WO2017139857A1 - Dispositif optique en relief pour produire des images en couleur non spectrales - Google Patents

Dispositif optique en relief pour produire des images en couleur non spectrales Download PDF

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Publication number
WO2017139857A1
WO2017139857A1 PCT/BG2016/000001 BG2016000001W WO2017139857A1 WO 2017139857 A1 WO2017139857 A1 WO 2017139857A1 BG 2016000001 W BG2016000001 W BG 2016000001W WO 2017139857 A1 WO2017139857 A1 WO 2017139857A1
Authority
WO
WIPO (PCT)
Prior art keywords
relief
patterns
optical device
colour
area
Prior art date
Application number
PCT/BG2016/000001
Other languages
English (en)
Inventor
Valentin Konstantinov MONOVSKI
Andrii Ivanovskyi
Georgi Ivanov STOILOV
Mario Rumenov DOBREV
Ihnat POHAN
Angel Georgiev BALDZHIEV
Evgeniy Anastasov LASKOV
Dimitar Antonov TONCHEV
Ivo Rumenov DELCHEV
Original Assignee
Demax - Holograms Ad
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Demax - Holograms Ad filed Critical Demax - Holograms Ad
Priority to PCT/BG2016/000001 priority Critical patent/WO2017139857A1/fr
Publication of WO2017139857A1 publication Critical patent/WO2017139857A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
    • B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
    • B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
    • B42D25/30—Identification or security features, e.g. for preventing forgery
    • B42D25/324—Reliefs
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
    • B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
    • B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
    • B42D25/30—Identification or security features, e.g. for preventing forgery
    • B42D25/328—Diffraction gratings; Holograms

