Wavelength dependence of twisted nematic liquid crystal phase modulators

Many twisted nematic liquid crystal spatial light modulators suffer from limited phase modulation capability and coupled amplitude modulation. In particular, a phase modulation capability of less than 2π radians is a severe limitation. Phase modulation is wavelength dependent. We examine the effect of changing the operating wavelength on the phase and amplitude modulation characteristics of a commercial liquid crystal spatial light modulator. Comparisons are made with a double pass configuration which can also increase the phase modulation capability.