Measurement of Biaxial Displacement by a Speckle Correlation Method at High Temperature

Biaxial displacement of a buttonhead tensile‐torsional specimen surface was measured by a speckle correlation method at 800°C. A high‐power argon gas laser of 488 nm wavelength and band‐pass filters were used to improve the signal/noise ratio at high temperature. In the case of displacement parallel to a specimen axis, calculated values by the speckle correlation agreed with the displacement measured with a dial gauge. For the perpendicular direction, agreement was also obtained, taking into account an additional correction. These biaxial displacements were measured in real time.