Holographic optical element, method for manufacturing the same and apparatus for manufacturing the same

Abstract

The present invention relates to a holographic optical element capable of improving the brightness of an enhanced image, a manufacturing method for the holographic optical element, and a manufacturing apparatus for the holographic optical element. The holographic optical element is configured by combining a plurality of optical elements in which respective interference patterns recorded on each optical element have the same pitch as each other but different tilt angles from each other.

Description

[0001] Cross-reference of related technologies

[0002] This application claims the benefit of Korean Patent Application No. 10-2020-0107287, filed with the Korean Intellectual Property Office on August 25, 2020, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to holographic optical elements, methods for manufacturing the holographic optical elements, and apparatus for manufacturing the holographic optical elements, and more specifically, to holographic optical elements capable of improving the brightness of enhanced images, methods for manufacturing the holographic optical elements, and apparatus for manufacturing the holographic optical elements. Background Technology

[0004] Holographic optical elements are optical elements made by recording an interference pattern, formed by the interference between an object wave and a reference wave, onto a photosensitive material. The object wave is light reflected and diffracted from an object, and the reference wave is another wave coherent with the light. Because the photosensitive material on which the interference pattern is recorded uses diffraction rather than reflection or refraction to reproduce and enhance image information, such photosensitive materials are also classified as diffractive optical elements.

[0005] Meanwhile, holographic optical elements are typically manufactured by irradiating photosensitive materials with object waves and reference waves as described above.

[0006] Holographic optical elements manufactured in this way can be applied to vehicles such as head-up displays (HUDs) and can provide enhanced image light for driving to the user's eye box area, so that users such as drivers who want to visually recognize enhanced images (hereinafter referred to as users) can see the information needed for driving and the surrounding environment.

[0007] Therefore, enhancing the brightness of the image is important so that users can effectively view the enhanced image provided to the head-up display (HUD) even in bright daylight.

[0008] However, in the case of holographic optics used in conventional head-up displays (HUDs), an interference pattern is formed with a constant maximum diffraction efficiency angle, causing high-brightness light to be emitted only in specific directions. Therefore, a problem with holographic optics is that most of the high-brightness light is emitted outside the user's eye box area, thus reducing the brightness of the enhanced image.

[0009] In addition, among light emitted to a user's eyebox region by a holographic optical element used in a conventional head-up display (HUD), only light containing information about a specific portion of an augmented image has high luminance. Thus, the holographic optical element has a problem in that the augmented image viewed by the user has different luminance for each portion. SUMMARY

[0010] TECHNICAL PROBLEM

[0011] One object of the present disclosure is to solve a problem in that augmented image light emitted from a holographic optical element used in a head-up display (HUD) or the like cannot be effectively focused on a user's eyebox region.

[0012] Another object of the present disclosure is to solve a problem in that an augmented image provided to a user's eyebox region from a holographic optical element used in a head-up display (HUD) or the like does not have uniform luminance over the entire augmented image.

[0013] Still another object of the present disclosure is to solve a problem in that it is not easy to manufacture a holographic optical element capable of emitting augmented image light such that an augmented image provided to a user's eyebox region has uniform and high luminance.

[0014] The objects of the present disclosure are not limited to the above-mentioned objects, and other unmentioned objects will be clearly understood by those skilled in the art from the following description.

[0015] TECHNICAL SOLUTION

[0016] One embodiment of the present disclosure provides a method for manufacturing a holographic optical element, the method including: a 1st step of laminating a master on a substrate, the master being a diffractive optical element having an interference pattern formed on the master; a 2nd step of laminating a photosensitive material on the master, and recording the interference pattern of the master on the photosensitive material by irradiating the photosensitive material with an incident light beam at a predetermined incident angle; a 3rd step of manufacturing an optical element by separating the photosensitive material having the interference pattern recorded thereon from the master; a 4th step of manufacturing a plurality of optical elements by repeating the 2nd step and the 3rd step a predetermined number of times; and a 5th step of forming the holographic optical element by combining the plurality of optical elements, wherein the 4th step includes, in each repeated 2nd step, irradiating the photosensitive material with the incident light beam at a different incident angle such that the interference patterns recorded on the plurality of optical elements, respectively, have the same pitch and different tilt angles.

[0017] According to one embodiment of the present disclosure, the 4th step can include, in each 2nd step, irradiating the photosensitive material with the incident light beam after rotating the substrate by a predetermined angle.

[0018] According to one embodiment of the present disclosure, the fifth step can include combining the plurality of optical elements such that the tilt angles of the interference patterns recorded on the holographic optical elements gradually increase or decrease in a predetermined direction.

[0019] According to one embodiment of the present disclosure, the master can diffract the incident light beam to the photosensitive material when the incident angle of the incident light beam is between the first angle and the second angle, and, after the substrate is rotated, the photosensitive material can be irradiated with the incident light beam such that the incident angle of the incident light beam incident to the master is between the first angle and the second angle.

[0020] According to one embodiment of the present disclosure, the master can include a holographic optical element or a diffractive optical element having a surface relief grating formed thereon.

