A Real-time Heterodyne Shearography Interferometry Measurement Technology

Interferometry with the characters of non-contact, whole-field and high sensitivity is widely used for the measurement of shape profile, tiny displacement and deformation. Speckle interferometry can be used for the measurement of stress, defects. But when it turns to measure the strain or displacement gradient, shearography would be more precise without one more calculation. Meanwhile, the heterodyne interferometry with the merits of anti-interference, easy to extract the information; we introduce the heterodyne interferometry to the real-time digital shearography measurement, and develop a new measurement system of real-time heterodyne shearography interferometry. This system combined with heterodyne measurement, shearography interferometry as well as time domain signal processing technology, and it can detect the out-of-plane displacement gradient synchronous. The system has been build up and the experiment of the measurement of the displacement-derivative is conducted. Preliminary results are obtained.The main work of this paper includes:1. The heterodyne measurement has been introduced to the real-time digital shearography interferometry, and calculated the system in theory, and the system proved to be true theoretically.2. The finite element analysis software-ANSYS has been used to do the simulation of the object to get the ideal out-of-plane displacement gradient.3. A real-time heterodyne shearography interferometry measurement setup has been developed, and the experiment has been done to measure the out-of-plane displacement gradient. The experiment result has been compared with the simulation result, and the relative error is 2.24%.