| 摘要 |
PROBLEM TO BE SOLVED: To provide an apochromatic object lens to which apochromatic correction is performed over a wide wavelength region, which hardly has distortion aberration even with a very large image area to be formed. SOLUTION: This apochromatic object lens includes diaphragms 4 and a plurality of optical members each of which is a refractive optical member. The optical members constitute a plurality of lens groups 1, 2, 3 and include a plurality of lenses L1, L2, L3, L4, L5, L6, L7, L8 arranged on one optical axis (X). As for the forming material of the lenses, a plurality of different kinds of materials are used. Each of the lenses L1, L2, L3, L4, L5, L6, L7, L8 is formed of any of calcium fluoride CaF2, synthetic quartz SiO2, or the other radiation resistance optical material SR. COPYRIGHT: (C)2010,JPO&INPIT
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