Central fringe identification in a white light interferometer using a multi-stage-squaring signal processing scheme

Abstract A new signal processing scheme for central fringe identification in a white light interferometer is described. With the use of a simple, fast and low-cost multi-stage-squaring processing unit, the central fringe in the output fringe pattern can be considerably enhanced and the SNR min required to identify the central fringe can be reduced from about 30 dB to 17 dB in a practical application.