C. Jenkins, Nick Dillon, Mike Burns, R. Mcgonegal, J. Oschmann, D. Robertson
The GEMINI telescopes are intended to deliver very good image quality with only tip-tilt correction at the secondary mirror. Designing the guiding systems for these telescopes has made use of simple yet accurate models of the image size. These are described here, with illustrations of the complex tradeoffs that are necessary to achieve the best images. The current design of the guiders is given. These also serve as active optics wavefront sensors to provide closed loop control of the telescope alignment and figure at slow rates.
{"title":"Gemini 8 Meter Telescopes Active Guiding System Considerations","authors":"C. Jenkins, Nick Dillon, Mike Burns, R. Mcgonegal, J. Oschmann, D. Robertson","doi":"10.1364/adop.1995.tua40","DOIUrl":"https://doi.org/10.1364/adop.1995.tua40","url":null,"abstract":"The GEMINI telescopes are intended to deliver very good image quality with only tip-tilt correction at the secondary mirror. Designing the guiding systems for these telescopes has made use of simple yet accurate models of the image size. These are described here, with illustrations of the complex tradeoffs that are necessary to achieve the best images. The current design of the guiders is given. These also serve as active optics wavefront sensors to provide closed loop control of the telescope alignment and figure at slow rates.","PeriodicalId":256393,"journal":{"name":"Adaptive Optics","volume":"29 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":"121944553","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 use wavefront sensor data, obtained directly during the acquisition of the science target, to retrieve the system point spread function, required for data reduction and image restoration. First results on simulated data are presented.
{"title":"Adaptive Optics Point Spread Function Retrieval from Wavefront Sensor Measurements","authors":"J. Véran, F. Rigaut, H. Maître","doi":"10.1364/adop.1995.pd2","DOIUrl":"https://doi.org/10.1364/adop.1995.pd2","url":null,"abstract":"We use wavefront sensor data, obtained directly during the acquisition of the science target, to retrieve the system point spread function, required for data reduction and image restoration. First results on simulated data are presented.","PeriodicalId":256393,"journal":{"name":"Adaptive Optics","volume":"87 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":"122282984","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 set of two independent testing subsystem of segmented mirror figure based on heterodine interferometer and local sensors of angle and linear moving makes it possible to solve the 2nπ problem and reduce demands to the stability of local sensors zero point.
{"title":"The Potential Accuracy of Segmented Mirror Figure Stabilisation with Two-Stage Testing","authors":"V. Sidorov","doi":"10.1364/adop.1995.pd5","DOIUrl":"https://doi.org/10.1364/adop.1995.pd5","url":null,"abstract":"The set of two independent testing subsystem of segmented mirror figure based on heterodine interferometer and local sensors of angle and linear moving makes it possible to solve the 2nπ problem and reduce demands to the stability of local sensors zero point.","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":"132332750","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. S. Acton, P. Stomski, P. Wizinowich, J. Maute, T. Gregory, M. Ealey, T. Price
The W. M. Keck Observatory and Lawrence Livermore National Labs are currently developing an adaptive optics system for use on Keck II--a 10.8-meter segmented telescope. This AO system will make use of a 349-actuator deformable mirror (DM). The Keck II telescope sits atop Hawaii’s Mauna Kea, where the ambient nighttime temperature varies between -5 and 5 degrees C. In order to reduce dome seeing, and to minimize the thermal emissivity, the AO system (and hence the DM) will be cooled to the ambient temperature of the outside air. Therefore, we are motivated to use actuators in the DM that are optimized for operation at 0 degrees C.
