Laser Machining Process Planning Of Complicated Micro-structures

Ultrashort laser is an advanced technology widely used, one of the ideal ultra-precision micro-machining means. Ultrashort laser is developing toward the directions of the shorter wavelength and the shorter pulse,157nm excimer laser and femtosecond laser are the most representative.157nm excimer laser owns advantages of high single-photon energy, minimal heat affected zone and high etching precision; femtosecond laser outputs femtosecond(10-15s) pulse, with the characteristics of short time acting on the material and high peak power. Compared to traditional processing methods, ultrashort laser is easier to obtain high machining accuracy and the ideal performance,which is the hottest research frontier of laser technology.In this paper, to research maching’s process planning using the157nm laser of ultrashort wave length and the femtosecond laser of ultrashort pulse, the ultrashort laser micro-machining CNC automatic programming system(man-machine interface) is developed. Combination of mathematical models and basic micro-machining experiments is to find the influences of process parameters on the processing quality, and to find optimal combinations of process parameters.The content and the research results of this paper are as follows:(1)157nm laser machining’s process planning and the basic experiments are done. The results show that, for157nm laser polishing,when the cumulative radiation energy of etched surface is about350J/cm2, surface roughness Ra can achieve the best20nm. The mathematical model is built by mathematical analysis methods, and the least square method is to derive the calculation formula of the roughness Ra. It explains gully’s formation of the polished surface, which provides a theoretical basis to improve the machining quality in the future.(2) Process planning of femtosecond laser machining is researched. In the experiments of the femtosecond laser polishing quartz materials, when other process parameters are the same, the greater the scan line distance, the more obvious the gully, the rougher the underside. Matlab with powerful computing and graphics capabilities can construct a mathematical model to explain the formation mechanism of roughness. Fristly small laser energy should be used in the femtosecond polishing, then utilize the roughness mathematical model to select the appropriate scan line distance.(3) The interactive interface based on ultrashort laser micromachining is developed by using tools of Visual Basic and Matlab. Man-machine interface consists of157nm excimer laser micromachining and femtosecond laser micromachining. It can automatically generate the NC instruction code to drive the stage. Matlab can simulate machining process of the selected shape. According to the simulation results, users can adjust the appropriate process parameters until it reaches the desired processing quality.