Defocus based phase retrieval of the electron probe wave function using focal series of probe intensities in SEM.
All functions and code are annotated and commented well and are clear to understand when read with the main paper. It takes a decent computational capability to run this program quickly.
main_code.m - Run this code to execute the program
ASM_propagation.m - Propagation function based on the angular spectrum method
defocus_phase_retrieval.m - Automated function to perform iterative phase retrieval based on defocus variation
defocus_phase_retrieval_hard.m - Hard-coded function to perform iterative phase retrieval based on defocus variation
volt2wavelen.m - Function to calculate the relativistic wavelength from accelerating
psf_visualization.m - Function to visualize the PSF of SEM Optics based on recovered probe wavefunction
z_sampling.mat - z-locations (mm) of the specimen plane in the focal series
probe_intensity_focal_series - Folder containing probe intensity images named (0_PSF.png, +-1.png, ...), although they are named as PSF.png, but they are not to be confused with PSF of the SEM Optics, they are just probe intensity.
IMPORTANT DISTINCTION: The probe intensity is loosely referred to as the PSF of SEM in SEM literature (inaccurate). We are visualizing the PSF of "SEM Optics - the lens system", which is a mathematically defined quantity.
Main work: Kamal, S., & Hailstone, R. K. (2024). Point-Spread Function of the Optics in Scanning Electron Microscopes. arXiv preprint arXiv:2407.01439. http://dx.doi.org/10.48550/arXiv.2407.01439
Probe intensity reconstruction: Zotta, M. D., Nevins, M. C., Hailstone, R. K., & Lifshin, E. (2018). The Determination and Application of the Point Spread Function in the Scanning Electron Microscope. Microscopy and microanalysis: the official journal of Microscopy Society of America, Microbeam Analysis Society, Microscopical Society of Canada, 24(4), 396–405. https://doi.org/10.1017/S1431927618012412
Phase retrieval algorithm: Allen, L. J., & Oxley, M. P. (2001). Phase retrieval from series of images obtained by defocus variation. Optics communications, 199(1-4), 65-75.
If you have any questions or suggestions about the program, please email: surya.kamal@rit.edu