Phase-Shifting Interferometry

Abstract

Interierometric methods permit us to measure the shape oi an optical suriace with high accuracy, using the wavelength as a unit oi length. On the other hand, spherical suriaces are the most common, but aspherical surfaces i.e., not spherical, are more and more popular due to their great design advantages. Aspherical surfaces generally have the shape of a conic of revolution. The prozedure to determine the quality of an aspherical surface is not an easy one. However, these methods are absolutely necessary in order to manufacture the very precise modern optica! surfaces. Phase shifting interferometry started about ten years ago. It has many great advantages with respect to the traditiona! methods, mainly when it's applied to the testing of optical surfaces. Here, we present a review of these advances.