Spatial Frequency Filter Assembly for Overlapping Laser Beam Components

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Solution Overview

Problem

Existing spatial frequency filters struggle to effectively filter out unwanted beam components that overlap with the main or useful beam, leading to interference and potential damage to downstream components.

Innovation Solution

A spatial frequency filter arrangement with a neutral region and a deflection region that includes a constant section for reliable deflection and a variation section for gradual filtering, allowing for precise separation of unwanted beam components without adversely affecting the main beam.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a diffractive aperture is used to filter unwanted light components, then unwanted beam components can be effectively diffracted into well-defined solid angles, but unwanted beam components that overlap with the main beam cannot be filtered out

Engineering Contradiction:
Improvefiltering effectivenessVSAvoidcapability to filter overlapping components
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The spatial frequency filter device segments the aperture into distinct functional regions: a neutral region that transmits the main beam and a deflection region that deflects unwanted components. This segmentation allows the device to handle both well-separated and overlapping unwanted components by applying different optical treatments to different spatial frequency components of the input beam

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The deflection region incorporates a deflection structure with locally varying properties - a constant section for components sufficiently separated from the main beam and a variation section for components close to or overlapping with the main beam. This local quality variation enables tailored deflection strategies for different types of unwanted components

Inventive Principle:
Principle #3Local quality

2Ease of manufacture

If a uniform deflection structure is used across the entire aperture, then manufacturing is simplified, but unwanted components close to the main beam cannot be gradually filtered without affecting the main beam

Engineering Contradiction:
Improveaperture fabrication simplicityVSAvoidfiltering precision for overlapping components
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The deflection region is segmented into a constant section with uniform deflection properties and a variation section with gradually changing deflection properties. This segmentation maintains manufacturing feasibility while enabling precise control over the deflection of unwanted components at different radial positions

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The deflection structure in the variation section exhibits parameter changes - specifically, the deflection angle or deflection strength varies continuously from the neutral region boundary outward. This parameter variation allows gradual filtering of unwanted components without abrupt changes that would affect the main beam

Inventive Principle:
Principle #35Parameter changes

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 filter arrangement efficiently separates unwanted beam components from the main beam, ensuring minimal interference and enabling effective filtering of components that overlap or are close to the main beam, while maintaining the integrity of the main beam.

Implementation Method 1

a neutral region (110) configured to transmit or reflect the laser beam

Methodology Applied
Scientific EffectTransmission:

Implementation Method 2

a neutral region (110) configured to transmit or reflect the laser beam

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 3

an element having an aperture arranged adjacent to the transmission body or integrated into the transmission body. The element has a diffractive and/or refractive deflection structure

Methodology Applied
Scientific EffectDiffraction: Diffraction

Implementation Method 4

an element having an aperture arranged adjacent to the transmission body or integrated into the transmission body. The element has a diffractive and/or refractive deflection structure

Methodology Applied
Scientific EffectRefraction: Refraction

Data Source

PatentEP3956701B1Spatial frequency filter device for use with a laser beam, spatial frequency filter assembly having such a spatial frequency filter device, and method for spatial frequency filtering of a laser beam
Publication Date: 2025.10.01 TRUMPF LASER & SYSTEMTECHNIK SE
  • EP3956701B1 patent drawingFigure 1
  • EP3956701B1 patent drawingFigure 2
  • EP3956701B1 patent drawingFigure 3~4

AI summary

The invention relates to a spatial frequency filter device (100) for use with a laser beam (200), comprising a neutral region (110), which is designed to transmit or to reflect the laser beam (200), and a deflection region (120) which radially adjoins the neutral region (110) and is designed to deflect beam components (210) of the laser beam (200) from a beam axis (A) of the laser beam (200). The deflection region (120) has a constant portion (123) in which a deflecting effect on the beam components (210) of the laser beam (200) for each location in the constant portion (123) is independent of a distance of the location from the neutral region (110), and the deflection region (120) has a varying portion (125) in which the deflecting effect on the beam components (210) of the laser beam (200) varies according to a distance from the neutral region (110).