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 - 6  (canceled).  
     
     
         7 . A crystalline quartz plate configured as a polarization rotator ( 14 ), wherein a crystal axis ( 17 ) of said plate is at least approximately normal to the plane of said plate.  
     
     
         8 . A crystalline quartz plate according to  claim 7 , configured as a component for an optical imaging system.  
     
     
         9 . A crystalline quartz plate according to  claim 7 , wherein said plate has a thickness of 500 μm or less.  
     
     
         10 . A crystalline quartz plate according to  claim 9 , wherein said plate has a thickness of 200 μm or less.  
     
     
         11 - 14  (canceled).  
     
     
         15 . A polarization rotator for an optical imaging system comprising a final optical element of a plurality of imaging optical elements arranged as an optical train along an optical axis, and a radial polarizer radially polarizing light transiting said optical imaging system and arranged at a location ahead of said final imaging optical element, 
 wherein said polarization rotator transforms said radially polarized light into a tangentially polarized light, and    said polarization rotator is configured to be arranged at a location following an imaging optical element of said plurality of imaging optical elements that follows said radial polarizer in the optical train.    
     
     
         16 . The polarization rotator according to  claim 15 , wherein said optical imaging system is a microlithographic projection exposure system.  
     
     
         17 . The polarization rotator according to  claim 15 , comprising a plate fabricated from an optically active material.  
     
     
         18 . The polarization rotator according to  claim 17 , wherein said plate is fabricated from crystalline quartz whose optical axis is aligned parallel to said optical axis of said optical imaging system.  
     
     
         19 . The polarization rotator according to  claim 15 , 
 wherein said optical imaging system forms a microlithographic projection exposure system, and    said polarization rotator is arranged within a section of a projection lens of said microlithographic projection exposure system where the path of an imaging beam of the projection lens is at least approximately parallel to said optical axis of said optical imaging system.    
     
     
         20 . The polarization rotator according to  claim 15 , 
 wherein said optical imaging system forms a microlithographic projection exposure system, and    said polarization rotator is arranged between a pupillary plane and an image plane of a projection lens of said microlithographic projection exposure system.    
     
     
         21 . A polarization rotator for an optical imaging system comprising a plurality of imaging optical elements arranged as an optical train along an optical axis, a radial polarizer radially polarizing light transiting the optical imaging system, said plurality of imaging optical elements including an imaging optical element arranged behind said radial polarizer in the optical train and a final imaging optical element in the optical train, said radial polarizer being arranged ahead of said final imaging optical element in the optical train, 
 wherein said polarization rotator transforms the radially polarized light into tangentially polarized light, and    said polarization rotator is configured to be arranged behind said imaging optical element in the optical train.    
     
     
         22 . The polarization rotator according to  claim 21 , comprising a plate of optically active material.  
     
     
         23 . The polarization rotator according to  claim 22 , wherein said material is a crystalline quartz material.  
     
     
         24 . The polarization rotator according to  claim 23 , wherein said plate has a crystal axis that is at least approximately normal to a plane of said plate and is at least approximately aligned parallel to the optical axis.  
     
     
         25 . The polarization rotator according to  claim 17 , wherein said plate is arranged so that an optical activity of said optically active material transforms said radially polarized light into said tangentially polarized light.  
     
     
         26 . The polarization rotator according to  claim 22 , wherein said plate is arranged so that an optical activity of said optically active material transforms said radially polarized light into said tangentially polarized light.