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Target-in-the-loop wavefront sensing and control with a Collett-Wolf beacon: speckle-average phase conjugation
Mikhail A Vorontsov1, Valeriy V Kolosov, Ernst Polnau
1Intelligent Optics Laboratory, Computational and Information Sciences Directorate, U.S. Army Research Laboratory, Adelphi, Maryland 20783, USA. mvorontsov@arl.army.mil
Applied Optics
|December 25, 2008
Summary
A new adaptive optics technique uses speckle-average phase conjugation to improve laser projection onto distant targets. This method enhances power density by compensating for atmospheric turbulence and speckle effects.
Area of Science:
- Optical Engineering
- Laser Physics
- Wavefront Sensing
Background:
- Adaptive optical systems are crucial for laser beam projection through turbulent media.
- Speckle effects from target surfaces degrade beam quality and power density.
- Conventional methods struggle with extended targets in inhomogeneous environments.
Purpose of the Study:
- To introduce and evaluate a novel adaptive optics wavefront control technique: speckle-average (SA) phase conjugation.
- To mitigate speckle effects and compensate for atmospheric turbulence in laser projection.
- To analyze the performance of SA phase conjugation with varying target anisoplanatism and beacon size.
Main Methods:
- Developed and implemented speckle-average (SA) phase conjugation for wavefront control.
- Utilized a Shack-Hartmann wavefront sensor to measure target return wave slopes.
- Generated an incoherent Collett-Wolf beacon on the target using a scanned auxiliary laser beam.
- Conducted numerical simulations and experimental validation.
Main Results:
- SA phase conjugation effectively mitigates speckle effects from rough target surfaces.
- The technique demonstrates efficient compensation for atmospheric turbulence.
- Significant increase in projected laser beam power density on remote extended targets was observed.
- Performance is influenced by target anisoplanatism and Collett-Wolf beacon characteristics.
Conclusions:
- Speckle-average phase conjugation offers a robust solution for adaptive optics in challenging environments.
- The method enhances laser projection efficiency and power delivery to extended targets.
- Further research can optimize system performance by considering beacon size and target properties.
