Acoustic interferometer

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

An impedance analysis of double-stream interaction in semiconductors

Abstract: The electromagnetic waves propagating through a drifting semiconductor plasma are studied from a macroscopic point of view in terms of double-stream interaction. The possible existing waves (helicon waves, longitudinal waves, ordinary waves, and pseudolongitudinal waves) which depend upon the orientation of the dc external magnetic field are derived. A powerful impedance concept is introduced to investigate the wave behavior of longitudinal (space charge) waves or pseudolongitudinal waves in a semiconductor plasma. The impedances due to one- and two-carrier stream interactions were calculated theoretically.

Using a High-Quality Thermostated Acoustic Interferometer to Study Changes in the Structure of Human Serum Proteins

Abstract: An acoustic interferometric technique for determining the protein in blood serum is presented. This acoustic approach is based on high-precision measurements of the temperature dependences of the velocity, frequency, and absorption of ultrasound. The acoustic characteristics of blood serum are measured by a constant-length interferometer in acoustic wells with volumes of around 80 μL in the temperature range of 28–40°C and the frequency range of 1.4–14 MHz.

Acoustic scattering of metallic springs in elastic medium

Abstract: In applications such as ultrasonic immersion testing, damping of flow noise in pipes and ducts and coating of acoustic control surfaces, it is very useful to reduce the reflection of acoustic waves from surfaces. Significant echo reduction can be achieved by addition of an anechoic coating. According to some general design guidelines for a single layer of homogenous coating, a single layer of 15 dB coating must be at least one wavelength thick. For absorbing acoustic waves of low frequencies, inhomogeneities such as metallic fillers, cavities and irregular metallic helices can be introduced into the lossy matrix to substantially enhance the acoustic absorption by acoustic scattering. In this presentation, the acoustic scattering of a single metallic spring embedded in an infinite elastic medium has been investigated using a boundary element formulation. The cross sections of the scattered longitudinal and shear waves have been calculated for various spring sizes, orientations and wave numbers. It will be ...

Fiber laser sensing system for double-frequency sound wave detection

Abstract: The invention relates to a fiber laser sensing system for double-frequency sound wave detection. The system comprises a fiber DBR grating, a rotary part, a 980/1550 wavelength division multiplexer, a pump laser, an optical isolator, a polarization controller, a polarizer and a photoelectric detector, wherein 980nm laser pumped by the pump laser is emitted and then input to the fiber DBR grating via the 980/1550 wavelength division multiplexer, the rotary part keeps the fiber DBR grating rotating, external double-frequency sound waves from different directions act on the fiber DBR grating which keeps rotating, the rotating grating is sensitive to one frequency of sound waves at one angle and is sensitive to the other frequency of sound waves at the other angle, information of the double-frequency sound waves is modulated into transmitted light waves, the light wavelength is converted to 1550nm, and the light waves are reflected back to the 980/1550 wavelength division multiplexer; and the light waves are input to the polarization controller via the optical isolator that prevents photo echo, and then two polarization states are converted into electrical signals in the same direction via the polarizer. The system can simultaneously detect the sound waves of two different frequencies.