Laser Machining Focus Correction via Parallel Plate Reflection
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Solution Overview
Problem
High-power laser beams cause thermal distortion in optical elements, leading to focal shifts, and contamination from fumes or dust further exacerbates this issue by altering the optical absorption coefficient, making it difficult to detect and correct thermal lens effects in laser machining devices.
Innovation Solution
A laser machining device equipped with detectors to monitor the reflected beams from both entrance and exit surfaces of parallel plates, allowing for the detection and calculation of focal shifts, with a position adjuster to correct these shifts and a warning system to alert operators of contamination, thereby maintaining optimal laser output and machining precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-power laser beams are used for machining, then productivity and machining capability are improved, but thermal lens effect occurs causing focal shift and reducing manufacturing precision
Solution Approach 1:
The patent applies preliminary action by measuring the focal position before machining operations begin. The detection unit measures the actual focal position of the laser beam in advance, and the control unit calculates the focal shift based on these preliminary measurements. This allows the system to compensate for thermal lens effects before they significantly impact machining precision, thereby maintaining both high productivity and manufacturing precision.
2Manufacturing precision
If optical elements are disposed in the machining head for focusing, then manufacturing precision is improved, but thermal distortion occurs due to heat absorption and causes focal shift
Solution Approach 1:
The patent implements feedback by continuously measuring the focal position using the detection unit and comparing it with the target focal position. The control unit receives this feedback information, calculates the focal shift, and adjusts the focal position accordingly. This closed-loop feedback system allows the optical elements to maintain precise focus control even when thermal distortion occurs during high-power operation.
3Reliability
If contamination adheres to optical elements, then thermal absorption increases leading to thermal distortion, but detecting this contamination is difficult
Solution Approach 1:
The patent uses an intermediary approach by introducing a separate detection unit that indirectly measures the focal position to infer contamination levels. Instead of directly detecting contamination on the optical elements, the system measures the focal shift caused by thermal absorption, which serves as an intermediary indicator of contamination. This makes contamination detection feasible through focal position measurements.
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 real-time detection and correction of thermal lens effects, ensuring consistent laser beam focus and preventing damage from contamination, thereby enhancing the reliability and precision of laser machining processes.
Implementation Method 1
a first detector that detects an output of a reflected beam from an exit end surface of the first parallel plate
Implementation Method 2
a second detector that detects an output of a reflected beam from an entrance end surface of the first parallel plate
Implementation Method 3
a third detector that detects an output of a reflected beam from an entrance end surface of the second parallel plate
Implementation Method 4
a first parallel plate disposed closer to an outgoing side than a long-focus lens; a laser beam passing through a second parallel plate and then a first parallel plate
Data Source
Figure 1
Figure 2~3
AI summary
A first detector 31 detects an output of a reflected beam from an exit end surface of a first parallel plate 25. A determination unit 16 determines that an abnormality occurs in the first parallel plate 25 when the detection value of the first detector 31 is smaller than a predetermined determination threshold.