| 摘要 |
PURPOSE:To prevent a projection lens of less spherical aberration, astigmatism, and coma aberration through which a good spot image is focused, by constituting the lens with four groups of four lenses, namely, three positive meniscus lenses and one negative meniscus lens. CONSTITUTION:The first lens 7 of the first group where the length on the axis between lens faces having radiuses r1 and r2 of curvature is d1, the second lens 8 of the second growup where the length on the axis between lens faces having radiuses r3 and r4 of curvature is d3, the third lens 9 of the third group where the length on the axis between lens faces having radiuses r5 and r6 of curvature is d5, and the fourth lens 10 of the fourth group where the length on the axis between lens faces having radiuses r7 and r8 of curvature are so arranged that the length on the axis between the first lens 7 of the first group and the second lens 8 of the second group is d2, that between the second lens 8 of the second group and the third lens 9 of the third group is d4, and that between the third lens 9 of the third group and the fourth lens 10 of the fourth group is d6 respectively, and lenses 7, 9, and 10 are constituted with positive meniscus lenses, and the lens 8 is constituted with a negative meniscus lens. They are constituted to satisfy 1.00<¦r2/r3¦<1.08, -0.50f<r6<-0.42f, -1.85f<r7<-1.60f, and 0.010f< d4<0.050f. |
