Near-eye display for augmented reality haivng polygon-curved waveguide holographic combiner and operating method of the same

Abstract

The present disclosure provides a near-eye display for augmented reality having a polygon-curved optical waveguide holographic coupler and a method of operating the same. In the present disclosure, the near-eye display for augmented reality comprises at least one source and a curved optical waveguide disposed in front of at least one of a user's right eye and left eye, which replicates light from the source by internally reflecting it through at least one of two ends and outputs the replicated light for at least one of the right eye and left eye, and the curved optical waveguide may be a polygon-curved optical waveguide having a plurality of planes disposed at points where the light is totally reflected.

Description

Technology Field

[0001] The present disclosure generally relates to a near-eye display for augmented reality (AR) having a polygon-curved optical waveguide holographic coupler for a large field of view (FOV) and a method of operating the same, and more specifically, to a near-eye display for augmented reality having a polygon-curved optical waveguide holographic coupler utilizing a polygonal symmetric structure to solve the convergence distortion problem on a curved surface and a method of operating the same. Background Technology

[0002] Many companies are unveiling mixed reality (XR) devices for the metaverse and spatial computing. In particular, near-eye displays for augmented reality utilizing flat waveguides are predominant, but the reality is that there are many challenges to overcome for commercialization. Near-eye displays (NEDs) can collectively refer to glasses or head-mount displays (HMDs) worn on a user's face or head, or augmented reality glasses in the form of contact lenses that come into direct contact with the user's eyeball. Although near-eye displays for augmented reality using flat waveguides offer a wider field of view and eyebox compared to other optical structures for augmented reality, a larger field of view is required to enhance the user's immersive experience, necessitating structural innovation in flat waveguides.

[0003] Most planar optical waveguides consist of in-couplers, expanders, and out-couplers. In-couplers and out-couplers are optical elements that diffract light at an angle capable of total internal reflection and have the same grating structure. The expander serves to bend the light totally reflected through the in-coupler in a vertical direction, and the size of the grating structures of the in-coupler and out-coupler is It is about that long.

[0004] Recently, active research has been conducted on near-eye displays for augmented reality utilizing curved waveguides (also referred to as curved waveguides) instead of conventional planar waveguides to enhance the field of view. Specifically, research is underway to achieve an enlarged eye box effect by emitting light in the same direction as the incident light after the outcoupler, similar to conventional planar waveguides, thereby limiting the field of view. Additionally, research is being conducted to utilize the curvature of the curved waveguide to focus light toward the user's eyes, thereby increasing the field of view while reducing the eye box. Furthermore, research is being conducted on projecting holograms onto planar waveguides to achieve a wide field of view. However, the phenomenon of light convergence caused by the curvature of the curved surface during total internal reflection within the curved waveguide is becoming a problem. The problem to be solved

[0005] The present disclosure provides a near-eye display for augmented reality that maximizes a wide field of view by converging light toward the user's eye using a curved optical waveguide, and a method of operating the same.

[0006] The present disclosure provides a near-eye display for augmented reality having a polygon-curved optical waveguide holographic coupler utilizing a polygonal symmetric structure to compensate for distortion caused by the curvature of a curved surface, and a method of operating the same. means of solving the problem

[0007] In the present disclosure, a near-eye display for augmented reality comprises at least one source and a curved optical waveguide positioned in front of at least one of a user's right eye and left eye, which replicates light from the source by internally reflecting it through at least one of two ends and outputs the replicated light to at least one of the right eye and left eye, wherein the curved optical waveguide may be a polygon-curved optical waveguide having a plurality of flat surfaces positioned at points where the light is totally reflected.

