Online measuring instrument for mirror pendulum pose based on correlation measurement

This paper introduces an online measuring instrument for mirror pendulum pose, which uses quadrant Si-photoelectric cell as the detector. The semiconductor laser is driven by AC modulate circuit and the polarization splitting optical system and the correlation signal process is adopted, so the DC drift effects can be removed and the instrument's reliability and precision are improved. The result being effected by beam spot size is analyzed in this paper, and a special demarcate equipment is designed. The measurement range is about ±30′, the precision is better than 0.5″. The instrument can measure the mirror pendulum pose online easily in science study and industrial measurement.