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Medical and Biological Engineering and Computing

, Volume 29, Issue 5, pp 470–474 | Cite as

Frequency stabilisation of multimode helium-neon lasers in laser Doppler flowmetry

  • H. Deblén
  • P. Å. Öberg
Instrumentation

Abstract

Low-frequency noise in laser Doppler recordings can be generated because of thermal instabilities in the gas laser cavity. Mode partition noise can be eliminated by thermal stabilisation of the laser cavity. The paper describes a method for closed loop temperature control of the laser cavity. The method uses orthogonal properties of longitudinal laser modes for the temperature control. The signal-to-noise ratio is considerably improved by the procedure. It is recommended that all gas laser equipped Doppler instruments used for precision blood flow studies shold be equipped with stabilised laser sources.

Keywords

Laser Doppler Noise stabilisation Temperature control Vasomotion 

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Copyright information

© IFMBE 1991

Authors and Affiliations

  • H. Deblén
    • 1
  • P. Å. Öberg
    • 1
  1. 1.Department of Biomedical EngineeringLinköping UniversityLinköpingSweden

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