| 摘要 |
PURPOSE:To contrive improvement in the through-put of the titled exposing device as well as to simplify the constitution of the entire device by a method wherein the retreat of a part of an alignment optical system to outside the luminous flux of the optical system of illumination during each exposure is unnecessitated. CONSTITUTION:A dichroic mirror 30 is provided in such a manner that it is inclined at an angle of 45 deg. to the optical axis of a projection objective lens 1, and the main condenser 11 of the optical system of illumination 10 for exposure is arranged on the reflected light path of the dichroic mirror 30. On the transmitted light path of the dichroic mirror 30, the objective lenses 21L and 21R constituting an alignment optical system 20, and the paralleled flat surface plates 22L and 22R to be used for astigmatism correction are arranged. The paralleled flat surface plates 22L and 22R are incliningly arranged at the angle of 45 deg. to the optical axis equal to the direction reverse to the dichroic mirror 30 for the purpose of offsetting the astigmatism generating on the dichroic mirror 30 obliquely provided in a non-paralleled light path. The correction of color aberration for the first and the second wavelength lights is performed on the projection objective lens 1. |
