title: Note: Laser Doppler velocimeter using a dual-longitudinal-mode laser source.
abstract: This paper presents a new laser Doppler technique using a dual-longitudinal-mode He-Ne laser as the laser source. Theoretical analysis shows that the Doppler frequency is proportional with the frequency difference of the two modes. The Doppler frequency in this technique is very low compared with the one in the single-mode laser Doppler technique. The new laser Doppler technique can be used to measure high speed. Experiment results show that the Doppler frequency is only about 82 Hz while the measurement speed reaches 31.4 m∕s. The signal-to-noise ratio of the Doppler signal is improved by the technique of digital filter and digital autocorrelation.
authors.affiliation: Department of Optoelectronic Engineering, College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha 410073, China.
authors.forename: Nie
authors.initials: N
authors.lastname: Xiaoming
authors.forename: Zhou
authors.initials: Z
authors.lastname: Jian
authors.forename: Long
authors.initials: L
authors.lastname: Xingwu