Dispersion effect analysis with multiwavelength combination sources in optical sensor applications

Abstract

Using a multiwavelength combination source, the central fringe in the interference fringe pattern in a white light interferometric sensor system can often be more easily identified, which is important for high precision and absolute measurement. However, owing to the possible optical path imbalance inside the optical dispersive elements which are usually involved in such systems, the zero optical path difference (OPD) position corresponding to one of the individual sources may not coincide with that of the others and consequently the central fringe intensity may decrease. This may be associated with a substantial degree of fringe pattern asymmetry, which causes a significant problem with central fringe identification. In this work, the effect of zero OPD position variation with the wavelength on fringe patterns of multiwavelength combination sources are analyzed and a method to alleviate such an effect is proposed, supported by a simple theoretical analysis and experimental results.