Optical anti-counterfeiting element and anti-counterfeiting product

Abstract

The invention provides an optical anti-counterfeiting element and an anti-counterfeiting product. The optical anti-fake element comprises a base material and a plating layer, a partial area of at least one surface of the base material is provided with an optical microstructure, the plating layer is arranged on the surface of the side, away from the base material, of the optical microstructure, the optical density of the plating layer is larger than 1, and the optical microstructure is provided with optical microstructure units. At least 200 optical microstructure units are contained in the cross section of at least a local area of the optical microstructure within the span range per millimeter, and the depth of at least one part of the optical microstructure meets the following conditions: when a light beam irradiates the optical microstructure at an incident angle, the light beam is irradiated to the optical microstructure; light of a wavelength or a wavelength range in the light beam is long in interference in the reflected light direction and the transmitted light direction, presents a first color in the reflected light direction and the transmitted light direction and presents a second color in at least one direction near the reflected light, and the first color and the second color are complementary colors. The problems that in the prior art, an optical anti-counterfeiting element is unclear in anti-counterfeiting feature and difficult to manufacture are solved.

Description

Technical Field

[0001] This invention relates to the field of anti-counterfeiting, and more specifically, to an optical anti-counterfeiting element and an anti-counterfeiting product. Background Technology

[0002] To prevent counterfeiting through scanning and photocopying, diffraction-modified optical image (DMO) security features (such as holograms and dynamic diffraction patterns) are widely used in high-security or high-value-added printed materials such as banknotes, certificates, and product packaging, achieving excellent results. For example, high-denomination Euro banknotes use DMO hot-stamped markings, while low-denomination banknotes use wide DMO hot-stamped stripes. The 2005 edition of the Renminbi, except for the one-yuan note, uses a windowed security thread with a DMO image. Visa, MasterCard, and UnionPay credit cards use DMO hot-stamped markings, and important documents such as ID cards, driver's licenses, and passports also employ DMO security technology. To date, most banknotes, credit cards, passports, and other security documents worldwide utilize DMO security technology.

[0003] The diffraction optical variable image used for anti-counterfeiting is a grating with an embossed structure. When illumination light (such as natural light) shines on its surface, diffraction occurs, and the first-order (or -1st-order) diffracted light is used to form a reproduced image, achieving eye-catching dynamic, three-dimensional, color-changing and other popular anti-counterfeiting features.

[0004] With the increasing popularity of diffraction optical variable imaging technology, it has been widely used in general commodities and packaging, such as the packaging of cigarettes, alcohol, and pharmaceuticals, and even the labels of textiles and toys. However, this anti-counterfeiting technology is becoming increasingly easy to implement, significantly reducing its effectiveness. Therefore, a new and more reliable anti-counterfeiting technology is needed.

[0005] Chinese patent application CN104249597 discloses an optical anti-counterfeiting element, the microstructure of which is defined such that when a light beam is irradiated at an incident angle, light of a wavelength or wavelength range in the beam undergoes constructive interference in the direction of transmission or reflection. This optical anti-counterfeiting element differs from the aforementioned diffraction-based optical patterns, avoiding interference from diffracted light with uncertain colors and rainbow characteristics. Instead, it utilizes easily describable, color-stable light formed by interference mechanisms. This allows the area covered by the microstructure in the optical anti-counterfeiting element to form specific patterns with high recognizability and difficulty in counterfeiting. However, given the increasingly urgent need for high-level anti-counterfeiting technology in products such as banknotes and identity documents, this optical anti-counterfeiting element needs further improvement in its uniqueness and recognizability.

[0006] Theoretically speaking, the color characteristics formed by constructive interference in the direction of transmitted light of the optical anti-counterfeiting element in Chinese patent application CN104249597 also depend on the refractive index difference of two at least semi-transparent materials. Such requirements on materials and structure are difficult to apply, and its color characteristics are different from those formed by constructive interference in the direction of reflected light.

[0007] In other words, existing optical anti-counterfeiting elements suffer from unclear anti-counterfeiting features and manufacturing difficulties. Summary of the Invention

[0008] The main objective of this invention is to provide an optical anti-counterfeiting element and an anti-counterfeiting product to solve the problems of unclear anti-counterfeiting features and manufacturing difficulties in existing optical anti-counterfeiting elements.

[0009] To achieve the above objectives, according to one aspect of the present invention, an optical anti-counterfeiting element is provided. The optical anti-counterfeiting element includes a substrate and a coating. At least a portion of the surface of the substrate has an optical microstructure. The coating is disposed on the side of the optical microstructure away from the substrate. The optical density of the coating is greater than 1. The optical microstructure has optical microstructure units. At least 200 optical microstructure units are contained within a span of one millimeter in at least a local region of the optical microstructure. The depth of at least a portion of the optical microstructure satisfies the following: when a light beam irradiates the optical microstructure at an incident angle, light of a wavelength or wavelength range in the light beam is constructively interfered in both the reflected light direction and the transmitted light direction, and exhibits a first color in both the reflected light direction and the transmitted light direction, and exhibits a second color in at least one direction near the reflected light, wherein the first color and the second color are complementary colors.

[0010] Furthermore, at least a portion of the optical microstructure units are randomly or pseudo-randomly distributed, and the feature size of the optical microstructure units is greater than 0.3 micrometers and less than 6 micrometers. The depth of the optical microstructure units satisfies the following condition: when a light beam illuminates the optical microstructure at an incident angle, at least a portion of the optical microstructure exhibits a second color in the direction of scattered light.

[0011] Furthermore, at least a portion of the optical microstructure units are randomly or pseudo-randomly distributed in the second direction. The feature size of the optical microstructure units in the second direction is greater than 0.3 micrometers and less than 6 micrometers, and the feature size in the first direction is greater than 6 micrometers. The depth of the optical microstructure units satisfies the following condition: when a light beam irradiates the optical microstructure unit at an incident angle, if the light beam is in a first plane that is perpendicular to the plane of the substrate and includes the second direction, then at least a portion of the optical microstructure will have a second color in the direction of scattered light in the first plane.

[0012] Furthermore, at least a portion of the optical microstructure units are periodically distributed in the first direction and randomly or pseudo-randomly distributed in the second direction. The feature size of the optical microstructure units in the first direction is greater than 0.3 micrometers and less than 6 micrometers, and the feature size in the second direction is greater than 0.3 micrometers and less than 6 micrometers. The depth of the optical microstructure units satisfies the following: when a light beam illuminates the optical microstructure unit at an incident angle, if the light beam is in a first plane perpendicular to the plane of the substrate and including the second direction, at least a portion of the optical microstructure exhibits a second color in the direction of scattered light in the first plane; if the light beam is in a second plane perpendicular to the plane of the substrate and including the first direction, at least a portion of the optical microstructure exhibits a +1 or -1 order diffraction color that varies with the angle in the direction of diffraction light in the second plane.

