Diffractive optical element, method of manufacturing same, hologram using same, virtual reality / augmented reality device using same, and head-up display using same

Abstract

The invention discloses a manufacturing method of a diffractive optical element. The manufacturing method of the diffractive optical element may include the following steps; an imprint template preparation step of preparing an imprint template including a template pattern in which peaks and valleys having a curved shape are alternately and repeatedly arranged; a base structure preparation step in which a coating layer containing a photocurable polymer and nanoparticles is formed on the base substrate; and a base pattern forming step of applying pressure to the coating layer of the base structure with the imprint template to form a base pattern having a reverse pattern of the template pattern on the coating layer.

Description

TECHNICAL FIELD

[0001] The present application relates to a diffractive optical element and a manufacturing method thereof, and more particularly, to a diffractive optical element in which a pattern is formed in a material having a high refractive index and transparency and a manufacturing method thereof.

[0002] The diffractive optical element and the manufacturing method thereof according to an embodiment of the present application can be used in a hologram, a virtual reality (VR) / augmented reality (AR) device, and a head up display (HUD). BACKGROUND

[0003] The diffractive optical element is an optical element used in a wide range of optical fields including a spectrometer and an analog hologram or a digital hologram.

[0004] Recently, a method of manufacturing an optical element using a polymer containing an azobenzene molecule has been actively studied, and this is a technology in which a structure is formed by irradiating only a specific light pattern without a chemical etching process, thereby making the manufacturing process easy and improving yield.

[0005] Further, unlike a diffractive optical element manufactured using other manufacturing methods, the surface structure of the optical element is formed in a sinusoidal wave shape, thereby reducing optical loss.

[0006] However, the optical element cannot be used in the entire visible light region due to the absorption characteristics of the material, and the diffraction efficiency is also limited, thereby having limitations in application.

[0007] Therefore, the present application aims to provide a diffractive optical element and a manufacturing method thereof, which manufacture a diffractive optical element using a polymer containing an azobenzene molecule, can be easily used in the entire visible light region, and has a high diffraction efficiency. SUMMARY

[0008] PROBLEMS TO BE SOLVED BY THE INVENTION

[0009] One technical problem to be solved by the present application is to provide a diffractive optical element and a manufacturing method thereof using a polymer containing an azobenzene molecule.

[0010] Another technical problem to be solved by the present application is to provide a diffractive optical element and a manufacturing method thereof in which the absorption rate is reduced.

[0011] Still another technical problem to be solved by the present application is to provide a diffractive optical element and a manufacturing method thereof in which the transmittance is improved.

[0012] Still another technical problem to be solved by the present application is to provide a diffractive optical element and a manufacturing method thereof in which the refractive index is improved.

[0013] Still another problem to be solved by the present application is to provide a diffractive optical element with improved diffraction efficiency and a manufacturing method thereof.

[0014] Still another problem to be solved by the present application is to provide a diffractive optical element with simplified manufacturing process and reduced manufacturing cost and a manufacturing method thereof.

[0015] The technical problems to be solved by the present application are not limited to the foregoing technical problems.

[0016] Solutions to the problems

[0017] To solve the technical problems, the present application discloses a manufacturing method of a diffractive optical element.

[0018] According to an embodiment, the manufacturing method of a diffractive optical element can include the following steps: a stamping template preparation step, the stamping template including a template pattern with peaks and valleys alternately and repeatedly arranged in a curved shape in at least a part of the area; a base structure preparation step, a coating layer including a photocurable polymer and nanoparticles is formed on a base substrate; and a base pattern formation step, a base pattern with an inverse pattern of the template pattern is formed on the coating layer of the base structure by applying pressure to the coating layer of the base structure with the stamping template.

[0019] According to an embodiment, the stamping template preparation step can include the following steps: a sub-structure preparation step, a polymer film including an azobenzene molecule is formed on a sub-substrate; a polymer pattern formation step, a polymer pattern with peaks and valleys alternately and repeatedly arranged in a curved shape is formed in at least a part of the area by irradiating light to the polymer film; a template composition coating step, a template composition including a thermocurable polymer is coated on the polymer film in a manner to cover the polymer pattern; and a stamping template manufacturing step, the stamping template including the template pattern with an inverse pattern of the polymer pattern is manufactured by heat treating the template composition.

[0020] According to an embodiment, in the base pattern, peaks and valleys alternately and repeatedly arranged in a curved shape, the peaks of the base pattern correspond to the valleys of the template pattern, and the valleys of the base pattern correspond to the peaks of the template pattern.

[0021] According to an embodiment, the base structure preparation step can include the following steps: a base substrate preparation step; a step of forming an adhesive layer on the base substrate; and a step of forming the coating layer on the adhesive layer.

[0022] According to an embodiment, the adhesive layer can include poly (methyl methacrylate) (PMMA).

[0023] According to an embodiment, the manufacturing method of the diffractive optical element, after the base substrate preparation step, before the adhesive layer formation step, further includes a step of treating the base substrate with oxygen plasma.

[0024] According to an embodiment, the manufacturing method of the diffractive optical element, after the imprinting mold preparation step, before the base pattern formation step, further includes a step of imparting hydrophobicity to a surface of the imprinting mold on which the mold pattern is formed.

[0025] According to an embodiment, the surface of the imprinting mold on which the mold pattern is formed is treated with hexamethyldisilazane (HMDS) to impart hydrophobicity.

