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The European Physical Journal Special Topics

, Volume 153, Issue 1, pp 439–441 | Cite as

Photoacoustic signal generation based on self-oscillation method

  • T. Borowski
  • T. Starecki
Article

Abstract.

In conventional photoacoustic experiments a signal generated by photoacoustic phenomenon is produced by a forced stimulation of the investigated sample by electromagnetic radiation energy (light) which intensity is modulated at a user selected frequency. Resultant photoacoustic signal has the same frequency as the light modulation frequency. The paper presents a new technique of photoacoustic signal generation, based on self-oscillations resulting from a loopback in the signal path consisting of a modulated light source, a photoacoustic chamber, a microphone, and an amplifier. Signal from the amplifier output was used to drive the light source. Gain of the amplifier was chosen in order to obtain total loop gain of the signal path greater than one and positive feedback operation. On contrary to conventional photoacoustic methods, frequency of the photoacoustic signal in the presented self-oscillation method is determined mainly by acoustic properties of the photoacoustic cell, which in the experiments was corresponding to the resonance frequency of the cell. Taking into consideration that resonance frequency of a photoacoustic cell depends on the speed of sound, which is affected by properties of the fluid filling the cell, the method based on self-oscillations can be applied e.g. to quantitative analysis of the investigated substance.

Keywords

European Physical Journal Special Topic Acoustic Resonance Photoacoustic Signal Photoacoustic Cell Electret Microphone 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© EDP Sciences/Società Italiana di Fisica/Springer-Verlag 2008

Authors and Affiliations

  1. 1.Independent researcher, Baborowska 5/18WarsawPoland
  2. 2.Institute of Electronic Systems, Warsaw University of TechnologyWarsawPoland

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