Measurement of thermal diffusivity of glasses using light interference
Hyeon Hwangbo and Sok Won Kim
Information about the thermophysical properties of materials is important in manufacturing and processing. Thermal diffusivity is one of the most important values and is widely applied in industry and basic research. In this study, the thermal diffusivities of transparent solids were measured using a two-beam interference method from room temperature to 358 K. When a laser beam is reflected at the front and rear surfaces, a pattern is generated by the interference of the reflected beams. A thermal wave is then applied by a heater, and the intensity of the pattern changes. The thermal diffusivity can be obtained using the time when the intensity change occurs. The experimental results at room temperature for BK7 optical glass, Pyrex, and quartz were 5.32×10-7 m2s-1, 6.39×10-7 m2s-1, and 7.33×10-7 m2s-1, respectively. These results agree with the literature values within 8.16 %. The optical glass (BK7) has a smaller thermal diffusivity than the heat-resistant glasses (Pyrex and quartz). In addition, the thermal diffusivity of each sample significantly increased as the temperature increased.
Keywords: Light interference, Thermal diffusivity, Thermophysical property