Beam Focus Detection Using Split Sub-Beams for Thermal Focal Shift
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing technologies are inadequate for precisely determining the axial position of a laser beam focus in processing optics, especially during high-power laser material processing, due to thermal focal shift and contamination effects.
Innovation Solution
A beam analysis device that includes a beam shaping device to release two sub-beams, a detector to capture the intensity distribution, and an evaluation device to determine the axial position of the beam focus based on the distance between the sub-beams on the detector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high-power lasers are used for material processing, then processing power and efficiency are improved, but thermal focal shift occurs due to heating of optical elements
Solution Approach 1:
A sample beam is introduced as an intermediary element to measure the focal position. The sample beam passes through the processing optics and its focal position is detected by a beam analysis device, allowing indirect measurement without being affected by the high power of the main processing beam
Solution Approach 2:
The sample beam serves as a copy or replica of the processing beam, following the same optical path and experiencing the same thermal focal shift. By measuring the focal position of this copy beam, the actual focal position of the processing beam can be determined
2Ease of operation
If optical elements are used in high-power laser processing, then beam delivery is enabled, but thermal focal shift occurs due to temperature dependence of refractive index
Solution Approach 1:
The beam analysis device provides continuous feedback on the focal position by detecting the sample beam. This information can be used to adjust the optical system or processing parameters to compensate for thermal focal shift, maintaining focal position stability
3Productivity
If processing continues during laser material processing, then productivity is improved, but contamination deposits on optics leading to increased absorption and focal shift
Solution Approach 1:
The sample beam continuously monitors the focal position during processing, allowing the system to self-diagnose contamination effects. The measurement function is integrated into the processing system, enabling real-time detection without interrupting production
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 accurate determination of the axial position of the laser beam focus, even in the presence of thermal focal shift and contamination, thereby improving the consistency and quality of laser material processing.
Implementation Method 1
a beam shaping device (12), in particular a modulation device (20), which is set up for shaping an intensity distribution on the detector with at least two beam spots
Implementation Method 2
The detector (40) is set up for converting the intensity distribution into electrical signals
Implementation Method 3
Devices for determining a workpiece distance or a workpiece surface position are known from the prior art; these function, for example, in accordance with the basic principle of optical triangulation
Data Source
AI summary
The invention relates to a beam analysis device (10) for determining the axial position of the focal point (71) of an energy beam or a sample beam (70) decoupled from an energy beam, comprising a beam-shaping device (12), a detector (40), and an analysis device (45). The beam-shaping device (12) is designed to release two sub-beams (72, 73) from the sample beam (70) on a plane of the sub-beam release process (19). The cross-sections of the two sub-beams (72, 73) are defined by sub-apertures (32, 33) which are delimited from each other and which are arranged at a distance k to each other in a first lateral direction (31). The beam-shaping device (12) is designed to image the two sub-beams (72, 73) in order to form two beam spots (92, 93) on the detector and deflect at least one of the two sub-beams (72, 73) in a second lateral direction (37) which is oriented transversely to the first lateral direction (31) in order to form a distance w in the second lateral direction (37) between the two beam spots (92, 93). The analysis device (45) is designed to determine the distance a along the first lateral direction (31) between positions of the two beam spots (92, 93) on the detector (40) and to determine the axial position of the beam focus (71) on the basis of the distance a and/or to determine a change in the axial position of the beam focus (71) on the basis of a change in the distance a. The invention also relates to a corresponding method for determining the axial position of a beam focus (71).