A Device for Calibration of Electronic Speckle Pattern Interferometers

Abstract

A calibration device intended for metrological assurance of instruments used to measure deformations and displacements by methods of electronic speckle interferometry and shearography is developed. The optical methods presented here may be applied to different types of materials possessing rough surfaces. The proposed device reproduces stress-strain states by means of elastic deformation of the surface of a membrane through the use of a rod and leverage. Calibration of the device is performed, its transfer characteristics are investigated, and the nonlinearity of the displacement of the surface of the membrane is estimated. Results of experiments designed to measure the stress-strain state with the use of the noncontact method of shearography are presented. The phase image produced by deformation of the membrane is described and the metrological characteristics of the calibrated device are estimated. It is shown that through the use of the present calibration device it is possible to use optical methods not only for qualitative assessment of the deformation of objects of complex shape, but also for quantitative estimation of the geometric characteristics of these objects.