[0026] According to an embodiment, a hydrophobicity imparting layer is further provided on the surface of the imprinting mold on which the mold pattern is formed, and the base structure further includes an adhesive layer provided between the base substrate and the coating layer, and the ΔW value derived from the following <Mathematical Formula 1> is 40 mJ / m 2 or more.

[0027] <Mathematical Formula 1>

[0028]

[0029] : Dispersion surface energy, : Polar surface energy, : the base substrate, : the coating layer, : the imprinting mold

[0030] To solve the technical problem, the present application provides a diffractive optical element.

[0031] According to an embodiment, a diffractive optical element includes a diffractive optical layer containing a polymer and nanoparticles, the diffractive optical layer including a base pattern having peaks and valleys alternately and repeatedly arranged in a curved shape, and the diffractive efficiency is 30% or more.

[0032] According to an embodiment, the diffractive optical element has a transmittance of 80% or more for light having a wavelength of 400 nm to 800 nm.

[0033] ​According to an embodiment, the high molecule can include dipentaerythritol penta- / hexa-acrylate or benzyl methacrylate (BzMA).

[0034] According to an embodiment, the nanoparticle can include titanium oxide (TiO2) nanoparticle.

[0035] The diffractive optical element of the embodiment of the present application has a structure in which a sinusoidal pattern is formed on a coating layer having a high refractive index and a transparent property, and a high molecule containing an azobenzene molecule can be used to form the sinusoidal pattern. Thus, the sinusoidal pattern can be formed without a complicated etching process, thereby simplifying the process and reducing the process cost.

[0036] Further, the aforementioned structure (structure in which a sinusoidal pattern is formed on a coating layer having a high refractive index and a transparent property) can have a high transmittance of 80% or more in the entire visible light range (for example, 400 nm to 800 nm wavelength), thereby easily using the entire visible light range and having a theoretically maximum diffraction efficiency in the entire visible light range. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 is a sequence diagram for explaining a method of manufacturing a diffractive optical element of the embodiment of the present application.

[0038] Figure 2 is a sequence diagram for specifically explaining step S100 in the method of manufacturing a diffractive optical element of the embodiment of the present application.

[0039] Figure 3 is a schematic diagram for explaining step S110 in the method of manufacturing a diffractive optical element of the embodiment of the present application.

[0040] Figure 4 is a schematic diagram for explaining step S120 in the method of manufacturing a diffractive optical element of the embodiment of the present application.

[0041] Figure 5 is a schematic diagram for explaining step S130 in the method of manufacturing a diffractive optical element of the embodiment of the present application.

[0042] Figure 6 is a schematic diagram for explaining step S140 in the method of manufacturing a diffractive optical element of the embodiment of the present application.

[0043] Figure 7 is a schematic diagram for explaining step S150 in the method of manufacturing a diffractive optical element of the embodiment of the present application.

[0044] Figure 8 is a sequence diagram for specifically illustrating step S200 in the manufacturing method of the diffractive optical element according to the embodiment of the present application.

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

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

[0047] Figure 11 and Figure 12 is a schematic diagram for illustrating step S300 in the manufacturing method of the diffractive optical element according to the embodiment of the present application.

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

[0049] Figure 14 is a graph for illustrating the results of measuring the transmittance of the inner adhesive layer and the coating layer of the diffractive optical element according to the experimental example of the present application.

[0050] Figure 15 is a graph for illustrating the results of measuring the refractive index of the coating layer of the diffractive optical element according to the experimental example of the present application.

[0051] Figure 16 is a graph for illustrating the theoretical diffraction efficiency of the diffractive optical element according to the experimental example of the present application.

[0052] Figure 17 is a graph for comparing the actual diffraction efficiency with the theoretical diffraction efficiency of the diffractive optical element according to the experimental example of the present application.

[0053] Figure 18 is a graph for comparing the diffraction tendency of the diffractive optical element according to the experimental example of the present application with that of the diffractive optical element according to the comparative example.

[0054] Figure 19 and Figure 20 is a graph for illustrating the influence of the adhesion work value in the manufacturing process of the diffractive optical element according to the experimental example of the present application.

[0055] Figure 21 and Figure 22 is a graph for illustrating the influence of the content of the photocurable polymer and the nanoparticles in the manufacturing process of the diffractive optical element according to the experimental example of the present application. DETAILED DESCRIPTION

[0056] The preferred embodiments of the present application will be described in detail below with reference to the attached drawings. However, the technical spirit of the present application is not limited to the embodiments described herein, but can be embodied in other forms. The embodiments described herein are intended to enable the disclosed contents to be more complete and thorough and to fully convey the spirit of the present application to those skilled in the art to which the present application pertains.

[0057] In the present specification, when a certain element is referred to as being "on" or "under" another element, it can be directly on the other element, or an intervening third element can also be present. Also, in order to effectively describe the technical contents, the thicknesses of the films and regions are exaggerated in the drawings.

[0058] Also, the various embodiments of the present specification use terms such as first, second, third, etc. when describing various elements, but the elements should not be limited to the terms. The purpose of using the terms is only to distinguish the elements from other elements. Thus, an element described as a first element in one embodiment can be described as a second element in another embodiment. The embodiments described and illustrated herein also include complementary embodiments. Also, "and / or" in the present specification is used to include at least one of the elements listed before and after the term.