[0013] Furthermore, the coating is a single-layer coating, and the single-layer coating includes at least one of a metal reflective layer, a semiconductor material layer, and a dielectric layer.

[0014] Furthermore, the coating is a multi-layer coating, and the multi-layer coating forms a Fabry-Poisson resonant cavity.

[0015] Furthermore, the coating is a multilayer coating, which includes at least two of an absorption layer, a dielectric layer, and a reflective layer; or the multilayer coating includes multiple dielectric layer groups.

[0016] Furthermore, the coating has a perforated pattern.

[0017] Furthermore, the cross-sectional shape of the optical microstructure unit includes at least one of sinusoidal, trapezoidal, and rectangular shapes.

[0018] Furthermore, the optical anti-counterfeiting element includes a secondary optical microstructure that is essentially isomorphic overlaid on the optical microstructure.

[0019] Furthermore, the secondary optical microstructure includes at least one of holographic diffraction microstructures and subwavelength microstructures.

[0020] Furthermore, the groove shape of the holographic diffraction microstructure includes at least one of the following: arc-shaped, sinusoidal, rectangular, and sawtooth-shaped.

[0021] Furthermore, the holographic diffraction microstructure has a feature size greater than 0.5 micrometers and less than 5 micrometers in the two-dimensional plane it resides in, and a groove depth greater than 50 nanometers.

[0022] Furthermore, the subwavelength microstructure is a one-dimensional grating or a two-dimensional grating, and the groove shape of the subwavelength microstructure is at least one of arc shape, sinusoidal shape, rectangular shape, and sawtooth shape.

[0023] Furthermore, the subwavelength microstructure has a feature size greater than 0.05 micrometers and less than 0.5 micrometers in the two-dimensional plane, and a groove depth greater than 10 nanometers.

[0024] According to another aspect of the present invention, an anti-counterfeiting product is provided, which includes the aforementioned optical anti-counterfeiting element.

[0025] According to the technical solution of the present invention, the optical anti-counterfeiting element includes a substrate and a coating. At least one surface of the substrate has a portion of an optical microstructure. The coating is disposed on the side of the optical microstructure away from the substrate. The optical density of the coating is greater than 1. The optical microstructure has optical microstructure units. At least 200 optical microstructure units are contained within a span of each millimeter in at least a local region of the optical microstructure. The depth of at least a portion of the optical microstructure satisfies the following: when a light beam irradiates the optical microstructure at an incident angle, light of a wavelength or wavelength range in the light beam is constructively interfered in both the reflected light direction and the transmitted light direction, and exhibits a first color in both the reflected light direction and the transmitted light direction, and exhibits a second color in at least one direction near the reflected light, wherein the first color and the second color are complementary colors.

[0026] By setting at least 200 optical microstructure units on at least a portion of the optical microstructure, the incident light beam can undergo reflection, transmission, scattering, or diffraction. By setting the depth of at least a portion of the optical microstructure, it is ensured that the incident light of a certain wavelength, after passing through a specific position and path, satisfies the condition of constructive interference in both the reflected and transmitted light directions, causing at least a portion of the optical microstructure to exhibit a first color. Therefore, the first color can be observed in both the reflected and transmitted light directions, giving the optical anti-counterfeiting element unique anti-counterfeiting features and improving its level of easy identification and difficulty in counterfeiting. In addition, the lack of the first color in the reflected light causes a second color, complementary to the first color, to appear in at least one direction near the reflected light, increasing the uniqueness of the optical anti-counterfeiting element. By flexibly designing the depth of at least a portion of the optical microstructure, the difficulty of counterfeiting is increased, which is conducive to meeting high anti-counterfeiting requirements and expanding the application range of the optical anti-counterfeiting element. By setting a coating 4 on the surface away from the substrate, the incident light is mainly reflected by the coating when passing through the optical microstructure unit, enhancing the intensity of the reflected light and facilitating the observation of the first color feature. Further reducing stray light transmitted through the optical microstructure unit improves the purity of the first color of the transmitted light required for constructive interference, while simultaneously increasing the intensity of the reflected light with the first color characteristic in the direction of constructive interference. Furthermore, at the steep sidewalls of the optical microstructure unit, some incident light can penetrate the coating and exit directly, or enter the optical microstructure unit and be reflected before exiting in the direction of transmitted light, enabling constructive interference between these two types of light, thus achieving the presentation of the first color in both the reflected and transmitted light directions. Attached Figure Description

[0027] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0028] Figure 1 A cross-sectional schematic diagram of an optical anti-counterfeiting element according to Embodiment 1 of the present invention is shown;

[0029] Figure 2 A schematic diagram of the reflected light principle of a portion of the optical microstructure of an optical anti-counterfeiting element according to Embodiment 1 of the present invention is shown;

[0030] Figure 3 A schematic diagram of the transmission light principle of a portion of the optical microstructure of an optical anti-counterfeiting element according to Embodiment 1 of the present invention is shown.

[0031] Figure 4 A schematic diagram illustrating the prior art features of a portion of the optical microstructure of an optical anti-counterfeiting element according to Embodiment 1 of the present invention is shown.

[0032] Figure 5 A top view of the optical microstructure of an optical anti-counterfeiting element according to Embodiment 2 of the present invention is shown;

[0033] Figure 6 A cross-sectional view of the optical microstructure of an optical anti-counterfeiting element according to Embodiment 2 of the present invention is shown;

[0034] Figure 7 A simplified cross-sectional diagram of the optical microstructure of the optical anti-counterfeiting element according to Embodiment 2 of the present invention is shown;

[0035] Figure 8 Another simplified cross-sectional view of the optical microstructure of the optical anti-counterfeiting element according to Embodiment 2 of the present invention is shown;

[0036] Figure 9 A top view of the optical microstructure of an optical anti-counterfeiting element according to Embodiment 3 of the present invention is shown;

[0037] Figure 10 A cross-sectional view of the optical microstructure of an optical anti-counterfeiting element according to Embodiment 3 of the present invention is shown;

[0038] Figure 11 A top view of the optical microstructure of an optical anti-counterfeiting element according to Embodiment 4 of the present invention is shown;

[0039] Figure 12 A cross-sectional view of the optical microstructure of an optical anti-counterfeiting element according to Embodiment 4 of the present invention is shown;

[0040] Figure 13A cross-sectional view of the optical microstructure of the optical anti-counterfeiting element according to Embodiment 4 of the present invention is shown in another dimension.

[0041] Figure 14 A cross-sectional view of the optical microstructure of an optical anti-counterfeiting element according to Embodiment 5 of the present invention is shown.

