CPC G02B 13/0045 (2013.01) [G02B 1/041 (2013.01); G02B 9/60 (2013.01); G02B 13/02 (2013.01); G02B 27/0025 (2013.01); G02B 27/646 (2013.01); G02B 5/005 (2013.01); G02B 9/00 (2013.01); G02B 13/002 (2013.01); H04N 2101/00 (2013.01); H04N 2201/00 (2013.01); Y10T 29/4913 (2015.01)] | 16 Claims |
1. A lens system, comprising:
a lens assembly comprising a plurality of refractive lens elements arranged along an optical axis with a first lens element on an object side, wherein at least one surface of at least one of the plurality of refractive lens elements is aspheric, and wherein the lens assembly has an effective focal length EFL;
a window positioned between the plurality of lens elements and an image plane, wherein the lens system has a total track length TTL of 6.5 mm or less, a ratio TTL/EFL smaller than 1.0, a F number smaller than 2.9, and a ratio L11/L1e between a largest optical axis thickness L11 and a circumferential edge thickness L1e of the first lens element smaller than 3.08; and
a stop positioned before the first lens element, wherein the plurality of lens elements includes, in order from an object side to an image sidee, a first group comprising the first lens element, a second lens element with negative refractive power and a third lens element, and a second group comprising a first element of the second group and a second lens element of the second group, wherein the first and second groups are separated by a gap that is larger than twice any other gap between lens elements, wherein the first lens element has positive refractive power and wherein the first element of the second group and the second lens element of the second group have opposite refractive powers.
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