Infrared and Laser Engineering, Volume. 50, Issue 4, 20200297(2021)
Design of LiDAR optical machine system for airborne single frequency bathymetry
Figures & Tables(31)
Fig. 2. System structure of LiDAR. a-Integrated control unit; b-Power supply; c-532 nm laser; d-Motor driver; e-24V DC servo motor; f-Reflective wedge; g-Optical emission channel; h-Optical receiving channel; i-APD and its processing circuit; j-PMT and its processing circuit; k-Area array multispectral high resolution CCD camera; l-POS system
Fig. 4. Field loss factors corresponding to different water depths and receiving field of view
Fig. 5. Recognition factors for different water depths changing with field of view
Fig. 6. Recognition factor of 50 m water depth changing with field of view
Fig. 17. Schematic diagram of receiving and transmitting light system
Table 1. [in Chinese]
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Parts Parameter Value Laser Wavelength 532 nm Peak power 100 kW Pulse width 3 ns Repetition frequency 1 kHz Divergence angle 0.2 mrad Scanning unit Wedge angle 5º Wedge diameter 40 mm Wedge thickness 15 mm Angle between the bottom of wedge and vertical axis 45º Motor speed 540, 600 r/min Rated voltage of motor 24 V Rated power of motor 100 W Receiving Optical unit Receiving field angle 95 mrad Entrance pupil diameter 82 mm Exit pupil diameter 8 mm Magnification 10.25× and 42× Bandwidth ±1 nm Overall system Weight 25 kg Volume 1050 mm×400 mm× 460 mm Mode of delivery UAV Flight speed 0-10 m/s Flight height 150 m Run time 20 min Scanning width 52.9 m Scanning point density 1/m2 Best measuring depth 25 m Maximum measuring depth 50 m
Table 2. [in Chinese]
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Parameters Parameters name Parameters values Calculation formula(Parameters see column 1) θr Equivalent receiving FOV θr=θr0cosθa/(ncosθw) H Equivalent flight height 205.781 4 m H0=150 m H=H0n(cosθw/cosθa)3 h Water depth measurement 25 m m Scattering angle mean cosine function 8 bf Forward scattering coefficient 0.4 θw Angle between laser direction and vertical direction 6.74° θa=10° sinθa=nsinθw rr Equivalent radius 82.689 m m rr0=82 mm rr=rr0cosθw/cosθa rl Equivalent radius of laser beam cross section 3.054 m m rl0=3 mm rl=rl0cosθw/cosθa θl Equivalent laser divergence angle 0.1492 m rad θl0=0.2 mrad θl=θl0cosθa/(ncosθw) n Refractive 1.333
Table 3. [in Chinese]
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Value of qccoefficient Visibility range/km 1.6 V>50 1.3 10<V<50 0.16 V+0.34 0.5<V<10 0 V<0.5
Table 4. [in Chinese]
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Lens Radius of curvature/mm Focal length/mm Material Refractive index (532 nm) Distance Surface/mm 1 198.543 213.098 ZF14 1.9317 12 air→ZF14 2 600.383 644.395 ZF14 1.9317 111.411 ZF14→air 3 −353.382 −564.779 F2HT 1.6257 10 air→F2HT 4 156.494 250.110 F2HT 1.6257 36.799 F2HT→air 5 513.419 551.056 ZF14 1.9317 12 air→ZF14 6 −481.289 516.571 ZF14 1.9317 307.790 ZF14→air
Table 5. [in Chinese]
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Lens Radius of curvature/mm Focal length/mm Material/refractive (532 nm) Distance to next side/mm Surface 7 $\infty $ $\infty $ SF66/1.937 5 8 air→SF66 8 −135.530 144.565 SF66/1.937 5 19.907 SF66→air 9 48.617 51.858 SF66/1.937 5 7.990 air→SF66 10 92.216 −98.364 SF66/1.937 5 16.1 SF66→air 11 63.200 76.190 LASF14A/1.829 5 10 air→LASF14A 12 −316.269 −2 928.417 LASF14A/1.829 5 7.6 LASF14A→SF66 13 143.183 −152.728 SF66/1.937 5 17.172 SF66→air
Table 6. [in Chinese]
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Lens Radius of curvature/mm Focal length/mm Material / refractive (532 nm) Distance to next side/mm Surface 7 $\infty $ $\infty $ SF66/1.937 5 4 air→SF66 8 41.854 −44.644 SF66/1.937 5 30.426 SF66→air 9 52.443 55.939 SF66/1.937 5 4.5 air→SF66 10 −47.173 50.318 SF66/1.937 5 1 SF66→air 11 15.276 18.416 LASF14A/1.829 5 7.5 air→LASF14A 12 −22.175 −205.324 LASF14A/1.829 5 4 LASF14A→SF66 13 19.558 −20.862 SF66/1.937 5 10.053 SF66→air
Table 7. [in Chinese]
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Lens Optical transmittance Surface Objective 1 89.9% air→ZF14 Objective 2 89.9% ZF14→air Objective 3 94.32% air→F2HT Objective 4 94.32% F2HT→air Objective 5 89.9% air→ZF14 Objective 6 89.9% ZF14→air Eyepiece 7 89.8% air→SF66 Eyepiece 8 89.8% SF66→air Eyepiece 9 89.8% air→SF66 Eyepiece 10 89.8% SF66→air Eyepiece 11 91.41% air→LASF14A Eyepiece 12 99.9% LASF14A→SF66 Eyepiece 13 89.8% SF66→air
Table 8. [in Chinese]
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Component Weight/kg Power source 5 532 nm laser 3 80 flange servo motor 0.75 Motor driver 0.75 Optical pipeline 2.1(7 series aluminum) APD or PMT and its circuit 0.5 IMU 2.6 Integrated control system 3.5 CCD camera 0.35 Other 0.95 Outsourcing network 5 (PVC) Total 25
Table 9. [in Chinese]
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Component Volume/mm3 Power source 188×156×97.5 532 nm laser 104×104×166.5 80 flange servo motor 100×60×70 Motor driver 150×100×40 Optical pipeline 80(inside diameter)×660 IMU 200×116×80 Integrated control system 180×120×100 Outsourcing network 1 050×460×400
Table 10. [in Chinese]
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Plan Order number Flight speed/m·s−1 Flight height/m Scanning point density/m−2 Scanning width/m Distance/m Area/m2 1 a 6 100 2.42 35.26 36 1 269.36 b 8 100 2.07 35.26 48 1 692.48 c 10 100 1.81 35.26 60 2 137.20 2 a 6 150 1.29 52.89 36 1 904.04 b 8 150 1.14 52.89 48 2 538.72 c 10 150 1.02 52.89 60 3 173.40 3 a 6 200 0.81 70.53 36 2 539.08 b 8 200 0.73 70.53 48 3 385.44 c 10 200 0.66 70.53 60 4231.80
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Guoqing Zhou, Haocheng Hu, Jiasheng Xu, Xiang Zhou, Xueqin Nong. Design of LiDAR optical machine system for airborne single frequency bathymetry[J]. Infrared and Laser Engineering, 2021, 50(4): 20200297
Paper Information
Category: Lasers & Laser optics
Received: Dec. 15, 2020
Accepted: --
Published Online: Jul. 30, 2021
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