Theoretical evaluation of radiation pressure magnitudes and effects in laser material processing

Laser beam radiation and particularly its effects on irradiated materials are commonly specified in terms of intensity. However, laser beam radiation is also a carrier of considerable momentum as a result of high photon flow rates which give rise to a pressure acting at the surface of irradiated probes. Both characteristics, i.e. intensity and radiation pressure are directly related, and resultant effects cannot be easily distinguished from each other under real processing conditions. The current analysis presents theoretical estimations of the different pressure levels that are supposed to be involved in interactions with target surfaces in continuous wave and pulsed-wave laser applications. The results demonstrate that neglecting the radiation pressure seems not to be justified for an appropriate physical characterization and/or interpretation of effects in a number of established laser applications. It is concluded that there is a need to evaluate more profoundly the role of radiation pressure by appropriate experimental and theoretical studies.