Fig. 1. Geometry of DSPI system for deformation measurement.

Fig. 2. Illustration of the phase evaluation process. (a) DSPI interferogram. (b) Spectrum of an interferogram in the Fourier domain. (c) The wrapped phase difference ΔØ. (d) The unwrapped continuous phase difference ΔØ.

Fig. 3. Geometry of DSPI system for shape measurement.

Fig. 4. Experimental DSPI setup.

Fig. 5. Experiment result of out-of-plane deformation measurement for curved objects. (a) The wrapped phase difference ΔØ. (b) The unwrapped continuous phase difference ΔØ. (c) Shape measurement result. (d) A section through the center of the surface.

Fig. 6. Experiment result of deformation measurement for a cylinder surface. (a) The wrapped phase difference ΔØ. (b) The unwrapped continuous phase difference ΔØ. (c) The measured deformation in the direction of optical axis. (d) An example of out-of-plane deformation of cylinder surface. (e) The measured and applied rotation angles in the optical axis direction. (f) Comparison between the measured and theoretical applied out-of-plane deformation in the x axis. (g) Comparison between the measured and theoretical applied out-of-plane deformation in the y axis. (h) The MSEs of the measured out-of-plane deformations in the whole field of view for the 10 different loads (indexed by case number).

Fig. 7. Experiment result of 3D shape measurement with spherical wave illumination. (a) 3D shape measurement with spherical wave illumination after compensation. (b) Comparison between the results with and without compensation in the x axis. (c) The MSE with and without compensation.