Holographic optical element manufacturing device for improving diffraction efficiency and method thereof

Abstract

The present invention is, A prism comprising a light incident surface into which light is incident and a light reflecting surface inclined at a predetermined angle from the light incident surface to reflect light; A light source configured to irradiate light toward a light incidence surface; comprising The light incident slope is, A diffractive optical element manufacturing apparatus characterized by having a first light incident surface formed by attaching a photoreactive material to form an interface with a prism, through which light irradiated from a light source passes through the photoreactive material and enters the prism, and a second light incident surface formed by not attaching a photoreactive material and through which light irradiated from a light source passes directly into the prism. A method for manufacturing a diffraction optical element is provided.

Description

Technology Field

[0001] The present invention relates to an apparatus and method for manufacturing a diffractive optical element with improved diffraction efficiency, and more specifically, to an apparatus and method for manufacturing a diffractive optical element with improved diffraction efficiency through the interference of reflected light directly incident on a prism and reflected from a light beam surface and incident on a photoreactive material. Background Technology

[0003] Diffractive optical elements, such as holographic optical elements, were fabricated by interfering two laser beams having the same wavelength and coherent length in a photoreactive material.

[0004] When manufacturing diffractive optical elements using two laser beams, problems with the reproducibility of the manufactured elements frequently occurred due to significant influence from external environmental factors such as vibration or air flow.

[0005] As an alternative, a technology was developed to replicate diffractive optical elements using a single laser beam after fabricating a master in advance, leading to the mass production of diffractive optical elements.

[0006] A single laser beam is diffracted by the master to generate regenerated light, and the original laser beam and the regenerated light from the master interfere in a photoreactive material to replicate a diffractive optical element identical to the master.

[0007] In particular, when replicating a diffractive optical element using a master, it is common for laser light to pass through a photoreactive material as it is diffracted from the master to generate regenerated light; consequently, a problem arises in which a portion of the laser light is absorbed by the initiator of the photoreactive material. When laser light is partially absorbed, it results in a deterioration of optical properties, specifically diffraction efficiency.

[0008] Referring to Fig. 8, when an interference pattern is formed on a photoreactive material using a master, the intensity of the reflected light reflected from the master and incident on the photoreactive material decreases as it passes through the photoreactive material; therefore, compared to the irradiated light incident into the photoreactive material, it can be observed that the Beam Ratio (BR) of the two laser light intensities decreases as the distance from the master increases. The diffraction efficiency is affected by the BR value of the photoreactive material.

[0009] The diffraction efficiency of a diffractive optical element is a factor in evaluating holographic image quality; when diffraction efficiency is low, the resolution decreases when reproducing virtual images. Consequently, there is a problem in that the quality of the diffractive optical element also deteriorates. The problem to be solved

[0011] The technical problem to be solved by the present invention is to provide an apparatus and method for manufacturing a diffractive optical element with improved diffraction efficiency, which is produced through the interference of reflected light directly incident on a prism and reflected from a light beam surface and incident on a photoreactive material.

[0012] However, the problems that the present invention aims to solve are not limited to those mentioned above, and other unmentioned problems will be clearly understood by those skilled in the art from the description below. means of solving the problem

[0014] The present invention, according to one embodiment, comprises a prism including a light incident surface into which light is incident and a light reflecting surface inclined at a predetermined angle from the light incident surface to reflect light, and a light source configured to irradiate light toward the light incident surface. The light incident surface may be characterized by being formed into a first light incident surface to which a photoreactive material is attached to form an interface with the prism so that light irradiated from the light source is incident on the prism through the photoreactive material, and a second light incident surface to which light irradiated from the light source is not attached and is incident directly on the prism.

[0015] In addition, the irradiated light, which is irradiated from the light source and refracted at the interface between air and the photoreactive material and incident into the photoreactive material, and the reflected light, which is irradiated from the light source, passes through the second light incident surface of the prism, is reflected at the light reflecting surface, and is refracted between the prism and the first light incident surface and incident into the photoreactive material, can interfere to form interference fringes in the photoreactive material.

[0016] In addition, the light source may be characterized by being located on the light incidence surface of the prism.

[0017] In addition, the light source may be characterized as being a single light source.

[0018] In addition, the light-reflecting surface may include a mirror-coated surface or a mirror-deposited surface.

