Color-Camera-Based Dual-Wavelength Shearography for Simultaneously Measuring in-Plane and out-of-Plane Displacement Derivatives

A color-camera-based shearography system using dual-wavelength lasers was developed for simultaneously measuring the in-plane and out-of-plane displacement derivatives of a deformed object. Lasers of dual wavelengths arc arranged to symmetrically and simultaneously illuminate on the object with identical angles of incidence. A set of phase-shifter and a modified Michelson interferometer arc used to build a temporal-phase-shift dual-wavelength shearography. The interferograms formed by the two wavelength arc recorded by one 3-chip color camera with green and blue channels. The phases related to the in-plane and out-of-plane components arc extracted from the shcarograms by using Carra algorithm. Experiment on a cantilevered aluminum beam deformation was performed to verify the feasibility and the capability of the testing system.