The migration induced by intensive light is termed photophoresis. We could show that the evaluation of light-induced
velocities of microparticles, bacteria and cells suspended in water is valuable for the prediction of their intrinsic
properties. Two different laser setups were evaluated for photophoretic migration, a He-Ne laser (<i>P</i> = 45 mW, λ = 633
nm) and a diode-pumped cw-Nd:YAG (<i>P</i> = 1.1 W, λ = 532 nm). When analyzing the migration behavior of particles, we
find significant differences depending on both, geometrical size and refractive index. We describe migration of PS
particles of different size as well as with different refractive index but same diameter, SiO<sub>2</sub> and melamine resin. The
potential for the separation of biological matter is shown as velocity distributions of heat killed bacteria of Escherichia
coli, Salmonella enteritidis, and baker's yeast is reported.