Mid-IR Glass Cutting With Tunable Absorption Depth
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Solution Overview
Problem
Current laser cutting methods for transparent oxide glass result in shallow cracks due to high absorption near the surface, requiring additional processing and leading to imperfect cuts and reduced edge strength, while near-IR lasers face limitations in cutting speed and power requirements.
Innovation Solution
Employing a middle-infrared (mid-IR) laser with tunable wavelength between 2.6 μm and 2.9 μm to achieve controlled depth of heating in the glass, allowing for precise cutting and separation by adjusting the absorption depth from 30 μm to 30 cm, and using a cover substrate with higher mid-IR transmission to direct the laser beam effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If CO2 or CO lasers are used for cutting glass, then high absorption in the glass material is achieved, but the initial crack is shallow and requires additional processing for full separation
Solution Approach 1:
The patent changes the wavelength parameter of the laser from conventional CO2 (10.6 μm) or CO (5.0-6.0 μm) lasers to a mid-IR laser with wavelength between 2.0-3.0 μm. This parameter change exploits the O-H fundamental absorption band in oxide glasses, which has a strong absorption peak at 2.6-2.9 μm. By tuning the laser wavelength within this range, the absorption depth can be controlled to achieve deeper initial cracks while maintaining high energy absorption, thereby resolving the contradiction between energy absorption and crack depth.
2Temperature
If laser wavelength is tuned to absorption band of glass material, then localized heating is achieved, but most oxide glasses need to be transparent in visible wavelength range which limits available laser wavelengths
Solution Approach 1:
The patent transitions from the visible and near-IR wavelength range to the mid-IR range (2.0-3.0 μm), effectively moving to another dimension of the electromagnetic spectrum. This dimensional change in wavelength selection allows access to the O-H fundamental absorption band, which provides strong absorption for localized heating while being independent of the glass's visible transparency requirements. This resolves the contradiction by finding a wavelength regime that satisfies both localized heating needs and glass transparency constraints.
3Productivity
If mid-IR laser with power up to tens of Watts is used, then processing opportunities for transparent oxide glasses are increased, but the absorption curve is sharp requiring precise wavelength selection
Solution Approach 1:
The patent implements feedback control for wavelength tuning, where the laser wavelength is adjusted based on monitoring the absorption characteristics and cutting effectiveness. By using feedback mechanisms to detect the optimal wavelength within the 2.6-2.9 μm range and continuously adjusting to maintain peak absorption, the system achieves precise control despite the sharp absorption curve. This feedback approach enables productive processing while managing the precision requirement through active control.
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 flexible and efficient cutting of transparent oxide glass with improved edge strength and reduced debris, allowing for precise control of heating profiles and increased processing capabilities with mid-IR lasers.
Implementation Method 1
most of the radiation is absorbed only a few μm from the surface of the glass... strong absorption peak at 2.6-2.9 μm in the O—H fundamental absorption band
Implementation Method 2
directing a laser beam from a middle-infrared (mid-IR) laser source onto a major surface of the glass sheet... create a desired temperature profile on the glass surface and inside the thickness of the glass
Implementation Method 3
Cutting glass with lasers typically includes localized heating of the glass resulting in thermal stress in the glass... creating color centers, etc.
Implementation Method 4
the initial crack may be shallow and require additional processing for full separation of the glass segments... cutting the glass sheet using the laser beam
Data Source
AI summary
A method of cutting a glass sheet comprising a transparent oxide glass includes directing a laser beam from a middle-infrared (mid-IR) laser source onto a major surface of the glass sheet. A wavelength of the laser beam is tuned thereby adjusting an absorption depth of the laser beam in the glass sheet. The glass sheet is cut using the laser beam.