[0042] The above figures include the following reference numerals:

[0043] 2. Substrate; 201. Upper surface area; 202. Local optical microstructure; 3. Optical microstructure; 4. Coating; 5. Secondary optical microstructure; M. Direction; O1. First incident light; O2. Second incident light; O1'. First reflected light; O2'. Second reflected light; O1”. First transmitted light; O2”. Second transmitted light; O1”'. Third transmitted light; O2”'. Fourth transmitted light; I. Incident light; R. Reflected light; T. Transmitted light; S. Scattered light; D1. +1st order diffraction light; D2. -1st order diffraction light. Detailed Implementation

[0044] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0045] It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0046] In this invention, unless otherwise stated, directional terms such as "upper," "lower," "top," and "bottom" are generally used in relation to the direction shown in the accompanying drawings, or in relation to the vertical, perpendicular, or gravitational direction of the component itself; similarly, for ease of understanding and description, "inner" and "outer" refer to the inner and outer contours of each component itself, but the above directional terms are not intended to limit this invention.

[0047] In this paper, "characteristic dimension" refers to the dimension in any direction of the optical microstructure 3, which is formed by dividing the surface by taking the average of the lowest and highest points of its surface height, thereby creating a contour that surrounds the protruding or concave part.

[0048] "Optical microstructure unit" refers to a single protrusion or depression formed by dividing the surface of an optical microstructure 3 by taking the average of the lowest and highest points of its surface height, with its characteristic size on the order of micrometers.

[0049] "Depth of optical microstructure 3" refers to the height difference between the highest and lowest points on the surface of the micro-relief structure.

[0050] To address the problems of unclear anti-counterfeiting features and manufacturing difficulties in existing optical anti-counterfeiting elements, this invention provides an optical anti-counterfeiting element and an anti-counterfeiting product. This application achieves the same color characteristics in both reflected and transmitted light directions, as well as a complementary color in at least one direction near the reflected light direction, by controlling the depth of the optical microstructure 3, the density of the optical microstructure units, and the arrangement of the coating layer 4. This results in an optical anti-counterfeiting element with unique color characteristics that is easy to mass-produce and apply.

[0051] like Figures 1 to 14 As shown, the optical anti-counterfeiting element includes a substrate 2 and a coating 4. At least one surface of the substrate 2 has a portion of an optical microstructure 3. The coating 4 is disposed on the side of the optical microstructure 3 away from the substrate 2, and the optical density of the coating 4 is greater than 1. The optical microstructure 3 has optical microstructure units. At least 200 optical microstructure units are contained within a span of one millimeter in at least a local region of the optical microstructure 3. The depth of at least a portion of the optical microstructure 3 satisfies the following: when a light beam irradiates the optical microstructure 3 at an incident angle, light of a wavelength or wavelength range in the light beam is constructively interfered in both the reflected light direction and the transmitted light direction, and exhibits a first color in both the reflected light direction and the transmitted light direction, and exhibits a second color in at least one direction near the reflected light, wherein the first color and the second color are complementary colors.

[0052] By setting at least 200 optical microstructure units on at least a portion of the optical microstructure 3, the incident light beam can undergo reflection, transmission, scattering, or diffraction. By setting the depth of at least a portion of the optical microstructure 3, it is ensured that the incident light of a certain wavelength, after passing through a specific position and path, satisfies the condition of constructive interference in both the reflected and transmitted light directions, causing at least a portion of the optical microstructure 3 to exhibit a first color. Therefore, the first color can be observed in both the reflected and transmitted light directions, giving the optical anti-counterfeiting element unique anti-counterfeiting features and improving its level of easy identification and difficulty in counterfeiting. In addition, the lack of the first color in the reflected light causes a second color, complementary to the first color, to appear in at least one direction near the reflected light, increasing the uniqueness of the optical anti-counterfeiting element. By flexibly designing the depth of at least a portion of the optical microstructure 3, the difficulty of counterfeiting is increased, which is conducive to the optical anti-counterfeiting element meeting high anti-counterfeiting requirements and expanding the application range of the optical anti-counterfeiting element. By setting a coating 4 on the surface away from the substrate 2, the incident light is mainly reflected by the coating 4 when passing through the optical microstructure unit, enhancing the intensity of the reflected light and facilitating the observation of the first color feature. Further reducing stray light transmitted through the optical microstructure unit improves the purity of the first color of the transmitted light required for constructive interference, while simultaneously increasing the intensity of the reflected light with the first color characteristic and constructive interference in the reflected light direction. Furthermore, at the steep sidewalls of the optical microstructure unit, some incident light can penetrate the coating 4 and exit directly, or it can enter the optical microstructure unit, be reflected, and then exit in the direction of transmitted light, enabling constructive interference between these two types of light, thus achieving the first color in both the reflected and transmitted light directions.

[0053] The following detailed explanation uses a one-dimensional rectangular optical microstructure 3 as an example.

[0054] like Figure 1 As shown, the optical anti-counterfeiting element includes a substrate 2; the upper surface region 201 of the substrate 2 has an optical microstructure 3, and the optical microstructure 3 is a one-dimensional rectangular structure, and the surface of the optical microstructure 3 has a coating 4.

[0055] like Figure 2 and Figure 3 As shown, select Figure 1 Local optical microstructure 202 of optical microstructure 3. Figure 2A first incident light O1 from sunlight illuminates the raised portion of the rectangular outline of the optical microstructure 3 at a specific angle, and its reflected light is the first reflected light O1'. A second incident light O2, parallel to the direction of the first incident light O1, illuminates the recessed portion of the rectangular outline of the optical microstructure 3, and its reflected light is the second reflected light O2'. Therefore, the first reflected light O1' and the second reflected light O2' will interfere in the direction of the reflected sunlight. Corresponding to the incident angle and the depth of the optical microstructure, light within the wavelength range corresponding to the first color will exhibit constructive interference in the direction of the reflected light.

[0056] At the same time, such as Figure 3 As shown, at the steep sidewalls of the rectangular outline, some incident light can pass through in two special ways. The coating 4 is relatively thin at the steep sidewalls, allowing the first incident light O1 to partially pass through, forming the first transmitted light O1”; the coating 4 is relatively thick at the concave or convex portions of the rectangular outline, allowing the second incident light O2 to be reflected twice at adjacent concave and convex locations, forming the second transmitted light O2”. The first transmitted light O1” and the second transmitted light O2” have the same interference phase wavelength as the first reflected light O1’ and the second reflected light O2’, thus forming transmitted light with the same first color.

[0057] Furthermore, the thickness of coating 4 is relatively thick in the recessed or raised portions of the rectangular outline, thereby ensuring that the intensity of transmitted light is sufficiently low in the areas other than the steep sidewalls. This results in higher purity of the transmitted light with the first color. The relatively thick thickness of coating 4 in the recessed or raised portions of the rectangular outline also ensures that the reflected light with the first color characteristics, exhibiting constructive interference in the direction of reflected light, is sufficiently strong.

[0058] Since the area occupied by the steep sidewall is relatively small, in order to ensure the proportion of transmitted light, the optical microstructure 3 is designed to contain at least 200 optical microstructure units per millimeter span within the cross-section of at least a local area, thereby increasing the density of the steep sidewall and ensuring the intensity of transmitted light.