[0019] Additionally, the photoreactive material is formed in a sheet shape having a predetermined width direction size and extending in the length direction, and includes a conveying mechanism for conveying the sheet of the photoreactive material in the length direction so that the photoreactive material is attached to the first light incident surface of the prism, and the first light incident surface of the prism may be formed with a size corresponding to the width direction size of the photoreactive material.

[0020] In addition, the prism can be in the shape of a triangular prism.

[0021] A method for manufacturing a diffracting optical element according to one embodiment of the present invention may include the steps of: preparing a prism comprising a light incident surface into which light is incident and a light reflecting surface inclined at a predetermined angle from the light incident surface to reflect light; attaching a photoreactive material to record an interference pattern to a first light incident surface, which is part of the light incident surface of the prism; and recording an interference pattern by irradiating light from a light source toward a second light incident surface of the prism, which is one of the light incident surfaces to which the photoreactive material is not attached.

[0022] Additionally, in the step of recording the interference pattern, an irradiated light that is irradiated from the light source, refracted at the interface between air and the photoreactive material, and incident into the photoreactive material, and a reflected light that is irradiated from the light source, passes through the second light incident surface of the prism, is reflected at the light reflecting surface, and is refracted between the prism and the first light incident surface and incident into the photoreactive material, may interfere to form an interference pattern in the photoreactive material.

[0023] In addition, the photoreactive material may be formed in a sheet shape having a predetermined width direction size and extending in the length direction, and the method may further include a step of transporting the sheet of the photoreactive material in the length direction so that the photoreactive material is attached to the first light incident surface of the prism.

[0024] In addition, the above diffractive optical element may be a holographic optical element.

[0025] In addition, the diffractive optical element can be manufactured by at least one of the above manufacturing methods. Effects of the invention

[0027] According to the present invention, when irradiated light is directly transmitted and reflected by a prism without passing through a photoreactive material to form reflected light, since there is no absorption of light by the initiator, the diffraction efficiency of the interference fringe formed on the photoreactive material can be increased.

[0028] In addition, there is no need to continuously produce consumable masters, and it is possible to prevent defects in the master from being replicated in the diffractive optical element.

[0029] In addition, the diffractive optical element manufacturing apparatus according to the present invention can be implemented as a roll-to-roll device, thereby enabling mass production of diffractive optical elements with uniform performance.

[0030] In addition, the prism of the diffractive optical element manufacturing apparatus according to the present invention can be manufactured over a large area, thereby improving chamfering efficiency during mass production of diffractive optical elements.

[0031] The effects of the present invention are not limited to those described above, and unmentioned effects will be clearly understood by those skilled in the art from the present specification and the accompanying drawings. Brief explanation of the drawing

[0033] FIG. 1 is a cross-sectional view of a diffractive optical element manufactured by irradiating light and reflected light in a diffractive optical element manufacturing apparatus according to one embodiment of the present invention. FIG. 2 is a schematic diagram showing a diffraction optical element manufacturing apparatus according to one embodiment of the present invention. FIG. 3 is a block diagram showing a method for manufacturing a diffractive optical element according to one embodiment of the present invention. FIG. 4 is a cross-sectional view showing constant values ​​for calculating the laser light intensity of a diffractive optical element manufacturing apparatus according to one embodiment of the present invention. FIG. 5a is a graph showing the transmittance of a photoreactive material of a diffracting optical element calculated according to one embodiment of the present invention. FIG. 5b is a graph showing the diffraction efficiency according to the average refractive index modulation of a diffractive optical element calculated according to one embodiment of the present invention. FIG. 6a is a graph showing the transmittance according to wavelength of a diffractive optical element manufactured according to one embodiment of the present invention. FIG. 6b is a graph showing the reflectance according to wavelength of a diffractive optical element manufactured according to one embodiment of the present invention. FIG. 7a is a graph showing the transmittance according to wavelength of a diffractive optical element manufactured according to a comparative embodiment of the present invention. FIG. 7b is a graph showing the reflectance according to wavelength of a diffractive optical element manufactured according to a comparative embodiment of the present invention. Figure 8 is a schematic diagram showing the ratio of the intensity of the incident light and the reflected light when recording interference patterns on a photoreactive material using a master of the prior art. Specific details for implementing the invention

[0034] The present invention will become clear from the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below but may be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims. Meanwhile, the terms used in this specification are for describing the embodiments and are not intended to limit the present invention.

[0035] Throughout this specification, the singular form includes the plural form unless specifically stated otherwise in the text.

