Laser Process Sensor With Wavelength-Split Error Detection
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Solution Overview
Problem
Current laser machining process monitoring methods using broadband spectral sensitivity in photodiodes fail to detect intensity changes at individual wavelengths, leading to undetected process errors, particularly in laser welding, due to integrated intensity sensing and inadequate imaging and amplification configurations.
Innovation Solution
A sensor device with a beam splitter arrangement that splits the process beam into multiple, non-overlapping wavelength ranges, allowing individual sensing, imaging, and amplification of sensor signals for each range, using photosensors to monitor laser machining processes more precisely.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If broadband spectral sensitivity photodiodes are used to sense the process beam, then the device complexity is reduced and ease of operation is improved, but measurement precision deteriorates because intensity changes at individual wavelengths cannot be detected
Solution Approach 1:
The patent divides the broadband process beam into multiple narrowband wavelength ranges using beam splitters with specific reflection and transmission characteristics. Each wavelength range is directed to a separate photodiode, enabling precise detection of intensity changes in individual wavelength bands while maintaining manageable system complexity through modular optical component arrangement.
2Measurement precision
If integrated intensity sensing is used in a large wavelength range, then the device complexity is reduced, but measurement precision deteriorates because changes in sensor signal cannot be detected when intensity decreases in one wavelength range and increases in another
Solution Approach 1:
The patent segments the broadband wavelength range into multiple narrowband ranges using beam splitters, with each segment monitored by a dedicated photodiode. This allows detection of intensity changes in specific wavelength ranges that would be masked in integrated sensing, while the overall device complexity remains controlled through systematic optical component design.
Solution Approach 2:
The patent applies local quality by optimizing the spectral sensitivity of each photodiode for its assigned wavelength range and positioning optical components to direct specific wavelength ranges to specific sensors. This localized optimization enables precise detection of process errors that manifest as intensity changes in particular wavelength bands.
3Measurement precision
If optimal imaging is configured for each wavelength range, then measurement precision is improved, but device complexity increases due to different aperture sizes and sensor area sizes required
Solution Approach 1:
The patent implements local quality by configuring each photodiode with optimal imaging parameters for its assigned wavelength range, including appropriate aperture sizes and sensor area dimensions. This wavelength-specific optimization maximizes detection precision for each band while the modular beam splitter architecture keeps the overall optical configuration manageable.
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 detection of process errors by separately sensing and amplifying intensity changes across different wavelength ranges, improving monitoring accuracy and enabling better error detection in laser machining processes.
Implementation Method 1
a beam splitter arrangement (28) configured to separate a process beam (16) generated during the laser machining process into a plurality of partial beams (36a, 36b) with different wavelength ranges
Implementation Method 2
The beam splitter arrangement comprises a primary beam splitter (28a) arranged on a beam axis (27) of the process beam (16)... a first secondary beam splitter (28b) arranged on a beam axis (30b) of the transmitted partial beam (30b)
Implementation Method 3
a first photosensor arrangement (42) for sensing an intensity of the process beam (16) in a visible wavelength range with a plurality of photosensors (42a, 42b, 42c, 42d)... a second photosensor arrangement (44) for sensing an intensity of the process beam (16) in an infrared wavelength range
Data Source
AI summary
A sensor device for monitoring a laser machining process by a laser beam by sensing an intensity of a process beam, the sensor device includes: an optical input; a beam splitter arrangement configured to couple out a plurality of visible partial beams with a respective visible wavelength range from the process beam; a first photosensor arrangement for sensing the intensity of the process beam in the visible wavelength range with a plurality of photosensors arranged to respectively sense an intensity of one of the visible partial beams, the beam splitter arrangement is configured to couple out a first visible partial beam with a first visible wavelength range, a second visible partial beam with a second visible wavelength range, a third visible partial beam with a third visible wavelength range, and a fourth visible partial beam with a fourth visible wavelength range to one photosensor of the first photosensor arrangement, respectively.