Phased Array Inspection
Phased Array (UT) Phased Array is an ultrasonic testing technique that uses specialised multi-element “array” transducers and pulses. These elements are in a patterned sequence called “phasing”. This phasing sequence allows wave steering, focusing and scanning. This is all performed electronically.
Phased array technology uses an arrangement of antenna elements where the relative phase of each element is varied to steer the radiation pattern or beam. The beam can be aimed in various directions electronically, overcoming the limited speed and reliability problems of a mechanically steered antenna.
The sensor consists of a phased array probe that is 25–100 mm (1–4 in.) long and contains between 32 and 128 elements. When these elements are excited using different time delays (focal laws), the beams can be steered at different angles, focused at different depths, or multiplexed over the length of a long array, creating electronic movement of the beam. The electronic indexing is performed so fast that a 100 mm (4 in.) line length is covered by the ultrasonic beams in milliseconds
Three modes of scanning are obtained with respect to the pulses of Ultrasound
- A-scan – Amplitude mode display gives only one-dimensional information about the given specimen. In this, a single transducer is used to transmit and receive the pulses from the specimen
- B-Scan – B-Scan the transducer can be moved rather than keeping in a fixed position.
- T-M scan or C-scan – This combines the features of both A-Scan as well as B-Scan. In this the transducer is held stationary as in A-scan and echoes appear as dots in the B-scan.
