WO2021063126A1 - 光学防伪元件及防伪产品 - Google Patents

光学防伪元件及防伪产品 Download PDF

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Publication number
WO2021063126A1
WO2021063126A1 PCT/CN2020/110024 CN2020110024W WO2021063126A1 WO 2021063126 A1 WO2021063126 A1 WO 2021063126A1 CN 2020110024 W CN2020110024 W CN 2020110024W WO 2021063126 A1 WO2021063126 A1 WO 2021063126A1
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Prior art keywords
preset
color
angle
reflective facets
incidence
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PCT/CN2020/110024
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English (en)
French (fr)
Inventor
崔海波
张巍巍
张宝利
孙凯
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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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
Priority to EP20871998.9A priority Critical patent/EP4039493A4/en
Publication of WO2021063126A1 publication Critical patent/WO2021063126A1/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
    • B42D25/309—Photographs
    • 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
    • B42D25/30—Identification or security features, e.g. for preventing forgery
    • B42D25/351—Translucent or partly translucent parts, e.g. windows
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B30/00—Optical systems or apparatus for producing three-dimensional [3D] effects, e.g. stereoscopic images
    • G02B30/50—Optical systems or apparatus for producing three-dimensional [3D] effects, e.g. stereoscopic images the image being built up from image elements distributed over a 3D volume, e.g. voxels
    • G02B30/56—Optical systems or apparatus for producing three-dimensional [3D] effects, e.g. stereoscopic images the image being built up from image elements distributed over a 3D volume, e.g. voxels by projecting aerial or floating images
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/08—Mirrors
    • G02B5/09—Multifaceted or polygonal mirrors, e.g. polygonal scanning mirrors; Fresnel mirrors
    • 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 anti-counterfeiting product.
  • Image reproduction technology is an effective second-line anti-counterfeiting method. Specifically, when an appropriate light source is irradiated on the surface of the anti-counterfeiting element, specific graphic information can be observed on the corresponding receiving screen; while direct observation cannot be observed The above graphic information. Therefore, this image reproduction technology requires certain conditions to be able to observe the hidden features.
  • Traditional image reproduction technology generally uses a diffraction grating, that is, the incident light is diffracted by the surface micro-relief structure to diffract the light to a position of ⁇ 1st order.
  • the position of the diffraction spot can be controlled, and then several spots can be combined into a specific image and text.
  • due to the principle of diffraction there is ⁇ 1st order diffraction.
  • two symmetrical patterns appear on the left and right sides of the specular reflection, which limits the design of graphic information.
  • the diffraction direction is strictly related to the frequency of the incident light, the light required by the reproduction technology is generally laser light. When white light or daylight illumination is used, the clarity of the reproduced pattern is very poor.
  • white light sources are easy to obtain, especially with the popularity of smart phones, flashes have been widely used as white light illumination sources, and even sunlight, flashlights, projector light sources and other light sources can be used for white light reproduction illumination. How to realize the reproduction of color images illuminated by white light has become an urgent problem to be solved.
  • the purpose of the present invention is to provide an optical anti-counterfeiting element and an anti-counterfeiting product, which can reproduce a color preset pattern under the irradiation of white light.
  • the optical anti-counterfeiting element includes: a substrate; a plurality of reflective facets formed on the substrate for reflecting and/or transmitting incident light to A preset position to present preset graphic information at the preset position; and a color modulation structure formed on the reflective facet to modulate the light reflected and/or transmitted by the reflective facet Color, so that the preset graphic information presents a preset color.
  • the inclination angle and the azimuth angle of the plurality of reflective facets are determined by a Fresnel formula, wherein the Fresnel formula is related to the preset angle of incidence and the preset position of the incident light.
  • the plurality of reflective facets are a first group of reflective facets, and the inclination and azimuth angles of the first group of reflective facets are determined by a first Fresnel formula, wherein the first Fresnel formula Related to the first preset angle of incidence and the first preset position of the incident light, the first set of reflective facets is used to reflect and/or transmit the incident light with the first preset angle of incidence to the first A preset position to present first preset graphic information at the first preset position, and the color modulation structure is a first color modulation structure with a first modulation depth for enabling the first preset It is assumed that the graphic information presents a first preset color, and when the optical anti-counterfeiting element is illuminated by incident light having the first preset incident angle, the first preset color is presented at the first preset position A real image of the first preset graphic information.
  • the plurality of reflective facets is a second set of reflective facets, and the inclination and azimuth angles of the second set of reflective facets are determined by a second Fresnel formula, wherein the second Fresnel formula Related to the second predetermined angle of incidence and the second predetermined position of the incident light, the second set of reflective facets is used to reflect and/or transmit the incident light having the second predetermined angle of incidence to the first Two preset positions, to present second preset graphic information at the second preset position, and the color modulation structure includes: a second color modulation structure with a second modulation depth, configured to enable the second The preset graphic information presents a second preset color; and a third color modulation structure having a third modulation depth is used to make the second preset graphic information present a third preset color, and the second modulation depth Different from the third modulation depth, when the optical anti-counterfeiting element is illuminated by the incident light with the second preset angle of incidence, the second preset color and the optical anti-
  • the multiple reflective facets include: a third set of reflective facets and a fourth set of reflective facets, and the inclination and azimuth angles of the multiple reflective facets in the third set of reflective facets are determined by the third set of reflective facets.
  • the Fresnel formula determines that the inclination and azimuth angles of the multiple reflective facets in the fourth group of reflective facets are determined by the fourth Fresnel formula, wherein the third Fresnel formula is related to the incident light
  • the third preset angle of incidence is related to the third preset position
  • the fourth Fresnel formula is related to the fourth preset angle of incidence and the fourth preset position of the incident light
  • the third preset angle of incidence is related to the The fourth preset angle of incidence is different, the third preset position is different from the fourth preset position, and the third set of reflective facets is used to reflect incident light having the third preset angle of incidence And/or transmit to the third preset position to present the third preset graphic information at the third preset position
  • the fourth group of reflective facets is used to have the fourth preset
  • the incident light at the incident angle is reflected and/or transmitted to the fourth preset position to present fourth preset graphic information at the fourth preset position
  • the color modulation structure is a color
  • the multiple reflective facets include: a fifth group of reflective facets and a sixth group of reflective facets, and the inclination and azimuth angles of the multiple reflective facets in the fifth group of reflective facets are determined from the fifth group of reflective facets.
  • the Fresnel formula determines that the inclination and azimuth angles of the multiple reflective facets in the sixth group of reflective facets are determined by the sixth Fresnel formula, wherein the fifth Fresnel formula is related to the incident light The fifth preset angle of incidence and the fifth preset position are related; the sixth Fresnel formula is related to the fifth preset angle of incidence and the sixth preset position of the incident light, and the seventh preset position is related to the The vertical distance from the eighth preset position to the substrate is different, and the fifth set of reflective facets is used to reflect and/or transmit the incident light having the fifth preset angle of incidence to the fifth preset Position to present the fifth preset graphic information at the fifth preset position; the sixth group of reflective facets is used to reflect and/or transmit the incident light with the fifth preset angle of incidence to The sixth preset position is to present the sixth preset graphic information at the sixth preset position, and the color modulation structure is a fifth color modulation structure with a fifth modulation depth, and is used to enable
  • the color modulation structure includes: a metal film with a predetermined thickness; and a microstructure with steep side walls, or a subwavelength microstructure.
  • the depth of the microstructure with a steep side wall is in the range of 0.05-10 ⁇ m.
  • the color modulation structure is a microstructure with steep side walls
  • the period of the microstructure with steep side walls along at least one of the two directions in the two-dimensional plane in which it is located The range is 0.5-100 ⁇ m.
  • the depth of the groove of the sub-wavelength microstructure is in the range of 50-100 nm.
  • the shape of the groove of the sub-wavelength microstructure is sinusoidal, rectangular or sawtooth.
  • the period of the sub-wavelength microstructure in at least one of the two directions extending along the two-dimensional plane in which it is located is 50-700nm .
  • the periodic range of the reflective facet along at least one of the two directions in the two-dimensional plane in which it is located is 0.5-500 ⁇ m.
  • the second aspect of the present invention provides an anti-counterfeiting product, which includes the optical anti-counterfeiting element.
  • the anti-counterfeiting product includes banknotes, ID cards, bank cards or money orders.
  • the present invention creatively reflects and/or transmits incident light to a preset position through a plurality of reflective facets, and modulates the color of the reflected light and/or transmitted light through the color modulation structure, so that the The position presents the preset graphic information of the preset color, which can reproduce the preset color pattern under the irradiation of white light, which improves the anti-counterfeiting ability and recognition degree, thereby realizing the optical anti-counterfeiting element that is "easy to identify and difficult to forge” .
  • Figure 1 is a structural diagram of an optical anti-counterfeiting element provided by an embodiment of the present invention
  • FIG. 2 is a structural diagram of an optical anti-counterfeiting element (including a microstructure with a steep side wall) provided by an embodiment of the present invention
  • FIG. 3 is a schematic diagram of pixel distribution and combination provided by an embodiment of the present invention to realize a reproduced image
  • Figure 4 (a) is a top view of an optical anti-counterfeiting element provided by an embodiment of the present invention.
  • Figure 4(b) is a top view of an optical anti-counterfeiting element provided by an embodiment of the present invention.
  • FIG. 5 is a structural diagram of an optical anti-counterfeiting element (including a microstructure with steep side walls) for realizing reflection and reproduction of color images provided by an embodiment of the present invention
  • FIG. 6 is a structural diagram of an optical anti-counterfeiting element (including a microstructure with steep side walls) for realizing transmission and reproduction of color images provided by an embodiment of the present invention
  • FIG. 7 is a structural diagram of an optical anti-counterfeiting element (including sub-wavelength microstructures) for realizing reflection and reproduction of color images provided by an embodiment of the present invention
  • FIG. 8 is a structural diagram of an optical anti-counterfeiting element (including sub-wavelength microstructures) for realizing transmission and reproduction of color images provided by an embodiment of the present invention
  • FIG. 9(a) is a schematic diagram of the composition of reflective facets and microstructures provided by an embodiment of the present invention.
  • FIG. 9(b) is a schematic diagram of the composition of reflective facets and microstructures according to an embodiment of the present invention.
  • FIG. 9(c) is a schematic diagram of the composition mode of the reflective facet and the microstructure provided by an embodiment of the present invention.
  • FIG. 10 is a structural diagram of an optical anti-counterfeiting element (including sub-wavelength microstructures with two groove depths) for realizing reflection and reproduction of color images provided by an embodiment of the present invention
  • FIG. 11 is a structural diagram of an optical anti-counterfeiting element (including sub-wavelength microstructures with two groove depths) for realizing transmission and reproduction of color images provided by an embodiment of the present invention
  • FIG. 12 is a structural diagram of an optical anti-counterfeiting element (including sub-wavelength microstructures) that realizes reflection and reproduction of color images under illumination at two incident angles according to an embodiment of the present invention
  • FIG. 13 is a structural diagram of an optical anti-counterfeiting element (including sub-wavelength microstructures) that realizes transmission and reproduction of color images under illumination at two incident angles according to an embodiment of the present invention
  • optical anti-counterfeiting element including sub-wavelength microstructures and two sets of reflective facets
  • optical anti-counterfeiting element including sub-wavelength microstructures and two sets of reflective facets
  • the reproduced image is composed of some pixels in the space. If these pixels are converged by reflected or transmitted light, then the reproduced image is a real image; if these pixels are converged by the extension of the reflected or transmitted light , Then this reproduced image is a virtual image.
  • the reproduced patterns include virtual and real images. Specifically, when the reproduced image is a real image, the real image can be displayed on the receiving screen on the side where the real image is located, and can be observed by the observer. When the reproduced image is a virtual image, the virtual image can only be directly observed by the observer.
  • FIG. 1 is a schematic structural diagram of an optical anti-counterfeiting element 1 provided by an embodiment of the present invention.
  • the optical anti-counterfeiting element 1 may include: a substrate 2; a plurality of reflective facets 3 (indicated by dashed lines) formed on the substrate 2 for reflecting and/or transmitting incident light to a preset position, Presenting the preset graphic information at the preset position; and the color modulation structure 4 formed on the reflective facet 3 for modulating the color of the light reflected and/or transmitted by the reflective facet 3, So that the preset graphic information presents a preset color.
