Coherent Laser Beam Combination via Two-Stage Microlens Arrays
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Solution Overview
Problem
Existing methods for combining coherent laser beams often result in a loss of beam quality and power, particularly in reducing divergence and increasing beam cross-section, which is challenging to achieve without compromising the quality of the combined laser beam.
Innovation Solution
A microlens arrangement with at least two microlens arrays is used to combine coherent laser beams, where the phase settings and focal lengths of the microlenses are carefully designed to maintain high beam quality, allowing for the formation of a combined laser beam with minimal loss of power and quality by adhering to specific equations and configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If coherent laser beams are combined using conventional methods (tiled aperture or filled aperture), then the power of the combined beam is increased, but the beam quality deteriorates due to loss of power or increased divergence
Solution Approach 1:
The invention divides the beam combination process into two independent stages: first, multiple laser beams are combined in the transverse direction using a microlens array to form an intermediate beam; second, multiple intermediate beams are combined in the longitudinal direction using another microlens array to form the final combined beam. This segmentation allows each stage to optimize for its specific direction, maintaining beam quality while achieving high power combination.
Solution Approach 2:
The invention transitions from conventional single-plane beam combination to a two-dimensional combination approach. The first microlens array combines beams in the transverse dimension, while the second microlens array combines intermediate beams in the longitudinal dimension. This dimensional separation resolves the contradiction by allowing power accumulation without compromising beam quality in either direction.
2Speed
If the beam cross section is increased to reduce divergence, then the combined beam has lower divergence, but power is lost
Solution Approach 1:
The invention dynamically adjusts the beam parameters through a two-stage microlens array system. The first stage creates intermediate beams with specific cross-sectional characteristics, while the second stage further shapes the final combined beam. This dynamic control allows the system to achieve low divergence without the power losses associated with simple beam expansion, as each stage optimizes the beam parameters for the next.
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 effectively maintains the beam quality of individual laser beams during combination, achieving high coupling efficiency and forming a combined laser beam with improved power and quality by precisely setting the phases and focal lengths of the microlens arrangement.
Implementation Method 1
a microlens arrangement with at least two microlens arrays for forming the at least one combined laser beam
Data Source
AI summary
An apparatus for combining a plurality of coherent laser beams includes at least N−1 phase setting devices configured to set a respective phase (δφn) of a respective one of the plurality of coherent laser beams, and a beam combination device configured to combine the plurality of coherent laser beams to form at least one combined laser beam. The beam combination device includes a microlens arrangement having at least two microlens arrays configured to form the at least one combined laser beam.