| 摘要 |
PURPOSE:To correct various aberrations satisfactorily, and to obtain a satisfactory spot image formation, by constituting a lens system of 5 groups and 5 pieces consisting of 4 positive meniscus lenses and 1 negative meniscus lens, and satisfying prescribed conditions with respect to an (f).(theta) lens which is used for a facsimile, etc. CONSTITUTION:In a lens system of 5 groups and 5 pieces consisting of 4 positive meniscus lenses and 1 negative meniscus lens, the first, and the thrid - the fifth groups consist of positive meniscus lenses whose concave surface has been turned to the light beam incident direction. When radiuses of curvature of the pupil side of each lens, radiuses of curvature of the reverse side of each lens, the thickness of each lens and a lens interval, refractive indexes in the vicinity of 6,328Angstrom of each lens blank material, and a focal distance of the whole system are denoted by r1, r3, r5, r7 and r9 and r2, r4, r6, r8 and r10 and d1-d9, n1-n5 and (f), respectively, each condition of the expression (1)-(5) is satisfied. |
