LIQUID CRYSTAL OPTICAL DEVICES BASED ON META SURFACE with POLARIZING DIRECTION AND WAVELENGTH selective type

Abstract

The present invention relates to a liquid crystal device based on a polarization direction and wavelength-selective metasurface, comprising: a liquid crystal layer (150) that changes the polarization direction of an incident beam according to the strength of an electric field; and a metasurface layer (100) that imparts a metasurface effect to an incident beam passing through the liquid crystal layer (150) and imparts different first and second metasurface effects to incident beams of first and second polarizations that are vertical and horizontal polarizations of a preset reference line, and may further include one of a front alignment layer (135), a front electrode layer (125), and a light source filter (215) of a light source (210) with different active portions.

Description

Technology Field

[0001] The present invention relates to a liquid crystal device based on a metasurface that is selective for the polarization direction and wavelength of light. Background Technology

[0002] Various encryption technologies are being developed to prevent forgery or alteration. However, there may be security images exposed in specific environments due to these technologies. While there are technologies that integrate security images with metasurface technology, generating such metasurfaces presents many challenges. During the fabrication stage, the metasurface structure must be custom-designed to fit the specific image, which is time-consuming and costly. Furthermore, there is a disadvantage in that the optical properties of the already fabricated metasurface cannot be adjusted. The problem to be solved

[0003] The present invention provides a liquid crystal device based on a metasurface that is selective for the polarization direction and wavelength of light. means of solving the problem

[0004] A liquid crystal element based on a polarization direction and wavelength-selective metasurface according to one embodiment of the present invention comprises: a liquid crystal layer (150) that changes the polarization direction of an incident beam according to the strength of an electric field; a metasurface layer (100) that imparts a metasurface effect to an incident beam passing through the liquid crystal layer (150) and imparts different first and second metasurface effects to incident beams of first and second polarizations that are vertical and horizontal polarizations of a preset reference line; and a front alignment layer (135) disposed on the front surface of the liquid crystal layer (150). The front alignment layer (135) may have an active alignment portion (231) that causes liquid crystal molecules of the liquid crystal layer (150) to be aligned in a specific position and direction, and an inactive alignment portion (233) that causes the liquid crystal molecules to be unaligned.

[0005] A liquid crystal element based on a polarization direction and wavelength selectable metasurface according to another embodiment of the present invention comprises: a liquid crystal layer (150) that changes the polarization direction of an incident beam according to the strength of an electric field; a metasurface layer (100) that imparts a metasurface effect to an incident beam passing through the liquid crystal layer (150) and imparts different first and second metasurface effects to first and second polarized incident beams that are polarized perpendicular and horizontally to a preset reference line; and a front electrode layer (125) that causes the electric field to be generated, wherein the front electrode layer (125) may have an active electrode portion (221) to which voltage is applied and an inactive electrode portion (223) to which voltage is not applied.

[0006] A liquid crystal element based on a polarization direction and wavelength-selective metasurface according to another embodiment of the present invention comprises: a liquid crystal layer (150) that changes the polarization direction of an incident beam according to the strength of an electric field; a metasurface layer (100) that imparts a metasurface effect to an incident beam passing through the liquid crystal layer (150) and imparts different first and second metasurface effects to first and second polarized incident beams that are polarized perpendicular and horizontally with respect to a preset reference line; and a light source (210) that irradiates light onto the metasurface layer (100). The light source (210) may have an inactive polarization part (218) that passes all light and an active polarization part (217) that passes only the first polarized incident beam.

[0007] In addition, at least one of the first and second metasurface effects may vary depending on the wavelength of the incident polarized beam.

[0008] In addition, the above meta surface layer (100) may be provided in multiple numbers.

[0009] In addition, the intensity of the first emission beam according to the first metasurface effect may be either greater or smaller than the intensity of the second emission beam according to the second metasurface effect.

