Precision measurement of angle using digital speckle pattern interferometry

A non-contact and non-cooperative method of angle measurement based on digital speckle pattern interferometry (DSPI) was introduced in this paper. Studies have shown that when the illumination angle of the DSPI system was every small, the angle can be determined according to the interferometric phase distribution and the length of the measured object. Thereby a direct relationship between the angle and the phase distribution was established. In our experiments, the resolution of measurement system was 0.00025 degrees(0.9"), proving that the proposed method is effective for measuring small angles. Theoretically, this method can achieve higher resolution if the measurement noise can be minimized.