[0008] In the present disclosure, a method of operating a near-eye display for augmented reality comprises the steps of: at least one source causing light to be incident through at least one of two ends of a curved optical waveguide positioned in front of at least one of the right eye and left eye of a user; and the curved optical waveguide replicating the light from the source while internally reflecting it, and outputting the replicated light to at least one of the right eye and left eye, wherein the curved optical waveguide may be a polygon-curved optical waveguide having a plurality of planes positioned at points where the light is totally reflected. Effects of the invention

[0009] According to the present disclosure, a polygon-curved optical waveguide holographic coupler can provide a user with high degrees of freedom of the eye and a large field of view by utilizing a polygon-curved optical waveguide. Specifically, light can be identically replicated within the polygon-curved optical waveguide without convergence distortion caused by the curvature of the curved surface of the curved optical waveguide, and light can be output as a planar wave from the polygon-curved optical waveguide. Thus, a polygon-curved optical waveguide holographic coupler using a polygon-curved optical waveguide will serve as a structure for improving the user's immersive experience. Furthermore, since the polygon-curved optical waveguide can be manufactured by milling the curved surface of the curved optical waveguide into a plane, only the design of three diffraction gratings—namely, an incoupler, an expander, and an outcoupler—is required to manufacture the polygon-curved optical waveguide holographic coupler. Therefore, the manufacturing process of the polygon-curved optical waveguide holographic coupler is easy. Brief explanation of the drawing

[0010] Figure 1 is a diagram illustrating a typical curved optical waveguide. FIG. 2 is a drawing illustrating a polygon-curved optical waveguide holographic coupler for a near-eye display for augmented reality according to various embodiments. Figure 3 is a diagram showing the propagation path of light in a polygon-curved optical waveguide when the polygon-curved optical waveguide holographic coupler of Figure 2 includes two sources. FIG. 4 is a diagram showing an example of a polygon-curved optical waveguide holographic coupler of FIG. 2 and the propagation of light in it. Figure 5 is a diagram showing another example of the polygon-curved optical waveguide holographic coupler of Figure 2 and the propagation of light therein. Figures 6 and 7 illustrate a computer-generated holography (CGH) algorithm for designing a polygon-curved optical waveguide holography coupler of Figure 1. FIG. 8 is a diagram illustrating the operation method of a near-eye display for augmented reality according to various embodiments. Specific details for implementing the invention

[0011] In the following, the present disclosure provides a near-eye display for augmented reality having a polygon-curved optical waveguide holographic coupler and a method of operating the same. A curved optical waveguide has a larger angle at which light can be focused toward the eye compared to a flat optical waveguide of the same size. Furthermore, when considering the unit pixel diffraction angle of a virtual display generated by replication in the two types of optical waveguides, the diffraction angle of a unit pixel located at the end of a flat optical waveguide must be bent at a high angle to focus light toward the eye, whereas in a curved optical waveguide, the degree of bending can be mitigated due to the curvature. This serves as the basis for securing a wider field of view for the curved optical waveguide than for the flat optical waveguide. Additionally, this is a process-advantageous factor compared to the high-diffraction diffraction grating of a flat optical waveguide.

[0012] In a curved optical waveguide, light incident as a plane wave converges as it undergoes total internal reflection due to the curvature of the curved surface of the curved optical waveguide. This is because, due to the characteristics of the optical waveguide, the same diffraction grating is used for the incoupler and the outcoupler. Since operation requires maintaining the collimation of the light incident on the diffraction grating and matching the direction of the light designed on the grating, convergence distortion becomes a significant problem in the curved optical waveguide. To solve this, the present disclosure can prevent convergence distortion from occurring during internal total internal reflection by converting the curved surface into a polygonal structure.

[0014] Hereinafter, various embodiments of the present disclosure are described with reference to the accompanying drawings.

[0015] Figure 1 is a drawing illustrating a typical curved optical waveguide (10).

[0016] Referring to FIG. 1, in a general curved optical waveguide (10), light is incident as a plane wave and can be repeatedly totally reflected inside. At this time, the curved optical waveguide (10) may have a first curved surface (11) that is concave with respect to the light traveling inside the curved optical waveguide (10), and a second curved surface (13) that is convex with respect to the light traveling inside the curved optical waveguide (10). However, due to the curvature of the first curved surface (11) and the curvature of the second curved surface (13), the light may repeatedly converge and diverge while totally reflecting. This can, consequently, lead to convergence distortion. That is, distorted light with astigmatism, rather than a plane wave, may be output from the curved optical waveguide (10). This acts as an aberration in augmented reality imaging, such as holographic reconstruction or Maxwellian view, and becomes a major obstacle to applying the curved optical waveguide (10) to the optical system for augmented reality.

