radiometriasta

Radiometry is the science of measuring electromagnetic radiation, independent of how it is perceived by the human eye. It covers the entire spectrum from radio waves to gamma rays and focuses on physical quantities that describe radiant power and its distribution. Core radiometric quantities include radiant flux (the total power in a beam), radiant intensity (power per unit solid angle), irradiance (power arriving on a surface), and radiance (power per unit area per unit solid angle). Spectral forms express these quantities as functions of wavelength, such as spectral irradiance and spectral radiance. Radiometry differs from photometry, which weights radiant power by the eye's sensitivity; radiometry uses true physical power across wavelengths.

Measurement instruments used in radiometry include radiometers, spectroradiometers, bolometers, and photodiode-based detectors. Instruments are calibrated to SI units, with traceability to national or international standards, often using blackbody radiators or calibrated transfer sources. Measurements may be conducted in the laboratory or in the field and require careful consideration of spectral response, angular calibration, and environmental conditions. The distinction between radiometric and photometric calibration is essential in applications like solar energy and remote sensing.

Historically, radiometry emerged in the 19th century with studies of blackbody radiation and the early understanding of radiant power. It underpins many modern technologies and scientific fields, including climate studies, astronomy, and remote sensing, where radiative transfer models describe how light interacts with matter. In industry, radiometry supports sensor calibration, material characterization, and photometric corrections in imaging systems.