Disclosure of Invention
The invention provides a Mie scattering laser radar and an optical axis calibration method thereof for solving the problems.
A first object of the present invention is to provide a rice scattering lidar comprising: the device comprises a laser emission unit, a beam expanding and collimating unit, an optical receiving unit, an optical detection unit and a supporting component;
The laser emission unit comprises a laser driver, a laser emission cavity, emitted laser, a fixed reflector, a first adjustable reflector, a reflection assembly mounting plate, a fixed reflector mounting frame and an adjustable reflector fixing frame; the beam expanding and collimating unit comprises a half-wave plate, a beam expanding lens, a second adjustable reflector, a large fixed reflector, a half-wave plate mounting ring, a half-wave plate fixing frame, a beam expanding lens mounting frame, a large reflector mounting frame and a large reflector fixing frame; the optical receiving unit comprises a Cassegrain telescope, a telescope mounting plate, a diaphragm, a collimating lens, a sub-optical path reflecting mirror, a dichroic sheet, a narrow-band optical filter and a polarizing prism; the support assembly includes: the device comprises a main support frame, a first backboard, a second backboard and a plurality of support columns;
The laser driver, the laser emission cavity, the fixed reflector mounting frame, the adjustable reflector mounting frame, the half-wave plate mounting frame and the beam expander mounting frame are fixedly arranged on the reflector assembly mounting plate; the fixed reflector is fixed on the fixed reflector mounting frame; the first adjustable reflector is fixed on the adjustable reflector mounting frame, and the adjustable reflector mounting frame is connected with the adjustable reflector mounting frame through at least three adjusting screws; the adjusting screw is provided with a pre-tightening spring in a pressing mode and is used for adjusting the angle of the first adjustable reflecting mirror by rotating the adjusting screw;
The half-wave plate is fixed on the half-wave plate mounting ring, and the half-wave plate mounting ring is movably connected with the half-wave plate fixing frame; the beam expander is fastened on the beam expander mounting frame; the second adjustable reflector is fixed on the large reflector mounting frame, the large reflector mounting frame is connected with the large reflector fixing frame through a large adjusting screw, and the large reflector fixing frame is fixed on the second backboard; the large fixed reflector is fixed at the hollow part of the second backboard and is used for enabling emergent laser to enter the atmosphere; the second backboard and the first backboard and the main support frame are connected through support column threads;
The laser driver generates laser, the laser emission cavity emits and emits laser, the laser is reflected by the fixed reflector and then reflected by the first adjustable reflector, and the laser is incident to the half-wave plate; the emergent laser enters the beam expander after passing through the half-wave plate, is reflected by the second adjustable reflector and the large fixed reflector after being emergent, and is emitted into the atmosphere; the back scattered light generated by the laser incident into the atmosphere encountering aerosol particles is reflected by the Cassegrain telescope and then converged into a focus, and the diaphragm is arranged at the focus position and used for shielding stray light; the backward scattered light passing through the diaphragm is collimated by the collimating lens, reflected by the sub-optical path reflecting mirror, dichroic sheet and narrow-band filter in sequence, and then enters the polarizing prism; the back-scattered light passing through the polarizing prism is received by an optical detection unit.
Preferably, the optical detection unit includes a first optical detector and a second optical detector; the back scattered light is changed into two paths of light beams with different polarization states after exiting from the polarizing prism, and the two paths of light beams are respectively received by the first optical detector and the second optical detector.
Preferably, the laser emission unit further comprises a heat dissipation backboard and a radiator, and the heat dissipation backboard is fixedly connected with the reflection assembly mounting plate; the laser driver and the laser emission cavity are fixedly arranged close to one surface of the heat dissipation back plate, and the radiator is arranged on the other surface of the heat dissipation back plate and used for providing real-time heat dissipation for the laser driver and the laser emission cavity.
