Study on a small modulation and high precision laser range finder using the self-mixing effect in a single-mode VCSEL

Abstract

The paper proposes a small modulation and high precision laser range finder using the self-mixing effect in a single-mode vertical-cavity surface-emitting laser (VCSEL). According to the characteristic curve of single-mode VCSEL, the nonlinear distortion of ∆λ/∆I is severe and related with the modulation current ∆I, which worsens the system ranging accuracy obviously. In this paper, by applying small current to modulate single-mode VCSEL and specific circuits to process photoelectric signal, the system ranging accuracy is improved obviously. The experiment results show that, using small modulation current ∆I = 0.28 mA p-p, modulation frequency f m = 500 Hz to modulate single-mode VCSEL, and applying difference frequency analog phase-locked loop (APLL) to process the self-mixing beat frequency signals that exist phase abrupt changes, when the sampling time is 0.1 s, the measurement dynamic range is as large as 50 ~ 500 mm, and the ranging accuracy is better than 2 mm.

Blind identification of occurrence of multi-modality in laser-feedback-based self-mixing sensor

“…doi: 10.3788/COL202018.011201 SELF-MIXING (SM) or optical feedback (OF) interferometry [1,2] is actively researched for vibration, angle [3] , frequency [4] , size [5] , range-finding [6] , topographical [7] , and seismic applications [8] due to the simple, low-cost, and miniaturized nature of SM sensors. In order to design low-cost SM sensors, usually commercial off the shelf (COTS) laser diodes (LD) are preferred.…”