双光子三维微细加工重复率对表面形貌的影响

Effect of overlapping degree on surface roughness in two photon micro fabrication

飞秒激光三维微细加工是一种集超快激光、CAD/CAM、光化学材料等技术于一体的新型加工方法,它采用单点扫描累积成型,由点成线,由线成面进行加工.要得到精细的三维微器件,不仅需要高加工分辨率,还须选用合适的扫描步距.我们采用不同重复率工艺参数进行实验,并对得到的表面质量进行了分析,优化了微器件加工的重复率参数.还基于自由基浓度理论和曝光等效性原理,对重复率影响表面质量进行了仿真.加工系统采用飞秒激光光源:脉宽为80fs,中心波长为800nm,重复频率为80MHz,输出功率为400mW;使用数值孔径(NA=1.25)浸油物镜聚焦;三维扫描使用PZT移动台;材料是新型聚丙烯类S-3负性光刻胶.实验中采用步距0.1,0.2,0.3,0.4μm得到不同平面,并测得其表面粗糙度,分析了重复率对微器件表面质量的影响.

Femtosecond laser microfabrication is a new processing method combining such technologies as ultra fast laser, CAD/CAM and photochemical material etc, for fabricating micro devices by means of layer-by-layer writing, In making a good micro device, the overlapping degree is a key parameter aside from the resolution, Thus the effect of different overlapping degrees on the quality of surfaces was studied, Theoretical emulation was also performed based on the free-radical theory and the equivalent exposition principle, In the experiments, an 80 fs pulsewidth and 800 nm wavelength femtosecond laser, mode locked at 80 MHz repetition rate, was used as the two-photon irradiation source. The laser beam was focused by a high numerical aperture （NA = 1.25） oil immersion objective lens. Sample scanning was realized by a piezostage, The photopolymer material consisted of radical initiators, urethane acrylate monomer and oligomers, Different overlapping degrees with the paces of 0.1, 0, 2, 0, 3 and 0.4 μm were used to get different surfaces, After measuring and analyzing the surface roughness, the most suitable overlapping degree was found for a high-quality micro device fabrication.