David J. Gulbransen

Teledyne Imaging Sensors: infrared imaging technologies for astronomy and civil space

Teledyne Imaging Sensors develops and produces high performance infrared sensors, electronics and packaging for astronomy and civil space. These IR sensors are hybrid CMOS arrays, with HgCdTe used for light detection and a silicon integrated circuit for signal readout. Teledyne manufactures IR sensors in a variety of sizes and formats. Currently, the most advanced sensors are based on the Hawaii-2RG (H2RG), 2K×2K array with 18 μm pixel pitch. The HgCdTe detector achieves very low dark current (<0.01 e-/pixel/sec) and high quantum efficiency (80-90%) over a wide bandpass. Substrate-removed HgCdTe can simultaneously detect visible and infrared light, enabling spectrographs to use a single focal plane array (FPA) for Visible-IR sensitivity. The SIDECARTM ASIC provides focal plane electronics on a chip, operating in cryogenic environments with very low power (<11 mW). The H2RG and SIDECARTM have been qualified to NASA Technology Readiness Level 6 (TRL-6). Teledyne continues to advance the state-of-the-art and is producing a high speed, low noise array designed for IR wavefront sensing. Teledyne is also developing a 4K×4K, 15 µm pixel infrared array that will be a cost effective module for the large focal planes of the Extremely Large Telescopes and future generation space astronomy missions.

2Kx2K HgCdTe detector arrays for VISTA and other applications

The demand for large-format near infrared arrays has grown for both ground-based and space-based applications. These arrays are required for maintaining high resolution over very large fields of view for survey work. We describe results of the development of a new 2048 × 2048 HgCdTe/CdZnTe array with 20-micron pixels that responds with high quantum efficiency over the wavelength range 0.85 to 2.5 microns. With a single-layer anti-reflection coating, the responsive quantum efficiency is greater than 70% from 0.9 micron to 2.4 microns. Dark current is typically less than 4 e-/sec at 80 K. The modular package for this array, dubbed the VIRGO array, allows 3-side butting to form larger mosaic arrays of 4K × 2nK format. The VIRGO ROIC utilizes a PMOS Source Follower per Detector input circuit with a well capacity of about 2 × 105 electrons and with a read noise of less than 20 e- rms with off-chip Correlated Double Sampling. Other features of the VIRGO array include 4 or 16 outputs (programmable), and a frame rate of up to 1.5 Hz in 16-output mode. Power dissipation is about 7 mW at a 1 Hz frame rate. Reset modes include both global reset and reset by row (ripple mode). Reference pixels are built-in to the output data stream. The first major application of the VIRGO array will be for VISTA, the United Kingdom’s Visible and Infrared Survey Telescope for Astronomy. The VISTA focal plane array will operate near 80 K. The cutoff wavelength of the HgCdTe detector can be adjusted for other applications such as SNAP, the Supernova/Acceleration Probe, which requires a shorter detector cutoff wavelength of about 1.7 microns. For applications which require both visible and near infrared response, the detector CdZnTe substrate can be removed after hybridization, allowing the thinned detector to respond to visible wavelengths as short as 0.4 microns.

Illuminating dark energy with the Joint Efficient Dark-energy Investigation (JEDI)

The Universe appears to be expanding at an accelerating rate, driven by a mechanism called Dark Energy. The nature of Dark Energy is largely unknown and needs to be derived from observation of its effects. JEDI (Joint Efficient Dark-energy Investigation) is a candidate implementation of the NASA-DOE Joint Dark Energy Mission (JDEM). It will probe the effects of Dark Energy in three independent ways: (1) using Type Ia supernovae as cosmological standard candles over a range of distances, (2) using baryon acoustic oscillations as a cosmological standard ruler over a range of cosmic epochs, and (3) mapping the weak gravitational lensing distortion by foreground galaxies of the images of background galaxies at different distances. JEDI provides crucial systematic error checks by simultaneously applying these three independent observational methods to derive the Dark Energy parameters. The concordance of the results from these methods will not only provide an unprecedented understanding of Dark Energy, but also indicate the reliability of such an understanding. JEDI will unravel the nature of Dark Energy by obtaining observations only possible from a vantage point in space, coupled with a unique instrument design and observational strategy. Using a 2 meter-class space telescope with simultaneous wide-field imaging (~ 1 deg2, 0.8 to 4.2 μm in five bands) and multi-slit spectroscopy (minimum wavelength coverage 1 to 2 μm), JEDI will efficiently execute the surveys needed to solve the mystery of Dark Energy.

Astronomy FPA advancements at Rockwell Scientific

Advancements in space and ground-based astronomy focal plane array (FPA) technology at Rockwell Scientific Company (RSC) are presented. The review covers the broad base of astronomy work at RSC for both present and next generation FPAs, and details recent achievements in detector, readout, and packaging technologies. RSC astronomy FPA progress includes: RSC FPA delivery for NASAs successful Deep Impact mission, progress on RSCs programs supplying H-2RG FPAs for James Webb Space Telescope (JWST) instruments JWST NIRCam, NIRSpec and FGS; selection of RSCs SIDECAR Application Specific Integrated Circuit (ASIC) for use on JWST instruments NIRCam, NIRSpec and FGS and the development of the JWST SIDECAR space flight package; first silicon on the 16 million pixel HAWAII-4RG (4Kx4K); optimization of NIR FPAs for space telescope missions; construction of multiple 16 million pixel 2x2 mosaic FPAs using the HAWAII-2RG readouts, and the development of the Microlensing Planet Finder (MPF) very large, 150 million pixel FPA.

Overview of Astronomy Arrays at Raytheon Infrared Operations (RIO)

We review the various types of astronomy arrays currently available from RIO for wide-field imaging and spectroscopy. Arrays for infrared astronomy became available from RIO (previously the Santa Barbara Research Center) with the introduction of the 58×62 InSb in 1984. Since the introduction of this first array, RIO has developed and produced increasingly larger format arrays, including the 256×256 InSb array for SIRTF (Space Infrared Telescope Facility) and the Aladdin 1K×1K array. Over 70 Aladdin arrays have been delivered and are currently deployed on a number of major telescopes throughout the world. RIO is currently developing the next generation of 2K×2K format arrays. These include the 2K×2K ORION InSb array, and the VIRGO 2K×K SWIR HgCdTe array for ground-based applications and the 2K×2K InSb array for the NGST program. In addition, RIO is currently developing the next generation large format 1K×1K Si:As Impurity Band Conduction (IBC) arrays for the NGST MIR instrument.

Infrared readout integrated circuit technology for tactical missile systems

The development of the direct injection unit cell architecture with a direct readout has produced several varieties of high-performance large-area staring arrays. These arrays satisfy almost all foreseeable missile applications. The uniformity, noise, and linearity lend themselves to low-complexity, high-performance missile systems. These readout integrated circuits (ROICs) are demonstrated with InSb over a spectral band of 0.5 to 5.5 um with NE(Delta)T of 17 mK under ambient tactical and low-background space conditions. Hybridization of eighteen 128 x 128 ROICs with LWIR HgCdTe resulted in an average NE(Delta)T of 21 mK. The new EPIC substrates yielded high-performance 256 x 256 LWIR HgCdTe capable of withstanding 2000 thermal cycles. The simple interface requirements of the /ST ROIC coupled with the high yield and extremely high operability show promise for future low-cost commercial IR systems.