Polarization-sensitive laser feedback interferometry for specular reflection removal

Specular reflection from the surface of targets or prepared specimens represents a significant problem in optical microscopy and related optical imaging techniques as usually the surface reflection does not contribute to the desired signal. Solutions exist for many of these imaging techniques; however, remedial techniques for imaging based on laser feedback interferometry (LFI) are absent. We propose a reflection cancellation technique based on crossed-polarization filtering that is tailored for a typical LFI configuration. The technique is validated with three experimental designs, and a significant improvement of about 40 dB in the ratio of the diffuse and specular LFI signal is observed. Applications of this principle extend from specular reflection removal to characterization of target materials in industrial to biomedical domains.