Curved-Surface Laser Beam Shaping With Phase-Corrected Focus
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Solution Overview
Problem
Existing laser processing technologies face challenges in effectively processing workpieces with curved surfaces, as beam shaping approaches developed for plane surfaces are not suitable and result in aberrations that disrupt the formation of nondiffractive beams like Bessel beams, leading to incomplete material modifications.
Innovation Solution
The method involves beam shaping using diffractive, reflective, and refractive optical assemblies to form an elongated focus zone along the beam axis, with phase-correcting beam shaping to counteract interference effects caused by the curved surface, allowing for the modification of transparent materials like glass tubes or cylinders.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If beam shaping approaches developed for plane surfaces are used on curved surfaces, then the device complexity is reduced, but the manufacturing precision deteriorates due to aberrations disrupting nondiffractive beam formation
Solution Approach 1:
The patent applies local quality by implementing phase correction specifically at the curved entry surface of the workpiece. The optical system is designed to correct phase aberrations only where they occur (at the curved interface), while maintaining the nondiffractive beam properties in the bulk material. This localized approach to phase correction resolves the contradiction by adapting the beam shaping to the specific geometric condition without requiring complete redesign of the entire optical system.
Solution Approach 2:
The patent changes the phase parameter of the laser beam through phase-correcting optical elements. By modifying the phase distribution of the beam before it enters the curved workpiece, the system compensates for the aberrations that would otherwise disrupt nondiffractive beam formation. This parameter change (phase correction) enables precise material modification on curved surfaces while maintaining a relatively simple overall device configuration.
2Manufacturing precision
If phase-correcting beam shaping is implemented to counteract interference effects, then the manufacturing precision is improved, but the device complexity increases due to additional optical assemblies
Solution Approach 1:
The patent merges the phase correction function with the beam shaping function by integrating phase-correcting optical elements into the existing beam shaping optical path. Rather than adding completely separate correction systems, the phase correction is combined with the beam shaping process, thereby improving manufacturing precision while minimizing the increase in device complexity through functional integration.
Solution Approach 2:
The patent introduces phase-correcting optical elements as intermediaries between the laser beam source and the workpiece. These intermediary elements (such as phase plates or diffractive optical elements) modify the beam phase to compensate for curved surface effects without requiring fundamental changes to the laser source or the workpiece, thus achieving precision improvement with controlled complexity increase.
3Productivity
If beam portions enter at an entry angle to form an elongated focus zone, then the productivity is improved through volume absorption, but the manufacturing precision deteriorates due to interference effects from the curved surface
Solution Approach 1:
The patent applies preliminary action by pre-correcting the phase of the laser beam before it enters the curved workpiece. The phase-correcting optical elements prepare the beam in advance to compensate for the interference effects that would occur during entry into the curved surface. This preliminary phase correction enables the beam to maintain its nondiffractive properties and form an accurate elongated focus zone, thereby preserving manufacturing precision while maintaining productivity through volume absorption.
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 approach enables the successful formation and propagation of nondiffractive beams within the workpiece, allowing for precise material modifications and separation processes, even on curved surfaces, by compensating for aberrations and maintaining the desired intensity distribution.
Implementation Method 1
beam shaping of the laser beam is carried out by using an arrangement of diffractive, reflective and/or refractive optical assemblies
Implementation Method 2
beam shaping of the laser beam is carried out by using an arrangement of diffractive, reflective and/or refractive optical assemblies
Implementation Method 3
beam shaping of the laser beam is carried out by using an arrangement of diffractive, reflective and/or refractive optical assemblies
Implementation Method 4
focus-forming beam shaping to cause beam portions to enter at an entry angle to a beam axis of the laser beam for forming the elongated focus zone along the beam axis in the workpiece by way of interference
Implementation Method 5
phase-correcting beam shaping to counteract any influence of the interference by entrance of the laser beam into the workpiece
Implementation Method 6
an absorption of the laser radiation that occurs in the volume of the material (volume absorption for short) can bring about an elongated modification of the structure of the material
Data Source
AI summary
A method for processing a workpiece using a pulsed laser beam includes beam shaping of the laser beam to form an elongated focus zone in the material of the workpiece. The beam shaping is carried out by using an arrangement of diffractive, reflective and/or refractive optical assemblies. The beam shaping includes focus-forming beam shaping to cause beam portions to enter at an entry angle to a beam axis of the laser beam for forming the elongated focus zone along the beam axis in the workpiece by way of interference, and phase-correcting beam shaping to counteract any influence of the interference by entrance of the laser beam into the workpiece. The method further includes setting beam parameters of the laser beam so that the material of the workpiece is modified in the elongated focus zone.