Laser Machining Transparent Materials via Temporal Pulse Shaping
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for precise material processing in transparent materials using nanosecond pulses face challenges due to random and destructive plasma formation, making it difficult to achieve localized and reproducible energy deposition without causing extensive damage.
Innovation Solution
Identifying a specific radiation intensity range below the optical breakthrough threshold for nanosecond pulses, where material changes occur without plasma formation, allowing for precise localization and reproducibility by using temporally smooth laser pulses with adjustable irradiance to avoid plasma formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If nanosecond laser pulses are used for material processing in transparent materials, then the system complexity and cost are reduced, but plasma formation occurs causing random and destructive effects that reduce manufacturing precision
Solution Approach 1:
The patent applies parameter changes by modifying the temporal profile of the laser pulse from a standard shape to a specifically shaped profile with controlled rise and fall times. This shaping allows the pulse to stay below the plasma formation threshold while still delivering sufficient energy for material processing, thereby maintaining precision without requiring complex ultrashort pulse systems.
Solution Approach 2:
The patent uses partial action by delivering laser energy in a controlled manner that accumulates below the plasma threshold. Instead of using high peak power that would cause plasma, the shaped pulse delivers energy more gradually, achieving the desired material effect through cumulative heating without the harmful plasma phase.
2Manufacturing precision
If high energy density is deposited to achieve precise material changes, then manufacturing precision is improved, but heat diffusion occurs reducing reliability
Solution Approach 1:
The patent applies dynamics by continuously optimizing the laser pulse shape parameters (rise time, peak duration, fall time) based on the specific material and processing requirements. This dynamic adjustment allows the system to maintain optimal energy deposition profiles that achieve precise localization while preventing heat diffusion, ensuring reliable and reproducible results across different materials and conditions.
3Manufacturing precision
If ultrashort laser pulses are used to avoid heat diffusion, then manufacturing precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent substitutes the mechanical/physical approach of using ultrashort pulses (requiring complex mode-locking lasers) with an optical approach using shaped nanosecond pulses. By controlling the temporal profile of the pulse, the system achieves similar precision effects without the need for complex ultrashort pulse generation equipment, replacing a mechanically complex system with a more manageable optical control system.
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 and reproducible material processing with nanosecond pulses by maintaining spatial localization and avoiding far-reaching damage, with a wider usable energy range and lower peak power compared to femtosecond pulses, while being more cost-effective and compact.
Implementation Method 1
localized energy deposition can only occur through nonlinear absorption, i.e. through multiphoton processes in the form of multiphoton ionization and avalanche ionization
Implementation Method 2
multiphoton processes in the form of multiphoton ionization and avalanche ionization
Implementation Method 3
multiphoton processes in the form of multiphoton ionization and avalanche ionization
Implementation Method 4
the plasma formation process in this parameter range is also called 'optical breakthrough'
Implementation Method 5
the pulsed laser light creates bubbles in the immediate vicinity of the cell
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3
AI summary
The invention relates to a method for machining a transparent material by the non-linear absorption of pulsed laser radiation, in the region of a laser focus, said method comprising the following steps: a laser wavelength of between 300 and 1000 µm is selected; and laser impulses having a temporally flat beam profile are applied. The method is characterised in that the irradiation intensity is selected from an interval pre-determined for the material to be machined, in which plasma is formed without plasma luminescence.