Diffractive Laser Beam Combining With Spectral Pre-Compensation
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Solution Overview
Problem
Combining input laser beams with non-ideal bandwidths often results in impaired beam quality due to wavelength-dependent diffraction effects, particularly when using fiber lasers, which can lead to a deformed beam cross-section and reduced usability in high-power laser applications.
Innovation Solution
A device comprising pre-compensation and combination units with diffractive optical elements that spatially sort spectral components and align them for convergence, ensuring that the beam quality of the output beam matches the input beams by reversing beam broadening through diffraction effects, using diffraction grids and mirrors for accurate alignment and adaptation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If spectral coupling with diffractive optical elements is used to combine laser beams, then power density and intensity are improved, but beam quality deteriorates due to wavelength-dependent diffraction causing additional divergence and deformed beam cross-section
Solution Approach 1:
The patent applies preliminary action by using pre-compensation units with diffractive optical elements before the combination unit to pre-sort the spectral components of broadband laser beams. This preliminary spatial sorting compensates for the wavelength-dependent diffraction that will occur in the combination unit, ensuring that when beams are combined, the spectral components converge properly without causing beam quality degradation. The pre-compensation occurs upstream in the optical path, preparing the beams for optimal combination.
Solution Approach 2:
The patent introduces intermediary elements in the form of pre-compensation units and combination units with specifically designed diffractive optical elements. These intermediaries actively manage the spectral components by sorting and recombining them in a controlled manner. The pre-compensation unit acts as an intermediary that prepares the broadband beams by spatially separating spectral components, while the combination unit serves as another intermediary that merges the pre-compensated beams while maintaining beam quality through coordinated diffraction of spectral components.
2Ease of operation
If fiber lasers with non-ideal bandwidth are used as input sources, then ease of operation and power delivery are improved, but beam quality deteriorates due to bandwidth-induced divergence and beam cross-section deformation
Solution Approach 1:
The patent converts the harmful effect of non-ideal bandwidth into a benefit by using the wavelength-dependent diffraction property of diffractive optical elements in a controlled manner. Instead of treating the bandwidth-induced divergence as purely harmful, the invention uses pre-compensation units to deliberately sort spectral components based on their wavelengths, transforming the problematic bandwidth characteristic into a useful spatial separation mechanism that enables subsequent high-quality beam combination.
Solution Approach 2:
The patent applies parameter changes by using diffractive optical elements that exploit the wavelength parameter of light. The diffractive elements are designed with specific diffraction patterns that depend on wavelength, allowing them to spatially sort spectral components according to their wavelength parameters. This parameter-based sorting enables the system to handle broadband fiber laser output while maintaining beam quality through controlled manipulation of the wavelength parameter throughout the optical path.
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
The solution enables the generation of high-intensity laser radiation with excellent beam quality, maintaining the intrinsic divergence of input laser beams and preventing additional beam broadening, even when using fiber lasers with non-ideal bandwidths, thus ensuring high-power beams with preserved quality.
Implementation Method 1
The pre-compensation unit has at least one diffractive optics which expands the respective input laser beam into an assigned, widened intermediate beam bundle
Implementation Method 2
the first diffractive optical element transforms an intermediate beam bundle by diffraction into a convergent beam bundle with a beam waist
Implementation Method 3
The second diffractive optical element is then in turn designed and arranged in such a way that all incident spectral components are deflected into a common radiation direction
Data Source
AI summary
A device for combining at least two input laser beams having different spectral components. At least one pre-compensation unit for the at least two input laser beams has a diffractive optical unit which expands the input laser beam into an intermediate beam bundle in which the spectral components are spatially arranged so as to be adjacent to one another with increasing wavelength. A combination unit has at least a first diffractive optical element and a second diffractive optical element, the combination unit being aligned with the pre-compensation unit in such a way that the first diffractive optical element converts an intermediate beam bundle into a convergent beam bundle having a beam waist, the beam waist lying on the second diffractive element, and the second diffractive optical element being designed in this way that all incident spectral components are diffracted in a common radiation direction.