Term: radiometry
https://doi.org/10.1351/goldbook.R05115

Definition:
The measurement of quantities associated with radiant energy. The quantities may also describe the variation of the energy with respect to other variables such as wavelength, time, position, direction (solid angle), area normal to the light or projected area of emitting or receiving surfaces. If the light is monochromatic, it is sometimes convenient to replace the radiant energy by the corresponding number of photons (or quanta) which is obtained by dividing the energy by h.c/λ where h is the Planck constant, c the velocity of light and λ the wavelength of the light.

Related Terms:
1) radiant energy (http://doi.org/10.1351/goldbook.R05039).
2) wavelength (http://doi.org/10.1351/goldbook.W06659).
3) angle (http://doi.org/10.1351/goldbook.A00346).
4) planck constant (http://doi.org/10.1351/goldbook.P04685).
5) intensity (http://doi.org/10.1351/goldbook.I03072).
6) irradiance (http://doi.org/10.1351/goldbook.I03254).
7) radiance (http://doi.org/10.1351/goldbook.R05037).

Source: PAC, 1990, 62, 2167. 'Glossary of atmospheric chemistry terms (Recommendations 1990)' on page 2209 (https://doi.org/10.1351/pac199062112167)

Citation: 'radiometry' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.R05115

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