利用CVD金刚石实现光学衍射光栅新技术

实验室合成钻石 2018-12-05 16:21:21

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利用CVD金刚石

实现光学衍射光栅新技术


瑞士洛桑联邦理工学院研究出一种新技术将纯金刚石制成光学衍射光栅。这些新原件可以用来改变高性能激光的波长,也可应用于先进的光谱仪。

瑞士洛桑联邦理工学院科研人员研发一种新方法,通过显微镜将金刚石切割成特定的形状,并打磨抛光。2017年9月5日,在国际金刚石和碳材料大会上介绍了这种技术。这个新技术对光谱学和高能量激光光学原件有独特意义。

类似棱镜,衍射光栅由平行的细槽构成,这些细槽将光分散为光谱分量。衍射光栅由玻璃和硅材料制成,它可以改变激光的颜色。



瑞士洛桑联邦理工学院的工程系的教授尼尔斯夸克带领的研究小组发现单晶金刚石也可以制成衍射光栅。这项发现开启了该领域的新可能。金刚石具有很好热传导性,是其他材料的5到10倍。金刚石硬度极高,在UV射线,红外线及其他可见光束下工作性能良好。金刚石具有化学惰性,即使腐蚀性最强的化学物质也不能将其腐蚀。这也意味着金刚石很难加工制造。这种新的切割方式非常有效。

利用氧气来切割金刚石

研究小组发现的这项技术具有开创性意义,利用这个技术将金刚石蚀刻为毫米级别的单晶金刚石碟。表面光洁度很高,槽与槽直接的距离只有几微米。研究中科研小组用的是化学气相沉积法制成的CVD金刚石。



金刚石蚀刻分为以下几个步骤,首先,在金刚石的表面沉积形成一层硬膜,之后通过氧气电浆,通过电场的作用在金刚石表面形成氧离子。没有硬膜的覆盖的地方,氧离子使碳原子脱离金刚石表面。“通过调节电场的强度,可以改变金刚石蚀刻的形状。”教授尼尔斯夸克介绍。“我们雕刻出槽间距为几微米的三角形的沟槽,用来制作衍射光栅。调整加工参数,有选择性的展示出界限清楚的一组晶面。采用这种加工方式,我们可以加工出原子层级平滑的V型槽,用激光切割方式是不可能实现的。”



洛阳誉芯金刚石制备的CVD单晶金刚石是采用微波等离子法(Microwave Plasma Chemical Vapor Deposition)制造而成。具有硬度高、耐磨性好、强度高、导热性好、摩擦系数低、抗黏结性好以及优良的抗腐蚀性和化学稳定性,可以刃磨出极其锋利的刀刃,被认为是最理想的超精密切削用刀具材料,在机械加工领域尤其是超精密加工领域有着重要地位并得到广泛应用。

特点:适用于超精密刀具,特别是加工有色金属材料,如铝(合金)、铜、高分子材料(MMCs)、碳纤维增强塑料(CFPs)

零件表面可达到镜面效果,其表面粗糙度可达到Ra-0.1μm以下。



Diamond Optical Gratings to Enable

 New Uses in Spectroscopy and 

High-power Laser Control


Thanks to a new technique developed at École polytechnique fédérale de Lausanne (EPFL; Lausanne, Switzerland), optical diffraction gratings can now be made out of pure diamond, with their surfaces smoothed down to the atomic level. These new devices can be used to spectrally control high-powered lasers or in cutting-edge spectrographs. The technique was presented at the International Conference on Diamond and Carbon Materials DCM2017 (5 September, 2017; Gothenburg, Sweden).



Diamond gratings have properties that are ideal for both spectroscopy and the optical components used in high-powered lasers. Diamonds are unmatched in terms of their thermal conductivity, which is between five and ten times greater than that of any other material used for this purpose. Diamonds are also chemically inert, extremely hard, and work well with UV radiation, as well as infrared and visible light.

Using Oxygen cuts diamonds

The technique developed by the team, which was led by EPFL professor Niels Quack, is groundbreaking because it allows well-defined shapes to be etched into millimeter sized single-crystal diamond plates, with the grooves separated by just a few microns and with atomically smooth surfaces. The researchers used synthetic diamonds created via chemical vapor deposition (CVD).



The diamonds are etched in several stages. First, a hard mask is deposited and structured on the surface of a diamond plate, which is then exposed to an oxygen plasma. The oxygen ions in the plasma are accelerated onto the surface of the diamond by an electric field. Where not covered by the hard mask, the oxygen ions remove carbon atoms from the diamond's surface one by one.


"By adjusting the intensity of the electric field, we can alter the shape we etch into the diamond," says Quack. "For the diffraction gratings, we carve out triangular grooves that are just a few microns apart from each other. We adjust the process parameters to selectively reveal a set of well-defined crystal planes, allowing us to create V-shaped grooves that are smoothed down almost to the atomic level. It is impossible to get this kind of precision when the diamonds are simply cut with a laser."



Luoyang Yuxin Diamond Co., Ltd's CVD single crystal diamond is manufactured by Microwave Plasma Chemical Vapor Deposition. With good wear resistance, thermal conductivity and compressive resistance, high hardness and strength, low friction coefficient, excellent corrosion resistance and chemical stability, it can be sharpened into very sharp blade, and it is considered to be the most ideal ultra-precision cutting tool material, which occupies an important position and is widely used in the mechanical processing field especially the ultra precision processing field.

 

Features: used in ultra precision cutting tools, especially processing non-ferrous metal materials, such as aluminum (alloy), copper, high polymer materials (MMCs), carbon fiber reinforced plastics (CFPs) Parts surface can be the mirror effect, and its surface roughness can reach below Ra-0.1μm.



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