JPH08262140A - Beam tilt mechanism for laser radar and laser device using the tilt mechanism - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] To provide a laser beam tilting mechanism that can effectively collect scattered light emitted from a wide range of measurement target gas and returning from it with a telescope. [Structure] There is a spherical indentation 11 at the center of the bottom of an approximately square cavity 13 having an open top, and a box body 10 forming a concave arc portion with an internal thread 12 at the upper part of the inner wall of the cavity. Is provided with a mirror support portion 21 to which the laser beam tilting mirror 25 is attached and a spherical portion 23 connected to the mirror support portion 21. The spherical portion 23 is slidably fitted into the bottom spherical recess 11.
There is a mirror support body 20 configured such that the mirror support part swings and swings about the fulcrum. Further, a ring-shaped tightening member 30 having a male screw for fitting with the female screw 12 of the box on the outer peripheral side surface and having a hole 32 for the mirror support 20 in the center.
Similarly, it has a hole 41 for the mirror support body 20, and
It includes a rectangular pressing plate 40 having a shape capable of being fitted in the hollow portion 13 of 0 with a minute gap.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a beam tilting mechanism for a laser radar and a laser device using the tilting mechanism.

[0002]

2. Description of the Related Art Recently, the problem of environmental pollution has been widely taken up, but air pollution has become a major theme. Nitrogen oxides and sulfur oxides are particularly important among pollutant gases, and laser radars have conventionally been used to measure the concentrations of these pollutant gases and particular important gases of interest.

FIG. 6 is a diagram for explaining a gas concentration measuring method using a laser radar.

When measuring the concentration of a gas by a laser radar, a laser beam is used to generate a laser beam having a wavelength that is significantly absorbed by the gas to be measured, and the degree of absorption of the laser beam by the gas is detected by a photodetector or the like. Is measured, and for this purpose, a laser device 9 for generating a laser beam 6 having a unique wavelength that is absorbed by the measurement target gas 7 is used. In the laser radar, the laser beam 6 is radiated toward the measurement target gas 7, the returning weak light is condensed by the large-diameter telescope 5, and the degree of absorption by the gas is detected to obtain the gas concentration. At this time, the emission direction Y of the laser beam 6 must overlap the field of view 8 of the telescope 5. The scattered light of the measurement target gas 7 cannot be detected unless the laser beam 6 enters the field of view 8 of the telescope 5. Therefore, the laser beam 6
The direction of the laser beam 6 is adjusted by a mirror so that the emission direction of the laser beam coincides with the direction of the field of view 8 of the telescope 5. This is called a laser beam tilt mechanism. This tilt is adjusted so that the laser beam 6 enters the field of view 8 of the telescope 5, in which case it is visible to the eye or using an oscilloscope.

[0005]

Conventionally, in the measurement of gas concentration by this method, the positional relationship between the telescope and the laser beam has been fixed. Therefore, although the concentration measurement effect can be obtained to some extent in the measurement in only one direction, accurate concentration measurement cannot be performed when it is desired to measure the two-dimensional or three-dimensional spread. Therefore, a coude laser radar has been used in which the optical axis of the laser beam 6 is aligned with the rotation axis of the lens barrel and both the telescope 5 and the laser beam 6 are synchronously moved. However, there has not been a practical means for arbitrarily adjusting the positions of the telescope 5 and the laser beam 6 so that the telescope 5 and the laser beam 6 can be accurately moved when using the laser radar of the coude system.

The laser beam tilting mechanism that has been used in the past has one sphere between two plates and always keeps the distance between both plates constant at only one place, and fixes the mirror to the outside of one plate. However, the distance between the two plates is adjusted by two screws and springs so as to irradiate the laser beam. This conventional method has a drawback that the tilt range is narrow and it takes time to adjust with two screws.

The present invention has been made in view of the above points, and in a coup type laser radar, the positions of the telescope and the laser beam can be swiftly and accurately adjusted so that the telescope and the laser beam are moved accurately. The laser beam tilts so that the weak scattered light that is emitted toward a wide range of measurement target gas having a two-dimensional or three-dimensional spread, and that returns from it can be effectively collected by a telescope. An object of the present invention is to provide a mechanism and a laser device using the same.

[0008]

In order to solve the above-mentioned problems, the present invention has a cavity having a substantially square shape with an open top, and a spherical recess is provided at the center of the bottom of the cavity, and an inner wall of the cavity is formed. A box body in which a concave arc portion having a series of internal threads is formed in an upper portion, a mirror support portion for mounting a laser beam tilting mirror, and a spherical portion connected to the mirror support portion, the spherical portion being the box. A mirror support having a spherical surface that is slidably fitted in a spherical recess on the bottom of the body cavity, and the mirror support is configured to swing and swing about the spherical part; and a cavity of the box. A ring-shaped tightening member having a diameter longer than one side, an external thread on the outer peripheral side that fits with the internal thread of the concave arc portion of the box, and a hole in the center that projects the upper part of the mirror support, Projecting the top of the mirror support Has a hole that allows it to be fitted into the cavity of the box with a minute gap and can move up and down, and the tightening member and the spherical portion of the mirror support in the cavity of the box. And a quadrangle pressing plate interposed between and.

