| 摘要 |
PROBLEM TO BE SOLVED: To continuously measure a liquid level in a measurement container without being affected by the property of an object to be measured by continuously measuring temperature distribution in the measurement container using an optical fiber thermometer where the Raman scattering effect is applied. SOLUTION: An optical fiber thermometer 1 where the Raman effect of an optical fiber has been applied applies a high-speed light pulse to an optical fiber 8 and separates scattering light being reflected from each point of the optical fiber 8 into low-frequency and high-frequency components by a frequency separation circuit 2. One of them is related to the physical properties of the optical fiber 8, while the other is related to the physical properties and a reflection surface temperature. Therefore, the temperature of the reflection surface can be measured according to the ratio of the strength of the two frequency components by a frequency component strength ratio operation circuit 3. A temperature operation circuit 4 calculates the temperature of each point in a measurement container 7 according to a temperature signal that is outputted by the frequency component strength ratio operation circuit 3. Then, a liquid level measurement circuit 5 converts the temperature of each point being outputted by the temperature operation circuit 4 to calculate a liquid level.
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