What is a characteristic feature of thermal detectors?

A characteristic feature of thermal detectors is that they respond to changes in temperature. These detectors operate based on the principle that they measure the thermal energy or heat generated by the absorption of radiation. When thermal energy is absorbed, it causes a change in the temperature of the detector material, which can then be measured and correlated to the intensity of the radiation being detected.

This is unlike detectors designed solely to identify visible light or other types of radiation. Thermal detectors usually rely on heat changes rather than light sensitivity, making it essential for their operation to focus on thermal responses rather than light detection. Additionally, while some types of detectors do require a power supply for their operation, thermal detectors can often function without an external power source once set to ambient temperature, relying instead on the heat generated by incoming radiation.

The linear response is not universally applicable to all thermal detectors; many exhibit non-linear behavior due to varying temperature sensitivities. Therefore, the ability to respond specifically and effectively to temperature changes is what distinctly characterizes thermal detectors.