Particle discriminator and method

A method of distinguishing and characterizing at least two distinct types of particles which have different depolarizing structures, said method comprising,

• directing a suspension of particles containing the distinct particle types through an optical sensing zone,
• illuminating the particles in the zone with an incident beam of linearly polarized light,
• by said illuminating, producing from each of the distinct types of particles, depolarized scattered light whose intensity, at a selected scattering angle, is dependent on the particle's depolarizing structure, and is within an intensity distribution range which is (a) characteristic of one of the particle types and (b) substantially non-overlapping with the intensity distribution of the other particle types in the suspension, in a particle-feature space which is defined in one dimension by depolarized light scattering intensity measured at the selected angle,
• measuring the intensity of the depolarized scattered light from each particle at the selected angle, and
• based on the intensity of the measured scattered light in the particle-feature space, distinguishing and characterizing at least two distinct particle types in the suspension.