This International Standard gives rules for the measurement of the spectral reflectance of plane surfaces and spectral transmittance of plane parallel elements using spectrophotometers over the spectral range 190 nm to 25 μm.

The transmittanceτ and the reflectanceρ of optical components are generally divided into two parts as follows:

This International Standard applies only to measurements of the regular transmittance and the regular reflectance; it does not apply to those of the diffuse transmittance and the diffuse reflectance.

This International Standard is applicable to test specimens which are coated or uncoated optical components without optical power.