Abstract

We report an optical range sensor that combines the advantages of focus sensing and interferometry. It works for specularly reflecting objects and for diffusely reflecting objects. The sensor is simple, robust against vibrations, and has high depth resolution. The aperture is very small, hence the sensor is small and minimizes shading problems. The sensor is based on the following principle: A light spot is projected onto the object under test. The radius of the wave that is scattered at the object is measured with high accuracy by shearing interferometry.

© 1988 Optical Society of America

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References

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  1. T. C. Strand, “Optical Three-Dimensional Sensing for Machine Vision,” Opt. Eng. 24, 33 (1985).
    [CrossRef]
  2. M. Halioua, H. C. Liu, “Optical Sensing Techniques for 3-D Machine Vision,” Proc. Soc. Photo-Opt. Instrum. Eng. 665, 150 (1986).
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  4. M. Taylor, D. A. Jackson, “High Precision Non-Contacting Optical Level Gauge,” Opt. Acta 33, 1571 (1986).
    [CrossRef]
  5. G. Hausler, E. Korner, “Simple Focusing Criterion,” Appl. Opt. 23, 2468 (1984).
    [CrossRef] [PubMed]
  6. R. Brodmann, “In-Process Optical Metrology for Precision Machining,” Proc. Soc. Photo-Opt. Instrum. Eng. 802, 165 (1987).
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    [CrossRef] [PubMed]
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  9. A. F. Fercher, H. Z. Hu, U. Vry, “Rough Surface Interferometry with a Two-Wavelength Heterodyne Speckle Interferometer,” Appl. Opt. 24, 2181 (1985).
    [CrossRef] [PubMed]
  10. J. W. Goodman, “Statistical Properties of Laser Speckle Patterns,” in Laser Speckle and Related Phenomena, J. C. Dainty, Ed. (Springer-Verlag, Berlin, 1984), p. 9.
  11. G. Hausler, J. Herrmann, “Range Sensing by Shearing Interferometry: Influence of Speckle,” Appl. Opt. 27, 4631 (1988).
    [CrossRef] [PubMed]
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1988 (1)

1987 (1)

R. Brodmann, “In-Process Optical Metrology for Precision Machining,” Proc. Soc. Photo-Opt. Instrum. Eng. 802, 165 (1987).

1986 (3)

M. Halioua, H. C. Liu, “Optical Sensing Techniques for 3-D Machine Vision,” Proc. Soc. Photo-Opt. Instrum. Eng. 665, 150 (1986).

W. Dremel, G. Hausler, M. Maul, “Triangulation with Large Dynamical Range,” Proc. Soc. Photo-Opt. Instrum. Eng. 665, 182 (1986).

M. Taylor, D. A. Jackson, “High Precision Non-Contacting Optical Level Gauge,” Opt. Acta 33, 1571 (1986).
[CrossRef]

1985 (2)

1984 (1)

1983 (1)

1981 (1)

1980 (2)

Brodmann, R.

R. Brodmann, “In-Process Optical Metrology for Precision Machining,” Proc. Soc. Photo-Opt. Instrum. Eng. 802, 165 (1987).

Dremel, W.

W. Dremel, G. Hausler, M. Maul, “Triangulation with Large Dynamical Range,” Proc. Soc. Photo-Opt. Instrum. Eng. 665, 182 (1986).

Fercher, A. F.

Goodman, J. W.

J. W. Goodman, “Statistical Properties of Laser Speckle Patterns,” in Laser Speckle and Related Phenomena, J. C. Dainty, Ed. (Springer-Verlag, Berlin, 1984), p. 9.

Halioua, M.

M. Halioua, H. C. Liu, “Optical Sensing Techniques for 3-D Machine Vision,” Proc. Soc. Photo-Opt. Instrum. Eng. 665, 150 (1986).

Hausler, G.

Hayslett, C. R.

Herrmann, J.

Hu, H. Z.

Jackson, D. A.

M. Taylor, D. A. Jackson, “High Precision Non-Contacting Optical Level Gauge,” Opt. Acta 33, 1571 (1986).
[CrossRef]

Korner, E.

