| 摘要 |
PROBLEM TO BE SOLVED: To obtain a condenser lens by which a focal distance can be shortened while realizing high NA at a long actuation distance, an aperture diaphragm, etc., can be arranged at a pupil position and the image-formation performance of a field diaphragm can be improved by specifying the constitution of the lens. SOLUTION: The condenser lens is a retrofocus type one constituted of a 1st lens group G1 having negative refractive power and a 2nd lens group G2 having positive refractive power, and the front side focus F of the 2nd lens group G2 is positioned between the 1st and the 2nd lens groups G1 and G2, then the 2nd lens group G2 includes at least a positive bonded lens obtained by bonding a concave lens and a convex lens. By constituting the condenser lens in such a way, the focal distance is made short while realizing the high NA at the long actuation distance. Since the front side focus F is positioned between the 1st and the 2nd lens groups G1 and G2, sufficient space is secured in the vicinity of the pupil position of the condenser lens and the aperture diaphragm etc., can be arranged at the pupil position.
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