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1 January 2010 Fine-pitch high-efficiency spatial optical modulator for mobile display applications
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Diffractive spatial optical modulators (SOM) employing a fine-pitch pixel array were introduced. The micromechanical designs of the lead zirconate titanate (PZT) actuator and mirror ribbon structure were optimized for a small volume while maintaining the same level of performance. The same design rule and fabrication equipment were used for a new 10-µm-pitch and conventional 16-µm-pitch SOM. The optical efficiency of the new SOM was 78% (zeroth-order diffraction), which is an improvement over that of the 16-µm-pitch SOM (73%). The full on/off contrast ratio showed no differences, and a high displacement of 500 nm was achieved. The stress of the Pt/PZT/Pt actuating layer was the main parameter affecting the initial gap height and displacement of the ribbon. The required ribbon flatness could be achieved by applying a stress gradient on the SiN layer. The temperature-sensitive characteristics, which degrade image quality, could be minimized by a mechanical compensation method that takes advantage of the thermal expansion effect of Si substrates. The estimated lifetime of the device is >4000 h. The developed fine-pitch SOM device has sufficient response time and ribbon displacement to be suitable for high-quality embedded laser-projection displays. The VGA optical module was successfully demonstrated in a mobile laser projection display.
©(2010) Society of Photo-Optical Instrumentation Engineers (SPIE)
Jong Hyeong Song, Sang Kyeong Yun, Hee-Yeoun Kim, Seungdo An, Heung-Woo Park, Yoon Joon Choi, Victor Yurlov, Anatoly Stepanovych Lapchuk, Chung Mo Yang, Sung Jun Lee, Jae Wook Jang, Ki Un Lee, Ki Suk Woo, and El Mostafa Bourim "Fine-pitch high-efficiency spatial optical modulator for mobile display applications," Journal of Micro/Nanolithography, MEMS, and MOEMS 9(1), 013026 (1 January 2010).
Published: 1 January 2010

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