JPH04160612A - Optical real time computing element - Google Patents

Abstract

PURPOSE:To obtain an optical real time computing element capable of executing arithmetic operation at real time by providing the computing element with the 3rd means for generating a contradictional optical change in accordance with the writing of the 1st or 2nd wavelength light and a reading means for reading out the optical change of the 3rd means based upon reading light. CONSTITUTION:The optical real time computing element 10 is constituted of the 1st space-light modulator (SLM) 12 for converting an input image 1 to the 1st wavelength lambda1, the 2nd SLM 14 for converting an input image into the 2nd wavelength lambda2 and an SLM (lambda - SLM) 16 for generating a change in optical characteristics such as transmissivity and polarization in the contradic tory direction in accordance with the sort of the wavelength. Either one of the wavelength lambda1, lambda2 is selected so that a change in the optical characteristics is generated in the contradictory direction in the gamma-SLM 16. Thereby, the sum/ difference arithmetic operation of two obtained images can be executed at real time. Consequently, the optical real time computing element 10 sufficiently utilizing the parallelism of light can simply be obtained.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an optical real-time arithmetic unit.

[Conventional technology]

For optical computing, sum and difference operations using optical operations are essential. Conventional optical calculations include those using multifunctional devices with sum/difference calculation functions such as spatial light modulators (hereinafter referred to as SLMs) using microchannel plates, and methods in which sum and difference calculations are performed optically, respectively. There is an optical-electrical hybrid system that electrically performs sum/difference calculations after photoelectric conversion. A neural network device 1 based on a conventional optical-electrical hybrid system shown in FIG. 10 includes a light emitting diode array 2 that outputs information on an original image, and a memory mask 3 that stores light output from the light emitting diode array 2.
and a photodetector array 4 for reading the memory of this memory mask 3. One row in the horizontal direction of the memory mask 3 is composed of the following two sub-pixel rows, and as shown in FIG. 8(B), the upper row represents +1 and the lower row represents −1, and each row represents a photodetector. The signals are read out to a corresponding pair of photodetectors PD 1 and PD 2 in the array 4, and the final difference calculation result of VO=R(I 2 -I 1) is output.

[Problem to be solved by the invention]

Those using the above-mentioned SLM etc., when calculating sums and differences,
Since the voltage must be converted to switch the calculation mode, there is a problem in that calculations cannot be performed in real time. Furthermore, in the case of the latter optical-electrical hybrid system that performs photoelectric conversion, there are problems in that the configuration is complicated and the parallelism of light cannot be fully utilized. This invention was made in view of the above-mentioned conventional problems, and an object of the present invention is to provide an optical real-time arithmetic unit that has a simple configuration, makes full use of optical parallelism, and can perform calculations in real time. shall be.

[Means to solve the problem]

This invention includes a first means for creating an image using a first wavelength, a second means for creating an image using a second wavelength different from the first wavelength, and a first means for creating an image using a second wavelength different from the first wavelength, and a second means for creating an image using the first wavelength and the second wavelength. The above-mentioned object is achieved by an optical real-time arithmetic unit comprising a third means for producing contradictory optical changes by writing, and a read-out means for reading out the optical changes in the third means using read-out light. It is. The first, second and third means may be spatial light modulators.

[Action and effect]

In this invention, the first means and the second means are different from the third means consisting of a light modulator, etc., in which changes in optical properties such as transmittance and polarization occur in opposite directions depending on the wavelength. By performing writing with different wavelengths from , and reading out the changes in the third means, it is possible to perform sum/difference calculations on the two images obtained by the first and second means in real time. Therefore, with this configuration, it is possible to easily realize an optical real-time arithmetic unit by making full use of the parallelism of light.

