OCT Reference Arm Staging for Laser Head Distance Measurement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing laser processing systems face challenges in achieving precise and error-free distance measurements between the laser processing head and the workpiece, particularly due to complex control mechanisms and limited measuring range in optical coherence tomography (OCT) systems.
Innovation Solution
The implementation of an OCT measuring device with more than two reference stages having different optical path lengths, where measuring light is divided and superimposed to determine distance, eliminating the need for synchronous mechanical adjustments and ensuring gapless distance measurement even with rapid changes in processing position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If synchronous adjustment of optical path length in reference arm is used to increase measuring range, then measuring range is increased, but control complexity increases significantly
Solution Approach 1:
The reference arm is segmented into multiple discrete reference stages (at least three), each with a different fixed optical path length. This segmentation allows the measuring device to cover an extended measuring range by selecting appropriate reference stages without requiring continuous mechanical adjustment, thereby reducing control complexity while maintaining an enlarged measuring range.
2Length of stationary object
If mechanical adjustment of reference arm position is used to extend measuring range, then measuring range is increased, but system complexity and time offsets increase
Solution Approach 1:
The system dynamically selects appropriate reference stages based on the current measuring requirements and processing position. This dynamic selection allows the system to adapt to rapid changes in processing position without requiring continuous mechanical adjustment of the entire reference arm, reducing both system complexity and time offsets while maintaining an extended measuring range.
Solution Approach 2:
Multiple reference stages with different optical path lengths are pre-configured in the reference arm. This preliminary arrangement of fixed optical path lengths eliminates the need for synchronous mechanical adjustment during operation, reducing system complexity and avoiding time offsets that would arise from real-time mechanical changes.
3Ease of operation
If indirect determination of measuring beam position is used, then positioning is achieved, but measurement precision is insufficient
Solution Approach 1:
The system replaces indirect camera-based positioning methods with direct optical path length measurement using multiple reference stages. This substitution provides more precise and reliable distance measurements by directly measuring the optical path difference between the measuring beam and reference beams, eliminating the inaccuracies inherent in indirect image-based positioning methods.
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 approach simplifies the control of the reference arm, reduces time offsets, and enables precise, error-free distance measurements over an enlarged measuring range, ensuring stable OCT interference signals and accurate processing head positioning.
Implementation Method 1
the measuring light reflected from the workpiece interferes with measuring light reflected in a reference arm with more than two reference stages
Implementation Method 2
Optical coherence tomography (OCT) can be used in laser material processing to measure various process parameters
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
The present disclosure relates to a measuring device for determining a distance between a machining head (101) for a laser machining system (100), which is designed for machining a workpiece (1) using a laser beam (10), and the workpiece. The measuring device comprises an optical coherence tomograph (120), which is designed to measure a distance between the machining head (101) and the workpiece (1), wherein, in the optical coherence tomograph (120), measurement light (13) which is generated by a measurement light source and which is reflected by the workpiece (1) interferes with measurement light which is reflected in a reference arm (200, 300) having two or more reference stages. The two or more reference stages comprise a first reference stage (210), which is designed such that measurement light reflected in the first reference stage (210) covers a first optical path length, and a second reference stage (220), which is designed such that measurement light reflected in the second reference stage (220) covers a second optical path length, which is different from the first optical path length, wherein the measurement light reflected by the workpiece (1) is interfered with by the reflected measurement light of the first reference stage (210) and the reflected measurement light of the second reference stage (220).