Abstract

A laser Doppler anemometer (LDA) has been developed that combines the compactness and low power consumption of laser diodes and avalanche photodiodes with the flexibility and possibility of miniaturization by using fiber-optic probes. The system has been named DFLDA for laser diode fiber LDA and is especially suited for mobile applications, for example, in trains, airplanes, or automobiles. Optimization considerations of fiber-optic probes are put forward and several probe examples are described in detail. Measurement results from three typical applications are given to illustrate the use of the DFLDA. Finally, a number of future configurations of the DFLDA concept are discussed.

© 1992 Optical Society of America

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References

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  1. D. Dopheide, M. Faber, G. Reim, G. Taux, “A portable frequency stabilized laser diode backscatter semiconductor LDA for high velocity applications,” in Proceedings of the Fourth International Symposium on Application of Laser Anemometry to Fluid Mechanics (LADOAN, Institute Superior Tecnico, Lisbon, 1989).
  2. R. Müller, A. Naqwi, “Optimization of a laser diode anemometry system,” Rep. LSTM 239/T/88 (Lehrstuhl für Strömungsmechanik, Universität Erlangen-Nürnberg, Erlangen D-8520, Germany, 1988).
  3. R. G. W. Brown, J. G. Burnett, N. Hackney, “A miniature, battery operated laser Doppler anemometer,” in Proceedings of the Fourth International Symposium on Application of Laser Anemometry to Fluid Mechanics (LADOAN, Institute Superior Tecnico, Lisbon, 1988).
  4. F. F. M. de Mul, H. W. Jentink, M. Koelink, J. Greve, J. G. Aarnoudse, “Velocimetry with diode lasers,” in Proceedings of the Third International Conference on Laser Anemometry: Advances and Applications (UK and Dutch LDA Users Group, Swansea, Wales, UK, September1989).
  5. Laser Diode LDA Product Information (Polytec GmbH, Waldbronn, Germany, 1991).
  6. P. W. Forder, C. N. Pannell, J. D. C. Jones, D. A. Jackson, “Designs of fibre optic probes for laser anemometry,” in Proceedings of the Second International Symposium on Laser Anemometry: Advances and Applications (UK and Dutch LDA Users Group, Strathclyde, UK, 1987).
  7. J. D. C. Jones, R. K. Y. Chan, D. A. Jackson, “Design of fibre optic systems for Doppler difference laser velocimetry,” in Proceedings of the Second International Symposium on Applications of Laser Anemometry to Fluid Mechanics (LADOAN, Institute Superior Tecnico, Lisbon, 1984).
  8. D. A. Jackson, J. D. C. Jones, “Extrinsic fibre-optic sensors for remote measurement: Part I and Part II,” Opt. Laser Technol. 18, 243–249 (1986).
    [CrossRef]
  9. Diode Laser Guide Product Catalog (Melles-Griot, Irvine, Calif., 1990).
  10. L. Goldberg, H. F. Taylor, A. Dandrige, J. F. Weller, R. O. Miles, “Spectral characteristics of semiconductor lasers with optical feedback,” IEEE Trans. Microwave Theory Tech. MTT-30, 401–420 (1982).
    [CrossRef]
  11. Laser Doppler Velocimetry Components Product Catalog (TSI, Inc., St. Paul, Minn., 1991).
  12. A. Naqwi, F. Durst, “Computation of light scattering from a dual-beam system,” Rep. LSTM 259/T/89 (Lehrstuhl für Strömungsmechanik, Universität Erlangen-Nürnberg, Erlangen D-8520, Germany, 1989).
  13. C. Tropea, G. Dimaczek, J. Kristensen, “Evaluation of the Dantec burst spectrum analyzer,” Rep. LSTM 218/I/88 (Lehrstuhl für Strömungsmechanik, Universität Erlangen-Nürnberg, Erlangen D-8520, Germany, 1988).
  14. Y. Ikeda, T. Nakajiwa, S. Hosokawa, R. Matsumoto, “A compact fiber LDV with a perforated beam expander,” Meas. Sci. Technol. 1, 260–264 (1990).
    [CrossRef]
  15. S. Bopp, F. Durst, C. Tropea, “In-cylinder velocity measurements with a mobile fiber optic LDA system,” in Proceedings of the 1990 SAE Congress and Exposition (Society of Automotive Engineers, Warrendale, Pa., 1990), paper 900055.
  16. M. Lorenz, K. Prescher, “Cycle resolved LDV measurements of a fired SI-engine at high data rates using a conventional modular LDV-system,” in Proceedings of the 1990 SAE Congress and Exposition (Society of Automotive Engineers, Warrendale, Pa., 1990), paper 900054.
  17. C. Tropea, D. Struthers, “Microprocessor based on-line measurement system for LDA,” in Proceedings of an International Specialists Meeting on the Use of Computers in Laser Anemometry, H. J. Pfeifer, B. Jeaggy, eds. (Institut Saint Louis, Saint Louis, France, 1987).
  18. J. Domnick, C. Tropea, R. Wagner, “A miniaturized semiconductor fiber optic phase-Doppler anemometer (DF-PDA) with applications to liquid sprays,” in Proceedings of the International Conference on Multiphase Flows (University of Tsukuba, Tsukuba, Japan, September1991).