【Example】

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a basic embodiment of the present invention. The optical real-time arithmetic unit 10 according to this embodiment includes a first spatial light modulator (SLM) 12 that converts an input image 1 into a first wavelength λ 1, and a first spatial light modulator (hereinafter referred to as SLM) 12 that converts an input image 1 into a first wavelength λ1. A second SLM 14 that converts an image to a second wavelength λ 2 and an SLM (r-8LM hereinafter) 1 in which changes in optical properties such as transmittance and polarization occur in opposite directions depending on the wavelength.
6. Here, the wavelengths λ 1 and λ 2 are selected such that changes in the optical properties of the r-3 LM 16 occur in opposite directions. The first and second SLMs 12, 14 are so-called scattering SLMs that can two-dimensionally change the degree of scattering of the readout light by an external control signal. In this SLM12.14, as a modulation material for readout light,
For example, transparent ceramics or liquid crystal may be used, and the addressing method may be either an optical writing method or an electrical addressing method. The r-3LM 16 is an SLM that uses an optical material that has the property that when light having different wavelengths and planes of polarization is used, the amount of change in refractive index is opposite in positive and negative to each input light. Materials with such properties include organic materials such as bacteriorhodopsin (bR), BSO, LN (L
There are inorganic optical crystals such as iNbO3). The characteristics when the bR described above is used in the r-3LM16 are as follows. As shown in FIG. 2(A), the lens L1,
When measuring with one spectroscope with the pump light and globe light respectively incident from L2, the same figure (B)
, (C), the wavelength of the pump light is λ 1=
In the case of 410nm and in the case of λ 2-600nn+,
The change in absorption characteristics of sample bR18 appears completely opposite. For example, when the readout light λ 3 = 560 nIn, the image of λ 1 represents a negative amount, and the image of λ 2 represents a positive amount. Therefore, by appropriately determining λ 1 , λ 2 , and λ 3 so as to satisfy the above conditions, positive/negative calculations and weighting calculations can be performed. In the case of SO or LN, similar characteristics can be obtained by using light with a short wavelength for negative calculations. said first and second SLM12.14 to r-3LM1
Specific configuration for writing light input to 6, r-3L
The specific configuration of M16 and the configuration for inputting readout light are shown in FIG. Wavelengths λ 1, λ 2 of the first and second SLMs 12.14
The writing light of r is superimposed by the half mirror 20 and
-3LM16. This r-3
In the LM 16, tichroic mirrors 16B and 16C each having a characteristic of transmitting and reflecting desired wavelengths are arranged on both end faces of a light modulating material 16A. That is, the dichroic mirror 16B transmits light with wavelengths λ1 and λ2 and reflects the readout light with wavelength λ3, and the dichroic mirror 16C reflects light with wavelengths λ1 and λ2, and reflects light with wavelength λ3.
It is designed to transmit the readout light of No. 3. The readout light with a wavelength of λ 3 passes through a half mirror 22.
The modulated reflected light incident on the r-3LM 16 is transmitted through the half mirror 22 and taken out to form an output cover turn. Note that SLMs generally have a two-layer structure of an optical address material and a light modulation material, but the r-3LM16 in this example is made of bR, which has the functions of both an optical address material and a light modulation material. to 2
No layer structure is required. Next, the operation of the apparatus of the above embodiment will be explained. ′
The input @1 is input to the first SLM 12 and the wavelength λ 1
The light is read out as parallel light. Also, the input @2 is input to the second SLM 14, and the wavelength λ
It is read out as two parallel lights. These two @ (coherent images) of wavelengths λ 1 and λ 2 are simultaneously input to the r-3LM16. In this r-8LM16, the respective wavelengths λ1 and λ2
An optical change occurs as shown in FIG. 2 in response to the positive or negative amount of . Dichroic mirror 16B as mentioned above
, 16C, an optical real-time arithmetic unit is constructed by reading out the change using the readout light of wavelength λ3 from the wavelength selectivity of reflection and transmission of 16C. Next, a second embodiment of the present invention shown in FIG. 4 will be described. This second example uses an inorganic optical crystal.
This is for case 4. Here, as the photoaddressing material 24A, a combination of a photocathode and a microchannel plate, a-sr
