Pub Date : 1996-07-07DOI: 10.1364/adop.1996.amb.12
R. Dekany
Currently under construction at the Jet Propulsion Laboratory, the Palomar Adaptive Optics System (PALAO) is a Cassegrain-mounted system for infrared astronomy incorporating active laser metrology to minimize the effects of mechanical flexure.
{"title":"The Palomar Adaptive Optics System","authors":"R. Dekany","doi":"10.1364/adop.1996.amb.12","DOIUrl":"https://doi.org/10.1364/adop.1996.amb.12","url":null,"abstract":"Currently under construction at the Jet Propulsion Laboratory, the Palomar Adaptive Optics System (PALAO) is a Cassegrain-mounted system for infrared astronomy incorporating active laser metrology to minimize the effects of mechanical flexure.","PeriodicalId":256393,"journal":{"name":"Adaptive Optics","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123232994","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 Keck telescope adaptive optics system is designed to optimize performance in the 1 to 3 micron region of observation wavelengths (J, H, and K astronomical bands). The system uses a 349 degree of freedom deformable mirror, so that the interactuator spacing is 56 cm as mapped onto the 10 meter aperture. 56 cm is roughly equal to r0 at 1.4 microns, which implies the wavefront fitting error is 0.52 (λ/2π)(d/r0)5/6 = 118 nm rms. This is sufficient to produce a system Strehl of 0.74 at 1.4 microns if all other sources of error are negligible, which would be the case with a bright natural guidestar and very high control bandwidth. Other errors associated with the adaptive optics system will however contribute to Strehl degradation, namely, servo bandwidth error due to inability to reject all temporal frequencies of the aberrated wavefront, wavefront measurement error due to finite signal-to-noise ratio in the wavefront sensor, and, in the case of a laser guidestar, the so-called cone effect where rays from the guidestar beacon fail to sample some of the upper atmosphere turbulence. Cone effect is mitigated considerably by the use of the very high altitude sodium layer guidestar (90 km altitude), as opposed to Rayleigh beacons at 20 km. However, considering the Keck telescope’s large aperture, this is still the dominating wavefront error contributor in the current adaptive optics system design.
{"title":"Performance of Keck Adaptive Optics with Sodium Laser Guide Stars","authors":"D. Gavel, S. Olivier, J. Brase","doi":"10.1364/adop.1996.amb.5","DOIUrl":"https://doi.org/10.1364/adop.1996.amb.5","url":null,"abstract":"The Keck telescope adaptive optics system is designed to optimize performance in the 1 to 3 micron region of observation wavelengths (J, H, and K astronomical bands). The system uses a 349 degree of freedom deformable mirror, so that the interactuator spacing is 56 cm as mapped onto the 10 meter aperture. 56 cm is roughly equal to r0 at 1.4 microns, which implies the wavefront fitting error is 0.52 (λ/2π)(d/r0)5/6 = 118 nm rms. This is sufficient to produce a system Strehl of 0.74 at 1.4 microns if all other sources of error are negligible, which would be the case with a bright natural guidestar and very high control bandwidth. Other errors associated with the adaptive optics system will however contribute to Strehl degradation, namely, servo bandwidth error due to inability to reject all temporal frequencies of the aberrated wavefront, wavefront measurement error due to finite signal-to-noise ratio in the wavefront sensor, and, in the case of a laser guidestar, the so-called cone effect where rays from the guidestar beacon fail to sample some of the upper atmosphere turbulence. Cone effect is mitigated considerably by the use of the very high altitude sodium layer guidestar (90 km altitude), as opposed to Rayleigh beacons at 20 km. However, considering the Keck telescope’s large aperture, this is still the dominating wavefront error contributor in the current adaptive optics system design.","PeriodicalId":256393,"journal":{"name":"Adaptive Optics","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122014197","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 : 1996-03-08DOI: 10.1364/adop.1996.amb.11
H. Bissinger, S. Olivier, C. Max
In this paper, we present a conceptual design for a general-purpose adaptive optics (AO) system, usable with all Cassegrain facility instruments on the 3 meter Shane telescope at the University of California's Lick Observatory located on Mt. Hamilton near San Jose, California. The overall design goal for this system is to take the sodium-layer laser guide star adaptive optics technology out of the demonstration stage and to build a user-friendly astronomical tool. The emphasis will be on ease of calibration, improved stability and operational simplicity in order to allow the system to be run routinely by observatory staff.
