- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Underwater Wide-Area Layered Light Field for Underwater Detection
摘要： In underwater electro-optic detection, image quality can be degraded by the backscattering of light from the illuminated water volume. In practical systems, we tend to simultaneously require a high level of detection distance (DD), ?eld of view (FOV), and depth of ?eld (DOF), but these factors in?uence each other by the media scattering. To eliminate this restriction, we propose to explore the underwater wide-area layered light ?eld (UWLLF), which classi?es the underwater detection area by the DD and distribution characteristics of the light ?eld, to minimize the scattering in?uence on target detection. Based on the UWLLF, an underwater electro-optic detection system is designed that can achieve the speci?cations of a 70? FOV and 7.9-fold attenuation length (for the attenuation coef?cient 1.43 /m of 532 nm) DD. In addition, with the spatial separation of light energy, the non-detection zone at short ranges is eliminated, yielding an almost full DOF. With these three factors simultaneously improved, the ability of underwater exploration for object detection is enhanced.
关键词： object detection,Underwater technology,light ?eld,optical imaging,underwater detection
更新于2025-09-09 09:28:46
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Low-Cost Submersible Turbidity Sensors Using Low-Frequency Source Light Modulation
摘要： Submersible turbidimeter and fluorometer design generally involves tradeoffs between ambient light rejection, sensitivity, and cost. We introduce an optical backscatter transducer in which the light source is modulated with a low-frequency (tens of Hz) square wave, with a detection scheme that mitigates the effects of external interference from ambient light and from 50- and 60-Hz sources. With this design, high-pass filtering and subsequent amplification enable sensitive measurements using inexpensive circuitry. Additional accuracy-enhancing features include: a rail-splitting virtual ground, which eliminates the potential for clipping at low signal levels; a reference output, which provides correction for the intensity of the internal light source; and error-tracking provisions, which flag the output if circuit voltages reach saturation limits during measurement. We have designed, constructed, and evaluated submersible turbidimeters which incorporate this transducer. These sensors were inexpensive to fabricate (U.S. $70 of materials and 4 h of labor) and were proof tested to 7 atm of water pressure. They responded linearly and reproducibly to formazin turbidity standard, with negligible inherent offset. A calibrated sensor exhibited bias ≤0.11 NTU in suspensions ranging from 0 to 8 NTU. A similar sensor with reduced circuit gain exhibited a one-to-one response to increasing turbidity in suspensions ranging from 0 to 815 NTU.
关键词： water quality,underwater technology,nephelometer,turbidimeter,fluorometer,fluorescence,optical backscatter,Environmental monitoring,turbidity sensor
更新于2025-09-09 09:28:46