Definitions

  • the invention relates to a relief optical device for creating non-spectral colour images and it will be applicable as a security feature to protect goods and documents against falsification and counterfeiting.
  • the iridescent colours of such images vary within the whole visible spectral range upon changing the observation and/or the incidence beam angle.
  • the spectral colours are saturated rainbow colours, with one, predominating wavelength in the spectrum, e.g. red (630nm), or green (550nm), or blue (450nm) etc., and a spectral image is the image, formed by means of one spectral colour.
  • the non-spectral colours are obtained as a result of mixing of two or more spectral colours, whereby an unsaturated colour, e.g. brown, violet, crimson etc.
  • a disadvantage of the indicated devices is their low diffraction efficiency, which in some cases amounts only to 6,4%.
  • the goal of the present invention is to create a relief optical device for displaying bright non-spectral images.
  • the task is solved by the proposed relief optical device for creating nonspectral colour images, including a set of areas of unspecified shape, filled with relief periodic diffraction patterns, having two levels of depth, whereby according to the invention the period of the patterns in these areas varies from an area to an area in random order within the range from 0,6um to 5 ⁇ , preferably with a step less than 0,050um, the angle of inclination of the pattern grooves varies from an area to an area in random order from 0 to 180 degrees with a step less than 0,7 degrees, the size of the areas is within the range from 5 ⁇ to SOum and the pattern relief depth, which preferably varies within the limits of 0,1 um - 0,8um, determines the colour hue of the non-spectral colours.
  • the relief periodic diffraction patterns have more than two discrete levels of depth, which forms a complicated pattern's groove profile shape.
  • the relief of the diffraction patterns is formed at the boundary of a metal and a transparent medium, preferably air or polymer material.
  • the relief of the diffraction patterns is formed at the boundary of two transparent media, having a different refractive indexes.
  • the proposed relief optical device object of the present invention, creates bright images of non-spectral colours.
  • Figure 1 depicts a schematic diagram of the relief optical device
  • Figure 2 The dependence J q (m/2) (Bessel function) of the intensity of the light, diffracted on a phase sinusoidal shape grating into particular order (q), on the phase modulation value (m);
  • Figure 3 Spectral dependence of the zero diffraction order for a binary grating at different depths;
  • Figure 4 Example of mixing red and blue colours in order to obtain magenta colour in the first order of diffraction from patterns with a period of 0,8um and l,16uin;
  • Figure 5 Example of mixing the complimentary colours: cyan (470nm) colour and yellow (570nm) colour in order to obtain white colour in the first order of diflraction;
  • Figure 6 Examples of patterns with different groove profiles
  • Figure 7 Spectral dependence of a pattern with different groove profiles
  • Figure 8 Example of obtaining rose colour in the zero order by means of changing the dimensional ratio between exposed and non-exposed parts of the pattern
  • Figure 9 Relief of a reflective optical device, formed on a polymer material and a metal coating laid on;
  • Figure 10 Relief of a transparent optical device, formed on a polymer material and a dielectric coating laid on.
  • the proposed relief optical device for creating non-spectral colour images includes a set of relief phase diffraction patterns 2 with two levels of depth, which are calculated and recorded for each particular case.
  • the relief phase diffraction patterns 2 are filled with areas 3 of unspecified shape.
  • the period T of the diffraction patterns 2 in these areas 3 varies from an area to an area in random order within the range from 0,6um to 5,0um, preferably with a step less than 0,050um
  • the angle of inclination of the grooves ⁇ of the patterns 2 varies from an area to an area in random order from 0 to 180 degrees with a step less than 0,7 degrees
  • the size of the areas 3 is within the range from 5 to 50um.
  • the theoretical diffraction efficiency of the phase pattern depends on the groove profile, reaching through sinusoidal groove profile 33,8 % /2/, and in case of rectangular profile - 41 % /3/. In this way the periodic structures allow to obtain much more brighter non-spectral colours, than in the case of using non-periodic structures.
  • the diffraction patterns have several diffraction orders.
  • Zero order the direction of the light distribution coincides with the beam passed over, or with the reflected beam.
  • the colour is formed on account of substracting of several spectral components.
  • the remaining diffraction orders (1,2,3.8) the non-spectral colour is formed due to the superposition of light from different patterns.
  • Such parameters like pattern space period, relief profile and groove width-to-period ratio are used in the process control of the spectral pattern features.
  • the intensity of the light is proportional to the square of the Bessel function of the relevant phase modulation .
  • This dependence is shown schematically in Figure 2. If the phase modulation corresponds to the maximum of the diffraction efficiency in the q-th order for a definite wavelength of light, the phase modulation will not be optimal for the other wavelengths and the light with mis wavelength will be redistributed to other diffraction orders. Thereby, the diffraction pattern can operate as a spectral filter.
  • a reflective metal pattern is considered for all examples below, unless otherwise indicated.
  • Figure 3 depicts an example of a zero order spectral dependence of diffraction for a pattern with a period 0,8um at a different modulation depth.
  • FIG. 4 illustrates an example of mixing red and blue colours, in order to obtain a magenta colour in the first diffraction order of a pattern with a period of 0,80um and l,16um.
  • the spectral characteristics of the pattern also depends on the groove profile d.
  • Figure 6 shows patterns with different profile of the groove d: binary 4, sinusoidal 5 and stepped 6, and Figure 7 - the relevant spectral characteristics of the zero diffraction order 7, 8 and 9. It can be seen, that in the case of binary profile, the zero order is coloured in red, in the case of sinusoidal profile, the colour will be dark magenta, and in the case of stepped profile - magenta.
  • the ratio between the exposed and the non-exposed part of the pattern can be changed.
  • a set of patterns with a different inclination angle of the grooves ⁇ is necessary to be applied.
  • the average diameter of the human eye pupil is about 3 mm. People usually look at a hologram at a distance of 250 mm. Therefore, the step of changing the angle of inclination ⁇ of the pattern shall not be larger than 0,7 degrees. Otherwise, a sampling of the image will be seen - it will "flicker" upon changing the observation angle.
  • the relief optical device consists of raster text images of crimson colour and white colour background.
  • the pixel size is selected to be lOum, because this size provides graphics at high resolution and pixels are not visible to the naked eye.
  • a topology consisting of periodic patterns, is exposed by means of electron-beam lithography on a silicon wafer, coated with resist with thickness of lum. Patterns with a period of 0,7um and l,0um are exposed in the magenta areas, and patterns with 0,75um and 0,90um are exposed in the white areas.
  • the inclination angle of the pattern varies from a pixel to a pixel in random order. The range of changes is ⁇ 10° with a step of 0,3°.
  • Relief diffraction patterns are obtained after resist developing.
  • Blue colour and red colour are mixed upon diffraction of patterns with periods 0,7um and l,0um in the direction of the first diffraction order.
  • a magenya colour is obtained as a result thereof, and a white colour is obtained upon mixing light blue colour and yellow colour of patterns with periods 0,75pm and 0,90 um.
  • a thin conductive silver layer with thickness of 0,050um is deposited on its surface by means of vacuum thermal evaporation.
  • a nickel copy is produced by use of electroplating.
  • the obtained nickel copy is used for stamping on a polymer material, e.g. polycarbonate, to reproduce the optical device on the polymer material.
  • the optical device, obtained in this way, is covered by an aluminum layer 10 with thickness of 0,1 um, in order to increase its reflectivity and the brightness of the device ( Figure 9) . In that case, the device can only be seen upon reflection.
  • a dielectric material with high refractive index - zinc sulfide 11 is deposited, in order to increase the relief reflectivity ( Figure 10). After applying adhesive and cutting to final shape, the optical device is applied on the object and it is used as a sign for its authenticity.
  • Hie relief optical device consists of raster text images of red colour and yellow colour background.
  • the pixel size is selected to be lOum, because this size provides graphics at high resolution and pixels are not visible to the naked eye.
  • a topology consisting of periodic patterns with a period, which vary from a pixel to a pixel in random order, is exposed by means of electron-beam lithography on a silicon wafer, coated with resist of lum thickness.
  • the range of period changes is from lum to 3um with a step of 0.05um.
  • the inclination angle of the pattern varies from a pixel to a pixel in random order.
  • the range of angle changes is ⁇ 10° with a step of 0,3°.
  • the dose is selected in such a way, that the relief height is 0,25um in the red areas, and 0,35um in the yellow areas. A red/yellow image will be observed at a close to the zero order of the diffraction .