Preferably, the half-wave plate is directly stuck and fixed on the half-wave plate mounting ring through epoxy glue; the half-wave plate mounting ring is provided with fine threads, the half-wave plate mounting ring can be screwed into the half-wave plate fixing frame to realize movable connection, and the angle of the half-wave plate is adjusted through rotation of the fine threads.
Preferably, the support assembly further comprises four auxiliary support blocks; the Cassegrain telescope is connected with the telescope mounting plate through bolts, and the telescope mounting plate is connected with the main support through bolts; four auxiliary supporting blocks are arranged on the first backboard, and the Cassegrain telescope passes through the hollowed-out part of the first backboard and is clamped by the auxiliary supporting blocks in a tight fit manner.
Preferably, the cassegrain telescope comprises a primary card mirror and a secondary card mirror, and the backward scattered light generated by the laser incident into the atmosphere encountering aerosol particles is reflected by the primary card mirror and then reflected by the secondary card mirror.
Preferably, the transmission band in the dichroic plate is 532nm wavelength.
The second object of the present invention is to provide a method for calibrating an optical axis of a Mie scattering laser radar, which is used for adjusting the Mie scattering laser radar to make the optical axes of laser emission and laser reception coaxial; the method specifically comprises the following steps:
s1, temporarily adding a point light source behind a diaphragm, wherein the point light source is close to the diaphragm;
S2, arranging a collimator opposite to the whole meter scattering laser radar, and arranging a CCD camera at the receiving end of the collimator; opening the point light source, reversely enabling light to enter the collimator through the Cassegrain telescope, and displaying a small light spot on the target surface of the CCD camera;
S3, turning on a laser driver, and after the emitted laser passes through the collimator, displaying a large light spot on the target surface of the CCD camera, and obtaining the coaxial state of the two light spots by reading the pixel points of the CCD camera;
S4, adjusting the angle of the emergent laser by adjusting the screwing degree of at least one large adjusting screw, so that a large light spot of the emergent laser on the CCD camera and a small light spot of the point light source on the CCD camera are concentric; at this time, the optical axes of the transmission and the reception are considered to be coaxial, and the optical axis calibration is completed.
Compared with the prior art, the invention has the following beneficial effects:
According to the invention, the laser driver, the laser cavity and the Q-switching are disassembled, so that the space utilization rate can be greatly improved, a heat dissipation mode can be designed in a targeted manner, and a plurality of reflectors are additionally arranged between the laser and the beam expander, and between the beam expander and the emergent light, so that a plurality of positions on a light path can be adjusted, and the convenience of assembling and adjusting the optical machine is improved;
The beam expanding collimation system and the reflector additionally arranged in the optical detection unit can be independently adjusted, so that the two systems can be adjusted to avoid adjusting the Cassegrain receiving system, the purpose of coaxial transmitting and receiving light can be achieved, and the adjustment difficulty of the whole machine is greatly reduced; the invention has the advantages that the diaphragm is arranged at the focus of the Cassegrain receiving system, the ultra-narrow band filter is arranged at the front end of the optical detector, the influence of background light noise on signals is greatly reduced, the overall signal to noise ratio of the system is improved, and meanwhile, the invention also introduces a calibration method which can be applied to the coaxiality of the receiving and transmitting optical paths of the laser radar, ensures the coaxiality of the transmitting optical axis of laser and the receiving optical axis of a telescope, and ensures the signal quality.
Drawings
Fig. 1 is a schematic diagram of an optical path of a Mie scattering lidar according to an embodiment of the present invention.
Fig. 2 is an isometric schematic view of a rice scattering lidar structure provided according to an embodiment of the present invention.
Fig. 3 is another schematic axial view of a Mie scattering lidar structure provided according to an embodiment of the present invention.
Fig. 4 is a schematic diagram of an optical axis section of an optical receiving unit of a Mie scattering laser radar according to an embodiment of the present invention.
Fig. 5 is a schematic cross-sectional view of a Mie scattering laser radar according to an embodiment of the present invention on an optical axis of an outgoing laser.
Fig. 6 is a schematic diagram of an optical axis calibration method according to an embodiment of the present invention.
