Bolometer Array Suitable for 350-µm Astronomy

Researchers at the Jet Propulsion Laboratory and California Institute of Technology in Pasadena, Lawrence Berkeley National Laboratory in Berkeley, Calif., University of Colorado in Boulder and Cardiff University in the UK have developed a micromesh bolometer array for spaceborne astrophysics at 350 µm. The detectors, which they reported in the Oct. 1 issue of Applied Optics, display a dark-noise-equivalent power of 2.9 x 10^-17 W/√Hz and a 1.3-pJ/K mean heat capacity at 390 mK.

The silicon nitride devices feature neutron-transmutation-doped germanium thermistors that are attached with indium bump bonds to the edge of the absorbers using 1 to 2 N of force from a micrometer. The thermistors, as well as the use of lithographically defined electrical leads, reduced heat capacity in the array by 20 times and reduced thermal conductance by 300 times from earlier arrays.