  • the cross-section of the aforementioned reflective facet 3 can be linear and non-linear, that is, the cross-section of the reflective facet 3 can be a smooth inclined surface (that is, a flat surface) with no curvature change, or it can have a certain degree of curvature ( That is, a curved surface, for example, a part of a paraboloid, arc, or other shape with curvature).
  • the lateral feature size of the reflective facet is in the range of 0.5-500 ⁇ m, preferably 30-200 ⁇ m.
  • the ⁇ 1st order diffraction angle is in the vicinity of the 0th order reflected light, and the distance is very close, and basically coincides with the 0th order reflected light. Since the reproduced image is formed by 0th-order reflected/transmitted light, the reproduced image formed by the microstructure within the above-mentioned size range is clear, and there is no diffraction interference.
  • the reflective facet satisfies the Fresnel reflection/transmission formula when the plane wave is incident.
  • the inclination angle and the azimuth angle of the plurality of reflective facets 3 can be determined by the Fresnel formula, where the Fresnel formula and the preset angle of incidence of the incident light (referring to the plane of the incident light and the substrate The included angle between) is related to the preset position.
  • the inclination angle and azimuth angle of a group of reflective facets can be determined by the predetermined incident angle and the predetermined position of the incident light, and then the set of reflective facets can be designed according to the determined inclination angle and azimuth angle, thereby
  • a pixel can be presented at a preset position, and multiple sets of reflective facets can be set according to a specific arrangement rule (the same as the above-mentioned set of reflective facets). Satisfying the same Fresnel formula) can present the preset graphic information at the preset position.
  • the optical anti-counterfeiting element 1 shown in FIG. 2 includes at least three different reflective facets 311, 312, 313 (the cross-section of which is diagonal to form a micro-mirror), and the inclination angles of the three different reflective facets ( Or the orientation is different, so the pixel points are formed at three different positions T1, T2, and T3 of the receiving screen 5.
  • the tilt angle and azimuth angle of the optical facet and purposefully designing the distribution of multiple sets of optical facets, a complex and practical image can be realized.
  • the optical security element 1 has different reflective facet groups, for example, reflective facet group S1 (including S1-1, S1-2, S1-3, S1-4), S2 (S2-1 , S2-2, S2-3, S2-4, S2-5) and S3 (S3-1, S3-2, S3-3), where the four reflective facets of the reflective facet group S1 focus the incident light To the position T1 of the receiving screen 5, a pixel T1 of the reflected projection image "8" is formed.
  • reflective facet group S1 including S1-1, S1-2, S1-3, S1-4
  • S2 S2-1 , S2-2, S2-3, S2-4, S2-5
  • S3 S3-1, S3-2, S3-3
  • the four reflective facets of the reflective facet group S2 reflect and focus the incident light to the position T2 of the receiving screen 5 to form the pixel T2 of the reflected projection image "8"; the four reflective facets of the reflective facet group S3 will The incident light is reflected and focused to the position T3 of the receiving screen 5 to form the pixel T3 of the reflected projection image "8".
  • the reflective facets in the reflective facet groups S1, S2, S3 are randomly distributed in the optical anti-counterfeiting element 1.
  • the optical anti-counterfeiting element 1 provides enough reflective facets to form a sufficient number of pixels at the reflective position. The positions of these pixels ultimately form a graphic with a specific meaning, such as the number "8", thus achieving The reproduction of the image.
  • the spatial position of the focal point can be modulated by the structural parameters of the reflective facet (for example, the orientation, including the tilt angle and the azimuth angle). If each focus point is arranged in a plane parallel to the optical anti-counterfeiting element, a plane reproduced image can be formed; if each focus point is arranged in the entire space, a three-dimensional reproduction pattern can be formed.
  • the reproduced image can only be in the form of grayscale, achieving a simple "black-gray-white" image.
  • the present invention arranges the "color modulation structure" on the reflective surface, and realizes reflection and/or transmission reproduction through preset physical principles.
  • the colorization Specifically, the color can be controlled by changing the parameters of the color modulation structure 4, for example, feature size and depth, etc., so as to achieve customized colors. Therefore, the reproduced preset graphic information can be a single Colored, it can also be colored, and it can even be a gradual color.
  • the depths of the three color modulation structures are different.
  • the depth of the color modulation structure 411 is 0.35 ⁇ m, and the color modulation structure 411 has a depth of 0.35 ⁇ m.
  • the depth of the modulation structure 412 is 0.45 ⁇ m, and the depth of the color modulation structure 413 is 0.27 ⁇ m.
  • the 311+411 combination corresponds to a green spot at the T1 position
  • the 312+412 combination corresponds to a red spot at the T2 position
  • the 313+413 combination corresponds to a yellow spot at the T3 position. Therefore, three different color pixels appear in the same reflection reproduction image.
  • the specific graphic information of a specific color can be formed by designing the characteristic parameters of the reflective facet 3 and the color modulation structure.
  • Figures 4(a) and 4(b) show the realized patterns of multiple colors, where one gray scale represents one color. It can be seen from the figure that multi-color patterns can be displayed, and the positions of different colors are accurately located. There is no overlap or distance between the two colors.
  • the upper and lower parts of the number "8" of the reflective reproduction pattern have two colors. If required by the design, a color gradient effect without obvious color boundaries can also be formed, which is similar to a rainbow color effect.
  • the colors at different positions of the reflective reproduction pattern ring are different.
  • the color modulation structure 4 may include: a microstructure 40 with steep side walls; and a metal film 42 with a predetermined thickness, as shown in FIG. 5 or FIG. 6.
  • the microstructure 40 with steep side walls may be a one-dimensional grating or a two-dimensional grating, and its characteristic size in the x-direction and/or y-direction ranges from 0.5 to 100 ⁇ m, preferably from 1 to 20 ⁇ m.
  • the depth range of the microstructure 40 with steep side walls in the z direction is 0.05-10 ⁇ m, preferably 0.1-3 ⁇ m.
  • the reflectivity of the optical anti-counterfeiting element is generally less than 20%, so the color saturation and brightness of the reflected and reproduced image are relatively high. low.
  • the preset thickness of the metal film 42 is not 0. The preset thickness of the metal film 42 can increase the reflectivity to more than 80%, or even 90%. %.
  • the two incident lights i1 and i2 are incident on the surfaces s1 and s2, they are reflected by the metal film 42 on the surfaces s1 and s2 of the "reflective facet 3 + the microstructure 40 with steep side walls" to form the reflected light r1 and r2; the angle between the reflected light r1 and the corresponding incident light i1 is 2 ⁇ , and the same is true, the angle between the reflected light r2 and the corresponding incident light i2 is also 2 ⁇ . If there is no microstructure 40 with steep side walls on the reflective facet 3, the reflective facet 3 is a traditional micro-mirror structure.
  • the reflected light after the incident white light has the same optical path, and there is no optical path difference, so the reflected light
  • the phases are the same, no interference occurs, and the reflected light is still white light.
  • the optical path of the reflected light r1 and r2 changes.
  • the optical path difference occurs, resulting in interference phenomenon between the reflected light r1 and r2, and finally a reflected light with a specific color is obtained in the reflection direction.
  • the color in this embodiment may be yellow.
  • the reflective facets 3 meeting the same Fresnel reflection formula at other positions reflect white light to the same position, they also appear yellow, that is, the light reflected by all the reflective facets 3 meeting the same Fresnel reflection formula
  • a focal point T is formed at the same position, and the focal point T is a pixel constituting the pattern, and the pixel is yellow.
  • the reflective facet 3 and the microstructure 40 with steep side walls are made of a transparent material (the reflection and absorptivity of the transparent material is not high), more light will be transmitted
  • the over-reflective facet 3 and the microstructure 40 with steep side walls, that is, the optical anti-counterfeiting element has a relatively high transmittance.
  • the metal film 42 may not be added, that is, the optical facet 3 is directly exposed in the air.
  • the lateral characteristic size of the reflective facet 3 in FIG. 6 is 40 ⁇ m, and the inclination angle is 10°; the lateral characteristic period of the microstructure with steep side walls varies from 3 ⁇ m to 10 ⁇ m, and the depth is 1.2 ⁇ m.
  • the transmitted light t converges on the receiving screen 8 through the combined action of the reflective facet 3 and the steep side wall of the microstructure 40, forming a yellow light spot (Or pixels).
  • the difference from reflection is that in reflection reproduction, when light is modulated by a microstructure with steep side walls, the optical path difference between the two beams reflected by the top and bottom of the microstructure is 2 times that of the light.
  • the depth of the microstructure, whether there is filling material on the surface of the microstructure, and the refractive index of the filling material are related; in transmission reproduction, since the surface of the microstructure generally cannot have filling material, the two beams of light passing through the top and bottom of the microstructure
  • the orientation (tilt angle and/or azimuth angle) of the reflective facet 3 and the parameters (for example, depth) of the color modulation structure 4 By appropriately designing the orientation (tilt angle and/or azimuth angle) of the reflective facet 3 and the parameters (for example, depth) of the color modulation structure 4, pixels of different colors can be presented at different positions, and these pixels can be formed with Graphical information of actual meaning.
  • the above-mentioned reflective facet 3 and the color modulation structure 4 can be randomly distributed, that is, in the case of diffuse reflection illumination, the above-mentioned pattern that needs to be reproduced cannot be observed, and can only be observed from the reflection and/or transmission direction when illuminated by light. To color reproduction of graphic information.
  • the color modulation structure 4 may include: a sub-wavelength microstructure 41; and a metal film 42 with a predetermined thickness, as shown in FIG. 7.
  • a metal film needs to be vapor-deposited or sputtered on the surface of the sub-wavelength microstructure.
  • Combining the reflective facet 3 and the color modulation structure 4 can form a plasma reflective facet.
  • the plasmon resonance absorption characteristics of the plasma reflective facet make the hidden image present a specific color.
  • the sub-wavelength microstructure 41 can be a one-dimensional grating or a two-dimensional grating, wherein the grid distribution of the two-dimensional grating can be an orthogonal structure, a honeycomb structure, a two-dimensional Bravais lattice structure, a random structure, etc.; a sub-wavelength microstructure
  • the groove can be sinusoidal, rectangular or sawtooth. It should be understood that the sub-wavelength microstructure 41 is not limited to the structure described above, and the splicing or combination of these sub-wavelength microstructures can be used in the actual optical anti-counterfeiting element.
  • the sub-wavelength microstructure 41 is preferably a two-dimensional grating.
  • the reflection spectrum reflected by the subwavelength microstructure 41 can be obtained according to the coupled wave theory.
  • the depth (or groove depth), period, groove type and metal film of the subwavelength microstructure 41 can all affect the resonance absorption of the reflection spectrum through calculation and simulation analysis. wavelength. Especially the influence of groove depth is particularly obvious.
  • the lateral feature size of the reflective facet 3 is much larger than the lateral feature size of the sub-wavelength microstructure 41.
  • the characteristic parameters of the sub-wavelength microstructure can be obtained. Take a one-dimensional grating as an example. When the incident light is incident on the grating at an angle ⁇ , diffracted light of different orders will be generated. When the diffracted light propagates on the surface of the grating, it resonates with the surface plasmon wave excited on the surface of the metal film. , That is, the wave vectors are equal.
  • the diffraction order is m
  • the component of incident light in the x direction of the grating surface is k x
  • the wave vector of the grating is k d
  • the component of diffracted light in the x direction of the grating surface is k x m
  • the surface plasma excited by the metal film surface The bulk wave vector is k sp
  • ⁇ is the incident angle of the incident light that causes resonance
  • ⁇ 0 is the wavelength in vacuum
  • n 1 is the refractive index of the metal film
  • ⁇ 0 is the dielectric constant of the incident light in the medium.
  • ⁇ 1 is the dielectric constant of the metal film.
  • the period d of the sub-wavelength grating structure can be obtained.
  • the period of the above-mentioned two-dimensional sub-wavelength micro-relief structure is variable, and the period in the x-direction and/or y-direction (ie, lateral feature size) ranges from 50 to 700 nm, preferably 200 to 400 nm.
  • the trench depth of the sub-wavelength microstructure is in the range of 10-500 nm, and more preferably, the trench depth of the sub-wavelength microstructure is in the range of 50-100 nm.
  • the predetermined thickness of the metal film 42 is less than 50 nm, preferably less than 20 nm.
  • the metal film 42 includes at least one of a metal layer, a metal compound layer, a high/low refractive index material stack, and a Fabry-Perot interferometer.
