Annular Array Search Units and Their Potential Application in Conventional Ultrasonic Testing Systems
This paper is based on a program to investigate the potential of multi-element annular arrays for practical application in ultrasonic testing systems. The annular array is comprised of coaxially-located, ring-shaped piezoelectric elements. By providing excitation pulses in a spherical time relationship, the transmitted beam may be focused at a specific range. By electronic switching, the focal point can be placed at various distances in the material under examination, Of particular interest is the length over which the beam can be held in collimation. Fabrication methods, delayed excitation techniques, and beam patterns in water and steel are described,
New equipment and transducers for ophthalmic diagnosis
Abstract In his clinical experience the author has relied on A-scan presentation used in combination with a special ophthalmoscope. A-scan and B-scan he has looked on as complementary; A-scan for intraocular examination and B-scan for the stationary orbital structures, largely because the patient is likely to move his eye during a mechanical B-scan. To expand the use of B-scan in intraocular work he has devised a switched system in which the signal is switched cyclically along an arc of ten transducers. A cycle takes approximately 30 ms and the display is an instantaneous B-scan of the eye and surroundings.
A Two Dimensional Electronically Focused Imaging System
Abstract : A two dimensional acoustic imaging device, with electronic focusing and scanning in both directions was constructed. The device is designed to work with 2.25 MHz acoustic waves. It employs M piezoelectric elements in a transmitting transducer, which produce a beam focused and scanned in the y direction. An N element receiving transducer is used to focus and scan in the x direction. This makes it possible to obtain M by N resolvable spots with only M plus N elements, a considerable saving in complexity. The phase reference for the transmitter and receiver are supplied by frequency modulated chirp signals sent along acoustic surface wave delay lines. One of the novel features of this device is the ability to obtain an arbitrary scan velocity, even a stationary focus, with the transmitter.