Reference numerals:
1. a laser driver;
2. a laser emitting cavity;
2-1, a heat dissipation backboard;
3. emitting laser;
4. A fixed mirror;
4-1, fixing a reflector mounting frame; 4-2, a reflective assembly mounting plate;
5. a first adjustable mirror;
5-1, an adjustable reflector mounting rack; 5-2, an adjustable reflector fixing frame; 5-3, pre-tightening a spring; 5-4, adjusting a screw;
6. A half-wave plate;
6-1, a half-wave plate mounting ring; 6-2, a half-wave plate fixing frame;
7. A beam expander;
7-1, a beam expander mounting rack; 7-2, mounting blocks; 7-3, a first backboard; 7-4, long support columns; 7-5, short support columns; 7-6, a second backboard;
8. A second adjustable mirror;
8-1, a large reflector mounting rack; 8-2, a large reflector fixing frame; 8-3, big adjusting screws;
9. a large fixed mirror;
10. back-scattered light;
11. a card-type secondary mirror;
12. A card-type main mirror;
13. A diaphragm;
14. a collimating lens;
15. a sub-optical path mirror;
16. a dichroic plate;
17. A narrow band filter;
18. A polarizing prism;
19-1, a first photodetector;
19-2, a second photodetector;
20. Cassegrain telescope;
21. A telescope mounting plate;
22. A main support frame;
23. a heat sink;
24. A circuit board assembly;
25. an auxiliary supporting block;
26. a point light source;
27. A collimator;
28. a CCD camera;
28-1, small light spots; 28-2, large light spot.
Detailed Description
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, like modules are denoted by like reference numerals. In the case of the same reference numerals, their names and functions are also the same. Therefore, a detailed description thereof will not be repeated.
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be further described in detail with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not to be construed as limiting the invention.
A rice scattering lidar comprising: the device comprises a laser emission unit, a beam expanding and collimating unit, an optical receiving unit, an optical detection unit and a supporting component;
The laser emitting unit includes: the device comprises a laser driver, a laser emission cavity, emitted laser, a fixed reflector, a first adjustable reflector, a reflector assembly mounting plate, a fixed reflector mounting frame, an adjustable reflector fixing frame, a heat dissipation backboard and a heat radiator;
the beam expansion collimation unit comprises: the device comprises a half-wave plate, a beam expander, a second adjustable reflector, a large fixed reflector, a half-wave plate mounting ring, a half-wave plate fixing frame, a beam expander mounting frame, a large reflector mounting frame and a large reflector fixing frame;
The optical receiving unit includes: the device comprises a Cassegrain telescope, a telescope mounting plate, a diaphragm, a collimating lens, a sub-optical path reflecting mirror, a dichroic plate, a narrow-band filter and a polarizing prism; the Cassegrain telescope comprises a cassette primary mirror and a cassette secondary mirror;
The support assembly includes: the device comprises a main support frame, a first backboard, a long support column, a short support column and a second backboard.
The laser driver is separated from the laser emission cavity, the laser driver and the laser emission cavity are mounted close to the heat dissipation back plate in a bolt connection mode, and the radiator is close to the other surface of the heat dissipation back plate in a bolt connection mode, so that heat generated by the laser driver and the laser emission cavity can be directly transferred to the radiating fin of the radiator;
The fixed reflector mounting frame and the adjustable reflector mounting frame are mounted with the reflector assembly mounting plate in a bolt connection mode, and the reflector assembly mounting plate is mounted on the heat dissipation backboard in a bolt connection mode; the fixed reflector is directly adhered to the fixed reflector mounting frame through epoxy glue, the first adjustable reflector is directly adhered to the adjustable reflector mounting frame through epoxy glue, the adjustable reflector mounting frame is connected with the adjustable reflector mounting frame through three adjusting screws, and three pre-tightening springs are pressed on the three adjusting screws, so that the purpose of adjusting the angle of the first adjustable reflector can be achieved by rotating the adjusting screws at different positions, and the aim of aligning the emergent laser optical axis with the beam expander optical axis is achieved;
the laser driver generates laser, the laser emission cavity emits emergent laser, the emergent laser is reflected by the fixed reflector and then reflected by the first adjustable reflector, and the emergent laser enters the beam expanding and collimating unit.