[0059] In the present specification, unless clearly apparent from the context of the sentence, the singular form also includes the plural form. Also, the terms such as "include" or "have" only designate the presence of the characteristics, numbers, steps, elements, or combinations thereof described in the specification, and should not be construed as precluding the presence or addition of one or more other characteristics, numbers, steps, elements, or combinations thereof. Also, in the present specification, "connected" is used to include indirect connection of a plurality of elements as well as direct connection of a plurality of elements.

[0060] Also, when describing the present application below, detailed descriptions of well-known structures or functions will be omitted if it is deemed that the detailed descriptions unnecessarily obscure the gist of the present application.

[0061] Figure 1 is a sequence diagram for describing a method of manufacturing a diffractive optical element according to an embodiment of the present application.

[0062] Referring to Figure 1 , the method of manufacturing a diffractive optical element according to an embodiment of the present application can include a step of preparing a stamping template (step S100), a step of preparing a substrate structure having a coating layer (step S200), and a step of forming a substrate pattern in the coating layer by applying pressure to the coating layer of the substrate structure with the stamping template (step S300). Each step will be described below.

[0063] Impression mold preparation step (step S100)

[0064] Figure 2 is a sequence diagram for specifically illustrating step S100 in the diffractive optical element manufacturing method according to an embodiment of the present application, Figure 3 is a schematic diagram for illustrating step S110 in the diffractive optical element manufacturing method according to an embodiment of the present application, Figure 4 is a schematic diagram for illustrating step S120 in the diffractive optical element manufacturing method according to an embodiment of the present application, Figure 5 is a schematic diagram for illustrating step S130 in the diffractive optical element manufacturing method according to an embodiment of the present application, Figure 6 is a schematic diagram for illustrating step S140 in the diffractive optical element manufacturing method according to an embodiment of the present application, Figure 7 is a schematic diagram for illustrating step S150 in the diffractive optical element manufacturing method according to an embodiment of the present application.

[0065] Referring to Figure 2 and Figure 3 , a sub-structure 100 having a polymer film 120 containing azobenzene molecules formed on a sub-substrate 110 can be prepared (step S110). According to an embodiment, the sub-substrate 110 can include a glass substrate. According to an embodiment, the polymer film 120 can include poly (disperse red 1 methacrylate) (pDR1m).

[0066] Referring to Figure 2 and Figure 4 , the polymer film 120 can be irradiated with light L to form a polymer pattern 120p having peaks 120a and valleys 120b with a curved shape alternately and repeatedly arranged in at least a part of the region (step S120).

[0067] According to an embodiment, the light L irradiated to the polymer film 120 can include a polarization interference pattern (PIP). More specifically, the light L irradiated to the polymer film 120 can include a polarization interference pattern in a mixed form of right circularly polarized (RCP) and left circularly polarized (LCP).

[0068] More specifically, when the light L including the polarized interference pattern is irradiated to the polymer film 120, the azobenzene molecules are aligned perpendicularly to the polarization direction and are movable along the polarization direction. Therefore, the polymer film 120 can form the polymer pattern 120p having the peaks 120a and the valleys 120b alternately and repeatedly arranged in a sinusoidal shape in at least a part of the region. That is, thanks to the characteristics of the azobenzene molecules, the pattern in the sinusoidal shape can be formed on the polymer film 120 in a simple method of irradiating the light without an etching process.

[0069] Referring to Figure 2 and Figure 5 , the template composition 200 can be coated on the polymer film 120 in a manner of covering the polymer pattern 120p (step S130). According to an embodiment, the template composition 200 can include a thermosetting polymer. For example, the thermosetting polymer can include polydimethylsiloxane (PDMS).

[0070] Referring to Figure 2 and Figure 6 , the template composition 200 can be subjected to a heat treatment to manufacture the imprint template 200 including the template pattern 200p having the inverse pattern of the polymer pattern 120p (step S140). That is, the imprint template 200 can be defined as a state in which the template composition 200 is cured. Also, the imprint template 200 can be prepared in a state of being separated from the substructure 100.

[0071] As described above, the template pattern 200p of the imprint template 200 has the inverse pattern of the polymer pattern 120p, and thus the template pattern 200p can also have a structure in which the peaks 200a and the valleys 200b are alternately and repeatedly arranged. The peaks 200a of the template pattern 200p can correspond to the valleys 120b of the polymer pattern 120p, and the valleys 200b of the template pattern 200p can correspond to the peaks 120a of the polymer pattern 120p.

[0072] Referring to Figure 2 and Figure 7 , the surface of the imprint template 200 on which the template pattern 200p is formed can be imparted with hydrophobicity (step S150). More specifically, the surface of the imprint template 200 on which the template pattern 200p is formed can be subjected to a hexamethyldisilazane treatment to impart hydrophobicity. By this, the surface of the imprint template 200 on which the template pattern 200p is formed can be formed with a hydrophobicity-imparting layer 210.

[0073] With the hydrophobicity-imparting layer 210, the substrate structure 300 can be easily separated from the imprinting template 200 in the later step S300. In contrast, if the hydrophobicity-imparting layer 210 is not provided, the substrate structure 300 can not be properly separated from the imprinting template 200 in the later step S300.