  • the metal film may be a film formed by one or more of gold, silver, copper, aluminum, iron, tin, zinc, nickel, chromium, and the like.
  • the metal film 42 may be an aluminum layer formed by vapor deposition, and the thickness is 30 nm.
  • a single dielectric layer or multiple dielectric layers can also be vapor-deposited before the metal film 42 is vapor-deposited.
  • the dielectric material used can be selected from one or more of MgF 2 , SiO 2 , Al 2 O 3 , MgO, PMMA, TiO 2 , ZnS, and ZnO, and the multilayer dielectric film usually adopts a high-low-high film design.
  • SiO 2 is used , and a three-layer structure is vapor-deposited, and the light-changing color is yellow to green.
  • the light-changing color is red to green; for the three-layer SiO 2 formed directly on the reflective facet, the light-changing color is yellow to green.
  • the sub-wavelength microstructure 41 or the microstructure 42 with steep side walls can be periodic in the x-direction and y-direction, or can be periodic in a certain range, or it can be Random.
  • Period means that in the entire range of the optical anti-counterfeiting element, all microstructures have the same arrangement rules and parameters.
  • Period in a certain range means that the microstructures have the same arrangement rules and parameters in a specific small range, but the microstructures do not have the same arrangement rules and parameters in the entire range of the optical anti-counterfeiting element.
  • Random means that the shape parameters and arrangement of the microstructures do not have the same law, and they are randomly distributed.
  • FIG. 9(a)-Fig. 9(c) Several arrangements of microstructures that can realize color reproduction images will be listed below, as shown in Fig. 9(a)-Fig. 9(c).
  • the square from black to white in Figure 9(a)- Figure 9(c) represents the reflective facet, black means lower height, and white means higher height, that is, the reflective facets are small slopes, and the characteristic size It is 49 ⁇ m.
  • the orientation of the reflective facet changes (it can change the content of the reproduced image as needed).
  • Figure 9(a) shows that the microstructure is constant along the x-direction, and periodically presents with/without changes along the y-direction. The overall period is periodic with a period of 5 ⁇ m.
  • Figure 9(b) shows another arrangement of microstructures.
  • the lateral feature size of the reflective facet is preferably 25 ⁇ m, and the longitudinal feature size is preferably in the range of 0.5-4 ⁇ m.
  • the reflective facet is a planar structure, and the sub-wavelength microstructure is a two-dimensional grating structure.
  • the reflective facet group After the plane wave is reflected by the reflective facet group, it propagates to the reproduced image area on the receiving screen. Assuming that the reflective facet group includes 10,000 reflective facets, and the number of pixels of the reproduced image is 100, a hidden image of 1 pixel is reproduced for every 100 reflective facets, and the 100 pixels are randomly distributed. For simple description, only a few reflective facets are listed in the structural diagram of the optical anti-counterfeiting element corresponding to each embodiment.
  • the plurality of reflective facets may be a first group of reflective facets, and the inclination and azimuth angles of the first group of reflective facets are determined by a first Fresnel formula, wherein the first Fresnel formula is related to the incident
  • the first predetermined incident angle of the light is related to the first predetermined position.
  • the first set of reflective facets is used to reflect and/or transmit the incident light with the first preset angle of incidence to the first preset position, so as to be at the first preset position Present the first preset graphic information.
  • the color modulation structure may be a first color modulation structure having a first modulation depth, and is used to make the first preset graphic information present a first preset color.
  • the first preset graphic information of the first preset color can be presented at the first preset position The real image.
  • the optical anti-counterfeiting element (as shown in FIG. 7) in the first embodiment can realize a single-color image that is reflected and reproduced.
  • the sub-wavelength microstructure is covered with a 30nm thick aluminum layer, which can play a role in enhancing reflection.
  • the inclination and azimuth angles of the three reflective facets in Figure 7 satisfy the same Fresnel reflection formula (the first preset position is O point, and the first preset incident angle is 90 degrees).
  • the distribution of multiple combinations of facets may present the first preset graphic information A at point O.
  • incident light for example, white light
  • the sub-wavelength microstructures on different reflective facets are the same (the depth is 120nm). Therefore, the sub-wavelength microstructures can modulate the light reflected by the reflective facets into light of the same color (for example, red), thereby A single color (for example, red) image A appears at O.
  • the extension of the refracted light also has a certain convergence effect, thereby forming an image A (not shown).
  • the image A is relatively close to the substrate (which can be regarded as the surface of the substrate) and is a virtual image; relative to the real image A reproduced, the virtual image A is located on the opposite side of the real image A.
  • the optical anti-counterfeiting element (as shown in FIG. 8) in the second embodiment can realize a single color image that is transmitted and reproduced.
  • a metal layer In order to meet the plasma absorption condition, a metal layer needs to be vapor-deposited or sputtered on the surface of the sub-wavelength microstructure, but the metal layer is a reflective layer, which will reduce the brightness of the transmitted image. Therefore, the metal layer needs to meet a certain thickness requirement in order to realize the transmission and reproduction of the hidden image. In other words, if the thickness of the metal layer is too large, even if there is plasma absorption, the reproduced image will not be observed in the transmission direction.
  • the thickness of the metal layer is constant, the reflective facet with plasma has a higher transmittance than the reflective facet without plasma.
  • the sub-wavelength microstructure is covered with a 15nm thick aluminum layer.
  • the inclination and azimuth angles of the three reflective facets in Figure 8 satisfy the same Fresnel transmission formula (the first preset position is O'point, and the first preset incident angle is 90 degrees).
  • the distribution of multiple combinations of reflective facets may present the first preset graphic information A at point O'.
  • incident light for example, white light
  • the sub-wavelength microstructures on different reflective facets are the same. Therefore, the sub-wavelength microstructures can modulate the light transmitted by the reflective facets into light of the same color, thereby presenting a single-color image A at O'.
  • the extension of the reflected light when light is incident, the extension of the reflected light also has a certain convergence effect, thereby forming an image A (not shown).
  • the image A is relatively close to the substrate (which can be regarded as the surface of the substrate) and is a virtual image; relative to the real image A reproduced, the virtual image A is located on the opposite side of the real image A.
  • the color (for example, blue) of the image A reproduced by transmission is complementary to the color of the image A (for example, red) reproduced by the reflection.
  • the plurality of reflective facets may be a second set of reflective facets, and the inclination and azimuth angles of the second set of reflective facets are determined by a second Fresnel formula, wherein the second Fresnel formula is related to the incident
  • the second predetermined incident angle of the light is related to the second predetermined position.
  • the second set of reflective facets is used to reflect and/or transmit the incident light with the second preset angle of incidence to the second preset position, so as to be at the second preset position Present the second preset graphic information.
  • the color modulation structure may include: a second color modulation structure having a second modulation depth, configured to make the second preset graphic information present a second preset color; and a third color modulation structure having a third modulation depth The structure is used to make the second preset graphic information present a third preset color, and the second modulation depth is different from the third modulation depth.
  • the optical anti-counterfeiting element is presented at the second preset position.
  • the real image of the second preset graphic information with integrated color effect, and/or the virtual image of the second preset graphic information with integrated color effect composed of two different colors is presented on the surface of the optical anti-counterfeiting element.
  • the optical anti-counterfeiting element in the third embodiment can realize a reflected and reproduced image with a comprehensive color effect of two colors.
  • the subwavelength microstructure is a two-dimensional grid structure, and the depth of the subwavelength microstructure is different.
  • the characteristic dimensions of the sub-wavelength microstructure 421 on the reflective facet 321 and the sub-wavelength microstructure 422 on the reflective facet 322 are both: the period is 300nm, and the depth is 120nm. This part of the optical anti-counterfeiting element reflects and focuses red under the illumination of white light.
  • the feature size of the sub-wavelength microstructure 423 on the reflective facet 323 and the sub-wavelength microstructure 424 on the reflective facet 324 are: the period is 300nm, the depth is 150nm, this part of the optical anti-counterfeiting element reflects under white light irradiation Focus on pixels that appear blue.
  • the sub-wavelength microstructure is covered with a 30nm thick aluminum layer, which can play a role in enhancing reflection.
  • the four reflective facets satisfy the same Fresnel reflection formula (the second preset position is point P, and the second preset incident angle is 90 degrees).
  • the second preset graphic information A is presented.
  • incident light for example, white light
  • the sub-wavelength microstructures 421 and 422 can respectively modulate the light reflected by the reflective facets 321 and 322 into red light
  • the subwavelength microstructures 423 and 424 can respectively modulate the light reflected by the reflective facets 323 and 324 into red light.
  • the blue light thus presents an image A of a mixed color of red and blue at P (the image A is a real image).
  • the red (complementary to the blue observed in the reflection direction) at a closer distance (compared to point P) from the substrate (which can be regarded as the surface of the optical security element) and
  • An image A of a mixed color of blue (complementary to the red observed in the reflection direction) (not shown, the image A is a virtual image, which is formed by converging the extension lines of the refracted light).
  • the optical anti-counterfeiting element (as shown in FIG. 11) in the fourth embodiment can realize an image with a comprehensive color effect of two colors transmitted and reproduced.
  • the sub-wavelength microstructure in the fourth embodiment is covered with a 15nm thick aluminum layer.
  • the inclination and azimuth angles of the four reflective facets in Figure 11 satisfy the same Fresnel transmission formula (the second preset position is P'point, and the second preset incident angle is 90 degrees).
  • the distribution of multiple combinations of reflective facets may present the second preset graphic information A at point P'.
  • incident light for example, white light
  • the sub-wavelength microstructures 431 and 432 can respectively modulate the light reflected by the reflective facets 331 and 332 into blue light
  • the subwavelength microstructures 433 and 434 can respectively modulate the light reflected by the reflective facets 333 and 334.
  • the multiple reflective facets include: a third set of reflective facets and a fourth set of reflective facets.
  • the inclination and azimuth angles of the multiple reflective facets in the third set of reflective facets are determined by the third Fresnel
  • the formula is determined, and the inclination angle and the azimuth angle of the multiple reflective facets in the fourth group of reflective facets are determined by the fourth Fresnel formula.
  • the third Fresnel formula is related to the third preset angle of incidence and the third preset position of the incident light; the fourth Fresnel formula is related to the fourth preset angle of incidence and the fourth preset position of the incident light Assuming that the positions are related, the third preset angle of incidence is different from the fourth preset angle of incidence, and the third preset position is different from the fifth preset position.
  • the third set of reflective facets is used to reflect and/or transmit the incident light having the third preset angle of incidence to the third preset position, so as to be at the third preset position Presenting the third preset graphic information;
  • the fourth group of reflective facets is used to reflect and/or transmit the incident light with the fourth preset angle of incidence to the fourth preset position, so as to The fourth preset graphic information is presented at the fourth preset position.
  • the color modulation structure is a fourth color modulation structure with a fourth modulation depth, and is used to make the third preset graphic information and the fourth preset graphic information present a fourth preset color.
  • the third preset graphic information of the third preset color is presented at the third preset position A real image, and/or a real image of the fourth preset graphic information in the fourth preset color is presented at the fourth preset position under the illumination of incident light having the fourth preset angle of incidence .
  • the optical anti-counterfeiting element in the fifth embodiment can reproduce the images A and B in the direction of the reflected light by changing the incident directions a1 and a2 of the white light irradiation.
  • the sub-wavelength microstructure is covered with a 30nm thick aluminum layer, which can play a role in enhancing reflection.
  • the sub-wavelength microstructures on different reflective facets are the same. Therefore, the sub-wavelength microstructures can modulate the light reflected by the reflective facets into light of the same color, thereby presenting image A and image B of a single color.
  • the reflective facets 341 and 342 satisfy the same Fresnel reflection formula (the third preset position is point S, and the third preset angle of incidence is 90 degrees); the reflective facets 343 and 344 satisfy the same Fresnel reflection formula (the fourth The preset position is U point, and the fourth preset incident angle is 45 degrees). Therefore, the third preset graphic information A can be presented at point S by designing the distribution of multiple combinations composed of the above-mentioned reflective facets 341, 342; The combined distribution can present the fourth preset graphic information B at the U point.
  • the slope and azimuth angle of the reflective facet are calculated, and two different sets of parameters can be obtained, and then 1/ of each set of parameters is selected. 2 Reconstitute the design parameters, and the distribution law is random. For example, when the incident angle is 90 degrees, 100*100 reflective facets are generated, which will reproduce image A; when the incident angle is 45 degrees, 100*100 reflective facets are generated, and the reflective facets will be reproduced. Image B is output; then, 50*100 reflective facets are selected respectively to form a new 100*100 reflective facet.
