All-optical beam deflection method for simultaneous thermal conductivity and thermo-optic coefficient (dn/dT) measurements

作者：Putnam Shawn A^*; Fairchild Steven B; Arends Armando A; Urbas Augustine M

来源：Journal of Applied Physics, 2016, 119(17): 173102.

DOI：10.1063/1.4948429

This work describes an all-optical beam deflection method to simultaneously measure the thermal conductivity (Lambda) and thermo-optic coefficient (dn/dT) of materials that are absorbing at lambda = 10.6 mu m and are transparent to semi-transparent at lambda = 632.8 nm. The technique is based on the principle of measuring the beam deflection of a probe beam (632.8 nm) in the frequency-domain due to a spatially and temporally varying index gradient that is thermally induced by 50: 50 split pump beam from a CO2 laser (10.6 mu m). The technique and analysis methods are validated with measurements of 10 different optical materials having K and dn/dT properties ranging between 0.7W/m K <= K <= 33.5W/m K and -12 x 10(-6) K-1 less than or similar to dn/dT less than or similar to 14 x 10(-6) K-1, respectively. The described beam deflection technique is highly related to other well-established, all-optical materials characterization methods, namely, thermal lensing and photothermal deflection spectroscopy. Likewise, due to its all-optical, pump-probe nature, it is applicable to materials characterization in extreme environments with minimal errors due to black-body radiation. In addition, the measurement principle can be extended over a broad range of electromagnetic wavelengths (e.g., ultraviolet to THz) provided the required sources, detectors, and focusing elements are available. Published by AIP Publishing.

• 出版日期2016-5-7