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The Impact of Interpixel Capacitance in CMOS Detectors on PSF Shapes and Implications for WFIRST

Kannawadi, Arun and Shapiro, Charles A. and Mandelbaum, Rachel and Hirata, Christopher M. and Kruk, Jeffrey W. and Rhodes, Jason D. (2016) The Impact of Interpixel Capacitance in CMOS Detectors on PSF Shapes and Implications for WFIRST. Publications of the Astronomical Society of the Pacific, 128 (967). Art. No. 095001. ISSN 0004-6280. doi:10.1088/1538-3873/128/967/095001.

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Unlike optical CCDs, near-infrared detectors, which are based on CMOS hybrid readout technology, typically suffer from electrical crosstalk between the pixels. The interpixel capacitance (IPC) responsible for the crosstalk affects the point-spread function (PSF) of the telescope, increasing the size and modifying the shape of all objects in the images while correlating the Poisson noise. Upcoming weak lensing surveys that use these detectors, such as WFIRST, place stringent requirements on the PSF size and shape (and the level at which these are known), which in turn must be translated into requirements on IPC. To facilitate this process, we present a first study of the effect of IPC on WFIRST PSF sizes and shapes. Realistic PSFs are forward-simulated from physical principles for each WFIRST bandpass. We explore how the PSF size and shape depends on the range of IPC coupling with pixels that are connected along an edge or corner; for the expected level of IPC in WFIRST, IPC increases the PSF sizes by ~5%. We present a linear fitting formula that describes the uncertainty in the PSF size or shape due to uncertainty in the IPC, which could arise for example due to unknown time evolution of IPC as the detectors age or due to spatial variation of IPC across the detector. We also study of the effect of a small anisotropy in the IPC, which further modifies the PSF shapes. Our results are a first, critical step in determining the hardware and characterization requirements for the detectors used in the WFIRST survey.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Mandelbaum, Rachel0000-0003-2271-1527
Hirata, Christopher M.0000-0002-2951-4932
Kruk, Jeffrey W.0000-0002-5861-7236
Rhodes, Jason D.0000-0002-4485-8549
Additional Information:© 2016 The Astronomical Society of the Pacific. Received 2015 December 4; accepted 2016 March 7; published 2016 June 23. The authors thank Roger Smith, Bernard Rauscher, and Andrés Plazas Malagón for many useful discussions and Mike Jarvis and Joshua Meyers for their inputs in developing the GalSim WFIRST module. We thank Edward Cheng of Conceptual Analytics for his comments in improving the manuscript and the referee, David Spergel, for correcting a few minor errors in the original version of the manuscript. This work was carried out in part at the Jet Propulsion Laboratory (JPL), a NASA center run by California Institute of Technology. The authors acknowledge funding from WFIRST study office. CMH is supported by the US Department of Energy, the Packard Foundation, and the Simons Foundation.
Funding AgencyGrant Number
Department of Energy (DOE)UNSPECIFIED
David and Lucile Packard FoundationUNSPECIFIED
Simons FoundationUNSPECIFIED
Subject Keywords:instrumentation: detectors – instrumentation: high angular resolution
Issue or Number:967
Record Number:CaltechAUTHORS:20160729-131908526
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:69320
Deposited By: Tony Diaz
Deposited On:29 Jul 2016 21:14
Last Modified:11 Nov 2021 04:12

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