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Study of the Technique of Multi-spectral Radiation Thermometry

Author: DaiJingMin
Tutor: QiangXiFu；ZuoZaiXiang
School: Harbin Institute of Technology
Course: Precision instruments and machinery
Keywords: multispectral thermometry radiation thermometer high temperature measurement one point calibration emissivity blackbody Monte-Carlo method
CLC: TH811.2
Type: PhD thesis
Year: 1995
Downloads: 1078
Quote: 23
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Abstract

The multispectral (multiwavelength) radiation thermometry, which can be used to measure the true temperature and spectral emissivity simultaneously, has been developed since the seventies this century. Meanwhile, the multiwavelength pyrometer is also an important instrument for dynamic measurement of multi — parameters of thermophysical properties such as emissivity, melting point, heat capacity, thermal expansion etc. The temperature and emissivity measurement of the ablative and composite high temperature materials is an urgent need along with the vigorous development of the Aerospace and Aviation Industries as well as the technology advances. And the multiwavelength pyrometer MWP is just a powerful tool for solving the above — mentioned problems.Although many advanced countries such as the United States of America and the Commission of European Communities (CEC) have developed the six — wavelengths pyrometers, the systematic research should still be performed in this field. Some important topics including the multispectral theory, multiwavelength pyrometer design and manufacturing and calibration method research are still the new challenges before us.According to the practical demands of the Aerospace Ministry and International Scientific Cooperation Agreement with Roma University, the dissertation brings forth the new ideas and work in the field of multispectral radiation thermometry as follows.1.Develop the brand — new 35 channels multiwavelength pyrometer with prisms for beam split instead of interference filters. The six — wavelengths pyrometers with six interference filters for effective wavelength defined and with optical fibers for beam split were developed by the U.S. and CEC scientists inl980’s. This kind of MWP has some disadvantages such as great energy flux loss passing the optical system, unsatisfactory stability due tothe use of interference filters and less flexibility for six wavelengths selected. A new kind 35 channels pyrometer has been developed for improving the MWP performances. The composite prism is used without aging for increasing the signal - to - noise ratio and restraining the effects of temperature and humidity variations with Chinese characteristics.2. The Monte — Carlo method has been proposed for estimating the errors of the "One Point Calibration"based’ on the measurement of pyrometer wavelength function (PWF). The typical results have been obtained for spread and practical applications of this advanced calibration technique.3. The multispectral radiation thermometry has been studied systematically. Meanwhile, the mathematical model used between emissivity and wavelength was checked for proving the limitation of the model. Furthermore, an automatic recognition and selection method is presented according to the calculation and analysis from a large amount of the experimental results.4. Design and set up the first computer controlled equipment in China for pyrometer wavelength function measurement of all kinds of radiation thermometer. It is also the necessary of the "One Point Calibration".5. Develop the practicality fixed point blackbody furnace which is the first set in our country including Cu> Al and Zn points for narrow —band and/or multiwavelength pyrometer calibration. The device can also be used for ITS — 90 temperature realization and transferring as well as the standard source for photometry and radiometry.6. Design and manufacture an apparatus for dynamic performance measurement of MWP. The dynamic response and static specifications of the MWP have been precisely measured using the device at the laboratory of the Rome University.7. The MWP has been put into practical use for measuring the true temperature and spectral emissivity of the ablative materials for the Fourth Institute of the Aerospace Ministry. The system has operated stably since 1993. The outstanding results have been obtained for contribution of establishment of the military standard "Ablative Standard of Metrology".

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