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Proceedings Paper

Parabolic transition region curve for a wedge projection display
Author(s): Kuan Wen Chen; Adrian Travis; Shun Yi Tan; Tim Wilkinson
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Paper Abstract

A wedge shaped flat panel projection display can be made by combining a slab waveguide with a tapered "wedge" waveguide sector. The sudden angle transition between the flat slab-waveguide surface and the tilted wedge-waveguide surface, sometimes called the 'kink' in a conventional wedge flat panel screen design, causes the rays which are incident at the flat slab-waveguide surface just before the kink to overlap with the rays which are incident at the tilted wedge-waveguide surface just after the kink. This paper identifies the 'kink' problem by using the reverse ray tracing technique, where parallel rays are traced from the wedge-waveguide surface back to the receiving end of the slab-waveguide. We propose a parabolic curved transition region to be inserted between the slab and the wedge waveguide as the solution to this problem, as the parabolic curved surface replaces the 'kink' with a smoother angle change between the flat and the tilted waveguide surfaces, to avoid the rays overlapping. The parabolic curve is designed to introduce collimation for the rays projected from a point light source to avoid inducing convergence or divergence to the rays which are incident at the parabolic curved surface. A thick wedge design consisting of the slab, parabola and wedge waveguides is demonstrated in this paper which shows how the ray overlapping problem for a conventional slab-wedge waveguide design can be solved.

Paper Details

Date Published: 3 February 2009
PDF: 11 pages
Proc. SPIE 7232, Emerging Liquid Crystal Technologies IV, 72320U (3 February 2009); doi: 10.1117/12.807833
Show Author Affiliations
Kuan Wen Chen, Cambridge Univ. (United Kingdom)
Adrian Travis, Cambridge Univ. (United Kingdom)
Shun Yi Tan, Cambridge Univ. (United Kingdom)
Tim Wilkinson, Cambridge Univ. (United Kingdom)

Published in SPIE Proceedings Vol. 7232:
Emerging Liquid Crystal Technologies IV
Liang-Chy Chien; Ming Hsien Wu, Editor(s)

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