[0010] In addition, the active and inactive orientation portions may be partitioned by at least one of physical rubbing and ultraviolet irradiation. Effects of the invention

[0011] The liquid crystal device based on a metasurface with selective polarization direction and wavelength according to the present invention utilizes a fabricated metasurface with known optical properties to enable various applications such as security images and metasurface-based optical devices, thereby reducing time and costs. Brief explanation of the drawing

[0012] FIG. 1 is a cross-sectional view of an electric liquid crystal optical element according to one embodiment of the present invention. FIGS. 2 and FIGS. 3 are cross-sectional views of an electric liquid crystal optical element according to another embodiment of the present invention, with and without power supply. FIGS. 4 to 6 illustrate various embodiments in which a metasurface effect is imparted according to a polarized beam. FIGS. 7 and 8 illustrate various embodiments in which a metasurface effect is imparted to a polarizing beam depending on whether power is supplied to the liquid crystal layer. FIGS. 9 to 13 illustrate various embodiments in which a metasurface effect according to the present invention occurs in a required part. FIG. 14 illustrates various applications in which the present invention can be implemented. FIG. 15 illustrates an electro-liquid crystal optical device having a plurality of meta-surface characteristics. Figure 16 illustrates the security image exposure state according to the wavelength and the presence or absence of voltage in the liquid crystal layer. Specific details for implementing the invention

[0013] The present invention will be described in more detail below with reference to the drawings.

[0014] Terms such as "first," "second," etc., may be used to describe various components, but said components should not be limited by said terms. These terms are used solely for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be named the second component, and similarly, the second component may be named the first component. The term "and / or" includes a combination of multiple related described items or any of the multiple related described items. "Or" may be interpreted as a logical exclusive combination in the context, but generally, unless there is a direct description such as "otherwise" or "logical exclusive combination," it is interpreted as having the same meaning as "and / or," that is, a logical disjunction.

[0015] When it is stated that one component is "connected" or "connected" to another component, it should be understood that while it may be directly connected or connected to that other component, there may also be other components in between. Conversely, when it is stated that one component is "directly connected" or "directly connected" to another component, it should be understood that there are no other components in between. Furthermore, the fact that a first component and a second component on a network are connected or connected implies that data can be exchanged between the first component and the second component via wired or wireless means.

[0016] Furthermore, the suffixes "module" and "part" for components used in the following description are assigned solely for the ease of drafting this specification and do not inherently confer any particularly significant meaning or role. Accordingly, the terms "module" and "part" may be used interchangeably.

[0017] When implemented in actual applications, these components may be configured such that two or more components are combined into a single component or a single component is subdivided into two or more components as needed. Identical or similar components throughout the drawings are assigned the same reference numerals, and detailed descriptions of components having the same reference numeral may be omitted and replaced by the description of the aforementioned components.

[0018] Furthermore, the present invention encompasses all possible combinations of the embodiments set forth in this specification. Various embodiments of the present invention are different but not mutually exclusive. One embodiment of a specific shape, structure, function, and characteristic described in this specification may be implemented in other embodiments. For example, the components mentioned in the first and second embodiments may perform all the functions of the first and second embodiments.

[0019] FIG. 1 is a cross-sectional view of an electro-liquid crystal optical element according to one embodiment of the present invention. FIG. 2 and FIG. 3 are cross-sectional views of an electro-liquid crystal optical element according to another embodiment of the present invention, with and without power supply.

[0020] Referring to FIGS. 1 and 2, a liquid crystal device based on a metasurface that is selective for the polarization direction and wavelength of light according to the present invention (used interchangeably with 'electric liquid crystal optical device' throughout the specification) may include a liquid crystal layer (150) and a metasurface layer (100).

[0021] The electric liquid crystal optical element according to the present invention can utilize the liquid crystal operating principle of a conventional LCD device.

[0022] A liquid crystal device based on a polarization direction and wavelength-selective metasurface can control whether plasmons are generated on the metasurface by adjusting the polarization direction of an incident beam passing through the liquid crystal layer.

