Unconventional Imaging and Adaptive Optics 2021最新文献

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Analysis of Aero-Optical Jitter in Boundary Layers Using the Stitching Method 用拼接法分析边界层中的气动光学抖动

Unconventional Imaging and Adaptive Optics 2021 Pub Date : 2021-08-05 DOI: 10.1117/12.2594754

Matthew R. Kemnetz, S. Gordeyev

{"title":"Analysis of Aero-Optical Jitter in Boundary Layers Using the Stitching Method","authors":"Matthew R. Kemnetz, S. Gordeyev","doi":"10.1117/12.2594754","DOIUrl":"https://doi.org/10.1117/12.2594754","url":null,"abstract":"In the typical analysis of aero-optical wavefront data, the three lowest order spatial modes are removed from the experimental data. These three spatial modes (tip, tilt, and piston) are commonly corrupted by mechanical disturbances. In this work an algorithm was developed that takes advantage of the advective nature of aberrations to compensate for the tip, tilt, and piston removal common in experiment. The algorithm is able to recover the aero-optical component of the jitter and provide time series of global tilt free of mechanical disturbances. This algorithm is called the stitching method. Experiments were conducted in Notre Dame’s Tri-sonic Wind Tunnel (TWT) Facility. Optical wavefront measurements were conducted on a Mach 0.6/0.1 shear layer. Voice coil actuators were placed on the shear layer splitter plate to regularize the shear layer. The predicted results for the RMS of the aero-optical jitter from the stitching method matched well with modeled results. Since the stitching method produces full time series of global tilt, energy spectra were also computed and presented. This information can be used by systems designers to benchmark fast steering mirrors for use in airborne directed energy systems.","PeriodicalId":168416,"journal":{"name":"Unconventional Imaging and Adaptive Optics 2021","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114384218","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}

引用次数: 0

Geiger-mode Avalanche Photodiode (GmAPD) arrays for single photon non-conventional imaging 盖革模式雪崩光电二极管(GmAPD)阵列用于单光子非常规成像

Unconventional Imaging and Adaptive Optics 2021 Pub Date : 2021-08-05 DOI: 10.1117/12.2599081

P. Kondratko, Stephen Stephen, Olaleye Aina

{"title":"Geiger-mode Avalanche Photodiode (GmAPD) arrays for single photon non-conventional imaging","authors":"P. Kondratko, Stephen Stephen, Olaleye Aina","doi":"10.1117/12.2599081","DOIUrl":"https://doi.org/10.1117/12.2599081","url":null,"abstract":"Availability of multi-pixel short-wave infra-red (SWIR) Geiger-mode avalanche photodiode (GmAPD) light detection and ranging (LIDAR) receivers have enabled unique detection and imaging capabilities in commercial and government platforms. Specific applications of this technology include long range target detection, acquisition, tracking, 3D mapping, optical communication, as well as intelligence, surveillance, and reconnaissance (ISR) missions capable of passive, direct, and coherent detection. This work will review the status of SWIR GmAPD cameras for various system applications. Technical specifications of the synchronous and asynchronous cameras enabled by high detector sensitivity and low dark count rate will be presented. Furthermore, details of camera functions and detector experimental performance (e. g. Format, Photon Detection Efficiency, Dark Count Rate, Wavelength, Timing) will be discussed. Combining single photon sensitive pixels, each capable of precise photon arrival timing enables LIDAR systems capable of unparalleled engagement ranges and non-conventional imaging methods. Range-echo imaging, non-line of sight detection, and other novel sensing techniques will be discussed specifically in systems challenged by platform’s size, weight, and power (SWaP). Application of measured Geiger-mode performance in various extended range scenarios will be reviewed for ground, tactical, space, and surveillance applications.","PeriodicalId":168416,"journal":{"name":"Unconventional Imaging and Adaptive Optics 2021","volume":"96 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114598476","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}

引用次数: 1

Investigating the outer scale of turbulence with time domain processing of anemometer data 用风速表数据的时域处理研究湍流的外尺度

Unconventional Imaging and Adaptive Optics 2021 Pub Date : 2021-08-04 DOI: 10.1117/12.2594967

J. McCrae, Steven T. Fiorino, S. Bose-Pillai, Benjamin Wilson

{"title":"Investigating the outer scale of turbulence with time domain processing of anemometer data","authors":"J. McCrae, Steven T. Fiorino, S. Bose-Pillai, Benjamin Wilson","doi":"10.1117/12.2594967","DOIUrl":"https://doi.org/10.1117/12.2594967","url":null,"abstract":"Sonic anemometers are used to study the outer scale in near ground level turbulence. Turbulence is expected to obey a Kolmogorov power spectrum within some inertial range, where the temperature or index of refraction fluctuations decrease as the inverse 11/3rds power of the spatial wavenumber. Below this inertial range (that is for sufficiently small spatial wavenumbers, or equivalently sufficiently large scale sizes) the form of the power spectrum isn’t predicted by theory, but it is expected to roll off. A levelling off of the power spectrum at low spatial frequencies corresponds to a levelling off of the structure function at large spatial separations, and this is the signal sought in the data. Near the ground there is some evidence the outer scale size may be as small as the height above ground. Sonic anemometer data was collected in the summer of 2019 in conjunction with optical turbulence experiments. These experiments showed good agreement between different ways of monitoring turbulence. In these experiments, the sonic anemometers were mostly mounted 2.64 meters above the ground. In this work, the anemometer data is being revisited to study the outer scale. Outer scale effects are quite subtle with optical techniques, which are arranged to be most sensitive to variations in index of refraction within the inertial range precisely in order to avoid inner and outer scale effects. Sonic anemometry usually achieves this by including only nearest neighbor measurements in turbulence estimation, but here we examine the variance of temperature differences across a wide range of baselines in order to study the structure function itself.","PeriodicalId":168416,"journal":{"name":"Unconventional Imaging and Adaptive Optics 2021","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123490895","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}

引用次数: 3