Optical Fiber Bundle Beam Superposition for High-Density Laser Spots

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Solution Overview

Problem

Laser processing faces challenges in achieving high power density due to beam divergence issues when using tapered optical fibers or waveguides, and the use of power combiners can lead to heat generation and failures like combustion or disconnection.

Innovation Solution

A laser irradiation apparatus that combines laser beams from multiple optical fibers without a power combiner, using a light deflection unit at the emission side bundle end to overlap and scatter the beams, ensuring a high-power density irradiation spot while minimizing the risk of heat generation and failures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of moving object

If a tapered optical fiber or optical waveguide is used to narrow the beam emission port, then the beam width is reduced, but the beam divergence increases causing the irradiation spot to expand and power density to decrease

Engineering Contradiction:
Improvebeam emission port areaVSAvoidpower density at irradiation spot
Core Design Contradiction:
Area of moving objectVSIllumination intensity

Solution Approach 1:

The invention divides the beam transmission system into multiple separate optical fibers instead of using a single tapered fiber. Each fiber maintains its own beam path without tapering, avoiding the beam divergence problem while achieving power combination through spatial arrangement and overlap of multiple beams at the target.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention combines multiple laser beams from separate optical fibers by overlapping them in space at the irradiation target. This merging approach achieves high power density without requiring beam narrowing through tapering, thus avoiding the beam divergence issue.

Inventive Principle:
Principle #5Merging (Combining)

2Device complexity

If a power combiner is used to couple laser lights into a single optical fiber, then the number of fusion-spliced portions increases, but cladding light generation increases causing heat generation and potential failures

Engineering Contradiction:
Improvenumber of fusion-spliced portionsVSAvoidheat generation from cladding light absorption
Core Design Contradiction:
Device complexityVSObject-generated harmful factors

Solution Approach 1:

The invention extracts the problematic power combiner component from the system and replaces it with a direct multi-fiber configuration. By eliminating the combiner and its associated fusion splices, the source of cladding light generation and heat accumulation is removed entirely.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of trying to manage and dissipate the harmful cladding light heat generation, the invention avoids creating the problem in the first place by using a configuration that doesn't require aggressive beam coupling, thus converting the potential harm into a design advantage.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

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 apparatus effectively forms a high-power density irradiation spot with reduced risk of combustion or disconnection, maintaining beam focus and stability during laser processing.

Implementation Method 1

an optical fiber bundle (1) formed of a bundle of a plurality of optical fibers (2)

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 2

a light deflection unit (3) is provided at the emission side bundle end

Methodology Applied
Scientific EffectRefraction: Refraction

Data Source

PatentEP3767350B1Optical fiber bundle provided with beam superposing mechanism
Publication Date: 2024.10.23 FURUKAWA ELECTRIC CO LTD
  • EP3767350B1 patent drawingFigure 1~3B
  • EP3767350B1 patent drawingFigure 4A~5
  • EP3767350B1 patent drawingFigure 6

AI summary

Provided is a condensing apparatus that can form an irradiation spot of the laser beam having a large power density by combining a plurality of laser lights without using a power combiner. An optical fiber bundle is formed of a bundle of a plurality of optical fibers, one end thereof forms an incident side bundle end at which light incident ends of individual optical fibers are arranged, and the other end forms an emission side bundle end at which light emission ends of individual optical fibers are arranged. The optical fiber bundle includes, at the emission side bundle end, an optical deflection unit that deflects at least two light beams toward different directions, respectively, such that the at least two light beams emitted from respective light emission ends of at least two optical fibers out of the plurality of optical fibers overlap each other on at least one cross section that is at rear on an optical path of the emission side bundle end and are then scattered.