Underwater ghost imaging with detection distance up to 9.3 attenuation lengths

Area of Science:

• Optics and Photonics
• Oceanography
• Remote Sensing

Background:

• Underwater detection is crucial for various applications.
• Traditional LiDAR methods face challenges in turbid water environments.
• Ghost imaging offers a unique approach to underwater sensing.

Purpose of the Study:

• To develop and validate a theoretical model for underwater ghost imaging.
• To investigate the impact of water optical parameters on ghost imaging performance.
• To experimentally determine the maximum detection distances for different target types.

Main Methods:

• Developed an underwater optical transmission model incorporating Wells and Sahu-Shanmugam models.
• Utilized the second-order Glauber function to analyze scattering effects.
• Conducted experiments using a gated photomultiplier tube (PMT) and a 532 nm laser.
• Tested imaging of high-reflective and diffuse-reflection targets at varying distances.

Main Results:

• The proposed model accurately reflects the degrading effects of water on ghost imaging.
• High-reflective targets were imaged up to 65.2 m (9.3 attenuation lengths).
• Diffuse-reflection targets were imaged up to 41.2 m (6.4 attenuation lengths).
• The system achieved a maximum detection distance equivalent to 193.7 m in Jerlov-I water.

Conclusions:

• The developed underwater ghost imaging model enhances detection capabilities.
• Gated PMT effectively filters backscattering for extended range detection.
• The research provides a foundation for improved underwater optical imaging systems.