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Kolobrodov V.G., Mykytenko V.I., Tymchik G.S., Tiagur V.M. Spaceborne linear array imager's spatial resolution for arbitrary viewing angles

Friday, 13 September 2019 09:21 administrator
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Kolobrodov V.G., Dobrovolska C.V., Mykytenko V.I., Tymchik G.S., Tiagur V.M., Komada P., Mussabekova A., Targeusizova A., Iskakova A. Spaceborne linear array imager's spatial resolution for arbitrary viewing angles (Conference Paper)

Simplified model of image forming in spaceborne linear array sensors at arbitrary sight angles is proposed in this paper. On basis of evaluation of system lens - linear array detector modulation transfer function (MTF), the equations were obtained that allow you to determine spatial resolution on Earth's surface. An example of pushbroom imager's MTF determination at sight of Nadir and with different slopes of lens optical axis is given. Image quality changes, which accompany lens optical axis angular inclination were studied. More research needed to determine the impact of lens aberrations on imager's MTF with arbitrary viewing angles.

Keywords: linear array detector, modulation transfer function, remote sensing, spatial resolution

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Last Updated on Friday, 13 September 2019 09:35
 

Kolobrodov V.G., Tymchik G.S., Kuchugura I.O. Design of the multiorder intraocular lenses

Sunday, 03 January 2016 20:26 administrator
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Kolobrodov V.G., Tymchik G.S., Kuchugura I.O. Design of the multiorder intraocular lenses

Abstract. Intraocular lenses (IOLs) are used to replace the natural crystalline lens of the eye. Just few basic designs of IOLs are used clinically. Multiorder diffractive lenses (MODL) which operate simultaneously in several diffractive orders were proposed to decrease the chromatic aberration. Properties analysis of MODL showed a possibility to use them to develop new designs of IOLs. The purpose of this paper was to develop a new method of designing of multiorder intraocular lenses with decreased chromatic aberration. The theoretical research of the lens properties was carried out. The diffraction efficiency dependence with the change of wavelength was studied. A computer simulation of MODL in a schematic model of the human eye was carried out. It is found the capability of the multiorder diffractive lenses to focus polychromatic light into a segment on the optical axis with high diffraction efficiency. At each point of the segment is present each component of the spectral range, which will build a color image in combination. The paper describes the new design method of intraocular lenses with reduced chromaticism and with endless adaptation. An optical system of an eye with an intraocular lens that provides sharp vision of objects located at a distance of 700 mm to infinity is modeled.
Keywords: multiorder intraocular lens, diffraction efficiency, endless adaptation.

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Kolobrodov V.G., Tymchik G.S., NguyenQ.A. The problems of designing coherent spectrum analyzers

Monday, 30 March 2015 10:25 administrator
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Kolobrodov V.G., Tymchik G.S., NguyenQ.A. The problems of designing coherent spectrum analyzers.

The purpose of this article is to improve methods of calculating generalized characteristics of the coherent spectrum analyzers, which define the device’s properties and operation. These are the working range of spatial frequencies, the spatial spectral resolution and the energy resolution. Due to these methods, it is possible to choose optimal dimensions and parameters of components of the device to improve the properties of the last.

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Last Updated on Monday, 30 March 2015 10:31
 

Kolobrodov V.G., Tymchyk G.S., Kolobrodov M.S., Vasyura A.S., Komada P., Azeshova Z. The output signal of a digital optoelectronic processor

Friday, 22 January 2021 11:45 administrator
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In this article, we investigate the mathematical model of a digital optoelectronic processor for the purpose of determining the signal at the processor's output. The study of the model allows us to determine the distortions of the input signal of the processor, which are caused by the matrix spatio-temporal modulator. The developed physical and mathematical model of the processor made it possible to obtain an analytical expression for the signal at the processor's output. Its analysis shows that the formula for determining the spatial frequency differs significantly from the traditional formula. The spatial frequency depends on positions of the central and side maxima in the first-order diffraction maximum. In this case, the signal spectrum can be determined by measuring the lateral maximum, which is located closer to the optical axis of the processor. This allows to use of smaller matrix detectors, as well as to investigate the signal spectrum beyond the Nyquist frequency of the modulator.

https://doi.org/10.1117/12.2501595

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Last Updated on Friday, 22 January 2021 12:07
 

Kolobrodov V.G., Tymchyk G.S., Mykytenko V.I., Kolobrodov M.S. Physical and mathematical model of the digital coherent optical spectrum analyzer

Friday, 13 September 2019 09:43 administrator
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Kolobrodov V.G., Tymchyk G.S., Mykytenko V.I., Kolobrodov M.S. Physical and mathematical model of the digital coherent optical spectrum analyzer

A physical and mathematical model of digital coherent optical spectrum analyzers is discussed. In digital coherent optical spectrum analyzers the input signal is forming as a two-dimensional transparency by means of a spatial light modulator. After Fourier transformation with a lens, multiplication by a spatial filter and second Fourier transformation, the signal is captured by a matrix detector for further computer processing. A lot of digital coherent optical spectrum analyzers and their components (laser, lighting system, spatial light modulator, Fourier lens and matrix detector) models were developed to calculate the signal at the matrix detector output. They use the impulse response and transfer function to evaluate the effectiveness of digital coherent optical spectrum analyzers. The analysis of mathematical relationships shows that the use of a discrete spatial light modulator for the signal input and a matrix detector for light field registration in the spectral domain when combined with computer technology greatly extends the functionality of digital coherent optical spectrum analyzer. The formulas for impulse response and transfer function calculations were obtained, which allows to analyze and optimize the digital coherent optical spectrum analyzer basic characteristics.

