Compact dual-channel integral-field snapshot underwater hyperspectral imager

In contrast to push-broom hyperspectral imagers, the snapshot approach substantially reduces sensitivity to platform motion and vibration, which constitutes a crucial advantage for underwater mobile deployment. Here, we present the design and development of a compact, integral-field snapshot underwater hyperspectral imager. The system comprises a relay panchromatic imaging channel with high spatial resolution and a spectral imaging channel with lower spatial resolution. By fusing high-resolution panchromatic images with low-resolution spectral images, we obtain hyperspectral images with a enhanced spatial resolution. Both the panchromatic imaging channel and the spectral imaging channel share a common front objective, which features a focal length of 16 mm and a field of view of 38^∘×29^∘. By leveraging prism dispersion, the spectral imaging system covers a wavelength range from 450 to 1000 nm with a spectral resolution of better than 6 nm at 532 nm. By introducing a relay imaging system into the panchromatic channel, we reduce the back focal distance of the front objective lens while simultaneously shortening the overall length of the spectral imaging system. This addresses a key limitation of existing dual-channel snapshot underwater hyperspectral imaging systems-namely, their excessive length, which hinders integration with underwater vehicles. Compared with conventional dual-channel systems, the proposed design achieves a reduction in length of 182 mm, resulting in compact dimensions of 145 mm in diameter and 452 mm in length, thereby facilitating integration onto underwater vehicle platforms. In addition, a spectral-guided spatial-spectral fusion framework is specifically developed for the dual-channel configuration. The proposed method separately encodes spectral and spatial features and integrates them through multi-scale alignment and progressive reconstruction to handle the large resolution gap between channels while preserving spectral fidelity. Experimental results obtained across diverse scenes demonstrate the system's superior spectral imaging performance, thereby establishing it as a robust solution for underwater snapshot hyperspectral imaging.