| 摘要 |
PURPOSE:To constitute so that a focal surface scarcely becomes out-of-focus by forming an aspherical part to a spherical surface extending from an optical axis to a prescribed height, and forming its circumferential part by an aspherical surface. CONSTITUTION:In an optical system consisting of one or plural lenses, at least one surface is constituted of a spherical surface to a height H from an optical axis, and an aspherical surface is formed extending to the circumferential part from H, so that each of them becomes a continuous shape. Also, when the outside diameter of the lens containing the aspherical surface, a radius of curvature of the spherical surface, and a height from the optical axis in case when an axial beam of 1:4 aperture ratio is made incident to the aspherical surface are denoted as phi, (r) and (h) respectively, conditions of phi/30<H<phi/4, h/3<=H<= h, and ¦r¦<30f are satisfied. |
