Comparison of Data for Thermal Diffusivity Obtained by Laser‐Flash Method Using Thermocouple and Photodetector

Thermal diffusivities of cordierite glass and glass‐ceramics measured by the laser‐flash method using remote optical sensing to monitor the transient temperature of the specimen were higher than those obtained with a thermocouple. The latter data were thought to be lower because of thermal contact resistance, the heat capacity of the cement used to adhere the thermocouple, and heat loss along the thermocouple wire. It is concluded that remote optical sensing yields more reliable data.