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A stacked prism lens concept for next-generation hard X-ray telescopes


Effective collecting area, angular resolution, field of view and energy response are fundamental attributes of X-ray telescopes. The performance of state-of-the-art telescopes is currently restricted by Wolter optics, especially for hard X-rays. Here we report the development of a stacked prism lens (SPL), which is lightweight and modular and has the potential for a significant improvement in effective area, while retaining high angular resolution. The proposed optics are built by stacking disks embedded with prismatic rings, created with photoresist by focused ultraviolet lithography. We demonstrate the SPL approach using a prototype lens that was manufactured and characterized at a synchrotron radiation facility. The design of a potential satellite-borne X-ray telescope is outlined and the performance is compared with contemporary missions.

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Fig. 1: Illustration of the proposed SPL.
Fig. 2: Main fabrication process steps of the disks for the SPL (not to scale).
Fig. 3: The fabricated disks and completed SPL.
Fig. 4: Experimental and simulated performance of the SPL.
Fig. 5: Implementation of a hard X-ray focusing telescope based on the SPL array.

Data availability

The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.


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We thank the KTH nanolab for access to the fabrication devices and support during fabrication. We acknowledge the Diamond Light Source for provision of synchrotron radiation facilities and express our thanks to O. Fox and K. Sawhney for assistance in applying and using beamline B16. We thank C. Xu and S. Karlsson for taking part in the experiment at the Diamond Light Source, C. Svensson for the detector design and power calculation and L. Mi for X-ray telescope concept drawing. W.M and M.D. acknowledge funding from Stiftelsen Olle Engkvist Byggmästare. M.P. acknowledges funding received from the Swedish Research Council (grant number 2016-04929).

Author information




W.M. performed the design, fabrication, test experiments and simulation of the stacked prism lens, analysed the experiment data and space application, and prepared the paper. P.N. contributed to the design of stacked prism lens and the development of the simulation programme, performed the X-ray experiments and discussed the experiment results. M.P. discussed and developed the space application of stacked prism lenses and assisted with the writing of the manuscript. M.D. managed the project, proposed applications for space and other areas and together with the co-authors coordinated the writing of the manuscript.

Corresponding author

Correspondence to Wujun Mi.

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The authors declare no competing interests.

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Peer review information: Nature Astronomy thanks Ralf Heilmann, Julia Vogel and the other anonymous reviewer(s) for their contribution to the peer review of this work.

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Supplementary Figs. 1–8.

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Mi, W., Nillius, P., Pearce, M. et al. A stacked prism lens concept for next-generation hard X-ray telescopes. Nat Astron 3, 867–872 (2019).

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