PURPOSE: To determine the temperature of a particle or the effect thereof at the time of measuring the size of an atomized liquid particle by measuring the phase shift of a scattering beam from a primary beam simultaneously at a scattering angle where the phase shift depends only on the particle size and at another scattering angle where the phase shift depends on the particle size and the refractive index and then deriving the density and the temperature of the particle from the particle size and the refractive index thus determined.

CONSTITUTION: A light from a laser light source 1 is polarized and two coherent exciting beams 2, 3 are crossed in an atomized measuring space 4 and then a scattering beam generated in the measuring space 4 is measured simultaneously at different scattering angles 1, 2 by means of a measuring unit 5. The measuring unit 5 has two detection systems 6, 6' and one detection system 6 is directed toward a forward scattering beam in the range of 70° while the other detection system 6' is directed toward a forward scattering beam in the range of 30°. The detection systems 6, 6' generate signals proportional to the phase shift simultaneously at respective scattering angles 1, 2 and these signals are introduced to an evaluation unit 7 where the density and the temperature of atomized droplet are calculated.