Ring Fiber Saddle Beam for Reduced Laser Hot Spots
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Solution Overview
Problem
Gaussian single mode laser beams can cause hot spots and unwanted vaporization due to conduction and absorptive heating, leading to spatter or voids in applications like additive manufacturing.
Innovation Solution
A single mode input beam is coupled into a ring fiber with a depressed index hole in the center, creating a saddle-shaped beam with a low M2 value, which reduces central heating and maintains shape even when defocused, suitable for high-precision processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a gaussian single mode laser beam is used to achieve minimum spot size and longest Rayleigh range, then beam focusing capability is improved, but hot spots and unwanted vaporization occur due to conduction and absorptive heating
Solution Approach 1:
The patent modifies the beam intensity distribution by creating a saddle-shaped profile where the center region has reduced intensity compared to the perimeter. This is achieved through specific optical arrangements that redistribute energy locally, reducing hot spots in the center while maintaining adequate intensity at the edges for effective processing.
Solution Approach 2:
The patent changes the beam shape parameter from gaussian to saddle-shaped, transforming the intensity distribution profile. This parameter change allows the beam to maintain focus capability while redistributing energy to avoid excessive heating at the center, thereby preventing vaporization and spatter.
2Temperature
If a ring fiber with depressed index hole is used to create saddle beam shape, then central heating is reduced, but device complexity increases
Solution Approach 1:
The patent uses a ring fiber with depressed index hole as an intermediary optical element to transform the beam profile. This specialized fiber acts as a mediator that converts a standard gaussian input beam into a saddle-shaped output beam, reducing central heating without requiring complex external optical systems.
3Object-generated harmful factors
If beam shape is modified to reduce hot spots, then harmful thermal effects are reduced, but beam quality and M2 value may deteriorate
Solution Approach 1:
The patent optimizes the saddle beam parameters including M2 value, spot size, and intensity distribution to achieve a balance between reducing thermal effects and maintaining beam quality. The beam is designed with controlled divergence and specific intensity profiles that preserve focusing capability while eliminating hot spots.
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 saddle beam shape achieves a flatter temperature profile and is compatible with any spot size, reducing unwanted effects like vaporization and spatter, making it suitable for advanced manufacturing and welding applications.
Implementation Method 1
the first length of fiber having a first refractive index profile (RIP) defined by a centrally located guiding region and an annular region coaxially encompassing the centrally located guiding region, the centrally located guiding region having a first diameter and a first index of refraction, and the annular region having a second index of refraction that is less than the first index of refraction
Implementation Method 2
a second length of fiber having a second RIP defined by a centrally located anti-guiding core and an annular guiding region coaxially encompassing the centrally located anti-guiding core, the centrally located anti-guiding core having a second diameter and a third index of refraction
Data Source
AI summary
Optical fiber structures for generating a single mode, saddle shaped output beam include first and second lengths of fiber. The first length of fiber has a first input end configured to receive a single mode gaussian beam. The second length of fiber has a second input end coupled to an output end of the first length of fiber. The second length of fiber includes a centrally located anti-guiding core and an annular guiding region coaxially encompassing the centrally located anti-guiding core.