Laser Resonator Microstructure Beam Divergence Control
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Solution Overview
Problem
High power lasers used in industrial and military applications often suffer from large divergence angles, shallow depth of focus, and high power density loss during long distance transmission due to their multi-mode nature.
Innovation Solution
A laser design incorporating a total reflective mirror with a microstructure and a partial reflective output mirror, optimized for a specific wavelength, which reduces beam divergence and enhances focus depth while minimizing power loss, achieved through the use of a spherical mirror with a metal film and microstructures within the resonant cavity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high power multi-mode lasers are used to achieve high power levels, then power output 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-convex mirror arrangement for fundamental mode generation, while the second resonant cavity uses a plane-plane mirror arrangement for higher mode generation. This segmentation allows the laser to produce a composite beam that maintains low divergence while achieving high power output.
Solution Approach 2:
The laser beam is formed as a composite of multiple modes (fundamental mode from the first cavity and higher modes from the second cavity). This composite beam structure combines the low divergence property of fundamental mode with the high power capability of multi-mode operation, resolving the contradiction between power output and beam quality.
2Power
If high power multi-mode lasers are used to achieve high power levels, then power output is improved, but depth of focus becomes shallow
Solution Approach 1:
The resonant cavity is segmented into multiple sections with different mirror configurations. The first resonant cavity uses a concave-convex mirror arrangement for fundamental mode generation, while the second resonant cavity uses a plane-plane mirror arrangement for higher mode generation. This segmentation allows the laser to produce a composite beam that maintains low divergence while achieving high power output.
Solution Approach 2:
The laser beam is formed as a composite of multiple modes (fundamental mode from the first cavity and higher modes from the second cavity). This composite beam structure combines the low divergence property of fundamental mode with the high power capability of multi-mode operation, resolving the contradiction between power output and beam quality.
3Power
If high power multi-mode lasers are used to achieve high power levels, then power output is improved, but power density loss increases during long distance transmission
Solution Approach 1:
The resonant cavity is segmented into multiple sections with different mirror configurations. The first resonant cavity uses a concave-convex mirror arrangement for fundamental mode generation, while the second resonant cavity uses a plane-plane mirror arrangement for higher mode generation. This segmentation allows the laser to produce a composite beam that maintains low divergence while achieving high power output.
Solution Approach 2:
The laser beam is formed as a composite of multiple modes (fundamental mode from the first cavity and higher modes from the second cavity). This composite beam structure combines the low divergence property of fundamental mode with the high power capability of multi-mode operation, resolving the contradiction between power output and beam quality.
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 results in a laser beam with a small divergence angle, small spot size, long depth of focus, and low power density loss, making it suitable for efficient cutting and welding applications, especially over long distances.
Implementation Method 1
a total reflective mirror (102) and an output mirror (104) which are separately arranged at two ends of the discharge lamp (106) to define a resonant cavity (110) together with the discharge lamp (106)
Implementation Method 2
an active laser medium (108) filled in the resonant cavity (110)
Implementation Method 3
a microstructure (112) and a metal film (1022) coated on a first reflective surface (1021) of the body (1020)
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. The at least one microstructure has a height and a lateral size, and both the height and the lateral size are in a range from about 0.5λ to about 2λ, while λ is a working wavelength of the laser.