Bolometers:

Bolometers (bottom two are used in BLAST)

Bolometer detectors have the following favorable properties:

• Large collecting area with low surface area
• Fast response (16-30 ms at 300 mK)
• Can be mass produced in array or as single pixels
• Are tunable over a wide range of frequencies

The BLAST focal plane consists of three bolometer arrays with 149, 88 and 43 detectors at 250, 350, and 500 μm respectively. The silicon-nitride micromesh ("spider-web") bolometric detectors are coupled to the sky with 2fλ feedhorn arrays.

The detectors are read out with an AC-biased differential circuit. The data will be collected using a high-speed, flexible, 18-bit data acquisition system developed at the University of Toronto.