New design for laser image—speckle interferometer

Abstract

A new laser image—speckle interferometer, a device used for looking at vibrational modes on defusely reflecting surfaces, has been designed. The design makes it possible to provide a reference field in the instrument that is substantially free from spurious pattern. This field interferes with a speckled image so giving a more intense image field. As larger surfaces may be viewed with lower power lasers, the method offers an attractive alternative to strictly holographic methods.