Novel Interferometer Enables Challenging Measurements

Dynamic interferometry is a standard technique for measuring optics, meter-class optics and optical systems in challenging environments. The method provides high out-of-plane resolution and repeatability even in the pres¬ence of significant vibration and air turbulence. A new dynamic interferometer utilizing a proprietary laser source and patented optical configuration has enabled wavefront measurements which until now have been difficult or impossible to complete with standard temporal phase-shifting systems. This article describes a short coherence Fizeau interferometer and its applications for measuring large telescope optics, general purpose optics, disk drive substrates and media, flat panel display components and lithography optics.

In an interferometer, light reflecting from a test and reference surface combine to produce patterns of light and dark fringes called "interferograms." By acquiring a series of interferograms and applying algorithms, the system extracts the shape of the test surface with sub-nanometer vertical resolution.