[0074] Substrate structure preparation step (step S200)

[0075] Figure 8 is a sequence diagram for specifically illustrating the step S200 in the method of manufacturing a diffractive optical element according to an embodiment of the present application, Figure 9 is a schematic diagram for illustrating the steps S210 and S220 in the method of manufacturing a diffractive optical element according to an embodiment of the present application, Figure 10 is a schematic diagram for illustrating the steps S230 and S240 in the method of manufacturing a diffractive optical element according to an embodiment of the present application.

[0076] Please refer to Figure 8 and Figure 9 The substrate substrate 310 can be prepared (step S210). According to an embodiment, the substrate substrate 310 can include a glass substrate.

[0077] The substrate substrate 310 can be treated by an oxygen plasma (step S220). In this way, the adhesion between the later bonding layer and the substrate substrate 310 can be further improved. In contrast, if the oxygen plasma treatment step is omitted, the later bonding layer can not be easily formed.

[0078] Please refer to Figure 8 and Figure 10 A bonding layer 320 can be formed on the substrate substrate 310 (step S230). According to an embodiment, the bonding layer 320 can include polymethyl methacrylate (PMMA). The bonding layer 320 can improve the adhesion between the later coating layer and the substrate substrate 310.

[0079] A coating layer 330 can be formed on the bonding layer 320 (step S240). In this way, the substrate structure 300 can be prepared. According to an embodiment, the coating layer 330 can be formed by coating a substrate composition having a high refractive index and transparent properties. In this way, the coating layer 330 also has a high refractive index and transparent properties.

[0080] According to an embodiment, the base composition can include a photocurable polymer, a nanoparticle, a photoinitiator, and a solvent. For example, the photocurable polymer can include dipentaerythritol penta / hexa acrylate or benzyl methacrylate. For example, the nanoparticle can include titanium oxide (TiO2) nanoparticles as metal nanoparticles that can increase a refractive index. For example, the photoinitiator can include Igacure 784, which can be used at a content of 1 wt% with respect to the weight of the entire base composition. For example, the solvent can include propylene glycol monomethylether acetate (PGMEA).

[0081] According to an embodiment, the reliability of the later-described diffractive optical layer can be controlled according to the content of the photocurable polymer and the nanoparticle in the base composition.

[0082] For example, when the photocurable polymer includes dipentaerythritol penta / hexa acrylate and the nanoparticle includes titanium oxide (TiO2) nanoparticles, the content of the nanoparticle:photocurable polymer can be controlled to be more than 70:30 wt% and less than 95:5 wt%. Thereby, the reliability of the later-described diffractive optical layer can be improved. Unlike this, when the content of the nanoparticle:photocurable polymer is controlled to be less than 70:30 wt%, a problem of a decrease in reliability due to aggregation can occur. Also, when the content of the nanoparticle:photocurable polymer is controlled to be more than 95:5 wt%, a problem of a decrease in reliability due to cracking can occur.

[0083] As another example, when the photocurable polymer includes benzyl methacrylate and the nanoparticle includes titanium oxide (TiO2) nanoparticles, the content of the nanoparticle:photocurable polymer can be controlled to be less than 95:5 wt%. Thereby, the reliability of the later-described diffractive optical layer can be improved. Unlike this, when the content of the nanoparticle:photocurable polymer is controlled to be more than 95:5 wt%, a problem of a decrease in reliability due to cracking can occur.

[0084] Substrate pattern formation step (step S300)

[0085] Figure 11 With Figure 12 is a schematic diagram for explaining step S300 in the method of manufacturing a diffractive optical element according to an embodiment of the present application.

[0086] Please refer to Figure 1 , Figure 11 and Figure 12In a state where the pressure (Press) is applied to the coating layer 330 of the base structure 300 by the imprint template 200, the ultraviolet light (UV light) is irradiated to the coating layer 330, and then the imprint template 200 is separated (Pell off) from the base structure 300. By this, the base pattern 330p having the inverse pattern of the template pattern 200p can be formed in the coating layer 330 (Step S300).

[0087] More specifically, in a state where the surface of the imprint template 200 on which the hydrophobicity-imparting layer 210 is formed is in contact with the coating layer 330, the pressure can be applied and the ultraviolet light can be irradiated. By this, the base pattern 330p having the inverse pattern of the template pattern 200p can be formed in the coating layer 330.

[0088] The base pattern 330p has the inverse pattern of the template pattern 200p, and thus the base pattern 330p can also have a structure in which the peaks 330a and the valleys 330b are alternately and repeatedly arranged. The peak 330a of the base pattern 330p can correspond to the valley 200b of the template pattern 200p, and the valley 330b of the base pattern 330p can correspond to the peak 200a of the template pattern 200p. That is, the pattern in the form of a sine wave can be formed in the coating layer 330 having a high refractive index and a transparent characteristic.

[0089] It is difficult to form a pattern in the form of a sine wave in a high-molecular substance having a high refractive index without an etching process. Therefore, the present application provides a method in which a pattern in the form of a sine wave is formed in a high-molecular substance having a high refractive index without an etching process by using a sub-structure using an azobenzene-based high-molecular substance which can easily form a pattern in the form of a sine wave without an etching process although it has a low refractive index, and manufacturing an imprint template using the sub-structure, and then forming a pattern in the form of a sine wave in the high-molecular substance having a high refractive index by the imprint template.

