OPTICAL DENSITY (OD)

For a given wavelength , an expression of the transmittance of an optical element. Note 1: Optical density is expressed by log 10 (1/ T ) where T is transmittance. ( 188 ) Note 2: The higher the optical density, the lower the transmittance. Note 3: Optical density times 10 is equal to transmission loss expressed in decibels, e.g. , an optical density of 0.3 corresponds to a transmission loss of 3 dB .