| 摘要 |
PROBLEM TO BE SOLVED: To provide a phase diffraction optical device which can be easily manufactured with satisfactory accuracy and to provide a method for manufacturing the device. SOLUTION: The phase diffraction optical device has random phase distribution, in which a large number of unit patterns having different phase modulation functions are arranged with each unit pattern, consisting of recesses and projections having a period shorter than the wavelength of the light to be used, and different phase modulation functions in the unit patterns are obtained, by varying the width ratio of the recesses and projections in the recessed and projected part. Using the method for manufacturing the phase diffraction optical device, a resist layer is formed on a substrate, irradiated with electron beam or a laser beam and developed to remove a part of the resist layer to form a surface having recesses and projections, then a metal layer is formed on the recesses and projections, the resist layer with the metal layer is lifted off, and the surface after the lift-off process is etched to form recesses and projections.
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