Real Time Measurement of Meniscuses on the Water Surface Caused by a Pond Skater Using a Holographic Shearing Interferometer

Abstract

A holographic shearing interferometer is applied to the real time measurement of meniscuses on the water surfaces, caused by a pond skater. A holographic shearing interferometer has advantages as follows; 1) it is a simple interferometer with a common path and is stable for the external vibration; 2) it gives interferograms of better contrast and of larger area than a Ronchi type interferometer; and 3) the shearing of the two orthogonal directions can be produced at the same time.
However, there are problems to be solved as follows; 1) adjustability of the number of interference fringes observed; and 2) the problems on the overlap of zero order undiffracted light and 1st order diffracted light, and 3) on the effect of lens aberration. The problems 2) and 3) become serious when theF number of optical system is small.