WO2020187287A1 - 光学防伪元件及光学防伪产品 - Google Patents

光学防伪元件及光学防伪产品 Download PDF

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Publication number
WO2020187287A1
WO2020187287A1 PCT/CN2020/080181 CN2020080181W WO2020187287A1 WO 2020187287 A1 WO2020187287 A1 WO 2020187287A1 CN 2020080181 W CN2020080181 W CN 2020080181W WO 2020187287 A1 WO2020187287 A1 WO 2020187287A1
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Prior art keywords
micro
relief structure
area
counterfeiting
relief
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PCT/CN2020/080181
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English (en)
French (fr)
Inventor
张宝利
胡春华
王晓利
朱军
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中钞特种防伪科技有限公司
中国印钞造币总公司
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Publication of WO2020187287A1 publication Critical patent/WO2020187287A1/zh

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    • 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
    • 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
    • B42D25/40—Manufacture
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B44—DECORATIVE ARTS
    • B44F—SPECIAL DESIGNS OR PICTURES
    • B44F1/00—Designs or pictures characterised by special or unusual light effects
    • B44F1/08—Designs or pictures characterised by special or unusual light effects characterised by colour effects

Definitions

  • the invention relates to the field of optical anti-counterfeiting, in particular to an optical anti-counterfeiting element and an optical anti-counterfeiting product.
  • anti-counterfeiting technologies for diffractive optically variable images are widely used in various high-security or high-value-added printed materials such as banknotes, cards, and product packaging. And achieved very good results.
  • large denomination Euro banknotes use diffractive light variable image hot stamping logos
  • small denominations use diffractive light variable image hot stamping wide strips
  • China 2005 version of Renminbi uses diffractive light variable image window security lines except for one yuan side.
  • the diffractive optically variable image used for anti-counterfeiting is a grating with a relief structure.
  • the illuminating light such as natural light
  • the reproduced image is formed by using its 1st (or -1) diffracted light to achieve Public anti-counterfeiting features such as eye-catching dynamics, three-dimensionality, and color changes.
  • Chinese patent application CN104249597A discloses an optical anti-counterfeiting element, the microstructure contained in it is defined as when a light beam is irradiated at an angle of incidence, light of a wavelength or wavelength range in the light beam interferes in the direction of transmitted light or reflected light Constructive.
  • the optical anti-counterfeiting element is different from the above-mentioned diffracted light-changing image, avoiding the interference of diffracted light with the rainbow characteristic of uncertain colors, but using the easy-to-describe color stable light formed by the interference mechanism, so that the optical anti-counterfeiting element
  • the area covered by the micro-relief structure forms a specific pattern that is easy to identify and difficult to forge.
  • the optical anti-counterfeiting element needs to be further improved. Attributes that are easy to identify and difficult to forge.
  • Multi-layer structure coating technology In order to prevent counterfeiting of various types of high-security or high-value-added printed materials such as banknotes, certificates and product packaging, multi-layer structure coating technology is widely used. Multi-layer structure coating technology can present various color characteristics or different colors under different viewing angles, and cannot be imitated or copied by electronic equipment such as cameras, scanners, printers, etc., so it has a high anti-counterfeiting ability. However, simply using multi-layer coating technology can no longer meet the needs of the anti-counterfeiting field.
  • the purpose of the embodiments of the present invention is to provide an optical anti-counterfeiting element and an optical anti-counterfeiting product that are more reliable and easy to identify and difficult to forge.
  • the present invention provides an optical anti-counterfeiting element, the optical anti-counterfeiting element comprising: a base layer; a color functional layer located on the base layer; a first micro-relief covering at least a part of a first area of the color functional layer Structure, the first area is a partial area of the color functional layer; and the plating layer only covers the surface of the first micro-relief structure; the first micro-relief structure is defined as when the light beam is irradiated at an incident angle In the first micro-relief structure, light of a wavelength or wavelength range in the light beam interferes constructively in the direction of the reflected light.
  • the present invention also provides an optical anti-counterfeiting product, including the above-mentioned optical anti-counterfeiting element.
  • optical anti-counterfeiting feature that is not only clearly different from the diffractive optically variable image anti-counterfeiting technology, but also different from the simple multilayer structure coating.
  • the sample containing this feature provides different observations in the first micro-relief structure area.
  • the angles respectively present two complementary color features, while the remaining areas provide the color features of the color function layer.
  • the sharp contrast and contrast can be achieved by separately defining the structural parameters of the first micro-relief structure and the color functional layer, and a unique optical anti-counterfeiting element with easy identification and difficult to forge characteristics can be formed.
  • FIGS 1a to 1b show an optical security element according to an embodiment of the present invention
  • 1c to 1d show schematic diagrams of the cross-sectional shape of the relief unit of the micro-relief structure
  • FIGS. 2a to 2b show an optical security element according to an embodiment of the present invention
  • 3a to 3c show an optical security element according to an embodiment of the present invention
  • FIG. 4a to 4f show schematic diagrams of the manufacturing process of an optical anti-counterfeiting element according to an embodiment of the present invention
  • FIG. 5a to 5c show schematic top views of an optical security element according to an embodiment of the present invention.
  • FIG. 6a to 6b show schematic top views of an optical anti-counterfeiting element according to an embodiment of the present invention
  • Figure 7 shows a schematic cross-sectional view of an optical security element according to an embodiment of the present invention.
  • Fig. 8 shows a schematic cross-sectional view of an anti-counterfeiting element according to an embodiment of the present invention.
  • the “feature size” mentioned in the present invention refers to the average value of the lowest and highest surface heights in the micro-relief structure to divide the surface to form the size of the contour surrounding the convex or concave part in any direction.
  • Micro-relief structure refers to the uneven microstructure formed on a two-dimensional surface as needed.
  • the "relief unit” refers to a single convex or concave part formed by dividing the surface into a single convex or concave part in the micro-relief structure by taking the average of the lowest and highest points on the surface of the micro-relief structure, and its characteristic size is on the order of microns.
  • the "depth d of the micro-relief structure” refers to the height difference between the highest point and the lowest point of the surface height in the micro-relief structure.
  • Fig. 1a shows an optical security element 1 according to an embodiment of the present invention.
  • 1a is a schematic cross-sectional view of an anti-counterfeiting element 1 according to an embodiment of the present invention.
  • the optical anti-counterfeiting element 1 includes a base layer 101, a color function layer 103 on the base layer 101, and an area B on the color function layer 103 and covering the color function layer 103 At least a part of the micro-relief structure 102, and the plating layer 104 only covering the micro-relief structure 102.
  • the area B is a partial area of the area of the color functional layer 103, and the area of the color functional layer 103 except for the area B is called area A.
  • the micro-relief structure 102 is defined as when a light beam illuminates the micro-relief structure 102 at an incident angle, light of a wavelength or wavelength range in the beam interferes constructively in the direction of the reflected light, and the color functional layer 103 and the micro-relief structure 102 can provide optical features with different color features.
  • the color functional layer 103 may be an interference type multilayer film structure, which forms a Fabry-Perot resonant cavity, which has a selective effect on the incident white light, so that the emitted light only contains certain These wavelengths present a specific color; when the incident angle changes, the relative optical path changes, and the interference waveband also changes, so that the color presented to the observer in the direction of the exit angle also changes, thereby forming a light change effect.
  • the interference-type multilayer film structure may include any one of the following structures: (1) A plating layer formed by stacking an absorption layer, a low refractive index medium layer, and a reflective layer in sequence, wherein the reflective layer is the same as the surface of the base layer 101.
  • the material of the above-mentioned reflective layer can be a material with high reflectivity, such as gold, silver, copper, aluminum, zinc, nickel, titanium, etc.
  • the material requirement of the above-mentioned absorbing layer is that its refractive index and Materials with close absorption coefficients, for example, can be semi-metallic materials (such as silicon, germanium, etc.), or metal materials or their alloys (such as chromium, copper, nickel, nickel-chromium alloys, etc.); the aforementioned low refractive index dielectric layer
  • the refractive index is less than 1.7, such as magnesium fluoride, silicon dioxide, cryolite, etc.
  • the refractive index of the above-mentioned high refractive index dielectric layer is greater than or equal to 1.7, such as ZnS, TiN, TiO 2 , TiO, Ti 2 O 3.
  • the interference type multilayer film structure can be obtained by physical or chemical vapor deposition methods such as thermal evaporation, electron beam evaporation, and magnetron sputtering.
  • the color functional layer 103 may be an absorbing structure, where the absorbing structure may be one or a combination of ink, pigment, and dye.
  • the OVI optically variable ink produced by Sicpa can be used, for example.
  • the color functional layer 103 may also be a liquid crystal light variable layer.
  • a cholesteric liquid crystal material can be used to realize the color function layer 103, so that color characteristics such as green to blue, red to green, etc., which are changed with the observation angle, can be realized.
  • the liquid crystal light variable layer can be mass-produced by coating, printing and other methods.
  • the color functional layer 103 can also be a multi-layer co-extruded optically variable film.
  • the multi-layer co-extruded optical variable film can be directly used as the base layer 101.
  • an x-y-z spatial coordinate system is defined.
  • the micro-relief structure 102 may be located on the xoy plane (or a plane parallel to the xoy plane), and the feature size in the x-axis and y-axis directions may be, for example, 0.3 ⁇ m-6 ⁇ m, preferably 0.6 ⁇ m-3 ⁇ m, And the pattern of the micro-relief structure 102 (ie, the relief units of the micro-relief structure) may be randomly or pseudo-randomly distributed.
  • the raised portion of the micro-relief structure 102 may account for 20%-80% of the total area of the micro-relief structure 102, preferably 35%-65%.
  • the cross-sectional shape of the relief unit of the micro-relief structure 102 may be sinusoidal.
  • the cross-sectional shape of the relief unit of the micro-relief structure 102 may be sawtooth.
  • the cross-sectional shape of the relief unit of the micro-relief structure 102 may be a rectangle.
  • the cross-sectional shape of the relief unit of the micro-relief structure 102 may also be other shapes.
  • the depth d of the micro-relief structure 102 can meet the following conditions, that is, when natural light (white light) illuminates the micro-relief structure 102 at an incident angle ⁇ , after the light beam passes through the micro-relief structure 102, light with a wavelength of ⁇ or a wavelength range is in the reflected light direction
  • the upper interference is constructive, so that when the optical security element 1 is viewed in the direction of reflected light, it presents a first color, and when the optical security element 1 is viewed in the direction of scattered light, it presents a second color (as shown in Fig. 1a).
  • the depth d of the micro-relief structure 102 is usually between 100 nm and 5 ⁇ m, preferably 200 nm to 3 ⁇ m.
  • the depth d can be determined by the following method.
