JP3835016B2 - Laser radar equipment - Google Patents

Laser radar equipment Download PDF

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Publication number
JP3835016B2
JP3835016B2 JP29478998A JP29478998A JP3835016B2 JP 3835016 B2 JP3835016 B2 JP 3835016B2 JP 29478998 A JP29478998 A JP 29478998A JP 29478998 A JP29478998 A JP 29478998A JP 3835016 B2 JP3835016 B2 JP 3835016B2
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Japan
Prior art keywords
semi
field stop
light
laser beam
laser
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Expired - Fee Related
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JP29478998A
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Japanese (ja)
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JP2000121724A (en
Inventor
隆一 樋口
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三菱電機株式会社
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Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to detection of an axial deviation between a transmission axis and a reception axis of a laser radar device.
[0002]
[Prior art]
The laser radar device emits the laser itself, hits the target, receives the reflected light from the target, measures the signal magnitude and the time from the launch, and determines the characteristics of the target and the distance to the target Device. Recently, the field of application has expanded, and it is now possible to measure the altitude distribution of atmospheric scattering characteristics onboard satellites. Since the laser radar device receives the reflected laser beam, the target irradiated with the laser must be in the field of view of the receiving optical system. If it is completely out of the field of view, the signal cannot be grasped in the first place, and even if it is partially off, the characteristics of the target cannot be measured accurately. Therefore, it is an indispensable condition for the laser radar apparatus to keep the target irradiated with the laser at the center of the field of view of the receiving optical system, in other words, to match the axes of transmission and reception. Axis deviation detection and axis deviation correction are required to match the transmission and reception axes.
[0003]
FIG. 5 is a diagram showing a conventional axis deviation detection method. In FIG. 5, 1 is a laser, 2 is an adjustment device for adjusting the direction of the laser beam, such as a double wedge, 3 is a receiving telescope such as a Cassegrain optical system, 4 is a field stop such as a pinhole, and 5 is a relay An optical system, 6 is a narrow band filter, 7 is a detector, 8 is a signal processing circuit, 10 is a semi-transparent mirror, 16 is a lens, and 17 is a quadrant detector.
[0004]
Next, the operation will be described. The laser beam generated from the laser 1 is transmitted toward the target through the adjusting device 2 and the semi-transparent mirror 10. The reflected light from the target is collected by the receiving telescope 3 including the cassegrain primary mirror 3 a and the cassegrain secondary mirror 3 b and passes through the field stop 4. The light that has passed through the field stop 4 passes through a narrow-band filter 6 placed inside a relay optical system 5 including a lens 5a and a lens 5b, and is collected by a detector 7. The light is converted into an electric signal by the detector 7, amplified and digitized by the signal processing circuit 8, and target information is extracted. In such a laser radar apparatus, the axis deviation is detected as follows. A part of the laser beam is reflected by the semi-transparent mirror 10 and enters the four-quadrant detector 17 through the lens 16. Since the 4-quadrant detector 17 is placed at the focal point of the lens 16, the laser beam becomes a small spot on the surface of the 4-quadrant detector 17. If the spot is at the center of the four-quadrant detector 17, the output of the four-quadrant detector 17 is 0. If the spot is shifted from the center, an output proportional to the shift is obtained. By detecting the spot position in this way, the direction of the laser beam can be known. If a deviation occurs, the adjustment device 2 corrects the output while monitoring the output of the four-quadrant detector 17.
[0005]
[Problems to be solved by the invention]
The conventional axis deviation detection device in the laser radar apparatus detects the transmission axis deviation as described above. Compared to the transmission axis misalignment caused by a laser device that consumes a large amount of power and therefore generates a large amount of heat, the misalignment on the receiving side is much smaller. Substituting the relative axis misalignment of can be used. However, in a satellite-equipped device in which thermal imbalance occurs even if there is no internal heat generation, the reception axis deviation cannot be ignored. Therefore, the conventional method that only detects the transmission axis deviation correctly detects the relative axis deviation of transmission and reception. There is a problem that it cannot be evaluated.
