P. Topart, R. Beaulieu, S. Leclair, M. Poirier, J. Pelletier, M. Bernier, H. Jerominek "Replication of micro-optical elements in hybrid organic-inorganic materials" Proc. of SPIE, 4984:54-63, 2003
Résumé: In this paper, a detailed study of replication of microlenses by UV-assisted moulding in hybrid glass materials is presented. Circular aspherical, spherical and cylindrical microlenses were designed and fabricated in photoresist by using the grey-scale lithography based on high-energy beam sensitive glass. A semi-transparent replication master was then generated. Hybrid organic-inorganic resins were synthesized by sol-gel processing of functionalized alkoxysilanes. The resin viscosity and refractive index depended on synthesis conditions. Transparent, well adhering, several tens of microns-thick films were deposited on fused silica substrates by adjusting the solvent content of the formulation. The thermal expansion coefficient of our material, determined by a Michelson interferometric technique was 1.75 10-4 K-1. High replication fidelity e. g. better than 5% is demonstrated by controlling changes, at the various process steps, in the radius of curvature i.e. focal lengths of microlenses performing the measurements with a Twyman-Green interferometer. Close to diffraction limited microlenses with f-numbers ranging from f/1.4 to f/10 were fabricated.
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