Photometrische

Photometric (photometrische) refers to photometry, the branch of science concerned with the measurement of light and other radiant energy according to the human eye’s response and optical detectors. The term is used to describe quantities, methods, and instruments that quantify light intensity, flux, or brightness in a given wavelength range or passband.

Key concepts include the distinction between radiometric and photometric measurements. Radiometric quantities (such as radiant flux or irradiance) quantify energy independently of perception, while photometric quantities weight energy by the eye’s luminosity sensitivity. Common photometric units are lumen, candela, and lux, often used in lighting and display contexts.

Photometric systems organize measurements into standardized passbands. In astronomy, common systems include UBVRI and SDSS filters, with magnitudes expressed on logical scales (e.g., apparent or absolute magnitude) and sometimes converted to fluxes. Calibration relies on standard stars and the determination of zero points, extinction coefficients, and color terms to translate instrumental readings into comparable, physical or astronomical magnitudes.

Instrumentation ranges from simple photometers to modern CCD cameras and spectrophotometers. Photometric measurements can be performed with filter-based instruments or spectrophotometry that integrates over wavelengths. Calibration procedures address linearity, detector response, and atmospheric or instrumental effects.

Applications span multiple fields. In astronomy, photometry measures stellar brightness, calibrates observations, and supports concepts such as photometric redshift estimation. In color science and materials testing, photometry informs color coordinates, luminance, and perceived brightness for displays, lighting design, and quality control.

The German term photometrische appears in scientific literature to describe all aspects of these brightness measurements, data processing, and quality assurance processes.