Pub Date : 2024-07-01DOI: 10.1117/1.jatis.10.3.039001
Jalo Nousiainen, Juha-Pekka Puska, Tapio Helin, Nuutti Hyvönen, Markus Kasper
Time delay error is a significant error source in adaptive optics (AO) systems. It arises from the latency between sensing the wavefront and applying the correction. Predictive control algorithms reduce the time delay error, providing significant performance gains, especially for high-contrast imaging. However, the predictive controller’s performance depends on factors such as the wavefront sensor (WFS) type, the measurement noise level, the AO system’s geometry, and the atmospheric conditions. We study the limits of prediction under different imaging conditions through spatiotemporal Gaussian process models. The method provides a predictive reconstructor that is optimal in the least-squares sense, conditioned on the fixed times series of WFS data and our knowledge of the atmospheric conditions. We demonstrate that knowledge is power in predictive AO control. With a Shack–Hartmann sensor-based extreme AO instrument, perfect knowledge of the wind and atmospheric profile and exact frozen flow evolution lead to a reduction of the residual wavefront phase variance up to a factor of 3.5 compared with a non-predictive approach. If there is uncertainty in the profile or evolution models, the gain is more modest. Still, assuming that only effective wind speed is available (without direction) led to reductions in variance by a factor of ∼2.3. We also study the value of data for predictive filters by computing the experimental utility for different scenarios to answer questions such as how many past telemetry frames should the prediction filter consider and whether is it always most advantageous to use the most recent data. We show that within the scenarios considered, more data provide a consistent increase in prediction accuracy. Furthermore, we demonstrate that given a computational limitation on how many past frames, we can use an optimized selection of n past frames, which leads to a 10% to 15% additional improvement in root mean square over using the n latest consecutive frames of data.
时延误差是自适应光学（AO）系统中的一个重要误差源。它产生于感测波前和应用校正之间的延迟。预测控制算法可减少时延误差，显著提高性能，尤其是在高对比度成像方面。然而，预测控制器的性能取决于波前传感器（WFS）类型、测量噪声水平、AO 系统的几何形状和大气条件等因素。我们通过时空高斯过程模型研究了不同成像条件下的预测极限。根据 WFS 数据的固定时间序列和我们对大气条件的了解，该方法提供了最小二乘意义上的最优预测重构器。我们证明了在预测性 AO 控制中，知识就是力量。利用基于夏克-哈特曼传感器的极端定向仪，与非预测方法相比，对风和大气剖面的完美了解以及精确的冻结流演变可将残余波前相位差降低 3.5 倍。如果剖面或演变模型存在不确定性，则收益会更小。不过，假设只有有效风速（没有风向），方差还是减少了 2.3 倍。我们还研究了预测滤波器的数据价值，计算了不同情况下的实验效用，以回答预测滤波器应考虑多少个过去的遥测帧，以及使用最新数据是否总是最有利等问题。我们的研究表明，在所考虑的各种情况下，更多的数据可以持续提高预测精度。此外，我们还证明，考虑到对过去帧数的计算限制，我们可以使用 n 个过去帧数的优化选择，这比使用 n 个最新连续帧数据的均方根提高了 10%-15%。
{"title":"Power of prediction: spatiotemporal Gaussian process modeling for predictive control in slope-based wavefront sensing","authors":"Jalo Nousiainen, Juha-Pekka Puska, Tapio Helin, Nuutti Hyvönen, Markus Kasper","doi":"10.1117/1.jatis.10.3.039001","DOIUrl":"https://doi.org/10.1117/1.jatis.10.3.039001","url":null,"abstract":"Time delay error is a significant error source in adaptive optics (AO) systems. It arises from the latency between sensing the wavefront and applying the correction. Predictive control algorithms reduce the time delay error, providing significant performance gains, especially for high-contrast imaging. However, the predictive controller’s performance depends on factors such as the wavefront sensor (WFS) type, the measurement noise level, the AO system’s geometry, and the