Measurement of the spatial phase modulation of a ferroelectric liquid-crystal modulator

Ferroelectric liquid crystal is used as a dynamic light-wave phase modulator. A device that performs phase-only modulation is investigated, especially with regard to the boundary effect caused by the inevitable gap between controlling electrodes. The dependence of cell retardation and polarizer alignment is discussed. Two phase-retrieving algorithms are used to determine the complex Lightwave front after traversing the device. In operation it was found that the electrode gap region was partly controlled.