JP2000067459A - Optical processing method and optical processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make easily and speedingly conductible an arbitrary arithmetic operation such as summing, or differencing and logical operation between data such as two pictures recorded in an optical recording medium. SOLUTION: In a first step of a recording, the polarization direction of signal light beams is set to 0 deg. and the polarization direction of a reference light beams is also set to 0 deg. and the signal light beams of a picture (A) are recorded on an optical recording medium as a first sheet hologram. In a second step, the polarization direction of the signal light beans is set to 90 deg. and the polarization direction of the reference light beams is set to 0 deg. and the signal light beams of a picture (B) are multiplexed and recorded onto the first sheet hologram as a second sheet hologram. During a reading, the medium is irradiated by the reading light beams same as the reference light beams during a recording, the diffracted light beams from the hologram are passed through a polarizer and detected and the transmissive axis of the polarizer is adjusted in an arbitrary direction. If the transmissive axis of the polarizer is set to 45 deg., a picture (C), which is the added output of the pictures (A) and (B), is obtained and by conducting a threshold value processing, an ANDing picture (E) or an ORing picture (F) is obtained. If the transmissive axis of the polarizer is set to 135 deg., a picture (an exclusive OR picture) (D), which is the differencing output of the picture (A) and the picture (B), is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical processing method and an optical processing apparatus for reading data from an optical recording medium in which data such as an image is recorded as a hologram.

[0002]

2. Description of the Related Art In a device such as a defect inspection device that compares a pattern to be measured and a mask pattern and detects only a portion different between the two patterns, and a visual sensor that detects only a new object from background light, etc. , Usually, by detecting two image patterns and calculating the sum and difference thereof,
The difference between the two images is identified to detect a defect or movement of the object.

The calculation of such two images is usually performed by a computer. However, image processing by a computer basically has a drawback that the processing time is long because the calculation is performed sequentially for each pixel. Therefore, it is practically difficult to calculate the sum or difference of two images in real time. In order to shorten the processing time, a high-speed computer or a parallel computer is required. However, this is expensive, large, and not suitable for practical use.

As a method for solving this problem, Japanese Patent Laid-Open No.
No. 107827 discloses that an irreversible grating is formed in a medium according to a change in light intensity caused when a coherent probe light and a pump light are incident with their polarization directions parallel to each other, A reversible (temporary) grating is formed in the medium in accordance with the polarization direction modulation that occurs when the polarization direction is perpendicularly incident, and another coherent pump light having the same polarization direction as the pump light is generated. A holographic reproduction process using an irreversible grating and a four-wave mixing process using a reversible grating, when the light is made to face the pump light, the polarization directions of the probe light parallel and perpendicular to the pump light, respectively. By generating two orthogonal phase conjugate lights having polarization directions equal to and comparing the two phase conjugate lights, the sum of the two images is calculated. How to calculate the difference are shown.

[0005]

However, the method disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 3-107827 has the following problems. In the above method, one of the two images is reproduction light (phase conjugate light) from a hologram recorded on a medium, and the other is reproduction light (phase conjugate light) obtained in real time by four-wave mixing. It is. Therefore, two images to be calculated cannot be simultaneously recorded on a medium. Therefore, when the above method is used as a hologram memory system for storing images and digital data, it is not possible to perform calculations between a plurality of recorded images and digital data. Also, in the above method,
In order to record the obtained calculation result, a storage device is separately required.

Further, in the above method, two images cannot be simultaneously recorded on a medium, and two images cannot be reproduced simultaneously in real time. There is a problem that the sum or difference of two images cannot be calculated.

Therefore, the present invention enables arbitrary and simple operations such as sum or difference operations and logical operations to be performed between data such as two images recorded on an optical recording medium. It was made.

[0008]

According to the optical processing method of the present invention, two signal lights having polarization directions orthogonal to each other are recorded in the same area of the optical recording medium by the same reference light. By irradiating the same read light as the reference light to obtain a diffracted light in which two diffracted light components having polarization directions orthogonal to each other are synthesized, and by extracting an arbitrary polarized light component from the diffracted light, An operation output between two data recorded as two signal lights is obtained.

[0009]

The applicant previously disclosed in Japanese Patent Application No. Hei 10-32834, by changing the polarization direction of signal light or reference light and recording a plurality of signal lights as a plurality of holograms in the same area of an optical recording medium in a multiplex manner. Suggested to do.

