Measurement of the absorption coefficient of the glass substrate of holographic plates

We present a simple method of evaluating the absorption of the glass substr ate of holographic plates which makes use of transmission data. The method is based on the analysis of the transmission of a plane parallel glass plat e as a function of the angle of incidence assuming that multiple interferen ces occur at the plate when it is illuminated with a coherent beam of light from a laser. It is necessary to know the absorption of the glass substrat e in order to be able to correct the data for the transmission and diffract ion efficiencies of holographic diffraction gratings. The agreement between calculated and measured data confirms the applicability of this method.