atmospheric conditions. We study the limits of prediction under different imaging conditions through spatiotemporal Gaussian process models. The method provides a predictive reconstructor that is optimal in the least-squares sense, conditioned on the fixed times series of WFS data and our knowledge of the atmospheric conditions. We demonstrate that knowledge is power in predictive AO control. With a Shack–Hartmann sensor-based extreme AO instrument, perfect knowledge of the wind and atmospheric profile and exact frozen flow evolution lead to a reduction of the residual wavefront phase variance up to a factor of 3.5 compared with a non-predictive approach. If there is uncertainty in the profile or evolution models, the gain is more modest. Still, assuming that only effective wind speed is available (without direction) led to reductions in variance by a factor of ∼2.3. We also study the value of data for predictive filters by computing the experimental utility for different scenarios to answer questions such as how many past telemetry frames should the prediction filter consider and whether is it always most advantageous to use the most recent data. We show that within the scenarios considered, more data provide a consistent increase in prediction accuracy. Furthermore, we demonstrate that given a computational limitation on how many past frames, we can use an optimized selection of n past frames, which leads to a 10% to 15% additional improvement in root mean square over using the n latest consecutive frames of data.","PeriodicalId":54342,"journal":{"name":"Journal of Astronomical Telescopes Instruments and Systems","volume":"49 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141611364","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-01DOI: 10.1117/1.jatis.10.3.039002
Yesh Pal, Naveen Kumar Mishra, Naimesh R. Patel, Neeraj Mathur, Shaunak R. Joshi
The goal of deformable mirrors (DMs) is to correct aberrated optical wavefronts in spaceborne electro-optical (EO) payloads. It is used as part of an active/adaptive optics system. A continuous-surface, metal-based DM is highly reliable and less complex to assemble, has better stability of the active surface, is less expensive, and can be manufactured quickly. In addition, metal DM with actuation away from the active surface makes the overall configuration scalable. Continuing our previous work on deformable metal mirrors, this work presents the design, validation, and qualification of an aluminum DM using 25 piezoelectric actuators, which include an actuator in the center of the mirror, to improve the spherical aberration correction accuracy. The optomechanical design and analysis of the deformable mirror assembly (DMA) are also presented for performance and survival loads. Later, a qualification model (QM) was built with vacuum-compatible closed-loop piezoelectric actuators. The correction accuracy was demonstrated at the QM by correcting aberrations in the mirror itself. The QM was successfully tested in the space environment in the ThermoVac for operating temperature limits of 20°C±5°C and demonstrated survivability for storage temperature limits of 20°C±40°C. Likewise, the survivability of QM for launch environments such as sinusoidal and random vibration loads is demonstrated. The successful completion of all these tests has improved the maturity of this technology to the technology readiness level of 7 and is now ready to be configured for the appropriate spaceborne EO payload.
