Research On High-temperature Sapphire Optical Fiber Sensor

In the system of twin-roll casting, temperature of molten steel in molten pool affects the quality of steel billets. So, the temperature must be measured accurately and quickly. This paper studied a high-temperature sapphire optical fiber sensor which aims to measure the temperature of molten steel in molten pool.In this essay, the following four tasks are finished:essay1. The theories are analyzed. Studying lots of research data from NEU cast-rolling laboratory, the colorimetric temperature measurement is successfully derived based on the theory of blackbody radiation.2. The key technology is studied. The feasibility that the sapphire optical fiber can be used as high temperature detector is shown through analyzing the physical and chemical properties of the sapphire optical fiber; The length of blackbody cavity is determined through analyzing the blackbody cavity radiation model; The central wavelength and bandwidth is determined through analyzing the parameters affecting the colorimetric temperature measurement model; The analysis of the Loss characteristics of silica fiber lays the foundation for the design of the fiber system.3. The circuits are designed, including power circuit, signal conditioning circuit, data-storing circuit, serial interface circuit, display circuit and current loop circuit. Firstly, the optical signals filtered are converted to voltage signals through signal conditioning circuit, then the voltage signals are transferred to microcontroller. Secondly, actual temperature is computed by the microcontroller, shown by LED, and stored in flash. Thirdly, the temperature is converted to current signal, and transferred to PLC through current loop circuit. Thus, the temperature in flash can be read through serial interface circuit.4. The software system is designed. The system mainly contains initial model, parameters-reading model, temperature-computation model, storing model, LED-display model and keyboard-input model.