Diffractive optical element, method for manufacturing same, hologram using same, vr / ar device using same, and hud using same

Abstract

Provided is a method for manufacturing a diffractive optical element. The method for manufacturing a diffractive optical element may comprise: a step for preparing an imprinting stamp including a stamp pattern in which peaks and valleys having a curved shape are alternately and repeatedly arranged; a step for preparing a base structure in which a coating layer including a photocurable polymer and nanoparticles is formed on a base substrate; and a step for applying pressure to the coating layer of the base structure using the imprinting stamp to form, in the coating layer, a base pattern having the inverse image of the stamp pattern.

Description

Diffractive optical elements and their manufacturing methods, holograms using them, VR / AR devices using them, and HUDs using them

[0001] The present invention relates to a diffractive optical element and a method for manufacturing the same, and more particularly, to a diffractive optical element in which a pattern is formed on a material having a high refractive index and being transparent, and a method for manufacturing the same.

[0002] The diffractive optical element and its manufacturing method according to an embodiment of the present invention can be used in holograms, VR (virtual reality) / AR (Augmented Reality) devices, and HUD (head up display).

[0003] Diffractive optical elements are optical elements used in various optical fields, from spectrometers and analog holograms to digital holograms.

[0004] Recently, a method for manufacturing optical elements using polymers containing azobenzene molecules has been extensively studied. This technology has the advantage of being easy to manufacture and having high yields, as it can form structures simply by irradiating specific light patterns without a chemical etching process.

[0005] In addition, unlike diffractive optical elements that can be manufactured using other manufacturing methods, the optical element has a surface structure in the form of a sinusoid, which can reduce optical loss.

[0006] However, this optical element cannot be used in the entire visible light range due to the absorption characteristics of the material, and its diffraction efficiency is also limited, which limits its application.

[0007] Accordingly, the present invention aims to provide a diffractive optical element using a polymer containing azobenzene molecules, which can be easily used in the entire visible light range and has high diffraction efficiency, and a method for manufacturing the same.

[0008] The technical problem to be solved by the present invention is to provide a diffractive optical element using a polymer containing azobenzene molecules and a method for manufacturing the same.

[0009] Another technical problem to be solved by the present invention is to provide a diffractive optical element with reduced absorption rate and a method for manufacturing the same.

[0010] Another technical problem to be solved by the present invention is to provide a diffractive optical element with improved transmittance and a method for manufacturing the same.

[0011] Another technical problem that the present invention seeks to solve is to provide a diffractive optical element with improved refractive index and a method for manufacturing the same.

[0012] Another technical problem to be solved by the present invention is to provide a diffractive optical element with improved diffraction efficiency and a method for manufacturing the same.

[0013] Another technical problem to be solved by the present invention is to provide a diffractive optical element and a method for manufacturing the same, in which the manufacturing process is simplified and the process cost is reduced.

[0014] The technical problems to be solved by the present invention are not limited to those described above.

[0015] To solve the above technical problem, the present invention provides a method for manufacturing a diffractive optical element.

[0016] According to one embodiment, the method for manufacturing the diffractive optical element may include the steps of preparing an imprinting stamp including a stamp pattern in which peaks and valleys having a curved shape are alternately and repeatedly arranged in at least a portion of the stamp pattern, preparing a base structure having a coating layer including a photocurable polymer and nanoparticles formed on a base substrate, and applying pressure to the coating layer of the base structure using the imprinting stamp to form a base pattern having an inverse image of the stamp pattern on the coating layer.

[0017] According to one embodiment, the step of preparing the imprinting stamp may include the steps of preparing a sub-structure on a sub-substrate in which a polymer film including azobenzene molecules is formed, irradiating the polymer film with light to form a polymer pattern in which peaks and valleys having a curved shape are alternately and repeatedly arranged in at least a portion of the polymer pattern, coating a stamp composition including a thermosetting polymer on the polymer film to cover the polymer pattern, and heat-treating the stamp composition to manufacture the imprinting stamp including the stamp pattern having an inverse image of the polymer pattern.

[0018] According to one embodiment, the base pattern may include peaks and valleys having a curved shape arranged alternately and repeatedly, wherein the peaks of the base pattern correspond to valleys of the stamp pattern, and the valleys of the base pattern correspond to peaks of the stamp pattern.

[0019] According to one embodiment, the step of preparing the base structure may include the step of preparing a base substrate, the step of forming an adhesive layer on the base substrate, and the step of forming the coating layer on the adhesive layer.

[0020] According to one embodiment, the adhesive layer may include PMMA (Poly(methyl methacrylate)).

[0021] According to one embodiment, the method for manufacturing the diffractive optical element may further include a step of treating the base substrate with oxygen plasma before the step of forming the adhesive layer after the step of preparing the base substrate.

[0022] According to one embodiment, the method for manufacturing the diffractive optical element may further include a step of imparting hydrophobicity to a surface of the imprinting stamp on which the stamp pattern is formed, before the step of forming the base pattern and after the step of preparing the imprinting stamp.

[0023] According to one embodiment, the method may include treating the surface of the imprinting stamp on which the stamp pattern is formed with HMDS (Hexamethyldisilazane) to impart hydrophobicity.

[0024] According to one embodiment, a hydrophobic layer is further disposed on the surface of the imprinting stamp on which the stamp pattern is formed, and the base structure further includes an adhesive layer disposed between the base substrate and the coating layer, wherein the ΔW value derived through the following <Mathematical Formula 1> is 40 mJ / m 2 It may include the following:

[0025] <Mathematical Formula 1>

[0026]

[0027] ( : Dispersion surface energy, : Polar surface energy, : the above base substrate, : the above coating layer, : (imprinting stamp above)

[0028] To solve the above technical problem, the present invention provides a diffractive optical element.

