A Circumferential Closed Single Displacement Measurement Method Based on the Light Intensity Orthogonal Modulation 2019-01-1267
In order to achieve high precision measurement with low manufacturing process, we propose a new angular displacement measurement method, which can realise simultaneous measurement of whole circumference. Firstly, through the orthogonal modulation of time and space for the ring light field, four channels of standing wave light field uniformly distributed along the circumference is obtained. Then, a electric traveling wave signal is synthesized by photoelectric conversion and phase-shifting processing. Finally, the angle displacement is measured by using the method of phase discrimination through calculating the phase difference between electric traveling wave signal and reference signal. By deducating the measuring mechanism of the sensor, the measuring error characteristics caused by the non-uniform distribution of light field is analyzed. Based on above, lots of confirmatory experiments were carried out, and the results prove the correctness of the theoretical analysis. According to the theoretical analysis and experimental results, the errors caused by the light field distribution is clarified, and the sensing structure and parameters are optimized. Finally, the measuring accuracy of the sensor reaches ±1.5″by using an equi-transmissive surface with a central angle of 12°.