[0036] Throughout this specification, the terms “comprises” and / or “comprising” as used mean that the mentioned components, steps, actions and / or elements do not exclude the presence or addition of one or more other components, steps, actions and / or elements, and that, unless specifically stated otherwise, they do not exclude other components but may include additional components.

[0037] Throughout this specification, terms such as "first," "second," etc., may be used to describe various components, but the components should not be limited by these terms. The terms are used solely for the purpose of distinguishing one component from another.

[0038] Throughout this specification, the term "diffracting optical element" refers to an optical element equipped with a diffraction grating pattern in which high-refractive index portions and low-refractive index portions are alternately arranged along a predetermined direction, and light reaching the diffracting optical element may be diffracted and its optical path may be changed.

[0039] Throughout this specification, the term "holographic diffractive optical element" refers to an optical element having a holographic grating pattern in which high-refractive index and low-refractive index regions are alternately arranged along a predetermined direction, and light reaching the holographic diffractive optical element may be diffracted to change the optical path. Such a holographic grating pattern may be recorded by interference of multiple lasers on a photosensitive material such as a photopolymer.

[0041] The present invention will be described in more detail below.

[0042] Referring to FIG. 1, a diffractive optical element manufacturing apparatus (1) according to one embodiment of the present invention can manufacture a diffractive optical element by irradiating light onto a photoreactive material (2) and interfering to record an interference pattern.

[0043] A diffractive optical element manufacturing apparatus (1) according to one embodiment of the present invention may be formed by including a prism (10) comprising a light incident surface (11) into which light is incident and a light reflecting surface (12) that reflects light at a predetermined angle from the light incident surface (11), and a light source (20) configured to irradiate light toward the light incident surface (11).

[0044] In particular, the light incident surface (11) of the prism (10) can be formed into a first light incident surface (11a) to which a photoreactive material (2) is attached to form an interface with the prism (10) so that light irradiated from the light source (20) is incident on the prism (10) through the photoreactive material (2), and a second light incident surface (11b) to which light irradiated from the light source (20) is not attached and is incident directly on the prism (10). That is, unlike the first light incident surface (11a), the second light incident surface (11b) does not have a photoreactive material (2) attached to it, so light irradiated from the light source (20) can be incident directly on the prism (10).

[0045] As illustrated in FIG. 1, a diffractive optical element manufacturing apparatus (1) according to one embodiment of the present invention can manufacture a diffractive optical element by recording an interference pattern on the photoreactive material (2) through interference between the irradiated light (La) which is irradiated from a light source (20), refracted at the interface between air and the photoreactive material (2), and incident into the photoreactive material (2), and the reflected light (Lb) which is irradiated from the light source (20), passes through the second light incident surface (11b) of the prism (10), is reflected at the light reflection surface (12), and is refracted at the prism (10) and the first light incident surface (11a).

[0046] In the conventional method for manufacturing a reflective diffractive optical element, the reflected light (Lb) is formed when the irradiating light (La) passes through the photoreactive material (2), is reflected from the light-reflecting surface (12) of the prism (10), and is then refracted at the interface between the prism (10) and the photoreactive material (2) before being incident on the photoreactive material (2). In this case, since the light is partially absorbed by the initiator of the photoreactive material (2), there was a problem in that the diffraction efficiency of the interference pattern formed on the photoreactive material (2) was poor.

[0047] Meanwhile, when the irradiating light (La) is not transmitted through the photoreactive material (2) but is directly transmitted and reflected by the prism (10) to form reflected light (Lb), some of the light is not absorbed by the initiator, so the diffraction efficiency of the interference pattern formed on the photoreactive material (2) can be increased.

[0048] In addition, a diffractive optical element manufacturing device according to one embodiment of the present invention can manufacture a diffractive optical element by passing only one light source (20) through a prism (10) without a master.

[0049] In addition, the light source (20) of the diffracting optical element manufacturing device according to one embodiment of the present invention may allow light irradiated from the light source (20) located on the light incident surface (11) side of the prism (10) to pass through the second light incident surface (11b) of the prism (10) and be reflected on the light reflection surface (12).

[0050] According to one embodiment of the present invention, the light-reflecting surface (12) of the prism (10) is configured to reflect light incident into the prism (10) by passing through the light-incident surface (11). A mirror-coated surface or a mirror-deposited surface may be formed through coating or deposition, but is not limited thereto. It is also possible to implement the light-reflecting surface (12) by attaching a reflective optical element to the prism (10). Any configuration capable of reflecting light that is incident into the prism (10) and reaches the light-reflecting surface (12) is sufficient.