  • incident light with an incident angle of 90 degrees can be reflected and focused to point S, and a real image of image A is presented; the incident light with an incident angle of 45 degrees (for example, white light) can be reflected and focused Go to point U, and show the real image of image B.
  • a virtual image A or B appears on the surface of the optical anti-counterfeiting element, and its color and reflection direction are observed
  • the colors of the real image A or B are complementary.
  • the optical anti-counterfeiting element in the sixth embodiment (as shown in Figure 13) can reproduce images A and B in the transmitted light direction by changing the incident directions a1 and a2 of the white light.
  • the sub-wavelength microstructure in the sixth embodiment is covered with a 15nm thick aluminum layer.
  • the reflective facets 351 and 352 satisfy the same Fresnel transmission formula (the third preset position is S'point, and the third preset angle of incidence is 90 degrees); the reflective facets 353 and 354 satisfy the same Fresnel transmission formula (the third preset position is 90 degrees).
  • the four preset positions are U'point, and the fourth preset incident angle is 45 degrees). Therefore, the third preset graphic information A can be presented at point S'by designing the distribution of multiple combinations composed of the aforementioned reflective facets 351, 352; the third preset graphic information A can be presented at point S'; The distribution of the two combinations can present the fourth preset graphic information B at the U'point.
  • the Fresnel transmission formula when the incident angle is 90 degrees and 45 degrees, the slope and azimuth angle of the reflective facet are calculated, and two different sets of parameters can be obtained, and then 1/ of each set of parameters is selected. 2 Reconstitute the design parameters, and the distribution law is random.
  • incident light with an incident angle of 90 degrees for example, white light
  • incident light with an incident angle of 45 degrees for example, white light
  • the transmission is focused to the U'point, and the real image of image B is presented.
  • a virtual image A or B appears on the surface of the optical anti-counterfeiting element, and its color and the transmission direction are observed
  • the colors of the real image A or B are complementary.
  • the incident angle can be set for the incident angle, but the more incident angle parameters, the lower the brightness of the reproduced image, and there will be interference between the images during reproduction.
  • the reproduction effect can also use the principle in FIG. 10, and images of different colors will be reproduced at different focal planes.
  • the multiple reflective facets include: a fifth set of reflective facets and a sixth set of reflective facets.
  • the inclination and azimuth angles of the multiple reflective facets in the fifth set of reflective facets are determined by the fifth Fresnel
  • the formula is determined, and the inclination angle and the azimuth angle of the multiple reflective facets in the sixth group of reflective facets are determined by the sixth Fresnel formula.
  • the fifth Fresnel formula is related to the fifth preset angle of incidence and the fifth preset position of the incident light
  • the sixth Fresnel formula is related to the fifth preset angle of incidence and the sixth preset position of the incident light Assuming that the position is related, the vertical distance between the seventh preset position and the eighth preset position to the substrate is different.
  • the fifth set of reflective facets is used to reflect and/or transmit the incident light with the fifth preset angle of incidence to the fifth preset position, so as to be at the fifth preset position
  • the sixth group of reflective facets is used to reflect and/or transmit the incident light with the fifth preset angle of incidence to the sixth preset position, so as to The sixth preset graphic information is presented at the sixth preset position.
  • the color modulation structure is a fifth color modulation structure with a fifth modulation depth, and is used to make the fifth preset graphic information and the sixth preset graphic information present a fifth preset color.
  • the optical anti-counterfeiting element is illuminated by incident light having the fifth preset angle of incidence
  • the fifth preset image and text information of the fifth preset color is presented at the fifth preset position A real image, and a real image showing the sixth preset graphic information of the fifth preset color at the sixth preset position.
  • the optical anti-counterfeiting element in the seventh embodiment can display images A and B at focal planes at different distances from the substrate in the direction of reflected light (for example, 5 cm and 10 cm from the substrate).
  • the sub-wavelength microstructure is covered with a 30nm thick aluminum layer, which can play a role in enhancing reflection.
  • the sub-wavelength microstructures on different reflective facets are the same. Therefore, the sub-wavelength microstructures can modulate the light reflected by the reflective facets into light of the same color, thereby presenting image A and image B of a single color.
  • the reflective facets 361 and 362 satisfy the same Fresnel reflection formula (the fifth preset position is X point, and the fifth preset angle of incidence is 90 degrees); the reflective facets 363 and 364 satisfy the same Fresnel reflection formula (the sixth The preset position is Y point, and the fifth preset incident angle is 90 degrees). Therefore, the fifth preset graphic information B can be presented at point X by designing the distribution of multiple combinations composed of the above-mentioned reflective facets 361, 362; The combined distribution can present the sixth preset graphic information A at the Y point.
  • the imaging focus position is X point (for example, 10 cm from the substrate surface) and Y point (for example, 5 cm from the substrate surface)
  • the slope of the reflective facet is calculated
  • the azimuth angle two different sets of parameters can be obtained, and then 1/2 of each set of parameters is selected to re-form the design parameters, and the distribution law is random.
  • incident light for example, white light
  • incident angle of 90 degrees can be reflected and focused to points X and Y, and real images of images B and A are respectively presented.
  • the optical anti-counterfeiting element in the eighth embodiment (as shown in FIG. 15) can realize the focal plane at different distances from the substrate in the transmitted light direction (for example, 5cm from the substrate). And 10 cm) images A and B are presented. Due to the resonant absorption characteristics of plasma, when white light irradiates the optical anti-counterfeiting element, it has a certain anti-reflection effect, and a color complementary to the color of the reflected and reproduced image in the seventh embodiment will appear in the transmission direction.
  • the sub-wavelength microstructure in the eighth embodiment is covered with a 15nm thick aluminum layer.
  • the reflective facets 371 and 372 satisfy the same Fresnel transmission formula (the fifth preset position is X'point, and the fifth preset angle of incidence is 90 degrees); the reflective facets 373 and 374 satisfy the same Fresnel transmission formula (the fifth preset position is 90 degrees).
  • the sixth preset position is Y'point, and the fifth preset incident angle is 90 degrees). Therefore, the fifth preset graphic information B can be presented at point X'by designing the distribution of multiple combinations composed of the aforementioned reflective facets 371, 372; the fifth preset graphic information B can be presented at point X'; The distribution of these combinations can present the sixth preset graphic information A at point Y'.
  • the imaging focal position is at the X'point (for example, 10 cm from the substrate surface) and Y'point (for example, at 5 cm)
  • the slope of the reflection facet and For the azimuth angle two sets of different parameters can be obtained, and then 1/2 of each set of parameters is selected to reconstitute the design parameters, and the distribution law is random.
  • incident light for example, white light
  • incident angle of 90 degrees can be transmitted and focused to points X'and Y', and real images of images B and A are respectively presented.
  • the reproduction effect can also use the principle in FIG. 12, and different white light irradiation angles will reproduce different images.
  • the color of the imaging can also be modulated by changing the sub-wavelength microstructure, which will not be repeated here.
  • the microstructures in the various embodiments of the present invention are made by laser plate making. As a result, the reflective facets 321 and 322 in FIG. 10 can reproduce one image, and the reflective facets 323 and 324 can reproduce another image, forming two Color reproduction of macro images.
  • the two-dimensional sub-wavelength depth of each independent reflective facet can be precisely controlled, that is, the color of each pixel of the reproduced image can be accurately controlled to form a colored image.
  • the size of the first structure has certain requirements.
  • the longitudinal dimension (ie, the height) of the reflective facet should not be too high, otherwise the thickness of the reflective facet can be too high, and it cannot be buried in the paper or pasted on the carrier, resulting in unevenness. Therefore, the height of the reflective facet is generally less than 100 ⁇ m, preferably less than 10 ⁇ m, which is conducive to the application of this feature to the window security thread, buried in paper; or as a wide strip product, pasted on paper or plastic substrate, and It can maintain the flatness of the substrate in the above two cases.
  • the present invention creatively reflects and/or transmits incident light to a preset position through a plurality of reflective facets, and modulates the color of the reflected light and/or transmitted light through the color modulation structure, so that the color of the reflected light and/or transmitted light is modulated in the preset position.
  • the position presents the preset graphic information of the preset color, which can reproduce the preset color pattern under the irradiation of white light, which improves the anti-counterfeiting ability and recognition degree, thereby realizing the optical anti-counterfeiting element that is "easy to identify and difficult to forge" .
  • the present invention also provides an anti-counterfeiting product, which may include the above-mentioned optical anti-counterfeiting element.
  • the optical anti-counterfeiting element can be placed in the above-mentioned anti-counterfeiting product in a manner such as a window opening security thread, a window opening sticker or a label.
  • the anti-counterfeiting products may include high value-added products such as banknotes, ID cards, bank cards, money orders or securities.

