Temperature measurement is required for many applications but can be difficult in some cases. Laser heating or cooling studies demand accurate measurements of temperature changes. A Michelson interferometer configuration has been used to investigate laser heating in solids. An analytical formula was derived to estimate the temperature change from the fringe count by taking into account the temperature dependence of the sample length and refractive index. When $115\mathrm{mW}$ of a focused ${\mathrm{Ar}}^{+}$ laser beam ( $488\mathrm{nm}$ ) passes through a ${\mathrm{Pr}}^{3+}$ -doped YAG sample, its temperature increased by $11.7\pm 1.0\mathrm{K}$ along the beam path due to nonradiative relaxation. The power dependence of the fringe count/movement was recorded. The temperature change was estimated by the interferometric method and is in agreement with that measured by a thermocouple.