Methods and systems for characterizing laser machining properties by measuring keyhole dynamics using interferometry
First Claim
1. An apparatus comprising:
- a low coherence imaging light source that produces an imaging beam that is applied by a material processing system, wherein the material processing system implements a material modification process using a material processing energy source that produces a material processing beam that is applied to the material, wherein the material processing beam creates a phase change region (PCR) in the material;
at least one directing element that directs the imaging beam at one or more selected imaging beam positions in the PCR;
at least one optical element that sets a numerical aperture of the imaging beam so as to resolve a depth of the PCR at a plurality of locations within the PCR;
at least one input-output port that outputs the imaging beam to the material processing system and that receives at least one reflection component of the imaging light reflected from the PCR;
an optical combiner that combines the reflection component of the imaging light and at least another component of the imaging light to produce an interferometry output, the interferometry output based on an optical path length taken by the imaging beam and the reflection component compared to an optical path length taken by the at least another component of the imaging light; and
an interferometry output processor that processes the interferometry output to determine at least one characteristic of the PCR;
wherein the directing element directs the imaging beam to a selected imaging beam position that is offset relative to the processing beam in the PCR and is selected from at least one previous imaging beam position.
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Abstract
A method, apparatus, and system are provided to monitor and characterize the dynamics of a phase change region (PCR) created during laser welding, specifically keyhole welding, and other material modification processes, using low-coherence interferometry. By directing a measurement beam to multiple locations within and overlapping with the PCR, the system, apparatus, and method are used to determine, in real time, spatial and temporal characteristics of the weld such as keyhole depth, length, width, shape and whether the keyhole is unstable, closes or collapses. This information is important in determining the quality and material properties of a completed finished weld. It can also be used with feedback to modify the material modification process in real time.
35 Citations
30 Claims
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1. An apparatus comprising:
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a low coherence imaging light source that produces an imaging beam that is applied by a material processing system, wherein the material processing system implements a material modification process using a material processing energy source that produces a material processing beam that is applied to the material, wherein the material processing beam creates a phase change region (PCR) in the material; at least one directing element that directs the imaging beam at one or more selected imaging beam positions in the PCR; at least one optical element that sets a numerical aperture of the imaging beam so as to resolve a depth of the PCR at a plurality of locations within the PCR; at least one input-output port that outputs the imaging beam to the material processing system and that receives at least one reflection component of the imaging light reflected from the PCR; an optical combiner that combines the reflection component of the imaging light and at least another component of the imaging light to produce an interferometry output, the interferometry output based on an optical path length taken by the imaging beam and the reflection component compared to an optical path length taken by the at least another component of the imaging light; and an interferometry output processor that processes the interferometry output to determine at least one characteristic of the PCR; wherein the directing element directs the imaging beam to a selected imaging beam position that is offset relative to the processing beam in the PCR and is selected from at least one previous imaging beam position. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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26. A method comprising:
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using a low coherence imaging light source to apply an imaging beam to a material processing system, wherein the material processing system implements a material modification process using a material processing energy source that produces a material processing beam that is applied to the material, wherein the material processing beam creates a phase change region (PCR) in a material; using at least one directing element to direct the imaging beam at one or more selected imaging beam positions in the PCR; using at least one optical element to set a numerical aperture of the imaging beam so as to resolve a depth of the PCR at a plurality of locations within the PCR; outputting the imaging beam to the material processing system and receiving at least one reflection component of the imaging light from the PCR; combining the reflection component of the imaging light and at least another component of the imaging light to produce an interferometry output, the interferometry output based on an optical path length taken by the imaging beam and the reflection component compared to an optical path length taken by the at least another component of the imaging light; processing the interferometry output to determine at least one characteristic of the PCR; and directing the imaging beam to a selected imaging beam position that is offset relative to the processing beam in the PCR and is selected from at least one previous imaging beam position. - View Dependent Claims (27, 28, 29, 30)
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Specification