In the optical recording method of the prior application, the signal light and the reference light are polarized in two directions, that is, a direction parallel to each other and a direction orthogonal to each other. Two signal lights can be multiplexed and recorded as two holograms in the same region of a recordable optical recording medium (hereinafter referred to as a polarization-sensitive optical recording medium).

According to this, for example, in the first step, the polarization directions of the signal light and the reference light are made parallel to each other, the first signal light is recorded as the first hologram, and in the second step, the signal light is recorded. By rotating the polarization direction of the light by 90 °, the polarization directions of the signal light and the reference light are made orthogonal to each other, and the second signal light is used as a second hologram in the area where the first hologram is recorded. Can be recorded.

At the time of reading, a reproduced image can be obtained from each of the two holograms by irradiating an area where two holograms are recorded with the same reading light as the reference light at the time of recording. However, the diffracted light component from the first hologram and the diffracted light component from the second hologram have orthogonal polarization directions.

Therefore, a polarizer is arranged in the optical path of the diffracted light,
By making the direction (transmission axis) of the polarizer coincide with the polarization directions of two diffracted light components of which the polarization directions of the diffracted light are orthogonal to each other, the two diffraction images are separated and read out, and are multiplex-recorded. Two data can be read separately.

Using the optical recording method of the prior application, in the optical processing method of the present invention, as described above, two signal lights having polarization directions orthogonal to each other are recorded in the same area by the same reference light. In the area of the optical recording medium
By irradiating the same read light as the reference light to obtain a diffracted light in which two diffracted light components having polarization directions orthogonal to each other are synthesized, and by extracting an arbitrary polarized light component from the diffracted light, An arithmetic output between two data recorded as two signal lights is obtained.

Therefore, according to the optical processing method of the present invention, any operation, such as a sum or difference operation or a logical operation, between two data such as images recorded on an optical recording medium can be performed simply and at high speed. Can be done.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [Principle of Light Processing Method] FIG. 1 shows the principle of a light processing method according to the present invention. As described above, in the optical recording medium, the signal light of the first image and the signal light of the second image having the polarization directions orthogonal to each other are formed as holograms by the same reference light in the same area. It is recorded in.

By irradiating the area where the two holograms are recorded with the same readout light as the reference light at the time of recording, a reproduced image is obtained from each of the two holograms. However, as shown in FIG. 1, the polarization direction of the diffracted light component A1 from the first hologram and the diffracted light component A2 from the second hologram are orthogonal to each other.

As described above, the polarizer is arranged in the optical path of the diffracted light. When the direction θ of the polarizer is set to 0 ° and coincides with the polarization direction of the diffracted light component A1, only the diffraction image of the first hologram can be separated and taken out. At this time, assuming that the amplitude of the diffracted light component A1 is T1,
Light intensity transmitted through the polarizer | proportional to ² | T1.

When the direction θ of the polarizer is set to 90 ° and coincides with the polarization direction of the diffracted light component A2, only the diffraction image of the second hologram can be separated and taken out.
At this time, when the amplitude of the diffracted light components A2 and T2, the light intensity transmitted through the polarizer | proportional to ² | T2.

[0020] In the azimuth θ of the polarizer 45 °, when parallel to the direction of the two composite vectors of the diffracted light components A1 and A2, the light intensity transmitted through the polarizer | becomes proportional to ² | T1 + T2 . That is, by setting θ = 45 °, the sum of the two diffracted light components A1 and A2 is obtained.

When the azimuth θ of the polarizer is set to 135 ° and is orthogonal to the direction of the combined vector of the two diffracted light components A1 and A2, the light intensity transmitted through the polarizer is | T1−T2 | ²
Becomes proportional to That is, by setting θ = 135 °, a difference between the two diffracted light components A1 and A2 is obtained.

The first and second images read as the diffracted light components A1 and A2 are shown in FIG.
If a binary image as shown in FIG.
When the angle is set to °, the added output becomes an image as shown in FIG. 7C, and when the angle θ is set to 135 °, the subtracted output becomes an image as shown in FIG. The image of the subtraction output in FIG. 11D is an exclusive OR (XOR) of the first and second images.

Also, the image of the addition output of FIG. 3C is subjected to threshold processing by a computer or the like, so that the logic of the first and second images as shown in FIG. An image of a product (AND) or an image of a logical sum (OR) as shown in FIG.

