Reflection suppression via elastomeric films.

Abstract

Transparent substrates introduce challenges in optical metrology, recording, and microscopy. Backside reflections reduce signal to noise, are recorded as artifacts, or introduce spurious signals. These reflections often need to be suppressed, but large angular and spectral bandwidths preclude the use of anti-reflection (AR) coatings. Using elastomeric materials doped with optical absorbers, we detail a method and a materials set for temporary suppression of Fresnel reflections for multiple substrates spanning wide spectral and angular bandwidths. Tuning the refractive index of the elastomer to match a substrate minimizes reflection and the addition of different absorptive dopants allow for either broadband or wavelength-selective reflection suppression. As performance is limited only by the index mismatch, both spectral and angular performances significantly exceed those of AR coatings. We demonstrate reflection suppression in excess of 30 dB spanning a bandwidth over 500 nm. After use, these light traps may be removed and reused without damaging the substrate.