Spectral effects of dual wavelength low coherence light source in white light interferometry

The spectral property of some modern (or hybrid) low coherent light source introduces distinctive feature to the interference signal of white light interferometry. The distinctive feature is defined as discontinuities which make the fringe contrast function (which is the envelope of the interference signal) unable to be modeled as a single Gaussian function. In this paper, we investigate the spectral effect of dual wavelength low coherence light source in white light interferometry and identify the distinctive feature as the result of destructive interference within the localized window where the optical path difference (OPD) is small. By doing so, we give a theoretical explanation of the distinctive feature and demonstrate that the fringe contrast function (and the location of the distinctive feature) can be manipulated by spectrum shaping.

► Dual wavelength low coherence light introduces a distinctive feature.
► Distinctive feature is the result of interference and is similar to a beat.
► With our work, interference signal can be manipulated by spectrum shaping.