[0023] The liquid crystal layer (150) can change the polarization direction of the incident beam according to the strength of the electric field. The liquid crystal layer (150) can change the alignment method of the liquid crystal molecules according to the voltage applied to the liquid crystal molecules distributed inside. The amount of light can be controlled according to the direction of the liquid crystal molecules. This can be achieved by changing the polarization direction of the incident beam.

[0024] In this embodiment, FIGS. 1 to 3 illustrate a TN Mode (TN, Twisted Nematic), but are not limited thereto, and an IPS (In-Plane Switching) Mode, VA (Vertical Alignment) Mode, FFS Mode (FFS, Fringe Field Switch), etc. may be applied.

[0025] In order for this TN Mode to be implemented, in a normal state (no voltage applied), the liquid crystal molecules of the liquid crystal layer (150) are arranged horizontally, and the liquid crystal molecules of the upper and lower layers may be twisted 90 degrees.

[0026] Referring to FIG. 1, the electro-liquid crystal optical element may further include a front alignment layer (135). The twisting of liquid crystal molecules can be achieved by the front alignment layer (135) and the meta-surface layer (100).

[0027] An alignment layer refers to a layer that orients liquid crystal molecules so that they are aligned in a specific position and / or direction.

[0028] The front alignment layer (135) may utilize an existing alignment layer. The meta surface layer (100) may function as an alignment layer. This will be described later.

[0029] Referring to FIG. 2, the electro-liquid crystal optical element may further include a base alignment layer (130). A conventional alignment layer may be used for the base alignment layer (130). The twisting of liquid crystal molecules may be achieved by the front alignment layer (135) and the base alignment layer (130). The meta-surface layer (100) may have a coating layer (105) for protecting or supporting the meta-surface. When the base alignment layer (130) is disposed on the meta-surface layer (100), it is preferable to have the coating layer (105) provided.

[0030] Referring to FIG. 1, the orientation direction formed in the front orientation film (135) is formed parallel to the ground, and the groove formed in the meta surface layer (100) can be formed perpendicular to the ground. The direction of the groove in the meta surface layer (100) can be freely determined so that a desired meta effect occurs in the meta surface layer (100).

[0031] Referring to FIGS. 2 and 3, the orientation direction formed on the front orientation film (135) may be formed perpendicular to the ground, and the orientation direction formed on the base orientation film (130) may be formed parallel to the ground.

[0032] The following description is based on FIG. 2 and FIG. 3, which are equipped with a base alignment layer (130).

[0033] Referring to FIG. 3, when a power source (V) is applied to both ends of the liquid crystal layer (150) to form an electric field, the liquid crystal molecules can be arranged in a vertical direction. To this end, the electric liquid crystal optical element may further include a front electrode layer (125) and a base electrode layer (120).

[0034] It is preferable that the electrodes constituting the front electrode layer (125) and the base electrode layer (120) be transparent electrodes such as ITO.

[0035] The front electrode layer (125) and the base electrode layer (120) can be arranged in a grid pattern like a matrix to form pixel electrodes. In this case, the arrangement of liquid crystal molecules at specific locations can be changed.

[0036] The front electrode layer (125) and the base electrode layer (120) may be surface electrodes that cover the entire liquid crystal layer (150). This may be applied to the modulation of the front alignment layer (135) described later, or to an embodiment of a light source filter (215) placed on a light source (210).

[0037] The base electrode layer (120) is provided with a surface electrode that covers the entire liquid crystal layer (150), and the front electrode layer (125) can be implemented with an active electrode portion (221) to which voltage is applied and an inactive electrode portion (223) to which voltage is not applied. This is not limited thereto, and the configuration of the surface electrode and some electrodes of the front electrode layer (125) and the base electrode layer (120) may be implemented by swapping them with each other, or both the front electrode layer (125) and the base electrode layer (120) may be composed of some electrodes. A detailed explanation thereof will be provided later.

