Optimization of a Cryogenic Transition-Edge Sensor Detector Array for Far-Infrared Astrophysics

We describe the commissioning and operation of a 25 element Transition-Edge Sensor (TES) cryogenic detector array system for use in the far-infrared band of the electromagnetic spectrum. This detector system, supplied by QMC Instruments Limited, is an integral component to the development of a spatial/spectral double Fourier laboratory-based interferometer testbed instrument within the Astronomical Instrumentation Group laboratories at the University of Lethbridge, Canada. The 5x5 rectangular grid of TES elements is feedhorn-coupled and operates at similar to 6K within a dedicated cryostat providing both optical and thermal shielding. Cryogenic cooling of similar to 0.5W is provided by a CryoMech PT405RM/CP2850 pulse-tube cooler/compressor suite. The detector readout system uses time-division multiplexing controlled by a dedicated National Instruments field-programmable gate array board and computer interface. This paper describes the characterization and optimization of this detector system, including the evaluation and validation of the readout electronics, hardware, software, detector noise properties, the multiplexing parameter space, optical sensitivity, and the integration of this system within a laboratory testbed interferometer instrument.