• Title/Summary/Keyword: 광표백

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A Study on the Holographic Optical Element for Multiple Image Processing (다중 영상처리용 홀로그래피 광학소자에 관한 연구)

  • Kim, Nam
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.17 no.12
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    • pp.1353-1361
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    • 1992
  • Holographic optical element(HOE) is fabricated with the properties of lightweight, thin thickness and interconnectivity for free space. Particularly, HOE for optical interconnection and multiple image processing should have a high efficiency and equal spot intensity, Nonlinear equations for 2-dimensional binary phase grating(BPG) structure is solved by computer simulation based on modified Newton method. Computer-generated pattern drawn by plotter is scaled down and translated into the microfilm. After contact printing between the microfilm and silver halide hologram film, phase diffraction grating produces the $5{\times}5$ multiple spots. Experimental results are shown that bleached phase grating has a high efficiency and equal focused beams except central zero order.

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Stabilization of Output Pulses from a Passively Q-switched Nd:YVO4 Laser Pumped by a Continuous-wave Laser Diode (연속 발진 다이오드 레이저로 여기된 수동형 Q-스위치 Nd:YVO4 레이저의 출력 펄스 안정화)

  • Ahn, Seung-In;Park, Yune-Bae;Yeo, Hwan-Seop;Lee, Joon-Ho;Lee, Kang-In;Yi, Jong-Hoon
    • Korean Journal of Optics and Photonics
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    • v.20 no.5
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    • pp.276-280
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    • 2009
  • A Cr:YAG crystal was used as a saturable absorber for passive Q-switching of a Nd:$YVO_4$ laser which was pumped by a 1-W continuous wave laser diode. The first surface of the Cr:YAG was high-reflection coated for the pump wavelength. The high-reflection coating improved the absorption efficiency of the pump beam in the Nd:$YVO_4$ through double pass absorption. It also prevented pump beam induced partial bleaching of the Cr:YAG. The peak-to-peak pulse fluctuation of passively Q-switched laser output was approximately 4 %. The minimum pulse-width was measured to be 7.11 ns. Also, the average pulse repetition rate was 9 kHz and the maximum output power was 16.27 mW.