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Proceedings Paper

Expanding possibilities how to apply Bayfol HX(R) film into recording stacks and optical parts
Author(s): Friedrich-Karl Bruder; Johannes Frank; Sven Hansen; Roland Künzel; Christel Manecke; Richard Meisenheimer; Jack Mills; Lena Pitzer; Thomas Rölle; Brita Wewer
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Paper Abstract

See-through optical components are being intensively studied in applications such as Head-up-displays (HUD) and Head-mounted-displays (HMD). In particular, volume holographic optical elements (vHOE) have received a lot of attention due to their unique optical (angular and spectral selectivity) and mechanical (lightweight and thin) characteristics which make them perfectly suitable for use in integrated optical components like spectacle lenses and car windshields. Bayfol® HX photopolymer films prove themselves as easy to process recording materials for vHOEs. The Bayfol® HX instantly developing holographic photopolymer film provides full color capability and adjustable diffraction efficiency as well as an unprecedented optical clarity when compared to classical volume holographic recording materials like silver halide emulsions (AgX) or dichromated gelatin (DCG). Besides the recording step, no pre- or postprocessing is necessary and easy mass production of vHOEs in a completely dry roll to roll process is possible.

The layout of a typical Bayfol® HX film consists of a light-sensitive photopolymer layer coated onto a transparent substrate and protected on the other side by a cover film. The substrate is particularly beneficial, not only for easy handling of the film during holographic recording, but also for further mechanical processing steps which are required to embed the film into a finished optical component. However for certain applications it is desirable to remove the substrate before or after recording. This will allow the user to make full use of the high flexibility of the photopolymer layer, for example if it comes to curved surfaces that have to be covered. Also more complex stack geometries can be realized in which the photopolymer layer could be embedded in optically well designed cavities or mechanically demanding setups. To facilitate this, we developed Bayfol® HX film grades in which the substrate has a lower adhesion to the photopolymer layer compared to the protective cover film. Therefor the substrate can be removed first in contrast to existing Bayfol® HX film grades which only allow to remove the protective cover film. On the other hand the adhesion of the protective cover film can also be well controlled, so that it can be specifically selected according to the needs of the surface to which the photopolymer layer has to be transferred to. In this paper we demonstrate versatile application processes making use of these transfer grades of Bayfol® HX films with respect to adhesion design, integration in complex stacks and application on curved surfaces.

Paper Details

Date Published: 21 February 2020
PDF: 17 pages
Proc. SPIE 11306, Practical Holography XXXIV: Displays, Materials, and Applications, 113060C (21 February 2020); doi: 10.1117/12.2546220
Show Author Affiliations
Friedrich-Karl Bruder, Covestro Deutschland AG (Germany)
Johannes Frank, Covestro Deutschland AG (Germany)
Sven Hansen, Covestro Deutschland AG (Germany)
Roland Künzel, Covestro Deutschland AG (Germany)
Christel Manecke, Covestro Deutschland AG (Germany)
Richard Meisenheimer, Covestro Deutschland AG (Germany)
Jack Mills, Covestro LLC (United States)
Lena Pitzer, Covestro Deutschland AG (Germany)
Thomas Rölle, Covestro Deutschland AG (Germany)
Brita Wewer, Covestro Deutschland AG (Germany)

Published in SPIE Proceedings Vol. 11306:
Practical Holography XXXIV: Displays, Materials, and Applications
Hans I. Bjelkhagen, Editor(s)

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