Sub-nanometer metrology of optical wafers using an angle-scanned Fabry-Perot interferometer

An rms measurement repeatability of <= 0.07 nm and a reproducibility of <= 0.16 are reported from a series of thickness measurements made on a 280 mu m thick, 37.5 mm diameter lithium niobate wafer. The measurements were taken on a custom made metrology rig based on accurate rotation of a Fabry-Perot etalon structure in a collimated beam from a wavelength stabilized Helium Neon laser. The measurements were made on different days with the wafer in three different orientations. (c) 2006 Optical Society of America.