The analytical solution of transient temperature distribution and Tresca failure stress in cw-end-pumped laser rod has been derived using integral transform method. The analytical result is compared with numerical solutions presented by other works and good agreement has been found. Analytical solution with its clear physical meaning and its explicit form permits to predict the influence of various factors on the solution. The optical path difference which gives a valuable means to quantify the optical properties of laser material such as designed beam quality, will converge to a constant value as steady-state temperature distribution is reached. One can obtain the dominate factors which affect the laser response to bring the laser rod to the thermal equilibrium; it has been found that fast response can be achieved by reducing pumping power, increasing extracted heat from the rod, choosing a crystal having high thermal diffusivity and decreasing laser rod radius while its volume remains constant. One final advantage of the analytical solution is that a fast result can be obtained where the numerical solution usually is a time consuming technique.

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Cornea thermal damage due to incidental continuous wave CO2 laser irradiation is studied numerically based on bio-heat equation. The interaction of laser with tissue leads to a rapid temperature increased in target and the nearby tissue. As the temperature of the eye surface reaches 44?C, a sensation of pain will cause aversion response of the reflex blink and/or shifting away from the source of pain. The aim of the work is to predict numerically the threshold limit of incidental laser power that causes damage to the anterior part of the cornea, which can be healed within 2-5 days as long as damage is not exceeding the outer part of the eye (epithelium). A finite element analysis is used to predict temperature distribution through the cornea where the necroses region can be obtained using thermal dose equation. The thermal dose that required for damaging the cornea is predicted from previously published experimental data on rhesus monkeys and used later as a limit for shrinkage to human cornea. The result of this work is compared by international standard of safety and a good nearby result is obtained which verified the result of this work.

Laser welding process reduces the heat input to the work-piece which is the main goal in aerospace and electronics industries. A finite element model for axi-symmetric transient heat conduction has been used to predict temperature distribution through a steel cylinder subjected to CW laser beam of rectangular beam profile. Many numerical improvements had been used to reduce time of calculation and size of the program so as to achieve the task with minimum time required. An experimental determined absorptivity has been used to determine heat induced when laser interact with material. The heat affected zone and welding zone have been estimated to determine the effect of welding on material. The ratio of depth to width of the welding zone can be changed by proper selection of beam power to meet the specific production requirement. The temperature history obtained numerically has been compared with experimental data indicating good agreement.