1 Measurement method According to JJG22T80 standard optical pyrometer verification procedures, JJG11079 standard temperature lamp verification procedures, 2000 national large-scale legal metrology technical institutions 800 * C1700 * C temperature comparison rules, using the hospital has introduced its own effective wavelength standard The optical pyrometer (hereinafter referred to as pyrometer) is used as a standard, and the manual comparison of the direct comparison method makes the brightness of the pyrometer filament balance with the high stability vacuum tungsten lamp with a given current (hereinafter referred to as the high stability lamp). Wavelength correction, to the high steady lamp in the specified 660nm effective wavelength 700 * C temperature range around the temperature of the whole Baidu temperature given a given brightness current temperature is divided.
The measurement method implemented in the comparison is similar to the indexing of the standard temperature lamp by the pyrometer. The method for evaluating the uncertainty can be partially referred to the method for assessing the uncertainty of the temperature lamp of a pyrometer standard. The difference lies in the uncertainty of each standard. The difference in degree components and the introduction of the effective wavelength standard uncertainty component. In addition, the performance indicators and structures of high-stable lamps are virtually the same as the working reference temperature lamps. Therefore, the uncertainty component of measurement results caused by the lampholder temperature, ambient temperature, and index repeatability should be selected separately or obtained by experiments alone. .
2 Mathematical model According to the luminance temperature corresponding to the average value of the filament current when the luminance of the pyrometer is balanced, the brightness temperature rate of the high steady lamp near the given current is determined.
The difference between the average current and current average value of the high-stable lamp corresponds to the brightness temperature difference, and the brightness temperature and the average measured current of the high-stable lamp under the high-stable lamp given current are calculated; the current given by the high-stable lamp ratio rule is calculated. Value; dig / dtg - high steady light at t at the current temperature change rate.
The half-width of the difference is a half-width evenly distributed between a and A1. The two standard uncertainties are Ua, =a1p3, UA, =A1/P3, reliability is 90%, and the degrees of freedom are Va = 50,50. The transfer formula of uncertainty can be obtained: degree of freedom V1 = Vff1 Calculated by Va and V according to the Welter Satterthwaitt formula: Pyrometer readings are visually balanced by the human eye.
Many factors such as human eye spectral resolution, balanced field of view and non-isotropic properties, optical system differences, and subjectivity of reading all contribute to the error in brightness balance. According to the statistical analysis of a large number of experimental data by China Institute of Metrology, the temperature balance error tL (three times the standard deviation of the mean value) is obtained for each temperature point. The uncertainty of measurement U3=At:/3 introduced by the eye-eye balance error is taken as a normal distribution, and the reliability is 75%, V=8, c3=1; (This component is only for analysis, and the actual operation has been Included in the repetitive component, in order to avoid repetition, the U3 is not introduced during the synthesis.) The stability of the pyrometer bulb is measured by the power method. The first amount of 700*C is At, respectively. = 6 * C. Take the normal distribution, then U4 = At, | 3, the reliability of the pyrometer temperature changes caused by changes in the temperature of the temperature change rate C5 = Cb ring = 5t 丨 | 5t ring measured by the experiment. (C5 and C8 are in the same direction. Because C8 is very small, C5 is still used here and it is not processed according to the synthetic temperature coefficient). According to the requirements of the regulations, the ambient temperature is 20°C*2*C, the actual temperature is 20°C*0.5*C, the trapezoidal distribution is taken, B=071, then U5=0.5|2, the reliability is 70%, and V=6 The measurement uncertainty caused by the influence of the pyrometer power supply is mainly composed of two items: the temperature of the entire pyrometer of the pyrometer and the rate of change of the temperature current of the pyrometer is C6 = 丨| 5ib, which is calculated from the verification certificate. Uniform distribution, then U6 = 00005 "| (2 million). ib for each temperature point pyrometer measured current value, reliability is 75%, V = 8. 0.1%, resulting in pyrometer light-temperature current changes On the order of 10-7, the corresponding brightness temperature is about a few hundredths of a degree and is ignored.
5.2 High-stable lamp related standard uncertainties The uncertainty of the current caused by the component electrical measuring instrument U2.2 High-stable lamp current is measured indirectly using the Type 7081 digital voltmeter and the BZ6 standard resistor. The maximum allowable error of the digital voltmeter is the range of the maximum allowable error. The range of the x (1V range) difference half-width is =A2A/3, and the reliability is 50. According to the uncertainty transfer formula, the Wetter formula is calculated and obtained. .
The three-point quasi-bias J of each point of the process contributes to the brightness temperature of the electric power of the two ambiguous ambiguities and the high enthalpy s, and the uncertainty of the brightness and temperature of the high-steady lamp caused by the two items can be transferred by the uncertainty. Obtain: The degree of freedom M2 is calculated by Mi and M22 according to the Welch-Satterthwaite formula: The change rate of the high-stable lamp base temperature t seat changes the brightness temperature, resulting in a change rate of C7=cgs=5tg/5t. According to the data from the China Academy of Metrology, the temperature control range of the high-stable lamp base is: 20*C*0.5*C, which is evenly distributed, u7=0.5/3, and the reliability is the brightness of the high-stable lamp caused by ambient temperature changes. The change rate of temperature change C8=Cg ring=5tg/5t ring is given by the China Institute of Metrology. The temperature control range of high-stable lamp is: 20*C*2*C. The actual control temperature in this hospital is 20 trapezoidal distribution. , B = high-stable lamp power supply measurement uncertainty caused by the main consists of two: 02%, high-stable lamp brightness temperature current change rate c9 = 5tg/5ig obtained by the experiment.
Uniform distribution, u9=0 0002ig/(20,000), ig is the current value measured at each temperature point of the high-stable lamp, the reliability is 75%, and M=8.1%, that is, non-sinusoidal periodic ripple current fundamental wave and direct current The component amplitude ratio is less than 0 1%, and higher harmonics are ignored here. According to the calculation, under this condition, the change of the brightness temperature of the high-stable lamp caused by this AC component is in the order of 10-6, and the corresponding brightness temperature change is about several hundredths of a degree, which can be ignored.
The repeatability of the measurement result caused by repeatability of 5-3 is repeated 10 times under the same conditions. The Bessel formula calculates the single experiment standard deviation s10, M0=n-1=9, C10=1; The average value of the three experiments indicates that the uncertainty component caused by the resolution of the average digital voltmeter is ignored due to its small contribution. The above mentioned standard uncertainty components are not related to each other.
6 Evaluation results The evaluation results are shown in Table 1. Table 1 High Stability Lamps 800°C to 1700°C Range Uncertainty Evaluation Results Temperature TC 7 Conclusion The above uncertainty evaluation method is applicable to the use of a pyrometer and its own effective wavelength (including average Effective wavelength and limit effective wavelength) Measure blackbody radiation source temperature and brightness temperature of other non-black body objects. It can also measure the standard temperature lamp and high stable lamp brightness temperature at a specified effective wavelength. This method does not apply when the effective wavelength of the pyrometer is taken from the reference photoelectric high temperature comparator and is used only for standard temperature lamps with the same effective wavelength division.
JJG22780, standard optical pyrometer verification procedures.
JJG1179, Standard Temperature Lamp Verification Procedures.
Cui Zhishang, et al. Commonly used radiation temperature measuring instruments and their verification. Beijing: China Measurement Press, 1986, JJF105-1999, Evaluation and Expression of Measurement Uncertainty.
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