The phase-Doppler technique, allowing one to measure velocities and si
zes of individual spherical particles in moving flows, is a very popul
ar technique. Nevertheless, the bulkiness of the device and the need f
or accurate adjustments still impose restrictions in use in a large nu
mber of industrial situations. We present here a miniature phase-Doppl
er probe in which the emitting and collecting units are assembled in a
compact way. The performance of the device is numerically and experim
entally demonstrated.