[0090] According to an embodiment, there is a problem in which the coating layer 330 is separated from the adhesive layer 320 together with the imprint template 200 during the separation of the imprint template 200 from the base structure 300. Therefore, in order to solve the aforementioned problem, the work of adhesion value of the base structure 300 and the imprint template 200 can be controlled. More specifically, the ΔW value derived by the following <Mathematical Formula 1> can be controlled to be 40 mJ / m 2 and the like.

[0091] <Mathematical Formula 1>

[0092]

[0093] ( : Dispersion surface energy, : Polar surface energy, : the base substrate, : the coating layer, : the imprinting template

[0094] The coating layer 330 formed with the base pattern 330p can be defined as a diffractive optical layer, and an element including the diffractive optical layer can be defined as a diffractive optical element. The diffractive optical layer has a structure in which the base pattern 330p in a sinusoidal form is formed on the coating layer 330 having a high refractive index and a transparent characteristic, and thus a 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 by the following Mathematical Formula 2. That is, the diffractive optical element including the diffractive optical layer can be calculated in a diffraction efficiency calculation method of a thin sinusoidal phase grating.

[0095] <Mathematical Formula 2>

[0096]

[0097] (DE m : Diffraction efficiency, m: Diffraction order, k0: Wave number, n': Refractive index of diffractive optical layer, n: Air refractive index (=1), h0: Maximum value of modulation height, J: Bessel function

[0098] The Bessel function of Mathematical Formula 2 can be expressed by the following Mathematical Formula 3.

[0099] <Mathematical Formula 3>

[0100]

[0101] With respect to a conventional diffractive optical element manufactured by a method of forming a pattern in a sinusoidal form by irradiating light to a polymer film containing an azobenzene molecule, since the azobenzene molecule has a characteristic (high absorption rate), it cannot be used in the entire visible light range, and the diffraction efficiency is also low.

[0102] However, the diffractive optical element of the embodiment of the present application has a structure in which the base pattern 330p in the form of a sine wave is formed on the coating layer 330 having a high refractive index and a transparent property, and thus can have a high transmittance of 80% or more with respect to the entire visible light range (for example, a wavelength of 400 nm to 800 nm), and thus can be easily used with respect to the entire visible light range and can have a theoretical maximum value with respect to the diffraction efficiency with respect to the entire visible light range. By virtue of this characteristic, the diffractive optical element of the embodiment of the present application can be used in a hologram, a virtual reality (VR) / augmented reality (AR) device, a head up display (HUD).

[0103] The foregoing describes the diffractive optical element of the embodiment of the present application and the manufacturing method thereof. The following describes a specific experimental example of the diffractive optical element of the embodiment of the present application and the manufacturing method thereof and the results of the evaluation of the characteristics.

[0104] Experimental Example 1: Fabrication of a diffractive optical element

[0105] A poly (disperse red 1 methacrylate) (pDR1m) polymer film was coated on an organic substrate, and light including a polarization interference pattern was irradiated to form a polymer pattern in the form of a sine wave. Thereafter, polydimethylsiloxane was coated in a manner of covering the polymer pattern and heat-treated to cure the polydimethylsiloxane, and the cured polydimethylsiloxane was separated by the polymer film, and a stamping mold in which a template pattern in the form of a sine wave was formed on the surface of the cured polydimethylsiloxane was manufactured. Also, the surface of the stamping mold on which the template pattern was formed was subjected to hexamethyldisilazane treatment to impart hydrophobicity.

[0106] A poly (disperse red 1 methacrylate) (pDR1m) polymer film was coated on an organic substrate, and light including a polarization interference pattern was irradiated to form a polymer pattern in the form of a sine wave. Thereafter, polydimethylsiloxane was coated in a manner of covering the polymer pattern and heat-treated to cure the polydimethylsiloxane, and the cured polydimethylsiloxane was separated by the polymer film, and a stamping mold in which a template pattern in the form of a sine wave was formed on the surface of the cured polydimethylsiloxane was manufactured. Also, the surface of the stamping mold on which the template pattern was formed was subjected to hexamethyldisilazane treatment to impart hydrophobicity.

[0107] Finally, the base structure is irradiated with UV light while the base structure is pressed against the stamp pattern of the stamp. Thereafter, the base structure is separated from the stamp. In this way, a diffractive optical element in which a sinusoidal base pattern is formed in the coating layer is manufactured.

[0108] Figure 13 is a photograph of the coating layer of the diffractive optical element of the experimental example of the present application.

[0109] Please refer to Figure 13 (a), which shows a state in which a base pattern of the coating layer is formed with a period of 2700 nm, and Figure 13 (b), which shows a state in which a base pattern of the coating layer is formed with a period of 760 nm. As can be seen from Figure 13 (a) and (b), the base pattern of the diffractive optical element of the experimental example has a sinusoidal shape with high reliability.

[0110] Experimental Example 2: Measurement of transmittance and refractive index of a diffractive optical element

[0111] Figure 14 is a graph for explaining the results of measuring the transmittance of the coating layer and the adhesive layer in the diffractive optical element of the experimental example of the present application.

