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WO2020187286A1 - 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
WO2020187286A1
WO2020187286A1 PCT/CN2020/080180 CN2020080180W WO2020187286A1 WO 2020187286 A1 WO2020187286 A1 WO 2020187286A1 CN 2020080180 W CN2020080180 W CN 2020080180W WO 2020187286 A1 WO2020187286 A1 WO 2020187286A1
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WO
WIPO (PCT)
Prior art keywords
micro
relief structure
optical anti
counterfeiting
relief
Prior art date
Application number
PCT/CN2020/080180
Other languages
English (en)
French (fr)
Inventor
张宝利
蹇钰
朱军
Original Assignee
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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Filing date
Publication date
Application filed by 中钞特种防伪科技有限公司, 中国印钞造币总公司 filed Critical 中钞特种防伪科技有限公司
Publication of WO2020187286A1 publication Critical patent/WO2020187286A1/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
    • B44F1/02—Designs or pictures characterised by special or unusual light effects produced by reflected light, e.g. matt surfaces, lustrous surfaces
    • B44F1/04—Designs or pictures characterised by special or unusual light effects produced by reflected light, e.g. matt surfaces, lustrous surfaces after passage through surface layers, e.g. pictures with mirrors on the back
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/18—Diffraction gratings

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.
  • the front and back images are formed by two processes. In this case, it is difficult to avoid position errors between the two processed images , That is, the correlation between the front and back images is reduced, and the processing technology is too complicated, it is not easy to mass produce the product, and the cost is high;
  • the purpose of the present invention is to provide an optical anti-counterfeiting element and an optical anti-counterfeiting product for solving or at least partially solving the above technical problems.
  • the present invention provides an optical anti-counterfeiting element
  • the optical anti-counterfeiting element includes: a base layer, the surface of the base layer includes a first area; at least covering the first area and at least translucent first micro-relief structure; A plating layer that covers at least a part of the first micro-relief structure in the same shape; and a first coating that at least partially covers the plating layer and is at least translucent; wherein the refractive index of the first micro-relief structure is the same as that of the first coating.
  • the refractive index of the layers is different, and the depth of at least a part of the first micro-relief structure satisfies the following condition: when a light beam irradiates at least a part of the first micro-relief structure at an incident angle, the light beam passes through the first micro-relief structure After at least a part of the light beam, light of a wavelength or wavelength range in the light beam interferes constructively in the reflected light direction, so that at least a part of the optical anti-counterfeiting element presents the first color in the reflected light direction.
  • the present invention also provides an optical anti-counterfeiting product, including the above-mentioned optical anti-counterfeiting element.
  • the optical anti-counterfeiting element of the present invention has at least the following advantages: (1) The images on the front and back of the anti-counterfeiting element are formed at one time during the processing of the micro-relief structure, so the images on the front and the back are related to each other regardless of position or content. Simplify the processing process; (2) The color characteristics of the front and back images are different, thereby ensuring the visual uniqueness of the anti-counterfeiting component.
  • 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
  • Fig. 1e shows a schematic diagram of images provided on the front and back sides of the optical security element shown in Fig. 1a;
  • FIGS. 2a to 2b show an optical security element according to another embodiment of the present invention.
  • 3a to 3c show an optical security element according to another embodiment of the present invention.
  • FIG. 4d shows a schematic top view of the front and back sides of the optical security element shown in FIG. 4c;
  • Figure 5 shows a cross-sectional view of an optical security element according to yet another embodiment of the present invention.
  • Fig. 6 shows a cross-sectional view of an optical security element according to another 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.
  • the present invention provides an optical anti-counterfeiting element.
  • the optical anti-counterfeiting element includes: a base layer, the surface of the base layer includes a first area; a first micro-relief structure covering at least the first area and at least translucent; A micro-relief structure at least a part of the coating; and a first coating at least partially covering the coating and at least translucent; wherein the refractive index of the first micro-relief structure is different from the refractive index of the first coating
  • the depth of at least a part of the first micro-relief structure satisfies the following condition: when a light beam irradiates at least a part of the first micro-relief structure at an incident angle, after the light beam passes through at least a part of the first micro-relief structure, The light of one wavelength or wavelength range in the light beam interferes constructively in the reflected light direction, so that at least a part of the optical anti-counterfeiting element presents the first color in the reflected light
  • the optical anti-counterfeiting element of the present invention has at least the following advantages: (1) The images on the front and back of the anti-counterfeiting element are formed at one time during the processing of the micro-relief structure, so the images on the front and the back are related to each other regardless of position or content. Simplify the processing process; (2) The color characteristics of the front and back images are different, thereby ensuring the visual uniqueness of the anti-counterfeiting component.
  • the surface of the base layer may be the upper surface or the lower surface of the base layer, and the first area may be the entire surface of the base layer, or may be a partial area of the surface of the base layer. If the first area is a partial area of the surface of the base layer, other areas on the surface of the base layer except the first area may be covered with other types of micro-relief structures.
  • the optical anti-counterfeiting element provided by the present invention will be schematically described below in conjunction with FIGS. 1a to 6.
  • Figures 1a to 1b show an optical anti-counterfeiting element 1 according to an embodiment of the present invention, which is described with an example in which the first area of the base layer surface is the entire base layer surface.
  • the optical anti-counterfeiting element 1 may include: a base layer 101; a micro-relief structure 102 located on the base layer 101 and at least partially covering the base layer, and a plating layer 104 at least partially covering the surface of the micro-relief structure 102;
  • the coating 103 covering the plating layer 104 covers the micro-relief structure 102 in the same shape, the micro-relief structure 102 and the coating 103 are at least semi-transparent, and the micro-relief structure 102 is
  • the coating 103 has a different refractive index.
  • the depth of at least a part of the micro-relief structure 102 satisfies the following condition: when a light beam illuminates at least a part of the micro-relief structure 102 at an incident angle, after the light beam passes through at least a part of the micro-relief structure 102, a wavelength or The light in the wavelength range interferes constructively in the reflected light direction, so that at least a part of the optical anti-counterfeiting element 1 presents the first color in the reflected light direction.
  • the sample containing this feature provides images with different color features but content-related images on the front side (positive z-axis coordinate) and the negative side (negative z-axis coordinate).
  • the color features are composed of the micro-relief structure 102 and the plating layer 104.
  • the coating 103 is jointly determined, and the difference in color characteristics between the front and back sides is determined by the difference in refractive index between the micro-relief structure 102 and the coating 103.
  • the base layer 101 can be, for example, a transparent material such as PET, PVC, PE, etc., or a carrier such as paper, printed matter, and packaging.
  • the base layer 101 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 plating layer 104 may also be an interference type multilayer film structure.
  • 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.
  • 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 to 6 ⁇ m, preferably 0.6 ⁇ m to 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% to 80% of the total area of the micro-relief structure 102, preferably 35% to 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. Those skilled in the art can understand that 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 reflected The light directions interfere constructively, so that when the optical security element 1 is viewed in the reflected light direction, the first color appears, and when the optical security element 1 is viewed in the scattered light direction, the second color appears (as shown in FIG. 1a).
