| 摘要 |
PURPOSE:To eliminate a chromatic aberration, to widen a fiedl of view, and to improve resolution by relaying an image by an objective lens of a retrofocus type by a relay lens consisting of a refractive index distribution type lens, and observing its image by an eyepiece system. CONSTITUTION:A front group lens L1 is formed by a concave lens 11, a glass block 13 having a diaphragm 12 in the inside, and a convex lens 14. A rear group lens L2 is formed by joining a convex lens 15 and a concave lens 16. An objective lens of a retrofocus type is constituted of the lens group L1 and L2. Also, a view diaphragm 17 is provided between the rear end face of the lens 16 and a refractive index distribution type relay lens 2 and both end faces are to adhered to each other. As a result, a chromatic aberration is corrected, an aberration regarding image formation is also corrected, its resolution is improved, and a wide picture angle can be set freely. Also, a bright picture is obtained up to the circumference of a field of view by eliminating a black part of the circumferential part by the view diaphragm 17. This optical system is suitable to a hard endoscope for infant. |
