Method for manufacturing nanostructure

Abstract

A method for manufacturing a nanostructure is provided, in which pores ( 3 ) having diameters on the order of nanometers (nm), the diameter decreasing as in a tapered shape, can be manufactured. The method includes repeated cycles of the alternate step of anodizing Al or an Al alloy ( 1 ) to form an anodic oxide film ( 2 ) having pores ( 3 ) in an anodizing step and increasing diameter of the pore ( 3 ) in a pore-widening step, so that the diameter of the pore ( 3 ) is varied in the depth direction.

1 . A method for manufacturing a nanostructure, the method comprising the steps of: 
 a) an anodizing step of anodizing Al or an Al alloy to form an anodic oxide film having first pores,    b) an increasing step of increasing diameters of the first pores in the anodic oxide film, and    c) an anodizing step of anodizing the anodic oxide film to form a second pore at the bottom of each first pore, wherein the second pores have different diameters to the first pores.    
     
     
         2 . The method for manufacturing a nanostructure according to  claim 1 , further comprising the step of repeating the steps a), b) and c) at least once.  
     
     
         3 . The method for manufacturing a nanostructure according to  claim 1 , wherein the diameters of the pores decrease between the first and second pores in the depth direction from the nanostructure surface.  
     
     
         4 . The method for manufacturing a nanostructure according to  claim 3 , wherein the diameter decrease is stepwise.  
     
     
         5 . The method for manufacturing a nanostructure according to  claim 3 , wherein the diameter decrease is tapered.  
     
     
         6 . The method for manufacturing a nanostructure according to any one of  claim 1 , wherein intervals between the pores are controlled by adjusting the composition, the temperature, and the applied voltage of an acidic electrolytic solution used in the anodizing step.  
     
     
         7 . The method for manufacturing a nanostructure according to any one of  claim 1 , wherein the diameters of the pores are controlled by adjusting the composition, the temperature, and the treatment time of an etching solution used in the increasing step.  
     
     
         8 . The method for manufacturing a nanostructure according to any one of  claim 1 , wherein the acidic electrolytic solution and the etching solution are phosphoric acid.  
     
     
         9 . A nanostructure manufactured by the manufacturing method according to any one of  claim 1 .  
     
     
         10 . A method for manufacturing a mold for molding a scanning lens, the method comprising the step of producing a nanostructure on a mold surface in the shape of a curved surface by the manufacturing method according to any one of  claim 1 .  
     
     
         11 . A fine structure grating produced using a nanostructure manufactured by the manufacturing method according to  claim 9 .  
     
     
         12 . A scanning lens produced using a mold manufactured by the manufacturing method according to  claim 10  and comprising the fine structure grating on a lens surface.  
     
     
         13 . An optical scanning apparatus comprising a scanning lens according to  claim 12  and an imaging optical system to direct a light beam reflected from an optical deflector to a surface to be scanned.  
     
     
         14 . An image forming apparatus comprising an optical scanning apparatus according to  claim 13  and a photosensitive drum disposed on the surface to be scanned.