transmittance factor
quotient of the flux transmitted by a specimen in a given optical system and the flux transmitted when the specimen is removed from the sampling aperture
EXAMPLE Comparison of the radiation penetrating a slide situated in a projector and reaching a screen to the radiation when the slide is removed from the projector and only an empty slide mount is in the projector.
Note 1 to entry: The transmittance factor has unit one.
Note 2 to entry: This entry was numbered 17-1338 in CIE S 017:2011.