Adjustable dispersion reduction in low-coherent techniques by a system of tilted metallic mirrors with dielectric coating

• Adjustable dispersion reduction through a reflection from dielectric coated metallic mirrors is presented.
• Adjustability is based on polarization dependent phase shift upon reflection from a metallic surface of tilted mirror.
• The influence of dielectric layer thickness was analysed numerically for the silver mirrors based compensator.
• The experimental works has shown over 40% increase in axial resolution.
• The changes in a polarization azimuth had high influence on axial resolution.

In this paper a new method for adjustable reduction of a dispersive drop in axial resolution during low-coherent measurements is presented. This method is based on multiple reflections of a light beam from dielectric coated metallic mirrors and is intended for reducing dispersion in full-field systems. The tilted metallic mirror with a dielectric coating works like an adjustable Gires–Tournois interferometer. The concept of adjustability is based on a polarization dependent phase shift upon reflection from metallic surfaces at incidence angles different from θi=0°θi=0°. The dispersion compensation was simulated numerically with the use of Fresnel equations for a silver mirror based compensator. The possibility of dispersion reduction was then verified experimentally in a Twyman–Green interferometer showing over 40% improvement in the axial resolution.