D Scan

D-scan refers to the image produced when the data collected from an ultrasonic inspection is plotted on an end view of the component. The true definition according to BS EN 1330-4:2000 is the 'Image of the results of an ultrasonic examination showing a cross-section of the test object perpendicular to the scanning surface and perpendicular to the projection of the beam axis on the scanning surface'.

The D-scan view is perpendicular to both the C-scan and the B-scan. However, like the C-scan, the D-scan usually shows ultrasonic data collected through the whole or part of the inspection volume.
The D-scan allows quick discrimination of indications along a weld by presenting their position in depth from the scanning surface. D-scans are often used in the presentation and analysis of TOFD data.

C Scan

The C-scan presentation provides a plan-type view of the location and size of test specimen features. The plane of the image is parallel to the scan pattern of the transducer. C-scan presentations are produced with an automated data acquisition system, such as a computer controlled immersion scanning system. Typically, a data collection gate is established on the A-scan and the amplitude or the time-of-flight of the signal is recorded at regular intervals as the transducer is scanned over the test piece. The relative signal amplitude or the time-of-flight is displayed as a shade of gray or a color for each of the positions where data was recorded. The C-scan presentation provides an image of the features that reflect and scatter the sound within and on the surfaces of the test piece.
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a two dimensional presentation of data displayed as a top or planar view of a test piece, similar in its graphic perspective to an x-ray image, where color represents the gated signal amplitude or depth at each point in the test piece mapped to its position. Planar images can be generated on flat parts by tracking data to X-Y position, or on cylindrical parts by tracking axial and angular position. For conventional ultrasound, a mechanical scanner with encoders is used to track the transducer's coordinates to the desired index resolution. The images that follow conceptually show C-scans of a reference block made with a conventional immersion scanning system using a focused immersion transducer.
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C-scan from a phased array system is very similar to the one from the conventional probe seen above. With phased array systems however, the probe is typically moved physically along one axis while the beam electronically scans along the other according to the focal law sequence. Signal amplitude or depth data is collected within gated region of interest just as in conventional C-scans. In the case of phased arrays, data is plotted with each focal law progression, using the programmed beam aperture.

B scan

A Single Value B-scan is commonly used with conventional flaw detectors and corrosion thickness gages to plot the depth of reflectors with respect to their linear position. The thickness is plotted as a function of time or position while the transducer is scanned along the part to provide its depth profile. Correlating ultrasonic data with actual transducer position allows a proportional view to be plotted and allows the ability to correlate and track data to specific areas of the part being inspected. This position tracking is typically done through the use of electromechanical devices known as encoders. These encoders are used in fixtures which are either manually scanned or in automated systems that move the transducer by a programmable motor-controlled scanner. In either case the encoder records the location of each data acquisition with respect to a desired user-defined scan pattern and index resolution.

In the case below, the B-scan shows two deep reflectors and one shallower reflector, corresponding to the positions of the side drilled holes in the test block.
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The B-scan presentations is a profile (cross-sectional) view of the test specimen. In the B-scan, the time-of-flight (travel time) of the sound energy is displayed along the vertical axis and the linear position of the transducer is displayed along the horizontal axis. From the B-scan, the depth of the reflector and its approximate linear dimensions in the scan direction can be determined. The B-scan is typically produced by establishing a trigger gate on the A-scan. Whenever the signal intensity is great enough to trigger the gate, a point is produced on the B-scan. The gate is triggered by the sound reflecting from the backwall of the specimen and by smaller reflectors within the material. In the B-scan image above, line A is produced as the transducer is scanned over the reduced thickness portion of the specimen. When the transducer moves to the right of this section, the backwall line BW is produced. When the transducer is over flaws B and C, lines that are similar to the length of the flaws and at similar depths within the material are drawn on the B-scan. It should be noted that a limitation to this display technique is that reflectors may be masked by larger reflectors near the surface.

A Scan

A scan is an amplitude modulation scan. It gives the information in the form of one dimensional. it is used to detect the presence of flaws in the materials. A-scan ultrasound biometry, commonly referred to as an A-scan

A data presentation method by which intelligence signals from a signal object located are displayed. As generally applied to pulse echo ultrasonics, the horizontal and vertical sweeps are proportional to time or distance and amplitude or magnitude respectively. Thus the location and magnitude of acoustical interface are indicated as to depth below the transducer.

The most basic presentation of ultrasonic waveform data is in the form of an A-scan, or waveform display, in which echo amplitude and transit time are plotted on a simple grid with the vertical axis representing amplitude and the horizontal axis representing time. The example below shows a version with a rectified waveform; unrectified RF displays are also used. The red bar on the screen is a gate that selects a portion of the wave train for analysis, typically measurement of echo amplitude and/or depth.