[0038] The electric liquid crystal optical element may further include a front substrate (115) and / or a base substrate (110) that protects the frame and internal components.

[0039] FIG. 14 illustrates various applications in which the present invention can be implemented.

[0040] Referring to FIG. 14, a liquid crystal device based on a metasurface that selects the polarization direction and wavelength of light can be applied such as a front substrate (115) to display various specific shapes as in FIG. 14(a) depending on the polarization direction and / or wavelength, a Fresnel lens using a plurality of concentric hollow circles with variable focal lengths as in FIG. 14(b), or a grating with adjustable (variable) diffraction characteristics as in FIG. 14(c).

[0041] The front substrate (115) is preferably transparent, and the base substrate (110) may be transparent (when used as a lens) or opaque as needed.

[0042] The meta surface layer (100) can impart a meta surface effect to the transmitted beam passing through the liquid crystal layer (150).

[0043] The metasurface can be a plasmonic metasurface or a metasurface utilizing dielectric properties. The metasurface structure may be a pattern formed on a substrate in a one-dimensional or two-dimensional lattice structure using a dielectric material or a metal material. In this embodiment, if the metasurface is a pattern of a one-dimensional lattice structure, the present invention can be implemented without the aforementioned base electrode layer (120). The metasurface is not limited to this lattice structure, and any meta structure in which plasmon generation changes according to polarization may be possible.

[0044] In this embodiment, the metasurface provided by the metasurface layer (100) may be one that has already been manufactured and whose optical properties are known. In order to implement an image using a conventional metasurface, the image must be considered during the structural design stage. Such image-customized design makes it difficult to change the image after manufacturing, and requires significant time, cost, and labor costs because process conditions must be newly adjusted for each image. Since the present invention utilizes a pre-manufactured metasurface with predetermined optical properties, there is no need for a separate metasurface design, and its ease of use is expected to increase demand.

[0045] FIGS. 4 to 6 illustrate various embodiments in which a metasurface effect is imparted according to a polarized beam. This embodiment is described under the assumption that a beam is directly irradiated onto the metasurface (metasurface layer (100)).

[0046] Referring to FIGS. 4 through 6, the metasurface layer (100) can impart first and second metasurface effects different from each other to first and second polarized irradiation beams, which are vertically and horizontally polarized with respect to a preset reference line at a specific wavelength. In this embodiment, a reflected beam having different reflection or absorption characteristics depending on the polarization of the irradiation beam is illustrated. These metasurface effects may vary depending on the wavelength of the irradiation beam. The irradiation beam may refer to a beam that reaches the metasurface layer.

[0047] In this embodiment, the reference line set in advance may be one of the length direction of the one-dimensional grid of the meta surface layer (100), the length direction of the groove formed in the front alignment film (135), etc. Hereinafter, this embodiment will be described with reference to the length direction of the one-dimensional grid of the meta surface layer (100). The first and second polarization irradiation beams may be polarization beams perpendicular and horizontal to the length direction of the one-dimensional grid, or horizontal and vertical polarization beams.

[0048] Referring to FIG. 4, when an irradiation beam of the first wavelength is horizontally polarized, a first metasurface effect (brightness 1) as in FIG. 4(a) can be imparted and reflected.

[0049] Referring to FIG. 5, when an irradiation beam of the first wavelength is vertically polarized, a second metasurface effect (brightness 2) as in FIG. 5(a) can be imparted and reflected. In this embodiment, the brightness 2 of the reflected beam may be brighter than brightness 1 of FIG. 4.

[0050] Referring to FIG. 6, when an irradiation beam of the first wavelength is vertically polarized, a second metasurface effect (brightness 3) as in FIG. 6(a) can be imparted and reflected. In this embodiment, the brightness 3 of the reflected beam may be darker than brightness 1 of FIG. 4.

