JP2836137B2 - Optical information processing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a visual device such as an industrial robot, which performs image processing such as filtering and feature extraction of an input image in a spatial frequency domain, or a specific standard based on a plurality of input patterns. The present invention relates to an optical information processing apparatus that identifies a pattern that matches a pattern.

2. Description of the Related Art As an example of a conventional optical information processing apparatus, an optical correlation processing apparatus that identifies a pattern that matches a specific standard pattern from a plurality of input patterns will be described below.

FIG. 3 is a plan view of a conventional optical information processing apparatus.
Reference numeral 20 denotes a TV camera, 21 denotes a first liquid crystal display for displaying an input image captured by the TV camera 20, 22 denotes a semiconductor laser, 23 denotes a collimator lens for converting light from the semiconductor laser 22 into parallel light, and 24 denotes a first The first liquid crystal display 21 is disposed on the front focal plane of the first lens 24. Reference numeral 25 denotes a second liquid crystal display, which is disposed on the rear focal plane of the first lens 24. Reference numeral 26 denotes a plurality of standard patterns which are calculated in advance by using each pixel on the second liquid crystal display as a sampling point. Of Fourier transform computer generated hologram, ie, second liquid crystal display
Write the data of the applied voltage corresponding to the transmittance of each of the 25 pixels, read only memory (hereinafter referred to as ROM), 2
Reference numeral 7 denotes a second lens, on which a second liquid crystal display 25 is disposed on the front focal plane. 28 is the second lens 27
Is a photoelectric conversion device arranged on the rear focal plane.

Next, the operation of the conventional optical information processing apparatus configured as described above will be described with reference to FIG. First, TV
An image of the target object captured by the camera 20 is displayed on the first liquid crystal display 21. The first liquid crystal display 21 is irradiated with coherent light from a semiconductor laser 22 that has been collimated by a collimator lens 23. Since the first liquid crystal display 21 is arranged on the front focal plane of the first lens 24, the first liquid crystal display 21 is placed on the rear focal plane of the first lens 24, that is, on the second liquid crystal display 25. A Fourier-transformed image optically converted by the lens 24 is formed.

At this time, a Fourier transform pattern of a standard pattern is displayed on the second liquid crystal display 25 as a matched filter.
The data written in the ROM 26 is used as an input signal to spatially modulate the transmittance of each picture element of the second liquid crystal display 25, so that the data is shown in the form of a Fourier transform computer generated hologram. Therefore, the Fourier transform image obtained by optically transforming the pattern of the target object displayed on the first liquid crystal display 21 by the first lens 24 and the Fourier transform image of the standard pattern are superimposed on the second liquid crystal display 25. Is done. This 2
The optical product of the four Fourier transform images is inversely Fourier transformed by the second lens 27. As a result, if the pattern of the target object and the Fourier transform image of the standard pattern on the second liquid crystal display 25 match, that is, if the two are the same object, a bright spot is formed on the rear focal plane of the second lens 27. It is generated and detected by the photoelectric conversion means 28.

In the above configuration, the input pattern 3 is illuminated with parallel light and is formed as a Fourier transform image of the input pattern on the rear focal plane of the first lens 24, that is, on the second liquid crystal display 25. However, at this time, the size DH of the Fourier transform image is represented by DH = λ * f * Sf. Here, λ indicates the wavelength of the laser, f is the focal length of the first lens 4, Sf
Indicates the highest spatial frequency included in the input pattern 3. That is, assuming that the input pattern is constant, the size of the Fourier transform image changes depending on the focal length of the first lens 24.

Since the focal length of the first lens 24 is constant in the conventional device, the size of the Fourier transform image changes depending on the input pattern. That is, when the maximum spatial frequency included in the input pattern is small, the Fourier transform image becomes small, and when the maximum spatial frequency is large, the Fourier transform image becomes large.

