A variant of the phased array ultrasonic process, known as RapidScan (see Fig.1), has been developed for inspecting large areas without the need for immersion of the component. It uses a wheel probe, containing an array transducer, which is scanned across the surface of a component generating an instant picture of the structure under test.

This portable system utilises a 128-channel pulsar receiver that can generate beams from up to 32 channels. The system has a high-speed data capture card, which controls the beam-forming electronics and processes the raw ultrasound data to deliver high frame rate B-scans and rapid processing for C-scan imaging. The array is deployed in a wheel probe to permit scanning of curved structures and components with the use of very little couplant. The system can display any combination of A-scans, real-time, high frame rate B-scans or C-scans. Array frequencies of 1, 2 and 5MHz with beam dimensions from 6mm to 16mm allow inspection of a range of inspections of metallic and composite structures. Wheel widths of up to 100mm have been successfully utilised to permit high-resolution scans (0.8mm scan pitch) with full waveform capture, at speeds of up to 200mm/s. The full waveform capture allows post acquisition analysis of archived data.

The Rapidscan 2 is able to produce auditable images of a wide range of flaws and material conditions found in large area composite structures. These include impact damage, porosity, delaminations and fibre wrinkles. The ability to operate at a variety of frequencies allows interrogation of features and defects at various depths within the structure. The system incorporates an image stitching feature that joins a number of inspection images together to permit the assessment of large areas.

Another piece of equipment for area scanning is the DSL Andscan system which has a unique manually manipulated R-? scanner arm. (shown in Fig.2). In this, the scanner base incorporates encoders that register the position and orientation of the probe head. However, if the probe is held stationary and the scanner base is moved, this movement is also registered. Thus, by first scanning the complete area that can be covered within the limits of the arm for one base position and then moving the base to new locations, a large area can be fully mapped.