Determining the phase and amplitude distortion of a wavefront using a plenoptic sensor

Area of Science:

• Optical Engineering
• Wavefront Sensing
• Atmospheric Optics

Background:

• Phase reconstruction in optical systems is often limited to a narrow range (-π,π).
• Conventional Shack-Hartmann sensors can suffer from ambiguities like branch points and cuts.
• Existing methods struggle with accurate phase and amplitude retrieval through turbulent media.

Purpose of the Study:

• To develop a plenoptic sensor for retrieving continuous phase and amplitude changes of laser beams propagating through atmospheric turbulence.
• To overcome the limitations of existing phase reconstruction techniques.
• To provide a more robust method for wavefront sensing in turbulent environments.

Main Methods:

• Designed a plenoptic sensor by modifying a light field camera into a mini Keplerian telescope array.
• Cascaded the object lens's back focal plane with a microlens array's front focal plane, matching numerical apertures.
• Utilized reconstruction algorithms to analyze complex amplitude distribution across a matrix of images.

Main Results:

• Achieved continuous phase reconstruction beyond the typical (-π,π) range.
• Demonstrated reduced likelihood of ambiguities such as branch points and cuts compared to Shack-Hartmann sensors.
• Successfully reconstructed wavefronts and phase screens equivalent to atmospheric turbulence distortions.

Conclusions:

• The developed plenoptic sensor offers superior phase and amplitude retrieval capabilities for laser beams in turbulent conditions.
• The sensor design and reconstruction algorithms provide a more robust and accurate alternative to conventional wavefront sensing methods.
• The reconstructed data can effectively guide adaptive optics systems for beam control in atmospheric turbulence.