Temporal and spectral multiplexing for EUV multibeam ptychography with a high harmonic light source

Initial probe function construction in ptychography based on zone-plate optics

X-ray ptychography is a popular variant of coherent diffraction imaging that offers ultrahigh resolution for extended samples. In x-ray ptychography instruments, the Fresnel zone-plate (FZP) is the most commonly used optical probe system for both soft x-ray and hard x-ray. In FZP-based ptychography with a highly curved defocus probe wavefront, the reconstructed image quality can be significantly impacted by the initial probe function form, necessitating the construction of a suitable initial probe for successful reconstruction. To investigate the effects of initial probe forms on FZP-based ptychography reconstruction, we constructed four single-mode initial probe models (IPMs) and three multi-mode IPMs in this study, and systematically compared their corresponding simulated and experimental reconstructions. The results show that the Fresnel IPM, spherical IPM, and Fresnel-based multi-mode IPMs can result in successful reconstructions for both near-focus and defocus cases, while random IPMs and constant IPMs work only for near-focus cases. Consequently, for FZP-based ptychography, the elaborately constructed IPMs that closely resemble real probes in wavefront phase form are more advantageous than natural IPMs such as the random or constant model. Furthermore, these IPMs with high phase similarity to the high-curvature large-sized probe adopted in experiments can help greatly improve ptychography experiment efficiency and decrease radiation damage to samples.

High-speed and wide-field nanoscale table-top ptychographic EUV imaging and beam characterization with a sCMOS detector

We present high-speed and wide-field EUV ptychography at 13.5 nm wavelength using a table-top high-order harmonic source. Compared to previous measurements, the total measurement time is significantly reduced by up to a factor of five by employing a scientific complementary metal oxide semiconductor (sCMOS) detector that is combined with an optimized multilayer mirror configuration. The fast frame rate of the sCMOS detector enables wide-field imaging with a field of view of 100 µm × 100 µm with an imaging speed of 4.6 Mpix/h. Furthermore, fast EUV wavefront characterization is employed using a combination of the sCMOS detector with orthogonal probe relaxation.