabling one to carry out measurements in situ, at customer's, not only in laboratory conditions. This is a very important feature of the instrument because it allows inexpensive calibration and testing of large industrial laser installations and interesting laboratory intercomparisons as well. A method of measurement used in operation of the standard is presented. Main characteristics of the standard are shown. Methods of calculation of uncertainties of measurement during laser energy meters calibration by means of the standard of energy unit of pulse laser radiation are also presented. An alternative measurement option of the standard operating as an energy calibrator for unknown pulse optical radiation source is also available. Some results of testing of laser energy meters at eye-safe wavelength (1.54 micrometer) are presented.
Chosen properties of a photometric detector BPYP 07
Author(s):
Irena Fryc
Show Abstract
In the paper one of the basic parameters of silicon optical measuring photovoltaic cells is discussed. The method of testing the quality of the transducer and the results of measurements made on a photovoltaic cell BPYP 07 chosen as an example are also given.
Angular characteristics of a silicon detector spectral sensitivity corrected by an absorption filter
Author(s):
Irena Fryc
Show Abstract
In this paper the results of measurements of the spectral sensitivity of a silicon detector fitted with a filter for spectral correction are presented. The measurements were made at various angles of incidence of a monochromatic luminous flux on the same surface of the spectral correction filter. The effect of the luminous flux angle of incidence on the spectral sensitivity of the system, detector -- correction filter, was studied. In addition, the errors resulting from changes in spectral sensitivity were determined quantitatively.
New approach to the spatial correction of luxmeter photometric heads
Author(s):
Irena Fryc
Show Abstract
In this paper methods of a spatial correction of a luxmeter photometric head are presented. It was found that a transparent element may be used in a luxmeter photometric head for its spatial correction. Furthermore the luminous efficiency of this type of photometric head is 4.3 times higher than that of photometric head used at present. Thus high photometric efficiency of this kind of the photometric head enables measurement of very low illuminance.
Method of order parameter estimation for liquid crystal in the electro-optical cell from absorption band dichroism
Author(s):
Dmitrii F. Kiselev;
Tatiana M. Glushkova;
Sergei A. Ivanov;
Marina M. Firsova;
Antonina P. Shtyrkova
Show Abstract
In this work the polarization absorption spectrum of homeotropically oriented comb-shaped liquid crystal polymer (LCP) film interposed in the electro-optical cell was investigated. The optical parameters of electrodes were estimated from the observed absorption spectra of the cell with and without polymer film using the method of interferometric extrema envelopes. This method enabled us to re-establish the true polarization absorption spectrum of the polymer. For this purpose the refractive index dispersion data of the substrates and the polymer obtained by independent investigation were used.
Absorption spectra and circular dichroism of calcium and strontium gallogermanates doped by chromium
Author(s):
V. P. Orekhova;
Zoya Borisovna Perekalina;
K. A. Kaldybaev;
B. V. Mill
Show Abstract
The absorption spectra and circular dichroism of gallogermanate crystals Ca3Ga2Ge4O14 and Sr3Ga2Ge4O14, undoped and Cr-doped are investigated. In absorption spectra of all doped crystals three bands connected with ions Cr3+ in octahedral coordination are found. Besides in doped crystals Sr3Ga2Ge4O14 additional low-intensive bands connected apparently with Cr4+ ions in tetrahedral coordination are presented. In circular dichroism (CD) spectra of doped crystals the absorption bands connected to Cr3+ ions are found and the additional ones, which are not connected with Cr3+ ions. Probably these additional bands in CD spectra in both type crystals are connected with defects generating during crystals growth. The rotary forces of transition are determined from CD spectra.