[0021] According to one embodiment of the present disclosure, the photosensitive material can be a photopolymer.

[0022] Another embodiment of the present disclosure provides a holographic optical element including a plurality of optical elements combined together, and in the holographic optical element, interference patterns respectively recorded on the plurality of optical elements have the same pitch and different tilt angles.

[0023] According to one embodiment of the present disclosure, the plurality of optical elements can be combined together such that the different tilt angles of the interference patterns gradually increase or decrease in a predetermined direction.

[0024] Another embodiment of the present disclosure provides an apparatus for manufacturing a holographic optical element, the apparatus including: a lamination unit configured to form a laminate by laminating a substrate, a master, and a photosensitive material in a predetermined order, the master being a diffractive optical element having an interference pattern formed thereon; a light beam irradiation unit configured to irradiate the photosensitive material with an incident light beam at a predetermined incident angle such that the interference pattern of the master is recorded on the photosensitive material; a rotation control unit configured to rotate at least one of the laminate and the light beam irradiation unit such that the predetermined incident angle of the incident light beam incident to the photosensitive material is controlled; a master removal unit configured to manufacture an optical element by separating the photosensitive material on which the interference pattern is recorded from the master; and a combination unit configured to combine a plurality of optical elements to form a holographic optical element.

[0025] According to one embodiment of the present disclosure, the rotation control unit can rotate at least one of the laminate and the light beam irradiation unit so as to irradiate the photosensitive material with the incident light beam at different incident angles, such that the interference patterns respectively recorded on the plurality of optical elements have the same pitch and different tilt angles.

[0026] According to one embodiment of the disclosure, the combining unit can combine the plurality of optical elements together such that the tilt angles of the interference patterns recorded on the holographic optical elements gradually increase or decrease in a predetermined direction.

[0027] Specific details of other embodiments for implementing these objectives are included in the following description of the disclosure and in the accompanying drawings.

[0028] Technical Effects

[0029] The holographic optical element according to the disclosure is formed by combining a plurality of optical elements on which interference patterns having the same pitch and different tilt angles are recorded, focuses light of an augmented image having high brightness, and emits it to a user's eyebox region, and thus provides an effect of enabling a user to see an augmented image having high brightness.

[0030] In addition, since the holographic optical element enables light containing information about each portion of an augmented image and having high brightness to be focused and uniformly emitted to a user's eyebox region, the holographic optical element provides an effect of enabling a user to see an augmented image having uniform brightness.

[0031] In addition, the method for manufacturing a holographic optical element according to the disclosure provides an effect of enabling a holographic optical element to be manufactured through a simple and convenient process, because the method manufactures a plurality of optical elements to be combined, on which interference patterns having the same pitch and different tilt angles are recorded, through simple repetition of rotating a master.

[0032] In addition, the apparatus for manufacturing a holographic optical element according to one embodiment of the disclosure provides an effect of enabling a holographic optical element to be manufactured in a large quantity in a simple and convenient manner, because the apparatus manufactures a plurality of optical elements to be combined, on which interference patterns having the same pitch and different tilt angles are recorded, through simple repetition of rotating a master. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 FIG. 1 is a flowchart illustrating a method for manufacturing a holographic optical element according to one embodiment of the disclosure.

[0034] Figure 2 FIG. 2 is a diagram illustrating a process of recording an interference pattern on a photosensitive material.

[0035] Figure 3 FIG. 3 is a graph showing a change in diffraction efficiency of an incident light beam incident to a master with respect to an incident angle of the incident light beam.

[0036] Figure 4(a) is a diagram showing the angle at which an incident beam is diffracted with maximum diffraction efficiency in multiple optical elements comprising an interference pattern with the same tilt angle.

[0037] Figure 4 (b) is a diagram showing the angle at which an incident beam is diffracted with maximum diffraction efficiency in multiple optical elements comprising interference patterns with different tilt angles.

[0038] Figure 5 (a) shows the combination of Figure 4 The diagram in (a) shows multiple optical elements and the enhanced image light emitted by conventional holographic optical elements to the user's eye box.

[0039] Figure 5 (b) illustrates a combination of embodiments according to this disclosure. Figure 4 The diagram in (b) shows the multiple optical elements that are used to obtain the enhanced image light emitted by the holographic optical elements to the user's eye box.

[0040] Figure 6 (a) shows the data visible to the user. Figure 5 An example of an enhanced image of (a).

[0041] Figure 6 (b) shows the data visible to the user. Figure 5 The figure shows an example of an enhanced image of (b).

[0042] Figure 7 This is a diagram illustrating a holographic optical element according to one embodiment of the present disclosure. Detailed Implementation

[0043] Preferred embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings and the following description. However, the present disclosure is not limited to the embodiments described herein and may be implemented in other forms. Throughout the specification, similar reference numerals refer to similar parts.

[0044] Hereinafter, a method for manufacturing a holographic optical element 1 according to one embodiment of the present disclosure will be described.

[0045] Figure 1 This is a flowchart illustrating a method for manufacturing a holographic optical element according to one embodiment of the present disclosure.

