Fabrication of a simple and easy-to-make piezoelectric actuator and its use as phase shifter in digital speckle pattern interferometry

Abstract

In this report, design and assembly of a simple, easy-to-make and low-cost piezoelectric actuator (PZA) with one degree of freedom for application in phase-shifting interferometry is described. The PZA is designed in a way that its components can easily be manufactured and assembled. In the developed PZA, a series of ring-shaped piezo-ceramics are assembled inside a stainless steel case and through a couple of plate springs are preloaded. Planar electrodes are cut from a thin beryllium copper plate using wire-cut EDM and used on top and bottom sides of each ceramic plate. The supply voltage is applied to the electrodes by a designed control electronic circuit connected directly to a computer through a standard parallel port. A graphical user interface is developed in the MATLAB environment for controlling the converter. The electromechanical response of the PZA is studied by applying a calibration procedure based on using a Michelson interferometer. It is shown that by increasing the DC voltage from 0 to 200 V, the PZA has a good linear response. By using the PZA for strain field measurement in a rectangular steel plate, it is shown that the linear response of the designed PZA makes it a suitable candidate for use in Carre phase-shifting interferometry.