[0006]
The present invention has been made to solve the above-described problems, and an object of the present invention is to obtain an apparatus capable of detecting transmission and reception relative axis deviations by detecting reception axis deviations simultaneously with transmission axis deviations.
[0007]
[Means for Solving the Problems]
The apparatus according to the first aspect of the invention emits light from the receiving optical system in the reverse direction by illuminating the field stop that determines the receiving field of view, and detects the relative axis shift between the optical axis and the optical axis of the transmitted laser beam. It is a thing. The axis deviation is detected as follows. A part of the light emitted from the receiving optical system is bent by a reflecting mirror, and a part of the transmission laser beam is bent by a semi-transparent mirror, and both beams are superimposed to form an image on an image sensor. If the axes are aligned, the image is formed at one point, but if the axis shifts, the spots are separated. Since the distance between the two spots corresponds to the misalignment of the two axes, the misalignment is known. In addition, by integrating the reflector and the semi-transparent mirror so that relative changes do not occur, even if the orientation of the reflector / semi-transparent mirror changes due to surrounding changes, the relative axis deviation can be measured accurately. .
[0008]
The apparatus according to the second invention is a case where the reflecting mirror in the first invention is replaced with a semi-transparent mirror.
[0009]
The device according to the third invention is a case where the laser beam is emitted from the center of the receiving optical system, that is, applied to a coaxial laser radar device.
[0010]
The apparatus according to the fourth aspect of the invention irradiates a part of the outgoing laser beam to the receiving detector through an optical fiber so that not only the axis deviation but also the deviation of the detector can be detected.
[0011]
The apparatus according to the fifth aspect of the invention facilitates observation by illuminating from the back of the field stop to illuminate the center of the field of view.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
Embodiment 1 of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is a laser, 2 is an adjustment device for adjusting the direction of a laser beam, such as a double wedge, 3 is a receiving telescope such as a Cassegrain optical system, 4 is a field stop such as a pinhole, and 5 is a relay. An optical system, 6 is a narrow band filter, 7 is a detector, and 8 is a signal processing circuit, which are components of a normal laser radar device. Reference numeral 9 denotes a reflecting mirror, 10 denotes a semi-transparent mirror, 11 denotes a support frame that integrally supports the reflecting mirror 9 and the semi-transparent mirror 10, 12 denotes an image sensor, and 13 denotes an illumination light source.
[0013]
Next, the operation will be described. A laser beam generated from the laser 1 is transmitted toward the target via the adjusting device 2 and the semi-transparent mirror 10. The reflected light from the target is collected by the receiving telescope 3 including the cassegrain primary mirror 3 a and the cassegrain secondary mirror 3 b and passes through the field stop 4. The light that has passed through the field stop 4 passes through a narrowband filter 6 placed inside a relay optical system 5 including a lens 5a and a lens 5b, and is collected by a detector 7. The light is converted into an electric signal by the detector 7, amplified and digitized by the signal processing circuit 8, and target information is extracted. In such a laser radar apparatus, the axis deviation is detected as follows. The illumination light source 13 illuminates the field stop 4 from the front. The field stop 4 is usually a pinhole and has a small hole in the substrate. When illuminated, light is diffusely reflected from the substrate. There is no light from the small holes, but they are much smaller than the diffusely reflected light from the substrate, so the small holes look black. Diffuse reflected light from the substrate exits in the opposite direction to the incident light of the laser radar device through the cassegrain secondary mirror 3b and the cassegrain main mirror 3a. A part of the light beam exiting from the Kasegrain main mirror 3a is blocked by the reflecting mirror 9, bent, and taken out. A part of the laser beam from the laser 1 is also bent by the semi-transparent mirror 10 and taken out. The two beams taken out by bending are merged by the semi-transparent mirror 10 and enter the image sensor 12. From the observation of this image, it can be seen that the optical axes are aligned when the spots overlap, and the optical axes are shifted when the spots are separated. If the optical axis is deviated, it can be corrected by the beam direction adjusting device 2. Since the reflecting mirror 9 and the semi-transparent mirror 10 are integrated so that they do not move independently even if there is deformation in the surroundings, the direction of the light beam is the same as that of one plane mirror, and the transmission / reception axis deviation is accurately measured. can do.
