| 摘要 |
PURPOSE:To decrease loss of light by detecting the ratio of transmissivities in two wavelengths of light of a light transmittable material containing doped impurities and comparing said ratio with a calipration curve of temp. dependency of the transmissivity ratio of the material. CONSTITUTION:A sensor 1 consisting of a glass prism made of Na2O.SiO2 having Nd<3+> ions doped is set at the top end of an optical fiber 4 and is arranged in a temp. measuring atmosphere 2. The light of wide band radiated from a projector 3 passes through the fiber 4 and is made incident to the sensor 1, and the reflected light is made incident to a rotary filter apparatus 6. A narrow band zone passing filter having the peak wavelegth of lambda1-lambda3 is arranged on the disc of the apparatus 6, the pulse light of lambda1-lambda3 wavelength is made incident to a photodetector 5, the strength ratio of the light signals corresponding to the wavelengths of lambda1 and lambda3 is calculated by an arithmetic circuit 7 and the temp. is measured in comaprision with a calibration curve of temp. dependency of the strength ratio stored previously. Since visible light and infrared light can be used the transferring loss of the fiber 4 is decreased. |
