The laser calorimetry (LCA) technique is used to determine simultaneously the absorptances and thermal diffusivities of optical components. An accurate temperature model, in which both the finite thermal conductivity and the finite sample size are taken into account, is employed to fit the experimental temperature data measured with an LCA apparatus for a precise determination of the absorptance and thermal diffusivity via a multiparameter fitting procedure. The uniqueness issue of the multiparameter fitting is discussed in detail. Experimentally, highly reflective (HR) samples prepared with electron-beam evaporation on different substrates (BK7, fused silica, and Ge) are measured with LCA. For the HR-coated sample on a fused silica substrate, the absorptance is determined to be 15.4 ppm, which is close to the value of 17.6 ppm, determined with a simplified temperature model recommended in the international standard ISO11551. The thermal diffusivity is simultaneously determined via multiparameter fitting to be approximately 6.63 x 10(-7) m(2) center dot s(-1) with a corresponding square variance of 4.8 x 10(-4). The fitted thermal diffusivity is in reasonably good agreement with the literature value (7.5 x 10(-7) m(2) center dot s (-1)). Good agreement is also obtained for samples with BK7 and Ge substrates.
Chinese Acad Sci, Inst Opt & Elect, Chengdu 610209, Sichuan, Peoples R China
Recommended Citation:
Wang, Yanru,Li, Bincheng. Simultaneous Absorptance and Thermal-Diffusivity Determination of Optical Components with Laser Calorimetry Technique[J]. INTERNATIONAL JOURNAL OF THERMOPHYSICS,2012,33(10-11):2069-2075.