1990 (1)

Y. Ikeda, T. Nakajiwa, S. Hosokawa, R. Matsumoto, “A compact fiber LDV with a perforated beam expander,” Meas. Sci. Technol. 1, 260–264 (1990).
[CrossRef]

1986 (1)

D. A. Jackson, J. D. C. Jones, “Extrinsic fibre-optic sensors for remote measurement: Part I and Part II,” Opt. Laser Technol. 18, 243–249 (1986).
[CrossRef]

1982 (1)

L. Goldberg, H. F. Taylor, A. Dandrige, J. F. Weller, R. O. Miles, “Spectral characteristics of semiconductor lasers with optical feedback,” IEEE Trans. Microwave Theory Tech. MTT-30, 401–420 (1982).
[CrossRef]

Aarnoudse, J. G.

F. F. M. de Mul, H. W. Jentink, M. Koelink, J. Greve, J. G. Aarnoudse, “Velocimetry with diode lasers,” in Proceedings of the Third International Conference on Laser Anemometry: Advances and Applications (UK and Dutch LDA Users Group, Swansea, Wales, UK, September1989).

Bopp, S.

S. Bopp, F. Durst, C. Tropea, “In-cylinder velocity measurements with a mobile fiber optic LDA system,” in Proceedings of the 1990 SAE Congress and Exposition (Society of Automotive Engineers, Warrendale, Pa., 1990), paper 900055.

Brown, R. G. W.

R. G. W. Brown, J. G. Burnett, N. Hackney, “A miniature, battery operated laser Doppler anemometer,” in Proceedings of the Fourth International Symposium on Application of Laser Anemometry to Fluid Mechanics (LADOAN, Institute Superior Tecnico, Lisbon, 1988).

Burnett, J. G.

R. G. W. Brown, J. G. Burnett, N. Hackney, “A miniature, battery operated laser Doppler anemometer,” in Proceedings of the Fourth International Symposium on Application of Laser Anemometry to Fluid Mechanics (LADOAN, Institute Superior Tecnico, Lisbon, 1988).

Chan, R. K. Y.

J. D. C. Jones, R. K. Y. Chan, D. A. Jackson, “Design of fibre optic systems for Doppler difference laser velocimetry,” in Proceedings of the Second International Symposium on Applications of Laser Anemometry to Fluid Mechanics (LADOAN, Institute Superior Tecnico, Lisbon, 1984).

Dandrige, A.

