Pub Date : 1900-01-01DOI: 10.1364/adop.1996.amb.13
J. Shelton, T. G. Schneider, D. McKenna, S. Baliunas
Since June of 1994 we have been operating and improving a natural-guide-star adaptive optics system on the Mount Wilson 100-inch telescope.1,3 The system is routinely operated by one person plus a telescope operator. First astronomical observations have achieved image profiles with a full-width-at-half-max (FWHM) of 0.068 arcsec, using a silicon CCD with no wavelength discrimination (Fig. 1).
{"title":"Results from the Cassegrain adaptive optics system of the Mount Wilson 100-inch telescope","authors":"J. Shelton, T. G. Schneider, D. McKenna, S. Baliunas","doi":"10.1364/adop.1996.amb.13","DOIUrl":"https://doi.org/10.1364/adop.1996.amb.13","url":null,"abstract":"Since June of 1994 we have been operating and improving a natural-guide-star adaptive optics system on the Mount Wilson 100-inch telescope.1,3 The system is routinely operated by one person plus a telescope operator. First astronomical observations have achieved image profiles with a full-width-at-half-max (FWHM) of 0.068 arcsec, using a silicon CCD with no wavelength discrimination (Fig. 1).","PeriodicalId":256393,"journal":{"name":"Adaptive Optics","volume":"30 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":"116634283","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 this paper we present a reconstructor optimized to fully utilize spatial and temporal correlations of the measured wavefront and a hardware implementation being built for the adaptive optics system for the new 6.5m single-mirror MMT. We compare the projected performance for a closed-loop system which drives the mirror to obtain a wavefront sensor null with a system designed to “optimally” utilize measurements from the source--which may be a laser guide star.
{"title":"New Wavefront Reconstructor for the MMT Adaptive Secondary","authors":"S. Stahl, T. Barrett","doi":"10.1364/adop.1995.tua34","DOIUrl":"https://doi.org/10.1364/adop.1995.tua34","url":null,"abstract":"In this paper we present a reconstructor optimized to fully utilize spatial and temporal correlations of the measured wavefront and a hardware implementation being built for the adaptive optics system for the new 6.5m single-mirror MMT. We compare the projected performance for a closed-loop system which drives the mirror to obtain a wavefront sensor null with a system designed to “optimally” utilize measurements from the source--which may be a laser guide star.","PeriodicalId":256393,"journal":{"name":"Adaptive Optics","volume":"13 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":"124947441","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 factors which limits the performance of a NGS AO system is the brightness of available stars. This, when combined with a requirement for a high sky coverage and a moderate Strehl ratio (see Table 1), means that reference stars up to about 1.5 arcmin from the science object have to be used.
{"title":"Conjugating AO Correction to Turbulence in the WHT AO System Design","authors":"M. Wells","doi":"10.1364/adop.1995.pd9","DOIUrl":"https://doi.org/10.1364/adop.1995.pd9","url":null,"abstract":"One of the factors which limits the performance of a NGS AO system is the brightness of available stars. This, when combined with a requirement for a high sky coverage and a moderate Strehl ratio (see Table 1), means that reference stars up to about 1.5 arcmin from the science object have to be used.","PeriodicalId":256393,"journal":{"name":"Adaptive Optics","volume":"128 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":"122742097","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.8
P. Gallant, G. Aitken
Artificial neural networks have gained significant popularity over the past several years in a wide variety of engineering applications. This popularity is due in part to the ability of a neural network that is trained using a supervised training rule such as error backpropagation to acquire a nonparametric representation of the mapping between a set of inputs and outputs without any specific knowledge of the application domain. Given a sufficient number of nonlinear terms, represented by a number of hidden-layer neurons, a multilayer neural network can model any mathematical function that is continuous and differentiable (Hecht-Nielsen, 1990). Difficulties can arise however when a network is trained with a limited amount of noisy “real” data and is then expected to operate as part of a system for a specific application. The network must acquire an internal representation, as stored in its weights, during the training phase that subsequently generalizes well to unseen data. In the case of a prediction application, generalization capability becomes the paramount design criteria. The generalization performance of a trained network is a strong function of several factors, including: the architecture and complexity of the network, the type of supervised training rule employed, and the manner in which data is preprocessed and presented to the network.