[0029] According to one embodiment, a diffractive optical element including a diffractive optical layer including a polymer and nanoparticles, wherein the diffractive optical layer includes a base pattern in which peaks and valleys having a curved shape are alternately and repeatedly arranged, and may include a diffraction efficiency of 30% or more.

[0030] According to one embodiment, the diffractive optical element may include one having a transmittance of 80% or greater for light having a wavelength of 400 nm to 800 nm.

[0031] In one embodiment, the polymer may comprise Dipentaerythritol penta- / hexa-acrylate or BzMA (Benzyl methacrylate).

[0032] In one embodiment, the nanoparticles may include titanium oxide (TiO2) nanoparticles.

[0033]

[0034] A diffractive optical element according to an embodiment of the present invention has a structure in which a sinusoidal pattern is formed on a coating layer having high refractive index and transparency. A polymer containing azobenzene molecules can be used to form the sinusoidal pattern. Accordingly, a sinusoidal pattern can be formed without a complex etching process, thereby simplifying the process and reducing process costs.

[0035] In addition, the structure described above (a structure in which a sinusoidal pattern is formed on a coating layer having high refractive index and transparent properties) can have a high transmittance of 80% or more for the entire visible light range (e.g., wavelengths from 400 nm to 800 nm), so that it can be easily used in the entire visible light range, and the diffraction efficiency for the entire visible light range can also have a theoretical maximum value.

[0036]

[0037] FIG. 1 is a flowchart illustrating a method for manufacturing a diffractive optical element according to an embodiment of the present invention.

[0038] FIG. 2 is a flowchart specifically explaining step S100 of a method for manufacturing a diffractive optical element according to an embodiment of the present invention.

[0039] FIG. 3 is a schematic diagram illustrating step S110 of a method for manufacturing a diffractive optical element according to an embodiment of the present invention.

[0040] FIG. 4 is a schematic diagram illustrating step S120 of a method for manufacturing a diffractive optical element according to an embodiment of the present invention.

[0041] FIG. 5 is a schematic diagram illustrating step S130 of a method for manufacturing a diffractive optical element according to an embodiment of the present invention.

[0042] FIG. 6 is a schematic diagram illustrating step S140 of a method for manufacturing a diffractive optical element according to an embodiment of the present invention.

[0043] FIG. 7 is a schematic diagram illustrating step S150 of a method for manufacturing a diffractive optical element according to an embodiment of the present invention.

[0044] FIG. 8 is a flowchart specifically explaining step S200 of a method for manufacturing a diffractive optical element according to an embodiment of the present invention.

[0045] FIG. 9 is a schematic diagram illustrating steps S210 and S220 of a method for manufacturing a diffractive optical element according to an embodiment of the present invention.

[0046] FIG. 10 is a schematic diagram illustrating steps S230 and S240 of a method for manufacturing a diffractive optical element according to an embodiment of the present invention.

[0047] FIG. 11 and FIG. 12 are schematic diagrams for explaining step S300 of a method for manufacturing a diffractive optical element according to an embodiment of the present invention.

[0048] Figure 13 is a photograph of a coating layer of a diffractive optical element according to an experimental example of the present invention.

[0049] FIG. 14 is a drawing for explaining the results of transmittance measurements for an adhesive layer and a coating layer in a diffractive optical element according to an experimental example of the present invention.

[0050] Figure 15 is a drawing for explaining the results of measuring the refractive index of a coating layer in a diffractive optical element according to an experimental example of the present invention.

[0051] Figure 16 is a drawing for explaining the theoretical diffraction efficiency of a diffractive optical element according to an experimental example of the present invention.

[0052] Figure 17 is a drawing comparing the actual diffraction efficiency and theoretical diffraction efficiency of a diffractive optical element according to an experimental example of the present invention.

[0053] Figure 18 is a drawing comparing the diffraction trends of a diffractive optical element according to an experimental example of the present invention and a diffractive optical element according to a comparative example.

[0054] FIG. 19 and FIG. 20 are drawings for explaining the influence of the bonding work value in the manufacturing process of a diffractive optical element according to an experimental example of the present invention.

[0055] FIG. 21 and FIG. 22 are drawings for explaining the influence of the content of photocurable polymer and nanoparticles in the manufacturing process of a diffractive optical element according to an experimental example of the present invention.

[0056] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. However, the technical concept of the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided to ensure that the disclosed content is thorough and complete and to sufficiently convey the spirit of the present invention to those skilled in the art.

[0057] In this specification, when a component is referred to as being on another component, it means that it can be formed directly on the other component, or a third component may be interposed between them. In addition, in the drawings, the thicknesses of films and regions are exaggerated for the purpose of effectively explaining the technical contents.

[0058] Also, although terms such as first, second, and third have been used to describe various components in various embodiments of this specification, these components should not be limited by these terms. These terms are only used to distinguish one component from another. Thus, what is referred to as a first component in one embodiment may be referred to as a second component in another embodiment. Each embodiment described and illustrated herein also includes its complementary embodiments. Also, the term "and / or" has been used herein to mean including at least one of the components listed before and after.

[0059] In the specification, singular expressions include plural expressions unless the context clearly dictates otherwise. In addition, terms such as "comprise" or "have" are intended to specify the presence of a feature, number, step, component, or combination thereof described in the specification, and should not be construed as excluding the presence or addition of one or more other features, numbers, steps, components, or combinations thereof. In addition, the term "connection" is used in the present specification to mean both indirectly connecting multiple components and directly connecting them.

[0060] In addition, when describing the present invention below, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description will be omitted.

[0061]

[0062] FIG. 1 is a flowchart illustrating a method for manufacturing a diffractive optical element according to an embodiment of the present invention.

