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| Calibration on Measurement System for the Refractive Index of Air Based on Edlén Formula |
| CUI Jian-jun1,2, LIU Xiang-bin2, KANG Yan-hui2, ZHANG Heng2, LI Jian-shuang1,2 |
1.State Key Laboratory of Precision Measuring Technology & Instruments,Tianjin University,Tianjin 300072, China;
2.National Institute of Metrology, Beijing 100013, China |
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Abstract To verify the performance of refractive index of air measurement system, which has a great influence for accuracy of laser interferometer, one kind of calibration approach is presented for the refractive index of air measurement system of laser interferometer. One special calibration setup is designed which consists of temperature, air pressure and humidity sensors and it is based on Edlén formula to measure the refractive index of air indirectly.Experiment shows that the temperature uncertainty is less than 0.02 ℃ in (5~40)℃, uncertainty of air pressure is 18 Pa in (60~110) kPa and uncertainty of air humidity is 2.0% RH in (10~90) %RH. The relative expend uncertainty of whole system for refractive index of air is 1×10-7, where cover factor k=2.
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2014, Vol. 35 
