Underwater Hyperspectral Imaging System with Liquid Lenses

Abstract

The underwater hyperspectral imager enables the detection and identification of targets on the seafloor by collecting high-resolution spectral images. The distance between the hyperspectral imager and the targets cannot be consistent in real operation by factors such as motion and fluctuating terrain, resulting in unfocused images and negative effects on the identification. In this paper, we developed a novel integrated underwater hyperspectral imaging system for deep sea surveys and proposed an autofocus strategy based on liquid lens focusing transfer. The calibration tests provided a clear focus result for hyperspectral transects and a global spectral resolution of less than 7 nm in spectral range from 400 to 800 nm. The prototype was used to obtain spectrum and image information of manganese nodules and four other rocks in a laboratory environment. The classification of the five kinds of minerals was successfully realized by using a support vector machine. We tested the UHI prototype in the deep sea and observed a Psychropotidae specimen on the sediment from the in situ hyperspectral images. The results show that the prototype developed here can accurately and stably obtain hyperspectral data and has potential applications for in situ deep-sea exploration.

Detection of manganese nodule ore based on underwater hyperspectral imaging technology

“…In this study, we employed an independently developed underwater hyperspectral imaging system, designed for deepsea exploration [12] . The system is encased in a titanium alloy pressure shell, capable of operating at depths up to 6000…”

Closed-loop wavefront calibration of a multi-electrode electrowetting-based tunable microlens

“…From simple, focus-tunable lenses, 1 the technology has advanced to produce lenses with tunable asphericity, 2 lenses with integrated tunable apertures, 3 or cylindrical lenses. 4 Recent applications of such devices include underwater hyperspectral imaging, 5 depth estimation 6 and continuous zoom systems. 7 Especially interesting are designs with a large number of electrodes because they offer a greater degree of shape control, enabling generation of astigmatic or higher-order surfaces.…”