  • ⁇ g is a function of the depth d, the design wavelength ⁇ , the groove type of the micro-relief structure 102, the material refractive index distribution n, and the position (x, y); 2 Perform Fourier transform on the complex amplitude transmittance ⁇ g ; 3 find the maximum condition of the reflected light with wavelength ⁇ (ie zero-order diffracted light); 4 calculate the depth d of the micro-relief structure 102 according to the maximum reflected light condition.
  • the micro-relief structure can be made into a master by laser etching, electron beam etching, ion etching, etc., and then copied onto the base layer by processes such as electroforming, molding, and UV replication.
  • a more commonly used process is to coat an imaging layer on the surface of the base layer, and copy the micro-relief structure on the imaging layer, with the purpose of improving the quality and efficiency of copying the micro-relief structure.
  • the material constituting the micro-relief structure can be, for example, ZnS, ZnO, Ta 2 O 5 , SnO 2 , Nb 2 O 5 , HfO 2 , In 2 O 3 , CeO 2 , Dy 2 O 3 , Bi 2 O 3 , MgF 2 , Al 2 O 3 , AlF 3 , CaF 2 , SiO 2 , SrF 2 , YbF 3 , NaF, Na 3 AlF 6 , PET, PVC, PE, polyester glue, or polyurethane glue, etc.
  • the base layer can be, for example, a transparent material such as PET, PVC, or PE, or a carrier such as paper, printed matter, and packaging.
  • the substrate may also be a carrier in the processing process, and be peeled off during later application.
  • the plating layer 104 may be, for example, a metal reflective layer.
  • the material constituting the metal reflective layer may include, for example, gold, silver, copper, iron, tin, nickel, chromium, aluminum, zinc, titanium and alloys thereof, and the thickness may be greater than 5 nm, preferably greater than 10 nm.
  • the coating layer 104 can be obtained by physical or chemical vapor deposition methods such as thermal evaporation, electron beam evaporation, magnetron sputtering, and the like.
  • the function of the plating layer 104 is to provide a reflection function for the micro-relief structure 102, thereby enhancing the efficiency of reflected light.
  • the effect is the superposition of the color characteristic and the color characteristic provided by the micro-relief structure 102.
  • optical anti-counterfeiting features of the respective parts of the area A and the area B in the optical anti-counterfeiting element 1 shown in FIGS. 1a to 1b will be described below.
  • the optical characteristics of the area A in the optical anti-counterfeiting element 1 depend on the choice of the color functional layer 103 in the above preferred solutions. There are two possibilities. One is to provide a single color that is constant at various viewing angles. , The other is to provide the feature that the color changes when the viewing angle changes.
  • the part where area B is located can provide color changes and complementary color characteristics in the direction of reflected light and scattered light, which is not available in the color functional layer 103 of the part where area A is located;
  • the color characteristics of the part where area B is located depends on Because of the micro-relief structure 102's morphology, refractive index n, its parameter distribution on the xoy plane, and the structure depth d, the color or color provided by the part where the area B is located and the part where the area A is located can be changed by calculation and design parameters. The characteristics are different, and even strong contrast and contrast are formed, so that the optical anti-counterfeiting element of the present invention has stronger uniqueness, and achieves
  • Color functional layer select the color functional layer 103 as red nano ink.
  • Optical anti-counterfeiting features when viewed in the direction of reflected light, the part where area A is located and the part where area B is located tend to be red; when viewed in the direction of scattered light, the part where area A is located is red, and the part where area B is located is blue-green.
  • Color function layer select the color function layer 103 as green metallic ink.
  • Optical anti-counterfeiting features when viewed in the direction of reflected light, the part where area A is located is metallic green, and the part where area B is located tends to red; when viewed in the direction of scattered light, the part where area A and area B are located both tend to green .
  • Color functional layer Select the color functional layer 103 to be OVI ink produced by Sicpa Company.
  • the OVI ink is green when viewed along the z-axis, and blue when viewed at an angle of 45° to the z-axis.
  • Optical anti-counterfeiting features when viewed in the direction of reflected light, both the area where the area A is located and the area where the area B is located tend to be green; during oblique observation, the area where the area A is located turns green, and the portion where the area B located turns to magenta.
  • Color functional layer Select the color functional layer 103 as an interference type multilayer film structure that sequentially contains Al (thickness: 40nm)/SiO2 (thickness: 370nm)/Cr (thickness: 5nm), which is an interference-type multilayer structure of this parameter
  • the film is golden yellow when viewed from the front and green when viewed obliquely.
  • Optical anti-counterfeiting features when viewed in the reflected light direction, the part where area A is located is golden yellow, and the part where area B is located are all green; during oblique observation, the part where area A is located turns green, and the part where area B turns to magenta .
  • the color functional layer 103 is selected to be a cholesteric liquid crystal light variable film produced by Rolic, Switzerland, which adopts red-green characteristics, that is, red when viewed from the front and green when viewed obliquely.
  • Optical anti-counterfeiting features when viewed in the direction of reflected light, the area where the area A is located is red, and the area where the area B is located is yellow; during oblique observation, the area where the area A is located turns green, and the portion where the area B located turns blue.
  • the color functional layer 103 is selected as a multi-layer co-extruded optically variable film produced by 3M Company, which adopts a green-blue characteristic, that is, green when viewed from the front and blue when viewed obliquely.
  • Optical anti-counterfeiting features the part where area A is observed in the reflected light direction is green, and the part where area B is yellow; during oblique observation, the part where area A is located and the part where area B is located tend to blue.
  • the color functional layer 103 and the micro-relief structure are configured so that the part where the area A is located and the part where the area B is located have different colors or color change characteristics. It should be noted that although there is a situation where the color of the part where the area A is located and the part where the area B is located are the same at a specific observation angle, objectively, there are still differences in the absorption or reflection spectra of the two in practice, but this is essentially The above does not affect the anti-counterfeiting performance and quality of the optical anti-counterfeiting element 1 of the present invention, and the difference can help attract and help users to recognize the pattern of the part where the area A is located or the part where the area B is located.
  • Figures 2a and 2b show a reflective optical security element 2 according to an embodiment of the present invention.
  • an optical anti-counterfeiting element 2 is provided, including a base layer 201, a color functional layer 203 on the base layer 201, a micro-relief on the color functional layer 203 and covering at least a part of the area B of the color functional layer 203
  • the structure 202, and the plating layer 204 only covering the micro-relief structure 202.
  • the area B is a partial area of the area of the color functional layer 203, and the area of the color functional layer 203 except for the area B is called area A.
  • the micro-relief structure 202 is defined as when a light beam illuminates the micro-relief structure 202 at an incident angle, light of a wavelength or wavelength range in the light beam interferes constructively in the direction of the reflected light, and the color functional layer 203 and the micro-relief structure 202 can provide optical features with different color features.
  • the micro-relief structure 202 can be located on the xoy plane (or a plane parallel to the xoy plane), and the feature size in the x-axis direction can be greater than 6 ⁇ m, preferably greater than 10 ⁇ m, so that the micro-relief structure 202 is in this direction Without diffraction effect, the feature size of the micro-relief structure 202 in the y-axis direction may be 0.3 ⁇ m-6 ⁇ m, preferably 0.6 ⁇ m-3 ⁇ m, and the pattern may be randomly or pseudo-randomly distributed.
  • the protruding portion of the micro-relief structure 202 may occupy 20%-80% of the total area of the micro-relief structure 202, preferably 35%-65%.
  • Figure 2b is a schematic cross-sectional view of an anti-counterfeiting element in a Yoz plane (or a plane parallel to the Yoz plane) according to an embodiment of the present invention. As shown in FIG. 2b, the cross-sectional shape of the relief unit of the micro-relief structure 202 may be sinusoidal. However, those skilled in the art can understand that the cross-sectional shape of the relief unit of the micro-relief structure 202 may be sawtooth, rectangular or other shapes.
  • the depth d of the micro-relief structure 202 can meet the following conditions, that is, when natural light (white light) illuminates the micro-relief structure 202 at an incident angle ⁇ , after the light beam passes through the micro-relief structure 202, light with a wavelength of ⁇ or a wavelength range is in the reflected light direction The upper interference is constructive, so that the optical anti-counterfeiting element 2 presents the first color in the direction of the reflected light.
  • the optical anti-counterfeiting element 2 presents a second color in the direction of the scattered light in the Yoz plane (or a plane parallel to the Yoz plane).
  • the depth d of the micro-relief structure 202 may be 100 nm-5 ⁇ m, preferably 200 nm-3 ⁇ m.
  • the method for determining the depth d is the same as the foregoing embodiment, and will not be repeated here.
  • other features and beneficial effects of the optical anti-counterfeiting element 2 are the same as those of the above-mentioned optical anti-counterfeiting element 1, and will not be repeated here.
  • Figures 3a-3c show a reflective optical security element 3 according to an embodiment of the present invention.
  • an optical anti-counterfeiting element 3 is provided, including a base layer 301, a color functional layer 303 located on the base layer 301, a micro-relief on the color functional layer 303 and covering at least a part of the area B of the color functional layer 303 The structure 302, and the plating layer 304 only covering the microstructure.
  • the area B is a partial area of the area of the color functional layer 303, and the area of the color functional layer 303 except for the area B is called area A.
  • the micro-relief structure 302 is defined as when a light beam illuminates the micro-relief structure 302 at an incident angle, light of a wavelength or wavelength range in the light beam interferes constructively in the direction of the reflected light, and the color functional layer 303 and the micro-relief structure 302 can provide optical features with different color features.
  • the micro-relief structure 302 can be located on the xoy plane (or a plane parallel to the xoy plane), the feature size in the y-axis direction can be, for example, 0.3 ⁇ m-6 ⁇ m, preferably 0.6 ⁇ m-3 ⁇ m, and the pattern can be Randomly or pseudo-randomly distributed, the feature size in the x-axis direction may be 0.3 ⁇ m-6 ⁇ m, preferably 0.6 ⁇ m-3 ⁇ m, and the pattern may be, for example, a periodic structure.
  • the protruding part of the micro-relief structure 302 may occupy 20%-80% of the total area of the micro-relief structure 302, preferably 35%-65%.
  • Figure 3b is a schematic cross-sectional view of the anti-counterfeiting element 3 in the Yoz plane (or a plane parallel to the Yoz plane) according to an embodiment of the present invention
  • Figure 3c is the anti-counterfeiting element 3 in accordance with an embodiment of the present invention in the xoz plane (or with xoz plane parallel plane) cross-sectional schematic diagram.
  • the cross-sectional shape of the relief unit of the micro-relief structure 302 may be sinusoidal, sawtooth, rectangular or other shapes.
  • the depth d of the micro-relief structure 302 can meet the following conditions, that is, when natural light (white light) illuminates the micro-relief structure 302 at an incident angle ⁇ , after the light beam passes through the micro-relief structure 302, light with a wavelength of ⁇ (or a wavelength range) is reflected The light direction interferes constructively, so that the optical security element 3 observes the first color in the reflected light direction.