Abstract

公开了一种光学防伪元件（1）及防伪产品。光学防伪元件包括：基材（2）；形成于基材上的多个反射小面（3），用于将入射光线反射和/或透射到预设位置，以在该预设位置处呈现预设的图文信息；以及形成于反射小面上的颜色调制结构（4），用于调制反射小面所反射和/或透射的光线的颜色，以使预设的图文信息呈现预设颜色。可在白光的照射下再现彩色的预设图案，提高了防伪能力和辨识度。

Description

光学防伪元件及防伪产品
相关申请的交叉引用
本申请要求2019年09月30日提交的中国专利申请201910943326.0的权益，该申请的内容通过引用被合并于本文。
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防伪产品。
背景技术
图像再现技术是一种有效的二线防伪手段，具体地，将适当的光源照射在防伪元件表面上时，能够在相应的接收屏上观察到特定的图文信息；而直接观察时，不能观察到上述图文信息。因此，这该图像再现技术需要借助一定的条件才能够观察到隐藏的特征。
传统的图像再现技术一般采用衍射光栅，即通过表面微浮雕结构对入射光的衍射，将光线衍射至±1级的位置。经过适当的排布衍射光栅的周期和方向，能够控制衍射光斑的位置，进而将若干光斑组合成具有特定意义的图文。但是由于衍射原理导致存在±1级衍射，一般会在镜面反射的左右出现两个对称的图案，故限制了图文信息的设计。同时，由于衍射方向与入射光的频率严格相关，故该再现技术需要的光线一般为激光。而当采用白光或日光照明时，再现图案的清晰度非常差。
由于白光光源易于获得，特别是随着智能手机的普及，闪光灯作为白光照明光源得到了广泛的使用，甚至阳光、手电、投影仪光源等多种光源均可以用于白光再现的照明。如何实现白光照射下的彩色图像的再现成了亟待解决的问题。
发明内容
本发明的目的是提供一种光学防伪元件及防伪产品，其可在白光的照射下再现彩色的预设图案。
为了实现上述目的，本发明一方面提供一种光学防伪元件，该光学防伪元件包括：基材；形成于所述基材上的多个反射小面，用于将入射光线反射和/或透射到预设位置，以在该预设位置处呈现预设的图文信息；以及形成于所述反射小面上的颜色调制结构，用于调制所述反射小面所反射和/或透射的光线的颜色，以使所述预设的图文信息呈现预设颜色。
优选地，所述多个反射小面的倾斜角与方位角由菲涅尔公式确定，其中，所述菲涅尔公式与入射光线的预设入射角及所述预设位置相关。
优选地，所述多个反射小面为第一组反射小面，该第一组反射小面的倾斜角与方位角由第一菲涅尔公式确定，其中，所述第一菲涅尔公式与入射光线的第一预设入射角及第一预设位置相关，所述第一组反射小面用于将具有所述第一预设入射角的入射光线反射和/或透射到所述第一预设位置，以在所述第一预设位置处呈现第一预设图文信息，所述颜色调制结构为具有第一调制深度的第一颜色调制结构，用于使所述第一预设图文信息呈现第一预设颜色，在具有所述第一预设入射角的入射光线照射该光学防伪元件的情况下，在所述第一预设位置处呈现所述第一预设颜色的所述第一预设图文信息的实像。
优选地，所述多个反射小面为第二组反射小面，该第二组反射小面的倾斜角与方位角由第二菲涅尔公式确定，其中，所述第二菲涅尔公式与入射光线的第二预设入射角及第二预设位置相关，所述第二组反射小面用于将具有所述第二预设入射角的入射光线反射和/或透射到所述第二预设位置，以在所述第二预设 位置处呈现第二预设图文信息，所述颜色调制结构包括：具有第二调制深度的第二颜色调制结构，用于使所述第二预设图文信息呈现第二预设颜色；以及具有第三调制深度的第三颜色调制结构，用于使所述第二预设图文信息呈现第三预设颜色，所述第二调制深度与所述第三调制深度不同，在具有所述第二预设入射角的入射光线照射该光学防伪元件的情况下，在所述第二预设位置处呈现由所述第二预设颜色及所述第三预设颜色组成的综合颜色效果的所述第二预设图文信息的实像。
优选地，所述多个反射小面包括：第三组反射小面及第四组反射小面，所述第三组反射小面中的多个反射小面的倾斜角与方位角由第三菲涅尔公式确定，所述第四组反射小面中的多个反射小面的倾斜角与方位角由第四菲涅尔公式确定，其中，所述第三菲涅尔公式与入射光线的第三预设入射角及第三预设位置相关；所述第四菲涅尔公式与入射光线的第四预设入射角及第四预设位置相关，所述第三预设入射角与所述第四预设入射角不同，所述第三预设位置与所述第四预设位置不同，所述第三组反射小面用于将具有所述第三预设入射角的入射光线反射和/或透射到所述第三预设位置，以在所述第三预设位置处呈现第三预设图文信息；所述第四组反射小面用于将具有所述第四预设入射角的入射光线反射和/或透射到所述第四预设位置，以在所述第四预设位置处呈现第四预设图文信息，所述颜色调制结构为具有第四调制深度的第四颜色调制结构，用于使所述第三预设图文信息与所述第四预设图文信息呈现第四预设颜色，在具有所述第三预设入射角的入射光线照射该光学防伪元件的情况下，在所述第三预设位置处呈现所述第三预设颜色的所述第三预设图文信息的实像，和/或在具有所述第四预设入射角的入射光线照射下，在所述第五预设位置处呈现所述第四预设颜色的所述第四预设图文信息的实像。
优选地，所述多个反射小面包括：第五组反射小面及第六组反射小面，所述第五组反射小面中的多个反射小面的倾斜角与方位角由第五菲涅尔公式确定，所述第六组反射小面中的多个反射小面的倾斜角与方位角由第六菲涅尔公式确定，其中，所述第五菲涅尔公式与入射光线的第五预设入射角及第五预设位置相关；所述第六菲涅尔公式与入射光线的第五预设入射角及第六预设位置相关，所述第七预设位置与所述第八预设位置到所述基材的垂直距离不同，所述第五组反射小面用于将具有所述第五预设入射角的入射光线反射和/或透射到所述第五预设位置，以在所述第五预设位置处呈现第五预设图文信息；所述第六组反射小面用于将具有所述第五预设入射角的入射光线反射和/或透射到所述第六预设位置，以在所述第六预设位置处呈现第六预设图文信息，所述颜色调制结构为具有第五调制深度的第五颜色调制结构，用于使所述第五预设图文信息与所述第六预设图文信息呈现第五预设颜色，在具有所述第五预设入射角的入射光线照射该光学防伪元件的情况下，在所述第五预设位置处呈现所述第五预设颜色的所述第五预设图文信息的实像，以及在所述第六预设位置处呈现所述第五预设颜色的第六预设图文信息的实像。
优选地，所述颜色调制结构包括：预设厚度的金属膜；以及边壁陡直的微结构，或者亚波长微结构。
优选地，在所述颜色调制结构为所述边壁陡直的微结构的情况下，所述边壁陡直的微结构的深度范围为0.05-10μm。
优选地，在所述颜色调制结构为所述边壁陡直的微结构的情况下，所述边壁陡直的微结构沿其所在的二维平面内的两个方向中至少一个方向的周期范围为0.5-100μm。
优选地，在所述颜色调制结构为所述亚波长微结构的情况下，所述亚波长微结构的槽的深度范围为50-100nm。
优选地，在所述颜色调制结构为所述亚波长微结构的情况下，所述亚波长微结构的槽的形状为正弦形、矩形或锯齿形。
优选地，在所述颜色调制结构为所述亚波长微结构的情况下，所述亚波长微结构沿其所在的二维平面延伸的两个方向中至少一个方向上的周期范围为50-700nm。
优选地，所述反射小面沿其所在的二维平面内的两个方向中至少一个方向的周期范围为0.5-500μm。
本发明第二方面提供一种防伪产品，该防伪产品包含所述的光学防伪元件。
优选地，所述防伪产品包括钞票、身份证、银行卡或汇票。
通过上述技术方案，本发明创造性地通过多个反射小面将入射光反射和/或透射到预设位置，并通过颜色调制结构调制反射光线和/或透射光线的颜色，以在所述预设位置处呈现出预设颜色的预设图文信息，其可在白光的照射下再现彩色的预设图案，提高了防伪能力和辨识度，从而可实现“易识别，难伪造”的光学防伪元件。
本发明的其他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实用新型的进一步理解，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实用新型，但并不构成对本实用新型的限制。在附图中：
图1是本发明实施例提供的光学防伪元件的结构图；
图2是本发明实施例提供的光学防伪元件(包括边壁陡直的微结构)的结构图；
图3是本发明实施例提供的像素分布及组合实现再现图像的示意图；
图4(a)是本发明实施例提供的光学防伪元件的俯视图；
图4(b)是本发明实施例提供的光学防伪元件的俯视图；
图5是本发明实施例提供的实现反射再现彩色图像的光学防伪元件(包括边壁陡直的微结构)的结构图；
图6是本发明实施例提供的实现透射再现彩色图像的光学防伪元件(包括边壁陡直的微结构)的结构图；
图7是本发明实施例提供的实现反射再现彩色图像的光学防伪元件(包括亚波长微结构)的结构图；
图8是本发明实施例提供的实现透射再现彩色图像的光学防伪元件(包括亚波长微结构)的结构图；
图9(a)是本发明实施例提供的反射小面与微结构的组成方式的示意图；
图9(b)是本发明实施例提供的反射小面与微结构的组成方式的示意图；
图9(c)是本发明实施例提供的反射小面与微结构的组成方式的示意图；
图10是本发明实施例提供的实现反射再现彩色图像的光学防伪元件(包括两种沟槽深度的亚波长微结构)的结构图；
图11是本发明实施例提供的实现透射再现彩色图像的光学防伪元件(包括两种沟槽深度的亚波长微结构)的结构图；
图12是本发明实施例提供的两种入射角照射下实现反射再现彩色图像的光学防伪元件(包括亚波长微结构)的结构图；
图13是本发明实施例提供的两种入射角照射下实现透射再现彩色图像的光学防伪元件(包括亚波长微结构)的结构图；
图14是本发明实施例提供的实现反射再现彩色图像的光学防伪元件(包括亚波长微结构及两组反射小面)的结构图；以及
图15是本发明实施例提供的实现透射再现彩色图像的光学防伪元件(包括亚波长微结构及两组反射小面)的结构图。
具体实施方式
以下结合附图对本发明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，并不用于限制本发明。
由于反射小面随机分布在整个光学防伪元件内，在漫反射照明的情况下，光学防伪元件呈现亚光效果，不呈现具体可辨识的颜色，故不能观察与再现图像相关的外观，从而实现了再现图像的隐藏。而再现图像为在空间内的一些像素点构成，若这些像素点是由反射或透射光线汇聚而成，那么这个再现图像为实像；若这些像素点是由反射或透射光线的延长线汇聚而成，那么这个再现图像为虚像。再现图案包括虚像和实像。具体地，再现图像为实像时，所述实像可以显示在实像所在一侧的接收屏上，并能够被观察者观察到。再现图像为虚像时，所述虚像仅能够被观察者直接观察到。
图1是本发明实施例提供的光学防伪元件1的结构示意图。所述光学防伪元件1可包括：基材2；形成于所述基材2上的多个反射小面3(用虚线表示)，用于将入射光线反射和/或透射到预设位置，以在该预设位置处呈现预设的图文信息；以及形成于所述反射小面3上的颜色调制结构4，用于调制所述反射小面3所反射和/或透射的光线的颜色，以使所述预设的图文信息呈现预设颜色。
需要说明的是，上述反射小面3的截面可以是线性的和非线性的，即反射小面3的截面可以是无曲率变化的平滑斜面(即平面)，也可以是具有一定弯曲程度的(即曲面，例如，抛物面、圆弧或其他具有曲率的形状的一部分)。
为了实现反射/透射聚焦的特点，并且有效避免衍射的情况干扰再现图像的清晰度，反射小面的横向特征尺寸的范围为0.5-500μm，优选为30-200μm。特别是在优选尺寸范围内，即使存在微弱的衍射现象，其±1级衍射角也在0级反射光的附近，且距离非常近，基本上与0级反射光重合。由于再现图像由0级反射/透射光形成，因此上述尺寸范围内的微结构形成的再现图像清晰，不会存在衍射干扰。
由于反射小面的尺寸较大基本避免了衍射现象的发生，因此，反射小面在平面波入射时，满足菲涅尔反射/透射公式。具体地，所述多个反射小面3的倾斜角与方位角可由菲涅尔公式确定，其中，所述菲涅尔公式与入射光线的预设入射角(是指入射光线与基材所在平面之间的夹角)及所述预设位置相关。由此，可通过入射光线的预设入射角及所述预设位置来确定一组反射小面的倾斜角与方位角，然后按照所确定的倾斜角与方位角设计该组反射小面，从而在具有预设入射角的白光照射所设计的该组反射小面的情况下，可在预设位置呈现一个像素，按照特定的排布规律设置多组反射小面(与上述那组反射小面满足同一菲涅尔公式)可在所述预设位置呈现预设的图文信息。
