M. Harris, R. Loudon, J. W. H. Perry, T. Shepherd, J. Vaughan
Optimum alignment of a coherent lidar is notoriously difficult to achieve1, particularly in compact systems designed for field operation. The correct spatial overlap and wavefront matching of signal and local oscillator beams can be especially time-consuming in systems at non-visible wavelengths (eg CO2). Several authors have suggested re-injection of the signal into the laser oscillator to achieve automatic alignment2-4.
{"title":"An Automatically Aligned Lidar System","authors":"M. Harris, R. Loudon, J. W. H. Perry, T. Shepherd, J. Vaughan","doi":"10.1364/clr.1991.md5","DOIUrl":"https://doi.org/10.1364/clr.1991.md5","url":null,"abstract":"Optimum alignment of a coherent lidar is notoriously difficult to achieve1, particularly in compact systems designed for field operation. The correct spatial overlap and wavefront matching of signal and local oscillator beams can be especially time-consuming in systems at non-visible wavelengths (eg CO2). Several authors have suggested re-injection of the signal into the laser oscillator to achieve automatic alignment2-4.","PeriodicalId":152434,"journal":{"name":"Coherent Laser Radar: Technology and Applications","volume":"118 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115165261","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Global Backscatter Experiment (GLOBE) was intended to provide data on prevailing values of atmospheric backscatter cross section. The primary intent was predicting the performance of space borne lidar systems, most notably the Laser Atmospheric Wind Sounder (LAWS) for EOS. A second and related goal was to understand the source and characteristics of atmospheric aerosol particles. For remote ocean locations, and the Southern hemisphere in general, a significant lack of knowledge exists. The major components of the experiment were flight surveys throughout the Pacific region by the NASA DC-8 aircraft. A lidar system was operated on the missions to obtain aerosol backscatter cross section at the fundamental and doubled Nd:YAG laser wavelengths of 1.064 an 0.532 µm and, in addition, at a wavelength of 1.54 µm. The system was the first operational lidar at the one-and-a-half micron wavelength region. Coherent doppler lidar at near IR wavelengths is currently under development. Advantages of one-and-a-half micron lidar is eye safe operation and increased sensitivity to aerosol characteristics. The GLOBE flights were carried out in November 1989 and May-June 1990. In this paper we will discuss measurement techniques and initial results.
{"title":"Aerosol Backscatter at 1.06, 0.53 and 1.54 µM","authors":"J. Spinhirne","doi":"10.1364/clr.1991.fa3","DOIUrl":"https://doi.org/10.1364/clr.1991.fa3","url":null,"abstract":"The Global Backscatter Experiment (GLOBE) was intended to provide data on prevailing values of atmospheric backscatter cross section. The primary intent was predicting the performance of space borne lidar systems, most notably the Laser Atmospheric Wind Sounder (LAWS) for EOS. A second and related goal was to understand the source and characteristics of atmospheric aerosol particles. For remote ocean locations, and the Southern hemisphere in general, a significant lack of knowledge exists. The major components of the experiment were flight surveys throughout the Pacific region by the NASA DC-8 aircraft. A lidar system was operated on the missions to obtain aerosol backscatter cross section at the fundamental and doubled Nd:YAG laser wavelengths of 1.064 an 0.532 µm and, in addition, at a wavelength of 1.54 µm. The system was the first operational lidar at the one-and-a-half micron wavelength region. Coherent doppler lidar at near IR wavelengths is currently under development. Advantages of one-and-a-half micron lidar is eye safe operation and increased sensitivity to aerosol characteristics. The GLOBE flights were carried out in November 1989 and May-June 1990. In this paper we will discuss measurement techniques and initial results.","PeriodicalId":152434,"journal":{"name":"Coherent Laser Radar: Technology and Applications","volume":"77 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115712431","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In all laser radar systems the detector is an essential part that can influence the performance of the system to a great extent. It is therefore necessary to study the detector characteristics in order to determine the effect of the detector on the overall performance of the laser radar system.
{"title":"Performance studies on a HgCdTe detector for heterodyne systems","authors":"D. Letalick, Ingmar Renhom","doi":"10.1364/clr.1991.me2","DOIUrl":"https://doi.org/10.1364/clr.1991.me2","url":null,"abstract":"In all laser radar systems the detector is an essential part that can influence the performance of the system to a great extent. It is therefore necessary to study the detector characteristics in order to determine the effect of the detector on the overall performance of the laser radar system.","PeriodicalId":152434,"journal":{"name":"Coherent Laser Radar: Technology and Applications","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120938329","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Previous work1 produced a maximum likelihood (ML) estimator for the path-integrated concentration vector, CL, for a set of N materials measured using topographic or atmospheric backscatter differential absorption lidar (DIAL) with at least N+1 wavelengths. That analysis also showed that a Neyman-Pearson-based detection algorithm for the generalized DIAL measurement could be developed using a fixed-size sample of lidar data. Although adequate for many purposes, the Neyman-Pearson detection approach with fixed sampling does not fully exploit the time series aspect of most DIAL data collection. As a first step toward utilizing this aspect, it was shown2 that an adaptive Kalman filter could significantly improve the estimation of CL using a sequence of lidar measurements with little or no additional processing time. The question naturally arises as to whether a sequential approach could improve detection as well as estimation performance for a DIAL sensor.
