| 摘要 |
PURPOSE: A device for measuring a refractive index structure of the surface of an optical fiber or an optical waveguide is provided to project three laser beams having different wavelengths on the surface of the optical fiber or the optical waveguide as scanning the surface, and to measure reflection rate changes on the surface according to each location in the state of maintaining scanning height, so as to precisely measure a refraction rate distribution having a high signal to noise ratio. CONSTITUTION: A lens(12) induces a light coming from a reflection surface(16), which forms focal points of three laser beams(L1,L2,L3) of an optical fiber end(10a') or measures a refraction rate structure, to an optical fiber(10a) again. A PZD(PieZo electric Transducer) adjusts a distance between the optical fiber end(10a') and the lens(12) in proportion to a voltage generated by light strength differences between the laser(L1) having a short wavelength and the laser(L2) having a long wavelength. WDMs(Wavelength Division Multiplexers)(WDM1,WDM2) induce the laser beams(L1, L2, L3) through an optical fiber(10b) or make reflected lights proceed toward the laser beams(L1,L2,L3). PCs(Photo Couplers)(PC1,PC2,PC3) divide or couple the laser beams(L1,L2,L3). PDs(Photo Detectors)(PD1,PD2,PD3) measure the strength of the laser beams coming through the PCs(PC1,PC2,PC3). A DA(Differential Amplifier) subtracts the strength of a light of the PD2 from the strength of the PD1, and amplifies the light. An x-axis scanner(XSC) and a y-axis scanner(YSC) scan the reflection surface(16) to measure the strength of a light reflected from the middle-wavelength laser(L3) detected from the PD3.
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