The broad research fields of microscopy and computational imaging actively seek higher resolution, better quality, faster acquisition, versatile and easy-to-operate instrumentation to accommodate as many scientific applications as possible. Ptychography is one of the computational microscopy techniques based on diffraction imaging principles, where algorithms are used to reconstruct a high-fidelity image of the sample without the use of magnifying lenses. While powerful, ptychography’s effectiveness can, however, be limited by the characteristics of the probing light, particularly in the case of samples exhibiting a high degree of symmetry.
In this study, researchers at the DiProi beamline explored the use of Extreme Ultraviolet light carrying Orbital Angular Momentum (OAM), often referred to as “twisted light” to enhance ptychographic imaging resolution. Unlike conventional (Gaussian) beams, OAM light has a helical phase structure, which combined with the structured illumination of the beam profile, allows for a selective amplification of high-frequency spatial component in the diffraction process. The net effect is an increase in the amount of information (spatial resolution) that can be captured about the sample.
The experiments were conducted using the FERMI seeded free-electron laser (FEL) source, which provides a highly coherent and intense beam of light. By pairing state-of-the-art ptychography reconstruction algorithms designed by the Scientific Computing Team with the high-quality characteristics of the source, the researchers were able to reliably use the OAM beam to improve the spatial resolution of the reconstructed images.
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