Share Email Print

Proceedings Paper

Photon counting arrays for AO wavefront sensors
Author(s): John Vallerga; Anton Tremsin; Jason McPhate; Bettina Mikulec; Allan Clark; Oswald Siegmund
Format Member Price Non-Member Price
PDF $14.40 $18.00
cover GOOD NEWS! Your organization subscribes to the SPIE Digital Library. You may be able to download this paper for free. Check Access

Paper Abstract

Future wavefront sensors for AO on large telescopes will require a large number of pixels and must operate at high frame rates. Unfortunately for CCDs, there is a readout noise penalty for operating faster, and this noise can add up rather quickly when considering the number of pixels required for the extended shape of a sodium laser guide star observed with a large telescope. Imaging photon counting detectors have zero readout noise and many pixels, but have suffered in the past with low QE at the longer wavelengths (> 500 nm). Recent developments in GaAs photocathode technology, CMOS ASIC readouts and FPGA processing electronics have resulted in noiseless WFS detector designs that are competitive with silicon array detectors, though at ~ 40% the QE of CCDs. We review noiseless array detectors and compare their centroiding performance with CCDs using the best available characteristics of each. We show that for sub-aperture binning of 6x6 and greater that noiseless detectors have a smaller centroid error at fluences of 60 photons or less, though the specific number is dependent on seeing conditions and the centroid algorithm used. We then present the status of a 256x256 noiseless MCP/Medipix2 hybrid detector being developed for AO.

Paper Details

Date Published: 25 August 2005
PDF: 11 pages
Proc. SPIE 5903, Astronomical Adaptive Optics Systems and Applications II, 59030M (25 August 2005); doi: 10.1117/12.620295
Show Author Affiliations
John Vallerga, Univ. of California/Berkeley (United States)
Anton Tremsin, Univ. of California/Berkeley (United States)
Jason McPhate, Univ. of California/Berkeley (United States)
Bettina Mikulec, Univ. of Geneva (Switzerland)
Allan Clark, Univ. of Geneva (Switzerland)
Oswald Siegmund, Univ. of California/Berkeley (United States)

Published in SPIE Proceedings Vol. 5903:
Astronomical Adaptive Optics Systems and Applications II
Robert K. Tyson; Michael Lloyd-Hart, Editor(s)

© SPIE. Terms of Use
Back to Top