Study On The High-temperature Sensing Technology Based On The White Light Polarimetric Differential Interferometric Technology

Temperature is an important parameter in the industry process. Real-time and accurate temperature measurement is very important to ensure the operation safty and efficiency. With the fast development of world economy, there are sustainable increasing needs of high temperature sensors in harsh environment, such as high temperature, high pressure, chemical corrosion, toxicity, strong electromagnetic interference, and high-energy radiation exposure. To meet the requirement for high-temperature measurement in harsh environment such as coal gasifier, a high-temperature optical fiber sensing system based on the white light polarimetric differential interferometric technology is proposed and developed using single crystal sapphire material.Firstly, this dissertation gives a brief intrudoction the sapphire crystal, and the principle of temperature measurement using the sapphire crystal is proposed and simulated. The principles of the white light interferometry, and algorithms such as peak to peak method, FFT method and Fourier transform white-light interferometry method were comparatively studied. Fourier transform white-light interferometry was adopted as the data processing algorithm.Secondly, a high temperature sensing system was designed to meet the needs of temperature measurement in real application. Most efforts were focused on the optical and mechanical structure of the sensing probe. Instrumentational designing of the high temperature sensing system were carried on. The TMS320VC33 floating-point DSP chip was used to realize the communication between signal processing board and spectrometer, and it also serves as the CPU to implement data-processing programs. Finally, experiments were carried out to demonstrate the feasibility of our system.Experimental results showed that the sensing system has very good accuracy in the range of 0 ~ 700℃. Limited by our experiemtal equipment, the high temperature tolerance was not fully tested. As sapphire crystal itself can withstand 1800℃temperature, it is reasonable to expect our white light interferometric sensing system has the ability to operate in harsh environment with high temperature to 1500℃, high pressure, and chemical corrosion.The study of principle, structure design and instrumentational in this dissertation is a basis of white light interferometric high temperature sensing for real world application, and it could serve as a good guide and reference in future work.