{"title":"Simple Neural Networks as Wavefront Slope Predictors: Training and Performance Issues","authors":"P. Gallant, G. Aitken","doi":"10.1364/adop.1996.athc.8","DOIUrl":"https://doi.org/10.1364/adop.1996.athc.8","url":null,"abstract":"Artificial neural networks have gained significant popularity over the past several years in a wide variety of engineering applications. This popularity is due in part to the ability of a neural network that is trained using a supervised training rule such as error backpropagation to acquire a nonparametric representation of the mapping between a set of inputs and outputs without any specific knowledge of the application domain. Given a sufficient number of nonlinear terms, represented by a number of hidden-layer neurons, a multilayer neural network can model any mathematical function that is continuous and differentiable (Hecht-Nielsen, 1990). Difficulties can arise however when a network is trained with a limited amount of noisy “real” data and is then expected to operate as part of a system for a specific application. The network must acquire an internal representation, as stored in its weights, during the training phase that subsequently generalizes well to unseen data. In the case of a prediction application, generalization capability becomes the paramount design criteria. The generalization performance of a trained network is a strong function of several factors, including: the architecture and complexity of the network, the type of supervised training rule employed, and the manner in which data is preprocessed and presented to the network.","PeriodicalId":256393,"journal":{"name":"Adaptive Optics","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":"116752788","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}
Advances in adaptive optics have made it possible to consider their use to enhance ground-to-space laser communications systems. Adaptive optics are used to counteract the effects of atmospheric turbulence and deliver a beam undistorted through the atmosphere. This paper examines the system level requirements of an adaptive optical system in terms of communication parameters. An optical communications link must deliver a modulated beam to a receiving sensor with minimal distortion of the modulated signal. Distortion which stretches pulses, distorts pulse shapes, or otherwise randomizes the pulse intensity or location contributes to a higher bit error rate. The ability of adaptive optics to compensate for atmospheric scintillation is studied with respect to its effect on signal fade and surge.
{"title":"Adaptive optics requirements for a ground-to-space laser communications system","authors":"R. Tyson","doi":"10.1364/adop.1995.thc3","DOIUrl":"https://doi.org/10.1364/adop.1995.thc3","url":null,"abstract":"Advances in adaptive optics have made it possible to consider their use to enhance ground-to-space laser communications systems. Adaptive optics are used to counteract the effects of atmospheric turbulence and deliver a beam undistorted through the atmosphere. This paper examines the system level requirements of an adaptive optical system in terms of communication parameters. An optical communications link must deliver a modulated beam to a receiving sensor with minimal distortion of the modulated signal. Distortion which stretches pulses, distorts pulse shapes, or otherwise randomizes the pulse intensity or location contributes to a higher bit error rate. The ability of adaptive optics to compensate for atmospheric scintillation is studied with respect to its effect on signal fade and surge.","PeriodicalId":256393,"journal":{"name":"Adaptive Optics","volume":"22 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":"128218493","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}
Using a Shack-Hartmann sensor for measuring the wavefront gradient and the wavefront curvature by integrating over the subapertures allows to separate the influence of atmospheric layers.
