Abstract

An image-processing system with inexpensive computers is described. With the adaption to the special case of a Young’s pattern of interference fringes it is possible to achieve an evaluation time of 2 pictures/sec for such patterns.

© 1985 Optical Society of America

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References

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  1. M. Francon, Laser Speckle and Application in Optics (Academic, New York, 1975).
  2. F. P. Chiang, “Subjective Laser Speckle Method and its Application to Solid Mechanics Problems,” Opt. Eng. 21, 379 (1982).
    [CrossRef]
  3. R. Meynart, “Instantaneous Velocity Field Measurements in Unsteady Gas Flow by Speckle Velocimetry,” Appl. Opt. 22, 535 (1983).
    [CrossRef] [PubMed]
  4. U. Köpf, “Application of Speckling for Measuring the Deflection of Laser Light by Phase Objects,” Opt. Commun. 5, 853 (1972).
    [CrossRef]
  5. P. V. Farrell, D. L. Hofeldt, “Temperature Measurement in Gases using Speckle Photography,” Appl. Opt. 23, 1055 (1984).
    [CrossRef] [PubMed]
  6. U. Wernekinck, W. Merzkirch, N. Fomin, “Measurement of Light Deflection in a Turbulent Density Field,” Exp. Fluids 3, 206 (1985).
    [CrossRef]
  7. R. Meynart, “Digital Image Processing for Speckle Flow Velocimetry,” Rev. Sci. Instrum. 53, 110 (1980).
    [CrossRef]
  8. H. G. Kaufmann et al., “An Electro-optical Read-out System for Analysis of Speckle Photographs,” J. Phys. E 13, 3411.
  9. B. Ineichen, P. Eglin, R. Dandliker, “Hybrid Optical and Electronic Image Processing for Strain Measurement by Speckle Photography,” Appl. Opt. 19, 2191 (1980).
    [CrossRef] [PubMed]

1985

U. Wernekinck, W. Merzkirch, N. Fomin, “Measurement of Light Deflection in a Turbulent Density Field,” Exp. Fluids 3, 206 (1985).
[CrossRef]

1984

1983

1982

F. P. Chiang, “Subjective Laser Speckle Method and its Application to Solid Mechanics Problems,” Opt. Eng. 21, 379 (1982).
[CrossRef]

1980

1972

U. Köpf, “Application of Speckling for Measuring the Deflection of Laser Light by Phase Objects,” Opt. Commun. 5, 853 (1972).
[CrossRef]

Chiang, F. P.

F. P. Chiang, “Subjective Laser Speckle Method and its Application to Solid Mechanics Problems,” Opt. Eng. 21, 379 (1982).
[CrossRef]

Dandliker, R.

Eglin, P.

Farrell, P. V.

Fomin, N.

U. Wernekinck, W. Merzkirch, N. Fomin, “Measurement of Light Deflection in a Turbulent Density Field,” Exp. Fluids 3, 206 (1985).
[CrossRef]

Francon, M.

M. Francon, Laser Speckle and Application in Optics (Academic, New York, 1975).

Hofeldt, D. L.

Ineichen, B.

Kaufmann, H. G.

H. G. Kaufmann et al., “An Electro-optical Read-out System for Analysis of Speckle Photographs,” J. Phys. E 13, 3411.

Köpf, U.

U. Köpf, “Application of Speckling for Measuring the Deflection of Laser Light by Phase Objects,” Opt. Commun. 5, 853 (1972).
[CrossRef]

Merzkirch, W.

U. Wernekinck, W. Merzkirch, N. Fomin, “Measurement of Light Deflection in a Turbulent Density Field,” Exp. Fluids 3, 206 (1985).
[CrossRef]

Meynart, R.

R. Meynart, “Instantaneous Velocity Field Measurements in Unsteady Gas Flow by Speckle Velocimetry,” Appl. Opt. 22, 535 (1983).
[CrossRef] [PubMed]

R. Meynart, “Digital Image Processing for Speckle Flow Velocimetry,” Rev. Sci. Instrum. 53, 110 (1980).
[CrossRef]

Wernekinck, U.

U. Wernekinck, W. Merzkirch, N. Fomin, “Measurement of Light Deflection in a Turbulent Density Field,” Exp. Fluids 3, 206 (1985).
[CrossRef]

Appl. Opt.

Exp. Fluids

U. Wernekinck, W. Merzkirch, N. Fomin, “Measurement of Light Deflection in a Turbulent Density Field,” Exp. Fluids 3, 206 (1985).
[CrossRef]

J. Phys. E

H. G. Kaufmann et al., “An Electro-optical Read-out System for Analysis of Speckle Photographs,” J. Phys. E 13, 3411.

Opt. Commun.

U. Köpf, “Application of Speckling for Measuring the Deflection of Laser Light by Phase Objects,” Opt. Commun. 5, 853 (1972).
[CrossRef]

Opt. Eng.

F. P. Chiang, “Subjective Laser Speckle Method and its Application to Solid Mechanics Problems,” Opt. Eng. 21, 379 (1982).
[CrossRef]

Rev. Sci. Instrum.

R. Meynart, “Digital Image Processing for Speckle Flow Velocimetry,” Rev. Sci. Instrum. 53, 110 (1980).
[CrossRef]

Other

M. Francon, Laser Speckle and Application in Optics (Academic, New York, 1975).

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Figures (7)

Fig. 1
Fig. 1

Young’s pattern (photography).

Fig. 2
Fig. 2

Setup for automatic evaluation.

Fig. 3
Fig. 3

Examples of compensated Young’s pattern: (a) Young’s pattern without pre-processing; (b) Young’s pattern with compensator; (c) Young’s pattern with rotating ground glass; (d) Young’s pattern with rotating ground glass and compensator.

Fig. 4
Fig. 4

Autocorrelation method.

Fig. 5
Fig. 5

Trances on which the CF is calculated. Examples of the correlation function in each direction.

Fig. 6
Fig. 6

Error of evaluation.

Fig. 7
Fig. 7

Refractive-index gradient of a laminar and turbulent jet.

Equations (1)

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g ( u ) = n = 1 F { m = 1 F u I ( m , n ) * I ( m + u , n ) m = 1 F [ I ( m , n ) ] 2 } u = 0 , , F 1 , m , n = 1 , , F .

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