CN113484845B - Unmanned aerial vehicle-oriented light and small off-axis four-reflection type laser radar optical receiving device - Google Patents
Unmanned aerial vehicle-oriented light and small off-axis four-reflection type laser radar optical receiving device Download PDFInfo
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- CN113484845B CN113484845B CN202110562515.0A CN202110562515A CN113484845B CN 113484845 B CN113484845 B CN 113484845B CN 202110562515 A CN202110562515 A CN 202110562515A CN 113484845 B CN113484845 B CN 113484845B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
- G01S7/481—Constructional features, e.g. arrangements of optical elements
- G01S7/4816—Constructional features, e.g. arrangements of optical elements of receivers alone
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- Radar, Positioning & Navigation (AREA)
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- Optical Radar Systems And Details Thereof (AREA)
Abstract
The invention discloses a light small off-axis four-reflection type laser radar optical receiving device facing an unmanned aerial vehicle. The receiving device mainly faces to a laser radar (LiDAR) for measuring water depth and comprises an off-axis four-reflection type receiving light path objective lens, a deep water signal channel eyepiece with a single-lens structure, a shallow water signal channel eyepiece with a Huygens structure and a water surface signal channel eyepiece with the Huygens structure. The receiving device has the advantages that the main optical aperture D =22mm, F #10, the receiving field angle is better than 50mrad, the effective focal length f' =220mm, and the receiving device is a laser radar receiving device which is medium in field view, small in relative aperture, small in size, light in weight, high in optical transmittance and capable of being hung on an unmanned aerial vehicle.
Description
Technical Field
The invention relates to the field of laser radars, in particular to a light, small, medium and relative aperture water depth measurement laser radar optical receiving device for an unmanned aerial vehicle.
Technical Field
At present, as for an unmanned airborne laser radar for bathymetry, the optical receiving device has the following defects: 1. most of them are transmissive systems, and their optical transmittance is low. For example, CN201610821346.7 is a laser radar optical receiving device and a laser radar ranging method. Further, patent CN110764073A discloses a laser radar lens, which is a high resolution lens, but the excessive number of lenses makes the thickness of the optical receiving device too large, resulting in low optical receiving efficiency. 2. Laser radar main optical aperture is mostly medium aperture in the medium field of view, and is bulky, and weight is heavy, is not fit for unmanned aerial vehicle carry. Such as a laser radar optical receiving device of CN201410177032.9 and a laser radar optical receiving device of CN 201621054857.2.
Aiming at the defects of the laser radar optical receiving device for measuring the water depth, the invention provides a light small off-axis four-reflection type laser radar optical receiving device facing an unmanned aerial vehicle, which comprises an off-axis four-reflection type optical receiving objective lens and an eyepiece with a reasonable structure. The device D =22mm, F #10, the receiving field angle is better than 50mrad, and the effective focal length f' =220mm.
Disclosure of Invention
The invention discloses a light small off-axis four-reflection type laser radar optical receiving device facing an unmanned aerial vehicle.
The invention is realized by adopting the following technical scheme: the objective lens adopts an off-axis four-reflection type objective lens, wherein the curvature radius of a primary mirror is R 1 The radius of curvature of the secondary mirror is R 2 Third mirror radius of curvature R 3 = infinity, fourth mirror radius of curvature R 4 . The main mirror, the auxiliary mirror and the fourth mirror are used for adjusting light, and the third mirror is used for rotating images, so that the image surface is parallel to the main optical axis. The distance from the vertex of the primary mirror to the vertex of the secondary mirror is d 1 The distance from the vertex of the secondary mirror to the vertex of the third mirror is d 2 The distance from the vertex of the third mirror to the vertex of the fourth mirror is d 3 . The distance between the fourth lens and the first surface of the eyepiece lens is d 4 。
In addition, at the focal plane of the receiving lens, a field stop is placed for separating the deep water signal, the shallow water signal and the water surface signal. The field diaphragm is a reflector with an opening at the center of one surface and the diameter of the reflecting area is D 1 The diameter of the opening area is D 2 . The reflection area reflects the deep water signal to enable the deep water signal to enter the deep water signal channel. The open pore area passes through the shallow water and water surface signals, so that the signals enter a common signal channel of the shallow water and the water surface. The deep water signal channel adopts a single-chip aspheric convex flat lens, and the convex curvature radius of the lens is R 5 (ii) a The shallow water signal channel adopts Huygens eyepiece, and the curvature radius of two convex surfaces of the eyepiece is R respectively 6 、R 7 Distance between two ocular lenses is d 5 (ii) a The water surface signal channel adopts a Huygens eyepiece, and the curvature radiuses of two convex surfaces of the eyepiece are R respectively 7 、R 8 The distance between two eyepieces being d 6 。
The invention has the following beneficial effects: by adopting the small-aperture length Jiao Lizhou four-reflection type objective lens, the receiving efficiency of the laser radar for water depth measurement is improved, the maximum depth measurement capability of the laser radar is improved, and meanwhile the miniaturization of the laser radar for water depth measurement can be realized.
