Chromaticity and luminous efficiency of phase imaging systems

The luminous efficiency, obtained with white light readout of phase grating light valves, is practically equivalent to the diffraction efficiency. However, due to the spectrally selective nature of the grating, the resulting image has been found to suffer from strong chromatic shifts. A method of correcting this is described in which chromatic filters are used in the spatial frequency plane in order to produce black-and-white images at maximum efficiency. The results presented include the luminous efficiency, and the chromaticity coordinates as a function of deformation amplitude for CIE illuminant A, a tungsten source at 2854 K, and CIE illuminant C, average daylight, and a useful approximation to a Xenon arc lamp.