Optical detection of ultrasound using an apertureless near-field scanning optical microscopy system

Phillip Ahn, Zhen Zhang, Cheng Sun, Oluwaseyi Balogun

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Scopus citations

Abstract

Laser ultrasonics techniques are power approaches for non-contact generation and detection of high frequency ultrasound on a local scale. In these techniques, optical diffraction limits the spatial information that can be accessed from a measurement. In order to improve the lateral spatial resolution, we incorporate an apertureless near-field scanning optical microscope (aNSOM) into laser ultrasonics setup for local detection of laser generated ultrasound. The aNSOM technique relies on the measurement of a weak backscattered near-field light intensity resulting from the oblique illumination of a nanoscale probe-tip positioned close to a sample surface. We enhance the optical near-field intensity by coupling light to surface plasmon polaritons (SPPs) on the shaft of an atomic force microscopy (AFM) cantilever. The SPPs propagate down the AFM shaft, localize at the tip apex, and are backscattered to the far-field when the separation distance between the probe tip and the sample surface is comparable to the probe-tip radius. The backscattered near-field intensity is dynamically modulated when an ultrasonic wave arrives at the sample surface leading to a transient change in the tip-sample separation distance. We present experimental results detailing measurement of broadband and narrowband laser generated ultrasound in solids with frequencies reaching up to 180 MHz range.

Original languageEnglish (US)
Title of host publicationReview of Progress in Quantitative Nondestructive Evaluation, Volume 32
EditorsDale E. Chimenti, Donald O. Thompson
PublisherAmerican Institute of Physics Inc.
Pages360-366
Number of pages7
ISBN (Electronic)9780735411296
DOIs
StatePublished - Jan 1 2013
Event39th Annual Review of Progress in Quantitative Nondestructive Evaluation, QNDE 2012 - Denver, United States
Duration: Jul 15 2012Jul 20 2012

Publication series

NameAIP Conference Proceedings
Volume1511
ISSN (Print)0094-243X
ISSN (Electronic)1551-7616

Conference

Conference39th Annual Review of Progress in Quantitative Nondestructive Evaluation, QNDE 2012
CountryUnited States
CityDenver
Period7/15/127/20/12

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Keywords

  • Apertureless Near-field Scanning Optical Microscope
  • Laser Ultrasonics Sub-surface Imaging
  • Surface Plasmon Polaritons

ASJC Scopus subject areas

  • Physics and Astronomy(all)

Cite this

Ahn, P., Zhang, Z., Sun, C., & Balogun, O. (2013). Optical detection of ultrasound using an apertureless near-field scanning optical microscopy system. In D. E. Chimenti, & D. O. Thompson (Eds.), Review of Progress in Quantitative Nondestructive Evaluation, Volume 32 (pp. 360-366). (AIP Conference Proceedings; Vol. 1511). American Institute of Physics Inc.. https://doi.org/10.1063/1.4789070