Laser Polarization Patterning for Omnidirectional Iridescent Surfaces
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Solution Overview
Problem
Current laser treatment methods for achieving an iridescent effect on stainless steel surfaces face challenges in achieving homogeneous treatment over large areas due to limitations in optical field dimensions, leading to non-homogeneous results and visibility issues from directionality of the iridescence, as well as synchronization problems between laser and scanner systems, resulting in 'stitching' and incomplete coverage.
Innovation Solution
The method involves using laser beams with pulse durations less than one nanosecond, scanning the surface in lines or a matrix of points, and modifying the polarization of the laser beam between consecutive lines or points to create wavelets with varying orientations, ensuring uniform iridescence across different angles of observation and minimizing the visibility of junction zones between overlapping fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If laser treatment is applied using conventional optical fields, then treatment can be performed on material surfaces, but the treatment is non-homogeneous over large areas and shows directional dependence
Solution Approach 1:
The patent applies local quality by varying the polarization direction of the laser beam across different regions of the treatment field. By rotating the polarization direction according to a predetermined pattern (e.g., 0°, 45°, 90°, 135° in different zones), each local region receives treatment with optimized wavelet orientation, resulting in homogeneous iridescent effect from all viewing angles across the entire large-area surface
Solution Approach 2:
The patent segments the optical field into multiple polarization zones, where each zone is assigned a specific polarization direction. This segmentation allows different parts of the treatment field to create wavelets with different orientations, eliminating the directional dependence of the iridescent effect and achieving omnidirectional visibility
2Area of stationary object
If multiple overlapping laser fields are used to treat large surfaces, then coverage area increases, but junction zones become visible due to synchronization issues between laser and scanner
Solution Approach 1:
The patent changes the polarization parameter as a function of position across the treatment field, particularly in the overlapping junction zones. By adjusting the polarization direction in these zones according to a predetermined pattern, the wavelet orientation is optimized to match the surrounding areas, making the junction zones invisible and achieving seamless large-area coverage
Solution Approach 2:
The patent applies preliminary action by pre-defining the polarization direction pattern across the entire treatment field before treatment begins. The control system calculates and sets the polarization angles for all zones in advance, ensuring that when multiple laser fields overlap, the junction zones automatically achieve homogeneous appearance without requiring post-treatment 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
This approach achieves a homogeneous, omnidirectional iridescent effect on stainless steel surfaces, reducing the visibility of treatment junctions and enabling the treatment of larger surfaces with improved productivity by ensuring consistent energy distribution and wavelet orientation across the surface.
Implementation Method 1
irradiating the surface of a material with a pulsed laser radiation of short pulse duration
Implementation Method 2
This structure is composed of small wavelets that, in the case of stainless steels, are oriented in the direction of the polarization of the incident laser beam
Implementation Method 3
this periodic organization of the surface allows an induced phenomenon, well known to operators of laser surface treatments, which is the diffraction of light through the creation of an optical network
Implementation Method 4
said optical system comprises a polarization optical system that confers a determined polarization on said beam, and means for varying this polarization
Data Source
AI summary
Method for creating an iridescent visual effect on the surface of a part, using a laser beam having a pulse duration of less than a nanosecond sent onto said surface in the optical field of the focusing system of a device comprising also a laser source and a scanner, to apply wavelets having the same orientation to said surface over the pulse width. The scanner scans the surface using laser radiation along a series of consecutive lines, or a matrix of points using relative movement of said surface and the device, the width of each line or the dimension of each point of each matrix being equal to the pulse diameter. Between the carrying out of the scanning along two consecutive lines or two adjacent points the polarization of the laser beam is modified to create wavelets having different orientations on two consecutive lines or two adjacent points.