Bifocal Laser Optical System for Spattering Reduction
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Solution Overview
Problem
Laser processing with fiber or YAG lasers results in increased absorption and spattering due to high evaporation reactive forces, leading to inefficiencies and instability in welding, particularly with low-carbon steel, and requires separate optical systems for cutting and welding.
Innovation Solution
An optical system with two focal points on the optical axis is created using a first lens for focusing and a second lens with a through-hole region that does not focus, and a diverging region, reducing evaporation reactive forces and allowing for stable welding and efficient switching between cutting and welding modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a fiber laser or YAG laser is used to increase absorption efficiency, then the energy absorption rate increases significantly, but the evaporation reactive force increases causing excessive spattering
Solution Approach 1:
The patent divides the laser beam into two separate beams with different characteristics: a center beam with high energy intensity for effective welding and a peripheral beam with low energy intensity to suppress spattering. This segmentation allows simultaneous achievement of high absorption efficiency and reduced harmful evaporation effects
Solution Approach 2:
The patent applies different energy intensities to different regions of the laser beam: high energy intensity at the center for effective material processing and low energy intensity at the periphery to reduce evaporation reactive force. This local differentiation resolves the contradiction between absorption efficiency and spattering control
2Object-generated harmful factors
If the focal point is shifted away from the processing point to reduce spattering, then evaporation reactive force decreases, but the high energy intensity of the laser light cannot be fully utilized
Solution Approach 1:
Instead of shifting the single focal point, the patent creates two focal points: one at the processing point for maximum energy utilization and another slightly offset to provide a low energy intensity region that suppresses spattering. This resolves the trade-off between energy utilization and spattering control
Solution Approach 2:
The patent introduces a beam shaping optical system as an intermediary between the laser source and workpiece, which transforms the single high-intensity beam into a composite beam with both high and low intensity regions, enabling simultaneous optimization of welding efficiency and spattering suppression
3Device complexity
If a single optical system is used for both cutting and welding, then device complexity is reduced, but the different beam forms required for cutting and welding make sharing difficult
Solution Approach 1:
The patent designs a universal optical system with a beam shaping unit that can generate different beam profiles (single focal point for cutting, dual focal points for welding) using the same hardware platform. This allows one optical system to perform both cutting and welding functions effectively
Solution Approach 2:
The patent introduces adjustable optical elements that can dynamically change the beam configuration between cutting mode (single focal point) and welding mode (dual focal points), enabling the optical system to adapt to different processing requirements without requiring separate systems
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
This configuration reduces spattering and allows for stable welding with reduced evaporation reactive forces, enabling efficient processing with high energy intensity at the center and low intensity at the periphery, facilitating quick switching between cutting and welding operations.
Implementation Method 1
a first lens that focuses laser light
Implementation Method 2
a second region that surrounds the first region and that diverges the laser light
Implementation Method 3
forming two focal points on the optical axis
Implementation Method 4
laser light is transmitted to a processing head from a laser oscillator via an optical fiber
Data Source
AI summary
Provided are an optical system (7) and a laser processing apparatus with which spattering can be suppressed by reducing an evaporation reactive force at a workpiece by forming two focal points (F1, F2) on the optical axis, using a simple configuration. An optical system (7) is provided with a convex lens (8) that focuses laser light, and a concave lens (9) that is disposed on the same optical axis as the laser light that passes through the convex lens (8), wherein the concave lens (9) has a first region that has a through-hole (11), that is positioned on the optical axis, and that does not have lens properties, as well as a second region that surrounds the first region and that diverges the laser light.