Pub Date : 1900-01-01DOI: 10.1364/adop.1996.athc.1
C. Mackay
New generations of fast, low-noise CCDs and their controllers are achieving the read-out noise and high frame rates that are critical to the successful completion of true adaptive optics systems. We describe the performance achieved for a variety of systems from those on COAST (Cambridge Optical Aperture Synthesis Telescope), the site evaluation program on the William Herschel Telescope on La Palma, and the results from the latest fast CCDs and new generation of CCD controllers.
新一代快速、低噪声的ccd及其控制器正在实现读出噪声和高帧率，这对于成功完成真正的自适应光学系统至关重要。本文介绍了在剑桥光学孔径合成望远镜(COAST)、拉帕尔马天文台威廉赫歇尔望远镜(William Herschel Telescope)上的现场评估项目以及最新的快速CCD和新一代CCD控制器的测试结果。
{"title":"Fast CCD Imaging Systems for Tilt-Tip and Wavefront Sensing Applications","authors":"C. Mackay","doi":"10.1364/adop.1996.athc.1","DOIUrl":"https://doi.org/10.1364/adop.1996.athc.1","url":null,"abstract":"New generations of fast, low-noise CCDs and their controllers are achieving the read-out noise and high frame rates that are critical to the successful completion of true adaptive optics systems. We describe the performance achieved for a variety of systems from those on COAST (Cambridge Optical Aperture Synthesis Telescope), the site evaluation program on the William Herschel Telescope on La Palma, and the results from the latest fast CCDs and new generation of CCD controllers.","PeriodicalId":256393,"journal":{"name":"Adaptive Optics","volume":"191 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":"123818632","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}
Pub Date : 1900-01-01DOI: 10.1364/adop.1996.atub.3
P. Ryan, J. Angel, D. McCarthy, L. Close, S. Mohanty, R. Fugate, D. Sandler
One of the questions which has endured for as long as man has looked at the heavens is ”Are we alone?”. Are there beings on other planets who are also looking into the heavens? The first requirement for alien life similar to our own is that there be planets orbiting other stars. The early stages of planet formation as dictated by theory appear to be robust and several large planets have recently been detected by indirect means[1][2]. Direct imaging is currently being used to search for less ambitious, yet still scientifically interesting faint objects called Brown Dwarfs. The most convincing evidence of a Brown Dwarf, a cross between a star and a planet, was discovered by direct imaging with the aid of a 7.7 arcsecond separation from a companion star[3].
{"title":"Halo Properties and Their Influence on Companion Searches at the Starfire Optical Range","authors":"P. Ryan, J. Angel, D. McCarthy, L. Close, S. Mohanty, R. Fugate, D. Sandler","doi":"10.1364/adop.1996.atub.3","DOIUrl":"https://doi.org/10.1364/adop.1996.atub.3","url":null,"abstract":"One of the questions which has endured for as long as man has looked at the heavens is ”Are we alone?”. Are there beings on other planets who are also looking into the heavens? The first requirement for alien life similar to our own is that there be planets orbiting other stars. The early stages of planet formation as dictated by theory appear to be robust and several large planets have recently been detected by indirect means[1][2]. Direct imaging is currently being used to search for less ambitious, yet still scientifically interesting faint objects called Brown Dwarfs. The most convincing evidence of a Brown Dwarf, a cross between a star and a planet, was discovered by direct imaging with the aid of a 7.7 arcsecond separation from a companion star[3].","PeriodicalId":256393,"journal":{"name":"Adaptive Optics","volume":"300 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":"131604671","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}
D. Bonaccini, S. Cova, M. Ghioni, F. Zappa, R. Gheser
Considering adaptive optics servosystems (AOS) in astronomical applications, a number of error sources have been identified in the wavefront sensor, which provides the reference signal of the servo-loop. These errors impair the system performance, especially with usually faint sources such as Natural Guide Stars (NGS).
{"title":"Development of high QE, fast Avalanche Photodiodes for Astronomical Adaptive Optics","authors":"D. Bonaccini, S. Cova, M. Ghioni, F. Zappa, R. Gheser","doi":"10.1364/adop.1995.tua53","DOIUrl":"https://doi.org/10.1364/adop.1995.tua53","url":null,"abstract":"Considering adaptive optics servosystems (AOS) in astronomical applications, a number of error sources have been identified in the wavefront sensor, which provides the reference signal of the servo-loop. These errors impair the system performance, especially with usually faint sources such as Natural Guide Stars (NGS).","PeriodicalId":256393,"journal":{"name":"Adaptive Optics","volume":"5 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":"124715818","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}
Spatial light modulators have substantially improved in the past few years. Currently, commercial 256 by 256 pixel liquid crystal binary SLMs are available with an operating speed of a millisecond and a pixel spacing of 20 microns for a price of $15,000. Additional improvements in speed by orders of magnitude should be available in the next few years, and micro-mechanical flexure and deformable membrane devices will probably become available.