{"title":"Design and qualification of an aluminum deformable mirror for spaceborne electro-optical payloads","authors":"Yesh Pal, Naveen Kumar Mishra, Naimesh R. Patel, Neeraj Mathur, Shaunak R. Joshi","doi":"10.1117/1.jatis.10.3.039002","DOIUrl":"https://doi.org/10.1117/1.jatis.10.3.039002","url":null,"abstract":"The goal of deformable mirrors (DMs) is to correct aberrated optical wavefronts in spaceborne electro-optical (EO) payloads. It is used as part of an active/adaptive optics system. A continuous-surface, metal-based DM is highly reliable and less complex to assemble, has better stability of the active surface, is less expensive, and can be manufactured quickly. In addition, metal DM with actuation away from the active surface makes the overall configuration scalable. Continuing our previous work on deformable metal mirrors, this work presents the design, validation, and qualification of an aluminum DM using 25 piezoelectric actuators, which include an actuator in the center of the mirror, to improve the spherical aberration correction accuracy. The optomechanical design and analysis of the deformable mirror assembly (DMA) are also presented for performance and survival loads. Later, a qualification model (QM) was built with vacuum-compatible closed-loop piezoelectric actuators. The correction accuracy was demonstrated at the QM by correcting aberrations in the mirror itself. The QM was successfully tested in the space environment in the ThermoVac for operating temperature limits of 20°C±5°C and demonstrated survivability for storage temperature limits of 20°C±40°C. Likewise, the survivability of QM for launch environments such as sinusoidal and random vibration loads is demonstrated. The successful completion of all these tests has improved the maturity of this technology to the technology readiness level of 7 and is now ready to be configured for the appropriate spaceborne EO payload.","PeriodicalId":54342,"journal":{"name":"Journal of Astronomical Telescopes Instruments and Systems","volume":"14 8 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141869153","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-01DOI: 10.1117/1.jatis.10.3.030301
Tom Patton, Kevin France, Arika Egan
The National Aeronautics and Space Administration’s (NASA) first dedicated exoplanetary spectroscopy mission, the Colorado Ultraviolet Transit Experiment (CUTE), is used to search for signatures of atmospheric escape, the process by which constituent gases depart a planetary atmosphere. Through transit spectroscopy, the signs of escape driven by the high level of ultraviolet (UV) radiation from their parent stars are detectable around close-in planets. CUTE is a 6U CubeSat developed and operated by the Laboratory for Atmospheric and Space Physics (LASP) of the University of Colorado in Boulder, Colorado, United States; it looks for these signs of escape by surveying close-in extrasolar planets in the near-UV (2479 to 3306 Å) with 208×84 mm Cassegrain telescope-fed, UV-enhanced charged coupled device. Funded through a NASA ROSES proposal in 2017 and forced to deal with a worldwide pandemic during the heart of its fabrication and test program, CUTE has demonstrated the capability of small satellites to launch on schedule and perform challenging astronomical measurements. We will highlight the CUTE mission’s science objectives, implementation, and tribulations on its road to delivering a successful science program while discussing lessons learned pertaining to the development of CubeSat programs and the application of those lessons for a CUTE-style follow-on mission in the future.
{"title":"Colorado Ultraviolet Transit Experiment: a mission development history and future possibilities from the National Aeronautics and Space Administration’s first ultraviolet astronomy CubeSat","authors":"Tom Patton, Kevin France, Arika Egan","doi":"10.1117/1.jatis.10.3.030301","DOIUrl":"https://doi.org/10.1117/1.jatis.10.3.030301","url":null,"abstract":"The National Aeronautics and Space Administration’s (NASA) first dedicated exoplanetary spectroscopy mission, the Colorado Ultraviolet Transit Experiment (CUTE), is used to search for signatures of atmospheric escape, the process by which constituent gases depart a planetary atmosphere. Through transit spectroscopy, the signs of escape driven by the high level of ultraviolet (UV) radiation from their parent stars are detectable around close-in planets. CUTE is a 6U CubeSat developed and operated by the Laboratory for Atmospheric and Space Physics (LASP) of the University of Colorado in Boulder, Colorado, United States; it looks for these signs of escape by surveying close-in extrasolar planets in the near-UV (2479 to 3306 Å) with 208×84 mm Cassegrain telescope-fed, UV-enhanced charged coupled device. Funded through a NASA ROSES proposal in 2017 and forced to deal with a worldwide pandemic during the heart of its fabrication and test program, CUTE has demonstrated the capability of small satellites to launch on schedule and perform challenging astronomical measurements. We will highlight the CUTE mission’s science objectives, implementation, and tribulations on its road to delivering a successful science program while discussing lessons learned pertaining to the development of CubeSat programs and the application of those lessons for a CUTE-style follow-on mission in the future.","PeriodicalId":54342,"journal":{"name":"Journal of Astronomical Telescopes Instruments and Systems","volume":"33 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141548745","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-01DOI: 10.1117/1.jatis.10.3.035001
