What is reflectance in the context of luminance and illumination?

In the context of luminance and illumination, reflectance specifically refers to the ratio of incident light to reflected light. This ratio indicates how much of the light that strikes a surface is reflected back from that surface. Reflectance is crucial in understanding how surfaces interact with light and can significantly affect visual perception, energy efficiency, and safety in environments.

Luminance involves the amount of light that passes through or is emitted from a particular area in a given direction, while illumination pertains to the amount of light arriving at a surface. Understanding reflectance helps in calculating how much light is available or usable in a given environment based on the properties of the surface.

Thus, focusing on the correct ratio, reflectance provides insights into the effectiveness of a surface in reflecting light, which is crucial for designing lighting and for assessing environmental conditions in industrial hygiene.