Sealed Laser Optics With Protective Glasses for Contamination Control

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Solution Overview

Problem

High-power laser machining systems face issues with optical elements being sensitive to contamination, leading to heating, damage, and imaging errors due to materials like quartz glass and zinc sulfide, which are either expensive or inefficient in thermal conductivity and imaging.

Innovation Solution

A composite optical unit with a quartz glass or calcium fluoride optical element protected by sapphire or zinc sulfide protective glasses, enclosed in an airtight holder to prevent contamination and thermal issues, while using materials with high thermal conductivity for the protective glasses to minimize forward scattering and birefringence.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If quartz glass optical elements are used for high-power laser machining, then the optical element can be coated very well and has very good imaging properties, but the optical element is very sensitive to dirt and contamination leading to heating and damage

Engineering Contradiction:
Improveimaging propertiesVSAvoidsensitivity to contamination
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The optical system is divided into separate functional components: a quartz glass optical element for imaging and protective glasses (sapphire or zinc sulfide) for contamination protection. This segmentation allows each component to be optimized for its specific function without compromise.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Protective glasses made of sapphire or zinc sulfide are introduced as intermediary elements between the laser beam path and the quartz glass optical element. These protective glasses prevent direct contact with contamination while allowing laser transmission, thereby protecting the sensitive optical element.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Temperature

If zinc sulfide protective glasses are used, then thermal conductivity is improved, but forward scattering of 2-3% of laser power occurs causing heating of surroundings and adverse effects on machining

Engineering Contradiction:
Improvethermal conductivityVSAvoidforward scattering
Core Design Contradiction:
TemperatureVSObject-generated harmful factors

Solution Approach 1:

The invention changes the material parameters of the protective glasses by offering a choice between sapphire and zinc sulfide, each with different optical and thermal properties. This allows optimization based on specific application requirements, balancing thermal management against optical performance.

Inventive Principle:
Principle #35Parameter changes

3Object-generated harmful factors

If sapphire protective glasses are used, then forward scattering is reduced compared to zinc sulfide, but the material is expensive and difficult to process due to high hardness

Engineering Contradiction:
Improveforward scatteringVSAvoiddifficulty to process
Core Design Contradiction:
Object-generated harmful factorsVSEase of manufacture

Solution Approach 1:

The invention changes the material parameters of the protective glasses by offering a choice between sapphire and zinc sulfide, each with different optical and thermal properties. This allows optimization based on specific application requirements, balancing thermal management against optical performance.

Inventive Principle:
Principle #35Parameter changes

4Temperature

If sapphire optical elements are used, then thermal conductivity is acceptable and scattering is reduced, but the material is anisotropic with birefringence leading to imaging errors

Engineering Contradiction:
Improvethermal conductivityVSAvoidimaging accuracy
Core Design Contradiction:
TemperatureVSManufacturing precision

Solution Approach 1:

The optical system is divided into separate functional components: a quartz glass optical element for imaging and protective glasses (sapphire or zinc sulfide) for contamination protection. This segmentation allows each component to be optimized for its specific function without compromise.

Inventive Principle:
Principle #1Segmentation

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

The solution effectively protects the optical element from contamination, maintains imaging quality, and reduces thermal-related issues, ensuring reliable high-power laser machining with reduced sensitivity to dirt and improved thermal management.

Implementation Method 1

optical imaging is understood to mean that the laser beam is guided onto the workpiece, for example by refraction, reflection, diffraction and/or beam shaping

Methodology Applied
Scientific EffectRefraction: Refraction

Implementation Method 2

ZnS has good thermal conductivity

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 3

the outer edges of which are enclosed in an airtight manner by a holder in such a way that they form an interior space with the holder

Methodology Applied
Scientific EffectPhysical containment: Physical Containment

Implementation Method 4

in the case of a focusing lens made of quartz

Methodology Applied
Scientific EffectFocusing: Focusing

Data Source

PatentEP4034330B1Optical unit for laser machining of a workpiece and laser machining device
Publication Date: 2023.02.08 BYSTRONIC LASER AG
  • EP4034330B1 patent drawingFigure 1~2
  • EP4034330B1 patent drawingFigure 3a~3b
  • EP4034330B1 patent drawingFigure 3c~3d

AI summary

Disclosed is an optical unit for a laser beam for laser machining of a workpiece, in particular for a high-power laser beam, comprising an optical element for the optical imaging of the laser beam, and two protective glasses that are transparent for the laser beam, the outer edges of which protective glasses are enclosed in an airtight manner by a holder in such a way that they form an interior space with the holder, the optical element being arranged in the interior space. Also disclosed is a laser machining device.