JP2751570B2 - Distance measuring device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical three-dimensional distance measuring device for non-contact measurement of a three-dimensional position of an object using light, and particularly to a distance measuring device using optical information processing technology. It concerns the device.

2. Description of the Related Art A configuration of a conventional three-dimensional distance measuring apparatus called a spatial coding method will be described with reference to FIG.

FIGS. 11A and 11E are a plan view and a front view, respectively, showing the principle of a conventional three-dimensional distance measuring apparatus. 20 is a light source, 21 is a mask pattern generation device, 22 is a columnar target object, 23 is a prismatic target object, and 24 is A to FIG. 11 (b) to (d) generated by the mask pattern generation device. This is a TV camera for imaging reflected light after the target object is irradiated with the mask pattern indicated by C, and is arranged at a distance d from the light source 20. Reference numeral 25 denotes an image processing unit for the image captured by the TV camera 24, which comprises a binarization processing unit 25a, a binarized image memory unit 25b, a coding processing unit 25c, and a distance calculation unit 25.

Next, the operation of the conventional three-dimensional distance measuring apparatus will be described with reference to FIG. First, the mask pattern generator 21
Then, the pattern A of FIG. 11 is generated, and then the pattern B,
Further, a mask pattern is sequentially generated with the pattern C, and the target objects 22 and 23 are irradiated. The reflected light from the target objects 22, 23 is photographed by the TV camera 24 and converted into a binarized image by the binarization processing unit 25a, and then the binarized image memory unit 25b
Are sequentially stored. This stored binarized image is represented by 2
Read from the coded image memory unit 25b and code processing unit 25e
Performs image processing based on the digitized electric signal. As a result, as shown in FIG. 11, for example, the light and dark pattern of the point P in FIG. 11 indicates a bright portion as 1 and a dark portion as 0, as shown in FIG. Is coded as 0, the mask pattern C is coded as 1, and the point Q is coded as (0, 1, 1). In this way, a code is assigned to each fan-shaped area determined by the projection angle Φ of the light source 20, and each can be regarded as one slit light beam. Therefore, the scene is photographed with a TV camera for each mask pattern, the light-dark pattern is subjected to a binarization process by the binarization processing unit 25a, and then sequentially stored in the binarized image memory unit 25b, and is stored for each mask pattern. Configure bit planes. The horizontal position of the multiplexed bit plane image thus obtained corresponds to the observation direction θ, while the projection angle Φ can be determined from the bit code such as (0, 1, 1). That is, the three-dimensional coordinates of the point of interest are calculated from the observation direction θ and the projection angle Φ by the distance calculation unit 25c using the following three equations based on the principle of triangulation.

X = Ztanθ (1) Y = Ztanξ (2) Z = d / (tanθ−tan (Φ + Φ0)) (3) Problems to be Solved by the Invention A conventional three-dimensional distance measuring apparatus configured as described above. The problems that have are described below.

In this conventional three-dimensional distance measuring apparatus, in order to obtain the three-dimensional coordinates (X, Y, Z) of the target object using the equations (1) to (3), it is necessary to obtain the projection angle Φ. . For this purpose, several types of different patterns are projected onto a target object, and imaging patterns corresponding to the respective projected patterns are converted into coded information by using an image processing technique based on digital electric signals. As a result, a plurality of patterns must be projected, which complicates the mask pattern generator.
Further, a memory unit for storing a plurality of imaging patterns is required.

Furthermore, since it is necessary to convert to coded information by image processing technology based on digital electric signals, when the number of picture elements of the mask pattern increases, there is a problem that processing time is required. Is actually a one-dimensional one with a light-dark pattern in only one direction,
There was a problem that it was limited.

The present invention projects a two-dimensional pattern having a one-dimensional or two-dimensional light-dark pattern on a target object, captures a reflection pattern of the target object with a TV camera, and uses the reflected image and the target object as three-dimensional patterns.
By performing pattern matching with a standard reflection pattern determined by a dimensional shape or position using optical information processing technology, the mask pattern generator becomes complicated.
A conventional three-dimensional technique in which a memory unit for storing a plurality of imaging patterns is required, or the mask pattern is substantially limited to one dimension due to an increase in calculation time due to an increase in the number of picture elements of the mask pattern An object of the present invention is to improve the shortcomings of a distance measuring device.

