Study Of Colorimetric Optical Fiber High-Temperature Measurement Based DSP

Since transferring and sensor technology of optical fiber has some advantages in practice, such as anti-electromagnetic interference, no space transmission and so all, radiation temperature measurement technology based on optical fiber is developed rapidly. In recent years, brightness optical fiber pyrometer is widely applied. However, in some circumstances there are measurement errors caused by variation of obiect emissivity, dust, vapour, and losing accuracy of detector. A system is constructed in this paper to diminish the problems above in order to enhance temperature-measuring accuracy.Optical fiber high-temperature measurement system based DSP is studied. In view of high-temperture measurement problem under special environment, and according to the principle of blackbody radiation, and by using"touchable-untouchable"measurement technology and using colorimetry as measurement method, the effect of emissivity and environment on the results of measurement is decreased and inhabited.Firstly, the blackbody cavity probe is designed. Many kinds of factor affecting the effective emissivity of blackbody cavity are researched in detail, such as temperature distribution, geometric characteristics of sensor, material emissivity, environment temperature and so all. Optimum parameters of blackbody emissivity are obtained to improve the temperature-measuring accuracy. Secondly, the structure and property of colorimetric temperature measurement are investigated in detail. Lens collimator is used to make signal light couple to optical fiber effectively. By analyzing, optimum wavelength and bandwidth are choosed, and wavelength division multiplexer is used as filter, and the narrow band filtering characteristics of optical fiber grating makes effect of background light decrease. According to the spectral response of detector, silicon photocell is used as photoelectric converter. Finally, a kind of signal processing method using DSP to store and process mass data is disscussed. The hardware and software are designed, and mathematical model of temperature measurement is obtained.By experiment, curve of R(T)-T is drawed and fitted sectionally. Good results are obtained and the accuracy requirements are satisfied. This high-temperature measurement system is characterized by high precision and anti-electromagnetic disturbance and it will be applicated very well in the future.