Laser Focus Control via Thermal Feedback
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional laser processing apparatuses are unable to accurately correct focus position deviations in real-time during processing due to thermal lens effects, and their configurations often complicate temperature detection, leading to inaccuracies in maintaining the desired focus position.
Innovation Solution
A process control apparatus that calculates positional deviations of the focus position based on changes in the laser beam's output during processing and adjusts the focus position using a calculator and focus position control unit to maintain accurate beam alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a test object is used to detect focus position deviation before laser processing, then the focus position can be corrected before processing starts, but it is not possible to detect deviations that occur during laser processing in real-time
Solution Approach 1:
The patent implements real-time feedback by detecting the temperature rise of the workpiece during laser processing to continuously monitor focus position deviations. The detection unit measures temperature changes at the workpiece surface, and the control unit uses this feedback to dynamically adjust the processing lens position, enabling continuous correction throughout the processing operation rather than only pre-processing correction.
Solution Approach 2:
The patent replaces the conventional mechanical test object method with a thermal detection mechanism. Instead of using a separate test object to detect focus position, the system uses temperature sensing at the actual workpiece location to infer focus deviations, substituting mechanical detection with thermal field measurement for real-time monitoring.
2Device complexity
If a temperature detector is provided in the processing nozzle away from the processing lens, then the configuration is simplified, but it is not possible to accurately detect deviations of the focus position that occur during laser processing
Solution Approach 1:
The patent uses the workpiece itself as an intermediary medium for detection. The temperature detector measures temperature rise at the workpiece surface, which serves as an indirect indicator of focus position accuracy. The workpiece acts as a mediator that translates optical focus deviations into thermal signals that can be measured and used for correction.
Solution Approach 2:
The patent replaces direct optical or mechanical focus detection mechanisms with thermal field measurement. By detecting temperature changes in the workpiece rather than directly measuring optical parameters, the system achieves accurate focus position detection without complex mechanical detection apparatus in the processing nozzle.
3Productivity
If the processing lens absorbs the laser beam, then the laser processing can be performed, but the refractive index of the processing lens changes causing focus position deviation
Solution Approach 1:
The patent implements a feedback control system that continuously monitors temperature rise at the workpiece during laser processing. This temperature information serves as feedback about focus position accuracy, allowing the control unit to detect when thermal lens effects cause focus deviations and trigger corrective actions to restore accurate focusing.
Solution Approach 2:
The patent compensates for thermal lens effects by dynamically changing the position parameter of the processing lens. As the lens absorbs laser energy and its refractive index changes, the control system adjusts the lens position along the optical axis to counteract the focus shift, maintaining the desired focus position despite the changing optical properties of the lens.
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 control of the laser beam's focus position on the workpiece, effectively correcting for thermal lens effects and ensuring accurate laser processing by continuously adjusting the position of the processing lens or bend mirror.
Implementation Method 1
a processing lens converges the laser beam into a predetermined focus position
Implementation Method 2
when the processing lens absorbs the laser beam, the refractive index of the processing lens changes
Implementation Method 3
This phenomenon is called a thermal lens effect
Data Source
AI summary
A process control apparatus controls a focus position of a laser beam, while a laser processing mechanism converges the laser beam into a predetermined focus position and performs a laser processing on a workpiece. The process control apparatus includes: a calculator that, based on the magnitude of an output of the laser beam that changes during the laser processing, calculates a change amount of a positional deviation of the focus position in an optical axis direction that changes during the laser processing at a laser beam radiation position; and a control unit that, based on the change amount of the positional deviation that has been calculated by the calculator, controls the focus position of the laser beam during the laser processing so as to resolve the positional deviation of the focus position.