激光雷达成像技术PPT参考课件.ppt

航天学院,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,单击此处编辑母版标题样式,激光雷达成像技术（,3,）,成像技术要点,距离测量技术,直接飞行时间“,Direct Time-of-Flight(TOF)”,连续波振幅调制的相位“,Phase-Based AM-CW”,连续波振幅啁啾调制“,Chirped AM-CW“,连续波频率啁啾调制“,Frequency chirp(FM-CW)”,成像方式,扫描成像（,X-Y,扫描、线扫描、,MEMS,或,DMD,扫描）,FLASH,成像（焦平面成像）,条纹相机成像,距离选通成像,相控阵成像,合成孔径成像,激光雷达常见的性能指标,最大辐射功率,水平视场“,horizontal Field of View(FOV)”,垂直视场“,vertical FOV”,光源波长“,Wavelength of optical source”,最远测量距离“,Maximum distance to be measured”,测量时间,/,帧频“,Measurement time/frame rate”,纵向分辨率“,depth resolution“,角分辨率“,angular resolution”,测距精度“,Range Measurement accuracy”,脉冲飞行时间测量法（,1,）,图,-1,纯脉冲飞行时间物理过程,连续波幅度调制相位测量法,图,-2,飞行时间决定相位的物理过程,相位差与距离关系,模糊距离,信噪比与测距精度,举例,1,连续波啁啾幅度调制测量法,F-,调制深度,T-,调制周期,f,if,-,中频,啁啾调制信号与中频信号图示,Block diagram for an experimental single channel(2-D)chirped-AM/cw LADAR,连续波频率啁啾调制测量法,Frequency chirp(FM-CW)used in the Metric Vision MV-200 coherent Ladar.,相干激光雷达距离精度,外差等效噪声功率,heterodyne noise equivalent power(NEP),信噪比,signal-to-noise ratio(SNR),散焦损耗,defocusing loss,外差探测信噪比受相干长度影响。对于洛伦兹型光源线宽,:,考虑散焦和相干长度等因素，其效噪比,SNR,表示为,including the losses due to the defocusing and coherence,the equation becomes:,啁啾激光雷达,1,个正弦信号测距精度,距离精度,range accuracy,Typical parameters for the Metric Vision MV-200 CLR,Theoretical Range Accuracies for Different Targets for the sensor as described,扫描成像,平行光束扫描,会聚光束扫描,V,高度,H(m),的飞行速度；,N=m,n,探测器单元数量；,d,res,探测器面元尺寸,脉冲重复频率,f,r,：,其中：,N(m,n),-,像素；,F-,帧频,总的扫描时间：,其中：,tot,-,总扫描角；,tot,-,光束发散角；,T,dwell,=1/,f,r,-,光束滞留时间,飞行时扫描频率：,扫描时脉冲积累数：,其中：,B,-,天线,3dB,光束宽度,(deg);f,r,-,重频；,m,-天线每分转数,瞄准误差与滞后角效应：,其中：,-,滞后角；,d/dt-,扫描速率；,-,往返时间；,r-,到目标距离；,c-,光速；,n-,传播介质平均折射率,Model 6400 Moving Coil Capacitive Position Detector Optical Scanner,Preliminary Specs,PE100011,PF210012,PE200012,PE210012,Scan speed(fast axis),10 kHz,21 kHz,20kHz,21 kHz,Scan speed(slow axis),1.15 kHz,1.2 kHz,1.2 kHz,12 kHz,Mirror plate size,1.2 mm Circular,0.9 mm Circular,1.0 mm Circular,1.0 mm Circular,Optical scanning angle,15,o,/12,o,15,o,/15,o,15,o,/15,o,15,o,/15,o,Scan trajectory(fast axis),sinusoidal,sinusoidal,sinusoidal,sinusoidal,Scan trajectory(slow axis),sinusoidal,sinusoidal,sinusoidal,sinusoidal,Scan jitter,0.1%,0.1%,0.1%,80%450650nm,80%450650nm,80%450650nm,80%450650nm,Mirror flatness,l,/8 635nm,l,/8 635nm,l,/8 635nm,l,/8 635nm,Operating temperature,0,o,60,o,C,0,o,60,o,C,0,o,60,o,C,0,o,60,o,C,Operating