Molten Area Characteristics in Micro-welding of Glass by Picosecond Laser

抄録

In this study, a picosecond pulsed laser of 1064 nm in wavelength and 12.5 ps in pulse duration was used as a laser source for joining of glass material, and characteristics of the molten area in micro-welding of borosilicate glass are described. Influence of focusing condition on microwelding of glasses was experimentally investigated by using an objective lens with and without spherical aberration correction, and its molten area was characterized. Also, influence of pulse interval on the molten area of laser-irradiated specimens by focused laser beam with spherical aberration correction was discussed. The usage of objective lens with spherical aberration correction led to a larger molten area inside the bulk material of glass even under the same pulse energy, which related to the efficient micro-welding of glass materials. In addition, an optical system with the spherical aberration correction led to a stable absorption of laser energy inside the bulk glass material, stabilizing the shape of molten area, which resulted in the reliable weld joint. It was also found that shape of molten area after the laser irradiation became larger at shorter pulse interval compared with that in longer pulse interval. Finally, pulling test results showed that breaking strength of the specimens with spherical aberration correction was higher than that without spherical aberration correction. Therefore, it is concluded that the laser irradiation condition at shorter pulse interval and focusing condition with spherical aberration correction led to the larger and stable molten area, which resulted in higher joining strength in micro-welding of glass materials.