Measuring Thermal Diffusivity of Mechanical and Optical Grades of Polycrystalline Diamond Using an AC Laser Calorimetry Method

Abstract

Because of its extremely high thermal conductivity, measuring the thermal conductivity or diffusivity of optical-grade diamond can be challenging. Various methods have been used to measure the thermal conductivity of thick diamond films. For the purposes of commercial quality control, the AC laser calorimetry method is appealing because it enables fairly rapid and convenient sample preparation and measurement. In this paper, the method is used to measure the thermal diffusivity of optical diamond. It is found that sample dimensions and measurement parameters are critical, and data analysis must be performed with great care. The results suggest that the method as it is applied to optical-grade diamond could be enhanced by a more powerful laser, higher frequency beam modulation, and post-processing based on 2D thermal simulation