Naohisa MUKOZAKA, Biqing YE¹ and Narihiro YOSHIDA

Central Research Laboratory, Hamamatsu Photonics K.K., 5000 Hirakuchi, Hamakita 434-8601, Japan
¹State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou 310027, China

(Received May 22, 2003; Accepted July 14, 2003)

An optically addressed parallel-aligned nematic-liquid-crystal spatial light modulator (PAL-SLM) has been studied as a dynamic phase-only modulation device. A computer control feature of the spatial light modulator is strongly desired for practical applications. For those demands, an electrically-addressable phase-only spatial light modulator has been developed to combine a liquid crystal display (LCD) with a PAL-SLM (LCD-coupled PAL-SLM) and its performance has been reported. However, a temporal characteristic especially two-dimensional (2D) response has not been discussed before. In this paper, 2D response analysis system has been constructed by using a high-speed complementary Metal-Oxide-Semiconductor (CMOS) camera (1000 frames/sec) and the 2D-modulation characteristic of the LCD-coupled PAL-SLM has been observed. As a result, the LCD has a spatially non-uniform modulation characteristic due to a scanning addressing. It has the potential to cause problems in high speed switching for a computer generated hologram. On the other hand, the spatial non-uniformity has not been observed with the LCD-coupled PAL-SLM.

Key words: spatial light modulator, liquid crystal display, phase-only modulator, phase modulation, amorphous silicon, liquid crystal