| 摘要 |
PURPOSE:To excellently correct various aberration, especially, Petzval's curvature of field, by constituting a meniscus lens in such a way that its refractive index can be reduced from the convex surface toward its concave surface along the optical axis and the difference in the refractive indexes can be set at >=0.15. CONSTITUTION:The power and refractive index of the convex surface 2 of a distributed index meniscus lens are respectively set at phii and Ni and the power and refractive index of the concave surface 3 are respectively set at phik and Nk. Moreover, the meniscus lens is constituted in such a way that its refractive index can be reduced from the convex surface toward the concave surface, with the difference in refractive index DELTAN being >=0.15. Therefore, the sum of Petzval's coefficients becomes very small and an equivalent effect to a cemented lens of a convex and concave lenses having a high and low refractive indexes, respectively, can be obtained. Moreover, since this meniscus lens has no cemented surface, occurrence of high-order aberration can be suppressed and Petzval's curvature of field can be corrected. In addition, occurrence of spherical aberration can be prevented. Furthermore, when one of symmetrically arranged two meniscus lenses is constituted in a distributed refractive index type, asymmetrical aberration, such as coma aberration, etc., can be corrected simultaneously and a compact lens system can be constituted.
|
