Interferometer Module With Adjustable Optical Path for Laser Focus Control

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Solution Overview

Problem

Existing laser processing systems face challenges in maintaining accurate and reliable distance measurements due to uncontrolled variations in the optical path length, which affect the focus of the laser beam, leading to irregularities in the final product quality, and existing solutions like optical coherent tomography (OCT) are costly and complex.

Innovation Solution

A measurement module with an interferometer system that includes a housing, connection ports, and an optical path length regulator system to adjust the optical path length difference between two separate paths, allowing for continuous and accurate distance determination, independent of surface irregularities and deflection system variations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If an optical path length regulator system is not used, then the system structure is simpler, but distance measurement accuracy deteriorates due to uncontrolled optical path length variations

Engineering Contradiction:
Improvedistance measurement accuracyVSAvoidsystem structure complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent introduces an optical path length regulator system as an intermediary component between the laser processing module and the measurement beam path. This regulator actively compensates for optical path length variations caused by deflection system movements, workpiece surface irregularities, and environmental factors, thereby maintaining measurement accuracy without requiring complete system reconfiguration.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent implements a feedback mechanism where the optical path length regulator continuously monitors and adjusts the optical path length based on real-time measurements. The system uses the measured distance information to dynamically compensate for path length variations, creating a closed-loop control system that maintains measurement precision despite external disturbances.

Inventive Principle:
Principle #23Feedback

2Adaptability or versatility

If the optical path length is adjusted for different work distances, then the measurement range is extended, but the focusing system requires reconfiguration

Engineering Contradiction:
Improvemeasurement rangeVSAvoidfocusing system reconfiguration
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent separates the optical path length regulation function from the focusing system by introducing a dedicated optical path length regulator system. This segmentation allows the regulator to independently adjust optical path length for different work distances without affecting the focusing system configuration, enabling extended measurement range while maintaining focusing stability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The optical path length regulator acts as an intermediary that decouples the relationship between work distance changes and focusing system requirements. By inserting this regulatory component in the measurement beam path, the system can adapt to different work distances through optical path adjustment alone, eliminating the need for focusing system reconfiguration.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Measurement precision

If existing OCT-based distance detection is used, then distance measurement capability is achieved, but the system becomes costly and complex

Engineering Contradiction:
Improvedistance detection capabilityVSAvoidsystem cost and complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent implements a simplified interferometric measurement approach that copies the essential functionality of OCT-based distance detection without requiring the full OCT system infrastructure. By using a basic interferometer setup with optical path length regulation, the system achieves comparable distance measurement capability at reduced cost and complexity.

Inventive Principle:
Principle #26Copying

Solution Approach 2:

The patent extracts and isolates the critical distance measurement function from the complex OCT system architecture. By taking out only the essential interferometric measurement capability and combining it with a simple optical path length regulator, the system achieves effective distance detection while eliminating the unnecessary complexity and cost of a complete OCT implementation.

Inventive Principle:
Principle #2Taking out (Extraction)

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 ensures accurate and reliable distance measurements by maintaining a constant optical path length difference, enabling precise focus control without reconfiguring the focusing system, thus improving the quality of laser processing.

Implementation Method 1

an interferometer system with a housing (11), connection ports (12, 14), and an optical path length regulator system (20) for adjusting an optical path length difference between two separate optical paths (P1, P2) defined in the housing (11) for laser light received and outputted through the connection port (12)

Methodology Applied
Scientific EffectInterference: Interference

Data Source

PatentEP4483129B1Measuring module with adjustable path length difference for laser processing apparatus
Publication Date: 2026.03.04 RAYLASE GMBH
  • EP4483129B1 patent drawingFigure 1~2
  • EP4483129B1 patent drawingFigure 3~4
  • EP4483129B1 patent drawingFigure 5~6

AI summary

The invention refers to a measurement module (10) for a laser processing apparatus (1) in which a first optical path (P1) and a second optical path (P2) are defined for laser light within a housing (11). The first optical path (P1) has a fixed predefined optical path length. The second optical path (P2) is defined between a connection port (12) of the housing and a coupling port (14) and has a variable optical path length adjustable by an optical path length regulator system (20). The invention further refers to an interferometer system comprising a measurement module with a first optical path (P1) corresponding to a reference arm of the interferometer system and with a second optical path (P2) corresponding to an object arm of the interferometer system, wherein an optical path length regulator system (20) is configured for adjusting an optical path length of the second optical path (P2), i.e., of the object arm of the interferometer system. The invention further refers to a laser processing apparatus (1) comprising a laser processing module (30) for laser-processing a workpiece (P) on a work field (37) using a work beam (W) and a measurement module (10) according to the invention.