By Isamu Miyamoto

The author started laser materials processing in 1965 with developing the CO₂ laser, and since then has been involved in a variety of materials processing using CW (continuous wave) to USLP (ultrashort laser pulse). Among them laser welding has attracted a lot of the author’s interest because of its profound and interesting physics from linear to nonlinear processes. The author’s work on laser welding is classified into two groups; depending on the laser absorption process. In the first group, CW laser welding process is studied based on linear absorption process, and the research efforts are directed to understanding keyhole welding process, and expanding the process limits. In the second group, USLP welding is analyzed where the laser energy is absorbed by nonlinear process, and is shown to provide excellent welding performances so that the most process limits found in the first group are in principle removed. In this paper, laser welding technology is presented starting from its origin using a CO₂ laser to a new wave of laser welding brought by USLP. Continue reading →