| 摘要 |
PROBLEM TO BE SOLVED: To provide a refractive index sensor which hardly suffers physical damage and is applicable for measuring a refractive index of a liquid, gas and solid.SOLUTION: There is provided a refractive index sensor which comprises: a light source 2; an optical bandpass filter 3 in which an object to be measured is in contact with a dielectric multilayer film 8 formed on one end surface 7A of an optical fiber 7 and light output from the light source 2 is incident via the optical fiber 7; a measurement unit 4 for measuring the spectrum of light reflected by the object to be measured; and a refractive index calculation unit for calculating the refractive index of reflected light on the basis of the center wavelength of the spectrum of the reflected light, wherein the dielectric multilayer film 8 has a reflective multilayer film obtained by laminating a plurality of high refractive index layers and a plurality of low refractive index layers on both sides of a cavity layer disposed approximately on the center. The combined optical thickness of the high refractive index layers and the low refractive index layers is λ0/2 when the center wavelength of the light output from the light source 2 is defined as λ0, and the optical thickness of each of the layers is different from λ0/4, respectively. |
