Radiation heat transfer in tissue welding and soldering with ultrafast lasers

We develop the discrete ordinate method to incorporate transient radiation heat transfer in tissue welding and soldering with the use of ultrafast lasers. The tissue is assumed to be an axially symmetric cylinder. The temporal distribution of radiative energy inside the tissue as well as the radiative heat flux along the tissue surface is obtained. Comparisons are performed between laser welding and laser soldering. The use of solder is found to substantially enhance the radiation energy absorption in the solder-stained tissue region, but reduce the surface radiative heat flux.