| 摘要 |
Object To provide a diffractive optical element manufacturing method through which a high-precision diffractive optical element is formed to assure an improvement in the diffraction efficiency. Means for Solving the Problems A diffractive optical element assuming cyclical stage patterns is manufactured through a procedural sequence of steps of exposing and developing a substrate 1 with a resist 2 applied thereupon by using a mask to form a resist pattern and then repeatedly etching the substrate by using resist pattern. In a first process, a pattern defining widths matching the widths of the stages to be formed is formed and greater pattern widths are set for subsequent processes. When manufacturing a diffractive optical element with seven-stage patterns, for instance, the areas to form the second, fourth and sixth stages are etched to a depth D representing the stage depth through the first process, the area to form the ninth stage is etched to a depth 2D through a second process, the area to form the fifth, sixth and seventh stages is etched to the depth 2D through a third process and the area to form the third, fourth, fifth, sixth and seventh stages is etched to the depth 2D through a fourth process.
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