Microbolometer technology

A Microbolometer is a specific type of bolometer used as a detector in a thermal camera. It is a grid of vanadium oxide or amorphous silicon heat sensors atop a corresponding grid of silicon. Infrared radiation from a specific range of wavelengths strikes the vanadium oxide and changes its electrical resistance. This resistance change is measured and processed into temperatures which can be represented graphically. The microbolometer grid is commonly found in two sizes, a 320×240 array or less expensive 160×120 array. The schematic structure of an uncooled thermal detector is shown in figure 1.

The most common detection mechanism is the resistive bolometer whose resistance changes with temperature, but various other mechanisms can be used.. Considering a two dimensional array of detectors, a readout integrated circuit (ROIC) is generally designed to measure the resistance of each bolometer and to format the results into a single data stream for video imaging purpose. Finally, due to the strong correlation between thermal insulation and sensitivity, the high performance uncooled IR detector must be operated under vacuum - typically 10-2 Torr .