  • the depth d of the micro-relief structure 102 is generally between 100 nm and 5 ⁇ m, preferably 200 nm to 3 ⁇ m.
  • the depth d can be determined by the following method.
  • the anti-counterfeiting element 1 presents magenta in the reflected light direction on the reverse side (z-axis negative direction), and its complementary color in the scattered light direction is green.
  • the difference in color characteristics between the front side (positive z-axis) and the negative side (negative z-axis) of the optical security element 1 is determined by the difference in refractive index between the micro-relief structure 102 and the coating 103.
  • the micro-relief structure 102 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 sample containing the optical anti-counterfeiting element provides images with different color features but content-related images on the front side (positive z-axis coordinate) and the negative side (negative z-axis coordinate).
  • the color features are formed by the micro-relief structure 102 .
  • the plating layer 104 and the coating layer 103 are jointly determined, and the difference in color characteristics between the front and back sides is determined by the difference in refractive index between the micro-relief structure 102 and the coating 103.
  • optical anti-counterfeiting element 1 of the present invention The advantages of the optical anti-counterfeiting element 1 of the present invention will be specifically described below:
  • Optical anti-counterfeiting components must not only be easy to identify and difficult to forge, but also have the feasibility of low-cost mass production and industrial production.
  • the image content provided on the front and back sides of the micro-relief structure 102 is the same. As shown in FIG. 1e, the image on the front and back of the optical anti-counterfeiting element The images are consistent.
  • the depth d of the micro-relief structure 102 on the front and back sides is the same, and the refractive index of the micro-relief structure 102 and the coating 103 are different, this makes the reflected light interference constructive conditions change, and the scattered light as the complementary color of the reflected light is also corresponding Has changed. All in all, the content of the front and back images are related, but the color characteristics are different.
  • the anti-counterfeiting element 1 appears red in the direction of reflected light and blue-green in the direction of scattered light.
  • another image needs to be processed on the other side of the window to achieve the difference between the anti-counterfeiting features on both sides.
  • this method of production increases the number of processing times and increases the cost.
  • the existence of alignment processing errors cannot satisfy that the anti-counterfeiting features on both sides have sufficient relevance.
  • micro-relief structure 102 and the coating 103 with different refractive indexes adopted in the optical anti-counterfeiting element 1 of the present invention effectively solve the above-mentioned problems, so that under the same micro-relief structure depth d, the optical anti-counterfeiting
  • the front and back of the component can present different color characteristics.
  • the refractive index of the common polymer material coating is around 1.50, and the fluctuation range is ⁇ 0.02, which can modulate the depth d of the micro-relief structure 102 At 0.04 ⁇ d, the modulation of the constructive wavelength range of the reflected light interference is relatively limited, and it is difficult to meet the purpose of color feature contrast between the front and the back.
  • the present invention further provides a specific configuration of the micro-relief structure 102 and the coating 103 with a refractive index difference:
  • the main resin of the micro-relief structure 102 and the coating 103 may be doped with silicon oxide, and adjusting the doping ratio of silicon oxide can adjust the refractive index of the micro-relief structure 102 and the coating 103 to be between 1.45 and 1.58, for example;
  • the main resin of the micro-relief structure 102 and the coating 103 may be doped with physical holes, and the physical holes are wrapped with air. Adjusting the doping ratio of the physical holes in the main resin can adjust the micro-relief structure 102 and the coating
  • the refractive index of 103 is, for example, between 1.40 and 1.46;
  • the main resin of the micro-relief structure 102 and the coating 103 may be doped with fluoride with a low refractive index (for example, lower than 1.70), and adjusting the doping ratio of the fluoride in the main resin can adjust the micro-relief structure 102
  • the refractive index of the coating 103 is, for example, between 1.30 and 1.40;
  • the main resin of the micro-relief structure 102 and the coating layer 103 can have a high refractive index of 1.70, for example, the refractive index of the micro-relief structure 102 and the coating layer 103, which are mixed with a curing agent and other materials, can be adjusted in the range of Between 1.50 and 1.60;
  • the main resin of the micro-relief structure 102 and the coating 103 can be doped with a high refractive index (for example, higher than 1.70) oxide, such as zirconia, and the micro-relief structure 102 and the coating can be adjusted by adjusting the doping ratio.
  • the refractive index of the layer 103 is 1.60 or more.
  • the refractive index of the micro-relief structure 102 and the coating 103 can be measured by an Abbe refractometer or an ellipsometer, and the resin composition can be adjusted according to the result.
  • the coating 103 may be coated on the plating layer 104 by printing. It should be understood that the thickness of the coating 103 only needs to be able to fill the gap of the depth d of the micro-relief structure in the corresponding area, and the excess thickness of the coating will not affect the color features provided on the front of the optical security element. Therefore, in the actual processing process, the thickness of the coating 103 can be accurately controlled not to be greater than the depth d to save costs.
  • the refractive index difference between the micro-relief structure 102 and the coating 103 is not less than 0.04, and further preferably, the refractive index difference is not less than 0.1.
  • the optical anti-counterfeiting element 2 may include: a base layer 201; a plating layer 204 located on the base layer 201 and at least partially covering the base micro-relief structure 202, at least partially covering the surface of the micro-relief structure 202;
  • the coating 203 of the plating layer 204 covers the micro-relief structure 202 in the same shape, and the micro-relief structure 202 and the coating 203 are at least semi-transparent and have different refractive indexes.
  • the depth of at least a part of the micro-relief structure 202 satisfies the following conditions: when a light beam irradiates at least a part of the micro-relief structure 202 at an incident angle, after the light beam passes through at least a part of the micro-relief structure 202, a wavelength or The light in the wavelength range interferes constructively in the reflected light direction, so that at least a part of the optical anti-counterfeiting element 2 presents the first color in the reflected light direction.
  • 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 to 6 ⁇ m, preferably 0.6 ⁇ m to 3 ⁇ m, and the pattern may be randomly or pseudo-randomly distributed.
  • the raised portion of the micro-relief structure 202 may account for 20% to 80% of the total area of the micro-relief structure 202, preferably 35% to 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 reflected The light direction interferes constructively, so that the optical security element 2 observes the first color in the reflected light direction.
  • the optical anti-counterfeiting element 2 observes the second color in the direction of the scattered light in the Yoz plane (or a plane parallel to the Yoz plane).
  • the optical path length of the front side (positive z-axis) is n 1 ⁇ d
  • the optical length of the back side (negative z-axis) is n 2 ⁇ d
  • the depth d of the micro-relief structure 202 is generally between 100 nm and 5 ⁇ m, preferably between 200 nm and 3 ⁇ m.
  • the method for determining the depth d is the same as that in the foregoing embodiment, and will not be repeated here.
  • the other features and beneficial effects of the optical anti-counterfeiting element 2 are the same as those of the optical anti-counterfeiting element 1, and will not be repeated here.
  • the optical anti-counterfeiting element 3 may include: a base layer 301; a micro-relief structure 302 located on the base layer 301 and at least partially covering the base layer; a plating layer 304 at least partially covering the surface of the micro-relief structure 302; at least partially covering In the coating 303 of the plating layer, the coating layer 304 covers the micro-relief structure 302 in the same shape, and the micro-relief structure 302 and the coating 303 are at least semi-transparent and have different refractive indexes.