{"title":"A new method for separating atmospheric layers using a Shack-Hartmann Curvature Sensor","authors":"A. Glindemann, T. Berkefeld","doi":"10.1364/adop.1996.awc.2","DOIUrl":"https://doi.org/10.1364/adop.1996.awc.2","url":null,"abstract":"Using a Shack-Hartmann sensor for measuring the wavefront gradient and the wavefront curvature by integrating over the subapertures allows to separate the influence of atmospheric layers.","PeriodicalId":256393,"journal":{"name":"Adaptive Optics","volume":"1 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":"128775481","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.5
J. Ge, B. Jacobsen, J. Angel, N. Woolfv, J. Black, M. Lloyd-Hart, P. Gray, R. Fugate
A prototype optical wavelength ultrahigh resolution echelle cross-dispersed spectrograph has been tested at the Starfire Optical Range (SOR) 1.5 m telescope (Woolf et al. 1995; Ge et al. 1996). To our knowledge this is the first high resolution spectrograph to take advantage of the diffraction limited images produced by an adaptive optics system. Because of the sharpened images produced by the adaptive optics at visible wavelength, about r0/D ~ 1/15 in the seeing-dominant domain, the narrow slits necessary for high resolution can be used without a large loss of light. This is a great advantage when compared with conventional high resolution spectrographs (e.g. Lambert et al. 1990; Diego et al. 1995). In addition, the smaller image widths inherent with the adaptive optics system allow the orders to be spaced closer together on the chip, allowing more orders to be observed simultaneously.
在星火光学距离(SOR) 1.5 m望远镜上测试了一个原型光学波长超高分辨率梯队交叉分散光谱仪(Woolf et al. 1995;Ge et al. 1996)。据我们所知，这是第一个利用自适应光学系统产生的衍射限制图像的高分辨率光谱仪。由于自适应光学在可见光波段产生的图像锐化，在视觉主导域约为0/D ~ 1/15，因此可以使用高分辨率所需的窄狭缝而不会造成大的光损失。与传统的高分辨率摄谱仪相比，这是一个很大的优势(例如Lambert et al. 1990;Diego et al. 1995)。此外，自适应光学系统固有的较小图像宽度允许订单在芯片上间隔更近，允许同时观察更多订单。
{"title":"An Optical Ultrahigh Resolution Spectrograph with the Adaptive Optics","authors":"J. Ge, B. Jacobsen, J. Angel, N. Woolfv, J. Black, M. Lloyd-Hart, P. Gray, R. Fugate","doi":"10.1364/adop.1996.atub.5","DOIUrl":"https://doi.org/10.1364/adop.1996.atub.5","url":null,"abstract":"A prototype optical wavelength ultrahigh resolution echelle cross-dispersed spectrograph has been tested at the Starfire Optical Range (SOR) 1.5 m telescope (Woolf et al. 1995; Ge et al. 1996). To our knowledge this is the first high resolution spectrograph to take advantage of the diffraction limited images produced by an adaptive optics system. Because of the sharpened images produced by the adaptive optics at visible wavelength, about r0/D ~ 1/15 in the seeing-dominant domain, the narrow slits necessary for high resolution can be used without a large loss of light. This is a great advantage when compared with conventional high resolution spectrographs (e.g. Lambert et al. 1990; Diego et al. 1995). In addition, the smaller image widths inherent with the adaptive optics system allow the orders to be spaced closer together on the chip, allowing more orders to be observed simultaneously.","PeriodicalId":256393,"journal":{"name":"Adaptive Optics","volume":"40 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":"129655875","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.17
G. Brusa, P. Gray, C. Vecchio, P. Salinari, W. Gallieni
The advantages of using an adaptive secondary mirror for astronomical high resolution observations are very attractive. The drastic reduction of optical surfaces along the optical train of the adaptive system will allow a very compact system with high transmission and low emissivity. Also such a system has the potentiality of a very high actuator density.
