测温仪低温段的温度分辨力和测温灵敏度及对测温精度的影响

简要介绍了一种利用半导体发光器件作辅助测量光源、以InGaAs光电二极管作光电转换器件实现的发射率和温度测量仪（工作波长1．5μm、测温范围400℃至1100℃），着重讨论了该仪器低温段的温度分辨力受被测温度、波长带宽、A／D转换电路的设计、探测器的灵敏元尺寸以及测温灵敏度等的影响。得到如下结论：（1）温度越低，则温度分辨力就越低、进而仪器的测温精度也越低。因此只要400℃时的温度分辨力符合要求，则测温范围内的其它测温点都符合要求；（2）波长带宽越窄，则仪器的温度分辨力越低、相应的测温精度也就越低。反之，则越高。但波长带宽越宽，则进入探测器的干扰光就越多，从而导致其测温精度也不高。综合考虑这些因素后，仪器选择△λ=20nm作为其工作波长的带宽。采用优化设计的仪器参数、尤其是采用高探测率的InGaAs光电二极管作探测器后，在整个测温范围内的测温精度都不低于0．2％，符合设计要求。

Study on temperature resolution power and measurement sensitivity at lower temperatures and its effect on measurement accuracy

Based on the Kirchhoff law, a practical real - time emissivity and temperature measurement instrument has been developed. This instrument uses an InGaAs photodiode as the detector and uses a laser diode as the light source. Its working wavelength and temperature measurement range are of 1.5μm and 400 -1100 ℃, respectively. The effects on the temperature resolution power by the temperature, bandwidth, A/D converter, sensitive area of the detector and temperature sensitivity are discussed at lower temperatures. Two conclusions are drawn. Firstly, the lower the temperature, the worse the temperature resolution power is. Thus, the temperature resolution power must fall into the specifications as long as it is in accordance with the requirements at 400℃. And secondly, the narrower the wavelength bandwidth, the lower the temperature resolution power, and the worse the temperature measurement accuracy is. But the accuracy is also low when the wavelength bandwidth is too wide due to the surrounding radiation. Taking into consideration these factors, the instrument chooses △λ = 20 nm as its wavelength bandwidth. Experimental results show that the temperature measurement accuracy is superior to 0.2% after taking the optimized parameters and the InGaAs photodiode as the detector.