Means for Solving the Problems In order to solve the above problems, a distance measuring apparatus according to the present invention includes a pattern generation device that generates a predetermined projection pattern, a projection light source that irradiates the mask pattern to a target object, Photograph a reflection image of the mask pattern from an object
A TV camera, a first spatial light modulator that displays a captured image of the TV camera, a laser light source that irradiates the first spatial light modulator with parallel coherent light, and the first spatial light modulator. A first lens disposed on the front focal plane, a second spatial light modulator disposed on the rear focal plane of the first lens, and a second spatial light modulator disposed on the front focal plane. A second lens, and a photodetector disposed on the rear focal plane of the second lens, and displaying a computer generated hologram image of a predetermined standard reflection pattern on the second spatial light modulator. And

Alternatively, a pattern generating device that generates a predetermined projection pattern, a projection light source that irradiates the mask pattern onto a target object, a TV camera that captures a reflection image of the mask pattern from the target object, and an image captured by the TV camera A spatial light modulator for displaying an image, a laser light source for irradiating the spatial light modulator with parallel coherent light, a lens having the spatial light modulator on its front focal plane, and a rear focal plane for this lens. And a photodetector composed of a plurality of light receiving sections arranged.

Alternatively, a pattern generating device that generates a predetermined projection pattern, a projection light source that irradiates the mask pattern onto a target object, a TV camera that captures a reflection image of the mask pattern from the target object, and an image captured by the TV camera A first spatial light modulating element for displaying an image, a laser light source for irradiating the first spatial light modulating element with parallel coherent light, and a first spatial light modulating element disposed on its front focal plane.
Lens, a beam splitter disposed behind the first lens, and a second spatial light modulator disposed on a rear focal plane of the first lens located on the transmission side or the reflection side of the beam splitter. A first photodetector comprising a plurality of light receiving sections disposed on a rear focal plane of the first lens located on the other side of the beam splitter;
And a second photodetector disposed on a rear focal plane of the second lens, wherein the second spatial light modulating element is disposed on a front focal plane of the second spatial light modulator. A computer generated hologram image of a predetermined standard reflection pattern is displayed on the modulation element.

Operation The operation of the above means is as follows.

That is, the one-dimensional or two-dimensional mask pattern generated by the pattern generator is projected onto the target object,
A reflected image from the target object captured by the camera is displayed on the first spatial light modulator, and a computer-generated hologram image of a standard reflection pattern determined by the three-dimensional coordinates or position of the target object is displayed on the second spatial light modulator. Then, the pattern matching between the computer generated hologram image and the reflected image from the target object is performed by an optical information processing technique using a laser light source and first and second lenses, or the first space. The configuration is simple by optically Fourier transforming the reflected image displayed on the light modulation element and detecting the pattern of the converted image with a photodetector composed of a plurality of detection units, and
It is possible to provide a three-dimensional distance measuring device that can perform high-accuracy and high-speed processing.

Embodiment Next, the configuration of the first embodiment of the three-dimensional distance measuring apparatus of the present invention will be described with reference to FIG.

FIG. 1A is a configuration diagram of a first embodiment of a three-dimensional distance measuring apparatus according to the present invention. 1 is a white light source 1a that generates parallel light,
A pattern projecting device comprising a film 1b on which a mask pattern is recorded, 2 a recognition target object, 3 a TV camera for photographing a reflected image from the target object 2, 4 a first space for displaying a photographed image of the TV camera 3 This is a light modulation element, and a liquid crystal display is used in this embodiment. 5 is a semiconductor laser 5a
And a collimator lens 5b. The laser light source irradiates the first spatial light modulator 4 with parallel light. The laser light source 6 is determined by the mask pattern projected by the pattern projection device 1 and the three-dimensional shape or position of the target object. A memory for storing a computer-generated hologram image calculated in advance for the standard reflection pattern, and a second spatial light modulator 7 for displaying the computer-generated hologram image read from the memory 6 is used in this embodiment. Uses a liquid crystal display.

Reference numeral 8 denotes a first lens, on which a first spatial light modulator 4 is disposed on a front focal plane, and a second spatial light modulator 7 is disposed on a rear focal plane. Reference numeral 9 denotes a second lens, on the front focal plane of which a second spatial light modulator 7 is arranged. Reference numeral 10 denotes a photodetector, which is disposed on the rear focal plane of the second lens 9.

Next, the operation of the first embodiment of the three-dimensional distance measuring apparatus of the present invention thus configured will be described with reference to FIGS. The numbers in the figure that are the same as in FIG. 1 indicate the same.