[0063] Referring to FIG. 1, a method for manufacturing a diffractive optical element according to an embodiment of the present invention may include a step of preparing an imprinting stamp (S100), a step of preparing a base structure having a coating layer formed thereon (S200), and a step of applying pressure to the coating layer of the base structure using the imprinting stamp to form a base pattern on the coating layer (S300). Each step is described below.

[0064] Imprinting Stamp Preparation Step (S100)

[0065] FIG. 2 is a flowchart specifically explaining step S100 of a method for manufacturing a diffractive optical element according to an embodiment of the present invention, FIG. 3 is a schematic diagram for explaining step S110 of a method for manufacturing a diffractive optical element according to an embodiment of the present invention, FIG. 4 is a schematic diagram for explaining step S120 of a method for manufacturing a diffractive optical element according to an embodiment of the present invention, FIG. 5 is a schematic diagram for explaining step S130 of a method for manufacturing a diffractive optical element according to an embodiment of the present invention, FIG. 6 is a schematic diagram for explaining step S140 of a method for manufacturing a diffractive optical element according to an embodiment of the present invention, and FIG. 7 is a schematic diagram for explaining step S150 of a method for manufacturing a diffractive optical element according to an embodiment of the present invention.

[0066] Referring to FIGS. 2 and 3, a sub-structure (100) may be prepared in which a polymer film (120) including azobenzene molecules is formed on a sub-substrate (110) (S110). According to one embodiment, the sub-substrate (110) may include a glass substrate. According to one embodiment, the polymer film (120) may include pDR1m (Poly(Disperse Red 1 methacrylate)).

[0067] Referring to FIGS. 2 and 4, by irradiating light (L) onto the polymer film (120), a polymer pattern (120p) having peaks (120a) and valleys (120b) having a curved shape in at least some areas can be formed in an alternating and repetitive manner (S120).

[0068] According to one embodiment, the light (L) irradiated onto the polymer film (120) may include a polarization interference pattern (PIP). More specifically, the light (L) irradiated onto the polymer film (120) may include a polarization interference pattern in the form of a mixture of right circularly polarized (RCP) and left circularly polarized (LCP).

[0069] More specifically, when light (L) including a polarization interference pattern is irradiated onto the polymer film (120), azobenzene molecules are aligned perpendicular to the polarization direction and can move along the polarization direction. As a result, a polymer pattern (120p) in which peaks (120a) and valleys (120b) having a curved shape are alternately and repeatedly arranged can be formed on at least a portion of the polymer film (120). That is, due to the characteristics of azobenzene molecules, a sinusoidal pattern can be formed on the polymer film (120) by a simple method of irradiating light without an etching process.

[0070] Referring to FIGS. 2 and 5, a stamp composition (200) may be coated on the polymer film (120) to cover the polymer pattern (120p) (S130). According to one embodiment, the stamp composition (200) may include a thermosetting polymer. For example, the thermosetting polymer may include PDMS (polydimethylsiloxane).

[0071] Referring to FIGS. 2 and 6, an imprinting stamp (200) including a stamp pattern (200p) having an inverse image of the polymer pattern (120p) can be manufactured by heat-treating the stamp composition (200) (S140). That is, the imprinting stamp (200) can be defined as a state in which the stamp composition (200) is cured. In addition, the imprinting stamp (200) can be prepared in a state separated from the sub-structure (100).

[0072] As described above, since the stamp pattern (200p) of the imprinting stamp (200) has an inverse image of the polymer pattern (120p), the stamp pattern (200p) may also have a structure in which peaks (200a) and valleys (200b) are alternately and repeatedly arranged. The peaks (200a) of the stamp pattern (200p) may correspond to the valleys (120b) of the polymer pattern (120p), and the valleys (200b) of the stamp pattern (200p) may correspond to the peaks (120a) of the polymer pattern (120p).

[0073] Referring to FIGS. 2 and 7, hydrophobicity can be imparted to the surface on which the stamp pattern (200p) of the imprinting stamp (200) is formed (S150). More specifically, hydrophobicity can be imparted to the surface on which the stamp pattern (200p) of the imprinting stamp (200) is formed by treating it with HMDS (Hexamethyldisilazane). Accordingly, a hydrophobicity-imparting layer (210) can be formed on the surface of the imprinting stamp (200) on which the stamp pattern (200p) is formed.

[0074] The separation of the base structure (300) and the imprinting stamp (200) can be easily achieved in step S300, which will be described later, by the hydrophobic layer (210). In contrast, if the hydrophobic layer (210) is not present, a problem may arise in which the separation of the base structure (300) and the imprinting stamp (200) is not properly achieved in step S300, which will be described later.

[0075] Base structure preparation stage (S200)

[0076] FIG. 8 is a flowchart specifically explaining step S200 of a method for manufacturing a diffractive optical element according to an embodiment of the present invention, FIG. 9 is a schematic diagram for explaining steps S210 and S220 of a method for manufacturing a diffractive optical element according to an embodiment of the present invention, and FIG. 10 is a schematic diagram for explaining steps S230 and S240 of a method for manufacturing a diffractive optical element according to an embodiment of the present invention.

[0077] Referring to FIGS. 8 and 9, a base substrate (310) may be prepared (S210). According to one embodiment, the base substrate (310) may include a glass substrate.

[0078] The above base substrate (310) may be treated with oxygen plasma (O2 plasma) (S220). Accordingly, the adhesion between the adhesive layer described below and the base substrate (310) may be further improved. Conversely, if the oxygen plasma treatment step is omitted, a problem may arise in which the adhesive layer described below is not easily formed.