  • the depth of at least a part of the micro-relief structure 302 satisfies the following conditions: when a light beam irradiates at least a part of the micro-relief structure 302 at an incident angle, after the light beam passes through at least a part of the micro-relief structure 302, a wavelength or The light in the wavelength range interferes constructively in the reflected light direction, so that at least a part of the optical anti-counterfeiting element 3 presents the first color in the reflected light direction.
  • the micro-relief structure 302 may be located on the xoy plane (or a plane parallel to the xoy plane), and the feature size in the y-axis direction may be, for example, 0.3 ⁇ m to 6 ⁇ m, preferably 0.6 ⁇ m to 3 ⁇ m, and the pattern may be Randomly or pseudo-randomly distributed, the feature size in the x-axis direction may be 0.3 ⁇ m to 6 ⁇ m, preferably 0.6 ⁇ m to 3 ⁇ m, and the pattern may be, for example, a periodic structure.
  • the raised portion of the micro-relief structure 302 may account for 20% to 80% of the total area of the micro-relief structure 302, preferably 35% to 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 anti-counterfeiting element 3 observes the first color in the reflected light direction.
  • the optical security element 3 observes the 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 optical path length of the front side (positive z-axis) is n 1 ⁇ d
  • the optical length of the back side (negative z-axis) is n 2 ⁇ d
  • the depth d of the micro-relief structure 302 is usually between 100 nm and 5 ⁇ m, preferably between 200 nm and 3 ⁇ m.
  • the method for determining the depth d is the same as that in the foregoing embodiment, and will not be repeated here.
  • the other features and beneficial effects of the optical anti-counterfeiting element 3 are the same as those of the optical anti-counterfeiting element 1, and will not be repeated here.
  • optical anti-counterfeiting element has higher uniqueness and easy identification and difficult to forge attributes.
  • the optical anti-counterfeiting element provided by the present invention can also be covered with other types of micro-relief structures on the surface of the base layer, which will be described below with reference to FIGS. 4a to 6.
  • the optical anti-counterfeiting element 4 may include a base layer 401, which is located on the base layer 401 and at least partially covers the micro-relief structure 402 in area A and the micro-relief structure 4021 in area B of the base layer 401;
  • the plating layer 404 on the surface of the micro-relief structure 402; the coating 403 at least partially covering the plating layer 404, the plating layer 404 covers the micro-relief structure 402 in the same shape, and the micro-relief structure 402 and the coating 403 are at least translucent , And has a different refractive index.
  • the micro-relief structure 402 is defined as when a light beam illuminates the micro-relief structure 402 at an incident angle, light of a wavelength or wavelength range in the light beam interferes constructively in the direction of the reflected light.
  • the ratio of the surface area to the apparent area of the micro-relief structure 402 is smaller than the ratio of the surface area to the apparent area of the micro-relief structure 4021. That is, the area covered by the plating layer 404 is determined by the difference in the ratio of the surface area to the apparent area of the micro-relief structure 402 and the micro-relief structure 4021.
  • the micro-relief structure 402 and the micro-relief structure 4021 are composed of surface undulation structures whose height on the xoy plane fluctuates with position distribution. Compared with a flat surface, the surface undulation structure has a higher value per apparent area. 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 an orthographic projection in a plane parallel to the area in a certain area, that is, the area ignoring the undulating structure in the area; the term "surface area” refers to Consider the actual area of the undulating structure in a certain area. Obviously, the ratio of the surface area of a certain area to its apparent area is a value not less than 1.
  • the selection range of the micro-relief structure 402 is the same as that of the micro-relief structure in the embodiment of FIG. 1, and will not be repeated here.
  • the micro-relief structure 4021 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 402 in the x-axis and y-axis directions is 2.8 ⁇ m
  • the cross-sectional shape of the micro-relief structure 402 is sinusoidal
  • the micro-relief structure 4021 is a sinusoidal grating with an arrangement period of 350 nm and a depth of 300 nm.
  • the processing process of the optical anti-counterfeiting element 4 shown in Fig. 4a is as follows:
  • Step 1 Use a laser etching process to make an optical original plate containing the micro-relief structure 402 and the micro-relief structure 4021, and electroform it into a metal plate roll, and use a molding process on the lower surface of the base layer to copy the micro-relief structure on the metal plate roll into
  • the micro-relief structure 402 and the micro-relief structure 4021, the refractive index of the material forming the micro-relief structure may be around 1.48.
  • Step 2 Evaporate a plating layer 404 on the surfaces of the micro-relief structure 402 and the micro-relief structure 4021, and the plating layer may be, for example, a 50-nm-thick metal aluminum film reflective layer.
  • Step 3 Immerse the structure formed in Step 2 into a solution capable of dissolving the coating.
  • the solution may be, for example, a sodium hydroxide aqueous solution with a concentration of about 5% at 40°C until the coating on the surface of the micro-relief structure 4021 (for example, a metal aluminum film) The reaction of the reflective layer) is completed, so that the plating layer 404 accurately covers the micro-relief structure 402, thereby forming a precise hollow pattern.
  • Step 4 Print a coating 403 with a refractive index of 1.61 on the surface of the coating 404 in the area A.
  • the part of the area A of the optical anti-counterfeiting element 4 is the coating 403 and the micro-relief structure 402 on the upper and lower sides of the coating 404, and the difference in refractive index makes the front and back of the area A provide different color features and associated patterns.
  • Area B provides a hollow feature, and the hollow area is determined by the difference between the surface area of the micro-relief structure 402 and the micro-relief structure 4021 to the apparent area ratio. Therefore, the images provided by the hollow area B and area A are strictly error-free and accurate. Counterpoint.
  • FIG. 4b Another configuration of the optical anti-counterfeiting element 4 is shown in FIG. 4b, which may include: a base layer 401 located on the base layer 401 and at least partially covering the micro-relief structure 402 in the area A and the micro-relief structure 402 in the area B of the base layer 401 Relief structure 4021, a plating layer 404 covering the surface of the micro-relief structure 402; a coating 403 covering at least a part of the plating layer 404, the plating layer 404 covering the micro-relief structure 402 in the same shape, the micro-relief structure 402 and
  • the coating 403 is at least semi-transparent and has different refractive indexes.
  • the micro-relief structure 402 is defined as when a light beam illuminates the micro-relief structure 402 at an incident angle, light of a wavelength or wavelength range in the light beam interferes constructively in the direction of the reflected light.
  • the undulation height of the micro-relief structure 402 is smaller than the undulation height of the micro-relief structure 4021. That is, the area covered by the plating layer 404 is determined by the difference between the undulation heights of the micro-relief structure 402 and the micro-relief structure 4021.
  • the selection range of the micro-relief structure 402 is the same as that of the micro-relief structure in the embodiment of FIG. 1, and will not be repeated here.
  • the micro-relief structure 4021 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 402 in the x-axis and y-axis directions is 4.0 ⁇ m
  • the cross-sectional shape of the micro-relief structure 402 is rectangular
  • the external medium is Air
  • d 600nm.
