| Temperature is an important parameter in the production process,and it is often used as an important characterization parameter to monitor production safety status and evaluate product quality in aerospace,metal smelting,industrial production and other fields.The multi-wavelength radiation temperature measurement method is a non-contact temperature measurement method.By measuring the spectral intensity of the target,and combining it with a certain assumed emissivity model,the temperature and emissivity of the target are calculated.In this paper,a multi-wavelength pyrometer is constructed by the spectrometer,and based on the assumed relationship between the emissivity and temperature,a multi-wavelength temperature measurement algorithm is proposed,which can realize the simultaneous measurement of target temperature and emissivity.The specific research work is as follows:(1)The multi-wavelength pyrometer is constructed based on the optical fiber spectrometer,and the mathematical model of the multi-wavelength pyrometer temperature measurement is established.The instrument coefficient is calibrated based on the blackbody furnace,and the calibration uncertainty is analyzed at last.The experimental results show that the temperature measurement range of the pyrometer can reach 800～1200℃.For all channels,the square root of the calibration uncertainty of the instrument constant K is0.031%,and the square root of the uncertainty of the offset B is 7.6%.(2)In order to quantitatively evaluate the influence of the internal noise of the pyrometer on temperature measurement,a noise model of the pyrometer is established,and the distribution rules of readout noise,photoelectronic noise and dark noise are quantitatively analyzed through experiments.On this basis,the influence of these noises on temperature measurement is quantitatively evaluated.The experimental results show that when the exposure time is set to 9ms,the temperature measurement range is 800～1200℃,and the wavelength range is 780～1030nm,the mean relative measurement deviations of temperature caused by readout noise,photoelectronic noise,and dark noise are 0.24%,0.35%,and 0.03%,respectively.(3)In order to accurately measure the real temperature and spectral emissivity of the target,the "secondary measurement" multi-wavelength temperature measurement algorithm is established,and the particle swarm optimization algorithm is introduced to solve the undetermined coefficients in the multi-wavelength temperature measurement algorithm,to realize the simultaneous measurement of the emissivity and temperature of the target.The feasibility of the proposed algorithm is verified by numerical simulation experiments.The experimental results show that the maximum error of temperature estimation is 1.04%under the assumption of the linear emittance model and 0.46% under the assumption of the nonlinear emittance model when the relationship between emissivity change and temperature change is unknown. |
