Diffractive surfaces for cat-eye array retro-reflectors

I. Glaser

doi:10.1117/12.797253

27 September 2008 Diffractive surfaces for cat-eye array retro-reflectors

I. Glaser

Proceedings Volume 7100, Optical Design and Engineering III; 71001Q (2008) https://doi.org/10.1117/12.797253
Event: Optical Systems Design, 2008, Glasgow, Scotland, United Kingdom

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.

Citation Download Citation

I. Glaser "Diffractive surfaces for cat-eye array retro-reflectors", Proc. SPIE 7100, Optical Design and Engineering III, 71001Q (27 September 2008); https://doi.org/10.1117/12.797253

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