| 摘要 |
PROBLEM TO BE SOLVED: To provide an easy-to-manufacture optical multilayer film bandpass filter that dispenses with two sheets of edge filters in transmitting only the light beams of a prescribed wavelength region, has less polarization dependency of transmissivity, and deals with large oblique incident light beams. SOLUTION: The bandpass filter is composed of: a nonpolarized short wave pass filter (SPF) 3 in which a slope on the long wave end of a transmissivity characteristic curve is formed with an optical multilayer film against an oblique incident light of 45°angle of incidence formed on one side of a substrate 2 transparent to a target light beam; and a nonpolarized long wave pass filter (LPF) 4 in which a slope on the short wave end of the transmissivity characteristic curve is formed with an optical multilayer film against an oblique incident light of 45°angle of incidence formed on the other side of the substrate 2. In addition, respective filters 3, 4 are provided with basic structures 7, 10 which are obtained by laminating a plurality of basic blocks 7a, 10a formed by alternately laminating a high refractive index film H and a low refractive index film L, while a transmitting region is formed with one on the long wavelength end of the SPF 3 and with one on the short wavelength end of the LPF 4. COPYRIGHT: (C)2006,JPO&NCIPI
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