Niyati Desai, Axel Potier, Susan F. Redmond, Garreth Ruane, Phillip K. Poon, A. J. Eldorado Riggs, Matthew Noyes, Camilo Mejia Prada
Future space telescope coronagraph instruments hinge on the integration of high-performance masks and precise wavefront sensing and control techniques to create dark holes essential for exoplanet detection. Recent advancements in wavefront control algorithms might exhibit differing performances depending on the coronagraph used. This research investigates three model-free and model-based algorithms in conjunction with either a vector vortex coronagraph or a scalar vortex coronagraph under identical laboratory conditions: pairwise probing with electric field conjugation, the self-coherent camera with electric field conjugation, and implicit electric field conjugation. We present experimental results in narrowband and broadband light from the In-Air Coronagraph Testbed at the Jet Propulsion Laboratory. We find that model-free dark hole digging methods achieve broadband contrasts comparable to model-based methods, and we highlight the calibration costs of model-free methods compared with model-based approaches. This study also reports the first time that electric field conjugation with the self-coherent camera has been applied for simultaneous multi-subband correction with a field stop. This study compares the advantages and disadvantages of each of these wavefront sensing and control algorithms with respect to their potential for future space telescopes.
{"title":"Comparative laboratory study of electric field conjugation algorithms","authors":"Niyati Desai, Axel Potier, Susan F. Redmond, Garreth Ruane, Phillip K. Poon, A. J. Eldorado Riggs, Matthew Noyes, Camilo Mejia Prada","doi":"10.1117/1.jatis.10.3.035001","DOIUrl":"https://doi.org/10.1117/1.jatis.10.3.035001","url":null,"abstract":"Future space telescope coronagraph instruments hinge on the integration of high-performance masks and precise wavefront sensing and control techniques to create dark holes essential for exoplanet detection. Recent advancements in wavefront control algorithms might exhibit differing performances depending on the coronagraph used. This research investigates three model-free and model-based algorithms in conjunction with either a vector vortex coronagraph or a scalar vortex coronagraph under identical laboratory conditions: pairwise probing with electric field conjugation, the self-coherent camera with electric field conjugation, and implicit electric field conjugation. We present experimental results in narrowband and broadband light from the In-Air Coronagraph Testbed at the Jet Propulsion Laboratory. We find that model-free dark hole digging methods achieve broadband contrasts comparable to model-based methods, and we highlight the calibration costs of model-free methods compared with model-based approaches. This study also reports the first time that electric field conjugation with the self-coherent camera has been applied for simultaneous multi-subband correction with a field stop. This study compares the advantages and disadvantages of each of these wavefront sensing and control algorithms with respect to their potential for future space telescopes.","PeriodicalId":54342,"journal":{"name":"Journal of Astronomical Telescopes Instruments and Systems","volume":"90 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141743288","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-01DOI: 10.1117/1.jatis.10.3.034002
Gagan Agarwal, Naimesh R. Patel, Neeraj Mathur, Shaunak R. Joshi, Shri Hari Satheeshkumar
The mirror repositioning system is one critical system in large-size deployable space telescopes that aids in correcting errors in mirror orientation once deployed. Stewart mechanism is employed for reorienting the mirror due to its potential for use in high-precision applications, and a high-range and high-accuracy Stewart platform for positioning the mirror was designed using dual-resolution actuators. System characterization is crucial for understanding, optimizing, and evaluating the performance of a system. It provides insight into a system’s behavior, strengths, weaknesses, and limitations, aiding in troubleshooting, design decisions, and quality assurance. Overall, it forms the foundation for ensuring the functionality, efficiency, and reliability of a system throughout its lifecycle. We discuss the techniques adopted for characterizing the mirror repositioning system and the methods employed for error reduction in the system.
