Based on the 1 550 nm all-fiber pulsed laser Doppler vibrometer(LDV) system independently developed by our laboratory, empirical mode decomposition(EMD) and optimally modified Log-spectral amplitude estimator(OM-LSA) ...Based on the 1 550 nm all-fiber pulsed laser Doppler vibrometer(LDV) system independently developed by our laboratory, empirical mode decomposition(EMD) and optimally modified Log-spectral amplitude estimator(OM-LSA) algorithms are associated to separate the speech micro-vibration from the target macro motion. This combined algorithm compensates for the weakness of the EMD algorithm in denoising and the inability of the OM-LSA algorithm on signal separation, achieving separation and simultaneous acquisition of the macro motion and speech micro-vibration of a target. The experimental results indicate that using this combined algorithm, the LDV system can functionally operate within 30 m and gain a 4.21 d B promotion in the signal-to-noise ratio(SNR) relative to a traditional OM-LSA algorithm.展开更多
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 beam...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.展开更多
基金supported by the National Natural Science Foundation of China (No.61805234)the Key Research Program of Frontier Science,CAS (No.QYZDB-SSWSLH014)the Foundation of State Key Laboratory of Laser Interaction with Matter (No.SKLLIM1704)。
文摘Based on the 1 550 nm all-fiber pulsed laser Doppler vibrometer(LDV) system independently developed by our laboratory, empirical mode decomposition(EMD) and optimally modified Log-spectral amplitude estimator(OM-LSA) algorithms are associated to separate the speech micro-vibration from the target macro motion. This combined algorithm compensates for the weakness of the EMD algorithm in denoising and the inability of the OM-LSA algorithm on signal separation, achieving separation and simultaneous acquisition of the macro motion and speech micro-vibration of a target. The experimental results indicate that using this combined algorithm, the LDV system can functionally operate within 30 m and gain a 4.21 d B promotion in the signal-to-noise ratio(SNR) relative to a traditional OM-LSA algorithm.
基金supported by the National Natural Science Foundation of China(No.61805234)the Foundation of State Key Laboratory of Laser Interaction with Mater(No.SKLLIM1704)
文摘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.
