JPH0329917A - Optical coordinate transforming device - Google Patents

Abstract

PURPOSE:To always obtain a proper coordinate transformed image by detecting the light intensity and its variance of the coordinate transformed image and changing the light intensity of the coordinate transformed image or the light reception sensitivity of a photodetector in accordance with detection results. CONSTITUTION:The coherent light emitted from a laser 1 is expanded by a beam expander 2 and passes a spatial optical modulator 3 where an input image is written and a coordinate transforming filter 4 and is subjected to Fourier transformation by a Fourier transforming lens 5 and passes a beam splitter 6 to obtain the coordinate transformed image of the input image on the photode tector (A) 7. The light branched by the beam splitter 6 is received by a photode tector (B) 8, and the output of the laser 1 is controlled by a laser control part 9 based on the signal outputted from this photodetector. Thus the light reception sensitivity of the photodetector or the light intensity of the coordinate transformed image is adjusted to always obtain the proper coordinate transformed image though the light intensity of the desired coordinate transformed image is changed by the change of the size, the shape, or the like of an object.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to an optical coordinate conversion device used for optical measurement, optical information processing, etc.

[Summary of Hatsushi]

The present invention solves the problem that an appropriate coordinate transformation image cannot be obtained when the size, shape, etc. of a human image that is a target of coordinate transformation changes in an optical coordinate transformation device. By detecting the angle and its changes and changing the light intensity of the coordinate transformation image accordingly, or changing the light receiving sensitivity of the light receiving element, an appropriate coordinate transformation image can always be obtained. It is something.

[Conventional technology]

For example, when measuring and recognizing objects with different shapes, sizes, orientations, positions, etc., such as characters or parts, firstly, the object is converted into a two-dimensional image (input image), and secondly, the input A common procedure is to transform an image into a desired coordinate system, and then thirdly perform measurement and recognition on the coordinate transformed image.

Here, the seeds of Iel 4 coordinate transformation include polar coordinate transformation when performing recognition and recognition for objects with different orientations, 31 measurements during quadruple rotation, etc., and recognition and recognition for objects with different orientations and sizes. 7 when measuring rotation angles and magnifications, etc. ,,r～
There are various types depending on the purpose, such as θ conversion.

A general method for performing the above coordinate transformation optically is shown in FIG. This is achieved by arranging the input image 22 and the coordinate conversion filter 23 superimposed on the front focal plane of the Fourier transform lens 24, and by irradiating the coherent light 21 from behind the human image 22, the input image 22 and the coordinate conversion filter 23 are placed on the front focal plane of the Fourier transform lens 24. A coordinate transformed image is obtained on the arranged light receiving element 25. Further, the coordinate conversion filter 23 is created using a computer-generated hologram.

[Problem to be solved by the invention]

However, conventional methods have had the problem that if the size or shape of the object to be recognized changes, an appropriate coordinate transformation image cannot be obtained. For example, if the size of the object becomes smaller, the two-dimensional input image written on the spatial light modulator becomes smaller. = 1 for that spatial light modulator
When the Heeren 1 light is irradiated, the amount of gold light transmitted through the spatial light modulator decreases, so the light intensity of the coordinate transformed image decreases. Therefore, the light intensity of the coordinate-transformed image is too small relative to the light-receiving sensitivity of the light-receiving element, and the coordinate-transformed image cannot be received. On the other hand, if the object is large, the light intensity of the coordinate transformed image will be too high and the coordinate transformed image will not be able to be received.

[Means to solve the problem]

In order to solve the above problems, in the present invention, at least one coherent light source and a spatial light modulator holding a two-dimensional input image that is an illusion of coordinate transformation are placed over the spatial light modulator. means for obtaining a desired coordinate transformation image from a coordinate transformation filter, a lens, and a light receiving element; a means for measuring the light intensity of the coordinate transformation image or a change in the light intensity; and a means for measuring the light intensity or a change in the light intensity. The light receiving device includes means for changing the light intensity or means for changing the light-receiving sensitivity of the light-receiving element.

[Effect]

With the above structure, even if the light intensity 3 of the desired coordinate transformation image changes due to changes in the size or shape of the object, the light receiving sensitivity of the light receiving element can be adjusted.
By adjusting the light intensity of the coordinate transformed image, an appropriate coordinate transformed image can always be obtained.

〔Example〕

Embodiments according to the present invention will be described below based on the drawings.

(First Embodiment) FIG. 1 is a diagram showing the structure of an embodiment of an optical coordinate conversion device according to the present invention. After the coherent light emitted from the laser 1 is expanded by a beam L and an expander 2, it is sent to a spatial light modulator 3 on which an input image is written.
, passes through the coordinate transformation filter 4, and passes through the Fourier transformation lens 5.
The beam is Fourier transformed and transmitted through the beam splitter 6.
A coordinate transformed image of the input pattern is obtained on the light receiving element (4) 7 (for example, a CCD camera). However, the Fourier transform lens 5
A spatial light modulator 3 and a coordinate conversion filter 4 are placed in an overlapping manner on the front focal plane, and a light receiving element (Al7) is placed on the back focal plane.

The light branched by the beam splinter 6 is sent to a light receiving element (1'1
Based on the signal received by the light receiving element 8 and output from the light receiving element 8, the laser control section 9 controls the output of the laser 1.

Next, the operation will be explained. For example, spatial light modulator 3''
Consider the case where the input image written in the second section becomes smaller. If the input image is written on the spatial light modulator 3 in a blur state, when the input image becomes smaller, the amount of light passing through the spatial light modulator 3 decreases accordingly. For this reason, the light intensity of the coordinate-converted image formed on the light-receiving element 7 decreases, and it goes outside the light-receiving range.
7, only a part of the coordinate transformation image can be obtained. In this case, since the amount of light incident on the light receiving element 08 has also decreased, it can be seen from the signal output from the light receiving element 08 that the light intensity of the coordinate transformed image has decreased. Therefore, if the laser control section 9 controls the output of the laser 1 to increase based on the signal output from the light receiving element ((3) 8), the light intensity of the coordinate transformed image formed on the light receiving element (4) 7 becomes stronger.

