Laser Structuring Monitoring With Spatially Resolved Interference Feedback

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Solution Overview

Problem

Existing methods for monitoring direct laser interference structuring processes lack precision in detecting structure position and dimensioning, often requiring complex adjustments and non-compact systems, leading to inefficiencies and laser radiation loss.

Innovation Solution

An optical arrangement with divided laser beams and an integrated optical detector connected to an electronic evaluation and control unit for spatially resolved detection of radiation intensities, allowing for precise regulation of the structuring process and structure formation with minimal adjustment effort, enabling a compact structure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If an additional beam splitter is placed in the beam path to direct a partial beam onto a sensor, then monitoring capability is achieved, but laser radiation is lost and efficiency is reduced

Engineering Contradiction:
Improvestructure position detection accuracyVSAvoidlaser radiation loss
Core Design Contradiction:
Measurement precisionVSLoss of energy

Solution Approach 1:

The laser beam is segmented into multiple partial beams using beam splitters, with one partial beam used for structuring and another partial beam directed to the sensor for monitoring. This allows simultaneous structuring and monitoring without using the entire laser beam for a single purpose.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The optical arrangement serves multiple functions: it performs direct laser interference structuring on the component surface while simultaneously providing monitoring capability through the sensor. The same optical system handles both processing and detection tasks.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Measurement precision

If a sensor is positioned in the beam path with a beam splitter, then monitoring is enabled, but very precise and complex positioning is required

Engineering Contradiction:
Improvestructure position detection accuracyVSAvoidsensor positioning complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

Beam splitters and optical elements act as intermediaries that redirect portions of the laser beam to the sensor without requiring the sensor to be positioned precisely in the main beam path. The optical elements mediate between the laser source and sensor, simplifying sensor positioning.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Loss of energy

If an optical sensor is positioned decoupled from the laser beam, then laser losses are avoided, but the optical setup becomes complex and compact design is not possible

Engineering Contradiction:
Improvelaser radiation lossVSAvoidoptical setup complexity
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The monitoring function is merged with the structuring function by integrating the sensor and optical elements into the same optical arrangement. The beam splitters and optical elements are positioned within the structuring optical path, allowing both structuring and monitoring to occur in a unified, compact system.

Inventive Principle:
Principle #5Merging (Combining)

4Measurement precision

If detectors are arranged in series next to the optical arrangement, then detection is possible, but only refracted laser radiation can be detected and compact design is not possible

Engineering Contradiction:
Improvelaser radiation detection capabilityVSAvoidoptical arrangement complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The detection is performed in a different spatial dimension or direction from the main laser beam path. By using beam splitters to redirect light to the sensor positioned at an angle or different location, the system detects reflected or scattered radiation without requiring detectors in the direct beam path, enabling more flexible and compact arrangements.

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

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 solution provides accurate, efficient, and compact monitoring of direct laser interference structuring processes, allowing for real-time control and adjustment of process parameters to achieve precise structure formation with reduced laser losses and simplified setup.

Implementation Method 1

an arrangement of optical elements which is designed such that a laser beam emitted by a laser radiation source (2) is split into at least two partial beams (1)

Methodology Applied
Scientific EffectBeam splitting:

Implementation Method 2

with beam-splitting, optically refractive, and/or reflective optical elements

Methodology Applied
Scientific EffectRefraction: Refraction

Implementation Method 3

with beam-splitting, optically refractive, and/or reflective optical elements

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 4

the at least two partial beams are directed onto the surface of a component to be structured (3) in such a way that the interference of the at least two partial beams creates a locally defined structure on the respective surface of the component with a predeterminable structure period Λ

Methodology Applied
Scientific EffectInterference: Interference

Implementation Method 5

designed for the spatially resolved detection of intensities of laser radiation reflected at the surface to be structured or already at least partially structured

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 6

or of laser radiation reflected and refracted at the already at least partially structured surface

Methodology Applied
Scientific EffectRefraction: Refraction

Data Source

PatentEP3980217B1Arrangement for monitoring laser structuring processes which are carried out on surfaces of components
Publication Date: 2025.01.15 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV
  • EP3980217B1 patent drawingFigure 1
  • EP3980217B1 patent drawingFigure 2
  • EP3980217B1 patent drawingFigure 3

AI summary

The arrangement for monitoring laser structuring processes which are carried out on surfaces of components is provided with an arrangement of optical elements (9), which arrangement is designed such that a laser beam (2) emitted by a laser radiation source is split into at least two partial beams (1) and the partial beams (1) are directed onto the surface such that, owing to the interference of the at least two partial beams, a locally defined structure on the particular surface of the component (3) is formed having predefinable structural periods Ʌ. An optical detector (4), which is designed for spatially resolved capturing of intensities of laser radiation (5) reflected by the component surface to be structured or an already partially structured component surface, or laser radiation (6) reflected and refracted by the already at least partially structured component surface, is a component of the arrangement of optical elements. The detector (4) is connected to an electronic evaluation and control unit that is designed to control the process of the direct laser interference structuring on the basis of the intensities captured in a spatially resolved manner.