Abstract

The aim of the project is to investigate the potential of expanding the instrument measurement bandwidth of a traditional phase measuring interferometer (PMI) using a comparatively simple optical/software modification. This would offer the benefit to users of gaining increased measurement bandwidth within a single measurement set-up.

Specifically the design is aimed at detecting (and measuring the locations of) higher frequency components than are traditionally measured. These components are those that arise from the general roughness and pits and scratches within the figure of the surface geometry. The principle of the technique is to make a two part measurement and then to examine the two measurements either individually or in combination. The first measurement is simply the conventional interferogram analysis. The second measurement involves introducing additional optical components (lenses and a spot mask) into the optical path and then re-measuring the phase map. Software is then used to analyze the resultant images.

This paper describes the design and construction of a “bread boarded” set-up of the test instrument. It includes some preliminary test measurements demonstrating the functionality of the system.

© 1994 Optical Society of America