[0014]
In FIG. 1, a semi-transparent mirror may be used instead of the reflecting mirror 9.
[0015]
Embodiment 2. FIG.
Another embodiment is shown in FIG. In FIG. 2, the laser beam generated from the laser 1 passes through the adjusting device 2 and is translated by the two right-angle prisms 18 a and 18 b to the back side of the cassegrain secondary mirror 3 b, and then toward the target through the semi-transparent mirror 14. Sent out. The reflected light from the target is collected by the receiving telescope 3 including the cassegrain primary mirror 3 a and the cassegrain secondary mirror 3 b and passes through the field stop 4. The light that has passed through the field stop 4 passes through a narrowband filter 6 placed inside a relay optical system 5 including a lens 5a and a lens 5b, and is collected by a detector 7. The light is converted into an electric signal by the detector 7, amplified and digitized by the signal processing circuit 8, and target information is extracted. In such a coaxial type laser radar apparatus, the axis shift detection is performed as follows. A part of the laser beam is reflected by the semi-transparent mirror 14 and taken out. Part of the light emitted from the receiving telescope is also bent out by the semi-transparent mirror 10 and extracted. The two beams taken out by bending are merged by the semi-transparent mirror 10 and imaged on the image sensor 12.
[0016]
Embodiment 3 FIG.
Another embodiment is shown in FIG. In FIG. 3, reference numeral 15 denotes an optical fiber having one end placed at the end of the laser beam and the other end placed near the detector. A part of the laser beam is taken out by the optical fiber 15 and irradiated to the detector 7. The light diffusely reflected by the detector surface passes through the relay optical system 5 and the field stop 4 and exits from the receiving telescope 3. Since there is a narrow band filter 6 that allows only the laser wavelength to pass through in the relay optical system 5, a part of the laser light itself is used to pass through the relay optical system 5. With this configuration, the light emitted from the field stop 4 can be used as in the first embodiment. Further, if the detector 7 is displaced, the light deviating from the uniform detector surface passes through the field stop 4 and exits from the receiving telescope 3, so that the displacement of the detector 7 can be found by observing the spot shape.
[0017]
Embodiment 4 FIG.
Another embodiment is shown in FIG. In FIG. 4, illumination is performed from the back of the field stop 4. By illuminating in this way, only the light that passes through the hole formed in the substrate, not the diffusely reflected light from the substrate, enters the image sensor, so that the image can be easily observed.
[0018]
【The invention's effect】
As described above, according to the present invention, since it is possible to measure the relative axis deviation between the transmission axis and the reception axis of the laser radar apparatus, the laser radar on the artificial satellite orbit where not only the transmission axis but also the change of the reception axis cannot be ignored. Increase instrument measurement accuracy.
[Brief description of the drawings]
FIG. 1 is a diagram showing a laser radar apparatus according to Embodiment 1 of the present invention.
FIG. 2 is a diagram showing a second embodiment of the present invention.
FIG. 3 is a diagram showing a third embodiment of the present invention.
FIG. 4 is a diagram showing a fourth embodiment of the present invention.
FIG. 5 is a diagram showing a conventional laser radar device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Laser, 2 Laser beam direction adjustment apparatus, 3 Reception telescope, 3a Cassegrain primary mirror, 3b Cassegrain secondary mirror, 4 Field stop, 5 Relay optical system, 5a, 5b Lens, 6 Narrow-band filter, 7 Detector, 8 Signal processing Circuit, 9 Reflector, 10 Semi-transparent mirror, 11 Support frame, 12 Image sensor, 13 Illumination light source, 14 Semi-transparent mirror, 15 Optical fiber, 16 Lens, 174 Quadrant detector, 18a, 18b Right angle prism.

