Acoustic interferometer

About: Acoustic interferometer is a research topic. Over the lifetime, 1493 publications have been published within this topic receiving 19355 citations.

High Resolution Photoacoustic Microscopy on a Surface Acoustic Wave Device

Abstract: Photoacoustic imaging of microscopic metal film test structures on a surface acoustic wave device at 76‐MHz light modulation frequency is reported. The samples are evaporated on a YZ LiNbO3 crystal surface and are scanned through the focus spot of a mode‐locked dye laser beam. The optically generated surface acoustic waves are detected by means of a resonant interdigital transducer. Synchronization of the focus spot position to the corresponding piezoelectric signal yields a high resolution photoacoustic image of the samples (lateral resolution 5 μm).

SAW waveguiding in high aspect ratio transducers

Abstract: Efficient acoustic waveguides with a confinement in 3-dimensional space were obtained using high aspect ratio interdigital transducers (HAR IDTs). Energy trapping at the substrate surface is ensured by mass loading effect, while lateral confinement is preserved while reducing the acoustic aperture of the HAR IDTs down to one acoustic wavelength. A detailed analysis of such HAR IDTs fabricated on X-cut lithium niobate, with Y-propagating waves is presented. Reflection scattering parameter measurements were performed and are here reported. They show the existence of several modes with a resonance frequency much lower than the one expected for a Rayleigh wave. The wave velocity is indeed reduced from 3639 m/s down to 781 m/s. Using heterodyne laser scanning interferometry, measurements of out-of-plane displacement induced by the generated surface waves were performed. The measurement results show that the elastic energy is strongly localized within the acoustic aperture of the transducer.

Large-aperture high-accuracy lateral shearing interferometer utilizing a Twyman-Green interferometer

Abstract: This paper puts forward a new large-aperture high-accuracy interferometer for flow visualization and optical shop testing. The interferometer uses a Twyman-Green interferometer as a beam splitter, and a grating as a detector. Using this interferometer to measure the flow fields in a shock tunnel and to test optical elements obtained some satisfactory results.

Diagnosis of Laser-Induced Shock Waves in Brass Foil Using a Fiber-Optic Interferometer

Abstract: A fiber-optic interferometer is developed to investigate shock waves in brass foil impacted by a Neodymium:Yttrium–Aluminium–Garnet (Nd:YAG) laser at a wavelength of 1064 nm and pulse width (FWHM) of 7 ns. Because of introduction of an optical transceiver module, the interferometer is compact and reliable. Appreciable signals due to shock waves have been detected using this interferometer. The shock-wave velocity is deduced from the measured arrival times of shock waves in brass foils with different thicknesses (0.200 and 0.300 mm), and is found to be 8.33 km/s.

Suppression of Beam-Excited Electron Waves by an Externally Applied RF Signal

Abstract: Suppression of the beam-excited electron wave in a bounded system is investigated in connection with the beam distribution function. Wave suppression has two different processes depending on whether injected beams are reflected at the other end or not. In the absence of reflected beam electrons, deformation of the beam distribution function is observed in relation to the suppression of the electron wave. However, when beam electrons are reflected, the external wave suppresses the electron wave but distribution function shows no appreciable change. By using the method of partial simulation, interaction between two waves in the bounded system including nonlinear motions of beam electrons is studied numerically. Qualitative agreement between experimental and numerical results is obtained.