Prism, apparatus and method for manufacturing diffractive optical element and photoreactive material

Abstract

This disclosure provides an apparatus for manufacturing a diffractive optical element and a method for manufacturing a diffractive optical element. The apparatus includes: a prism for manufacturing a diffractive optical element, the prism including a photoreactive material attachment surface and a light-reflecting surface tilted at a predetermined angle from the photoreactive material attachment surface; and a light source positioned on the opposite side of the prism relative to the photoreactive material attached to the photoreactive material attachment surface and configured to irradiate light toward the photoreactive material.

Description

Technical Field

[0001] This specification claims priority and benefits to Korean Patent Application No. 10-2021-0093488, filed with the Korean Intellectual Property Office on July 16, 2021, the entire contents of which are incorporated herein by reference.

[0002] This invention relates to an apparatus and method for manufacturing diffractive optical elements, and more particularly, to an apparatus and method for manufacturing diffractive optical elements using a prism comprising a light-reflecting surface. Prior Technology

[0003] Diffractive optical elements, such as holographic optical elements, are manufactured by allowing two laser beams to interfere with each other, wherein the two laser beams have the same wavelength and coherent length in the photoreactive material.

[0004] When two laser beams are used to manufacture diffractive optical elements, the diffractive optical elements are greatly affected by the external environment (such as vibration or airflow), which frequently causes problems with the reproducibility of the manufactured diffractive optical elements.

[0005] As an alternative, after prefabricating a master plate, a technique has been developed to use the master plate to replicate diffractive optical elements with a single laser beam, thereby enabling the mass production of diffractive optical elements.

[0006] A laser beam is diffracted by a substrate to generate regenerated light, and the original laser beam and the regenerated light from the substrate interfere in a photoreactive material to undergo a process that replicates the diffractive optical element of the substrate. The following problems have been continuously arising.

[0007] First, it is not easy to set up the optical system for manufacturing the motherboard and control the external environment, and it is difficult to enlarge the motherboard itself due to the limitations of the laser beam source and optical system. Although increasing the area of ​​the motherboard is essential for mass production, the motherboards that can be manufactured only have a maximum side length of 100 mm, so some motherboards are already in use in a state where they are attached to the motherboard by the image block attachment method.

[0008] In this situation, it is necessary to mass-produce uniform master plates, and due to the nature of the master plates (which are consumable), they need to be produced continuously. In order for the replicated diffractive optical elements to maintain consistent optical performance, the master plates should be larger than the replicated diffractive optical elements, which leads to a degradation of chamfering efficiency during actual mass production, thereby adversely affecting the yield.

[0009] Furthermore, the performance of the replicated diffractive optical element depends on the performance of the master plate, and if defects occur during the manufacturing of the master plate, there is a problem that the defects of the master plate will also be replicated to the diffractive optical element. Summary of the Invention

[0010] Technical issues

[0011] The objective of this disclosure is to provide a prism that can be configured to manufacture diffractive optical elements.

[0012] Another objective of this disclosure is to provide an apparatus and method for manufacturing diffractive optical elements with a single light source without a mother plate by using a prism.

[0013] However, the problems to be solved by this disclosure are not limited to those mentioned above, and those skilled in the art will clearly understand from the following description other problems not mentioned.

[0014] Technical solution

[0015] According to the present disclosure, a prism for manufacturing diffractive optical elements is provided, the prism comprising: a photoreactive material attachment surface; and a light-reflecting surface tilted at a predetermined angle from the photoreactive material attachment surface.

[0016] In a prism for manufacturing a diffractive optical element according to an embodiment of the present disclosure, a predetermined angle between the photoreactive material attachment surface and the light-reflecting surface can be determined by the following Equation 1.

[0017] [Equation 1]

[0018] Where θp is the angle between the photoreactive material attachment surface and the light-reflecting surface of the prism; θt is the first incident angle when the irradiating light irradiates the photoreactive material from the opposite side of the prism towards the photoreactive material, and the irradiating light is refracted at the interface between the air and the photoreactive material and enters the photoreactive material; θd is the second incident angle when the irradiating light is transmitted through the photoreactive material, and the reflected light reflected from the light-reflecting surface is refracted at the interface between the prism and the photoreactive material and enters the photoreactive material; npp is the refractive index of the photoreactive material; and np corresponds to the refractive index of the prism.

[0019] When irradiating light is directed from the opposite side of a prism toward a photoreactive material attached to a prism for manufacturing a diffractive optical element according to an embodiment of the present disclosure, the first incident angle θt of the irradiating light, which is refracted at the interface between the air and the photoreactive material and incident into the photoreactive material, may be equal to or less than the total internal reflection angle θc between the photoreactive material and the air; and when the irradiating light is transmitted through the photoreactive material, the second incident angle θd of the reflected light reflected from the light-reflecting surface, which is refracted at the interface between the prism and the photoreactive material and incident into the photoreactive material, may be equal to or greater than the total internal reflection angle θc.

[0020] In a prism for manufacturing a diffractive optical element according to an embodiment of the present disclosure, a predetermined angle between the photoreactive material attachment surface and the light-reflecting surface can be determined by the following Equation 2.

[0021] [Equation 2]

[0022] Where θp is the angle between the photoreactive material attachment surface and the light-reflecting surface of the prism; θi is the incident angle at the interface between air and photoreactive material when the irradiation light is incident on the photoreactive material from the opposite side of the prism relative to the photoreactive material attached to the prism; θd is the second incident angle when the irradiation light is transmitted through the photoreactive material, the reflected light reflected from the light-reflecting surface is refracted at the interface between the prism and the photoreactive material and incident into the photoreactive material; npp is the refractive index of the photoreactive material; np is the refractive index of the prism; and nair corresponds to the refractive index of air.

[0023] According to one embodiment of this disclosure, the light-reflecting surface of a prism used for manufacturing diffractive optical elements may comprise a mirror-coated surface or a mirror-deposited surface.

[0024] According to one embodiment of this disclosure, a prism for manufacturing diffractive optical elements may have a triangular prism shape.

[0025] According to another aspect of this disclosure, an apparatus for manufacturing diffractive optical elements is provided, the apparatus comprising: a prism including a photoreactive material attachment surface and a light-reflecting surface tilted at a predetermined angle from the photoreactive material attachment surface; and a light source positioned on the opposite side of the prism relative to the photoreactive material attached to the photoreactive material attachment surface and configured to irradiate light toward the photoreactive material.

