Calibration of digital speckle pattern interferometry based on three-axis angle motions measurement theory

Digital speckle pattern interferometry (DSPI) is a full-field optical testing technique that can be used to measure tiny displacements and strains. However, the lack of effective calibration method has prevented the wider adoption of this technique. In this paper, a comprehensive calibration method based on the theory of three-axis angle motions measurement using DSPI has been proposed. The tiny three-axis angle motions are loaded by Piezoelectric actuators and measured using a DSPI device based on the DSPI three-axis angle motions measurement theory. A multi-axis interferometry is used to measure the three-axis angle motions simultaneously and its output is used as the measurement reference. Because the angle motions of a rigid body instead of the displacements of an elastic body are measured, the measurement reference is readily available, yielding the successful precision calibration of the DSPI.