[0059] Preferably, the optical microstructure 3 contains at least 500 optical microstructure units per millimeter span within the cross-section of at least a local region of the optical microstructure 3. More preferably, the optical microstructure 3 contains at least 1000 optical microstructure units per millimeter span within the cross-section of at least a local region of the optical microstructure 3, thereby increasing the density of the steep sidewalls and increasing the proportion of transmitted light per unit area within the upper surface region 201 of the substrate 2. This is beneficial for observing the first color feature in the direction of transmitted light and ensures the anti-counterfeiting effect of the optical anti-counterfeiting element.

[0060] And in existing technologies, it is as follows: Figure 4As shown, the upper refractive index of the rectangular outline of optical microstructure 3 is n1, and the refractive index of optical microstructure 3 is n2. Then, the optical path difference between the third transmitted light O1”' and the fourth transmitted light O2”' formed by the first incident light O1 and the second incident light O2 passing through the concave and convex positions of the rectangle, respectively, is approximately |n1-n2|*d. This optical path difference is related to... Figure 2 or Figure 3 The optical path difference between the corresponding constructive interference of reflected and transmitted light differs, making it impossible to provide a first color feature in the direction of transmitted light. Furthermore, according to the formula, the first color feature formed by constructive interference in the direction of transmitted light depends on the refractive index difference |n1-n2| between the two at least two semi-transparent materials. Typically, this refractive index difference is no greater than 0.5, resulting in a small optical path difference. Increasing the optical path difference places stringent requirements on the material and structural depth, making it difficult to apply. Moreover, apart from the wavelength portion satisfying constructive interference, most of the incident light is transmitted without being reflected or absorbed, creating background noise beyond the transmitted light color. This noise can easily burn the eyes and results in low color purity in the transmitted light, making it difficult to identify. Figure 4 The mechanisms shown not only differ in their optical anti-counterfeiting features, but also in their requirements for the coating 4, which contradict the optical anti-counterfeiting element of this invention. This invention requires the coating 4 to be sufficiently thick, while... Figure 4 The requirement is that coating 4 is thin enough, or even that coating 4 can be completely removed.

[0061] It should be noted that the upper refractive index of the rectangular outline of the optical microstructure 3 refers to the refractive index of the environment in which the upper part is located. If the upper part of the optical microstructure 3 is in the air, then the refractive index is the refractive index of air, i.e., 1.

[0062] Preferably, the optical density of the coating 4 is greater than 2, and more preferably, the optical density of the coating 4 is greater than 3, thereby increasing the reflectivity and decreasing the transmittance of the concave and convex portions of the rectangular outline of the optical microstructure 3. Furthermore, the intensity of transmitted light in portions other than the steep sidewalls is sufficiently low, improving the color purity of the transmitted light and enhancing the intensity of the constructively interfering reflected light of a specific color in the direction of reflected light.

[0063] Optionally, coating 4 can be formed by PVD vapor deposition.

[0064] The depth of the optical microstructure 3 is typically greater than 100 nanometers and less than 5 micrometers. Preferably, the depth of the optical microstructure 3 is greater than 200 nanometers and less than 3 micrometers. The depth can be determined by the following method.

[0065] ① Represents the complex amplitude transmittance τ of optical microstructure 3. g , τ g ① is a function of depth, design wavelength λ, groove shape of optical microstructure 3, material refractive index distribution n, and position (x,y); ② is a function of complex amplitude transmittance τ.g Perform a Fourier transform; ③ Find the condition under which the reflected light (i.e., the zeroth-order diffraction light) with wavelength λ is maximized; ④ Calculate the depth based on the condition under which the reflected light is maximized.

[0066] To illustrate with an example, consider a design wavelength λ = 600 nm, a refractive index n = 1.5 for the material of optical microstructure 3, a sinusoidal cross-sectional shape for optical microstructure 3, and air as the external medium. When d = 1528.8 nm, the light appears red in both the reflected and transmitted light directions, and bluish-green in the scattered light direction. If d = 2668.8 nm, since the light with a wavelength of 410.8 nm also satisfies the condition of constructive interference in both the reflected and transmitted light directions, it appears magenta in both the reflected and transmitted light directions, and green in the scattered light direction.

[0067] The optical microstructure 3 can be made into a master template using methods such as laser etching, electron beam etching, and ion etching, and then copied onto the substrate 2 through processes such as electroforming, molding, and UV (ultraviolet) replication. A more common process is to coat an imaging layer on the surface of the substrate 2 and then copy the optical microstructure 3 onto the imaging layer, thereby improving the replication quality and efficiency of the optical microstructure 3. This is beneficial for the mass production and application of optical anti-counterfeiting components and reduces production costs.

[0068] Optionally, at least a portion of the optical microstructure units of the optical anti-counterfeiting element are randomly or pseudo-randomly distributed. The feature size of the optical microstructure unit is greater than 0.3 micrometers and less than 6 micrometers. The depth of the optical microstructure 3 satisfies the following condition: when a light beam illuminates the optical microstructure 3 at an incident angle, at least a portion of the optical microstructure 3 exhibits a second color in the direction of scattered light. By limiting the feature size of the optical microstructure unit to greater than 0.3 micrometers, the difficulty of constructive interference of reflected light due to excessively small feature size is avoided, as is the reduction in the proportion of reflected light satisfying the constructive interference condition, which would affect the observation of the first color feature in the direction of reflected light. Simultaneously, the reduction in the proportion of scattered light is avoided, thus affecting the observation of the second color feature in the direction of scattered light. Furthermore, the difficulty in manufacturing due to excessively small feature size of the optical microstructure unit is avoided, facilitating the mass production of the optical anti-counterfeiting element. By limiting the feature size of the optical microstructure unit to less than 6 micrometers, the density of the optical microstructure unit is avoided, as excessively large feature size would reduce the intensity of transmitted light, increasing the difficulty of observing the first color feature in the direction of transmitted light and affecting the anti-counterfeiting effect of the optical anti-counterfeiting element.

[0069] Of course, at least a portion of the optical microstructure units can be randomly or pseudo-randomly distributed in the second direction. The feature size of the optical microstructure units in the second direction is greater than 0.3 micrometers and less than 6 micrometers, and the feature size in the first direction is greater than 6 micrometers. The depth of the optical microstructure 3 satisfies the following: when the light beam irradiates the optical microstructure unit at an incident angle, if the light beam is in a first plane that is perpendicular to the plane where the substrate 2 is located and includes the second direction, then at least a portion of the optical microstructure 3 will have a second color in the direction of the scattered light in the first plane.

