JPS63307379A - Infrared visual sensor - Google Patents

Abstract

PURPOSE:To take a measurement with high accuracy by projecting laser light on an object intermittently and obtaining pieces of information by reflected laser light and infrared radiant light from the object alternately. CONSTITUTION:The laser light from a laser oscillator 1 is split 2 into reference laser light 11 and measurement laser light 3. The laser light 3 is passed through an acoustooptic converter 4, a holed mirror 6, and a two-dimensional scanner 7 and projected on the object 8 and its reflected laser light 9 is passed through the scanner 7, mirror 6, and reflecting mirror 6a, mixed 12 with the laser light 11, and detected 14 through a lens 13. Further, the infrared radiant light 10 which is emitted by the object 8 according to the body temperature is also detected 14 through the scanner 7, etc. The output of the detector 14 is divided into two and one is amplified 19 and inputted to an image input device 20 as brightness information 203 by the emitted light 10. The other is passed through a wide-band preamplifier 15, a BPF 16, and a demodulator 17 to obtain brightness information 202 by the laser light 9 and the information is inputted to the device 20 as distance information through a phase detector 18. A pulse generator 23 controls the oscillation of the oscillator 1 and the pieces of information by the laser light 9 and radiant light 10 are obtained alternately.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to an infrared visual sensor that can simultaneously obtain visual information and distance information.

BACKGROUND ART Conventional infrared vision sensors of this type include, for example, Applied Fist Optics, Vol. 23, p. 2565, 1984 (Appl. Optics, Vol. 23. P2).
565, 1984) is known.

The conventional infrared visual sensor will be described below with reference to FIG.

As shown in FIG. 4, the continuous wave laser beam emitted from the laser oscillator 27 is separated into a reference laser beam 36 and a measurement laser beam 29 by a beam splitter 28. The measurement laser beam 29 is frequency-shifted by a frequency filter 30 and further intensity-modulated by a modulator 31 . The intensity-modulated laser beam 32 is transmitted by a two-dimensional scanner 33.
is scanned and irradiated onto the object 34. A reflected laser beam 35 reflected from an object 34 passes through a two-dimensional scanner 33, is mixed with the reference laser beam 36 and a beam splitter 37, and is focused by a lens 38 onto a detector 39, where light heterodyne detection is performed. . The signal from the detector 39 has the frequency of the frequency thick 30 and both sideband waves of the modulation frequency. This signal is amplified by a preamplifier 40, passed through a bandpass filter 41, and demodulated by a demodulator 42. One of the demodulated signals is sent to the phase detector 4
3, the demodulated signal is phase-compared with the modulated signal and output as distance information, and the other branched signal of the demodulated signal is output as luminance information from the reflected laser light intensity by the intensity modulation detector 44.

Problems to be Solved by the Invention However, in such a conventional infrared visual sensor, depending on the material of the object 34, the reflected laser beam 35 may be detected by the detector 39.
may not be detected and the object 34 may not be visible. That is, if the reflectance of the object 34 to the laser beam 32 is very small and the intensity of the reflected laser beam 35 becomes lower than the detection ability of the detector 39, it becomes undetectable. Furthermore, if the object 34 has a large reflectance with respect to the laser beam 32 and the surface of the object 34 is tilted, most of the energy of the irradiated laser beam 32 is reflected to the other side and the detector 39 Since it does not return to , it becomes undetectable. Therefore, it is difficult to obtain information from the visual sensor, and the visual sensor does not function as a visual sensor.

Therefore, the present invention solves the above-mentioned problems of the conventional example, and even if the emitted laser light is absorbed by the object or is reflected to the other object, it can be detected and visualized. The present invention aims to provide an infrared visual sensor that can do this.

