Research On Laser Etching Technology Of Diamond Micro Groove

As the third generation of ultra wide band gap semiconductor materials,diamond has excellent mechanical properties,good thermal conductivity,low coefficient of thermal expansion at room temperature,and good transmittance for most wavelength lasers.Due to these characteristics of diamond,laser is a good method for diamond processing.Water-jet guided laser processing can extend the focus of the laser and improve the processing efficiency along the axial direction.the area of heat affected zone is small and there is no slag in the processing process;The pulse width of femtosecond laser is very short,and the electron temperature in the working area rises instantaneously,and the electron becomes plasma state and breaks away by jet.Therefore,the thermal effect is very small,and the surface quality is very high.In order to meet the requirements of high-quality processing of diamond micro groove,this paper studies the application of two laser processing methods in the processing of diamond micro groove.First of all,based on the Fourier heat conduction theory and thermal elastic-plastic theory,this paper studies the material removal process in the processing of water-jet guided laser.Considering the heat transfer effect of water jet,the finite element simulation model of water-jet guided laser machining was established,and the water-jet guided laser machining of diamond was simulated.Secondly,the change of temperature field and stress field in the process of diamond material etching is simulated.The change rule of machining effect of water-jet guided laser with pulse number,laser output power and water jet diameter is analyzed by simulation.The change rule of water guided laser grooving with scanning times and laser power is explored experimentally.Then,in this paper,the law of femtosecond laser machining holes is explored through experiments,and the ablation threshold of 515nm femtosecond laser machining single crystal diamond is calculated.The rules of femtosecond laser groove and multi-channel scanning groove are also studied,it is found that with the increase of scanning speed,the depth and width of multi-channel scanning groove decrease a little,but when the scanning interval is large and the scanning speed is too fast,the groove will appear obvious overlap marks.Finally,this paper compares and analyzes the processing effect of water-jet guided laser processing and femtosecond laser processing,and combines the two processing methods to process diamond microgrooves.That is,femtosecond laser is used to modify the microgrooves after water-jet guided laser processing.After modification,the grooved-surface is regular,and the R_aand R_zindexes related to roughness are decreased.And the quality of modification increases with the decrease of scanning speed.When the scanning speed is between 0.5mm/s and 1mm/s,the modification effect is good,and the R_a value can reach about 1.2μm.