Landscapes

  • Diffracting Gratings Or Hologram Optical Elements (AREA)

Abstract

La présente invention concerne un dispositif optique en relief pour créer des images en couleur non spectrales. Le dispositif optique en relief comprend un ensemble de zones de forme non spécifiée, remplies de motifs de diffraction périodiques en relief ayant deux niveaux de profondeur, de sorte que, selon l'invention, la période des motifs (2) dans les zones (3) varient d'une zone à une autre dans un ordre aléatoire dans la plage de 0,6 µm à 5 µm, de préférence avec un pas inférieur à 0,050 µm, l'angle d'inclinaison des rainures (φ) des motifs varie d'une zone à une autre dans un ordre aléatoire de 0 à 180 degrés avec un pas inférieur à 0,7 degré, la taille des zones (3) est dans la plage de 5 µm à 50 µm et la profondeur du relief (h) des motifs (2), qui varie de préférence dans les limites de 0,1 à 0,8 µm, détermine la teinte de couleur des couleurs non spectrales.
PCT/BG2016/000001 2016-01-15 2016-01-15 Dispositif optique en relief pour produire des images en couleur non spectrales WO2017139857A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/BG2016/000001 WO2017139857A1 (fr) 2016-01-15 2016-01-15 Dispositif optique en relief pour produire des images en couleur non spectrales

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/BG2016/000001 WO2017139857A1 (fr) 2016-01-15 2016-01-15 Dispositif optique en relief pour produire des images en couleur non spectrales

Publications (1)

Publication Number Publication Date
WO2017139857A1 true WO2017139857A1 (fr) 2017-08-24

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111032364A (zh) * 2017-10-04 2020-04-17 捷德货币技术有限责任公司 光学可变的透视防伪元件和数据载体

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014033324A2 (fr) * 2012-09-03 2014-03-06 Ovd Kinegram Ag Élément de sécurité et document de sécurité
DE102013105246A1 (de) * 2013-05-22 2014-11-27 Leonhard Kurz Stiftung & Co. Kg Optisch variables Element

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014033324A2 (fr) * 2012-09-03 2014-03-06 Ovd Kinegram Ag Élément de sécurité et document de sécurité
DE102013105246A1 (de) * 2013-05-22 2014-11-27 Leonhard Kurz Stiftung & Co. Kg Optisch variables Element

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111032364A (zh) * 2017-10-04 2020-04-17 捷德货币技术有限责任公司 光学可变的透视防伪元件和数据载体
CN111032364B (zh) * 2017-10-04 2021-02-02 捷德货币技术有限责任公司 光学可变的透视防伪元件和数据载体

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