Abstract

Optical techniques are appropriate to industrial inspection tasks because of their noncontact nature, high response speed, and increasing ruggedness and affordability. This paper relates to the development of two electrooptical systems for the inspection of woven webs and of extruded wires. In both cases, parameters of industrial interest are inferred from the light beam distribution after interaction with the material under analysis. Suitable optical configurations provide a laminar light beam which is line array scanned and Fourier transform processed. The emphasis is on the maximization of the measurement reliability, depth of field, and processing speed according to on-line application requirements.

© 1988 Optical Society of America

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References

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  1. B. G. Batchelor, D. A. Hill, D. C. Hodgson, Eds., Automated Visual Inspection (IFS/North-Holland, U.K., 1985).
  2. A. Browne, L. Norton-Wayne, Vision and Information Processing for Automation (Plenum, New York, 1986).
  3. P. Cielo, Optical Techniques for Industrial Inspection (Academic, Boston, 1988).
  4. B. Vogeley, “Vision Systems or Vision Sensors?” Sensor Rev. 7(3), 152 (1987).
    [CrossRef]
  5. D. L. Hudson, “A Practical Solution Using a New Approach to Machine Vision,” in Conference Proceedings, QualTest-2, ASNT/ASQC/SME (1983), p. 27-1.
  6. P. Chavel, T. C. Strand, “Range Measurement Using Talbot Diffraction Imaging of Gratings,” Appl. Opt. 23, 862 (1984).
    [CrossRef] [PubMed]
  7. M. W. Siegel, “Lasers and CCD’s for Flash Measurement of Small Diameters,” Proc. Soc. Photo-Opt. Instrum. Eng. 730, 119 (1986).
  8. P. Cielo, G. Vaudreuil, M. Lamontagne, “In-Process Product Control by Electro-optical Sensors,” in ISA-Digicom ’87, Montreal (21–22 Oct. 1987).
  9. H. L. Kasdan, U.S. Patent3,937,580 (1976).
  10. M. Kerker, The Scattering of Light and Other Electromagnetic Radiation (Academic, New York, 1969).
  11. H. C. van de Hulst, Light Scattering by Small Particles (Dover, New York, 1981).
  12. M. Born, E. Wolf, Principles of Optics (Pergamon, Oxford, 1975).
  13. Y. S. Touloukian, R. K. Kirby, R. E. Taylor, P. D. Desai, Thermophysical Properties of Matter, Vol. 12 (IFI/Plenum, New York, 1975), p. 1217.
  14. G. T. Dyos, S. A. Smith, “Two New Methods for Noncontact Temperature Measurement,” Proc. Soc. Photo-Opt. Instrum. Eng. 665, 96 (1986).

1987 (1)

B. Vogeley, “Vision Systems or Vision Sensors?” Sensor Rev. 7(3), 152 (1987).
[CrossRef]

1986 (2)

M. W. Siegel, “Lasers and CCD’s for Flash Measurement of Small Diameters,” Proc. Soc. Photo-Opt. Instrum. Eng. 730, 119 (1986).

G. T. Dyos, S. A. Smith, “Two New Methods for Noncontact Temperature Measurement,” Proc. Soc. Photo-Opt. Instrum. Eng. 665, 96 (1986).

1984 (1)

Born, M.

M. Born, E. Wolf, Principles of Optics (Pergamon, Oxford, 1975).

Browne, A.

A. Browne, L. Norton-Wayne, Vision and Information Processing for Automation (Plenum, New York, 1986).

Chavel, P.

Cielo, P.

P. Cielo, G. Vaudreuil, M. Lamontagne, “In-Process Product Control by Electro-optical Sensors,” in ISA-Digicom ’87, Montreal (21–22 Oct. 1987).

P. Cielo, Optical Techniques for Industrial Inspection (Academic, Boston, 1988).

Desai, P. D.

Y. S. Touloukian, R. K. Kirby, R. E. Taylor, P. D. Desai, Thermophysical Properties of Matter, Vol. 12 (IFI/Plenum, New York, 1975), p. 1217.