[0079] Referring to FIGS. 8 and 10, an adhesive layer (320) may be formed on the base substrate (310) (S230). According to one embodiment, the adhesive layer (320) may include PMMA (Poly(methyl methacrylate)). The adhesive layer (320) may improve adhesion between the coating layer described below and the base substrate (310).

[0080] A coating layer (330) may be formed on the adhesive layer (320) (S240). Accordingly, a base structure (300) may be prepared. According to one embodiment, the coating layer (330) may be formed by coating a base composition having a high refractive index and transparency. Accordingly, the coating layer (330) may also have a high refractive index and transparency.

[0081] According to one embodiment, the base composition may include a photocurable polymer, nanoparticles, a photoinitiator, and a solvent. For example, the photocurable polymer may include Dipentaerythritol penta- / hexa-acrylate or BzMA (Benzyl methacrylate). For example, the nanoparticles may include titanium oxide (TiO2) nanoparticles as metal nanoparticles capable of improving refractive index. For example, the photoinitiator may include Igacure 784 and may be used in an amount of 1 wt% based on the total weight of the base composition. For example, the solvent may include PGMEA (Propylene glycol monomethyl ether acetate).

[0082] According to one embodiment, the reliability of the diffractive optical layer described below can be controlled depending on the content of the photocurable polymer and the nanoparticles in the base composition.

[0083] For example, when the photocurable polymer comprises Dipentaerythritol penta- / hexa-acrylate and the nanoparticles comprise titanium oxide (TiO2) nanoparticles, the content of the nanoparticles:the photocurable polymer can be controlled to be greater than 70:30 wt% and less than 95:5 wt%. Accordingly, the reliability of the diffraction optical layer described below can be improved. In contrast, when the content of the nanoparticles:the photocurable polymer is controlled to be less than 70:30 wt%, a reliability degradation problem due to aggregation may occur. In addition, when the content of the nanoparticles:the photocurable polymer is controlled to be more than 95:5 wt%, a reliability degradation problem due to cracks may occur.

[0084] For another example, when the photocurable polymer comprises BzMA (Benzyl methacrylate) and the nanoparticles comprise titanium oxide (TiO2) nanoparticles, the content of the nanoparticles:the photocurable polymer can be controlled to be less than 95:5 wt%. Accordingly, the reliability of the diffraction optical layer described below can be improved. Conversely, when the content of the nanoparticles:the photocurable polymer is controlled to be 95:5 wt% or more, a problem of reduced reliability due to cracks may occur.

[0085] Base pattern formation step (S300)

[0086] FIG. 11 and FIG. 12 are schematic diagrams for explaining step S300 of a method for manufacturing a diffractive optical element according to an embodiment of the present invention.

[0087] Referring to FIGS. 1, 11, and 12, while applying pressure (Press) to the coating layer (330) of the base structure (300) with the imprinting stamp (200), UV light is irradiated to the coating layer (330), and then the imprinting stamp (200) can be separated (Pell off) from the base structure (300). Accordingly, a base pattern (330p) having an inverse image of the stamp pattern (200p) can be formed on the coating layer (330) (S300).

[0088] More specifically, pressure application and ultraviolet irradiation can be performed while the surface of the imprinting stamp (200) on which the hydrophobic layer (210) is formed is in contact with the coating layer (330). Accordingly, a base pattern (330p) having an inverse image of the stamp pattern (200p) can be formed on the coating layer (330).

[0089] Since the base pattern (330p) has an inverse image of the stamp pattern (200p), the base pattern (330p) may also have a structure in which peaks (330a) and valleys (330b) are alternately and repeatedly arranged. The peaks (330a) of the base pattern (330p) may correspond to the valleys (200b) of the stamp pattern (200p), and the valleys (330b) of the base pattern (300p) may correspond to the peaks (200a) of the stamp pattern (200p). That is, a sinusoidal pattern may be formed on the coating layer (330) having a high refractive index and transparent characteristics.

[0090] High refractive index polymer materials have a problem in that it is difficult to form a sinusoidal pattern without an etching process. Accordingly, the present invention provides a method for forming a sinusoidal pattern on a high refractive index polymer material without an etching process, comprising forming a sub-structure using an azobenzene-based polymer having a low refractive index but allowing a sinusoidal pattern to be easily formed without an etching process, manufacturing an imprinting stamp using the sub-structure, and then forming a sinusoidal pattern on a high refractive index polymer material through the imprinting stamp.

[0091] According to one embodiment, in the process of separating the imprinting stamp (200) from the base structure (300), a problem may occur in which the coating layer (330) does not remain on the adhesive layer (320) and is separated from the adhesive layer (320) together with the imprinting stamp (200). Accordingly, in order to solve the above-described problem, the work of adhesion value of the base structure (300) and the imprinting stamp (200) may be controlled. More specifically, the ΔW value derived through the following <Mathematical Formula 1> is 40 mJ / m 2 It can be controlled to have an ideal.

[0092] <Mathematical Formula 1>

[0093]

[0094] ( : Dispersion surface energy, : Polar surface energy, : the above base substrate, : the above coating layer, : (imprinting stamp above)

[0095] The coating layer (330) on which the base pattern (330p) is formed can be defined as a diffractive optical layer, and an element including the diffractive optical layer can be defined as a diffractive optical element. Since the diffractive optical layer has a structure in which the base pattern (330p) in a sinusoidal shape is formed on the coating layer (330) having a high refractive index and transparent characteristics, the diffraction efficiency for the entire visible light range can have a theoretical maximum value. More specifically, the diffractive optical element including the diffractive optical layer can have a diffraction efficiency value of 30% or more derived through the following <Mathematical Formula 2>. In other words, the diffractive optical element including the diffractive optical layer can be calculated by a diffraction efficiency calculation method of a thin sinusoidal phase grating.