[0051] As illustrated in FIG. 2, a prism (10) for manufacturing a diffracting optical element according to one embodiment of the present invention may have a triangular prism shape, and a photoreactive material (2) may be partially attached to one side of the triangular prism to form a light incident surface (11) into which light from a light source (20) is incident, and the other side adjacent thereto may form a light reflecting surface (12). However, it is not limited thereto, and a configuration is possible that includes a light reflecting surface (12) adjacent thereto while satisfying a predetermined angle relationship with the light incident surface (11).

[0052] A prism (10) for manufacturing a diffractive optical element according to one embodiment of the present invention may be made of quartz, BK7, or PMMA (Poly(methyl methacrylate)), but is not limited thereto.

[0053] In a diffraction optical element manufacturing apparatus (1) according to one embodiment of the present invention, the light source (20) may be a laser light source (20) and may be configured to irradiate a single light having a predetermined wavelength and coherent length.

[0054] According to one embodiment of the present invention, the photoreactive material (2) may include a photosensitive material and may be formed in various shapes, such as a sheet shape or a roll shape, having a predetermined width direction and / or length direction size. Various types of photosensitive materials that can be used in the manufacture of diffractive optical elements including holographic optical elements are known, and such materials may be used in the present invention without limitation.

[0055] According to one embodiment of the present invention, the photosensitive material may be a photopolymer, photoresist, silver halide emulsion, dichromated gelatin, photographic emulsion, photothermoplastic, or photorefractive material. Interference patterns can be easily recorded using the above-mentioned photosensitive material.

[0056] A diffractive optical element manufactured according to one embodiment of the present invention may be a holographic optical element.

[0057] A diffractive optical element manufacturing apparatus (1) according to another embodiment of the present invention may be configured as a roll-to-roll device to mass-produce diffractive optical elements.

[0058] Let's look at this in more detail with reference to Fig. 2.

[0059] In a diffractive optical element manufacturing apparatus (1) according to another embodiment of the present invention, the photoreactive material (2) may be formed in a sheet shape that has a predetermined width direction size and extends in the length direction. At this time, the width direction size of the photoreactive material (2) may be configured to be 500 mm or more, but is not limited thereto and can be set in various ways to match the size of the diffractive optical element to be produced.

[0060] The sheet-shaped photoreactive material (2) can be supplied by a supply roll (40) wound in a roll shape, and the sheet-shaped photoreactive material (2), which is manufactured into a diffraction optical element with an interference pattern recorded thereon, can also be wound by a recovery roll (50) and recovered in a roll form.

[0061] When a sheet-shaped photoreactive material (2) is supplied to a diffraction optical element manufacturing device (1), a transfer mechanism (30) for transferring the photoreactive material (2) so that the photoreactive material (2) is attached to the first light incident surface (11a) of the prism (10) may be installed, and the transfer mechanism (30) may be configured in the form of a transfer roller that continuously transfers the sheet of photoreactive material (2).

[0062] In addition, according to another embodiment of the present invention, the first light incident surface (11a) of the prism (10) for manufacturing a diffracting optical element can be configured to correspond to the width-direction size of the sheet-shaped photoreactive material (2). That is, the irradiated light (La) incident into the photoreactive material (2) attached to the first light incident surface (11a) of the light incident surface (11) of the prism (10) and the reflected light (Lb) reflected from the prism (10) through the second light incident surface (11b) can be configured to interfere with each other.

[0063] Due to laser and optical limitations, masters in conventional technology could not be manufactured over a large area; therefore, for mass production, it was necessary to attach multiple masters to a substrate in a tile-like manner. However, attaching multiple masters in this tile-like manner resulted in a problem of reduced chamfering efficiency during the production of diffractive optical elements.

[0064] In contrast, the prism (10) for manufacturing a diffracting optical element according to another embodiment of the present invention can be manufactured with a side length of 500 mm or more, so the reduction in chamfering efficiency when attached in a tile-like manner as in the prior art can be prevented.

[0065] In addition, in the conventional method for manufacturing a reflective diffraction optical element, the reflected light (Lb) is formed when the irradiating light (La) passes through the photoreactive material (2), and since the light is partially absorbed by the initiator of the photoreactive material (2), there was a problem in that the diffraction efficiency of the interference pattern formed in the photoreactive material (2) was poor.