  • the optical security element 3 presents a second color in the direction of the scattered light in the Yoz plane (or a plane parallel to the Yoz plane); if the light beam is in the xoz plane ( Or a plane parallel to the xoz plane), the optical anti-counterfeiting element 3 observes the color of the +1 or -1 order diffracted light of the grating in the diffracted light direction and changes with the observation angle.
  • the depth d of the micro-relief structure 302 is generally between 100 nm and 5 ⁇ m, preferably 200 nm to 3 ⁇ m.
  • the method for determining the depth d is the same as that in the first embodiment, and will not be repeated here.
  • other features and beneficial effects of the optical anti-counterfeiting element 3 are the same as those of the above-mentioned optical anti-counterfeiting element 1, and will not be repeated here.
  • FIGS. 4a-f the manufacturing process of the optical anti-counterfeiting element 1 in the embodiment of FIG. 1 will be illustrated by using FIGS. 4a-f.
  • Step 1 As shown in Figure 4a, an optical original plate with a micro-relief structure 102 is produced by a laser etching process, and electroformed into a metal plate roll. On the lower surface of the base layer 1011, the micro embossing process on the metal plate roll The relief structure is replicated as the micro relief structure 1021, and the refractive index of the material forming the micro relief structure 1021 can be around 1.48.
  • Step 2 As shown in FIG. 4b, a plating layer 104 is vapor-deposited on the surface of the micro-relief structure 1021, and the plating layer may be a 40 nm thick metal aluminum film reflective layer.
  • Step 3 As shown in FIG. 4c, a protective layer 105 is coated on the surface of the plating layer 104 in the area B by printing.
  • the protective layer 105 may be an acrylic material, and its refractive index may be around 1.48.
  • Step 4 As shown in Figure 4d, immerse the structure shown in Figure 4c in a solution that can dissolve the plating layer 104 but cannot dissolve the protective layer 105.
  • the solution may be sodium hydroxide with a concentration of about 10% at 40°C.
  • Step 5 As shown in Figure 4e, the color functional layer 103 is vapor-deposited on the upper surface of the base layer 101, for example, an interference type multilayer film, that is, Al (thickness 40nm)/SiO 2 (thickness 370nm)/ Cr (with a thickness of 5 nm), where the aluminum layer is in contact with the base layer 101.
  • the interference type multilayer film of this parameter has the characteristics of being golden yellow when viewed from the front and green when viewed obliquely.
  • Step 6 As shown in Figure 4f, the structures shown in Figure 4d and Figure 4e are bonded together with a composite adhesive with adhesive properties.
  • the refractive index of the composite adhesive is about 1.48, which is the same as 1021 and 105.
  • the optical performance is the same, so the composite glue and 1021 and 105 are unified as 102 in FIG. 4f.
  • optical anti-counterfeiting element 1 described in FIG. 1.
  • the production process of the optical anti-counterfeiting elements 2 and 3 is similar to this, and will not be repeated here.
  • Figure 5a corresponds to the top view image of the micro-relief structure 1021 with the plating layer 104 shown in Figure 4b on the xoy plane or a plane parallel to it, where different areas C and D are filled with different parameters (for example, the micro-relief structure in the plane Arrangement, structure depth, morphology and other parameters) micro-relief structure.
  • regions C and D can also be further divided into macroscopic or microscopic sub-regions according to design requirements to fill micro-relief structures with different parameters.
  • Figure 5b corresponds to the micro-relief structure 1021 with the protective layer 105 applied in Figure 4c. Since the protective layer 105 and the micro-relief structure 1021 are processed in separate steps, the projection of the two on the xoy plane will appear objectively
  • the inevitable misalignment error is usually more than 0.1 mm.
  • the area covered by the protective layer 105 is to cover the area D of the micro-relief structure 1021 without error as the initial design goal, it actually covers the area B.
  • the uncertainty of the reserved area of the plating layer 104 is caused, which further causes the uncertainty of the position of the area A and the area B in the optical anti-counterfeiting element 1.
  • the image distortion and incompleteness shown in Fig. 5c inevitably appear in practical applications.
  • Figures 6a-b show an optimized embodiment for the image distortion and incomplete problems exposed in the embodiment of Figures 5a-c.
  • Figure 6a shows a top view image of the micro-relief structure 1021 with the plating layer 104 on the xoy plane or a plane parallel to it, in which different areas C and D are filled with different parameters (such as the arrangement of the micro-relief structure in the plane, structure Depth, topography, etc.) micro-relief structure.
  • Fig. 6b corresponds to the micro-relief structure 1021 to which the protective layer 105 is applied shown in Fig. 4c.
  • the coverage area of the protective layer 105 is slightly larger than the target coverage area D, and the excess size is, for example, at least 0.1 mm to ensure that the misalignment error is included. Therefore, the target coverage area D can still be fully included in the actual coverage area B even in the presence of the misalignment error, thereby ensuring the integrity of the image.
  • this optimized structure brings another problem, that is, the plating layer 104 protected by the protective layer 105 covers the area outside the design target area D, that is, a part of the area C, which solves the image integrity and causes image redundancy. More.
  • the redundant plating layer 104 will affect the area and integrity of the region A where the color functional layer 103 is located.
  • neither the optical anti-counterfeiting element 1 described in FIG. 5 nor FIG. 6 can achieve a high-definition hollow pattern of the plating layer 104. This is limited by the printing process of the protective layer 105, and the line fineness in the existing printing process cannot exceed the stroke width of 0.01 mm.
  • the present invention further provides another optical anti-counterfeiting element, which is described below with reference to FIG. 7.
  • the optical anti-counterfeiting element 7 includes a base layer 701, a color functional layer 703 located on the base layer 701, and an area B located on the color functional layer 703 and covering the color functional layer 703 At least a part of the micro-relief structure 702, the micro-relief structure 7022 of the area A covering the color functional layer 703, the area A and the area B do not overlap, and only the plating layer 704 covering the micro-relief structure 702.
  • the ratio of the surface area to the apparent area of the micro-relief structure layer 702 is smaller than the ratio of the surface area to the apparent area of the micro-relief structure 7022. That is, the area covered by the plating layer 704 is determined by the difference in the ratio of the surface area to the apparent area of the micro-relief structure 702 and the micro-relief structure 7022.
  • the micro-relief structure 702 and the micro-relief structure 7022 are composed of surface undulation structures whose height on the xoy plane fluctuates with the position distribution. Compared with a flat surface, the surface undulation structure is more than a flat surface. The surface area is larger, and the surface area is positively correlated with the degree of undulation of the surface undulating structure.
  • the term "apparent area” refers to the area of the orthographic projection of a certain area in a plane parallel to the area, that is, the area ignoring the undulating structure in the area; the term “surface area” refers to the area State the actual area of the undulating structure in a certain area. Obviously, the ratio of the surface area of the certain area to its apparent area is a value not less than 1.
  • the surface microstructure 7022 can be selected within the following range: one or more continuous curved structures, one or more rectangular structures, one or more sawtooth prisms, or their splicing or combination.
  • the continuous curved structure may be a splicing or combination of one or more structures of a micro lens structure, a sinusoidal structure, an elliptical structure, a hyperboloid structure, a parabolic structure, and the like.
  • the microlens structure may be a refractive microlens, a diffractive microlens, or a splicing or combination thereof, wherein the refractive microlens may include a spherical microlens, an ellipsoidal microlens, a cylindrical microlens or other arbitrary geometric shapes based on Geometrical optics microlenses, diffractive microlenses include harmonic diffractive microlenses, plane diffractive microlenses, Fresnel zone plates, etc.
  • the specific arrangement of the above structures may be periodic, partially periodic, aperiodic, random, or a combination thereof.
  • the feature size of the micro-relief structure 702 in the x-axis and y-axis directions is 2.8 ⁇ m
  • the cross-sectional shape of the micro-relief structure 702 is sinusoidal
  • the micro-relief structure 7022 is a sinusoidal grating with an arrangement period of 350 nm and a depth of 300 nm.
  • the processing process of the optical security element 7 is as follows:
  • Step 1 Use the laser etching process to make an optical original plate containing the micro-relief structure 702 and the micro-relief structure 7022, and electroform it into a metal plate roller, and copy the micro-relief structure on the metal plate roller using a molding process on the lower surface of a base layer
  • the refractive index of the material forming the micro-relief structure may be around 1.48.
  • Step 2 Evaporate a plating layer 704 on the surface of the micro-relief structure 702, and the plating layer may be a 50 nm thick metal aluminum film reflective layer.
  • Step 3 Immerse the structure formed in Step 2 in a solution capable of dissolving the plating layer 704.
  • the solution may be an aqueous solution of sodium hydroxide with a concentration of about 5% at 40°C.
  • the plating layer on the surface of the micro-relief structure 7022 (for example, The metal aluminum film (reflective layer) is not dissolved until the coating layer 704 accurately covers the micro-relief structure 702, thereby forming a precise hollow pattern.
  • Step 4 Vapor-deposit the color functional layer 703 on the upper surface of the other base layer 701, for example, an interference type multilayer film, that is, sequentially vapor-deposit Al (thickness of 40nm)/SiO 2 (thickness of 370nm)/Cr (thickness of 5nm), where the aluminum layer is in contact with the base layer 701.
  • an interference type multilayer film that is, sequentially vapor-deposit Al (thickness of 40nm)/SiO 2 (thickness of 370nm)/Cr (thickness of 5nm), where the aluminum layer is in contact with the base layer 701.
  • Step 5 Use a composite adhesive with adhesive properties to bond the structures respectively formed in steps 3 and 4 together.
  • the refractive index of the composite adhesive is about 1.48, which is consistent with the optical properties of the micro-relief structures 702 and 7022.
  • the optical anti-counterfeiting feature of the part where area A is located is determined by the micro-relief structure 7022 and the color functional layer 703.
  • the composite adhesive used in the processing has the same refractive index as the micro-relief structure 7022, so that the micro-relief structure 7022 does not contribute to
  • the optical anti-counterfeiting feature of the area A that is, the optical anti-counterfeiting feature of the part where the area A is located, is determined by the color functional layer 703.
  • the optical anti-counterfeiting feature of the part where the area B is located is determined by the micro-relief structure 702 and the coating 704 on the surface thereof.
  • the area A in Figure 7 can provide the interference-type multilayer film with a golden-yellow-to-green feature
  • the area B can be Provides features that appear yellow in the direction of reflected light and blue in the direction of scattered light. That is, when viewed in the direction of the reflected light, the area where the area A is located and the area where the area B is located are golden yellow and yellow respectively, and the two areas change to green and blue respectively as the viewing angle continues to be tilted.
  • the other features and beneficial effects of the optical anti-counterfeiting element 7 are the same as those of the above-mentioned optical anti-counterfeiting element 1, which will not be repeated here.
  • the optical anti-counterfeiting element 8 is a schematic cross-sectional view of an anti-counterfeiting element 8 according to another embodiment of the present invention.