[0096] <Mathematical Formula 2>

[0097]

[0098] DE m : diffraction efficiency, m: diffraction order, k0: wave number, n': refractive index of the diffractive optical layer, n: refractive index of air (=1), h0: maximum value of modulation height, J: Bessel function)

[0099] The Bessel function of <Mathematical Formula 2> can be expressed as <Mathematical Formula 3> below.

[0100] <Mathematical Formula 3>

[0101]

[0102] In the case of conventional diffractive optical elements manufactured by a method of forming a sinusoidal pattern by irradiating light on a polymer film containing azobenzene molecules, there is a problem that they cannot be used in the entire visible light range due to the characteristics (high absorption rate) of azobenzene molecules, and the diffraction efficiency is also low.

[0103] However, since the diffractive optical element according to an embodiment of the present invention has a structure in which the base pattern (330p) in a sinusoidal shape is formed on the coating layer (330) having a high refractive index and transparent characteristics, it can have a high transmittance of 80% or more for the entire visible light range (e.g., wavelengths from 400 nm to 800 nm), and can be easily used in the entire visible light range, and the diffraction efficiency for the entire visible light range can also have a theoretical maximum value. Due to these characteristics, the diffractive optical element according to an embodiment of the present invention can be used in holograms, VR (virtual reality) / AR (Augmented Reality) devices, and HUD (head up display).

[0104] Above, a diffractive optical element and a method for manufacturing the same according to an embodiment of the present invention have been described. Below, specific experimental examples and characteristic evaluation results of a diffractive optical element and a method for manufacturing the same according to an embodiment of the present invention are described.

[0105] Experimental Example 1: Fabrication of Diffractive Optical Elements

[0106] A polymer film of pDR1m (Poly(Disperse Red 1 methacrylate)) was coated on an organic substrate, and light containing a polarized interference pattern was irradiated to form a polymer pattern in the shape of a sinusoidal wave. Subsequently, polydimethylsiloxane (PDMS) was coated to cover the polymer pattern, and the PDMS was hardened by heat treatment. The hardened PDMS was separated into polymer films, thereby manufacturing an imprinting stamp in which a sinusoidal stamp pattern was formed on the surface of the hardened PDMS. In addition, the surface of the imprinting stamp on which the stamp pattern was formed was treated with HMDS (Hexamethyldisilazane) to impart hydrophobicity.

[0107] After treating a glass substrate with oxygen plasma, an adhesive layer was formed by coating PMMA (Poly(methyl methacrylate)) on the glass substrate. Thereafter, a base composition including a photocurable polymer, nanoparticles, a photoinitiator, and a solvent was coated on the adhesive layer to form a coating layer, thereby manufacturing a base structure. More specifically, Dipentaerythritol penta- / hexa-acrylate or BzMA (Benzyl methacrylate) was used as the photocurable polymer, titanium oxide (TiO2) nanoparticles were used as the nanoparticles, Igacure 784 (1 wt% based on the total weight of the base composition) was used as the photoinitiator, and PGMEA (Propylene glycol monomethyl ether acetate) was used as the solvent.

[0108] Finally, while the coating layer of the base structure was in contact with the stamp pattern of the imprinting stamp, pressure was applied to the base structure using the imprinting stamp, and the coating layer was irradiated with ultraviolet light to harden the coating layer. Thereafter, the base structure and the imprinting stamp were separated. Accordingly, a diffractive optical element was manufactured, in which a sinusoidal base pattern was formed on the coating layer.

[0109] Figure 13 is a photograph of a coating layer of a diffractive optical element according to an experimental example of the present invention.

[0110] Referring to (a) of Fig. 13, a photograph is taken of a state in which a base pattern of a coating layer is formed with a period of 2700 nm, and referring to (b) of Fig. 13, a photograph is taken of a state in which a base pattern of a coating layer is formed with a period of 760 nm. As can be seen in (a) and (b) of Fig. 13, it can be confirmed that the base pattern of the diffractive optical element according to the experimental example has a highly reliable sinusoidal wave shape.

[0111]

[0112] Experimental Example 2: Measurement of Transmittance and Refractive Index of Diffractive Optical Elements

[0113] FIG. 14 is a drawing for explaining the results of transmittance measurements for an adhesive layer and a coating layer in a diffractive optical element according to an experimental example of the present invention.

[0114] Referring to Fig. 14, the transmittance of the adhesive layer (PMMA) and the coating layer of the diffractive optical element according to the experimental example were measured, respectively. In addition, the coating layer was prepared by preparing base compositions having different contents of nanoparticles (TiO2) and photocurable polymer (Acrylate), and then the transmittance of the coating layer formed from each base composition was measured. More specifically, the transmittance of the coating layer formed from each base composition having a content of nanoparticles (TiO2):photocurable polymer (Acrylate) in the ratios of 9:1, 8:2, and 7:3 was measured.

[0115] As can be seen in Fig. 14, the coating layers formed with the adhesive layer (PMMA) and the base compositions having a content of 9:1 and 7:3 all have a high transmittance of 80% or more within the visible light range (400 nm to 800 nm). In addition, the coating layer formed with the base composition having a content of 8:2 also has a high transmittance approaching 80%.

[0116] Figure 15 is a drawing for explaining the results of measuring the refractive index of a coating layer in a diffractive optical element according to an experimental example of the present invention.

[0117] Referring to Fig. 15, the refractive index was measured for each of the coating layer (high refractive index resin) and the azopolymer film (azopolymer) formed from a base composition having a content of nanoparticles (TiO2) and photocurable polymer (acrylate) of 9:1.

