Long-pulsed laser-induced breakdown spectroscopy for elemental imaging: An evaluation with human teeth

Laser-induced breakdown spectroscopy (LIBS) is a practical technique for chemical imaging by analyzing elemental emissions. The utilization of long-pulsed lasers has been proven to enhance LIBS detection in water and air. However, the application of long-pulsed LIBS in imaging remains unexplored. In this study, we employed a laser with a pulse width of 100 ns for LIBS imaging to obtain elemental distribution using a human tooth as sample for performance evaluation. It is demonstrated that the tooth layer can be effectively resolved with distinct boundaries under the long-pulsed LIBS. When compared with a 10-ns pulsed laser, the LIBS emissions were generally enhanced under the long-pulse laser, resulting in improved chemical imaging capabilities. This enhancement might be attributed to higher mass consumption achieved through prolonged excitation. After examining plasma properties, it was found that the long-pulsed LIBS exhibited higher sensitivity towards changes in tooth layers. Furthermore, the molecular emission was significantly amplified under long-pulsed LIBS. The compositional distribution is also trackable using these molecular emissions, and more information could be extracted by referencing the correlation between element and molecules. Therefore, utilizing a long pulse laser can serve as an effective approach to enhance chemical imaging in LIBS analysis while providing alternative options such as molecular mapping.