Abstract
A laser pumped-thermal lens system as a tool for the measurement of liquid samples was constructed. The clear distinction of three different liquids at the stationary state was demonstrated. An example of the time-course feature at the transient state of diffusion when an impurity droplet was dropped into water was traced, exhibiting a time of about 5 s to the end of diffusion. The intensity of thermal lens signal versus the mixing rate of liquid samples in water at the steady state was measured with good reproducibility.