[0046] Reference Figure 1 and Figure 2According to one embodiment of the present disclosure, a method for manufacturing a holographic optical element 1 can include: a first step S100 of laminating a master 200 on a substrate 100; a second step S200 of recording an interference pattern on a photosensitive material; a third step S300 of manufacturing an optical element; a fourth step S400 of manufacturing a plurality of optical elements; and a fifth step S500 of forming a holographic optical element.

[0047] First, the first step S100 will be described.

[0048] The first step S100 is a step of laminating a master 200 on a substrate 100 made of glass or the like. In this case, the master 200 can be composed of a conventional holographic optical element (HOE) or a diffractive optical element (DOE) on which a surface relief grating is formed.

[0049] On the master 200, a master interference pattern 210 to be transferred and recorded on a holographic optical element to be manufactured can be formed.

[0050] Now, the second step S200 will be described.

[0051] The second step S200 is a step of recording an interference pattern 404, 405, or 406 (see (b) or (c) of FIG. 4) on a photosensitive material 300. Figure 4 Figure 7 ) on the photosensitive material 300.

[0052] The photosensitive material 300 is a material on which optical information can be recorded by exposure to light, and a conventional photosensitive material known in the field of holograms can be used. For example, the photosensitive material 300 can include a photopolymer, on which optical information can be recorded due to a difference in refractive index between an exposed portion and a non-exposed portion of the photopolymer.

[0053] Figure 2 is a diagram illustrating a process of recording an interference pattern on a photosensitive material.

[0054] Referring to Figure 2 , when the photosensitive material 300 is laminated on the master 200 and the photosensitive material 300 is irradiated with an incident light beam such as a laser beam, light incident to the master 200 through the photosensitive material 300 can be diffracted to the photosensitive material 300, in which the master 200 is laminated on the substrate 100. At this time, the light diffracted from the master 200 to the photosensitive material 300 can record an interference pattern 404, 405, or 406 (see (b) or (c) of FIG. 4) on the photosensitive material 300. Figure 4 Figure 7 ) on the photosensitive material 300.

[0055] Now, the third step S300 will be described.

[0056] ​​The third step S300 is a step of manufacturing optical elements 540, 550, or 560 by separating the photosensitive material 300 from the master 200 (see Figure 4 (b) of the above-described (a) or Figure 7 The photosensitive material 300 on which the interference pattern 404, 405, or 406 is recorded and separated from the master 200 can be referred to as the optical element 540, 550, or 560.

[0057] Now, the fourth step S400 will be described.

[0058] The fourth step S400 is a step of manufacturing a plurality of optical elements 540, 550, and 560 by repeating the second step S200 and the third step S300 a predetermined number of times. The number of the plurality of optical elements 540, 550, and 560 having the master interference pattern 210 transferred thereto can be the same as the number of repetitions of the second step S200 and the third step S300. In addition, in the fourth step S400, the plurality of optical elements 540, 550, and 560 can be produced so that the interference patterns 404, 405, or 406 recorded on the optical elements 540, 550, and 560 have the same pitch but different tilt angles.

[0059] For example, the plurality of optical elements 540, 550, and 560 on which the interference patterns 404, 405, or 406 having the same pitch and different tilt angles are formed can be produced by irradiating each of the photosensitive materials 300 laminated on the master 200 with the incident light beam at different incident angles.

[0060] Specifically, the master 200 and the photosensitive material 300 laminated on the substrate 100 can be irradiated with the incident light beam at different incident angles by rotating the substrate 100 by a predetermined angle.

[0061] First, when the first photosensitive material is irradiated with the incident light beam in a direction perpendicular to the plane of each of the master 200 and the first photosensitive material, a first interference pattern 404 having a tilt angle of θa can be recorded on the first photosensitive material.

[0062] In addition, when the substrate 100 on which the master 200 and the second photosensitive material are laminated is rotated by an angle clockwise and then the second photosensitive material is irradiated with the incident light beam, a second interference pattern 405 having a tilt angle of θb can be recorded on the second photosensitive material.

[0063] In addition, when the substrate 100 on which the master 200 and the third photosensitive material are laminated is rotated by an angle counterclockwise and then the third photosensitive material is irradiated with the incident light beam, a third interference pattern 406 having a tilt angle of θc can be recorded on the third photosensitive material.

[0064] In this case, the tilt angle θb of the second interference pattern 405 recorded on the second photosensitive material is larger than the tilt angle θa of the first interference pattern 404 recorded on the first photosensitive material, and the tilt angle θc of the third interference pattern 406 recorded on the third photosensitive material is larger than the tilt angle θb of the second interference pattern 405 recorded on the second photosensitive material.

[0065] Meanwhile, the diffraction efficiency of the incident light beam incident to the master 200 can vary according to the incident angle of the incident light beam.

[0066] Figure 3 is a graph showing the variation of the diffraction efficiency of the incident light beam incident to the master with the incident angle of the incident light beam.

[0067] Referring to Figure 3 For example, when the incident angle of the incident light beam incident to the master 200 is between the first angle and the second angle, the master 200 can diffract 90% or more of the incident light beam.

