| 摘要 |
PURPOSE:To realize an aspherical single lens with about 0.12-0.2 N.A and with spherical aberration and sine condition compensated well, by constituting a single lens, whose face in the exit side of parallel light is a spheroidal face having a positive refracting power so that this elliptic face of revolution satisfies specific conditions. CONSTITUTION:The single lens whose face in the exit side of parallel light is a spheroidal face having a positive refracting power is so constituted that the spheroidal face satisfies not only a formula I where X, (h), C1, and K are the distance of a point on the aspherical face from a plane contacting with the apex of the aspherical face, the height from an optical axis, the curvature of the apex of the elliptic face, and the constant of cone respectively but also formulas IIand III where R1, (f), and (n) are 1/C1 (the radius of curvature of the apex of the elliptic face), the focal length of the lens, and the refractive index of the lens respectively. Thus, the precision of each face is measured easily with an about 1/(10) of a used wavelength by an ordinary interferometer, and spherical aberration and sine condition are compensated well. |
