Abstract

A simple and inexpensive method of directional discrimination of velocity based on the analysis of the Doppler signal's waveform obtained through a self-mixing type laser Doppler velocimeter (LDV) is described. The technique does not need the components commonly used to give the frequency offset required to yield directional information in LDV. The device is described, and experimental evidence is presented.

© 1987 Optical Society of America

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References

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  1. D. A. Jackson, D. M. Paul, “Measurement of Supersonic Velocity and Turbulence by Laser Anemometry,” J. Phys. E 4, 173 (1971).
    [CrossRef]
  2. W. H. Stevenson, “Optical Frequency Shifting by Means of a Rotating Diffraction Grating,” Appl. Opt. 9, 649 (1970).
    [CrossRef] [PubMed]
  3. R. Dandliker, P. D. Iten, “Direction Sensitive Laser Doppler Velocimeter with Polarized Beams,” Appl. Opt. 13, 286 (1974).
    [CrossRef] [PubMed]
  4. Y. C. Agrawal, J. R. McCullough, “Directional Pedestal-free Laser Doppler Velocimetry Without Frequency Biasing,” Appl. Opt. 20, 1553 (1981).
    [CrossRef] [PubMed]
  5. S. Shinohara, A. Mochizuki, H. Yoshida, M. Sumi, “Laser Doppler Velocimeter Using the Self-mixing Effect of a Semiconductor Laser Diode,” Appl. Opt. 25, 1417 (1986).
    [CrossRef] [PubMed]

1986

1981

1974

1971

D. A. Jackson, D. M. Paul, “Measurement of Supersonic Velocity and Turbulence by Laser Anemometry,” J. Phys. E 4, 173 (1971).
[CrossRef]

1970

Agrawal, Y. C.

Dandliker, R.

Iten, P. D.

Jackson, D. A.

D. A. Jackson, D. M. Paul, “Measurement of Supersonic Velocity and Turbulence by Laser Anemometry,” J. Phys. E 4, 173 (1971).
[CrossRef]

McCullough, J. R.

Mochizuki, A.

Paul, D. M.

D. A. Jackson, D. M. Paul, “Measurement of Supersonic Velocity and Turbulence by Laser Anemometry,” J. Phys. E 4, 173 (1971).
[CrossRef]

Shinohara, S.

Stevenson, W. H.

Sumi, M.

Yoshida, H.

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Figures (8)

Fig. 1
Fig. 1

Schematic configuration of LDV based on the Michelson interferometer.

Fig. 2
Fig. 2

Example of Doppler beat signal obtained with a Michelson interferometer type LDV: (a) frequency spectrum; instrumental bandwidth, 1 kHz; (b) beat signal waveform.

Fig. 3
Fig. 3

Schematic configuration of a self-mixing type LDV.

Fig. 4
Fig. 4

Example of a beat signal obtained with a self-mixing type LDV: (a) frequency spectrum; instrumental bandwidth, 1 kHz; (b) beat signal waveform.

Fig. 5
Fig. 5

Characteristic of waveforms obtained with a self-mixing type LDV: (a) positive Doppler shift; (b) negative Doppler shift.

Fig. 6
Fig. 6

Doppler beat signal analysis. Below: experimental results. The fundamental beat signal and the second harmonic are shown separately; the inversion of the phase of the second harmonic can be seen for the opposite sign of fD. Above: theoretical waveform: the fundamental beat signal and the second harmonic are indicated by broken lines. The composite waveform is drawn with bold lines.

Fig. 7
Fig. 7

Doppler signal level as a function of the separating distance l between the laser and target for different bias current values.

Fig. 8
Fig. 8

Frequency characteristics of the Doppler signal level. Solid and broken lines correspond to incidence angles of 88 and 83°, respectively.

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