Therefore, the size of the matched filter must be changed correspondingly. Therefore, the display medium of the matched filter is required to have both characteristics of a resolution for displaying a faithful computer hologram image in a small matte filter and a size for displaying a large matched filter. Both of these characteristics were easily realized with a mat filter using a photographic dry plate.

On the other hand, a spatial light modulator, which has been actively researched and developed recently, for example, the liquid crystal display shown in FIG. 3 can be relatively easily enlarged, but it is difficult to obtain a resolution equivalent to a photographic plate. . In addition, it has been difficult to achieve the two characteristics such that it is relatively easy to obtain the resolution of the optical crystal with the BSO crystal, but it is difficult to increase the size.

According to the present invention, the size of the Fourier transform image of the input pattern, that is, the size of the matte filter is changed by changing the focal length of the first lens in accordance with the output signal from the means for detecting the size of the Fourier transform image of the input pattern. An object of the present invention is to control and relax restrictions on the resolution or size of the spatial light modulator.

Means for Solving the Problems The present invention provides a first spatial light modulator for displaying an image captured by a TV camera, a light source for irradiating the first spatial light modulator, and a first spatial light. A first lens having a surface on which the modulation element is placed as a focal plane on the front side thereof;
And a semi-transmissive mirror disposed between the rear focal plane of the first lens and a concentric circle disposed on the rear focal plane of the first lens in the reflection optical path of the semi-transmissive mirror. A photodetector forming the detection unit, and a first light path of a transmission light path of the semi-transmission mirror.
A second spatial light modulator disposed on a rear focal plane of the first lens, a second lens having a rear focal plane on the rear side of the first lens, and a second lens A photoelectric conversion device disposed on a rear focal plane; and a focal length variable unit that controls a focal length of the first lens based on an output signal of the photodetector, wherein the first and second spatial light modulations are provided. The transmittance of each element of the element is spatially modulated to display a computer generated hologram.

According to the present invention, an image input from a TV camera is displayed on a first spatial light modulation element by the above-described configuration to form an input pattern, and an optical filter such as a computer hologram is used for a second spatial light modulation element.
Display on the spatial light modulator of the present invention, performs various parallel optical arithmetic processings on a large number of input patterns in real time, and detects the size of the Fourier transform image of the input pattern formed by the first lens. By changing the focal length of the first lens according to the output signal, the size of the Fourier transform image of the input pattern can be controlled, and the restriction on the resolution or size of the spatial light modulator can be relaxed.

Embodiment 1 A first embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG.

FIG. 1 is a plan view of a first embodiment of the present invention. 20 is
A TV camera, 21 is a first liquid crystal display for displaying an input image taken by the TV camera 20, 22 is a semiconductor laser,
Reference numeral 23 denotes a collimator lens for converting the light from the semiconductor laser 22 into parallel light, and reference numeral 24 denotes a first lens. As shown in FIG. Is variable. The first liquid crystal display 21 is disposed on the front focal plane of the first lens 24. 25 is a second liquid crystal display and a first lens
It is located at the back focal plane of 24. Reference numeral 26 denotes data of a Fourier transform computer generated hologram calculated in advance for each of a plurality of standard patterns using each picture element on the second liquid crystal display as a sampling point, that is, the second liquid crystal display 25.
A read-only memory (hereinafter referred to as a ROM) in which data of an applied voltage corresponding to the transmittance of each picture element is written, 27 is a second lens, and a second liquid crystal display 25 is arranged on a front focal plane of the second lens. ing. Reference numeral 28 denotes a photoelectric conversion device disposed on the rear focal plane of the second lens 27, and reference numeral 30 denotes a first lens 24.
A semi-transmissive mirror arranged between the first liquid crystal display 21 and
31 is a photodetector for detecting the size of the Fourier transform image of the input pattern disposed on the rear focal plane of the first lens 24 in the reflected light path of the semi-transmissive mirror 30, and 32 is based on the output signal of the photodetector 31. A focal length varying unit that controls a focal length of the first lens. Reference numeral 33 denotes a third lens, which is disposed between the semi-transmissive mirror 30 and the photodetector 31. In this embodiment, the first lens 24 and the third lens 33 are combined with the third lens 33 by using a convex lens. The distance is shorter than the focal length of the first lens 24 alone.

