Patent ID: 6031668
Filing Date: 2000-02-29
Classification: G02B

Abstract:
An optical imaging system for focusing light from an object plane onto an image plane, comprising:a rod lens array having a plurality of rod lenses with a refractive index distribution in a radial direction that are arranged in one row so that their optical axes are parallel;wherein the refractive index distribution of said rod lenses can be expressed byn(r).sup.2 =n.sub.0.sup.2 .multidot.{1-(g.multidot.r).sup.2 +h.sub.4 .multidot.(g.multidot.r).sup.4 +h.sub.6 .multidot.(g.multidot.r).sup.6 }(Eq. 1)wherein r is a radial distance from an optical axis of said rod lenses, n.sub.0 is a refractive index at the optical axis of said rod lenses, and g, h.sub.4 and h.sub.6 are coefficients of the refractive index distribution;constants a, b, c, d, and e are given bya=-10.sup.LALA=3.632-24.54(g.multidot.r.sub.0)+102.4(g.multidot.r.sub.0).sup.2 -172.8(g.multidot.r.sub.0).sup.3 (Eq. 2)b=10.sup.LBLB=3.729-28.78(g.multidot.r.sub.0)+131.4(g.multidot.r.sub.0).sup.2 -238.6(g.multidot.r.sub.0).sup.3 (Eq. 3)c=1 (Eq. 4)d=10.sup.LD .multidot.(1.789-0.6063 m+0.06225 m.sup.2)LD=2.216-18.01(g.multidot.r.sub.0)+53.51(g.multidot.r.sub.0).sup.2 -73.59(g.multidot.r.sub.0).sup.3 (Eq. 5)e=10.sup.LE .multidot.10.sup.LE2LE=5.327-47.81(g.multidot.r.sub.0)+197.7(g.multidot.r.sub.0).sup.2 -334.2(g.multidot.r.sub.0).sup.3LE2=0.2460-0.1669 m+0.00056 m.sup.2 (Eq. 6)wherein r.sub.0 is a radius of a portion of said rod lenses functioning as a lens, and m is an overlapping degree; andthe refractive index distribution coefficients h.sub.4 and h.sub.6 are in ranges defined byc-d.ltoreq.h.sub.4 .ltoreq.c+d (Eq. 7){(h.sub.4 -c)/d}.sup.2 +[{h.sub.6 -(a.multidot.h.sub.4 +b)}/e].sup.2 .ltoreq.1. (Eq. 8)