| 摘要 |
PROBLEM TO BE SOLVED: To observe or photograph a sample in plural magnification sates in an extremely low magnification area by positioning am auxiliary lens for extremely low magnification an optical path when a 1st objective lens for extremely low magnification is positioned in the optical path and satisfying specified conditions. SOLUTION: The 1st lens 10 for extremely low magnification attached to a revolver 20 is constituted of a positive 1st group and a negative 2nd group, and the positive auxiliary lens S for extremely low magnification is constituted to be freely inserted in and pulled out from the optical path between the 1st objective lenses 10 and 11 and the 2nd objective lens, and combined and used with the lens 10. The conditions: 1<=(D+L)/fS<=1.5, 50<=L<=200, and 12<=|ν1S-ν2S|are satisfied. Provided that D is the parfocal distance of the microscope, fS is the focal distance of the lens S,ν1S andν2S are the Abbe number of the lens elements having the largest Abbe number and the smallest Abbe number of the lens S, and L is a distance from the shoulder surface of the lens 10 to the lens surface nearest to an image side of the lens S.
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