Protective Window Fouling Detection by Weighted Image Analysis
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Solution Overview
Problem
Existing methods for determining the fouling of protective glasses in laser processing machines lack selectivity, leading to unnecessary interruptions or failure to detect detrimental fouling, as they do not differentiate between types of fouling.
Innovation Solution
A method and machine that illuminate the transmissive element, analyze the image using a camera, and calculate an optical element fouling value by weighting pollution based on its distance from the laser beam intersection point, considering pollution impact on the laser beam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a threshold value is set for scattered light detection, then the method can detect fouling, but either operation is unnecessarily interrupted (low threshold) or detrimental fouling is not detected (high threshold)
Solution Approach 1:
The patent applies local quality by differentiating the importance of fouling at different locations on the protective glass. Pollution near the laser beam intersection point is weighted more heavily than pollution at the periphery. This resolves the contradiction by enabling selective detection: the system can set higher overall thresholds without missing critical fouling, because central pollution receives disproportionate weight in the evaluation, reducing false negatives while avoiding unnecessary interruptions from peripheral dust.
Solution Approach 2:
The patent changes the parameter of fouling evaluation from a simple binary threshold detection to a weighted quantitative assessment. By introducing position-dependent weighting factors and calculating a weighted sum of pollution areas, the system transforms the detection parameter from uniform to spatially varying. This allows the threshold to be set higher overall while still reliably detecting detrimental central fouling, resolving the contradiction between reliability and productivity.
2Productivity
If visual inspection is replaced by sensor-based scattered light detection, then inspection efficiency is improved, but selectivity in detecting detrimental fouling is lost
Solution Approach 1:
The patent restores selectivity to the automated sensor system by implementing local quality weighting. The evaluation function assigns different weights to pollution areas based on their position relative to the laser beam intersection point. This allows the high-speed sensor-based inspection to maintain efficiency while regaining the ability to selectively identify detrimental fouling patterns that would affect laser processing quality.
Solution Approach 2:
The patent enhances the sensor-based detection system by substituting simple threshold comparison with a more sophisticated image analysis and weighted calculation system. Instead of directly replacing visual inspection with basic photodiode detection, the system uses camera-based imaging combined with computational weighting to achieve both automation and selectivity, resolving the contradiction between inspection efficiency and measurement precision.
3Reliability
If protective glass is inspected regularly, then equipment damage is prevented, but production time is lost during inspection and cleaning
Solution Approach 1:
The patent changes the inspection parameter from uniform threshold-based detection to position-weighted quantitative assessment. This enables more accurate determination of when cleaning is actually needed, reducing false positives that would trigger unnecessary cleaning operations. By weighting central pollution more heavily, the system can maintain equipment protection while reducing inspections that would not lead to actual quality issues.
Solution Approach 2:
The patent implements a feedback mechanism where the weighted fouling assessment informs cleaning decisions. The system continuously monitors and calculates the weighted pollution metric, providing feedback on the actual risk level. This feedback loop allows production to continue when pollution is minimal or peripheral, and only interrupts when the weighted assessment indicates genuine risk, thus protecting equipment while minimizing time loss.
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
Provides a reliable and selective assessment of fouling, reducing unnecessary interruptions and ensuring the quality of laser processing by accurately determining when cleaning or replacement is needed.
Implementation Method 1
an illumination of the protective glass in combination with sensors (such as photodiodes) that detect scattered light. The higher the fouling, the more scattered light is detected.
Data Source
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AI summary
The present disclosure concerns a method of determining the degree of fouling of a transmissive element of a laser processing machine (for example a protective window facing the workpiece), through which transmissive element in use a laser beam is directed. The method comprises illuminating the transmissive element and taking an image (50), for example by a camera, of the illuminated transmissive element. The image will represent pollution of the transmissive element. The image is analyzed for calculating an optical element fouling value that is a quantitative measure of the degree of fouling. In this calculation, the distance of the pollution to an intersection position of the laser beam propagation axis through the transmissive element is taken into account in that the pollution is given a weight by that depends on the distance to the intersection position.