Liquid-Through Laser Peening with Pulse Width and Polarization Control
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Solution Overview
Problem
In laser peening and forming processes, the interaction between high-intensity pulsed laser light and a liquid leads to the formation of an acoustic lattice, causing stimulated Brillouin scattering (SBS) which hinders effective energy utilization of the laser light.
Innovation Solution
A laser processing device and method where the pulse width of pulsed laser light is set between 200 ps to 2 ns, and the laser light is of an unsteady polarization state, such as elliptically polarized or multi-mode, to reduce SBS and enhance energy utilization by minimizing acoustic lattice formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high-intensity pulsed laser light is irradiated through a liquid to perform laser peening or forming, then the processing effect is achieved, but stimulated Brillouin scattering (SBS) occurs due to acoustic lattice formation, reducing laser energy utilization efficiency
Solution Approach 1:
The patent changes the polarization state parameter of the laser light from steady (linearly polarized) to unsteady (elliptically polarized or multi-mode) to suppress acoustic lattice formation and reduce SBS. This parameter change transforms the laser properties to prevent the harmful interaction with the liquid medium while maintaining processing effectiveness.
2Ease of operation
If liquid is injected to the processing region to enable laser peening or forming, then the processing capability is provided, but refraction and reflection occur at the liquid-atmosphere boundary, reducing laser energy efficiency
Solution Approach 1:
The patent introduces a transparent window as an intermediary component between the liquid medium and the atmosphere. This window provides a stable optical interface that eliminates the need for continuous liquid injection while maintaining the liquid's beneficial effects on SBS suppression. The window acts as a mediator that allows laser transmission without the energy losses associated with liquid-atmosphere boundaries.
3Device complexity
If steady linearly polarized laser light is used, then the laser source is simple, but acoustic lattice is easily formed in the liquid, increasing SBS occurrence
Solution Approach 1:
The patent changes the polarization state parameter of the laser light from steady (linearly polarized) to unsteady (elliptically polarized or multi-mode) to suppress acoustic lattice formation and reduce SBS. This parameter change transforms the laser properties to prevent the harmful interaction with the liquid medium while maintaining processing effectiveness.
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 configuration allows for effective use of laser energy in peening and forming processes by reducing SBS, preventing dielectric breakdown, and maintaining high peak intensity, thus ensuring efficient processing without damaging optical components.
Implementation Method 1
an acoustic lattice may be formed in the liquid due to an interaction between the liquid on the processing region and an electric field of the pulsed laser light. When the acoustic lattice is formed in this manner, stimulated brillouin scattering (SBS) occurs
Implementation Method 2
a processing method using a laser peening process is known... The laser peening process is a technology of strengthening a surface of a processing region by using an impact force when irradiating the processing region of a workpiece disposed in a liquid
Implementation Method 3
even when subjecting the processing region to a laser forming process by irradiating the processing region of the workpiece with the high-intensity pulsed laser light through a liquid
Data Source
AI summary
A laser processing device according an embodiment is a laser processing device that irradiates a processing region of a workpiece with pulsed laser light through a liquid to subject the processing region to a laser peening process or a laser forming process. The laser processing device includes: a laser irradiation unit including a laser oscillator that outputs the pulsed laser light; and an accommodation unit that includes an injection port through which the liquid is injected to the processing region, and accommodates the laser irradiation unit. A pulse width of the pulsed laser light is 200 ps to 2 ns, and the pulsed laser light output from the laser oscillator is emitted to the processing region through a liquid that is injected from the injection port.