| 摘要 |
PURPOSE:To obtain high power and to compensate various aberrations excellently by allowing fix group lenses to meet specific requirements. CONSTITUTION:This objective lens consists of a positive meniscus lens having the concave surface on an object side as the 1st group, a biconvex lens as the 2nd group, a positive cemented lens of a positive and a negative lens as the 3rd group, the 4th group lens, a negative cemented lens of a negative and a positive lens as the 5th group, and a negative cemented lens of a positive and a negative lens as the 6th group. Then, the focal length, refractive index, and radius of curvature of the lens are so set that an expression holds. In this case, (f), and n4 and n5 are the focal length of the whole system and the object-side and image- side focal lengths of the 3rd group lens, n6-n9 are the object-side and image- side refractive indexes of the 4th group and the object-side and image-side refractive indexes of the 5th group lens respectively, and r8, r11, and r14 are the radii of curvature of cementing surfaces of the 3rd, the 4th, and the 5th group lenses.
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