 View of a fetus in the womb, created by a phased array instrument
 Principle of operation of phased array (PA). The PA probe consists of many small elements, each of which can be pulsed separately. In the figure the element on the right is pulsed first, and emits a pressure wave that spreads out like a ripple on a pond (largest semi-circle). The second to right element is pulsed next, and emits a ripple that is slightly smaller than the first because it was started later. The process continues down the line until all the elements have been pulsed. The multiple waves add up to one single wave front travelling at a set angle. In other words, the beam angle can be set just by programming the pulse timings.
 Weld examination by phased array. TOP: The phased array probe emits a series of beams to flood the weld with sound. BOTTOM: The flaw in the weld appears as a red indication on the instrument screen. Phased Array (PA) ultrasonics is an advanced method of testing that has applications in medical imaging and industrial nondestructive testing, originally pioneered by Albert Macovski of Stanford University.[1] The application of PA most familiar to the public is the image of the fetus in the womb. Similarly, when applied to steel, the PA image shows a slice that may reveal defects hidden inside a structure or weld. ImageMetadata File history File links Baby_in_ultrasound. ...
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Ultrasound is sound with a frequency greater than the upper limit of human hearing, this limit being approximately 20 kilohertz (20,000 hertz). ...
Medical ultrasonography (sonography) is an ultrasound-based diagnostic imaging technique used to visualize muscles and internal organs, their size, structures and possible pathologies or lesions. ...
// Nondestructive testing (also called NDT, nondestructive evaluation, NDE, and nondestructive inspection, NDI) is testing that does not destroy the test object. ...
Albert Macovski is an American Professor (Emeritus) at Stanford University, know for his many innovations in the area of imaging, particularly in the medical field. ...
A human fetus A fetus (or foetus, or fœtus – see below) is a developing mammal after the embryonic stage and before birth. ...
Welding is a fabrication process that joins materials, usually metals or thermoplastics, by causing coalescence. ...
Principle of operation
The PA probe is comprised of many small ultrasonic elements, each of which can be pulsed individually. By varying the timing, for instance by pulsing the elements one by one in sequence along a row, a pattern of interference is set up that results in a beam at a set angle. In other words, the beam can be steered electronically. The beam is swept like a search-light through the tissue or object being examined, and the data from multiple beams are put together to make a visual image showing a slice through the object.
Features of phased array - The method most commonly used for medical ultrasonography.
- Multiple probe elements produce a steerable, tightly focused, high-resolution beam.
- Produces an image that shows a slice through the object.
- Compared to conventional, single-element ultrasonic inspection systems, PA instruments and probes are more complex and expensive.
- In industry, PA technicians require more experience and training than conventional technicians.
Medical ultrasonography (sonography) is an ultrasound-based diagnostic imaging technique used to visualize muscles and internal organs, their size, structures and possible pathologies or lesions. ...
This article needs to be cleaned up to conform to a higher standard of quality. ...
Further Reading Online - Chapter One of Introduction to Phased Array Ultrasonic Technology Applications [text book on industrial PA] (PDF 1.42 MB)
- Chapter One of Phased Array Technical Booklet [reference booklet on industrial PA] (PDF 1.56 MB)
- Industrial applications of portable phased array [technical paper]
- Construction Weld Testing Procedures Using Phased Array [technical paper; based on computer modelling]
- Introduction to theory for medical phased array, Martin E. Anderson, Duke University
- Introduction to the physical principles of medical phased array imaging and Doppler, Peter N Burns, University of Toronto. (PDF, 2.2 MB)
- Phased array animated simulator [registration required after 5 minutes' use]
- Phased Array definition and lexicon
Books - Introduction to Phased Array Ultrasonic Technology Applications, R/DTech Inc. (now Olympus NDT), 2004.
- Automated Ultrasonic Testing for Pipeline Girth Welds, R/DTech Inc. (now Olympus NDT).
- ASME Boiler and Pressure Vessel Code. American Society Of Mechanical Engineers, 2004. Section V — Nondestructive Examination. [See Article 4 — Ultrasonic Examination Methods for Welds. Para E-474 UT-Phased Array Technique]
- ASME Code Case 2235-9, Use of Ultrasonic Examination in Lieu of Radiography — Section I and Section VIII, Divisions 1 and 2. American Society Of Mechanical Engineers, Approval Date: October 11, 2005. [See page 1, footnote 1 on phased array] (PDF here)
See also A giant phased-array radar in Alaska In telecommunication, a phased array is a group of antennas in which the relative phases of the respective signals feeding the antennas are varied in such a way that the effective radiation pattern of the array is reinforced in a desired direction and...
Phased array optics (PAO) is the technology of controlling the phase of light waves transmitting or reflecting from a two-dimensional surface by means of adjustable surface elements. ...
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