W. M.凯克天文台和劳伦斯利弗莫尔国家实验室目前正在开发一种用于凯克二号的自适应光学系统——一个10.8米的分段望远镜。该AO系统将使用349致动器变形镜(DM)。凯克II号望远镜位于夏威夷的莫纳克亚山上，那里的夜间环境温度在-5到5摄氏度之间变化。为了减少圆顶的可见度，并最大限度地减少热辐射率，AO系统(因此DM)将被冷却到外部空气的环境温度。因此，我们有动力在DM中使用针对0℃操作进行优化的执行器。
{"title":"Keck Adaptive Optics: Test of a Deformable Mirror in a Freezing Environment","authors":"D. S. Acton, P. Stomski, P. Wizinowich, J. Maute, T. Gregory, M. Ealey, T. Price","doi":"10.1364/adop.1996.afa.2","DOIUrl":"https://doi.org/10.1364/adop.1996.afa.2","url":null,"abstract":"The W. M. Keck Observatory and Lawrence Livermore National Labs are currently developing an adaptive optics system for use on Keck II--a 10.8-meter segmented telescope. This AO system will make use of a 349-actuator deformable mirror (DM). The Keck II telescope sits atop Hawaii’s Mauna Kea, where the ambient nighttime temperature varies between -5 and 5 degrees C. In order to reduce dome seeing, and to minimize the thermal emissivity, the AO system (and hence the DM) will be cooled to the ambient temperature of the outside air. Therefore, we are motivated to use actuators in the DM that are optimized for operation at 0 degrees C.","PeriodicalId":256393,"journal":{"name":"Adaptive Optics","volume":"62 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":"132561702","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.athb.1
W. Wild
An adaptive optics system is a closed-loop servo control system that seeks to maximize PSF Strehl ratio performance by minimizing wavefront distortions. The wavefront is sampled over discrete subapertures and the local slopes are used to estimate the instantaneous wavefront shape which is then used to drive a deformable mirror with a discrete array of actuators. The temporal and spatial performance of the system is embodied in a single mathematical descriptor of the form Γ is a covariance matrix of the error between the atmosphere phase φ(ti+1) at time ti+1 and the deformable mirror figure, ϕdm(ti), derived from measurements at the previous time ti. Boldface quantities are vectors and matrices. The phase reflecting off the mirror is φ(ti+1) – ϕ(ti), presently assuming that ϕdm(ti)≈ϕ(ti), where ϕ(ti) is the estimated wavefront phase. Covariance matrices are a powerful mathematical tool because they contain information, in an ensemble average sense, about the sources of error and correlations present in the system. From Γ, the Strehl ratio, the MTF, time-delay, etc., can be computed. The Strehl ratio in the Marechal approximation is S ~ exp(–σ2), where σ2=Tr(Γ) /Na, for Na actuators within the pupil.
{"title":"Optimal Estimators for Astronomical Adaptive Optics","authors":"W. Wild","doi":"10.1364/adop.1996.athb.1","DOIUrl":"https://doi.org/10.1364/adop.1996.athb.1","url":null,"abstract":"An adaptive optics system is a closed-loop servo control system that seeks to maximize PSF Strehl ratio performance by minimizing wavefront distortions. The wavefront is sampled over discrete subapertures and the local slopes are used to estimate the instantaneous wavefront shape which is then used to drive a deformable mirror with a discrete array of actuators. The temporal and spatial performance of the system is embodied in a single mathematical descriptor of the form Γ is a covariance matrix of the error between the atmosphere phase φ(ti+1) at time ti+1 and the deformable mirror figure, ϕdm(ti), derived from measurements at the previous time ti. Boldface quantities are vectors and matrices. The phase reflecting off the mirror is φ(ti+1) – ϕ(ti), presently assuming that ϕdm(ti)≈ϕ(ti), where ϕ(ti) is the estimated wavefront phase. Covariance matrices are a powerful mathematical tool because they contain information, in an ensemble average sense, about the sources of error and correlations present in the system. From Γ, the Strehl ratio, the MTF, time-delay, etc., can be computed. The Strehl ratio in the Marechal approximation is S ~ exp(–σ2), where σ2=Tr(Γ) /Na, for Na actuators within the pupil.","PeriodicalId":256393,"journal":{"name":"Adaptive Optics","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":"133997743","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.24
D. Gregory, J. L. McClain, T. Hudson
Most common optical elements employ some sort of phase delay in order to manipulate wavefronts. These optical elements (lenses, prisms, etc.) are well known and have fixed phase delays. Using a pixelated, phase modulating device, such as a liquid crystal television (LCTV), it is possible to design tunable lenses, prisms, and gratings.