[0026] In an apparatus for manufacturing a diffractive optical element according to an embodiment of the present disclosure, interference fringes may be formed on a photoreactive material by allowing an irradiating light to interfere with reflected light, the irradiating light being irradiated from a light source and refracted at the interface between air and the photoreactive material, and then incident into the photoreactive material, wherein when the irradiating light passes through the photoreactive material, reflected light is reflected from a light-reflecting surface and refracted at the interface between a prism and the photoreactive material, and then incident into the photoreactive material.

[0027] In the prism of an apparatus for manufacturing diffractive optical elements according to an embodiment of the present disclosure, a predetermined angle between the photoreactive material attachment surface and the light-reflecting surface can be determined by the following Equation 1.

[0028] [Equation 1]

[0029] Where θp is the angle between the photoreactive material attachment surface and the light-reflecting surface of the prism; θt is the first incident angle when the irradiating light irradiates the photoreactive material from the opposite side of the prism towards the photoreactive material, and the irradiating light is refracted at the interface between the air and the photoreactive material and enters the photoreactive material; θd is the second incident angle when the irradiating light is transmitted through the photoreactive material, and the reflected light reflected from the light-reflecting surface is refracted at the interface between the prism and the photoreactive material and enters the photoreactive material; npp is the refractive index of the photoreactive material; and np corresponds to the refractive index of the prism.

[0030] In the apparatus for manufacturing diffractive optical elements according to embodiments of the present disclosure, the first incident angle θt of the irradiation light irradiated from the light source is refracted at the interface between air and photoreactive material and incident into the photoreactive material may be equal to or less than the total internal reflection angle θc between the photoreactive material and air, and when the irradiation light is transmitted through the photoreactive material, the second incident angle θd of the reflected light reflected from the light-reflecting surface is refracted at the interface between the prism and the photoreactive material and incident into the photoreactive material may be equal to or greater than the total internal reflection angle θc.

[0031] In the prism of the apparatus for manufacturing diffractive optical elements according to embodiments of the present disclosure, a predetermined angle between the photoreactive material attachment surface and the light-reflecting surface can be determined by the following Equation 2.

[0032] [Equation 2]

[0033] Where θp is the angle between the photoreactive material attachment surface and the light-reflecting surface of the prism; θi is the incident angle at the interface between air and photoreactive material when the irradiation light is incident on the photoreactive material from the opposite side of the prism relative to the photoreactive material attached to the prism; θd is the second incident angle when the irradiation light is transmitted through the photoreactive material, the reflected light reflected from the light-reflecting surface is refracted at the interface between the prism and the photoreactive material and incident into the photoreactive material; npp is the refractive index of the photoreactive material; np is the refractive index of the prism; and nair corresponds to the refractive index of air.

[0034] The apparatus for manufacturing diffractive optical elements according to embodiments of the present disclosure may further include a transmission mechanism configured to transmit photoreactive material or a prism such that the photoreactive material is attached to the photoreactive material attachment surface of the prism.

[0035] In an apparatus for manufacturing diffractive optical elements according to an embodiment of the present disclosure, the photoreactive material may be formed in the form of a sheet having a predetermined size in the width direction and extending in the length direction, and the transmission mechanism may include a transmission roller configured to continuously transmit the sheet of photoreactive material.

[0036] According to embodiments of this disclosure, the photoreactive material attachment surface of the prism of an apparatus for manufacturing diffractive optical elements may have a size corresponding to the width direction size of the photoreactive material.

[0037] In an apparatus for manufacturing a diffractive optical element according to an embodiment of the present disclosure, interference fringes may be continuously formed along any one of the width direction, length direction, and tilt direction of the photoreactive material, wherein the tilt direction forms a predetermined angle with the width direction or length direction.

[0038] According to another aspect of this disclosure, an apparatus for manufacturing a diffractive optical element is provided, the apparatus comprising: a prism including a photoreactive material attachment surface and a light-reflecting surface tilted at a predetermined angle from the photoreactive material attachment surface; and a light source positioned on the opposite side of the prism relative to the photoreactive material attached to the photoreactive material attachment surface and configured to irradiate light toward the photoreactive material, wherein a diffractive optical element having only one light source and without a mother plate can be manufactured by interfering reflected light with the irradiated light irradiated from the light source, wherein when the irradiated light passes through the photoreactive material, the reflected light is reflected from the light-reflecting surface.

[0039] According to another aspect of this disclosure, a method for manufacturing a diffractive optical element is provided, the method comprising the steps of: preparing a prism comprising a photoreactive material attachment surface and a light-reflecting surface tilted at a predetermined angle from the photoreactive material attachment surface; attaching a photoreactive material on which interference fringes are to be recorded to the prism; and recording interference fringes by irradiating the photoreactive material with light from a light source positioned on the opposite side of the prism relative to the photoreactive material.

[0040] In the step of preparing a prism in the method for manufacturing a diffractive optical element according to an embodiment of the present disclosure, a predetermined angle between the photoreactive material attachment surface and the light-reflecting surface of the prism can be determined by the following Equation 1.

[0041] [Equation 1]

[0042] Where θp is the angle between the photoreactive material attachment surface and the light-reflecting surface of the prism; θt is the first incident angle when the irradiating light irradiates the photoreactive material from the opposite side of the prism towards the photoreactive material, and the irradiating light is refracted at the interface between the air and the photoreactive material and enters the photoreactive material; θd is the second incident angle when the irradiating light is transmitted through the photoreactive material, and the reflected light reflected from the light-reflecting surface is refracted at the interface between the prism and the photoreactive material and enters the photoreactive material; npp is the refractive index of the photoreactive material; and np corresponds to the refractive index of the prism.

[0043] In the step of preparing a prism in the method for manufacturing a diffractive optical element according to an embodiment of the present disclosure, a predetermined angle between the photoreactive material attachment surface and the light-reflecting surface of the prism can be determined by the following Equation 2.

[0044] [Equation 2]

[0045] Where θp is the angle between the photoreactive material attachment surface and the light-reflecting surface of the prism; θ [, i, ] is the incident angle at the interface between air and photoreactive material when the irradiating light is incident on the photoreactive material attached to the prism from the opposite side of the prism towards the photoreactive material; θd is the second incident angle when the irradiating light is transmitted through the photoreactive material, the reflected light reflected from the light-reflecting surface is refracted at the interface between the prism and the photoreactive material and incident into the photoreactive material; npp is the refractive index of the photoreactive material; np is the refractive index of the prism; and nair corresponds to the refractive index of air.

