JPH02108907A - Distance/shape measuring instrument - Google Patents

Abstract

PURPOSE:To find the distance to a body, etc., stably in a short time by measuring distances in flight time provided to respective light intensity sensors in a sensor array and measuring the distance shape of the body according to the differences. CONSTITUTION:Laser light from a laser 2 becomes nearly parallel light by passing through a lens 3. The laser light is split by a beam splitting mirror 4 in the directions of the body 5 and a photodetecting element. Light which is reflected and scattered by the body 5 forms its image on a photodiode array 9 through a lens 6. Light quantity outputs of the respective elements are led to a signal shaping circuit 10. The signal of a local oscillator 11 is also led to the circuit 10 and converted into a low-frequency signal wherein the intensity and phase of the light quantity signals are maintained. The output of a reference generating circuit 13 and the output of the circuit 10 are inputted to an intensity and phase measuring circuit 14 and the phase difference between the reference signal and light quantity signal and the intensity of a component of the same frequency with the reference signal in the light quantity signal are outputted as voltage signals. A signal processing circuit 16 calculates the distance from the phase difference and distance information is superimposed on the video signal of the body 5 which is photographed by a television camera 8 in the form of chrominance components and displayed on a monitor 17.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a distance ktt shape measuring device that measures the flight time of light to determine the distance to an object and/or the shape of the object.

[Prior art] A light wave distance meter is a method that measures the flight time of light using time measurement and phase measurement methods, and measures the distance to an object from the time it takes for the light to hit the object and return. It is widely used in , rangefinders for geographical distance measurement, 0TDR1 astronomical observation for optical fiber defect inspection, laser radar, etc. However, in the past, since the optical modulation frequency remained at a few MHz, the resolution was poor and the measurement method was not suitable for use in recognizing the position and shape of objects at short distances.

On the other hand, recent developments in semiconductor laser and high-frequency circuit technology have made it possible to measure distances with a resolution of 1 mm or less [Reference: Japanese Journal
of Applied Physics Vol 26
．． No, 10. (1987), 1690 pages ~,
K, 5eta, etc.].

In addition, a method of scanning light two-dimensionally to determine the distance shape is also being used [Reference: Obtronics (1985
), NO, page 12, 59~, Seiji Iguchi et al.

Such].

FIG. 3 is a schematic configuration diagram of a distance shape measuring device, which is one of the conventional examples. In this method, a motor 23 drives a mirror 24 to scan an object 25 with a laser beam, the reflected light is received by a phototube 27, and the distance to the object 25 and the shape of the object 25 are determined from the signal.

[Problems to be Solved by the Invention] However, according to the above conventional example, since the mirror 24 and the like are driven by mechanical means to scan the light, there are problems in speeding up and stabilizing the measurement. There was a problem in that it was difficult to clarify the correspondence between position and distance.

In view of the above-mentioned problems in the conventional example, the present invention eliminates the mechanical driving part for optical scanning, allows distances and shapes to be determined quickly and stably, and also allows for correspondence between measurement positions and distances. It is an object of the present invention to provide a distance shape measuring device that can also clarify relationships.

[Means and effects for solving the problem] In order to achieve the above object, the distance shape measuring device according to the present invention irradiates the measurement light of the light wave distance meter onto the measurement range on the object, and A sensor array consisting of a plurality of light intensity sensors is arranged on the image plane of an optical system that forms an image of the measurement range, and the above flight time is set for each light intensity sensor of the sensor array without scanning the light. The distance shape of the object is measured based on this difference.

In other words, light is modulated with one or more types of modulation frequencies and projected onto the measurement object at an angle or size that is equal to or larger than the measurement object, and its reflection is reflected. The light, scattered light, diffracted light, or interference light is imaged on the conjugate plane of the optical system, and the two
The amount of light is determined using more than one light amount measurement sensor, and the shape of the distance to the object is determined from the change in the amount of light over time.

[Example] Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 is a schematic configuration diagram of a distance shape measuring device according to an embodiment of the present invention. In the figure, 1 is a laser control device that modulates the intensity of the laser at high speed, 2 is a laser such as a semiconductor laser that is modulated by the control device 1, 3 is a lens that magnifies and collimates the laser light emitted by the laser 2, and 4 is a laser that modulates the intensity of the laser at high speed. a beam splitting mirror that splits the laser beam; 5 is an object to be measured having a rough surface; 6 is a lens that forms an image of the object 5;
7 is a beam splitting mirror, 8 is a television camera that photographs the formed image, and 9 is a photodiode array that measures the intensity of the formed laser beam. 10 is a photodiode array 9
After converting the frequency of the light amount signal output from each element,
These are signal shaping circuits that amplify the signal to a level suitable for phase measurement and limit the band. 11 is a local oscillation circuit for the heterodyne circuit, and 12 is a light receiving element that measures the laser beam that passes through the beam splitting mirror 4 in a straight line. 13 is a standard for creating a phase reference signal after converting the frequency of the light amount signal output of the light receiving element 12, amplifying it to an intensity suitable for phase measurement, or band-limiting, in the same way as the signal shaping circuit 10. This is the creation circuit. 14 indicates the phase difference between the outputs of the signal shaping circuit 10 and the reference generation circuit 13 and the signal shaping circuit 10
15 is a signal processing circuit 16 that digitally converts the measurement results of the measurement circuit 14;
16 is a signal processing device that analyzes and processes the measurement results, simultaneously analyzes and processes the video signal of the television camera 8, and displays the two signals on a display device 17; 17 displays the output of the processing device 1.6; This is a display device such as a CRT.

