Precise machining of ceramics by using a femtosecond terawatt laser

使用飞秒太瓦激光器精密加工陶瓷

• 批准号: 11555182
• 负责人: KONDO Ken-ichi
• 金额: $ 8.64万
• 依托单位: Tokyo Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B).
• 财政年份: 1999
• 资助国家: 日本
• 起止时间: 1999 至 2000
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-11555182/
• 关键词: femtosecond laser; laser machining; dielectric breakdown; ceramics; tera watt laser; optical communication device; precise machining; shock wave

In the first year, a set of precise stages for controlling a target position at five-axes were installed in the large vacuum chamber which was a part of the femtosecond, terawatt laser system. Some preliminary tests of machining were carried out in order to find a critical condition for dielectric breakdown in silicon crystal.The threshold laser fluence was 0.4 J/cm^2 for ablation in the case of a pulse width of 300 ps and was in good agreement with the extrapolation of the published data. The threshold fluence decreased under atmospheric condition. By changing energy of femtosecond laser at a pulse width of 50 fs, values of ablation threshold were experimentally examined for several ceramic materials such as fused quartz, optical glass(BK-7), alumina crystal, and calcium fluoride crystal. Threshold values for alumina crystal were analyzed by three methods as follows : (1) monitoring the scattered light from the sample surface, (2) gaussian fitting of laser energy spatial distribution to the crater shape of sample, and (3) fitting of the etching rate to the formula for five-photons absorption mechanism. They were in good agreement each other as follows : (1) 0.35, (2) 0.37, and (3) 0.37 J/cm^2, respectively. Such values were dependent on materials but did not reveal a simple linear relationship with magnitude of their bad gap. Calcium fluoride crystal was broken by the effect of thermalstress and/or shock waves that were generated after the irradiation of laser, because the crystal had a weak mechanical strength. A trial machining were carried out for patterning of some mask patterns such as character and designed mark. Sharp edges were obtained in the direction of the depth, but interference of laser light deformed the pattern. It requires modifying optical system without parabolic mirror. In conclusion, this femtosecond laser machining technology is promising that ceramics having a certain strength can be machined precisely without thermal damage.

在第一年，将一组用于控制五轴目标位置的精确阶段安装在大型真空室中，该室是femtsecond，terawatt Laser系统的一部分。进行了一些加工的初步测试，以找到硅晶体中介电击穿的临界条件。阈值激光通量为0.4 j/cm^2，以在300 ps的脉冲宽度为300 ps的情况下进行消融，并且与已发表数据的伸出非常吻合。阈值在大气条件下降低。通过在50 fs的脉冲宽度上改变飞秒激光的能量，通过实验检查了几种陶瓷材料，例如熔融石英，光玻璃（BK-7），氧化铝晶体和氟化钙晶体。通过三种方法分析了氧化铝晶体的阈值：（1）监测样品表面的散射光，（2）激光能量空间分布对样品的火山口形状的高斯拟合，以及（3）将蚀刻速度拟合到五光子吸收机制的蚀刻速率。他们在彼此之间相互良好一致：（1）0.35，（2）0.37和（3）0.37 J/cm^2。这样的值取决于材料，但并未揭示出简单的线性关系，其差距的大小。由于晶体的机械强度较弱，由于激光照射后产生的热剂和/或冲击波的作用破坏了氟化钙的晶体。进行了试验加工，以制定某些掩模图案，例如角色和设计标记。沿深度方向获得锋利的边缘，但是激光光的干扰使模式变形。它需要修改无抛物线镜的光学系统。总之，这种飞秒激光加工技术有望确切地将具有一定强度的陶瓷精确加工而不会受到热损坏。

项目成果

大野嘉土,水山淳,弘中陽一郎,矢崎秋夫,岡野泰彬,斎藤文一,中村一隆,近藤建一,竹中久貴: "超短パルスレーザー誘起による誘電体の誘電破壊と圧力発生"第41回高圧討論会講演要旨集. 70 (2000)

Kado Ohno、Jun Mizuyama、Yoichiro Hironaka、Akio Yazaki、Yasunori Okano、Bunichi Saito、Kazutaka Nakamura、Kenichi Kondo、Hisataka Takenaka：“超短脉冲激光诱导介电材料中的介电击穿和压力产生”第 41 卷摘要集。高电压研讨会。70 (2000)

大野嘉士,弘中陽一郎、矢崎秋夫,岡野泰彬,斎藤文一,中村一隆,近藤建一,竹中久貴: "超短パルスレーザー誘起による誘電破壊と圧力発生"平成11年度衝撃波シンポジウム講演論文集. 637-640 (2000)

Yoshihiro Ohno、Yoichiro Hironaka、Akio Yazaki、Yasuaki Okano、Bunichi Saito、Kazutaka Nakamura、Kenichi Kondo、Hisataka Takenaka：“超短脉冲激光引起的介电击穿和压力产生”1999 年冲击波研讨会论文集 637-640（2000 年）。

Y.Ohno, Y.Hironaka, A.Yazaki, Y.Okno, K.G.Nakamura and K.Kondo: "Ultra short pulsed laser induced breakdown and generation of compression in Si"Proc.of Symposium on shock wav, JAPAN 2000, Tokyo University, on March 16-18. 637-640 (2000)

Y.Ohno、Y.Hironaka、A.Yazaki、Y.Okno、K.G.Nakamura 和 K.Kondo：“超短脉冲激光诱导的 Si 中的击穿和压缩产生”Proc.of Symposium on shock wav，JAPAN 2000，东京大学

Y.Ohno, J.Mizuyam, Y.Hironaka, A.Yazaki, Y.Okano, F.Saito, K.G.Nakamura, K.Kondo and H.Yakenaka: "Dielectric breakdown and shock wave generation by femtosecond laser irradiation."Proc. of Symposium on shock wav, JAPAN 2001, ISAS, on March 8-10. 511-514 (2

Y.Ohno、J.Mizuyam、Y.Hironaka、A.Yazaki、Y.Okano、F.Saito、K.G.Nakamura、K.Kondo 和 H.Yakenaka：“飞秒激光照射产生的介电击穿和冲击波。”Proc。

大野嘉士,水山淳,弘中陽一郎、矢崎秋夫,岡野泰彬,斎藤文一,中村一隆,近藤建一,竹中久貴: "超短パルスレーザー誘起による誘電体の誘電破壊と圧力発生"第41回高圧討論会講演要旨集. 70 (2000)

Yoshihiro Ohno、Jun Mizuyama、Yoichiro Hironaka、Akio Yazaki、Yasunori Okano、Bunichi Saito、Kazutaka Nakamura、Kenichi Kondo、Hisataka Takenaka：“超短脉冲激光诱导介电材料中的介电击穿和压力产生”第 41 期高压摘要研讨会。70（2000）