  • the micro-relief structure 4021 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 anti-counterfeiting element 4 shown in Fig. 4b is as follows:
  • Step 1 Use a laser etching process to make an optical original plate containing the micro-relief structure 402 and the micro-relief structure 4021, and electroform it into a metal plate roll, and use a molding process on the lower surface of the base layer to copy the micro-relief structure on the metal plate roll into
  • the micro-relief structure 402 and the micro-relief structure 4021, the refractive index of the material forming the micro-relief structure is around 1.48.
  • Step 2 A plating layer 404 is vapor-deposited on the surfaces of the micro-relief structure 402 and the micro-relief structure 4021, and the plating layer may be a metal aluminum thin film reflective layer with a thickness of 50 nm.
  • Step 3 Coating a coating 403 on the entire surface of the plating layer 404.
  • the coating 403 completely covers the micro-relief structure 402, but does not completely cover the protruding part of the micro-relief structure 4021.
  • the refractive index of the coating 404 may be 1.62.
  • Step 4 Immerse the structure formed in Step 3 into a solution that can dissolve the coating 404 but cannot dissolve the coating 403.
  • the solution may be, for example, a sodium hydroxide aqueous solution with a concentration of about 10% at 40°C until the micro-relief structure
  • the plating layer on the surface of 4021 (for example, the reflective layer of the metal aluminum film) is not dissolved until the plating layer 404 accurately covers the micro-relief structure 402, thereby forming a precise hollow pattern.
  • the specific reaction process is: the coating 403 does not completely cover the plating layer 404 on the micro-relief structure 4021, so the environment is reacted with the exposed plating layer 404 on the micro-relief structure 8022 to achieve hollowing out of the area.
  • the next stage of this reaction process is that the environment is centered on the exposed plating layer 404 in the micro-relief structure 4021 and penetrates into the plating layer covered by the coating 403 on both sides, thereby further interacting with the micro-relief structure 4021.
  • the coating 804 covered by the coating 403 reacts to be translucent, and even becomes fully transparent as the reaction process continues.
  • the coating 404 on the micro-relief structure 402 is completely covered by the coating 403, so that it does not participate in the reaction and is retained.
  • the part where the optical anti-counterfeiting element area A is located is the coating 403 and the micro-relief structure 402 on the upper and lower sides of the coating 404 respectively, and the difference in refractive index makes the front and back of the area A provide different color features and associated patterns.
  • Area B provides a hollow feature, and the hollow area is determined by the difference between the surface area of the micro-relief structure 402 and the micro-relief structure 4021 to the apparent area ratio. Therefore, the image provided by the hollow area B and area A of the optical security element is strictly Accurate alignment without errors.
  • Fig. 4c is an embodiment of the optical security element 4 formed by further adding a coating 4021' to the surface of the optical security element 4 in Fig. 4a or 4b.
  • the coating 4021’ is combined with a micro-relief structure 404 and a micro-relief structure
  • the refractive index of 4021 is approximately the same, so that the micro-relief structure 4021 in the area B is covered, so that the area B has an at least semi-transparent hollow feature without the influence of the micro-relief structure.
  • the coating 4021' can have the same refractive index as the micro-relief structure 4021, thereby further ensuring the transparency of the covering micro-relief structure 4021.
  • Figure 4d shows a top view of the front (front: positive z-axis) and reverse (back: negative z-axis) of the optical anti-counterfeiting element shown in Figure 4c on the xoy plane, in which the micro-relief structure 402 and the coating covering the surface thereof
  • the front and back sides formed by 404 and the coating 403 are related and have different color characteristics in the area A, and the area not covered by the plating 404—the hollow area is in the area B.
  • the processing of the plating layer 404, the formation of the hollow pattern, the micro-relief structure 402 and the micro-relief structure 4021 are implemented in different processes, position errors inevitably occur between them.
  • the optical anti-counterfeiting element 4 of the present invention solves this problem. Therefore, strictly controlling the area covered by the plating layer 404 is only in the area A where the micro-relief structure 402 is located. This feature gives the optical anti-counterfeiting element 4 stronger uniqueness and stronger Anti-counterfeiting capability.
  • optical anti-counterfeiting element 4 The other features and beneficial effects of the optical anti-counterfeiting element 4 are the same as those of the optical anti-counterfeiting element 1, which will not be repeated here.
  • FIG. 5 is an optical security element 5 according to another embodiment of the present invention, which includes a base layer 501, located on the base layer 501 and at least partially covering the micro-relief structure 502 in the area A and the micro-relief in the area B of the base layer 501 Structure 5022, coating 504 covering the surface of said micro-relief structure 502 and micro-relief structure 5022; coating 503 at least partially covering said coating 504, said coating 504 covering said micro-relief structure 502 and micro-relief structure in the same shape 5022, the micro-relief structure 502, the micro-relief structure 5022 and the coating 503 are at least translucent, the micro-relief structure 502 and the micro-relief structure 5022 have substantially the same refractive index, and the micro-relief structure 502 and the coating The layer 503 has different refractive indices.
  • the micro-relief structure 502 is defined as when a light beam illuminates the micro-relief structure 502 at an incident angle, light of a wavelength or wavelength range in the light beam interferes constructively in the direction of the reflected light.
  • the micro-relief structure 5022 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 anti-counterfeiting features presented by the optical anti-counterfeiting element 5 are: the images on the front and back sides of the area A are related but the color features are different, and the images on the front and back sides of the area B are related and the color features are the same.
  • the reason for the formation of this feature is that the depth of the micro-relief structure 5022 of the region B does not meet the condition of the reflected light interference constructively, so its optical anti-counterfeiting feature is not sensitive to the refractive index of the coating 503 or the micro-relief structure 5022.
  • the selection range of the micro-relief structure 502 is the same as that of the micro-relief structure in the embodiment of FIG. 1, and will not be repeated here.
  • the depth d of the micro-relief structure 502 is usually between 100 nm and 5 ⁇ m, preferably between 200 nm and 3 ⁇ m.
  • the method for determining the depth d is the same as that in the foregoing embodiment, and will not be repeated here.
  • the other features and beneficial effects of the optical anti-counterfeiting element 5 are the same as those of the optical anti-counterfeiting element 1, and will not be repeated here.
  • Fig. 6 is an optical security element 6 according to another embodiment of the present invention.
  • the optical security element 6 includes a base layer 601 on the base layer 601 and at least partially covers the micro-relief structure 602 in the region A and the base layer 601.
  • the micro-relief structure 6022 in area B, the plating layer 604 covering the surface of the micro-relief structure 602 and the micro-relief structure 6022; the coating 603 at least partially covering the plating layer 604, the plating layer 604 covers the micro-relief structure in the same shape 602 and the micro-relief structure 6022, the micro-relief structure 602, the micro-relief structure 6022 and the coating 603 are at least semi-transparent, and the micro-relief structure 602 and the micro-relief structure 6022 have approximately the same refractive index, the micro-relief structure 602 and the coating 603 has a different refractive index.
  • the area C is a hollow area.
