JPH0457984B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a laser radar visual sensor that can simultaneously obtain distance information and visual information.

BACKGROUND TECHNOLOGY Conventionally, this type of laser radar vision sensor has been disclosed in, for example, Applied Optics, Vol. 23.
2565 pages, 1984 (Appl.Optics, Vol23, P2565,
1984) is known. The conventional laser radar visual sensor will be described below with reference to FIG. 2.

As shown in FIG. 2, a laser beam emitted from a laser oscillator 21 is separated by a beam splitter 22 into a signal laser beam 23 and a reference laser beam 24. The signal laser beam is frequency-shifted by a frequency shifter 25 and intensity-modulated by a modulator 26 in a sinusoidal manner. The intensity-modulated signal laser beam 27 is two-dimensionally scanned by a two-dimensional scanner 28 and irradiates a target object 29 . The reflected laser beam 30 reflected from the surface of the object 29 passes through the two-dimensional scanner 28 again, is mixed with the reference laser beam 24 separated by the beam splitter 22, and is guided to the detector 31 by the beam splitter 32. Heterodyne detection is performed. The signal from the detector 31 is amplified by a preamplifier 33, passed through a bandpass filter 34 with the same frequency as the frequency of the carrier wave for intensity modulation, and demodulated by a demodulator 35, followed by a phase detector 36 for distance measurement; An intensity modulation detector 37 for visual information provides distance information and reflected laser light intensity information, respectively.

Problems to be Solved by the Invention However, in the configuration of such a conventional laser radar vision sensor, depending on the material of the object 29, the reflected signal cannot be detected by the detector 31, and the object 29 may be Sometimes you can't see it. That is, if the reflectance of the target object 29 to the laser beam 27 is very small and the reflected light from the target object becomes smaller than the detection ability of the detector 31, it becomes undetectable. Furthermore, if the object 29 has a large reflectance to the laser beam 27 and the object 29 is tilted, most of the energy of the emitted laser beam 27 will be reflected to the other side and will not return to the detector 31. , 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. It is an object of the present invention to provide a laser radar visual sensor that can perform the following functions.

Means for Solving the Problems Technical means of the present invention for solving the above problems include: a laser oscillator that emits infrared laser light; and intensity modulation of the infrared laser light emitted from the laser oscillator. an acousto-optic modulation element; an infrared laser beam whose intensity is modulated by the acousto-optic modulation element is two-dimensionally irradiated onto an object; and a reflected infrared laser beam in which the infrared laser beam is reflected from the object; a scanner that receives at least both the object infrared radiation of the object itself; and photoelectric conversion of both the reflected infrared laser beam from the object and the object infrared radiation received through the scanner. a first filter that outputs brightness information of the reflected infrared laser beam by separating a first signal component corresponding to the reflected infrared laser beam from the output of the infrared detector; a second filter that outputs brightness information due to the infrared radiation of the object by separating a second signal component corresponding to the object's infrared radiation from the output of the infrared detector; a phase detector that detects a phase lag of the output of the first filter with respect to the output of the infrared laser beam intensity-modulated by the optical modulation element, and outputs the phase lag as distance information to the object; It is equipped with

Effect The effects of the above technical means are as follows.

In other words, the reflected laser light and the infrared radiation from the object are detected by the same infrared detector, and a filter is used to separate the two so that they can be measured, so the reflected laser light cannot be obtained. In the case of such an object, infrared radiation increases and can be visualized using brightness information.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of a laser radar visual sensor in one embodiment of the present invention.

In FIG. 1, 1 is a laser oscillator, 3 is an acousto-optic modulator, 4 is a perforated mirror, 5 is a two-dimensional scanner, 6 is an object, 9 is a lens, 10 is an infrared detector, 11 is a preamplifier, and 12 is a A bandpass filter (BPF), 13 a phase detector, and 14 a reduction filter (LPF).

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

A laser beam 2 emitted from a laser oscillator 1 is intensity-modulated in a sinusoidal manner by an acousto-optic modulation element 3,
Through the hole in the center of the perforated mirror 4, the two-dimensional scanner 5
The target object 6 is irradiated with the light. The reflected laser beam 8 from the object 6 passes through the two-dimensional scanner 5, is reflected by the perforated mirror 4, is focused by the lens 9, and is detected by the infrared detector 10. At this time, infrared radiation 7 is emitted from the object 6, which is determined by the temperature and emissivity of the object 6. That is, if the temperature of an object is above absolute zero, there is infrared radiation from all objects. The amount of infrared radiation varies depending on the temperature and emissivity (efficiency of infrared radiation) of the object, and the higher the temperature of the object, the greater the amount, and it is maximum in the case of a completely black body that does not reflect infrared rays at all. In the case of a completely reflective surface, the infrared radiation of the object itself is zero, but infrared radiation from surrounding objects is reflected. Therefore, a portion of the infrared radiation 7 emitted from the object 6 is also detected by the infrared detector 10.

After the output of the infrared detector 10 is amplified by a preamplifier 11, an infrared radiation component is separated by a reduction filter 14, and infrared radiation information is obtained.
The high-frequency components that are not separated by the reduction filter 14 pass through the bandpass filter 12 matched to the intensity modulation frequency, and only the intensity-modulated reflected laser beam 8 component is selected. Reflected laser beam brightness information can be obtained from the intensity.

As is clear from the above embodiment, it is possible to measure both the distance information and reflected laser beam brightness information from the object 6 by the intensity-modulated laser beam, and the infrared radiation information from the object 6. Even if the emitted laser beam 2 is absorbed by the object 6 or reflected to the other object and cannot be detected by a conventional laser radar visual sensor, it can be detected.
In particular, in the above embodiment, the addition of the reduction filter 14 allows detection to be performed using infrared radiation components that have not been used in the past, so the configuration is simple and inexpensive.

Effects of the Invention As described above, according to the present invention, reflected laser light and infrared radiation from an object are detected by an infrared detector, and a filter is used to separate and measure the two. Therefore, in the case of objects for which reflected laser light cannot be obtained, they can be visualized using infrared radiation information. Therefore, any object can be detected and visualized.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a laser radar visual sensor according to an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional laser radar visual sensor. 1... Laser oscillator, 3... Acousto-optic modulator, 4... Hole mirror, 5... Two-dimensional scanner, 6
...Object, 7...Infrared radiation, 10...Infrared detector, 11...Preamplifier, 12...Band filter (BPF), 13...Phase detector, 14...Reduction filter (LPF).

Claims (1)

[Scope of Claims] 1. A laser oscillator that emits an infrared laser beam, an acousto-optic modulation element that modulates the intensity of the infrared laser beam emitted from the laser oscillator, and an infrared laser beam that is intensity-modulated by the acousto-optic modulation element. a scanner that two-dimensionally irradiates an object with the infrared laser beam and receives at least both the reflected infrared laser beam reflected from the object and the object's own infrared radiation; an infrared detector that photoelectrically converts both the reflected infrared laser beam from the object and the object infrared radiation received through the scanner, and the reflected infrared laser beam is converted from the output of the infrared detector a first filter that outputs brightness information of the reflected infrared laser beam by separating a first signal component corresponding to the object infrared radiation from the output of the infrared detector; a second filter that outputs luminance information due to infrared radiation of the object by separating two signal components; A laser radar visual sensor comprising: a phase detector that detects a phase lag in the output of a filter and outputs the phase lag as distance information to the object.