[0009]

With the beam tilting mechanism of the present invention, the horizontal and vertical rotation axes of the telescope and the optical axis of the laser beam can be accurately and easily aligned with each other.
Since the laser beam direction can be adjusted to any direction in 0 degree, the field of view of the telescope and the emitting direction of the laser beam are exactly overlapped, and it becomes possible to collect the scattered light intensity necessary for gas concentration measurement. Moves in synchronism with the laser beam.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the drawings.

FIG. 1 is a plan view of a beam tilting mechanism for a laser radar according to the present invention, FIG. 2 is a sectional view taken along the line II--II of FIG. 1, and FIG. 3 is a sectional view taken along the line III--III of FIG. is there.

The main components of the beam tilting mechanism for laser radar according to the present invention are a box 10, a mirror support 20,
The tightening member 30 and the pressing plate 40. The box body 10 has a substantially square hollow portion 13 with an open top, a spherical recess 11 at the center of the bottom of the hollow portion 13, and four concave portions at the upper portions of the four inner peripheral walls of the hollow portion 13. Arc part A
Are formed. A series of internal threads 12 are engraved on these four concave arc portions A.

The mirror support 20 comprises an uppermost mirror support 21 and a thin handle 2 connected below the mirror support 21.
2 and a spherical portion 23 connected below the handle 22. The top surface 24 of the mirror support portion 21 is formed at an angle of 45 degrees with respect to the central axis of the mirror support body 20 in the longitudinal direction, and the mirror 25 is attached to the top surface 24 with an adhesive. The spherical portion 23 has a diameter that can be accommodated in the hollow portion 13 of the box body 10 and has a spherical surface that is slidably fitted into the spherical recess 11 provided at the center of the bottom portion of the hollow portion 13. Mirror support 20 in which spherical portion 23 is fitted into spherical recess 11
Can swing and swing around the spherical recess 11 as a fulcrum as shown by an arrow B in FIG. The swing angle of the mirror support 20 is determined by the holes 32 of the tightening member 30 and the pressing plate 40, which will be described later.
It can be adjusted by changing the manufacturing dimensions of the holes 41 and the like.

The tightening member 30 is a ring having a diameter longer than one side of the cavity 13 of the box 10, a hole 32 in the center, and a male screw on the outer peripheral surface. It is possible to fit a series of internal threads 12 provided on the concave arc portion A. The upper part of the mirror support 20 can be projected from the hole 32. An appropriate number of small holes 31 are formed on the upper surface of the tightening member 30. This small hole 31
Is an insertion hole of a jig (not shown) for fitting and removing the fastening member 30 in the box 10.

The pressing plate 40 is a quadrangular plate that fits in the cavity 13 of the box 10 with a minute gap and can move up and down smoothly, and has a hole 41 in the center, and a mirror support is provided from this hole 41. The upper part of the body 20 can be projected. As shown in FIG. 2, the pressing plate 40 is interposed between the tightening member 30 and the spherical portion 23 of the mirror support 20 inside the cavity 13 of the box 10. Therefore, the tightening member 30
Is fitted to the female screw 12 provided on the concave arc portion A of the box 10 and rotated, the pressing plate 40 descends to press the spherical portion 23 of the mirror support 20 downward, and as a result, the mirror support 20 will not get out of position. When the pressing plate 40 descends in the direction of arrow C, the four corners 4 of the pressing plate 40 are
No. 2 descends inside the four corners of the cavity 13 of the box 10 and cannot rotate. Therefore, when the pressing plate 40 pushes the spherical portion 23 of the mirror support 20 downward in the direction of the arrow C, the mirror support 20 does not shift its fixed position, and as a result, the uppermost part of the mirror support 20. The mirror attached to the will not vibrate, and will have the effect of keeping the tilt adjustments correct.

FIG. 4 is a perspective view showing a schematic structure of a laser radar using the light beam tilting mechanism of the present invention, and FIG. 5 is a view for explaining the operating principle of the Coude system telescope of the laser radar of FIG.

The laser radar of FIGS. 4 and 5 is a coup type laser radar, in which a horizontal rotary table 2 is rotatably mounted on a top surface of a pedestal 1 supported by a tripod about a vertical axis V--V. Left and right upward protrusions 3 of the horizontal turntable 2
The left and right gun ears 4 are attached so as to be able to raise and lower about a horizontal axis H-H, and a large-diameter telescope 5 is fixed to these gun ears 4. The optical axis X-X of the telescope 5 is the vertical axis V-V of the horizontal turntable 2 and the horizontal axis H-H of the gun ear 4.
Pass through.

A bracket B1 attached to the mount 1,
Each of the bracket B2 attached to the horizontal rotary table 2, the bracket B3 and the bracket B4 attached to one of the upward protrusions 3, and the B5 attached to the gun ear 4 has mirrors M1, M2, M3, M4 on the top surface. The light beam tilting mechanism (not shown in FIGS. 4 and 5 except the mirror) of the present invention to which M5 is attached is fixed one by one.

