Home   >   Blog

Phased Array Probe: Definition and Application

In this blog post, you’ll read:Ever wondered what a phased array probe can do and where it is applicable? This is the basic post for you to learn about the pa probe.

Table of Contents

Ever wondered what a phased array probe can do and where it is applicable? 

Several types of phased array probes are determined by the kind of inspection or the type of measurement it is required to perform. Phased array probes are deployed as a form ultrasonic testing tool that detects cracks and voids which may arise from corrosion. And sometimes, it is used to determine coating and material density. 

Many suppliers of this tool have varying specifications for the phased array probe type, and they supply based on customers’ requirements. 

So, if you want to find out more, make sure you read to the end. 



I. What is Phased Array Probe?


To begin with, a phased array probe is a piece of non-destructive ultrasonic testing equipment composed of numerous piezoelectric crystals capable of transmitting and receiving ultrasound signals individually and analyzed as a group.

Application of time delays is an essential factor for beam focusing on generating a constructive interference of ultrasonic waves. This interference enables the energy generated to be focused on the test objects’ required depths.

Consequently, they are typically connected to specially adapted drive units which enable the probes to concurrently emit and receive via each different channel. One good thing about phased array probes is that they can be programmed to act in specific ways and patterns that help accurately identify and analyze flaws. 


➤ Related Article: What is Ultrasonic Piezoelectric Transducers?


II. What are the Features of Phased Array Probes?


Phased array probes have varying features. A phased array probe usually consists of between sixteen to one hundred and twenty-eight elements or even more as some are up to two hundred and fifty-six pieces.

Therefore, due to the small-faced features of phased array probes that enable imaging of small areas and switching the focus of beam wavelength, their length is typically two to three centimeters long. Their frequency is usually within the 2 -10 MHz range, and this is the frequency range most phased array probes require to perform their flaw detection roles.

Many phased array probes are angle beam types fabricated for deployment with either a plastic wedge or a straight plastic shoe. Furthermore, as the element width gets smaller, it enables increased beam steering capability. However, expanded area coverage requires more elements, which comes at an increased cost.



III. Types of Phased Array Probes


Here are the various types of phased array probes that are available in the industry today. 


  • Angle Beam Probes: angle beam probes are available in different shapes and sizes, and they allow for testing in standard angles of forty-five, sixty, and seventy degrees. Angle beam probes have a frequency range between five hundred kilohertz and ten megahertz. Although lower frequency ensures greater penetration, higher frequencies provide better resolution to help detect smaller flaws.
  • Weld Inspection Probes: are perfect for performing automated and manual inspections of thick welds and forgings, castings, tubes, pipes, including machined and structural elements for welding and crack defects.
  • Linear Phased Array Probe: These are probes made up of a set of components aligned and connected towards an axis on the test object, which allows a beam to be moved, deflected, and focused along a plane.


Linear Immersion Phased Array Transducer


  • Corrosion Probes: This electrochemical response monitoring instrument is used to document data on live corrosion rates in chemical environments. These probes are typically deployed directly with the metallic objects liable to corrosion. They are also deployed in extracting electrical resistance data in chemical, industrial, and petroleum processing environments.
  • Immersion Probes: Immersion probes are generally fabricated to transmit ultrasound in applications where the test objects are entirely or partially immersed in water. This process ensures an unvarying and quick coupling technique for fast scanning of parts. A focusing lens is usually added to improve probe sensitivity and performance in a test part or object.
  • Curved Array Probes: These probes are waterproof up to one meter underwater because they are made with a corrosion-resistant stainless-steel compartment. They are also appropriate for use with adjustable immersion wedges and are regularly utilized to inspect carbon fiber reinforced polymers (CFRP).


Concave Phased Array Transducer


  • Flexible Phased Array Probe: The flexible phased array probe exhibits a remarkable ability to assume complex shape inspection on parts such as elbows. It can also scan complicated components with varying geometries and execute high-resolution density mapping. The flexible probe generates sector and linear scans similar to a standard phased array probe.
  • Matrix Array Probes: These probes have an active area that can be divided into two dimensions in various elements, and these divisions take different shapes or forms from sectored rings to a checkerboard shape. Matrix array probes are very resourceful when accessibility becomes a problem or when defects are detected in various locations.



IV. What are the Applications of Phased Array Probes?


Phased array probes are extensively employed in non-destructive testing (NDT) in numerous industrial sectors, including pipelines, power generation, and construction. This advanced NDT is utilized to identify discontinuities, i.e., cracks or flaws, and thereby determine an element’s quality.

The phased array probe has three different application concepts that interrelate with the various techniques of applying the probes in ultrasonic testing.


Electronic Scanning

This is a theory whereby not all the probe components are deployed simultaneously as the drive element employs dynamic complexes to dispense active units within the elements of the probe. It allows for beam movement in space via the activation of different active gaps, with each made up of various units of a phased array probe.

In essence, this theory is employed in the in-line examination of bars, plates, or welds and can be used for testing tubes.


The Electronic Focusing

Strictly speaking, this concept derives from the use of electronic delays adapted during emitting and receiving elements along every channel of the probe. These delays compare to that of a focusing lens, which ensures focusing to numerous various depths.

Electronic focusing permits just one phased array probe to be employed in a situation where many single-element probes with varying focal distances should have been employed. It is very much applicable in heavy plate testing.


Electronic Deflection

This notion also utilizes the delay laws of electronic focusing. The modified delay law, i.e., the delays adapted to all the channels, is calculated to accord the emitted beam an angle of incidence.

Now that these application principles have been established, it would be noteworthy to note that these three principles can be jointly deployed to resolve applications like the inspection of tubes and welds.


Here’s the guide on top phased array manufacturers, continue to read if you are interested in.




To round up, a phased array probe helps eradicate several inspections where a single inspection could be executed with the appropriate phased array probe.

Its features consist of elements ranging from ten to its highest form of two hundred and fifty-six elements, dependent on the type of phased array probe, with a frequency of about two to ten megahertz.

However, some of its different types include the matrix array probe, corrosion probe, linear probe, curved array probe, immersion probe, weld inspection probe, etc.

Finally, a significant advantage is that conventional mechanical scanning has been replaced with faster electronic scanning. Electronic focusing permits the usage of one probe to inspect at different depths. Lastly, electronic deflection enables the angles of incidence to be varied by a single probe. Thereby reducing costs as it saves adjustment and inspections time.

4.9/5 - (70 votes)