图2示出的光学防伪元件1包含至少3个不同的反射小面311、312、313(其截面为斜劈型，从而形成微反镜)，并且该3个不同反射小面的倾斜角(或朝向)不同，故在接收屏5的三个不同位置T1、T2、T3处形成像素点。由此，类似地，通过设计光学小面的倾斜角及方位角，并有目的地设计多组光学小面的分布可实现复杂的有实际意义的图像。
如图3所示，光学防伪元件1中具有不同的反射小面组，例如，反射小面组S1(包含S1-1、S1-2、S1-3、S1-4)，S2(S2-1、S2-2、S2-3、S2-4、S2-5)和S3(S3-1、S3-2、S3-3)，其中反射小面组S1的四个反射小面将入射光反射聚焦至接收屏5的T1位置，形成反射投影图像“8”的像素T1。同理，反射小面组S2的四个反射小面将入射光反射聚焦至接收屏5的T2位置，形成反射投影图像“8”的像素T2；反射小面组S3的四个反射小面将入射光反射聚焦至接收屏5的T3位置，形成反射投影图像“8”的像素T3。其中，反射小面组S1、S2、S3中的各个反射小面在光学防伪元件1中随机分布。以此类推，光学防伪元件1中提供足够的反射小面组即能够在反射位置形成足够数量的像素，这些像素的所在位置最终组成具有特定含义的图文，例如数字“8”，从而实现了图像的再现。
因此，可通过反射小面的结构参数(例如朝向，包括：倾斜角与方位角)来实现对聚焦点的空间位置的调制。如果将各个聚焦点布置在与光学防伪元件平行的一个平面内，则能够形成平面再现图像；如果将各个聚焦点布置在整个空间内，则能够形成立体再现图案。
如果只存在反射小面，那么再现图像只能是灰度的形式，实现简单的“黑-灰-白”的图像。为了丰富再现图像的信息量，增加技术难度以提高防伪能力，并便于公众观察，本发明将“颜色调制结构”布置于反射小面上，通过预设的物理原理，实现反射和/或透射再现的颜色化。具体地，可通过改变颜色调制结构4的参数，例如，特征尺寸和深度等，来实现对颜色的控制，从而实现订制化的颜色，由此，再现的预设的图文信息可以是单色的，也可以是彩色的，甚至可以是渐变色的。
如图2所示，在反射小面上具有三种不同深度的颜色调制结构411、412和413，该三种颜色调制结构的深度均不同，其中，颜色调制结构411的深度为0.35μm，颜色调制结构412的深度为0.45μm，颜色调制结构413的深度为0.27μm。当白光照射到光学防伪元件1时，“反射小面3+颜色调制结构4”的组合将入射光反射汇聚到接收屏5的不同位置，呈现不同颜色的像素。具体地，311+411组合对应的T1位置处呈现绿色的光斑，312+412组合对应的T2位置处呈现红色的光斑，313+413组合对应的T3位置处呈现黄色的光斑。因此，在同一反射再现图像中呈现三种不同颜色的像素。
因此，可通过设计反射小面3及颜色调制结构的特征参数可形成特定颜色的特定图文信息。图4(a)及图4(b)示出了实现的多种颜色的图案，其中一种灰度代表一种颜色。从图中可见，能够显示多色图案，且不同颜色的位置是精准定位的。两种颜色之间不存在相互重叠或远离，如图4(a)所示，反射再现图案数字“8”的上半部分与下半部分具有两种颜色。如果设计需要，还可以形成不存在明显颜色界限的颜色渐变效果，类似彩虹色的效果，如图4(b)所示，反射再现图案圆环的不同位置处的颜色不同。
下面在两个实施例中对颜色调制结构4的具体情况进行说明。
在一实施例中，所述颜色调制结构4可包括：边壁陡直的微结构40；以及预设厚度的金属膜42，如图5或图6所示。所述边壁陡直的微结构40可以是一维光栅，也可以是二维光栅，其在x方向和/或y方向的特征尺寸范围为0.5-100μm，优选为1-20μm。所述边壁陡直的微结构40在z方向的深度范围为0.05-10μm，优选为0.1-3μm。
下面介绍图5及图6所示的光学防伪元件成像的光学原理。
如图5所示，以反射情况为例，当边壁陡直的微结构40上无金属层时，光学防伪元件的反射率一般小于20％，故反射再现图像颜色的饱和度和亮度均较低。为了提高再现图像颜色的饱和度与亮度，在反射再现的情况下，金属膜42的预设厚度不为0，该预设厚度的金属膜42能够将反射率提高至80％以上，甚至达到90％。
图5中的反射小面的横向特征尺寸L为70μm，高度H为2μm，斜面的倾角α＝arctg(H/L)，边壁陡直的微结构40的深度h为0.37μm，金属膜42为铝膜且铝膜的预设厚度为30nm。当两束入射光i1、i2入射至表面s1、s2时，被“反射小面3+边壁陡直的微结构40”的表面s1和s2之上的金属膜42反射，形成反射光r1和r2；反射光线r1与其对应的入射光线i1的夹角为2α，同理，反射光线r2与其对应的入射光线i2的夹角亦为2α。如果反射小面3之上无边壁陡直的微结构40，则反射小面3为传统的微反镜结构，白光入射后的反射光之间光程相同，不存在光程差，因此反射光之间相位相同，无干涉现象发生，反射光仍然为白光。但是当边壁陡直的微结构40附着于反射小面3之上后，由于边壁陡直的微结构40的上下表面具有垂直的高度差，因此，反射光r1和r2的光程发生变化，出现光程差，导致反射光r1和r2之间发生干涉现象，最终在反射方向上获得具有特定颜色的反射光，例如，本实施例中的颜色可为黄色。当其他位置处的满足同一菲涅尔反射公式的反射小面3将白光反射到相同的位置时也呈现黄色，也就是说，所有满足同一 菲涅尔反射公式的反射小面3所反射的光线在同一位置处形成聚焦点T，该聚焦点T即为组成图案的一个像素，且该像素为黄色。
如图6所示，以透射情况为例，若反射小面3及边壁陡直的微结构40为透明材料(该透明材料的反射与吸收率均不高)，则更多的光线会透射过反射小面3及边壁陡直的微结构40，即该光学防伪元件具有较高的透过率。在这种情况下可不增加金属膜42，即光学小面3直接裸露在空气中。
图6中的反射小面3的横向特征尺寸为40μm，且倾斜角为10°；边壁陡直的微结构的横向特征周期在3μm至10μm之间变化，且深度为1.2μm。与反射情况类似，当入射光i入射至光学防伪元件1时，通过反射小面3和边壁陡直的微结构40的共同作用，透射光线t汇聚于接收屏8之上，形成黄色的光斑(或像素)。与反射情况的区别之处在于：在反射再现中，光线被边壁陡直的微结构调制时，经该微结构的顶部与底部反射的两束光之间的光程差与2倍的该微结构的深度、微结构表面是否有填充材料及填充材料的折射率等因素相关；而透射再现中，由于微结构表面一般不能有填充材料，经该微结构的顶部与底部的两束光线的光程差与1倍的该微结构的深度相关。由此，为了能够呈现与反射再现时的同一种颜色，透射再现中的微结构的深度要大于反射再现中的微结构的深度，比例大约为2n，其中n为反射再现时填充材料的折射率，无填充材料时n＝1。当然，通过设计金属膜的厚度，还可在反射方向与透射方向同时再现彩色的图文信息，于此不再赘述。
通过适当的设计反射小面3的朝向(倾斜角和/或方位角)和颜色调制结构4的参数(例如，深度)，能够在不同位置呈现不同颜色的像素点，并使这些像素点形成具有实际意义的图文信息。上述反射小面3和颜色调制结构4可以是随机分布的，即在漫反射照明的情况下，不能观察到上述需要再现的图案，只有在由光线照明时才能够从反射和/或透射方向观察到彩色的再现图文信息。
在另一实施例中，所述颜色调制结构4可包括：亚波长微结构41；以及预设厚度的金属膜42，如图7所示。为满足等离子体吸收条件，需在亚波长微结构的表面蒸镀或溅射金属膜。组合反射小面3与颜色调制结构4可形成等离子体反射小面。等离子体反射小面的等离子体共振吸收特性，使得隐藏图像呈现特定的颜色。
亚波长微结构41可以为一维光栅或二维光栅，其中，二维光栅的栅格分布可以是正交结构、蜂窝结构、二维布拉维点阵结构、随机结构等；亚波长微结构的槽型可以是正弦形、矩形或锯齿形等。应当理解的是，亚波长微结构41并不局限于以上描述的结构，而且实际的光学防伪元件中可以采用这些亚波长微结构的拼接或组合。亚波长微结构41优选为二维光栅。
经亚波长微结构41反射的反射谱可根据耦合波理论得到，通过计算模拟分析得到亚波长微结构41的深度(或沟槽深度)、周期、槽型及金属膜都会影响反射谱的共振吸收波长。尤其是沟槽深度的影响尤为明显。
需要说明的是，反射小面3的横向特征尺寸远大于亚波长微结构41的横向特征尺寸。根据等离子体共振条件，可得到亚波长微结构的特征参数。以一维光栅为例，当入射光以角度θ入射到该光栅上时，会产生不同级次的衍射光，衍射光在该光栅表面传播时，与金属膜表面激发的表面等离子体波产生共振，即波矢相等。
k x m＝k sp   (1)
Figure PCTCN2020110024-appb-000001
k x m＝k x+m*k d   (3)
Figure PCTCN2020110024-appb-000002
Figure PCTCN2020110024-appb-000003
Figure PCTCN2020110024-appb-000004
Figure PCTCN2020110024-appb-000005
其中，衍射级次为m，入射光在光栅表面x方向上的分量为k x，光栅波矢为k d，衍射光在光栅表面x方向的分量为k x m，金属膜表面激发的表面等离子体波波矢为k sp，θ为引起共振时的入射光的入射角，λ 0为真空中的波长，n 1为金属膜的折射率，ε 0为入射光在介质中的介电常数，ε 1为金属膜的介电常数。
将公式(2)-(7)带入公式(1)，即可得到亚波长光栅结构的周期d与等离子体共振波长之间的关系：
Figure PCTCN2020110024-appb-000006
由公式(8)可得亚波长光栅结构的周期d。
为了实现多种颜色，上述二维亚波长微浮雕结构的周期是可变的，在x方向和/或y方向上(即横向特征尺寸)的周期范围为50-700nm，优选200-400nm。优选地，亚波长微结构的沟槽深度位于10-500nm的范围内，更为优选地，亚波长微结构的沟槽深度位于50-100nm的范围内。
所述金属膜42的预设厚度小于50nm，优选为小于20nm。金属膜42包括金属层、金属化合物层、高/低折射率材料叠层和法布里-珀罗干涉器中至少一者。其中，金属膜可以为金、银、铜、铝、铁、锡、锌、镍、铬等中一者或多者形成的膜。优选地，金属膜42可为采用蒸镀的方式形成的铝层，且厚度为30nm。当然，还可以在蒸镀金属膜42之前蒸镀单层介质层或者多层介质层。所采用的介质材料可以选自MgF 2、SiO 2、Al 2O 3、MgO、PMMA、TiO 2、ZnS、ZnO中的一者或多者，并且多层介质膜通常采用高低高膜系设计。优选地，采用SiO 2，蒸镀三层结构，光变颜色为黄变绿。对于形成于二维光栅区域之上的三层SiO 2，光变颜色为红色变绿；对于直接形成于反射小面之上的三层SiO 2，光变颜色为黄变绿。
亚波长微结构41或边壁陡直的微结构42(该两者可简称为微结构)在x方向和y方向上可以是周期性的，也可以在一定范围内具有周期性，也可以是随机的。“周期”的含义为在整个光学防伪元件的范围内，所有微结构都是具有相同的排布规律和参数。“一定范围内具有周期性”的含义为在特定小范围内微结构具有相同的排布规律和参数，但是在整个光学防伪元件的范围内微结构不具有相同的排布规律和参数。“随机”含义为在微结构的自身形状参数和排布无相同的规律，是任意分布的。
下面将列举几种能够实现彩色再现图像的微结构的排布方式，如图9(a)-图9(c)所示。其中，图9(a)-图9(c)中由黑渐变至白的方形表示反射小面，黑色表示高度较低，白色表示高度较高，即反射小面为一个个小斜面，特征尺寸为49μm。从图中可以看出反射小面的朝向是变化的(其可根据需要再现图像的内容发生变化)。图9(a)为微结构沿x方向是不变的，沿y方向依次周期性呈现有/无的变化，整体具有周期性，周期为5μm。图9(b)为微结构的另一种排布方式，在该种排布方式中没有个反射小面上的微结构是具有周期性的，但是不同反射小面上的微结构之间是不同的，这种布置方式能够在一定程度上抑制图9(a)中的微结构的周期性带来的衍射干扰，增强再现颜色图案的清晰度。图9(c)中的微结构为圆形结构，且圆形结构的位置是随机变化的。
具体地，下面通过8个实施例对光学防伪元件的具体结构及成像结果进行详细地说明。在各个实施例中，反射小面的横向特征尺寸优选为25μm，纵向特征尺寸的范围优选为0.5-4μm。反射小面为平面结构，并且亚波长微结构为二维光栅结构。
