OCT Beam Alignment for Accurate Laser Welding Depth Measurement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for optically measuring welding depth in laser welding are inaccurate due to indirect determination of the measuring light beam's position relative to the vapor capillary (keyhole), making precise positioning challenging.
Innovation Solution
A method that couples a measuring light beam from an OCT-based sensor system into the processing beam path of a laser processing head, focusing it onto the workpiece surface to form a measuring light spot, which is then guided over the vapor capillary to determine its precise position, ensuring accurate alignment with the keyhole for reliable welding depth measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If indirect methods (camera-based) are used to determine measuring beam position, then device complexity is reduced, but measurement precision deteriorates because the exact position relative to the vapor capillary cannot be determined
Solution Approach 1:
The patent combines the measuring beam path and the working laser beam path within the same optical system. Both beams are guided through the same processing optics, which ensures that they share the same optical path and focusing characteristics. This merging eliminates the need for separate positioning systems while ensuring precise alignment with the vapor capillary.
Solution Approach 2:
The patent introduces an intermediary approach by using the working laser beam's interaction with the workpiece (vapor capillary formation) as a reference for positioning the measuring beam. The measuring beam is positioned relative to the vapor capillary that is created by the working laser, using the capillary's optical signature as a mediator to achieve precise positioning without complex mechanical alignment systems.
2Measurement precision
If the measuring light beam is coupled into the processing beam path through processing optics, then measurement precision improves by direct alignment with the vapor capillary, but device complexity increases due to integration requirements
Solution Approach 1:
The processing optics serve multiple functions: they guide both the working laser beam for material processing and the measuring light beam for depth measurement. The same optical components (mirrors, lenses, beam paths) are used for both purposes, making the optical system universal and eliminating the need for separate positioning and measurement optical paths.
Solution Approach 2:
The patent merges the measurement function into the existing processing beam path. The measuring light beam is coupled into the processing optics at a point where it can share the optical path with the working laser beam, allowing both beams to be focused onto the workpiece through the same focusing optics, thereby achieving precise alignment without adding complex separate positioning systems.
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
Enables precise and reliable measurement of welding depth by directly aligning the measuring light beam with the vapor capillary, improving measurement accuracy and allowing for continuous monitoring and readjustment of welding depth during the process.
Implementation Method 1
The measuring light beam is bundled or focused onto the surface of a workpiece by focusing optics of the processing beam path in order to form a measuring light spot there
Implementation Method 2
A measuring light beam of a sensor system, in particular an OCT-based sensor system
Implementation Method 3
which work according to the principle of optical short-coherence interferometry, in which the measuring light is split into a measuring light beam
Implementation Method 4
The measuring and reference light beams reflected back from a measuring arm and a reference arm are superimposed on one another in order to determine the desired distance information from the path differences
Data Source
Figure 1~2
Figure 3~5b
Figure 6
AI summary
The invention relates to a method for measuring the welding-in depth, in particular when welding, drilling or removing material by means of a working laser beam (36), in which a measuring light beam (28) of a sensor system (10) is coupled into a machining beam path (30) of the working laser beam (36) in a laser machining head (26) and is concentrated or focused by a focusing optical unit (42) of the machining beam path (30) to a measuring light spot on a surface of a workpiece (44). The measuring light beam (28) reflected at the surface of the workpiece is then returned to a measuring and evaluating unit (12) of the sensor system (10), in order to obtain information about the distance of the surface of the workpiece (44) from the laser machining head (26). In order to obtain a surface profile of the workpiece in the region of the vapour capillary (54), from which the position of the vapour capillary (54) in relation to the point of incidence of the working laser beam can be determined, the position of the measuring light spot on the surface of the workpiece (44) is guided both in the welding direction and transversely thereto over the vapour capillary (54). The measuring light spot is then moved into the determined position of the vapour capillary (54) for measuring the welding-in depth during the laser machining.