[0066] Meanwhile, when the irradiating light (La) is not transmitted through the photoreactive material (2) but is directly transmitted through the prism (10) and reflected to form reflected light (Lb), the diffraction efficiency of the interference pattern formed on the photoreactive material (2) can be increased.

[0068] Referring to FIG. 3, a method for manufacturing a diffracting optical element according to another embodiment of the present invention comprises the steps of: preparing a prism (10) comprising a light incident surface (11) into which light is incident and a light reflecting surface (12) that reflects light at a predetermined angle from the light incident surface (11); attaching a photoreactive material (2) to record an interference pattern to a first light incident surface (11a) which is part of the light incident surface (11) of the prism (10) (S20); and recording an interference pattern by irradiating light from a light source (20) toward a second light incident surface (11b) of the light incident surface (11) of the prism (10) to which the photoreactive material (2) is not attached (S30).

[0069] In the step (S10) of preparing the prism (10), the prism (10) can be configured in the same way as the configuration of the diffractive optical element manufacturing device (1) according to the preceding embodiments.

[0070] In the step (S20) of attaching the photoreactive material (2) to the first light incident surface (11a), the photoreactive material (2) can be attached to a part of the light incident surface (11) so that the reflected light (Lb) formed from the light reflection surface (12) of the prism (10) among the light irradiated from the light source (20) can be formed without passing through the photoreactive material (2).

[0071] In the step (S30) of recording interference patterns after attaching the photoreactive material (2) to the prism (10), an irradiating light (La) that is irradiated from a light source (20), refracted at the interface between air and the photoreactive material (2), and incident into the photoreactive material (2), and a reflected light (Lb) that is irradiated from the light source (20), passes through the second light incident surface (11b) of the prism (10), is reflected at the light reflection surface (12), refracted at the prism (10) and the first light incident surface (11a), and incident into the photoreactive material (2), can form an interference pattern on the photoreactive material (2) by interference.

[0072] According to another embodiment of the present invention, a method for manufacturing a diffracting optical element may be configured to continuously supply the photoreactive material (2) and manufacture the diffracting optical element by further including a step (S40) of transporting the photoreactive material (2) in the longitudinal direction so that the photoreactive material (2) is attached to the first light incident surface (11a) of the prism (10). In this case, the photoreactive material (2) may be configured in a sheet shape having a predetermined width direction size and extending in the longitudinal direction so that the sheet of photoreactive material (2) can be continuously transported.

[0073] According to another embodiment of the present invention, a diffractive optical element is provided by at least one of the methods for manufacturing a diffractive optical element according to the preceding embodiments. When a diffractive optical element is manufactured by the method according to the preceding embodiments, the diffraction efficiency is improved compared to the prior art.

[0074] The diffraction efficiency of the diffraction optical element is influenced by the ratio of the intensity of incident light and reflected light (Lb) irradiated onto the photoreactive material (2) (Beam Ratio: BR). This is the ratio of the intensity of the diffracted or reflected light (Lb) to the intensity of the incident light, and the lower the absorption by the initiator as the diffracted or reflected light (Lb) passes through the photoreactive material (2), the higher the diffraction efficiency will be.

[0075] The light intensity follows Equation 1 according to Lambert-Beer's Law with reference to Fig. 4.

[0076] [Mathematical Formula 1]

[0077]

[0078]

[0079]

[0080] Here, is the intensity of incident light, is the intensity of the diffracted light or reflected light (Lb), is the thickness direction position of the photoreactive material (2), is the absorption rate of the photoreactive substance (2), The thickness of the photoreactive material (2), The transmittance of the photoreactive material (2), Angle of incidence, θ is the light diffraction angle of the master or the light reflection angle of the prism (10), DE% is the diffraction efficiency of the master, and R% is the reflectance of the mirror.

[0081] The ratio of the intensities of the two lights (Beam Ratio; BR) can be derived according to Equation 2 using the intensity values ​​of the incident light and the diffracted or reflected light (Lb), and the resulting mean diffraction efficiency; ) can be calculated according to mathematical formula 3.

[0083] [Mathematical Formula 2]

[0084]

[0085] [Mathematical Formula 3]

[0086]

[0087]

[0088]

[0089]

[0090] Here, is visibility, Mean Visibility, Mean refractive index modulation, is refractive index modulation, is the wavelength of light, is the angle difference between the incident light and the refracted light, is the angle of incidence of the incident light, is the grating spacing of the diffractive optical element.

