arXiv subjects

Syed Muhammad Kazim

Publications and source records attributed to Syed Muhammad Kazim.

4 recordsLinked to original sources

arXiv2025

Performance Validation of Coded Wavefront Sensing for Quantitative Phase Imaging of Static and Dynamic Specimens Using Digital Holographic Microscopy

Coded wavefront sensing (Coded-WFS) is a snapshot quantitative phase imaging (QPI) technique that has been shown to successfully leverage the memory effect to retrieve the phase of biological specimens. In this paper, we perform QPI on static silica beads and dynamic HEK cells using Coded-WFS. The accuracy of the retrieved phase map is validated using digital holographic microscopy (DHM) for the same specimens. We report comparisons of simultaneous bright-field intensity and optical path delay.

physics.optics↗

arXiv2025

Direct Image Classification from Fourier Ptychographic Microscopy Measurements without Reconstruction

The computational imaging technique of Fourier Ptychographic Microscopy (FPM) enables high-resolution imaging with a wide field of view and can serve as an extremely valuable tool, e.g. in the classification of cells in medical applications. However, reconstructing a high-resolution image from tens or even hundreds of measurements is computationally expensive, particularly for a wide field of view. Therefore, in this paper, we investigate the idea of classifying the image content in the FPM measurements directly without performing a reconstruction step first. We show that Convolutional Neural Networks (CNN) can extract meaningful information from measurement sequences, significantly outperforming the classification on a single band-limited image (up to 12 %) while being significantly more efficient than a reconstruction of a high-resolution image. Furthermore, we demonstrate that a learned multiplexing of several raw measurements allows maintaining the classification accuracy while reducing the amount of data (and consequently also the acquisition time) significantly.

eess.IV↗

arXiv2024

Vignetting Effects: a Tool to Characterize a Fourier Ptychographic Microscope

Fourier Ptychographic Microscopy (FPM) is a recent technique to overcome the diffraction limit of a low numerical aperture (NA) objective lens by algorithmic post-processing of several lower resolved images. It can increase the space-bandwidth product of an optical system by computationally combining images captured under different illumination conditions. Vignetting determines the spatial extent of the bright field and dark field regions in the captured images that contain information about low and high frequency image content, respectively. State-of-the-art analyses treat vignetting as a nuisance that needs to be reduced or excluded from algorithmic consideration by means of ad-hoc decision rules [1]. In contrast, this work investigates vignetting effects as a tool to infer a range of properties of the optical system. To achieve this, we characterize the individual system components of the experimental setup and compare experimental data to both, geometrical and wave optical simulations. We demonstrate that using vignetting as an analytical tool enables the modeling of the geometric and coherence properties of the optical system as evidenced by the good agreement between our simulation and experiment. Moreover, our work investigates pupil aberrations in the FPM setup and enables their partial characterization, despite not yet encompassing all aspects.

physics.optics↗

arXiv2021

Adaptive quantum state tomography with iterative particle filtering

Several Bayesian estimation based heuristics have been developed to perform quantum state tomography (QST). Their ability to quantify uncertainties using region estimators and include a priori knowledge of the experimentalists makes this family of methods an attractive choice for QST. However, specialized techniques for pure states do not work well for mixed states and vice versa. In this paper, we present an adaptive particle filter (PF) based QST protocol which improves the scaling of fidelity compared to nonadaptive Bayesian schemes for arbitrary multi-qubit states. This is due to the protocol's unabating perseverance to find the states's diagonal bases and more systematic handling of enduring problems in popular PF methods relating to the subjectivity of informative priors and the invalidity of particles produced by resamplers. Numerical examples and implementation on IBM quantum devices demonstrate improved performance for arbitrary quantum states and the application readiness of our proposed scheme.

quant-ph↗