Fabrication Methods for Micro Compound Optics

Abstract

Methods for fabricating refractive element(s) and aligning the elements in a compound optic, typically to a zone plate element. The techniques are used for fabricating micro refractive, such as Fresnel, optics and compound optics including two or more optical elements for short wavelength radiation. One application is the fabrication of the Achromatic Fresnel Optic (AFO). Techniques for fabricating the refractive element generally include: 1) ultra-high precision mechanical machining, e.g,. diamond turning; 2) lithographic techniques including gray-scale lithography and multi-step lithographic processes; 3) high-energy beam machining, such as electron-beam, focused ion beam, laser, and plasma-beam machining; and 4) photo-induced chemical etching techniques. Also addressed are methods of aligning the two optical elements during fabrication and methods of maintaining the alignment during subsequent operation.

1 . An optical element for short wavelength radiation, the element comprising: 
 concentric rings for focusing a beam of short wavelength radiation; and    segments extending at least partially radially between the concentric rings to support the rings.    
   
   
       2 . An optical element as claimed in  claim 1 , further comprising a frame extending around at least a portion of a perimeter of the concentric rings, segments extending between the rings and the frame to support the rings in the frame.  
   
   
       3 . An optical element as claimed in  claim 1 , wherein the optical element is a zone plate lens.  
   
   
       4 . An optical element as claimed in  claim 1 , wherein the optical element is a Fresnel refractive lens.  
   
   
       5 . An optical element as claimed in  claim 1 , wherein the concentric rings are fabricated from silicon.  
   
   
       6 . An optical element as claimed in  claim 1 , wherein the concentric rings are fabricated from copper.