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1.3 PHYSICAL SCIENCES, Optics
Twisted nematic liquid crystal spatial light modulators, (SLM) are widely used for amplitude modulation of light. The technique for measuring phase and amplitude modulation introduced by a twisted nematic cell is not new but the novelty here is that after characterisation of a Holoeye LC2002 TNLC device we were able to identify specific conditions that allow for its use as a pure 180 degree or more, phase modulator with little or no amplitude modulation at 514.5 nm laser wavelength. The phase shift introduced by the SLM was measured using a Mach-Zehnder interferometer. The experimentally measured and the theoretically predicted intensity transmission and phase shift as functions of gray levels, are compared. Finally, the effects of errors in the angular settings of the polarizers and quarter waveplates on the intensity transmission and phase shift are studied.
Mahmud, M., Naydenova, I. & Toal, V. (2008) Implementation of phase-only modulation utilizing a twisted nematic liquid crystal spatial light modulator. Journal of Optics A: Pure and Applied Optics, Vol. 10, No. 8, 10 085007. doi:10.1088/1464-4258/10/8/085007