Laser Direct Writing of Diamond Micro-nozzle Using Q-Switched Nd:YAG Laser
Laser Direct Writing of Diamond Micro-nozzle Using Q-Switched Nd:YAG Laser
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调Q Nd:YAG激光器激光直写金刚石微喷嘴
DOI：
10.29979/jcsme.200808.0003
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发表时间：
2008
期刊：
影响因子：
--
通讯作者：
Jeng
中科院分区：
文献类型：
--
作者：
X. Chou;Jiaxiu Wang;Jeng
在这项工作中，使用脉冲宽度为 170 ns 的 Q 开关 Nd: YAG 激光器（1064 nm）在 Ib 型单晶金刚石上制造 3D 几何特征。基于激光直写方法加工3D几何特征，而不是光掩模辅助技术（掩模投影）来制造用于纳米粉末喷涂装置的金刚石喷嘴。金刚石很难加工，因为它在很宽的波长范围内是透明的。然而，在高激光功率密度下，由于非线性吸收现象，吸收系数会显着增加。因此，使用Q开关Nd:YAG激光器激光烧蚀金刚石的结论是，激光注量达到阈值注量，将引起光学非线性吸收，形成热刺激过程。我们将金刚石激光烧蚀的材料去除机制视为结合了化学反应和物理反应的两步过程。第一步是在 1500K 左右的温度下将晶态金刚石结构转变为层状石墨（称为石墨化过程），然后层状石墨在 4000K 左右的温度下升华（称为升华过程）。实验确定石墨化和升华步骤的激光辐照度阈值分别为 0.45 J/mm^2 和 1.14 J/mm^2。由于采用激光直写方法，因此可以使用 CAD/CAM 软件直接生成各层图案。最后，我们证明了使用 170 ns 脉冲宽度和 1064 nm 波长的 Nd-YAG 激光制造出具有清洁且低 HAZ（热影响区）表面外观的金刚石微喷嘴。通过拉曼光谱检查激光处理的金刚石基底。结果证实金刚石上残留的石墨层并不明显。激光加工后基材表面仍保持单晶金刚石状态。
In this work, a Q-switched Nd: YAG laser (1064 nm) with a pulse width of 170 ns was used to fabricate 3D geometric features on the type Ib single crystal diamond. The 3D geometric features were machined based on the laser direct writing method instead of photo-mask assisted technique (mask projection) to fabricate diamond nozzle for nano-powder spray devices. Diamond is difficult to machine because it is transparent in a wide wavelength range. However, under high laser power density, the absorption coefficient can be increased significantly due to the nonlinear absorption phenomenon. Therefore a conclusion of the laser ablation of diamonds using a Q-switched Nd:YAG laser is the laser fluence up to a threshold fluence that will cause the optical nonlinear absorption to form a thermally stimulated process. We considered the material removal mechanism of laser ablation of diamond as a two-step process which combines the chemical and physical reactions. The first step employs a transformation of the crystalline diamond structure to the layered graphite at a temperature around 1500K (called the graphitization process), and followed by the sublimation of the layered graphite at a temperature around 4000K (called the sublimation process). The laser irradiance thresholds for the graphitization and sublimation steps were experimentally identified as 0.45 J/mm^2 and 1.14 J/mm^2 respectively. Because of the laser direct writing method, it permits direct pattern generation of each layer by use of CAD/CAM software. Finally, we demonstrated that a diamond micro-nozzle was fabricated with clean and low HAZ (heat affected zone) surface appearance using the Nd-YAG laser of 170 ns pulse width and 1064 nm wavelength. The laser-treated diamond substrate was examined by a Raman spectroscopy. The result confirms that the residual graphite layer on the diamond is not significant. The substrate surface remained as single crystalline diamond state after the laser processing.