[0051] Although not illustrated, when the irradiation beam of the first wavelength is vertically polarized, the brightness of the reflected beam may be the same as brightness 1 in FIG. 4. In this case, it means that the metasurface effect does not change depending on the polarization direction. Or it may mean that the metasurface effect does not occur regardless of the polarization direction.

[0052] The metasurface layer (100) can have a wavelength-selective metasurface effect.

[0053] For example, the reflected beam of a vertically polarized irradiation beam at the first wavelength may be darker than the reflected beam of a horizontally polarized irradiation beam at the first wavelength.

[0054] The reflected beam of a vertically polarized irradiation beam at the second wavelength may be brighter than the reflected beam of a horizontally polarized irradiation beam at the second wavelength.

[0055] The brightness of the reflected beam of the vertically polarized irradiation beam at the third wavelength and the reflected beam of the horizontally polarized irradiation beam at the third wavelength can be the same.

[0056] FIGS. 7 and 8 illustrate various embodiments in which a metasurface effect is imparted to a polarizing beam depending on whether power is supplied to the liquid crystal layer. In the description of FIGS. 7 and 8, hatching indicates that no metasurface effect occurs, and the absence of hatching indicates that a metasurface effect occurs.

[0057] The metasurface layer (100) of FIGS. 7 and 8 may not impart a metasurface effect to a vertically polarized incident beam of a specific wavelength range. Hereinafter, it is assumed that a beam of the same wavelength range is incident.

[0058] Referring to FIG. 7, when no voltage is applied to the liquid crystal layer (150) (Fig. 7(a)), a horizontally polarized incident beam passes through the liquid crystal layer and can be changed into a vertically polarized beam (transmitted beam). In this case, a metasurface effect is not generated by the metasurface layer (100) of FIG. 7, which does not impart a metasurface effect to the vertically polarized beam (irradiated beam).

[0059] When a voltage is applied to the liquid crystal layer (150) (Fig. 7(b)), a horizontally polarized incident beam can pass through the liquid crystal layer without changing its polarization direction and reach the meta-surface layer (100). In this case, a meta-surface effect can be generated by the meta-surface layer (100) of Fig. 7, which imparts a meta-surface effect to the horizontally polarized beam (irradiation beam).

[0060] FIG. 8 illustrates the incident vertical polarization beam, unlike FIG. 7. Accordingly, the opposite effect to FIG. 7 occurs. That is, when no voltage is applied to the liquid crystal layer (150), a horizontal polarization beam (transmitted beam) reaches the meta surface layer (100) and a meta surface effect occurs, and when voltage is applied to the liquid crystal layer (150), a vertical polarization beam (transmitted beam) reaches the meta surface layer (100) and a meta surface effect does not occur.

[0061] FIGS. 9 to 13 illustrate various embodiments in which a metasurface effect according to the present invention occurs in a required portion. Each embodiment may be implemented alone, but is not limited thereto, and the present invention may be implemented in combination of each embodiment.

[0062] Referring to FIG. 9, the electric liquid crystal optical element may further include a light source (210) that irradiates light onto a metasurface layer (100).

[0063] The light source (210) may be equipped with a light source filter (215). The light source filter (215) may be equipped with an inactive polarizing section (218) that allows all light to pass through and an active polarizing section (217) that allows only the first polarized incident beam to pass through.

[0064] Among the beams emitted from the light source (210), only the first polarized beam that passes through the active polarization unit (217) may have a specific metasurface effect applied according to the wavelength and polarization direction.

[0065] Referring to FIGS. 10 and 11, the front alignment film (135) may have an active alignment portion (231) and an inactive alignment portion (233).