Kwon, O.

Liu, H. C.

M. Halioua, H. C. Liu, “Optical Sensing Techniques for 3-D Machine Vision,” Proc. Soc. Photo-Opt. Instrum. Eng. 665, 150 (1986).

Maul, M.

W. Dremel, G. Hausler, M. Maul, “Triangulation with Large Dynamical Range,” Proc. Soc. Photo-Opt. Instrum. Eng. 665, 182 (1986).

Sommargren, G. E.

Strand, T. C.

T. C. Strand, “Optical Three-Dimensional Sensing for Machine Vision,” Opt. Eng. 24, 33 (1985).
[CrossRef]

Takasaki, H.

Taylor, M.

M. Taylor, D. A. Jackson, “High Precision Non-Contacting Optical Level Gauge,” Opt. Acta 33, 1571 (1986).
[CrossRef]

Tsukiji, M.

Umeda, N.

Vry, U.

Wyant, J. C.

Appl. Opt. (7)

Opt. Acta (1)

M. Taylor, D. A. Jackson, “High Precision Non-Contacting Optical Level Gauge,” Opt. Acta 33, 1571 (1986).
[CrossRef]

Opt. Eng. (1)

T. C. Strand, “Optical Three-Dimensional Sensing for Machine Vision,” Opt. Eng. 24, 33 (1985).
[CrossRef]

Proc. Soc. Photo-Opt. Instrum. Eng. (3)

M. Halioua, H. C. Liu, “Optical Sensing Techniques for 3-D Machine Vision,” Proc. Soc. Photo-Opt. Instrum. Eng. 665, 150 (1986).

W. Dremel, G. Hausler, M. Maul, “Triangulation with Large Dynamical Range,” Proc. Soc. Photo-Opt. Instrum. Eng. 665, 182 (1986).

R. Brodmann, “In-Process Optical Metrology for Precision Machining,” Proc. Soc. Photo-Opt. Instrum. Eng. 802, 165 (1987).

Other (1)

J. W. Goodman, “Statistical Properties of Laser Speckle Patterns,” in Laser Speckle and Related Phenomena, J. C. Dainty, Ed. (Springer-Verlag, Berlin, 1984), p. 9.

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Figures (8)

Fig. 1
Fig. 1

Range sensing by shearing interferometry: basic setup.

Fig. 2
Fig. 2

Fringe patterns for a diffusely reflecting object, for a constant shear, and different speckle size: (a) large speckles; (b) medium speckles; (c) speckles approximately as large as the shear.

Fig. 3
Fig. 3

High resolution evaluation of the fringe pattern by iterative oversampling of the Fourier transform. After seven iterations, resolution increased by a factor of 27.

Fig. 4
Fig. 4

Experimental results of range sensing of a specularly reflecting object: (a) measured distance z vs actual z displacement and (b) deviations from the regression line taken from (a). The maximum deviation is ±20 μm at a distance z of ~300 mm. With standard deviation σ ≈ 10 μm, we get a relative depth resolution of σ/z ≈ 1/30.000. The measuring aperture was only 0.035.

Fig. 5
Fig. 5

Experimental results of range sensing for diffusely reflecting objects. To reduce speckle errors, the object spot was moved across the object by a distance of 1.5 mm during each measurement. (a) Measured distance vs actual displacement and (b) deviation from the regression line taken from (a).

Fig. 6
Fig. 6

High resolution fringe evaluation by heterodyning: basic setup.

Fig. 7
Fig. 7

Experimental results of heterodyne evaluation with a specularly reflecting object.

Fig. 8
Fig. 8

Experimental results of heterodyne evaluation for a diffusely reflecting object. To study the influence of speckle on the reproducibility, several measurements are performed on different locations of the surface but at a constant object distance. The small squares show statistical variation without speckle reduction; the circles indicate measurements with speckle reduction by a boiling pupil.

Equations (7)

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δ z = ± δ x / sin θ .
δ z = ± λ / 2 · sin θ · sin u .
δ z = ± λ / 2 · sin 2 u ,
p = λ z / s .
d s = λ z / d o .
s d s .
d 0 p .

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