Optical transmission spectra of Na0.4R0.6F2.2 single crystals with fluorite structure
Author(s):
Antonina P. Shtyrkova;
Tatiana M. Glushkova;
Marina M. Firsova;
Dmitrii F. Kiselev;
Elena A. Krivandina;
Zinaida I. Zhmurova
Show Abstract
Na0.4R0.6F2.2 single crystals with fluorite structure were grown by the Stockbarger method. Optical transmission spectra were recorded on the 2 mm thick samples of these crystals at room temperature in the broad spectral region (0.2 - 12 micrometer). It was found that the spectra of crystals with Dy, Ho, Er and Tm ions have the clearly defined discrete structure with a large number of absorption bands in visible, UV and nearest IR regions. The spectra become simpler on going from Dy to Yb. The spectra of crystals with Y and Lu are simplest, almost coinciding and similar to the NaF-crystal spectrum. The peculiarities of these spectra are due to the REE-ions presence in crystalline structure. All single crystals studied have the IR absorption edge at (lambda) approximately equals 12 micrometer. The spectra obtained are compared with these of other fluorides.
New peculiarities of spectroscopic measurements with noncollinear scheme and nonpolarized light
Author(s):
Andrei V. Lavrinenko;
Igor I. Gancheryonok;
Thomas Dreier
Show Abstract
We present theoretical analysis of noncollinear two-wave spectroscopic schemes taking into account polarization incoherence of arbitrary polarized pumping. Our very general treatment is based on a coordinate-free method of wave operators. The analytical expressions for the signal dependencies on beam-crossing angle (noncollinearity angle) and polarization parameters have been obtained for the cases of saturation spectroscopy, nonlinear polarization spectroscopy and optically heterodyned polarization interferometry (OHPI). The comprehensive studies of the OHPI scheme with noncollinear partially polarized light are given. Three different methods of nonlinear susceptibility measurements are suggested.
Polarization characteristics of He-Ne laser radiation reflected by leaves
Author(s):
Viacheslav A. Dlugunovich;
Valentina A. Zaitseva;
Aleh V. Tsaruk
Show Abstract
It is shown that the largest differences in the angular distribution and meanings of the polarization characteristics of radiation reflected by different plant's leaves are observed for leaves illuminated at the angle of 55 degrees by a He-Ne laser radiation ((lambda) equals 0.63 micrometer) linearly polarized in the plane of incidence. It has been revealed that radiation reflected by a leaf becomes elliptically polarized at observation angles of 55 degrees plus or minus 10 degrees. The ellipticity of radiation reflected by leaves depends on the leaf thickness and the position of the top or bottom of the leaf surface relative to the direction of illumination.
Laser heating effect on polarization characteristics of radiation reflected by glass-reinforced silicon polymer
Author(s):
V. Z. Greben;
Viacheslav A. Dlugunovich;
E. A. Kruplevich;
Valerii N. Snopko;
Aleh V. Tsaruk
Show Abstract
The Stokes parameters of He-Ne laser radiation ((lambda) equals 0.63 micrometer) reflected at the angles of incidence from 5 to 70 degrees by glass reinforced silicon polymer before and after its heating up to 1200 K by CW CO2-laser radiation were measured. The He-Ne laser radiation was linearly polarized either parallel, or perpendicular to the plane of incidence. It is shown that radiation reflected in the specular direction by samples illuminated at near the Brewster angle ((theta) approximately equals 56 degrees) by radiation linearly polarized in the plane of incidence contains an elliptically polarized component. Simultaneously, the change of polarization azimuth of reflected radiation is observed.
Optical properties of deposited layers created by an erosion plasma torch
Author(s):
V. Z. Greben;
Viacheslav A. Dlugunovich;
Aleh V. Tsaruk;
V. V. Shkurko
Show Abstract
The results of investigation of the Stokes parameters of He- Ne-laser radiation reflected by different zones of the material precipitated from the plasma torch formed by the interaction of the linearly polarized pulse Nd-laser radiation with a solid target (tantalum) are presented. It was found out, that the intensity ndicatrixes of reflected radiation depends on the deposited layer position. The dependencies of reflection character of the probing radiation on the types of the mentioned above layers are presented.
Optical constants and film thickness calculation based on the ratio of envelopes of the reflectance spectrum
Author(s):
Valery V. Filippov;
Vitaly P. Kutavichus
Show Abstract
A spectrophotometric method is presented, in which the ratio of envelopes of minima and maxima of reflection spectra is used to determine optical constants of a film on substrate. The ratio used allows avoiding absolute reflectivity measurements. Thus, there is no need for the procedure of a spectrophotometer calibration. An application of the ratio measurements for an analysis of isotropic absorbing homogeneous films is described. Provided the film is transparent, the approach offers the simple analytical solution of an inverse problem. A simple iterative procedure is described to find the thickness and optical constants of absorbing films from measurements for s and p polarizations at single angle of incidence.