[0068] In order to effectively record the interference pattern 404, 405, or 406 on the photosensitive material 300, the incident light beam incident to the master 200 needs to be incident at an incident angle at which diffraction is efficient.

[0069] The rotation angle of the substrate 100 is the same as the incident angle of the incident light beam incident to the master 200. Thus, when the photosensitive material 300 is irradiated with the incident light beam after the substrate 100 is rotated in the 4th step S400, the substrate 100 is preferably rotated such that the rotation angle of the substrate 100 has a value within a range of the incident angle at which the incident light beam incident to the master 200 diffracts with high efficiency.

[0070] Now, the 5th step S500 will be described.

[0071] The 5th step S500 is a step of forming the holographic optical element 1 by combining the plurality of optical elements 540, 550, and 560 manufactured in the 4th step S400.

[0072] When the holographic optical element 1 is formed by combining the plurality of optical elements 540, 550, and 560, the plurality of optical elements 540, 550, and 560 can be combined with each other such that the tilt angles of the interference patterns recorded on the holographic optical element 1 gradually increase or decrease in a predetermined direction.

[0073] When the tilt angles of the interference patterns recorded on the holographic optical element 1 are configured to gradually increase or decrease in a predetermined direction as described above, the incident angle at which the incident light beam can be diffracted with the maximum efficiency (hereinafter referred to as "maximum diffraction efficiency angle") can vary according to the position of the holographic optical element 1.

[0074] Figure 4 FIG. 4 is a graph showing the maximum diffraction efficiency angle in a plurality of optical elements including interference patterns having the same tilt angle, according to an embodiment of the present disclosure.

[0075] Referring to Figure 4 FIG. 4, when the interference patterns 404, 405, and 406 respectively formed on the fourth optical element 540, the fifth optical element 550, and the sixth optical element 560 for manufacturing the holographic optical element 1 have the same pitch but different tilt angles, the fourth optical element 540, the fifth optical element 550, and the sixth optical element 560 have different maximum diffraction efficiency angles.

[0076] Specifically, when the fourth optical element 540 is irradiated with the first incident beam 10, the second incident beam 20, and the third incident beam 30, the diffraction efficiency of the first incident beam 10 can be the highest. In addition, when the fifth optical element 550 is irradiated with the first incident beam 10, the second incident beam 20, and the third incident beam 30, the diffraction efficiency of the second incident beam 20 can be the highest, the interference pattern 405 recorded on the fifth optical element 550 having a larger tilt angle than the interference pattern 404 of the fourth optical element 540.

[0077] Figure 4 FIG. 5 is a graph showing the maximum diffraction efficiency angle in a plurality of optical elements including interference patterns having different tilt angles, according to an embodiment of the present disclosure.

[0078] Referring to Figure 4 FIG. 5, when the interference patterns 404, 405, and 406 respectively formed on the fourth optical element 540, the fifth optical element 550, and the sixth optical element 560 for manufacturing the holographic optical element 1 have the same pitch but different tilt angles, the fourth optical element 540, the fifth optical element 550, and the sixth optical element 560 have different maximum diffraction efficiency angles.

[0079] Specifically, when the fourth optical element 540 is irradiated with the first incident beam 10, the second incident beam 20, and the third incident beam 30, the diffraction efficiency of the first incident beam 10 can be the highest. In addition, when the fifth optical element 550 is irradiated with the first incident beam 10, the second incident beam 20, and the third incident beam 30, the diffraction efficiency of the second incident beam 20 can be the highest, the interference pattern 405 recorded on the fifth optical element 550 having a larger tilt angle than the interference pattern 404 of the fourth optical element 540.

[0080] In addition, when the sixth optical element 560 is illuminated by the first incident beam 10, the second incident beam 20 and the third incident beam 30, the diffraction efficiency of the third incident beam 30 can be the highest, and the interference pattern 406 recorded on the sixth optical element 560 has a larger tilt angle than the interference pattern 405 of the fifth optical element 550.

[0081] A holographic optical element 1, which is generated by combining multiple optical elements 540, 550 and 560 to have different maximum diffraction efficiency angles depending on their positions, can be applied to vehicle head-up displays (HUDs), etc.

[0082] Figure 5 (a) shows the combination of Figure 4 The diagram in (a) shows multiple optical elements and the enhanced image light emitted by conventional holographic optical elements to the user's eye box.

[0083] For example, refer to Figure 5 (a), in Figure 5 The emitting side optical element 500-2 in (a) is formed by combining a first optical element 510, a second optical element 520 and a third optical element 530 on which interference patterns 401, 402 and 403 with the same spacing and the same tilt angle are respectively recorded.

[0084] When the first incident beam 10, the second incident beam 20, and the third incident beam 30 illuminate the incident-side optical element 500-1, the beams can reach the emitting-side optical element 500-2 through total internal reflection. When the diffraction efficiency of the second incident beam 20 is the highest among the diffraction efficiencies of the light reaching the first optical element 510 of the emitting-side optical element 500-2, the diffraction efficiency of the second incident beam 20 is also the highest among the diffraction efficiencies of the light reaching the second optical element 520 and the third optical element 530.