{"title":"Spatial Light Modulator Structures for Adaptive Optics","authors":"C. Woods","doi":"10.1364/adop.1995.tha5","DOIUrl":"https://doi.org/10.1364/adop.1995.tha5","url":null,"abstract":"Spatial light modulators have substantially improved in the past few years. Currently, commercial 256 by 256 pixel liquid crystal binary SLMs are available with an operating speed of a millisecond and a pixel spacing of 20 microns for a price of $15,000. Additional improvements in speed by orders of magnitude should be available in the next few years, and micro-mechanical flexure and deformable membrane devices will probably become available.","PeriodicalId":256393,"journal":{"name":"Adaptive Optics","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":"120867916","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}
Pub Date : 1900-01-01DOI: 10.1364/adop.1996.athc.26
D. Gallieni, D. Bonaccini
Adaptive Optics systems need a wavefront sensor (WFS) for the servo-loop. The WFS integration time has to be selected considering SNR requirements. This requires to extend the integration period as much as possible, especially when dealing with faint sources. On the other hand, WFS sampling period imposes the discretization time-step to the entire servo-system, thus influencing its close loop bandwidth. The latter is also affected by additional time delays caused by WFS readout/reconstructor computing time.
{"title":"Digital Filtering Techniques and Centroid Predictors In Ao Servo-Systems","authors":"D. Gallieni, D. Bonaccini","doi":"10.1364/adop.1996.athc.26","DOIUrl":"https://doi.org/10.1364/adop.1996.athc.26","url":null,"abstract":"Adaptive Optics systems need a wavefront sensor (WFS) for the servo-loop. The WFS integration time has to be selected considering SNR requirements. This requires to extend the integration period as much as possible, especially when dealing with faint sources. On the other hand, WFS sampling period imposes the discretization time-step to the entire servo-system, thus influencing its close loop bandwidth. The latter is also affected by additional time delays caused by WFS readout/reconstructor computing time.","PeriodicalId":256393,"journal":{"name":"Adaptive Optics","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":"133850044","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}
We shall be concerned here with the problem of tilt anisoplanatism in the use of an artificial-guide-star adaptive optics system in imaging some astronomical object of interest through the turbulent atmosphere. It is well known that because the position of the back scatter region is determined by the direction in which the laser beam was transmitted an artificial-guide-star can not provide any pointing information pertaining to turbulence induced tilt— at least not in any direct manner. (Indirect methods, such as those involving second harmonic generation closely coupled with the back scatter process are being considered but the feasibility of such approaches is still unclear.) If the object of interest is sufficiently bright it can serve as the guide star for correction of turbulence induced tilt—or if there is a sufficiently bright star close enough to the object of interest then it can serve as a natural-guide-star for the correction of turbulence induced tilt. The farther away that natural-guide-star is from the object of interest the greater the discrepancy between the turbulence induced tilt for the object of interest and that for the natural-guide-star, and the lower the Strehl ratio of the image of the object of interest will be—even though the artificial-guide-star may be providing a basis for perfect adaptive optics correction of the higher-order wave front distortion.
{"title":"Artificial-Guide-Star Tilt-Anisoplanatism: Its Magnitude and (Limited) Amelioration","authors":"D. Fried","doi":"10.1364/adop.1995.wb5","DOIUrl":"https://doi.org/10.1364/adop.1995.wb5","url":null,"abstract":"We shall be concerned here with the problem of tilt anisoplanatism in the use of an artificial-guide-star adaptive optics system in imaging some astronomical object of interest through the turbulent atmosphere. It is well known that because the position of the back scatter region is determined by the direction in which the laser beam was transmitted an artificial-guide-star can not provide any pointing information pertaining to turbulence induced tilt— at least not in any direct manner. (Indirect methods, such as those involving second harmonic generation closely coupled with the back scatter process are being considered but the feasibility of such approaches is still unclear.) If the object of interest is sufficiently bright it can serve as the guide star for correction of turbulence induced tilt—or if there is a sufficiently bright star close enough to the object of interest then it can serve as a natural-guide-star for the correction of turbulence induced tilt. The farther away that natural-guide-star is from the object of interest the greater the discrepancy between the turbulence induced tilt for the object of interest and that for the natural-guide-star, and the lower the Strehl ratio of the image of the object of interest will be—even though the artificial-guide-star may be providing a basis for perfect adaptive optics correction of the higher-order wave front distortion.","PeriodicalId":256393,"journal":{"name":"Adaptive Optics","volume":"135 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":"134082620","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}
S. Browne, J. Vaughn, G. Tyler, J. Gonglewski, D. Dayton, S. Sandven, D. Laughlin
Au experiment with a nasmyth adaptive optics system mounted on the SOR 3.5m telescope employs an adaptive optical imager. A 148-subaperture hexagonal lenslet array provides a Hartmann wavefront sensor for the 163 actuator mirror to which it is mated. Our analysis of the control loop of the adaptive optical system is edified, and the actual implementation is explained. Performance tradeoffs between various subaperture geometries, based on reconstructor noise gain and stability considerations, are presented. A fast algorithm for measuring Hartmann spot positions is combined with a computationally efficient reconstructor running on a pair of i860XP processors to achieve 1000 reconstructions per second. Moreover, the reconstructor can perform much of its processing on the fly while the frame is being transferred from the pupil plane camera, resulting in significantly reduced servo phase lag. We describe the control loop design, with particular emphasis on the creative use of hardware data paths.
