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Bad Pixel Mapping

Smith, Roger M. and Hale, David and Wizinowich, Peter (2014) Bad Pixel Mapping. In: High Energy, Optical, and Infrared Detectors for Astronomy VI. Proceedings of SPIE. No.9154. Society of Photo-Optical Instrumentation Engineers , Bellingham, WA, Art. No. 915417. ISBN 978-0-8194-9622-5.

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Bad pixels are generally treated as a loss of useable area and then excluded from averaged performance metrics. The definition and detection of “bad pixels” or “cosmetic defects” are seldom discussed, perhaps because they are considered self-evident or of minor consequence for any scientific grade detector, however the ramifications can be more serious than generally appreciated. While the definition of pixel performance is generally understood, the classification of pixels as useable is highly application-specific, as are the consequences of ignoring or interpolating over such pixels. CMOS sensors (including NIR detectors) exhibit less compact distributions of pixel properties than CCDs. The extended tails in these distributions result in a steeper increase in bad pixel counts as performance thresholds are tightened which comes as a surprise to many users. To illustrate how some applications are much more sensitive to bad pixels than others, we present a bad pixel mapping exercise for the Teledyne H2RG used as the NIR tip-tilt sensor in the Keck-1 Adaptive Optics system. We use this example to illustrate the wide range of metrics by which a pixel might be judged inadequate. These include pixel bump bond connectivity, vignetting, addressing faults in the mux, severe sensitivity deficiency of some pixels, non linearity, poor signal linearity, low full well, poor mean-variance linearity, excessive noise and high dark current. Some pixels appear bad by multiple metrics. We also discuss the importance of distinguishing true performance outliers from measurement errors. We note how the complexity of these issues has ramifications for sensor procurement and acceptance testing strategies.

Item Type:Book Section
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Wizinowich, Peter0000-0002-1646-442X
Additional Information:© 2014 SPIE.
Series Name:Proceedings of SPIE
Issue or Number:9154
Record Number:CaltechAUTHORS:20150615-143348390
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Official Citation:Roger M. Smith ; David Hale ; Peter Wizinowich; Bad pixel mapping. Proc. SPIE 9154, High Energy, Optical, and Infrared Detectors for Astronomy VI, 915417 (July 23, 2014); doi:10.1117/12.2057694
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:58260
Deposited By: Tony Diaz
Deposited On:15 Jun 2015 21:43
Last Modified:10 Nov 2021 22:02

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