{"title":"Characterization technique for high-resolution mirror repositioning hexapod mechanism for space telescopes","authors":"Gagan Agarwal, Naimesh R. Patel, Neeraj Mathur, Shaunak R. Joshi, Shri Hari Satheeshkumar","doi":"10.1117/1.jatis.10.3.034002","DOIUrl":"https://doi.org/10.1117/1.jatis.10.3.034002","url":null,"abstract":"The mirror repositioning system is one critical system in large-size deployable space telescopes that aids in correcting errors in mirror orientation once deployed. Stewart mechanism is employed for reorienting the mirror due to its potential for use in high-precision applications, and a high-range and high-accuracy Stewart platform for positioning the mirror was designed using dual-resolution actuators. System characterization is crucial for understanding, optimizing, and evaluating the performance of a system. It provides insight into a system’s behavior, strengths, weaknesses, and limitations, aiding in troubleshooting, design decisions, and quality assurance. Overall, it forms the foundation for ensuring the functionality, efficiency, and reliability of a system throughout its lifecycle. We discuss the techniques adopted for characterizing the mirror repositioning system and the methods employed for error reduction in the system.","PeriodicalId":54342,"journal":{"name":"Journal of Astronomical Telescopes Instruments and Systems","volume":"40 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141779783","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-01DOI: 10.1117/1.jatis.10.2.026007
Naidu Bezawada, Derek Ives, Elizabeth George, Domingo Alvarez, Benoit Serra, Mark Farris, Anders Petersen, Liz Corrales
The Hawaii-4RG near-infrared detectors offer several output configurations in which the detectors can be interfaced with the European Southern Observatory cryogenic preamplifiers. The buffered mode of output operation has the advantages of higher speed and lower electrical crosstalk between the outputs, reduced unit cell current, etc. One of the effects of the buffered mode operation is increased glow at the bottom of the array due to the operation of the output buffers compared to the unbuffered mode. The excess glow can be a limiting source to achieve low noise in long integrations using the up-the-ramp sampling readout mode. The glow can be significantly reduced by optimally biasing the output buffer stages. This work presents the output buffer glow issue, its quantification in terms of glow per read, glow per unit integration time, its dependency on pixel speed, and its mitigation by optimization of buffered mode operation.
{"title":"Output buffer glow and its mitigation in H4RG-15 detectors","authors":"Naidu Bezawada, Derek Ives, Elizabeth George, Domingo Alvarez, Benoit Serra, Mark Farris, Anders Petersen, Liz Corrales","doi":"10.1117/1.jatis.10.2.026007","DOIUrl":"https://doi.org/10.1117/1.jatis.10.2.026007","url":null,"abstract":"The Hawaii-4RG near-infrared detectors offer several output configurations in which the detectors can be interfaced with the European Southern Observatory cryogenic preamplifiers. The buffered mode of output operation has the advantages of higher speed and lower electrical crosstalk between the outputs, reduced unit cell current, etc. One of the effects of the buffered mode operation is increased glow at the bottom of the array due to the operation of the output buffers compared to the unbuffered mode. The excess glow can be a limiting source to achieve low noise in long integrations using the up-the-ramp sampling readout mode. The glow can be significantly reduced by optimally biasing the output buffer stages. This work presents the output buffer glow issue, its quantification in terms of glow per read, glow per unit integration time, its dependency on pixel speed, and its mitigation by optimization of buffered mode operation.","PeriodicalId":54342,"journal":{"name":"Journal of Astronomical Telescopes Instruments and Systems","volume":"14 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141506967","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
An exoplanet survey with a near-infrared Doppler (IRD) instrument focused on mid-to-late M-type dwarfs began in February 2019 within the framework of the Subaru Strategic Program. Because mid-to-late M-type dwarfs are brighter in the infrared region than in the visible region, a laser frequency comb (LFC) system was developed as a wavelength reference, covering the near-infrared region from 970 to 1750 nm. To stabilize the comb image on the spectrometer, the original 12.5 GHz comb generated using highly nonlinear fibers was injected into the spectrometer after optical processing, including spectral shaping, depolarization, and mode scrambling. An inline fiber module was introduced to enable any optical system configuration for the optical processor. This fiber-optic configuration in the LFC system allows for long-term stability and easy repair. Moreover, simple remote control of the LFC system using an interactive program enabled LFC generation in approximately 5 min, excluding warm-up time. The observations using the IRD instrument over 4 years have proven that our LFC system is practical and stable. The LFC system operated stably without major problems during this period, helping to maintain a high radial velocity accuracy.