Claims (4)

  1. Laser that generates a laser beam, a receiving telescope that receives reflected light from a target irradiated with the laser beam, a field stop that adjusts the field of view of the receiving telescope, and a relay optical system that collects light emitted from the field stop on a detector In a laser radar apparatus comprising: a detector that converts light collected by the relay optical system into an electrical signal; and a signal processing circuit that extracts target information from the electrical signal.
    A light source for illuminating the field stop,
    A reflecting mirror that bends part of illumination light from the light source that is emitted from the field stop through the receiving telescope;
    A semi-transparent mirror that overlaps with the illumination light bent by the reflecting mirror and is arranged in parallel with the reflecting mirror and bends a part of the laser beam;
    A support frame that integrally supports the reflector and the semi-transparent mirror;
    A laser radar device comprising: an image sensor for photographing light emitted from the semi-transparent mirror.
  2. Laser that generates a laser beam, a receiving telescope that receives reflected light from a target irradiated with the laser beam, a field stop that adjusts the field of view of the receiving telescope, and a relay optical system that collects light emitted from the field stop on a detector In a laser radar apparatus comprising: a detector that converts light collected by the relay optical system into an electrical signal; and a signal processing circuit that extracts target information from the electrical signal.
    A light source for illuminating the field stop,
    A first semi-transparent mirror that bends part of illumination light from the light source that is emitted from the field stop through the reception telescope;
    A second semi-transparent mirror that overlaps the illumination light bent by the first semi-transparent mirror and is arranged in parallel with the reflecting mirror and bends a part of the laser beam;
    A support frame that integrally supports the two semi-transparent mirrors,
    A laser radar device comprising: an image sensor for photographing light emitted from the second semi-transparent mirror.
  3. Laser that generates a laser beam, a receiving telescope that receives reflected light from a target irradiated with the laser beam, a field stop that adjusts the field of view of the receiving telescope, and a relay optical system that collects light emitted from the field stop on a detector In a laser radar apparatus comprising: a detector that converts light collected by the relay optical system into an electrical signal; and a signal processing circuit that extracts target information from the electrical signal.
    A light source for extracting a part of the laser beam with an optical fiber and illuminating the detector;
    A reflecting mirror that bends part of illumination light from the light source that is emitted from the field stop through the receiving telescope;
    A semi-transparent mirror that overlaps with the illumination light bent by the reflecting mirror and is arranged in parallel with the reflecting mirror and bends a part of the laser beam;
    A support frame that integrally supports the reflector and the semi-transparent mirror;
    A laser radar device comprising: an image sensor for photographing light emitted from the semi-transparent mirror.
  4. Laser that generates a laser beam, a receiving telescope that receives reflected light from a target irradiated with the laser beam, a field stop that adjusts the field of view of the receiving telescope, and a relay optical system that collects light emitted from the field stop on a detector In a laser radar apparatus comprising: a detector that converts light collected by the relay optical system into an electrical signal; and a signal processing circuit that extracts target information from the electrical signal.
    A light source for illuminating the field stop from the back side,
    A reflecting mirror that bends part of illumination light from the light source that is emitted from the field stop through the receiving telescope;
    A semi-transparent mirror that overlaps with the illumination light bent by the reflecting mirror and is arranged in parallel with the reflecting mirror and bends a part of the laser beam;
    A support frame that integrally supports the reflector and the semi-transparent mirror;
    A laser radar device comprising: an image sensor for photographing light emitted from the semi-transparent mirror.
JP29478998A 1998-10-16 1998-10-16 Laser radar equipment Expired - Fee Related JP3835016B2 (en)

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JP29478998A JP3835016B2 (en) 1998-10-16 1998-10-16 Laser radar equipment

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Application Number Priority Date Filing Date Title
JP29478998A JP3835016B2 (en) 1998-10-16 1998-10-16 Laser radar equipment

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JP3835016B2 true JP3835016B2 (en) 2006-10-18

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US9513107B2 (en) 2012-10-05 2016-12-06 Faro Technologies, Inc. Registration calculation between three-dimensional (3D) scans based on two-dimensional (2D) scan data from a 3D scanner
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