| 摘要 |
The invention relates to a tube lens unit that obtains a chromatically compensating effect when used with objectives having an infinite image distance and chromatic residual errors. The inventive tube lens unit fulfils the following conditions: <?in-line-formulae description="In-line Formulae" end="lead"?>CHL=CHL<SUB>o</SUB>-A<SUB>T</SUB><SUP>2</SUP>m<SUB>T</SUB>phi<SUB>T</SUB>=0 Equation (1)<?in-line-formulae description="In-line Formulae" end="tail"?> <?in-line-formulae description="In-line Formulae" end="lead"?>CHV=CHV<SUB>o</SUB>-1000lambdam<SUB>T</SUB>phi<SUB>T</SUB>d<SUB>1</SUB>=0 Equation (2)<?in-line-formulae description="In-line Formulae" end="tail"?> where CHL is the longitudinal chromatic aberration of the combination of tube lens unit plus objective, CHL<SUB>o </SUB>is the longitudinal chromatic aberration of the objective, CHV is the chromatic difference of magnification of the combination of tube lens unit plus objective, CHV<SUB>o </SUB>is the chromatic difference of magnification of the objective.
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