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Proceedings Paper

Diffractive surfaces for cat-eye array retro-reflectors
Author(s): I. Glaser
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Paper Abstract

Cat-eye-array retro-reflectors, combining a lenslet array with a reflective surface at the common focal plane of the lenslets, are widely used due to their simple structure and low cost. While for many applications the performance (brightness, acceptance angle range and directionality) is acceptable, others could benefit from better performance. Improving these retroreflectors is difficult because their simplicity results in too few degrees of freedom. Here, we show how the use of one or two diffractive surfaces can significantly increase the brightness of the reflected beam and/or the acceptance angle while still allowing inexpensive manufacturing by molding or replication. Specifically, we focus here on one potential application of cat-eye-array retro-reflectors: semipassive optical communication units. Semi-passive communication units combine a retroreflector with a light modulator. The directional auto-aligned retro-reflected signal enhances security and power efficiency. Furthermore, many modulators use very low power: far lower than light emitter. Modulated retro-reflectors have already been demonstrated for space and military communication. Here we focus on a different application: optical smart cards. These devices described elsewhere, can be used, for example, for access control identification or as non-contact secure teller machine ID. Such devices must have an optical modulator in the optical path, so the effect of the modulator must also be accounted for in the design. As a consumer product, low cost manufacturability is another requirement. Design examples are presented.

Paper Details

Date Published: 27 September 2008
PDF: 9 pages
Proc. SPIE 7100, Optical Design and Engineering III, 71001Q (27 September 2008); doi: 10.1117/12.797253
Show Author Affiliations
I. Glaser, Holon Institute of Technology (Israel)

Published in SPIE Proceedings Vol. 7100:
Optical Design and Engineering III
Laurent Mazuray; Jean-Luc Tissot; Jeffrey M. Raynor; Rolf Wartmann; Andrew Wood, Editor(s)

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