Evanescent Bessel light beams
Author(s):
Andrey M. Goncharenko;
Nikolay A. Khilo;
Elena S. Petrova
Show Abstract
The spatial structure and polarization of evanescent Bessel light beams excited in an optically less dense medium in conditions of total internal reflection is investigated in detail. TH- and TE-polarized Bessel beams and also their linear superposition are considered. The Pointing vector of evanescent BLBs are calculated. An existence of azimuthal and radial components of the energy flow and also of its z- component, oscillating with the radial coordinate, is established. The structure of the central maximum of a zero- order evanescent BLB is investigated and its diameter is shown being able to be reduced to submicron sizes.
Linear bi-gyrotropic and quadratic gyroelectric Kerr effect
Author(s):
Ondrej Barta;
Jaroslav Vlcek;
Jaromir Pistora
Show Abstract
The extended description of magneto-optical effects in reflection is developed. Two special case are studied -- linear bi-gyrotropic and quadratic gyrotropic Kerr effect in the principal configurations according to magnetization. Obtained polarization states are presented in the form of polarization vectors. The 2D and 3D graphical output is used to the demonstration some important examples.
Polytetrafluoroethylene powder as a material for reflectance and color standards
Author(s):
Adriana Kuszczynska;
Jerzy Pietrzykowski
Show Abstract
Physical and optical properties of polytetrafluoroethylene with particular attention to its suitability as a material for reflectance and color standards are described. Technology used for the preparation of white, gray and color standards is given. Spectrophotometric and colorimetric characteristics of obtained standards are presented.
AFM and optical methods in determining roughness of SERS-active silver electrodes
Author(s):
Stefan Kruszewski;
T. Kobiela
Show Abstract
The results of optical and AFM measurements of SERS-active silver electrodes are presented. The intensity of specularly reflected light from these electrodes was measured and next, the rms roughness determined. The rms roughness of these electrodes were also determined from their AFM profiles. The origins of observed divergences are discussed.
Direct and inverse problem in scatterometry of rough surfaces
Author(s):
Czeslaw Lukianowicz
Show Abstract
Various optical methods are served for surface roughness measurements and have been applied for inspection of precise machined surfaces. These methods sometimes use scatterometry. Scatterometry of rough surfaces is based on scattering of light wave by surface irregularities. Essence of scatterometry consists of intensity and angular distribution of scattered light measurements. Scatter pattern is measured in one or two directions, depending on surface structure and its illumination. How will light be scattered from known irregular surface? It is the main question in direct problem of scatterometry. Research on dependence between measured distribution of scattered field and surface topography is the topic in inverse problem. Mathematical expression of this relation is based on various theories, primarily on the Rayleigh-Rice perturbation theory and on Kirchhoff theory. Direct and inverse problems in light scatter measurements of surface roughness are the subject of this paper. Theoretical and experimental studies of both these problems are presented. Computer techniques make possible to simulate and investigate direct and inverse problem for light scattering by rough surfaces. Investigations of both problems were carried on applying scalar Kirchhoff diffraction theory. Diffraction analysis of coherent light scattered from rough surface shows, that complex amplitude of light in Fraunhofer zone is proportional to two-dimensional Fourier transform complex amplitude of light in surface. Two-dimensional fast Fourier transform algorithm for computer simulation of diffraction field is applied. A discussion of modeling light scattered from periodical and random surfaces is also given.
Comparison of ellipsometric methods for separate determination of thickness and optical constants of thin films
Author(s):
Eugene G. Bortchagovsky;
O. M. Getsko
Show Abstract
This talk is devoted to the analysis of different ellipsometric methods for their ability to get separately thickness and refractive index of thin films. Such analysis is necessary for unambiguous determination of all thin film parameters, not only its 'optical thickness.' Analysis and comparison of different approaches for solving of this problem is made both on the base of the theoretical consideration of methods background and on the calculation of correlation matrix for parameters of interest.
