Non-linear optical electrohydrodynamic effect (OEHD-effect) in liquid dielectric

Laser beams are often used in the research of electrodynamic and prebreakdown processes in liquid dielectrics. Nonlinear optical effects, caused by heating of a liquid, can appear even when a laser beam of a relatively small power 5-10 mW passes through a medium. Certain nonhomogeneous temperature distributions and consequently refraction coefficient distributions can be observed in the region through which a laser beam passes, The above-mentioned region produces a defocusing influence on a liquid. Thus, for example, when a helium-neon laser (power 10 mW) passes through a 10 cm layer of transformer oil, the angle of defocusing reaches 10/sup -3/ rad.