Non-contact and fast measurement of small roll angle using digital shearography

Abstract

An approach to non-contact, fast, and precision measurement of small roll angle using digital shearography is introduced. The roll angles are determined directly by recording the interferometric phase changes when using a dual-beam digital shearography to measure tested surfaces. Phase at a point rather than full-field phase distribution is used to calculate the roll angle, so global image processing is no longer needed and the measurement speed becomes much faster. The proposed approach is robust due to the nature of digital shearography, making it a promising method in field applications. The theoretical measurement resolution of the method is from 1.5 µrad to deep sub-microradian, which can compete with the best resolution of the existing methods.