Uncooled Microbolometer Infrared Sensor Arrays

The first man-made infrared (IR) sensor was a thermometer, demonstrated by Herschel in 1800 [1]. Such an IR sensor is now termed a “thermal” sensor, since it operates by sensing the temperature rise caused by absorbed infrared radiation (in contrast to other types of infrared detectors [2] which operate at fixed temperatures). Figure 1 shows the fundamental form of a thermal IR sensor: an IR-absorbing plate (area A) is suspended from a large thermal mass (supporting substrate) by supporting “legs”. The supporting legs are long and narrow, and are made from a material with low thermal conductivity, so that the IR heat energy dissipated in the IR-absorbing plate does not quickly leak away to the supporting substrate. Some type of temperature-sensitive device is placed on the absorbing plate, to measure the temperature changes produced by incident infrared radiation.