Single optical lens with large aperture and large field
Large-aperture single lens with aspherical surfaces
Lens system for optical recording type disks
Lens system for optical disks
Objective lens system for optical reading device
Aspherical single lens
Single optical lense with diffraction limit converging capability and wide field angle Patent #: 4842388
ApplicationNo. 343256 filed on 04/26/1989
US Classes:359/708Including a nonspherical surface
ExaminersPrimary: Dzierzynski, Paul M.
Attorney, Agent or Firm
Foreign Patent References
International ClassG02B 013/18
AbstractA lens controls the chromatic aberration of an objective lens for practical use in an optical disk system. The lens has first and second aspherical surfaces each providing a positive refractive power for focusing a light through a transparent plate and satisfies a condition: ##EQU1## where fL =focal length of the lens, dc =thickness of the transparent plate, nc =refractive index of the transparent plate, λ=center wavelength of the light, NA=numerical apperture of the lens, νL =local dispersion of the lens, and νc =local dispersion of the transparent plate. The local dispersion of each element is expressed by: ##EQU2## where n80 is refractive index at a center wavelength λ nm, nλ +5 a refractive index at λ+5 nm, and nλ -5 a refractive index at λ-5 nm.