Surface roughness detection by spin Hall effect of light with sub-nanometer resolution

Abstract

We report here a novel measurement method for detecting a rough surface with sub-nanometer accuracy by using the spin Hall effect of light (SHEL). Reflecting an inspection light at a sample surface, a slightly position shift, which is called “the SHEL,” occurs at the reflection surface. The shift corresponds to polarization difference between an incident and a reflected lights. The difference depends on a conditions of a surface roughness of a sample surface or a thickness of a thin film. Because a rough surface within λ/10 can be approximated to thin film by the theory of the effective medium theory. We measured the SHEL of some Au thin films and surface roughness of a optical flat sample via the weak value amplification technique. Sub-nanometer resolution for the measurement of the film thickness is obtained and some experimental results are shown in this paper.