humidity,10%85%,10%85%,10%85%,10%85%,Acoustic noise,30dB,30dB,30dB,30dB,Driving principle,electrostatic,electrostatic,electrostatic,electrostatic,Power consumption,40 mW,100 mW,100 mW,100 mW,Package footprint,10 x10 mm,2,8x8 mm,2,8x8 mm,2,8x8 mm,2,Package,PLCC,PLCC,PLCC,PLCC,Status,Engineering sample,Engineering sample,Engineering sample,Engineering sample,先進微系統科技,(,股,),公司,2D-MEMS,Opus Microsystems Corp.Taipei,Taiwan,2D MEMS,mirrorcletech,4.2,4.2mm,0.7,0.7mm2.0,2.2mm,No,Mirror Model No,Mirror Diameter,(mm),Frequency,(Hz),Opt.Scan angle,(,),Max.Voltage,(V),1,S0103,0.8,10552/,10874,6.1954,2,S0264,1.2,2017/1987,7.2186,127,3,S0394,2.0,935/907,7.4309,134,4,S0233,2.4,623/629,7.1093,134,5,S0273,3.4,531/529,7.6862,140,The Sick LMS 200 laser scanner,Implementation of a Risley prism scanner for an FPA staring array LADAR.,Maximum range,3-5 km,Range resolution,10 mm,Range accuracy at 50 m,5 cm,FOV(Field of View),20,x 20,Laser beam divergence,500,rad,Data rate,8-10 kpoints/s,Instrument mass,power,volume,10 kg,70 W,13 L,Laser(eye-safety),Class 3B,Data output,Range,bearing,centroid,Micro electro-mechanical system(MEMS),距离选通激光成像雷达,Burst illuminations Ladar(BIL),距离选通激光成像雷达,激光测距仪,+,扫描仪,+,数字相机,距离范围：,3800m,距离分辨率：厘米量级,波长：,1.5,m,热像仪图像,BIL,图像,闪烁式激光成像雷达,机载激光成像雷达,测距方式,:TOF,面阵探测器：给出目标的角度和距离,盖革模式雪崩二极管,(GM-APD),是其核心技术,Jigsaw image of helicopter,参数,数值,注释,标定距离,150m,视场角,10.8,在距离,150m,处直径为,28.3m,波长,532nm,激光远场光束图样,32,32,点阵,按探测器瞬时视场点阵排列,激光脉宽,300ps,半宽度,激光脉冲和成像速率,16000/s,接收孔径,7.5cm,有效焦距,300mm,F,数,f/4.0,焦平面像素,32,32,纵向设计,100,m,像素,333,rad,瞬时斜距采样,在,150m,处为,5cm,7.5m,FPA,采样率,2GHz,500GHz,瞬时视场,10.1,10.1mrad在,150m,处为,1.5m,正方形,2003,年,6,月该,Jigsaw,系统装在,UH-1,直升机上进行了飞行实验,隐蔽在树林中带伪装网的坦克目标,飞行实验中获取的坦克目标的伪彩色,3D,激光雷达图像处理过程显示,APD,的工作模式,线性模式,工作电压接近并小于雪崩电压时，,M,到,1000,左右就会饱和，这样的倍增还不足以探测到单光子信号；,盖革模式,工作偏压大于雪崩电压时，光子信号,APD,吸收，并使,APD,迅速雪崩，同时采用一定的抑制电路（无源抑制、有源抑制和主动门抑制），迅速切断雪崩，使,APD,恢复到接收光子的状态。,盖革模式淬灭电路,被动淬灭,主动淬灭,GM-APD:,光子/,数字转换,Digitally encodedphoton arrival time,photon,APD,单元,Digital,timing,circuit,Lenslet,array,APD array,焦平面,CMOS array,APD/CMOS,时间记录阵列,Silicon APDs for,0.9,m,20-50%,探测效率,10-kHz,暗光子技术率,桥接,CMOS,计时,InGaAsP/InP APDs for,1,1.5,m,20-50%,探测效率,10-kHz,暗光子技术率,TE-cooling(1,m),桥接,CMOS,计时,CMOS,计时电路,t,250-500-ps,时间分辨率,500 MHz and 1-GHz,时钟,100-,m,m,Bridge-Bonded Si APDs,Bump-Bonded InGaAsP APDs,32x32 Array,Silicon(Visible),InGaAs(1-,m),32 x 128 