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Broadband electrostatic acoustic transducer for ultrasonic measurements in liquidsA broadband capacitive electrostatic acoustic transducer (ESAT) has been developed for use in a liquid environment at megahertz frequencies. The ESAT basically consists of a thin conductive membrane stretched over a metallic housing. The membrane functions as the ground plate of a parallel plate capacitor, the other plate being a dc biased electrode recessed approximately 10 microns from the electrically grounded membrane. An ultrasonic wave incident on the membrane varies the membrane-electrode gap spacing and generates an electrical signal proportional to the wave amplitude. The entire assembly is sealed for immersion in a liquid environment. Calibration of the ESAT with incident ultrasonic waves of constant displacement amplitude from 1 to 15 MHz reveals a decrease in signal response with increasing frequency independent of membrane tension. The use of the ESAT as a broadband ultrasonic transducer in liquids with a predictable frequency response is promising.
Document ID
19790036731
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Cantrell, J. H., Jr.
(NASA Langley Research Center Hampton, VA, United States)
Heyman, J. S.
(NASA Langley Research Center Hampton, Va., United States)
Yost, W. T.
(NASA Langley Research Center Hampton, VA, United States)
Torbett, M. A.
(NASA Langley Research Center Hampton, VA, United States)
Breazeale, M. A.
(Tennessee, University Knoxville, Tenn., United States)
Date Acquired
August 9, 2013
Publication Date
January 1, 1979
Publication Information
Publication: Review of Scientific Instruments
Volume: 50
Subject Category
Instrumentation And Photography
Accession Number
79A20744
Distribution Limits
Public
Copyright
Other

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