[0092] Using the above mathematical formulas 1 to 3, the diffraction efficiency of a diffractive optical element fabricated under the following conditions is predicted.

[0093] The light source (20) uses a laser light source (20) with a wavelength of 660 nm, and the irradiation angle toward the photoreactive material (2) is set to 35°, and the diffraction angle at the photoreactive material (2) is set to 65°. Referring to FIG. 5a, the photoreactive material (2) has a transmittance of 24% at a wavelength of 660 nm and a thickness of 8.5 , it is a photopolymer (PP) with a refractive index modulation of 0.05 and a refractive index of 1.5. In the example, the reflectance of the prism (10) mirror is set to 95% at a wavelength of 660 nm, and the master diffraction efficiency of the comparative example is set to 91% at a wavelength of 660 nm.

[0094] FIG. 5b is a graph showing the diffraction efficiency according to average refractive index modulation for the result calculated by the mathematical formulas 1 to 3 for the value set according to one embodiment of the present invention. When using the prism (10) mirror of the embodiment, the average refractive index modulation is 0.037, and when using the master as a comparison example The value is 0.027. Accordingly, the diffraction efficiency of the replicated diffraction optical element is 57.0% in the example and 39.2% in the comparative example, showing a difference of about 17%, and it is predicted that a diffraction optical element with high diffraction efficiency can be fabricated when using the example.

[0095] This can be determined through the following examples of actual production and comparisons.

[0097] Example of implementation

[0098] In a diffractive optical element manufacturing apparatus (1) according to one embodiment of the present invention, the photoreactive material (2) has a transmittance of 24% at 660 nm and a thickness of 8.5 , it is a photopolymer (PP) with a refractive index modulation of 0.05 and a refractive index of 1.5. A laser light source (20) with a wavelength of 660 nm is used as the light source (20), and a diffraction optical element is fabricated by interfering the irradiated light (La) and the reflected light (Lb) by setting the irradiation angle to the photoreactive material (2) to 35° and the diffraction angle in the photoreactive material (2) to 65°.

[0099] The optical properties of the fabricated diffractive optical element are shown in Figs. 6a and 6b.

[0100] FIGS. 6a and 6b are drawings showing the efficiency of a diffractive optical element manufactured according to an embodiment of the present invention, FIG. 5(a) is a graph showing the transmittance according to wavelength of a diffractive optical element manufactured according to an embodiment of the present invention, and FIG. 5(b) is a graph showing the reflectance according to wavelength of a diffractive optical element manufactured according to an embodiment of the present invention.

[0101] According to FIGS. 6a and 6b, the diffracting optical element according to one embodiment of the present invention diffracts at 50° when incident at 0°, has a peak wavelength of 987 nm, and exhibits a diffraction efficiency of approximately 53%. This is similar to the diffraction efficiency of 57% predicted through the prism (10) mirror of the embodiment.

[0103] Comparison Example

[0104] A diffractive optical element manufacturing apparatus (1) according to a comparative embodiment of the present invention was prepared. Unlike the diffractive optical element manufacturing apparatus (1) according to one embodiment of the present invention, a master according to the prior art was manufactured instead of a prism (10). The components other than the master were configured in the same way as in one embodiment of the present invention.

[0105] More specifically, the master uses a photopolymer, and the light source (20) uses a laser light source (20) with a wavelength of 660 nm. After attaching the photoreactive material (2) to the surface of the photoreactive material (2) on the master plate, an irradiating light (La) is incident from the light source (20) at an irradiating angle of 35°, and then the incident angle of the diffracted light diffracted from the master is set to 65° to interfere the irradiating light (La) and the diffracted light, thereby fabricating a replica diffracting optical element identical to the master in the photoreactive material (2).

[0106] The optical characteristics of the diffractive optical element fabricated according to the comparative example are shown in FIGS. 7a and FIGS. 7b.

[0107] FIGS. 7a and 7b are drawings showing the efficiency of a diffractive optical element manufactured according to a comparative embodiment of the present invention, FIG. 7a is a graph showing the transmittance according to wavelength of a diffractive optical element manufactured according to a comparative embodiment of the present invention, and FIG. 7b is a graph showing the reflectance according to wavelength of a diffractive optical element manufactured according to a comparative embodiment of the present invention.

