Laser-Excited Fluid Surface Treatment With Low Thermal Damage
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Solution Overview
Problem
Existing surface treatment methods, such as reactive ion etching and laser ablation, face challenges including high energy input, thermal damage, and limited control over the shape and geometry of material removal, which complicates the processing of solid surfaces and can result in undesirable material changes and structural limitations.
Innovation Solution
A method using ultra-short laser pulses with a power density greater than 10^13 W/cm^2 and pulse energies less than 10 mJ to excite a fluid reaction medium, which interacts with the solid surface at a distance, minimizing thermal influence and allowing precise control over the interaction area and shape through nonlinear absorption processes and movement of the laser focus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If direct laser irradiation of the workpiece surface is used, then material removal efficiency is improved, but thermal damage and inhomogeneous temperature increase occur
Solution Approach 1:
The patent introduces a fluid reaction medium as an intermediary between the laser beam and the workpiece surface. The laser irradiates the fluid medium, which then interacts with the workpiece surface to achieve material removal. This mediator approach allows the laser energy to be converted into chemical reactions in the fluid medium, which subsequently react with the workpiece, thereby avoiding direct thermal exposure of the workpiece to high-power laser radiation and preventing thermal damage while maintaining material removal efficiency.
2Productivity
If plasma generation using electric fields is used, then material removal is achieved, but vacuum maintenance and electrode insertion are required
Solution Approach 1:
The patent replaces the traditional electric field-based plasma generation mechanism with a laser-induced chemical reaction mechanism in a fluid medium. Instead of using electrodes and vacuum systems to generate plasma, the invention uses laser radiation to activate chemical reactions in the fluid medium, which then interact with the workpiece surface. This substitution eliminates the need for complex vacuum maintenance measures and electrode insertion, simplifying the device while maintaining material removal capability.
3Object-affected harmful factors
If laser focus is placed at a distance from the workpiece surface, then thermal influence is minimized, but interaction effectiveness with the workpiece surface is reduced
Solution Approach 1:
The fluid reaction medium serves as an intermediary that bridges the gap between the laser focus and the workpiece surface. By placing the laser focus at a distance in the fluid medium, thermal influence on the workpiece is minimized. The activated fluid medium then chemically reacts with the workpiece surface, enabling effective material removal or modification without direct thermal exposure. This intermediary approach allows optimization of both thermal management and interaction effectiveness.
4Power
If high power density is used for laser activation, then reaction medium excitation is improved, but risk of workpiece damage increases
Solution Approach 1:
The fluid reaction medium acts as a buffer and intermediary that allows the use of high power density laser radiation without directly exposing the workpiece to such intense energy. The laser activates the fluid medium through chemical reactions, and these activated species then interact with the workpiece surface. This intermediary mechanism enables high power density to be utilized effectively for driving the chemical reactions while the workpiece is protected from direct laser-induced damage, thereby improving both reaction efficiency and workpiece integrity.
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 minimizes laser-induced material changes, decouples photon absorption from the workpiece properties, and enables precise surface treatment with reduced risk of damage, allowing for efficient material removal, deposition, or modification of surfaces without the need for direct laser irradiation, and can be applied to inaccessible areas.
Implementation Method 1
excitation of the reaction medium takes place through nonlinear absorption processes
Implementation Method 2
irradiating the fluid reaction medium in the processing zone with laser radiation
Implementation Method 3
the fluid reaction medium excited by the laser radiation interacts with the solid surface in the processing zone
Data Source
Figure 1~2
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AI summary
The invention relates to a method for treating a solid surface, comprising the following steps: (a) providing a fluid reaction medium, (b) supplying the fluid reaction medium to the solid surface, at least in a processing zone, and (c) irradiating the fluid reaction medium in the processing zone with laser radiation, the laser focus of which is arranged at a distance from the solid surface within the fluid reaction medium, such that the fluid reaction medium excited by the laser radiation interacts with the solid surface in the processing zone. The object of the invention is to propose a method for treating a solid surface in which the thermal influence on the workpiece is low and the structural dimensions achievable on the surface of the workpiece are minimized. Furthermore, the possibilities for influencing the shape and geometry of the interaction with the workpiece are to be increased.This problem is solved by the fact that the laser radiation (B11) has a pulse duration of less than 50 ps, a power density of greater than 1013 W/cm² in the laser focus (B15), and a pulse energy of less than 10 mJ, and that the laser focus (B15) is arranged at a distance of greater than 10 µm from the solid surface (A11). (Fig. 1).