SIOM Achieves First Absolute Wavefront Measurement of an EUV Light Source

Excellence in Ultra-Intense Laser Science Briefing

(Issue 823)

September 15, 2026

SIOM Makes Progress in Photon-Sieve EUVAbsolute Wavefront Measurement

Recently, a research team from the Joint Laboratory for High-Power Laser Physics at the Shanghai Institute of Optics and Fine Mechanics (SIOM), Chinese Academy of Sciences, in collaboration with a team from Harbin Institute of Technology, achieved for the first timeEUVabsolute wavefront measurement of an EUV source, addressing the challenge of absolute wavefront measurement for extreme ultraviolet andsoftx-ray sources. The related findings were published inOptics and Lasersin Engineering under the title “Single-shot absolute wavefront sensing with a freestanding photon-sieve splitter in extreme ultraviolet”.

The lack of functional devices in theEUV and softx-ray bands has become one of the bottlenecks limiting the development of short-wavelength measurement. The recent advent of the anisotropic self-splitting photon sieve (Optica, 12, 1388, 2025) offers short-wavelength devices an alternative to zone plates, meeting the technical requirements of short-wavelength wavefront measurement.

Hollowed-out photon sieves open a viable route to absolute wavefront measurement forEUV and softx-ray sources (Single-shot radial shearing interferometric wavefront sensing based on an ultra-large-aperture Archimedes' ladder-film photon sieve, invited paper, Chinese Journal of Lasers,2024). The joint team first designed a beam-splitting photon sieve, whose first-layer single focus lies at the projection center of the second-layer double foci, and then proposed the Airy spot interchange phase diversity wavefront measurement technique (AiPD), converting the small-defocus phase constraint of conventional phase diversity into large-scale Airy spot phase constraints at different coordinates, reducing the experimental difficulty at short wavelengths. In the experiment, a46.9nm laser illuminated the photon sieve, and multi-frame diffraction fields were recorded by photoresist, then read out with an atomic force microscope, and finally the phase distribution of the EUV source was successfully obtained by least-squares optimization. The experimental results agree with those of conventional phase diversity measurements and geometrical optics analysis.EUV and softx-ray absolute wavefront measurement provides strong support for precision control of structured light fields from short-wavelength sources, and supplies accurate wavefront information for high-end applications such as short-wavelength structured lithography, in vivo imaging of living biological cells in the water window, laser plasma x-ray diagnostics and coherent diffraction imaging.

This work was supported by the National Natural Science of China and the Strategic Priority Research Program of the Chinese Academy of Sciences (CategoryA), among other projects.

Original article link

Figure1 EUV AiPDwavefront measurement optical setup schematic

Figure2 EUV AiPDexperimental results (a,b,e,f) diffraction patterns, Zernike-fitted wavefronts (c,g), with the defocus term removed (d,h)