Thermal Sensors: Bolometers

This lecture covers the principles of thermal sensors, focusing on bolometers. The temperature variation is measured by the resistance variation of the thermally insulated sensor. The infrared radiation is absorbed on a resistive thermal sensor, isolated from its support. The lecture discusses the thermal conductance, time constant, sensitivity, and equivalent thermal model of bolometers. It also explores the response to a jump in intensity, frequency response, and sensitivity of infrared cameras. The ultimate resolution limit of bolometers and the types of cryogenic bolometers used in astronomy are explained, including resistance bolometers and superconducting bolometers. The construction and detection mechanisms of superconducting cryogenic bolometers are detailed.