Influence of crystal anisotropy on subsurface damage in ultra-precision cylindrical turning of CaF2
Influence of crystal anisotropy on subsurface damage in ultra-precision cylindrical turning of CaF2
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DOI：
10.1016/j.precisioneng.2017.01.017
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发表时间：
2017-07
影响因子：
3.6
通讯作者：
Yuta Mizumoto;H. Kangawa;Hiroki Itobe;T. Tanabe;Y. Kakinuma
中科院分区：
文献类型：
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作者：
Yuta Mizumoto;H. Kangawa;Hiroki Itobe;T. Tanabe;Y. Kakinuma
光微腔是实现全光信号处理的重要组成部分，它将光存储在一定的点上。单晶氟化钙（CaF2）理论上具有较高的q因子，这是一种理想的光学性质。caf2微腔只能通过超精密圆柱车削（UPCT）加工。对caf2的UPCT进行了研究，揭示了晶体各向异性和刀具几何形状对表面粗糙度和亚表面损伤的影响。研究表明，较小的切削齿鼻半径导致较浅的次表面损伤。因此，可以推断，与之前的鼻半径（0.05 mm）相比，更小的鼻半径可以进一步减少表面下损伤。然而，由于晶体各向异性导致亚表面损伤差异的机制还不够清楚。亚表面损伤对微腔性能的影响尚不清楚。在本研究中，使用鼻口半径为0.01 mm的工具进行caf2的UPCT。采用透射电镜（TEM）从晶格排列变化的角度观察了亚表面损伤。在我们之前的研究中，使用快速傅里叶转移（FFT）分析来确认晶体结构的变化。在本研究中，FFT分析也用于定量评价亚表面损伤的深度。此外，利用快速反傅立叶变换（IFFT）清晰地分析了晶体晶格排列的变化，从而讨论了滑移系统的影响。最后，利用波长可调谐激光器和功率计实验评估了亚表面损伤对微腔性能的影响。
An optical microcavity, which stores light at a certain spot, is an essential component to realize all-optical signal processing. Single-crystal calcium fluoride (CaF2) theoretically shows a high Q-factor which is a desirable optical property. The CaF2microcavity can only be manufactured by ultra-precision cylindrical turning (UPCT). The authors have studied UPCT of CaF2and shown the influence of crystal anisotropy and tool geometry on surface roughness and subsurface damage. The study indicated that a smaller nose radius of the cutting tool led to shallower subsurface damage. Thus, it is inferred that a smaller nose radius compared to the previous nose radius (0.05 mm) can further reduce subsurface damage. Nevertheless, the mechanism that causes a difference in subsurface damage due to crystal anisotropy is not sufficiently clear. The influence of subsurface damage on microcavity performance is still unclear. In this study, the UPCT of CaF2was conducted using a tool with a nose radius of 0.01 mm. The subsurface damage was investigated by transmission electron microscope (TEM) observation from the viewpoint of the change in crystal lattice arrangement. In our previous study, fast Fourier transfer (FFT) analysis was used for confirmation of change of crystal structure. In this study, FFT analysis was also used to quantitatively evaluate the depth of subsurface damage. In addition, inverse fast Fourier transfer (IFFT) was used to analyze change of crystal lattice arrangement clearly, which enables discussion of the influence of slip systems. Finally, optical microcavities are manufactured without any crack, and the influence of subsurface damage on microcavity performance is experimentally evaluated using a wavelength tunable laser and power meter.