Optical: systems and elements – Lens – With reflecting element
Patent
1994-03-10
1997-06-03
Nelms, David C.
Optical: systems and elements
Lens
With reflecting element
359727, 359629, G02B 1700
Patent
active
056360665
ABSTRACT:
Exposure light from a pattern on a first surface advances through a first converging group, is then reflected at the periphery around an aperture on a first plane mirror, thereafter is reflected by a second converging group including a first concave reflecting mirror, and forms a first intermediate image of the pattern in the aperture of first plane mirror. A beam from the first intermediate image passes through a third converging group to form a second intermediate image of the pattern in an aperture of a second plane mirror. A beam from the second intermediate image is reflected by a fourth converging group including a second concave reflecting mirror, thereafter is reflected at the periphery around the aperture of second plane mirror, and then passes through a fifth converging group to form an image of the second intermediate image on a second surface. A projection optical system is arranged as described without using a beam splitter. The projection optical system is composed of a reflecting optical system and a refracting optical system and has little eclipse of beam and a large numerical aperture. Use of such a projection optical system permits a catadioptric projection exposure apparatus excellent in imaging performance to be provided.
REFERENCES:
patent: 4747678 (1988-05-01), Shafer et al.
patent: 4953960 (1990-09-01), Williamson
patent: 5052763 (1991-10-01), Singh et al.
patent: 5241423 (1993-08-01), Chiu et al.
Nelms David C.
Nikon Corporation
Niranjan F.
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