Optical: systems and elements – Lens – With reflecting element
Patent
1998-05-22
2000-01-11
Epps, Georgia
Optical: systems and elements
Lens
With reflecting element
359642, G02B 1700, G02B 300
Patent
active
060142723
ABSTRACT:
A retroreflective lens includes: a single positive power lens element with an index of refraction N.sub.1 and thickness T.sub.1 ; a single negative power lens element with an index of refraction N.sub.2 and thickness T.sub.2, the negative power lens element being spaced from the positive power lens element by a distance S.sub.1 ; and a reflective surface intercepting light propagating from the negative lens element and reflecting this light toward the negative lens element. The lens elements in combination with the reflective surface provide the retroreflective lens with an F-number between F/3 and F/6. According to one embodiment N2>1.6 and N1-N2>0.15. According to another embodiment of the present invention the single negative power lens element has an integral reflecting surface and the retroreflective lens satisfies the following inequalities: N2>1.6, N2-N1>0.12. According to one embodiment of the present invention T1+T2+S1<0.15 F, where F is the focal length of the retroreflective lens.
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Eastman Kodak Company
Epps Georgia
Letendre Suzanne
Short Svetlana Z.
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