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    National Tsing Hua University Institutional Repository > 電機資訊學院 > 電機工程學系 > 期刊論文 >  Dual-frequency laser Doppler velocimeter for speckle noise reduction and coherence enhancement

    Please use this identifier to cite or link to this item: http://nthur.lib.nthu.edu.tw/dspace/handle/987654321/83617

    Title: Dual-frequency laser Doppler velocimeter for speckle noise reduction and coherence enhancement
    Authors: C. H. Cheng;C. W. Lee;T. W. Lin;F. Y. Lin
    教師: 林凡異
    Date: 2012
    Publisher: Optical Society of America
    Relation: OPTICS EXPRESS, Optical Society of America, Volume 20, Issue 18, AUG 27 2012, Pages 20255-20265
    Abstract: We study the characteristics of a dual-frequency laser Doppler velocimeter (DF-LDV) based on an optically injected semiconductor laser. The laser operated in a period-one (P1) dynamical state with two optical frequencies separated by 11.25 GHz is used as the dual-frequency light source. With a microwave beat signal carried by the light, the DF-LDV possesses both the advantages of good directionality, high intensity, and high spatial resolution from the light and low speckle noise and good coherence from the microwave, respectively. By phase-locking the two frequency components with a microwave signal, the coherence of the dual-frequency light source can be further improved and the detection range can be much extended. In this paper, velocity resolutions of the DF-LDV with different amounts of speckle noise and at different detection ranges are experimentally measured and analyzed. Compared with the conventional single-frequency LDV (SF-LDV), the velocity resolution of the DF-LDV is improved by 8x10(3) times from 2.5 m/s to 0.31 mm/s for a target with a longitudinal velocity v(z) - 4 cm/s, a transverse velocity v(t) - 5 m/s, and at a detection range of 108 m.
    Relation Link: http://www.osa.org/
    URI: http://nthur.lib.nthu.edu.tw/dspace/handle/987654321/83617
    Appears in Collections:[電機工程學系] 期刊論文
    [光電工程研究所] 期刊論文

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