Curved Beam Combining Optics for Low-BPP Fiber-Coupled Lasers
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Solution Overview
Problem
Lamp pumped laser systems face challenges in maintaining low Beam Parameter Product (BPP) due to thermal lensing effects, which degrade beam quality and reduce alignment tolerances, especially at high pulse energies and frequencies.
Innovation Solution
A laser system comprising a relay assembly with curved reflective surfaces and a galvo with different curvature radii, coupled with a coupling assembly, to redirect and combine laser beams, reducing spherical aberrations and achieving a lower BPP than the optical fiber, thereby improving beam quality and alignment tolerances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If lamp pumped laser systems are used to generate high pulse energy and frequency, then power output is improved, but beam quality deteriorates due to thermal lensing effect
Solution Approach 1:
The patent employs curved reflective surfaces in both the relay assembly and galvo scanner with specifically designed curvature radii. The curved surfaces refract and redirect the laser beams in a manner that compensates for thermal lensing effects, maintaining beam quality despite high power operation. The curvature is engineered to counteract the spherical aberrations introduced by the thermal lensing in the gain medium.
2Productivity
If the BPP of the output laser beam is made close to the BPP of the fiber, then coupling efficiency is improved, but alignment tolerance deteriorates
Solution Approach 1:
The patent carefully controls and adjusts the Beam Parameter Product (BPP) of the combined laser beam through the curved reflective surfaces, ensuring that the output BPP is optimized for fiber coupling. By manipulating the beam parameters through controlled refraction and redirection, the system achieves efficient coupling while maintaining sufficient alignment tolerance through precise parameter management.
3Ease of operation
If optics are used to direct the input laser beam to the optical fiber, then beam delivery is improved, but beam quality deteriorates due to additional degradation
Solution Approach 1:
The patent introduces a relay assembly with curved reflective surfaces as an intermediary between the laser resonators and the galvo scanner. This relay assembly acts as a mediating optical element that redirects and condition the beams before they enter the galvo, ensuring that the subsequent optics maintain rather than degrade beam quality. The curved surfaces in the relay assembly pre-condition the beams to compensate for potential quality losses in downstream optics.
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 system achieves a combined laser beam with a BPP at least 10% less than the optical fiber's BPP, enhancing beam quality and increasing alignment tolerances, making the system more reliable at high pulse energies and frequencies.
Implementation Method 1
a relay assembly including at least one curved reflective surface that redirects each input laser beam
Implementation Method 2
a relay assembly including at least one curved reflective surface that redirects each input laser beam, and reduces a beam size of the redirected beam
Data Source
AI summary
Laser systems and methods are disclosed. One laser system comprises: a plurality of laser resonators, each resonator being operable to discharge an input laser beam; a relay assembly including at least one curved reflective surface that redirects each input laser beam, and reduces a beam size of the redirected beam; a galvo including a curved reflective surface that receives each redirected beam, and outputs a combined laser beam at power level greater than a power level of each laser input beam; and a coupling assembly that reduces spherical aberrations in the combined laser beam, and directs the combined laser beam into an optical fiber. In this system, the combined laser beam may have a maximum beam parameter product lower than a minimum beam parameter product of the optical fiber. Related systems and methods are also disclosed.