[0070] Of course, at least a portion of the optical microstructure units can be periodically distributed in the first direction and randomly or pseudo-randomly distributed in the second direction. The characteristic size of the optical microstructure units in the first direction is greater than 0.3 micrometers and less than 6 micrometers, and the characteristic size in the second direction is greater than 0.3 micrometers and less than 6 micrometers. The depth of the optical microstructure 3 satisfies the following: when a light beam irradiates the optical microstructure unit at an incident angle, if the light beam is in a first plane that is perpendicular to the plane where the substrate 2 is located and includes the second direction, then at least a portion of the optical microstructure 3 exhibits a second color in the direction of scattered light in the first plane; if the light beam is in a second plane that is perpendicular to the plane where the substrate 2 is located and includes the first direction, then at least a portion of the optical microstructure 3 exhibits a +1 or -1 order diffraction color that varies with the angle in the direction of diffraction light in the second plane. By restricting at least a portion of the optical microstructure units to a periodic distribution in the first direction, with feature sizes greater than 0.3 micrometers and less than 6 micrometers, while ensuring that both reflected and transmitted light undergo constructive interference and present the first color of the anti-counterfeiting feature, the diffracted light direction in the second plane containing the first direction presents a +1 or -1 order diffracted light color that varies with the angle. This is beneficial for enhancing the color recognition features of the optical anti-counterfeiting element, while also increasing the difficulty of counterfeiting, which is conducive to higher-level anti-counterfeiting applications.

[0071] It should be noted that random distribution refers to a distribution without any pattern, while pseudo-random distribution refers to a distribution that appears to be random but actually follows a specified rule.

[0072] Optionally, the coating 4 can be a single-layer coating. By setting the coating 4 to be a single layer, it is advantageous to deposit the coating 4 onto the optical microstructure 3, thereby improving processing efficiency and reducing manufacturing costs. The single-layer coating can be at least one of a metal reflective layer, a semiconductor material layer, and a dielectric layer.

[0073] Of course, coating 4 can be multi-layered, forming a Fabry-Perot resonant cavity. The Fabry-Perot resonant cavity formed by the multi-layered coating selectively absorbs and reflects incident white light, allowing for better control over the emitted light to contain only certain wavelengths, thus creating specific colors. When the incident or exit angle of light changes, the corresponding optical path changes, and the interference wavelength also changes, resulting in a change in the color presented to the observer, thus creating a specific color-changing effect and enhancing the easy-to-identify and difficult-to-counterfeit characteristics of the optical anti-counterfeiting element.

[0074] Of course, coating 4 can be a multilayer coating, and the multilayer coating can be at least two of the following: an absorption layer, a dielectric layer, and a reflective layer. In this case, the structure of the multilayer coating is a metal / dielectric multilayer film structure, usually a three-layer or five-layer structure.

[0075] Specifically, the structure of a multilayer coating may include at least one of the following:

[0076] a. A first reflective layer formed on the optical microstructure 3, a first dielectric layer formed on the first reflective layer, and a first absorption layer formed on the first dielectric layer. The order of the above three layers can be reversed.

[0077] b. A second absorption layer formed on the optical microstructure 3, a second dielectric layer formed on the second absorption layer, and a third absorption layer formed on the second dielectric layer. The order of the above three layers can be reversed.

[0078] c. A fourth absorption layer formed on the optical microstructure 3, a third dielectric layer formed on the fourth absorption layer, a second reflective layer formed on the third dielectric layer, a fourth dielectric layer formed on the second reflective layer, and a fifth absorption layer formed on the fourth dielectric layer;

[0079] d. A sixth absorption layer formed on the optical microstructure 3, a fourth dielectric layer formed on the sixth absorption layer, a seventh absorption layer formed on the fourth dielectric layer, a fifth dielectric layer formed on the seventh absorption layer, and an eighth absorption layer formed on the fifth dielectric layer.

[0080] In general, a three-layer multi-coating structure consists of a reflective layer, a dielectric layer, and an absorption layer, or an absorption layer, a dielectric layer, and an absorption layer. The former allows for observation of the light-changing effect from only one side, while the latter allows observation from both sides. A five-layer multi-coating structure consists of an absorption layer, a dielectric layer, a reflective layer, a dielectric layer, and an absorption layer, or an absorption layer, a dielectric layer, an absorption layer, a dielectric layer, and an absorption layer. The light-changing effect observed on both sides can be designed to be the same or different, depending on the parameters and materials of each reflective, dielectric, and absorption layer. This increases the uniqueness of optical anti-counterfeiting elements, making them more adaptable to a wider range of anti-counterfeiting applications and enhancing their anti-counterfeiting capabilities.

[0081] It should be noted that the aforementioned reflective layers are generally thick metal layers, typically greater than 20 nanometers, and the materials used can be at least one of gold, silver, copper, aluminum, iron, tin, zinc, nickel, and chromium. The aforementioned dielectric layers can be single-layer dielectric layers, and the dielectric materials used can be selected from inorganic coating materials such as MgF2, SiO2, Al2O3, MgO, PMMA, HfO2, TiO2, ZnS, and ZnO, as well as polymers. Their thickness is determined by the desired optical effect and the refractive index of the material, generally greater than 10 nanometers and less than 10 micrometers; preferably, the thickness is greater than 50 nanometers and less than 0.8 micrometers. Of course, the aforementioned dielectric layers can also be multilayer dielectric layers, and the dielectric materials used can be selected from common inorganic coating materials such as MgF2, SiO2, Al2O3, MgO, PMMA, HfO2, TiO2, ZnS, and ZnO. Furthermore, multilayer dielectric layers typically employ a high- and low-refractive-index λ / 4 film system design. The materials used in each of the above-mentioned absorption layers can be at least one of metals or metal compounds such as gold, silver, copper, aluminum, iron, tin, zinc, nickel, and chromium. The thickness is usually no more than 20 nanometers, preferably greater than 5 nanometers and less than 10 nanometers. Its function is to partially reflect, partially transmit and partially absorb the illumination beam.

[0082] It should be understood that the structure of the multilayer coating according to the present invention is not limited to the structure described above. For example, a two-layer structure (i.e., a reflective layer and a dielectric layer) or a four-layer structure (i.e., an absorption layer, a dielectric layer, a reflective layer, and a dielectric layer) is also desirable.

[0083] Of course, coating 4 can be a multilayer coating, and the multilayer coating can be composed of multiple dielectric layer groups. That is, the multilayer coating is composed of different dielectric layers with high and low refractive indices. This structure usually adopts a λ / 4 film system design. Moreover, the material used for each dielectric layer can be at least one of the inorganic coating materials such as MgF2, SiO2, Al2O3, MgO, HfO2, TiO2, ZnS, and ZnO. Of course, it can also be a polymer, or a combination of inorganic coating materials and polymers.

[0084] Optionally, coating 4 has a perforated pattern. Single-layer or multi-layer coatings can be further perforated using processes such as printing with an alkaline wash, printing with a water wash, or a precision perforation process. The perforated pattern allows for more precise reflection, transmission, or absorption of incident light.

[0085] The coating 4 can be formed by physical deposition, chemical deposition, or a combination of both. Examples include, but are not limited to, thermal evaporation, magnetron sputtering, MOCVD (metal-organic chemical vapor deposition), and molecular beam epitaxy. The coating 4 is formed on the optical microstructure 3 in a conformal covering form, facilitating fabrication.

