| 摘要 |
PURPOSE:To obtain a practically usable copper mirror to be used for laser having extremely high durability by forming a copper mirror of copper single crystals having <=10ppm total content of oxide or sulfide of a specified atom and having a specified purity. CONSTITUTION:A copper mirror for CO2 laser is formed of single crystals of Cu having <=10ppm total content of oxides or sulfides of Cu, Al, Si, Na, K, Ca, and Mg and having >=99.999% purity of Cu. The copper having such high purity is prepd. by reducing Si, S, etc., in electrolytic copper by reelectrolyzing, melting it in an EB melting furnace to remove Na, K, etc. Particularly, invasion of Al is prevented by using a water-cooled copper casting mold in the EB melting furnace. By elevating the purity to so high value generation of plasma due to irradiation with light or decrease of reflectance are prevented, and damage of mirror is also prevented. Thus, prepn. of an extremely superior copper mirror for CO2 laser is realized.
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