CESAM - Coded excitation scanning acoustic microscope

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Meriläinen , A , Hyvönen , J T J , Salmi , A & Haeggström , E 2021 , ' CESAM - Coded excitation scanning acoustic microscope ' , Review of Scientific Instruments , vol. 92 , no. 7 , 074901 . https://doi.org/10.1063/5.0047351

Title: CESAM - Coded excitation scanning acoustic microscope
Author: Meriläinen, Antti; Hyvönen, Jere Tapio Johannes; Salmi, Ari; Haeggström, Edward
Contributor organization: Doctoral Programme in Materials Research and Nanosciences
Department of Physics
Materials Physics
Doctoral Programme in Particle Physics and Universe Sciences
Date: 2021-07-01
Language: eng
Number of pages: 7
Belongs to series: Review of Scientific Instruments
ISSN: 0034-6748
DOI: https://doi.org/10.1063/5.0047351
URI: http://hdl.handle.net/10138/346233
Abstract: Scanning acoustic microscopy (SAM) finds use across many disciplines, e.g., biology, industrial quality control, and materials science, thanks to its unique ability to quantify mechanical sample properties combined with its high resolution. However, such imaging is often slow, especially if averaging is necessary. We present a Coded Excitation Scanning Acoustic Microscope (CESAM) that employs coded signals and show that it produces images of higher signal-to-noise ratios (SNRs) than the classical SAM in a comparable measurement time. The CESAM employs coded signals instead of the short bursts used in traditional SAMs, and we employ both linear and non-linear frequency modulation. Our results show that compared to the SAM approach, this modulation increases the SNR by 16.3 dB (from 39.9 to 56.2 dB) and reduces the echo duration by 26.7% when we employ a linear chirp to the transducer with a nominal bandwidth of 130-370 MHz. Driving the transducer with a broader bandwidth signal using non-linear chirps (100-450 MHz), we obtained a SNR increase of 10.3 dB and a reduced echo duration of 70.5%. The shorter echo duration increases z-resolution, whereas the lateral resolution remains limited by the wavelength. Finally, we show that by using these coded signals, one can obtain enhanced image quality relative to the standard actuation of the same measurement time. Our results have potential to invigorate the field of acoustic microscopy, especially with samples where the enhanced SNR and/or contrast-to-noise ratio is crucial for image quality.
Subject: 114 Physical sciences
arbitrary waveform generator
ultrasonic instruments
materials imaging
digital signal processing
digital oscilloscope
material characterization methods
acoustic microscopy
Pulse compression
Peer reviewed: Yes
Rights: unspecified
Usage restriction: openAccess
Self-archived version: publishedVersion

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