[0046] In the step of recording interference fringes in the method for manufacturing a diffractive optical element according to an embodiment of the present disclosure, the interference fringes may be formed on a photoreactive material by allowing an irradiating light to interfere with the reflected light, the irradiating light being irradiated from a light source and refracted at the interface between air and the photoreactive material, and then incident into the photoreactive material, wherein when the irradiating light passes through the photoreactive material, the reflected light is reflected from a light-reflecting surface and refracted at the interface between a prism and the photoreactive material, and then incident into the photoreactive material.

[0047] In the step of recording interference fringes in the method for manufacturing a diffractive optical element according to an embodiment of the present disclosure, the first incident angle θt of the illumination light irradiated from the light source is refracted at the interface between air and photoreactive material and incident into the photoreactive material may be equal to or less than the total internal reflection angle θc between the photoreactive material and air, and when the illumination light is transmitted through the photoreactive material, the second incident angle θd of the reflected light reflected from the light-reflecting surface is refracted at the interface between the prism and the photoreactive material and incident into the photoreactive material may be equal to or greater than the total internal reflection angle θc.

[0048] In the step of recording interference fringes in the method for manufacturing a diffractive optical element according to an embodiment of the present disclosure, the interference fringes may be continuously formed along any one of the width direction, length direction, and tilt direction of the photoreactive material, wherein the tilt direction forms a predetermined angle with the width direction or length direction.

[0049] The method for manufacturing a diffractive optical element according to embodiments of the present disclosure may further include the step of transferring a photoreactive material or a prism, such that the photoreactive material is attached to the photoreactive material attachment surface of the prism.

[0050] In the method for manufacturing a diffractive optical element according to an embodiment of the present disclosure, the photoreactive material can be formed in the form of a sheet having a predetermined size in the width direction and extending in the length direction, and the sheet of photoreactive material can be continuously transferred in the step of transferring the photoreactive material.

[0051] The method for manufacturing diffractive optical elements according to embodiments of the present disclosure may further include the step of cutting a plurality of diffractive optical elements of a predetermined size along any one of the width direction, length direction, and tilt direction of the photoreactive material on which interference fringes are recorded, wherein the tilt direction forms a predetermined angle with the width direction or length direction.

[0052] The diffractive optical element manufactured by the method for manufacturing a diffractive optical element according to the embodiments of the present disclosure can be a holographic optical element.

[0053] A photoreactive material can be formed in the form of a sheet, on which interference fringes are recorded by allowing illumination light to interfere with reflected light. The illumination light is emitted from a light source of an apparatus for manufacturing diffractive optical elements according to an embodiment of the present disclosure, wherein when the illumination light passes through the photoreactive material, the reflected light is reflected from the light-reflecting surface, and the interference fringes can be continuously formed along any one of the width direction, length direction, and tilt direction of the photoreactive material, wherein the tilt direction forms a predetermined angle with the width direction or length direction.

[0054] A photoreactive material can be formed in the form of a sheet, on which interference fringes are recorded by means of a method for manufacturing a diffractive optical element according to an embodiment of the present disclosure, and the interference fringes can be continuously formed along any one of the width direction, length direction and tilt direction of the photoreactive material, wherein the tilt direction forms a predetermined angle with the width direction or length direction.

[0055] Beneficial effects

[0056] According to this disclosure, it is possible to manufacture a diffractive optical element with a light source but without a mother plate by using a prism with a light-reflecting surface, by allowing the illumination light illuminating from the light source to interfere with the reflected light reflected from the light-reflecting surface of the prism.

[0057] Therefore, there is no need to continuously produce consumable master sheets, and it is possible to prevent defects in the master sheets from being replicated in the diffractive optical elements.

[0058] Furthermore, the apparatus for manufacturing diffractive optical elements according to this disclosure can be implemented as a roll-to-roll apparatus, thereby mass-producing diffractive optical elements with uniform performance.

[0059] Furthermore, since the prism of the apparatus for manufacturing diffractive optical elements according to this disclosure can be manufactured over a large area, the chamfering efficiency can be improved during the mass production of diffractive optical elements.

[0060] Meanwhile, since no interference fringes are recorded in the gap between the mother plates when manufacturing diffractive optical elements using a conventional image block attachment type mother plate, the cutting efficiency is reduced when intermittent interference fringes are formed on the photoreactive material, especially when performing inclined cutting.

[0061] Conversely, according to this disclosure, it is possible to continuously form interference fringes on photoreactive materials, thereby greatly improving cutting efficiency.

[0062] The effects of this disclosure are not limited to those described above, and those skilled in the art will clearly understand from this specification and the accompanying drawings any effects not mentioned. Simple Explanation of the Diagram

[0063] Figure 1 is a diagram illustrating the concept of manufacturing a diffractive optical element according to an embodiment of the present disclosure. Figure 2 is a cross-sectional view showing the optical path of irradiated light in an apparatus for manufacturing a diffractive optical element according to an embodiment of the present disclosure. Figure 3 is a perspective view of a prism illustrating an apparatus for manufacturing diffractive optical elements according to an embodiment of the present disclosure. Figure 4 is a schematic diagram illustrating an apparatus for manufacturing diffractive optical elements according to another embodiment of the present disclosure. Figure 5A is a graph showing the transmittance of the wavelength of a diffractive optical element manufactured according to an example of the present disclosure. Figure 5B is a graph showing the reflectivity of the wavelength of a diffractive optical element manufactured according to an example of the present disclosure. Figure 6A is a graph showing the transmittance of the wavelength of a diffractive optical element manufactured according to the comparative example of this disclosure. Figure 6B is a graph showing the reflectivity of the wavelength of a diffractive optical element manufactured according to the comparative example disclosed herein. Implementation

[0064] This disclosure will become apparent from the following detailed description of the embodiments in conjunction with the accompanying drawings. However, this disclosure is not limited to the embodiments disclosed below, but will be implemented in various different forms. These embodiments are provided only to ensure that the disclosure is complete and fully informs those skilled in the art of the subject matter of the disclosure, and the disclosure is defined only by the scope of the claims. Furthermore, the terminology used in this specification is for describing embodiments and is not intended to limit the disclosure.

[0065] Throughout this specification, unless otherwise specifically indicated by the phrase, the singular form also includes the plural form.

[0066] Throughout this specification, the terms "comprise / comprising and / or include / including" are used to indicate the presence of named components, steps, operations, and / or elements, without excluding the presence or addition of one or more other components, steps, operations, and / or elements. Unless otherwise specifically stated, these terms mean that another component may be included but not excluded.

