Research On Sensing Technology Utilizing Self-mixing Effect Of VCSEL And Optical Tracking System

The work in this dissertation is motivated by three main projects: "Laser Doppler tracking", "Fiber-optic self-mixing laser Doppler tracking" and "Optical tracking", which were undertaken by University of Science & Technology of China in collaboration with Microsoft's Hardware Division.The sensing technology based on self-mixing effect of semiconductor laser diode has stimulated great interest in optical sensing field to measure the velocity, distance and vibration, owing to its significant advantages in simplicity, compactness, robustness and high precision. We have studied the characteristics of the self-mixing interferometry using single longitudinal-mode vertical-cavity surface-emitting Lasers (VCSELs), and constructed high precision self-mixing laser Doppler velocimetry, laser range finder, laser Doppler vibrometry and real-time two-dimensional (2D) triangulation-based optical tracking system. Lots of exciting results have been obtained.The main conclusions are as follows:1. We have described the fundamental principle of sensing technology based on the self-mixing effect of laser diode using three-mirror model and rate equation. The self-mixing signals of VCSEL modulated by triangular current under different feedback strength have been obtained by numerical simulation. And we have reconstructed vibration signal from self-mixing waveform. The theoretical results are in good agreement well with experiments.2. The self-mixing laser Doppler velocimetry using VCSEL is fabricated. It can discriminate the direction of velocity without ambiguity in a wide range from 5.2mm/s to 479mm/s using a dynamic triangular modulation current. This velocimetry is also a realized measurement of fluid flow.3. We have studied the influences of polymer optical fiber (POF) on self-mixing signals in laser Doppler velocimetry. The waveform distortion and Doppler...