Abstract

Optical coatings that shift color with viewing angle have been adapted into optically variable foils, pigments, and inks to prevent color copying by color copiers, printers, cameras, or lithographic reproduction. Metal–dielectric multilayer thin-film structures have large color shifts with angle, high chroma, a large color gamut, and light fastness that make them uniquely suited for security inks. World currencies are now protected by these structures.

© 1996 Optical Society of America

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References

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  1. J. A. Dobrowolski, K. M. Baird, P. D. Carman, A. Waldorf, “Optical interference coatings for inhibiting of counterfeiting,” Opt. Acta 20, 925–937 (1973).
    [CrossRef]
  2. L. N. Hadley, D. M. Dennison, “Reflection and transmission interference filters,” J. Opt. Soc. Am. 37, 483–496 (1947).
    [CrossRef]
  3. A. F. Turner, “Some current developments in multilayer optical films,” J. Phys. Rad. 11, 444–460 (1950).
    [CrossRef]
  4. J. A. Dobrowolski, F. C. Ho, A. Waldorf, “Research on thin film anti-counterfeiting coatings at the National Research Council of Canada,” Appl. Opt.28, 2702–2717 (1989); J. A. Dobrowolski, “Optical thin film security devices,” in Optical Document Security, R. L. Van Renesse, ed. (Artech House, Boston, 1993), pp. 227–261.
    [CrossRef]
  5. J. Rolfe, “Vacuum coatings for document security,” in Thirty-Fourth Annual Technical Conference Proceedings (Society of Vacuum Coaters, Washington, D.C., 1991), pp. 20–25.
  6. J. Rolfe, “Optically variable devices for use on bank notes,” in Optical Security and Anticounterfeiting Systems, W. F. Fagan, ed., Proc. SPIE1210, 14–19 (1990).
  7. R. W. Phillips, T. Mayer, G. Ash, “Ink incorporating optically variable thin film flakes,” U.S. patent5,059,245 (22Oct.1991); OVI is a trademark of SICPA Holding S.A.
  8. The Currency Design Act: Hearing before the Subcommittee on Consumer Affairs and Coinage of the Committee on Banking, Finance and Urban Affairs, House of Representatives, on H.R.6005 (U.S. GPO, Washington, D.C., 24July1984).
  9. “Counterfeit deterrent features for the next generation currency design,” Pub. NMAB-472 (Committee on Next-Generation Currency Design, National Materials Advisory Board, U.S. National Research Council, National Academy of Sciences, Washington, D.C., 1993).
  10. Presented at the Druck und Papier Exhibition, Dusseldorf, Germany, 5–18 May 1995.
  11. M. T. Nowak, T. E. Lewis, “Lithographic printing members for use with laser-discharge imaging,” U.S. patent5,379,698 (10Jan.1995).
  12. R. W. Phillips, T. Mayer, G. S. Ash, “Method of making optical thin flakes and inks incorporating the same,” U.S. patent5,383,995 (24Jan.1995).
  13. R. W. Phillips, T. Mayer, G. S. Ash, “Optically variable printing ink,” U.S. patent5,279,657 (18Jan.1994).
  14. R. W. Phillips, “Optically variable films, pigments and inks,” in Optical Thin Films III: New Developments,” R. I. Seddon, ed., Proc. SPIE1323, 98–109 (1990).
  15. P. G. Coombs, R. W. Phillips, “Optically variable interference device with peak suppression and method,” U.S. patent5,214,530 (25May1993).

1973 (1)

J. A. Dobrowolski, K. M. Baird, P. D. Carman, A. Waldorf, “Optical interference coatings for inhibiting of counterfeiting,” Opt. Acta 20, 925–937 (1973).
[CrossRef]

1950 (1)

A. F. Turner, “Some current developments in multilayer optical films,” J. Phys. Rad. 11, 444–460 (1950).
[CrossRef]

1947 (1)

L. N. Hadley, D. M. Dennison, “Reflection and transmission interference filters,” J. Opt. Soc. Am. 37, 483–496 (1947).
[CrossRef]

Ash, G.

R. W. Phillips, T. Mayer, G. Ash, “Ink incorporating optically variable thin film flakes,” U.S. patent5,059,245 (22Oct.1991); OVI is a trademark of SICPA Holding S.A.

Ash, G. S.

R. W. Phillips, T. Mayer, G. S. Ash, “Method of making optical thin flakes and inks incorporating the same,” U.S. patent5,383,995 (24Jan.1995).

R. W. Phillips, T. Mayer, G. S. Ash, “Optically variable printing ink,” U.S. patent5,279,657 (18Jan.1994).

Baird, K. M.

J. A. Dobrowolski, K. M. Baird, P. D. Carman, A. Waldorf, “Optical interference coatings for inhibiting of counterfeiting,” Opt. Acta 20, 925–937 (1973).
[CrossRef]

Carman, P. D.

