NIRSpec detectors: noise properties and the effect of signal dependent inter-pixel crosstalk

NIRSpec (Near Infrared Spectrograph) is one of the four science instruments of the James Webb Space Telescope (JWST) and its focal plane consists of two HAWAII-2RG sensors operating in the wavelength range 0.6−5.0μm. As part of characterizing NIRSpec, we studied the noise properties of these detectors under dark and illuminated conditions. Under dark conditions, and as already known, 1/f noise in the detector system produces somewhat more noise than can be accounted for by a simple model that includes white read noise and shot noise on integrated charge. More surprisingly, at high flux, we observe significantly lower total noise levels than expected. We show this effect to be due to pixel-to-pixel correlations introduced by signal dependent inter-pixel crosstalk, with an inter-pixel coupling factor, α, that ranges from ~ 0.01 for zero signal to ~ 0.03 close to saturation.

[1]  Zoran Ninkov,et al.  QE Overestimation and Deterministic Crosstalk Resulting from Inter-pixel Capacitance , 2005 .

[2]  Zoran Ninkov,et al.  Interpixel capacitance in nondestructive focal plane arrays , 2004, SPIE Optics + Photonics.

[3]  T. Böker,et al.  The spectro-photometric calibration of the JWST NIRSpec instrument , 2012, Other Conferences.

[4]  David H. Lumb,et al.  The Euclid Mission , 2010, Astronomical Telescopes + Instrumentation.

[5]  Zoran Ninkov,et al.  Quantum efficiency overestimation and deterministic cross talk resulting from interpixel capacitance , 2006 .

[6]  D. J. Fixsen,et al.  Cosmic‐Ray Rejection and Readout Efficiency for Large‐Area Arrays , 2000, astro-ph/0005486.

[7]  Ori D. Fox,et al.  The 55 Fe X-Ray Energy Response of Mercury Cadmium Telluride Near-Infrared Detector Arrays , 2009 .

[8]  Peter Rumler,et al.  The Near Infrared Spectrograph (NIRSpec) on-ground calibration campaign , 2012, Other Conferences.

[9]  Markus Loose,et al.  Reducing the read noise of H2RG detector arrays: eliminating correlated noise with efficient use of reference signals , 2010, Astronomical Telescopes + Instrumentation.

[10]  Markus Loose,et al.  Reducing the read noise of HAWAII-2RG detector systems with improved reference sampling and subtraction (IRS2) , 2012, Other Conferences.

[11]  Markus Loose,et al.  High-performance focal plane arrays based on the HAWAII-2RG/4G and the SIDECAR ASIC , 2007, SPIE Optical Engineering + Applications.

[12]  Markus Loose,et al.  Reducing the read noise of HAWAII-2RG based detector systems with improved reference sampling and subtraction (IRS2) , 2011, Optical Engineering + Applications.

[13]  Peter Rankin McCullough,et al.  Quantum Efficiency and Quantum Yield of an HgCdTe Infrared Sensor Array , 2008 .

[14]  E. al.,et al.  Detectors for the James Webb Space Telescope near-infrared spectrograph. I. Readout mode, noise model, and calibration considerations , 2007, 0706.2344.

[15]  Markus Loose,et al.  James Webb Space Telescope Near-Infrared Spectrograph: dark performance of the first flight candidate detector arrays , 2008, Astronomical Telescopes + Instrumentation.

[16]  Markus Loose,et al.  Teledyne Imaging Sensors: infrared imaging technologies for astronomy and civil space , 2008, Astronomical Telescopes + Instrumentation.