[0086] Specifically, the cross-sectional shape of the optical microstructure unit includes at least one of sinusoidal, trapezoidal, and rectangular shapes. By designing the cross-sectional shape of the optical microstructure unit, the ratio of reflected light to transmitted light can be adjusted according to actual needs, meeting the requirements of production and processing, enhancing the easily identifiable and difficult-to-counterfeit characteristics of the optical anti-counterfeiting element, and improving the anti-counterfeiting effect. Furthermore, while ensuring the achievement of anti-counterfeiting objectives, the manufacturing difficulty is reduced, facilitating the mass production of optical anti-counterfeiting elements.

[0087] Optionally, the substrate 2 can be a polyvinyl chloride (PVC) board, a polyethylene terephthalate (PET) board, a polycarbonate (PC) board, a glass board, etc.

[0088] Optionally, at least one functional layer may be coated on the surface of the substrate 2, depending on the specific requirements of the product.

[0089] Optionally, the functional layer includes, but is not limited to, a release layer, a reinforcement layer, a protective layer, a magnetic layer, a fluorescent layer, and an infrared layer.

[0090] Optionally, at least one functional layer may be further applied to the upper surface of coating 4.

[0091] Example 1

[0092] like Figure 1 As shown, the optical microstructure 3 is a one-dimensional rectangular microstructure with a period of 2 micrometers and a depth of 0.5 micrometers. Specifically, in the cross-section formed along direction M in the upper surface region 201 of the substrate, the optical microstructure 3 exhibits a rectangular outline with a period of 2 micrometers and a height difference of 0.5 micrometers between its highest and lowest points. At this point, the optical microstructure 3 contains 500 rectangular optical microstructure units per millimeter span in the cross-section formed along direction M. Furthermore, in the upper surface region 201 of the substrate, in the direction perpendicular to direction M (in... Figure 1 The optical microstructure 3 extends infinitely along a direction perpendicular to the paper (the center direction is shown in the image). The coating 4 is a 60-nanometer-thick Al coating with an optical density of 3.0. In this embodiment, when sunlight illuminates the optical microstructure 3 at an incident angle, it appears green in both the reflected and transmitted light directions, a magenta complementary color to green near the reflected light, and diffracted light colors in the +1st or -1st order diffraction directions. Through the deep design of the optical microstructure 3, an optical anti-counterfeiting element with unique color characteristics and easy mass production and application is achieved.

[0093] Example 2

[0094] In this embodiment, the optical microstructure units are randomly or pseudo-randomly distributed.

[0095] For ease of description, we define an xyz spatial coordinate system, where the xoy plane is parallel to the plane containing the optical anti-counterfeiting element, and the z-direction is perpendicular to this plane. For example... Figure 5 As shown, the optical microstructure 3 can be located in the xoy plane (or a plane parallel to the xoy plane), and its feature size in the x-axis and y-axis directions can be, for example, greater than 0.3 micrometers and less than 6 micrometers, preferably greater than 0.6 micrometers and less than 3 micrometers, and the optical microstructure units can be randomly or pseudo-randomly distributed. The protruding portions in the optical microstructure 3 can account for more than 20% and less than 80% of the total area of ​​the optical microstructure 3, preferably more than 35% and less than 65% of the total area of ​​the optical microstructure 3.

[0096] For ease of description, in the following figures, I represents incident light, R represents reflected light, T represents transmitted light, S represents reflected light, D1 represents +1st order diffraction light, and D2 represents -1st order diffraction light.

[0097] like Figures 6 to 8 As shown, the cross-sectional shape of the optical microstructure unit can be sinusoidal, trapezoidal, or rectangular. Those skilled in the art will understand that the cross-sectional shape of the optical microstructure unit can also be other shapes.

[0098] like Figure 6 As shown, the depth of the optical microstructure 3 can satisfy the following condition: when natural light (white light) irradiates the optical microstructure 3 at an incident angle α, the light with wavelength λ (or a wavelength range) is constructively interfered in both the reflected light direction and the transmitted light direction, so that the optical anti-counterfeiting element appears as the first color when observed in both the reflected light direction and the transmitted light direction, and as the second color when observed in the scattered light direction.

[0099] Example 3

[0100] The difference from Example 2 is that the optical microstructure 3 is different.

[0101] In this embodiment, the optical microstructure units are randomly or pseudo-randomly distributed in the second direction.

[0102] In this embodiment, the x-axis direction is the first direction, and the y-axis direction is the second direction.

[0103] like Figure 9As shown, the optical microstructure 3 can be located in the xoy plane (or a plane parallel to the xoy plane), and its feature size in the x-axis direction can be greater than 6 micrometers, preferably greater than 10 micrometers. Therefore, the optical microstructure 3 has no diffraction effect in this direction. The feature size of the optical microstructure 3 in the y-axis direction can be greater than 0.3 micrometers and less than 6 micrometers, preferably greater than 0.6 micrometers and less than 3 micrometers, and the pattern can be randomly or pseudo-randomly distributed. The protruding portion in the optical microstructure 3 can account for more than 20% and less than 80% of the total area of ​​the optical microstructure 3, preferably more than 35% and less than 65% of the total area of ​​the optical microstructure 3.

[0104] like Figure 10 As shown, the cross-sectional shape of the optical microstructure unit in the yoz plane can be sinusoidal. However, those skilled in the art will understand that the cross-sectional shape of the optical microstructure unit can be trapezoidal, rectangular, or other shapes.

[0105] The depth of the optical microstructure 3 can satisfy the following condition: when natural light (white light) illuminates the optical microstructure 3 at an incident angle α, after the light beam passes through the optical microstructure 3, the light with wavelength λ (or a wavelength range) exhibits constructive interference in both the reflected and transmitted light directions, thus allowing the first color to be observed in both directions. Furthermore, if the light beam lies within the yoz plane (or a plane parallel to the yoz plane), a second color is observed in the direction of scattered light within the yoz plane (or a plane parallel to the yoz plane). By designing the depth of the optical microstructure 3, an optical anti-counterfeiting element with unique color characteristics and easy mass production and application can be realized.

[0106] Example 4

[0107] The difference from Example 2 is that the optical microstructure 3 is different.

[0108] In this embodiment, the optical microstructure units are periodically distributed in the first direction and randomly or pseudo-randomly distributed in the second direction.

[0109] In this embodiment, the x-axis direction is the first direction, and the y-axis direction is the second direction.

[0110] like Figure 11As shown, the optical microstructure 3 can be located in the xoy plane (or a plane parallel to the xoy plane). Its feature size in the y-axis direction can be, for example, greater than 0.3 micrometers and less than 6 micrometers, preferably greater than 0.6 micrometers and less than 3 micrometers. The pattern can be randomly or pseudo-randomly distributed. Its feature size in the x-axis direction can be, for example, greater than 0.3 micrometers and less than 6 micrometers, preferably greater than 0.6 micrometers and less than 3 micrometers. The pattern can be, for example, a periodic structure. The protruding portion in the optical microstructure 3 can occupy more than 20% and less than 80% of the total area of ​​the optical microstructure 3. Preferably, the protruding portion in the optical microstructure 3 can occupy more than 35% and less than 65% of the total area of ​​the optical microstructure 3.