In the above configuration, laser light whose intensity is modulated at a higher speed than that of the laser 2 is emitted by the laser control device 1, and is expanded by the lens 3 to become substantially parallel light. The parallelism of the laser beam only needs to be such that a sufficient amount of light is returned to each element of the photodiode array 9.The beam splitting mirror 4 directs one side of the laser beam toward the object 5 and the other toward the light receiving element 12. Divided into directions. The light reflected and scattered by the object 5 is imaged onto a photodiode array 9 by a lens 6. The light output of each photodiode element is
Each signal is guided to a signal shaping circuit 10. On the other hand, the signal from the local oscillator 11 is also guided to the signal shaping circuit 10, where it is converted into a low frequency signal that preserves the intensity and phase of the light amount signal using the heterodyne method.

Further, the light transmitted through the beam splitting mirror 4 enters the light receiving element 12, and similarly, a low frequency reference signal is generated by the reference signal generation circuit 13 using a signal from the local oscillator 11.

The output of the reference generation circuit 13 and the output of the signal shaping circuit 10 are as follows.
The signal is input to the intensity/phase measurement circuit 14, and the phase difference between the reference signal and the light amount signal and the intensity of the component of the same frequency as the reference signal in the light amount signal are output as a voltage No. 12. The phase difference and intensity signals are analog/digital converted by the interface circuit 15 and taken into the signal processing circuit 16. The signal processing circuit 16 calculates the distance from the phase difference, and puts distance information in the form of a color signal on the video signal of the object 5 photographed by the television camera 8, so that it is displayed on the monitor 17 in the form of a color signal if it is close, and blue if it is far. Display above. Also, if the object has a complicated shape, for example, if there is a through hole, no light will be returned. therefore,
The distance cannot be measured at that point, but the measured value is due to noise. Therefore, when the amount of light is low to a certain extent, it is necessary to express on the screen that ``the amount of light is low, so it is likely to be returned.''

Therefore, the signal processing circuit 16 forcibly changes the color to a certain designated color when the intensity signal is less than a set value.

According to this embodiment, everything from the sensor to the processing circuit can be realized using only electronic parts and elements, so that it is possible to integrate it into a hybrid IC or a monolithic IC. Additionally, since all circuits are low voltage, there is no need for safety circuits or special high voltage circuits.

Furthermore, since the video signal can have distance information and intensity information (monochrome signal) at the same time, video equipment such as a VTR can be used. Furthermore, if the laser light is invisible light, distance information can be obtained without affecting the television camera.

[Other Embodiments] FIG. 2 is a schematic configuration diagram of a distance shape measuring device according to a second embodiment of the present invention. In this figure, the same numbers as in FIG. 1 represent the same parts.

In FIG. 2, the output of the local oscillator 11 is supplied to each photodiode of the imaging photodiode array 9 as a reverse bias voltage. Therefore, the photodiode itself performs heterodyne conversion, and the heterodyne circuit of the signal shaping circuit 10 becomes unnecessary.

According to this second embodiment, since the photodiode itself performs heterodyne conversion, the number of parts can be reduced and the device can be made smaller. Furthermore, it is easy to manufacture an element that integrates a photodiode array and a detection circuit into an integrated IC.

[Effects of the Invention] As explained above, the present invention has the following effects.

l) Since there is no drive unit and optical scanning is not required, the distance to the object and the shape of the object can be determined quickly and stably within the measurement time of the electrical measurement circuit. Furthermore, the correspondence between measurement positions and distances can also be clarified.

2) Since it takes time to measure each point, it has become possible to use circuit components with poor high frequency characteristics.

3) Longer life is possible because there is no driving part.

4) Since there is no driving part, integration is easy.

It is also possible to use IC.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a distance shape measuring device according to an embodiment of the present invention, FIG. 2 is a schematic configuration diagram of a distance shape measuring device according to a second embodiment of the present invention, and FIG. , is a schematic configuration diagram of a conventionally used distance shape measuring device. 1: Laser control device, 2: Laser, 3: Lens,
4: Beam splitting mirror, 5: Measurement object, 6: Lens,
7: Beam splitting mirror, 8: Television camera, 9
: Photodiode array, 10: Signal shaping circuit,
11: Local oscillator, 12: Light receiving element, 13: Reference creation circuit, 14: Phase 1 intensity measurement circuit, 15: Interface circuit, 16: Signal processing device, 17:
Display device, 18: Laser, 19: Oscillator, 2
0: Optical modulator, 21: Beam splitting mirror, 22: Photodiode, 23: Motor, 24: Scanning mirror, 25
: Measurement object, 26: Optical lens system, 27: Phototube, 28: Tuning filter, 29: Phase intensity measuring device,
30: Computer. Patent Applicant Canon Co., Ltd. Agent Patent Attorney Tetsuya Ito Agent Patent Attorney Tatsuo Ito

Claims (1)

[Claims] (1) The difference in flight time between the light that is emitted from a light source toward an object, is reflected, scattered, diffracted, or interfered with on the surface of the object, and enters the light intensity sensor, and a predetermined reference light from the light source is measured by time measurement or In a distance and shape measuring device that measures using a phase measurement technique to determine the distance to the object and/or the shape of the object, an optical system that forms an image of the object surface, and an image forming surface of the optical system are provided. A distance shape measuring device comprising: a sensor array consisting of a plurality of light intensity sensors arranged; and means for measuring the difference in flight time provided for each light intensity sensor of the sensor array. .