Projection optical system and exposure apparatus having the same
AssigneeCanon Kabushiki Kaisha
InventorYuhei Sumiyoshi
Life of this patent
Estimating the term…
Abstract
A projection optical system used for an exposure apparatus to projecting a reduced size of an image of an object onto an image plane includes plural refractive elements that dispense with a reflective element having a substantial optical power, wherein the projection optical system forms an intermediate image.
Claims16
A projection optical system used for an exposure apparatus projecting a reduced size of an image of an object onto an image plane, said projection optical system comprising plural refractive elements,
- wherein said projection optical system forms an intermediate image,
- wherein only the plural refractive elements have optical powers in said projection optical system,
- wherein said projection optical system has only one straight optical axis, and
- wherein a maximum effective diameter of said projection optical system divided by an overall length of said projection optical system is equal to or smaller than 0.2.
A projection optical system used for an immersion exposure apparatus projecting a reduced size of an image of an object onto an image plane, said projection optical system comprising plural refractive elements, wherein:
- only the plural refractive elements have optical powers in said projection optical system,
- said projection optical system has only one straight optical axis,
- said projection optical system includes, in order from an object side to an image side, first, second, third and fourth units having optically positive powers, a first pupil being formed between the first and second units, an intermediate image surface being formed between the second and third units, and a second pupil being formed between the third and fourth units,
- a field stop is provided on or near the intermediate image surface and an iris stop is provided on or near the second pupil,
- the first, second and third units include a negative lens,
- each of the negative lens is arranged at a boundary between adjacent units that include the negative lens, and
- a maximum effective diameter of said projection optical system divided by an overall length of said projection optical system is equal to or smaller than 0.2.
Dependencies are inferred from the claim text.