Triggering digitisation of interferograms for Michelson interferometers - involves triggering digitiser with pulses satisfying sampling theorem, seeking spectral lines of known wave number for wave number calibration

摘要

The method is used for triggering the digitisation of interferograms. It involves triggering an analogue-to-digital converter (2) connected after the interferometer detector (10) with pulses of frequency selected to satisfy the sampling theorem. The start of movement of a mirror (16) and hence of the measurement process is detected whereby equidistant signal scanning is ensured by a constant mirror motion and trigger frequency. The step width for a Fourier transformation is set to one and spectral lines or bands of accurately known wave number sought in the spectrum. A stretching factor is determined from the wave numbers for wave number calibration and used to multiply computed abscissa values. USE/ADVANTAGE - For use with Michelson interferometers. The triggering is achieved very reliably and at low cost without direct distance measurement.