In operating the beam tilting mechanism of the present invention,
The tightening member 30 of each tilting mechanism is loosened by a jig, the respective mirror support bodies 20 are swung and swung, and the tilts thereof are adjusted to lift the mirrors, so that the laser beam finally reaches the field of view 8 of the telescope 5. 6 so that it fits in (Fig. 6
), The tightening member 30 is tightened at that position, and the tilting operation is completed. Such a tilting operation is characterized in that it can be adjusted accurately in a short time and has a wide range of tilting as compared with the operation of a conventional tilting mechanism.

The laser beam 6 emitted from the light source is indicated by an arrow D.
The light is incident on M1 in the horizontal direction, and is reflected perpendicularly in the direction of arrow E to enter M2. The laser beam 6 reflected by M2 is horizontally incident on M3 in the direction of arrow F and reflected by arrow G
It is incident on M4 perpendicular to the direction. Further, it is reflected by M4 and is incident horizontally on the M5 in the direction of the arrow H, is reflected here and is emitted toward the measurement target gas 7 in the direction of the arrow Y, and the weak scattered light returning therefrom is the mirror of the telescope 5. The light is collected by (see FIG. 6).

The laser beam focused by the mirror in the telescope 5 is detected by the photomultiplier tube, converted into a voltage, amplified by an amplifier if necessary and put into an AD converter to be converted into a digital signal. And transfer it to a computer to get the waveform.

[0022]

As described above, the beam tilting mechanism for a laser radar according to the present invention includes a box body having a spherical recess at the center of the bottom and a series of internal threads formed on the upper part of the inner wall of the cavity, and a beam tilting device for laser beam. A mirror support having a mirror support for mounting a mirror and a spherical part that slides into a spherical recess on the bottom of the box cavity, and an external thread on the outer peripheral surface that fits with the internal thread of the concave arc of the box. A ring-shaped tightening member; and a pressing plate that fits in the cavity of the box with a minute gap and can move up and down and is fixed between the tightening member and the spherical portion of the mirror support. Because
Compared to the conventional beam tilt mechanism that uses screws, it can be adjusted in a shorter time and the tilt range is wider, so the horizontal and vertical rotation axes of the telescope and the optical axis of the laser beam can be accurately and easily Since it can be matched and the laser beam direction of 360 degrees of the measurement target can be matched, the field of view of the telescope and the exit direction of the laser beam exactly overlap, and the scattered light intensity required for gas concentration Can be collected. In addition, the telescope can be moved in synchronization with the laser beam.

[Brief description of drawings]

FIG. 1 is a plan view of a beam tilting mechanism for a laser radar according to the present invention.

FIG. 2 is a sectional view taken along the line II-II of FIG.

3 is a cross-sectional view taken along the line III-III of FIG.

FIG. 4 is a perspective view showing a schematic configuration of a laser radar using the light beam tilting mechanism of the present invention.

5A and 5B are diagrams for explaining the operating principle of the coupé-type telescope of the laser radar of FIG.

FIG. 6 is a diagram illustrating a gas concentration measuring method using a laser radar.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Frame 2 Horizontal rotary table 3 Upward protrusion 4 Gun ear 5 Telescope 6 Laser beam 7 Gas to be measured 8 Field of view of telescope 9 Laser device 10 Box body 11 Spherical dent 12 Female screw 13 Cavity 20 Mirror support 21 Mirror support 22 Handle 23 spherical portion 24 top surface 25 mirror 30 tightening member 31 jig fitting hole 32 hole 40 pressing plate 41 hole 42 corner portion A concave arc portion

Claims (2)

[Claims] 1. A mechanism for irradiating a laser beam radiated into a gas when measuring a gas concentration by a laser radar, which has a substantially square hollow portion with an open upper portion, and a spherical shape at the center of the bottom portion of the hollow portion. A box body having a recess and a concave arc portion having a series of internal threads formed in an upper portion of an inner wall of the cavity portion; a mirror support portion for mounting a laser beam tilting mirror; and a spherical portion connected to the mirror support portion. And the spherical portion has a spherical surface that is slidably fitted in the spherical concave portion at the bottom of the box cavity, and the spherical portion fitted to the spherical surface serves as a fulcrum so that the mirror support portion can swing and swing. Has a longer diameter than one side of the cavity of the box, has an external thread on the outer peripheral side that fits into the internal thread of the concave arc portion A of the box, and has the mirror support in the center. A hole that projects the upper part of the body A ring-shaped tightening member having, and a hole for projecting the upper part of the mirror support in the center,
It has such a shape that it can fit in the cavity of the box with a minute gap and can move up and down, and is interposed between the tightening member and the spherical portion of the mirror support in the cavity of the box. A light beam tilting mechanism for a laser radar, which includes a rectangular pressing plate. 2. A laser device using the beam tilting mechanism for a laser radar according to claim 1.