[0112] Please refer to Figure 14 , in which the transmittance of the coating layer and the adhesive layer (PMMA) of the diffractive optical element of the experimental example was measured. Also, regarding the coating layer, base compositions in which the contents of the nanoparticles (Ti02) and the photocurable polymer (Acrylate) were different were prepared, and the transmittance of the coating layer formed from each base composition was measured. More specifically, the transmittance of the coating layer formed from a base composition in which the contents of the nanoparticles (Ti02) and the photocurable polymer (Acrylate) were 9:1, 8:2, and 7:3, respectively, was measured.

[0113] As can be seen from Figure 14 , it can be confirmed that the coating layer formed from the adhesive layer (PMMA) and the base compositions having contents of 9:1 and 7:3 has a high transmittance of 80% or more in the visible light range (400 nm to 800 nm). Also, it can be confirmed that the coating layer formed from the base composition having a content of 8:2 also has a high transmittance close to 80%.

[0114] Figure 15 is a graph for explaining the results of measuring the refractive index of the coating layer in the diffractive optical element of the experimental example of the present application.

[0115] Please refer to Figure 15, the refractive index of each of a coating (High refractive index resin) formed of a base composition having a content of 9:1 of a nanoparticle (TiO2): a photocurable polymer (Acrylate) and an azopolymer film (Azopolymer) was measured.

[0116] From Figure 15 it is known that the inner coating of the diffractive optical element of the experimental example has a higher refractive index than the azopolymer film. As a result, from Figure 14 and Figure 15 it is known that the diffractive optical element of the experimental example is both transparent and has a high refractive index.

[0117] Experimental Example 3: Diffraction efficiency and diffraction tendency of a diffractive optical element

[0118] Figure 16 is a graph for explaining the theoretical diffraction efficiency of the diffractive optical element of the experimental example.

[0119] Referring to Figure 16 , the theoretical diffraction efficiency of the diffractive optical element of the experimental example is derived by the following <Mathematical Formula 2> and the derived result value is shown.

[0120] <Mathematical Formula 2>

[0121]

[0122] (DE m : Diffraction efficiency, m: diffraction order, k0: wave number, n': refractive index of the diffractive optical layer, n: air refractive index (=1), h0: maximum value of modulation height, J: Bessel function)

[0123] From Figure 16 and <Mathematical Formula 2>, it can be confirmed that the main variables that determine the diffraction efficiency are the refractive index of the diffractive optical layer (coating) and the maximum value of the modulation height. Also, for the value of the refractive index, when n 低 is set to 1.7 and n 高 is set to 2.0, it is known that when the refractive index value is high, the maximum diffraction efficiency can be achieved at a lower modulation height.

[0124] Accordingly, as the present application forms a pattern in the form of a sinusoidal wave in a coating having high transmittance and high refractive index characteristics, it is possible to further increase the refractive index, and thus it is known that the maximum theoretical diffraction efficiency can be achieved.

[0125] Figure 17is a comparison chart of the actual diffraction efficiency and the theoretical diffraction efficiency of the diffractive optical element of the experimental example of the present application.

[0126] Referring to Figure 17 , the actual diffraction efficiency (Exp.) and the theoretical diffraction efficiency (Sim.) of the diffractive optical element of the experimental example are compared and shown. More specifically, Figure 17 (a) of Figure 17 (b) shows the measurement result for 532 nm wavelength light, Figure 17 (c) shows the measurement result for 640 nm wavelength light. Also, Figure 17 (a) to (c) of

[0127] As is apparent from Figure 17 , the diffractive optical elements having different modulation heights all have actual diffraction efficiencies close to the maximum theoretical diffraction efficiency for 488 nm to 640 nm wavelength light.

[0128] Figure 18 is a comparison chart of the diffraction tendency of the diffractive optical element of the experimental example of the present application and the diffractive optical element of the comparative example.

[0129] Referring to Figure 18 (a), for the diffractive optical element of the comparative example, a diffractive optical element was prepared by irradiating a polymer film containing an azobenzene molecule with light containing a polarization interference pattern to form a sinusoidal polymer pattern, and then measuring and showing the diffraction tendency thereof, referring to Figure 18 (b), after the diffractive optical element of the experimental example was prepared, the diffraction tendency thereof was measured and shown.

[0130] As is apparent from Figure 18 (a) and (b), the diffractive optical element of the comparative example could not observe a diffraction signal for light having a wavelength of about 550 nm or less due to the absorption of the azobenzene molecule, in contrast, it was confirmed that the diffractive optical element of the experimental example could clearly observe a diffraction signal for the entire visible light range.

[0131] Experimental Example 4: Confirmation of the effect of adhesion work value

[0132] Figure 19 and Figure 20 is a chart for explaining the effect of the adhesion work value in the manufacturing process of the diffractive optical element of the experimental example of the present application.

[0133] Referring to Figure 19(a) through (d), after preparing four diffractive optical elements manufactured according to the aforementioned experimental example but under different conditions, the coating state of each element was photographed and shown. The four diffractive optical elements manufactured under different conditions are defined as samples 1-1 to 1-4. Figure 19 (a) to (d) are shown after photographing the coating state of samples 1-1 to 1-4 respectively.

[0134] More specifically, Sample 1-1 is a diffractive optical element manufactured using a bonding layer (PMMA) and a hydrophobic imparting layer (HMDS); Sample 1-2 is a diffractive optical element manufactured using a bonding layer (PMMA) but without a hydrophobic imparting layer (HMDS); Sample 1-3 is a diffractive optical element manufactured without a bonding layer (PMMA) but with a hydrophobic imparting layer (HDMS); and Sample 1-4 is a diffractive optical element manufactured without a bonding layer (PMMA) and a hydrophobic imparting layer (HDMS).