{"title":"Laser frequency comb system for the infrared Doppler instrument on the Subaru Telescope","authors":"Takuma Serizawa, Takashi Kurokawa, Yosuke Tanaka, Jun Nishikawa, Takayuki Kotani, Motohide Tamura","doi":"10.1117/1.jatis.10.2.025006","DOIUrl":"https://doi.org/10.1117/1.jatis.10.2.025006","url":null,"abstract":"An exoplanet survey with a near-infrared Doppler (IRD) instrument focused on mid-to-late M-type dwarfs began in February 2019 within the framework of the Subaru Strategic Program. Because mid-to-late M-type dwarfs are brighter in the infrared region than in the visible region, a laser frequency comb (LFC) system was developed as a wavelength reference, covering the near-infrared region from 970 to 1750 nm. To stabilize the comb image on the spectrometer, the original 12.5 GHz comb generated using highly nonlinear fibers was injected into the spectrometer after optical processing, including spectral shaping, depolarization, and mode scrambling. An inline fiber module was introduced to enable any optical system configuration for the optical processor. This fiber-optic configuration in the LFC system allows for long-term stability and easy repair. Moreover, simple remote control of the LFC system using an interactive program enabled LFC generation in approximately 5 min, excluding warm-up time. The observations using the IRD instrument over 4 years have proven that our LFC system is practical and stable. The LFC system operated stably without major problems during this period, helping to maintain a high radial velocity accuracy.","PeriodicalId":54342,"journal":{"name":"Journal of Astronomical Telescopes Instruments and Systems","volume":"22 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140927721","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-01DOI: 10.1117/1.jatis.10.2.029002
Joshua Liberman, Jorge Llop-Sayson, Arielle Bertrou-Cantou, Dimitri Mawet, Niyati Desai, Sebastiaan Y. Haffert, A. J. Eldorado Riggs
Connecting a coronagraph instrument to a spectrograph via a single-mode optical fiber is a promising technique for characterizing the atmospheres of exoplanets with ground and space-based telescopes. However, due to the small separation and extreme flux ratio between planets and their host stars, instrument sensitivity will be limited by residual starlight leaking into the fiber. To minimize stellar leakage, we must control the electric field at the fiber input. Implicit electric field conjugation (iEFC) is a model-independent wavefront control (WFC) technique in contrast with classical EFC, which requires a detailed optical model of the system. We present here the concept of an iEFC-based WFC algorithm to improve stellar rejection through a single-mode fiber (SMF). As opposed to image-based iEFC, which relies on minimizing intensity in a dark hole region, our approach aims to minimize the amount of residual starlight coupling into an SMF. We present broadband simulation results demonstrating a normalized intensity ≥10−10 for both fiber-based EFC and iEFC. We find that both control algorithms exhibit similar performance for the low wavefront error (WFE) case, however, iEFC outperforms EFC by ≈100x in the high WFE regime. Having no need for an optical model, this fiber-based approach offers a promising alternative to EFC for ground and space-based telescope missions, particularly in the presence of residual WFE.
