| 摘要 |
PURPOSE:To raise the performance of a Gauss type lens as an image-forming lens of a facsimile, etc. by constituting a Gauss type lens consisting of four groups and six pieces, and satisfying a specified conditional inequalities. CONSTITUTION:A Gauss type lens 13 placed between original placing glass 11 and protecting glass 12 of a solid-state image sensor is constituted of the first group lens being the first positive lens 14 whose convex face is turned to an object field side, the second group lens being a cemented lens consisting of the second positive lens 15 whose convex face is turned to the object field side and the third negative lens 16, the third lens group being a cemented lens consisting of the fourth negative lens 17 whose convex face is turned to an image field side and the fifth positive lens 18, and the fourth lens group being a positive single lens (the sixth lens) 19, and is constituted so as to satisfy conditional inequalities I -XII. According to this constitution, brightness can be set to about 1.8, and as to a view angle, too, when using a symmetrical type, a half view angle used in infinity can be set to about 24 deg.. |
