bolometreja

Bolometreja, known in English as a bolometer, is a detector that measures incident electromagnetic radiation by converting part of its energy into heat. The absorbed radiation raises the temperature of a sensitive element, whose electrical properties then produce a measurable signal. Bolometers cover a broad spectral range, from infrared to millimeter wavelengths.

Operating at cryogenic temperatures to minimize heat capacity and noise, bolometers typically include an absorber, a temperature sensor, and a weak thermal link to a heat sink. The output signal is proportional to the absorbed power and is read by electronics that convert a temperature rise into voltage or current.

Main types include resistive bolometers (thermistors and RTDs), superconducting bolometers such as transition-edge sensors (TES) and kinetic inductance detectors (KID), and microbolometers used in uncooled infrared cameras. Each type balances sensitivity, speed, and operating temperature for specific applications.

Applications are strongest in astronomy and cosmology, including observations of faint thermal radiation from stars, galaxies, and the cosmic microwave background, as well as in Earth and planetary remote sensing, spectroscopy, and security imaging. Sensitivity is described by metrics such as noise equivalent power (NEP) and time constant.

History: The bolometer was developed in the late 1870s by Samuel P. Langley to detect infrared radiation. Modern bolometers advance through cryogenic cooling, advanced materials, and microfabrication, achieving high sensitivity for cutting-edge astronomical experiments and practical infrared imaging.