Laser Working Head Standoff Measurement via Low-Coherence Fringes
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Solution Overview
Problem
Current laser processing technologies face challenges in accurately determining the separation distance between the working head and the material surface, especially for non-metal materials and complex surface geometries, leading to inefficiencies in processes like cutting, drilling, and welding.
Innovation Solution
The implementation of low coherence interferometry with spatial domain detection, which uses a measurement optical path integrated in the working head and a reference optical path to determine the separation distance by analyzing interference fringes, providing precise and robust measurements independent of material morphology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional capacitive sensors are used to determine separation distance, then the measurement can be performed, but the measurement precision deteriorates for non-metal materials and complex surface geometries
Solution Approach 1:
The patent replaces capacitive sensing (electrical field-based) with optical interferometry (light-based). The optical measurement system uses a measurement beam that reflects off the material surface and interferes with a reference beam, creating interference fringes that are analyzed to determine separation distance. This optical approach is insensitive to material electrical properties, enabling accurate measurement on non-metal materials and complex surface geometries where capacitive sensors fail.
2Measurement precision
If low coherence interferometry with spatial domain detection is implemented, then measurement precision and adaptability improve, but device complexity increases
Solution Approach 1:
The patent extracts only the essential interferometric measurement function from a complete interferometer, integrating the measurement optical path directly into the working head. By using a simple linear array of photodetectors to detect interference fringe positions and implementing straightforward signal processing algorithms, the system achieves high measurement precision while keeping the overall device complexity manageable through functional integration and selective implementation of only necessary components.
3Measurement precision
If computational algorithms are used to process interferometric signals, then measurement accuracy improves, but processing time and computational resources increase
Solution Approach 1:
The patent replaces complex computational processing with direct spatial domain analysis of interference fringes. By detecting the position of interference fringes directly in the spatial domain using a linear photodetector array and applying simple correlation algorithms, the system achieves high measurement accuracy with minimal processing time, avoiding the need for time-consuming Fourier transforms or iterative optimization algorithms.
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 method enables accurate and real-time measurement of separation distances over a large range, improving the precision and efficiency of laser processing operations such as cutting, drilling, and welding by directly visualizing interference patterns with an economical setup, reducing computational complexity and artifacts.
Implementation Method 1
superimposing a measurement beam of optical radiation with a reference beam of optical radiation, both beams being emitted by a low coherence optical radiation source, on a common region of incidence of a sensor arrangement so as to form interference fringes
Data Source
AI summary
A method for determining a separation distance between a working head in a machine for laser processing a material and a surface of the material includes generating a measurement beam of low coherence optical radiation, leading the measurement beam towards the material and a reflected or diffused measurement beam towards an optical interferometric sensor arrangement in a first direction of incidence, generating a reference beam of low coherence optical radiation, leading the reference beam towards the optical interferometric sensor arrangement in a second direction of incidence superimposing the measurement and reference beams on a common region of incidence, detecting a position of a pattern of interference fringes between the measurement and reference beams on the common region of incidence, and determining a difference in optical length between the measurement and reference optical paths based on the position of the pattern of interference fringes along an illumination axis.