CPC G02B 13/18 (2013.01) [G02B 3/04 (2013.01); G02B 3/08 (2013.01); G02B 5/04 (2013.01); G02B 25/00 (2013.01); G02B 27/0172 (2013.01); G02B 27/02 (2013.01)] | 8 Claims |
1. A lens system, comprising:
a Fresnel lens having a lens surface including a plurality of grooves that are concentrically formed, wherein:
both a pitch that is a distance between two adjacent grooves and a depth of each of the plurality of grooves vary with a distance from an optical axis that passes through a center of the lens system,
a distance from a center of the Fresnel lens and the pitch are defined as X (mm) and P (mm), respectively,
when 0 mm≤X≤10 mm, X and P satisfy following conditions:
P≤(0.00021(X−10) 4+0.6)×1.5
P≥(0.00021(X−10) 4+0.6)×0.5, and
when 10 mm≤X, P satisfies a following condition:
0.3≤P≤0.9.
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