{"title":"Status of the Design of an Adaptive Secondary for the 6.5m conversion of the MMT telescope","authors":"G. Brusa, P. Gray, C. Vecchio, P. Salinari, W. Gallieni","doi":"10.1364/adop.1996.athc.17","DOIUrl":"https://doi.org/10.1364/adop.1996.athc.17","url":null,"abstract":"The advantages of using an adaptive secondary mirror for astronomical high resolution observations are very attractive. The drastic reduction of optical surfaces along the optical train of the adaptive system will allow a very compact system with high transmission and low emissivity. Also such a system has the potentiality of a very high actuator density.","PeriodicalId":256393,"journal":{"name":"Adaptive Optics","volume":"1 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":"130560833","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}
J. Christou, B. Ellerbroek, T. Pennington, J. Riker, J. Roark, E. Spillar
Work is in progress towards a series of observations to characterize the short- and long-exposure performance of an adaptive optics system as a function of wavelength and field-of-view. A principal goal of this effort will be to characterize the anisoplanatism observed in the infrared while using an off-axis visual guide star for tracking. More generally, we will investigate the effects of various methods for real-time and post-facto image tracking upon image quality in the presence of anisoplanatism. The instrumentation for the experiment is similar to that reported in [1], with the addition of an infrared sensor. Images are formed using the 1.5-meter telescope at the U. S. Air Fore Phillips Laboratory Starfire Optical Range and its adaptive optics system [2]. A beamsplitter sends the visible portion of the spectrum to a high speed, 64 by 64 pixel MIT/Lincoln Laboratory CCD array with high quantum efficiency and low readout noise. Re-imaging optics enable both components of wide binaries to be formed on the same array with a plate scale of 289 nrad/pixel. The infrared portion of the spectrum is imaged onto a 256 by 256 pixel NICMOS III detector with Infrared Labs electronics yielding approximately 100e- read noise. We are able to obtain simultaneous wave front sensor, optical, and infrared data with integration times of from 1 to 50 milliseconds.
{"title":"Simultaneous short exposure measurements of anisoplanatism using compensated images at optical and near infrared wavelengths","authors":"J. Christou, B. Ellerbroek, T. Pennington, J. Riker, J. Roark, E. Spillar","doi":"10.1364/adop.1996.awd.6","DOIUrl":"https://doi.org/10.1364/adop.1996.awd.6","url":null,"abstract":"Work is in progress towards a series of observations to characterize the short- and long-exposure performance of an adaptive optics system as a function of wavelength and field-of-view. A principal goal of this effort will be to characterize the anisoplanatism observed in the infrared while using an off-axis visual guide star for tracking. More generally, we will investigate the effects of various methods for real-time and post-facto image tracking upon image quality in the presence of anisoplanatism. The instrumentation for the experiment is similar to that reported in [1], with the addition of an infrared sensor. Images are formed using the 1.5-meter telescope at the U. S. Air Fore Phillips Laboratory Starfire Optical Range and its adaptive optics system [2]. A beamsplitter sends the visible portion of the spectrum to a high speed, 64 by 64 pixel MIT/Lincoln Laboratory CCD array with high quantum efficiency and low readout noise. Re-imaging optics enable both components of wide binaries to be formed on the same array with a plate scale of 289 nrad/pixel. The infrared portion of the spectrum is imaged onto a 256 by 256 pixel NICMOS III detector with Infrared Labs electronics yielding approximately 100e- read noise. We are able to obtain simultaneous wave front sensor, optical, and infrared data with integration times of from 1 to 50 milliseconds.","PeriodicalId":256393,"journal":{"name":"Adaptive Optics","volume":"39 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":"114223027","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.amb.30
P. Milonni, J. Telle
We describe calculations of the photon return signals from mesospheric sodium fluorescence excited by laser pulse trains. The theory combines a full density–matrix treatment of the sodium D2 line, including Doppler broadening and polarization–dependent optical pumping effects, with the Fried model of optical propagation through the turbulent atmosphere.
{"title":"Analysis of Sodium Layer Scattering Physics","authors":"P. Milonni, J. Telle","doi":"10.1364/adop.1996.amb.30","DOIUrl":"https://doi.org/10.1364/adop.1996.amb.30","url":null,"abstract":"We describe calculations of the photon return signals from mesospheric sodium fluorescence excited by laser pulse trains. The theory combines a full density–matrix treatment of the sodium D2 line, including Doppler broadening and polarization–dependent optical pumping effects, with the Fried model of optical propagation through the turbulent atmosphere.","PeriodicalId":256393,"journal":{"name":"Adaptive Optics","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":"121563069","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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