L. Goldberg, H. F. Taylor, A. Dandrige, J. F. Weller, R. O. Miles, “Spectral characteristics of semiconductor lasers with optical feedback,” IEEE Trans. Microwave Theory Tech. MTT-30, 401–420 (1982).
[CrossRef]

de Mul, F. F. M.

F. F. M. de Mul, H. W. Jentink, M. Koelink, J. Greve, J. G. Aarnoudse, “Velocimetry with diode lasers,” in Proceedings of the Third International Conference on Laser Anemometry: Advances and Applications (UK and Dutch LDA Users Group, Swansea, Wales, UK, September1989).

Dimaczek, G.

C. Tropea, G. Dimaczek, J. Kristensen, “Evaluation of the Dantec burst spectrum analyzer,” Rep. LSTM 218/I/88 (Lehrstuhl für Strömungsmechanik, Universität Erlangen-Nürnberg, Erlangen D-8520, Germany, 1988).

Domnick, J.

J. Domnick, C. Tropea, R. Wagner, “A miniaturized semiconductor fiber optic phase-Doppler anemometer (DF-PDA) with applications to liquid sprays,” in Proceedings of the International Conference on Multiphase Flows (University of Tsukuba, Tsukuba, Japan, September1991).

Dopheide, D.

D. Dopheide, M. Faber, G. Reim, G. Taux, “A portable frequency stabilized laser diode backscatter semiconductor LDA for high velocity applications,” in Proceedings of the Fourth International Symposium on Application of Laser Anemometry to Fluid Mechanics (LADOAN, Institute Superior Tecnico, Lisbon, 1989).

Durst, F.

A. Naqwi, F. Durst, “Computation of light scattering from a dual-beam system,” Rep. LSTM 259/T/89 (Lehrstuhl für Strömungsmechanik, Universität Erlangen-Nürnberg, Erlangen D-8520, Germany, 1989).

S. Bopp, F. Durst, C. Tropea, “In-cylinder velocity measurements with a mobile fiber optic LDA system,” in Proceedings of the 1990 SAE Congress and Exposition (Society of Automotive Engineers, Warrendale, Pa., 1990), paper 900055.

Faber, M.

D. Dopheide, M. Faber, G. Reim, G. Taux, “A portable frequency stabilized laser diode backscatter semiconductor LDA for high velocity applications,” in Proceedings of the Fourth International Symposium on Application of Laser Anemometry to Fluid Mechanics (LADOAN, Institute Superior Tecnico, Lisbon, 1989).

Forder, P. W.

P. W. Forder, C. N. Pannell, J. D. C. Jones, D. A. Jackson, “Designs of fibre optic probes for laser anemometry,” in Proceedings of the Second International Symposium on Laser Anemometry: Advances and Applications (UK and Dutch LDA Users Group, Strathclyde, UK, 1987).

Goldberg, L.

L. Goldberg, H. F. Taylor, A. Dandrige, J. F. Weller, R. O. Miles, “Spectral characteristics of semiconductor lasers with optical feedback,” IEEE Trans. Microwave Theory Tech. MTT-30, 401–420 (1982).
[CrossRef]

Greve, J.

F. F. M. de Mul, H. W. Jentink, M. Koelink, J. Greve, J. G. Aarnoudse, “Velocimetry with diode lasers,” in Proceedings of the Third International Conference on Laser Anemometry: Advances and Applications (UK and Dutch LDA Users Group, Swansea, Wales, UK, September1989).

Hackney, N.

R. G. W. Brown, J. G. Burnett, N. Hackney, “A miniature, battery operated laser Doppler anemometer,” in Proceedings of the Fourth International Symposium on Application of Laser Anemometry to Fluid Mechanics (LADOAN, Institute Superior Tecnico, Lisbon, 1988).

Hosokawa, S.

Y. Ikeda, T. Nakajiwa, S. Hosokawa, R. Matsumoto, “A compact fiber LDV with a perforated beam expander,” Meas. Sci. Technol. 1, 260–264 (1990).
[CrossRef]

Ikeda, Y.