  • the optical anti-counterfeiting element 8 includes a base layer 801, a color functional layer 803 located on the base layer 801, and a color functional layer 803 covering the color functional layer 803.
  • At least a part of the micro-relief structure 802 of the area B, the micro-relief structure 8022 of the area A covering the color functional layer 803, the area A and the area B do not overlap, and only the plating layer 804 covering the micro-relief structure 802.
  • the undulation height of the micro-relief structure layer 802 is smaller than the undulation height of the micro-relief structure 8022. That is, the area covered by the plating layer 804 is determined by the difference in height of the undulations of the micro-relief structure 802 and the micro-relief structure 8022.
  • the surface microstructure 8022 can be selected within the following range: one or more continuous curved structures, one or more rectangular structures, one or more sawtooth prisms, or their splicing or combination.
  • the continuous curved structure may be a splicing or combination of one or more structures of a micro lens structure, a sinusoidal structure, an elliptical structure, a hyperboloid structure, a parabolic structure, and the like.
  • the microlens structure may be a refractive microlens, a diffractive microlens, or a splicing or combination thereof, wherein the refractive microlens may include a spherical microlens, an ellipsoidal microlens, a cylindrical microlens or other arbitrary geometric shapes based on Geometrical optics microlenses, diffractive microlenses include harmonic diffractive microlenses, plane diffractive microlenses, Fresnel zone plates, etc.
  • the specific arrangement of the above structures may be periodic, partially periodic, aperiodic, random, or a combination thereof.
  • the characteristic size of the micro-relief structure 802 in the x-axis and y-axis directions is 4.0 ⁇ m
  • the cross-sectional shape of the micro-relief structure 802 is rectangular
  • the external medium is Air
  • d 600nm.
  • the micro-relief structure 8022 is a one-dimensional arrangement of cylindrical mirrors, the arrangement period of which is 20 ⁇ m, the distance between the bottoms of adjacent cylindrical mirrors is 1.5 ⁇ m, and the height of the cylindrical mirrors is 3.5 ⁇ m.
  • the processing process of the optical security element 8 is as follows:
  • Step 1 Use a laser etching process to make an optical original plate containing a micro-relief structure 802 and a micro-relief structure 8022, and electroform it into a metal plate roll, and copy the micro-relief structure on the metal plate roll using a molding process on the lower surface of a base layer
  • the refractive index of the material forming the micro-relief structure is around 1.48.
  • Step 2 A plating layer 804 is vapor-deposited on the surface of the micro-relief structure 802, and the plating layer may be a metal aluminum thin film reflective layer with a thickness of 50 nm.
  • Step 3 Coating a protective layer on the entire surface of the plating layer 804.
  • the protective layer is preferably a polymer, especially a polymer containing cellulose.
  • the polymer forming the protective layer may include a mixture of nitrocellulose (preferably nitro alcohol) and a resin (such as gum arabic and rosin) added to improve the resistance to subsequent processing of the protective layer.
  • the main resin is a polyester resin material
  • the resin material contains the following components: (1) about 20 wt% to about 30 wt% of the main resin, the resin is a polyester with a hydroxyl value greater than 120 , The polyester is a branched hydroxy polyester with a viscosity of 25000 ⁇ 5000mPa.s; (2) about 10wt% to about 25wt% of nitrocellulose, the nitrocellulose has a nitrogen content of ⁇ 12.4% (3) about 5wt% to about 25wt% of a crosslinking agent, the crosslinking agent is an isocyanate oligomer; and (4) about 20wt% to about 60wt% of a solvent.
  • the refractive index of the protective layer is around 1.48.
  • Step 4 Immerse the structure formed in Step 3 into a solution that can dissolve the plating layer 804 but not the protective layer.
  • the solution can be an aqueous solution of sodium hydroxide with a concentration of about 10% at 40°C.
  • the plating layer on the surface of the micro-relief structure 8022 (for example, the metal aluminum film reflective layer) is not dissolved until the reaction is completed, so that the plating layer 804 accurately covers the micro-relief structure 802, thereby forming a precise hollow pattern.
  • the specific reaction process is as follows: the protective layer does not completely cover the plating layer 804 on the micro-relief structure 8022, so the environment is reacted with the exposed plating layer 804 on the micro-relief structure 8022 to achieve hollowing of the area.
  • the next stage of the reaction process is that the environment is centered on the exposed plating layer 804 in the micro-relief structure 8022 and penetrates into the plating layer 804 covered by the protective layers on both sides, thereby further interacting with the micro-relief structure 8022.
  • the plating layer 804 covered by the protective layer reacts to be translucent, and even becomes fully transparent as the reaction process continues.
  • the plating layer 804 on the micro-relief structure 802 is completely covered by the protective layer, so that it does not participate in the reaction and is retained.
  • Step 5 Vapor-deposit the color functional layer 803 on the upper surface of the base layer 801, for example, an interference type multilayer film, that is, sequentially vapor-deposit Al (thickness of 40nm)/SiO 2 (thickness of 270nm)/Cr (thickness of 5nm) , Where the aluminum layer is in contact with the base layer 801.
  • an interference type multilayer film that is, sequentially vapor-deposit Al (thickness of 40nm)/SiO 2 (thickness of 270nm)/Cr (thickness of 5nm) , Where the aluminum layer is in contact with the base layer 801.
  • Step 6 Use a composite adhesive with adhesive properties to bond the structures formed in steps 4 and 5 together.
  • the refractive index of the composite adhesive is about 1.48, which is compatible with the protective layer and micro-relief structures 802 and 8022. The optical performance is consistent.
  • the optical anti-counterfeiting feature of the part where the area A is located is determined by the micro-relief structure 8022 and the color functional layer 803.
  • the composite glue, the protective layer and the micro-relief structure 8022 used in the processing have the same refractive index, making the micro-relief structure 8022 It does not contribute to the optical anti-counterfeiting feature of the portion where the area A is located, that is, the optical anti-counterfeiting feature of the portion where the area A is located is determined by the color functional layer 803.
  • the optical anti-counterfeiting feature of the part where the area B is located is determined by the micro-relief structure 802 and the coating 804 on the surface thereof.
  • the area A in Figure 8 can provide the red-to-green feature of the interference-type multilayer film, and the area B can provide It appears green in the direction of reflected light and magenta in the direction of scattered light. That is, when viewed in the direction of the reflected light, the area where the area A is located and the area where the area B is located respectively appear red and green, and the two areas change to green and magenta respectively as the viewing angle continues to be tilted.
  • the other features and beneficial effects of the optical anti-counterfeiting element 8 are the same as those of the above-mentioned optical anti-counterfeiting element 1, and will not be repeated here.
  • the anti-counterfeiting element of the present invention can integrate a variety of other types of relief structures, such as ordinary diffractive optically variable images, blazed grating structures, and the like.
  • a rainbow or achromatic holographic image is added in area B in FIG. 1a.
  • the holographic image may adopt a sinusoidal, rectangular, and/or sawtooth microstructure, which has diffraction or non The diffractive optical feature, thereby providing a color feature or image feature that is different from the micro-relief structure 102 that does not have to satisfy the interference constructive condition.
  • the holographic image can be formed on the original plate synchronously with the micro-relief structure 102 to reduce the complexity of the process, or be generated step by step in the subsequent processing, for example, by using two molding methods.
  • the anti-counterfeiting element of the present invention can also be hot stamping type, that is, a release layer is coated on the substrate, and then the anti-counterfeiting element of the present invention is fabricated on the release layer. After the hot stamping process is applied to transfer it to the carrier, the substrate Peel it off.
  • the anti-counterfeiting element of the present invention further has other functional layers, such as a magnetic information layer, a fluorescent anti-counterfeiting feature layer, a printed pattern layer, an adhesive layer and the like.
  • the anti-counterfeiting element of the present invention can be applied to transfer or stick to a carrying object in the form of identification, hot stamping of wide strips, stickers, security threads, etc.
  • carrying objects can be high-security products such as banknotes, securities, credit cards, and passports, or high-value-added products.
  • an embodiment of the present invention also provides an optical anti-counterfeiting product, including the above-mentioned optical anti-counterfeiting element.

