Polarization rotator and a crystalline-quartz plate for use in an optical imaging system

Abstract

A polarization rotator and crystalline quartz plate for use with an optical imaging system. The system has several imaging optical components (L 1 -L 16 ) sequentially arranged along an optical axis ( 16 ), a means for creating radially polarized light arranged at a given location in that region extending up to the last of said imaging optical components, and a crystalline-quartz plate employable in such a system. A polarization rotator ( 14 ) for rotating the planes of polarization of radially polarized light and transforming same into tangentially polarized light, particularly in the form of a crystalline-quartz plate as noted above, is provided at a given location within a region commencing where those imaging optical components that follow said means for creating radially polarized light in the optical train are arranged. The optical imaging system is particularly advantageous when embodied as a microlithographic projection exposure system.

1 . A projection exposure system, comprising: 
 a plurality of imaging optical elements disposed along an optical beam path extending from a light source through an illumination system and a projection lens; and    a crystalline quartz plate arranged in the optical beam path which rotates a polarization of an imaging beam passing along said optical beam path by the optical activity of the crystalline quartz plate.    
   
   
       2 . The projection exposure system according to  claim 1 , wherein the crystalline quartz plate is disposed at a location in the beam path where the light rays propagate at least substantially parallel to an optical axis of the system.  
   
   
       3 . The projection exposure system according to  claim 1 , wherein the crystalline quartz plate is disposed with its optical axis parallel to an optical axis of the system.  
   
   
       4 . The projection exposure system according to  claim 1 , wherein a crystal axis of the crystalline quartz plate is at least approximately normal to the plane of the crystalline quartz plate.  
   
   
       5 . The projection exposure system according to  claim 1 , wherein the crystalline quartz plate has a thickness of 500 μm or less.  
   
   
       6 . The projection exposure system according to  claim 5 , wherein the crystalline quartz plate has a thickness of 200 μm or less.  
   
   
       7 . The projection exposure system according to  claim 1 , wherein the crystalline quartz plate outputs tangentially polarized light.  
   
   
       8 . The projection exposure system according to  claim 2 , wherein the crystalline quartz plate is disposed within the projection lens, along the optical beam path.  
   
   
       9 . The projection lens according to  claim 8 , wherein said crystalline quartz plate is disposed at a pupillary plane of the projection lens.  
   
   
       10 . The projection lens according to  claim 8 , wherein said crystalline quartz plate is disposed between a pupillary plane of the projection lens and an image plane of the projection lens.