Handheld snapshot multi-spectral camera at tens-of-megapixel resolution.

Multi-spectral imaging is a fundamental tool characterizing the constituent energy of scene radiation. However, current multi-spectral video cameras cannot scale up beyond megapixel resolution due to optical constraints and the complexity of the reconstruction algorithms. To circumvent the above issues, we propose a tens-of-megapixel handheld multi-spectral videography approach (THETA), with a proof-of-concept camera achieving 65-megapixel videography of 12 wavebands within visible light range. The high performance is brought by multiple designs: We propose an imaging scheme to fabricate a thin mask for encoding spatio-spectral data using a conventional film camera. Afterwards, a fiber optic plate is introduced for building a compact prototype supporting pixel-wise encoding with a large space-bandwidth product. Finally, a deep-network-based algorithm is adopted for large-scale multi-spectral data decoding, with the coding pattern specially designed to facilitate efficient coarse-to-fine model training. Experimentally, we demonstrate THETA's advantageous and wide applications in outdoor imaging of large macroscopic scenes.

Retrieving Object Motions From Coded Shutter Snapshot in Dark Environment.

Video object detection is a widely studied topic and has made significant progress in the past decades. However, the feature extraction and calculations in existing video object detectors demand decent imaging quality and avoidance of severe motion blur. Under extremely dark scenarios, due to limited sensor sensitivity, we have to trade off signal-to-noise ratio for motion blur compensation or vice versa, and thus suffer from performance deterioration. To address this issue, we propose to temporally multiplex a frame sequence into one snapshot and extract the cues characterizing object motion for trajectory retrieval. For effective encoding, we build a prototype for encoded capture by mounting a highly compatible programmable shutter. Correspondingly, in terms of decoding, we design an end-to-end deep network called detection from coded snapshot (DECENT) to retrieve sequential bounding boxes from the coded blurry measurements of dynamic scenes. For effective network learning, we generate quasi-real data by incorporating physically-driven noise into the temporally coded imaging model, which circumvents the unavailability of training data and with high generalization ability on real dark videos. The approach offers multiple advantages, including low bandwidth, low cost, compact setup, and high accuracy. The effectiveness of the proposed approach is experimentally validated under low illumination vision and provide a feasible way for night surveillance.

Controlled design of Na-P1 zeolite/ porous carbon composites from coal gasification fine slag for high-performance adsorbent.

Low-cost and concentrated industrial wastes have been recognized as a sustainable resource for preparation of new functional materials. Here, a new method was designed for the synthesis of porous composites containing high-purity Na-P1 zeolite and porous carbon from waste coal gasification fine slag (CGFS), which was treated first by acid leaching to controllably remove metal impurities and adjust Si/Al ratio, followed by NaOH fusion and hydrothermal treatment. By leaching with 1.0 mol/L HCl solution, the Si/Al ratio of the raw CGFS increased to 5.7, and the obtained CZ-1.0 consisted of high-purity Na-P1 zeolite with a typical cone-shaped flower cluster shape. The residue carbon in CGFS can be further activated to form porous carbon and graphite carbon layers interposed in the zeolite structure. The specific surface area and pore volume of CZ-1.0 reached 153.91 m2/g and 0.18 cm3/g, respectively. CZ-1.0 exhibited remarkable adsorption performance for methylene blue (MB) with the adsorption capacity reaching 137.5 mg/g for 100 mg/L MB solution. The adsorption process is mainly controlled by the chemisorption mechanism, and the adsorption of MB by CZ-1.0 may include ion exchange, hydrogen bond interaction, π-π bond interaction and van der Waals force. NaCl solution was successfully used as the desorption agent to regenerate the composite material, and the removal rate remained above 92% after five cycles. This work provides an effective strategy to synthesize a practically applicable adsorbent from the waste coal gasification fine slag for the purification of MB wastewater.