Drawings
FIG. 1 is a schematic view of an optical receiving device
FIG. 2 is a schematic view of an objective lens of an optical receiving device
FIG. 3 is a schematic view of the overall optical path structure of the optical receiving device
FIG. 4 is a schematic view of an MTF curve of an objective lens of an optical receiving device
Detailed Description
The following further describes the embodiments of the present invention with reference to the drawings.
Referring to fig. 1, a schematic structural diagram of an optical receiving device according to the present invention is illustrated. a is an objective lens comprising 1 Being the primary mirror of an objective lens, a 2 Secondary mirror being an objective lens, a 3 A third mirror being an objective lens, a 4 The fourth mirror being the objective lens. b is a high peak power pulse laser, c is a motor scanning system, d is a power supply device and a servo motor driving circuit, e is a photoelectric detector, f is a sampling circuit, h 1 Is a deep water signal channel ocular lens h 2 Is a shallow water signal channel ocular lens h 3 Is a water surface signal channel ocular lens.
Referring to fig. 2, the optical path structure of the integral receiving apparatus of the present invention is described, wherein the deep water signal channel employs a telescopic receiving system, and the shallow water signal channel employs a focusing telescopic receiving system. The deep water signal channel is received by a PMT type detector, and the shallow water signal channel and the water surface signal channel are received by an APD type detector.
Referring to fig. 3, a schematic view of an objective lens of an optical receiving device according to the present invention is illustrated, which reflects the propagation relationship of light in the objective lens. Let beta 1 Is a secondary mirror magnification, beta 2 Is third mirror magnification, beta 3 For fourth lens power, the radii of curvature of the respective lenses should satisfy the following relationship:
the objective lens pitch should satisfy the following relationship:
the off-axis angle of the third mirror is 73.866 degrees, and the off-axis amount of the auxiliary mirror is 12.5mm.
With reference to fig. 4, it is demonstrated that the MTF values of the present invention are all greater than 0.4 at a spatial frequency of 80lp/mm, and the deep and shallow water signals can be well distinguished.
With reference to fig. 1 and fig. 2, the operation of the light, small, off-axis, four-reflection type lidar optical receiving apparatus facing the unmanned aerial vehicle is described as follows:
(1) And b, the high peak power pulse laser emits a laser signal to the reflector, the laser signal is reflected to the c motor scanning system, and then the laser signal enters the water body through the air and the water surface, reaches the water bottom and is reflected back.
(2) The reflected laser echo signal is a 1 Reflected by the primary mirror to a 2 Secondary mirror, re-reflected to a 3 A third mirror, reflecting to a 4 Fourth mirror, finally reflecting to g 1 First diaphragm, deep water echo signal is reflected to h 1 Deep water signal channel, shallow water and water surface signal transmission g 1 First diaphragm reaches g 2 Second diaphragm, shallow water echo signal reflected to h 2 Shallow water signal channel, water surface echo signal transmission g 2 Second diaphragm reaches h 3 A water surface signal channel.
(3) Into h 1 、h 2 And h 3 The laser echo signals are respectively received and processed by PMT, APD and APD detectors, then transmitted to an f sampling circuit, and finally the sampled digital signals are stored.
