Birefringence optical element and manufacturing method thereof

Abstract

A mask with an opening pattern is placed on a substrate, and etching is carried out by use of anisotropy etching of crystal. The opening pattern of the mask is composed of broken lines, each of which is discontinued by discontinuing portions. By the etching, a birefringence optical element with a fine structure, in which trenches, each of which is discontinued by discontinuing portions, are juxtaposed periodically at a specified pitch, is obtained.

1 - 8 . (canceled)  
     
     
         9 . A method for producing a birefringence optical element comprising a plurality of trenches which are juxtaposed periodically at a specified pitch so as to cause structured birefringence, 
 wherein in an etching process of etching a substrate, a mask with an opening pattern for transfer of the trenches is placed on the substrate, the opening pattern of the mask being composed of broken lines, each of which is discontinued by discontinuing portions.    
     
     
         10 . A method according to  claim 9 , wherein the etching process is carried out by use of anisotropy etching of crystal.  
     
     
         11 . A method according to  claim 9 , wherein the etching process is a wet etching process.  
     
     
         12 . A method according to  claim 9 , wherein the substrate is a semiconductor monocrystal.  
     
     
         13 . A method according to  claim 12 , wherein the semiconductor monocrystal is silicon.  
     
     
         14 . A method according to  claim 12 , wherein the semiconductor monocrystal is silicon with a (110) surface.  
     
     
         15 . A method for producing a birefringence optical element comprising a plurality of trenches which are juxtaposed periodically at a specified pitch so as to cause structured birefringence, 
 wherein in an etching process of etching a substrate, a mask with an opening pattern for transfer of the trenches is placed on the substrate, the opening pattern of the mask being composed of lines, each of which is discontinued by at least one discontinuing portion.    
     
     
         16 . A method according to  claim 15 , wherein the etching process is carried out by use of anisotropy etching of crystal.  
     
     
         17 . A method according to  claim 15 , wherein the etching process is a wet etching process.  
     
     
         18 . A method according to  claim 15 , wherein the substrate is a semiconductor monocrystal.  
     
     
         19 . A method according to  claim 18 , wherein the semiconductor monocrystal is silicon.  
     
     
         20 . A method according to  claim 18 , wherein the semiconductor monocrystal is silicon with a surface.