[0085] Therefore, in the light emitted from the emitting optical element 500-2, most of the light with maximum diffraction efficiency is emitted to the area outside the user's eyebox region. Additionally, in the light containing information about the enhanced image that flows into the user's eyebox, the second incident beam 20, containing only information about specific portions of the enhanced image, diffracts with maximum diffraction efficiency and is emitted into the user's eyebox.

[0086] Figure 5 (b) illustrates a combination of embodiments according to this disclosure. Figure 4 The diagram in (b) shows the multiple optical elements that are used to obtain the enhanced image light emitted by the holographic optical elements to the user's eye box.

[0087] Reference Figure 5 (b) Figure 5The emission-side optical element 500-4 in (b) is an element formed by combining a fourth optical element 540, a fifth optical element 550, and a sixth optical element 560 on which interference patterns 404, 405, and 406 having the same pitch but different tilt angles are respectively recorded.

[0088] When the emission-side optical element 500-3 is irradiated with the first incident light beam 10, the second incident light beam 20, and the third incident light beam 30, beam light can reach the emission-side optical element 500-4 by total reflection. In this case, the first incident light beam 10 can have the highest diffraction efficiency among those lights reaching the fourth optical element 540.

[0089] In addition, among the lights reaching the fifth optical element 550, the second incident light beam 20 can have the highest diffraction efficiency, and the fifth optical element 550 has the interference pattern 405 having a larger tilt angle than the interference pattern 404 of the fourth optical element 540 recorded thereon, and among the lights reaching the sixth optical element 560, the third incident light beam 30 can have the highest diffraction efficiency, and the sixth optical element 560 has the interference pattern 406 having a larger tilt angle than the interference pattern 405 of the fifth optical element 550 recorded thereon.

[0090] Therefore, among the light emitted from the emission-side optical element 500-4, the majority of light having the largest diffraction efficiency is emitted to the eyebox region of the user. In addition, among the light containing the augmented image information and flowing into the eyebox of the user, the first incident light beam 10, the second incident light beam 20, and the third incident light beam 30 containing information about each portion of the augmented image are uniformly diffracted and emitted to the eyebox region of the user with the largest diffraction efficiency.

[0091] Figure 6 (a) of FIG. 1 is a diagram illustrating an example of an augmented image according to Figure 5 (a) of FIG. 1.

[0092] Referring to Figure 6 (a) of FIG. 1, when only the second incident light beam 20 is diffracted and emitted to the eyebox of the user with the largest diffraction efficiency as illustrated in (a) of FIG. 1, the augmented image seen by the user has high luminance only in a specific portion thereof. Figure 5

[0093] Figure 6 (b) of FIG. 1 is a diagram illustrating an example of an augmented image according to Figure 5 (b) of FIG. 1.

[0094] Referring to Figure 6 (b) of FIG. 1, when only the second incident light beam 20 is diffracted and emitted to the eyebox of the user with the largest diffraction efficiency as illustrated in (b) of FIG. 1, the augmented image seen by the user has high luminance only in a specific portion thereof. Figure 7 ​the first incident beam 10, the second incident beam 20, and the third incident beam 30 shown in (b) are diffracted at maximum diffraction efficiency and uniformly emitted to the eyebox of the user, the augmented image seen by the user generally has higher brightness than Figure 7 the augmented image in (a), and has uniform and high brightness throughout the augmented image.

[0095] Hereinafter, a holographic optical element 1 according to one embodiment of the present disclosure will be described.

[0096] ​ is a diagram illustrating a holographic optical element according to one embodiment of the present disclosure.

[0097] Referring to ​ , the holographic optical element 1 according to one embodiment of the present disclosure is configured by combining a plurality of optical elements 540, 550, and 560, and the interference patterns 404, 405, and 406 recorded on the optical elements 540, 550, and 560, respectively, can have the same pitch but different tilt angles.

[0098] In addition, the plurality of optical elements 540, 550, and 560 can be combined together such that the tilt angles of the interference patterns 404, 405, and 406 gradually increase or decrease in a predetermined direction.

[0099] Specifically, since the plurality of optical elements constituting the holographic optical element 1 are combined together such that the tilt angles of the interference patterns recorded on the optical elements gradually increase or decrease, the optical elements have different angles at which the efficiency of diffraction of light by the optical elements reaches a maximum value, and thus most of the light having the maximum diffraction efficiency in the emitted light is emitted to the eyebox region of the user, thereby improving the brightness of the augmented image.

[0100] On the other hand, when the optical elements are combined together such that the tilt angles of the interference patterns recorded on the optical elements do not have a tendency to gradually increase or decrease, the light having the maximum diffraction efficiency in the emitted light is not emitted to the eyebox region of the user, and thus the brightness of the augmented image decreases.

[0101] Meanwhile, although the holographic optical element 1 according to one embodiment of the present disclosure can be manufactured by the method for manufacturing the holographic optical element 1 according to the above-described embodiment of the present disclosure, the holographic optical element 1 can be manufactured by other methods.