{"title":"Sequential Detection of Multiple Materials Using Multiwavelength Lidar Time Series Data","authors":"S. Hannon, R. Warren","doi":"10.1364/clr.1991.thd8","DOIUrl":"https://doi.org/10.1364/clr.1991.thd8","url":null,"abstract":"Previous work1 produced a maximum likelihood (ML) estimator for the path-integrated concentration vector, CL, for a set of N materials measured using topographic or atmospheric backscatter differential absorption lidar (DIAL) with at least N+1 wavelengths. That analysis also showed that a Neyman-Pearson-based detection algorithm for the generalized DIAL measurement could be developed using a fixed-size sample of lidar data. Although adequate for many purposes, the Neyman-Pearson detection approach with fixed sampling does not fully exploit the time series aspect of most DIAL data collection. As a first step toward utilizing this aspect, it was shown2 that an adaptive Kalman filter could significantly improve the estimation of CL using a sequence of lidar measurements with little or no additional processing time. The question naturally arises as to whether a sequential approach could improve detection as well as estimation performance for a DIAL sensor.","PeriodicalId":152434,"journal":{"name":"Coherent Laser Radar: Technology and Applications","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127512980","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
CO2 lasers at wavelengths in the 10-μm region have been the main sources used in coherent laser radar system experiments, due in part to their ability to generate high, single-frequency output powers in both cw and pulsed operating modes. Improvements in the technology of solid state lasers have recently opened up the possibility that these devices can be used as alternatives to CO2-laser systems, providing more compact and reliable operation. Initial efforts have demonstrated coherent radar systems based on 1.06-μm-wavelength, Nd-doped and 2.1-μm-wavelength, Ho-doped lasers, with the latter devices favored in most cases because of the eye-safe operating wavelength. At present, the demonstrated output-power levels of solid state lasers, especially Ho-doped systems, fall well below those of CO2 lasers, and are not sufficient for challenging applications such as space-based atmospheric sensing. In this presentation we will describe some of our efforts to obtain better understanding of, and improvements in, solid state lasers for coherent laser radar.
{"title":"Solid State Lasers for Coherent Laser Radar","authors":"P. Moulton, Jere Harrison, J. Flint, D. Rines","doi":"10.1364/clr.1991.tua2","DOIUrl":"https://doi.org/10.1364/clr.1991.tua2","url":null,"abstract":"CO2 lasers at wavelengths in the 10-μm region have been the main sources used in coherent laser radar system experiments, due in part to their ability to generate high, single-frequency output powers in both cw and pulsed operating modes. Improvements in the technology of solid state lasers have recently opened up the possibility that these devices can be used as alternatives to CO2-laser systems, providing more compact and reliable operation. Initial efforts have demonstrated coherent radar systems based on 1.06-μm-wavelength, Nd-doped and 2.1-μm-wavelength, Ho-doped lasers, with the latter devices favored in most cases because of the eye-safe operating wavelength. At present, the demonstrated output-power levels of solid state lasers, especially Ho-doped systems, fall well below those of CO2 lasers, and are not sufficient for challenging applications such as space-based atmospheric sensing. In this presentation we will describe some of our efforts to obtain better understanding of, and improvements in, solid state lasers for coherent laser radar.","PeriodicalId":152434,"journal":{"name":"Coherent Laser Radar: Technology and Applications","volume":"69 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125955489","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The injected ion model Hg0.2Cd0.2Te photovoltaic deteotion is important element on CO2 coherent laser radar. The heterodyne quatum efficiency η(x,y) is important parameter for photovoltaic detection. The distribution function of the heterodyne quatum efficiency η(x,y) expreses homogemeity of photo-surface.
