| 摘要 |
PURPOSE:To make it possible to obtain a polygonal mirror for high speed laser printers or the like, having an excellent reflectivity, by cutting and then cooling an aluminum material in the atmosphere of inert gas and oxygen gas, and as well by surface-treating the same with plasma. CONSTITUTION:While reciprocating a shaft 2 the mixture of argon gas and O2 gas is jetted from a nozzle 2, and a mirror section in a workpiece W having aluminum as a main component is cut by a cutting tool 4 and then cooled. When plasma 17 is created by a discharge electrode 11 so that the plasma 17 traces the cut section, an aluminum oxide film layer 8 which is as minute as sapphire is formed on the cut surface. Then the film layer 8 is removed at the next step, and a film made of mirror-surface materials such as, for example, pure aluminum, is formed on the cut surface by vapor coating. Due to coating at once the thin layer 18 the film made of mirror-surface materials are uniformly and firmly formed with no pin holes, thereby a highly reflective polygonal mirror may be obtained. |
