Detection of refractive index and imperfection in thin film transparent polymer by back focal plane imaging

Emission patterns from molecules at interfaces encode many details about their local environment and their axial position, along the microscope's optical axis. We introduce an advanced approach that synergizes back focal plane (BFP) imaging with innovative 'smart' surfaces make surface imaging more qualitative, more reliable, and more robust. Our method is particularly focused on accurately measuring the refractive index (Rl) of transparent thin films and their imperfections close to the interfaces. Our technique utilizes a 'smart' surface, which features a uniform fluorescent thin film of about 4 nm thickness together with back-focal plane (BFP) imaging. We manage to detect bubbles or other imperfection in 100 nm thin film of polymer with Rl of 1.34.