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From Lab Testing to Science: Applying SAPHIRA HgCdTe L-APD Detectors to Adaptive Optics.

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Title:From Lab Testing to Science: Applying SAPHIRA HgCdTe L-APD Detectors to Adaptive Optics.
Authors:Goebel, Sean B.
Contributors:Astronomy (department)
Date Issued:Aug 2018
Publisher:University of Hawaiʻi at Mānoa
Abstract:Due to their high frame rates, high sensitivity, low noise, and low dark current, SAPHIRA
detectors provide new capabilities for astronomical observations. The SAPHIRA detector
is a 320256@24 m pixel HgCdTe linear avalanche photodiode array manufactured by
Leonardo. It is sensitive to 0:8􀀀2:5 m light. Unlike other near-infrared arrays, SAPHIRA
features a user-adjustable avalanche gain, which multiplies the photon signal but has
minimal impact on the read noise. This enables the equivalent of sub-electron read
noise and therefore photon-counting performance, which has not previously been achieved
with astronomical near-infrared arrays. SAPHIRA is intended for high clocking speeds,
and we developed a new readout controller to utilize this capability and thereby enable
the high frame rates ( 400 Hz for the full frame or 1:7 kHz for a 128128 pixel
subarray). Beginning with the rst science-grade SAPHIRA detectors and continuing with
later improved devices, we deployed SAPHIRAs to the SCExAO instrument at Subaru
Telescope. SCExAO is an extreme adaptive optics instrument intended for observations of
high-contrast objects such as debris disks and extrasolar planets. While at SCExAO, we
demonstrated the ability of SAPHIRA to function as a focal-plane wavefront sensor, and we
performed extensive studies of speckle evolution. Our demonstration of SAPHIRAs ability
to wavefront sense behind pyramid optics contributed to the decision to select a SAPHIRA
detector and pyramid optics for the facility-class Keck Planet Imager. Additionally, we
utilized the high Strehl provided by SCExAO to characterize the morphology of the HIP
79977 debris disk. Due largely to our characterization of the performance of SAPHIRA detectors and our demonstration of their capabilities, numerous facilities throughout the
world have recently proposed to use them in instruments currently in development.
Description:Ph.D. Thesis. University of Hawaiʻi at Mānoa 2018.
Rights:All UHM dissertations and theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission from the copyright owner.
Appears in Collections: Ph.D. - Astronomy

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