Due to the limitations outlined above for ultrasound-based methods, other AL measurement techniques based upon optical principles have predominantly superseded use of A-scans
in the myopia research field.
The frequency domain image is one of several images made by transforming the A-scans
In comparison with the existing Pundit Lab(+), the Pundit PL-200 provides an extended range of measurement modes and superior features for on-site testing: Assessing the concrete uniformity using standard A-Scans
and the new Line Scan functionality, estimating the compressive strength of concrete or measuring the surface velocity and the depth of perpendicular cracks.
used to measure the anterior chamber depth, lens thickness, vitreous chamber length, and axial length, was the Alcon ultrasonic scan using a frequency of 10 MHz.
This phenomenon is displayed on A-scan
, as high reflectivity with strong sound attenuation.
The strength of the reflected signals is plotted as a waveform called an A-scan
(A stands for "amplitude").
An oscilloscope display of the echo pattern, known as an A-Scan
, shows defects as areas of higher contrast in the image.
Material has been added on exophthalmometry and A-scan
For example, the latest precision thickness gauge offers a snapshot A-scan
display as well as a digital display.
This feature can be browsed or searched to learn more about tests ranging from the A-scan
, used to determine the length of the eye, to the Zung Self-Rating Depression Scale (SDS).
In an A-scan
presentation, the initial sound pulse and the resulting rear wall or discontinuity reflections are displayed on a cathode ray tube (CRT).
RadarView receives, processes and scan converts multiple channels of radar video in normal PPI (plan position indicator) view, and, for more specialist requirements, supports B-Scan and A-Scan
formats - the latter is especially useful for radar configuration and set-up.
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with increasing depth), OCT produces a 1-D axial a-scan
Although conventional A-scan
ultrasonography is the gold standard method for measuring ACD, noncontact methods and devices such as partial coherence interferometry, slit-scanning topography, anterior segment optical coherence tomography and Scheimpflug imaging have become widely used in clinics in recent years.