Wide Range Fiber-optical Superhightempe Raturesensor’s Technical Research

The measurement and the control of temperature, which is an important state parameter of material, play a meaningful role in People’s daily lives, industrial production, scientific research and many other fields. And the measurement of high temperature which is higher than2000℃plays a crucial role in fields such as metallurgy, material, energy, chemical industry, aerospace and weapons test. At present, the methods commonly used to measure temperature have certain limitations. And they cannot be directly applied to the wide range temperature measurement (30～2200℃) under harsh environment of high temperature with oxygen, strong electromagnetic radiation and severe vibration.A new ruby-sapphire composite fiber sensor of wide range temperature measurement based on contacting fluorescence lifetime measurement and blackbody radiation measurement is designed in this paper. The sensor’s measuring range is30～2200℃.The related researches open up a new space for the application and development of the ruby fiber temperature sensor and the sapphire fiber temperature sensor with non-isothermal cavity.Based on the needs of the wide range-temperature measurement under harsh environment, the paper compares and analyzes the mature contacting temperature measuring methods, chooses the fluorescence temperature measurement which is represented by ruby fluorescence fiber temperature sensor and the radiation temperature measurement which is represented by the sapphire fiber temperature sensor. Then limitations of these two temperature measurements are analyzed, and the design ideas of ruby-sapphire composite fiber sensor of wide range temperature measurement based on fluorescence lifetime measurement and contacting radiation theory is proposed.In order to achieve a composite of the two sensors, the paper designs and studies the temperature-sensing probe, the optical transmission path and the signal-regulating circuit of the composite sensor, then analyses and verifies the related key influencing factors, mainly influence the fluorescence radiation of excitation light source are analyzed in detail; A calibration-test apparatus of electric oven is set up for the lower temperature range’s calibration and testing, and another calibration-test apparatus of plasma flame is set up for the higher temperature range’s calibration and testing which use the temperature calculation, and multi-point calibration algorithm based on the compensated and corrected Plank formula. A electric oven is used to provide the environment of room temperature to500℃,and a thermocouple acts as the calibration benchmark in the lower temperature range’s experiments; And in the higher temperature range’s experiments,a plasma flame is used to provide the high temperature above2300℃, a manually regulating mechanism of three dimensions to adjust the position and the depth of heating, an infrared thermometer to provide a temperature reference to the sensor, a cooling structure of circulating water to cool down the back end and the installation structure of the sensor.Wide range temperature sensor is currently still in early period of development, and in the design of the probe, the structure of the sensor as well as the calibration and test platform, there are still some problems existing which produce certain influences on the technical specification and measurement accuracy of the sensor. In the paper these problems are simply analyzed and the preliminary ideas to solve them are put forward as the key points of the next stage of study.