[0067] Throughout this specification, terms such as "first," "second," etc., may be used to describe various components, but components should not be limited by these terms. Terms are used only for the purpose of distinguishing one component from another.

[0068] Throughout this specification, the term "diffractive optical element" means an optical element having a diffraction grating pattern, wherein high-refractive and low-refractive portions are alternately arranged along a predetermined direction, and light reaching the diffractive optical element can be diffracted to change its optical path.

[0069] Throughout this specification, the term "holographic diffraction optical element" refers to an optical element having a holographic grating pattern in which high-refractive-index and low-refractive-index portions are alternately arranged along a predetermined direction, and light reaching the holographic diffraction optical element can be diffracted to alter its optical path. Such holographic grating patterns can be recorded by allowing multiple lasers to interfere with each other on a photosensitive material such as a photopolymer.

[0070] This disclosure will be described in more detail below.

[0071] Figures 1 to 4 illustrate the configuration and operation of an apparatus for manufacturing a diffractive optical element according to an embodiment of the present disclosure. Figure 1 is a schematic diagram illustrating the concept of manufacturing a diffractive optical element according to an embodiment of the present disclosure. Figure 2 is a cross-sectional view showing the optical path of the irradiating light in the apparatus for manufacturing a diffractive optical element. Figure 3 is a perspective view showing the prism of the apparatus for manufacturing a diffractive optical element. Figure 4 is a schematic diagram showing the apparatus for manufacturing a diffractive optical element.

[0072] An apparatus 1 for manufacturing a diffractive optical element according to an embodiment of the present disclosure will be described with reference to Figures 1 to 4. The apparatus 1 for manufacturing a diffractive optical element according to an embodiment of the present disclosure can manufacture a diffractive optical element by irradiating light onto a photoreactive material 2 and allowing the light to interfere with the photoreactive material 2, thereby recording interference fringes.

[0073] According to an embodiment of the present disclosure, an apparatus 1 for manufacturing diffractive optical elements is configured to include a light source 20 configured to irradiate light onto a photoreactive material 2 and a prism 10 configured to interfere with light irradiated from the light source 20.

[0074] More specifically, the prism 10 used to manufacture diffractive optical elements can be configured to include a photoreactive material attachment surface 11 to which the photoreactive material 2 is attached and a light-reflecting surface tilted at a predetermined angle θp from the photoreactive material attachment surface 11.

[0075] The light source 20 can be positioned on the opposite side of the prism 10 relative to the photoreactive material 2 attached to the attachment surface 11 of the photoreactive material, and can be configured to irradiate light toward the photoreactive material 2.

[0076] As shown in FIG1, the apparatus 1 for manufacturing a diffractive optical element according to an embodiment of the present disclosure can manufacture a diffractive optical element having only one light source and no mother plate by irradiating light onto a photoreactive material 2 attached to a prism 10 and allowing the irradiation light La to interfere with the reflected light Lb irradiated from the light source 20, wherein when the irradiation light La is transmitted through the photoreactive material 2, the reflected light is reflected from the light-reflecting surface 12, thereby recording interference fringes on the photoreactive material 2.

[0077] The optical path for recording interference fringes on a photoreactive material 2 using an apparatus 1 for manufacturing diffractive optical elements, according to an embodiment of the present disclosure, will be described with reference to FIG2. Irradiation light La, irradiated from light source 20 at a predetermined irradiation angle θi, is refracted at the interface between air and photoreactive material 2 and incident into photoreactive material 2, and the incident angle at this time can be referred to as the first incident angle θt.

[0078] After being transmitted through the photoreactive material 2 and reflected from the light-reflecting surface 12, the irradiated light La is refracted at the interface between the prism 10 and the photoreactive material 2 and then incident into the photoreactive material 2. The light reflected from the light-reflecting surface 12 is called the reflected light Lb, and the incident angle at this time can be called the second incident angle θd.

[0079] On the other hand, the irradiation light La and the reflected light Lb are light generated from a light source 20, and after the irradiation light La is reflected from the light-reflecting surface 12 of the prism 10, the irradiation light La becomes the reflected light Lb. The irradiation light La and the reflected light Lb interfere with each other to form interference fringes on the photoreactive material 2, thereby making it possible to manufacture diffractive optical elements.

[0080] In the apparatus 1 for manufacturing diffractive optical elements according to the embodiments of the present disclosure, in order to form interference fringes by allowing the illumination light La, which is irradiated by the light source 20, to interfere with the reflected light Lb reflected from the light-reflecting surface 12 of the prism 10 along the optical path, preferably, the first incident angle θt when the illumination light La is refracted at the interface between the air and the photoreactive material 2 and incident into the photoreactive material 2, and the second incident angle θd when the reflected light La is refracted at the interface between the prism 19 and the photoreactive material 2 and incident into the photoreactive material 2, each satisfy a predetermined relationship of the total internal reflection angle θc between the photoreactive material 2 and the air.

[0081] Specifically, if the first incident angle θt becomes equal to or less than the total reflection angle θc and the second incident angle θd becomes equal to or greater than the total reflection angle θc, then the irradiated light La and the reflected light Lb can interfere with each other within the photoreactive material 2 to form interference fringes.

[0082] From another perspective, in order to adjust the angles of the two types of light that need to be incident on the photoreactive material 2 to create a diffractive optical element, the angle of the prism 10 (that is, the angle between the photoreactive material attachment surface 11 and the light reflecting surface 12 of the prism 10) can be determined by the following [Equation 1].

[0083] [Equation 1]

[0084] Where θp is the angle between the photoreactive material attachment surface 11 and the light reflecting surface 12 of the prism 10; θt is the first incident angle at which the irradiation light La, irradiated by the light source 20, is refracted at the interface between the air and the photoreactive material 2 and incident into the photoreactive material 2; θd is the second incident angle at which the reflected light Lb, reflected from the light reflecting surface 12, is refracted at the interface between the prism 10 and the photoreactive material 2 and incident into the photoreactive material 2 when the irradiation light La is transmitted through the photoreactive material 2; npp is the refractive index of the photoreactive material 2; and np corresponds to the refractive index of the prism 10.

[0085] If the angle at which the illumination light from the light source 20 is incident on the interface between the air and the photoreactive material is defined as the illumination angle θi, then the first incident angle θt can be replaced by the illumination angle θi using Snell's law, and [Equation 1] is changed as shown in [Equation 2] below, so that the angle θp of the prism 10 can be plotted as the relationship between the illumination angle θi and the second incident angle θd.

