High-sensitivity displacement measurement using a novel fiber optic electronically scanned white light interferometer

High sensitivity displacement measurement using a novel fibre-optic electronically-scanned white light interferometerR. H. Marshall, Y. N. Ning, A.W. Palmer and K. T. V. GrattanDepartment of Electrical, Electronic and Information Engineering,City University, London, ECIV OHB, UK.ABSTRACTIn recent years, white-light interferometry (WLI) has been used extensively for the measurement of displacement. Inthis work, a novel bulk-optical Mach-Zehnder interferometer (MZI) is employed as a processing interferometer in an extrinsicfibre-optic electronically scanned white light interferometer. A Fabry-Perot interferometer (FPI) was used as the sensinginterferometer, whereby one of its mirrors was translated using a linear PZT stage in order to provide the displacementmeasurand. An electronically-scanned system was employed, which has the advantages of not requiring any moving parts,which in turn increases the mechanical stability of the system. In addition, this bulk-optical MZI configuration has theadvantages of being relatively small and compact, and does not require the use of polarizers, unlike some electronically-scanned interferometers -