Point-spread function associated with underwater imaging through a wavy air-water interface: theory and laboratory...

Area of Science:

• Optics
• Fluid Dynamics
• Imaging Science

Background:

• Accurate imaging of underwater objects is crucial for various applications.
• Existing models often struggle with the complexities of light propagation through wavy water surfaces.
• The point-spread function (PSF) is essential for understanding image degradation.

Purpose of the Study:

• To theoretically derive and experimentally validate a point-spread function model for underwater imaging.
• To investigate the impact of a wavy water surface on image quality.
• To compare theoretical predictions with experimental results under different conditions.

Main Methods:

• Developed a theoretical model based on the emergent-ray model.
• Utilized Gram-Charlier series for non-Gaussian probability-density functions of emergent angles.
• Employed a finite-element methodology with emergent-ray angular probability distributions.
• Conducted experiments to validate the theoretical model.

Main Results:

• The derived point-spread function model shows good agreement with experimental results for downwind conditions.
• A slight deviation between the theoretical model and experimental data was observed for crosswind conditions.
• The deviation in crosswind conditions may be attributed to unmodeled standing wave interactions.

Conclusions:

• The emergent-ray model provides a robust theoretical framework for underwater imaging PSFs.
• The model's accuracy is demonstrated, particularly under downwind scenarios.
• Further refinement is needed to account for complex wave interactions in crosswind conditions.