arXiv subjects

Nazanin Samadi

Publications and source records attributed to Nazanin Samadi.

4 recordsLinked to original sources

arXiv2026

Free-form diamond refractive optics enable efficient high-energy X-ray nano-imaging

Full-field transmission X-ray microscopy (TXM) enables nondestructive three-dimensional imaging of thick and strongly absorbing materials with high spatial resolution. Such capabilities are essential for understanding structure-function relationships in hierarchical materials, with broad applications in biology, energy conversion, and energy storage. At high photon energies, however, TXM performance is limited by the reduced efficiency of diffractive optics and by the challenge of matching the numerical aperture (NA) of the illumination to that of the objective optics. Here we harness freeform diamond refractive optics to overcome a key illumination-efficiency bottleneck in high-energy TXM, demonstrating full-field nano-imaging at 20 keV with a half-period resolution of 72 nm. The optical system combines a custom-designed diamond refractive beam shaper that produces a uniform near-flat-top illumination at the sample with a 94% efficiency, a moving diffuser placed near the sample to increase the effective illumination NA and improve image quality and resolution, and high-precision aberration-corrected diamond compound refractive lenses as the objective optics. These results establish free-form diamond optics as a powerful route to efficient high-energy TXM, expanding full-field nano-imaging to complex, evolving materials systems and enabling in situ, operando, and tomographic studies under experimentally realistic conditions. Furthermore, it opens new avenues for innovation of joint X-ray optical-digital design for a new generation of high-energy X-ray nano-imaging.

physics.optics↗

arXiv2025

High-quality Blazed Gratings through Synergy between E-Beam lithography and Robust Characterisation Techniques

Maintaining the highest quality and output of photon science in the VUV-, EUV-, soft- and tender-X-ray energy ranges requires high-quality blazed profile gratings. Currently, their availability is critical due to technological challenges and limited manufacturing resources. In this work we discuss the opportunity of an alternative method to manufacture blazed gratings by means of electron-beam lithography (EBL). We investigate the different parameters influencing the optical performance of blazed profile gratings produced by EBL and develop a robust process for the manufacturing of high-quality blazed gratings using polymethyl methacrylate (PMMA) as high resolution, positive tone resist and ion beam etching.

physics.optics↗

arXiv2024

Design, fabrication, and testing of diamond axicons for X-ray microscopy applications

This work presents the design, fabrication, and experimental validation of a refractive diamond axicon for X-ray beam shaping. The diamond axicon was developed to overcome the limitations of polymer-based axicons particularly for application in Transmission X-ray Microscopy (TXM) systems, offering superior mechanical strength, thermal stability, and radiation resistance, making it ideal for synchrotron applications. The axicon was fabricated using femtosecond laser ablation and tested at 11 keV under various coherence conditions. Results demonstrated that the axicon efficiently transformed the X-ray beam into a ring-shaped profile with over 80% transmission. Simulations confirmed the experimental findings and highlighted the potential for further improvements. This work paves the way for the use of diamond axicons in next-generation synchrotron facilities, with future efforts focusing on optimizing fabrication and testing the axicon in full TXM systems.

physics.optics↗

arXiv2020

Focusing and Energy Dispersion Properties of a Cylindrically Bent Asymmetric Laue Crystal

Elastically bent single-crystal Laue case diffraction crystals provide interesting new opportunities for imaging and spectroscopy applications. The diffraction properties are well understood, however, the ability to easily model the diffracted beams hinders assessment of the focal, phase and energy dispersive properties needed for many applications. This work begins to collect the elements needed to ray trace diffracted beams within bent Laue crystals for the purpose of incorporation into other powerful ray tracing applications such as SHADOW. Specifically, we address the condition in a bent Laue crystal where a cylindrically bent Laue crystal will focus all the polychromatic diffracted beams at a single location when a specific asymmetry angle condition is met for a target x-ray energy - the so-called "magic condition". The focal size of the beam can be minimized, but this condition also results in excellent energy-dispersive properties. The conceptual and mathematical aspects of this interesting focusing and energy dispersive phenomenon is discussed.

physics.optics↗