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-10913130-B2
Publication Date
2021-02-09
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 and method for a keyhole welding process that uses an optical interferometer and imaging light delivered into a phase change region created in the material. A laser beam source produces a laser beam applied to a sample location with beam intensity sufficient to extend the phase change region into the material to open a vapor channel.
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. A detector receives the interferometry output and produces a detector output indicative of a characteristic of the phase change region during the keyhole welding process.
An interferogram processor performs analysis based on the detector output to produce a depth measurement reflecting how deep the laser beam has penetrated in the phase change region. A feedback controller controls at least one processing parameter of the material modification process based on the depth measurement and the detector output, including controlling a laser beam power in real time during the process.
Claims Coverage
The independent claims are directed to an apparatus and a method for keyhole welding using imaging-light interferometry through a phase change region to generate a depth measurement and to control processing parameter(s) based on the detector output. Across the independent claims, the inventive concept centers on depth-related interferometry characterization and feedback-controlled control of a material modification parameter.
Keyhole welding with interferometric imaging and depth measurement feedback
A laser beam source applies a laser beam to a sample location in a keyhole welding process to extend a phase change region into the material and open a vapor channel; an imaging optical source produces imaging light delivered into the phase change region; an optical interferometer produces an interferometry output based on at least one optical path length to at least one point in the phase change region compared to another optical path length; a detector produces a detector output indicative of a characteristic of the phase change region; an interferogram processor analyzes the detector output to produce a depth measurement reflecting how deep the laser beam has penetrated in the phase change region; and a feedback controller controls at least one processing parameter based on the depth measurement.
Keyhole welding method with interferometry-based detector output control
Applying a laser beam to a sample location as part of a keyhole welding process with beam intensity sufficient to extend a phase change region into the material to open a vapor channel; generating imaging light with an imaging optical source; producing an interferometry output using at least a component of the imaging light delivered into the phase change region based on at least one 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 characteristic of the phase change region; and controlling at least one processing parameter of the material modification process based on the detector output.
Both independent claims cover keyhole welding in which imaging-light interferometry through a laser-created phase change region yields a detector output indicative of that region. In the apparatus claim, interferogram processing produces a depth measurement reflecting laser penetration, and a feedback controller controls processing parameter(s) based on that depth measurement.
Stated Advantages
Not explicitly described in patent.
Documented Applications
Not explicitly described in patent.
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