[0118] As can be seen in Fig. 15, the coating layer within the diffractive optical element according to the above experimental example can be confirmed to have a higher refractive index compared to the azopolymer film. Consequently, as can be seen in Figs. 14 and 15, the diffractive optical element according to the above experimental example can be seen to have a high refractive index while being transparent.

[0119]

[0120] Experimental Example 3: Diffraction Efficiency and Diffraction Trend of Diffractive Optical Elements

[0121] Figure 16 is a drawing for explaining the theoretical diffraction efficiency of a diffractive optical element according to an experimental example of the present invention.

[0122] Referring to Fig. 16, the theoretical diffraction efficiency of the diffractive optical element according to the above experimental example is derived through <Mathematical Formula 2> below, and the derived result value is shown.

[0123] <Mathematical Formula 2>

[0124]

[0125] DE m : diffraction efficiency, m: diffraction order, k0: wave number, n': refractive index of the diffractive optical layer, n: refractive index of air (=1), h0: maximum value of modulation height, J: Bessel function)

[0126] As can be seen in Fig. 16 and <Mathematical Formula 2>, the main variables that determine the diffraction efficiency are the refractive index of the diffractive optical layer (coating layer) and the maximum value of the modulation height. In addition, the value of the refractive index is n low is 1.7, n high When comparing the diffraction efficiency by setting it to 2.0, it can be seen that when the refractive index value is high, the maximum diffraction efficiency can be achieved at a lower modulation height.

[0127] Accordingly, it can be seen that when a sinusoidal pattern is formed on a coating layer having high transmittance and high refractive index characteristics as in the present invention, the refractive index can be further improved, and thus the theoretical maximum diffraction efficiency can be achieved.

[0128] Figure 17 is a drawing comparing the actual diffraction efficiency and theoretical diffraction efficiency of a diffractive optical element according to an experimental example of the present invention.

[0129] Referring to Fig. 17, the actual diffraction efficiency (Exp.) and the theoretical diffraction efficiency (Sim.) of the diffractive optical element according to the experimental example are compared. More specifically, Fig. 17 (a) shows the result measured for light having a wavelength of 488 nm, Fig. 17 (b) shows the result measured for light having a wavelength of 532 nm, and Fig. 17 (c) shows the result measured for light having a wavelength of 640 nm. In addition, A, B, and C shown in Figs. 17 (a) to (c) represent diffractive optical elements having different modulation heights.

[0130] As can be seen in Fig. 17, it can be confirmed that all diffractive optical elements with different modulation heights have a diffraction efficiency close to the theoretical maximum diffraction efficiency for light with a wavelength of 488 nm to 640 nm.

[0131] Figure 18 is a drawing comparing the diffraction trends of a diffractive optical element according to an experimental example of the present invention and a diffractive optical element according to a comparative example.

[0132] Referring to (a) of Fig. 18, a diffractive optical element is prepared by irradiating light including a polarization interference pattern on a polymer film including azobenzene molecules as a diffractive optical element according to a comparative example to form a polymer pattern in the form of a sinusoidal wave, and then the diffraction tendency thereof is measured and shown. Referring to (b) of Fig. 18, a diffractive optical element according to the experimental example is prepared and then the diffraction tendency thereof is measured and shown.

[0133] As can be seen in (a) and (b) of Fig. 18, in the diffractive optical element according to the comparative example, no diffraction signal is observed for light with a wavelength of about 550 nm or less due to absorption of azobenzene molecules, whereas in the diffractive optical element according to the experimental example, a diffraction signal is clearly observed for the entire visible light range.

[0134]

[0135] Experimental Example 4: Checking the Influence of Adhesive Work Values

[0136] FIG. 19 and FIG. 20 are drawings for explaining the influence of the bonding work value in the manufacturing process of a diffractive optical element according to an experimental example of the present invention.

[0137] Referring to (a) to (d) of Fig. 19, four diffractive optical elements manufactured according to the experimental example described above but manufactured under different conditions are prepared and then photographed to show the state of each coating layer. The four diffractive optical elements manufactured under different conditions are defined as samples 1-1 to 1-4, and (a) to (d) of Fig. 19 photograph and show the state of the coating layer of samples 1-1 to 1-4, respectively.

[0138] More specifically, Sample 1-1 is a diffractive optical element manufactured under conditions in which both an adhesive layer (PMMA) and a hydrophobic layer (HMDS) are used, Sample 1-2 is a diffractive optical element manufactured under conditions in which an adhesive layer (PMMA) is used but a hydrophobic layer (HMDS) is not used, Sample 1-3 is a diffractive optical element manufactured under conditions in which an adhesive layer (PMMA) is not used but a hydrophobic layer (HDMS) is used, and Sample 1-4 is a diffractive optical element manufactured under conditions in which neither an adhesive layer (PMMA) nor a hydrophobic layer (HDMS) is used.

[0139] In addition, all samples 1-1 to 1-4 used BzMA (Benzyl methacrylate) as a photocurable polymer, and the ΔW value for each sample was measured using <Mathematical Formula 1> below. The manufacturing conditions and ΔW values ​​of samples 1-1 to 1-4 are summarized in below.

[0140] <Mathematical Formula 1>

[0141]

[0142] ( : Dispersion surface energy, : Polar surface energy, : the above base substrate, : the above coating layer, : (imprinting stamp above)

[0143] Photocurable polymer adhesive layer (PMMA) Hydrophobic layer (HDMS) ΔW (mJ / cm 2 ) Sample 1-1 BzMAOO40.624 Sample 1-2 BzMAOX38.0347 Sample 1-3 BzMAXO30.5079 Sample 1-4 BzMAXX27.9186

[0144] As can be seen in (a) to (d) of Fig. 19, in the case of the 1-1 sample having a ΔW value of 40 or more, it can be confirmed that there are no defects on the surface of the coating layer. In contrast, in the case of the 1-2 to 1-4 samples having a ΔW value of less than 40, it can be confirmed that defects are formed on the surface of the coating layer.

