| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical filter which attains the optical properties close to those of the conventional multilayer film filter by microfabricating a substrate to allow the transmitted light to have a refractive index distribution and which has high reliability.SOLUTION: The optical filter, which has a band-pass characteristic to transmit the light of a predetermined wavelength band includes: a substrate 2; and an upper block 1 and a lower block 3 which are arranged on at least one main surface side of the substrate 2. Each of the upper block 1 and the lower block 3 has a minute periodic structure made of the same material as that of the substrate 2 and an effective refractive index to be fixed by dividing the refractive index of the material and that of the space proportionally by an area ratio. The minute structure has a periodic structure smaller than that of the lower limit of the transmitted wavelength band. |
