Coherent Fiber Array Beam Control for High-Power Remote Projection
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Solution Overview
Problem
Conventional high power laser beam projection systems face challenges in scaling laser power to tens and hundreds of kilowatts while maintaining near diffraction-limited beam quality and effectively mitigating the negative impacts of optical inhomogeneities and environmental factors.
Innovation Solution
The use of coherent fiber array laser systems with novel adaptive optics control algorithms and beam tail interference sensors with amplitude gratings enables upwards scaling of laser power while preserving beam quality and adaptively mitigating the effects of propagation-medium-induced phase aberrations and environmental vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional adaptive optics with electro-mechanical deformable mirrors are used, then beam quality can be maintained, but the system cannot withstand laser power scaling above 100 kW and has insufficient response time for fast-moving targets
Solution Approach 1:
The patent replaces electro-mechanical deformable mirrors with a purely optical adaptive optics system using a spatial light modulator (SLM). This substitution eliminates the mechanical components that limit power handling capability, allowing the system to scale to hundreds of kilowatts while maintaining beam quality correction. The SLM uses electro-optic or liquid crystal effects rather than mechanical deformation, fundamentally resolving the power scaling limitation.
Solution Approach 2:
The patent changes the response time parameter by using an SLM with microsecond or sub-microsecond switching speeds, compared to the 100 microsecond or longer response time of conventional deformable mirrors. This parameter change enables the system to track and correct phase aberrations for fast-moving targets, significantly improving the system's ability to handle dynamic scenarios.
2Power
If the deformable mirror size is increased to decrease power density, then power handling improves, but system cost, size, and complexity increase
Solution Approach 1:
By replacing the mechanical deformable mirror with an SLM-based optical system, the patent achieves high power handling capability without increasing physical size. The SLM can be implemented in a compact form factor while maintaining the ability to handle hundreds of kilowatts of laser power, thus avoiding the trade-off between power handling and system complexity.
3Power
If laser power is scaled to tens and hundreds of kilowatts, then system capability improves, but beam quality deteriorates due to thermal blooming and optical inhomogeneities
Solution Approach 1:
The patent implements a closed-loop feedback system using wavefront sensing to measure phase aberrations caused by thermal blooming and optical inhomogeneities. The measured aberrations are fed back to the SLM in real-time, which applies compensating phase corrections. This feedback mechanism enables the system to maintain near-diffraction-limited beam quality even at power levels of hundreds of kilowatts, where thermal effects would otherwise severely degrade performance.
Solution Approach 2:
The replacement of mechanical deformable mirrors with an SLM-based optical system enables more precise and rapid phase correction at high power levels. The optical approach avoids thermal loading and mechanical limitations that constrain conventional systems, allowing maintaining beam quality at higher powers where thermal blooming becomes significant.
4Reliability
If conventional adaptive optics techniques are used, then some mitigation of phase aberrations can be achieved, but the response time is insufficient for rapidly changing phase aberrations from fast-moving targets
Solution Approach 1:
The patent changes the response time parameter by utilizing an SLM with microsecond or sub-microsecond switching speeds, compared to the 100 microsecond or longer response time of conventional deformable mirrors. This parameter improvement enables the system to track and correct rapidly changing phase aberrations from fast-moving targets, achieving reliable beam quality maintenance in dynamic scenarios.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for the achievement of near diffraction-limited beam quality and adaptive mitigation of phase aberrations, enabling efficient high power laser beam projection systems capable of scaling to tens and potentially hundreds of kilowatts.
Implementation Method 1
beam tail interference sensors with amplitude gratings
Implementation Method 2
beam tail interference sensors with amplitude gratings
Implementation Method 3
coherent fiber array laser systems
Implementation Method 4
coherent fiber array laser systems
Data Source
AI summary
A coherent fiber array laser power projection system scalable to large number of subapertures and includes sensors that produce signals dependent upon beam characteristics, and controllers configured to control beam characteristics to achieve either phasing of outgoing beams at transmitter plane or coherent beam combining at a remote target or both.