As described above, according to the present invention, two images to be calculated can be recorded in advance in the same area of an optical recording medium as a hologram. Then, at the time of reading, by simply adjusting the orientation of the polarizer arranged in the optical path of the diffracted light, an arbitrary operation output such as a sum or difference or a logical operation output of the two images recorded as the hologram is obtained. be able to.

[Embodiment of Light Processing Method and Light Processing Apparatus] FIG. 3 shows one embodiment of the light processing method and light processing apparatus of the present invention. The coherent light from the light source 30 is
The beam is split into two lights by a beam splitter 31, and at the time of recording, a shutter 32 is opened, and the light transmitted through the beam splitter 31 is converted into wide-parallel light by lenses 33 and 34, and is incident on the spatial light modulator 20.

As described later, an image is displayed on the spatial light modulator 20 by the computer 50 and the spatial light modulator 2 is displayed.
As the light passing through 0, a signal light having information of an image displayed on the spatial light modulator 20 is obtained, and this signal light is passed through a half-wave plate 21 to be converted into a signal light 1 having a predetermined polarization direction. Convert to

The signal light 1 having passed through the half-wave plate 21
Is condensed by the lens 35 and is irradiated on the above-mentioned polarization-sensitive optical recording medium 10. At the same time, the light reflected by the beam splitter 31 is reflected as the reference light 2 by the mirrors 37 and 38, and is applied to an area of the optical recording medium 10 where the signal light 1 is applied. Thereby, the optical recording medium 1
0, the signal light 1 and the reference light 2 interfere with each other, and the optical recording medium 10
A hologram is recorded inside.

In this case, in the first stage, as the first image, an image as shown in FIG.
0, and the 波長 wavelength plate 21 is adjusted so that the polarization direction of the signal light 1 passing therethrough is perpendicular to the paper surface (this is set to 0 °), and the signal light 1 and the reference light 2 are adjusted. At the same time, the first hologram is recorded in the optical recording medium 10.

Next, in the second stage, as the second image, an image as shown in FIG.
And the signal light 1 and the reference light 2 are adjusted by adjusting the half-wave plate 21 so that the polarization direction of the signal light 1 passing therethrough is parallel to the paper surface (this is 90 °). By irradiating the optical recording medium 10 at the same time, a second hologram is recorded in an area of the optical recording medium 10 where the first hologram is recorded.

However, the polarization direction of the reference light 2 is the same when recording the first hologram and when recording the second hologram.

At the time of reading, the signal light 1 is shut off by closing the shutter 32, and the same light as the reference light 2 at the time of recording is irradiated to the optical recording medium 10 as the reading light 3. The irradiated reading light 3 is diffracted by the hologram recorded in the optical recording medium 10.

The diffracted light 4 is converted by the lens 36 into C
An image is formed on a photodetector 40 such as a CD, and a data image of the signal light 1 is read. In this case, the polarizer 22 is arranged between the lens 36 and the photodetector 40, and the connection is omitted in the figure. However, by adjusting the transmission axis of the polarizer 22 in an arbitrary direction by the computer 50, As described below, only the first image or the second image, or an arbitrary calculation output between the first image and the second image is read.

As described with reference to FIG. 1, when reading only the first image, the transmission axis of the polarizer 22 is set to 0 °.
When reading only the second image, the polarizer 2
The transmission axis of No. 2 is 90 °. Assuming that the amplitude of the diffracted light component A1 from the first hologram recorded in the first stage is T1, and the amplitude of the diffracted light component A2 from the second hologram recorded in the second stage is T2, a polarizer is used. 22 transmission axes
°, the light intensity transmitted through the polarizer 22 is | T
1 | ² in proportion, when the transmission axis of the polarizer 22 was 90 °, the light intensity transmitted through the polarizer 22 | proportional to ² | T2.

However, this is the case where the polarization of the signal light 1 is reproduced faithfully to the diffracted light 4. Actually, the polarization direction of the diffracted light 4 may slightly deviate from that of the signal light 1 due to the polarization characteristics of the optical system and the optical recording medium 10. However, even in such a case, the polarization directions of the two multiplex-recorded images are kept orthogonal to each other. Therefore, by appropriately adjusting the transmission axis of the polarizer 22, crosstalk between the two images can be reduced. It can be separated and taken out without generating.