The half-wave plate is fixed on the half-wave plate mounting ring, and the half-wave plate mounting ring is movably connected with the half-wave plate fixing frame; the half-wave plate fixing frame is installed with the reflecting component mounting plate in a bolt connection mode; the beam expander is fastened on the beam expander mounting frame, and the beam expander mounting frame is fixedly arranged on the heat dissipation backboard in a bolt connection mode;
The second adjustable reflector is directly stuck on the large reflector mounting frame through epoxy glue, the large reflector mounting frame is connected with the large reflector mounting frame through a large adjusting screw, and the large reflector mounting frame is connected with the second backboard through threads; the large fixed reflector is fixed at the hollow part of the second backboard and is used for enabling emergent laser to enter the atmosphere; the second backboard is in threaded connection with the first backboard through four short support columns; the first backboard is in threaded connection with the main support frame through four long support columns; the two ends of the heat dissipation backboard are respectively connected with the first backboard and the main support frame through bolts, so that the whole machine forms a closed structure, and the strength and the stability are improved;
The emergent laser enters a beam expander after passing through the half wave plate; the beam diameter becomes larger after passing through the beam expander, and the beam divergence angle becomes smaller; the outgoing laser is emitted from the beam expander, reflected by the second adjustable reflector, reflected by the large fixed reflector and then emitted into the atmosphere.
The back scattered light generated by the laser incident into the atmosphere encountering aerosol particles is reflected by the card-type primary mirror and then reflected by the card-type secondary mirror to be converged into a focus, and a diaphragm is arranged at the focus position and used for shielding stray light; the diaphragm is connected with the Cassegrain telescope through a bolt, and the backward scattered light passing through the diaphragm is changed into parallel light through the collimating lens, is reflected by the sub-optical path reflector, passes through the dichroic plate, passes through the narrow-band filter and then is incident to the polarizing prism; the back scattered light passing through the polarizing prism becomes two paths of light beams with different polarization states, and the two paths of light beams are received by the optical detection unit.
In a specific embodiment, the optical detection unit comprises a first optical detector and a second optical detector; the back scattered light is changed into two paths of light beams with different polarization states after exiting from the polarizing prism, and the two paths of light beams are respectively received by the first optical detector and the second optical detector.
In a specific embodiment, the laser emission unit further comprises a heat dissipation backboard and a radiator, wherein the heat dissipation backboard is fixedly connected with the reflection assembly mounting plate; the laser driver and the laser emission cavity are fixedly arranged close to one surface of the heat dissipation back plate, and the radiator is arranged on the other surface of the heat dissipation back plate and used for providing real-time heat dissipation for the laser driver and the laser emission cavity.
In a specific embodiment, the half-wave plate is directly stuck and fixed on the half-wave plate mounting ring through epoxy glue; the half-wave plate mounting ring is provided with fine threads, the half-wave plate mounting ring can be screwed into the half-wave plate fixing frame to realize movable connection, and the angle of the half-wave plate is adjusted through rotation of the fine threads.
In a specific embodiment, the support assembly further comprises four auxiliary support blocks; the Cassegrain telescope is connected with the telescope mounting plate through bolts, and the telescope mounting plate is connected with the main support through bolts; four auxiliary supporting blocks are arranged on the first backboard, and the Cassegrain telescope passes through the hollowed-out part of the first backboard and is clamped by the auxiliary supporting blocks in a tight fit manner.
In a specific embodiment, different transmission bands and reflection bands are provided in the dichroic plate, the transmission bands being 532nm wavelength.