Spectroscopic ellipsometry investigation of influence of high-pressure high-temperature process on optical properties of SiO2-Si structures
Author(s):
Witold Rzodkiewicz;
Andrzej Kudla;
Andrzej Misiuk;
Stanislaw Lasisz
Show Abstract
In this paper, spectroscopic ellipsometry (SE) has been used to investigate SiO2-Si structures, which were subjected to annealing under a high hydrostatic pressure at high temperature (HPHT) processes. Temperature and pressure varied from 450 degrees Celsius to 1280 degrees Celsius and from 105 Pa to 1.2 GPa, respectively. Investigations have been carried out by variable angle spectroscopic ellipsometer VASE of J.A. Woollam Co Inc. Using the standard optical model of the SiO2-Si structure, no satisfying fit of measured and calculated (Psi) and (Delta) ellipsometric parameters characteristics can be obtained. This inconsistency, expressed by the MSE parameter (Mean Squared Error), is proportional to temperature, pressure and time of the HPHT process. Elongated convexities on SiO2 surface have been observed by scanning electron microscope (SEM). It was found that depolarization effect takes place as a result of non-uniformity of either chemical composition or SiO2 film thickness. A model consisting of upper SiO2 surface roughness, SiO2 layer and SiO2-Si interface has been used for data analysis. Application of this model allowed determination of changes in thickness and refractive index of SiO2 as a result of the HPHT process. An increase of refractive index and decrease of layer thickness can be ascribed to excessive stress in SiO2 layer. This stress has been probably caused by densification of silicon dioxide.
Spectroellipsometric investigation of GaSb surfaces after their chemical wet etching
Author(s):
Andrzej Kudla;
Ewa Papis-Polakowska
Show Abstract
Procedure of chemical preparation of GaSb and particularly wet etching of GaSb surface is still optimized. Properties of surface layers depend on applied etchant. Spectroscopic ellipsometry (SE) is a very sensitive and allows estimation both thickness and layer stechiometry. Best process, which gives thinnest layer, can be determined directly from spectroscopic ellipsometry measurement. Optical properties of surface GaSb oxide often differ from described by Zolner. To determine thickness and refraction index of thin layers optical model of investigated structure is required. By comparing results of calculations for different models best one was found. Layers thicknesses and approximate refraction indices were determined for the surface layers after different etching.
Laser goniophotometric Stokes polarimeter
Author(s):
Viacheslav A. Dlugunovich;
Valerii N. Snopko;
Aleh V. Tsaruk
Show Abstract
The dynamic type Stokes polarimeter is created to measure the polarization characteristics of radiation emitted, reflected, and scattered by objects at different angles to the surface. An analysis of the versions of processing of measurement results has shown that the dependence of a random error in determination of the parameters on the number of positions N of a quarter-wave plate, at which the radiation intensity is measured, is of a similar nature as the dependence on the number of independent measurements of the same quantity (approximately 1/(root)N).
Compact turbopolarimeter
Author(s):
Gennady I. Utkin
Show Abstract
A new high-speed laser polarimeter is intended for investigating the kinetics of quickly proceeding chemical reactions by using optically active reagents and has a speed which is tens of times the speed of the conventional servopolarimeters. It is shown that the turbopolarimeter resolution is of the order of several seconds of arc.
Simulation of birefringence effects in reciprocal fiber optic polarimetric current sensor
Author(s):
Prinya Tantaswadi
Show Abstract
We present a mathematical model for calculating the effect of birefringence in reciprocal fiber-optic polarimetric current sensor. The model will aid in designing a configuration with immunity to environmental perturbations, which affect birefringence properties of single-mode fiber used in the sensing part and cause fault current readings, such as acoustic vibrations.
Birefringence dispersion mapping: a new technique for testing of optical inhomogeneity in crystalline materials
Author(s):
Andrzej L. Bajor
Show Abstract
Birefringence dispersion seems to play at least an equal role to birefringence spatial inhomogeneity itself in many optical applications of crystalline materials including especially retardation plates, generators of the 2nd and higher harmonics, or polarizers. Mapping of parameters associated with birefringence dispersion on the entire areas of wafers cut out from crystalline boules seems then to be a powerful tool in testing and research works dealing with optical materials. The method of birefringence dispersion mapping and an automated, computer-controlled spectropolarimeter have been described. Its working has been illustrated by mapping of birefringence dispersion in Cu-doped LiNbO3 influenced by gamma irradiation and thermal annealing.