[0066] In a normal state (no electric field applied), the active alignment portion (231) can cause the first liquid crystal molecules in contact with its lower surface to be aligned in a specific position and direction. The active alignment portion (231) can cause the liquid crystal molecules in contact with its lower surface to be arranged in a twisted manner in three-dimensional space. The active alignment portion (231) can cause the liquid crystal molecules to be aligned in a TN structure. The active alignment portion (231) can be rubbed so that the rubbing orientation is perpendicular to the base alignment layer (130). The orientation (alignment direction) of the first liquid crystal molecules in contact with the active alignment portion (231) can be perpendicular to the orientation of the second liquid crystal molecules in contact with the base alignment layer (130). When no electric field is applied to the active alignment portion (231), the polarization directions of the incident beam incident on the liquid crystal layer (150) and the transmitted beam passing through the liquid crystal layer (150) can be perpendicular to each other. The active alignment portion (231) can maintain the function of the alignment film in the existing liquid crystal device.

[0067] Under normal conditions, the liquid crystal molecules below the inactive alignment portion (233) may be randomly dispersed or aligned in a specific direction. The inactive alignment portion (233) may be arranged such that the third liquid crystal molecules in contact with its lower portion are not perpendicular to the direction of the fourth liquid crystal molecules in contact with the base alignment layer (130), or the direction of the third liquid crystal molecules in contact with its lower portion may be randomly oriented. When the orientation of the third liquid crystal molecules and the fourth liquid crystal molecules is the same, a specific polarized beam may be transmitted through the liquid crystal layer (150) placed in the inactive alignment portion (233) without changing the polarization direction. When the third and fourth liquid crystal molecules are oriented at an angle that is not perpendicular, the polarization direction of the incident beam incident on the liquid crystal layer (150) and the transmitted beam may change to an angle that is not perpendicular. In this case, the metasurface effect may appear differently depending on the polarization direction of the transmitted beam irradiated on the metasurface layer (100). When the liquid crystal molecules placed in the inactive orientation section (233) are randomly dispersed, the incident beam is scattered or absorbed by the liquid crystal molecules, so that there is no transmitted beam reaching the metasurface layer (100) or the amount is small, and thus no metasurface effect occurs. Accordingly, since it is desirable for the inactive orientation section (233) to prevent the metasurface effect from occurring, it is desirable for the liquid crystal molecules below the inactive orientation section (233) to be randomly arranged or oriented in a specific direction so that the transmitted beam does not impart a metasurface effect.

[0068] In this embodiment, it is preferable that the irradiation beam (transmitted beam) polarized in the first polarization direction and irradiated onto the meta-surface layer (100) does not cause a meta-surface effect. Hereinafter, in this embodiment, the polarized irradiation beam in the first polarization direction is treated as not causing a meta-surface effect. Furthermore, the incident beam incident on the liquid crystal layer (150) is assumed to be in the first polarization direction and will be described.

[0069] As shown in FIG. 10, when voltage is applied to the liquid crystal layer (150), the liquid crystal molecules placed at the active alignment portion (231) can be twisted. The first polarized beam incident on the active alignment portion (231) can reach the metasurface layer (100) as a second polarized beam with a changed polarization direction. In this case, a metasurface effect according to the corresponding wavelength and second polarization direction may occur.

[0070] The first polarized beam passing through the inactive orientation section (233) does not pass through the liquid crystal layer (150) or reaches the meta-surface layer (100) without changing its polarization direction. In this case, no meta-surface effect occurs. Even if a meta-surface effect occurs, it is so minimal that it can be ignored.

[0071] As shown in FIG. 11, when a voltage is applied to the liquid crystal layer (150), the liquid crystal molecules positioned at the active alignment portion (231) and the inactive alignment portion (233) can be aligned in a vertical direction. In this case, no metasurface effect occurs. When the first polarized incident beam passes through the active alignment portion (231) and the inactive alignment portion (233), the polarization direction does not change. That is, the first polarized irradiation beam (transmitted beam) is irradiated onto the metasurface layer (100), and no metasurface effect occurs.

[0072] The active orientation portion (231) and the inactive orientation portion (233) can be partitioned by at least one of physical rubbing and ultraviolet irradiation.

