Measurement Scanner Path-Length Correction in Laser Processing Optics
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Solution Overview
Problem
Measurement scanners in laser processing systems face errors due to changes in the optical path length of the measurement beam, which can result in distorted images of the workpiece, especially when the measurement beam is deflected by the laser processing optical unit's mirrors.
Innovation Solution
A method to correct optical path length measurement errors involves coaxially incoupling the measurement beam into the processing laser beam, moving it laterally over the workpiece, and correcting distance values in the z-direction using change values calculated from known optical path lengths at different selection points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the measurement beam is deflected by deflection mirrors of the laser processing optical unit, then the measurement beam can scan the entire working area, but the optical path length changes by several millimetres leading to measurement errors
Solution Approach 1:
The patent applies preliminary action by calculating and storing the optical path length changes at various selection points in the x-y plane before actual measurement. These pre-calculated change values are then used to correct the distance measurements, eliminating the need for real-time complex calculations and enabling accurate measurements across the entire working area.
Solution Approach 2:
The patent changes the parameter of optical path length compensation by introducing correction values that account for the path length variations. By adding these correction values to the raw distance measurements, the system maintains measurement precision despite the beam being deflected across different positions by the mirrors.
2Area of stationary object
If the measurement beam is moved laterally over the workpiece, then the entire workpiece area can be scanned, but the optical path length varies causing distorted images
Solution Approach 1:
The patent compensates for image distortion by changing the parameter of optical path length through correction values. These correction values are applied to adjust the measured distances, thereby eliminating the distortion caused by varying optical path lengths when the beam scans across different areas of the workpiece.
Solution Approach 2:
The patent replaces the need for complex mechanical adjustment systems with a computational approach. Instead of mechanically adjusting the optical system to maintain constant path length, the system uses calculated correction values to compensate for path length variations, achieving the same effect through data processing.
3Measurement precision
If measurement correction is implemented for high precision, then measurement accuracy improves to a few micrometers, but the system complexity increases due to additional calculation and correction steps
Solution Approach 1:
The patent reduces system complexity by performing the complex optical path length calculations in advance and storing the results as correction values. During actual measurement, only simple addition of pre-calculated correction values is needed, maintaining high precision while minimizing real-time computational complexity.
Solution Approach 2:
The patent segments the correction process into discrete correction values for different selection points in the x-y plane. This segmentation allows the complex correction to be broken down into manageable, pre-calculated components that can be easily applied during measurement without requiring complex real-time processing.
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 method effectively eliminates distortions in the image generated by the measurement scanner, ensuring accurate distance data to a few micrometers, and allows for the generation of an undistorted image of the workpiece.
Implementation Method 1
measuring distance values by the measurement scanner at different measurement points of the workpiece
Implementation Method 2
measuring distance values by the measurement scanner at different measurement points of the workpiece
Implementation Method 3
the measurement beam is deflected by deflection mirrors of the laser processing optical unit
Data Source
AI summary
A method for correcting optical path length measurement errors of a measurement scanner at a laser processing optical unit includes incoupling a measurement beam of the measurement scanner for distance measurement purposes coaxially into a processing laser beam, moving the measurement beam laterally in an x-y plane over a workpiece in a vicinity of the processing laser beam, measuring distance values by the measurement scanner at different measurement points of the workpiece, and correcting the distance values in a z-direction by change values. The change values are obtained from calculated or previously known optical path lengths of the measurement beam at different selection points in the x-y plane.