Spectropolarimetric device for determination of optical anisotropic parameters of crystals
Author(s):
Gennady I. Utkin;
S. V. Alekseev;
U. V. Volnov;
Alisa F. Konstantinova;
E. A. Evdischenko;
Boris V. Nabatov
Show Abstract
Experimental spectropolarimeter device for simultaneous determination of birefringence, dichroism and parameters of an optical activity of crystals is designed and is made. The given device can be utilized for research of real structure of crystals, of the control both quality crystals also optical polarization elements of anisotropic optics (phase plate, polarization prisms). For determination of optical parameters of crystal plates the measurement of light intensity transmitted through a sample disposed between arbitrary oriented polarizer and analyzer is carried out. Control of device and processing of outcomes of experiment implement with the help of the designed software package. For an estimation of capabilities of the given device the measurements optically active crystal (quartz), absorptive crystal (ruby, mica), phase plates are conducted.
Effective anisotropic plane-stratified polarizer and its optimization by the analysis of density of modes
Author(s):
Andrei V. Lavrinenko;
Dzmitry Shyroki
Show Abstract
For a bilayered, N-period, photonic band gap (PBG) structure produced of anisotropic and isotropic layers, we derive analytic expressions for the tensorial density of modes (DOM) and optical transmittance of the structure as a whole. The computations of the DOM-tensor for different physically realizable PBG structures prove the possibility of considerable enhancement of one normal electromagnetic mode and simultaneous depression of the other one. This effect, which is called polarization selection of modes in anisotropic one-dimensional PBG crystals, enables us to design an effective plane-stratified polarizer working in near-optical frequency range, totally reflecting one normal mode and transmitting the other.
Polarization self-action effects of partially polarized light in polarization inhomogeneous media
Author(s):
Irina V. Shapochkina;
Igor I. Gancheryonok;
Thomas Dreier
Show Abstract
On the basis of covariant approach some generalizations of the theory of polarization self-action effects in isotropic (polarization inhomogeneous) resonance media have been done. The results obtained demonstrate influence of the degree of polarization on evolution of polarization parameters of laser radiation propagating in polarization inhomogeneous media. We present new theoretical findings as well as demonstrate agreement between our results and known experimental data.
Propagation and diffractional transformation of laser beams in anisotropic media
Author(s):
Svetlana N. Kurilkina;
Sergey N. Kovchur
Show Abstract
It has been analyzed the peculiarities of propagation of weakly and strongly divergent Gaussian beams near optical axes of uniaxial and biaxial crystals. It has been determined the dependence of character of the laser beam transformation by scanning near special directions on optical anisotropy of medium. It has been established that in strongly divergent light beams the presence of anisotropy leads to changes of energy distribution in its cross-section. It has been found the correct conditions of propagation of non-aberrational beams in crystals which take into account the influence of anisotropy. It has been investigated display of gyrotropy in polarization, energetic characteristics and beam divergence of optical radiation.
Estimation of effective electro-optical parameters of superlattices
Author(s):
Svetlana N. Kurilkina;
Alexander L. Zykov
Show Abstract
In the present report different configurations of electro- optical interaction in multilayer structures have been analyzed at long-length approach. By this, we considered these structures formed by the components with different kinds of symmetries, namely: 'centrosymmetrical/centrosymmetrical crystals,' 'noncentrosymmetrical/noncentrosymmetrical crystals,' 'centrosymmetrical/noncentrosymmetrical crystals.' It has been found the dependence of effective electro-optical coefficients of a superlattice from electro-optical constants of layers and their width. It has been shown that effective parameters of multilayer heterostructure created by crystal layers of arbitrary symmetry, which was put into external field, depend on the angle between crystallographic axes of the components of superlattice. The range of values of angle was defined for which the changes of effective parameters are unimportant.
