Luminance Factor

luminance factor [′lü·mə·nəns ‚fak·tər]

(optics)

The ratio of the luminance of a body when illuminated and observed under certain conditions to that of a perfect diffuser under the same conditions.

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luminance factor

The ratio of the luminance of a surface or medium under specified conditions of incidence, observation, and light source to the luminance of a lossless, perfectly diffusing surface or medium under the same conditions.

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Luminance Factor 

the ratio of the luminance of a body at a certain point and in a given direction to the luminance of a perfect diffuser under the same conditions of illumination. A perfect diffuser is a diffuser whose luminance is the same in all directions and whose reflection coefficient is equal to unity.

The concept of the luminance factor pertains to radiation that is evaluated in either radiometric or photometric units. The respective symbols for the luminance factor are β_e and β_v; the symbol β may be used in either case.

In recent years, the luminance factor has come to be applied not only to the reflection of light but also to the transmission and scattering of light, as well as to thermal radiation.

REFERENCE

Shuba, Iu. A. “Fotometricheskie kharakteristiki veshchestva.” Optiko-mekhanicheskaia promyshlennost’, 1975, no. 12, pp. 7–9.