[0102] Hereinafter, the operation and effects of the holographic optical element 1 of the present disclosure and the manufacturing method for the holographic optical element 1 will be described in detail.

[0103] First, a master 200 that is a diffractive optical element is laminated on a substrate 100, and a photosensitive material 300 is laminated on the master 200. Then, an interference pattern 404, 405, or 406 is recorded on the photosensitive material 300 by irradiating the photosensitive material 300 with an incident light beam. Then, the optical element 540, 550, or 560 is manufactured by separating the photosensitive material 300 on which the interference pattern 404, 405, or 406 is recorded from the master 200.

[0104] In addition, the above process is repeated by laminating another photosensitive material 300 on the master 200, rotating the master 200, irradiating the photosensitive material with an incident light beam at different incident angles, and separating the photosensitive material 300 on which the interference pattern 404, 405, or 406 is recorded from the master 200 to manufacture the optical element 540, 550, or 560.

[0105] The interference patterns 404, 405, or 406 recorded on the manufactured plurality of optical elements 540, 550, and 560 have the same pitch and different tilt angles. The holographic optical element 1 is manufactured by combining the plurality of optical elements 540, 550, and 560.

[0106] In this case, the plurality of optical elements 540, 550, and 560 are combined together such that the tilt angles of the interference patterns 404, 405, or 406 recorded on the holographic optical element 1 gradually increase or decrease in a predetermined direction.

[0107] When the holographic optical element 1 manufactured in this method is applied to a vehicle head-up display (HUD) or the like, by the holographic optical element 1, light containing information about each portion of an augmented image will be diffracted with maximum diffraction efficiency uniformly, and focused and emitted to a user's eyebox region, because the holographic optical element 1 has different maximum diffraction efficiency angles of light depending on its position.

[0108] Since the holographic optical element according to the present disclosure is formed by combining a plurality of optical elements on which interference patterns having the same pitch and different tilt angles are recorded, the holographic optical element focuses light of an augmented image having high brightness and emits it to a user's eyebox region, and thus provides an effect of enabling a user to see an augmented image having high brightness.

[0109] In addition, since the holographic optical element enables light containing information about each portion of an augmented image and having high brightness to be focused and emitted to a user's eyebox region uniformly, the holographic optical element provides an effect of enabling a user to see an augmented image having uniform brightness.

[0110] In addition, the method for manufacturing a holographic optical element according to the present disclosure provides an effect of enabling the holographic optical element to be manufactured through a simple and convenient process, because the method manufactures a plurality of optical elements to be combined on which interference patterns having the same pitch and different tilt angles are recorded through simple repetition of rotating the master.

[0111] Hereinafter, an apparatus for manufacturing a holographic optical element according to one embodiment of the present disclosure will be described.

[0112] Another embodiment of the present disclosure provides an apparatus for manufacturing a holographic optical element, the apparatus including: a lamination unit configured to form a laminate by laminating a substrate, a master, and a photosensitive material in a predetermined order, the master being a diffractive optical element on which an interference pattern is formed; a light beam irradiation unit configured to irradiate the photosensitive material with an incident light beam at a predetermined incident angle such that the interference pattern of the master is recorded on the photosensitive material; a rotation control unit configured to rotate at least one of the laminate and the light beam irradiation unit such that the incident angle of the incident light beam incident to the photosensitive material is controlled; a master removal unit configured to manufacture an optical element by separating the photosensitive material on which the interference pattern is recorded from the master; and a combination unit configured to combine a plurality of optical elements to form a holographic optical element.

[0113] The apparatus for manufacturing a holographic optical element according to one embodiment of the present disclosure provides an effect of enabling the holographic optical element to be manufactured in a large quantity in a simple and convenient manner, because the apparatus manufactures a plurality of optical elements to be combined on which interference patterns having the same pitch and different tilt angles are recorded through simple repetition of rotating the master.

[0114] According to one embodiment of the present disclosure, the apparatus includes a lamination unit configured to form a laminate by laminating a substrate, a master, and a photosensitive material in a predetermined order, the master being a diffractive optical element having an interference pattern formed thereon. Specifically, the laminate can be formed by laminating the master, which is a diffractive optical element having an interference pattern formed thereon, on the substrate, and laminating the photosensitive material on a surface of the master opposite to the surface of the master in contact with the substrate. More specifically, the laminate can be formed by laminating the substrate, the master, and the photosensitive material in this order. Since the substrate is rotated as much as the laminate is rotated, the laminate can be rotated to control the incident angle of the incident light beam, as will be described later. In addition, as will be described later, when the photosensitive material is irradiated with the incident light beam, an interference pattern can be recorded on the photosensitive material by interference occurring between light passing through the photosensitive material and light diffracted by the master. Since the apparatus includes the lamination unit configured to form the laminate by laminating the substrate, the master, and the photosensitive material in the predetermined order, the master being the diffractive optical element having the interference pattern formed thereon, as described above, the apparatus can easily form the laminate. In addition, when the substrate is rotated, the incident angle of the incident light beam can be controlled by rotating the entire laminate, and the interference pattern of the master can be transferred and recorded on the photosensitive material.