Mathematical model for calculation of the optical rotation and the contrast of an image
Author(s):
A. Andreev;
Prinya Tantaswadi
Show Abstract
We present a simple mathematical model for calculating the contrast of image and the parameters of the half-shade analyzer. Practical application of the model and accuracy of the measurements are discussed. Effect of the sensitivity of the angle of rotation on accuracy of the measurements and optical loss are also calculated. Method of the direct measurements of the magnetic domain contrast will also be described.
Colorimetric evaluation of display performance
Author(s):
Bogdan B. Kosmowski
Show Abstract
The development of information techniques, using new technologies, physical phenomena and coding schemes, enables new application areas to be benefited form the introduction of displays. The full utilization of the visual perception of a human operator, requires the color coding process to be implemented. The evolution of displays, from achromatic (B&W) and monochromatic, to multicolor and full-color, enhances the possibilities of information coding, creating however a need for the quantitative methods of display parameter assessment. Quantitative assessment of color displays, restricted to photometric measurements of their parameters, is an estimate leading to considerable errors. Therefore, the measurements of a display's color properties have to be based on spectral measurements of the display and its elements. The quantitative assessment of the display system parameters should be made using colorimetric systems like CIE1931, CIE1976 LAB or LUV. In the paper, the constraints on the measurement method selection for the color display evaluation are discussed and the relations between their qualitative assessment and the ergonomic conditions of their application are also presented. The paper presents the examples of using LUV colorimetric system and color difference (Delta) E in the optimization of color liquid crystal displays.
Color evaluation of guest-host liquid crystal displays
Author(s):
Danuta Bauman
Show Abstract
Monocolor, bicolor and black-color liquid crystal displays utilizing guest-host effect were investigated. The polarized absorption spectra for these displays were recorded and the order parameter of the dyes dissolved in liquid crystal matrix has been estimated. Moreover, the tristimulus values of the displays colors in OFF and ON states have been calculated and the changes of the color parameters under the electric field applied have been determined by using 1976 CIELAB Color System.
Colorimetry as a diagnostic tool in the manufacture of antireflection coatings
Author(s):
Grzegorz Jerzy Kopec
Show Abstract
A direct measurement of reflectance spectrum of steeply curved surfaces on commercial spectrophotometer is almost impossible. This work describes the use of colorimetry to estimate the change of spectral reflectance of antireflection coating deposited on such surfaces. The investigations show that the color coordinates for daylight D65 of coatings may be uses for this purpose. The coating deposited on curved surface consists of layers of aluminum oxide, substance H4 highly refractive and magnesium fluoride. Color coordinates for normal CIE'31 observer and illuminant D65 was calculated for varying thickness of layers of the coating. Comparison of calculated on this way color coordinates and observed colors on surface show that method may be used to estimate the reflectance spectrum distribution on the lens surfaces.
Efficient filtering of color image sequences
Author(s):
Robert Suski;
Slawomir Skoneczny;
Jaroslaw Szostakowski
Show Abstract
The first step in image filtering were filters developed on the simply binary images. That was caused because early filters were strictly limited by computational and memory resources of first computers. During the time most algorithms were applied to filter gray-scale images. Advances in high integrated microprocessor technology make possible to work on higher resolution images with more important details. Image processing has been developed very fast based on still 2-D gray-scale images. We could find most of up to now developed algorithms in many monographs.
Applications of low-coherence interferometry in fiber optics
Author(s):
Petr Hlubina
Show Abstract
The aim of this paper is to review some important experimental results we have obtained in the application of time-domain and spectral-domain low-coherence interferometry for dispersion characterizing optical fibers whose intermodal optical path differences (OPDs) exceed the source coherence length. In time-domain measurements, a tandem configuration of a Michelson interferometer and a few-mode optical fiber is used and the spatial interference fringes are obtained at its output when the OPDs between beams and modes are matched within the source coherence length. In spectral-domain measurements, the intermodal interference at the output of an optical fiber alone shows up as a periodic modulation of the source spectrum when a high-resolution spectrometer is used. By processing the measured spectral modulation, the wavelength dependence of the overall phase can be obtained and then, e.g., the intermodal group OPD can be evaluated. When the spectral modulation is not resolved by the spectrometer, a tandem configuration of a Michelson interferometer and the optical fiber is used to obtain the low-frequency spectral modulation and to evaluate the intermodal dispersion in the optical fiber. In this paper, two different low-coherence sources with different temporal and spectral characteristics are used to obtain the intermodal group OPD and its wavelength dependence for two different optical fibers.
