Transparent Substrate Cutting With Defect-Line Edge Control
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Solution Overview
Problem
Conventional ablative laser cutting processes for transparent substrates like glass result in significant debris, subsurface damage, and require extensive grinding or polishing, making the manufacturing process complex and costly, especially for applications requiring defect-free edges and surfaces.
Innovation Solution
A non-ablative process using a pulsed laser beam to induce nonlinear absorption in the substrate, creating a defect line through the entire thickness without filamentation, allowing for precise cutting and removal of interior portions with minimal damage by heating the substrate along the defect line to propagate a crack and isolate the plug.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ablative laser cutting process is used, then material can be removed layer by layer, but significant subsurface damage and debris are generated requiring extensive grinding or polishing
Solution Approach 1:
The patent changes the fundamental laser processing parameters by using ultrashort pulsed laser (picosecond or femtosecond duration) at wavelengths where the glass is transparent (e.g., 1064 nm), combined with high peak power to induce nonlinear optical absorption. This creates a different material removal mechanism that forms clean defect lines without the subsurface damage characteristic of conventional ablative processes, eliminating the need for extensive grinding or polishing
Solution Approach 2:
Instead of directly ablating material from the surface as in conventional laser cutting, the patent inverts the approach by using the substrate's transparency at the laser wavelength to guide the beam through the entire thickness, creating defect lines that naturally separate when heated. This indirect approach produces cleaner edges with minimal subsurface damage
2Productivity
If conventional laser ablation is used, then cutting can be achieved, but significant debris is generated that contaminates the major surfaces
Solution Approach 1:
The patent converts the substrate's transparency, which would normally prevent laser absorption, into a benefit by using nonlinear optical absorption at high peak powers. The transparency allows the laser to penetrate through the entire thickness without generating surface debris, while the nonlinear absorption at the focal line enables precise material modification without contamination
3Manufacturing precision
If multiple laser passes are used to remove material layer by layer, then complete cutting is achieved, but processing time increases significantly
Solution Approach 1:
The patent performs preliminary action by creating defect lines through the entire thickness of the substrate in a single pass using ultrashort pulsed laser. These pre-formed defect lines require no further material removal, and the subsequent heating step simply propagates cracks along these lines to achieve complete separation, dramatically reducing processing time compared to multiple ablation passes
4Ease of operation
If laser filamentation process is used, then self-focusing occurs, but the process depends on substrate properties and generates uncontrolled damage
Solution Approach 1:
The patent introduces an intermediary optical element (axicon lens or diffractive optical element) that mediates the laser beam transformation into a Bessel beam with a long focal line. This intermediary enables controlled energy deposition throughout the substrate thickness without relying on substrate-induced self-focusing, providing precise control over the defect line formation while minimizing uncontrolled damage
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 method reduces subsurface damage, minimizes debris, and simplifies the manufacturing process by achieving clean, defect-free edges and surfaces with reduced need for grinding or polishing, enabling precise cutting of complex shapes in transparent materials like glass.
Implementation Method 1
inducing nonlinear absorption in the material to be processed by directing a laser beam of sufficient intensity at the substrate, wherein the substrate would be substantially transparent to the laser beam at a lesser intensity
Implementation Method 2
The cutting comprises producing a linear focus line within the transparent substrate that produces damage along the focus line, thereby creating a defect line
Implementation Method 3
heating the substrate along the first predetermined path to propagate a crack through each defect line of the first plurality of locations
Implementation Method 4
cooling the interior plug after the isolating to remove the plug from the substrate
Data Source
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AI summary
A method for cutting, separating and removing interior contoured shapes in thin substrates, particularly glass substrates. The method involves the utilization of an ultra-short pulse laser to form defect lines in the substrate that may be followed by use of a second laser beam to promote isolation of the part defined by the interior contour.