Imaging through highly scattering environments using ballistic and quasi-ballistic light in a common-path Sagnac...

Area of Science:

• Optics and Photonics
• Complex Media Physics

Background:

• Time-reversal symmetry is crucial for interference effects in scattering media.
• Strong multiple scattering poses challenges for traditional imaging techniques.

Purpose of the Study:

• To investigate the use of time-reversed light paths for imaging in highly scattering environments.
• To develop a robust method for detecting objects behind scattering materials.

Main Methods:

• Construction of a common-path Sagnac interferometer.
• Utilizing a spatial offset between light paths to isolate specific scattering contributions.
• Analyzing frequency dependence of coherent modulation signals.

Main Results:

• Detection of objects behind up to 14 mean free paths of scattering material.
• Suppression of non-specific scattering using spatial path overlap.
• Observation of a transition from ballistic to quasi-ballistic light transport with increased scattering thickness.

Conclusions:

• Common-path, bistatic interferometry offers a novel approach for imaging in complex media.
• The technique enables short-range 3D imaging and has potential applications in medical imaging, machine vision, sensors, and lidar.