平面波经过反射小面组反射后，传播至接收屏上的再现图像区域。假设反射小面组包括10000个反射小面，而再现图像的像素数为100，则每100个反射小面再现1个像素的隐藏图像，且该100个像素是随机分布的。为了简单说明，与各个实施例相对应的光学防伪元件的结构图中仅列举了几个反射小面。
实施例一、二
所述多个反射小面可为第一组反射小面，该第一组反射小面的倾斜角与方位角由第一菲涅尔公式确定，其中，所述第一菲涅尔公式与入射光线的第一预设入射角及第一预设位置相关。由此，所述第一组反射小面用于将具有所述第一预设入射角的入射光线反射和/或透射到所述第一预设位置，以在所述第一预设位置处呈现第一预设图文信息。所述颜色调制结构可为具有第一调制深度的第一颜色调制结构，用于使所述第一预设图文信息呈现第一预设颜色。
在具有所述第一预设入射角的入射光线照射该光学防伪元件的情况下，在所述第一预设位置处可呈现所述第一预设颜色的所述第一预设图文信息的实像。
对于实施例一
实施例一中的光学防伪元件(如图7所示)可实现反射再现的单一颜色的图像。其中，亚波长微结构上覆盖有30nm厚的铝层，其可起到反射增强的作用。
图7中的三个反射小面的倾斜角与方位角满足同一菲涅尔反射公式(第一预设位置为O点，第一预设入射角为90度)，通过设计由上述三个反射小面组成的多个组合的分布可在O点呈现第一预设图文信息A。由此，可将具有入射角为90度的入射光(例如，白光)反射聚焦到O点处，且呈现图像A的实像。并且，不同反射小面上的亚波长微结构相同(深度为120nm)，由此，该亚波长微结构可将反射小面所反射的光线调制为同一颜色(例如，红色)的光线，从而在O处呈现单一颜色(例如，红色)的图像A。
另外，从整体光学设计来看，当光线入射时，折射光线的延长线也是具有一定汇聚作用的，从而形成图像A(未示出)。该图像A与基材相距较近(可看做基材表面)，且为虚像；相对于再现出的实像A，该虚像A位于实像A的相反一侧。
对于实施例二
与实施例一的区别之处在于：该实施例二中的光学防伪元件(如图8所示)可实现透射再现的单一颜色的图像。
为满足等离子体吸收条件，在亚波长微结构表面需蒸镀或溅射金属层，但金属层是反射层，会减少透射图像的亮度。由此，金属层需要满足一定的厚度要求，才能实现透射再现隐藏图像。换言之，若金属层的厚度过大，即使存在等离子体吸收，也不会在透射方向上观察到再现图像。当金属层的厚度一定时，具有等离子体的反射小面比未具有等离子体的反射小面具有更高的透过率。在本实施例中，亚波长微结构上覆盖有15nm厚的铝层。
图8中的三个反射小面的倾斜角与方位角满足同一菲涅尔透射公式(第一预设位置为O’点，第一预设入射角为90度)，通过设计由上述三个反射小面组成的多个组合的分布可在O’点呈现第一预设图文信息A。由此，可将具有入射角为90度的入射光(例如，白光)透射聚焦到O’点处，且呈现图像A的实像。并且，不同反射小面上的亚波长微结构相同，由此，该亚波长微结构可将反射小面所透射的光线调制为同一颜色的光线，从而在O’处呈现单一颜色的图像A。
另外，从整体光学设计来看，当光线入射时，反射光线的延长线也是具有一定汇聚作用的，从而形成图像A(未示出)。该图像A与基材相距较近(可看做基材表面)，且为虚像；相对于再现出的实像A，该虚像A位于实像A的相反一侧。并且，透射再现的图像A的颜色(例如，蓝色)与反射再现的图像A(例如，红色)的颜色互补。
实施例三、四
所述多个反射小面可为第二组反射小面，该第二组反射小面的倾斜角与方位角由第二菲涅尔公式确定，其中，所述第二菲涅尔公式与入射光线的第二预设入射角及第二预设位置相关。由此，所述第二组反 射小面用于将具有所述第二预设入射角的入射光线反射和/或透射到所述第二预设位置，以在所述第二预设位置处呈现第二预设图文信息。所述颜色调制结构可包括：具有第二调制深度的第二颜色调制结构，用于使所述第二预设图文信息呈现第二预设颜色；以及具有第三调制深度的第三颜色调制结构，用于使所述第二预设图文信息呈现第三预设颜色，所述第二调制深度与所述第三调制深度不同。
在具有所述第二预设入射角的入射光线照射该光学防伪元件的情况下，在所述第二预设位置处呈现由所述第二预设颜色及所述第三预设颜色组成的综合颜色效果的所述第二预设图文信息的实像，和/或在该光学防伪元件的表面处呈现两种不同颜色组成的综合颜色效果的所述第二预设图文信息的虚像。
对于实施例三
实施例三中的光学防伪元件(如图10所示)可实现反射再现的两种颜色的综合颜色效果的图像。其中，亚波长微结构为二维栅格结构，且亚波长微结构的深度不同。反射小面321上的亚波长微结构421与反射小面322上的亚波长微结构422的特征尺寸均为：周期为300nm，深度为120nm，该部分光学防伪元件在白光照射下反射聚焦呈现红色的像素；反射小面323上的亚波长微结构423与反射小面324上的亚波长微结构424的特征尺寸均为：周期为300nm，深度为150nm，该部分光学防伪元件在白光照射下反射聚焦呈现蓝色的像素。亚波长微结构上覆盖有30nm厚的铝层，其可起到反射增强的作用。
四个反射小面满足同一菲涅尔反射公式(第二预设位置为P点，第二预设入射角为90度)，通过设计由上述四个反射小面组成的多个组合的分布可在P点呈现第二预设图文信息A。由此，可将具有入射角为90度的入射光(例如，白光)反射聚焦到P点处，且呈现图像A的实像。并且，亚波长微结构421、422可分别将反射小面321、322所反射的光线调制为红色的光线；亚波长微结构423、424可分别将反射小面323、324所反射的光线调制为蓝色的光线，从而在P处呈现红色与蓝色的混合色的图像A(该图像A为实像)。与此同时，从透射方向来看，在(与P点相比)距基材较近距离处(可看做该光学防伪元件的表面)呈现红色(与反射方向观察到的蓝色互补)与蓝色(与反射方向观察到的红色互补)的混合色的图像A(未示出，该图像A为虚像，其是由折射光线的延长线汇聚而成的)。
当然，也可以设计两组满足不同菲涅尔反射公式的反射小面使得所呈现的图像不同。
对于实施例四
与实施例三的区别之处在于：该实施例四中的光学防伪元件(如图11所示)可实现透射再现的两种颜色的综合颜色效果的图像。本实施例四中的亚波长微结构上覆盖有15nm厚的铝层。
图11中的四个反射小面的倾斜角与方位角满足同一菲涅尔透射公式(第二预设位置为P’点，第二预设入射角为90度)，通过设计由上述四个反射小面组成的多个组合的分布可在P’点呈现第二预设图文信息A。由此，可将具有入射角为90度的入射光(例如，白光)透射聚焦到P’点处，且呈现图像A的实像。并且，亚波长微结构431、432可分别将反射小面331、332所反射的光线调制为蓝色的光线；亚波长微结构433、434可分别将反射小面333、334所反射的光线调制为红色的光线，从而在P’处呈现红色与蓝色的混合色的图像A(该图像A为实像)。与此同时，从反射方向来看，在(与P’点相比)距基材较近距离处(可看作该光学防伪元件表面)呈现蓝色(与透射方向观察到的红色互补)与红色(与透射方向观察到的蓝色互补)的混合色的图像A(未示出，该图像A为虚像，其是由反射光线的延长线汇聚而成的)。
当然，也可以设计两组满足不同菲涅尔透射公式的反射小面使得所呈现的图像不同。
实施例五、六
所述多个反射小面包括：第三组反射小面及第四组反射小面，所述第三组反射小面中的多个反射小面的倾斜角与方位角由第三菲涅尔公式确定，所述第四组反射小面中的多个反射小面的倾斜角与方位角由第四菲涅尔公式确定。其中，所述第三菲涅尔公式与入射光线的第三预设入射角及第三预设位置相关；所 述第四菲涅尔公式与入射光线的第四预设入射角及第四预设位置相关，所述第三预设入射角与所述第四预设入射角不同，所述第三预设位置与所述第五预设位置不同。由此，所述第三组反射小面用于将具有所述第三预设入射角的入射光线反射和/或透射到所述第三预设位置，以在所述第三预设位置处呈现第三预设图文信息；所述第四组反射小面用于将具有所述第四预设入射角的入射光线反射和/或透射到所述第四预设位置，以在所述第四预设位置处呈现第四预设图文信息。所述颜色调制结构为具有第四调制深度的第四颜色调制结构，用于使所述第三预设图文信息与所述第四预设图文信息呈现第四预设颜色。
在具有所述第三预设入射角的入射光线照射该光学防伪元件的情况下，在所述第三预设位置处呈现所述第三预设颜色的所述第三预设图文信息的实像，和/或在具有所述第四预设入射角的入射光线照射下，在所述第四预设位置处呈现所述第四预设颜色的所述第四预设图文信息的实像。
对于实施例五
实施例五中的光学防伪元件(如图12所示)可通过改变白光照射的入射方向a1和a2，实现在反射光方向上依次再现图像A和B。其中，亚波长微结构上覆盖有30nm厚的铝层，其可起到反射增强的作用。并且，不同反射小面上的亚波长微结构相同，由此，该亚波长微结构可将反射小面所反射的光线调制为同一颜色的光线，从而呈现单一颜色的图像A与图像B。
反射小面341、342满足同一菲涅尔反射公式(第三预设位置为S点，第三预设入射角为90度)；反射小面343、344满足同一菲涅尔反射公式(第四预设位置为U点，第四预设入射角为45度)。由此，可通过设计由上述反射小面341、342组成的多个组合的分布可在S点呈现第三预设图文信息A；可通过设计由上述反射小面343、344组成的多个组合的分布可在U点呈现第四预设图文信息B。具体而言，在菲涅尔反射公式中，当入射角为90度和45度时，计算反射小面的斜率和方位角，可以得到两组不同的参数，然后选取每组参数中的1/2重新组成设计参数，且分布规律是随机的。例如，当入射角为90度时，生成100*100个反射小面，该反射小面会再现出图像A；当入射角为45度时，生成100*100个反射小面，该反射小面会再现出图像B；然后，分别选取50*100个反射小面，组成新的100*100个反射小面。由此，可将具有入射角为90度的入射光(例如，白光)反射聚焦到S点处，且呈现图像A的实像；可将具有入射角为45度的射光(例如，白光)反射聚焦到U点处，且呈现图像B的实像。
与上述实施例一、三的情况类似，在该实施例五中，从透射方向来看，在该光学防伪元件表面呈现虚像A或B(未示出)，且其颜色与反射方向观察到的实像A或B的颜色互补。
对于实施例六
与实施例五的区别之处在于：该实施例六中的光学防伪元件(如图13所示)可通过改变白光照射的入射方向a1和a2，实现在透射光方向上依次再现图像A和B。本实施例六中的亚波长微结构上覆盖有15nm厚的铝层。
反射小面351、352满足同一菲涅尔透射公式(第三预设位置为S’点，第三预设入射角为90度)；反射小面353、354满足同一菲涅尔透射公式(第四预设位置为U’点，第四预设入射角为45度)。由此，可通过设计由上述反射小面351、352组成的多个组合的分布可在S’点呈现第三预设图文信息A；可通过设计由上述反射小面353、354组成的多个组合的分布可在U’点呈现第四预设图文信息B。具体而言，在菲涅尔透射公式中，当入射角为90度和45度时，计算反射小面的斜率和方位角，可以得到两组不同的参数，然后选取每组参数中的1/2重新组成设计参数，且分布规律是随机的。由此，可将具有入射角为90度的入射光(例如，白光)透射聚焦到S’点处，且呈现图像A的实像；可将具有入射角为45度的入射光(例如，白光)透射聚焦到U’点处，且呈现图像B的实像。
与上述实施例二、四的情况类似，在该实施例六中，从反射方向来看，在该光学防伪元件表面呈现 虚像A或B(未示出)，且其颜色与透射方向观察到的实像A或B的颜色互补。
当然，入射角可以设置多个参数，但是入射角参数越多，再现图像的亮度越低，且图像之间在再现时会有干扰。另外，该再现效果也可以利用图10中的原理，不同的焦平面处，将会再现出不同颜色的图像。
实施例七、八
所述多个反射小面包括：第五组反射小面及第六组反射小面，所述第五组反射小面中的多个反射小面的倾斜角与方位角由第五菲涅尔公式确定，所述第六组反射小面中的多个反射小面的倾斜角与方位角由第六菲涅尔公式确定。其中，所述第五菲涅尔公式与入射光线的第五预设入射角及第五预设位置相关；所述第六菲涅尔公式与入射光线的第五预设入射角及第六预设位置相关，所述第七预设位置与所述第八预设位置到所述基材的垂直距离不同。由此，所述第五组反射小面用于将具有所述第五预设入射角的入射光线反射和/或透射到所述第五预设位置，以在所述第五预设位置处呈现第五预设图文信息；所述第六组反射小面用于将具有所述第五预设入射角的入射光线反射和/或透射到所述第六预设位置，以在所述第六预设位置处呈现第六预设图文信息。所述颜色调制结构为具有第五调制深度的第五颜色调制结构，用于使所述第五预设图文信息与所述第六预设图文信息呈现第五预设颜色。
