AbstractThe newly developed dual‐cylindrical wave laser system is an alternative to the phase Doppler technique. It requires only frequency measurements for particle sizing and velocimetry, and hence prevents the difficulties associated with the phase measurements. This technique was evaluated experimentally using monosize liquid droplets of water and diethyl phthalate. The experimental results are compared with the theoretical predictions of the system response, based on geometrical optics and the electromagnetic theory of light, under certain simplifying assumptions. Although the measurements generally agree with the theory, some minor oscillations in the measured response are only roughly represented by the theory. Also, the experimental data indicate a large deviation from the theory if the particle is within a distance of three diameters from the origin of the cylindrical waves, hence defining the boundary of the region in which the theory is applicable. This work indicates that a properly laid out dual‐cylindrical wave laser system can be employed for sizing of small droplets in liquid spr