空間光位相変調器を用いたピコ秒パルスレーザによるガラス溶接特性の向上

抄録

In micro-welding of glass by using a laser, tightly focusing of high intensity ultra-short pulsed laser causes a nonlinear light absorption phenomenon inside the glass in the vicinity of focal point, and the micro-welding of glass is possible by locally internal melting. However, a large stress generates by the sudden change in the temperature during melting according to the concentration of laser energy in the vicinity of the focal point, and cracks formed inside the glass would deteriorate the bonding quality. In order to avoid the occurrence of cracks, it is important to control the energy distribution of laser beam. Thus, in the micro-welding of borosilicate glass using a picosecond pulsed laser, the energy distribution was controlled using a spatial light modulator (SLM). The separated laser beams by SLM were focused inside the glass at the multiple-point to control the energy distribution, and the shape of molten area and the welding characteristics were investigated. The separated laser beams at the multiple-point could form a rounded molten area, and the dispersion of laser energy from one beam to multiple beams enables the relaxation of energy concentration, which would contribute to suppress the occurrence of cracks during the welding process even by using a large energy condition. In addition, the arrangement of separated laser beams in the scanning direction has a possibility of functions as pre- and post-heating, which can reduce the generation of large stress by avoiding the sudden temperature change.