First, the mask pattern shown in FIG. 1B is projected onto the target object 2 by the pattern generator 1. At this time, if there is no step in the target object 2, as shown in FIG. 2, a reflection pattern A1 similar to the projection pattern is generated. However, if the target object 2 as shown in FIG.
, There is a step, the reflection pattern is deformed by this step, and is reflected as a reflection pattern B as a pattern as shown in FIG. These reflection patterns are photographed by the TV camera 3 and displayed on the first spatial light modulator 4.

This display image is illuminated from the back by the laser light source 5 with coherent parallel light. At this time, the first lens 8
Since the first spatial light modulating element 4 is arranged on the front focal plane, the rear focal plane of the first lens 8, that is,
An optical Fourier transform image of a reflection image from the target object 2 is formed on the surface of the second spatial light modulator 7.

On the other hand, at this time, the second spatial light modulating element 7 calculates in advance the various standard reflection patterns shown in (a) to (c) of FIG. Since the Fourier transform computer generated hologram image is displayed, optical integration of the optical Fourier transform image of the reflected image from the target object 2 and the Fourier transform computer hologram image of the standard reflection pattern is performed.

In addition, since the front focal plane of the second lens 9 and the plane on which the second spatial light modulator 7 is arranged coincide, the rear focal plane of the second lens 9, that is, on the photodetector 10 plane Next, the Fourier transform image of the optical integration result, that is, the result of pattern matching between the reflected image from the target object and the standard pattern appears as the magnitude of the spot luminance. By detecting this with the photodetector 10, the reflection image from the target object 2 can be specified as one from a plurality of standard reflection patterns. Therefore, the step, that is, the height of the target object can be detected from the pitch of the specified, ie, pattern-matched standard reflection pattern. FIG. 4 shows a one-dimensional pattern having a periodicity of light and dark in only one direction as a mask pattern. However, even if a two-dimensional pattern having a periodicity of light and dark in two directions such as a checkered pattern is used, a one-dimensional pattern can be obtained. The height of the target object can be detected by the same operation as in the case of the dimensional pattern.

As described above, according to the first embodiment of the three-dimensional distance measuring apparatus of the present invention, several different patterns are applied to the target object in order to obtain the projection angle Φ as in the conventional three-dimensional distance measuring apparatus. Unlike the method of projecting and processing the imaging pattern corresponding to each projection pattern using image processing technology based on digital electric signals to obtain height information of the target object, one type of mask pattern is projected. By using the optical information processing technology of pattern matching between the reflection pattern from the target object and the standard reflection pattern, which can be obtained only by performing the above, it is possible to prevent the mask pattern generator from becoming complicated, Since high-speed processing is possible regardless of an increase in the prime number, a high-resolution three-dimensional distance measuring apparatus using not only one-dimensional but also two-dimensional fine mask patterns can be realized.

Next, the configuration of a second embodiment of a three-dimensional distance measuring apparatus according to the present invention will be described with reference to FIGS.

FIG. 5A is a configuration diagram of a second embodiment of the three-dimensional distance measuring apparatus according to the present invention. 1 that are the same as those in FIG. 1 indicate the same components.

Numeral 30 denotes a spatial light modulator for displaying a reflection pattern from the target object 2 imaged by the TV camera 3, and this embodiment uses a ferroelectric liquid crystal display. Reference numeral 31 denotes a lens, and the spatial light modulator 30 is disposed on the front focal plane of the lens 31. Reference numeral 32 denotes a photodetector composed of a plurality of detectors divided in a radial direction and a circumferential direction as shown in FIG. 6, and is arranged on the rear focal plane of the lens 31.

The operation of the second embodiment of the present invention will be described with reference to FIG.
This will be described below with reference to FIGS. 3, 5 to 7.

First, the mask pattern shown in FIG. 5B is projected onto the target object 2 by the pattern projection device 1. At this time, if there is no step in the target object 2, as shown in FIG. 2, a reflection pattern A1 similar to the projection pattern is generated. However, if the target object 2 as shown in FIG.
, There is a step, the reflection pattern is deformed by this step, and is reflected as a reflection pattern B as a pattern as shown in FIG. These reflection patterns are photographed by the TV camera 3 and displayed on the spatial light modulator 30.