[0135] Furthermore, all samples 1-1 to 1-4 used benzyl methacrylate as the photocurable polymer, and the ΔW value was measured for each sample using the following <Mathematical Formula 1>. The manufacturing conditions and ΔW values ​​of the samples 1-1 to 1-4 are summarized in below.

[0136] <Mathematical Formula 1>

[0137]

[0138] ( Surface energy dispersion component. Polar surface energy. The substrate, The coating, (The embossing template)

[0139] Table 1

[0140]

[0141] Depend on Figure 19 As shown in (a) to (d), it can be confirmed that the coating surface of sample 1-1 with a ΔW value of 40 or higher is free of defects. In contrast, the coating surfaces of samples 1-2 to 1-4 with a ΔW value of less than 40 show defects.

[0142] Please refer to Figure 20(a) through (d), after preparing four diffractive optical elements manufactured according to the aforementioned experimental example but under different conditions, the coating state of each element was photographed and shown. The four diffractive optical elements manufactured under different conditions are defined as samples 2-1 to 2-4. Figure 20 (a) to (d) are shown after photographing the coating state of samples 2-1 to 2-4 respectively.

[0143] More specifically, sample 2-1 is a diffractive optical element manufactured using a bonding layer (PMMA) and a hydrophobic imparting layer (HMDS); sample 2-2 is a diffractive optical element manufactured using a bonding layer (PMMA) but without a hydrophobic imparting layer (HMDS); sample 2-3 is a diffractive optical element manufactured without a bonding layer (PMMA) but using a hydrophobic imparting layer (HDMS); and sample 2-4 is a diffractive optical element manufactured without a bonding layer (PMMA) and a hydrophobic imparting layer (HDMS).

[0144] Furthermore, all samples 2-1 to 2-4 used dipentaerythritol penta / hexaacrylate as the photocurable polymer, and the ΔW value was measured for each sample using the aforementioned <Mathematical Formula 1>. The manufacturing conditions and ΔW values ​​of samples 2-1 to 2-4 are summarized in below.

[0145] Table 2

[0146]

[0147] Depend on Figure 20 As can be seen from (a) to (d), it can be confirmed that all samples 2-1 to 2-4 have no defects on the coating surface.

[0148] As demonstrated in Experiment 4, in order to form a highly reliable coating without defects, the ΔW value needs to be 40 mJ / cm². 2 That's all. Furthermore, when using BzMA as a photocurable polymer, it is known that in order to achieve a ΔW value of 40 mJ / cm... 2 The above requires an adhesive layer (PMMA) and a hydrophobic coating layer (HDMS). Conversely, when dipentaerythritol penta / hexaacrylate is used as the photocurable polymer, the ΔW value is 40 mJ / cm², independent of the adhesive layer (PMMA) and the hydrophobic coating layer (HDMS). 2 above.

[0149] Experimental Example 5: Confirmation of the effect of photocurable polymer and nanoparticle content

[0150] Figure 21 and Figure 22This is a graph illustrating the influence of the content of photocurable polymers and nanoparticles during the manufacturing process of the diffractive optical element in the experimental example of the present invention.

[0151] Please refer to Figure 21 (a) through (d), after preparing four diffractive optical elements manufactured according to the aforementioned experimental example but under different conditions, the coating state of each element was photographed and shown. The four diffractive optical elements manufactured under different conditions are defined as samples 3-1 to 3-4. Figure 21 (a) to (d) are shown after photographing the coating state of samples 3-1 to 3-4 respectively.

[0152] More specifically, samples 3-1 to 3-4 were manufactured under the following conditions: the contents of the photocurable polymer and nanoparticles in the substrate composition used to form the coating were different, and dipentaerythritol penta / hexaacrylate was used as the photocurable polymer.

[0153] Furthermore, sample 3-1 was a diffractive optical element manufactured under the condition that the content of nanoparticles:photocurable polymer was 70:30wt%, sample 3-2 was a diffractive optical element manufactured under the condition that the content of nanoparticles:photocurable polymer was 80:20wt%, sample 3-3 was a diffractive optical element manufactured under the condition that the content of nanoparticles:photocurable polymer was 90:10wt%, and sample 3-4 was a diffractive optical element manufactured under the condition that the content of nanoparticles:photocurable polymer was 95:5wt%.

[0154] Table 3

[0155]

[0156] Depend on Figure 21 As shown in (b) and (c), the coatings of samples 3-2 and 3-3 have no defects (agglomeration or cracking). Conversely, from Figure 21 As shown in (a) and (d), the coating of sample 3-1 showed agglomeration, and the coating of sample 3-4 showed cracking.

[0157] That is, in the manufacturing process of the diffractive optical element of the present invention, when the photocurable polymer used to form the coating is dipentaerythritol penta / hexaacrylate, it is known that in order to form a highly reliable coating, the content of nanoparticles:photocurable polymer needs to be controlled to be more than 70:30wt% and less than 95:5wt%.

[0158] Please refer to Figure 22(a) through (d), after preparing four diffractive optical elements manufactured according to the aforementioned experimental example but under different conditions, the coating state of each element was photographed and shown. The four diffractive optical elements manufactured under different conditions are defined as samples 4-1 to 4-4. Figure 22 (a) to (d) are shown after photographing the coating state of samples 4-1 to 4-4 respectively.

