Responsivity and detectivity modelling of thermal radiation sensors based on a biased thermocouple

Abstract

Thermal radiation sensors are based on two signal transduction stages: radiation to thermal and thermal to electrical. The most common of these sensors are the radiation thermocouple using the Seebeck effect and the bolometer applying the thermoresistive effect. While the bolometer requires a bias current for signal generation the thermocouple is generally operated unbiased. The paper theoretically investigates a biased thermocouple instead, which can be thought of as a combination of both thermal radiation sensor types. Its responsivity and detectivity are calculated based on previous theories of the performance of bolometers and radiation thermocouples, respectively, thereby including the Peltier effect. The electrical resistance and thermal conductance of the thermocouple as input parameters for these calculations are modelled using a simple strip geometry to facilitate one-dimensional analytical electrothermal modelling.