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Rapidly convergent phase-retrieval strategy for use with reflected laser light
1Starfire Optical Range, Directed Energy Directorate, U.S. Air Force Research Laboratory, Kirtland Air Force Base, New Mexico, USA.
Summary
A novel wave-front sensing technique uses reflected laser light from rough surfaces. This method rapidly retrieves complex fields, showing high performance in noisy conditions and strong scintillation.
Area of Science:
- Optical Engineering
- Wave-front Sensing
- Phase Retrieval
Background:
- Accurate wave-front sensing is crucial for optical system performance.
- Traditional phase retrieval methods can be slow and sensitive to noise and atmospheric turbulence (scintillation).
Purpose of the Study:
- To propose and validate a new wave-front sensing approach using reflected laser light.
- To develop a robust phase-retrieval algorithm for complex field recovery from rough objects.
Main Methods:
- Splitting a single laser beam into two, illuminating a rough object from separated apertures.
- Measuring reflected light in pupil and conjugate planes.
- Modulating one beam to measure individual intensities and their cross-product.
- Formulating a phase-retrieval algorithm using projections onto constraint sets.
Main Results:
- The proposed algorithm rapidly converges to the correct complex field solution.
- Demonstrated superior convergence rates compared to conventional phase-retrieval techniques.
- Exhibited excellent performance under strong scintillation conditions.
- Showed high tolerance to noise with minimal gain.
Conclusions:
- The novel approach provides an efficient and robust method for wave-front sensing.
- The developed phase-retrieval algorithm is particularly effective for rough object illumination.
- This technique offers significant advantages in challenging environments with turbulence and noise.