| 摘要 |
<p>1,079,987. Cylindrical lenses. PERKINELMER CORPORATION. Sept. 21, 1965 [Sept. 21, 1964], No.40223/65. Heading G2J. A single cylindrical lens 10 has a different value of focal length f 0 for rays such as 17 in a plane 12 normal to the cylinder axes than it has f # for rays such as 19 in a plane 14 inclined thereto and so to obtain substantially constant focal length two cylindrical lenses with parallel axes and having focal lengths f 1 , f 2 , and refractive indexes N 1 , N 2 respectively are spaced apart a distance d equal to To obtain equal back focal lengths the distance d also equals In a modification three spaced lenses are used and the relevant formulae are given in the Specification.</p> |
