A lens array for directing infrared light or radiation to a passive infrared detector having at least two Fresnel lenses mounted on or incorporated into the lens array. Each of the lenses has a different infrared detection pattern and the lenses on the array are adapted to be selectively indexed so that...http://www.google.de/patents/US6376840?utm_source=gb-gplus-sharePatent US6376840 - Selectable lens array
