Transition Edge Cameras for Fast Optical Spectrophotometry

Abstract

When one spends 10^8–8.5 euros on a large aperture telescope, it behoves one to make maximal use of the photons concentrated at the focus. One popular path is to use very large focal plane arrays, for a high multiplex advantage; this is a natural driver in extragalactic survey science. The other avenue to efficiency applies to single source science, where a large field of view is not necessary, but energy resolution over a broad wavelength range, high time resolution and, possibly, polarization measurements wring maximum benefit from the collected photons.

Cryogenic energy-resolving sensors are proving to be promising detectors for many areas of astronomy. Significant astronomical observations have, in fact, already been made using two detector schemes: Superconducting Tunnel Junction (STJ) and Transition-Edge Sensor (TES). TES instruments, in particular, have found application as bolometric detectors from the sub-mm to the hard X-ray range. We focus here on TES applications in the near IR through UV, reviewing the basic technology and describing current work toward effective imaging arrays. A TES camera using such arrays can address the need for broad-band single source efficiency at large telescopes noted above. A review of early test observations and a description of a few science goals are presented to illustrate this potential.