Example 1
A Mie scattering lidar and light path diagram as shown in fig. 1-5, comprising: the device comprises a laser emission unit, a beam expanding and collimating unit, an optical receiving unit, an optical detection unit and a supporting component;
the laser emitting unit includes: the laser comprises a laser driver 1, a laser emission cavity 2, emitted laser 3, a fixed reflector 4, a first adjustable reflector 5, a heat dissipation backboard 2-1, heat dissipation fins 23 and a circuit board assembly 24;
The beam expansion collimation unit comprises: the device comprises a half-wave plate 6, a beam expander 7, a second adjustable reflector 8, a large fixed reflector 9, a half-wave plate mounting ring 6-1, a half-wave plate fixing frame 6-2, a beam expander mounting frame 7-1, a large reflector mounting frame 8-1 and a large reflector fixing frame 8-2;
The optical receiving unit includes: the device comprises a Cassegrain telescope 20, a telescope mounting plate 21, a diaphragm 13, a collimating lens 14, a sub-optical path reflecting mirror 15, a dichroic sheet 16, a narrow-band filter 17 and a polarizing prism 18; the cassegrain telescope 20 comprises a primary mirror 12 and a secondary mirror 11;
The support assembly includes: the main support frame 22, the first backboard 7-3, the long support columns 7-4, the short support columns 7-5 and the second backboard 7-6;
The optical detection unit includes: the first photodetector 19-1 and the second photodetector 19-2 are used for receiving light beams in different states.
The laser driver 1 is separated from the laser emission cavity 2, the laser driver 1 and the laser emission cavity 2 are mounted close to the heat dissipation back plate 2-1 in a bolt connection mode, the radiator is close to the other surface of the heat dissipation back plate 2-1 in a bolt connection mode, and heat generated by the laser driver 1 and the laser emission cavity 2 can be directly transferred to the radiating fin 23;
The fixed reflector mounting frame 4-1 and the adjustable reflector mounting frame 5-2 are mounted with the reflector mounting plate 4-2 in a bolt connection mode, and the reflector mounting plate 4-2 is mounted on the heat dissipation backboard 2-1 in a bolt connection mode; the fixed reflector 4 is directly stuck on the fixed reflector mounting frame 4-1 through epoxy glue, the first adjustable reflector 5 is directly stuck on the adjustable reflector mounting frame 5-1 through epoxy glue, the adjustable reflector mounting frame 5-1 is connected with the adjustable reflector mounting frame 5-2 through three adjusting screws 5-4, and three pre-tightening springs 5-3 are pressed on the three adjusting screws 5-4, so that the aim of adjusting the angle of the first adjustable reflector 5 can be achieved by rotating the adjusting screws 5-4 at different positions, and the aim of aligning the optical axis of the emergent laser 3 with the optical axis of the beam expander 7 can be achieved;
the laser driver 1 generates laser, the laser emission cavity 2 emits outgoing laser 3, the outgoing laser 3 is reflected by the fixed reflector 4 and then reflected by the first adjustable reflector 5, and enters the beam expansion collimation unit.
The half-wave plate 6 is directly stuck on the half-wave plate mounting ring 6-1 through epoxy glue, fine threads are arranged on the half-wave plate mounting ring 6-1, the half-wave plate can be screwed into the half-wave plate fixing frame 6-2, and the angle can be adjusted through thread rotation; the half-wave plate fixing frame 6-2 is arranged with the reflecting component mounting plate 4-2 in a bolt connection mode; the beam expander 7 is fastened on the beam expander mounting frame 7-1, and the beam expander mounting frame 7-1 is fixedly arranged on the heat dissipation backboard 2-1 in a bolt connection mode;
The second adjustable reflector 8 is directly stuck on the large reflector mounting frame 8-1 through epoxy glue, the large reflector mounting frame 8-1 is connected with the large reflector mounting frame 8-2 through three large adjusting screws 8-3, the large reflector mounting frame 8-2 is connected with the second backboard 7-6 through threads, and the second backboard 7-6 is connected with the first backboard 7-3 through four short support posts 7-5 through threads; the first backboard 7-3 is connected with the main support frame 22 through four long support columns 7-4 in a threaded manner; the two ends of the heat dissipation backboard 2-1 are respectively connected with the first backboard 7-3 and the main support frame 22 through bolts, so that the whole machine forms a closed structure, and the strength and the stability are improved; the mounting block 7-2 and the circuit board assembly 24 are fixedly mounted on the main support frame 22;
The emergent laser 3 enters a beam expander 7 after passing through a half-wave plate 6; the beam diameter becomes larger after passing through the beam expander 7, and the beam divergence angle becomes smaller; the outgoing laser 3 is emitted from the beam expander 7, reflected by the second tunable mirror 8, reflected by the large fixed mirror 9, and then emitted into the atmosphere.
