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US 6,646,718 B2Granted
Projection objective having adjacently mounted aspheric lens surfaces
AssigneeCarl Zeiss Semiconductor Manufacturing Technologies AG
InventorsKarl-Heinz Schuster, David R. Shafer, Wilhelm Ulrich, Helmut Beierl, Wolfgang Singer
Life of this patent
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Abstract
A projection objective has at least five lens groups (G1 to G5) and has several lens surfaces. At least two aspheric lens surfaces are arranged so as to be mutually adjacent. These mutually adjacently arranged lens surfaces are characterized as a double asphere. This at least one double asphere (21) is mounted at a minimum distance from an image plane (0′) which is greater than the maximum lens diameter (D2) of the objective.
Claims11
A projection objective defining a maximum lens diameter (D2) and comprising:
- a plurality of lenses defining an object plane (0) and an image plane (0′);
- at least two of said lenses having respective mutually adjacent lens surfaces which are aspheric to define a double asphere;
- said double asphere being mounted at a distance from said image plane (0′) corresponding at least to said maximum lens diameter (D2);
- the lenses of said double asphere defining a mean lens diameter;
- and,
- said mutually adjacent lens surfaces being mounted at a spacing from each other which is less than half of said mean lens diameter.
3 more elements
Dependencies are inferred from the claim text.