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Proceedings Paper

How post-processing by selective thermal reflow can reduce the roughness of 3D lithography in micro-optical lenses
Author(s): Robert Kirchner; Nachiappan Chidambaram; Mirco Altana; Helmut Schift
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Paper Abstract

Most polymeric refractive micro-optics simultaneously demand ultra-smooth 3D topographies and precise geometry for high optical performance and low stray light. We have established a surface selective smoothening for thermoplastic polymers that does not affect the designed optical geometry. For example, high curvature corners required for a 50 μm tall optical diffuser device were maintained while the surface roughness was reduced to about 10 nm RMS. 3D master structures were fabricated using direct write laser-lithography with two-photon absorption. Master structures were then replicated into poly(methyl methacrylate) through a poly(dimethyl siloxane) intermediate copying step and subsequently smoothed-out by high-energy photon exposure and thermal post-processing. The smoothening results in a lower roughness compared to a direct writing strategy using even about 50 nm vertical discretization steps still enables 10 times faster writing times.

Paper Details

Date Published: 24 February 2017
PDF: 9 pages
Proc. SPIE 10095, Laser 3D Manufacturing IV, 1009507 (24 February 2017); doi: 10.1117/12.2258090
Show Author Affiliations
Robert Kirchner, Paul Scherrer Institut (Switzerland)
Nachiappan Chidambaram, Paul Scherrer Institut (Switzerland)
Mirco Altana, Heptagon Oy (Switzerland)
Helmut Schift, Paul Scherrer Institut (Switzerland)

Published in SPIE Proceedings Vol. 10095:
Laser 3D Manufacturing IV
Bo Gu; Henry Helvajian; Alberto Piqué; Corey M. Dunsky; Jian Liu, Editor(s)

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