Fluid velocity measurements in a microchannel performed with two new optical heterodyne microscopes

Yu-Lung Lo, Chi Hsin Chuang

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Two laser Doppler microscopes (LDMs) based on an optical heterodyne interferometer have been developed for measuring fluid velocity in a microchannel. One of LDMs receives light from a Zeeman laser, and one easily obtains the standard heterodyne signal because a polarizer is set in front of a photomultiplier tube. The other LDM, with light from a He-Ne laser, employs a diffractive grating as a frequency shifter that is modulated in a sinusoidal movement by a piezoelectric transducer stack. By this modulation the nonstandard heterodyne signal is further processed by a new synthetic heterodyne algorithm. Finally, the phase shift related to the fluid velocity in both LDMs is demodulated by digital postprocessing in fast-Fourier-transform, bandpass filtering, inverse-fast-Fourier-transform, and arctangent algorithms.

Original languageEnglish
Pages (from-to)6666-6675
Number of pages10
JournalApplied Optics
Volume41
Issue number31
DOIs
Publication statusPublished - 2002 Nov 1

All Science Journal Classification (ASJC) codes

  • Atomic and Molecular Physics, and Optics
  • Electrical and Electronic Engineering

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