[0111] Figure 12 This is a schematic cross-sectional view of optical microstructure 3 in the yoz plane (or a plane parallel to the yoz plane). Figure 13 This is a schematic cross-sectional view of optical microstructure 3 in the xoz plane (or a plane parallel to the xoz plane). The cross-sectional shape of the optical microstructure unit can be sinusoidal, trapezoidal, rectangular, or other shapes.

[0112] The depth of the optical microstructure 3 can satisfy the following condition: when natural light (white light) illuminates the optical microstructure 3 at an incident angle α, after the light beam passes through the optical microstructure 3, the light with wavelength λ (or a wavelength range) exhibits constructive interference in both the reflected and transmitted light directions, thus allowing the first color to be observed in both directions. Furthermore, if the light beam is in the yoz plane (or a plane parallel to the yoz plane), a second color is observed in the scattered light direction within 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 +1 or -1 order diffracted light color of the grating is observed to change with the observation angle in the diffraction direction. By designing the depth of the optical microstructure 3, an optical anti-counterfeiting element with unique color characteristics and easy mass production and application can be realized.

[0113] Example 5

[0114] like Figure 14 As shown, the optical anti-counterfeiting element includes a secondary optical microstructure 5 that is basically shaped and covers the optical microstructure 3. By shaped and covering the optical microstructure 3 with the secondary optical microstructure 5, the unique color characteristics of the optical anti-counterfeiting element are preserved, while providing other anti-counterfeiting features. This makes the optical anti-counterfeiting element suitable for more anti-counterfeiting application scenarios and enhances its characteristics of being easy to identify and difficult to counterfeit.

[0115] Optionally, the secondary optical microstructure 5 includes at least one of holographic diffraction microstructure and subwavelength microstructure. By designing the secondary optical microstructure 5, patterns such as text and markings required for anti-counterfeiting can be realized, enhancing anti-counterfeiting features and facilitating the application of optical anti-counterfeiting elements in more demanding anti-counterfeiting scenarios.

[0116] Optionally, the groove shape of the holographic diffraction microstructure includes at least one of the following: arc-shaped, sinusoidal, rectangular, and sawtooth-shaped. The holographic diffraction microstructure can provide diffraction holographic features. By designing different groove shapes, different diffraction holographic feature requirements can be met, enhancing the uniqueness of optical anti-counterfeiting elements and improving the level of ease of identification and difficulty in counterfeiting of optical anti-counterfeiting elements.

[0117] Optionally, the feature size of the holographic diffraction microstructure in its two-dimensional plane is greater than 0.5 micrometers and less than 5 micrometers, and the groove depth is greater than 50 nanometers. By controlling the feature size of the holographic diffraction microstructure in its two-dimensional plane to be greater than 0.5 micrometers, excessive processing difficulty is avoided. By controlling the feature size to be less than 5 micrometers, the conditions for holographic diffraction are guaranteed. At the same time, this is coordinated with the feature size of the optical microstructure 3 to ensure the anti-counterfeiting effect of the optical anti-counterfeiting element. Controlling the groove depth to be greater than 50 nanometers ensures the occurrence of holographic diffraction and avoids unclear anti-counterfeiting features.

[0118] Optionally, the subwavelength microstructure is a one-dimensional grating or a two-dimensional grating, and the groove shape of the subwavelength microstructure is at least one of arc-shaped, sinusoidal, rectangular, and sawtooth shapes. Of course, the subwavelength microstructure can be a two-dimensional grating, and the groove shape can be sinusoidal, rectangular, sawtooth, etc., and the grating distribution of the two-dimensional grating can be an orthogonal structure, a honeycomb structure, a two-dimensional Bravais lattice structure, a random structure, etc.

[0119] It should be noted that the structure of the secondary optical microstructure 5 is not limited to the structure described above, and combinations of these structures can be used in practical applications.

[0120] Specifically, the subwavelength microstructure has a feature size greater than 0.05 micrometers and less than 0.5 micrometers in its two-dimensional plane, and a groove depth greater than 10 nanometers. By controlling the feature size of the subwavelength microstructure to be greater than 0.05 micrometers in its two-dimensional plane, excessive processing difficulty is avoided. By controlling the feature size to be less than 0.5 micrometers, the original color characteristics of the optical anti-counterfeiting element are ensured to match the feature size of the optical microstructure 3, thus guaranteeing the anti-counterfeiting effect of the optical anti-counterfeiting element. The groove depth is controlled within the range of greater than 10 nanometers to avoid unclear anti-counterfeiting features.

[0121] Preferably, the secondary optical microstructure 5 has a feature size greater than 200 nanometers and less than 400 nanometers in its two-dimensional plane.

[0122] Preferably, the groove depth of the secondary optical microstructure 5 is greater than 50 nanometers and less than 300 nanometers.

[0123] It should be noted that when the feature size of the secondary optical microstructure 5 in one direction meets the requirements, the feature size in the other direction can be unrestricted.

[0124] There is a certain matching relationship between the period and the groove depth of the secondary optical microstructure 5. This matching relationship can be represented by the aspect ratio (i.e., the ratio of the groove depth to the period). It is designed and calculated based on the specific reproduction effect through strict coupled wave theory. The aspect ratio is usually greater than 0.3 and less than 2. Preferably, the aspect ratio is greater than 0.4 and less than 1.

[0125] The aspect ratio (i.e., the ratio of grating peak width to period) of the secondary optical microstructure 5 is also an important parameter affecting the optical effect. It mainly affects the color, brightness and contrast of the optical anti-counterfeiting element. It is usually required that the aspect ratio be greater than 0.3 and less than 0.7. Preferably, the aspect ratio is greater than 0.4 and less than 0.6.

[0126] It should be noted that when the secondary optical microstructure 5 is selected as a subwavelength microstructure, the optical characteristics obtained by its combination with the coating 4, including the parameter matching relationship, specific principle, and optical characteristics, are specifically defined by Chinese Patent CN102514443, and the contents of its specification are incorporated into this invention. In summary, when the secondary optical microstructure 5 is selected as a subwavelength microstructure, its combination with the coating 4 forms a color-changing feature that changes with the viewing angle, which is different from the color features provided by the coating 4 with a flat or smooth surface, thus forming a unique color-changing feature that changes with the viewing angle.

[0127] Preferably, the secondary optical microstructure 5 and the coating 4 can also achieve polarization characteristics in or near the direction of reflected light by working together.