[0145] Referring to (a) to (d) of Fig. 20, four diffractive optical elements manufactured according to the experimental example described above but manufactured under different conditions are prepared, and then the states of their respective coating layers are photographed and shown. The four diffractive optical elements manufactured under different conditions are defined as samples 2-1 to 2-4, and (a) to (d) of Fig. 20 show the states of the coating layers of samples 2-1 to 2-4, respectively.

[0146] More specifically, the 2-1 sample is a diffractive optical element manufactured under conditions in which both an adhesive layer (PMMA) and a hydrophobic layer (HMDS) are used, the 2-2 sample is a diffractive optical element manufactured under conditions in which an adhesive layer (PMMA) is used but a hydrophobic layer (HMDS) is not used, the 2-3 sample is a diffractive optical element manufactured under conditions in which an adhesive layer (PMMA) is not used but a hydrophobic layer (HDMS) is used, and the 2-4 sample is a diffractive optical element manufactured under conditions in which neither an adhesive layer (PMMA) nor a hydrophobic layer (HDMS) is used.

[0147] In addition, all samples 2-1 to 2-4 used Dipentaerythritol penta- / hexa-acrylate as a photocurable polymer, and the ΔW value for each sample was measured using the above-described <Mathematical Formula 1>. The manufacturing conditions and ΔW values ​​of the samples 2-1 to 2-4 are summarized in below.

[0148] Photocurable polymer adhesive layer (PMMA) Hydrophobic layer (HDMS) ΔW (mJ / cm 2) Sample 2-1 Dipentaerythritol penta- / hexa-acrylate OO48.9767 Sample 2-2 Dipentaerythritol penta- / hexa-acrylate OX46.3661 Sample 2-3 Dipentaerythritol penta- / hexa-acrylate XO46.0923 Sample 2-4 Dipentaerythritol penta- / hexa-acrylateXX43.4816

[0149] As can be seen in (a) to (d) of Fig. 20, it can be confirmed that all of the samples 2-1 to 2-4 have no defects on the surface of the coating layer.

[0150] As a result, as can be seen from Experimental Example 4, in order to form a reliable coating layer without defects, the ΔW value is 40 mJ / cm 2 It can be seen that the ideal should be achieved. In addition, when BzMA is used as a photocurable polymer, the ΔW value is 40 mJ / cm 2 It can be seen that an adhesive layer (PMMA) and a hydrophobic layer (HDMS) are required to achieve this ideal. On the other hand, when Dipentaerythritol penta- / hexa-acrylate is used as a photocurable polymer, the ΔW value is 40 mJ / cm regardless of the adhesive layer (PMMA) and the hydrophobic layer (HDMS). 2 You can see that it has an ideal.

[0151]

[0152] Experimental Example 5: Confirming the Effect of Photocurable Polymer and Nanoparticle Contents

[0153] FIG. 21 and FIG. 22 are drawings for explaining the influence of the content of photocurable polymer and nanoparticles in the manufacturing process of a diffractive optical element according to an experimental example of the present invention.

[0154] Referring to (a) to (d) of Fig. 21, four diffractive optical elements manufactured according to the experimental example described above but manufactured under different conditions are prepared, and then the states of their respective coating layers are photographed and shown. The four diffractive optical elements manufactured under different conditions are defined as samples 3-1 to 3-4, and (a) to (d) of Fig. 21 show the states of the coating layers of samples 3-1 to 3-4, respectively.

[0155] More specifically, samples 3-1 to 3-4 were manufactured under different conditions, each with different contents of photocurable polymer and nanoparticles in the base composition for forming a coating layer, and Dipentaerythritol penta- / hexa-acrylate was used as the photocurable polymer.

[0156] In addition, the 3-1 sample is a diffractive optical element manufactured under the condition that the content of nanoparticles:photocurable polymer is 70:30 wt%, the 3-2 sample is a diffractive optical element manufactured under the condition that the content of nanoparticles:photocurable polymer is 80:20 wt%, the 3-3 sample is a diffractive optical element manufactured under the condition that the content of nanoparticles:photocurable polymer is 90:10 wt%, and the 3-4 sample is a diffractive optical element manufactured under the condition that the content of nanoparticles:photocurable polymer is 95:5 wt%.

[0157] Classification Photocurable polymer nanoparticles: Photocurable polymer (wt%) Sample 3-1 Dipentaerythritol penta- / hexa-acrylate 70:30 Sample 3-2 Dipentaerythritol penta- / hexa-acrylate 80:20 Sample 3-3 Dipentaerythritol penta- / hexa-acrylate 90:10 Sample 3-4 Dipentaerythritol penta- / hexa-acrylate 95:5

[0158] As can be seen in (b) and (c) of Fig. 21, there are no defects (aggregation or cracks) in the coating layers of the 3-2 and 3-3 samples, whereas as can be seen in (a) and (d) of Fig. 21, aggregation occurred in the coating layer of the 3-1 sample, and cracks were formed in the coating layer of the 3-4 sample.

[0159] That is, when Dipentaerythritol penta- / hexa-acrylate is used as a photocurable polymer for forming a coating layer in the process of manufacturing a diffractive optical element according to an embodiment of the present invention, it can be seen that the content of nanoparticles:photocurable polymer must be controlled to be greater than 70:30 wt% and less than 95:5 wt% in order to form a highly reliable coating layer.

[0160] Referring to (a) to (d) of Fig. 22, four diffractive optical elements manufactured according to the experimental example described above but manufactured under different conditions are prepared, and then the states of their respective coating layers are photographed and shown. The four diffractive optical elements manufactured under different conditions are defined as samples 4-1 to 4-4, and (a) to (d) of Fig. 22 show the states of the coating layers of samples 4-1 to 4-4, respectively.

