Mold for molding optical glass and method of manufacturing optical glass element

Abstract

A substrate protective film composed of chromium metal is formed on a molding surface of a mold base material composed of cemented carbide. The substrate protective film is oxidized by heat-treatment or ion implantation, so that a surface protective film composed of chromium oxide is formed. A pair of molds having such a constitution are prepared. Softened glass is pressed between the surface protective films of the paired molds, so that optical glass elements are molded.

1 . A mold for molding optical glass comprising: 
 a mold base material;    a substrate protective film composed of chromium metal formed on a molding surface of said mold base material; and    a surface protective film composed of chromium oxide formed on said substrate protective film.    
   
   
       2 . A mold according to  claim 1 , wherein said surface protective film is manufactured by giving an oxidation treatment to said substrate protective film.  
   
   
       3 . A mold according to  claim 2 , wherein the oxidation treatment includes a heat treatment carried out in an atmosphere including oxygen.  
   
   
       4 . A mold according to  claim 3 , wherein the heat treatment is carried out under conditions of 400° C. to 600° C. and 30 minutes to 90 minutes.  
   
   
       5 . A mold according to  claim 2 , wherein the oxidation treatment implants oxygen ion.  
   
   
       6 . A mold according to  claim 1 , wherein said substrate protective film has a thickness of 0.05 to 10 μm  
   
   
       7 . A mold according to  claim 1 , wherein said mold base material is made from cemented carbide.  
   
   
       8 . A method of manufacturing optical glass element, comprising the steps of: 
 preparing a pair of molds including a mold base material, a substrate protective film composed of chromium metal formed on a molding surface of the mold base material, and a surface protective film composed of chromium oxide formed on the substrate protective film; and    pressing glass using the paired molds.    
   
   
       9 . An optical glass element manufactured by the process comprising the steps of: 
 preparing a pair of molds including a mold base material, a substrate protective film composed of chromium metal formed on a molding surface of the mold base material, and a surface protective film composed of chromium oxide formed on the substrate protective film; and    pressing glass using the paired molds.