| 摘要 |
PURPOSE:To obtain a titled lens which has corrected an aberration on the axis and outside the axis, and has a numerical aperture of >=0.4 by forming an aspherical surface of a positive meniscus single lens whose first surface is positive and an aspherical surface, and whose second surface has a negative refractive power, to a prescribed shape, and also satisfying prescribed conditions. CONSTITUTION:The first surface R1 being an aspherical surface of a lens 1 is formed as shown by an expression I. In this expression, Z:(y):(c):(k): and D, E, F and G denote a distance from a tangential plane of an aspherical surface apex of a point on an aspherical surface whose height from an optical axis is (y), a height from the optical axis, a curvature 1/R of the aspherical surface apex, a cone constant, and coefficients of aspherical surfaces, respectively. Also, this optical system satisfies various conditions of an expression II - an expression V. In this regard, in these expressions, n1:R1:R2: and d1 denote a refractive index in a working wavelength of the lens 1, a radius of curvature of the aspherical surface apex of the first surface, a radius of curvature of the second surface, and a thickness of the center of the lens 1, respectively.
|
