Design and application research of the multi-longitudinal mode laser self-mixing vibration measurement system

摘要

The free spectral range of the resonant cavity is calculated to be 78.95 GHz based on 1.90 mm of the waveform separation period as a multi-longitudinal mode laser diode is employed as the light source of the self-mixing vibration measurement system. As such, the influence of the vibration amplitude of the loudspeaker to the self-mixing vibration signal waveform is further researched by means of the feasible theoretical analysis and experimental characterization. The primary experimental results demonstrate that the amplitude limitation ratio coefficient A(l) of this sensing system is required to design below 2.053 x 10(-3) corresponding to an entire waveform separation period, of which is to prevent the self-mixing signal waveform from distorting effectively in the context of the integral order of the external cavity mode. Furthermore, the feedback levels of the multi-longitudinal mode laser self-mixing vibration system are studied in detail. It has been shown that the experimental result of the free spectral range fits well with theoretical value when this system is matched to the applicable amplitude limitation range 0 < A(l) <= 2.053 x 10(-3) and the optimum optical feedback regime 0 < C < 4.6. (C) 2019 Elsevier Ltd. All rights reserved.