  • the area A and the area B in the optical security element 6 correspond to the area A and the area B of the optical security element 5 in the embodiment of FIG. 5, and the structure, features and implementation methods will not be repeated here.
  • the optical anti-counterfeiting element 6 has an area C added to the optical anti-counterfeiting element 5, and the area C is a hollow area that does not cover the plating layer 604.
  • the area C may be covered with a coating 603.
  • the structure, features, and implementation method of the area C may be the same as the structure, features, and implementation method of the area B of the optical anti-counterfeiting element 4 in the embodiment of FIGS. 4a-d, and will not be repeated here.
  • the area C shown in FIG. 6 is provided between the area A and the area B, it is understood that the area C may be provided at any position.
  • the selection range of the micro-relief structure 602 is the same as that of the micro-relief structure in the embodiment of FIG. 1, and will not be repeated here.
  • the depth d of the micro-relief structure 602 is usually between 100 nm and 5 ⁇ m, preferably between 200 nm and 3 ⁇ m.
  • the method for determining the depth d is the same as that in the foregoing embodiment, and will not be repeated here.
  • the other features and beneficial effects of the optical anti-counterfeiting element 6 are the same as those of the optical anti-counterfeiting element 1, and will not be repeated here.
  • the anti-counterfeiting element of the present application can also be hot stamping type, that is, coating a peeling layer on the substrate, and then making the anti-counterfeiting element of the present invention on the peeling layer.
  • hot stamping process is applied to transfer it to the carrier, the substrate Peel it off.
  • the anti-counterfeiting element of the present application further has other functional layers, such as a magnetic information layer, a fluorescent anti-counterfeiting feature layer, a printed pattern layer, an adhesive layer, etc.
  • the present invention also provides an optical anti-counterfeiting product, which includes the above-mentioned optical anti-counterfeiting element.
  • the anti-counterfeiting element of the present application can be transferred or pasted to the carrier in the form of being used for identification, hot stamping of wide strips, stickers, security threads, etc.
  • These carrying objects can be high-security products such as banknotes, securities, credit cards, and passports, or high-value-added products.

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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），基层（101）的表面包括第一区域；至少覆盖第一区域且至少半透明的第一微浮雕结构（102）；同形覆盖第一微浮雕结构（102）的至少一部分的镀层（104）；以及至少部分覆盖镀层（104）且至少半透明的第一涂层（103）；其中，第一微浮雕结构（102）的折射率与第一涂层（103）的折射率不同，第一微浮雕结构（102）的至少一部分的深度满足以下条件：当光束以一入射角照射所述第一微浮雕结构（102）的至少一部分时，光束通过该第一微浮雕结构（102）的至少一部分后，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。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。
当前，国际上以钞票为代表的高端防伪产品平台出现了一类炙手可热的产品形式——防伪视窗，例如自2011年开始发行的新版加拿大元系列，2013年开始发行的新版欧元系列，2015年开始发行的新版新西兰元系列，2016年开始发行的新版澳大利亚元系列均采用了防伪视窗，影响深远，广受好评。
防伪视窗的特点是两面均可观察，但是本申请发明人在实施上述现有技术的过程中发现，当 前视窗产品普遍存在以下两个方面的问题：
(1)如果采用双层结构，例如上述新版欧元系列的防伪视窗，其正面和反面的图像是通过两次加工形成的，这种情况下，两次加工的图像之间难以避免会存在位置误差，即正反面图像之间的关联度降低，同时加工工艺过于复杂，不易于产品批量生产，且成本较高；
(2)如果采用单层结构，例如上述新版加元、新西兰元和澳元系列的防伪视窗，其正面和反面的图像是一次加工形成的，这种情况下，正反面图像完全相同，不具有独特性，不具备突出的防伪功能。
发明内容
本发明的目的是提供一种光学防伪元件及光学防伪产品，用于解决或至少部分解决上述技术问题。
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，所述基层的表面包括第一区域；至少覆盖所述第一区域且至少半透明的第一微浮雕结构；同形覆盖所述第一微浮雕结构的至少一部分的镀层；以及至少部分覆盖所述镀层且至少半透明的第一涂层；其中，所述第一微浮雕结构的折射率与所述第一涂层的折射率不同，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，该光束通过该第一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。
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。
本发明的光学防伪元件至少具有以下优点：(1)防伪元件正面和反面的图像是微浮雕结构加工时一次成型的，因此正面和反面的图像无论位置抑或是内容都是相互关联的，同时也简化了加工工艺流程；(2)正面和反面图像的颜色特征是有差异的，从而保证了防伪元件的视觉独特性。
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1e示出了图1a所示的光学防伪元件的正面和反面提供的图像的示意图；
图2a至图2b示出了根据本发明的另一个实施方式的光学防伪元件；
图3a至图3c示出了根据本发明的又一个实施方式的光学防伪元件；
图4a至图4c示出了根据本发明的又一个实施方式的光学防伪元件；
