Daylight reflectance, visible light reflectance, luminous reflectance, and light reflectance value: are they the same?

Related services Glass optical & thermal properties, Daylight reflectance, Luminance contrast

They are the same in physical meaning: all of them are quantities representing the fraction of visible light reflected by a surface.

For general applications, the results are equivalent. For example: 0.50 (50%) of daylight reflectance = 0.50 (50%) of visible light reflectance = 0.50 (50%) of luminous reflectance = 50 of light reflectance value (LRV).

In practice, there are some subtle differences in the test results, due to the different test methods used. Below are the practices implemented in our lab:

Most of the time, the results obtained with different methods are very close (typically less than ±0.01 of variation).