{"title":"Implicit electric field conjugation through a single-mode fiber","authors":"Joshua Liberman, Jorge Llop-Sayson, Arielle Bertrou-Cantou, Dimitri Mawet, Niyati Desai, Sebastiaan Y. Haffert, A. J. Eldorado Riggs","doi":"10.1117/1.jatis.10.2.029002","DOIUrl":"https://doi.org/10.1117/1.jatis.10.2.029002","url":null,"abstract":"Connecting a coronagraph instrument to a spectrograph via a single-mode optical fiber is a promising technique for characterizing the atmospheres of exoplanets with ground and space-based telescopes. However, due to the small separation and extreme flux ratio between planets and their host stars, instrument sensitivity will be limited by residual starlight leaking into the fiber. To minimize stellar leakage, we must control the electric field at the fiber input. Implicit electric field conjugation (iEFC) is a model-independent wavefront control (WFC) technique in contrast with classical EFC, which requires a detailed optical model of the system. We present here the concept of an iEFC-based WFC algorithm to improve stellar rejection through a single-mode fiber (SMF). As opposed to image-based iEFC, which relies on minimizing intensity in a dark hole region, our approach aims to minimize the amount of residual starlight coupling into an SMF. We present broadband simulation results demonstrating a normalized intensity ≥10−10 for both fiber-based EFC and iEFC. We find that both control algorithms exhibit similar performance for the low wavefront error (WFE) case, however, iEFC outperforms EFC by ≈100x in the high WFE regime. Having no need for an optical model, this fiber-based approach offers a promising alternative to EFC for ground and space-based telescope missions, particularly in the presence of residual WFE.","PeriodicalId":54342,"journal":{"name":"Journal of Astronomical Telescopes Instruments and Systems","volume":"33 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141150383","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-01DOI: 10.1117/1.jatis.10.2.026005
Yuuki Wada, Philippe Laurent, Damien Pailot, Ion Cojocari, Eric Bréelle, Stéphane Colonges, Jean-Pierre Baronick, François Lebrun, Pierre-Louis Blelly, David Sarria, Kazuhiro Nakazawa, Miles Lindsey-Clark
We developed the X-ray, gamma-ray, and relativistic electron detector (XGRE) onboard the Tool for the Analysis of RAdiation from lightNIngs and Sprites (TARANIS) satellite, to investigate high-energy phenomena associated with lightning discharges such as terrestrial gamma-ray flashes and terrestrial electron beams. XGRE consisted of three sensors. Each sensor has one layer of LaBr3 crystals for X-ray/gamma-ray detections and two layers of plastic scintillators for electron and charged-particle discrimination. Since 2018, the flight model of XGRE was developed, and validation and calibration tests, such as a thermal cycle test and a calibration test with the sensors onboard the satellite, were performed before the launch of TARANIS on 17 November 2020. The energy range of the LaBr3 crystals sensitive to X-rays and gamma rays was determined to be 0.04 to 11.6 MeV, 0.08 to 11.0 MeV, and 0.08 to 11.3 MeV for XGRE1, 2, and 3, respectively. The energy resolution at 0.662 MeV (full width at half maximum) was 20.5%, 25.9%, and 28.6%, respectively. The results from the calibration test were then used to validate a simulation model of XGRE and TARANIS. By performing Monte Carlo simulations with the verified model, we calculated effective areas of XGRE to X-rays, gamma rays, electrons, and detector responses to incident photons and electrons coming from various elevation and azimuth angles.
