Laser Ablation Raster Irregularity for Reduced Diffraction Visibility
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Solution Overview
Problem
Laser ablation processes often result in undesirable diffraction effects on workpieces, particularly visible as diffraction gratings when light interacts with the ablated surfaces of transparent or reflective materials, which can be problematic for applications requiring invisibility or uniform reflectivity.
Innovation Solution
Modifying the laser ablation process by adjusting scan speed, increasing laser pulse frequency, using a defocused beam, employing non-Gaussian or flat energy profiles, and introducing irregularities in the raster patterns, such as non-parallel lines or curvilinear paths, along with the use of index-matching fluids, to reduce the visibility of diffraction gratings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If laser ablation is performed with regular raster patterns and standard parameters, then material removal efficiency is maintained, but diffraction gratings become visible on the ablated surface
Solution Approach 1:
The patent applies asymmetry by using non-parallel raster lines with varying angles and spacings instead of regular parallel lines. This asymmetric pattern disrupts the formation of diffraction gratings while maintaining effective material removal coverage
Solution Approach 2:
The patent implements dynamics by varying laser parameters (pulse frequency, scan speed, power) during the ablation process and using irregular raster patterns that change spacing and orientation, preventing the formation of static diffraction patterns
2Object-affected harmful factors
If laser parameters are adjusted to reduce diffraction visibility, then surface appearance improves, but processing time increases
Solution Approach 1:
The patent applies partial action by using multiple passes with different parameters rather than requiring a single high-quality pass. This allows each pass to be optimized for speed while the cumulative effect achieves the desired surface quality
Solution Approach 2:
The patent utilizes parameter changes by varying laser pulse frequency, scan speed, and power levels between passes and across different regions, enabling optimization of both processing speed and surface appearance through dynamic parameter adjustment
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
These modifications effectively reduce the appearance of diffraction patterns by minimizing residual material and altering the spacing and alignment of laser spots, thereby reducing the intensity and visibility of diffraction gratings, making the ablated surfaces more suitable for transparent and reflective applications.
Implementation Method 1
Laser ablation is a process that has been used to remove material or layers of materials from workpieces
Implementation Method 2
This controlled amount of energy is selected to liquefy, vaporize, or otherwise rapidly expand the surface material at the laser spot
Implementation Method 3
very little is known about the effects of laser ablation on the optical properties of a workpiece or product that has been subjected to a laser ablation process
Data Source
AI summary
A laser ablation process can be configured to reduce the appearance of or eliminate a potentially objectionable diffraction effect that can occur when a workpiece or product that has been subjected to the ablation process interacts with light. The diffraction effect can be reduced by introducing irregularity into the arrangement of overlapping laser spots during the process. Other process parameters may be modified to reduce the diffraction effect, such as laser scan speed, laser pulse frequency, the position of the focal plane of the laser, the configuration of raster lines, or the energy profile of the laser beam, for example. The process modifications and configurations are particularly useful with products including an ablated surface that is intended to reflect light or to allow light to pass therethrough as part of its function.