This display image is illuminated from the back by the laser light source 5 with coherent parallel light. At this time, since the spatial light modulator 30 is disposed on the front focal plane of the lens 31,
An optical Fourier transform image of the reflected image from the target object 2 is formed on the rear focal plane of the lens 31, that is, on the photodetector 32. This optical Fourier transform image is shown in FIGS.
As shown in (c), it has a unique pattern determined by the reflection pattern from the target object 2. Therefore, the reflection pattern from the target object 2 can be specified from the detection signals of the plurality of divided detection units on the photodetector 32 by determining the radial position and direction of the optical Fourier transform image. Can be detected.

The second embodiment of the three-dimensional distance measuring apparatus of the present invention configured as described above
According to this embodiment, the same effect as that of the first embodiment can be obtained. Furthermore, according to the second embodiment of the three-dimensional distance measuring apparatus of the present invention, the configuration of the optical information processing unit is simplified as compared with the first embodiment, and the reflected image pattern from the target object 2 Since it is not necessary to compare with a number of standard reflection image patterns in order to specify the pattern, it is possible to obtain an effect that the speed can be increased.

Next, a third embodiment of the present invention will be described. Third
This embodiment can improve the complexity or accuracy of wiring processing for processing signals from a large number of detection units by subdividing the detection units of the photodetector 32 in the second embodiment.

First, the configuration will be described with reference to FIG. 8 and FIG. The numbers in the figures that are the same as those in FIGS. 1 and 5 indicate the same.

Reference numeral 50 denotes a beam splitter, which includes a first lens 8 and a second lens
Are arranged in the optical path between the spatial light modulators 7. 51
Denotes a first photodetector, which is constituted by a plurality of detecting portions divided in a radial direction or a circumferential direction as shown in FIGS. It is arranged on the rear focal plane located on the reflection side of the beam splitter 50. Reference numeral 7 denotes a second spatial light modulator, which is disposed on a rear focal plane of the first lens 8 located on the transmission side of the beam splitter 50. 52 is a second photodetector.

Next, the operation of the third embodiment of the three-dimensional distance measuring apparatus according to the present invention will be described with reference to FIGS. 2, 3, and 8 to 9.

First, the mask pattern shown in FIG. 8B is projected onto the target object 2 by the pattern generator 1. At this time, if there is no step in the target object 2, as shown in FIG. 2, a reflection pattern A1 similar to the projection pattern is generated. However, if the target object 2 as shown in FIG.
, There is a step, the reflection pattern is deformed by this step, and is reflected as a pattern as shown as a reflection pattern B.

These reflection patterns are photographed by the TV camera 3,
It is displayed on the first spatial light modulator 4. This display image is
The laser light source 5 irradiates from the back with coherent parallel light. At this time, since the first spatial light modulating element 4 is disposed on the front focal plane of the first lens 8, the first
The target object 2 is placed on the rear focal plane of the lens 4 located on the reflection surface side of the beam splitter 50, that is, on the first photodetector 51.
An optical Fourier transform image of the reflected image from is formed.

This optical Fourier transform image has a unique pattern determined by a reflection pattern from the target object 2. That is, the pitch of the optical Fourier transform image shown in FIG. 10 indicates the spatial frequency (period of the pattern) of the light and dark pattern of the reflected image, and the inclination θ of the optical Fourier transform image is the inclination of the light and dark pattern of the reflected image (pattern). Indicate directions having periodicity).

Therefore, if the first photodetector 51 shown in FIG. 9A is used, it is possible to detect the direction in which the light and dark pattern of the reflected image has periodicity. Further, if the first photodetector 51 shown in FIG. 9B is used, the spatial frequency of the light and dark pattern of the reflected image can be known.

Therefore, based on the detection signal of the first photodetector 51, a Fourier transform computer generated hologram image displayed on the second spatial light modulator 7, that is, a standard pattern for specifying a reflection image from the target object 2 The approximate value of the period or inclination of the light and dark pattern can be known.

Then, the approximate value is read from the memory 6 and the second
It is possible to narrow down the number of standard reflection image patterns to be displayed on the spatial light modulator 7. The narrowed-down standard reflection image patterns are sequentially displayed on the second spatial light modulation element 7, and the pattern matching with the reflection pattern from the target object 2 displayed on the first spatial light modulation element 4 is performed in the first manner. The operation is performed via the lens 8, the transmission side of the beam splitter 50, the second spatial light modulator 7, and the second lens 9.

By detecting the result of the optical pattern matching by the second photodetector 52, the height of the target object 2 can be measured.

As described above, according to the third embodiment of the three-dimensional distance measuring apparatus of the present invention, it is possible to perform high-precision optical pattern matching after narrowing down the candidates for the standard reflection pattern to be matched first. This makes it possible to realize a high-speed and high-accuracy three-dimensional distance measuring apparatus.

