| 摘要 |
PROBLEM TO BE SOLVED: To provide a scale having an optical grating with improved stability of diffraction efficiency. SOLUTION: After a first metal layer 21 made of tungsten is formed on the substrate 17 of a scale, a second metal layer 23 made of chromium is formed on the first metal layer 21. The second metal layer 23 is selectively removed by using a resist 27 as a mask and the first metal layer 21 as an etching stopper, whereby an optical grating 19 is formed. The optical grating 19 is a phase grating whose sidewall includes an angle of larger than 80 degrees and smaller than 90 degrees. COPYRIGHT: (C)2011,JPO&INPIT
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