ENHANCING CENTRAL FRINGE IDENTIFICATION USING 2 OPTICAL BEAMS WITH DIFFERENT POWER AND WAVELENGTHS IN WHITE-LIGHT INTERFEROMETRIC SENSING

Results of a study to enhance the relative amplitude of the central fr inge in the output of a white light interferometric system with two op tical beams has been described, where the approach is based on the ele ctronic multiplication of the output signals corresponding to the two optical beams. The outputs were generated by separating the sensing be am with a wavelength selective filter and detected using two separate photodetectors. The results obtained show that the relative amplitude of the central fringe of the multiplied output is independent of the p ower ratio of the two beams. Comparisons between this approach and the more conventional use of the dual wavelength technique are also inclu ded. (C) 1998 Elsevier Science S.A. All rights reserved.