High Resolution Dispersed Reference Interferometry

Dispersed reference interferometry (DRI) is a single point measurement technique with potential for use in applications such as absolute displacement, surface topography and film thickness measurement. A dispersed reference interferometer using a short coherence near infrared light source is described with chromatic
dispersion in the reference arm introduced by a pair of matched transmission gratings. By tracking the point of symmetry of the produced interferogram, absolute position measurement may be performed. A previously demonstrated method (Martin 2013) to provide single point measurements is described and further simulated
and experimental evidence is provided to demonstrate the potential capability of DRI to provide higher vertical resolution relative measurement while maintaining range.