Design of Phase-shifting ESPI System for 3D Deformation Measurement

It designs the phase-shifting ESPI(electronic speckle pattern interferometry) systems for 3D deformation measurement. The first design applies common optics, single laser source and two PZTs to introduce five testing beams, in which two beams are phase-shifted. By this system, in-plane and out-plane deformation can be tested by switching the projecting beams and 3D deformation of the object can be calculated. The testing is closely dynamic. The second design applies a one to five beam-splitting fiber to simply and compact the system. In this system, the laser beam is divided into five sub-beams as the testing rays. On the heads of two sub-fibers, PZTs are attached to introduce phase-shifting. By analysis, the system error by this phase-shifting mode can be omitted. In this system, the in-plane and out-plane deformation are tested by the same switching mode as the first design, which means that the dynamic characteristic is determined by the switching speed. It describes the two designs and analyzes briefly