Methods and systems for coherent imaging and feedback control for modification of materials using dynamic optical path switch in the reference arms
Inventors
WEBSTER, Paul J. L. • Fraser, James M. • YANG, Victor X. D.
Assignees
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Publication Number
US-11534858-B2
Publication Date
2022-12-27
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 inline coherent imaging system includes an imaging light source and at least one sample arm configured to direct imaging light to a sample location. The system further includes a first reference arm having a first optical path length and at least one additional reference arm configured to have an optical path length different from the first optical path length. An optical path selector selectively couples an optical path for the imaging light into one of the reference arms.
The optical path selector is a dynamic optical path switch that dynamically switches between the first reference arm and the additional reference arm in coordination with timing of a main processing beam directivity, including coordination with the directivity of a laser beam. A processor controls the dynamic optical path switch to selectively couple the optical path in coordination with the main processing beam directivity, so that interferometry is generated using a comparison between imaging light reflected from the sample location and imaging light reflected from the selected reference arm.
The system uses interferometry outputs based on comparison between imaging light reflected from the sample location through the sample arm and imaging light reflected from the selected reference arm. An interferogram processor/controller estimates depth/penetration and subsurface interfaces, and controls processing parameters of a material modification process based on depth measurements and/or transition detection. Feedback is accelerated via homodyne filtering using pre-calculated synthesized interferograms with correlation thresholding, enabling detection and guidance relative to a phase change region and subsurface interfaces.
Claims Coverage
The document includes three independent claims: an inline coherent imaging system with dynamically switchable reference arms coordinated with processing beam directivity; a welding method using the same dynamic reference-arm selection to generate interferometry outputs; and an apparatus combining a laser beam source for material modification with the inline coherent imaging system for dynamically coordinated reference-path selection.
Dynamically switchable reference optical paths coordinated with processing beam directivity
An optical path selector configured to selectively couple an optical path for imaging light from the imaging light source into one of the first reference arm or the at least one additional reference arm, wherein the selector is a dynamic optical path switch configured to dynamically switch between the first reference arm and the additional reference arm in coordination with timing of a main processing beam directivity, and a processor configured to control the dynamic optical path switch to selectively couple the optical path in coordination with the timing of the main processing beam directivity.
Interferometry output based on comparison using the selected reference arm
Generating an interferometry output based on a comparison between imaging light reflected from the sample location through the at least one sample arm and imaging light reflected from one of the first reference arm and the at least one additional reference arm.
Laser beam material modification with inline coherent imaging using dynamically coordinated reference-path selection
A laser beam source that produces a laser beam applied to a sample location in a material modification process, together with an inline coherent imaging system having a first reference arm and at least one additional reference arm with different optical path lengths, and an optical path selector that dynamically switches between the first reference arm and the additional reference arm in coordination with the directivity of the laser beam, controlled by a processor configured to coordinate the switching with the directivity of the laser beam.
Across the independent claims, the coverage centers on using multiple reference arms with different optical path lengths and selecting between them via a dynamic optical path switch coordinated with processing beam/laser directivity, such that interferometry outputs are generated from a comparison between sample-reflected imaging light and the selected reference-arm reflected imaging light, including controlling or enabling material modification when used with a laser beam source.
Stated Advantages
Not explicitly described in patent.
Documented Applications
Welding process with imaging-light interferometry for monitoring and feedback during welding.
Hard-tissue drilling/perforation control with depth and subsurface sensing to guide processing.
Laser welding keyhole depth monitoring and guidance based on interferometry-derived depth and transition detection.
Laser surgery forward-viewing guidance using inline coherent imaging to sense subsurface interfaces.
Breakthrough detection/perforation/overdrilling monitoring using depth-related interferometry and feedback.
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