Y. Ikeda, T. Nakajiwa, S. Hosokawa, R. Matsumoto, “A compact fiber LDV with a perforated beam expander,” Meas. Sci. Technol. 1, 260–264 (1990).
[CrossRef]

Jackson, D. A.

D. A. Jackson, J. D. C. Jones, “Extrinsic fibre-optic sensors for remote measurement: Part I and Part II,” Opt. Laser Technol. 18, 243–249 (1986).
[CrossRef]

J. D. C. Jones, R. K. Y. Chan, D. A. Jackson, “Design of fibre optic systems for Doppler difference laser velocimetry,” in Proceedings of the Second International Symposium on Applications of Laser Anemometry to Fluid Mechanics (LADOAN, Institute Superior Tecnico, Lisbon, 1984).

P. W. Forder, C. N. Pannell, J. D. C. Jones, D. A. Jackson, “Designs of fibre optic probes for laser anemometry,” in Proceedings of the Second International Symposium on Laser Anemometry: Advances and Applications (UK and Dutch LDA Users Group, Strathclyde, UK, 1987).

Jentink, H. W.

F. F. M. de Mul, H. W. Jentink, M. Koelink, J. Greve, J. G. Aarnoudse, “Velocimetry with diode lasers,” in Proceedings of the Third International Conference on Laser Anemometry: Advances and Applications (UK and Dutch LDA Users Group, Swansea, Wales, UK, September1989).

Jones, J. D. C.

D. A. Jackson, J. D. C. Jones, “Extrinsic fibre-optic sensors for remote measurement: Part I and Part II,” Opt. Laser Technol. 18, 243–249 (1986).
[CrossRef]

J. D. C. Jones, R. K. Y. Chan, D. A. Jackson, “Design of fibre optic systems for Doppler difference laser velocimetry,” in Proceedings of the Second International Symposium on Applications of Laser Anemometry to Fluid Mechanics (LADOAN, Institute Superior Tecnico, Lisbon, 1984).

P. W. Forder, C. N. Pannell, J. D. C. Jones, D. A. Jackson, “Designs of fibre optic probes for laser anemometry,” in Proceedings of the Second International Symposium on Laser Anemometry: Advances and Applications (UK and Dutch LDA Users Group, Strathclyde, UK, 1987).

Koelink, M.

F. F. M. de Mul, H. W. Jentink, M. Koelink, J. Greve, J. G. Aarnoudse, “Velocimetry with diode lasers,” in Proceedings of the Third International Conference on Laser Anemometry: Advances and Applications (UK and Dutch LDA Users Group, Swansea, Wales, UK, September1989).

Kristensen, J.

C. Tropea, G. Dimaczek, J. Kristensen, “Evaluation of the Dantec burst spectrum analyzer,” Rep. LSTM 218/I/88 (Lehrstuhl für Strömungsmechanik, Universität Erlangen-Nürnberg, Erlangen D-8520, Germany, 1988).

Lorenz, M.

M. Lorenz, K. Prescher, “Cycle resolved LDV measurements of a fired SI-engine at high data rates using a conventional modular LDV-system,” in Proceedings of the 1990 SAE Congress and Exposition (Society of Automotive Engineers, Warrendale, Pa., 1990), paper 900054.

Matsumoto, R.

Y. Ikeda, T. Nakajiwa, S. Hosokawa, R. Matsumoto, “A compact fiber LDV with a perforated beam expander,” Meas. Sci. Technol. 1, 260–264 (1990).
[CrossRef]

Miles, R. O.

L. Goldberg, H. F. Taylor, A. Dandrige, J. F. Weller, R. O. Miles, “Spectral characteristics of semiconductor lasers with optical feedback,” IEEE Trans. Microwave Theory Tech. MTT-30, 401–420 (1982).
[CrossRef]

Müller, R.

