A 260 megapixel visible/NIR mixed technology focal plane for space

Abstract

Mission concepts for NASA's Wide Field Infrared Survey Telescope (WFIRST)^1,2, ESA's Euclid^3,4 mission, as well as next-generation ground-based surveys require large mosaic focal planes sensitive in both visible and near infrared (NIR) wavelengths. We have developed space-qualified detectors, readout electronics and focal plane design techniques that can be used to intermingle CCDs and NIR detectors on a single, silicon carbide (SiC) cold plate. This enables optimized, wideband observing strategies. The CCDs, developed at Lawrence Berkeley National Laboratory, are fully-depleted, pchannel devices that are backside illuminated and capable of operating at temperatures down to 120K. The NIR detectors are 1.7 μm and 2.0 μm wavelength cutoff H2RG® HgCdTe, manufactured by Teledyne Imaging Sensors under contract to LBNL. Both the CCDs and NIR detectors are packaged on 4-side abuttable SiC pedestals with a common mounting footprint supporting a 44 mm mosaic pitch. Both types of detectors have direct-attached readout electronics that convert the detector signal directly to serial, digital data streams and allow a flexible, low cost data acquisition strategy to enable large data rates. A mosaic of these detectors can be operated at a common temperature that achieves the required dark current and read noise performance necessary for dark energy observations. We report here the qualification testing and performance verification for a focal plane that accommodates a 4x8 array of CCDs and HgCdTe detectors.