RU2180466C2 - Method and device for converting optical signal - Google Patents

Abstract

FIELD: optical data processing. SUBSTANCE: method involves double ended automatic projection of space- time light modulator on high resistance photo-semiconductor and double collinear transmission of spectrum- modulated light through electrooptic crystal: in space by intensity of forward reading i(x,y,δλ) light and reverse collinearly reflected i^*(x,y,δλ_ij) light and in time t by rotation frequency f of shutter that has a number of sectors with different optical transmission spectrums. Optical signal being converted is matrixed by insulating layer made in the form of matrix of microdiscrete holes periodically filled with light-conducting material with different transmission spectrums; reading-light spectrum δλ also has semiconductor photo-active radiation component. EFFECT: provision for additive-subtractive conversion of chromatic-brightness optical signal by space-time light modulator. 3 cl, 4 dwg

Description

 The invention relates to the field of optical information processing and can be widely used to create image converters that work in real time and carry out spectral coding - decoding of optical signals, as well as in colorimetric systems.

 A known method of converting a color-luminance optical signal based on additive (summation of several multi-colored radiation) or subtractive (subtraction of one color from another) reproduction [1]. In this case, the resulting color is determined by the colors of the mixed radiation [1, p. 232]. Additive color-combining devices (colorimeters) are based on the optical mixing of three color radiation, obtained by filtering the radiation from a comparison source with three separating light filters (for example: red, green, and blue) or dispersing elements [2]. In this case, the additive color mixing can be: optical (using multiple reflections in a diffuse chamber), sequential (by rapidly alternating bursts of radiation of different spectra and a frequency exceeding the critical flicker frequency) and spatial (determined by the original colors of the reproduction system and the ratio of the areas occupied by the elements each color within the general field). The simplest additive colorimeter is a Maxwell disk (obturator), consisting of three multi-colored (red, green and blue), as well as two additional (white and black) sectors, which are rotated, providing a continuous perception of the color of the rotating sectors [1, p. 399]. In subtractive colorimeters (densitometers), color reproduction is carried out by filtering the source radiation using three color filters (wedges), sequentially located in the direction of radiation propagation [1, p. 369, fig. 2.78].

 The disadvantages of this method are: firstly, the impossibility of spatiotemporal conversion of the optical signal, secondly, the inability to quickly rebuild the spectrum of the optical radiation control (electrical or optical) signal and, thirdly, the impossibility of simultaneous additive and subtractive color mixing in the converted optical signal.

 The closest in technical essence and the achieved result to the claimed one is a method that uses internal photoelectric feedback (OS) in a space-time light modulator (PVMS) [3, p. 225]. The method consists in two-sided projection of photoactive light onto a photoconductor (FP): on the one hand, the recording light, and on the other hand, spatially modulated in intensity by the electro-optical crystal (EOK) of the reading (converted) light propagating towards the recording light, while the FI and EOK combined along the optical channel and power circuit.

 A device that implements the method according to the internal photovoltaic OS contains a lens, a beam-splitting prism, a PVMS consisting of an input transparent electrically conductive layer, a dielectric layer, a phase transition, a polarization layer, an EOK and an output electrically conductive layer, and a polarization prism. The reading light passes through a polarizing prism and enters the EOC, the spatial texture of which is formed on the basis of orientational or hybrid electro-optical effects. Due to the spatial modulation of photoconductivity in the phase transition when projecting recording light applied to the electrically conductive layers and concentrated mainly on the phase transition, the external voltage is redistributed to the EOC. Upon reaching the threshold stress values in the EEC in the areas corresponding to the illuminated sections of the FP, the textured thickness of the EEC is destroyed. The plane-polarized read light passing through the EOC in the areas of textured damage changes the polarization phase and, through the polarization layer, is converted to intensity-modulated.

 The main disadvantage of the method and device is the impossibility of spectral conversion of the read light.

 An object of the invention is the expansion of functionality.