J. A. Dobrowolski, K. M. Baird, P. D. Carman, A. Waldorf, “Optical interference coatings for inhibiting of counterfeiting,” Opt. Acta 20, 925–937 (1973).
[CrossRef]

Coombs, P. G.

P. G. Coombs, R. W. Phillips, “Optically variable interference device with peak suppression and method,” U.S. patent5,214,530 (25May1993).

Dennison, D. M.

L. N. Hadley, D. M. Dennison, “Reflection and transmission interference filters,” J. Opt. Soc. Am. 37, 483–496 (1947).
[CrossRef]

Dobrowolski, J. A.

J. A. Dobrowolski, K. M. Baird, P. D. Carman, A. Waldorf, “Optical interference coatings for inhibiting of counterfeiting,” Opt. Acta 20, 925–937 (1973).
[CrossRef]

J. A. Dobrowolski, F. C. Ho, A. Waldorf, “Research on thin film anti-counterfeiting coatings at the National Research Council of Canada,” Appl. Opt.28, 2702–2717 (1989); J. A. Dobrowolski, “Optical thin film security devices,” in Optical Document Security, R. L. Van Renesse, ed. (Artech House, Boston, 1993), pp. 227–261.
[CrossRef]

Hadley, L. N.

L. N. Hadley, D. M. Dennison, “Reflection and transmission interference filters,” J. Opt. Soc. Am. 37, 483–496 (1947).
[CrossRef]

Ho, F. C.

J. A. Dobrowolski, F. C. Ho, A. Waldorf, “Research on thin film anti-counterfeiting coatings at the National Research Council of Canada,” Appl. Opt.28, 2702–2717 (1989); J. A. Dobrowolski, “Optical thin film security devices,” in Optical Document Security, R. L. Van Renesse, ed. (Artech House, Boston, 1993), pp. 227–261.
[CrossRef]

Lewis, T. E.

M. T. Nowak, T. E. Lewis, “Lithographic printing members for use with laser-discharge imaging,” U.S. patent5,379,698 (10Jan.1995).

Mayer, T.

R. W. Phillips, T. Mayer, G. Ash, “Ink incorporating optically variable thin film flakes,” U.S. patent5,059,245 (22Oct.1991); OVI is a trademark of SICPA Holding S.A.

R. W. Phillips, T. Mayer, G. S. Ash, “Method of making optical thin flakes and inks incorporating the same,” U.S. patent5,383,995 (24Jan.1995).

R. W. Phillips, T. Mayer, G. S. Ash, “Optically variable printing ink,” U.S. patent5,279,657 (18Jan.1994).

Nowak, M. T.

M. T. Nowak, T. E. Lewis, “Lithographic printing members for use with laser-discharge imaging,” U.S. patent5,379,698 (10Jan.1995).

Phillips, R. W.

R. W. Phillips, T. Mayer, G. S. Ash, “Method of making optical thin flakes and inks incorporating the same,” U.S. patent5,383,995 (24Jan.1995).

R. W. Phillips, T. Mayer, G. Ash, “Ink incorporating optically variable thin film flakes,” U.S. patent5,059,245 (22Oct.1991); OVI is a trademark of SICPA Holding S.A.

R. W. Phillips, T. Mayer, G. S. Ash, “Optically variable printing ink,” U.S. patent5,279,657 (18Jan.1994).

P. G. Coombs, R. W. Phillips, “Optically variable interference device with peak suppression and method,” U.S. patent5,214,530 (25May1993).

R. W. Phillips, “Optically variable films, pigments and inks,” in Optical Thin Films III: New Developments,” R. I. Seddon, ed., Proc. SPIE1323, 98–109 (1990).

Rolfe, J.

J. Rolfe, “Vacuum coatings for document security,” in Thirty-Fourth Annual Technical Conference Proceedings (Society of Vacuum Coaters, Washington, D.C., 1991), pp. 20–25.

J. Rolfe, “Optically variable devices for use on bank notes,” in Optical Security and Anticounterfeiting Systems, W. F. Fagan, ed., Proc. SPIE1210, 14–19 (1990).

Turner, A. F.

A. F. Turner, “Some current developments in multilayer optical films,” J. Phys. Rad. 11, 444–460 (1950).
[CrossRef]

Waldorf, A.

