| 摘要 |
PURPOSE: A projection objective lens is provided to realize a maximum aperture value in a case where a diameter of a lens is minimum, considering an additional quality necessary for a micro lithography-projection objective lens. CONSTITUTION: A projection objective lens comprises a first lens group(LG1) of a positive refraction, a second lens group(LG2) of a negative refraction, a third lens group(LG3) of a positive refraction, a fourth lens group(LG4) of a negative refraction and an addition lens(LG5-LG7) having an aperture iris(AS). At least one(L21,L24) of two lenses(L21,L22; L23,L24) of the addition lens(LG5-LG7) is disposed in front/back of the aperture iris(AS) so as to have a negative refraction.
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