Accurate values for the thermal expansion coefficient α and the thermal coefficient of refractive index

are important in the design of a solid-state laser. This paper presents values of α and

that were measured for Nd:YAG and Nd:YALO by a single-exposure holographic interferometry technique. The value of α for Nd:YAG agrees closely with that reported before, yet significantly different values of

for Nd:YAG and α for Nd: YALO were obtained. A discussion of the measurement techniques is given.