Beam steering with two ferroelectric liquid-crystal spatial light modulators

Ferroelectric liquid-crystal spatial light modulators (FLC SLM's) are binary modulating devices that can be used for flexible beam steering in the microsecond range. Because they are binary, at least 60% of the light power is lost to unwanted diffraction orders, however. We suggest the use of a second FLC SLM, synchronously operating in amplitude-modulating mode, to block the unwanted orders. The proposed beam-steering method is demonstrated in a simple scanner experiment. The efficiency of the suggested beam steerer is independent of the number of steering directions.