Next, the operation of the first embodiment of the present invention configured as described above will be described below with reference to FIGS.

FIG. 2 shows a photodetector for detecting the size of a Fourier transform image.
31 is a plan view of FIG. The pattern of the target object imaged by the TV camera 20 is displayed on the first liquid crystal display 21. This first liquid crystal display 21 is a collimator lens
Irradiation is performed by coherent light from the semiconductor laser 22 which has been made parallel by the light 23. This first liquid crystal display
Since the reference numeral 21 is disposed on the front focal plane of the first lens 24, the first lens in the reflection optical path and the transmission optical path of the semi-transmission mirror 30 is used.
The first lens of the pattern of the object on the back focal plane of 24, ie on the photodetector 31 and on the second liquid crystal display 25
24 forms an optically transformed Fourier transform image. As shown in FIG. 2, the photodetector 31 is constituted by arranging six ring-shaped detecting portions 31a to 31f concentrically. Therefore, the size of the Fourier transform image optically transformed by the first lens 24 of the pattern of the target object is determined by detecting the output signal of each of the concentric ring-shaped detectors 31a to 31f. Can be identified.

The focal length of the first lens 24 is controlled by the focal length varying means 32 based on the output of the photodetector 31 indicating the size of the Fourier transform image of the pattern of the target object. That is,
The focal length f of the first lens 24 is set so that the size DH of the Fourier transform image of the input pattern represented by DH = λ * f * Sf is substantially equal to the size of the second liquid crystal display 25. Control.

At this time, the Fourier transform image of the standard pattern is displayed on the second liquid crystal display 25 as an optical matched filter.
The data written in the ROM 26 is used as an input signal to spatially modulate the transmittance of each picture element of the second liquid crystal display 25, thereby displaying the data in the form of a Fourier transform computer generated hologram. Therefore, the Fourier transform image obtained by optically transforming the pattern of the target object displayed on the first liquid crystal display 21 by the first lens 24 and the Fourier transform image of the standard pattern are displayed on the second liquid crystal display 25. Superimposed.

The second liquid crystal display 25 is a second lens.
Since it is arranged on the front focal plane of 27, the optical product of the two Fourier transform images of the pattern of the target object and the standard pattern is inversely Fourier transformed by the second lens 27. if,
When the pattern of the target object and the Fourier-transformed image of the standard pattern on the second liquid crystal display 25 match, that is, when the two are the same object, a bright spot is generated on the rear focal plane of the second lens 27, and the photoelectric conversion is performed. Detected by means 28.

In this way, an optical information processing apparatus that performs optical correlation processing in which an optical filter based on a computer generated hologram displayed on the second liquid crystal display 25 acts as a matched filter is realized.

Furthermore, according to the present invention, the size of the Fourier transform image of the pattern of the target object is determined by the photodetector 31 and the focal length varying means 32.
, The size of the second liquid crystal display 25 is controlled to be substantially the same as that of the second liquid crystal display 25.
A Fourier transform computer hologram of a standard pattern having a size approximately equal to 25 will be displayed. As a result, since the entire surface of the spatial light modulator is always used, the number of picture elements that can be used increases even when a liquid crystal display with low resolution is used, as compared with the case where only a part of the spatial light modulator is used.

Therefore, a finer computer hologram can be used as a matched filter, and the identification accuracy can be improved. Further, in this embodiment, since the third lens 33 which is a convex lens is used, the size of the Fourier transform image of the input pattern detected by the photodetector position 31 is formed by the first lens 24 alone. It can be smaller than the Fourier transform image, and the photodetector 31 can be downsized.

