Abstract The thermal expansion measurements with NIM’s precision interferometer are described.The measurements are based on the observation of the length change of the material samples as a function of a temperature using laser interferometry. The interferometer and the material sample up to 1m are situated in a tight enclosure which temperature is controlled by a water circulation within a temperature range from 5 ℃ to 40 ℃.A heat-balanced interference mirror was designed.A high precision temperature measuring system is used for measuring the temperature of the material sample and the air.The accurate determination of the refractive index of air and the real-time compensation of zero error are accomplished. Using an 500 mm gauge block, thermal expansion coefficient is measured with a relative deviation of less than 0.2%, and it was compared with those of Physikalisch-Technische Bundesanstalt (PTB) of Germany. The coefficient of thermal expansion can be obtained with a uncertainty less than 3×10-8K-1.
［1］Naofumi Y, et al. Final report on the thermal expansion coefficient of gauge blocks(APMP.L-S1)［J］.Metrologia, 2008, 45(1A):04001.
［2］Suska J, Tschirnich J. An interferometric device for precise thermal expansion measurements on bar-shaped materials［J］.Meas Sci Technol, 1999, 10: N55-N59.
［3］Schodel R.Ultra high accuracy thermal expansion measur-ements with PTB’s Precision Interferometer［J］.Meas Sci Technol, 2008, 19(8):23-34.
［4］Hughes E B. Measurement of the linear thermal expansion coefficient of gauge blocks by interferometry［J］.Proc SPIE, 1993, 2088:179-189.
［5］Watanabe H, Yamada N, Okaji M. Linear Thermal Expansion Coefficient of Silicon from 293 to 1000K［J］.International Journal of Thermophysics, 2004, 25(1):221-236.
［6］Okaji M, Yamada N, Moriyama H.Ultra-precise thermal expansion measurements of ceramic and steel gauge blocks with an interferometric dilatometer［J］.Metrologia, 2000, 37:165-171.〗
［7］GB/T 4339—2008. 金属材料热膨胀特征参数的测定［S］.
［8］叶孝佑,甘晓川,等.提高环境参量法测量空气折射率精度的研究［J］.计量学报, 2008, 29(4A):69-73.
［9］Edlén B. The refractive index of air［J］. Metrologia
, 1966, 2(2): 71-80.
［10］Birch K P, Downs M J. An Updated Edlen Equation for the Refractive Index of Air［J］.Metrologia,1993, 30:155-162.
［11］Birch K P, Downs M J. Correction to the updated Edlén equation for the refractive index of air［J］.Metrologia,1994, 31:315-316.
［12］Phillip E.Ciddor.Refractive index of air: new equations for the visible and near infrared［J］.Appl Optics,1996, 35:1566-1573.
［13］李东光,张国雄,曲军.高精度激光干涉测量中环境误差因素的综合补偿［J］.光电工程,1999, 26(4):28-33.
［14］张旭东,刘香斌,等.基于热电偶的温度测量系统的不确定度［J］.计量学报, 2006, 27(3A):157-159.
［15］Hamid R,Sendogdu D,Erdogan C.The temperature stabilization and temperature measurement of a Ksters interferometer［J］.Meas Sci Technol,2005, 16: 2201-2207.
2012, Vol. 33 
