Three-dimensional Deformation Measurement With The Combination Of DSCM And ESPI

The Digital Speckle Correlation Method (DSCM) and Electronic Speckle PatternInterferometry (ESPI) has developed into whole field, non-contact, high-precision, highsensitivity and real-time measurement techniques. The DSCM obtains the deformation bycomparing the gray intensity changes of the object surface before and after deformation. TheESPI makes use of laser speckles in space or artificial speckles sprayed on the specimen surfaceto implement the displacement and deformation measurement. To perform3D evaluations ofdisplacements, ESPI systems always use three illumination beams. Accordingly the optical setupwould be complicated and the implementation procedure would not be easy. By using thecombination of DSCM and ESPI can solve the problem. In this paper, a typical optical setupwith one illuminating light sensitive to out-of-plane displacement is used in the measurement of3D displacements. The in-plane displacements and out-of-plane displacement can be obtained byusing DSCM and ESPI respectively by controlling the reference light.In this dissertation, three-dimensional deformation measurement with the combination ofDSCM and ESPI is discussed in detail. The main contents are described as the following:1. A review of the development of DSCM and ESPI, and discuss the significance of using thecombination of DSCM and ESPI in measurement.2. The theory and the select of correlation coefficient are introduced. Several sub-pixelalgorithms are introduced in detail and Simulation experiments are given.3. The form of speckle, in-plane and out-plane displacements measurement theory of ESPI andseveral methods of extracting phase (including Fourier transform method, phase shift methodand Hilbert transform method) are introduced.4. The theory of three-dimensional deformation measurement by using the combination ofDSCM and ESPI is presented. A typical three-point-bending beam experiment is completed bythe method proposed. Experiment results show that the three displacement components can be obtained effectively. The deformation measurement system is simple and useful for it has asimple setup and operation.