The high T/sub c/ superconducting bolometer

A description is given of the optimization of a bolometric infrared detector which uses the resistive transition of a high-T/sub c/ film as the thermometer. The performance of an LN (Liquid nitrogen)-cooled far-infrared bolometer operated with a cooled low-pass filter is computed for the ideal case of a noise-free readout. The theory is then extended to include various contributions to the readout noise. Measurements are presented of the low frequency noise near T/sub c/ in current-biased films of ErBa/sub 2/Cu/sub 3/O/sub 7/, which show that useful performance can be achieved. Comparisons are made with other infrared detection technologies which show that practical high T/sub c/ bolometers will be especially useful for wavelengths longer than the -20 mu m cutoff of LN-cooled photovoltaic detectors. Potential applications include far-infrared laboratory spectroscopy and passively cooled space observations of bright sources such as the earth.<
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