Reference fringe counting in Fourier transform spectroscopy

摘要

Fringe counting in a Michelson type interferometer is carried out by detecting when the amplitude of the reference fringe attains a given value eg a zero crossing. Reversals in scan direction are recognised by monitoring parameters of the waveform such as amplitude and time occurence of successive half fringes and identifying a reversal by the occurrence of a particular sequence or state of the monitored parameters.