图4d示出了图4c所示的光学防伪元件的正面和反面的俯视示意图；
图5示出了根据本发明的又一个实施方式的光学防伪元件的剖面图；以及
图6示出了根据本发明的又一个实施方式的光学防伪元件的剖面图。
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。
本发明提供一种光学防伪元件，该光学防伪元件包括：基层，所述基层的表面包括第一区域；至少覆盖所述第一区域且至少半透明的第一微浮雕结构；同形覆盖所述第一微浮雕结构的至少一部分的镀层；以及至少部分覆盖所述镀层且至少半透明的第一涂层；其中，所述第一微浮雕结构的折射率与所述第一涂层的折射率不同，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，该光束通过该第一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。
本发明的光学防伪元件至少具有以下优点：(1)防伪元件正面和反面的图像是微浮雕结构加工时一次成型的，因此正面和反面的图像无论位置抑或是内容都是相互关联的，同时也简化了加工工艺流程；(2)正面和反面图像的颜色特征是有差异的，从而保证了防伪元件的视觉独特性。
所述基层表面可以是基层的上表面或下表面，所述第一区域可以是所述基层表面的整体，或者可以是所述基层表面的部分区域。如果所述第一区域为所述基层表面的部分区域，则在所述基层表面除所述第一区域之外的其他区域上可以覆盖有其他类型的微浮雕结构。下面将结合图1a至图6对本发明提供的光学防伪元件进行示意性的描述。
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1，其是以基层表面的第一区域是整个基层表面为例进行说明的。如图1所示，光学防伪元件1可以包括：基层101；位于基层101上且至少部分覆盖所述基层的微浮雕结构102，至少部分覆盖在所述微浮雕结构102表面的镀层104；至少部分覆盖所述镀层104的涂层103，所述镀层104同形覆盖于所述微浮雕结构102，所述微浮雕结构102与所述涂层103是至少半透明的，并且微浮雕结构102与所述涂层103具有不同的折射率。微浮雕结构102的至少一部分的深度满足以下条件：当光束以一入射角照射所述微浮雕结构102的至少一部分时，该光束通过该微浮雕结构102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1的至少一部分在反射光方向上呈现第一颜色。
通过上述技术方案，可以实现一种明显区别于衍射光变图像的防伪产品。含有该特征的样品在正面(z轴坐标正向)和反面(z轴坐标负向)分别提供了不同的颜色特征但内容相关联的图像，所述颜色特征是由微浮雕结构102、镀层104以及涂层103共同来决定的，所述正反两面之间的颜色特征差异则是由微浮雕结构102和涂层103的折射率之差来确定。
所述基层101可以例如为PET、PVC、PE等透明材料，也可以是纸张、印刷品、包装等载体。所述基层101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还可以是干涉型多层膜结构。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。
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至6μm，优选为0.6μm至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％至80％，优选为35％至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至5μm之间，优选为200nm至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、覆盖在镀层104表面的涂层1031和1032的材料折射率分布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的折射率n＝1.5，其剖面形状为正弦形，外部介质为空气，则d＝2668.8nm时，波长为410.8nm的光满足反射光干涉相长条件，因此防伪元件1在反面(z轴负向)的反射光方向上呈现洋红色，散射光方向上呈现其补色——绿色，正面(z轴正向)由于涂层103折射率n＝1.63，其干涉相长条件发生了偏移，反射光方向上呈现绿色，散射光方向上呈现其补色——洋红色。
光学防伪元件1正面(z轴正向)和反面(z轴负向)的颜色特征差异是由微浮雕结构102和涂层103的折射率差异决定的。
微浮雕结构102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。
通过上述技术方案，可以实现一种明显区别于衍射光变图像的防伪产品。含有该光学防伪元件的样品在正面(z轴坐标正向)和反面(z轴坐标负向)分别提供了具有不同的颜色特征但内容相关联的图像，所述颜色特征是由微浮雕结构102、镀层104以及涂层103共同来决定的，所述正反两面之间的颜色特征差异则是由微浮雕结构102和涂层103的折射率之差来确定。
下面将具体说明本发明的光学防伪元件1的优势：
光学防伪元件不仅要易于识别和难以伪造，还要具备低成本批量化、工业化生产的可行性。在防伪元件1中，由于微浮雕结构102是一次加工完成的，其正面和反面提供的图像内容是相同的，如图1e中所示，光学防伪元件正面(front)的图像与反面(back)的图像一致。但是由于正反面微浮雕结构102的深度d相同，而微浮雕结构102与涂层103的折射率不同，这使得反射光干涉相长条件发生了变化，同时散射光作为反射光的补色也相应的发生了变化。总而言之，正反面图像内容相关，然而颜色特征却是不同的。
例如当选择d＝1528.8nm时，那么防伪元件1在反射光方向上呈现红色，在散射光方向呈现蓝绿色。按照2013年新版欧元系列中视窗的做法，需要在视窗另一面加工另外一个图像才能实现两面防伪特征的区别，然而这种制作方法一方面加工次数增加，提高了成本，另外一方面由于不同工序 间对位加工误差的存在，无法满足两面的防伪特征具有足够的关联性。本发明中所述光学防伪元件1中采用的具有不同折射率的微浮雕结构102和涂层103这一方案有效的解决了上述问题，使得在相同的微浮雕结构深度d的情况下，光学防伪元件正反面能够呈现不同的颜色特征。
在工业生产中，获得不同折射率的涂层是可能的，但是通常的高分子材料涂层折射率在1.50附近，起伏范围为±0.02，从而能够对微浮雕结构102的深度d产生的调制范围在0.04×d，对反射光干涉相长的波长范围的调制是相对有限的，难以满足正反两面颜色特征反差的目的。
为实现本发明中光学防伪元件1的正反两面呈现人眼可见的明显的颜色反差，本发明进一步提供了具有折射率差的微浮雕结构102和涂层103的具体配置：
优选地，微浮雕结构102和涂层103的主树脂中可以掺杂有氧化硅，调整氧化硅的掺杂比例能够调节微浮雕结构102和涂层103的折射率在例如1.45至1.58之间；
优选地，微浮雕结构102和涂层103的主树脂中可以掺杂有物理孔洞，所述物理孔洞包裹有空气，调整物理孔洞在主树脂中的掺杂比例能够调节微浮雕结构102和涂层103的折射率在例如1.40至1.46之间；
优选地，微浮雕结构102和涂层103的主树脂中可以掺杂有低折射率(例如，低于1.70)的氟化物，调整氟化物在主树脂中的掺杂比例能够调节微浮雕结构102和涂层103的折射率在例如1.30至1.40之间；
优选地，微浮雕结构102和涂层103的主树脂自身可以具有例如1.70的高折射率，那么结合固化剂等材料混合而成的微浮雕结构102和涂层103的折射率可调节范围在例如1.50～1.60之间；
优选地，微浮雕结构102和涂层103的主树脂中可以掺杂有高折射率(例如，高于1.70)氧化物，例如氧化锆，通过调节掺杂的比例能够调节微浮雕结构102和涂层103的折射率在1.60以上。
微浮雕结构102和涂层103的折射率可以通过阿贝折射仪或椭圆偏振光谱仪测量获得，并根据结果进行树脂组分的调整。
涂层103可以通过印刷的方式涂覆在镀层104上。应当理解，涂层103的厚度仅需要满足能够填充相应区域的微浮雕结构的深度为d的空隙即可，此外超出的部分涂层厚度将对所述光学防伪元件的正面提供的颜色特征没有影响，因此在实际加工过程中可以选择精确控制所述涂层103的厚度不大于所述深度d来节省成本。
为了获得所述光学防伪元件正面和反面较大的颜色特征差异，优选地，微浮雕结构102和涂层103的折射率差不小于0.04，进一步优选地，所述折射率差不小于0.1。
图2a和2b示出了根据本发明的一个实施方式的光学防伪元件2，其是以基层表面的第一区域是整个基层表面为例进行说明的。如图所示，光学防伪元件2可以包括：基层201；位于基层201 上且至少部分覆盖所述基层微浮雕结构202，至少部分覆盖在所述微浮雕结构202表面的镀层204；至少部分覆盖所述镀层204的涂层203，所述镀层204同形覆盖于所述微浮雕结构202，所述微浮雕结构202与所述涂层203至少半透明，并且具有不同的折射率。微浮雕结构202的至少一部分的深度满足以下条件：当光束以一入射角照射所述微浮雕结构202的至少一部分时，该光束通过该微浮雕结构202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2的至少一部分在反射光方向上呈现第一颜色。
