Laser Cutting Thermally Tempered Glass via Multi-Photon Absorption
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Solution Overview
Problem
Thermally tempered glass is difficult to cut due to its high stress profile, leading to fragmentation when conventional cutting methods are used, limiting its availability to specific stock sizes and inhibiting flexibility and cost-effectiveness in custom applications.
Innovation Solution
A method and system utilizing a focused pulsed laser beam to create damage tracks within the glass, inducing multi-photon absorption and controlled microcrack propagation, allowing precise cutting without de-tempering the glass.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional cutting methods are used on thermally tempered glass, then the glass can be cut to shape, but the built-in stress is released causing fragmentation of the whole sheet
Solution Approach 1:
The laser beam is focused into a line rather than a point, creating multiple damage tracks along the focal line. This segments the cutting process into discrete tracks that guide microcrack propagation without releasing stress across the entire sheet, preventing fragmentation while enabling cutting.
Solution Approach 2:
The laser processing creates localized damage tracks with specific lateral spacing within the bulk of the glass. This local modification of the glass structure at precise locations enables controlled microcrack propagation along the desired cut path while leaving the rest of the glass structure intact and stress-preserving.
2Ease of manufacture
If thermally tempered glass is cut before thermal tempering, then cutting can be performed without fragmentation, but the glass is only available in limited stock sizes reducing flexibility
Solution Approach 1:
The laser creates damage tracks and initiates microcrack propagation in advance along the desired cut path through the tempered glass. This preliminary damage structure guides subsequent crack propagation to follow the intended path, enabling cutting of custom sizes from large stock sheets without requiring pre-cutting to limited stock sizes.
3Productivity
If conventional laser cutting is attempted on thermally tempered glass, then cutting speed may be achieved, but the high stress causes uncontrolled crack propagation and shattering
Solution Approach 1:
The laser operates in pulsed mode, delivering periodic energy bursts that create discrete damage tracks at controlled intervals. This periodic action allows the glass structure to respond to each pulse individually, enabling controlled microcrack propagation between pulses while maintaining high cutting speed through rapid pulsing sequences.
Solution Approach 2:
The laser beam is focused into a line extending in the depth direction rather than concentrating energy at a single point on the surface. This dimensional change creates damage tracks throughout the bulk of the glass, guiding microcrack propagation in three dimensions and providing precise control over the cut path while maintaining high processing speed.
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
Enables precise cutting of thermally tempered glass with minimal subsurface damage and debris, allowing for custom shapes and increased material utilization while preventing shattering during the cutting process.
Implementation Method 1
The laser beam focal line generates an induced multi-photon absorption within the thermally tempered substrate that produces a damage track within the bulk of the thermally tempered substrate along the laser beam focal line
Implementation Method 2
one or more microcracks connect adjacent damage tracks of the first sequence of damage tracks
Data Source
Figure 1A~1B
Figure 2A
Figure 2B-1~2B-4
AI summary
Systems and methods for laser-cutting thermally tempered substrates are disclosed. In one embodiment, a method of separating a thermally tempered substrate includes directing a laser beam focal line such that at least a portion of the laser beam focal line is within a bulk of the thermally tempered substrate. The focused pulsed laser beam is pulsed to form a sequence of pulse bursts comprising one or more sub-pulses. The laser beam focal line produces a damage track within the bulk of the tempered substrate along the laser beam focal line. Relative motion is provided between the focused pulsed laser beam and the tempered substrate such that the pulsed laser beam forms a sequence of damage tracks within the tempered substrate. Individual damage tracks of the sequence of damage tracks are separated by a lateral spacing, and one or more microcracks connect adjacent damage tracks of the sequence of damage tracks.laser cutting of thermally tempered substrates using the multi photon absorption method