Time-domain and spectral-domain two-beam interference under general measurement conditions
Author(s):
Petr Hlubina;
Pavel Stejskal
Show Abstract
Time-domain and spectral-domain two-beam interference experiment with a Michelson interferometer and a detecting system consisting of a monochromator of a variable spectral bandpass and a broadband detector is analyzed theoretically and experimentally and the effect of the monochromator is included in the evaluation the visibility functions of both the spatial and spectral interference fringes. The time-domain theoretical analysis of the two-beam interference shows that the width of the visibility function, that is, the visibility of the spatial interference fringes as a function of the delay in the interferometer varies with the bandpass of the monochromator. The spectral-domain theoretical analysis of the two-beam interference gives the visibility function and shows that the visibility of the spectral interference fringes resolved for a given delay in the interferometer by a spectrometer also varies with the bandpass of the spectrometer. The theoretical conclusions are confirmed experimentally in the Michelson interferometer configuration using a TOLD 9140 laser diode operated below the threshold and a detecting system of a variable spectral bandpass consisting of a prism or grating monochromator and a PIN photodetector. It is shown from the time-domain measurements how the width of the visibility function decreases with the increasing width of the entrance slit of the monochromator. Similarly, it is shown what are the visibility functions for the spectral interference fringes resolved by spectrometers and how they vary with the bandpass of the spectrometer.
Modified interferometric method for refractive index profile measurement of multi-elliptical core optical fibers
Author(s):
Adel M. Sadik
Show Abstract
This paper presents a general interference formula described the interference pattern of multi-elliptical core optical fiber in a transverse interferometer. This formula with Mach- Zehnder interferometry is used to characterize multi- elliptical core optical fiber via its refractive index measurement. A CCD camera for further automatic processing and analysis captures the interference pattern of the output field of the Mach-Zehnder interferometry by the computer-aided system. This study gives possibility to analyze optical properties and possible optical and geometrical microdefects of multi-core optical fiber. Example of application to identical nine-elliptical core optical fiber of thickness 380 micrometer fibers is given.
Order parameter evaluation of LC polymer from interferometric/refractometric data
Author(s):
Dmitrii F. Kiselev;
Tatiana M. Glushkova;
Sergei A. Ivanov;
Marina M. Firsova;
Antonina P. Shtyrkova
Show Abstract
The temperature dependence of refractive indices of homeotropically oriented comb-shaped polymer films was determined with the help of optical interference wedge method. For order parameter S(T) estimation from the refractometrical data the information about the temperature dependence of the polymer density is needed and it is also necessary to choose a local field model. Born expression for the molecular refraction invariant in the large temperature range was used for evaluation of the polymer density temperature dependence. The problem of local field effects was investigated in detail on the example of the low-molecular LC PAA. It was shown that for the relative order parameter S(T) estimation it was possible to use Haller's extrapolation method. In this case the results obtained for different local field models are close to one another and to the results obtained by other independent methods.
Narrow-band polarizing interference filters with liquid crystal space layer
Author(s):
Jerzy Ciosek
Show Abstract
The narrow-pass-band polarization filters are mentioned. Several methods are used for such type of filters. The construction of narrow-band interference polarization filters with liquid crystal space (LC) layer has been presented. The peak of transmittance has been designed at wavelength 1064 nm. Refractive index of liquid crystal changes with driving voltage. At optical thickness of space layer changed to the multiple of quarter-wave thickness the construction has a stop-band in interested spectral range.
Application of interference filters for synthesis spectral characteristics of UV meters
Author(s):
Marian Gilewski
Show Abstract
This paper describes possibility of using a set of bandpass filters for synthesis of spectral response characteristics of UV power meters. In the introductory part, the effect of UV on human organism was presented. Then, a suggestion of UV meter construction was presented. The synthesis of erythemal effectiveness curve, defined by Polish Standards, was made with using spectral characteristics of interference filters and UV semiconductor photodetectors. In the final part, the results of computer simulation were presented together with evaluation of the obtained results.