Pulsed Laser Ablation Cutting Transparent Substrates
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Laser cutting of thin transparent substrates like glass and sapphire often results in damage beyond the immediate cutting area due to secondary processing zones, causing optical defects and reduced mechanical resilience.
Innovation Solution
A method involving two stages of pulsed laser processing: initial surface pretreatment with high pulse overlap to create scattering centers, followed by cutting with reduced pulse overlap to minimize energy penetration and prevent damage, using a pulsed laser with adjustable parameters like feed rate and pulse frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high laser energy is applied during laser cutting of transparent substrates, then cutting efficiency is improved, but secondary processing zones and material damage are formed
Solution Approach 1:
The patent applies preliminary action by first creating a surface modification layer through initial laser pulses before applying high energy for cutting. This pre-treatment modifies the surface properties to control subsequent energy absorption and prevent harmful secondary processing zones while maintaining cutting efficiency
Solution Approach 2:
The patent implements local quality by creating a differentiated surface layer with modified optical properties. The surface modification layer has different characteristics from the bulk material, allowing controlled energy absorption at the surface while protecting the interior from harmful effects during the cutting process
2Length of moving object
If laser beam penetrates deeply into transparent workpiece material, then cutting through is achieved, but damage zones are formed on the underside of the workpiece
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting laser pulse energy levels during the cutting process. The laser energy is modulated to achieve sufficient penetration for complete cutting while preventing excessive energy deposition that would create damage zones, thus maintaining workpiece integrity and stability
3Productivity
If laser radiation with high energy per unit distance is used, then material removal is efficient, but reflections and optical defects occur within the transparent workpiece
Solution Approach 1:
The patent converts the harmful effect of reflections and optical defects into a beneficial process. By creating a surface modification layer with controlled optical properties, the patent transforms potential harmful reflections into useful energy absorption at the surface, preventing light from penetrating deeper and causing defects while maintaining efficient material removal
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
Effectively prevents or reduces secondary damage zones, enhancing the stability and flexural strength of cut workpieces by minimizing energy penetration and reflections, thus reducing post-processing needs.
Implementation Method 1
Method for the ablation cutting of a workpiece by means of a pulsed laser beam
Implementation Method 2
The irradiated area of at least two consecutive laser pulses can spatially overlap
Implementation Method 3
Scattering centers are thus generated in the workpiece area near the surface, which prevent laser radiation with a then lower energy per unit distance from penetrating into the transparent workpiece material
Implementation Method 4
removal of the pretreated workpiece surface by repeatedly passing over the workpiece surface with the pulsed laser beam along the surface path
Data Source
Figure 1a~2d
Figure 3a~3e
AI summary
The method according to the invention for ablating an in particular transparent workpiece (1) by means of a pulsed laser beam (2) comprises the following steps: a) pretreating the workpiece surface (3) by moving the pulsed laser beam (2) over the workpiece surface (3) along a surface path (4), wherein consecutive laser pulses (2', 2") of the pulsed laser beam (2) have a first pulse overlap (61) on the workpiece surface (3a) in the path direction (5); and b) ablating the pretreated workpiece surface (3) by moving the pulsed laser beam (2) over the workpiece surface (3) along the surface path (4) multiple times, wherein consecutive laser pulses (2', 2") of the pulsed laser beam (2) have a second pulse overlap (62) on the workpiece surface (3) in the path direction (5), which second pulse overlap is less than the first pulse overlap (61).