The inspection of thick plates of large dimensions is a productivity challenge. While satisfying high-resolution requirements for defect detection and sizing (AA class, aerospace grade), the inspection speed must also satisfy production requirements.
Electronic scanning of only one aperture or virtual probe (VP) across the whole phased-array probe is time-consuming and is often limited by the height of the water column and/or the thickness of the component. One approach developed by M2M is to fire simultaneously several apertures at the same time at distinct locations of the phased-array probe, then electronic scan all these apertures simultaneously. This allows to inspect several locations along the sample at the same time while maintaining the same beam aperture. This technique keeps the resolution of the original electronic scanning while increasing the productivity.
Another approach developed by M2M is to fire all the elements of the array at the same time without any delay law and perform an electronic scanning in reception. The convolution between reception and transmission patterns provides a similar beam distribution as an electronic scanning. This makes it perfect for the inspection of thick components for which a long water-path is typically being used (to avoid repeats of the surface echo in the region of interest). This super-fast mode provides unparalleled inspection speed.
A comparison between the three inspection modes is illustrated on the animation below.
picture of aluminum plates. Typical thickness varies between 30 and 260mm.