Laser Scanner In-Situ Distance Measurement
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Solution Overview
Problem
Existing material-working devices face challenges in accurately measuring the working distance between a beam generator and a workpiece due to vibrations in optical fibers, which affect the reliability of tomogram recording and endpoint determination during processes like ablation and deposition.
Innovation Solution
A material-working device with a laser scanner and automatic refocusing system, utilizing linearly polarized measuring beams with crossed polarization directions and a spectrometer for in-situ distance measurement, stabilizes the measurement signals against vibrations and ensures accurate distance control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If optical fibers are used to transmit measurement signals in material-working devices, then the device can perform distance measurement and tomogram recording, but vibrations in the optical fibers cause modifications to the polarisation state and spectral transmission, degrading measurement reliability
Solution Approach 1:
The patent introduces a polarisation-maintaining optical fiber as an intermediary component between the light source and the measurement system. This specialized optical fiber is designed to preserve the polarisation state of light during transmission, acting as a mediator that prevents vibration-induced polarisation modifications from affecting the measurement signals. The optical coupling element also serves as an intermediary to combine beams with crossed polarisation directions while maintaining their polarisation states.
Solution Approach 2:
The patent employs parameter changes by using light sources with different polarisation directions (crossed polarisation) and transmitting them through a polarisation-maintaining optical fiber. By changing the polarisation parameter and maintaining it throughout the transmission path, the system becomes insensitive to vibration-induced polarisation modifications. The spectrometer detects spectral transmission changes while the polarisation state remains stable, enabling reliable distance measurement despite vibrations.
2Adaptability or versatility
If a laser scanner with variable refocusing device is used to vary working distances, then the device can adapt to different measurement ranges, but the complexity of the optical system increases
Solution Approach 1:
The patent applies universality by designing the laser scanner's optical system to serve multiple functions: the same objective lens and scanner mirrors are used for both the working laser beam and the sensor light beams. The variable refocusing device is integrated into the existing optical path, allowing the system to perform both material working and distance measurement without requiring separate optical paths. This multi-functionality reduces the overall complexity compared to having independent systems for each function.
Solution Approach 2:
The patent merges the measurement optical path with the working laser optical path by using the same laser scanner, objective lens, and variable refocusing device for both functions. The optical coupling element combines the sensor light with the working laser beam, allowing both beams to travel through the same optical components. This merging eliminates the need for separate optical systems, thereby reducing device complexity while maintaining adaptability.
3Measurement precision
If spectral transmission is measured to determine workpiece distance, then in-situ distance measurement is achieved, but vibrations cause unstable spectral transmission readings
Solution Approach 1:
The patent introduces a polarisation-maintaining optical fiber as an intermediary to stabilize the spectral transmission measurements. This specialized optical fiber preserves the polarisation state of the light during transmission, preventing vibration-induced polarisation modifications from causing instability in the spectral transmission readings. The optical coupling element also acts as an intermediary to properly combine the sensor light with the working laser beam, ensuring stable optical path conditions.
Solution Approach 2:
The patent changes the polarisation parameter of the light source and maintains it throughout the transmission path using a polarisation-maintaining optical fiber. By using light with defined polarisation directions and preserving these directions through the optical system, the measurement becomes insensitive to vibration-induced polarisation changes. This parameter control stabilizes the spectral transmission readings, enabling precise distance measurement despite vibrations.
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
The solution provides robust and reliable distance measurement throughout the laser scanner volume, enhancing the precision of surface topography recording and endpoint determination by stabilizing spectral transmission and preventing polarisation state modifications from fiber vibrations.
Implementation Method 1
an optical coupling element, wherein the measuring beams are linearly polarized in crossed polarization directions and collimated using the optical coupling element, and then directed to the workpiece
Implementation Method 2
the measuring beams are linearly polarized in crossed polarization directions
Implementation Method 3
a laser scanner for the working laser, the laser scanner including a two-dimensional deflecting device with scanner mirrors
Implementation Method 4
a sensor device including a spectrometer... directed back to the spectrometer to record to workpiece distance
Implementation Method 5
a sensor device including a spectrometer
Implementation Method 6
an objective lens... directed to the workpiece through the laser scanner and the objective lens
Data Source
AI summary
A material-working device with working beams of a beam generator and with in-situ measurement of a working distance between the beam generator and a workpiece, the material-working device including a working laser; a laser scanner for the working laser, the laser scanner including a two-dimensional deflecting device with scanner mirrors and a variable refocusing device at varying working distances; and a sensor device including a spectrometer and at least one sensor light source, wherein measuring beams together scan a working area of the workpiece by the laser scanner and an objective lens while gathering the working distance, and the measuring beams of at least two of the light sources of the sensor device being linearly polarized and being coupled into a working beam path of the laser scanner of the material-working device by an optical coupling element in a collimated state with crossed polarization directions.