Development of in-plane and out-of-plane deformation simultaneous measurement method by using only two speckle patterns

The deformation measurement method by using only two speckle patterns has been proposed in ESPI by using Fourier transform. In this paper, a new optical system which can measure precisely an in-plane and out-of-plane deformation of the object with rough surfaces is developed by using the proposed deformation measurement method. The in-plane deformation can be generally detected by using the two-beam speckle interferometer. Then, the measurement method for improving measuring accuracy using the new optical system has been discussed. The proposed optical system can also measure simultaneously the in-plane and out-of-plane deformations using two cameras and one beam. The analyzing algorithm, which can separate each component of the in-plane and out-of-plane deformations, is also proposed. Speckle patterns from each camera before and after the deformation are analyzed in order to detect the phase maps as the deformation information. Then, the optical path distance distribution before and after deformation in each camera is detected. Finally, the in-plane and out-of-plane deformations can be measured independently by using a pair of the optical path distance results based on the geometry of two cameras. From experimental results, it is confirmed that the new method can analyze a pair of in-plane and out-of-plane deformation simultaneously and independently in a high resolution power.