Means for solving the problems and technical means of the present invention for solving the above problems are a laser oscillator and an acousto-optic modulation for frequency shifting and intensity modulation of the laser light emitted from the laser oscillator. a scanner that two-dimensionally scans an object with frequency-shifted and intensity-modulated laser light; an infrared detector that detects reflected laser light and infrared radiation from the object; means for obtaining distance and brightness information of an object from laser light and infrared radiation, respectively, and brightness information due to infrared radiation, and means for intermittently irradiating laser light from the laser oscillator and using reflected laser light from the object. The apparatus is equipped with a control means for alternately obtaining information and information by infrared radiation light.

For production The effects of the above technical means are as follows.

In other words, the object is intermittently irradiated with a laser beam, the distance information and brightness information of the object is obtained by the laser beam, and the brightness information is obtained by the infrared radiation from the object when the laser beam is not irradiated. I have to. In this way, in the case of objects for which reflected laser light cannot be obtained, infrared radiation increases, and this infrared radiation can be visualized as brightness information, so any object can be detected and visualized. can do.

EXAMPLES Hereinafter, examples of the present invention will be described with reference to the drawings.

First, a first embodiment of the present invention will be described.

FIG. 1 is a block diagram showing an infrared visual sensor in a first embodiment of the present invention.

In FIG. 1, 1 is a laser oscillator, 2 is a beam splitter, 4 is an acousto-optic modulator, 6 is a perforated mirror, 7 is a two-dimensional scanner, 8 is an object, 6a is a beam mirror, 12 is a beam splitter, 13 is a lens, 14 is a detector, 15 is a wideband preamplifier, 16 is a bandpass filter, 17 is a demodulator, 18 is a phase detector, 19 is a low frequency preamplifier, 20 is an image capture device, 21 is a scanner driver, 22 2 is a laser power source, 23 is a pulse generator, and 24 is an input selector.

Next, the operation of the above embodiment will be explained.

A laser beam emitted from a laser oscillator 1 is separated by a beam splitter 2 into a reference laser beam 11 and a measurement laser beam 3. The measurement laser beam 3 is sinusoidally intensity-modulated by an acousto-optic modulator 4 and becomes an irradiation laser beam 5 whose frequency is shifted by the carrier frequency of the modulated wave. The irradiated laser beam 5 passes through a hole in a perforated mirror 6, is scanned two-dimensionally by a two-dimensional scanner 7, and is irradiated onto an object 8. The reflected laser beam 9 reflected by the target object 8 is taken into the two-dimensional scanner 7, reflected by the perforated mirror 6 and the reflecting mirror 6a, mixed with the reference laser beam 11 by the beam splitter 12, and sent to the detector by the lens 13. The light is focused on 14.

Infrared radiation 10 corresponding to the object temperature is emitted from the object 8, and this infrared radiation 10 is also taken into the detector 14 via the two-dimensional scanner 7, etc., as described above.

That is, if the temperature of an object is above absolute zero, there is infrared radiation from all surfaces of the object. The amount of this infrared radiation 10 varies depending on the temperature and emissivity (infrared radiation efficiency) of the object, and how many high-temperature objects there are, and at the same temperature, the maximum is reached in the case of a completely black body that does not reflect any infrared rays. becomes.

In the case of a perfect reflector, the infrared radiation from the object itself is zero, but the object is recognized by reflecting infrared radiation from surrounding objects. Therefore, the infrared radiation 10 emitted from the object 8 is also detected by the detector 14.

When the laser oscillator 1 oscillates, the pulse generator 23 generates a pulse, and the laser power supply 22 is controlled to perform the laser oscillation intermittently, resulting in a rectangular waveform of the output PO as shown in FIG. 3(a). . Since the infrared radiation light 10 is constantly emitted, the intensity PT of the object 8 at a constant temperature T has a constant value as shown in FIG. 3(b), and the incident light on the detector 14 is , as shown in FIG. 3(C), the product PR of the irradiated laser beam shown in (a) and the reflectance of the object 8, and (b)
This is the sum of the infrared radiation shown in

The output of the detector 14 is divided into two parts, one amplified by a wideband preamplifier 15 and the other amplified by a low frequency preamplifier 19. The signal amplified by the broadband preamplifier 15 passes through a bandpass filter 16, and then is demodulated by a demodulator 17, and information from the reflected laser beam 9 is selected. The demodulated signal has brightness information 20 from the signal strength.
2 into the image capture device 20, and the phase detector 1
The phase obtained from 8 is input into the image number importing device 20 as distance information 201. The signal amplified by the low frequency preamplifier 19 is brightness information 203 based on the infrared radiation 10.
The image is captured into the image capture device 20 as a.