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至6μm，优选为0.6μm至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％至80％，优选为35％至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2在yoz平面(或与yoz平面平行的平面)内散射光方向上观察到第二颜色。由于微浮雕结构202和涂层203折射率n 1和n 2的差异使正面(z轴正向)的光程为n 1×d，而背面(z轴负向)的光程为n 2×d，从而正面和背面的干涉相长条件产生了区别，相应的不论是正背面的反射光还是反射光颜色均发生了偏移，即正背面的颜色特征具有了反差。
微浮雕结构202深度d通常在100nm至5μm之间，优选为200nm至3μm。确定深度d的方法与上述实施方式中的相同，这里不再赘述。光学防伪元件2的其他特征和有益效果与光学防伪元件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光学防伪元件3，其是以基层表面的第一区域是整个基层表面为例进行说明的。如图所示，光学防伪元件3可以包括：基层301；位于基层301上且至少部分覆盖所述基层的微浮雕结构302；至少部分覆盖在所述微浮雕结构302表面的镀层304；至少部分覆盖所述镀层的涂层303，所述镀层304同形覆盖于所述微浮雕结构302，所述微浮雕结构302与所述涂层303至少半透明，并且具有不同的折射率。微浮雕结构302的至少一部分的深度满足以下条件：当光束以一入射角照射所述微浮雕结构302的至少一部分时，该光束通过该微浮雕结 构302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3的至少一部分在反射光方向上呈现第一颜色。
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至6μm，优选为0.6μm至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至6μm，优选为0.6μm至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％至80％，优选为35％至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)内散射光方向观察到第二颜色；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。由于微浮雕结构302和涂层303折射率n 1和n 2的差异使正面(z轴正向)的光程为n 1×d，而背面(z轴负向)的光程为n 2×d，从而正背面的干涉相长条件产生了区别，相应的不论是正背面的所述反射光还是反射光颜色均发生了偏移，即正背面的颜色特征具有了反差。
微浮雕结构302深度d通常在100nm至5μm之间，优选为200nm至3μm。确定深度d的方法与上述实施方式中的相同，这里不再赘述。光学防伪元件3的其他特征和有益效果与光学防伪元件1相同，这里不再赘述。
为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。本发明提供的光学防伪元件在基层表面还可以覆盖有其他类型的微浮雕结构，下面结合图4a至图6对其进行描述。
图4a至图4c示出了根据本发明的一个实施方式的光学防伪元件4。如图4a所示光学防伪元件4，可以包括基层401，位于基层401上且至少部分覆盖所述基层401的处于区域A的微浮雕结构402和处于区域B的微浮雕结构4021；覆盖在所述微浮雕结构402表面的镀层404；至少部分覆盖所述镀层404的涂层403，所述镀层404同形覆盖于所述微浮雕结构402，所述微浮雕结构402与所述涂层403至少半透明，并且具有不同的折射率。所述微浮雕结构402被定义成当光束以一入射角照射所述微浮雕结构402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。所述微浮雕结构402的表面积与表观面积的比值小于微浮雕结构4021的表面积与表观面积的比值。即镀层 404所覆盖的区域由微浮雕结构402和微浮雕结构4021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402和微浮雕结构4021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。在本发明中，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”指的是考虑到某一区域中的起伏结构的实际面积。显然，某一区域的表面积与其表观面积之比为不小于1的数值。
所述微浮雕结构402与图1实施例中微浮雕结构的选择范围相同，这里不再赘述。优选地，微浮雕结构4021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4a的实施方式中，微浮雕结构402在x轴、y轴方向的特征尺寸为2.8μm，微浮雕结构402材料的折射率n＝1.48，微浮雕结构402的剖面形状为正弦形，外部介质为空气，d＝500nm。微浮雕结构4021为正弦型光栅，其排列周期为350nm，深300nm。图4a所示的光学防伪元件4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402和微浮雕结构4021的光学原版，并电铸为金属版辊，在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402和微浮雕结构4021，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402和微浮雕结构4021表面蒸镀镀层404，所述镀层例如可以为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的溶液中，该溶液例如可以是40℃的浓度约为5％的氢氧化钠水溶液，直到微浮雕结构4021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404准确覆盖微浮雕结构402，从而形成精准镂空图形。
步骤四：在区域A的镀层404表面印刷折射率为1.61涂层403。
以上为制作图4a所示的光学防伪元件4的实施步骤。其中，光学防伪元件4区域A的部分由 于在镀层404的上下两面分别为涂层403和微浮雕结构402，其折射率差异使得区域A的正面和反面提供了不同的颜色特征和相关联的图案。区域B提供了镂空特征，并且该镂空区域是由微浮雕结构402和微浮雕结构4021的表面积与表观面积比值的差异决定的，因此镂空区域B与区域A提供的图像是严格无误差的精准对位的。
光学防伪元件4的另外一种配置方式如图4b所示，其可以包括：基层401，位于基层401上且至少部分覆盖所述基层401的处于区域A的微浮雕结构402和处于区域B的微浮雕结构4021，覆盖在所述微浮雕结构402表面的镀层404；至少部分覆盖所述镀层404的涂层403，所述镀层404同形覆盖于所述微浮雕结构402，所述微浮雕结构402与所述涂层403至少半透明，并且具有不同的折射率。所述微浮雕结构402被定义成当光束以一入射角照射所述微浮雕结构402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。所述微浮雕结构402的起伏高度小于微浮雕结构4021的起伏高度。即镀层404所覆盖的区域由微浮雕结构402和微浮雕结构4021的所述起伏高度的差异所决定。
所述微浮雕结构402与图1实施例中微浮雕结构的选择范围相同，这里不再赘述。优选地，微浮雕结构4021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4b的实施方式中，微浮雕结构402在x轴、y轴方向的特征尺寸为4.0μm，微浮雕结构402材料的折射率n＝1.48，微浮雕结构402的剖面形状为矩形，外部介质为空气，d＝600nm。微浮雕结构4021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。图4b所示的光学防伪元件4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402和微浮雕结构4021的光学原版，并电铸为金属版辊，在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402和微浮雕结构4021，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402和微浮雕结构4021表面蒸镀镀层404，所述镀层可以为50nm厚的金属铝薄膜反射层。
步骤三：在镀层404表面整体涂覆涂层403，所述涂层403完全覆盖微浮雕结构402，但不完 全覆盖微浮雕结构4021的凸起部分。所述涂层404的折射率可以为1.62。
步骤四：将步骤三形成的结构浸入能够溶解所述镀层404但是不能溶解涂层403的溶液中，所述溶液例如可以是40℃的浓度约为10％的氢氧化钠水溶液，直到微浮雕结构4021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404准确覆盖微浮雕结构402，从而形成精准镂空图形。具体反应过程为：涂层403并未完全遮盖微浮雕结构4021上的镀层404，因此使所述环境与微浮雕结构8022上裸露的镀层404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4021中裸露的镀层404为中心向由两侧的涂层403所遮盖的镀层中渗透，从而进一步与微浮雕结构4021上被涂层403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402上的镀层404被涂层403完全遮盖，因而不参与反应得以保留。
