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Pulsed C02 laser damage mechanism of plexiglass (polymethilmethacrylate, PMMA) is controlled by in-depth absorption of the 10.6 mm radiation. The interaction area heating gives rise to thermal or thermal-mechanical damage processes and to generation of Wave of Reflection and Conduction (WRC) . WRC consist of many pulses following each another and differing by velocity about factor of two. He-Ne laser monitoring beam showed the modulation of interaction area reflection by slow components of WRC traveling between front and rear sample surface with velocities - 4.2 and -2,1 cm/s. An IR camera Thermovision 1000 fixed modulations of the temperature and the image of interaction area on the opposite surface of different thickness samples. This modulations correspond to influence of the WRC components with velocities - 0.2; - 0.05; - 0.025 cm/s. This low WRC velocities do not depend in plexiglass upon laser pulse energy in the range 1,10 J/cm2. Relation of WRC to damage process is under study. This work was sponsored by DRET (France) and RFBR (Russie) . Keywords: reflection and conduction wave, slow components of, plexiglass, C02 laser, damage testing.
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