EFFECTS OF WIND ON THERMAL DEFOCUSING OF CO2 LASER RADIATION

A cw laser beam propagating in an absorbing medium may be spread, distorted, or deflected as a result of thermally self-induced refractive index gradients. In this paper the results of an experiment are reported where a wind, transverse to the direction of propagation of a CO2 laser beam, is imposed on an absorbing medium consisting of a mixture of air and propane. The experimental results show, in agreement with a simplified theoretical model, that the effect of the wind is (1) to deflect the laser beam into the wind for a certain range of wind velocities and (2) to reduce the thermal defocusing or blooming which results from the processes of thermal conduction and natural convection. © 1969 The American Institute of Physics.