, a-se, etc. are used. Further, as the light modulating material 24B, inorganic optical crystals such as LN, BS○, DKDP, etc. are used. A mirror/light shielding layer 24C is formed between the optical address material 24A and the optical modulation material 24B. In this embodiment, as shown in FIG. 4, a wavelength λ 1 light to which the optical addressing material 24A is sensitive is used as a positive value signal, and a light modulating material 24B is used as a negative value signal. A wavelength of λ 2 light is used that causes a photorefraction effect in a certain inorganic optical crystal. Therefore, the λ 1 light is made to enter from the optical addressing material 24A side, and the λ 2 light is made to enter from the light modulation material 24B side. Due to the incidence of the λ 2 light, polarization occurs in the crystal so that the electric field applied to the inorganic crystal constituting the light modulating material 24B is reduced. Therefore, the readout intensity approaches the O level as the λ 2 light increases, and functions equivalent to a negative amount. Therefore, by reading with the readout light λ 3, sum/difference calculations can be performed.Next, an application example of the optical real-time calculator configured as in the first and second embodiments will be described. First, it is possible to realize the side control of the Mexican hat-type function that the human eye has. By applying a Mexican hat-shaped function filter to the input image as shown in Figure 5 (A), the human eye can
Performing initial image processing (simple edge detection). FIG. 5 (
The function shown in A) is decomposed into a function that has a positive value and a function that has a negative value in all areas of input cover patterns as shown in Figure 5 (B), and the two decomposed By inputting the function to the optical real-time arithmetic unit, it is possible to obtain, from the output side, an image in which the Mexican hat arithmetic operation has been performed on the original pixels of all the pixels of the input pattern. Furthermore, the type of the function can be changed at any location. For example, as shown in Fig. 6, the original image Fig. 6 (A)
By applying filters with Mexican hat-shaped functions of different sizes to the original image, it is possible to decompose the original image into several copies with different levels of blur, and detect intensity changes for each copy separately. . For example, FIG. 6(B) is an image filtered with σ-8 pixels, and FIG. 6(C) is an image filtered with σ=4 pixels. The original image is made up of 320 pixels in the vertical direction and 320 pixels in the horizontal direction. In this way, by applying the filter to the original image, it is possible to put an upper limit on the range in which intensity changes occur in the original image and simplify the processing. FIG. 7 shows a specific configuration for applying the Mexican hat type function filter as described above to an input image. The embodiment shown in FIG. 7 includes an SLM 28A for obtaining an image of an arbitrary wavelength from an input image, and a beam splitter 30A for splitting the readout light of this SLM 28A into two, which are connected in series on one of the split optical paths. s-8L5-8L, 31M28B and 1 using the scattering effect placed on the s-8L5-8L, S-8L5-8L and S placed in series on the other branched optical path.
LM28C, a mirror 30B for merging readout lights of 31M28B and 28C, and a half mirror 30C;
r-8LM34 uses the combined readout light as the input image
It consists of and. Reference numbers 36A to 36D in the figure are
A half mirror for inputting read light of SLM28A to 28C and r-8LM34 is shown. The S-3L5-3L, 32B can change the degree of scattering of the readout light two-dimensionally by an external control signal. The readout light modulation material in these s-8L5-8L and 32B is PLZT or liquid crystal.
Furthermore, the address system can be configured to be compatible with either an optical writing type or an electrical writing type. In the case of the SLM using PLZT as described above, for example, when experimenting with the configuration shown in Fig. 8, the sample PL
It has been confirmed that when a voltage is applied perpendicular to the plane of the paper to the ZT 40, the relationship between the applied voltage and the output light pattern is such that the higher the voltage is applied, the greater the degree of scattering becomes. In other words, the type of the Mexican hat type function can be changed depending on the voltage. Reference numeral 42 in FIG. 8 is a helium neon laser, and 44 is an ND laser.
46 is a shutter, 48 is a polarizer, and 50 is a camera. Next, the operation of the above embodiment will be explained. First, the original image is input to the SLM 28A, where it is converted into a coherent image at a desired wavelength λ 0 . This coherent image is divided into two parts by the beam splitter 36A, s-3L5-3L and s-8L5, respectively.
- Input to 8L. A predetermined blurring operation is performed in these s-8L5-8L and 32B, and the respective output images are converted into images of respective wavelengths λ 1 and λ 2 in 31M28B and 28C. The output images of these 31M28B and 28C are half mirrors.
30C and input to r-3LM34. Here, the wavelength λ 1 of the output image of 31M28B, 28C,
As λ 2, r-3L as shown in FIG.
By selecting wavelengths that give opposite optical changes to M34, the r-S
, LM34 performs real-time positive/negative calculations to realize control of the input image, and the result is r
- It can be obtained as an output image of the SLM 34. That is, with the configuration of the embodiment shown in FIG. 7, a Mexican hat-shaped function filter is applied to the original image shown in circle A in the same figure, and the desired image is obtained as shown in circle B in the same figure. It is possible to obtain a blurred output image. In the embodiment shown in FIG. 7, s-3L5-3L and 3