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Abstract

提供了一种光学防伪元件及包含其的光学防伪产品。光学防伪元件（1）包括：基层（101）；位于基层上的颜色功能层（103）；覆盖颜色功能层的第一区域（B）的至少一部分的第一微浮雕结构（102），第一区域为颜色功能层的部分区域；以及仅覆盖在第一微浮雕结构表面上的镀层（104）。第一微浮雕结构被定义为当光束以一入射角照射第一微浮雕结构时，光束中一波长或波长范围的光在反射方向上干涉相长；并且，颜色功能层与第一微浮雕结构能够提供具有不同颜色特征的光学特征。这种光学防伪元件具有可靠性高且易识别难伪造的优点。

Description

光学防伪元件及光学防伪产品 技术领域
本发明涉及光学防伪领域，具体地，涉及一种光学防伪元件及光学防伪产品。
背景技术
为了防止利用扫描和复印等手段产生的伪造，钞票、证卡和产品包装等各类高安全或高附加值印刷品中广泛采用了衍射光变图像(例如全息图、动态衍射图等)防伪技术，并且取得了非常好的效果。例如，大面额欧元纸币采用了衍射光变图像烫印标识，小面额采用了衍射光变图像烫印宽条，中国2005版人民币除一元面额外都采用了衍射光变图像开窗安全线。Visa、MasterCard和中国的银联信用卡采用了衍射光变图像烫印标识，中国的身份证、驾驶证、护照等重要证件也都采用了衍射光变图像防伪技术。到目前为止，世界上的大多数钞票、信用卡、护照等安全证卡采用了衍射光变图像防伪技术。
用于防伪的衍射光变图像是一种浮雕结构的光栅，当照明光(例如自然光)照射到其表面时，发生衍射作用，利用其1级(或-1级)衍射光形成再现图像，实现醒目的动感、立体、颜色变化等大众防伪特征。
随着衍射光变图像技术的日益普及，该技术在一般商品及包装中也得到了广泛的应用，例如烟、酒、药品等的包装，甚至纺织品、玩具的标签都采用了该技术。这种防伪技术越来越易于实现，使得该技术的防伪性能大打折扣。因此，需要一种新的更可靠的防伪技术。
中国专利申请CN104249597A公开了一种光学防伪元件，其所包含的微结构被定义成当光束以一入射角照射时，该光束中一波长或波长范围的光在透射光方向或反射光方向上干涉相长。该光学防伪元件区别于上述衍射光变图像，避免了具有不确定颜色的彩虹特征的衍射光的干扰，而是利用了干涉机理形成的易于描述的颜色稳定的光，从而使得该光学防伪元件中微浮雕结构所覆盖的区域形成特定的图案时具有较高的易识别难伪造的作用，但作为钞票、身份证件等产品对高防伪技术水平日益提高的紧迫需求，该光学防伪元件需要进一步提高独特性以及易识别难伪造的属性。
为了防止伪造钞票、证件和产品包装等各类高安全或高附加值印刷品，广泛采用了多层结构镀层技术。多层结构镀层技术能够呈现各种颜色特征或在不同的观察角度下能够呈现不同的颜色，并且无法利用照相机、扫描仪、打印机等电子设备模仿或复制，所以具有较高的防伪能力。但是，单纯采用多层镀层技术已经不能很好地满足防伪领域的需求。
将多层结构镀层与中国专利申请CN104249597A公开的防伪元件相结合能够带来丰富而独特的光学防伪特征，然而由于二者都会对入射光波长进行选择性的相长干涉，这一结合将会产生矛盾，使多层结构镀层提供的颜色抑或是中国专利申请CN104249597A公开的防伪元件所提供的颜色特征都明显削弱，从而不利于防伪特征的识别，因此需要进一步开发新型的光学防伪元件。
发明内容
本发明实施例的目的是提供一种更可靠且易识别难伪造的光学防伪元件及光学防伪产品。
为了实现上述目的，本发明提供一种光学防伪元件，该光学防伪元件包括：基层；位于所述基层上的颜色功能层；覆盖所述颜色功能层的第一区域的至少一部分的第一微浮雕结构，所述第一区域为所述颜色功能层的部分区域；以及仅覆盖在所述第一微浮雕结构表面上的镀层；所述第一微浮雕结构被定义成当光束以一入射角照射所述第一微浮雕结构时，该光束中一波长或波长范围的光在反射光方向上干涉相长。
相应地，本发明还提供一种光学防伪产品，包括上述的光学防伪元件。
通过上述技术方案，可以实现一种既明显区别于衍射光变图像防伪技术又不同于单纯的多层结构镀层的光学防伪特征，含有该特征的样品在第一微浮雕结构区域提供了不同的观察角度分别呈现两种互为补色的颜色特征，而在其余区域则提供了颜色功能层的颜色特征。可以通过分别定义第一微浮雕结构及颜色功能层的结构参数来实现鲜明的对比和反差，形成具有易识别、难伪造的特征的独特的光学防伪元件。
本发明实施例的其它特征和优点将在随后的具体实施方式部分予以详细说明。
附图说明
附图是用来提供对本发明实施例的进一步理解，并且构成说明书的一部分，与下面的具体实施方式一起用于解释本发明实施例，但并不构成对本发明实施例的限制。在附图中：
图1a至图1b示出了根据本发明一实施方式的光学防伪元件；
图1c至图1d示出了微浮雕结构的浮雕单元的剖面形状示意图；
图2a至图2b示出了根据本发明一实施方式的光学防伪元件；
图3a至图3c示出了根据本发明一实施方式的光学防伪元件；
图4a至图4f示出了根据本发明一实施方式的光学防伪元件的制作流程示意图；
图5a至图5c示出了根据本发明一实施方式的光学防伪元件的俯视示意图；
图6a至图6b示出了根据本发明一实施方式的光学防伪元件的俯视示意图；
图7示出了根据本发明一实施方式的光学防伪元件的剖面示意图；以及
图8示出了根据本发明一实施方式的防伪元件的剖面示意图。
具体实施方式
以下结合附图对本发明实施例的具体实施方式进行详细说明。应当理解的是，此处所描述的具体实施方式仅用于说明和解释本发明实施例，并不用于限制本发明实施例。
本发明中提到的“特征尺寸”是指微浮雕结构中取其表面高度最低和最高点的平均值将表面分割，从而形成包围凸起或凹下部分的轮廓在任意方向的尺寸。
“微浮雕结构”是指二维表面上根据需要形成的凹凸不平的微结构。
“浮雕单元”是指微浮雕结构中取其表面高度最低和最高点的平均值，将表面分割形成的单个的凸起或凹下的部分，其特征尺寸在微米量级。“微浮雕结构的深度d”是指微浮雕结构中表面高度最高点和最低点的高度差。
图1a示出了根据本发明一实施方式的光学防伪元件1。图1a是根据本发明一实施方式的防伪元件1的剖面示意图，光学防伪元件1包括基层101，位于基层101上的颜色功能层103，位于颜色功能层103上且覆盖颜色功能层103的区域B的至少一部分的微浮雕结构102，以及仅覆盖在所述微浮雕结构102上的镀层104。区域B为颜色功能层103的区域的部分区域，颜色功能层103除区域B之外的区域称为区域A。微浮雕结构102被定义成当光束以一入射角照射微浮雕结构102时，该光束中一波长或波长范围的光在反射光方向上干涉相长，并且所述颜色功能层103与微浮雕结构102能够提供具有不同颜色特征的光学特征。
优选地，所述颜色功能层103可以是干涉型多层膜结构，该干涉型多层膜结构形成法布里-泊罗谐振腔，其对入射的白光具有选择作用，使得出射光线只包含某些波段，从而呈现特定的颜色；当入射角度变化时，与之相对的光程发生变化，干涉波段也发生变化，从而在出射角方向呈现给观测者的颜色也随之变化，从而形成光变效果。所述干涉型多层膜结构可以包括下述结构中的任意一种：(1)由吸收层、低折射率介质层和反射层依次堆叠形成的镀层，其中反射层与所述基层101表面相接触；(2)由高折射率介质层、低折射率介质层和高折射率介质层依次堆叠形成的镀层；以及(3)由吸收层、高折射率介质层和反射层依次堆叠形成的镀层，其中反射层与所述基层101表面相接触。优选地，上述的反射层的材料可以为具有高反射率的材料，如金、银、铜、铝、锌、镍、钛等以及它们的合金；上述的吸收层的材料要求是其折射率与吸光系数接近的材料，例如可以是半金属材料(如硅、锗等)，也可以是金属材料或其合金(如铬、铜、镍、镍铬合金等)；上述的低折射率介质层的折射率小于1.7，例如可以是氟化镁、二氧化硅、冰晶石等；上述的高折射率介质层的 折射率大于或等于1.7，例如可以是ZnS、TiN、TiO 2、TiO、Ti 2O 3、Ti 3O 5、Ta 2O 5、Nb 2O 5、CeO 2、Bi 2O 3、Cr 2O 3、Fe 2O 3、HfO 2、ZnO等。所述干涉型多层膜结构可以通过热蒸发、电子束蒸发、磁控溅射等物理或化学气相沉积的方法获得。
优选地，所述颜色功能层103可以是吸收型结构，其中，所述吸收型结构可以是油墨、颜料、染料中的一种或几种的组合。进一步优选地可以例如采用Sicpa公司生产的OVI光变油墨。
优选地，所述颜色功能层103还可以为液晶光变层。典型地，例如可采用胆甾型液晶材料来实现颜色功能层103，从而可实现例如随观察角度变化产生的绿变蓝、红变绿等的颜色特征。液晶光变层可以通过涂布、印刷等方式批量生产。
优选地，所述颜色功能层103还可以为多层共挤光变膜。而且可以直接将多层共挤光变膜用作基层101。
为了便于描述微浮雕结构102，定义x-y-z空间坐标系。如图1b所示，微浮雕结构102可以位于xoy平面(或与xoy平面平行的平面)，且在x轴、y轴方向的特征尺寸可以例如是0.3μm-6μm，优选为0.6μm-3μm，且微浮雕结构102的图案(即微浮雕结构的浮雕单元)可以是随机或伪随机分布的。微浮雕结构102中凸起部分可以占微浮雕结构102总面积的20％-80％，优选为35％-65％。如图1a所示，微浮雕结构102的浮雕单元的剖面形状可以是正弦形。如图1c所示，微浮雕结构102的浮雕单元的剖面形状可以是锯齿形。如图1d所示，微浮雕结构102的浮雕单元的剖面形状可以是矩形。本领域技术人员可以理解的是，微浮雕结构102的浮雕单元的剖面形状还可以是其他形状。微浮雕结构102的深度d可以满足以下条件，即当自然光(白光)以入射角α照射微浮雕结构102时，光束通过微浮雕结构102后，波长为λ或者一波长范围的光在反射光方向上干涉相长，从而使得在反射光方向观察光学防伪元件1时，呈现第一颜色，而在散射光方向上观察光学防伪元件1时，呈现第二颜色(如图1a所示)。
微浮雕结构102的深度d通常在100nm-5μm之间，优选为200nm-3μm。可以通过以下的方法来确定深度d。
①表示出微浮雕结构102的复振幅透过率τ g，τ g为深度d、设计波长λ、微浮雕结构102的槽型、材料折射率分布n以及位置(x,y)的函数；②对复振幅透过率τ g进行傅利叶变换；③找出波长为λ的反射光(即零级衍射光)最大的条件；④根据反射光最大的条件计算微浮雕结构102的深度d。