{"title":"Liquid crystal displays as programmable adaptive optical elements","authors":"D. Gregory, J. L. McClain, T. Hudson","doi":"10.1364/adop.1996.athc.24","DOIUrl":"https://doi.org/10.1364/adop.1996.athc.24","url":null,"abstract":"Most common optical elements employ some sort of phase delay in order to manipulate wavefronts. These optical elements (lenses, prisms, etc.) are well known and have fixed phase delays. Using a pixelated, phase modulating device, such as a liquid crystal television (LCTV), it is possible to design tunable lenses, prisms, and gratings.","PeriodicalId":256393,"journal":{"name":"Adaptive Optics","volume":"75 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":"134551315","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.athb.2
B. Ellerbroek, T. Rhoadarmer
Experiments have shown the reward adaptive-optics provides in improving the resolution of ground-based astronomical telescopes [1,2,3]. A critical contributor to adaptive-optics system performance is the control algorithm that converts wavefront sensor (WFS) measurements into the deformable mirror (DM) actuator commands. For the adaptive-optics systems in use today this control algorithm consists of a wavefront reconstruction step to estimate the instantaneous phase distortion to be compensated [4], followed by a servo control law to temporally filter this instantaneous estimate before it is applied to the deformable mirror [5]. So-called modal adaptive-optics systems can apply different temporal filters to separate spatial components, or modes, of the overall phase distortion [6]. Extensive analysis has been performed to evaluate and optimize the performance of these adaptive-optics control systems [7,8,9,10,11], but the results obtained depend on atmospheric parameters which are seldom known exactly and are constantly fluctuating. The uncertainty and variability of atmospheric conditions implies that an optimal degree of turbulence compensation cannot be achieved or maintained for long time intervals with a fixed control algorithm. A need exists for methods to update adaptive-optics control algorithms based upon actual system performance. Encouraging results have already been obtained demonstrating the value of emperically optimizing the control bandwidths for a modal adaptive-optics system [12]. In comparison, the subject of real-time adjustments to reconstruction matrices on the basis of measured system performance has received little attention.
{"title":"Optimization of Closed-Loop Adaptive-Optics Control Algorithms Using Measured Performance Data: Experimental Results","authors":"B. Ellerbroek, T. Rhoadarmer","doi":"10.1364/adop.1996.athb.2","DOIUrl":"https://doi.org/10.1364/adop.1996.athb.2","url":null,"abstract":"Experiments have shown the reward adaptive-optics provides in improving the resolution of ground-based astronomical telescopes [1,2,3]. A critical contributor to adaptive-optics system performance is the control algorithm that converts wavefront sensor (WFS) measurements into the deformable mirror (DM) actuator commands. For the adaptive-optics systems in use today this control algorithm consists of a wavefront reconstruction step to estimate the instantaneous phase distortion to be compensated [4], followed by a servo control law to temporally filter this instantaneous estimate before it is applied to the deformable mirror [5]. So-called modal adaptive-optics systems can apply different temporal filters to separate spatial components, or modes, of the overall phase distortion [6]. Extensive analysis has been performed to evaluate and optimize the performance of these adaptive-optics control systems [7,8,9,10,11], but the results obtained depend on atmospheric parameters which are seldom known exactly and are constantly fluctuating. The uncertainty and variability of atmospheric conditions implies that an optimal degree of turbulence compensation cannot be achieved or maintained for long time intervals with a fixed control algorithm. A need exists for methods to update adaptive-optics control algorithms based upon actual system performance. Encouraging results have already been obtained demonstrating the value of emperically optimizing the control bandwidths for a modal adaptive-optics system [12]. In comparison, the subject of real-time adjustments to reconstruction matrices on the basis of measured system performance has received little attention.","PeriodicalId":256393,"journal":{"name":"Adaptive Optics","volume":"116 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":"134582596","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}
Elemental Na has been the tracer of choice for the generation of high altitude (mesospheric) guide stars because of its relatively large natural abundance and large absorption cross section. Dye based systems using Na are currently under development for several large aperture telescopes. However, robust solid state laser technology to generate high power narrow linewidth light at 589 nm has progressed slowly. Here we consider both the tracer and the transmitter technology and show that using either the K D1 line at 769 nm or the 372 nm line of Fe (a 5D-z 5F°) for the tracer may provide robust solutions until solid state Na transmitter technology can be more fully developed. The comparable performance is primarily due to the fact that both lines can be generated with existing solid state materials (Alexandrite, Ti:Sapphire).