R. Müller, A. Naqwi, “Optimization of a laser diode anemometry system,” Rep. LSTM 239/T/88 (Lehrstuhl für Strömungsmechanik, Universität Erlangen-Nürnberg, Erlangen D-8520, Germany, 1988).

Nakajiwa, T.

Y. Ikeda, T. Nakajiwa, S. Hosokawa, R. Matsumoto, “A compact fiber LDV with a perforated beam expander,” Meas. Sci. Technol. 1, 260–264 (1990).
[CrossRef]

Naqwi, A.

A. Naqwi, F. Durst, “Computation of light scattering from a dual-beam system,” Rep. LSTM 259/T/89 (Lehrstuhl für Strömungsmechanik, Universität Erlangen-Nürnberg, Erlangen D-8520, Germany, 1989).

R. Müller, A. Naqwi, “Optimization of a laser diode anemometry system,” Rep. LSTM 239/T/88 (Lehrstuhl für Strömungsmechanik, Universität Erlangen-Nürnberg, Erlangen D-8520, Germany, 1988).

Pannell, C. N.

P. W. Forder, C. N. Pannell, J. D. C. Jones, D. A. Jackson, “Designs of fibre optic probes for laser anemometry,” in Proceedings of the Second International Symposium on Laser Anemometry: Advances and Applications (UK and Dutch LDA Users Group, Strathclyde, UK, 1987).

Prescher, K.

M. Lorenz, K. Prescher, “Cycle resolved LDV measurements of a fired SI-engine at high data rates using a conventional modular LDV-system,” in Proceedings of the 1990 SAE Congress and Exposition (Society of Automotive Engineers, Warrendale, Pa., 1990), paper 900054.

Reim, G.

D. Dopheide, M. Faber, G. Reim, G. Taux, “A portable frequency stabilized laser diode backscatter semiconductor LDA for high velocity applications,” in Proceedings of the Fourth International Symposium on Application of Laser Anemometry to Fluid Mechanics (LADOAN, Institute Superior Tecnico, Lisbon, 1989).

Struthers, D.

C. Tropea, D. Struthers, “Microprocessor based on-line measurement system for LDA,” in Proceedings of an International Specialists Meeting on the Use of Computers in Laser Anemometry, H. J. Pfeifer, B. Jeaggy, eds. (Institut Saint Louis, Saint Louis, France, 1987).

Taux, G.

D. Dopheide, M. Faber, G. Reim, G. Taux, “A portable frequency stabilized laser diode backscatter semiconductor LDA for high velocity applications,” in Proceedings of the Fourth International Symposium on Application of Laser Anemometry to Fluid Mechanics (LADOAN, Institute Superior Tecnico, Lisbon, 1989).

Taylor, H. F.

L. Goldberg, H. F. Taylor, A. Dandrige, J. F. Weller, R. O. Miles, “Spectral characteristics of semiconductor lasers with optical feedback,” IEEE Trans. Microwave Theory Tech. MTT-30, 401–420 (1982).
[CrossRef]

Tropea, C.

C. Tropea, G. Dimaczek, J. Kristensen, “Evaluation of the Dantec burst spectrum analyzer,” Rep. LSTM 218/I/88 (Lehrstuhl für Strömungsmechanik, Universität Erlangen-Nürnberg, Erlangen D-8520, Germany, 1988).

C. Tropea, D. Struthers, “Microprocessor based on-line measurement system for LDA,” in Proceedings of an International Specialists Meeting on the Use of Computers in Laser Anemometry, H. J. Pfeifer, B. Jeaggy, eds. (Institut Saint Louis, Saint Louis, France, 1987).

J. Domnick, C. Tropea, R. Wagner, “A miniaturized semiconductor fiber optic phase-Doppler anemometer (DF-PDA) with applications to liquid sprays,” in Proceedings of the International Conference on Multiphase Flows (University of Tsukuba, Tsukuba, Japan, September1991).