{"title":"Conceptual Design for a User-Friendly Adaptive Optics System at Lick Observatory","authors":"H. Bissinger, S. Olivier, C. Max","doi":"10.1364/adop.1996.amb.11","DOIUrl":"https://doi.org/10.1364/adop.1996.amb.11","url":null,"abstract":"In this paper, we present a conceptual design for a general-purpose adaptive optics (AO) system, usable with all Cassegrain facility instruments on the 3 meter Shane telescope at the University of California's Lick Observatory located on Mt. Hamilton near San Jose, California. The overall design goal for this system is to take the sodium-layer laser guide star adaptive optics technology out of the demonstration stage and to build a user-friendly astronomical tool. The emphasis will be on ease of calibration, improved stability and operational simplicity in order to allow the system to be run routinely by observatory staff.","PeriodicalId":256393,"journal":{"name":"Adaptive Optics","volume":"268 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124257662","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 : 1996-03-06DOI: 10.1364/adop.1996.amb.27
H. Friedman, R. Foy, M. Tallon, A. Migus
With the present state of technology, the tilt component of a aberrated stellar wavefront which has been distorted by atmospheric turbulence cannot be ascertained by an artificial guide star. The absolute position of the artificial guide star cannot be determined since it wanders on the uplink portion of its propagation and there is no way, at least with a single receiving telescope, to distinguish an undetermined position of a guide star from tilt in the wavefront. In conventional adaptive optics systems, a natural star is needed to supply the tilt information in addition to the higher order corrections supplied by an artificial guide star. The probability of finding a suitably bright natural guide star for tilt correction is not significantly higher than for higher order correction despite the fact that the entire telescope area is used and both the tilt anisoplanatic angle and integration time are considerably larger. Since the tilt contributes ≈90% of the phase variance, the accuracy in the tilt measurement has to be much greater than for higher order corrections1. In particular at galactic latitudes above the galactic plane, or at visible wavelengths, the sky coverage for a tilt star becomes unacceptable for most applications.
{"title":"First Results of a Polychromatic Artificial Sodium Star for the Correction of Tilt","authors":"H. Friedman, R. Foy, M. Tallon, A. Migus","doi":"10.1364/adop.1996.amb.27","DOIUrl":"https://doi.org/10.1364/adop.1996.amb.27","url":null,"abstract":"With the present state of technology, the tilt component of a aberrated stellar wavefront which has been distorted by atmospheric turbulence cannot be ascertained by an artificial guide star. The absolute position of the artificial guide star cannot be determined since it wanders on the uplink portion of its propagation and there is no way, at least with a single receiving telescope, to distinguish an undetermined position of a guide star from tilt in the wavefront. In conventional adaptive optics systems, a natural star is needed to supply the tilt information in addition to the higher order corrections supplied by an artificial guide star. The probability of finding a suitably bright natural guide star for tilt correction is not significantly higher than for higher order correction despite the fact that the entire telescope area is used and both the tilt anisoplanatic angle and integration time are considerably larger. Since the tilt contributes ≈90% of the phase variance, the accuracy in the tilt measurement has to be much greater than for higher order corrections1. In particular at galactic latitudes above the galactic plane, or at visible wavelengths, the sky coverage for a tilt star becomes unacceptable for most applications.","PeriodicalId":256393,"journal":{"name":"Adaptive Optics","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129487761","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 : 1996-03-05DOI: 10.1364/adop.1996.amb.28
H. Friedman, B. Macintosh
For laser guide star installations above a few watts in average power, the irradiance of the beam exceeds the ANSI1 standards for eye safety and an aircraft detection system is required to insure that pilots or passengers are not blinded. Even for powers lower than this level, numerous incidents of temporary flash blindness have been observed2 and pose a threat to the safety of aircraft. LLNL has deployed two laser guide star systems3,4 and has obtained permits from the Federal Aviation Association which insure safe operation of these lasers. These aircraft detection systems use a combination of a rotating search radar, a narrow angle, boresight radar and visual observers to provide a triple layer of detection, each with its own access to the laser safety shutter.
