Overview of the SAPHIRA detector for adaptive optics applications

Goebel, Sean; Hall, Donald N. B.; Guyon, Olivier; Warmbier, Eric; Jacobson, Shane

doi:10.1117/1.jatis.4.2.026001

Cited by 20 publications

(23 citation statements)

References 27 publications

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“…The measured excess noise factor is close to unity and the avalanche gain process is almost noiseless because HgCdTe is a direct semiconductor. For near infrared control loops the SAPHIRA eAPD arrays are mature devices with unmatched performance [21].…”

Section: Test Resultsmentioning

confidence: 99%

“…The electron avalanche photodiodes improved the sensitivity for fringe tracking by more than 2 magnitudes. The limiting magnitude for coherent exposures with GRAVITY is mK~17this sets a new sensitivity standard in infrared interferometry, made possible by the deployment of eAPD technology, which is now widely being used in near infrared interferometry and for wavefront sensing [9] [21].…”

Section: On-sky Performance Of Saphira In Gravitymentioning

confidence: 99%

“…Therefore, ESO funded the development of the near infrared SAPHIRA 320x256 pixel e-APD arrays at LEONARDO [3][4][5][6] [7]. SAPHIRA arrays have now become the devices of choice for control loops with unsurpassed performance [21]. This has also been demonstrated by the four wavefront sensors and the fringe tracker deployed in the VLTI instrument GRAVITY which set a new sensitivity standard in infrared interferometry [8] [9].…”

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On-sky performance verification of near infrared eAPD technology for wavefront sensing at ground based telescopes, demonstration of e-APD pixel performance to improve the sensitivity of large science focal planes and possibility to use this technology in space

Finger

Baker

Álvarez

et al. 2019

International Conference on Space Optics — ICSO 2018

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On-sky performance verification of near infrared eAPD technology for wavefront sensing at ground based telescopes, demonstration of e-APD pixel performance to improve the sensitivity of large science focal planes and possibility to use this technology in G. FingerABSTRACT Ground based near infrared adaptive optics as well as fringe tracking for coherent beam combination in optical interferometry required the development of high-speed sensors. Because of the high speed, a large analog bandwidth is needed. The short exposure times result in small signal levels which require noiseless detection. Both of these conflicting requirements cannot be met by state-of-the-art conventional CMOS technology of near infrared arrays as has been attempted previously[1] [2]. The HgCdTe electron avalanche photo diode (eAPD) technology is the only way to overcome the limiting CMOS noise barrier of near infrared sensors. Therefore, ESO funded the development of the near infrared SAPHIRA 320x256 pixel e-APD arrays at LEONARDO [3][4][5][6] [7]. SAPHIRA arrays have now become the devices of choice for control loops with unsurpassed performance [21]. This has also been demonstrated by the four wavefront sensors and the fringe tracker deployed in the VLTI instrument GRAVITY which set a new sensitivity standard in infrared interferometry [8] [9]. It has also been demonstrated that APD arrays have extremely low dark current (1E-3 electrons/s/pixel) and may outperform conventional CMOS arrays for 100 second integrations when operated with moderate APD gains. For AO systems of extremely large telescopes and for co-phasing segmented mirror telescopes larger formats are needed. Therefore, a 512x512 pixel SAPHIRA array with 64 parallel video outputs optimized for pyramid wavefront sensing is in development. Since the SAPHIRA array has successfully passed radiation hardness testing it soon may be used for future instruments in space. Apart from the large array common voltage for high APD gain it can also be operated with voltages compatible with the space qualified SIDECAR ASIC [10].

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Section: Test Resultsmentioning

confidence: 99%

Section: On-sky Performance Of Saphira In Gravitymentioning

confidence: 99%

mentioning

confidence: 99%

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On-sky performance verification of near infrared eAPD technology for wavefront sensing at ground based telescopes, demonstration of e-APD pixel performance to improve the sensitivity of large science focal planes and possibility to use this technology in space

Finger

Baker

Álvarez

et al. 2019

International Conference on Space Optics — ICSO 2018

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“…In addition, for groundbased instruments, we require very fast (several kHz) frame rates, at least for the wavefront sensor cameras, but preferentially also for the science cameras. The SAPHIRA detector 27 and its C-RED One incarnation offer low-noise, high-speed operation, thanks to a an avalanche photodiode array. These are now the detectors of choice for wavefront sensing in ground-based instruments.…”