在具有所述第五预设入射角的入射光线照射该光学防伪元件的情况下，在所述第五预设位置处呈现所述第五预设颜色的所述第五预设图文信息的实像，以及在所述第六预设位置处呈现所述第五预设颜色的第六预设图文信息的实像。
对于实施例七
实施例七中的光学防伪元件(如图14所示)可实现在反射光方向上的距基材不同距离的焦平面处(例如，距基材5cm和10cm处)呈现图像A和B。其中，亚波长微结构上覆盖有30nm厚的铝层，其可起到反射增强的作用。并且，不同反射小面上的亚波长微结构相同，由此，该亚波长微结构可将反射小面所反射的光线调制为同一颜色的光线，从而呈现单一颜色的图像A与图像B。
反射小面361、362满足同一菲涅尔反射公式(第五预设位置为X点，第五预设入射角为90度)；反射小面363、364满足同一菲涅尔反射公式(第六预设位置为Y点，第五预设入射角为90度)。由此，可通过设计由上述反射小面361、362组成的多个组合的分布可在X点呈现第五预设图文信息B；可通过设计由上述反射小面363、364组成的多个组合的分布可在Y点呈现第六预设图文信息A。具体而言，在菲涅尔反射公式中，当成像焦点位置为X点(例如，距基材表面10cm处)和Y点(例如，距基材表面5cm处)时，计算反射小面的斜率和方位角，可以得到两组不同的参数，然后选取每组参数中的1/2重新组成设计参数，且分布规律是随机的。由此，可将具有入射角为90度的入射光(例如，白光)反射聚焦到X、Y点处，且分别呈现图像B、A的实像。
与上述实施例一、三、五的情况类似，在该实施例七中，从透射方向来看，在该光学防伪元件表面呈现虚像A、B(未示出)，且其颜色与反射方向观察到的实像A、B的颜色互补。
对于实施例八
与实施例七的区别之处在于：该实施例八中的光学防伪元件(如图15所示)可实现在透射光方向上的距基材不同距离的焦平面处(例如，距基材5cm和10cm处)呈现图像A和B。由于等离子体具有共振吸收特性，当白光照射该光学防伪元件时，具有一定的增透作用，且在透射方向上会显现出与实施例七中的反射再现图像的颜色互补的颜色。本实施例八中的亚波长微结构上覆盖有15nm厚的铝层。
反射小面371、372满足同一菲涅尔透射公式(第五预设位置为X’点，第五预设入射角为90度)；反射小面373、374满足同一菲涅尔透射公式(第六预设位置为Y’点，第五预设入射角为90度)。由此，可通过设计由上述反射小面371、372组成的多个组合的分布可在X’点呈现第五预设图文信息B；可通过 设计由上述反射小面373、374组成的多个组合的分布可在Y’点呈现第六预设图文信息A。具体而言，在菲涅尔透射公式中，当成像焦点位置为X’点(例如，距基材表面10cm处)和Y’点(例如，处5cm处)时，计算反射小面的斜率和方位角，可以得到两组不同的参数，然后选取每组参数中的1/2重新组成设计参数，且分布规律是随机的。由此，可将具有入射角为90度的入射光(例如，白光)透射聚焦到X’、Y’点处，且分别呈现图像B、A的实像。
与上述实施例二、四、六的情况类似，在该实施例八中，从反射方向来看，在该光学防伪元件表面呈现虚像A、B(未示出)，且其颜色与透射方向观察到的实像A、B的颜色互补。
当然，该再现效果也可以利用图12中的原理，不同的白光照射角度，将会再现出不同的图像。另外，在本实施例中，还可通过改变亚波长微结构来调制成像的颜色，于此不再赘述。
另外，对于上述各个实施例还可通过设计满足菲涅尔反射公式及菲涅尔透射公式的反射小面组，并选择特定厚度的金属膜，在反射和透射方向同时呈现再现图像的实像，具体的设计细节可参见上述反射再现及透射再现中的具体描述，于此不再赘述。
上述微结构的制版方式有激光制版和电子束直刻制版两种。激光制版的优点是效率高、速度快，深度易控制；缺点是精度不够。而电子束直刻制版的优点是精度高；但是缺点尤其明显，制版速度慢，沟槽深度不易控制，制版工艺不成熟。本发明各个实施例中的微结构采用激光制版的方式制成，由此，图10中的反射小面321、322可再现一个图像，反射小面323、324区域再现另一个图像，形成两种颜色的再现宏观图像。
在制版工艺条件成熟时，在精确控制独立的每一个反射小面上的二维亚波长深度，即能够精确控制再现图像的每一个像素的颜色，形成彩色化的图像。
为了能够使上述光学防伪元件适应现有常用的产品承载物，一般为第一结构的尺寸具有一定的要求。例如反射小面的纵向尺寸(即，高度)不能过高，否则其厚度较高，不能将其埋入纸张之中或贴在承载物之上，造成凹凸不平的后果。因此，反射小面的高度一般小于100μm，优选小于10μm，这样有利于该特征应用于开窗安全线，埋于纸张之中；或者作为宽条产品，贴于纸张或塑料基材之上，并能够保持上述两种情况下基材的平整。
综上所述，本发明创造性地通过多个反射小面将入射光反射和/或透射到预设位置，并通过颜色调制结构调制反射光线和/或透射光线的颜色，以在所述预设位置处呈现出预设颜色的预设图文信息，其可在白光的照射下再现彩色的预设图案，提高了防伪能力和辨识度，从而可实现“易识别，难伪造”的光学防伪元件。
本发明还提供一种防伪产品，该防伪产品可包含上述的光学防伪元件。其中，所述光学防伪元件可以开窗安全线、开窗贴条或贴标等方式置于上述防伪产品中。所述防伪产品可包括钞票、身份证、银行卡、汇票或有价证券等具有高附加值的产品。
以上结合附图详细描述了本发明的优选实施方式，但是，本发明并不限于上述实施方式中的具体细节，在本发明的技术构思范围内，可以对本发明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，本发明对各种可能的组合方式不再另行说明。
此外，本发明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的思想，其同样应当视为本发明所公开的内容。

Claims (15)

  1. 一种光学防伪元件，其特征在于，该光学防伪元件包括：
    基材；
    形成于所述基材上的多个反射小面，用于将入射光线反射和/或透射到预设位置，以在该预设位置处呈现预设的图文信息；以及
    形成于所述反射小面上的颜色调制结构，用于调制所述反射小面所反射和/或透射的光线的颜色，以使所述预设的图文信息呈现预设颜色。
  2. 根据权利要求1所述的光学防伪元件，其特征在于，所述多个反射小面的倾斜角与方位角由菲涅尔公式确定，其中，所述菲涅尔公式与入射光线的预设入射角及所述预设位置相关。
  3. 根据权利要求2所述的光学防伪元件，其特征在于，所述多个反射小面为第一组反射小面，该第一组反射小面的倾斜角与方位角由第一菲涅尔公式确定，其中，所述第一菲涅尔公式与入射光线的第一预设入射角及第一预设位置相关，所述第一组反射小面用于将具有所述第一预设入射角的入射光线反射和/或透射到所述第一预设位置，以在所述第一预设位置处呈现第一预设图文信息，
    所述颜色调制结构为具有第一调制深度的第一颜色调制结构，用于使所述第一预设图文信息呈现第一预设颜色，
    在具有所述第一预设入射角的入射光线照射该光学防伪元件的情况下，在所述第一预设位置处呈现所述第一预设颜色的所述第一预设图文信息的实像。
  4. 根据权利要求2所述的光学防伪元件，其特征在于，所述多个反射小面为第二组反射小面，该第二组反射小面的倾斜角与方位角由第二菲涅尔公式确定，其中，所述第二菲涅尔公式与入射光线的第二预设入射角及第二预设位置相关，所述第二组反射小面用于将具有所述第二预设入射角的入射光线反射和/或透射到所述第二预设位置，以在所述第二预设位置处呈现第二预设图文信息，
    所述颜色调制结构包括：具有第二调制深度的第二颜色调制结构，用于使所述第二预设图文信息呈现第二预设颜色；以及具有第三调制深度的第三颜色调制结构，用于使所述第二预设图文信息呈现第三预设颜色，所述第二调制深度与所述第三调制深度不同，
    在具有所述第二预设入射角的入射光线照射该光学防伪元件的情况下，在所述第二预设位置处呈现由所述第二预设颜色及所述第三预设颜色组成的综合颜色效果的所述第二预设图文信息的实像。
  5. 根据权利要求2所述的光学防伪元件，其特征在于，所述多个反射小面包括：第三组反射小面及第四组反射小面，所述第三组反射小面中的多个反射小面的倾斜角与方位角由第三菲涅尔公式确定，所述第四组反射小面中的多个反射小面的倾斜角与方位角由第四菲涅尔公式确定，其中，所述第三菲涅尔公式与入射光线的第三预设入射角及第三预设位置相关；所述第四菲涅尔公式与入射光线的第四预设入射角及第 四预设位置相关，所述第三预设入射角与所述第四预设入射角不同，所述第三预设位置与所述第四预设位置不同，
    所述第三组反射小面用于将具有所述第三预设入射角的入射光线反射和/或透射到所述第三预设位置，以在所述第三预设位置处呈现第三预设图文信息；所述第四组反射小面用于将具有所述第四预设入射角的入射光线反射和/或透射到所述第四预设位置，以在所述第四预设位置处呈现第四预设图文信息，
    所述颜色调制结构为具有第四调制深度的第四颜色调制结构，用于使所述第三预设图文信息与所述第四预设图文信息呈现第四预设颜色，
    在具有所述第三预设入射角的入射光线照射该光学防伪元件的情况下，在所述第三预设位置处呈现所述第三预设颜色的所述第三预设图文信息的实像，和/或在具有所述第四预设入射角的入射光线照射下，在所述第四预设位置处呈现所述第四预设颜色的所述第四预设图文信息的实像。
  6. 根据权利要求2所述的光学防伪元件，其特征在于，所述多个反射小面包括：第五组反射小面及第六组反射小面，所述第五组反射小面中的多个反射小面的倾斜角与方位角由第五菲涅尔公式确定，所述第六组反射小面中的多个反射小面的倾斜角与方位角由第六菲涅尔公式确定，其中，所述第五菲涅尔公式与入射光线的第五预设入射角及第五预设位置相关；所述第六菲涅尔公式与入射光线的第五预设入射角及第六预设位置相关，所述第七预设位置与所述第八预设位置到所述基材的垂直距离不同，
    所述第五组反射小面用于将具有所述第五预设入射角的入射光线反射和/或透射到所述第五预设位置，以在所述第五预设位置处呈现第五预设图文信息；所述第六组反射小面用于将具有所述第五预设入射角的入射光线反射和/或透射到所述第六预设位置，以在所述第六预设位置处呈现第六预设图文信息，
    所述颜色调制结构为具有第五调制深度的第五颜色调制结构，用于使所述第五预设图文信息与所述第六预设图文信息呈现第五预设颜色，
    在具有所述第五预设入射角的入射光线照射该光学防伪元件的情况下，在所述第五预设位置处呈现所述第五预设颜色的所述第五预设图文信息的实像，以及在所述第六预设位置处呈现所述第五预设颜色的第六预设图文信息的实像。
  7. 根据权利要求1所述的光学防伪元件，其特征在于，所述颜色调制结构包括：
    预设厚度的金属膜；以及
    边壁陡直的微结构，或者亚波长微结构。
  8. 根据权利要求7所述的光学防伪元件，其特征在于，在所述颜色调制结构为所述边壁陡直的微结构的情况下，所述边壁陡直的微结构的深度范围为0.05-10μm。
  9. 根据权利要求7所述的光学防伪元件，其特征在于，在所述颜色调制结构为所述边壁陡直的微结构的情况下，所述边壁陡直的微结构沿其所在的二维平面内的两个方向中至少一个方向的周期范围为 0.5-100μm。
  10. 根据权利要求7所述的光学防伪元件，其特征在于，在所述颜色调制结构为所述亚波长微结构的情况下，所述亚波长微结构的槽的深度范围为50-100nm。
  11. 根据权利要求7所述的光学防伪元件，其特征在于，在所述颜色调制结构为所述亚波长微结构的情况下，所述亚波长微结构的槽的形状为正弦形、矩形或锯齿形。
  12. 根据权利要求7所述的光学防伪元件，其特征在于，在所述颜色调制结构为所述亚波长微结构的情况下，所述亚波长微结构沿其所在的二维平面延伸的两个方向中至少一个方向上的周期范围为50-700nm。
  13. 根据权利要求1所述的光学防伪元件，其特征在于，所述反射小面沿其所在的二维平面内的两个方向中至少一个方向的周期范围为0.5-500μm。
  14. 一种防伪产品，其特征在于，该防伪产品包含根据权利要求1-13中任一项权利要求所述的光学防伪元件。
  15. 根据权利要求14所述的防伪产品，其特征在于，所述防伪产品包括钞票、身份证、银行卡或汇票。
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