[0073] Physical rubbing may refer to a method of aligning liquid crystals using physical means, such as rotating a roller on an alignment layer. The UV irradiation method may refer to a method of inducing the alignment of liquid crystal molecules by irradiating a light-responsive film with ultraviolet light.

[0074] Physical rubbing may be suitable during production, that is, when creating an image that is required semi-permanently. The ultraviolet irradiation method may be used when it is necessary to change the arrangement of the active orientation part (231) and the inactive orientation part (233) several times. However, it is not limited to this, and the ultraviolet irradiation method may be used in all cases.

[0075] Referring to FIGS. 12 and 13, the front electrode layer (125) may have an active electrode portion (221) to which voltage is applied and an inactive electrode portion (223) to which voltage is not applied.

[0076] When the electrode layer (125, 120) is implemented as a grid-type matrix electrode that implements pixels, there is less need to implement it as in this embodiment. In this embodiment, it can be implemented with a simple process like a surface electrode. In this case, time and cost can be reduced compared to the matrix method.

[0077] In this embodiment, the present invention can be implemented through a process in which a transparent electrode is applied to the active electrode portion (221) and a transparent electrode is not applied to the inactive electrode portion (223).

[0078] As shown in FIG. 12, when voltage is not applied to the liquid crystal layer (150), the first polarized incident beam of a specific wavelength range changes into a second polarized beam and reaches the metasurface layer (100). In this case, a metasurface effect may occur due to the second polarized beam of the corresponding wavelength.

[0079] As shown in FIG. 13, when a voltage is applied to the liquid crystal layer (150), the liquid crystal molecules placed on the active electrode portion (221) of the liquid crystal layer (150) are arranged vertically, causing the first polarized beam to reach the metasurface layer (100). In this case, a metasurface effect according to the first polarized beam may occur. The beam passing through the inactive electrode portion (223) may produce a metasurface effect according to the second polarized beam as shown in FIG. 12. In this way, different metasurface effects are produced depending on the region.

[0080] FIG. 15 illustrates an electro-liquid crystal optical device having multiple meta-surface characteristics. FIG. 15(a) shows the names of each meta-surface layer, FIG. 15(b) shows the wavelength of the incident light, and FIG. 15(c) shows that the meta-surface effect occurs in a specific region according to the wavelength range.

[0081] Referring to FIG. 15, a liquid crystal device based on a polarization direction and wavelength-selective metasurface may have first to 16 metasurface portions (M1 to M16). Each of the first to 16 metasurface layers may be a metasurface layer (100) described in FIG. 1 to 14 and may have a metasurface with known optical properties. Each optical property may be different from one another.

[0082] This embodiment is preferably implemented through a configuration in which the front alignment film (135) is divided into an active alignment portion (231) and an inactive alignment portion (233). The active portion, in which the metasurface effect is differently exhibited by a specific wavelength, is referred to as the security image.

[0083] Security images configured on each of the known first to sixth meta-surfaces (M1 to M16) can be formed, and some of the security images can be displayed according to wavelength range.

[0084] Referring to FIG. 15, the security image (apple) of the third meta surface (M3) can be exposed to incident beams of all wavelengths. The security images of the fourth, seventh, and ninth meta surfaces (M4, M7, M9) can be exposed at wavelengths other than 500 nm. Security images can be exposed at wavelengths other than 550 nm, such as with the eighth meta surface (M8). These combinations can be implemented in various ways.

[0085] Figure 16 illustrates the security image exposure state according to the wavelength and the presence or absence of voltage in the liquid crystal layer.

[0086] FIG. 16 may be one of the multiple metasurface portions of FIG. 15. FIG. 16(a) shows the liquid crystal layer with no voltage applied, and FIG. 16(b) shows the liquid crystal layer with voltage applied. For reference, light green (or light green) shows the arrangement of liquid crystal molecules.

