Beam Shaper Optics for Lower Rear-Side Laser Intensity
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Solution Overview
Problem
Laser beams focused onto a workpiece can cause damage to members on the rear side due to high light intensity near the optical axis, as the beams near the optical axis pass through the kerf and travel to the back side of the workpiece.
Innovation Solution
A beam shaper comprising a mode conversion device, a collimating lens, and a focusing lens, which refracts and collimates laser beams to prevent overlap near the optical axis, reducing light intensity on the rear side by adjusting the size and configuration of the central portion to emit inner peripheral beams parallel or away from the optical axis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If an axicon lens is used to shape laser beams into a ring shape, then the laser beams can effectively process medium-thick plate workpieces, but the beams near the optical axis pass through the kerf and travel to the back side of the workpiece with high light intensity, causing damage to members on the back side
Solution Approach 1:
The patent segments the laser beam into two distinct paths: central beams passing through the central portion of the mode conversion device and outer peripheral side beams refracted through the inclined surface. This segmentation allows independent control of beam trajectories, preventing the formation of a continuous high-intensity path to the rear side while maintaining effective cutting capability.
Solution Approach 2:
The patent applies different optical properties to different regions of the mode conversion device: the central portion has a flat surface that transmits central beams with minimal refraction, while the outer peripheral portion has an inclined surface that refracts outer beams at a specific angle. This local differentiation of optical properties enables precise control over beam distribution and prevents harmful high-intensity concentration on the rear side.
2Shape
If the mode conversion device refracts outer peripheral beams towards the optical axis, then a ring-shaped beam profile is generated for effective cutting, but the inner peripheral beams intersect closer to the mode conversion device side, causing overlap and high light intensity peaks in the vicinity of the optical axis
Solution Approach 1:
The patent changes the geometric parameters of the mode conversion device, specifically setting the inclination angle of the outer peripheral surface between 5-15 degrees and positioning the intersection point of outer peripheral beams at a distance of 0.5-2.0 times the focal length from the mode conversion device. These parameter adjustments ensure that outer beams form the desired ring shape while preventing excessive convergence and intensity peaks near the optical axis.
3Area of stationary object
If the size of the central portion is increased to allow more central beams to pass through, then the beam distribution changes, but the inner peripheral beams may be emitted in directions that still cause overlap and high intensity regions
Solution Approach 1:
The patent performs preliminary action by pre-calculating and pre-setting the optimal size of the central portion and the inclination angle of the outer peripheral surface during the design phase. This preliminary configuration ensures that when the laser beam passes through the mode conversion device, the central and outer beams are automatically distributed in optimal patterns that prevent harmful intensity concentration, eliminating the need for real-time adjustment.
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 beam shaper effectively suppresses damage to rear-side members by reducing light intensity, ensuring that even if beams near the optical axis travel to the rear surface, the intensity is decreased, thereby minimizing damage.
Implementation Method 1
a mode conversion device configured to refract, among laser beams of incident divergent light, laser beams incident on an outer peripheral side of a central portion about an optical axis towards the optical axis
Implementation Method 2
a collimating lens configured to convert the outer peripheral side beams and the central beams emitted from the mode conversion device into collimated light
Implementation Method 3
a focusing lens configured to focus the outer peripheral side beams and the central beams emitted from the collimating lens
Data Source
AI summary
The beam shaper includes a mode conversion device, a collimating lens, and a focusing lens. The mode conversion device refracts, among laser beams of incident divergent light, laser beams incident on an outer peripheral side of a central portion about an optical axis towards the optical axis to emit as outer peripheral side beams, and emits the laser beams incident on the central portion as central beams having an angle of emergence equal to an angle of incidence. A collimating lens converts the outer peripheral side beams and the central beams emitted from the mode conversion device into collimated light. A focusing lens focuses the outer peripheral side beams and the central beams emitted from the collimating lens.