First demonstration of stripe-free multilayer monochromator imaging
Dec 29, 2025
Diamond Light Source scientists have achieved a long-sought breakthrough in X-ray optics - the first demonstration of stripe-free X-ray imaging using multilayer (ML) monochromators. The results, published in Advanced Optical Materials and Optics Express, show how advanced fabrication and coating techniques can completely remove the stripe artefacts that have long limited the image quality from ML optics.
- (L-R) Hongchang Wang , Murilo Bazan Da Silva, Wai Jue Tan, Arindam Majhi, Riley Shurvinton, Wadwan Singhapong, Paresh Pradhan and Kawal Sawhney
ML monochromators are essential for high-flux X-ray imaging, diffraction, and spectroscopy. They offer up to 100 times higher photon flux than crystal monochromators, but at a cost; faint, stripe-like intensity variations in the beam caused by tiny figure errors in the optical surface. These “stripe artefacts” reduce image clarity and complicate analysis, especially in demanding applications like tomography. Until now, eliminating these artefacts has proved extremely difficult.
- (Top) Leaf sample imaged using a commercial multilayer monochromator. (Bottom) Same sample imaged with an in-house multilayer monochromator developed by using IBF technique.
The Diamond team tackled the root cause: the optical curvature error. Using state-of-the-art, in-housed developed ion beam figuring (IBF) in the Optics Fabrication Facility, they produced multilayer monochromator substrates with record-breaking slope errors below 30 nanoradians root mean square (rms) - equivalent to flattening a surface to atomic-level precision without degrading microroughness. These substrates were then coated in Diamond’s Multilayer Deposition System, achieving exceptional layer thickness uniformity of 0.1% along the mirror length. Reflectivity matched design targets to within 0.01 nm in layer spacing, ensuring perfect optical performance.
By pushing the limits of optical fabrication and coating precision, we’ve eliminated the major drawback of multilayer monochromators. This opens new possibilities for high quality X-ray imaging across many beamlines.
Dr Hongchang Wang, Principal Optics Scientist and corresponding author of the study
The new monochromators were tested at the B16 Test Beamline using at-wavelength speckle-based metrology. Measurements confirmed slope errors below 30 nrad after coating, and the wavefront curvature uniformity matching theoretical predictions. Importantly, the flat-field beam intensity with no visible stripes.
The Diamond Optics Fabrication Facility has enabled the production of specialised, high-quality X-ray optics that will play a key role in the planned upgrade to the low-emittance Diamond-II source. The B16 Test Beamline also provides a unique platform for developing and validating new techniques and optics, ensuring they are ready for the next generation of synchrotron science.
Co-author Dr Kawal Sawhney, Principal Beamline Scientist and Optics and Metrology group leader
- Schematic of the ion beam figuring (IBF) system used in this work.
- Photograph of the sample holder in the multilayer deposition system.
This achievement marks the first time multilayer monochromators have matched the far-field uniformity of crystal monochromators while retaining their superior photon flux. It has direct benefits for tomography, high-speed imaging, advanced material and biomedical studies by providing enhanced contrast and clarity. The achievement of stripe-free imaging marks a breakthrough for multilayer monochromators. This result sets a new benchmark for far-field beam uniformity and will guide the future design and specification of ML monochromators for a wide range of scientific applications.
Related publications
Singhapong W, Majhi A, Tan WJ, Dhamgaye V, Shurvinton R, Pradhan P, et al. Development of High-Performance Multilayer Monochromators. Adv Optical Mater 2025, e01312.
Shurvinton R, Pradhan P, Da Silva MB, Singhapong W, Tan WJ, Majhi A, et al. Development of multilayer monochromators for stripe-free X-ray imaging. Opt. Express 2025, 33(16): 34814-34829.
Diamond Light Source is the UK's national synchrotron science facility, located at the Harwell Science and Innovation Campus in Oxfordshire.
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