Laser Marking Color Gamut via Multi-Objective Optimization

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Solution Overview

Problem

Current methods for creating colored laser markings on metals like stainless steel and titanium are inefficient due to the complex relationship between laser parameters and resulting colors, relying on trial and error and neglecting many design parameters, which limits the versatility and accuracy of color reproduction.

Innovation Solution

A data-driven method that explores the performance space of a laser marking system using a multi-objective optimization algorithm, iteratively marking and measuring samples to determine a Pareto front of optimal design parameters, allowing for the creation of a dense set of diverse, high-resolution colors and enabling color image reproduction on metal surfaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If trial and error measurements are used to find design parameters for colored laser marking, then some primary colors can be marked, but the relationship between device design space and performance space remains unknown and complex

Engineering Contradiction:
Improvecolor reproduction capabilityVSAvoidcomplexity of laser parameter relationships
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent implements a feedback loop where laser markings are systematically created with varying parameters, measured to determine color properties, and the results are stored to build a lookup table. This feedback mechanism allows the system to learn the relationship between laser parameters and color output, resolving the complexity by converting it into a data-driven model that can predict color results without requiring complex physics-based calculations.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent creates a computational model (lookup table) that copies and stores the relationship between laser parameters and color outcomes. Instead of attempting to mathematically model the complex physical processes, the system creates a data structure that replicates the input-output relationship, allowing for efficient prediction and control of color laser marking results.

Inventive Principle:
Principle #26Copying

2Measurement precision

If uniform sampling of process parameter space is performed, then some color information can be obtained, but the high-dimensional design space is too large and many parameters are ignored

Engineering Contradiction:
Improvecolor measurement accuracyVSAvoidefficiency of parameter exploration
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The patent segments the high-dimensional parameter space into a structured grid of design points, systematically varying one or two parameters at a time while holding others constant. This segmentation allows comprehensive exploration of the parameter space without requiring uniform sampling of all dimensions simultaneously, making the process manageable and efficient while capturing the essential color-forming mechanisms.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transforms the high-dimensional parameter exploration problem into a series of lower-dimensional problems by fixing certain parameters and varying others. This dimensional reduction strategy allows systematic sampling of the most influential parameters while maintaining computational efficiency, effectively navigating the high-dimensional space through a series of manageable slices.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Adaptability or versatility

If brute-force color gamut exploration is performed, then a limited range of colors can be marked, but the high-dimensional design space causes many design parameters to be neglected

Engineering Contradiction:
Improvecolor gamut rangeVSAvoidnumber of design parameters
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies local quality by focusing the systematic exploration on specific regions of the parameter space that are most likely to produce desirable color results. By identifying and prioritizing certain parameter combinations based on preliminary observations or domain knowledge, the method efficiently explores the most relevant areas of the high-dimensional space without uniformly sampling all possibilities, thus capturing diverse colors while managing parameter complexity.

Inventive Principle:
Principle #3Local quality

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 enables the reproduction of high-resolution, accurate color images on metals by systematically exploring the design space, overcoming the limitations of existing methods and achieving versatile color laser marking.

Implementation Method 1

Laser marking is an environmentally friendly, low maintenance process with no consumables, dyes, or pigments

Methodology Applied
Scientific EffectLaser heating: Laser

Implementation Method 2

Surface oxidation is one of these mechanisms where the heat (generated by a laser) facilitates the reaction of materials with oxygen

Methodology Applied
Scientific EffectOxidation: Oxidation

Implementation Method 3

Oxidation-induced colors are believed to stem from multilayer, heterogeneous mixture of structural colors (based on thin-film interference)

Methodology Applied
Scientific EffectThin-film interference: Interference

Data Source

PatentUS12145386B2Method for creating a colored laser marking
Publication Date: 2024.11.19 UNIVERSITÀ DELLA SVIZZERA ITALIANA (USI)
  • US12145386B2 patent drawing
  • US12145386B2 patent drawing
  • US12145386B2 patent drawing

AI summary

A method for preparing a laser marking system to create a colored laser mark on a specimen by providing a laser marking system and a specimen comprising a surface layer, where the laser marking system has a preset number of laser parameters, and performing an exploration of a first gamut specified by the laser marking system and the specimen. The method further generally comprises creating a design space with a preset number of design points; performing a marking of a sample on the specimen for each design point; measuring the sample using at least one detection device and determining a performance point for each design point; evaluating the performance space with regard to preset performance criteria using an evaluation device; generating an offspring design space with offspring design points; and creating a first gamut using a subset of performance points.