| 摘要 |
PURPOSE:To perform correction with high power and excellent chromatic aberration by composing the objective lens of a front group with positive refracting power and a rear group with negative refracting power, and specifying relations between their focal lengths, radii of curvature, and Abbe numbers. CONSTITUTION:The objective lens consists of the front group with positive refracting power which has a positive and a negative meniscus lens element and converts luminous flux from a body into convergent luminous flux and the rear group which is arranged at the image side of the front group and constituted by cementing a negative and a positive lens element together. Inequalities hold, where f1 and f2 are the focal lengths of the front and rear groups, R1 and R4 are the radii of curvature of the surfaces of the rear groups closest to the object side and image side, and V1, V2, and V3 are the Abbe numbers of the object-side lens element, positive lens element, and image-side negative lens element of the rear group. Consequently, the achromate objective lens of extremely rear group. Consequently, the achromat objective lens of extremely high power is realized while various aberrations, specially, the chromatic aberration is corrected. |
