Zonal wavefront sensing using a grating array without a reference wavefront.

Area of Science:

• Optics and Photonics
• Optical Metrology
• Wavefront Sensing

Background:

• Traditional wavefront sensors, such as Shack-Hartmann and interferometric systems, necessitate a high-quality reference source.
• The requirement for reference spots can be impractical or impossible to achieve in certain applications, limiting wavefront measurement capabilities.
• Existing methods often involve complex calibration procedures or dedicated reference optical components.

Purpose of the Study:

• To propose and validate a reference-free wavefront sensing scheme.
• To eliminate the need for independent reference spots in grating array-based wavefront sensors.
• To simplify wavefront measurement in systems where reference acquisition is challenging.

Main Methods:

• A grating array-based sensor employing local grating-induced diffraction is proposed.
• Phase gradients are encoded directly into the +1 and -1 diffraction orders.
• A single camera frame is used to record the diffraction spots, capturing encoded phase information.

Main Results:

• The proposed scheme successfully encodes phase gradients without requiring external reference spots.
• Proof-of-concept simulations demonstrated the feasibility of the technique.
• Experimental results confirmed the effectiveness and practicality of the reference-free sensing approach.

Conclusions:

• The developed reference-free wavefront sensing scheme effectively overcomes the limitations of traditional methods.
• This technique simplifies optical system design and calibration by removing the need for reference spots.
• The proposed method offers a robust solution for wavefront measurement in previously inaccessible scenarios.