White marking inside the transparent plastic materials by 1.55 μm nanosecond pulse fiber laser

In this paper, the authors report that it is possible to create a white marking inside transparent plastic materials by heating them to a temperature close to the threshold of creating a void and using a fiber laser. Heating plastic materials and using a fiber laser enable the threshold to be in excess only in the focus position, and a white marking is created. The authors experimented with polycarbonate and polyethylene terephthalate as the transparent plastic materials, and a 1.55 μm nanosecond pulse fiber laser as the laser equipment. They irradiated laser in the sample inside while heating. As a result, when polycarbonate was heated to 150 °C and polyethylene terephthalate to 50 °C, a void was created at the focus position. Therefore, the authors successfully created a white marking inside the transparent plastic materials by heating them and using a fiber laser.