A measurement method for the determination of the cell parameters of vertically aligned nematic LCOS devices has been developed. It provides the values for the pre-tilt angle and the cell thickness in a reliable way, without the need for spectroscopic instruments. The method is a single wavelength approach, using oblique incidence to enhance measurement accuracy. The measurement system consists only of a laser source, high quality polarizers, a quarter-wave plate and a sensitive photodiode.