Full matrix capture with time-efficient auto-focusing of unknown geometry through dual-layered media

This paper presents a method for time-efficient auto-focusing through a profile of unknown geometry applicable to immersion testing. It is demonstrated that capture of the complete time domain signal using the full matrix capture technique allows for rapid ultrasonic profile mapping of a complex geometry through the use of Fermat's principle to find the point of incidence at the reflective interface. Through advanced optimisation and parallelisation of the algorithms over the graphic processing unit, it is demonstrated that rapid inspections are possible, given that the geometry falls within the limits defined for the algorithm. To demonstrate this, a linear array transducer is mounted to a perspex shoe where auto-focusing is performed to generate ultrasonic imagery of side-drilled holes through a curved surface.