25 September 2014 Moth's eye anti-reflection gratings on germanium freeform surfaces
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Abstract
Germanium is commonly used for optical components in the infrared, but the high refractive index of germanium causes significant losses due to Fresnel reflections. Anti-reflection (AR) surfaces based on subwavelength “moth’s eye” gratings provide one means to significantly increase optical transmission. As found in nature, these gratings are conformal to the curved surfaces of lenslets in the eye of the moth. Engineered optical systems inspired by biological examples offer possibilities for increased performance and system miniaturization, but also introduce significant challenges to both design and fabrication. In this paper, we consider the design and fabrication of conformal moth’s eye AR structures on germanium freeform optical surfaces, including lens arrays and Alvarez lenses. Fabrication approaches and limitations based on both lithography and multi-axis diamond machining are considered. Rigorous simulations of grating performance and approaches for simulation of conformal, multi-scale optical systems are discussed.
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Meng Liu, Meng Liu, Jason A. Shultz, Jason A. Shultz, Joseph D. Owen, Joseph D. Owen, Matthew A. Davies, Matthew A. Davies, Thomas J. Suleski, Thomas J. Suleski, } "Moth's eye anti-reflection gratings on germanium freeform surfaces", Proc. SPIE 9192, Current Developments in Lens Design and Optical Engineering XV, 91920L (25 September 2014); doi: 10.1117/12.2061421; https://doi.org/10.1117/12.2061421
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