Superconducting Transition Edge Sensor Bolometer Arrays for Submillimeter Astronomy

Studies of astrophysical emission in the far-infrared and submillimeter will increasingly require large arrays of detectors containing hundreds to thousands of elements. The last few years have seen the increasing from one to a few tens of bolometers on ground-based telescopes. A further jump of this magnitude, to a thousand bolometers, requires a fundamental redesign of the technology of making bolometer arrays. One method of achieving this increase is to design bolometers which can be packed into a rectangular array of near-unity filling factor while Nyquist-sampling the focal plane of the telescope at the operating wavelengths. In this case, the array becomes more nearly analogous to the arrays used in the near-infrared which underwent a substantial growth during the last decade. A multiplexed readout is necessary for this many detectors, and can be developed using SQUIDs such that a 32×32 array of bolometers could be read out using 100 wires rather than the >2000 needed with a brute force expansion of existing arrays. Superconducting transition edge sensors are used as the detectors for these bolometer arrays. We describe a collaborative effort currently underway at NASA/Goddard and NIST to bring about the first astronomically useful arrays of this design, containing tens of bolometers. This technology is well-suited to low-background instruments such as SPIRE on FIRST and SAFIRE on SOFIA, and can also be used in broadband, high-background instruments such as HAWC on SOFIA.