{"title":"Design of an Infrared Camera Based Aircraft Dectection System for Laser Guide Star Installations","authors":"H. Friedman, B. Macintosh","doi":"10.1364/adop.1996.amb.28","DOIUrl":"https://doi.org/10.1364/adop.1996.amb.28","url":null,"abstract":"For laser guide star installations above a few watts in average power, the irradiance of the beam exceeds the ANSI1 standards for eye safety and an aircraft detection system is required to insure that pilots or passengers are not blinded. Even for powers lower than this level, numerous incidents of temporary flash blindness have been observed2 and pose a threat to the safety of aircraft. LLNL has deployed two laser guide star systems3,4 and has obtained permits from the Federal Aviation Association which insure safe operation of these lasers. These aircraft detection systems use a combination of a rotating search radar, a narrow angle, boresight radar and visual observers to provide a triple layer of detection, each with its own access to the laser safety shutter.","PeriodicalId":256393,"journal":{"name":"Adaptive Optics","volume":"26 6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130414401","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}
H. Friedman, G. Erbert, T. Kuklo, T. Salmon, Gary R. Thompson, N. Wong, J. G. Malik
Laser generated guide stars in the mesosphere at 90 km provide an effective beacon for adaptive optics schemes which compensate the effects of atmospheric turbulence. Atomic sodium, the species with the highest product of integrated density and cross section, requires an exciting laser with a stable wavelength of 589 nm, a spectral bandwidth of ≈3 GHz and a peak power incident on the mesosphere of ≤5 W/cm2 in order to reduce the effects of saturation. There are several other attributes of the laser which are desirable from a point of view of overall adaptive optics system performance and operation ease. These include the following: (1) near diffraction limited beam quality which is needed to make a small laser guide star, (2) pointing accuracy in the arcsecond range with resolution in the subarcsecond range, (3) the ability to detune the laser for background subtraction or retune to another wavelength for polychromatic guide stars1, (4) a configuration which simplifies the laser projection optics and does not require beam paths through the telescope bearings and (5) an effective method of removing waste head from the laser before it enters the dome volume. Finally, while lasers with average power in the ten watt range may be sufficient for observations in the near IR, extension to visible observations will require multiple guide stars with total powers in the hundred watt range. Therefore the ability to scale up in power by an order of magnitude in a straightforward manner is certainly desirable.
{"title":"Laser Systems for the Generation of Sodium Layer Guide Stars","authors":"H. Friedman, G. Erbert, T. Kuklo, T. Salmon, Gary R. Thompson, N. Wong, J. G. Malik","doi":"10.1364/adop.1996.amc.2","DOIUrl":"https://doi.org/10.1364/adop.1996.amc.2","url":null,"abstract":"Laser generated guide stars in the mesosphere at 90 km provide an effective beacon for adaptive optics schemes which compensate the effects of atmospheric turbulence. Atomic sodium, the species with the highest product of integrated density and cross section, requires an exciting laser with a stable wavelength of 589 nm, a spectral bandwidth of ≈3 GHz and a peak power incident on the mesosphere of ≤5 W/cm2 in order to reduce the effects of saturation. There are several other attributes of the laser which are desirable from a point of view of overall adaptive optics system performance and operation ease. These include the following: (1) near diffraction limited beam quality which is needed to make a small laser guide star, (2) pointing accuracy in the arcsecond range with resolution in the subarcsecond range, (3) the ability to detune the laser for background subtraction or retune to another wavelength for polychromatic guide stars1, (4) a configuration which simplifies the laser projection optics and does not require beam paths through the telescope bearings and (5) an effective method of removing waste head from the laser before it enters the dome volume. Finally, while lasers with average power in the ten watt range may be sufficient for observations in the near IR, extension to visible observations will require multiple guide stars with total powers in the hundred watt range. Therefore the ability to scale up in power by an order of magnitude in a straightforward manner is certainly desirable.","PeriodicalId":256393,"journal":{"name":"Adaptive Optics","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129319173","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}
A prototype adaptive optics system has been developed at Lawrence Livermore National Laboratory (LLNL) for use on the 3-m Shane telescope at Lick Observatory. This system is currently based on a 127-actuator continuous-surface deformable mirror developed at LLNL, a high-quantum-efficiency low-noise fast CCD camera built for LLNL by Adaptive Optics Associates using a chip developed by Lincoln Laboratory, and a Mercury VME board containing four Intel i860 processors.
{"title":"Initial results from the Lick Observatory laser guide star adaptive optics system","authors":"S. Olivier, J. An, K. Avicola","doi":"10.2172/114020","DOIUrl":"https://doi.org/10.2172/114020","url":null,"abstract":"A prototype adaptive optics system has been developed at Lawrence Livermore National Laboratory (LLNL) for use on the 3-m Shane telescope at Lick Observatory. This system is currently based on a 127-actuator continuous-surface deformable mirror developed at LLNL, a high-quantum-efficiency low-noise fast CCD camera built for LLNL by Adaptive Optics Associates using a chip developed by Lincoln Laboratory, and a Mercury VME board containing four Intel i860 processors.","PeriodicalId":256393,"journal":{"name":"Adaptive Optics","volume":"117 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134401928","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}
H. Friedman, G. Erbert, D. Gavel, T. Kuklo, J. G. Malik, J. Salmon, D. Smauley, Gary R. Thompson, J. Wong
The use of sodium-layer laser guide stars for adaptive optics systems greatly enhances the sky coverage as compared to systems using natural guide stars. In order to demonstrate the feasibility of a sodium-layer guide star, a 20 W pulsed dye laser system has been designed and installed on the 3 meter Shane telescope at the Lick Observatory, Mt. Hamilton, California. The adaptive optics system used in conjunction with the laser guide star system has been described elsewhere1 and has already demonstrated diffraction limited images at the 2.2 micron wavelength using natural guide stars. The integration of the sodium laser guide star and the adaptive optics systems represents the first such installation on an astronomical telescope.