J. A. Dobrowolski, K. M. Baird, P. D. Carman, A. Waldorf, “Optical interference coatings for inhibiting of counterfeiting,” Opt. Acta 20, 925–937 (1973).
[CrossRef]

J. A. Dobrowolski, F. C. Ho, A. Waldorf, “Research on thin film anti-counterfeiting coatings at the National Research Council of Canada,” Appl. Opt.28, 2702–2717 (1989); J. A. Dobrowolski, “Optical thin film security devices,” in Optical Document Security, R. L. Van Renesse, ed. (Artech House, Boston, 1993), pp. 227–261.
[CrossRef]

J. Opt. Soc. Am. (1)

L. N. Hadley, D. M. Dennison, “Reflection and transmission interference filters,” J. Opt. Soc. Am. 37, 483–496 (1947).
[CrossRef]

J. Phys. Rad. (1)

A. F. Turner, “Some current developments in multilayer optical films,” J. Phys. Rad. 11, 444–460 (1950).
[CrossRef]

Opt. Acta (1)

J. A. Dobrowolski, K. M. Baird, P. D. Carman, A. Waldorf, “Optical interference coatings for inhibiting of counterfeiting,” Opt. Acta 20, 925–937 (1973).
[CrossRef]

Other (12)

J. A. Dobrowolski, F. C. Ho, A. Waldorf, “Research on thin film anti-counterfeiting coatings at the National Research Council of Canada,” Appl. Opt.28, 2702–2717 (1989); J. A. Dobrowolski, “Optical thin film security devices,” in Optical Document Security, R. L. Van Renesse, ed. (Artech House, Boston, 1993), pp. 227–261.
[CrossRef]

J. Rolfe, “Vacuum coatings for document security,” in Thirty-Fourth Annual Technical Conference Proceedings (Society of Vacuum Coaters, Washington, D.C., 1991), pp. 20–25.

J. Rolfe, “Optically variable devices for use on bank notes,” in Optical Security and Anticounterfeiting Systems, W. F. Fagan, ed., Proc. SPIE1210, 14–19 (1990).

R. W. Phillips, T. Mayer, G. Ash, “Ink incorporating optically variable thin film flakes,” U.S. patent5,059,245 (22Oct.1991); OVI is a trademark of SICPA Holding S.A.

The Currency Design Act: Hearing before the Subcommittee on Consumer Affairs and Coinage of the Committee on Banking, Finance and Urban Affairs, House of Representatives, on H.R.6005 (U.S. GPO, Washington, D.C., 24July1984).

“Counterfeit deterrent features for the next generation currency design,” Pub. NMAB-472 (Committee on Next-Generation Currency Design, National Materials Advisory Board, U.S. National Research Council, National Academy of Sciences, Washington, D.C., 1993).

Presented at the Druck und Papier Exhibition, Dusseldorf, Germany, 5–18 May 1995.

M. T. Nowak, T. E. Lewis, “Lithographic printing members for use with laser-discharge imaging,” U.S. patent5,379,698 (10Jan.1995).

R. W. Phillips, T. Mayer, G. S. Ash, “Method of making optical thin flakes and inks incorporating the same,” U.S. patent5,383,995 (24Jan.1995).

R. W. Phillips, T. Mayer, G. S. Ash, “Optically variable printing ink,” U.S. patent5,279,657 (18Jan.1994).

R. W. Phillips, “Optically variable films, pigments and inks,” in Optical Thin Films III: New Developments,” R. I. Seddon, ed., Proc. SPIE1323, 98–109 (1990).

P. G. Coombs, R. W. Phillips, “Optically variable interference device with peak suppression and method,” U.S. patent5,214,530 (25May1993).

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Figures (11)

Fig. 1
Fig. 1

Counterfeiting threat. $M, millions of dollars.

Fig. 2
Fig. 2

Color output devices in the U.S.

Fig. 3
Fig. 3

Cross section of metal–dielectric symmetrical color filter. A, absorber; D, dielectric; M, metal.

Fig. 4
Fig. 4

Conversion of thin-film coating into OVP/OVI™.

Fig. 5
Fig. 5

Reflectance as a function of wavelength and viewing angle. QW, quarter-wave.

Fig. 6
Fig. 6

Gamut of available colors for M/D/A designs (solid curve) and color as a function of angle for gold-to-green designs (dashed curves); a* and b* refer to color coordinates of the CIELAB color space (CIELAB indicates Commission Internationale de l’Eclairage’s chromaticity coordinates L* a* b*).

Fig. 7
Fig. 7

Colors at 10° under illuminant C produced from M/D/A designs as a function of quarter-wave optical thickness (a* and b* refer to color coordinates of the CIELAB color space).

Fig. 8
Fig. 8

Effect of n/k ratio of absorbing layer A on reflected color.

Fig. 9
Fig. 9

Chroma variation that is due to increasing absorber layer A thickness.

Fig. 10
Fig. 10

Reflectance spectrum for green-to-blue designs with and without IR and UV covert features.

Fig. 11
Fig. 11

$100 Bermuda genuine bank note and a color copy of the same note at (a) 0°, (b) 45° orientation.

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