| 摘要 |
PURPOSE:To correct satisfactorily a spherical aberration by sticking a refractive index distribution type line whose refractive index is varied in the radial direction, and a lens consisting of a homogeneous medium, and equalizing refractive indexes of both the lenses at a prescribed position in the effective diameter of the lens. CONSTITUTION:A cemented lens consists of a refractive index distribution type lens 2 having such a variation as the refractive index drops gradually in the radial direction centering around the optical axis, and a lens 1 consisting of a homogeneous medium. As for these two lenses 1, 2, a difference of the refractive indexes scarcely exists in the vicinity A of the optical axis, therefore, a refraction of light does not occur, but at a point B separated from the optical axis, a refraction occurs due to a difference of the refractive indexes. As a result, on the cemented surface, in the point separated from the optical axis, a refractive index of a luminous flux becomes large. Accordingly, an out-of-axis luminous flux in each image height can be led in a desired direction, and a spherical aberration can be corrected satisfactorily by only one lens. |