Dyos, G. T.

G. T. Dyos, S. A. Smith, “Two New Methods for Noncontact Temperature Measurement,” Proc. Soc. Photo-Opt. Instrum. Eng. 665, 96 (1986).

Hudson, D. L.

D. L. Hudson, “A Practical Solution Using a New Approach to Machine Vision,” in Conference Proceedings, QualTest-2, ASNT/ASQC/SME (1983), p. 27-1.

Kasdan, H. L.

H. L. Kasdan, U.S. Patent3,937,580 (1976).

Kerker, M.

M. Kerker, The Scattering of Light and Other Electromagnetic Radiation (Academic, New York, 1969).

Kirby, R. K.

Y. S. Touloukian, R. K. Kirby, R. E. Taylor, P. D. Desai, Thermophysical Properties of Matter, Vol. 12 (IFI/Plenum, New York, 1975), p. 1217.

Lamontagne, M.

P. Cielo, G. Vaudreuil, M. Lamontagne, “In-Process Product Control by Electro-optical Sensors,” in ISA-Digicom ’87, Montreal (21–22 Oct. 1987).

Norton-Wayne, L.

A. Browne, L. Norton-Wayne, Vision and Information Processing for Automation (Plenum, New York, 1986).

Siegel, M. W.

M. W. Siegel, “Lasers and CCD’s for Flash Measurement of Small Diameters,” Proc. Soc. Photo-Opt. Instrum. Eng. 730, 119 (1986).

Smith, S. A.

G. T. Dyos, S. A. Smith, “Two New Methods for Noncontact Temperature Measurement,” Proc. Soc. Photo-Opt. Instrum. Eng. 665, 96 (1986).

Strand, T. C.

Taylor, R. E.

Y. S. Touloukian, R. K. Kirby, R. E. Taylor, P. D. Desai, Thermophysical Properties of Matter, Vol. 12 (IFI/Plenum, New York, 1975), p. 1217.

Touloukian, Y. S.

Y. S. Touloukian, R. K. Kirby, R. E. Taylor, P. D. Desai, Thermophysical Properties of Matter, Vol. 12 (IFI/Plenum, New York, 1975), p. 1217.

van de Hulst, H. C.

H. C. van de Hulst, Light Scattering by Small Particles (Dover, New York, 1981).

Vaudreuil, G.

P. Cielo, G. Vaudreuil, M. Lamontagne, “In-Process Product Control by Electro-optical Sensors,” in ISA-Digicom ’87, Montreal (21–22 Oct. 1987).

Vogeley, B.

B. Vogeley, “Vision Systems or Vision Sensors?” Sensor Rev. 7(3), 152 (1987).
[CrossRef]

Wolf, E.

M. Born, E. Wolf, Principles of Optics (Pergamon, Oxford, 1975).

Appl. Opt. (1)

Proc. Soc. Photo-Opt. Instrum. Eng. (2)

M. W. Siegel, “Lasers and CCD’s for Flash Measurement of Small Diameters,” Proc. Soc. Photo-Opt. Instrum. Eng. 730, 119 (1986).

G. T. Dyos, S. A. Smith, “Two New Methods for Noncontact Temperature Measurement,” Proc. Soc. Photo-Opt. Instrum. Eng. 665, 96 (1986).

Sensor Rev. (1)

B. Vogeley, “Vision Systems or Vision Sensors?” Sensor Rev. 7(3), 152 (1987).
[CrossRef]

Other (10)

D. L. Hudson, “A Practical Solution Using a New Approach to Machine Vision,” in Conference Proceedings, QualTest-2, ASNT/ASQC/SME (1983), p. 27-1.

B. G. Batchelor, D. A. Hill, D. C. Hodgson, Eds., Automated Visual Inspection (IFS/North-Holland, U.K., 1985).

A. Browne, L. Norton-Wayne, Vision and Information Processing for Automation (Plenum, New York, 1986).

P. Cielo, Optical Techniques for Industrial Inspection (Academic, Boston, 1988).

P. Cielo, G. Vaudreuil, M. Lamontagne, “In-Process Product Control by Electro-optical Sensors,” in ISA-Digicom ’87, Montreal (21–22 Oct. 1987).