This is achieved due to two-sided auto-projection onto a high-resistance phase transition and collinear passage through an EOK modulated in space in terms of intensity i (x, y) - EOK and in the spectrum δλ _i (x, y) - a matrix of micro-discrete holes periodically filled with light guide material with a different transmission spectrum dλ _i , and additionally time-modulated over the spectrum in time δλ _j (t) - an obturator, whose sectors have different transmission spectra δλ _{j for} reading light: direct i (x, y, δλ) and back collinearly reflected i ^* (x, y, δλ _{i, j} , f).
The method and device for its implementation are illustrated in figures 1 - 4. Figure 2 and 4 show embodiments of shutters, respectively, with a diameter of d ₁ and d ₂ (d ₁ <d ₂₎ , consisting of sectors (filters) with specified transmission spectra dλ _j , quantity j, area and sequence of their location. The device contains: 1 - lens, 2 - beam splitting prism; PVMS containing: 3, 9, respectively, the input and output transparent electrically conductive layers, 4 - a dielectric layer made in the form of a matrix of micro-discrete holes periodically filled with light-conducting material with different transmission spectra dλ _i [4], 5 - high-resistance photoconductor (FP) , 6 - charge reliefs formed in the volume of the phase transition from two sides, respectively: on the one hand, in the direction of propagation of the recording light E (x, y, Δλ _i ) and collinearly reflected and spectrum-modulated in the space δλ _i (x, y) and in belt δλ _j (t) of the reading light i ^* (x, y, δλ _{i, j} , f), and, on the other hand, in the direction of propagation of the spatially modulated reading light i (x, y, δλ) directed counter to the recording, 7 - polarization layer, 8 - electro-optical crystal (EOK); 10 - polarizing beam splitting prism, 11 - mirror, 12 - shutter, 13 - electromechanical drive and 14 - photosensor.

The essence of the proposed method for converting the color-luminance optical signal is as follows. The recording light (image) through the lens 1, the beam-splitting prism 2, the input conductive layer 3, the dielectric layer 4 are projected onto the FP 5, in the volume of which photoelectric conversion occurs, i.e., the conversion of the optical image into a spatially distributed (x, y) electrical signal (charge relief 6), proportional to the spatially modulated intensity E ₀ (x, y, Δλ) of the recording light. In this case, the charge relief photo-generation occurs only in those sections of the phase transitions that are under the areas of the matrix of micro-discrete holes periodically filled with filter materials with a transmission spectrum dλ _i , where i = 2, 3, 4 ... n, through which the recording light passed [4 ]. The plane-polarized spatially uniform readout light i ₀ (δλ) is projected collinearly towards the recording light through the beam-splitting polarizing prism 10 and the output conductive layer 9 from the side of the EOK 8, in which the electro-optical conversion occurs, i.e., the optical activity of the EOK controlled by spatially distributed (x , y) by electric field strength, changes the phase of polarization of the reading light i ₀ (δλ). The charge relief 6 leads to a spatial redistribution of the electric field in the EOK. Upon reaching the threshold value of the spatially distributed tension in the EEC in the areas (x, y) corresponding to the illuminated sections of the AF, the textured thickness of the EEC is destroyed. In sections (x, y) of textured fractures, the read light again changes the polarization phase. In this case, the phase modulation of polarization is converted by the polarization layer 7 into intensity modulation i (x, y, δλ). Spatially modulated in intensity in accordance with spatially distributed (x, y) fractures in the textured thickness of the EOK, the reading light i (x, y, δλ), which contains photoactive for high-resistance FP radiation, propagates into the FP layer, causing additional charge-generating photogeneration in it 6 Spatially modulated in intensity and transmitted through the FP 5, the reading light i (x, y, δλ) is matriced by a dielectric layer 4 made in the form of a matrix of microdiscrete holes filled with different materials i - filters and subtractively _{(δλ i = δλ-dλ i} (x, y)) is converted to a modulated spatially in intensity and spectrum of the reading light _{i (x, y, δλ i} ). Then, propagating to the mirror 11, the light i (x, y, δλ _i ) is modulated over the spectrum dλ _j in time t by the obturator 12. The obturator with a cyclic frequency ω = 2πf is rotated by an electromechanical drive 13. Since the obturator is made in the form of sectors consisting of j-filters with given transmission spectra dλ _j (j = 0,1,2,3 ... N) (Fig. 2), then for one full shutter turn-off, the spectrum δλ _{i of the} reading light is subtractively converted j - times into the spectra δλ _{i , j} (δλ _{i, j} = δλ-dλ _i (x, y) -2 • dλ _j (t), the factor 2 of the third term of the identity corresponds to double light through the j-filter (direct and back reflected) of the reading light i ^* (x, y, δλ _{i, j} , f). Collinearly reflected by the mirror 11 reading light i ^* (x, y, δλ _{i, j} , f), propagating in the opposite direction, in the direction of the recording light, secondarily causes additional photogeneration of the charge relief 6 in the volume of the phase transition 5 only when the subtractive spectrum δλ _{i, j} contains a photoactive component for the phase transition. The charge reliefs, respectively, according to the recording E ₀ (x, y, Δλ _i ) and the reading direct i (x, y, δλ) and the backward reflected i ^* (x, y, δλ _{i, j} , f) light are spatially combined in volume AF, and their amplitude textures are proportional, respectively, to the spatially distributed intensities of the recording and reading light.

