Method and system for high-resolution ultrasonic imaging of small defects or anomalies
This invention relates to a method and a system for ultrasonic detection and imaging of small defects inside or at the surface of an object. An improved version of the frequency-domain Synthetic Aperture Focusing Technique (F-SAFT) based on the angular spectrum approach is used. This method is of particular interest when ultrasound is generated by a laser and detected by either a contact ultrasonic transducer or a laser interferometer.
This technology is available for licensing. There is an opportunity for this invention to be developed for particular applications and for demonstration of the final product through a collaborative research project. The business opportunity may be referred to by its NRC ID: 11037
Applications for this technology are extensive, from manufacturing and quality control of products in various industries to the healthcare sector.
How it works
Ultrasound is a well-recognized technique for finding defects or discontinuities in objects. The proposed method drastically improves imaging of small defects that includes temporal deconvolution of the waveform data to enhance both axial and lateral resolutions, control of the aperture and of the frequency bandwidth.
Generated at a plurality of scanning positions at the surface of the object, backscattered ultrasound from the measurement grid is detected to provide an array of electrical signals which are digitally sampled, and a Fourier transform is performed on the array of signals to generate a new array of signals as a function of the temporal frequency. Each signal of the new array is then deconvolved with a reference signal to obtain an array of broadband signals corresponding to spike-like signals in the time domain. The system further performs a Fourier transform on the resulting array in the space domain to generate an array in 3D Fourier space that is back-propagated from the surface to a plane at depth z within the object. Then, the temporal frequency components are summed over a given bandwidth and the new array in 2D Fourier space is Fourier transformed back to the real object space to obtain the subsurface image at depth z.
- Non-destructive testing, applicable to objects of various shapes
- Improved resolution and signal-to-noise ratio
- Reduction of sampling requirements
- Reduction of inspection and processing time
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