Section: Detectorsmentioning

confidence: 99%

Review of high-contrast imaging systems for current and future ground-based and space-based telescopes III: technology opportunities and pathways

Snik

Absil

Baudoz

et al. 2018

Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation III

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The Optimal Optical Coronagraph Workshop at the Lorentz Center in September 2017 in Leiden, the Netherlands gathered a diverse group of 25 researchers working on exoplanet instrumentation to stimulate the emergence and sharing of new ideas. This contribution is the final part of a series of three papers summarizing the outcomes of the workshop, and presents an overview of novel optical technologies and systems that are implemented or considered for high-contrast imaging instruments on both ground-based and space telescopes. The overall objective of high contrast instruments is to provide direct observations and characterizations of exoplanets at contrast levels as extreme as 10 −10 . We list shortcomings of current technologies, and identify opportunities and development paths for new technologies that enable quantum leaps in performance. Specifically, we discuss the design and manufacturing of key components like advanced deformable mirrors and coronagraphic optics, and their amalgamation in "adaptive coronagraph" systems. Moreover, we discuss highly integrated system designs that combine contrast-enhancing techniques and characterization techniques (like high-resolution spectroscopy) while minimizing the overall complexity. Finally, we explore extreme implementations using all-photonics solutions for ground-based telescopes and dedicated huge apertures for space telescopes.

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“…On all nights, the SAPHIRA detector was operated in "read-reset" mode, wherein each line was read once and then reset. This enabled a maximum effective frame rate, optimal duty cycle, and full use of the dynamic range per image (Goebel et al 2018). We later collected dark/bias frames and subtracted these in order to remove the detector's pedestal pixel-by-pixel offset pattern.…”

Section: Experimental Setup and Observationsmentioning

confidence: 99%

Measurements of Speckle Lifetimes in Near-infrared Extreme Adaptive Optics Images for Optimizing Focal Plane Wavefront Control

Goebel¹,

Guyon²,

Hall³

et al. 2018

PASP

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Although extreme adaptive optics (ExAO) systems can greatly reduce the effects of atmospheric turbulence and deliver diffraction-limited images, our ability to observe faint objects such as extrasolar planets or debris disks at small angular separations is greatly limited by the presence of a speckle halo caused by imperfect wavefront corrections. These speckles change with a variety of timescales, from milliseconds to many hours, and various techniques have been developed to mitigate them during observations and during data reduction. Detection limits improve with increased speckle reduction, so an understanding of how speckles evolve (particularly at near-infrared wavelengths, which is where most adaptive optics science instruments operate) is of distinct interest. We used a SAPHIRA detector behind Subaru Telescope's SCExAO instrument to collect H-band images of the ExAO-corrected PSF at a frame rate of 1.68 kHz. We analyzed these images using two techniques to measure the timescales over which the speckles evolved. In the first technique, we analyzed the images in a manner applicable to predicting performance of real-time speckle nulling loops. We repeated this analysis using data from several nights to account for varying weather and AO conditions. In our second analysis, which follows the techniques employed by Milli et al. (2016) but using data with three orders of magnitude better temporal resolution, we identified a new regime of speckle behavior that occurs at timescales of milliseconds. It is not purely an instrument effect and likely is an atmospheric timescale filtered by the ExAO response. We also observed an exponential decay in the Pearson's correlation coefficients (which we employed to quantify the change in speckles) on timescales of seconds and a linear decay on timescales of minutes, which is in agreement with the behavior observed by Milli et al. For both of our analyses, we also collected similar datasets using SCExAO's internal light source to separate atmospheric effects from instrumental effects.

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Overview of the SAPHIRA detector for adaptive optics applications

Cited by 20 publications

References 27 publications

On-sky performance verification of near infrared eAPD technology for wavefront sensing at ground based telescopes, demonstration of e-APD pixel performance to improve the sensitivity of large science focal planes and possibility to use this technology in space

On-sky performance verification of near infrared eAPD technology for wavefront sensing at ground based telescopes, demonstration of e-APD pixel performance to improve the sensitivity of large science focal planes and possibility to use this technology in space

Review of high-contrast imaging systems for current and future ground-based and space-based telescopes III: technology opportunities and pathways

Measurements of Speckle Lifetimes in Near-infrared Extreme Adaptive Optics Images for Optimizing Focal Plane Wavefront Control

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