Methods and systems for coherent imaging and feedback control for modification of materials
Inventors
Kanko, Jordan • WEBSTER, Paul J. L. • Fraser, James M.
Assignees
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Publication Number
US-11327011-B2
Publication Date
2022-05-10
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 relates to monitoring and/or controlling a material modification process that uses a material processing beam applied to a location of a material. It applies an imaging beam to a phase change region and/or a surrounding region created in the material before, during, and/or after the material modification process, by performing at least a first scan over the phase change region and/or the surrounding region.
A coherent imaging system including an optical interferometer produces an interferometry output using at least a component of the imaging beam applied to the phase change region and/or the surrounding region. 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, and 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.
The invention also collects intrinsic optical emission from the phase change region and/or the surrounding region using one or more auxiliary optical sensors disposed to collect light in a plurality of wavelength bands. The intrinsic optical emission is obtained by performing at least a second scan over the phase change region and/or the surrounding region, and is intrinsic to the material modification process.
At least one of the interferometry output and the auxiliary sensor outputs is used for controlling, monitoring, and adjusting the material modification process. The content also identifies inline coherent imaging during material modification processes, including monitoring of overhang processing and defect detection, as well as feedstock monitoring and phase change region extent and geometry estimation.
Claims Coverage
The consolidated content includes two independent claims. The claims combine coherent interferometer-based inline imaging of a phase change region with auxiliary optical sensor measurement of intrinsic optical emission, and link the resulting outputs to monitoring, controlling, and adjusting the material modification process.
Scanning imaging beam on phase change region
Applying an imaging beam to a phase change region and/or a surrounding region created in the material before, during, and/or after the material modification process, wherein applying the imaging beam comprises performing at least a first scan with the imaging beam over the phase change region and/or the surrounding region.
Optical interferometer interferometry output based on optical path length comparison
Using a coherent imaging system including an optical interferometer to produce an interferometry output using at least a component of the imaging beam applied to the phase change region and/or the surrounding region, wherein 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 phase change characteristics
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.
Auxiliary sensing of intrinsic optical emission in multiple wavelength bands
One or more auxiliary optical sensors collect light in a plurality of wavelength bands and receive at least one intrinsic optical emission from the phase change region and/or surrounding region, and produce one or more auxiliary sensor output, wherein the intrinsic optical emission is obtained by performing at least a second scan over the phase change region and/or the surrounding region and is intrinsic to the material modification process.
Control monitoring using interferometry output and auxiliary sensor output
Using at least one of the interferometry output and the one or more output from the one or more auxiliary optical sensors for one or more of controlling, monitoring, and adjusting the material modification process.
Scanning system performing imaging scan and intrinsic emission scan
Including at least one scanning system configured to perform at least a first scan with the imaging beam over the phase change region and/or the surrounding region for applying the imaging beam, and configured to perform at least a second scan over the phase change region and/or the surrounding region for obtaining the at least one intrinsic optical emission.
The claims cover scanning an imaging beam over a phase change region or surrounding region, generating an interferometry output based on optical path length comparison, detecting characteristics with a detector, collecting intrinsic optical emission with auxiliary sensors in multiple wavelength bands using a second scan, and using the outputs for controlling, monitoring, and adjusting the material modification process.
Stated Advantages
Improves monitoring, quality assurance, and feedback/control of the material modification process using coherent imaging interferometry and auxiliary optical sensors.
Documented Applications
Inline coherent imaging during material modification processes, including monitoring of overhang processing and defect detection.
Feedstock monitoring including layer height, packing, uniformity, clumps, and equipment wear or damage inference.
Phase change region extent and geometry estimation and layer-by-layer assessment for quality assurance and control, including phase change region stability regime tracking.
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