[0086] [Equation 2]

[0087] Where θp is the angle between the photoreactive material attachment surface 11 and the light reflecting surface 12 of the prism 10; θi is the incident angle of the irradiation light La from the light source 20 at the interface between air and the photoreactive material 2; θd is the second incident angle at which the reflected light Lb reflected from the light reflecting surface 12 is refracted at the interface between the prism 10 and the photoreactive material 2 and incident into the photoreactive material 2 when the irradiation light La is transmitted through the photoreactive material 2; npp is the refractive index of the photoreactive material 2; np is the refractive index of the prism 10, and nair corresponds to the refractive index of air.

[0088] According to embodiments of the present disclosure, the light-reflecting surface 12 of a prism 10 for manufacturing diffractive optical elements can be configured to mirror-reflect light incident on the prism 10 after the photosensitive material attachment surface 11, and can be formed by coating or deposition to form a mirror-coated surface or a mirror-deposited surface, but the present disclosure is not limited thereto. The light-reflecting surface 12 can also be implemented by attaching a reflective optical element to the prism 10, and any configuration is possible as long as it can reflect light incident on the prism 10 and reaching the light-reflecting surface 12.

[0089] As shown in Figure 3, the prism 10 for manufacturing a diffractive optical element according to an embodiment of this disclosure may have a triangular prism shape, and one side surface of the triangular prism may become a photoreactive material attachment surface 11, and the adjacent side surface may become a light-reflecting surface 12. However, this disclosure is not limited to this, and any configuration is possible as long as it satisfies a predetermined angular relationship with the photoreactive material attachment surface 11 and includes a light-reflecting surface 12 adjacent to it.

[0090] The prism 10 for manufacturing diffractive optical elements according to embodiments of this disclosure may be made of quartz, BK7, or poly(methyl methacrylate); PMMA, but is not limited thereto.

[0091] In the apparatus 1 for manufacturing diffractive optical elements according to the embodiments of the present disclosure, the light source 20 may be a laser beam source and may be configured to irradiate a light having a predetermined wavelength and a coherence length.

[0092] Here, "one" can mean that, in addition to the light source being a single type of light, the illuminating light La and the reflected light Lb are also produced by the "same" light source.

[0093] According to embodiments of this disclosure, the photoreactive material may comprise a photosensitive material and may be formed in various shapes (such as sheet shapes or roll shapes having a predetermined width and / or length dimension). Various types of photosensitive materials that can be used in the manufacture of diffractive optical elements comprising holographic optical elements have been disclosed and are known, and such materials may be used without limitation even in this disclosure.

[0094] According to embodiments disclosed herein, photopolymers, photoresists, silver halide emulsions, gelatin dichromate, developing emulsions, photothermoplastic materials, or photorefractive materials can be used as photosensitive materials. Interference fringes can be easily recorded using the aforementioned photosensitive materials.

[0095] The diffractive optical element manufactured according to the embodiments disclosed herein can be a holographic optical element.

[0096] According to the embodiments of this disclosure, the apparatus 1 for manufacturing diffractive optical elements can be configured as a roll-to-roll apparatus to mass-produce diffractive optical elements.

[0097] This will be described in more detail with reference to Figure 4.

[0098] In the apparatus 1 for manufacturing diffractive optical elements according to the embodiments of the present disclosure, the photoreactive material 2 can be formed in the form of a sheet having a predetermined size in the width direction and extending in the length direction. At this time, the width direction size of the photoreactive material 2 can be configured to be 500 mm or larger, but is not limited thereto, and can be set differently depending on the size of the diffractive optical element to be produced.

[0099] The sheet-shaped photoreactive material 2 can be supplied by a supply roller 40 wound in the shape of a roller, and the sheet-shaped photoreactive material 2, on which interference fringes are recorded and manufactured as a diffraction optical element, can be wound by a reduction roller 50 in the form of a roller.

[0100] When the sheet-shaped photoreactive material 2 is supplied to the equipment 1 for manufacturing diffractive optical elements, a transmission mechanism 30 configured to transfer the photoreactive material 2 to the photoreactive material attachment surface 11 of the prism 10 can be installed, and the transmission mechanism 30 can be configured in the form of a transmission roller that continuously transfers the sheet of photoreactive material 2.

[0101] The transmission mechanism 30 can also be configured to transmit the prism 10 in addition to the photoreactive material 2.

[0102] Furthermore, the photoreactive material attachment surface 11 of the prism 10 used for manufacturing diffractive optical elements according to the embodiments of this disclosure can be configured to correspond to the width direction size of the sheet-shaped photoreactive material 2.

[0103] With this configuration, the chamfering efficiency during the generation of diffractive optical elements from the self-photoreactive material 2 can be greatly improved compared to the case of using a motherboard of conventional technology, and therefore it is effective.

[0104] The motherboards in conventional technology cannot be manufactured on a large scale due to laser and optical limitations. Therefore, for mass production, several motherboards must be attached to the substrate as image blocks for use. In this way, when several motherboards are attached as image blocks, there is a problem of reduced chamfering efficiency during the production of diffractive optical elements.

[0105] On the other hand, since the prism 10 for manufacturing diffractive optical elements according to the embodiments of this disclosure can be manufactured over a large area with a side length of 500 mm or more, the prism 10 can prevent the reduction in chamfering efficiency that occurs when several motherboards are attached in the manner of image blocks as in the prior art.

[0106] The sheet-shaped photoreactive material 2 on which interference fringes are recorded by the prism 10 can undergo a process of cutting the sheet-shaped photoreactive material 2 into individual diffractive optical elements each having a predetermined size.

[0107] This cutting can be performed in the width direction, length direction, or inclined direction of the sheet-shaped photoreactive material 2, wherein the inclined direction forms a predetermined angle with the width direction or length direction.

[0108] Here, it is necessary to effectively cut the sheet-shaped photoreactive material 2 so that as many individual diffractive optical elements as possible can be placed within a unit size of the sheet-shaped photoreactive material 2, for example, 500 mm × 500 mm.

[0109] The total area of ​​individual diffractive optical elements placed relative to the unit area of ​​the sheet-shaped photoreactive material 2 is defined as the cutting efficiency, and the production yield can be improved by improving the cutting efficiency.

[0110] The cutting efficiency of the diffractive optical element manufactured according to the embodiments of this disclosure is higher than that of the diffractive optical element manufactured using a conventional image block attachment type motherboard, and specifically, the difference in cutting efficiency between the two inventions becomes much larger when cutting in an oblique direction.