举例来说，设计波长λ＝600nm，微浮雕结构102材料的折射率n＝1.5，微浮雕结构102的剖面形状为正弦形，外部介质为空气，则d＝1528.8nm时，防伪元件1在反射光方向上呈现红色， 在散射光方向呈现蓝绿色。若d＝2668.8nm，由于此时波长为410.8nm的光也满足反射光干涉相长条件，所以防伪元件1在反射光方向上呈现洋红色，散射光方向上呈现绿色。
微浮雕结构可以通过激光刻蚀、电子束刻蚀、离子刻蚀等方式制成母版，然后通过电铸、模压、UV复制等工艺复制到基层上。更为常用的工艺是在基层的表面涂布成像层，将微浮雕结构复制在成像层上，目的是提高微浮雕结构的复制质量和提高复制效率。
构成微浮雕结构的材料可以例如为ZnS、ZnO、Ta 2O 5、SnO 2、Nb 2O 5、HfO 2、In 2O 3、CeO 2、Dy 2O 3、Bi 2O 3、MgF 2、Al 2O 3、AlF 3、CaF 2、SiO 2、SrF 2、YbF 3、NaF、Na 3AlF 6、PET、PVC、PE、聚酯胶、或聚氨酯胶等。
所述基层可以例如为PET、PVC、或PE等透明材料，也可以是纸张、印刷品、包装等载体。所述基材也可以是加工过程中的载体，而在后期应用时被剥离。
在本实施方式中，镀层104可以例如为金属反射层。优选地构成金属反射层的材料可以包括例如金、银、铜、铁、锡、镍、铬、铝、锌、钛及其合金，厚度可以大于5nm，优选大于10nm。所述镀层104可以通过热蒸发、电子束蒸发、磁控溅射等物理或化学气相沉积的方法获得。镀层104的作用是为微浮雕结构102提供反射功能，从而使反射光的效率增强。当镀层104具有颜色特征时，其效果为该颜色特征与微浮雕结构102提供的颜色特征的叠加。
下面对图1a至图1b所示的光学防伪元件1中区域A和区域B各自所在部分的光学防伪特征进行说明。
总的来说，光学防伪元件1中区域A所在部分的光学特征取决于颜色功能层103在以上优选方案中的选择，有两种可能，一种是提供各个观察角度下均单一不变的颜色，另一种是提供观察角度改变时的颜色随之变化的特征。不论如何选择，假设仅由颜色功能层103提供光学防伪元件的防伪特征，其防伪效果都是单一而不突出的，而区域B所在部分提供的防伪特征则对此作出了有力的补充：首先，区域B所在部分本身能够提供反射光方向和散射光方向上的颜色变化和互补色特征，这是区域A所在部分的颜色功能层103所不具备的；其二，区域B所在部分的颜色特征取决于微浮雕结构102的形貌、折射率n、其在xoy平面上的参数分布以及结构深度d，因此，可以通过计算和设计参数使区域B所在部分与区域A所在部分提供的颜色或颜色变化特征不同，甚至形成强烈的反差和对比，以达到本发明的光学防伪元件具有更强的独特性，达到更加易于公众识别且造假者难以伪造的目的。
实际应用中，可以例如采用如下优选方案对区域A所在部分和区域B所在部分进行配置：
(1)第一种配置
颜色功能层：选择颜色功能层103为红色纳米油墨。
微浮雕结构：微浮雕结构102材料的折射率n＝1.50，微浮雕结构102的剖面形状为正弦形，外部介质为空气，则d＝1528.8nm，所以防伪元件1中微浮雕结构102所在区域在反射光方向上呈现红色，在散射光方向呈现蓝绿色。
光学防伪特征：在反射光方向观察时，区域A所在部分和区域B所在部分均趋于红色；在散射光方向观察时，区域A所在部分为红色，区域B所在部分为蓝绿色。
(2)第二种配置
颜色功能层：选择颜色功能层103为绿色金属油墨。
微浮雕结构：微浮雕结构102材料的折射率n＝1.50，微浮雕结构102的剖面形状为正弦形，外部介质为空气，则d＝2668.8nm，所以防伪元件1中微浮雕结构102所在区域在反射光方向上呈现洋红色，散射光方向上呈现绿色。
光学防伪特征：在反射光方向观察时，区域A所在部分为金属质感的绿色，区域B所在部分均趋于红色；在散射光方向观察时，区域A所在部分和区域B所在部分均趋于绿色。
(3)第三种配置
颜色功能层：选择颜色功能层103为Sicpa公司生产的OVI油墨，该OVI油墨沿z轴观察为绿色，与z轴呈45°角附近观察时为蓝色。
微浮雕结构：微浮雕结构102材料的折射率n＝1.48，微浮雕结构102的剖面形状为矩形，外部介质为空气，则d＝600nm，所以防伪元件1中微浮雕结构102所在区域在反射光方向上呈现绿色，散射光方向上呈现洋红色。
光学防伪特征：在反射光方向观察时，区域A所在部分和区域B所在部分均趋于绿色；在倾斜观察过程中，区域A所在部分变为绿色，区域B所在部分则变为洋红色。
(4)第四种配置
颜色功能层：选择颜色功能层103为依次包含Al(厚度为：40nm)/SiO2(厚度为：370nm)/Cr(厚度为：5nm)的干涉型多层膜结构，该参数的干涉型多层膜具有正面观察呈现金黄色，倾斜观察呈现绿色的特征。
微浮雕结构：微浮雕结构102材料的折射率n＝1.48，微浮雕结构102的剖面形状为矩形，外部介质为空气，则d＝600nm，所以防伪元件1中微浮雕结构102所在区域在反射光方向上呈现绿色，散射光方向上呈现洋红色。
光学防伪特征：在反射光方向观察时，区域A所在部分呈现金黄色，区域B所在部分均呈现绿色；在倾斜观察过程中，区域A所在部分变为绿色，区域B所在部分则变为洋红色。
(5)第五种配置
颜色功能层：选择颜色功能层103为瑞士Rolic公司生产的胆甾型液晶光变膜，其采用红色-绿色特征，即正面观察为红色，倾斜观察为绿色的特征。
微浮雕结构：微浮雕结构102材料的折射率n＝1.48，微浮雕结构102的剖面形状为正弦形，外部介质为空气，则d＝500nm，所以防伪元件1中微浮雕结构102所在区域在反射光方向上呈现黄色，散射光方向上呈现蓝色。
光学防伪特征：在反射光方向观察时，区域A所在部分呈现红色，区域B所在部分呈现黄色；在倾斜观察的过程中，区域A所在部分变为为绿色，区域B所在部分变为蓝色。
(6)第六种配置
颜色功能层：选择颜色功能层103为3M公司生产的多层共挤光变膜，其采用绿色-蓝色特征，即正面观察为绿色，倾斜观察为蓝色的特征。
微浮雕结构：微浮雕结构102材料的折射率n＝1.48，微浮雕结构102的剖面形状为正弦形，外部介质为空气，则d＝500nm，所以防伪元件1中微浮雕结构102所在区域在反射光方向上呈现黄色，散射光方向上呈现蓝色。
光学防伪特征：在反射光方向观察区域A所在部分呈现绿色，区域B所在部分呈现黄色；在倾斜观察过程中，区域A所在部分和区域B所在部分均趋于蓝色。
以上是对于颜色功能层103和微浮雕结构进行配置从而形成区域A所在部分和区域B所在部分具有不同的颜色或颜色变化特征的实施例。需要说明的是，虽然其中存在区域A所在部分和区域B所在部分在特定观察角度上颜色趋同的情况，但是客观地看，实际中二者吸收或反射光谱仍然存在有差异的情况，但这本质上并不影响本发明的光学防伪元件1的防伪性能和质量，而且该差异能够有助于吸引和帮助用户对区域A所在部分或区域B所在部分图案的识别。
图2a和2b示出了根据本发明一实施方式的反射式光学防伪元件2。如图所示，提供了一种光学防伪元件2，包括基层201，位于基层201上的颜色功能层203，位于颜色功能层203上，且覆盖颜色功能层203的区域B的至少一部分的微浮雕结构202，以及仅覆盖在所述微浮雕结构202上的镀层204。区域B为颜色功能层203的区域的部分区域，颜色功能层203除区域B之外的区域称为区域A。微浮雕结构202被定义成当光束以一入射角照射微浮雕结构202时，该光束中一波长或波长范围的光在反射光方向上干涉相长，并且所述颜色功能层203与微浮雕结构202能够提供具有不同颜色特征的光学特征。
为便于描述，定义x-y-z空间坐标系。如图2a所示，微浮雕结构202可以位于xoy平面(或与xoy平面平行的平面)，且在x轴方向的特征尺寸可以大于6μm，优选大于10μm，由此微浮雕结构202在该方向上没有衍射效果，微浮雕结构202在y轴方向上的特征尺寸可以为0.3μm-6μm，优选为 0.6μm-3μm，且图案可以是随机或伪随机分布的。微浮雕结构202中凸起部分可以占微浮雕结构202总面积的20％-80％，优选为35％-65％。图2b是根据本发明的一个实施方式的防伪元件在yoz平面(或与yoz平面平行的平面)的剖面示意图。如图2b所示，微浮雕结构202的浮雕单元的剖面形状可以是正弦形。但是本领域技术人员可以理解，微浮雕结构202的浮雕单元的剖面形状可以是锯齿形、矩形或者其他形状。微浮雕结构202的深度d可以满足下述条件，即自然光(白光)以入射角α照射微浮雕结构202时，光束通过微浮雕结构202后，波长为λ或者一波长范围的光在反射光方向上干涉相长，从而使得所述光学防伪元件2在反射光方向上呈现第一颜色。此外，如果光束在yoz平面(或与yoz平面平行的平面)内，光学防伪元件2在yoz平面(或与yoz平面平行的平面)内散射光方向上呈现第二颜色。
微浮雕结构202深度d可以为100nm-5μm，优选为200nm-3μm。确定深度d的方法与上述实施方式相同，这里不再赘述。此外，光学防伪元件2的其他特征与有益效果与上述光学防伪元件1相同，这里不再赘述。
图3a-3c示出了根据本发明的一个实施方式的反射式光学防伪元件3。如图所示，提供了一种光学防伪元件3，包括基层301，位于基层301上的颜色功能层303，位于颜色功能层303上，且覆盖颜色功能层303的区域B的至少一部分的微浮雕结构302，以及仅覆盖在所述微结构上的镀层304。区域B为颜色功能层303的区域的部分区域，颜色功能层303除区域B之外的区域称为区域A。微浮雕结构302被定义成当光束以一入射角照射微浮雕结构302时，该光束中一波长或波长范围的光在反射光方向上干涉相长，并且所述颜色功能层303与微浮雕结构302能够提供具有不同颜色特征的光学特征。
为便于描述，定义x-y-z空间坐标系。如图3a所示，微浮雕结构302可以位于xoy平面(或与xoy平面平行的平面)，在y轴方向上的特征尺寸可以例如是0.3μm-6μm，优选为0.6μm-3μm，图案可以是随机或伪随机分布的，在x轴方向上的特征尺寸可以例如是0.3μm-6μm，优选为0.6μm-3μm，图案可以例如是周期性结构。微浮雕结构302中凸起部分可以占微浮雕结构302总面积的20％-80％，优选为35％-65％。图3b是根据本发明的一个实施方式的防伪元件3在yoz平面(或与yoz平面平行的平面)的剖面示意图，图3c是根据本发明的一个实施方式的防伪元件3在xoz平面(或与xoz平面平行的平面)的剖面示意图。微浮雕结构302的浮雕单元的剖面形状可以是正弦形、锯齿形、矩形或者其他形状。微浮雕结构302的深度d可以满足下述条件，即自然光(白光)以入射角α照射微浮雕结构302时，光束通过微浮雕结构302后，波长为λ(或者一波长范围)的光在反射光方向上干涉相长，从而使得所述光学防伪元件3在反射光方向上观察到第一颜色。此外，如果光束在yoz平面(或与yoz平面平行的平面)内，光学防伪元件3在yoz平面(或与yoz平面平行的平面)内散 射光方向上呈现第二颜色；如果光束在xoz平面(或与xoz平面平行的平面)内，光学防伪元件3在衍射光方向上观察到光栅的+1或-1级衍射光颜色随观察角度变化。
