Abstract

Shearing interferometers have a growing range of applications especially in the field of optical testing /1/ We propose a new type of lateral shearing interferometer /2/ based on two Ronchi gratings in series. We use this set-up because it has several advantages which make it very suitable for measurements e.g. of silicon lenses in the near IR region. The set-up /3/ consists of two Ronchi gratings in series with suppressed zero orders. The main advantage of this set-up is that the interferometer is very easy to adjust. The important parameters like amount of phase shift of shear can easily be controlled. The phase shift can be adjusted by moving the second grating laterally with respect to the other and the amount of shear can be adjusted by changing the longitudinal distance of the gratings. For the whole measurement of a wavefront two orthogonal partial derivatives can easily be obtained by rotating the two gratings together through 90 degrees.

© 1996 IEEE