[0087] Referring to Fig. 16(a), the present meta surface does not produce a security image at both green and red wavelengths. When voltage is applied to the liquid crystal layer, as shown in Fig. 16(b), the green wavelength does not change, but when the red wavelength is irradiated, an apple-shaped security image is exposed.

[0088] Furthermore, although preferred embodiments of the present invention have been illustrated and described above, the present invention is not limited to the specific embodiments described above. It is understood that various modifications can be made by those skilled in the art without departing from the essence of the invention as claimed in the claims, and such modifications should not be understood individually from the technical spirit or perspective of the present invention. Explanation of the symbols

[0089] 100: Metasurface layer 110: Base substrate 115: Front substrate 120: Base electrode layer 125: Front electrode layer 130: Base alignment layer 135: Front alignment layer 150: Liquid crystal layer 210: Light source 215: Light source filter 217: Active polarizer 218: Inactive polarizer 221: Active electrode part 223: Inactive electrode part 231: Active orientation 233: Inactive orientation

Claims

Claim 1 A liquid crystal layer that changes the polarization direction of at least some of the incident beams according to the strength of the electric field; a metasurface layer that imparts a metasurface effect to a transmitted beam passing through the liquid crystal layer, and imparts first and second metasurface effects different from each other to first and second polarized transmitted beams that are polarized perpendicular and horizontally with respect to a preset reference line; A liquid crystal device based on a light polarization direction and wavelength selective metasurface, comprising: a front alignment layer disposed on the front surface of the liquid crystal layer; wherein the front alignment layer comprises an active alignment portion and an inactive alignment portion, wherein the alignment of a first liquid crystal molecule in contact with the active alignment portion is perpendicular to the alignment direction of a second liquid crystal molecule in contact with a base alignment layer disposed on the rear surface of the liquid crystal layer, and wherein the alignment of a third liquid crystal molecule in contact with the inactive alignment portion is not perpendicular to the alignment of a fourth liquid crystal molecule in contact with the base alignment layer, and wherein the third liquid crystal molecule is a plurality and the alignment of each of the plurality of third liquid crystal molecules is different from one another, and wherein at least one of the first and second metasurface effects is a meta effect that varies depending on the wavelength of a polarization beam irradiated on the metasurface layer. Claim 2 delete Claim 3 A liquid crystal device based on a light polarization direction and wavelength selective metasurface, wherein the metasurface layer is provided in plurality in claim 1. Claim 4 A liquid crystal layer that changes the polarization direction of at least some of the incident beams according to the strength of the electric field; a metasurface layer that imparts a metasurface effect to a transmitted beam passing through the liquid crystal layer, and imparts first and second metasurface effects different from each other to first and second polarized transmitted beams that are polarized perpendicular and horizontally with respect to a preset reference line; A liquid crystal device based on a metasurface that is selective for polarization direction and wavelength of light, comprising: a front alignment layer disposed on the front surface of the liquid crystal layer; wherein the front alignment layer comprises an active alignment portion and an inactive alignment portion, wherein the orientation of a first liquid crystal molecule in contact with the active alignment portion is perpendicular to the orientation direction of a second liquid crystal molecule in contact with a base alignment layer disposed on the rear surface of the liquid crystal layer, and the orientation of a third liquid crystal molecule in contact with the inactive alignment portion is not perpendicular to the orientation of a fourth liquid crystal molecule in contact with the base alignment layer, and wherein the third liquid crystal molecule is a plurality and the orientation of each of the plurality of third liquid crystal molecules is different from one another, and wherein the intensity of a first emission beam according to the first metasurface effect is either greater than or smaller than the intensity of a second emission beam according to the second metasurface effect. Claim 5 A liquid crystal device based on a light polarization direction and wavelength selective metasurface according to claim 1 or 4, wherein the active and inactive orientation portions are partitioned by at least one of physical rubbing and ultraviolet irradiation.

Images