Frustoconical Quartz Termination Block for Back-Reflected Light Management
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Solution Overview
Problem
High power fiber laser systems face damage from back-reflected light that enters the fiber housing, causing overheating and destruction of the protective polymeric coatings and cladding due to ineffective existing solutions for managing back-reflected radiation.
Innovation Solution
A fiber laser system with a frustoconically shaped quartz termination block and a reflector configured to prevent back-reflected light from entering the fiber's cladding, utilizing a combination of a water-cooled housing, a reflector, and a light guard arrangement to minimize coupling of back-reflected light into the protective layer, including a configuration with multiple claddings to reduce the power of back-reflected light coupled into the delivery fiber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional bulk optics and cylindrical termination blocks are used, then the system structure is simple, but back-reflected light couples into the fiber cladding and protective layer causing damage
Solution Approach 1:
The patent applies asymmetry by changing the termination block from a conventional cylindrical shape to a frustoconical (truncated cone) shape with a specific apex angle. This asymmetric geometry creates total internal reflection at the block-fiber interface, preventing back-reflected light from coupling into the fiber cladding and protective layer, thereby resolving the contradiction between simple structure and effective protection.
Solution Approach 2:
The patent changes the geometric parameter of the termination block by specifying a particular apex angle range (60-110 degrees, preferably 70-90 degrees). This parameter change optimizes the total internal reflection effect, ensuring that back-reflected light is redirected away from the fiber cladding while maintaining structural simplicity.
2Reliability
If the termination block angle is optimized for total internal reflection, then back-reflected light is prevented from entering the cladding, but the manufacturing precision requirements increase
Solution Approach 1:
The patent specifies a range for the apex angle (60-110 degrees, preferably 70-90 degrees) rather than a single precise value. This parameter range provides manufacturing tolerance, allowing the total internal reflection effect to remain effective across a range of angles while reducing the stringency of manufacturing precision requirements.
Solution Approach 2:
The patent specifies that the termination block be made from quartz or similar high-damage-threshold material. This material selection complements the geometric design by providing high resistance to laser damage, allowing the system to tolerate some variation in angular precision while maintaining reliable protection.
3Reliability
If a reflector is added to block back-reflected light, then the protective layer is better protected, but the device complexity and housing space requirements increase
Solution Approach 1:
The patent extracts the light-blocking function from a separate reflector component and integrates it into the frustoconical termination block itself. The conical geometry inherently provides the light-blocking function through total internal reflection, eliminating the need for additional reflector components and reducing housing volume requirements.
Solution Approach 2:
The patent merges the termination function and the light-blocking function into a single frustoconical component. The termination block simultaneously serves as the fiber termination structure and the light redirecting element, consolidating multiple functions into one element and reducing overall device complexity and space requirements.
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 effectively reduces the damage from back-reflected light by ensuring it does not penetrate the protective layer, maintaining the integrity of the fiber laser system and preventing overheating, thereby extending its operational lifespan.
Implementation Method 1
The present disclosure provides for an angle of cone-termination block which would prevent back-reflected light from penetrating through the cone termination block and coupling into the fiber's outer cladding or protective coating
Implementation Method 2
The system may have a water-cooled housing supporting a termination block
Implementation Method 3
The reflected radiation from the surface of the workpiece or other thermal absorption is accomplished by the water
Data Source
AI summary
The present disclosure is a system for the protection of a fiber within a laser system. The system has a water-cooled housing supporting a termination block, which is operative to shield a protective layer of a delivery fiber from back-reflected beams of light. The termination block is manufactured from quartz and is frustconical in configuration and fuseable to the delivery fiber. The delivery fiber has a polymeric protective layer with an acceptance end and a delivery end, and passes through a washer contained within the housing; the washer has a dielectric reflective coating. The system has at least one terminal block connector which further comprises a cone termination block, a reflector, and a set of light guards. The cone termination block is spliced to an output end of the delivery fiber and produces an angle λ so as to reduce propagation of back-reflected light. The reflector is positioned so as to block additional back-reflected light from the protective layer of the delivery fiber.