{"title":"Control Loop Analysis and Characterization for an Adaptive Optics Experiment on the Starfire 3.5m Telescope","authors":"S. Browne, J. Vaughn, G. Tyler, J. Gonglewski, D. Dayton, S. Sandven, D. Laughlin","doi":"10.1364/adop.1995.tua37","DOIUrl":"https://doi.org/10.1364/adop.1995.tua37","url":null,"abstract":"Au experiment with a nasmyth adaptive optics system mounted on the SOR 3.5m telescope employs an adaptive optical imager. A 148-subaperture hexagonal lenslet array provides a Hartmann wavefront sensor for the 163 actuator mirror to which it is mated. Our analysis of the control loop of the adaptive optical system is edified, and the actual implementation is explained. Performance tradeoffs between various subaperture geometries, based on reconstructor noise gain and stability considerations, are presented. A fast algorithm for measuring Hartmann spot positions is combined with a computationally efficient reconstructor running on a pair of i860XP processors to achieve 1000 reconstructions per second. Moreover, the reconstructor can perform much of its processing on the fly while the frame is being transferred from the pupil plane camera, resulting in significantly reduced servo phase lag. We describe the control loop design, with particular emphasis on the creative use of hardware data paths.","PeriodicalId":256393,"journal":{"name":"Adaptive Optics","volume":"35 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":"134358534","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}
V. Biliotti, R. Biasi, G. Brusa, D. Gallieni, Roberto Spairani, Roberto Aiello
The thin faceplate adaptive secondary mirrors are controlled by means of electromagnetic force actuators, which seem to be a suitable choice in terms of stroke, accuracy and cost [Del Vecchio, Gallieni et al.; Biasi, Gallieni et al. in this Conference]. Those actuators need a local control loop to achieve a linear position response. The position sensor is definitely a crucial component of this control loop: both high sensitivity and high speed have to be achieved at same time.
薄面板自适应二次反射镜采用电磁力执行器控制，在行程、精度和成本方面似乎是一种合适的选择[Del Vecchio, Gallieni et al.;Biasi, Gallieni et al.[在本次会议上]。这些执行器需要一个局部控制回路来实现线性位置响应。位置传感器绝对是这个控制回路的关键组成部分:高灵敏度和高速度必须同时实现。
{"title":"High Accuracy Capacitive Displacement Transducer for the Position Local Control Loops at the Adaptive Secondary","authors":"V. Biliotti, R. Biasi, G. Brusa, D. Gallieni, Roberto Spairani, Roberto Aiello","doi":"10.1364/adop.1995.tua29","DOIUrl":"https://doi.org/10.1364/adop.1995.tua29","url":null,"abstract":"The thin faceplate adaptive secondary mirrors are controlled by means of electromagnetic force actuators, which seem to be a suitable choice in terms of stroke, accuracy and cost [Del Vecchio, Gallieni et al.; Biasi, Gallieni et al. in this Conference]. Those actuators need a local control loop to achieve a linear position response. The position sensor is definitely a crucial component of this control loop: both high sensitivity and high speed have to be achieved at same time.","PeriodicalId":256393,"journal":{"name":"Adaptive Optics","volume":"8 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":"133789456","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}
To estimate the centroid of a light intensity distribution is a technique widely used in different fields: motion analysis of moving objects from series of frames(1); tracking systems for laser communication(2); resolution improvement by recentering short-exposures images allowing motion removing(3); and adaptive optics, when the wave-front distortion is estimated from the movement of a series of spots produced by an array of lenslet (Hartman-Shack wave-front sensor)(4).
{"title":"Error reduction in centroid estimates using image intensifiers","authors":"M. Cagigal, M. G. Portilla, P. Prieto","doi":"10.1364/adop.1995.tua51","DOIUrl":"https://doi.org/10.1364/adop.1995.tua51","url":null,"abstract":"To estimate the centroid of a light intensity distribution is a technique widely used in different fields: motion analysis of moving objects from series of frames(1); tracking systems for laser communication(2); resolution improvement by recentering short-exposures images allowing motion removing(3); and adaptive optics, when the wave-front distortion is estimated from the movement of a series of spots produced by an array of lenslet (Hartman-Shack wave-front sensor)(4).","PeriodicalId":256393,"journal":{"name":"Adaptive Optics","volume":"48 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":"123509829","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 Western Europe in the early seventies, main emphasis was put on high-power laser applications. Later, compensated imaging became the main driver, leading to the first routinely operated adaptive system in astronomy.
{"title":"Adaptive Optics in Western Europe","authors":"F. Merkle, C. Zeiss","doi":"10.1364/adop.1995.tha1","DOIUrl":"https://doi.org/10.1364/adop.1995.tha1","url":null,"abstract":"In Western Europe in the early seventies, main emphasis was put on high-power laser applications. Later, compensated imaging became the main driver, leading to the first routinely operated adaptive system in astronomy.","PeriodicalId":256393,"journal":{"name":"Adaptive Optics","volume":"31 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":"122401823","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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