[0159] More specifically, samples 4-1 to 4-4 were manufactured under the following conditions: the contents of the photocurable polymer and nanoparticles in the substrate composition used to form the coating were different, and benzyl methacrylate was used as the photocurable polymer.

[0160] Furthermore, sample 4-1 was a diffractive optical element manufactured under the condition that the content of nanoparticles:photocurable polymer was 70:30wt%, sample 4-2 was a diffractive optical element manufactured under the condition that the content of nanoparticles:photocurable polymer was 80:20wt%, sample 4-3 was a diffractive optical element manufactured under the condition that the content of nanoparticles:photocurable polymer was 90:10wt%, and sample 4-4 was a diffractive optical element manufactured under the condition that the content of nanoparticles:photocurable polymer was 95:5wt%.

[0161] Table 4

[0162]

[0163] Depend on Figure 22 From (a) to (c), it can be seen that the coatings of samples 4-1 to 4-3 have no defects (cracking). Conversely, from Figure 22 As can be seen from (d), it can be confirmed that the coating of sample 4-4 has cracks.

[0164] That is, in the manufacturing process of the diffractive optical element of the present invention, when benzyl methacrylate is used as the photocurable polymer for forming the coating, it is known that in order to form a highly reliable coating, the content of nanoparticles:photocurable polymer needs to be controlled to be less than 95:5wt.

[0165] The present invention has been described in detail above using preferred embodiments. However, the scope of the present invention is not limited to the specific embodiments and should be defined according to the claims. Moreover, those skilled in the art will recognize that various modifications and variations can be made without departing from the scope of the present invention.

[0166] Industrial applications

[0167] This invention can be used in the semiconductor field.

Claims

1. A method for manufacturing a diffractive optical element, characterized in that, Includes the following steps; Imprint template preparation step, wherein the imprint template includes a template pattern with alternating and repeating peaks and valleys having a curved shape in at least a portion of the area; The substrate structure preparation step involves forming a coating comprising a photocurable polymer and nanoparticles on a substrate; and... The substrate patterning step involves applying pressure to the coating of the substrate structure using the embossing template to form a substrate pattern having a reverse pattern of the template pattern on the coating.

2. The method for manufacturing a diffractive optical element according to claim 1, characterized in that, The embossing template preparation steps include the following steps; The substructure preparation step involves forming a polymer film containing azobenzene molecules on a sub-substrate. The polymer patterning step involves irradiating the polymer film with light to form a polymer pattern with alternating and repeating peaks and valleys in at least a portion of the region; The template composition coating step involves coating the template composition comprising a thermosetting polymer onto the polymer film in a manner that covers the polymer pattern; and, The embossing template manufacturing step involves heat-treating the template composition to manufacture the embossing template comprising the template pattern having a reverse pattern of the polymer pattern.

3. The method for manufacturing a diffractive optical element according to claim 1, characterized in that, In the base pattern, peaks and valleys with curved shapes are arranged alternately and repeatedly. The peaks of the base pattern correspond to the valleys of the template pattern, and the valleys of the base pattern correspond to the peaks of the template pattern.

4. The method for manufacturing a diffractive optical element according to claim 1, characterized in that, The preparation steps for the substrate structure include the following steps; Substrate preparation steps; The step of forming an adhesive layer on the substrate; and, The step of forming the coating on the adhesive layer.

5. The method for manufacturing a diffractive optical element according to claim 4, characterized in that, The adhesive layer comprises polymethyl methacrylate.

6. The method for manufacturing a diffractive optical element according to claim 4, characterized in that, After the substrate preparation step and before the adhesive layer formation step, the following steps are also included: The step of treating the substrate with oxygen plasma.

7. The method for manufacturing a diffractive optical element according to claim 1, characterized in that, After the embossing template preparation step and before the substrate pattern formation step, the following steps are also included: The step of imparting hydrophobicity to the surface of the embossing template on which the template pattern is formed.

8. The method for manufacturing a diffractive optical element according to claim 7, characterized in that, The surface of the embossing template on which the template pattern is formed is treated with hexamethyldisilazane to impart hydrophobicity.

9. The method for manufacturing a diffractive optical element according to claim 1, characterized in that, A hydrophobic layer is further disposed on the surface of the embossing stencil on which the stencil pattern is formed, and the substrate structure further includes an adhesive layer disposed between the substrate and the coating. The value of ΔW derived from the following <Mathematical Formula 1> is 40 mJ / m 2 above, <Mathematical Formula 1> Surface energy dispersion component Surface energy polar component The substrate, The coating, The embossing template.

10. A diffractive optical element comprising a diffractive optical layer, the diffractive optical layer comprising polymers and nanoparticles, The diffractive optical layer includes a substrate pattern with alternating and repeating peaks and valleys in a curved shape. The diffraction efficiency is over 30%.

11. The diffractive optical element according to claim 10, characterized in that, It has a transmittance of over 80% for light with wavelengths from 400nm to 800nm.

12. The diffractive optical element according to claim 10, characterized in that, The polymer comprises dipentaerythritol penta / hexaacrylate or benzyl methacrylate.

13. The diffractive optical element according to claim 10, characterized in that, The nanoparticles include titanium oxide nanoparticles.

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