GOALI: High resolution diffractive x-ray optics

[00:99893]雅各布森电磁辐射的终极焦点是什么？透镜的远场聚焦的特点是其瑞利分辨率为0.61倍的波长除以透镜开角或数值孔径的一半。为了获得比可见光激光和高数值孔径显微镜物镜（如共聚焦显微镜）获得的更精细的聚焦，必须在保持可观的数值孔径的同时显著减小波长。这可以通过使用x射线的短波长和衍射光学来实现，以保持一个合理的高数值孔径。菲涅耳x射线带片被制成衍射聚焦光学器件，在任何波长下都能产生最好的远场电磁辐射聚焦——在2-5纳米波长下，瑞利分辨率约为35纳米。这些区域板是由纽约州立大学石溪分校物理和天文学系的一个小组和朗讯技术贝尔实验室的唐·坦南特的最先进的电子束光刻组在布鲁克海文国家实验室使用国家同步加速器光源（NSLS）进行x射线显微镜研究的学术-工业合作制造的。这次合作生产的带板被用作NSLS的三个x射线显微镜系统的聚焦光学元件，这些显微镜被石溪小组和许多美国和欧洲小组用于生物学、聚合物科学、地球科学、胶体化学、环境科学和其他领域的x射线显微镜研究。鉴于x射线微聚焦在包括布鲁克海文、阿贡、伯克利、斯坦福、康奈尔、威斯康星大学和路易斯安那州立大学在内的美国同步辐射设施中越来越重要，而且这些设施中的每一个都代表着2000万至5亿美元的投资，因此在美国的学术环境中进一步发展制造最高分辨率带片所需的工艺似乎至关重要。如果带片的空间分辨率能够大大提高到现在所能达到的水平，那么x射线显微镜（包括0.2-1 keV能量范围和1-10 keV能量范围）的大量潜在应用将成为可能。PIs的研究计划包括以下内容：o他们建议向世界领先的超快x射线脉冲产生小组之一：科罗拉多大学/JILA的Margaret Murnane和Henry Kapetyn实验室提供带片。这将使人们能够在热核武器以外的环境中首次探索x射线波长的非线性光学。他们建议开发带片，这应该是第一次，使低于100纳米分辨率成像常规可用于1-10 keV x射线显微镜。该能量范围内的显微镜是生物学和环境科学中微量元素测绘的理想选择，也是检测集成电路中埋藏互连缺陷的理想选择。o他们提出针对Bragg带片的未来发展进行实验测试，在Bragg条件下，高长宽比带必须成角度，以实现高聚焦效率和非常高的数值孔径。o他们建议与纳米压印技术的领先团队之一（德克萨斯大学奥斯汀分校）合作，将我们在细线宽带板制造方面的能力与他们的高通量光刻制造技术相结合。最终目标是制造有限数量的高分辨率“主”带片，并使用UTA纳米压印方法制造“一次性”高分辨率带片。这可能是一个高风险、高回报的科学项目的关键技术：使用x射线自由电子激光器获得膜蛋白结构的原子分辨率图。

0099893JacobsenWhat is the ultimate focus of electromagnetic radiation? The far-field focus of a lens can be characterized by its Rayleigh resolution of 0.61 times the wavelength divided by half of the lens' opening angle, or numerical aperture. To achieve a finer focus than that obtained from a visible light laser and a high numerical aperture microscope objective (such as in a confocal microscope), one must significantly decrease the wavelength while still maintaining appreciable numerical aperture. This can be accomplished by using x rays for their short wavelength, and diffractive optics for maintaining a reasonably high numerical aperture. Fresnel x-ray zone plates have been fabricated as diffractive focusing optics that produce the finest far-field focus of electromagnetic radiation at any wavelength - about 35 nm Rayleigh resolution at 2-5 nm wavelength. These zoneplates have been fabricated in an academic-industrial collaboration between a group at the Department of Physics and Astronomy at SUNY Stony Brook that carries out research in x-ray microscopy using the National Synchrotron Light Source (NSLS) at nearby Brookhaven National Laboratory, and the state-of-the-art electron beam lithography group of Don Tennant at Lucent Technologies Bell Laboratories. Zone plates produced by this collaboration are employed as the focusing optics in three x-ray microscope systems at the NSLS, and these microscopes are used by the Stony Brook group and by a number of U.S. and European groups for research in biology, polymer science, geoscience, colloid chemistry, environmental science, and other fields using x-ray microscopy. Given that x-ray microfocusing is growing in importance at U.S. synchrotron radiation facilities including those at Brookhaven, Argonne, Berkeley, Stanford, Cornell, University of Wisconsin, and Louisiana State University, and that each of these facilities represents an investment of $20-500 million, it seems crucial to further develop the processes needed for fabrication of the highest possible resolution zone plates within an academic setting in the U.S. Indeed, a large number of potential applications of x-ray microscopes (both in the 0.2-1 keV energy range, and the 1-10 keV energy range) would become possible if the spatial resolution of zone plates were to be increased significantly beyond what is now attainable. The PIs research program includes the following:o They propose to supply zone plates to one of the world's leading groups in ultrafast x-ray pulse generation: the lab of Margaret Murnane and Henry Kapetyn at the University of Colorado/JILA. This should enable the first exploration of nonlinear optics at x-ray wavelengths in a setting other than that of a thermonuclear weapon.o They propose to develop zone plates that should, for the first time, make sub-100 nm resolution imaging routinely available for 1-10 keV x-ray microscopes. Microscopes in this energy range are ideal for trace element mapping in biology and environmental science, and for inspection of defects in buried interconnects in integrated circuits.o They propose to carry out experimental tests aimed at future development of Bragg zone plates, where high aspect ratio zones must be angled to be on the Bragg condition to achieve high focusing efficiency and very high numerical aperture.o They propose to work with one of the leading groups in nanoimprint lithography (University of Texas at Austin) to combine our capabilities in fine linewidth zone plate fabrication with their technology for high throughput lithographic fabrication. The ultimate goal is to make a limited number of high resolution "master" zone plates, and use the UTA nanoimprint method to fabricate "disposable" high resolution zone plates. This could be a key technology for a high-risk, high-payoff scientific project: the use of x-ray free electron lasers to obtain atomic resolution maps of the structure of membrane proteins.