Title:
LENS FOR OPTICAL RECORDING AND REPRODUCING DEVICE
Document Type and Number:
Japanese Patent JPH01155309
Kind Code:
A
Abstract:
PURPOSE:To compensate aberrations excellently and to increase a NA by putting two lenses in partial charge of the refracting power of an optical system and using a radially distributed index type medium as one lens material. CONSTITUTION:This lens consists of two single lenses and divergent luminous flux from a light source or parallel luminous flux is condensed on an information recording surface. One of the two lens elements is made of a medium which has a refractive index n(r) at a position of a distance (r) from the optical axis and also has a radial refractive index distribution shown by an expression I. The bright optical system whose NA is 0.5-0.55 is constituted by using those two spherical or plane lenses [n0: refractive index on the optical axis, (g), h4, h6, and h8: distribution constant, z0: lens thickness on the optical axis, r0: radius of lens].
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Inventors:
KIKKO SHIGEO
Application Number:
JP31577987A
Publication Date:
June 19, 1989
Filing Date:
December 14, 1987
Export Citation:
Assignee:
NIPPON SHEET GLASS CO LTD
International Classes:
G02B13/00; G02B9/06; G11B7/135; (IPC1-7): G02B9/06; G02B13/00; G11B7/135
Attorney, Agent or Firm:
Ohno Seiichi