As a result of summing the spatially inhomogeneous recording light E ₀ (x, y, Δλ _i ) (matriced by the dielectric layer 4 and transmitted through the PWMS) and modulated by the spectrum in time and space of the reading light i ^* (x, y, δλ _{i, j} , f) at the output of the device at any time, the optical signal is converted to I (x, y, Σλ, t) = E ₀ (x, y, Δλ _i ) + i ^* (x, y, δλ _{i, j} , f), where Σλ = Δλ _i + δλ _{i, j} . In this case, the additive conversion of the light-brightness optical signal is carried out by quickly alternating subtractive radiation δλ _{i, j of} different spectra with a frequency f. Temporary modulation of the reading light by the filters δλ _{j of the} shutter 12 (Fig. 2) can be carried out separately both by collinearly reflected flux i ^* (x, y, δλ _{i, j} , f) (Fig. 1), and by the direct initial flux i ₀ (δλ).
With simultaneous spectral-temporal modulation by one obturator (Fig. 3, 4) with a given number, area and sequence of arrangement of j-filters, flows i ₀ (δλ) and
i (x, y, δλ _i ) of reading light located radially coplanar along the obturator plane, the initial spectrum of reading light δλ at the output of the device at each instant of time will be subtractively converted to the spectrum δλ _{j, i, j} = δλ-dλ _j (t + π) -dλ _i (x, y) -2 • dλ _j (t). This increases the combination of possible combinations of additive and subtractive color mixing. Simultaneous modulation of the streams i ₀ (δλ) and i ^* (x, y, δλ _i ) of the light-reading light filters dλ _j (Fig. 3) can be carried out separately by two shutters with a given number, area and sequence of arrangement of light filters rotating synchronously or according to a given law .

 The spatial integration of the converted optical signal I (x, y, Σλ, t) at the output of the device (for example, by a focusing lens, not shown in the figures) additively mixes colors in accordance with the ratio of the areas occupied by elements of each color within the aperture.

The introduction of the photosensor 14 with a given spectral photosensitivity, optically coupled by the beam-splitting part i (δλ _j , f, t) of the reading light modulated over time by the obturator 12 (Fig. 3) and electrically connected to the optical signal processing device I (x, y, Σλ, t) (not shown in the figures), allows monitoring and controlling, according to a given law, the operation of the inventive device. According to the amplitudes of the photosensitivity of the photosensor 14, at given times, electronic decoding of the converted optical signal I (x, y, Σλ, t) is carried out, which determines the spectral composition of the time additive-subtractive conversion of the optical signal. Spectral coding and decoding of optical signals is also possible with optical communication of the photosensor 14 with a beam-splitting part i (x, y, δλ _{j, i, j} , f, t) of the reading light modulated over the spectrum in space and time (Fig. 3 is shown by dashed lines) lines). In this case, the beam-splitting part i (x, y, δλ _{j, i, j} , f, t) of the reading light carries spatial light-brightness information (image), which is contained in the converted optical signal I (x, y, Σλ, t )
Since the converted optical signal I (x, y, Σλ, t) is the sum of the additive-subtractive mixing of the recording E ₀ (x, y, Δλ _i ) (matriced by the dielectric layer 4) and modulated by the spectrum in the PMSC and the time by the reading light obturator i ^* (x, y, δλ _{i, j} , f, t), then setting the initial components of the transformation (control) (intensity i ₀ and the spectrum δλ of the reading light; transmission spectra dλ _i , dλ _j filters, their number i = 1,2 , 3 ... n, j = 1,2,3 ... N, and the arrangement sequence; frequency ω and the direction of rotation of the seal) and riruya at a given time the converted optical signal I (x, y, Σλ, t) or _{i (δλ j, f, t} ) i (x, y, δλ j, i, j, f, t), can be determined (decode ) the spectral composition Δλ and the spatial texture (x, y) of the initial recording light E ₀ (x, y, Δλ).
Thus, due to the internal photovoltaic OS formed primarily by direct reading light i (x, y, δλ) and secondly by collinearly reflected subtractive reading light i ^* (x, y, δλ _{i, j} ), charge reliefs photogenerated in FP 5 and therefore, the electro-optical response of the EOK 8 is proportional to the additive mixing of the spectra of the recording and reading light. In this case, the total reading light at the output of the device is the result of simultaneous additive spatially sequential and subtractive color mixing. When converting an optical signal, the error of combining the original E ₀ (x, y, Δλ _i ) and the converted auto-projected i (x, y, δλ) and i ^* (x, y, δλ _{i, j} ) images along the optical OS circuit will be determined only by the error collinearity of the streams of recording and reading light. When the collinearity condition is fulfilled, the coordinates of the source and converted images are combined.

