Experimental results are reported that show the effects of the self-induced thermal lens due to a high power laser beam on imaging or tracking systems viewing along the same propagation path. The thermal distortion effects of a wind are simulated with a low power (≲ 3-W) CO2 laser beam propagating through a cell of liquid CS2 moving across the beam. The resulting image distortion includes a warping effect analogous to the deflection of the CO2 beam, together with a pronounced demagnification of the central portion of the object. An active optical tracker is simulated with a He-Ne laser beam propagating collinearly with the CO2 beam. The He-Ne beam pattern returned from a specular target is distorted and sharply confined to the outline of the crescent shaped CO2 beam. Simple ray optics models are used to provide qualitative explanations for the experimental results.
Frederick G. Gebhardt, "Self-Induced Thermal Distortion Effects on Target Image Quality," Appl. Opt. 11, 1419-1423 (1972)