Birefringent Laser Cutting Head for Cleaner 1 µm Cut Edges
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Solution Overview
Problem
Laser cutting with solid-state lasers at a wavelength of 1 µm often results in greater cutting edge roughness, scoring, and burring, especially with increasing sheet thickness, compared to CO2 lasers at 10 µm, and existing methods to improve polarization do not effectively address these issues.
Innovation Solution
A laser processing head with a birefringent beam splitter element that splits a randomly polarized or unpolarized laser beam into two partial beams with perpendicular linear polarization, which are then focused at an angle to the optical axis, allowing for improved cutting edge quality and speed by aligning the beam entry and exit surfaces obliquely to the focusing optics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If solid-state lasers with wavelength of 1 µm are used for laser cutting, then cutting speed and energy efficiency are improved, but cutting edge roughness, scoring, and burr formation increase
Solution Approach 1:
The laser beam is segmented into multiple partial beams with different polarization directions using a birefringent beam splitting element. This segmentation allows the beam to interact with the workpiece in a manner that reduces edge roughness and burr formation while maintaining high cutting speed, effectively resolving the contradiction between productivity and manufacturing precision.
Solution Approach 2:
The invention changes the polarization parameters of the laser beam by using a birefringent beam splitting element that creates partial beams with perpendicular linear polarization directions. This parameter change in polarization state improves the cutting edge quality while maintaining the high cutting speed advantage of solid-state lasers at 1 µm wavelength.
2Manufacturing precision
If polarization-maintaining optical fibers are used to generate radially polarized laser radiation, then cutting edge quality is improved, but device complexity and cost increase
Solution Approach 1:
The invention replaces expensive polarization-maintaining optical fibers with a more economical approach using standard optical fibers combined with a birefringent beam splitting element. This substitution reduces device complexity and cost while achieving the same improvement in cutting edge quality through polarization manipulation.
Solution Approach 2:
The invention substitutes the mechanical/optical complex system of polarization-maintaining fibers with a simpler system using standard fibers and a birefringent beam splitting element. This substitution reduces device complexity while maintaining the ability to generate the desired polarization states for improved cutting quality.
3Manufacturing precision
If beam splitting elements are used to create multiple partial beams, then cutting edge quality is improved, but lateral offset between focus surfaces decreases
Solution Approach 1:
The invention addresses the limited lateral offset by introducing angular separation in addition to spatial separation. The birefringent beam splitting element creates partial beams that diverge at angles, allowing the focusing optics to create focus surfaces with both lateral and angular offset, effectively increasing the usable lateral offset for improved cutting quality.
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 enhances cutting edge quality and cutting speed by creating a compact design that maintains polarization and focuses beams efficiently, reducing beam quality issues and increasing the lateral offset between focus surfaces.
Implementation Method 1
at least one birefringent beam splitter element for splitting the laser beam, which impinges on a beam entry surface of the birefringent beam splitter element, into two partial beams
Implementation Method 2
a focusing optic for focusing the partial beams onto at least two focus surfaces in a focus plane
Implementation Method 3
the beam entry surface and preferably also the beam exit surface of the birefringent beam splitter element are inclined (i.e. not perpendicular and not parallel) to an optical axis of the focusing optic
Data Source
Figure 1~3b
Figure 4~5
Figure 6a~7
AI summary
The invention relates to a device, in particular a laser processing head (4), for machining a workpiece by means of at least one laser beam (9), comprising: at least one birefringent beam splitter element (10) for splitting the at least one laser beam (9), which impinges on a beam entrance surface (12) of the birefringent beam splitter element (10), into two partial beams (11a, 11b), wherein the birefringent beam splitter element (10) has a beam exit surface (13), which is not oriented parallel to the beam entrance surface (12), for the exit of the two partial beams (11a, 11b), and a focusing optics (16) for focusing the partial beams (11a, 11b) onto at least two focal surface regions (F1, F2) in a focal plane (2a), wherein the beam entrance surface (12) and preferably the beam exit surface (13) of the beam splitter element (10) are inclined with respect to an optical axis (15) of the focusing optics (16). The device is designed to radiate the laser beam (9) perpendicularly to the beam entrance surface (12) onto the birefringent beam splitter element (10). The invention also relates to associated methods for machining, in particular laser cutting, a workpiece by means of a laser processing machine or a laser processing head (4).