Laser Focus Calibration Using Incision Width Detection

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Solution Overview

Problem

Existing methods for determining the focus position of a laser beam in laser processing systems are complex and cannot be automated, relying on manual measurement of slit widths in reference workpieces.

Innovation Solution

A method that uses existing components of the laser system to determine the focus position by making multiple incisions in a reference workpiece with varying focus settings, detecting process radiation or reflected laser radiation with sensors, and evaluating edge information to automatically determine the incision width and corresponding focus position.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Extent of automation

If manual measurement of slot width is used to determine focal position, then measurement can be performed with simple equipment, but the method cannot be automated and requires complex manual operations

Engineering Contradiction:

Improveautomation of focus position determinationVSAvoidcomplexity of measurement process

Core Design Contradiction:

Extent of automationVSDevice complexity

Solution Approach 1:

The patent replaces manual mechanical measurement with optical detection using a camera to capture images of incisions. The camera system automatically measures incision widths by analyzing image data, eliminating the need for manual measurement tools and operations while enabling full automation of the focus determination process

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent creates visual copies of the incisions through camera imaging. Instead of directly measuring physical incisions, the system captures optical images that serve as replicas, allowing automated analysis of incision widths through image processing algorithms without physical contact or manual intervention

Inventive Principle:

Principle #26Copying

2Measurement precision

If multiple incisions are made with different focal positions to find the narrowest point, then measurement precision can be improved, but the process becomes more complex and time-consuming

Engineering Contradiction:

Improveprecision of focal position determinationVSAvoidtime for focus calibration

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent makes multiple incisions continuously at different focal positions along the laser beam path without interrupting the process. The laser system automatically adjusts focal position and creates a series of incisions in sequence, allowing continuous data collection for focus determination rather than discrete manual measurements

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

The patent performs preliminary incisions at various focal positions before final focus determination. These preliminary incisions create a set of reference features that are captured in images, allowing the system to pre-establish measurement points and then automatically analyze them to determine the optimal focal position

Inventive Principle:

Principle #10Preliminary action

3Measurement precision

If additional light sources are added to detect incision edges, then detection accuracy can be improved, but the system complexity and cost increase

Engineering Contradiction:

Improveaccuracy of incision edge detectionVSAvoidnumber of additional components

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent uses the laser beam itself as the light source for illumination during the detection phase. The same laser that creates the incisions is used to illuminate them for imaging, eliminating the need for separate illumination sources. The system serves its own detection needs using its existing laser output

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The laser beam performs multiple functions: it creates the incisions through material removal and simultaneously serves as the illumination source for capturing images of those incisions. This multi-functionality eliminates the need for dedicated lighting equipment while maintaining adequate illumination for accurate edge detection

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 simple and automated calibration of the focus position using components already present in the laser system, improving precision and efficiency in workpiece machining processes without the need for additional light sources or complex setups.

Implementation Method 1

When the laser beam hits the material of the plate-like body around the incisions, process radiation and/or reflected laser radiation is produced

Methodology Applied

Scientific EffectReflection: Reflection

Data Source

PatentEP3386675B1Method for determining the reference focal position of a laser beam

Publication Date: 2021.09.22 TRUMPF WERKZEUGMASCHINEN GMBH & CO KG

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AI summary

The invention relates to a method for determining the reference focal position (15) of a laser beam (2) of a laser system (1), comprising the following steps: a) generating at least two recesses (21, 22) by means of the laser beam (2) of the laser beam system (1) in a plate-like body (20), the positions of the different focal positions being controlled for the at least two recesses (21, 22); b. radiating the plate-like body (20) with the laser beam (2); c. detecting the edges of the recesses (21, 22), one or more parameters (30) which are relative to the radiation of the plate-like body are detected; d. determining the width (b) of the incisions (21, 22) using the the detected parameter(s) (30).