Projection objective having adjacently mounted aspheric lens surfaces
View Patent ↗A projection objective has at least five lens groups (G 1 to G 5 ) 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 (D 2 ) of the objective.
1. A microlithographic projection objective defining a maximum lens diameter and comprising:
a plurality of lenses defining lens surfaces and defining an object plane and an image plane;
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 from said image plane at a distance of at least said maximum lens diameter; and,
at least two additional ones of said lenses having respective mutually adjacent lens surfaces which are aspheric to define a second double asphere and the mutually adjacent lens surfaces of each double asphere being mounted at a spacing from each other of at most their mean half lens diameter measured from the optical axis.
2. The projection objective of claim 1 , wherein the mutually adjacent aspheric lens surfaces of each of said double aspheres define an air gap measured on the optical axis of a maximum of 20% of the mean radius of the corresponding asphere.
3. The projection objective of claim 1 , wherein a numerical aperture of said projection objective is at least 0.8.
4. The projection objective of claim 1 , wherein a numerical aperture of said projection objective is at least 0.9.
5. The projection objective of claim 1 , wherein two mutually adjacent lens surfaces define an intermediate space chargeable with a fluid.
6. The projection objective of claim 1 , wherein at least 40% of the lenses are spherical.
7. The projection objective of claim 1 , wherein at least 60% of the lenses are spherical.
8. A projection objective defining a maximum lens diameter and comprising:
a plurality of lenses defining lens surfaces and defining an object plane and an image plane;
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 from said image plane at a distance of at least said maximum lens diameter; and,
said projection objective having a numerical aperture of at least 0.83.
9. The projection objective of claim 8 , wherein said numerical aperture of said projection objective is at least 0.9.
10. The projection objective of claim 8 , wherein two mutually adjacent lens surfaces define an intermediate space chargeable with a fluid.
11. The projection objective of claim 8 , wherein at least 40% of the lenses are spherical.
12. The projection objective of claim 8 , wherein at least 60% of the lenses are spherical.
13. A microlithographic projection objective defining a maximum lens diameter and comprising:
a plurality of lenses defining lens surfaces and defining an object plane and an image plane;
at least two of said lenses having respective mutually adjacent lens surfaces which are aspheric to define a double asphere:
the lens surfaces of said double asphere defining radii of the same sign; and,
at least two additional ones of said lenses having respective mutually adjacent lens surfaces which are aspheric to define a second double asphere and the mutually adjacent lens surfaces of each double asphere being mounted at a spacing from each other of at most their mean half lens diameter measured from the optical axis.
14. The microlithographic projection objective of claim 13 , wherein the mutually adjacent aspheric lens surfaces of each of said double aspheres define an air gap measured on the optical axis of a maximum of 20% of the mean radius of the corresponding asphere.
15. A microlithographic projection objective defining a maximum lens diameter and comprising:
a plurality of lenses defining lens surfaces and defining an object plane and an image plane;
at least two of said lenses having respective mutually adjacent lens surfaces which are aspheric to define a double asphere;
the lens surfaces of said double asphere defining radii of the same sign; and,
a numerical aperture of said microlithographic projection objective being at least 0.8.
16. The microlithographic projection objective of claim 15 , wherein a numerical aperture of said microlithographic projection objective is at least 0.9.
17. The microlithographic projection objective of claim 15 , wherein at least 40% of the lenses are spherical.
18. The microlithographic projection objective of claim 15 , wherein at least 60% of the lenses are spherical.
19. A microlithographic projection objective defining a maximum lens diameter and comprising:
a plurality of lenses defining lens surfaces and defining an object plane and an image plane;
at least two of said lenses having respective mutually adjacent lens surfaces which are aspheric to define a double asphere;
the lens surfaces of said double asphere defining radii of the same sign; and,
two mutually adjacent lens surfaces defining an intermediate space chargeable with a fluid.