Rayleigh Wave Amplitude Field Determination by a Simple Speckle Point Interferometer

Abstract

A very simple speckle point interferometer of the Michelson type and the method employed to achieve nanometric resolution and repeatability are described. Among the subjects of interest, the selection of the dimensions of the detector compared to the speckle size and fringe separation, the effects of temporal bandwidth of the detection system and of averaging the signal obtained from successive acquisitions under identical conditions are evaluated. An application of the interferometer to the measurement of the amplitude field of a Rayleigh wave train, propagating on the surface of an aluminium slab, with nanometric resolution is presented. The average repeatability obtained is of the order of 2 nm.