OPTICAL DEVICE

Information

  • Patent Application
  • 20070206295
  • Publication Number
    20070206295
  • Date Filed
    March 01, 2007
    17 years ago
  • Date Published
    September 06, 2007
    17 years ago
Abstract
A front group is formed of a negative first lens as a meniscus lens which is convex at the object side and a negative second lens, and a rear group is formed of a biconvex positive third lens, an aperture stop, a negative fourth lens and a biconvex positive fifth lens. The first lens is a glass lens, and the second lens is a plastic aspherical lens. The following conditions arc satisfied: −2.450, where f denotes a focal distance of a whole system, f1 denotes a focal distance of the first lens, f2 denotes a focal distance of the second lens, fI denotes a focal distance of the front group, va denotes an average value of abbe numbers of the third and the forth lenses, and vb denotes an average value of abbe numbers of the rest of the lenses.
Description

BRIEF DESCRIPTION OF THE DRAWINGS


FIG. 1 is a sectional view of an optical device according to a first aspect of the present invention;



FIGS. 2A and 2B show aberration graphs of the astigmatism and distortion;



FIG. 3 is a sectional view of an optical device according to a second aspect of the present invention;



FIGS. 4A and 4B show aberration graphs of the astigmatism and distortion according to the second embodiment;



FIGS. 5A and 5B show aberration graphs of the astigmatism and distortion according to the third embodiment;



FIGS. 6A and 6B show aberration graphs of the astigmatism and distortion according to the fourth embodiment;



FIGS. 7A and 7B show aberration graphs of the astigmatism and distortion according to the fifth embodiment;



FIGS. 8A and 8B show aberration graphs of the astigmatism and distortion according to the sixth embodiment;



FIGS. 9A and 9B show aberration graphs of the astigmatism and distortion according to the seventh embodiment;



FIGS. 10A and 10B show aberration graphs of the astigmatism and distortion according to the eighth embodiment;



FIGS. 11A and 11B show aberration graphs of the astigmatism and distortion according to the ninth embodiment;



FIG. 12 is a sectional view of the related art;



FIG. 13 is a sectional view of the related art; and



FIG. 14 is a sectional view of the related art.


Claims
  • 1. An optical device having a front group formed of a plurality of lenses and a rear group formed of a plurality of lenses, which are arranged from an object side, wherein: the front group includes a negative first lens as a meniscus lens being convex at the object side, and a negative second lens having a stronger curvature at an image side than at the object side, which are arranged in order from the object side, and the first lens is a glass lens and the second lens is a plastic aspherical lens;the rear group includes a positive biconvex third lens, an aperture stop, and a composite lens formed by combining a negative fourth lens with stronger curvature at the image side than at the object side, and a positive biconvex fifth lens in tight contact therewith; andsatisfying the following conditions for (C1) and (C2): −2.4<fI/f<−1.55   (C1)0.15<f2/f1<0.35   (C2)
  • 2. The optical device according to claim 1, wherein following conditions (C3) and (C4) are satisfied: va<29   (C3)vb>50   (C4)
  • 3. The optical device according to claim 1, wherein at least one of the lenses of the rear group is a plastic aspherical lens.
  • 4. The optical device according to claim 1, wherein a following condition (C5) is satisfied: −3.4<f3/fI<−1.4   (C5)
  • 5. The optical device according to claim 1, wherein a following condition (C6) is satisfied: −1.6<f4/fII<−1.1   (C6)
  • 6. The optical device according to claim 1, wherein a positive sixth lens formed as a plastic aspherical lens is added to the image side of the fifth lens of the rear group, and a following condition (C7) is satisfied: 4<f6/f   (C7)
  • 7. The optical device according to claim 6, wherein a following condition (C8) is satisfied: −1.2<f4/fII<−0.5   (C8)
Priority Claims (1)
Number Date Country Kind
2006-056312 Mar 2006 JP national