Effects of the Invention As described above, according to the present invention, the configuration is simple, and
It is possible to provide a three-dimensional distance measuring device that can perform high-accuracy and high-speed processing.

[Brief description of the drawings]

FIG. 1 is a block diagram of a first embodiment of a three-dimensional distance measuring apparatus of the present invention, and FIGS. 2 and 3 are operation explanatory diagrams of the first embodiment of the three-dimensional distance measuring apparatus of the present invention. FIG. 4 is an explanatory view of a Fourier transform computer hologram image of a standard reflection pattern used in the first embodiment of the three-dimensional distance measuring apparatus of the present invention, and FIG. 5 is a second embodiment of the three-dimensional distance measuring apparatus of the present invention. FIG. 6 is a block diagram of the photodetector in the second embodiment of the three-dimensional distance measuring apparatus of the present invention, and FIG. 7 is a diagram showing various parts in the second embodiment of the three-dimensional distance measuring apparatus of the present invention. 8 is an optical Fourier transform image of a reflection pattern from a target object, FIG. 8 is a block diagram of a third embodiment of a three-dimensional distance measuring device of the present invention, and FIGS. 9a and 9b are three-dimensional distance measuring devices of the present invention. FIG. 10 is a configuration diagram of a first photodetector of a third embodiment of the apparatus, FIG. 10 is an explanatory diagram of the operation of the three-dimensional distance measuring apparatus of the present invention, and FIG. It is a diagram. DESCRIPTION OF SYMBOLS 1 ... Pattern generator, 2 ... Target object, 3 ... TV camera, 4 ... First spatial light modulation element, 5 ... Laser light source, 6 ... Memory, 7 ... Second spatial light modulation Element, 8 ...
... first lens, 9 ... second lens, 10 ... photodetector, 50 ... beam splitter, 51 ... first photodetector,
52... Second photodetector.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Atsushi Fukui 1006 Kazuma Kadoma, Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (56) References JP-A-61-260107 (JP, A) JP-A-2-2 45704 (JP, A) JP-A-3-156581 (JP, A) JP-A-62-186225 (JP, A) JP-A-63-127223 (JP, A) JP-A-1-300382 (JP, A) JP-A-58-7506 (JP, A) JP-B-61-58761 (JP, B2) Patent 2615964 (JP, B2)

Claims (3)

(57) [Claims] 1. A pattern generating apparatus for generating a predetermined projection pattern, a projection light source for irradiating a target object with the mask pattern, a TV camera for photographing a reflection image of the mask pattern from the target object, A first spatial light modulator for displaying a captured image of a camera, a laser light source for irradiating the first spatial light modulator with parallel coherent light, and the first spatial light modulator on a front focal plane thereof First
A second spatial light modulating element disposed on the rear focal plane of the first lens, a second lens having the second spatial light modulating element disposed on the front focal plane thereof, A photodetector placed on the rear focal plane of the second lens and displaying a computer generated hologram image of a predetermined standard reflection pattern on the second spatial light modulator. 2. A pattern generator for generating a predetermined projection pattern, a projection light source for irradiating the mask pattern to a target object, a TV camera for photographing a reflection image of the mask pattern from the target object, A spatial light modulator for displaying a captured image of a camera, a laser light source for irradiating the spatial light modulator with parallel coherent light, a lens having the spatial light modulator on its front focal plane, and a rear side of the lens A distance measuring device comprising: a photodetector including a plurality of light receiving units disposed on a focal plane. 3. A pattern generator for generating a predetermined projection pattern, a projection light source for irradiating the mask pattern to a target object, a TV camera for photographing a reflection image of the mask pattern from the target object, A first spatial light modulator for displaying a captured image of a camera, a laser light source for irradiating the first spatial light modulator with parallel coherent light, and the first spatial light modulator on a front focal plane thereof First
Lens, a beam splitter disposed behind the first lens, and a second spatial light modulator disposed on a rear focal plane of the first lens located on the transmission side or the reflection side of the beam splitter. A first photodetector comprising a plurality of light receiving sections disposed on a rear focal plane of the first lens located on the other side of the beam splitter;
And a second photodetector disposed on a rear focal plane of the second lens, wherein the second spatial light modulating element is disposed on a front focal plane of the second spatial light modulator. A distance measuring apparatus characterized by displaying a computer generated hologram image of a predetermined standard reflection pattern on a modulation element.