1M28B position or s-, SLM32B and SLM28
A similar result can be obtained by interchanging the positions of C. In addition, by providing S-3LM32A and 32B with SLM functions, SLM28B
, 28C can also be omitted. Furthermore, in the configuration of FIG. 7, the s-3L5-3L and the SLM 28B may be omitted, and the output image of the SLM 28A may be input directly to the r-3LM 34 via the half mirror 30C. Next, an embodiment will be described in which a real-time optical neural network is constructed as shown in FIG. 9 using the optical real-time arithmetic unit as described above. In this embodiment, the photodetector array in the conventional optical-electrical hybrid system shown in FIG. It has been replaced. Further, in the sub-pixel columns constituting each row in the horizontal direction in the matrix of the memory mask 3 of this embodiment, the upper side (+1) is the first SLM (not shown) in the optical real-time calculation 52, and the lower side (-1) ) or a second SLM (not shown), respectively. Reference numeral 5 in FIG. 10 indicates an electrical feedback system. Neural networks are performed using simple calculations based on product-sum calculations, but large-scale parallelism is required. Conventionally, when a neural network device was configured with an optical-electrical hybrid system as shown in Fig. 10 described above, there were problems in that the configuration was complicated and the parallelism of light could not be fully utilized. However, in the optical neural network using the real-time optical arithmetic unit according to the present invention, the product can be realized optically by multiplying the transmittance, and the sum/difference calculation can be realized by the real-time arithmetic unit. By combining these, an all-optical neural network can be constructed as shown in FIG. With this device, data flows completely in parallel and calculations proceed optically, significantly reducing calculation time, which has been a problem in the past. In each of the above embodiments, spatial light modulators are used as means for creating images at wavelengths λ 1 and λ 2 and as means for producing contradictory optical changes by writing at different wavelengths, respectively. The present invention is not limited thereto, and if necessary, includes first and second means for creating an image of a desired wavelength from an original image, and a second means for producing contradictory optical changes by writing at these different wavelengths. Any method may be used as long as it includes the means described in 3 above.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing a basic embodiment of the optical real-time arithmetic unit according to the present invention, and Fig. 2 (A) shows the experimental configuration of a trial fIbR similar to the bR used in the r-8LM in the same embodiment. Optical system diagram, Figures 2 (B) and (C) are diagrams showing the characteristics of the same sample bR, Figure 3 is an optical system diagram showing the specific configuration of the above embodiment, and Figure 4 is a diagram showing the characteristics of the sample bR. FIG. 5 is a block diagram showing the second embodiment; FIG. 5 is a diagram showing a Mexican hat type function when the optical real-time arithmetic unit according to the present invention performs source control similar to the human eye; FIG. 6 is a diagram showing a Mexican hat type function. FIG. 7 is a plan view showing the process of applying a filter using a function to an original image, FIG. 7 is an optical system diagram showing an embodiment for performing source control using an optical real-time arithmetic unit according to the present invention, and FIG. FIG. 9 is an optical layout diagram showing an experimental system for measuring the characteristics of PLZT that is not used in r-3LM; FIG. 9 is a perspective view showing an embodiment in which the optical real-time computing unit of the present invention is applied to an optical neural network device; Figure 10 (
A) is a perspective view showing a model of a conventional optical-electrical hybrid neural network device, and FIG. 2B is a circuit diagram showing the relationship between the memory mask and the photodetector. 10.52... Optical real-time arithmetic unit, 12... Spatial light modulator (SLM), 14... Second spatial light modulator (SLM), 16...
Third spatial light modulator (r-3LM), 18...sample b
R1 20, 22... Half mirror 1 24A... Optical address material, 24B... Light modulation material, 28A-28C... SLM, 32A, 32B... s5-8L, 34-r-8LM, 54... Optical feedback system.

Claims (2)

[Claims] (1) A first means for creating an image using a first wavelength; a second means for creating an image using a second wavelength different from the first wavelength; and writing using the first and second wavelength lights. , a third means for producing opposite optical changes; and a readout means for reading out the optical change in the third means using readout light. (2) The optical real-time computing device according to claim 1, wherein the first, second, and third means are spatial light modulators.