Array,GM-APD,阵列,CMOS,计时电路,技术优势,:,极高的灵敏度,(,单光子,),极高的距离分辨率,(10 cm),高度集成化,距离像数字化输出,可升级大尺寸面阵,光子技术阵列也可用于相干探测（引入本振光子时）,使用,GM-APD,进行相干探测的优势,:,两种模式激光雷达,探测器阵列工作在近量子极限,可使用大尺度面阵探测器,GM-APD,相干激光成像雷达,Signal,Photons,Signal,Photons,LO,Photons,直接探测,相干探测,低光子通量下的干扰,Spatial:,双狭缝实验,Temporal:,外差探测,高光通量,低光通量,distance x,time,distance x,Intensity,Counts,Intensity,Counts,time,Laser,2,Laser,1,Detector,f,f+,f,1/,f,高光通量,低光通量,工作原理,LO,快门系统在直接探测,/,相干探测之间转换,CW,主振荡器和放大器调节产生某一波形,两个面阵探测器（水平和垂直偏振方向）,Master Oscillator,Amplitude,Modulator,Amplifier/,Isolator,Stages,Waveform Synthesizer,LO Shutter,Amplitude,Modulator,APD Arrays,经典相干探测描述,Laser source,AOM,Frequency reference,m,mixing efficiency,Phase,frequency-shifte,经典相干探测,:CNR,如果本振光产生的噪声远远大于其它噪声,则,CNR,主要由信号回波的散粒噪声决定，即：,GM APD,相干探测,:CNR,尽管,CNR,降低,3-dB,，但有如下好处：,单个探测器即可直接探测亦可相干探测，简化成双模系统,本振光功率,:,仍为传统相干探测水平，,mW,两级,/,每个单元,可以适用于大面阵探测器,GM-APD,与传统相干探测相比由于散粒噪声极限的作用使载噪比,CNR,降低一半,GM-APD,信号光和本振光光子探测,Luu and Jiang(Appl.Optics 45,3798)developed expression for CNR in presence of saturation(N,P,=total number of photon“buckets”available),Saturated,Next photon likely to hit dead pixel,Increasing LO or return power,Macropixel,Next photon likely to hit free pixel,Individual APDs,Focal Plane,GM-APD,相干探测数据处理方法,Collection of GM APDs acts as a single coherent detector,Histogram of arrival times gives intensity vs time,FFT or digitally mix with i.f.to obtain frequency/phase,Time resolution of clock(2 GHz)determines bandwidth,AOM,Frequency reference,Laser source,Arrival times,Histogram of arrival times,Power spectral density,Signal Processing,Early Hit,Late Hit,No Hit,CNR,结果比较,Number of return photoelectrons,Coherent CNR(dB),CNR,Array Filled,CNR,与理论值比较,-20,-10,0,10,20,30,1,10,100,1000,Number of return photoelectrons,Coherent CNR(dB),Array Filled,Saturating-pixel theory,nonuniform illumination,Detector intensity image,N,P,DCR=175 kHz/pixel,m=0.4,Saturating-pixel theory,uniform illumination,本振光功率增加效应,Number of return photons,在未饱和区域增加本振光功率可以得到,3 dB的好处,最佳本振光功率由信号回波和探测器单元参数确定,CNR(dB),Number of local oscillator photons,CNR/Shot noise limit,10 Return,photons,50 Return,photons,200 Return,photons,400 Return,photons,1024-pixel array,Shot noise limit(,mN,R,),P,LO,=P,R,P,LO,optimized,3 dB,条纹管激光成像雷达,2000,年美国空军实验室和美国国家海洋管理,(NOAA),提出条纹管成象激光雷达,(Streak Tube Imaging LIDAR,STIL),条纹管激光成像雷达原理,距离方位取样,未经处理的强度,-,距离,-,方位图像（,1,帧）,重构后的强度图像,重构后的距离像,圆球和圆形,（强度,-,距离,-,方位）条纹图,