An Interferometric Technique for the Measurement of Acoustic Velocity

POSTER

Abstract

We have developed a system for accurate measurement of acoustic velocity using an optical phase shifting technique employing acousto-optic modulators (AOMs)\footnote{E. Li et al., Opt. Lett. {\bf 30}, 189 (2005)}. We use a pair of AOMs driven at the same rf frequency but different phase $\Delta \phi$. They are aligned to cancel the optical frequency shifts they impose on a laser beam, but they still shift the optical phase by $\Delta \phi$. By maintaining $\Delta \phi$ constant and translating one modulator in the direction of acoustic propagation, a 2$\pi$ optical phase shift is produced for each acoustic wavelength $\lambda_a$ of translation. The acoustic velocity is the product of this measured $\lambda_a$ and the known rf frequency. We measure the optical phase shifts by inserting the pair of AOMs into one arm of a Mach-Zehnder interferometer, with one AOM mounted on a micrometer stage, and then detect the fringe shifts. We present results for longitudinal mode velocities in lead molybdate and tellurium dioxide. We will also discuss the importance of refractive index gradients that can produce anomalous results.

Authors

  • Student Workshop

    Physics, Stony Brook University, NY 11794-3800 USA, Physics Department, Western Michigan University, Kalamazoo, MI, 49008, USA, Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA, University of Pittsburgh, Pittsburgh, PA 15260, USA, R. Bo\v{s}kovi\'{c} Institute, Zagreb, Croatia, Bose Institute, Kolkata, India, U. Wisconsin, Argonne National Laboratory, U. Kentucky, Kansas State University, Rice University, Oak Ridge National Laboratory, University of Tennessee, Vienna University of Technology, University of Tennessee, Vienna University of Technology, University of North Alabama, Florence, AL, University of Connecticut, LANL, Auburn University, Voronezh State University, Russia, Oak Ridge National Laboratory, Rollins College, ATOMKI, Debrecen, GANIL, Caen, Stony Brook University, NY 11794-3800 USA, Hefei National Lab \& Dept of Chemical physics, Univ of Sci \& Tech of China, Dept of Earth \& Environ Sci, Univ of Illinois at Chicago, EFI \& Dept of Geophys. Sci., UofC, Chem Div, ANL, Phys Div, ANL, Phys Div, Argonne National Lab (ANL) \& Enrico Fermi Institute (EFI), Univ of Chicago (UofC), Department of Physics, University of Turku, 20014 Turku, Finland, Clarendon Laboratory, Oxford, SNL, Univ. Paris Sud, Orsay

  • Student Workshop

    Physics, Stony Brook University, NY 11794-3800 USA, Physics Department, Western Michigan University, Kalamazoo, MI, 49008, USA, Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA, University of Pittsburgh, Pittsburgh, PA 15260, USA, R. Bo\v{s}kovi\'{c} Institute, Zagreb, Croatia, Bose Institute, Kolkata, India, U. Wisconsin, Argonne National Laboratory, U. Kentucky, Kansas State University, Rice University, Oak Ridge National Laboratory, University of Tennessee, Vienna University of Technology, University of Tennessee, Vienna University of Technology, University of North Alabama, Florence, AL, University of Connecticut, LANL, Auburn University, Voronezh State University, Russia, Oak Ridge National Laboratory, Rollins College, ATOMKI, Debrecen, GANIL, Caen, Stony Brook University, NY 11794-3800 USA, Hefei National Lab \& Dept of Chemical physics, Univ of Sci \& Tech of China, Dept of Earth \& Environ Sci, Univ of Illinois at Chicago, EFI \& Dept of Geophys. Sci., UofC, Chem Div, ANL, Phys Div, ANL, Phys Div, Argonne National Lab (ANL) \& Enrico Fermi Institute (EFI), Univ of Chicago (UofC), Department of Physics, University of Turku, 20014 Turku, Finland, Clarendon Laboratory, Oxford, SNL, Univ. Paris Sud, Orsay

  • Student Workshop

    Physics, Stony Brook University, NY 11794-3800 USA, Physics Department, Western Michigan University, Kalamazoo, MI, 49008, USA, Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA, University of Pittsburgh, Pittsburgh, PA 15260, USA, R. Bo\v{s}kovi\'{c} Institute, Zagreb, Croatia, Bose Institute, Kolkata, India, U. Wisconsin, Argonne National Laboratory, U. Kentucky, Kansas State University, Rice University, Oak Ridge National Laboratory, University of Tennessee, Vienna University of Technology, University of Tennessee, Vienna University of Technology, University of North Alabama, Florence, AL, University of Connecticut, LANL, Auburn University, Voronezh State University, Russia, Oak Ridge National Laboratory, Rollins College, ATOMKI, Debrecen, GANIL, Caen, Stony Brook University, NY 11794-3800 USA, Hefei National Lab \& Dept of Chemical physics, Univ of Sci \& Tech of China, Dept of Earth \& Environ Sci, Univ of Illinois at Chicago, EFI \& Dept of Geophys. Sci., UofC, Chem Div, ANL, Phys Div, ANL, Phys Div, Argonne National Lab (ANL) \& Enrico Fermi Institute (EFI), Univ of Chicago (UofC), Department of Physics, University of Turku, 20014 Turku, Finland, Clarendon Laboratory, Oxford, SNL, Univ. Paris Sud, Orsay

  • Student Workshop

    Physics, Stony Brook University, NY 11794-3800 USA, Physics Department, Western Michigan University, Kalamazoo, MI, 49008, USA, Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA, University of Pittsburgh, Pittsburgh, PA 15260, USA, R. Bo\v{s}kovi\'{c} Institute, Zagreb, Croatia, Bose Institute, Kolkata, India, U. Wisconsin, Argonne National Laboratory, U. Kentucky, Kansas State University, Rice University, Oak Ridge National Laboratory, University of Tennessee, Vienna University of Technology, University of Tennessee, Vienna University of Technology, University of North Alabama, Florence, AL, University of Connecticut, LANL, Auburn University, Voronezh State University, Russia, Oak Ridge National Laboratory, Rollins College, ATOMKI, Debrecen, GANIL, Caen, Stony Brook University, NY 11794-3800 USA, Hefei National Lab \& Dept of Chemical physics, Univ of Sci \& Tech of China, Dept of Earth \& Environ Sci, Univ of Illinois at Chicago, EFI \& Dept of Geophys. Sci., UofC, Chem Div, ANL, Phys Div, ANL, Phys Div, Argonne National Lab (ANL) \& Enrico Fermi Institute (EFI), Univ of Chicago (UofC), Department of Physics, University of Turku, 20014 Turku, Finland, Clarendon Laboratory, Oxford, SNL, Univ. Paris Sud, Orsay