{"title":"A Sodium Guide Star Laser System for the Lick Observatory 3 Meter Telescope","authors":"H. Friedman, G. Erbert, D. Gavel, T. Kuklo, J. G. Malik, J. Salmon, D. Smauley, Gary R. Thompson, J. Wong","doi":"10.1364/adop.1995.tua28","DOIUrl":"https://doi.org/10.1364/adop.1995.tua28","url":null,"abstract":"The use of sodium-layer laser guide stars for adaptive optics systems greatly enhances the sky coverage as compared to systems using natural guide stars. In order to demonstrate the feasibility of a sodium-layer guide star, a 20 W pulsed dye laser system has been designed and installed on the 3 meter Shane telescope at the Lick Observatory, Mt. Hamilton, California. The adaptive optics system used in conjunction with the laser guide star system has been described elsewhere1 and has already demonstrated diffraction limited images at the 2.2 micron wavelength using natural guide stars. The integration of the sodium laser guide star and the adaptive optics systems represents the first such installation on an astronomical telescope.","PeriodicalId":256393,"journal":{"name":"Adaptive Optics","volume":"55 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128925651","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.6
T. Rimmele, R. Radick
The Sun presents unusual problems for wavefront sensing. Unlike the nighttime sky, the Sun does not provide natural, high-contrast point sources, and creation of laser beacons bright enough to be visible against the solar disk poses major technical and operational problems. Small sunspots and pores can provide satisfactory substitutes for point sources, but these are available for only a tiny fraction of the solar disk. Wavefront sensing at arbitrary locations on the Sun requires a sensor capable of using the ubiquitous solar granulation as its target. Solar granulation is extended (its characteristic angular scale is about one arcsecond), unbounded (the angular extent of the composite granulation pattern greatly exceeds the isoplanatic angle), low contrast (a few percent), and both spatially and temporally variable (the typical evolution time scale is minutes). Conventional wavefront sensors such as shearing interferometers and simple Shack-Hartmann position sensors have difficulty dealing with targets having these characteristics, and therefore are not well-suited for general solar imaging.
{"title":"Experimental Comparison of Two Approaches for Solar Wavefront Sensing","authors":"T. Rimmele, R. Radick","doi":"10.1364/adop.1996.athc.6","DOIUrl":"https://doi.org/10.1364/adop.1996.athc.6","url":null,"abstract":"The Sun presents unusual problems for wavefront sensing. Unlike the nighttime sky, the Sun does not provide natural, high-contrast point sources, and creation of laser beacons bright enough to be visible against the solar disk poses major technical and operational problems. Small sunspots and pores can provide satisfactory substitutes for point sources, but these are available for only a tiny fraction of the solar disk. Wavefront sensing at arbitrary locations on the Sun requires a sensor capable of using the ubiquitous solar granulation as its target. Solar granulation is extended (its characteristic angular scale is about one arcsecond), unbounded (the angular extent of the composite granulation pattern greatly exceeds the isoplanatic angle), low contrast (a few percent), and both spatially and temporally variable (the typical evolution time scale is minutes). Conventional wavefront sensors such as shearing interferometers and simple Shack-Hartmann position sensors have difficulty dealing with targets having these characteristics, and therefore are not well-suited for general solar imaging.","PeriodicalId":256393,"journal":{"name":"Adaptive Optics","volume":"10 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":"115314441","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.awd.18
V. Lukin, B. Fortes
It is pertinent to note that the applications of adaptive optics (AO) for implementation of the total potential of such a high-power telescope as AST-10 imposes heavy demands on the quality of production, adjustment and phasing of a primary mirror (PM). The atmospheric turbulence was a controlling factor of the image quality for previous generations of telescopes.
{"title":"Phasing of Elements of a Primary Mirror of AST-10","authors":"V. Lukin, B. Fortes","doi":"10.1364/adop.1996.awd.18","DOIUrl":"https://doi.org/10.1364/adop.1996.awd.18","url":null,"abstract":"It is pertinent to note that the applications of adaptive optics (AO) for implementation of the total potential of such a high-power telescope as AST-10 imposes heavy demands on the quality of production, adjustment and phasing of a primary mirror (PM). The atmospheric turbulence was a controlling factor of the image quality for previous generations of telescopes.","PeriodicalId":256393,"journal":{"name":"Adaptive Optics","volume":"23 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":"115467281","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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