以上为制作图4b所示的光学防伪元件4的实施步骤。其中，光学防伪元件区域A所在部分由于在镀层404的上下两面分别为涂层403和微浮雕结构402，其折射率差异使得区域A的正面和反面提供了不同的颜色特征和相关联的图案。区域B提供了镂空特征，并且该镂空区域是由微浮雕结构402和微浮雕结构4021的表面积与表观面积比值的差异决定的，因此光学防伪元件的镂空区域B与区域A提供的图像是严格无误差的精准对位的。
图4c为进一步在图4a或者图4b中的光学防伪元件4的表面继续添加涂层4021’而形成的光学防伪元件4的实施例，所述涂层4021’与微浮雕结构404和微浮雕结构4021的折射率大致相同，从而将区域B中的微浮雕结构4021覆盖，使区域B达到至少半透明的镂空特征而不存在微浮雕结构的影响。例如，涂层4021’可以与微浮雕结构4021具有相同的折射率，从而进一步保证覆盖微浮雕结构4021的透明性。
图4d示出了图4c所示的光学防伪元件在xoy平面上的正面(front：z轴正向)和反面(back：z轴负向)的俯视图，其中微浮雕结构402与其表面覆盖的镀层404和涂层403共同形成的正反面相关联而又具备不同的颜色特征的图案在区域A，镀层404不覆盖的区域——镂空区域在所述区域B。通常，由于镀层404的加工、镂空图案的形成与微浮雕结构402及微浮雕结构4021是在不同工序中实现的，其相互之间不可避免地会出现位置误差。而本发明的光学防伪元件4解决了这一问题，因此严格控制镀层404覆盖的区域仅在微浮雕结构402所在的区域A这一特点赋予了光学防伪元件4更强的独特性以及更强的防伪能力。
光学防伪元件4的其他特征和有益效果与光学防伪元件1相同，这里不再赘述。
图5为根据本发明的又一个实施方式的光学防伪元件5，其包括基层501，位于基层501上且至少部分覆盖所述基层501的处于区域A的微浮雕结构502和处于区域B的微浮雕结构5022，覆盖 在所述微浮雕结构502和微浮雕结构5022表面的镀层504；至少部分覆盖所述镀层504的涂层503，所述镀层504同形覆盖于所述微浮雕结构502和微浮雕结构5022，所述微浮雕结构502、微浮雕结构5022和所述涂层503至少半透明，所述微浮雕结构502和微浮雕结构5022的折射率大致相同，所述微浮雕结构502和所述涂层503具有不同的折射率。
所述微浮雕结构502被定义成当光束以一入射角照射所述微浮雕结构502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。所述微浮雕结构5022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。
所述光学防伪元件5的结构中：
(1)在区域A和区域B采用相同的镀层504，
(2)在区域A和区域B采用相同的折射率的涂层503，
(3)在区域A的微浮雕结构502和在区域B的微浮雕结构5022的折射率相同，
所述光学防伪元件5呈现的防伪特征为：区域A的正反两面的图像相关联但颜色特征不同，区域B的正反两面的图像相关联且颜色特征相同。形成该特征的原因是区域B的微浮雕结构5022的深度由于不满足反射光干涉相长的条件，所以其光学防伪特征并不对涂层503或微浮雕结构5022的折射率敏感。
所述微浮雕结构502与图1实施例中微浮雕结构的选择范围相同，这里不再赘述。微浮雕结构502深度d通常在100nm至5μm之间，优选为200nm至3μm。确定深度d的方法与上述实施方式中的相同，这里不再赘述。光学防伪元件5的其他特征和有益效果与光学防伪元件1相同，这里不再赘述。
图6为根据本发明的又一个实施方式的光学防伪元件6，所述光学防伪元件6包括基层601，位于基层601上且至少部分覆盖所述基层601的处于区域A的微浮雕结构602和处于区域B的微浮雕结构6022，覆盖在所述微浮雕结构602和微浮雕结构6022表面的镀层604；至少部分覆盖所述镀层604的涂层603，所述镀层604同形覆盖于所述微浮雕结构602和微浮雕结构6022，所述微浮雕结构602、微浮雕结构6022和所述涂层603至少半透明，并且微浮雕结构602和微浮雕结构6022 折射率大致相同，微浮雕结构602和涂层603具有不同的折射率。所述区域C为镂空区域。
光学防伪元件6中区域A和区域B即对应图5实施方式中光学防伪元件5的区域A和区域B，这里将不赘述其结构、特征和实现方法。光学防伪元件6相对于光学防伪元件5增加了区域C，所述区域C是不覆盖镀层604的镂空区域。可选地，在区域C上可以覆盖有涂层603。或者可选地，区域C的结构、特征和实现方法可以与图4a-d的实施例中光学防伪元件4的区域B的结构、特征和实现方法一致，这里不再赘述。此外，虽然图6所示的区域C设置在区域A和区域B之间，但是可以理解，区域C可以设置在任意位置。
所述微浮雕结构602与图1实施例中微浮雕结构的选择范围相同，这里不再赘述。微浮雕结构602深度d通常在100nm至5μm之间，优选为200nm至3μm。确定深度d的方法与上述实施方式中的相同，这里不再赘述。光学防伪元件6的其他特征和有益效果与光学防伪元件1相同，这里不再赘述。
本申请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。
本申请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。
相应地，本发明还提供一种光学防伪产品，该光学防伪产品包括上述的光学防伪元件。例如，本申请的防伪元件可以采用应用于标识、烫印宽条、贴条、安全线等的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。
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 (17)

  1. 一种光学防伪元件，该光学防伪元件包括：
    基层，所述基层的表面包括第一区域；
    至少覆盖所述第一区域且至少半透明的第一微浮雕结构；
    同形覆盖所述第一微浮雕结构的至少一部分的镀层；以及
    至少部分覆盖所述镀层且至少半透明的第一涂层；
    其中，所述第一微浮雕结构的折射率与所述第一涂层的折射率不同，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，该光束通过该第一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。
  2. 根据权利要求1所述的光学防伪元件，其中，所述基层的表面还包括第二区域，所述光学防伪元件还包括：
    覆盖在所述第二区域且至少半透明的第二微浮雕结构，该第二微浮雕结构的折射率与所述第一微浮雕结构的折射率相同。
  3. 根据权利要求2所述的光学防伪元件，其中，所述第二微浮雕结构上未覆盖所述镀层。
  4. 根据权利要求3所述的光学防伪元件，其中，
    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；和/或
    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。
  5. 根据权利要求3所述的光学防伪元件，其中，所述光学防伪元件还包括：
    覆盖在所述第一涂层和所述第二微浮雕结构之上的第二涂层，该第二涂层的折射率与所述第二微浮雕结构的折射率相同。
  6. 根据权利要求2所述的光学防伪元件，其中，所述第二微浮雕结构上覆盖有所述镀层和所述第一涂层。
  7. 根据权利要求6所述的光学防伪元件，其中，所述基层表面还包括第三区域，所述第一涂层覆盖在该第三区域上。
  8. 根据权利要求2所述的光学防伪元件，其中，所述第二微浮雕结构为连续曲面型结构、矩形结构、锯齿型棱镜结构和/或它们的拼接或组合。
  9. 根据权利要求1至8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。
  10. 根据权利要求9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。
  11. 根据权利要求9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。
  12. 根据权利要求9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。
  13. 根据权利要求1至8中任意一项权利要求所述的光学防伪元件，其中，所述镀层为金属反射层或干涉型多层膜结构。
  14. 根据权利要求1至8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折射率与所述涂层的折射率之间的差值不小于0.04，优选不小于0.1。
  15. 根据权利要求1至8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深度的为100nm至5μm，优选为200nm至3μm。
  16. 根据权利要求1至8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浮雕单元的剖面为以下任意一种：正弦形、锯齿形、或矩形。
  17. 一种光学防伪产品，包括根据权利要求1至16中任意一项权利要求所述的光学防伪元件。
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