{"title":"Study on Homogeneity of Photosensitive Surface of The HgCdTe Photovoltaic Detector","authors":"Zhao Yuan, Dai Yongjiang, Yu Haipeng","doi":"10.1364/clr.1991.wd1","DOIUrl":"https://doi.org/10.1364/clr.1991.wd1","url":null,"abstract":"The injected ion model Hg0.2Cd0.2Te photovoltaic deteotion is important element on CO2 coherent laser radar. The heterodyne quatum efficiency η(x,y) is important parameter for photovoltaic detection. The distribution function of the heterodyne quatum efficiency η(x,y) expreses homogemeity of photo-surface.","PeriodicalId":152434,"journal":{"name":"Coherent Laser Radar: Technology and Applications","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130405535","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
It is essential that the transmitting laser of a coherent laser radar operate in single mode. In an unstable resonator, single transverse mode operation is determined by proper choice of physical cavity parameters. Single longitudinal mode operation can be achieved by seed injection and cavity matching. In this paper we present our results from our studies of CO2 laser seed injection using an unstable resonator for our oscillator and a single mode CW CO2 laser as the injection source.
{"title":"Parametric Study of Seed Injection into a CO2 Laser with an Unstable Resonator","authors":"D. Angeley, H. Chou, S. Ghoshroy","doi":"10.1364/clr.1991.ma3","DOIUrl":"https://doi.org/10.1364/clr.1991.ma3","url":null,"abstract":"It is essential that the transmitting laser of a coherent laser radar operate in single mode. In an unstable resonator, single transverse mode operation is determined by proper choice of physical cavity parameters. Single longitudinal mode operation can be achieved by seed injection and cavity matching. In this paper we present our results from our studies of CO2 laser seed injection using an unstable resonator for our oscillator and a single mode CW CO2 laser as the injection source.","PeriodicalId":152434,"journal":{"name":"Coherent Laser Radar: Technology and Applications","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114067926","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
One of the most important inputs to numerical weather forecasting, climatology etc., that is still lacking is a full global set of three-dimensional wind data. A Doppler lidar holds promise of being able to help rectify this deficiency by monitoring winds globally in cloud free areas.
{"title":"Representativity of a single line-of-sight wind component","authors":"C. Werner, J. Streicher, G. Wildgruber","doi":"10.1364/clr.1991.wd3","DOIUrl":"https://doi.org/10.1364/clr.1991.wd3","url":null,"abstract":"One of the most important inputs to numerical weather forecasting, climatology etc., that is still lacking is a full global set of three-dimensional wind data. A Doppler lidar holds promise of being able to help rectify this deficiency by monitoring winds globally in cloud free areas.","PeriodicalId":152434,"journal":{"name":"Coherent Laser Radar: Technology and Applications","volume":"387 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115912570","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Doppler detection schemes, effective at high frequency instabilities of laser sources are of great interest for lidar performance. The stability of ≈ 10−9 is required to realize ≈ ± 1 m/s accuracy of wind speed [1,2]. Doppler detection schemes on the intermediate frequency opera ting at stabilities of order of 10−7 ÷ 10−6 are described here, based on the so-called tracking heterodyne [3,4] and the proper lidar synchronization.
{"title":"Doppler Detection at High Instabilities of Laser Sources","authors":"D. Stoyanov, B. M. Bratanov, M. D. Angelova","doi":"10.1364/clr.1991.tha3","DOIUrl":"https://doi.org/10.1364/clr.1991.tha3","url":null,"abstract":"The Doppler detection schemes, effective at high frequency instabilities of laser sources are of great interest for lidar performance. The stability of ≈ 10−9 is required to realize ≈ ± 1 m/s accuracy of wind speed [1,2]. Doppler detection schemes on the intermediate frequency opera ting at stabilities of order of 10−7 ÷ 10−6 are described here, based on the so-called tracking heterodyne [3,4] and the proper lidar synchronization.","PeriodicalId":152434,"journal":{"name":"Coherent Laser Radar: Technology and Applications","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132215874","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The performance of coherent laser radar (CLR) is determined by the transmitter-receiver aperture and the geometry of the transmitter and Local Oscillator (LO) field. The detector is assumed to have uniform quantum efficiency η Q and collects all the energy of the LO beam. The detector noise is assumed to be dominated by LO shot noise.
{"title":"Atmospheric Refractive Turbulence and Coherent Laser Radar Performance","authors":"R. Frehlich","doi":"10.1364/clr.1991.tub3","DOIUrl":"https://doi.org/10.1364/clr.1991.tub3","url":null,"abstract":"The performance of coherent laser radar (CLR) is determined by the transmitter-receiver aperture and the geometry of the transmitter and Local Oscillator (LO) field. The detector is assumed to have uniform quantum efficiency η\u0000 Q\u0000 and collects all the energy of the LO beam. The detector noise is assumed to be dominated by LO shot noise.","PeriodicalId":152434,"journal":{"name":"Coherent Laser Radar: Technology and Applications","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130466890","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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