Laser Material Processing Overlapping Interaction Zones
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Solution Overview
Problem
Existing laser surgical methods for creating curved cut surfaces in transparent materials, such as in ophthalmology, face challenges in achieving high accuracy and minimizing collateral damage, with issues related to plasma bubble merging and cut quality, particularly due to the sequential generation of optical breakthroughs and the need for high pulse energy.
Innovation Solution
The method involves controlling the distance and fluence of pulsed laser radiation to minimize interaction zone overlap, reducing pulse energy, and adjusting the scanning pattern to ensure adjacent interaction centers are close enough to reduce plasma bubble size and enhance cutting precision, allowing for the use of lower hazard class lasers and achieving a finer cut surface without plasma bubble formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high pulse energy is used to create optical breakthroughs and plasma bubbles, then material separation is achieved, but plasma bubbles merge and cut quality deteriorates
Solution Approach 1:
The patent changes the pulse energy parameter from high to low levels. By using low pulse energy, the patent prevents plasma bubble formation and merging while still achieving material separation through cumulative thermal effects from multiple low-energy pulses applied in sequence.
Solution Approach 2:
The patent applies periodic low-energy pulses rather than single high-energy pulses. Multiple pulses are applied at regular intervals to the same location, allowing heat to accumulate and eventually separate the material without creating harmful plasma bubbles that would merge and degrade cut quality.
2Productivity
If high pulse energy is used to achieve material separation, then cutting is effective, but collateral damage to adjacent tissue increases
Solution Approach 1:
The patent changes the pulse energy parameter from high to low. Low-energy pulses reduce collateral thermal damage to adjacent tissue while maintaining cutting effectiveness through cumulative heating from multiple pulses applied in sequence to the same location.
Solution Approach 2:
The patent applies preliminary low-energy pulses that prepare the material by gradually heating it without causing damage. These preliminary pulses raise the temperature of the target material to a level where subsequent pulses can achieve clean separation with minimal collateral damage.
3Object-generated harmful factors
If interaction zones are spaced far apart to avoid overlap, then plasma bubble merging is prevented, but cut continuity is compromised
Solution Approach 1:
The patent changes the energy parameter from high to low, allowing interaction zones to be placed closer together without creating plasma bubbles. The low energy per pulse prevents bubble formation even when zones overlap, while the cumulative thermal effect from multiple pulses ensures continuous and clean material separation.
4Object-affected harmful factors
If pulse energy is reduced to minimize damage, then collateral damage decreases, but optical breakthrough threshold is not exceeded
Solution Approach 1:
The patent uses periodic application of low-energy pulses rather than single high-energy pulses. Each individual pulse remains below the optical breakthrough threshold, preventing plasma formation and collateral damage. However, the repeated application of pulses to the same location causes heat to accumulate, eventually reaching temperatures sufficient for clean material separation.
Solution Approach 2:
The patent maintains continuous useful action by applying multiple low-energy pulses in sequence without interruption to the same target location. This continuous heating process reliably achieves material separation through thermal accumulation, providing consistent and predictable cutting results without relying on stochastic optical breakthrough events.
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 approach results in improved cut quality with reduced collateral damage, lower pulse energy requirements, and the ability to use safer laser classes, enabling more precise and efficient material processing while maintaining high accuracy, even in complex geometries like the cornea.
Implementation Method 1
the threshold value for the energy density required to trigger an optical breakthrough is only exceeded in the individual pulses
Implementation Method 2
The optical breakthrough first creates a plasma bubble in the material
Implementation Method 3
If a plasma is generated at a material interface, which can also lie within a material structure, material is removed from the interface. This is then referred to as photoablation
Implementation Method 4
an optical system that focuses the pulsed processing laser radiation into the material onto a center of interaction
Implementation Method 5
a scanning device that adjusts the position of the center of interaction in the material
Implementation Method 6
a control device which controls the scanning device and the laser beam source in such a way that a cut surface is formed in the material by lining up interaction zones
Data Source
Figure 1~2
Figure 3~5
Figure 6~7
AI summary
In a device for material processing using laser radiation, comprising an emitting laser beam source (S) that emits pulsed laser radiation (3) for interaction with the material (5), optics (6) that focus the pulsed laser radiation (3) into the material (5) onto an interaction center (7), wherein the laser pulses interact with the material (5) in the zones (8) surrounding the respective interaction centers (7), so that material (5) is separated in the interaction zones (8), a scanning device (10) that adjusts the position of the interaction center in the material (5), and a control device (17) that controls the scanning device (10) and the laser beam source (S) such that a cut surface (9) is created in the material (5) by arranging interaction zones (8) in succession, it is provided that the control device (17) controls the laser beam source (S) and the scanning device (10) in such a way thatthat the local distance a of the interaction centers (7) of two successive processing laser pulses is smaller than the focus size d, so that successively generated interaction zones (20-24) overlap in the material (5).