SIGNAL-PROCESSING SCHEME FOR CENTRAL POSITION IDENTIFICATION IN A WHITE-LIGHT INTERFEROMETRIC SYSTEM WITH A DUAL-WAVELENGTH SOURCE

A signal processing scheme using a curve fitting algorithm to determin e the central position of the digitized fringe pattern output of a whi te light interferometric (WLI) system is discussed. An analytic result for the resolution obtained in the central fringe position measuremen t using a specific curve fitting scheme has been given and a simulatio n of the measurement of the central position of a computer generated f ringe pattern has been carried out. The results from the simulation sh ow good agreement with those from the theoretical analysis. A supporti ng experiment to investigate this effect has also been carried out and the short term repeatability of the central position measurement usin g the curve fitting scheme gives close agreement with the theoretical results. (C) 1998 Elsevier Science Ltd. All rights reserved.