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.
Ultrasonics in Diagnosis of Abdominal Swellings
Ultrasonic echo-sounding (sonar) has something to offer in the field of diagnosis, particularly in the case of large tumour masses within the abdomen (Donald et al., 1958; Donald and Brown, 1961 ; MacVicar, 1962). Our experience, predominantly of course gynaecological and obstetrical, extends over many hundreds of cases, and we are gradually building up a library of characteristic diagnostic appearances. Some of these are presented here. Fig. A shows the apparatus at present in use at the Western Infirmary in Glasgow, which has been developed and built for us by Smiths Industrial Division Ltd. It will be noted that the patient does not have to be moved from heir bed, and the only inconvenience is the application of a film of olive oil to the abdominal surface. With the use of a polaroid camera a picture is obtainable in longitudinal or transverse section within two or three minutes (Fig l, Special Plate-normal). Fig. 2 (Special Plate) shows in diagrammatic form the scanning technique which we have developed in order to