FreDomLUS

FreDomLUS

Frequency Domain Laser Ultrasound System

Our FreDomLUS system is an optical laser ultrasound system based on an intensity-modulated CW laser for excitation of a sample and a laser vibrometer for detection of the excited sample. This allows a non-contact and non-destructive determination of material-specific parameters and elastic phenomena in different materials and thin films. Due to its low optical peak power, the fiber-based measurement system is particularly suitable for non-destructive testing of very sensitive samples (e.g., very thin or small samples). Narrowband measurements such as the determination of acoustic resonances can thus be performed with high accuracy.

Operating principle:

Standard laser ultrasound system RECENDT FreDomLUS system
time-domain laser ultrasound frequency-domain laser ultrasound
pulsed excitation harmonic excitation (intensity-modulated)
evaluation of echo running time evaluation of resonance frequencies
high peak power (up to 1 MW) low peak power (< 25 W)
frequency range: 0.1 - 100 MHz frequency range: 0.1 - 8000 MHz
Classification of FreDomLUS

Technical Features

Fiber-based optical laser ultrasound system consisting of:

Non-contact sample excitation
Excitation laser intensity-modulated CW laser
Central wavelength* option 1: 1550 nm
option 2: 1064 nm
Modulation frequency range* 100 kHz - 8 GHz
Focus dot size 1 - 3 µm (FWHM)
Maximum optical power 25 W
Interlock  
Non-contact sample detection
Detection laser* CW laser
Wavelength* 532 nm
Interferometer* option 1: Michelson, stabilized
option 2: Sagnac
* standard version, changes and further developments available on request

 

Frequency Domain Laser Ultrasound System

Application: Acoustic Spectral Imaging

Compared to current standard methods such as acoustic microscopy (C-SAM), the FreDomLUS system can also be used to measure material-specific parameters and elastic phenomena in different materials and thin films up to high frequency ranges (< 8 GHz) in a non-contact and non-destructive manner. The local acoustic spectroscopy used here provides spatially resolved imaging of a wide range of parameters that influence wave propagation in the material, such as dimensional, elastic, or piezoelectric properties.

Spatially resolved characterization of elastic properties (A)

By directly measuring plate resonances, the FreDomLUS system can determine both the Poisson's ratio (together with the Young's and shear moduli) and the acoustic damping (longitudinal and transverse damping coefficients) of plate geometries.

Spatially resolved characterization in single- and multilayer systems (B)

By scanning the sample, FreDomLUS enables spatially resolved determination of various parameters of single- and multi-layer systems, such as variations in layer thickness in the nanometer range. This also allows the detection and localization of defects and delaminations in different layers.

Other possible applications:

  • Detection of delamination in wafers, etc.
  • Characterization of filter materials for e.g. RF filters (such as BAW or FBAR filters)
  • Characterization of thin films and layer structures (µm to nm)
  • Characterization of microelectromechanical systems (MEMS)
  • Investigation of piezoelectric materials
Publications

Media publications:

  1. Regitnig-Tillian, N. Mit Klangschale zur Kernfusion. Der Standard. May 8, 2024.
    https://www.derstandard.de/story/3000000217553/mit-klangschalen-der-kernfusion-auf-der-spur

  2. Regitnig-Tillian, N. Schwingende Diamant-Klangschalen. Austria Innovativ. 4/2024 ed. August 16, 2024.
    https://www.austriainnovativ.at/singleview/article/fusionsforschung-schwingende-diamant-klangschalen

Scientific publications:

  1. Ryzy, M.; Veres, I.; Berer, T.; Salfinger, M.; Kreuzer, S.; Yan, G.; Scherleitner, E.; Grünsteidl, C. Determining Longitudinal and Transverse Elastic Wave Attenuation from Zero-Group-Velocity Lamb Waves in a Pair of Plates. The Journal of the Acoustical Society of America 2023, 153 (4), 2090–2100.
    https://doi.org/10.1121/10.0017652.

  2. Grünsteidl, C.; Veres, I.; Berer, T.; Kreuzer, S.; Rothemund, R.; Hettich, M.; Scherleitner, E.; Ryzy, M. Measurement of the Attenuation of Elastic Waves at GHz Frequencies Using Resonant Thickness Modes. Appl. Phys. Lett. 2020, 117 (16), 164102.
    https://doi.org/10.1063/5.0026367.

  3. Grünsteidl, C.; Ryzy, M.; Hettich, M.; Berer, T.; Veres, I. Evaluation of Elastic Wave Attenuation in the GHz Range  Using Zero-Group-Velocity Resonances. In Proceedings of  the e-Forum Acusticum; Lyon, 2020; pp 2557–2560.
    https://doi.org/10.48465/fa.2020.0582.

  4. Grünsteidl, C.; Berer, T.; Hettich, M.; Veres, I. Using Zero-Group-Velocity Lamb Waves to Determine Thickness and Bulk Sound Velocities of Isotropic Plates. In AIP Conference Proceedings; 2102; Vermont, USA, 2019; Vol. 38, pp 050016-1-050016–5.
    https://doi.org/10.1063/1.5099782.

  5. Berer, T.; Grunsteidl, C.; Rothemund, R.; Kreuzer, S.; Ryzy, M.; Hettich, M.; Veres, I. A. Determination of Longitudinal and Transversal Attenuation Coefficients in the Frequency Domain Using Zero Group Velocity Lamb Waves. In 2019 IEEE International Ultrasonics Symposium (IUS); IEEE: Glasgow, United Kingdom, 2019; pp 1974–1976.
    https://doi.org/10.1109/ULTSYM.2019.8925923.

  6. Ryzy, M.; Grabec, T.; Österreicher, J. A.; Hettich, M.; Veres, I. A. Measurement of Coherent Surface Acoustic Wave Attenuation in Polycrystalline Aluminum. AIP Advances 2018, 8 (12), 125019.
    https://doi.org/10.1063/1.5074180.

  7. Grünsteidl, C.; Berer, T.; Hettich, M.; Veres, I. Determination of Thickness and Bulk Sound Velocities of Isotropic Plates Using Zero-Group-Velocity Lamb Waves. Appl. Phys. Lett. 2018, 112 (25), 251905.
    https://doi.org/10.1063/1.5034313.

  8. Veres, I. A.; Grünsteidl, C.; Stobbe, D. M.; Murray, T. W. Broad-Angle Negative Reflection and Focusing of Elastic Waves from a Plate Edge. Phys. Rev. B 2016, 93 (17), 174304.
    https://doi.org/10.1103/PhysRevB.93.174304.

  9. Grünsteidl, C.; Veres, I. A.; Roither, J.; Burgholzer, P.; Murray, T. W.; Berer, T. Spatial and Temporal Frequency Domain Laser-Ultrasound Applied in the Direct Measurement of Dispersion Relations of Surface Acoustic Waves. Appl. Phys. Lett 2013, 102 (1), 011103-1-011103–011104.
    https://doi.org/10.1063/1.4773234.

 

Application: Acoustic Spectral Imaging

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Holzer Robert, Dipl.-Ing. -

Holzer Robert, Dipl.-Ing.
Project Management & Business Development

Zerobin Stefan, Dipl.-Ing. Dr. -

Zerobin Stefan, Dipl.-Ing. Dr.
Business Development Manager (actual paternity leave)

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The Research Center for Non-Destructive Testing GmbH is member of the UAR Innovation Network and is supported by funding from the Province of Upper Austria and the European Union.