All-fiber monostatic pulsed laser Doppler vibrometer: A digital signal processing method to eliminate cochannel interference. (April 2020)

• Record Type: Journal Article
• Authors: Peng, Shuping; Wu, Shisong; Li, Yuanyang; Chen, Hongkai
• Is Part Of: Optics & laser technology. Volume 124(2020)
• Publication Date: 2020-04
• Subjects: Laser Doppler vibrometer -- Acoustic monitoring -- Cochannel interference -- Digital range gated signal processing; Optics -- Periodicals; Lasers -- Periodicals; Electronic journals; 621.366
• DOI: 10.1016/j.optlastec.2019.105952
• Languages: English
• ISSNs: 0030-3992

Abstract

Highlights: An all-fiber monostatic pulsed LDV is developed. Cochannel interference is eliminated by the proposed range gated signal processing. The functions of range finding and vibrometry are realized at untra-low laser power output. Abstract: A 1.55 μ m all-fiber monostatic pulsed laser Doppler vibrometer is developed to overcome demodulation failures caused by cochannel interference. We discussed the waveform design guidelines and proposed a digital range gated signal processing method to avoid the "Narcissus" effects. The resulting phase-modulated intermediate frequency (IF) of 40 MHz, which carries the information of target vibration, is demodulated down to the baseband using a specific in-phase and quadrature (I&Q) demodulator. An experiment is carried out at a 23 m standoff with pulse repetition interval of 50 ns, single pulse energy of 0.25 nJ, and pulse repetition frequency of 1 MHz to verify the performance of the prototype. The experimental results show that the pulsed LDV system has the ability to demodulate the acoustic vibration at a stand-off about several dozens of meters using an ultra-low output laser power.