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Multifocal zone plate

  • US 4,210,391 A
  • Filed: 12/18/1978
  • Issued: 07/01/1980
  • Est. Priority Date: 09/14/1977
  • Status: Expired due to Term
First Claim
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1. A multiple focal power optical device comprising:

  • body means having a plurality of alternating odd and even, annular, concentric zones, bounded on the outside of radii rn, with n=1,3,5, . . . , for the odd zones and n=2,4,6, . . . , for the even zones;

    first focal power means within at least some of the odd zones for directing incident parallel light to a first focal point;

    second focal power means within at least some of the even zones for directing incident parallel light to a second focal point different from said first focal point;

    wherein the radii rn of said odd and even zones are substantially proportional to square root of n.

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