Independent Research

Wavefront sensing is essential for characterizing optical aberrations, yet conventional approaches often require complex optical arrangements. My research introduces a novel interferometric wavefront-sensing framework based on counter-accelerating Airy beams generated through engineered cubic phase modulation. As these beams propagate and interfere, their intensity patterns encode information about the incident wavefront, enabling computational reconstruction of optical phase and aberrations. Numerical simulations demonstrate highly accurate wavefront recovery, including in the presence of measurement noise. By eliminating the need for collection optics, this approach offers a promising pathway toward compact wavefront sensors for applications in optical metrology, electron microscopy, and emerging imaging systems.

Selected publication: S. Kamal, Theory of Airy-Beam Wavefront Sensing, submitted to Optics Letters (2026). Read preprint 

Contributions

My research focuses on developing computational and wave-optical methods to model, characterize, and improve scanning electron microscopy (SEM). A foundational contribution of this work is SEM Nano, an open-source electron wave-optical simulation framework developed to model electron beam propagation through the microscope column, from source to specimen. Building on this foundation, my research explores defocus-based phase retrieval to reconstruct electron-probe characteristics and recover the point-spread function, enabling quantitative assessment of electron-optical performance and aberrations. Complementary investigations examine detector noise and computational approaches to its characterization. Together, these contributions provide a physics-based computational framework for understanding electron-optical systems and advancing quantitative electron microscopy.

Selected Publications

1. S. Kamal, K. Nyaburi, and R. Hailstone, "Optical Point-Spread Function via Defocus Phase Retrieval in Scanning Electron Microscopy," Micron, 2026. DOI

2. S. Kamal, Y. Zhou, and Z. Gong, "Wave Optical Modeling of the SEM Column from Source to Specimen," Microscopy and Microanalysis, 2024. DOI

3. S. Kamal and R. Hailstone, "SEM Nano: An Electron Wave Optical Simulation for the Scanning Electron Microscope," Microscopy and Microanalysis, 2022. DOI

Open-source research software: SEM Nano | SEM Optics

Collaborative Research

My research in integrated photonics combines optical design, wave-optical modeling, and computational field reconstruction to improve optical interfaces in photonic integrated circuits (PICs). In collaboration with Prof. Stefan Preble, this work includes the development of a physics-guided methodology for designing and fabricating 3D-printed micro-optics for efficient optical coupling. A complementary research direction focuses on developing computational models to characterize light propagation, reflection, and interference through waveguide–microlens interfaces, with numerical comparisons against FDTD simulations. Another direction explores lensless computational imaging to reconstruct complex waveguide-facet fields from defocused intensity measurements. These ongoing investigations have produced promising numerical results and form the basis of two upcoming CLEO conference submissions and a planned journal submission.