Refraction is a well-known optical phenomenon that alters the direction of light waves propagating through matter. Microscopes, lenses and prisms based on refraction are indispensable tools for controlling light beams at visible, infrared, ultraviolet and X-ray wavelengths1. In the past few decades, a range of extreme-ultraviolet and soft-X-ray sources has been developed in laboratory environments2–4 and at large-scale facilities5,6. But the strong absorption of extreme-ultraviolet radiation in matter hinders the development of refractive lenses and prisms in this spectral region, for which reflective mirrors and diffractive Fresnel zone plates7 are instead used for focusing. Here we demonstrate control over the refraction of extreme-ultraviolet radiation by using a gas jet with a density gradient across the profile of the extreme-ultraviolet beam. We produce a gas-phase prism that leads to a frequency-dependent deflection of the beam. The strong deflection near to atomic resonances is further used to develop a deformable refractive lens for extreme-ultraviolet radiation, with low absorption and a focal length that can be tuned by varying the gas pressure. Our results open up a route towards the transfer of refraction-based techniques, which are well established in other spectral regions, to the extreme-ultraviolet domain.A refractive lens and a refractive prism for extreme-ultraviolet radiation have been developed that use the deflection of the radiation in an inhomogeneous jet of atoms.

中文翻译：

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极紫外折射光学

折射是一种众所周知的光学现象，它改变了光波在物质中传播的方向。基于折射的显微镜、透镜和棱镜是控制可见光、红外线、紫外线和 X 射线波长的光束不可或缺的工具。在过去的几十年中，在实验室环境 2-4 和大型设施 5,6 中开发了一系列极紫外和软 X 射线源。但是物质对极紫外辐射的强烈吸收阻碍了该光谱区域中折射透镜和棱镜的发展，为此使用反射镜和衍射菲涅耳波带片7进行聚焦。在这里，我们展示了通过使用具有跨极紫外光束轮廓的密度梯度的气体射流来控制极紫外辐射的折射。我们生产了一个气相棱镜，导致光束的频率相关偏转。原子共振附近的强偏转进一步用于开发用于极紫外辐射的可变形折射透镜，具有低吸收和可通过改变气压来调整焦距。我们的研究结果开辟了一条途径，将基于折射的技术（在其他光谱区域已经很好地建立）转移到极紫外域。 已经开发了用于极紫外辐射的折射透镜和折射棱镜，它们使用偏转不均匀的原子射流中的辐射。原子共振附近的强偏转进一步用于开发用于极紫外辐射的可变形折射透镜，具有低吸收和可通过改变气压来调整焦距。我们的研究结果开辟了一条途径，将基于折射的技术（在其他光谱区域已经很好地建立）转移到极紫外域。 已经开发了用于极紫外辐射的折射透镜和折射棱镜，它们使用偏转不均匀的原子射流中的辐射。原子共振附近的强偏转进一步用于开发用于极紫外辐射的可变形折射透镜，具有低吸收和可通过改变气压来调整焦距。我们的研究结果开辟了一条途径，将基于折射的技术（在其他光谱区域已经很好地建立）转移到极紫外域。 已经开发了用于极紫外辐射的折射透镜和折射棱镜，它们使用偏转不均匀的原子射流中的辐射。