While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (1)
1. The light and small off-axis four-reflection type laser radar optical receiving device facing the unmanned aerial vehicle is characterized by comprising a power supply device, a high peak power pulse laser, a servo motor driving circuit, a motor scanning system, a receiving light path objective lens, a deep water signal channel eyepiece, a shallow water signal channel eyepiece, a water surface signal channel eyepiece, a photoelectric detector and a sampling circuit; the receiving light path objective is an off-axis four-reflection type objective and comprises a main mirror, an auxiliary mirror, a third mirror and a fourth mirror, wherein the main mirror, the auxiliary mirror and the fourth mirror are used for adjusting light, and the third mirror is used for rotating images so that image surfaces are parallel to a main optical axis; the off-axis quantity of the secondary mirror is 12.5mm, the off-axis quantity of the primary mirror is 35mm, and the third off-axis angle is 73.866 degrees; radius of curvature of primary mirror R 1 The radius of curvature of the secondary mirror is R 2 Third mirror radius of curvature R 3 = ∞ radius of curvature of fourth mirror R 4 (ii) a The distance from the vertex of the primary mirror to the vertex of the secondary mirror is d 1 The distance from the vertex of the secondary mirror to the vertex of the third mirror is d 2 The distance from the vertex of the third mirror to the vertex of the fourth mirror is d 3 (ii) a The distance between the fourth lens and the first surface of the eyepiece lens is d 4 (ii) a The radii of curvature of the individual lenses should satisfy the following relationship:
the objective lens pitch should satisfy the following relationship:
d =22mm, F #10, the receiving field angle is better than 50mrad, and the effective focal length f' =220mm; the deep water signal channel eyepiece adopts a single aspheric convex plano mirror, the shallow water signal channel eyepiece and the water surface signal channel eyepiece adopt Huygens eyepieces, the first diaphragm reflects a deep water laser echo signal to the deep water signal channel, the second diaphragm reflects a shallow water laser echo signal to the shallow water signal channel, and the second diaphragm transmits a water surface laser echo signal to the water surface signal channel; at the spatial frequency of 80lp/mm, the MTF values are all larger than 0.4, so that deep and shallow water signals can be well distinguished; the deep water signal channel, the shallow water signal channel and the water surface signal channel respectively adopt PMT, APD and APD detectors to detect laser echo signals; an eyepiece lens group is fixed on an optical platform of the bottom plate by a lens bracket; the working process is as follows:
(1) The high-peak power pulse laser emits a laser signal to the reflector, reflects the laser signal to the motor scanning system, and then the laser signal enters the water body through the air and the water surface, reaches the water bottom and reflects the laser signal back;
(2) The reflected laser echo signal is reflected to the secondary mirror by the primary mirror, then reflected to the third mirror, then reflected to the fourth mirror, and finally reflected to the first diaphragm, the deep-water echo signal is reflected to the deep-water signal channel, the shallow water and water surface signal reach the second diaphragm through the first diaphragm, the shallow water echo signal is reflected to the shallow water signal channel, and the water surface echo signal reaches the water surface signal channel through the second diaphragm;
(3) Laser echo signals entering the deep water signal channel, the shallow water signal channel and the water surface signal channel are received and processed by the PMT, the APD and the APD detectors respectively, then transmitted to the sampling circuit, and finally sampled digital signals are stored.
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Citations (2)
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| CN103293666A (en) * | 2013-06-09 | 2013-09-11 | 北京理工大学 | Coaxial four-mirror auto-zooming optical system with spherical secondary mirror |
| CN105511075A (en) * | 2016-01-13 | 2016-04-20 | 中国科学院上海技术物理研究所 | Two-dimensional image motion compensation optical system for large-field-of-view whisk-broom double-channel imager |
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| US8334490B2 (en) * | 2009-10-14 | 2012-12-18 | Raytheon Company | Off-axis reflective transmit telescope for a directed infrared countermeasures (DIRCM) system |
| CN101672978A (en) * | 2009-10-16 | 2010-03-17 | 中国科学院上海技术物理研究所 | Catadioptric type off-axis three-reflector long-wave infrared optical system |
| CN110542893A (en) * | 2019-09-05 | 2019-12-06 | 桂林理工大学 | Airborne double-frequency laser radar three-channel optical receiving device |
| CN212134938U (en) * | 2020-03-16 | 2020-12-11 | 安徽蓝科信息科技有限公司 | Laser radar receiving device |
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|---|---|---|---|---|
| CN103293666A (en) * | 2013-06-09 | 2013-09-11 | 北京理工大学 | Coaxial four-mirror auto-zooming optical system with spherical secondary mirror |
| CN105511075A (en) * | 2016-01-13 | 2016-04-20 | 中国科学院上海技术物理研究所 | Two-dimensional image motion compensation optical system for large-field-of-view whisk-broom double-channel imager |
Non-Patent Citations (3)
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| Error analysis and design of the optical system in airborne remote sensing measurement;Lv Chao,et al;《The International Conference on Photonics and Optical Engineering》;20141231;p1-9 * |
| 用于对地观测小卫星的同轴四反光学系统设计;任秉文等;《中国空间科学学会2013年空间光学与机电技术研讨会》;20131231;第117-122页 * |
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