微浮雕结构302深度d通常在100nm-5μm之间，优选为200nm-3μm。确定深度d的方法与第一个实施方式中的相同，这里不再赘述。此外，光学防伪元件3的其他特征与有益效果与上述光学防伪元件1相同，这里不再赘述。
下面通过图4a-f对图1实施例中的光学防伪元件1的制作流程进行举例说明。
步骤一：如图4a所示，利用激光刻蚀工艺制作带有包含微浮雕结构102的光学原版，并电铸为金属版辊，在基层1011的下表面利用模压工艺将金属版辊上的微浮雕结构复制为微浮雕结构1021，形成微浮雕结构1021的材料折射率可以在1.48附近。
步骤二：如图4b所示，在微浮雕结构1021表面蒸镀镀层104，所述镀层可以为40nm厚的金属铝薄膜反射层。
步骤三：如图4c所示，采用印刷的方式在区域B的镀层104表面涂覆保护层105，所述保护层105可以为丙烯酸类的材料，其折射率可以在1.48附近。
步骤四：如图4d所示，将图4c所示的结构浸入能够溶解镀层104但是不能溶解保护层105的溶液中，例如，所述溶液可以是40℃的浓度约为10％的氢氧化钠水溶液，直至保护层105未覆盖的区域A中的反射层(例如，金属铝薄膜反射层)反应溶解完毕为止，从而使镀层104形成镂空图形。
步骤五：如图4e所示，在基层101的上表面蒸镀颜色功能层103，例如可以是干涉型多层膜，即依次蒸镀Al(厚度为40nm)/SiO 2(厚度为370nm)/Cr(厚度为5nm)，其中铝层与基层101接触。该参数的干涉型多层膜具有正面观察为金黄色，倾斜观察为绿色的特征。
步骤六：如图4f所示，利用带有粘接性能的复合胶将图4d和图4e所示的结构粘接在一起，所述复合胶的折射率约为1.48，即与1021和105的光学性能一致，因此图4f中将复合胶与1021和105统一表示为102。
以上为制作图1所述的光学防伪元件1的一种优选的典型实施方法。光学防伪元件2和3的制作流程与此类似，这里不再赘述。
下面继续结合图4a至图4f和图5a至图5c说明光学防伪元件1存在的不足之处，
图5a对应图4b所示的带有镀层104的微浮雕结构1021在与xoy平面或与其平行的平面上的俯视图像，其中不同区域C和D填充有不同参数(例如微浮雕结构在面内的排布、结构深度、形貌等参数)的微浮雕结构。实际应用中，也可以在区域C和D中根据设计需要进一步分割为宏观或微观的子区域用来填充不同参数的微浮雕结构。
图5b对应图4c所示的施加了保护层105的微浮雕结构1021，由于保护层105与微浮雕结构1021是在各自的步骤中分别加工的，二者在xoy平面上的投影客观上会出现难以避免的错位误差，按照现有加工工艺水平，该错位误差通常在0.1毫米以上。当保护层105覆盖的区域是以无误差地覆盖微浮雕结构1021的区域D为最初的设计目标时，其实际上却是覆盖了区域B。从而造成了镀层104保留区域的不确定性，进一步造成了光学防伪元件1中区域A和区域B的位置不确定性。例如实际应用中不可避免地出现图5c所示的图像失真和残缺。
图6a-b所示为针对图5a-c实施例中暴露出的图像失真和残缺问题的一种优化的实施例。图6a表示了带有镀层104的微浮雕结构1021在与xoy平面或与其平行的平面上的俯视图像，其中不同区域C和D填充有不同参数(例如微浮雕结构在面内的排布，结构深度，形貌等)的微浮雕结构。
图6b对应图4c所示的施加了保护层105的微浮雕结构1021。为了避免图像失真和残缺，保护层105的覆盖面积比目标覆盖区域D略大，超出的尺寸例如至少为0.1毫米，以确保所述错位误差被包含在内。因此目标覆盖区域D，即便是在所述错位误差存在的情况下依然能够被全包含实际覆盖区域B中，从而保证了图像的完整性。但是，这一优化结构带来了另外一个问题，即保护层105所保护的镀层104会覆盖设计目标区域D以外的区域，也就是区域C的一部分，解决了图像完整性的同时造成了图像冗余。而且冗余的镀层104会影响颜色功能层103所在的区域A的面积和完整性。
另外，不论是图5还是图6所述的光学防伪元件1都无法实现高精细度的镀层104的镂空图形。这受保护层105的印刷工艺的限制，现有印刷工艺中的线条精细度均无法突破0.01毫米的笔画宽度。
为解决图5和图6表述的问题，保证光学防伪元件具有更高的独特性和易识别难伪造的属性。本发明进一步提供另外一种光学防伪元件，下面结合图7进行描述。
图7是根据本发明一实施方式的防伪元件7的剖面示意图，光学防伪元件7包括基层701，位于基层701上的颜色功能层703，位于颜色功能层703上且覆盖颜色功能层703的区域B的至少一部分的微浮雕结构702，覆盖颜色功能层703的区域A的微浮雕结构7022，区域A和区域B不重叠，以及仅覆盖在微浮雕结构702上的镀层704。其中，微浮雕结构层702的表面积与表观面积的比值小于微浮雕结构7022的表面积与表观面积的比值。即镀层704所覆盖的区域由微浮雕结构702和微浮雕结构7022的所述表面积与表观面积的比值的差异所决定。
具体而言，微浮雕结构702和微浮雕结构7022是在xoy平面上的高度随位置分布而起伏变化的表面起伏结构所组成，相对于平坦表面而言，表面起伏结构在单位表观面积上的表面积更大，且该表面积与表面起伏结构的起伏程度呈正相关。在本文中，术语“表观面积”指的是某一区域中在与该区域平行的平面内的正投影的面积，即无视该区域中的起伏结构的面积；术语“表面积”指的 是所述某一区域中的起伏结构的实际面积。显然，所述某一区域的表面积与其表观面积之比为不小于1的数值。
优选地，表面微结构7022可以在如下范围内选择：一个或多个连续曲面型结构、一个或多个矩形结构、一个或多个锯齿型棱镜或它们的拼接或组合。其中，所述连续曲面型结构可以为微透镜结构、正弦型结构、椭圆型结构、双曲面型结构、抛物面型结构等中的一种或多种结构的拼接或组合。所述微透镜结构可以是折射型微透镜、衍射型微透镜或它们的拼接或组合，其中折射型微透镜可以包括球面微透镜、椭球面微透镜、柱面微透镜或其它任意几何形状的基于几何光学的微透镜，衍射型微透镜包括谐衍射微透镜、平面衍射微透镜、菲涅耳波带片等。另外，以上结构的具体排列方式可以是周期性的、局部周期性的、非周期性、随机性的或它们的组合等。
图7的实施方式中，微浮雕结构702在x轴、y轴方向的特征尺寸为2.8μm，微浮雕结构702材料的折射率n＝1.48，微浮雕结构702的剖面形状为正弦形，外部介质为空气，d＝500nm。微浮雕结构7022为正弦型光栅，其排列周期为350nm，深300nm。光学防伪元件7的加工过程如下：
步骤一：利用激光刻蚀工艺制作包含微浮雕结构702和微浮雕结构7022的光学原版，并电铸为金属版辊，在一基层的下表面利用模压工艺将金属版辊上的微浮雕结构复制为微浮雕结构702和微浮雕结构7022，形成微浮雕结构的材料折射率可以在1.48附近。
步骤二：在微浮雕结构702表面蒸镀镀层704，所述镀层可以为50nm厚的金属铝薄膜反射层。
步骤三：将步骤二形成的结构浸入能够溶解镀层704的溶液中，例如，所述溶液可以是40℃的浓度约为5％的氢氧化钠水溶液中，微浮雕结构7022表面的镀层(例如，金属铝薄膜反射层)反应溶解完毕为止，从而使镀层704准确覆盖微浮雕结构702，从而形成精准镂空图形。
步骤四：在另一基层701的上表面蒸镀颜色功能层703，例如可以是干涉型多层膜，即依次蒸镀Al(厚度为40nm)/SiO 2(厚度为370nm)/Cr(厚度为5nm)，其中铝层与基层701接触。
步骤五：利用带有粘接性能的复合胶将步骤三和步骤四分别形成的结构粘接在一起，所述复合胶的折射率约为1.48，与微浮雕结构702和7022的光学性能一致。
以上为制作图7所述的光学防伪元件7的实施步骤。其中，区域A所在部分的光学防伪特征由微浮雕结构7022和颜色功能层703共同决定，然而由于加工过程中采用的复合胶与微浮雕结构7022的折射率相同，使得微浮雕结构7022不贡献于区域A的光学防伪特征，即区域A所在部分的光学防伪特征由颜色功能层703所决定。同时，区域B所在部分的光学防伪特征由微浮雕结构702及其表面的镀层704共同决定。
以颜色功能层703是干涉型多层膜、镀层704为金属铝薄膜反射层为例，图7中区域A所在部分可以提供干涉型多层膜的金黄色变绿色的特征，区域B所在部分可以提供在反射光方向上呈现 黄色，散射光方向上呈现蓝色的特征。即在反射光方向上观察时，区域A所在部分和区域B所在部分分别呈现金黄色和黄色，而在继续倾斜视角的过程中两区域分别呈现向绿色和向蓝色变化的过程。光学防伪元件7的其他特征与有益效果与上述光学防伪元件1相同，这里不再赘述。
图8是根据本发明的另一个实施方式的防伪元件8的剖面示意图，光学防伪元件8包括基层801，位于基层801上的颜色功能层803，位于颜色功能层803上且覆盖颜色功能层803的区域B的至少一部分的微浮雕结构802，覆盖颜色功能层803的区域A的微浮雕结构8022，区域A和区域B不重叠，以及仅覆盖在所述微浮雕结构802上的镀层804。其中，微浮雕结构层802的起伏高度小于微浮雕结构8022的起伏高度。即镀层804所覆盖的区域由微浮雕结构802和微浮雕结构8022的所述起伏高度差异所决定。
优选地，表面微结构8022可以在如下范围内选择：一个或多个连续曲面型结构、一个或多个矩形结构、一个或多个锯齿型棱镜或它们的拼接或组合。其中，所述连续曲面型结构可以为微透镜结构、正弦型结构、椭圆型结构、双曲面型结构、抛物面型结构等中的一种或多种结构的拼接或组合。所述微透镜结构可以是折射型微透镜、衍射型微透镜或它们的拼接或组合，其中折射型微透镜可以包括球面微透镜、椭球面微透镜、柱面微透镜或其它任意几何形状的基于几何光学的微透镜，衍射型微透镜包括谐衍射微透镜、平面衍射微透镜、菲涅耳波带片等。另外，以上结构的具体排列方式可以是周期性的、局部周期性的、非周期性、随机性的或它们的组合等。
图8的实施方式中，微浮雕结构802在x轴、y轴方向的特征尺寸为4.0μm，微浮雕结构802材料的折射率n＝1.48，微浮雕结构802的剖面形状为矩形，外部介质为空气，d＝600nm。微浮雕结构8022为一维排列的柱面镜，其排列周期为20μm，相邻柱面镜的底部间隔为1.5μm，柱面镜高度为3.5μm。光学防伪元件8的加工过程如下：