[0115] According to one embodiment of the present disclosure, the apparatus includes a light beam irradiation unit configured to irradiate the photosensitive material with the incident light beam at a predetermined incident angle such that the interference pattern of the master is recorded on the photosensitive material. Specifically, the light beam irradiation unit is a device for outputting the incident light beam, and enables the predetermined incident angle of the incident light beam to be formed incident to the photosensitive material such that the interference pattern generated by interference between light passing through the photosensitive material and light diffracted by the master after irradiation of the incident light beam can be recorded on the photosensitive material. The light beam irradiation unit can be used without limitation as long as it corresponds to a light irradiation device used in the field of manufacturing a holographic optical element. As described above, since the apparatus includes the light beam irradiation unit configured to irradiate the photosensitive material with the incident light beam at the predetermined incident angle such that the interference pattern of the master is recorded on the photosensitive material, the light beam irradiation unit can easily control the tilt angle of the incident light beam by interacting with the rotation control unit as will be described below, and can easily control the incident angle of the recorded interference pattern.

[0116] According to one embodiment of the present disclosure, the apparatus includes a rotation control unit configured to rotate at least one of the laminated body and the beam irradiation unit such that a predetermined incident angle of an incident beam to the photosensitive material is controlled. Specifically, the rotation control unit rotates the laminated body, or rotates the beam irradiation unit, or rotates both the laminated body and the beam irradiation unit, thereby controlling the incident angle of the incident beam to the photosensitive material. When the incident angle is controlled, the path of the light passing through the photosensitive material and the path of the light diffracted by the master are changed, so that the tilt angle of the interference pattern can be controlled while the pitch of the interference pattern recorded on the photosensitive material does not change. Since the apparatus includes the rotation control unit configured to rotate at least one of the laminated body and the beam irradiation unit such that the incident angle of the incident beam to the photosensitive material is controlled as described above, the tilt angle of the interference pattern can be changed while the pitch of the interference pattern recorded on the photosensitive material does not change.

[0117] According to one embodiment of the present disclosure, the apparatus includes a master removal unit configured to manufacture an optical element by separating the photosensitive material on which the interference pattern is recorded from the master. Specifically, the master removal unit can manufacture the optical element by separating the master or the structure including the master laminated on the substrate from the photosensitive material after the interference pattern is recorded on the photosensitive material.

[0118] Since the apparatus includes the master removal unit configured to manufacture the optical element by separating the photosensitive material on which the interference pattern is recorded from the master, the apparatus can manufacture the optical element and prevent the path of the light from being changed by the master in the reproduction process.

[0119] According to one embodiment of the present disclosure, the laminated body is formed by the laminating unit, and then the beam irradiation unit or the laminated body is rotated by the rotation control unit according to the tilt angle of the interference pattern to be recorded, thereby controlling the incident angle of the incident beam, and the interference pattern is recorded, and then the master is removed by the master removal unit, thereby manufacturing the optical element. The above-described process is repeated, thereby manufacturing a plurality of optical elements in which the interference patterns have the same pitch but have different tilt angles. When a plurality of optical elements are manufactured as described above, a holographic optical element in which the tilt angle of the interference pattern tends to change in a predetermined direction can be implemented.

[0120] According to one embodiment of the present disclosure, the apparatus includes a combination unit configured to combine a plurality of optical elements to form a holographic optical element. Specifically, the combination unit can arrange and combine a plurality of optical elements manufactured as described above. Since the apparatus includes the combination unit configured to combine a plurality of optical elements to form the holographic optical element as described above, the apparatus can implement a holographic optical element in which the tilt angle of the interference pattern recorded thereon tends to change in a predetermined direction.

[0121] According to one embodiment of the present disclosure, the rotation control unit can rotate at least one of the laminated body and the beam irradiation unit so as to irradiate the photosensitive material with the incident light beam at different incident angles such that the interference patterns respectively recorded on the optical elements have the same pitch and different tilt angles. Specifically, the rotation control unit rotates the laminated body, or rotates the beam irradiation unit, or rotates both the laminated body and the beam irradiation unit, thereby controlling the incident angle of the incident light beam incident to the photosensitive material. When the incident angle is controlled, the path of the light passing through the photosensitive material and the path of the light diffracted by the master are changed, so that the tilt angle of the interference pattern can be controlled while the pitch of the interference pattern recorded on the photosensitive material does not change. The rotation control unit rotates at least one of the laminated body and the beam irradiation unit so as to irradiate the photosensitive material with the incident light beam at different incident angles such that the interference patterns respectively recorded on the optical elements have the same pitch and different tilt angles. Accordingly, an optical element having different tilt angles of various patterns can be manufactured.

[0122] According to one embodiment of the present disclosure, the combination unit can combine the plurality of optical elements together such that the tilt angles of the interference patterns recorded on the holographic optical elements gradually increase or decrease in a predetermined direction. Since the combination unit can combine the plurality of optical elements together such that the tilt angles of the interference patterns recorded on the holographic optical elements gradually increase or decrease in a predetermined direction as described above, the combination unit can focus light of an enhanced image having high brightness and emit it to the eyebox region of the user, thereby providing an effect of enabling the user to see the enhanced image having high brightness.