[0108] According to FIGS. 7a and 7b, the diffracting optical element according to the comparative embodiment of the present invention diffracts at 50° when incident at 0°, has a peak wavelength of 987 nm, and exhibits a diffraction efficiency of approximately 37%. This is similar to the diffraction efficiency of 39.2% of the comparative example predicted through the master.

[0110] Therefore, by comparing the measurement data according to one embodiment of the present invention with the measurement data according to a comparative embodiment, it can be determined that the embodiment can manufacture a diffraction optical element having a diffraction efficiency approximately 16% higher than that of the comparative example.

[0112] Although the present invention has been described above by limited embodiments, the present invention is not limited thereto, and it is obvious that various modifications and variations are possible within the scope of the technical spirit of the present invention and the equivalent scope of the claims described below by those skilled in the art to which the present invention belongs. Explanation of the symbols

[0114] 1: Diffractive optical element manufacturing device 2: Photoreactive substances 10: Prism 11: Light incident slope 11a: First light incidence slope 11b: Second light incidence slope 12: Light reflector 20: Light source 30: Transfer mechanism 40: Supply Roll 50: Recovery Roll La: Investigator Lb: Reflected light

Claims

Claim 1 A diffractive optical element manufacturing apparatus comprising: a prism including a light incident surface into which light is incident and a light reflecting surface inclined at a predetermined angle from the light incident surface to reflect light; and a light source configured to irradiate light toward the light incident surface; wherein the light incident surface is formed into a first light incident surface to which a photoreactive material is attached to form an interface with the prism so that light irradiated from the light source is incident on the prism through the photoreactive material, and a second light incident surface to which light irradiated from the light source is not attached and is incident directly on the prism, wherein the irradiated light irradiated from the light source is refracted at the interface between air and the photoreactive material and incident into the photoreactive material, and the reflected light irradiated from the light source passes through the second light incident surface of the prism, is reflected from the light reflecting surface, is refracted between the prism and the first light incident surface and incident into the photoreactive material, and the irradiated light interferes to form an interference pattern on the photoreactive material. Claim 2 delete Claim 3 A diffractive optical element manufacturing apparatus according to claim 1, characterized in that the light source is located on the side of the light incident surface of the prism. Claim 4 An apparatus for manufacturing a diffractive optical element according to claim 1, characterized in that the light source is a single light source. Claim 5 An apparatus for manufacturing a diffractive optical element according to claim 1, wherein the light-reflecting surface comprises a mirror-coated surface or a mirror-deposited surface. Claim 6 A diffractive optical element manufacturing apparatus according to claim 1, wherein the photoreactive material is formed in a sheet shape having a predetermined width direction size and extending in the length direction, and includes a conveying mechanism for conveying the sheet of the photoreactive material in the length direction so as to attach the photoreactive material to a first light incident surface of the prism, and the first light incident surface of the prism is formed with a size corresponding to the width direction size of the photoreactive material. Claim 7 A diffractive optical element manufacturing apparatus according to claim 1, wherein the prism is in the shape of a triangular prism. Claim 8 A method for manufacturing a diffractive optical element, comprising: a step of preparing a prism including a light incident surface into which light is incident and a light reflecting surface inclined at a predetermined angle from the light incident surface to reflect the light; a step of attaching a photoreactive material to record an interference pattern to a first light incident surface, which is part of the light incident surface of the prism; and a step of recording an interference pattern by irradiating light from a light source toward a second light incident surface of the prism, which is one of the light incident surfaces to which the photoreactive material is not attached. Claim 9 A method for manufacturing a diffractive optical element according to claim 8, wherein in the step of recording the interference pattern, an irradiating light that is irradiated from the light source, refracted at the interface between air and the photoreactive material, and incident into the photoreactive material, and a reflected light that is irradiated from the light source, passes through the second light incident surface of the prism, is reflected at the light reflecting surface, and is refracted between the prism and the first light incident surface and incident into the photoreactive material, interfere to form an interference pattern in the photoreactive material. Claim 10 A method for manufacturing a diffracting optical element according to claim 8, wherein the photoreactive material is formed in a sheet shape having a predetermined width direction size and extending in the longitudinal direction, and further comprising the step of transporting the sheet of the photoreactive material in the longitudinal direction so as to attach the photoreactive material to the first light incident surface of the prism. Claim 11 A method for manufacturing a diffractive optical element according to claim 8, wherein the diffractive optical element is a holographic optical element. Claim 12 A diffractive optical element manufactured by the method of any one of claims 8 to 11.

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