Ultrasound Phased Array
R/D Tech's Technology Information
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Dynamic beam control
To generate a beam, the various probe elements are pulsed at slightly different times. By precisely controlling the delays between the probe elements, beams of various angles, focal distance, and focal spot size can be produced. The illustration shows how a beam can be focussed at an angle and a given distance by firing the left elements slightly ahead of the corresponding elements on the right. It is possible to change the angle, focal distance, or focal spot size, simply by changing the timing to the various elements.
The sectorial scan is a real-time side view generated from a single inspection point, without any physical motion from the probe. Using R/D Tech's FOCUS phased-array system, the probe emits various beam angles, at a rate of up to 20,000 different angles per second. Note the direct relationship between the location and size of the side-drilled holes of the test block and the sector scan image.
Inspection of complex shapes
The capacity to produce at will, and under computer control, various beam angles and focal lengths can be used to inspect parts with complex shapes such as turbine disks, turbine blade root, reactor nozzles, and other complex shapes. Note here the precise defect indication shown on the top, side, and front view of the root area of the blade.
Beam multiplexing can be used to reduce the number of scan lines when inspecting a wide surface. A normal system with conventional transducers would require multiple passes to reach the required spatial resolution (left). With R/D Tech's phased-array technology, the beam is quickly multiplexed along a long probe, allowing scans a few inches wide at a time (right), reducing the number of mechanical passes.
Another feature of R/D Tech's FOCUS phased-array equipment is the capability to generate a beam with a few probe elements and then to time-multiplex the beam to other elements of the probe. This, in effect, moves the beam along the probe axis, with no mechanical movement from the probe.
The same principle can be applied to the inspection of welds to replace dual-axis weld inspections with a single-axis inspection, increasing inspection speed by a factor 10 or more. The beam is multiplexed within the probe and its focal length dynamically adjusted for optimum focusing on the weld line at all times. Because the beam angle and focal length are controlled from the software, it is easy to adapt to various material, thickness, and weld profiles.
Using circular array probes, an ultrasound beam can be formed using a few probe elements and the beam can then be moved in a circular fashion by shifting the active probe element. This can be applied to the inspection of bars, rods and tubes. Rotation speed of 10,000 r/min can be achieved, without any mechanical motion.
Dynamic depth focusing
Another feature of R/D Tech's FOCUS phased-array system is the ability to dynamically focus the beam within a part, in real time. The image on the right shows the inspection of a standard calibration block with a normal transducer with a fixed focus set at around half depth. Compare this with the inspection of the same block but with dynamic focusing (left). dynamic focusing allows inspections of thick components with flaws in perfect focus, regardless of the depth with a single probe.
Ultrasound phased array data acquisition system
R/D Tech's Tomoscan FOCUS is, by far, the most widely used NDT phased array system in the world. The FOCUS provides a revolutionary tool for UT data acquisition, allowing variation of the beam angles, focal distances, and focal spot under software control. Beam multiplexing often allows the elimination of one axis of motion, replacing raster scans and helix scans with a single axis scan, resulting in scan speeds that are 10 to 50 times faster.
- System bandwidth of 650 kHz to 20 MHz (–3dB)
- Maximum pulsing rate of 20 kHz
- Pulse-echo or transmit/receive inspection mode (dynamically selectable)
Multiple probe capability
The system supports up to 4 probes of 32 elements in pulse-echo configuration or any combination of probes up to 128 elements.