Optical Element Contamination Mapping by Variable Beam Diameter
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Solution Overview
Problem
Laser processing devices suffer from contamination of optical elements, which can lead to impaired processing results and unnecessary downtime due to the inability to accurately assess the location and extent of contaminants on these elements.
Innovation Solution
A method involving multiple measurements of scattered light from an optical element with varying laser beam diameters to determine location-dependent contamination, allowing for improved assessment and decision-making on the feasibility of laser processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single integral measurement of scattered light is performed, then the overall contamination level is detected, but location-specific information about contaminants is lost
Solution Approach 1:
The optical element's surface is divided into multiple measurement zones (e.g., central area and peripheral areas). Multiple scattered light measurements are performed at different locations and/or with different laser beam diameters to obtain spatially resolved contamination information. This segmentation allows identification of whether contaminants are located in critical central regions or less critical peripheral regions, enabling more informed decisions about continued operation.
2Reliability
If laser processing is stopped upon detecting any contaminant, then processing quality is maintained, but unnecessary downtime occurs when contaminants are in non-critical areas
Solution Approach 1:
Different evaluation criteria are applied based on the location of detected contaminants. Contaminants in the central laser beam path are evaluated more strictly than those in peripheral areas. If contaminants are found only in non-critical peripheral zones, laser processing can continue with maintained quality, avoiding unnecessary downtime. This location-dependent quality assessment optimizes both reliability and productivity.
3Loss of information
If multiple measurements with different beam diameters are performed, then location-dependent contaminant information is obtained, but measurement time and complexity increase
Solution Approach 1:
Instead of performing exhaustive measurements across the entire optical element surface, the method focuses measurements on critical zones using selectively adjusted laser beam diameters. By targeting only relevant measurement areas and using a limited number of beam diameter settings (e.g., two to four different diameters), the method obtains sufficient spatial information while minimizing measurement time and complexity.
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
Enables higher availability and quality of laser processing by providing spatially resolved information on contaminants, minimizing unnecessary downtime and optimizing processing decisions based on contamination location.
Implementation Method 1
scattered light emanating from the optical element is measured with an optical sensor
Data Source
AI summary
A method for checking an optical element of a laser processing device for contaminants is provided. A laser beam passes through the optical element. The method includes measuring scattered light emanating from the optical element by an optical sensor. N individual measurements are carried out, where N≥3. During each respective individual measurement i, the laser beam passes through the optical element. The scattered light emanating from the optical element is measured by the optical sensor. A respective signal strength Si is determined at the optical sensor. For the N individual measurements i, different diameters Di of the laser beam at the optical element are set. The method further includes ascertaining information about a location-dependent contaminant of the optical element based on the signal strengths Si of the N individual measurements, where i=1 . . . N and i is a measurement index.