Self-defocusing of He–Ne laser radiation as a result of thermoelastic deformations of a reflecting surface

Theoretical and experimental investigations were made of the efficiency of self-defocusing of cw He–Ne laser radiation as a result of thermoelastic deformation of a specularly reflecting surface of a strongly absorbing material. The divergence of a focused single-mode beam of ~20 mW power after reflection from a deformed ebonite surface was thirty times higher than the diffraction limit.