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US 12,474,300 B2Granted
Lift-off compensated eddy current system
AssigneeEvident Canada, Inc.
InventorsRémi Leclerc, Benoit Lepage
Life of this patent
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Abstract
Techniques for compensating the sensitivity variations induced by lift-off variations for an eddy current array probe. The techniques use the eddy current array probe coils in two separate ways to produce a first set of detection channels and a second set of lift-off measurement channels without the need to add coils 5 dedicated to the lift-off measurement operation.
Claims10
A lift-off compensated multi-frequency eddy current system for indicating a flaw in a material under test, the system comprising:
- an eddy current probe having a set of interface coils, the set of interface coils including:
- at least one first interface coil arranged to induce a first eddy current in the material in response to a first input excitation signal frequency;
- at least one second interface coil arranged to induce a second eddy current in the material in response to a second input excitation frequency that is different from the first input excitation frequency, wherein the first and the second input excitation frequencies are applied to the at least one first interface coil and the at least one second interface coil concurrently;
- and
- at least one third interface coil arranged to sense a response signal, wherein the response signal is a composite response to the first eddy current and the second eddy current;
- and
- a back-end circuit coupled with the at least one third interface coil, the back-end circuit to:
- receive the response signal;
- and
- extract a lift-off signal and a defect signal from the response signal.
7 more elements
A multi-frequency method for indicating a flaw in a material under test, the method comprising:
- using at least one first interface coil, inducing a first eddy current in the material under test in response to a first input excitation signal frequency;
- using at least one second interface coil, inducing a second eddy current in the material under test in response to a second input excitation frequency that is different from the first input excitation frequency, wherein the first and the second input excitation frequencies are applied to the at least one first interface coil and the at least one second interface coil concurrently;
- using at least one third interface coil, sensing a response signal, wherein the response signal is a composite response to the first eddy current and the second eddy current;
- and
- extracting, using a back-end circuit coupled with the at least one third interface coil, a lift-off signal and a defect signal from the response signal.
2 more elements
Dependencies are inferred from the claim text.