Antireflective Structures on Highly Flexible and Large Area Elastomer Membrane for Tunable Liquid-filled Endoscopic Lens

Abstract

Antireflection coating plays a key role for an optical lens not only to minimize specular reflection but also to maximize light transmission. Antireflective structures (ARS) found in moth’s eyes play the same role with conventional antireflection coating and they also provide many intriguing features such as broadband coverage, self-antireflection, and strong water repelling. In particular, ARS on a highly flexible membrane can effectively deliver antireflection, which is hardly achieved by conventional hard coating. Here we report antireflective structures on a highly flexible elastomeric lens membrane for tunable endoscopic imaging applications. A thin antireflective membrane was fabricated by using large-area nanohole template and replica molding . The thin membrane increases light transmittance up to 96.8 % over the visible region but also enhances the image contrast up to 56 % higher than a smooth membrane during the lens deformation. The antireflective tunable liquid-filled lens offers new opportunities for compact endoscopic laparoscope with maximum transmittance and variable zoom images in a narrow and low illumination environment.