Hyperspectral cameras face harsh trade-offs between spatial, spectral, and temporal resolution in inherently low-photon conditions. Computational imaging systems break through these trade-offs with compressive sensing, but have required complex optics and/or extensive compute. We present Spectrum from Defocus (SfD), a chromatic focal sweep method that achieves state-of-the-art hyperspectral imaging with only two off-the-shelf lenses, a grayscale sensor, and less than one second of reconstruction time. By capturing a chromatically-aberrated focal stack that preserves nearly all incident light, and reconstructing it with a fast physics-based iterative algorithm, SfD delivers sharp, accurate hyperspectral images. The combination of photon efficiency, optical simplicity, and physical interpretability makes SfD a promising solution for fast, compact, interpretable hyperspectral imaging.
@article{arxiv.2503.20184,
title = {Spectrum from Defocus: Fast Spectral Imaging with Chromatic Focal Stack},
author = {M. Kerem Aydin and Yi-Chun Hung and Jaclyn Pytlarz and Qi Guo and Emma Alexander},
journal= {arXiv preprint arXiv:2503.20184},
year = {2026}
}