The back scattered light 10 generated by the laser incident into the atmosphere encountering aerosol particles is reflected by the card-type main mirror 12 and then reflected by the card-type secondary mirror 11 to be converged into a focus, and a diaphragm 13 is arranged at the focus position and used for shielding stray light; the diaphragm 13 is connected with the Cassegrain telescope 20 through a bolt, and the backward scattered light 10 passing through the diaphragm 13 is changed into parallel light through the collimating lens 14, is reflected by the sub-light path reflector 15, passes through the dichroic plate 16, passes through the narrow-band filter 17 and then enters the polarizing prism 18; the transmission band and reflection band of the dichroic plate 16 are set according to the laser wavelength, here, the transmission band is 532nm wavelength laser, and the back scattered light 10 passing through the polarizing prism 18 becomes two light beams with different polarization states, one of which is received by the first optical detector 19-1 and the other of which is received by the second optical detector 19-2.
The support assembly further comprises four auxiliary support blocks 25; the Cassegrain telescope 20 is connected with a telescope mounting plate 21 through bolts, and the telescope mounting plate 21 is connected with a main support frame 22 through bolts; four auxiliary supporting blocks 25 are arranged on the first backboard 7-3, the Cassegrain telescope 20 passes through the hollowed-out part of the first backboard 7-3 and is clamped by the auxiliary supporting blocks 25 which are tightly attached, and the auxiliary supporting blocks 25 provide auxiliary support for the Cassegrain telescope 20.
Example 2
An optical axis calibration method (schematic diagram is shown in fig. 6) of a Mie scattering laser radar is used for adjusting the Mie scattering laser radar to enable the optical axes of transmitting and receiving to be coaxial, and specifically comprises the following steps:
s1, a point light source 26 is temporarily added behind a diaphragm 13, and in order to ensure the optical quality of the point light source 26 is required to be close to the diaphragm 13 as much as possible;
S2, arranging a collimator on the opposite side of the whole meter scattering laser radar, and arranging a CCD camera 28 (CCD is charge coupled device is called as charge coupled device) at the receiving end of the collimator; the light of the point light source 26 is reversely incident into the collimator 27 through the Cassegrain telescope 20, and the point light source 26 can present a small light spot 28-1 on the CCD camera 28;
S3, the laser driver 1 is turned on, after the emitted laser passes through the collimator 27, a large light spot 28-2 is displayed on the target surface of the CCD camera, and the coaxial state of the two light spots can be known by reading the pixel points of the CCD camera 28;
S4, adjusting the angles of the outgoing lasers by adjusting three large adjusting screws 8-3, so that a large light spot 28-2 of the outgoing lasers on the CCD camera 28 and a small light spot 28-1 of the point light source 26 on the CCD camera 28 are concentric; at this time, the optical axes of the transmission and the reception are considered to be coaxial, and the optical axis calibration is completed.
It should be appreciated that various forms of the flows shown above may be used to reorder, add, or delete steps. For example, the steps described in the present disclosure may be performed in parallel, sequentially, or in a different order, provided that the desired results of the technical solutions of the present disclosure are achieved, and are not limited herein.
The above embodiments do not limit the scope of the present invention. It will be apparent to those skilled in the art that various modifications, combinations, sub-combinations and alternatives are possible, depending on design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of the present invention.