We present here a complex experimental study of the optical quality and the strength to laser radiation of alkali-halide crystals (AHC) thermomechanically strengthened using different working modes. We have revealed in this study the change of deformation mechanism, according to the schemes {110}→{110} and {100}<110>→{100}<110> that occurs at an increased deformation degree, from 5 to 60%, at temperatures from 200 to 400°C. It is shown that formation of a coarse-grained re-crystallization structure at the deformation degree above 25-40% leads to an enhanced absorption at 10.6 mm wavelength and weakens the AHC strength to laser radiation.