[0111] When using a conventional image block attachment type motherboard, a solid gap appears between the motherboards when the motherboard is attached to the motherboard as an image block. Interference fringes cannot be recorded in this solid gap, so the interference fringes recorded on the photoreactive material sheet before cutting do not form continuously, but the interference fringes are intermittently recorded in the gap between the motherboards.

[0112] These intermittent interference fringes have a negative impact on increasing cutting efficiency.

[0113] Furthermore, according to the embodiments disclosed herein, since interference fringes can be continuously recorded on the sheet-shaped photoreactive material 2, it is possible to obtain significantly improved cutting efficiency compared to the prior art.

[0114] According to the embodiments disclosed herein, interference fringes can be continuously formed along the width direction, length direction, and tilt direction of the sheet-shaped photoreactive material 2, wherein the tilt direction forms a predetermined angle with the width direction or length direction, and individual diffraction optical elements can be cut across the entire area within a unit size of the sheet-shaped photoreactive material 2.

[0115] According to another embodiment of this disclosure, a method for manufacturing a diffractive optical element includes the following steps: preparing a prism 10, the prism 10 comprising a photoreactive material attachment surface 11 and a self-photoreactive material attachment surface 11 at a predetermined angle θ. [, p An inclined light-reflecting surface 12 is used; a photoreactive material 2 on which interference fringes are to be recorded is attached to a prism 10; and interference fringes are recorded by irradiating light from a light source 20 toward the photoreactive material 2, the light source 20 being positioned on the opposite side of the prism 10 relative to the photoreactive material 2.

[0116] In the step of preparing the prism 10, the prism 10 may have the same configuration as the device 1 for manufacturing diffractive optical elements according to the previous embodiment.

[0117] In the step of recording interference fringes after attaching the photoreactive material 2 to the prism 10, the irradiating light La (which is irradiated from the light source 20 and refracted at the interface between the air and the photoreactive material 2, and then incident into the photoreactive material 2) and the reflected light Lb (wherein, when the irradiating light La is transmitted through the photoreactive material 2, the reflected light Lb is reflected from the light reflecting surface 12 and refracted at the interface between the prism 10 and the photoreactive material 2, and incident into the photoreactive material 2) can interfere with each other to form interference fringes on the photoreactive material 2.

[0118] The method for manufacturing a diffractive optical element according to an embodiment of the present disclosure may further include the step of transferring photoreactive material 2 or prism 10 such that photoreactive material 2 is attached to photoreactive material attachment surface 11 of prism 10, which makes it possible to continuously supply photoreactive material 2 to manufacture a diffractive optical element.

[0119] In this case, the photoreactive material 2 can be configured to have a sheet shape with a predetermined width and an extension in the length direction, so that the sheet can continuously transmit the photoreactive material.

[0120] A method for manufacturing diffractive optical elements according to embodiments of the present disclosure may include the step of cutting a sheet-shaped photoreactive material 2 on which interference fringes are recorded into a plurality of diffractive optical elements.

[0121] This cutting can be performed along the width, length, or tilt direction of the sheet-shaped photoreactive material 2, wherein the tilt direction forms a predetermined angle with the width or length direction.

[0122] According to the embodiments disclosed herein, interference fringes can be continuously recorded on the sheet-shaped photoreactive material 2 during the step of recording interference fringes.

[0123] More specifically, since the interference fringes are continuously formed along the width, length, or tilt direction of the sheet-shaped photoreactive material 2, and the tilt direction forms a predetermined angle with the width or length direction, individual diffractive optical elements can be cut across the entire area within a unit size of the sheet-shaped photoreactive material 2, which makes it possible to improve the cutting efficiency.

[0124] Example

[0125] After the apparatus 1 for manufacturing a diffractive optical element according to an embodiment of the present disclosure is prepared to attach photoreactive material 2 to the photoreactive material attachment surface 11 of prism 10, the irradiation light La is incident from the light source 20 at an irradiation angle θi of 60 degrees, and then the second incident angle θd of the reflected light Lb reflected from the light reflecting surface 12 of prism 10 is set to 66 degrees to allow the irradiation light La to interfere with the reflected light Lb, thereby manufacturing a diffractive optical element.

[0126] Here, a laser beam source with a wavelength of 660 nanometers and a coherence length of 2 meters is used as the light source 20, a photopolymer is used as the photoreactive material 2, and the θp of the prism 10 is set to 15 degrees.

[0127] The optical properties of the fabricated diffractive optical element are illustrated in Figures 5A and 5B.

[0128] Figures 5A and 5B are graphs obtained by measuring the efficiency of the diffractive optical element manufactured according to the example of the present disclosure. Figure 5A is a graph showing the transmittance of the wavelength of the diffractive optical element manufactured according to the example of the present disclosure, and Figure 5B is a graph showing the reflectance of the wavelength of the diffractive optical element manufactured according to the example of the present disclosure.

[0129] According to Figures 5A and 5B, when light is incident at 0 degrees onto the diffractive optical element of the example according to the present disclosure, it diffracts at 50 degrees and exhibits a peak wavelength of 986 nanometers, a transmittance of 39.7%, and a reflectance of 49.9%.

[0130] Comparative example

[0131] An apparatus for manufacturing diffractive optical elements according to a comparative example of this disclosure is prepared. Unlike the apparatus for manufacturing diffractive optical elements according to the examples of this disclosure, a motherboard is manufactured using conventional techniques instead of a prism, and a main board is manufactured. The configuration, except for the main board, is configured in the same manner as in the examples of this disclosure.

[0132] More specifically, the photopolymer is used as the motherboard, and a laser beam source with a wavelength of 660 nanometers and a coherence length of 2 meters is used as the light source. The motherboard is manufactured by separating the light source into two light sources and allowing the two light sources to interfere with each other.

[0133] After the photoreactive material is attached to the photoreactive material attachment surface of the motherboard, the irradiation light is incident from the light source at an irradiation angle of 60 degrees, and then the incident angle of the diffracted light diffracting from the motherboard is set to 66 degrees to allow the irradiation light and the diffracted light to interfere with each other, thereby creating a replicated diffracted optical element identical to the motherboard on the photoreactive material.

[0134] Here, a laser beam source with a wavelength of 660 nanometers and a coherence length of 2 meters is used as the light source, and a photopolymer is used as the photoreactive material 2.

[0135] The optical properties of the diffractive optical element manufactured according to the comparative example are illustrated in Figures 6A and 6B.

