PURPOSE: To obtain a shading-less and compact image-forming lens, by attaching a positive refracting power as a whole, and satisfying specific conditions by the lenses in a front group and a rear group.
CONSTITUTION: As basic constitution, the image-forming lens to image-form an image formed by a microscope objective lens designed at infinity at a prescribed position is employed, and it is formed with two groups, the front group GF consisting of the joint lens of a positive lens and a negative lens, and the rear group GR consisting of a positive single lens and a negative single lens or the rear group GR consisting of the joint lens of the positive lens and the negative lens, and a positive refracting power is attached as a whole, and they are arranged in the above sequence from an objective side. And assuming the focal distance of the front group GF as fF, the focal distance of the whole system as (f), the radius of curvature of the lens in the rear group GR at the object side being positioned at a position nearest to the object as r4, the radius of curvature of the lens in the rear group GR at an image side being positioned at the position nearest to the image side as r6, and the interval of the lens between the front group GF and the rear group GR as d3, the conditions of equations IWIII are satisfied simultaneously. In such a way, it is possible to obtain a compact image-forming lens without the shading of a beam of light.
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