| WU Shi-song,Lü Tao,LI Yuan-yang,WANG Ting-feng,GUO Jin.Multi-beam interference competition in heterodyne detection[J].Optoelectronics Letters,2019,15(3):213-216 |
| Multi-beam interference competition in heterodyne detection |
| Author Name | Affiliation | | WU Shi-song | Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033,
University of Chinese Academy of Sciences, Beijing 100049, China | | Lü Tao | Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033,
University of Chinese Academy of Sciences, Beijing 100049, China | | LI Yuan-yang | Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, | | WANG Ting-feng | Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033,
University of Chinese Academy of Sciences, Beijing 100049, China | | GUO Jin | Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033,
University of Chinese Academy of Sciences, Beijing 100049, China |
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| Abstract: |
| In a typical infrared optical system, the “Narcissus” effect exists extensively. This concept can be extended into a heterodyne detection. In a heterodyne detection, besides the probe and local oscillator beams, a third coherent beam or even more beams caused by spurious reflection might interfere with each other on the surface of the photodetector. Generation of heterodyne signal is dependent on the interference effects between regular and unexpected waves. Based on the theory of PM demodulation, we analyze the effect of multi-beam interference competition in a laser Doppler vibrometer (LDV). A mathematical analysis demonstrates that the signal competition depends on the modulation index, the amplitude ratio of competing signals and their relative phases. The distortion of demodulated signal due to the appearance of ripples or spikes is also predicted in this study. These effects are verified by setting up an all-fiber LDV system for measuring vibration. |
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