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Experiments with narrow movable beams of pulsed sound waves at 35 GHz
Author(s) -
Knöll Th.,
Weis O.
Publication year - 1995
Publication title -
annalen der physik
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.009
H-Index - 68
eISSN - 1521-3889
pISSN - 0003-3804
DOI - 10.1002/andp.19955070403
Subject(s) - optics , beam (structure) , scattering , acoustics , resonator , physics , acoustic wave , gaussian beam , wavelength , materials science
Abstract Only the study of absorption and angular dependent scattering of GHz and THz sound can give us detailed information about interaction processes of acoustical phonons. Therefore, the necessary techniques of sound generation, detection and undisturbed transmission to the target must be improved or to a large extent must still be developed. Corresponding attempts at 35 GHz are described. Sound‐beam topography allowed to study crystal defects and also showed us where transmission without scattering occurred. For the piezoelectric generation a reflex klystron was used feeding a planar Hertzian resonator. The needle‐like sound beams appeared as a double beam, each showing a minimum diameter of 35 μm for longitudinal polarized sound at an acoustic wavelength of 165 nm in X‐cut quartz and 320 nm in a‐cut sapphire. To obtain the smallest possible beam diameter for high resolution work, model calculations are presented for an excited fundamental Gaussian sound beam in an isotropic medium.