Monitoring material processing using imaging signal density determined from inline coherent imaging (ICI)
Inventors
Galbraith, Christopher M. • Kanko, Jordan • WEBSTER, Paul J. L. • Van Vlack, Cole • Hayes, Genevieve Elizabeth
Assignees
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Publication Number
US-12053835-B2
Publication Date
2024-08-06
Expiration Date
Abstract
Systems, methods and apparatuses are used for monitoring material processing using imaging signal density calculated for an imaging beam directed to a workpiece or processing region, for example, during inline coherent imaging (ICI). The imaging signal density may be used, for example, to monitor laser and e-beam welding processes such as full or partial penetration welding. In some examples, the imaging signal density is indicative of weld penetration as a result of reflections from a keyhole floor and/or from a subsurface structure beneath the keyhole. The monitoring may include, for example, automated pass/fail or quality assessment of the welding or material processing or parts produced thereby. The imaging signal density may also be used to control the welding or material processing, for example, using imaging signal density data as feedback. The imaging signal density may be used alone or together with other measurements or metrics, such as distance or depth measurements.
Core Innovation
The document describes monitoring a material processing process in which a process beam is generated and directed to a workpiece, while an imaging beam is generated and directed to the workpiece together with the process beam. Interferometry output is produced from at least a component of the imaging beam reflected from the workpiece, and a plurality of A-scans of the workpiece is produced using the interferometry output. The A-scans are classified using a monitoring system.
The classification assigns the A-scans to categories representing at least one aspect of a phase change region or workpiece sub-region. The at least one aspect is at least one of vapor channel, vapor channel bottom, vapor channel sidewall, weld penetration depth, melt pool, workpiece surface, material composition, material phase, and material density. The document further characterizes the A-scans by producing or detecting ICI data using an inline coherent imaging (ICI) system.
The document introduces an imaging signal density that is determined from interferometry output or ICI data and is used to classify the phase change region or workpiece sub-region aspects. The imaging signal density is computed by checking for a measurement point whose signal intensity exceeds a threshold, and determining a portion of A-scans satisfying the condition within a bin. The monitoring is further tied to organizing the classification with respect to the phase change region, including distinguishing surface versus keyhole/vapor channel regions and weld-penetration-related behavior through signal-density thresholding.
Claims Coverage
The document provides three independent claims (a method, another method, and a system). Across the independent claims, three core inventive elements are present: using ICI interferometry to generate A-scans, classifying A-scans into categories corresponding to aspects of a phase change region or workpiece sub-region, and using an imaging signal density, including threshold-based logic, to perform that classification.
Inline coherent imaging A-scan generation and interferometry output
Generating a process beam and directing the process beam to a workpiece for material processing, generating an imaging beam, directing the imaging beam to the workpiece, producing an interferometry output from at least a component of the imaging beam reflected from the workpiece, and producing a plurality of A-scans of the workpiece using the interferometry output.
Category-based classification of A-scans for phase change region aspects
Classifying A-scans of the plurality of A-scans as pertaining to at least one aspect of a phase change region or workpiece sub-region, performed by a monitoring system, wherein the A-scans are classified into categories representing the at least one aspect, and wherein the at least one aspect is at least one of vapor channel, vapor channel bottom, vapor channel sidewall, weld penetration depth, melt pool, workpiece surface, material composition, material phase, and material density.
ICI signal density determination for classification
Producing a plurality of A-scans using an inline coherent imaging (ICI) system and classifying A-scans as pertaining to at least one aspect of a phase change region or workpiece sub-region using a monitoring system based on at least an ICI imaging signal density.
Threshold-based imaging signal density computation
Determining an ICI imaging signal density by determining whether each of the A-scans contains a measurement point whose signal intensity exceeds a threshold.
Wobble pattern to create periodic spatial alignment variations relative to PCR position
Directing the process beam to a workpiece using a wobble pattern that creates periodic spatial alignment variations between an imaging beam measurement location and a phase change region (PCR) position.
System combining material processing, ICI data, and monitoring with imaging signal density
A material processing system configured to generate a process beam and direct it toward a workpiece; an inline coherent imaging (ICI) system configured to generate an imaging beam, to direct the imaging beam toward the workpiece together with the process beam, to produce an interferometer output from a reflection of the imaging beam, and to detect the interferometer output to produce ICI data; and a monitoring system programmed to receive the ICI data, determine at least an ICI imaging signal density, and classify at least one aspect of a phase change region or workpiece sub-region using the imaging signal density.
The independent claims define an ICI-based monitoring approach where interferometry output generates A-scans, the A-scans are classified into categories tied to aspects of a phase change region or workpiece sub-region, and classification is performed using an imaging signal density determined from ICI/A-scan measurement points using threshold-based criteria. The document also specifies that process-beam wobble can be used to create periodic spatial alignment variations relative to PCR position.
Stated Advantages
Enables classification of at least one aspect of a phase change region or workpiece sub-region using imaging signal density.
Documented Applications
Monitoring and classifying aspects of a phase change region or workpiece sub-region during material processing using a process beam and an inline coherent imaging (ICI) system.
Characterizing weld-related phase change region features including vapor channel, vapor channel bottom, vapor channel sidewall, weld penetration depth, and melt pool.
Monitoring with wobble welding using periodic spatial alignment variations between an imaging beam measurement location and a phase change region (PCR) position.
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