Importance

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Abstract

An illuminating optical apparatus adapted to eliminate the occurrence of any exposure light quantity loss and maintain an uniform exposure condition even if the .sigma. value of an illuminating system is varied in response to changing of the pattern of a reticle to be exposed and an exposure apparatus having such illuminating optical apparatus. The illuminating optical apparatus includes an elliptical mirror for condensing an illuminating light from a light source, a collimating optical system for collimating the condensed illuminating light, an optical integrator for forming a plurality of secondary light sources from the coliminated illuminating light, and an afocal zoom optical system arranged in an optical path between the collimating optical system and the optical integrator to vary the secondary light sources in size. An image of an opening of the elliptical mirror is formed at an entrance surface of the optical integrator or in the vicinity thereof.

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First Claim