April 24, 2025
      
                  
        
  Author(s)
  Aaron  Chew,   Bryan  Barnes,   Eric  Shirley,   Thomas  Germer
 
       
            
    
    
        We propose and analyze the sensitivity of an ellipsometer that uses extreme ultraviolet (EUV) light from the synchrotron SURF-III. The ellipsometer employs a four-mirror geometry to control polarization, as documented in the associated patent. With a