The absorptance and high reflectance measurements of laser optics are presented. In the absorptance measurement, the laser calorimetry (LC) technique is investigated. A rigorous theoretical model describing the laser irradiation induced temperature rise in a coated sample, in which both the finite thermal conductivity and the finite size of sample are taken into account, is developed to optimize the temperature detection geometry to further improve the accuracy of the absorptance measurement. For the high reflectivity measurement, an optical feedback cavity ring-down (OF-CRD) technique, in which a continuous-wave (CW) Fabry-Perot (FP) diode laser is used as the light source, is employed for high reflectivity measurement. The linear and V-shaped schemes are investigated to measure the reflectivity of cavity mirrors and planar test mirrors, respectively. For cavity mirrors with reflectance larger than 99.99%, the measurement error is less than 1ppm.© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.