摘要 |
In producing an etalon, a thickness of an etalon base plate is measured, and the etalon base plate is placed in a process chamber. Then, a gas having a chemical reactivity with respect to a material of the etalon base plate is introduced into the process chamber, and a surface of the etalon base plate is etched for only a predetermined time corresponding to a thickness of the etalon base plate, thereby obtaining the etalon having a desired thickness.
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