If the transmission axis of the polarizer 22 is set at 45 °, the light intensity transmitted through the polarizer 22 becomes proportional to | T1 + T2 | ^2, and an added output of two images is obtained. When the transmission axis of the polarizer 22 is set to 135 °, the polarizer 2
2 is proportional to | T1−T2 | ^2, and a subtraction output of two images is obtained.

The two images represented by the amplitudes T1 and T2 are respectively "light" (data "1") and "dark" of light.
If the image is a binary image represented by (data “0”),
Subtracting outputs of the two images | T1-T2 | ² also becomes binary data, equivalent to the exclusive OR of the two images as shown in FIG. 2 (D) (XOR).

On the other hand, the added output of two images | T1 + T2
| ² has three values (brightness) of “1 + 1”, “1”, and “0”.
If “+1” and “1” are “bright” and “0” is “dark”, a logical sum (OR) of two images is obtained as shown in FIG. "Bright", "1" and "0" are "dark"
Then, a logical product (AND) of the two images is obtained as shown in FIG.

[Embodiment] Recording and reproduction were actually attempted by the method described above. The optical recording medium 10 may be of any type as long as the hologram can be recorded, regardless of the value of the polarization angle between the signal light 1 and the reference light 2. A polyester having a cyanoazobenzene in a side chain, represented by the chemical formula shown below, was used.

As described in detail in Japanese Patent Application No. 10-32834, this material can be used for photo-induced anisotropy (photo-induced birefringence, photo-induced two-color) by photoisomerization of side chain cyanoazobenzene. ), The polarization direction of the signal light can be recorded as a hologram. By making the polarization direction of the hologram readout light equal to that of the reference light, diffracted light having the same polarization direction as the signal light can be obtained. Also, by changing the polarization direction of the signal light or the reference light, a plurality of signal lights can be multiplexed and recorded as a plurality of holograms in the same area of the optical recording medium. That is, when two signal lights having polarization directions orthogonal to each other are recorded in the same area of the optical recording medium by the same reference light and read out by the same reading light as the reference light, the orthogonal polarization directions equal to the signal light are changed. The two diffracted light components can be obtained at the same time. Further, the recorded hologram is maintained without relaxation for several years or more under room-temperature natural light.

The light source 30 includes the optical recording medium 10,
An 515 nm oscillation line of an argon ion laser sensitive to polyester having cyanoazobenzene in the side chain was used. The spatial light modulator 20 has a pixel size of 42 μm.
A 1.3-inch liquid crystal panel for projectors having m × 42 μm and 640 × 480 pixels was used.

In the first stage of recording, the first image shown in FIG. 2A is created by the computer 50 and displayed on the spatial light modulator 20, and the half-wave plate 21 is set to the signal light 1 Is adjusted so that the polarization direction becomes perpendicular (0 °) to the paper surface, and the signal light 1 and the reference light 2 are simultaneously irradiated on the optical recording medium 10, so that the first hologram is placed in the optical recording medium 10. Recorded. At this time, the polarization direction of the reference light 2 was set to 0 °, which is the same as that of the signal light 1.

In the second stage of recording, the second image shown in FIG. 2B is created by the computer 50 and displayed on the spatial light modulator 20, and the half-wave plate 21 is set to the signal light 1 Is adjusted so that the polarization direction is parallel (90 °) to the paper surface, and the signal light 1 and the reference light 2 are simultaneously irradiated on the optical recording medium 10 so that the first hologram in the optical recording medium 10 is A second hologram was recorded in the recorded area. At this time, the polarization direction of the reference light 2 was set to 0 ° which is the same as the first stage.

At the time of reading, the signal light 1 was shut off by closing the shutter 32, and the same light as the reference light 2 at the time of recording was irradiated to the optical recording medium 10 as the reading light 3. Read light 3
Was set to 0 ° which is the same as the reference light 2. Diffracted light 4
Was imaged on the photodetector 40 by the lens 36, and the data image of the signal light 1 was read.

When the transmission axis of the polarizer 22 is substantially 0 °, the first image shown in FIG. 2A is detected. When the transmission axis of the polarizer 22 is substantially 90 °, the first image shown in FIG.
The second image shown in (B) was detected.

When the transmission axis of the polarizer 22 is set to approximately 45 °, the image of the added output shown in FIG. 2C is detected. The image of the subtraction output (the image of exclusive OR) shown in D) was detected. FIG. 2E shows an addition output image obtained when the transmission axis of the polarizer 22 is set to approximately 45 ° by performing threshold processing while changing the threshold value in two ways. Thus, the image of the logical product and the image of the logical sum shown in FIG. 2 (F) were obtained.