In the image capturing device 20, frame memories are prepared for each of distance information 201 based on the reflected laser beam 9, brightness information 202, and brightness information 203 based on the infrared radiation 10, and an address signal 204 from the scanner driver 21. Image capture is performed in response to the input switching signal 205 from the input selector 24.

In this embodiment, the pulse generator 23 generates the laser oscillator 1.
At the same time, the input selector 24 is controlled, and information from the reflected laser light 9 and information from the infrared radiation light 10 are obtained alternately.

Therefore, it becomes possible to take in infrared radiation information with an optical system using the heterogain detection method, and it becomes possible to visualize objects that could not be seen with the conventional infrared vision centimeter, which only uses information from reflected laser light 9.

Next, a second embodiment of the present invention will be described. FIG. 2 is a block diagram showing a second embodiment of the present invention.

In this embodiment, an optical chopper 25 is used to intermittently control the laser light emitted from the laser oscillator 1, and an optical chopper driver 26 controls the input selector 24. Since these are the same as those in the first embodiment, the same reference numerals are given and the explanation thereof will be omitted.

This embodiment is effective when the laser oscillator 1 does not have a pulse oscillation function.

According to each of the embodiments described above, the configuration is simple because the pulse generator 23 or the optical chopper 25, the optical chopper driver 26, and the input selector 24 can be added to the conventional infrared visual sensor.

Effects of the Invention As described above, according to the present invention, a laser beam is intermittently irradiated onto an object, and information from the laser beam reflected from the object and information from the infrared radiation from the object are alternately transmitted. Information from reflected laser light enables high-precision measurement using a measurement optical system using the heterodyne detection method, and information from infrared radiation prevents excessive input to the detector, making it possible to perform It becomes possible to visualize objects that cannot be seen with infrared vision sensors (such as completely black bodies and completely reflective objects).

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an infrared visual sensor according to a first embodiment of the present invention, FIG. 2 is a block diagram showing an infrared visual sensor according to a second embodiment of the present invention, and FIG. 3 is a block diagram showing an infrared visual sensor according to a second embodiment of the present invention. FIG. 4 is a configuration diagram showing a conventional infrared visual sensor. 1... Laser oscillator, 2... Beam splitter, 3
...Measurement laser beam, 4...Acousto-optic modulator, 5...
- Irradiation laser beam, 6... Hole mirror, 7... Two-dimensional scanner, 8... Target, 9... Reflected laser beam, 10
...Infrared radiation light, 11...Reference laser light, 12...
・Beam splitter, 13... Lens, 14... Detector, 15... Broadband preamplifier, 16... Band pass filter, 17... Demodulator, 18... Phase detector, 19...・Low frequency preamplifier, 20... Image capture device, 21... Scanner driver, 22... Laser power supply, 23... Pulse generator, 24... Input selector, 25... Optical detector Tsuba 126... Optical chopper driver. Figure 3 - Current time

Claims (1)

[Claims] a laser oscillator; an acousto-optic modulator for frequency shifting and intensity modulating the laser beam emitted from the laser oscillator; a scanner for two-dimensionally scanning an object with the frequency-shifted and intensity-modulated laser beam; An infrared detector for detecting reflected laser light and infrared radiation from an object, and means for obtaining distance and brightness information of the object from the reflected laser light and infrared radiation, respectively, and brightness information by infrared radiation. and a control means for intermittently irradiating laser light from the laser oscillator to obtain information from the reflected laser light from the object and information from the infrared radiation light alternately. visual sensor.