Laser Resonant Cavity with Microstructured Mirror for Beam Control
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Solution Overview
Problem
High power lasers often exhibit large divergence angles, shallow depth of focus, and high power density loss during long distance transmission due to their multi-mode nature, making them unsuitable for precise industrial and military applications.
Innovation Solution
A laser design featuring a total reflective mirror with a microstructure, including a step structure of cylinders, and an output mirror with controlled reflectivity, which reduces beam divergence and power density loss by optimizing the resonant cavity and active laser medium configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high power multi-mode lasers are used, then power level is improved, but beam divergence angle increases and depth of focus decreases
Solution Approach 1:
The resonant cavity is segmented into multiple sections with different mirror configurations. The first resonant cavity uses a concave output mirror to achieve beam convergence, while the second resonant cavity uses a flat or convex output mirror for different beam characteristics. This segmentation allows the system to maintain high power while controlling beam divergence through the specific geometry of each cavity section.
Solution Approach 2:
The patent employs curved mirrors with specific radii of curvature in the resonant cavity. The total reflective mirror has a curvature radius R1 and the output mirror has curvature radius R2, where these curved surfaces are strategically designed to control the beam propagation characteristics. The curvature of these mirrors enables the system to achieve both high power output and controlled beam divergence by manipulating the wavefront shape.
2Power
If high power multi-mode lasers are used, then power level is improved, but power density loss during long distance transmission increases
Solution Approach 1:
The laser system is divided into multiple resonant cavities with different mirror configurations to produce multiple laser beams with distinct characteristics. This segmentation allows optimization of each beam for specific transmission requirements, reducing overall power density loss by distributing energy across multiple optimized beams rather than a single high-divergence beam.
Solution Approach 2:
The patent changes key parameters of the resonant cavity including mirror curvature radii (R1, R2), cavity lengths (L1, L2), and mirror reflectivities to optimize beam propagation. By adjusting these parameters, the system achieves beam characteristics that minimize divergence and power density loss during long distance transmission while maintaining high power output.
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 laser beam achieves a small divergence angle, small spot size, long depth of focus, and low power density loss, enhancing its applicability in cutting, welding, and other long distance transmission tasks.
Implementation Method 1
a total reflective mirror (102) and an output mirror (104) are separately configured on two opposite ends of the discharge lamp (106)... The total reflective mirror (102), the output mirror (104), and the discharge lamp (106) define a resonant cavity (110)
Implementation Method 2
an active laser medium (108) is filled in the resonant cavity (110)
Data Source
AI summary
A laser includes a total reflective mirror, an output mirror, a discharge lamp, and an active laser medium. The total reflective mirror, the output mirror, and the discharge lamp define a resonant cavity. The active laser medium is filled in the resonant cavity. The total reflective mirror includes a body, a metal film, and at least one microstructure. Each of the at least one microstructure is a step structure. The step structure includes a plurality of cylinders stacked with each other with respect to their diameters. Both the height and the diameter of the cylinders are in a range from about 0.5λ to about 2λ, while λ is a working wavelength of the laser.