[0123] As described above, since the holographic optical element according to the present disclosure is formed by combining a plurality of optical elements on which interference patterns having the same pitch and different tilt angles are recorded, the holographic optical element focuses light of an enhanced image having high brightness and emits it to the eyebox region of the user, and thus provides an effect of enabling the user to see the enhanced image having high brightness.

[0124] In addition, since the holographic optical element enables light containing information about each portion of the enhanced image and having high brightness to be focused and uniformly emitted to the eyebox region of the user, the holographic optical element provides an effect of enabling the user to see the enhanced image having uniform brightness.

[0125] In addition, the method for manufacturing a holographic optical element according to the present disclosure provides an effect of enabling the holographic optical element to be manufactured through a simple and convenient process, since the method manufactures a plurality of optical elements to be combined, on which interference patterns having the same pitch and different tilt angles are recorded, by simple repetition of rotating a master.

[0126] In addition, the apparatus for manufacturing a holographic optical element according to the present disclosure provides an effect of enabling the holographic optical element to be manufactured in a large quantity in a simple and convenient manner, because the apparatus manufactures a plurality of optical elements to be combined by simple repetition of rotating the master, the optical elements having interference patterns with the same pitch and different tilt angles recorded thereon.

[0127] Although the present disclosure has been described in detail above with reference to the representative embodiments, it will be understood by those of ordinary skill in the art that various modifications can be made to the above-described embodiments without departing from the scope of the present disclosure. Accordingly, the scope of the present disclosure should not be limited to the described embodiments, but should be defined by all variations or modifications derived from the appended claims and their equivalents.

[0128] List of Reference Numerals

[0129] 1: holographic optical element

[0130] 10: first incident light beam

[0131] 20: second incident light beam

[0132] 30: third incident light beam

[0133] 100: substrate 200: master

[0134] 210: master interference pattern

[0135] 300: photosensitive material

[0136] 404, 405, or 406: interference pattern 540, 550, or 560: optical element

Claims

1. A method for manufacturing a holographic optical element, the method comprising: Step 1: Lay a master plate on a substrate, the master plate being a diffractive optical element having an interference pattern formed on the master plate; Step 2: A photosensitive material is laminated onto the master plate, and the interference pattern of the master plate is recorded on the photosensitive material by irradiating the photosensitive material with an incident light beam at a predetermined incident angle; Step 3: To manufacture an optical element by separating the photosensitive material having the interference pattern recorded on the photosensitive material from the master plate; Step 4: Fabricate multiple optical elements by repeating Step 2 and Step 3 a predetermined number of times; as well as Step 5: The holographic optical element is formed by combining multiple of the aforementioned optical elements together. The fourth step includes: in each repeated second step, irradiating the photosensitive material with an incident beam at different incident angles, such that the interference patterns recorded on the plurality of optical elements have the same spacing and different tilt angles.

2. The method according to claim 1, wherein, The fourth step includes: in each of the second steps, after rotating the substrate by a predetermined angle, irradiating the photosensitive material with an incident light beam.

3. The method according to claim 2, wherein, The fifth step includes combining a plurality of the optical elements together such that the different tilt angles of the interference pattern recorded on the holographic optical elements gradually increase or decrease in a predetermined direction.

4. The method according to claim 3, wherein, When the predetermined incident angle of the incident light beam is between a first angle and a second angle, the master plate diffracts the incident light beam onto the photosensitive material, and After the substrate is rotated, the photosensitive material is irradiated with the incident light beam such that the predetermined incident angle of the incident light beam incident on the master is between the first angle and the second angle.

5. The method according to claim 4, wherein, The master template includes a holographic optical element or a diffractive optical element, wherein the diffractive optical element has a surface relief grating formed on the diffractive optical element.

6. The method according to claim 1, wherein, The photosensitive material is a photopolymer.

7. An apparatus for manufacturing holographic optical elements, the apparatus comprising: A laminating unit configured to form a laminate by laminating a substrate, a master and a photosensitive material in a predetermined order, wherein the master is a diffractive optical element having an interference pattern formed on the diffractive optical element; A beam illumination unit is configured to illuminate the photosensitive material with an incident beam at a predetermined incident angle, such that the interference pattern of the master is recorded on the photosensitive material. A rotation control unit configured to rotate at least one of the laminate and the beam irradiation unit, such that the predetermined incident angle of the incident beam incident on the photosensitive material is controlled; A master removal unit is configured to manufacture an optical element by separating the photosensitive material from the master, the photosensitive material having the interference pattern recorded thereon; as well as A combining unit, configured to combine multiple optical elements together to form the holographic optical element. The rotation control unit rotates at least one of the laminate and the beam irradiation unit so that the incident beam irradiates the photosensitive material at different incident angles, such that the interference patterns recorded on the plurality of optical elements have the same spacing and different tilt angles.

8. The device according to claim 7, wherein, The combination unit combines multiple different optical elements together such that the tilt angle of the interference pattern recorded on the holographic optical element gradually increases or decreases in a predetermined direction.

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