Bessel Beam Optical Assembly Alignment Using Workpiece Imitation
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Solution Overview
Problem
Existing optical systems for forming Bessel beams in laser processing machines face difficulties in alignment due to aberration corrections, which disrupt the homogeneity and symmetry of the beam, making it challenging to correctly orient beam shaping elements and focusing lenses.
Innovation Solution
A device and method for aligning a processing optical assembly in a laser processing machine that includes an entrance region, a focus zone forming region, and an imaging unit with a lens and detector surface, using a workpiece imitation to compensate for aberrations and ensure the formation of a preset Bessel beam focus zone, allowing for the measurement of the focus zone's length and properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If aberration correction is implemented in the beam shaping process, then the Bessel beam can be formed correctly in workpieces with inclined or cylindrical surfaces, but the homogeneity and symmetry of the beam are disrupted, making alignment difficult
Solution Approach 1:
A workpiece imitation element is introduced as an intermediary component that reproduces the optical effects (aberrations) of the actual workpiece. This allows the alignment process to account for workpiece-specific optical distortions without requiring the actual workpiece, thereby maintaining beam symmetry and homogeneity during alignment while ensuring accurate Bessel beam formation during processing
Solution Approach 2:
The alignment process is performed in advance using the workpiece imitation element before actual processing. This preliminary alignment ensures that the beam shaping elements and focusing lenses are correctly oriented to compensate for aberrations, so that when the actual workpiece is processed, the Bessel beam forms accurately without requiring further adjustment
2Manufacturing precision
If workpiece-specific aberration corrections are applied, then processing accuracy for inclined or cylindrical workpieces is improved, but the beam properties downstream of the workpiece lose their regularity, preventing use as alignment features
Solution Approach 1:
A workpiece imitation element is created that copies the optical characteristics (refractive index, geometry, surface orientation) of the actual workpiece. This copy allows the alignment system to learn and compensate for workpiece-specific aberrations without the actual workpiece being present, preserving beam symmetry information during the alignment process while maintaining processing accuracy
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 solution simplifies the alignment of the processing optical assembly, ensures undisturbed formation of the Bessel beam focus zone despite aberration-causing workpiece geometries, and enables measurement of the focus zone's properties, improving alignment and material processing accuracy.
Implementation Method 1
an imaging unit having a lens and a detector surface, wherein the lens is configured to image measurement laser radiation that leaves the focus zone forming region after the measurement focus zone has been formed
Implementation Method 2
processing optical assembly configured to shape a laser beam in the laser processing machine and to focus it along an incident beam axis so that a processing laser beam can form a preset Bessel beam focus zone in a workpiece
Data Source
AI summary
A device for aligning a processing optical assembly of a laser processing machine includes an entrance region for receiving a processing laser beam, a focus zone forming region for forming a measurement focus zone by the received processing laser beam along a target axis, and an imaging unit having a lens and a detector surface. The lens is configured to image measurement laser radiation that leaves the focus zone forming region after the measurement focus zone has been formed, along an imaging axis predefined by the target axis, onto the detector surface. The processing optical assembly is configured to shape a laser beam in the laser processing machine and to focus it along an incident beam axis so that a processing laser beam forms a preset Bessel beam focus zone in a workpiece to be processed.