Optothermal properties of a converter of laser radiation to the radiation of a high-temperature point source

Laser radiation sources of different wavelengths with a silica fiber output are widely used in engineering (surface clearing and scratching/engraving, and so on) and in medicine (effective low-invasive scalpels for treating various diseases). These applications are based primarily on direct exposure of the object to laser radiation. The properties of a converter of such a laser radiation to the radiation of a point (similar to 0.5 . 0.5 mm), high-temperature (similar to 2000 K) source with strongly absorbing coating (SAC) at the distal end of the silica fiber are considered in the presented work. The use of a converter expands the capabilities of laser instruments significantly. The temperature (similar to 2000 K) of the operating silica fiber tip with SAC at a laser pump power of 3-10 W (lambda = 1.47 mu m) and its time dependence in air atmosphere, in CO2 gas and in vacuum have been studied in experiment. The results of the studies and the physical properties of heat transfer and material stability in the converter design are considered. Recommendations on converter application as a scalpel with SAC for cutting soft and hard biological tissues are formulated.