Surya Kamal | Search arXiv

arXiv2026

Theory of Airy-Beam Wavefront Sensing

A new wavefront sensing framework based on the interference of counter-accelerating Airy beams is presented. An engineered cubic phase function transforms a single Gaussian beam into two coherent Airy beams with opposite transverse accelerations, which self-recombine during free-space propagation to form an interference pattern encoding the aberrated incident wavefront. Numerical simulations demonstrate accurate recovery of the aberrated exit-pupil phase across the aberration sets considered, with a root-mean-square phase reconstruction error below $10^{-6} \mathrm{\;rad}$ for the aberration set shown and consistently low errors for the other sets, while maintaining accurate recovery in the presence of measurement noise. The approach eliminates collection optics and enables a compact wavefront-sensing architecture for applications where conventional interferometric systems are difficult to implement, including electron-optical systems, augmented and virtual reality systems.

physics.optics↗

arXiv2026

Optical Point-Spread Function via Defocus Phase Retrieval in Scanning Electron Microscopy

The point-spread function of the probe-forming optics ($PSF_{optics}$) is reported in an uncorrected (without multipole correctors) scanning electron microscope (SEM). In an SEM, information about the electron probe is generally lost as the beam interacts with the specimen. Here, we demonstrate an approach for recovering probe phase information from reconstructed probe intensity estimates. Controlled defocus was used to acquire a focal series of SEM images of $28.5,nm$ gold ($\mathrm{Au}$) nanoparticles ($\mathrm{NPs}$) on a carbon ($\mathrm{C}$) film. These images were used to reconstruct their respective probe intensities, generating a focal series of probe intensities that served as input to the phase retrieval pipeline. Using the complete description (intensity and phase) of the electron probe wavefunction at the specimen plane, we estimate the $PSF_{optics}$ for multiple data sets at a beam energy of $E = 20,keV$. These results represent an important step in demonstrating the possibility of experimental aberration quantification in uncorrected SEMs.

cond-mat.mtrl-sci↗