| 摘要 |
A method for producing diffractive optic molding tools with improved durability is accomplished by depositing a layer of chromium carbide (54) on a substrate material (50). This layer of chromium carbide becomes the receptor for a final machinable coating such as electroless nickel (56). The pattern (60) for the desired diffractive surface is predetermined and a single-point-diamond turning machine is used to cut the negative of this predetermined pattern into the machinable layer to produce the pattern of concentric zones to the required depths. The pattern is then uniformly etched in the machinable layer down into the intermediate layer of chromium carbide resulting in the complete removal of all of the electroless nickel. In that the etching rates of electroless nickel and chromium carbide differ from one another, it is necessary to dimensionally adjust the negative pattern turned into the electroless nickel surface to allow for the different etch rates. In such manner, an extremely durable molding surface of chromium carbide is achieved. <IMAGE> |
