| 摘要 |
PROBLEM TO BE SOLVED: To provide an ND filter, having the transmissivity with improved flatness and capable of enhancing the yield. SOLUTION: The ND filter has a first absorbing film formed on the first plane of a substrate, having a first plane and a second plane mutually facing in the opposite direction, and a second absorbing film formed on the second plane of the substrate. The transmissivity of the first absorbing film and that of the second absorbing film are mutually compensated, and uniform transmissivity is provided, extending over a wavelength range of 400-700 nm. COPYRIGHT: (C)2007,JPO&INPIT
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