Laser Machining Head With Passive Beam Divergence Compensation

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Solution Overview

Problem

High-power laser machining machines face challenges in maintaining stable focal point positions and reducing thermal aberrations due to the high divergence of laser beams from fiber-guided sources, leading to complications in beam deflection and focusing optics design, especially when dealing with output powers exceeding 500 W.

Innovation Solution

A machining head design featuring a deflecting assembly with a planar deflecting mirror and focusing optics made of materials with high thermal conductivity, where the deflecting assembly changes the laser beam's divergence in a power-dependent manner, compensating for thermal effects and minimizing focal point shifts, and utilizing a single aspherical lens for focusing, thereby reducing structural complexity and weight.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If high-power laser beams (>500 W) are used for machining, then productivity and cutting capability are improved, but thermal stress on optical elements increases causing focal point instability and thermal aberrations

Engineering Contradiction:

Improvecutting capabilityVSAvoidfocal point stability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent changes the material parameter of the focusing optics from conventional low thermal conductivity materials to high thermal conductivity materials (such as copper or copper alloys), fundamentally altering the thermal management characteristics of the optical system to handle high-power lasers effectively

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces active cooling mechanisms with passive thermal conduction through the focusing optics themselves, using the high thermal conductivity material to naturally conduct heat away from the focal point without requiring complex active cooling systems

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If fiber-guided laser sources are used, then ease of operation and beam delivery flexibility are improved, but beam divergence increases leading to focal point shifts and thermal aberrations

Engineering Contradiction:

Improvebeam delivery flexibilityVSAvoidfocal point position accuracy

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The patent changes the material parameter of the focusing optics to high thermal conductivity materials that can handle the divergent beam from fiber sources, maintaining focal point stability despite the increased beam divergence characteristic of fiber-guided lasers

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If conventional focusing optics materials are used, then ease of manufacture is improved, but thermal conductivity is insufficient leading to thermal aberrations at high power

Engineering Contradiction:

Improveoptics fabricationVSAvoidthermal conductivity

Core Design Contradiction:

Ease of manufactureVSTemperature

Solution Approach 1:

The patent employs copper or copper alloys as focusing optics materials, utilizing their superior thermal conductivity properties to manage heat effectively in high-power laser applications, replacing conventional optical materials that lack sufficient thermal management capabilities

Inventive Principle:

Principle #40Composite materials

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 design achieves a compact, lightweight machining head with minimal adjustment effort, ensuring high process reliability and dynamic performance by stabilizing thermal states and reducing aberrations, allowing for effective beam shaping and monitoring across the entire power range.

Implementation Method 1

the changes in the divergence of the working laser beam 6, which are caused due to thermal stress

Methodology Applied

Scientific EffectThermal stress: Thermal Expansion

Implementation Method 2

The focusing optics focus the laser beam in a focal point and thereby generate the intensity required for the cutting process

Methodology Applied

Scientific EffectFocusing: Focusing

Implementation Method 3

focusing optics made of materials with high thermal conductivity

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS11135676B2Machining head for laser machining machine, and laser machining machine

Publication Date: 2021.10.05 BYSTRONIC LASER AG

AI summary

The invention relates to a machining head (1) for laser machining machines, in particular for laser cutting machines, having an interface to a laser light source (3), preferably to fiber-coupled or fiber-based laser sources. Said laser sources are designed for more than 500 W of average output power in the near infrared region. The interface is preferably designed for coupling an optical waveguide (2) for the working laser beam (6). The machining head (1) also has a focusing optical unit (11) having preferably only one imaging lens. A deflecting assembly (9, 10) for at least one single deflection of the working laser beam (6) is arranged between the interface and the focusing optical unit (11). Said deflecting assembly (9, 10) is designed as a passive optical element that changes the divergence of the working laser beam (6) in dependence on power.