ABSTRACT
Flexible silicone membranes are key components for tunable optical lenses. The elastic operation of the membranes impedes the use of classical layer systems for an antireflective (AR) effect. To overcome this limitation, we equipped optical elastomer membranes with "moth-eye" structures directly in the flexible silicone substrate. The manufacturing of the AR structures in the flexible membrane includes a mastering process based on block copolymer micelle nanolithography followed by a replication method. We investigate the performance of the resulting AR structures under strain of up to 20% membrane expansion. A significant transmittance enhancement of up to 2.5% is achieved over the entire visible spectrum, which means that more than half of the surface reflection losses are compensated by the AR structures.
Subject(s)
Biomimetic Materials/chemistry , Dimethylpolysiloxanes/chemistry , Lenses , Animals , Equipment Design , Glass/chemistry , Gold/chemistry , Micelles , Microscopy, Electron, Scanning , Moths , Nanostructures/chemistry , Nanostructures/ultrastructure , Ocular Physiological Phenomena , Refractometry/instrumentationABSTRACT
In this Letter we report on the fabrication and testing of an extremely thin variable aperture stop based on the design of a single chamber adaptive membrane lens with integrated actuation. The aperture consists of a ring-shaped piezoelectric bending actuator with an elastic silicone membrane in the center. The formed cavity is filled with a nontransparent fluid and sealed with a glass platelet. In a voltage range up to 80 V, an opening of the aperture of 4.55 mm in diameter is obtained. The transmission in comparison to a standard mechanical aperture stop is maximum 6% lower.
ABSTRACT
We present an extended optical characterization of an adaptive microfluidic silicone-membrane lens at a wavelength of 633 nm, respectively 660 nm. Two different membrane variations; one with a homogeneous membrane thickness, and one with a shaped cross section, have been realized. This paper includes the theoretical predictions of the optical performance via FEM simulation and ray tracing, and a subsequent orientation dependent experimental analysis of the lens quality which is measured with an MTF setup and a Mach-Zehnder interferometer. The influence of the fabrication process on the optical performance is also characterized by the membrane deformation in the non-deflected state. The lens with the homogeneous membrane of 5 mm in diameter and an aperture of 2.5 mm indicates an almost orientation independent image quality of 117 linepairs/mm at a contrast of 50%. The shaped membrane lenses show a minimum wave front error of WFE(RMS) = 24 nm, and the lenses with a planar membrane of WFE(RMS) = 31 nm at an aperture of 2.125 mm.