S. Bopp, F. Durst, C. Tropea, “In-cylinder velocity measurements with a mobile fiber optic LDA system,” in Proceedings of the 1990 SAE Congress and Exposition (Society of Automotive Engineers, Warrendale, Pa., 1990), paper 900055.

Wagner, R.

J. Domnick, C. Tropea, R. Wagner, “A miniaturized semiconductor fiber optic phase-Doppler anemometer (DF-PDA) with applications to liquid sprays,” in Proceedings of the International Conference on Multiphase Flows (University of Tsukuba, Tsukuba, Japan, September1991).

Weller, J. F.

L. Goldberg, H. F. Taylor, A. Dandrige, J. F. Weller, R. O. Miles, “Spectral characteristics of semiconductor lasers with optical feedback,” IEEE Trans. Microwave Theory Tech. MTT-30, 401–420 (1982).
[CrossRef]

IEEE Trans. Microwave Theory Tech. (1)

L. Goldberg, H. F. Taylor, A. Dandrige, J. F. Weller, R. O. Miles, “Spectral characteristics of semiconductor lasers with optical feedback,” IEEE Trans. Microwave Theory Tech. MTT-30, 401–420 (1982).
[CrossRef]

Meas. Sci. Technol. (1)

Y. Ikeda, T. Nakajiwa, S. Hosokawa, R. Matsumoto, “A compact fiber LDV with a perforated beam expander,” Meas. Sci. Technol. 1, 260–264 (1990).
[CrossRef]

Opt. Laser Technol. (1)

D. A. Jackson, J. D. C. Jones, “Extrinsic fibre-optic sensors for remote measurement: Part I and Part II,” Opt. Laser Technol. 18, 243–249 (1986).
[CrossRef]

Other (15)

Diode Laser Guide Product Catalog (Melles-Griot, Irvine, Calif., 1990).

S. Bopp, F. Durst, C. Tropea, “In-cylinder velocity measurements with a mobile fiber optic LDA system,” in Proceedings of the 1990 SAE Congress and Exposition (Society of Automotive Engineers, Warrendale, Pa., 1990), paper 900055.

M. Lorenz, K. Prescher, “Cycle resolved LDV measurements of a fired SI-engine at high data rates using a conventional modular LDV-system,” in Proceedings of the 1990 SAE Congress and Exposition (Society of Automotive Engineers, Warrendale, Pa., 1990), paper 900054.

C. Tropea, D. Struthers, “Microprocessor based on-line measurement system for LDA,” in Proceedings of an International Specialists Meeting on the Use of Computers in Laser Anemometry, H. J. Pfeifer, B. Jeaggy, eds. (Institut Saint Louis, Saint Louis, France, 1987).

J. Domnick, C. Tropea, R. Wagner, “A miniaturized semiconductor fiber optic phase-Doppler anemometer (DF-PDA) with applications to liquid sprays,” in Proceedings of the International Conference on Multiphase Flows (University of Tsukuba, Tsukuba, Japan, September1991).

Laser Doppler Velocimetry Components Product Catalog (TSI, Inc., St. Paul, Minn., 1991).

A. Naqwi, F. Durst, “Computation of light scattering from a dual-beam system,” Rep. LSTM 259/T/89 (Lehrstuhl für Strömungsmechanik, Universität Erlangen-Nürnberg, Erlangen D-8520, Germany, 1989).

C. Tropea, G. Dimaczek, J. Kristensen, “Evaluation of the Dantec burst spectrum analyzer,” Rep. LSTM 218/I/88 (Lehrstuhl für Strömungsmechanik, Universität Erlangen-Nürnberg, Erlangen D-8520, Germany, 1988).

