28 January 2009 Laser generation of acoustic waves in liquids using a Helmholtz resonance photoacoustic cell
Author Affiliations +
Abstract
The thermoelastic mechanism for laser generation of acoustic waves in liquids is presented first of all. The amplitude of the acoustic waves excited by this mechanism is so small that most of time it can not satisfy application requirements. In our research, a Helmholtz resonance photoacoustic cell is employed to resolve the problem. It consists of a sample cell and a Helmholtz resonator. When the modulating frequency of a laser beam is equal to the acoustical resonance frequency of a Helmholtz resonator, the photoacoustic cell corresponds to an acoustic amplifier in the photoacoustic system. And then the amplifying performance of a Helmholtz resonance photoacoustic cell under liquids is investigated. The theoretical analysis indicates that both the resonance frequency and the magnitude of enlargement are dependent on the parameters of the Helmholtz resonator and the medium characteristics in and around the cell. After that, for a given laser source, a photoacoustic cell is designed to amplify the acoustic waves excited by the laser beam. The resonance frequency, the peak magnitude of enlargement, and the transfer function are analyzed theoretically. At last, an experimental system is set up. The photoacoustic signal is simulated by a single-frequency acoustic signal. The acoustic waves both inside and outside the photoacoustic cell are picked up using broadband piezoelectric hydrophones synchronously. The transfer function curve of the resonance photoacoustic cell is obtained experimentally. The results derived from theoretic analysis and those obtained from experiments agree with each other well.
© (2009) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Qiushi Li, Hong Luo, Zefeng Wang, Yongming Hu, "Laser generation of acoustic waves in liquids using a Helmholtz resonance photoacoustic cell", Proc. SPIE 7156, 2008 International Conference on Optical Instruments and Technology: Optical Systems and Optoelectronic Instruments, 71562J (28 January 2009); doi: 10.1117/12.807069; https://doi.org/10.1117/12.807069
PROCEEDINGS
9 PAGES


SHARE
Back to Top