[0161] More specifically, samples 4-1 to 4-4 were manufactured under different conditions with different contents of photocurable polymer and nanoparticles in the base composition for forming a coating layer, and BzMA (Benzyl methacrylate) was used as the photocurable polymer.

[0162] In addition, the 4-1 sample is a diffractive optical element manufactured under the condition that the content of nanoparticles:photocurable polymer is 70:30 wt%, the 4-2 sample is a diffractive optical element manufactured under the condition that the content of nanoparticles:photocurable polymer is 80:20 wt%, the 4-3 sample is a diffractive optical element manufactured under the condition that the content of nanoparticles:photocurable polymer is 90:10 wt%, and the 4-4 sample is a diffractive optical element manufactured under the condition that the content of nanoparticles:photocurable polymer is 95:5 wt%.

[0163] Photocurable polymer nanoparticles: Photocurable polymer (wt%) Sample 4-1 BzMA 70:30 Sample 4-2 BzMA 80:20 Sample 4-3 BzMA 90:10 Sample 4-4 BzMA 95:5

[0164] As can be seen in (a) to (c) of Fig. 22, there are no defects (cracks) in the coating layers of samples 4-1 to 4-3, whereas as can be seen in (d) of Fig. 22, cracks are formed in the coating layer of sample 4-4.

[0165] That is, when BzMA (Benzyl methacrylate) is used as a photocurable polymer for forming a coating layer in the process of manufacturing a diffractive optical element according to an embodiment of the present invention, it can be seen that the content of nanoparticles:photocurable polymer must be controlled to less than 95:5 wt% in order to form a highly reliable coating layer.

[0166]

[0167] While the present invention has been described in detail using preferred embodiments, the scope of the present invention is not limited to the specific embodiments described above, and should be interpreted in accordance with the appended claims. Furthermore, those skilled in the art will appreciate that numerous modifications and variations are possible without departing from the scope of the present invention.

[0168]

[0169] The present invention can be used in the semiconductor industry.

Claims

1. A step of preparing an imprinting stamp including a stamp pattern in which peaks and valleys having a curved shape are arranged alternately and repeatedly in at least some areas; A step of preparing a base structure in which a coating layer including a photocurable polymer and nanoparticles is formed on a base substrate; and A method for manufacturing a diffractive optical element, comprising the step of applying pressure to the coating layer of the base structure using the imprinting stamp to form a base pattern having an inverse image of the stamp pattern on the coating layer.

2. In paragraph 1, The steps for preparing the above imprinting stamp are: A step of preparing a sub-structure in which a polymer film containing azobenzene molecules is formed on a sub-substrate; A step of irradiating light onto the polymer film to form a polymer pattern in which peaks and valleys having a curved shape are alternately and repeatedly arranged in at least some areas; A step of coating a stamp composition including a thermosetting polymer on the polymer film to cover the polymer pattern; and A method for manufacturing a diffractive optical element, comprising the step of heat-treating the stamp composition to manufacture the imprinting stamp including the stamp pattern having an inverse image of the polymer pattern.

3. In paragraph 1, The above base pattern has peaks and valleys having a curved shape arranged alternately and repeatedly, A method for manufacturing a diffractive optical element, wherein the peak of the base pattern corresponds to the valley of the stamp pattern, and the valley of the base pattern corresponds to the peak of the stamp pattern.

4. In paragraph 1, The step of preparing the above base structure is: Steps to prepare the base substrate; A step of forming an adhesive layer on the base substrate; and A method for manufacturing a diffractive optical element, comprising the step of forming the coating layer on the adhesive layer.

5. In paragraph 4, A method for manufacturing a diffractive optical element, wherein the adhesive layer comprises PMMA (Poly(methyl methacrylate)).

6. In paragraph 4, After the step of preparing the base substrate and before the step of forming the adhesive layer, A method for manufacturing a diffractive optical element further comprising the step of treating the base substrate with oxygen plasma.

7. In paragraph 1, After the step of preparing the above imprinting stamp and before the step of forming the above base pattern, A method for manufacturing a diffractive optical element further comprising a step of imparting hydrophobicity to a surface on which the stamp pattern of the imprinting stamp is formed.

8. In paragraph 7, A method for manufacturing a diffractive optical element, comprising treating a surface on which the stamp pattern of the imprinting stamp is formed with HMDS (Hexamethyldisilazane) to impart hydrophobicity.

9. In paragraph 1, A hydrophobic layer is further disposed on the surface of the imprinting stamp on which the stamp pattern is formed, and the base structure further includes an adhesive layer disposed between the base substrate and the coating layer. The ΔW value derived through <Mathematical Formula 1> below is 40 mJ / m 2 A method for manufacturing a diffractive optical element including the above. <Mathematical Formula 1> ( : Dispersion surface energy, : Polar surface energy, : the above base substrate, : the above coating layer, : (imprinting stamp above) 10. In a diffractive optical element including a diffractive optical layer including a polymer and nanoparticles, The above diffractive optical layer includes a base pattern in which peaks and valleys having a curved shape are alternately and repeatedly arranged, A diffractive optical element comprising a diffraction efficiency of 30% or more.

11. In paragraph 10, A diffractive optical element comprising a light having a transmittance of 80% or more for light having a wavelength of 400 nm to 800 nm.

12. In paragraph 10, The above polymer is a diffractive optical element comprising Dipentaerythritol penta- / hexa-acrylate or BzMA (Benzyl methacrylate).

13. In paragraph 10, The above nanoparticles are diffractive optical elements comprising titanium oxide (TiO2) nanoparticles.

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