步骤一：利用激光刻蚀工艺制作包含微浮雕结构802和微浮雕结构8022的光学原版，并电铸为金属版辊，在一基层的下表面利用模压工艺将金属版辊上的微浮雕结构复制为微浮雕结构802和微浮雕结构8022，形成微浮雕结构的材料折射率在1.48附近。
步骤二：在微浮雕结构802表面蒸镀镀层804，所述镀层可以为50nm厚的金属铝薄膜反射层。
步骤三：在镀层804表面整体涂覆保护层，所述保护层优选为聚合物，尤其是包含纤维素的聚合物。例如，形成保护层的聚合物可以包括硝基纤维素(优选为硝基醇)与所加入的用以提高保护层的耐后续处理性的树脂(如阿拉伯树胶和松香)等的混合物。在一种优选方案中，主树脂为聚酯的树脂材料，所述树脂材料包含以下组分：(1)约20wt％-约30wt％的主树脂，所述树脂为羟值大于120的聚酯，所述聚酯为支链化羟基聚酯，黏度为25000±5000mPa.s；(2)约10wt％-约25wt％的硝基纤维素，所述硝基纤维素为含氮量<12.4％的低氮硝化纤维；(3)约5wt％-约25wt％的交联剂， 所述交联剂为异氰酸酯低聚体；以及(4)约20wt％-约60wt％的溶剂。所述保护层的折射率在1.48附近。
步骤四：将步骤三形成的结构浸入能够溶解镀层804但不能溶解保护层的溶液中，所述溶液可以是40℃的浓度约为10％的氢氧化钠水溶液，微浮雕结构8022表面的镀层(例如，金属铝薄膜反射层)反应溶解完毕为止，从而使镀层804准确覆盖微浮雕结构802，从而形成精准镂空图形。具体反应过程为：保护层并未完全遮盖微浮雕结构8022上的镀层804，因此使所述环境与微浮雕结构8022上裸露的镀层804反应，以实现该区域的镂空。同时，这一反应过程的下一阶段为，所述环境以微浮雕结构8022中裸露的镀层804为中心向由两侧的保护层所遮盖的镀层804中渗透，从而进一步与微浮雕结构8022上被保护层遮盖的镀层804反应至半透明，甚至随着反应过程的持续进行进而达到全透明。在整个反应过程中，微浮雕结构802上的镀层804被保护层完全遮盖，因而不参与反应得以保留。
步骤五：在基层801的上表面蒸镀颜色功能层803，例如可以是干涉型多层膜，即依次蒸镀Al(厚度为40nm)/SiO 2(厚度为270nm)/Cr(厚度为5nm)，其中铝层与基层801接触。
步骤六：利用带有粘接性能的复合胶将步骤四和步骤五分别形成的结构粘接在一起，所述复合胶的折射率约为1.48，与所述保护层及微浮雕结构802和8022的光学性能一致。
以上为制作图8所述的光学防伪元件8的实施步骤。其中，区域A所在部分的光学防伪特征由微浮雕结构8022和颜色功能层803共同决定，然而由于加工过程中采用的复合胶、保护层及微浮雕结构8022的折射率相同，使得微浮雕结构8022不贡献于区域A所在部分的光学防伪特征，即区域A所在部分的光学防伪特征由颜色功能层803所决定。同时，区域B所在部分的光学防伪特征由微浮雕结构802及其表面的镀层804共同决定。
以颜色功能层803是干涉型多层膜、镀层804为金属铝薄膜反射层为例，图8中区域A所在部分可以提供干涉型多层膜的红色变绿色的特征，区域B所在部分可以提供在反射光方向上呈现绿色，散射光方向上呈现洋红色的特征。即在反射光方向上观察时，区域A所在部分和区域B所在部分分别呈现红色和绿色，而在继续倾斜视角的过程中两区域分别呈现向绿色和向洋红色变化的过程。光学防伪元件8的其他特征与有益效果与上述光学防伪元件1相同，这里不再赘述。
本发明的防伪元件可以集成多种其他类型的浮雕结构，比如普通的衍射光变图像、闪耀光栅结构等。例如在图1a中的区域B中进一步在微浮雕结构102存在的同时，加入彩虹或消色全息图像，所述全息图像可以采用正弦形、矩形和/或锯齿形微观结构，其具备衍射或非衍射的光学特征，从而提供与微浮雕结构102不同的不必满足所述干涉相长条件的颜色特征或图像特征。所述全息图像可以与微浮雕结构102同步在原版上形成从而减少工艺复杂度，或在后续加工中分步生成，例如采用 两次模压的方式。
本发明的防伪元件还可以是烫印型的，即在基材上涂布剥离层，再在剥离层上制作本发明的防伪元件，当应用烫印工艺将它转移到承载物后，基材剥离下来。
本发明的防伪元件进一步带有其他功能层，如磁性信息层、荧光防伪特征层、印刷图案层、黏结胶层等。
本发明的防伪元件可以应用于标识、烫印宽条、贴条、安全线等形式转移或粘贴到承载物上。这些承载物可以是钞票、证券、信用卡、护照等高安全产品，也可以是高附加值商品。
相应地，本发明实施例还提供一种光学防伪产品，包括上述的光学防伪元件。
以上结合附图详细描述了本发明实施例的可选实施方式，但是，本发明实施例并不限于上述实施方式中的具体细节，在本发明实施例的技术构思范围内，可以对本发明实施例的技术方案进行多种简单变型，这些简单变型均属于本发明实施例的保护范围。
另外需要说明的是，在上述具体实施方式中所描述的各个具体技术特征，在不矛盾的情况下，可以通过任何合适的方式进行组合。为了避免不必要的重复，本发明实施例对各种可能的组合方式不再另行说明。
此外，本发明实施例的各种不同的实施方式之间也可以进行任意组合，只要其不违背本发明实施例的思想，其同样应当视为本发明实施例所公开的内容。

Claims (16)

  1. 一种光学防伪元件，该光学防伪元件包括：
    基层；
    位于所述基层上的颜色功能层；
    覆盖所述颜色功能层的第一区域的至少一部分的第一微浮雕结构，所述第一区域为所述颜色功能层的部分区域；以及
    仅覆盖在所述第一微浮雕结构表面上的镀层；
    所述第一微浮雕结构被定义成当光束以一入射角照射所述第一微浮雕结构时，该光束中一波长或波长范围的光在反射光方向上干涉相长。
  2. 根据权利要求1所述的光学防伪元件，其中，所述光学防伪元件还包括：
    覆盖在所述颜色功能层的除所述第一区域之外的第二区域上的第二微浮雕结构，所述第一微浮雕结构的表面积与表观面积的比值小于所述第二微浮雕结构的表面积与表观面积的比值。
  3. 根据权利要求1所述的光学防伪元件，其中，所述光学防伪元件还包括：
    覆盖在所述颜色功能层的除所述第一区域之外的第二区域上的第二微浮雕结构，所述第一微浮雕结构的起伏高度小于所述第二微浮雕结构的起伏高度。
  4. 根据权利要求1至3中任意一项权利要求所述的光学防伪元件，其中，所述第一微浮雕结构的至少一部分的深度满足以下条件：
    当所述光束以一入射角照射所述第一微浮雕结构的至少一部分时，该光束通过该微浮雕结构的至少一部分后，该光束中一波长或波长范围的光在反射光方向上干涉相长，由此所述光学防伪元件的至少一部分在反射光方向上呈现第一颜色。
  5. 根据权利要求4所述的光学防伪元件，其中，所述第一微浮雕结构的至少一部分的图案为以下中的至少一种或任意组合：
    所述第一微浮雕结构的浮雕单元随机或伪随机分布；
    所述第一微浮雕结构的浮雕单元在一个方向随机或伪随机分布；以及
    所述第一微浮雕结构的浮雕单元在第一方向周期分布，在第二方向随机或伪随机分布。
  6. 根据权利要求5所述的光学防伪元件，其中，在所述第一微浮雕结构的至少一部分的图案为所述第一微浮雕结构的至少一部分的浮雕单元随机或伪随机分布的情况下，该第一微浮雕结构的至 少一部分的特征尺寸为0.3μm-6μm，优选为0.6μm-3μm，该微浮雕结构的至少一部分的深度还满足以下条件：
    当所述光束以一入射角照射所述第一微浮雕结构的至少一部分时，所述光学防伪元件的至少一部分在散射光方向上呈现第二颜色。
  7. 根据权利要求5所述的光学防伪元件，其中，在所述第一微浮雕结构的至少一部分的图案为所述第一微浮雕结构的至少一部分的浮雕单元在第二方向随机或伪随机分布的情况下，该第一微浮雕结构的至少一部分在该第二方向的特征尺寸为0.3μm-6μm，优选为0.6μm-3μm，在第一方向的特征尺寸大于6μm，优选大于10μm，该第一微浮雕结构的至少一部分的深度还满足以下条件：
    当所述光束以一入射角照射所述第一微浮雕结构的至少一部分时，如果所述光束在与所述基层所在平面垂直并包含所述第二方向的第一平面内，则所述光学防伪元件的至少一部分在该第一平面内散射光方向上呈现第二颜色。
  8. 根据权利要求5所述的光学防伪元件，其中，在所述第一微浮雕结构的至少一部分的图案为所述第一微浮雕结构的至少一部分的浮雕单元在第一方向周期分布，在第二方向随机或伪随机分布的情况下，该第一微浮雕结构的至少一部分在该第一方向的特征尺寸为0.3μm-6μm，优选为0.6μm-3μm，在该第二方向的特征尺寸为0.3μm-6μm，优选为0.6μm-3μm，该微浮雕结构的至少一部分的深度还满足以下条件：
    当所述光束以一入射角照射所述第一微浮雕结构的至少一部分时，如果所述光束在与所述基层所在平面垂直并包含所述第二方向的第一平面内，则所述光学防伪元件的至少一部分在该第一平面内散射光方向上呈现第二颜色；如果所述光束在与所述基层所在平面垂直并包含所述第一方向的第二平面内，则所述光学防伪元件的至少一部分在该第二平面内的衍射光方向上呈现随角度变化+1级或-1级衍射光颜色。
  9. 根据权利要求1至3中任意一项权利要求所述的光学防伪元件，其中，所述颜色功能层为油墨、颜料、染料中的一种或几种的组合。
  10. 根据权利要求1至3中任意一项权利要求所述的光学防伪元件，其中，所述颜色功能层为液晶光变层。
  11. 根据权利要求1至3中任意一项权利要求所述的光学防伪元件，其中，所述颜色功能层为多层共挤光变膜。
  12. 根据权利要求1至3中任意一项权利要求所述的光学防伪元件，其中，所述颜色功能层为 干涉型多层膜结构，该干涉型多层膜结构形成法布里-泊罗谐振腔。
  13. 根据权利要求1所述的光学防伪元件，其中，所述镀层为金属反射层。
  14. 根据权利要求1所述的光学防伪元件，其中，所述第一微浮雕结构的浮雕单元的剖面为以下任意一种：正弦形、锯齿形、或矩形。
  15. 根据权利要求1所述的光学防伪元件，其中，所述光学防伪元件还包括：
    覆盖在所述第一区域的除所述第一微浮雕结构之外的其它部分上的全息图像。
  16. 一种光学防伪产品，包括根据权利要求1至15中任意一项权利要求所述的光学防伪元件。
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