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A sensitive electromagnetic acoustic transducer for picometer-scale ultrasonic displacement measurements
Author(s)
Dewhurst, R. J.
Date Issued
March 13, 2006
Type
Article
Abstract
The paper presents a novel design of an electromagnetic acoustic transducer (EMAT) for non-contact ultrasonic measurements. An EMAT sensor has been miniaturized with an overall receiver size to 1.0 cm diameter. It has been combined with a specially designed low noise preamplifier. Calibration procedures with a Michelson interferometer revealed that the EMAT sensor detected small displacement amplitudes as low as 1.0 ± 0.2 pm in aluminium samples, with a signal bandwidth up to 7.5 MHz (-3 dB). Alternatively, the sensitivity figure can be expressed in terms of a noise-equivalent displacement spectrum as 4.2 × 10 -17 mHz -1/2. The absolute sensitivity of the EMAT was 1.98 ± 0.50 V pm -1 for the detection of longitudinal ultrasonic waves. This sensitivity is compared with other forms of ultrasonic transducer. © 2005 Elsevier B.V. All rights reserved.
Citation
Sensors and Actuators A Physical, 127(2), 345-354, 2006