[0128] To illustrate with a concrete example, consider a secondary optical microstructure 5 within an optical microstructure 3. The secondary optical microstructure 5 is essentially identical to the optical microstructure 3. The secondary optical microstructure 5 is selected as a sinusoidal groove with a period of 300 nm and a depth of 100 nm, arranged in an orthogonal two-dimensional grid. The coating 4 is selected to sequentially contain Al (40 nm), SiO2 (370 nm), and Cr (5 nm) (on a flat surface, this multilayer coating exhibits a golden-yellow color when viewed from the front and a green color when viewed from an angle). Thus, the secondary optical microstructure 5 and the coating 4 together create a red-to-yellow color characteristic. By designing the depth of the optical microstructure 3, an optical anti-counterfeiting element with unique color characteristics and easy mass production and application can be achieved.

[0129] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects:

[0130] 1. By controlling the type and parameters of the optical microstructure 3, the density of the optical microstructure unit, the type and parameters of the coating 4 on the surface of the optical microstructure 3, and the optical density of the coating 4, the same color characteristics in the direction of reflected light and transmitted light, as well as another complementary color presented in at least one direction near the direction of reflected light, can be achieved.

[0131] 2. By setting up an optical microstructure 3 with a structure and features completely different from existing technologies, an optical anti-counterfeiting element with more unique optical anti-counterfeiting features and easy mass production application is realized, which is easy to identify and difficult to counterfeit.

[0132] Obviously, the embodiments described above are merely some, not all, embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0133] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0134] It should be noted that the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in sequences other than those illustrated or described herein.

[0135] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An optical anti-counterfeiting element, characterized in that, The substrate (2) includes a substrate (2) with a portion of at least one surface having an optical microstructure (3), the optical microstructure (3) having optical microstructure units, and at least 200 optical microstructure units per millimeter span within a cross-section of at least a local region of the optical microstructure (3), wherein the depth of at least a portion of the optical microstructure (3) satisfies the following: when a light beam irradiates the optical microstructure (3) at an incident angle, light of a wavelength or wavelength range in the light beam is constructively interfered in both the reflected light direction and the transmitted light direction, and exhibits a first color in both the reflected light direction and the transmitted light direction, and exhibits a second color in at least one direction near the reflected light, wherein the first color and the second color are complementary colors.

2. The optical anti-counterfeiting element according to claim 1, characterized in that, At least a portion of the optical microstructure units are randomly or pseudo-randomly distributed, the feature size of the optical microstructure units is greater than 0.3 micrometers and less than 6 micrometers, and the depth of the optical microstructure (3) satisfies that when the light beam irradiates the optical microstructure (3) at an incident angle, at least a portion of the optical microstructure (3) exhibits the second color in the direction of scattered light.

3. The optical anti-counterfeiting element according to claim 1, characterized in that, At least a portion of the optical microstructure units are randomly or pseudo-randomly distributed in the second direction. The characteristic size of the optical microstructure units in the second direction is greater than 0.3 micrometers and less than 6 micrometers, and the characteristic size in the first direction is greater than 6 micrometers. The depth of the optical microstructure (3) satisfies the following: when the light beam irradiates the optical microstructure (3) at an incident angle, if the light beam is in a first plane that is perpendicular to the plane where the substrate (2) is located and includes the second direction, then at least a portion of the optical microstructure (3) will present the second color in the direction of scattered light in the first plane.

4. The optical anti-counterfeiting element according to claim 1, characterized in that, At least a portion of the optical microstructure units are periodically distributed in a first direction and randomly or pseudo-randomly distributed in a second direction. The characteristic size of the optical microstructure units in the first direction is greater than 0.3 micrometers and less than 6 micrometers, and the characteristic size in the second direction is greater than 0.3 micrometers and less than 6 micrometers. The depth of the optical microstructure (3) satisfies the following: when the light beam irradiates the optical microstructure (3) at an incident angle, if the light beam is in a first plane that is perpendicular to the plane where the substrate (2) is located and includes the second direction, then at least a portion of the optical microstructure (3) presents the second color in the direction of scattered light in the first plane; if the light beam is in a second plane that is perpendicular to the plane where the substrate (2) is located and includes the first direction, then at least a portion of the optical microstructure (3) presents a +1 or -1 order diffraction color that varies with the angle in the direction of diffraction light in the second plane.

5. The optical anti-counterfeiting element according to claim 1, characterized in that, The optical anti-counterfeiting element further includes a coating (4), which is disposed on the side surface of the optical microstructure (3) away from the substrate (2).

6. The optical anti-counterfeiting element according to claim 5, characterized in that, The optical density of the coating (4) is greater than 1.

7. The optical anti-counterfeiting element according to claim 5, characterized in that, The coating (4) is a single-layer coating, and the single-layer coating includes at least one of a metal reflective layer, a semiconductor material layer, and a dielectric layer.

8. The optical anti-counterfeiting element according to claim 5, characterized in that, The coating (4) is a multilayer coating and the multilayer coating forms a Fabry-Poisson resonant cavity.

9. The optical anti-counterfeiting element according to claim 8, characterized in that, The coating (4) is a multilayer coating, which includes at least two of an absorption layer, a dielectric layer, and a reflective layer; or The multilayer coating comprises multiple dielectric layer groups.

10. The optical anti-counterfeiting element according to claim 5, characterized in that, The coating (4) has a hollowed-out pattern.

11. The optical anti-counterfeiting element according to any one of claims 1 to 10, characterized in that, The cross-sectional shape of the optical microstructure unit includes at least one of sinusoidal, trapezoidal, and rectangular shapes.

12. The optical anti-counterfeiting element according to any one of claims 1 to 10, characterized in that, The optical anti-counterfeiting element includes a secondary optical microstructure (5) that is substantially isomorphic to the optical microstructure (3).

13. The optical anti-counterfeiting element according to claim 12, characterized in that, The secondary optical microstructure (5) includes at least one of holographic diffraction microstructure and subwavelength microstructure.

14. The optical anti-counterfeiting element according to claim 13, characterized in that, The groove shape of the holographic diffraction microstructure includes at least one of the following: arc-shaped, sinusoidal, rectangular, and sawtooth-shaped.

15. The optical anti-counterfeiting element according to claim 13, characterized in that, The holographic diffraction microstructure has a feature size greater than 0.5 micrometers and less than 5 micrometers in the two-dimensional plane, and a groove depth greater than 50 nanometers.

16. The optical anti-counterfeiting element according to claim 13, characterized in that, The subwavelength microstructure is a one-dimensional grating or a two-dimensional grating, and the groove shape of the subwavelength microstructure is at least one of arc shape, sinusoidal shape, rectangular shape, and sawtooth shape.

17. The optical anti-counterfeiting element according to claim 13, characterized in that, The subwavelength microstructure has a feature size greater than 0.05 micrometers and less than 0.5 micrometers in the two-dimensional plane, and a groove depth greater than 10 nanometers.

18. An anti-counterfeiting product, characterized in that, The anti-counterfeiting product includes an optical anti-counterfeiting element according to any one of claims 1 to 17.

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