D. Dopheide, M. Faber, G. Reim, G. Taux, “A portable frequency stabilized laser diode backscatter semiconductor LDA for high velocity applications,” in Proceedings of the Fourth International Symposium on Application of Laser Anemometry to Fluid Mechanics (LADOAN, Institute Superior Tecnico, Lisbon, 1989).

R. Müller, A. Naqwi, “Optimization of a laser diode anemometry system,” Rep. LSTM 239/T/88 (Lehrstuhl für Strömungsmechanik, Universität Erlangen-Nürnberg, Erlangen D-8520, Germany, 1988).

R. G. W. Brown, J. G. Burnett, N. Hackney, “A miniature, battery operated laser Doppler anemometer,” in Proceedings of the Fourth International Symposium on Application of Laser Anemometry to Fluid Mechanics (LADOAN, Institute Superior Tecnico, Lisbon, 1988).

F. F. M. de Mul, H. W. Jentink, M. Koelink, J. Greve, J. G. Aarnoudse, “Velocimetry with diode lasers,” in Proceedings of the Third International Conference on Laser Anemometry: Advances and Applications (UK and Dutch LDA Users Group, Swansea, Wales, UK, September1989).

Laser Diode LDA Product Information (Polytec GmbH, Waldbronn, Germany, 1991).

P. W. Forder, C. N. Pannell, J. D. C. Jones, D. A. Jackson, “Designs of fibre optic probes for laser anemometry,” in Proceedings of the Second International Symposium on Laser Anemometry: Advances and Applications (UK and Dutch LDA Users Group, Strathclyde, UK, 1987).

J. D. C. Jones, R. K. Y. Chan, D. A. Jackson, “Design of fibre optic systems for Doppler difference laser velocimetry,” in Proceedings of the Second International Symposium on Applications of Laser Anemometry to Fluid Mechanics (LADOAN, Institute Superior Tecnico, Lisbon, 1984).

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Figures (13)

Fig. 1
Fig. 1

Block diagram of the base optical unit with a single Bragg cell.

Fig. 2
Fig. 2

Photography of the DFLDA: (a) cover removed, (b) assembled.

Fig. 3
Fig. 3

Image of fringes in the measuring control volume (without shift): (a) without an optical isolator, (b) with an optical isolator.

Fig. 4
Fig. 4

Block diagram of the base optical unit with a double Bragg cell.

Fig. 5
Fig. 5

Normalized collected power as a function of normalized beam diameter for several receiving aperture diameters.

Fig. 6
Fig. 6

Cross-sectional views of the 19- and 30-mm fiber-optic probes.

Fig. 7
Fig. 7

Computed power of collected scattered light for two probes (P0 = 36 mW, dpart = 2 μm).

Fig. 8
Fig. 8

Measured velocity profiles in a T junction.

Fig. 9
Fig. 9

Digitized Doppler signals and their power spectral densities.

Fig. 10
Fig. 10

Measurement location and sign convention for in-cylinder velocity measurements.

Fig. 11
Fig. 11

Typical single-cycle velocity data in (a) a motored engine, (b) a fired engine.

Fig. 12
Fig. 12

Typical boundary layer profiles that were made by using various focal lengths: (a) 60 mm, (b) 120 and 250 mm.

Fig. 13
Fig. 13

Two-point probe for the measurement of space–time correlations.

Tables (3)

Tables Icon

Table I Optical Specifications of the 19- and 30-mm Fiber-Optic Probes

Tables Icon

Table II Specifications and Operating Parameters of the Research Engine

Tables Icon

Table III Optical Specifications of the 85-mm Probe

Equations (5)

Equations on this page are rendered with MathJax. Learn more.

SNR η P 0 Δ f ( D a d in f 2 ) 2 a 2 G V 2 ,
K = ( D a d in f 2 ) 2
f sh = N min · U π d in 4 f λ ,
Δ f D f D = N min f osc N f r U d MCV ,
Δ f D f D = f s 2 N min f osc 1 f D ,

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