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.
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.
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.
Read more on the Diamond website
Image: (L-R) Hongchang Wang , Murilo Bazan Da Silva, Wai Jue Tan, Arindam Majhi, Riley Shurvinton, Wadwan Singhapong, Paresh Pradhan and Kawal Sawhney
Credit: Diamond Light Source