Reducing the read noise of HAWAII-2RG detector systems with improved reference sampling and subtraction (IRS2)

Abstract

IRS2 is a Wiener-optimal approach to using all of the reference information that Teledyne’s HAWAII-2RG (H2RG) detector array provides. Using a new readout pattern, IRS2 regularly interleaves reference pixels with the normal pixels during readout. This differs from conventional clocking, in which the reference pixels are read out infrequently, and only in a few rows and columns around the outside edges of the detector array. During calibration, the data are processed in Fourier space, which is close to the noise’s eigenspace. Using IRS2, we have reduced the read noise of the James Webb Space Telescope (JWST) Near Infrared Spectrograph’s (NIRSpec) H2RGs by 15% compared to conventional readout. We are attempting to achieve further gains by calibrating out a recently recognized non-stationary noise component that appears at the frame rate. Teledyne’s new HAWAII- 4RGs (H4RG) build in a flexible capability to interleave reference pixels. We eagerly look forward to applying IRS2 techniques to H4RGs when the opportunity arises.