[OPTICAL REVIEW Vol. 5, No. 3 (1998) 174-178]

Phase Modulation Characteristics Analysis of Optically-Addressed Parallel-Aligned Nematic Liquid Crystal Phase-Only Spatial Light Modulator Combined with a Liquid Crystal Display

Fanghong LI,* Naohisa MUKOHZAKA, Narihiro YOSHIDA, Yasunori IGASAKI, Haruyoshi TOYODA, Takashi INOUE, Yuji KOBAYASHI and Tsutomu HARA

Central Research Laboratory, Hamamatsu Photonics K.K., 5000, Hirakuchi, Hamakita, Shizuoka, 434-8601 Japan

(Received December 17, 1997; Accepted March 24, 1998)

An optically addressed parallel-aligned nematic-liquid-crystal spatial light modulator (PAL-SLM) has been studied as a dynamic phase-only light modulation device. The phase modulation characteristics of the PAL-SLM using a liquid crystal display (LCD) as an addressing mask were investigated by analyzing diffraction efficiencies resulting from binary gratings projected from the LCD. A more than 2p phase-only modulation depth was achieved. The highest first-order diffraction efficiency of approximately 38% was also obtained; this is close to the theoretical limit. The experimental results of diffraction efficiencies depending on the phase modulation depth are in good agreement with the simulation for the system operation.

Key words : spatial light modulator, liquid crystal, amorphous silicon, phase modulation, liquid crystal display, diffraction efficiency

* lfhw@crl.hpk.co.jp