Methods and systems for coherent imaging and feedback control for modification of materials
Inventors
WEBSTER, Paul J. L. • Fraser, James M. • YANG, Victor X. D.
Assignees
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Publication Number
US-8822875-B2
Publication Date
2014-09-02
Expiration Date
Abstract
Methods and systems are provided for using optical interferometry in the context of material modification processes such as surgical laser or welding applications. An imaging optical source that produces imaging light. A feedback controller controls at least one processing parameter of the material modification process based on an interferometry output generated using the imaging light. A method of processing interferograms is provided based on homodyne filtering. A method of generating a record of a material modification process using an interferometry output is provided.
Core Innovation
The invention provides an apparatus for generating a record of a welding material modification process. A material processing beam source applies a material processing beam to a sample location during the welding process, and an imaging optical source produces imaging light that is delivered into a phase change region created in the material during welding.
An optical interferometer produces an interferometry output based on optical path length differences, using at least a component of the imaging light delivered into the phase change region. The interferometry output is based on at least one optical path length to at least one point in the phase change region compared to another optical path length, and a detector receives the interferometry output and produces a detector output indicative of a characteristic of the phase change region during the welding process.
A record generator generates at least one record based on the detector output at a plurality of times. The record captures phase-change-region characteristics over time during welding and reflects weld-related characteristics, including keyhole stability or impending breakthrough, as identified by the dependent claim refinements.
Claims Coverage
Two independent claims are provided: an apparatus claim and a method claim. Across these claims, the core inventive features include inline interferometry delivering imaging light into a welding phase change region, optical path length difference-based interferometry output, detector output indicative of a phase-change-region characteristic, and generation of time-resolved records during welding.
Record generation for welding using phase-change-region interferometry
An apparatus that generates a record of a welding material modification process by delivering a material processing beam, delivering imaging light into a phase change region, producing an interferometry output based on optical path length differences to points in the phase change region, detecting the interferometry output to generate a detector output indicative of a characteristic of the phase change region, and generating at least one record based on the detector output at a plurality of times.
Interferometry output based on optical path length differences through a welding phase change region
A method that generates a record of a welding material modification process by applying a material processing beam to a sample, generating imaging light, producing an interferometry output from imaging light delivered into a phase change region, where the interferometry output is based on optical path length to at least one point in the phase change region compared to another optical path length, detecting the interferometry output to produce a detector output indicative of a phase-change-region characteristic, and generating at least one record based on the detector output at a plurality of times.
Both independent claims center on producing an interferometry output from imaging light delivered into a welding-created phase change region using optical path length differences, converting that interferometry output into a detector output indicative of a phase-change-region characteristic, and generating time-resolved records during the welding process.
Stated Advantages
Not explicitly described in patent.
Documented Applications
Not explicitly described in patent.
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