[0136] Figures 6A and 6B are graphs obtained by measuring the efficiency of the diffractive optical element manufactured according to the comparative example of the present disclosure. Figure 6A is a graph showing the transmittance of the wavelength of the diffractive optical element manufactured according to the comparative example of the present disclosure, and Figure 6B is a graph showing the reflectance of the wavelength of the diffractive optical element manufactured according to the comparative example of the present disclosure.

[0137] According to Figures 6A and 6B, when light is incident at 0 degrees onto the diffractive optical element of the comparative example according to the present disclosure, it diffracts at 50 degrees and exhibits a peak wavelength of 987 nanometers, a transmittance of 46.0%, and a reflectance of 44.8%.

[0138] Therefore, when comparing the measurement data of the example according to this disclosure with the measurement data according to the comparative example, the example can manufacture a diffractive optical element with an efficiency that is about 5% or higher than that of the comparative example.

[0139] Although this disclosure has been described with reference to limited embodiments, it is not limited thereto, and various changes and modifications are of course possible within the technical spirit of this disclosure and within the scope of the claims which are equivalent to those described below by those skilled in the art to which this disclosure pertains.

[0140] 1: Equipment used for manufacturing diffractive optical elements 2: Photoreactive materials 10: Prisms used to manufacture diffractive optical elements 11: Surface for attaching photoreactive materials 12: Light-reflecting surface 20: Light source 30: Transmission mechanism 40: Supply Roller 50: Reduction Roller La: illuminating light Lb: Reflected light θc: Total internal reflection angle θd: Second angle of incidence θi: Illumination angle θp: The angle between the photoreactive material attachment surface and the light-reflecting surface of the prism. θt: First angle of incidence

Claims

1. A prism for manufacturing a diffractive optical element, the prism comprising a photoreactive material attachment surface and a light-reflecting surface inclined at a predetermined angle from the photoreactive material attachment surface, wherein the predetermined angle is determined by either Equation 1 or Equation 2, [Equation 1], [Equation 2] Where θp is the angle between the photoreactive material attachment surface and the light-reflecting surface of the prism; θt is the first incident angle when the irradiated light irradiates the photoreactive material from the opposite side of the prism toward the photoreactive material, and the irradiated light is refracted at the interface between the air and the photoreactive material and incident into the photoreactive material; θi is the irradiation angle when the irradiated light irradiates the photoreactive material from the opposite side of the prism toward the photoreactive material, and the irradiated light is incident at the interface between the air and the photoreactive material; θd is the second incident angle when the irradiated light is transmitted through the photoreactive material, and the reflected light reflected from the light-reflecting surface refracts at the interface between the prism and the photoreactive material and incident into the photoreactive material; npp is the refractive index of the photoreactive material; and np corresponds to the refractive index of the prism.

2. The prism for manufacturing diffractive optical elements as described in claim 1, wherein, When irradiating light is directed from the opposite side of the prism toward the photoreactive material attached to the prism, the first incident angle θt of the irradiating light, refracted at the interface between the air and the photoreactive material and incident into the photoreactive material, is equal to or less than the total internal reflection angle θc between the photoreactive material and the air. Furthermore, when the irradiating light is transmitted through the photoreactive material, the second incident angle θd of the reflected light, refracted at the interface between the prism and the photoreactive material and incident into the photoreactive material, is equal to or greater than the total internal reflection angle θc.

3. The prism for manufacturing diffractive optical elements as claimed in claim 1, wherein the light-reflecting surface comprises a mirror-coated surface or a mirror-deposited surface.

4. The prism for manufacturing diffractive optical elements as claimed in claim 1, wherein the prism has a triangular prism shape.

5. An apparatus for manufacturing diffractive optical elements, the apparatus comprising: A prism includes a photoreactive material attachment surface and a light-reflecting surface tilted at a predetermined angle from the photoreactive material attachment surface; And a light source, positioned on the opposite side of the prism relative to the photoreactive material attached to the photoreactive material attachment surface, and configured to irradiate light toward the photoreactive material, wherein the predetermined angle is determined by the following Equation 1 or Equation 2, [Equation 1], [Equation 2], where θp is the angle between the photoreactive material attachment surface and the light-reflecting surface of the prism; θt is the first incident angle at which the irradiated light from the light source is refracted at the interface between the air and the photoreactive material and enters the photoreactive material; θi is the incident angle of the irradiation light from the light source onto the interface between the air and the photoreactive material; θd is the second incident angle of the reflected light from the light-reflecting surface when the irradiation light passes through the photoreactive material, which is refracted at the interface between the prism and the photoreactive material and incident into the photoreactive material; npp is the refractive index of the photoreactive material; and np corresponds to the refractive index of the prism.

6. The apparatus for manufacturing a diffractive optical element as claimed in claim 5, wherein interference fringes are formed on the photoreactive material by allowing an irradiating light to interfere with reflected light, the irradiating light being irradiated from the light source and refracted at the interface between air and the photoreactive material, and then incident into the photoreactive material, wherein when the irradiating light passes through the photoreactive material, reflected light is reflected from the light-reflecting surface and refracted at the interface between the prism and the photoreactive material, and incident into the photoreactive material.

7. The apparatus for manufacturing a diffractive optical element as claimed in claim 5, wherein the first incident angle θt of illumination light irradiated from the light source is refracted at the interface between the air and the photoreactive material and incident into the photoreactive material is equal to or less than the total internal reflection angle θc between the photoreactive material and the air, and when the illumination light is transmitted through the photoreactive material, the second incident angle θd of reflected light reflected from the light-reflecting surface is refracted at the interface between the prism and the photoreactive material and incident into the photoreactive material is equal to or greater than the total internal reflection angle θc.

8. The apparatus for manufacturing a diffractive optical element as claimed in claim 5, further comprising a transmission mechanism configured to transmit the photoreactive material or the prism such that the photoreactive material is attached to the photoreactive material attachment surface of the prism.

9. The apparatus for manufacturing a diffractive optical element as claimed in claim 8, wherein the photoreactive material is formed in the form of a sheet having a predetermined size in the width direction and extending in the length direction, and the transmission mechanism includes a transmission roller configured to continuously transmit the sheet of the photoreactive material.

10. The apparatus for manufacturing a diffractive optical element as claimed in claim 5, wherein the photoreactive material attachment surface of the prism has a size corresponding to the width direction size of the photoreactive material.

11. The apparatus for manufacturing a diffractive optical element as claimed in claim 5, wherein interference fringes are continuously formed along any one of the width direction, length direction, and tilt direction of the photoreactive material, the tilt direction forming a predetermined angle with the width direction or the length direction.

