Toward all-in-focus lensless imaging with full-aperture radial masks

We propose a lensless imaging system based on a full-aperture radial coded mask that produces a nearly depth-invariant point spread function (PSF), paving the way towards all-in-focus image reconstruction from a single PSF calibration. In contrast to conventional lens-based systems-where defocus blur is directly observed-lensless cameras rely on computational reconstruction using a calibrated PSF, making image quality highly sensitive to PSF mismatch. Our radial mask design ensures more consistent PSF structure across a wide depth range, mitigating this sensitivity and enabling captures that are less sensitive to depth variation. We validate the depth invariance of the proposed mask through experimental PSF analysis, demonstrating high correlation between PSFs captured at depths from 1 cm to 10 cm. We further evaluate the system through simulations and prototype experiments, showing improved robustness to depth mismatch when compared to conventional restricted-aperture masks. Finally, we introduce what we believe to be a novel shift-invariant reconstruction approach using an artificially extended PSF, enabled by the scale-invariant geometry of the radial pattern. This approximation allows for efficient and high-quality deconvolution across continuous depth ranges, demonstrating the practical feasibility of full-aperture lensless imaging.