[Other Embodiments] The material of the polarization-sensitive optical recording medium 10 is not limited to polyester having cyanoazobenzene in the side chain, but is generally a polymer having a photoisomerizable group in the side chain. Alternatively, a polymer liquid crystal is preferable. As the photoisomerizable group, a group containing an azobenzene skeleton is preferable, and as the polymer or the polymer liquid crystal, at least one group appropriately selected from the polyester group is used.
Some monomeric polymers are preferred.

Further, the entire optical recording medium 10 is not formed of such a material exhibiting light-induced anisotropy, but is provided on one surface side of a transparent substrate such as a glass substrate. May be formed.

[0048]

As described above, according to the optical processing method and the optical processing apparatus of the present invention, a sum or difference operation, a logical operation, or the like is performed between data such as two images recorded on an optical recording medium. Can be simply and quickly performed. Further, according to the optical processing method of the present invention, it is possible to realize a digital memory system for performing arithmetic processing on digital data recorded on an optical recording medium and outputting the digital data, and reduce the load on the CPU of the computer. .

[Brief description of the drawings]

FIG. 1 shows the polarization direction of signal light in the optical processing method of the present invention;
FIG. 3 is a diagram illustrating a relationship between a polarization direction of diffracted light and an orientation of a polarizer.

FIG. 2 is a diagram showing an example of an input image and an output image in the light processing method of the present invention.

FIG. 3 is a diagram showing one embodiment of a light processing method and a light processing apparatus of the present invention.

FIG. 4 is a diagram showing a chemical formula of an example of a material of an optical recording medium used in the optical processing method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Signal light 2 ... Reference light 3 ... Reading light 4 ... Diffraction light 10 ... Optical recording medium 20 ... Spatial light modulator 21 ... 1/2 wavelength plate 22 ... Polarizer 30 ... Light source 31 ... Beam splitter 32 ... Shutter 40 ... Photodetector 50 ... Computer

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kazuo Baba 430 Sakai, Nakagawa-machi, Ashigara-gun, Kanagawa Prefecture Green Tech Nakai Fuji Xerox Co., Ltd. F-term (reference) 2K008 AA01 AA04 AA06 AA17 BB04 BB06 CC01 DD12 HH12 HH14 HH26 5D119 BA01 BB20 CA20 FA02 JA31 JA33 JA70 KA07 KA08 KA11

Claims (8)

[Claims] 1. An area of an optical recording medium in which two signal lights having polarization directions orthogonal to each other are recorded in the same area by the same reference light, is irradiated with the same reading light as the reference light, By obtaining a diffracted light in which two diffracted light components having polarization directions orthogonal to each other are combined, and extracting an arbitrary polarized component from the diffracted light, two data recorded as the two signal lights in the area are obtained. An optical processing method characterized by obtaining an operation output during the period. 2. The optical processing method according to claim 1, wherein a polarization component parallel to a combined vector of the two diffracted light components is extracted from the diffracted light by a polarizer, thereby obtaining an addition output as the arithmetic output. A light processing method characterized by the above-mentioned. 3. The optical processing method according to claim 2, wherein a logical product or a logical sum of the two data is obtained by subjecting the added output to threshold processing. 4. The optical processing method according to claim 1, wherein a polarization component orthogonal to a combined vector of the two diffracted light components is extracted from the diffracted light by a polarizer, so that the subtraction output or the exclusive output is obtained as the arithmetic output. An optical processing method characterized by obtaining a logical sum. 5. The polarization-sensitive method according to claim 1, wherein the optical recording medium is made of a polymer or a polymer liquid crystal having a photoisomerizable group in a side chain on at least one side. A light processing method comprising a layer. 6. The light processing method according to claim 5, wherein the photoisomerizable group contains an azobenzene skeleton. 7. The light processing method according to claim 5, wherein the polymer or liquid crystal polymer is at least one monomer polymer selected from a polyester group. 8. An area of an optical recording medium in which two signal lights having polarization directions orthogonal to each other are recorded in the same area by the same reference light, is irradiated with the same reading light as the reference light, An optical system that obtains a diffracted light in which two diffracted light components having polarization directions orthogonal to each other are combined; a polarizer that extracts an arbitrary polarized light component from the diffracted light; and a light that detects the polarized light component transmitted through the polarizer. A light processing device comprising: a detector;