tailieunhanh - Micromachining Techniques for Fabrication of Micro and Nano Structures Part 4

Tham khảo tài liệu 'micromachining techniques for fabrication of micro and nano structures part 4', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Fundamentals of Laser Ablation of the Materials Used in Microfluiducs 49 Sapphire Silicon Scan speeds 5 mm s 10 mm s 20 mm s 50 mm s Threshold Fluence J cm2 266nm Nd YAG 355nm Nd YAG Table 2. The threshold fluences of laser micromachining of sapphire and silicon Fig. 6. The ablation rates for laser micromachining versus laser fluence for sapphire with different cutting speeds using 266 nm and 355 nm Nd YAG lasers. Laser Fluence J cmA2 Fig. 7. The ablation rates of laser micromachining versus laser fluences for silicon with different cutting speeds using 266 nm and 355 nm Nd YAG lasers. 50 Micromachining Techniques for Fabrication of Micro and Nano Structures Fig. 8. The ablation rates for laser micromachining versus laser fluences for Pyrex with different cutting speeds using 266 nm and 355 nm Nd YAG lasers. The ablation efficiency The ablation efficiency was calculated by dividing the ablation rate by the energy per pulse to normalize the ablation rate performed by the 355 nm and 266 nm Nd YAG lasers. Figures 9 - 11 show the plots of ablation efficiency as a function of laser fluence with various scan speeds using both lasers. The results indicate that at high laser fluences the ablation efficiencies of the 266 nm laser are better than that of the 355 nm laser for all three materials. Figure 10 silicon shows that the ablation rate of 266 nm Nd YAG laser micromachining is slower than 355 nm laser micromachining under 50 mm s scan speed after normalizing the ablation rate by energy per pulse. The result points out that at the laser fluences higher than 10 J cm2 the ablation efficieny of the 266 nm laser is times faster than that of the 355 nm laser at the scan speed of 50 mm s and times faster in the case of 20 mm s as shown in Table 3. Sapphire Silicon Pyrex Ablation Efficiency 50 mm s 20 mm s 266 nm 355 nm 9 13 Table 3. The comparison of Nd YAG 266 nm and 355 nm laser ablation efficiencies to sapphire .