Surface topography by wavelength scanning interferometry

Parallel and absolute measurement of surface shape using wavelength scanning interferometry has been applied to various objects including diffuse surfaces and milled ones having discontinuities such s steps, dips, and protrusions. We have employed not only the Michelson setup but also the Fizeau one newly introduced. The behaviors of interference signals arising from these objects are experimentally compared. Spiky noises have been observed from the milled surfaces and the defocused diffuse surface. In spite of the noise we succeeded in measuring steps and narrow dips on a mirror and a milled surface, as well as a cylindrical protrusion on a diffuse surface. With a dye laser of tuning range of 4.2 nm we attained the resolution of 39 micrometer within the depth of 3 mm.