Thermal Damage And Stress Of Underwater Germanium Glass Irradiated By Laser

Germanium glass has many applications in underwater environment,sometimes the problem of underwater laser irradiation occurs.Laser transmission in water and salt solution has a strong attenuation,the presence of salt ions in salt solution will affect the beam quality.In order to study the damage mechanism of underwater germanium glass irradiated by laser,the numerical simulation analysis of germanium glass irradiated by 1064 nm pulsed nanosecond laser in water and salt solution was carried out,the experimental system was established and carried out.Based on Comsol multiphysics,a mathematical and physical model of laser-irradiated underwater germanium glass is established by layering the process of laser transmission,absorption and reflection and absorption of germanium material in solution.The temperature and stress changes of germanium glass in salt solution with different concentration of salt and different distance of laser radiation in underwater germanium glass are analyzed.Experiments were carried out to irradiate germanium glass under water at different distances and germanium glass in salt solution with different salt concentration by laser,by means of spectral measurement and metallographic image device,the experimental process and results of germanium glass irradiated by laser in underwater germanium glass and in salt solution with different salt concentration were detected.The experimental process and results of laser irradiation of underwater germanium glass and laser irradiation of germanium glass in salt solution with different salt concentration were collected by spectral testing device.The surface damage morphology was measured by metallographic image device,the experimental results are analyzed.It is found that the propagation distance of laser in water has a great influence on the damage of germanium glass.With the increase of the propagation distance of laser in water,the damage of germanium glass surface decreases.The change of salt concentration in salt solution has little effect on germanium glass in salt solution irradiated by laser.Compared with laser irradiation of germanium glass in air,laser irradiation of underwater germanium glass does not show plasma spectral lines.Na and Cl plasma lines and an absorption peak appear in germanium glass in salt solution irradiated by laser.It is concluded that the damage degree of germanium glass surface decreases gradually with the change of laser underwater propagation distance,and the damage mechanism is also different.The plasma excited by germanium glass irradiated by laser in salt solution with different salt concentration is different.This research is of great significance to the underwater application of germanium glass and the underwater laser processing of germanium glass.