Moiré signal distortion caused by phase and amplitude nonuniformities of light beams

The distortion suffered by the amplitude and phase of a moiré signal when the illuminating beam is not a coherent and monochromatic plane wave has been measured by using different kinds of illuminating sources and a phase-sensitive intensity subtraction technique. A phenomenological model is proposed that explains these effects in terms of an irregular amplitude distribution and a phase evolution of the moiré signal with a grating gap. These effects are of great interest in all the measurement techniques related to the moiré effect, especially when compact light sources such as light-emitting diodes and incandescent lamps are used.