The Approach of Compensation of Air Refractive Index in Thermal Expansion Coefficients Measurement Based on Laser Feedback Interferometry
ZHENG Fa-Song1, DING Ying-Chun1**, TAN Yi-Dong2, LIN Jing1, ZHANG Shu-Lian2**
1Department of Physics, College of Science Beijing University of Chemical Technology, Beijing 100029 2The State Key Lab of Precision Measurement Technology and Instrument, Department of Precision Instruments, Tsinghua University, Beijing 100084
Abstract：We present the thermal expansion coefficient (TEC) measurement technology of compensating for the effect of variations in the refractive index based on a Nd:YAG laser feedback system, the beam frequency is shifted by a pair of acousto-optic modulators and then the heterodyne phase measurement technique is used. The sample measured is placed in a muffle furnace with two coaxial holes opened on the opposite furnace walls. The measurement beams hit perpendicularly and coaxially on each surface of the sample. The reference beams hit on the reference mirror and the high-reflectivity mirror, respectively. By the heterodyne configuration and computing, the influences of the vibration, distortion of the sample supporter and the effect of variations in the refractive index are measured and largely minimized. For validation, the TECs of aluminum samples are determined in the temperature range of 298–748 K, confirming not only the precision within 5×10?7 K?1 and the accuracy within 0.4% from 298 K to 448 K but also the high sensitivity non-contact measurement of the lower reflectivity surface induced by the sample oxidization from 448 K to 748 K.
. [J]. 中国物理快报, 2015, 32(07): 70702-070702.
ZHENG Fa-Song, DING Ying-Chun, TAN Yi-Dong, LIN Jing, ZHANG Shu-Lian. The Approach of Compensation of Air Refractive Index in Thermal Expansion Coefficients Measurement Based on Laser Feedback Interferometry. Chin. Phys. Lett., 2015, 32(07): 70702-070702.
2015, Vol. 32 