H. L. Kasdan, U.S. Patent3,937,580 (1976).

M. Kerker, The Scattering of Light and Other Electromagnetic Radiation (Academic, New York, 1969).

H. C. van de Hulst, Light Scattering by Small Particles (Dover, New York, 1981).

M. Born, E. Wolf, Principles of Optics (Pergamon, Oxford, 1975).

Y. S. Touloukian, R. K. Kirby, R. E. Taylor, P. D. Desai, Thermophysical Properties of Matter, Vol. 12 (IFI/Plenum, New York, 1975), p. 1217.

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Figures (15)

Fig. 1
Fig. 1

Front-surface photomicrographs of two web samples obtained under grazing-incidence illumination. The x axis corresponds to the knocking direction.

Fig. 2
Fig. 2

Moire fringe pattern obtained with a manually held variable-pitch grating for visual evaluation of the thread density in a woven web.

Fig. 3
Fig. 3

Straightforward configuration for the optical inspection of a periodic pattern.

Fig. 4
Fig. 4

Camera output with a configuration of the kind shown in Fig. 3; (a) single line-scan signal; (b) FFT spectrum of the same signal.

Fig. 5
Fig. 5

Top (a) and side (b) views of an optical configuration using shadow projection and unidimensional optical integration; S light source; SL, spherical lens; W, web material; CL, cylindrical lens; LA, line-array detector.

Fig. 6
Fig. 6

Line-array signals obtained with the configuration shown in Fig. 5 with web-to-detector distances of (a) 7 cm, (b) 12 cm, and (c) 25 cm.

Fig. 7
Fig. 7

Top (a) and side (b) diagrams of the setup used to compare results under transmissive and grazing incidence illumination: S, S′, light sources; SL, spherical lenses; W, web; CL, cylindrical lenses; LA, line-array detector.

Fig. 8
Fig. 8

Typical spectra obtained for the same sample illuminated (a) in transmission, (b) in reflection on the front surface, and (c) in reflection on the back surface.

Fig. 9
Fig. 9

Optimized optical design for thread density evaluation of a transmission-illuminated sample: S light source; SL, spherical lenses; W, web; CL, cylindrical lens; SF, spatial filter; LA, line-array detector.

Fig. 10
Fig. 10

Comparison of the thread density evaluated by the visual moire technique illustrated in Fig. 2 and by the FFT approach for different web samples.

Fig. 11
Fig. 11

Schematic diagram of the wire gauging system: S, light source; SL1, SL2, spherical lenses; W wire cross section; M, optical mask; LA, line-array detector.

Fig. 12
Fig. 12

Computed Fourier plane light distribution before masking, superposed to the mask transmissivity. The inset shows the photomicrograph of a portion of the binary mask.

Fig. 13
Fig. 13

(a) Photodetector-array output obtained with the setup shown in Fig. 11 when inspecting a 250-μm diam wire. Signals (b) and (c) show, respectively, the autocorrelation and power spectrum of signal (c).

Fig. 14
Fig. 14

Frequency spectra similar to Fig. 13(c) but obtained with wire diameters of (a) 400, (b) 650, and (c) 810 μm.

Fig. 15
Fig. 15

Resolution test for the Fourier transform diameter gauging system: the spectra (a) and (b) were obtained with the same wire before and after joule heating to produce a thermal expansion of the wire diameter by 0.8%.

Equations (4)

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I ( θ ) = 2 I 0 π r k | b 0 + 2 n = 1 b n cos n θ | 2 ,
b n = m J n ( m k a ) J n ( k a ) - J n ( m k a ) J n ( k a ) m J n ( m k a ) H n ( k a ) - J n ( m k a ) H n ( k a ) ,
I ( θ ) = I m [ sin ( k a sin θ ) ] 2 / ( k a sin θ ) 2 ,
I ( x ) = I m s 2 ( k a x ) 2 sin 2 k a s x ,

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