Transparent Material Separation With Laser-Induced Chamfered Edges
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Solution Overview
Problem
Current laser technologies face challenges in machining materials with large work angles, as they result in significant aberration of the laser beam, leading to ineffective energy deposition and targeted separation of transparent materials.
Innovation Solution
The use of ultrashort laser pulses with Type III material modifications, introduced at a work angle, to create cracks in transparent materials, allowing for precise separation and formation of chamfers or bevels by promoting crack formation and self-separation without external mechanical or thermal assistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If laser beam is introduced at a work angle for machining material edges, then chamfer and bevel structures can be produced, but significant aberration of the laser beam occurs leading to ineffective energy deposition
Solution Approach 1:
The patent employs dynamic focusing of the laser beam, where the focal point is continuously adjusted along the separation line to maintain optimal focus despite the work angle. This dynamic adaptation allows the laser to effectively machine at various work angles while maintaining precision through real-time focal point optimization
Solution Approach 2:
The patent changes key laser parameters including pulse duration (ultrashort pulses in the picosecond to nanosecond range), pulse energy, and wavelength to overcome the aberration problem. By using ultrashort high-energy pulses, the system maintains effective energy deposition even at work angles where conventional continuous-wave lasers would fail
2Reliability
If conventional laser pulses are used for separating transparent materials, then the materials remain transparent to the laser wavelength, but nonlinear absorption is insufficient for effective machining
Solution Approach 1:
The patent uses periodic ultrashort laser pulses with specific repetition rates to accumulate energy in the transparent material. The pulsed nature allows nonlinear absorption to occur at each pulse while the material cools between pulses, preventing damage accumulation and enabling progressive material modification along the separation line
Solution Approach 2:
The patent fundamentally changes the laser parameters from conventional continuous or long-pulse operation to ultrashort pulses with durations in the picosecond to nanosecond range. This parameter change enables nonlinear absorption in transparent materials by exceeding the material's response time, allowing effective energy coupling despite the material's transparency at the laser wavelength
3Manufacturing precision
If high pulse energy is used to machine transparent materials, then nonlinear absorption occurs, but uncontrolled crack formation and material damage may result
Solution Approach 1:
The patent applies preliminary low-energy pulses to create initial modification zones and stress fields in the transparent material before applying higher energy pulses. This preliminary action prepares the material for controlled fracture by establishing a defined separation path, ensuring that subsequent high-energy pulses produce clean breaks rather than uncontrolled cracking
Solution Approach 2:
The patent maintains continuous laser beam traversal along the separation line with overlapping or adjacent pulse positions. This continuous action ensures uniform energy distribution and progressive material modification along the entire separation path, preventing localized overheating and uncontrolled crack formation while maintaining precise separation geometry
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 enables high-quality separation of transparent materials with controlled crack progression, producing stable and visually appealing edges, even on thick workpieces, by leveraging nonlinear absorption and micro-explosion-induced voids within the material.
Implementation Method 1
The short pulse length and high pulse peak power, or the high pulse energy of a few microjoules to 100 μJ, may lead to nonlinear absorption of the pulse energy within the material
Implementation Method 2
The material modifications are Type III modifications associated with a formation of cracks in the material of the workpiece
Data Source
AI summary
A method for separating a workpiece having a transparent material includes providing ultrashort laser pulses using an ultrashort pulse laser, introducing material modifications into the transparent material of the workpiece along a separation line, and separating the material of the workpiece along the separation line. The laser pulses form a laser beam that is incident onto the workpiece at a work angle. The material modifications are Type III modifications associated with a formation of cracks in the material of the workpiece. The material modifications penetrate two sides of the workpiece that are located in intersecting planes. Separating the material of the workpiece produces a chamfer and/or a bevel. A length of a hypotenuse of the chamfer and/or bevel is between 50 μm and 5000 μm.