Focussing of ultrasonic waves in air using a micromachined Fresnel zone-plate
UNSPECIFIED. (1997) Focussing of ultrasonic waves in air using a micromachined Fresnel zone-plate. ULTRASONICS, 35 (4). pp. 275-285. ISSN 0041-624XFull text not available from this repository.
An ultrasonic Fresnel zone-plate has been micromachined from a thin stainless steel disk for the purpose of focussing high-frequency ultrasonic waves in air. This zone-plate, which was designed with a focal length of 7.5 mm, consisted of five concentric stainless steel rings that were separated from one another by narrow air-channels. The zone plate was fitted to a micromachined air-coupled capacitance transducer source, and the radiation profile measured by a second 1 mm diameter air-coupled capacitance receiver. It is shown that the resultant spot size (for an operating frequency of 580 kHz) was 0.8 mm, with a 3 mm depth-of-held. Comparison to an existing theoretical model shows that the zone-plate is operating as might be expected, but that improvements might be obtained by further research. (C) 1997 Elsevier Science B.V.
|Item Type:||Journal Article|
|Subjects:||T Technology > TA Engineering (General). Civil engineering (General)
|Journal or Publication Title:||ULTRASONICS|
|Publisher:||ELSEVIER SCIENCE BV|
|Number of Pages:||11|
|Page Range:||pp. 275-285|
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