{"title":"Mesospheric Metals for Guide Star Generation","authors":"G. Papen","doi":"10.1364/adop.1995.thc4","DOIUrl":"https://doi.org/10.1364/adop.1995.thc4","url":null,"abstract":"Elemental Na has been the tracer of choice for the generation of high altitude (mesospheric) guide stars because of its relatively large natural abundance and large absorption cross section. Dye based systems using Na are currently under development for several large aperture telescopes. However, robust solid state laser technology to generate high power narrow linewidth light at 589 nm has progressed slowly. Here we consider both the tracer and the transmitter technology and show that using either the K D1 line at 769 nm or the 372 nm line of Fe (a 5D-z 5F°) for the tracer may provide robust solutions until solid state Na transmitter technology can be more fully developed. The comparable performance is primarily due to the fact that both lines can be generated with existing solid state materials (Alexandrite, Ti:Sapphire).","PeriodicalId":256393,"journal":{"name":"Adaptive Optics","volume":"202 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":"133879013","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}
L. Close, M. Lloyd-Hart, J. Angel, D. Mccarthy, G. Brusa, B. McLeod, T. Groesbeck, D. Wittman, P. Ryan, T. Martinez, P. Gray, J. M. Hughes, M. Cheselka, B. Jacobsen, D. Bruns, D. Sandler
The mission of the Center for Astronomical Adaptive Optics (CAAO) at Steward Observatory is to develop a diffraction-limited laser guide star adaptive optics system. This system is targeted for the new 6.5m mirror MMT upgrade. This single mirror will be installed in the existing Multiple Mirror Telescope (MMT) mount in late 1996 (to replace the existing six individual 1.8m primaries). Presently CAAO has focused on implementing a simpler instrument which tip-tilt corrects all six beams from the existing MMT. The major features of this instrument (called FASTTRAC II) will be used in the 6.5m system with minimal changes. In addition, FASTTRAC II fully addresses all the major optical, electrical, mechanical and computational challenges of having a common user instrument on a ALT-AZ mount utilizing a sodium laser guide star.
{"title":"Results from the MMT Adaptive Optics Infrared Imager FASTTRAC II","authors":"L. Close, M. Lloyd-Hart, J. Angel, D. Mccarthy, G. Brusa, B. McLeod, T. Groesbeck, D. Wittman, P. Ryan, T. Martinez, P. Gray, J. M. Hughes, M. Cheselka, B. Jacobsen, D. Bruns, D. Sandler","doi":"10.1364/adop.1995.tua49","DOIUrl":"https://doi.org/10.1364/adop.1995.tua49","url":null,"abstract":"The mission of the Center for Astronomical Adaptive Optics (CAAO) at Steward Observatory is to develop a diffraction-limited laser guide star adaptive optics system. This system is targeted for the new 6.5m mirror MMT upgrade. This single mirror will be installed in the existing Multiple Mirror Telescope (MMT) mount in late 1996 (to replace the existing six individual 1.8m primaries). Presently CAAO has focused on implementing a simpler instrument which tip-tilt corrects all six beams from the existing MMT. The major features of this instrument (called FASTTRAC II) will be used in the 6.5m system with minimal changes. In addition, FASTTRAC II fully addresses all the major optical, electrical, mechanical and computational challenges of having a common user instrument on a ALT-AZ mount utilizing a sodium laser guide star.","PeriodicalId":256393,"journal":{"name":"Adaptive Optics","volume":"87 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":"128943789","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}
This work is part of a study that aims at implementing adaptive optics on a secondary mirror of an 8 m class astronomical telescope for atmospheric compensation at visible wavelength. The secondary mirror to be controlled is a continuous thin facesheet type. The goal is to fulfill operational specifications by using voice coils actuators coupled to collocated capacitive position transducers.
{"title":"Simulation of Adaptive Secondary Mirror Dynamic Response","authors":"R. Biasi, D. Gallieni, P. Mantegazza","doi":"10.1364/adop.1995.tua30","DOIUrl":"https://doi.org/10.1364/adop.1995.tua30","url":null,"abstract":"This work is part of a study that aims at implementing adaptive optics on a secondary mirror of an 8 m class astronomical telescope for atmospheric compensation at visible wavelength. The secondary mirror to be controlled is a continuous thin facesheet type. The goal is to fulfill operational specifications by using voice coils actuators coupled to collocated capacitive position transducers.","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":"132262464","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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