A bolometer is a sensitive instrument used to measure the power of incident electromagnetic radiation. It operates by detecting temperature changes that occur when the radiation is absorbed by a material. Typically, a bolometer consists of a temperature-sensitive element, such as a resistive material (like a thin film of metal or a semiconductor), which changes its resistance in response to temperature changes caused by the absorbed radiation.
Bolometers can be used across a wide range of wavelengths, from infrared to microwave frequencies, and are particularly useful in applications like astrophysics, thermal imaging, and radio astronomy. They allow scientists to measure the energy emitted by celestial bodies or other sources of radiation, making them valuable tools for observing and analyzing the universe.