Methods and systems for coherent imaging and feedback control for modification of materials
Inventors
Kanko, Jordan • Webster, Paul J.L. • Fraser, James M. • Yang, Victor X.D.
Assignees
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Publication Number
US-10124410-B2
Publication Date
2018-11-13
Expiration Date
Abstract
Methods and systems are provided for using optical interferometry in the context of material modification processes such as surgical laser, sintering, and 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 and a method for coherent inline imaging using an optical interferometer to measure characteristics of a phase change region and/or a surrounding region created in a material during a material modification process. An imaging light source produces imaging light that is delivered to the phase change region and/or the surrounding region before, during, and/or after the material modification process, and the optical interferometer produces an interferometry output based on optical path length to points in the phase change region and/or the surrounding region compared to another optical path length.
A detector receives the interferometry output and produces a detector output indicative of a characteristic of the phase change region and/or the surrounding region during the material modification process. A record generator generates at least one record based on the detector output at a plurality of times, enabling time-based characterization, and the interferometry output is used to control at least one processing parameter of the material modification process.
The material modification process is selected from sintering, welding, brazing, or a combination thereof. The apparatus includes a material processing beam source for producing a material processing beam applied to a location of a material, and the coherent imaging system provides in-situ measurement, quality assurance, and feedback/control framework, including layerwise morphology measurements and defect detection/control.
Claims Coverage
The independent claims are directed to coherent interferometric imaging of a phase change region and/or surrounding region, detector output indicative of a characteristic during modification, time-based record generation from detector output, and controlling processing parameters using interferometry output. The process is limited to sintering, welding, brazing, and combinations thereof.
Coherent interferometric imaging of a phase change region
A coherent imaging system including an optical interferometer produces an interferometry output using at least a component of imaging light delivered to a phase change region and/or a surrounding region, where the interferometry output is based on at least one optical path length to at least one point in the phase change region and/or the surrounding region compared to another optical path length.
Detector output indicative of a characteristic during modification
A detector receives the interferometry output and produces a detector output indicative of a characteristic of the phase change region and/or the surrounding region during the material modification process.
Time-based record generation from detector output
A record generator generates at least one record based on the detector output at a plurality of times.
Controlling processing parameters using interferometry output
Interferometry output indicative of a characteristic of the phase change region and/or the surrounding region during the material modification process is used to control at least one processing parameter of the material modification process.
Material modification process selected from sintering, welding, brazing
The material modification process is selected from sintering, welding, brazing, and a combination thereof.
The claims center on coherent interferometric imaging of a phase change region and/or surrounding region with an optical interferometer that yields an interferometry output based on optical path length differences. This output supports detector-based characterization, generation of records at multiple times, and control of at least one processing parameter for sintering, welding, brazing, or combinations thereof.
Stated Advantages
Enables measurement of a characteristic of a phase change region and/or surrounding region during a material modification process.
Generates time-based records based on the detector output.
Allows controlling at least one processing parameter using the interferometry output.
Provides an in-situ measurement, quality assurance, and feedback/control framework for additive manufacturing, including layerwise morphology measurements and defect detection/control.
Documented Applications
Monitoring and controlling material modification processes selected from sintering, welding, and brazing, including coherent interferometric measurement of phase change region characteristics during those processes.
Laser drilling/cutting in hard tissue (spinal surgery / hard tissue cutting) with penetration/breakthrough monitoring concepts described via interferometric outputs.
Laser welding/keyhole welding monitoring for keyhole depth/stability monitoring with quality records and guidance.
Additive manufacturing as an in-situ measurement, quality assurance, and control framework, including coaxial imaging with processing beams and layerwise morphology measurements for defect detection/control and improved process stability.
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