12. An apparatus for manufacturing diffractive optical elements, the apparatus comprising: A prism includes a photoreactive material attachment surface and a light-reflecting surface tilted at a predetermined angle from the photoreactive material attachment surface; A light source is positioned on the opposite side of the prism relative to the photoreactive material attached to the photoreactive material's attachment surface and configured to irradiate light toward the photoreactive material. A diffractive optical element with only one light source and no mother plate is manufactured by allowing the irradiated light to interfere with the reflected light from the light source. When the irradiated light passes through the photoreactive material, the reflected light is reflected from the light-reflecting surface. The predetermined angle is determined by either Equation 1 or Equation 2, [Equation 1], [Equation 2], where θp is the angle between the photoreactive material attachment surface and the light-reflecting surface of the prism; θt is the first angle of incidence when the irradiated light irradiates the photoreactive material from the opposite side of the prism toward the photoreactive material relative to the photoreactive material attached to the prism, refracted at the interface between the air and the photoreactive material, and incident into the photoreactive material. θi is the incident angle at the interface between air and the photoreactive material when the irradiating light is incident on the photoreactive material from the opposite side of the prism relative to the photoreactive material attached to the prism; θd is the second incident angle at which the reflected light reflected from the light-reflecting surface is refracted at the interface between the prism and the photoreactive material and incident on the photoreactive material when the irradiating light is transmitted through the photoreactive material; npp is the refractive index of the photoreactive material; and np corresponds to the refractive index of the prism.

13. A method for manufacturing a diffractive optical element, the method comprising the steps of: preparing a prism including a photoreactive material attachment surface and a light-reflecting surface tilted at a predetermined angle from the photoreactive material attachment surface; attaching a photoreactive material on which interference fringes are to be recorded to the prism; and recording interference fringes by irradiating light from a light source toward the photoreactive material, the light source being positioned on the opposite side of the prism relative to the photoreactive material.

14. The method for manufacturing a diffractive optical element as claimed in claim 13, wherein the predetermined angle in the step of preparing the prism is determined by the following Equation 1, [Equation 1] where θp is the angle between the photoreactive material attachment surface and the light-reflecting surface of the prism; θt is a first angle of incidence where the irradiated light from the light source is refracted at the interface between air and the photoreactive material and incident into the photoreactive material; θd is a second angle of incidence where the reflected light from the light-reflecting surface is refracted at the interface between the prism and the photoreactive material and incident into the photoreactive material when the irradiated light is transmitted through the photoreactive material; npp is the refractive index of the photoreactive material; and np corresponds to the refractive index of the prism.

15. The method for manufacturing a diffractive optical element as claimed in claim 13, wherein the predetermined angle in the step of preparing the prism is determined by the following Equation 2, [Equation 2] where θp is the angle between the photoreactive material attachment surface and the light-reflecting surface of the prism; θi is the incident angle of the irradiation light from the light source incident on the interface between air and the photoreactive material; θd is the second incident angle when the irradiation light is transmitted through the photoreactive material, the reflected light reflected from the light-reflecting surface is refracted at the interface between the prism and the photoreactive material and incident on the photoreactive material; npp is the refractive index of the photoreactive material; np is the refractive index of the prism; and nair corresponds to the refractive index of air.

16. The method for manufacturing a diffractive optical element as described in claim 13, wherein, In the step of recording the interference fringes, the interference fringes are formed on the photoreactive material by allowing the irradiated light to interfere with the reflected light, the irradiated light being irradiated from the light source and refracted at the interface between the air and the photoreactive material, and then incident into the photoreactive material, wherein when the irradiated light passes through the photoreactive material, the reflected light is reflected from the light-reflecting surface and refracted at the interface between the prism and the photoreactive material, and incident into the photoreactive material.

17. The method for manufacturing a diffractive optical element as described in claim 13, wherein, In the step of recording the interference fringes, the first incident angle θt of the irradiation light from the light source refracted at the interface between the air and the photoreactive material and incident into the photoreactive material is equal to or less than the total internal reflection angle θc between the photoreactive material and the air, and when the irradiation light is transmitted through the photoreactive material, the second incident angle θd of the reflected light reflected from the light-reflecting surface refracted at the interface between the prism and the photoreactive material and incident into the photoreactive material is equal to or greater than the total internal reflection angle θc.

18. The method for manufacturing a diffractive optical element as described in claim 13, wherein, In the step of recording the interference fringes, the interference fringes are continuously formed along any one of the width direction, length direction, and tilt direction of the photoreactive material, wherein the tilt direction forms a predetermined angle with the width direction or the length direction.

19. The method for manufacturing a diffractive optical element as claimed in claim 13, further comprising the step of transferring the photoreactive material or the prism such that the photoreactive material is attached to the photoreactive material attachment surface of the prism.

20. The method for manufacturing a diffractive optical element as claimed in claim 19, wherein the photoreactive material is formed in the form of a sheet having a predetermined size in the width direction and extending in the length direction, and the sheet of the photoreactive material is continuously transferred in the step of transferring the photoreactive material.

21. The method for manufacturing a diffractive optical element as claimed in claim 13 further includes the step of cutting a plurality of diffractive optical elements of a predetermined size along any one of the width direction, length direction, and tilt direction of the photoreactive material on which the interference fringes are recorded, wherein the tilt direction forms a predetermined angle with the width direction or the length direction.

22. The method for manufacturing a diffractive optical element as described in claim 13, wherein the diffractive optical element is a holographic optical element.

23. A photoreactive material on which interference fringes are recorded by allowing an irradiating light to interfere with reflected light, the irradiating light being irradiated by the light source of the apparatus for manufacturing diffractive optical elements described in claim 7, wherein... When irradiating light is transmitted through the photoreactive material, the reflected light is reflected from the light-reflecting surface. The photoreactive material is formed in the form of a sheet, and the photoreactive material has interference fringes continuously formed thereon along any one of the width direction, length direction, and tilt direction of the photoreactive material, wherein the tilt direction forms a predetermined angle with the width direction or the length direction.

24. A photoreactive material on which interference fringes are recorded by means of the method for manufacturing a diffractive optical element as described in claim 13, wherein the photoreactive material is formed in the form of a sheet and the photoreactive material has interference fringes continuously formed thereon along any one of a width direction, a length direction and a tilt direction of the photoreactive material, the tilt direction forming a predetermined angle with the width direction or the length direction.

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