In this embodiment, an electric writing type liquid crystal display is used as the first and second spatial light modulating elements. However, the present invention is not limited to this. An element may be used. If the resolution of these other spatial light modulators is low,
The same effects as in the first embodiment of the present invention can be obtained.

Further, when there is a limit to the size of an industrially available crystal such as an optical crystal, the size of the Fourier transform image of the pattern of the target object is always determined by the photodetector 31 and the focal length varying means 32. By controlling the size of the second liquid crystal display 25 to be substantially equal to that of the second liquid crystal display 25, the control of the size of the optical crystal can be relaxed, and the identification accuracy can be improved even if a small optical crystal is used.

Effect of the Invention As described above, in the present invention, an image is taken by a TV camera and displayed on the first spatial light modulation element to be used as an input pattern, and a computer generated hologram such as a matched filter is used as a second hologram.
A light detection system configured by arranging a plurality of ring-shaped detectors concentrically, displaying the size of the Fourier transform image of the input pattern on the reflected light path of the semi-transmissive mirror, displaying on the spatial light modulation element of The size of the computer hologram used in the optical information processing apparatus is changed by changing the focal length of the lens that performs the Fourier transform of the input pattern optically through the focal length variable means based on the output signal. Is always controlled to be substantially equal to the size of the spatial light modulator.
Thus, it is possible to provide an optical information processing apparatus in which the restriction on the resolution or the size of the spatial light modulator is relaxed and the identification accuracy is improved.

[Brief description of the drawings]

FIG. 1 is a plan view of an optical information processing apparatus according to a first embodiment of the present invention, FIG. 2 is a plan view of a photodetector 31 for detecting the size of a Fourier transform image, and FIG. FIG. 2 is a configuration diagram of a conventional optical information processing device used as a processing device. 20 ... TV camera, 21 ... First liquid crystal display, 22 ...
... Semiconductor laser, 23 ... Collimator lens, 24 ... First
Lens, 25 ... second liquid crystal display, 26 ... read-only memory (ROM), 27 ... second lens, 28 ...
... photoelectric conversion means, 30 ... semi-transmissive mirror, 31 ... photodetector for detecting the size of the Fourier transform image, 32 ... focal length variable means, 33 ... third lens.

Continuation of the front page (58) Fields investigated (Int. Cl. ⁶ , DB name) G06T 7/00 G02B 27/46 G03H 1/16 G06E 3/00 G06G 7/19 JICST file (JOIS)

Claims (3)

(57) [Claims] 1. A first spatial light modulator for displaying an image picked up by a TV camera, a light source for irradiating the first spatial light modulator, and the first spatial light modulator. A first lens whose surface is a front focal plane,
And a semi-transmissive mirror disposed between the rear focal plane of the first lens and a plurality of ring-shaped mirrors disposed on the focal plane on the rear side of the first lens in the reflection optical path of the semi-transmissive mirror. A photodetector configured by arranging a detection unit concentrically, a second spatial light modulation element disposed on a focal plane behind the first lens in a transmission optical path of the semi-transmissive mirror, and A second lens having a rear focal plane as a front focal plane on the rear side of the first lens, and a photoelectric conversion device disposed on the rear focal plane of the second lens;
A focal length varying means for controlling a focal length of the first range by an output signal of the photodetector, wherein a transmittance of each of the picture elements of the first and second spatial light modulators is spatially determined. An optical information processing apparatus, which displays a computer generated hologram by modulating. 2. An optical information processing apparatus according to claim 1, wherein said first and second spatial light modulators are constituted by liquid crystal displays. 3. A plurality of ring-shaped detectors arranged on a focal plane behind a first lens in a reflection optical path of a semi-transmissive mirror are arranged in front of a photodetector constituted by concentric circles. 3. The optical information processing apparatus according to claim 1, wherein three lenses are arranged.