{"title":"On-ground calibration of the X-ray, gamma-ray, and relativistic electron detector onboard TARANIS","authors":"Yuuki Wada, Philippe Laurent, Damien Pailot, Ion Cojocari, Eric Bréelle, Stéphane Colonges, Jean-Pierre Baronick, François Lebrun, Pierre-Louis Blelly, David Sarria, Kazuhiro Nakazawa, Miles Lindsey-Clark","doi":"10.1117/1.jatis.10.2.026005","DOIUrl":"https://doi.org/10.1117/1.jatis.10.2.026005","url":null,"abstract":"We developed the X-ray, gamma-ray, and relativistic electron detector (XGRE) onboard the Tool for the Analysis of RAdiation from lightNIngs and Sprites (TARANIS) satellite, to investigate high-energy phenomena associated with lightning discharges such as terrestrial gamma-ray flashes and terrestrial electron beams. XGRE consisted of three sensors. Each sensor has one layer of LaBr3 crystals for X-ray/gamma-ray detections and two layers of plastic scintillators for electron and charged-particle discrimination. Since 2018, the flight model of XGRE was developed, and validation and calibration tests, such as a thermal cycle test and a calibration test with the sensors onboard the satellite, were performed before the launch of TARANIS on 17 November 2020. The energy range of the LaBr3 crystals sensitive to X-rays and gamma rays was determined to be 0.04 to 11.6 MeV, 0.08 to 11.0 MeV, and 0.08 to 11.3 MeV for XGRE1, 2, and 3, respectively. The energy resolution at 0.662 MeV (full width at half maximum) was 20.5%, 25.9%, and 28.6%, respectively. The results from the calibration test were then used to validate a simulation model of XGRE and TARANIS. By performing Monte Carlo simulations with the verified model, we calculated effective areas of XGRE to X-rays, gamma rays, electrons, and detector responses to incident photons and electrons coming from various elevation and azimuth angles.","PeriodicalId":54342,"journal":{"name":"Journal of Astronomical Telescopes Instruments and Systems","volume":"16 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140884415","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Accurate solar observation plays a vital role in space weather prediction. Aditya-L1, ISRO’s first solar observatory mission, carried a Visible Emission Line Coronagraph (VELC) instrument. This instrument provides observations very close to the solar limb with internal occultation. We provide design and development details of detector electronics for continuum, two spectroscopic channels and one spectro-polarimetry channel of the VELC instrument. The developed hardware with imaging detectors (sCMOS in visible and InGaAs in near-infrared spectral region) has very high sensitivity (noise equivalent signal = 0.2 photon/s/pixel). The instrument has onboard intelligence for detection of coronal mass ejection events. Photon-noise-limited detector electronics are developed and qualified for all four channels. Dark noise of ≈1.2e− with dark signal ≈0.035e−/p/s was achieved. Detector electronics cater to very high input dynamic range >120 dB. Stringent contamination control protocols were evolved and implemented during all stages of development. The uniqueness of the VELC instrument is that it makes observations very close to the solar limb (1.05 R) as well as magnetic field measurements and has simultaneous spectroscopic and imaging capability.
{"title":"Detector electronics for visible emission line coronagraph payload of Aditya-L1","authors":"Ashok Kumar, Rajiv Kumaran, Jalshri Desai, Namita Singh, Ravi Kumar, Anuj Srivastava, Nandha P. Kumar, Vivek Gupta, Dhrupesh Shah, Jitendra Kumar, Sanjay Gupta","doi":"10.1117/1.jatis.10.2.026004","DOIUrl":"https://doi.org/10.1117/1.jatis.10.2.026004","url":null,"abstract":"Accurate solar observation plays a vital role in space weather prediction. Aditya-L1, ISRO’s first solar observatory mission, carried a Visible Emission Line Coronagraph (VELC) instrument. This instrument provides observations very close to the solar limb with internal occultation. We provide design and development details of detector electronics for continuum, two spectroscopic channels and one spectro-polarimetry channel of the VELC instrument. The developed hardware with imaging detectors (sCMOS in visible and InGaAs in near-infrared spectral region) has very high sensitivity (noise equivalent signal = 0.2 photon/s/pixel). The instrument has onboard intelligence for detection of coronal mass ejection events. Photon-noise-limited detector electronics are developed and qualified for all four channels. Dark noise of ≈1.2e− with dark signal ≈0.035e−/p/s was achieved. Detector electronics cater to very high input dynamic range >120 dB. Stringent contamination control protocols were evolved and implemented during all stages of development. The uniqueness of the VELC instrument is that it makes observations very close to the solar limb (1.05 R) as well as magnetic field measurements and has simultaneous spectroscopic and imaging capability.","PeriodicalId":54342,"journal":{"name":"Journal of Astronomical Telescopes Instruments and Systems","volume":"22 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140839513","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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