Laser Interference Structuring via Variable Distance Optics

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Solution Overview

Problem

Existing laser interference structuring methods require complex adjustments and large volumes, making them unsuitable for compact, mobile applications and unable to easily change the interference period.

Innovation Solution

A method using a diffractive optical element or acousto-optical modulator to split a laser beam into partial beams, which are directed at an angle and focused onto a component surface using a transparent optical element, allowing for easy adjustment of the interference period and compact structure design.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If optical lenses with constant focal length are used to focus partial beams, then the focusing function is achieved, but the interference period cannot be changed without exchanging lenses

Engineering Contradiction:
Improveinterference period adjustmentVSAvoidlens exchange requirement
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent makes the optical system adjustable by allowing the optical element to be positioned at different distances from the diffractive optical element. This dynamic positioning capability enables continuous adjustment of the interference period without requiring physical lens exchanges, thus resolving the contradiction between adaptability and device complexity.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The invention changes the geometric parameter (distance between optical element and diffractive optical element) to achieve different interference periods. By varying this distance parameter, the system can adapt to different structuring requirements without changing the optical components themselves, eliminating the need for lens exchanges.

Inventive Principle:
Principle #35Parameter changes

2Ease of operation

If beam splitters and reflecting elements are used to direct partial beams onto the surface, then the interference structuring is achieved, but the device requires large volume and complex adjustment

Engineering Contradiction:
Improveadjustment simplicityVSAvoidadjustment complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the complex beam splitter and reflecting element subsystem from the optical path. By using a simplified configuration with a single optical element positioned at variable distances, the invention removes the need for complex adjustments of multiple reflecting elements, thus improving ease of operation and reducing device complexity.

Inventive Principle:
Principle #2Taking out (Extraction)

3Volume of moving object

If a compact structure is designed for laser interference structuring, then the volume is reduced, but the ability to adjust interference period is limited

Engineering Contradiction:
Improvedevice volumeVSAvoidinterference period adjustability
Core Design Contradiction:
Volume of moving objectVSAdaptability or versatility

Solution Approach 1:

The patent achieves compactness while maintaining adjustability by making the optical element's position dynamic. The variable distance positioning mechanism allows a compact design without sacrificing the ability to adjust the interference period, as the adjustment is achieved through positional variation rather than through additional optical components that would increase volume.

Inventive Principle:
Principle #15Dynamics

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 a simple, compact, and adaptable laser interference structuring system that can be integrated into mobile devices, allowing for precise control of the interference period and efficient surface structuring with minimal volume and mass.

Implementation Method 1

the laser beam is directed onto a diffractive optical element or an acousto-optical modulator. The diffractive optical element or the acousto-optical modulator is designed in such a way that the laser beam is split into at least two partial beams

Methodology Applied
Scientific EffectDiffraction: Diffraction

Implementation Method 2

A second surface formed opposite to the first surface is inclined at an angle to the optical axis of the laser beam. As a result, the beam direction of the partial beams can be changed by optical refraction.

Methodology Applied
Scientific EffectRefraction: Refraction

Implementation Method 3

A focusing optical lens is arranged in the beam path of the partial beams between the further optical element(s) and a component surface to be processed. The partial beams are thus focused in such a way that they impinge on the surface of the component at a common position

Methodology Applied
Scientific EffectFocusing: Lens

Implementation Method 4

forming a structure on surfaces of components using a laser beam

Methodology Applied
Scientific EffectLaser ablation: Laser Ablation

Implementation Method 5

The laser beam should be emitted from a pulsed laser beam source. Pulse durations can be selected in the nanosecond range down to the even smaller picosecond range.

Methodology Applied
Scientific EffectLaser: Laser

Data Source

PatentEP2976176B1Method and device for forming a structured surface by means of a laser beam
Publication Date: 2018.10.03 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV
  • EP2976176B1 patent drawingFigure 1
  • EP2976176B1 patent drawingFigure 2
  • EP2976176B1 patent drawingFigure 3

AI summary

The invention relates to a method for forming a structuring on surfaces of components by means of a laser beam. In the case of the invention, a laser beam is directed onto a diffractive optical element. The diffractive optical element is designed such that the laser beam is split into at least two partial beams and the partial beams are directed at an angle α relative to the optical axis of the laser beam onto at least one further optical element, the latter being transparent to the laser radiation. The further optical element(s) has/have a first surface and a second surface, which is inclined at an angle relative to the optical axis of the laser beam, at which the beam direction of the partial beams is altered by optical refraction. In the beam path of the partial beams, a focusing optical lens is arranged between the further optical element(s) and a component surface to be processed, and the partial beams are focused such that they impinge on the surface of the component at a common position at an angle ß of incidence relative to the optical axis of the laser beam. The distance d1 between the optical elements is varied in order to vary the interference period.