Study On Several Nanosecond 532 Nm Laser High-Precision Machining Of Brittle Transparent Material

Brittle transparent materials such as soda-lime glass and quartz glass have been widely applied in the field of optoelectronics,lighting and photovoltaics etc,because of their excellent physical and chemical characteristics.Traditional diamond or carbide cutter wheel marking processing methods have many disadvantages,such as many working procedures and material loss.With the continuous progress of laser technology,laser machining has unique advantages in the processing accuracy and efficiency of brittle transparent materials.Long pulse laser changes the physical characteristics of the machining region,because of the thermal effect;although ultrashort pulse laser solves the problem of thermal effect and improves the processing quality,the inner cut piece after machining is difficult to separate from the substrate in the machining of small size structure,and the processing efficiency is low.Nanosecond laser can realize the machining of brittle transparent materials with low heat effect,but how to further realize high-precision machining is still a problem to be solved.In this thesis,several nanosecond 532 nm laser high-precision machining of brittle transparent materials are studied.Combined with the physical basis of the interaction between short pulse laser and materials and the proportion of powder mass to total removal mass,the material removal mechanism of brittle transparent materials by several nanosecond 532 nm laser is studied.Results show that the removal mechanism of transparent brittle materials by the high repetition frequency and several nanosecond 532 nm laser is that the local temperature rise in the processing area of the materials by laser irradiation induces the local large thermal stress gradient which causes cracking and removal of material in a limited space.The particle size characteristics of powder produced by laser ablation are studied by equivalent particle diameter.Results show that larger pulse energy leads to the result that the particle size distribution curve gradually moves to the left and the particle size distribution is more concentrated;in order to machine successfully and efficiently,the cutting path width is set at about 0.3 mm.A compact and easily operated machining experimental platform for brittle transparent material is built.Then,through hole processing characteristics is studied by several nanosecond 532 nm laser for induced material removal from the rear side in an orbit-in-orbital path on samples.Based on the maximum effective cutting speed,the cutting of through hole on different thickness glass sample is studied.Results show that although larger pulse energy leads to higher effective cutting speed,larger pulse energy leads to the worse edge cutting quality;the residual heat generated during the ablation process by subsequent laser pulses accumulates along the scan path as the heat conduction is slow,and the laser-induced thermal stresses may lead to the material cracking;the edge cutting quality of the front side is better than that of the rear side.Based on the research of the influences of processing parameters on cutting performance,the optimization method of dual energy overlapping is proposed by which a cutting with good cutting quality at the highest possible effective cutting speed can be achieved.The high-precision machining of complex structure on thick brittle transparent materials is successfully carried out by using the optimization method.For the high depth diameter ratio through hole machining of brittle transparent materials by several nanosecond 532 nm laser,the layer by layer material removal process of through hole bore covered by laser concentric circles scanning on the rear surface has more advantages.The results in this thesis have important application value in the several nanosecond green laser high-precision machining of transparent brittle materials.