 An essential distinguishing feature of the claimed method for converting an optical signal and a device for its implementation is additive-subtractive conversion of the light-luminance optical signal in the PVMS space and in time, modulated by the rotation speed of the obturator, which consists of several sectors with different light transmission spectra.

 The advantages of the proposed method for converting an optical signal and a device for its implementation compared to the prototype are to expand the functionality of the conversion of optical signals: firstly, additive-subtractive spatial-sequential conversion of the spectrum, and secondly, spatial spectral coding - decoding, and, thirdly, it becomes possible to quickly rebuild the spectrum of the converted optical signal by controlling electric or optical of their signals.

 In addition, the advantages of the proposed method and device are: firstly, the increase in the contrast of the converted optical signal when the optical activity of the EOK is doubled during direct and reverse collinear transmission of the reading light, and, secondly, the implementation of the precision internal photoelectric OS (autoprojection and combination of the original and converted images with collinearity of the recording and reading light), since the direct reading light serves as the control optical signal t, incorporating a photoactive component for the phase transition component.

Sources of information
1. Meshkov V.V., Matveev A.B. Fundamentals of lighting. Part 2 M .: Energoatomizdat, 1989 (analogue).

 2. Peysakhson IV. Optics of spectral instruments. - L .: Engineering, 1975.

 3. Vasiliev A. A., Casasent D., Kompanets I.N., Parfenov A.V. Spatial light modulators. - M .: Radio and communications, 1987 (prototype).

 4. Patent 2018957. Optical information carrier. Zakharov I.S., Spirin E.A., Mokrousov G.M. Registered August 4, 94

Claims (3)

 1. The method of converting an optical signal, which consists in projecting on one side the recording light of the lens onto a high-resistance photoconductor of a spatio-temporal light modulator, comprising an input conductive layer, a dielectric layer that is arranged in the form of a matrix of micro-discrete holes periodically filled, sequentially arranged in the direction of propagation of the recording light superconducting materials with different transmission spectra, high-resistance photoconductor, polar an insulating layer, an electro-optical crystal and an output transparent electrically conductive layer, combined into a single whole, on the other hand, modulated in space in intensity and spectrum of the reading light transmitted through a polarizing beam-splitting prism, an output transparent electrically conducting layer, an electro-optical crystal and a polarizing layer, in accordance with a charge relief in a layer of a high-resistance photoconductor, photogenerated modulated in space in intensity and in spectrum by recording light, characterized in that the light that is modulated in space in intensity and spectrum reads through a spatio-temporal light modulator and is reflected from the beam-splitting face of the beam-splitting prism, and is additionally modulated in time with a rotating shutter made in the form of sectors consisting of light filters with given transmission spectra, and are reflected back by a mirror through the beam splitting face of the beam splitting prism and the input transparent conductive layer n and the high-resistance photoconductor and electro-optical crystal are collinear to the reading light.  2. The method according to p. 1, characterized in that the reading light and modulated in space in intensity, spectrum and time collinearly reflected reading light is simultaneously modulated by a rotating obturator in spectrum over time.  3. A device for converting an optical signal containing a lens sequentially located in the direction of recording light propagation, a beam splitter, a spatio-temporal light modulator, consisting of an input transparent conductive layer, a dielectric layer, a high-resistance photoconductor, a polarization layer, an electro-optical crystal, and an output transparent conductive layer combined into a single whole, and a polarizing prism, characterized in that the obturate is introduced p with an electromechanical drive and a mirror outside the stream of recording light so that the working surfaces of the obturator and the mirrors are orthogonal to the direction of propagation of the reading light, while the obturator is made in the form of several sectors with different transmission spectra, and the dielectric layer is in the form of a matrix of micro-discrete holes periodically filled light-conducting materials with different transmission spectra.

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