With the above feed hask, an appropriate coordinate transformation image will be obtained for the light receiving element (Al7).On the other hand, if the input image becomes large, it goes without saying that all you need to do is perform the feed hask in the opposite direction to the above. stomach.

(Second Embodiment) FIG. 3 is a diagram showing another embodiment of the optical coordinate conversion device according to the present invention. The means for converting the coordinates of the human-powered image and receiving the light are the same as in the first embodiment, and will therefore be omitted. Third
In the figure, a variable ND filter I2 is arranged at an arbitrary position on the optical path from the laser beam 1 to the light receiving element (4) 7, and a stethoping motor 11 rotates the variable ND filter 12; A motor control section 10 for controlling the stethoping motor 11 is provided. And the light receiving element +1318
Based on the signal output from the motor controller 10, the motor controller 10 lowers the stethoscope 11.

-1- According to the memorandum, for example, when the human power image becomes smaller, it can be seen that the light intensity of the coordinate transformed image decreases from the signal output from the light receiving element (]) 8, as in the first embodiment. . Therefore, based on the signal output from the light receiving element e8, the motor controller 10 controls the steno pin 11, rotates the variable ND filter 12, and transmits the light through the variable ND filter 12. When the amount of light is increased, the light intensity of the coordinate transformed image becomes stronger. Due to the feed function described above, an appropriate coordinate transformed image is obtained in the light receiving element 7.

Here, the variable filter 12 is used to adjust the amount of light, but it goes without saying that any filter that can adjust the amount of transmitted light by an external electrical signal, such as a liquid crystal TV, may be used.

(Third Embodiment) FIG. 4 is a structural diagram showing another embodiment of the optical coordinate conversion device according to the present invention. The means for converting the coordinates of a human-powered image and receiving light are the same as in the previous embodiment, and will therefore be omitted. In FIG. 4, the light receiving sensitivity of the light receiving element (Al7) is adjusted based on the signal output from the light receiving element +138.

For example, when the human image becomes smaller, the signal output from the light receiving element (1'318)
It can be seen that the light intensity of the coordinate transformed image has decreased. Therefore,
Based on the signal output from the light receiving element 03B, the light receiving sensitivity of the light receiving element (self) 7 is adjusted so that it can receive light even at a weak light intensity. Due to the above-mentioned function, an appropriate coordinate transformation image can be obtained on the light receiving element (A) 7.

Here, in the above three embodiments, a CCD camera, for example, can be considered as the light receiving element (A) 7 for the coordinate transformed image, but it goes without saying that other materials such as a BS○ crystal or a film may also be used. In this case, in FIG. 4, the light-receiving sensitivity is adjusted according to changes in the voltage applied to the T3 SO crystal, changes in film sensitivity, and changes in exposure time.

In addition, in the above three embodiments, the beam splinter 6
is placed on the optical path between the Fourier transform lens 5 and the light receiving element 7, but it goes without saying that it may be placed at any position on the optical path after the spatial light modulator 3.

In addition, in the three embodiments described above, the beam splinter 6 and the light receiving element ((3) 8 are used to split the light and measure the light intensity and its changes in the coordinate transformed image. Since the CCD camera, etc. 8 cannot be used as the light receiving element (4) 7, the laser 1 is used based on the output from the CCD camera.
The output of the ND filter 12, the rotation angle of the ND filter 12, and the light receiving sensitivity of the CCD camera which is the light receiving element 7 can be changed.
Needless to say, the beam splinter 6 and the light receiving element +1318 become unnecessary.

〔Effect of the invention〕

As explained above, even if the size, shape, etc. of the input image that is the target of coordinate transformation changes, an appropriate coordinate transformation image is always obtained, so when used for measurement, the squareness will be in the opposite direction. , and when used for recognition, its reliability is improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of an optical coordinate conversion device according to the present invention, FIG. 2 is a diagram showing an example of a conventional optical coordinate conversion method, and FIG. 3 is a block diagram showing an optical coordinate conversion device according to the present invention. Fig. 4 is a structural diagram showing another embodiment of the optical coordinate conversion device according to the present invention. 1...Laser 2 ・ ・ 3 ・ ・ 4 ・ ・ 5 ・ ・ 6 ・ ・ 7 ・ ・ 8 ・ ・ 9 ・ ・ 10 ・ 1l ・ 12 ・ ・ 21 ・ 22 ・ 23 ・ ・ 24 ・25・・fL・・Heam expander・Spatial light modulator・Coordinate conversion filter・Fourier transform lens・Beam splinter・Photodetector (4)・Photodetector (D・Laser control unit・Motor control unit・Motor・Variable type ND filter, coherent light, human power image, coordinate conversion filter, Fourier transform lens, light receiving element, Fourier transform lens!!

Claims (1)

[Claims] In a device that performs coordinate transformation using a two-dimensional image obtained from an imaging device such as a CCD camera and coherent light,
A desired light source comprising at least one coherent light source, a spatial light modulator holding a two-dimensional input image to be subjected to coordinate transformation, a coordinate transformation filter placed over the spatial light modulator, a lens, and a light receiving element. means for obtaining a coordinate transformation image;
means for measuring the light intensity of the coordinate transformed image or a change in the light intensity; and depending on the light intensity or the change in the light intensity,
An optical coordinate conversion device characterized by comprising means for changing the light intensity or means for changing the light-receiving sensitivity of the light-receiving element.