Fiber-Coupled Common-Path Shearography for Simultaneous Measurement of Surface Deformation and Slope

A mechanical quantity sensing framework is proposed, which is based on fiber-coupled common-path shearography, for the simultaneous measurement of deformation and slope. An optical fiber directs the reference wave into the system for the generation of holograms without breaking the common-path structure. The present shearography possesses three features for mechanical quantity sensing, namely, the zero-approaching shear amount, the separate control of spatial carriers, and the scrambled reference wave. Single-shot phase measurement scheme is implemented by the spatial carrier method, in which the deformation and slope are retrieved from a single frame of interference pattern. Fiber scrambling is brought into the system to flatten the intensity distribution of the fiber-directed reference field and deliver a quality-enhanced phase map. Physical principle is demonstrated. Preliminary experiments are carried out to verify the feasibility and functionality of the proposed framework.