Keywords: Matrix detector, Optical correlator, Optical spectrum analyzer, Spatial light modulator

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Kostornov A.G., Kirichenko O. V., Sakhno S. P. and Tymchik G. S. Porosity determination of thin fibrous-material sheets according to the optical transmission coefficient

Sunday, 04 December 2011 10:05 administrator
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A. G. Kostornov, O. V. Kirichenko, S. P. Sakhno and G. S. Tymchik. - Porosity determination of thin fibrous-material sheets according to the optical transmission coefficient. - Powder Metallurgy and Metal Ceramics Volume 23, Number 10, 812-815, DOI: 10.1007/BF00792156 (Translated from Poroshkovaya Metallurgiya, No. 10(262), pp. 86-90, October, 1984).

A statistical model of a porous fibrous material is presented which describes, within 6% error at   0.7, the porosity  and the optical transmission coefficient T of a sheet fibrous material as a function of the geometric fiber sizes: i.e., diameter d, lengthl, sheet thickness h, and average density  , of the geometric fiber centers. A functional dependence f = (h, T) was established which allowed the porosity of thin fibrous material sheets to be determined by measurement of the optical transmission coefficient.

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Kostornov A.G., Kirichenko O.V., Sakhno S.P., and Tymchik G.S. Determination of the average pore size in thin sheets of permeable fiber materials by an optical method

Tuesday, 13 December 2011 10:45 administrator
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The majority of known methods of determination of the structural parameters of porous materials are inapplicable for use as nondestructive methods of continuous inspection of the structure of thin sheets of permeable fiber materials during their production and in finished form. In addition the results of measurements of the structural parameters of permeable materials by different methods differ significantly and there is not a strict correlation between them.

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Last Updated on Tuesday, 13 December 2011 10:53
 

Kuts I.V., Protasov A.G., Lysenko Iu.Iu., Dugin O.L. Pulsed Eddy Current Non-Destructive Testing of the Coating Thickness

Friday, 24 October 2014 09:52 administrator
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Kuts I.V., Protasov A.G., Lysenko Iu.Iu., Dugin O.L. Pulsed Eddy Current Non-Destructive Testing of the Coating Thickness - XI European Conference on Non-Destructive Testing 2014, 06-10 October 2014.

Usually the procedure of eddy current nondestructive testing includes harmonic excitation of the object and then evaluation of the received signal amplitude and phase. This article is devoted to pulse eddy current nondestructive testing which is a simple and effective alternative. It is discussed the use of pulsed eddy current testing for thickness evaluation of the non-magnetic coating which is placed on the low magnetic basis. It is described the method of information signal processing which is based on the Hilbert transform. This method makes it possible to obtained a response from fronts of the exciting pulse signal for the system "sensor - object". The experimental results of coating thickness evaluation are given. The frequency and attenuation of a signal which looks like a damped sinusoid are used as informative parameters. It was found a general nature of the dependence these parameters from the coating thickness.

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Last Updated on Friday, 24 October 2014 10:04
 

Kuts Y., Yeremenko V., Monchenko E., Protasov A. Ultrasound method of multi-layer material thickness measurement

Friday, 22 July 2011 17:20 administrator
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The new multi-layer materials are widely used in air-space industry. We present the new method of multi-layer material thickness measurement, which is based on the digital Hilbert transformation and the signal unwrapped phase analysis. The results indicate that a phase unwrapping of a signal from transducer is able to detect the phase jumps, which are produced by the eho signal superposition during ultrasound nondestructive examination of a multi-layer material.

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Kyrvyova A., Tereshchenko N. Estimation of ultrasound influence on biological tissue

Saturday, 12 November 2011 14:59 administrator
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Anastasiia Kyrylova, Nikolai F. Tereshchenko. Estimation of ultrasound influence on biological tissue. XIII International PhD Workshop OWD 2011, 22-25. pp. 319-323. October 2011

The paper is devoted to problems associated with methods that control BO (biological objects) during physiotherapeutic procedure. Mathematical model of interaction between parameters of ultrasound and BO that can evaluate time of the effective and positive influence of ultrasound on biological tissues is proposed in this article.

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Last Updated on Saturday, 12 November 2011 15:03
 
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