Precision glass molding of high-resolution diffractive optical elements

Karin Prater; Julia Dukwen; Toralf Scharf; Hans Peter Herzig; Sven Plöger; Andreas Hermerschmidt

doi:10.1117/12.2228873

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27 April 2016 Precision glass molding of high-resolution diffractive optical elements

Karin Prater, Julia Dukwen, Toralf Scharf, Hans Peter Herzig, Sven Plöger, Andreas Hermerschmidt

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Proceedings Volume 9888, Micro-Optics 2016; 98880U (2016) https://doi.org/10.1117/12.2228873
Event: SPIE Photonics Europe, 2016, Brussels, Belgium

Abstract

The demand of high resolution diffractive optical elements (DOE) is growing. Smaller critical dimensions allow higher deflection angles and can fulfill more demanding requirements, which can only be met by using electron-beam lithography. Replication techniques are more economical, since the high cost of the master can be distributed among a larger number of replicas. The lack of a suitable mold material for precision glass molding has so far prevented an industrial use. Glassy Carbon (GC) offers a high mechanical strength and high thermal strength. No anti-adhesion coatings are required in molding processes. This is clearly an advantage for high resolution, high aspect ratio microstructures, where a coating with a thickness between 10 nm and 200 nm would cause a noticeable rounding of the features. Electron-beam lithography was used to fabricate GC molds with highest precision and feature sizes from 250 nm to 2 μm. The master stamps were used for precision glass molding of a low T_g glass L-BAL42 from OHARA. The profile of the replicated glass is compared to the mold with the help of SEM images. This allows discussion of the max. aspect-ratio and min. feature size. To characterize optical performances, beamsplitting elements are fabricated and their characteristics were investigated, which are in excellent agreement to theory.

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Karin Prater, Julia Dukwen, Toralf Scharf, Hans Peter Herzig, Sven Plöger, and Andreas Hermerschmidt "Precision glass molding of high-resolution diffractive optical elements", Proc. SPIE 9888, Micro-Optics 2016, 98880U (27 April 2016); https://doi.org/10.1117/12.2228873

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