[0017] FIG. 2 is a drawing illustrating a polygon-curved optical waveguide holographic coupler of a near-eye display (100) for augmented reality according to various embodiments. FIG. 3 is a drawing showing the path of light in a polygon-curved optical waveguide (120) when the polygon-curved optical waveguide holographic coupler of FIG. 2 includes two sources (110).

[0018] Referring to FIG. 2, a polygon-curved waveguide holographic coupler of a near-eye display (100) for augmented reality according to various embodiments may be positioned in front of at least one eye (E) of a user, i.e., either the right eye or the left eye, so that the user can observe a virtual image through the polygon-curved waveguide holographic coupler. In this case, the polygon-curved waveguide holographic coupler may be implemented to compensate for convergence distortion using symmetric reflection so that even if light is incident as a plane wave, it can propagate as a plane wave without distortion due to total internal reflection. To this end, the near-eye display (100) may include at least one source (110), a polygon-curved waveguide (PCW) (120), at least one incoupler (130), an expander (140), and at least one outcoupler (150). In particular, the near-eye display (100) can be designed with a computer generated holography (CGH) algorithm according to the purpose of the near-eye display (100). Here, a plane (XY) including the viewing direction of the eyeball (E) and a direction (Z) perpendicular to said plane can be defined.

[0019] A source (110) can cause light to be incident on a polygon-curved optical waveguide (120). To do this, the source (110) may be positioned adjacent to one of the two ends of the polygon-curved optical waveguide (120). In one embodiment, when a polygon-curved optical waveguide holographic coupler is positioned in front of the right eye, at least one source (110) may be positioned adjacent to one end of the polygon-curved optical waveguide (120) on the right eye side of the user to cause light to be incident on one end of the polygon-curved optical waveguide (120). In another embodiment, when a polygon-curved optical waveguide holographic coupler is positioned in front of the left eye, at least one source (110) is positioned adjacent to the other end of the polygon-curved optical waveguide (120) on the user's left eye side so as to cause light to be incident on the other end of the polygon-curved optical waveguide (120). In yet another embodiment, the sources (110) are each positioned adjacent to both ends of the polygon-curved optical waveguide (120) so as to cause light to be incident on both ends of the polygon-curved optical waveguide (120).

[0020] The polygon-curved optical waveguide (120) may be positioned in front of the user's eye (E), that is, at least one of the right or left eye. At this time, the polygon-curved optical waveguide (120) may be concavely curved with respect to the eye (E) on a plane (XY) that includes the viewing direction of the eye (E). The polygon-curved optical waveguide (120) may replicate light from a source (110) by internally reflecting it through at least one of its two ends, and output the replicated light to the eye (E). Here, the light from the source (110) may travel along a zigzag path within the polygon-curved optical waveguide (120). At this time, there may be points (P1, P2) in the polygon-curved optical waveguide (120) where the light from the source (110) is totally reflected. In one embodiment, when two sources (110), namely a first source and a second source, are each positioned adjacent to one end of a polygon-curved optical waveguide (120), as illustrated in FIG. 3, light from the sources (110) may each travel along zigzag paths that do not intersect each other within the polygon-curved optical waveguide (120). Here, in the polygon-curved optical waveguide (120), there may be points (P1, P2) where light from the second source is totally reflected between points (P1, P2) where light from the first source is totally reflected.

[0021] Specifically, the polygon-curved optical waveguide (120) may have a first surface (121) that is concave for light traveling inside the polygon-curved optical waveguide (120), and a second surface (123) that is convex for light traveling inside the polygon-curved optical waveguide (120). When incident from a source (110), light may be repeatedly totally reflected on the first surface (121) and the second surface (123). Thus, first points (P1) where light is totally reflected may be distributed on the first surface (121), and second points (P2) where light is totally reflected may be distributed on the second surface (123). At the second points (P2) distributed on the second surface (123), light may not only be totally reflected but may also be output to the eyeball (E). In one embodiment, when a polygon-curved optical waveguide holographic coupler is positioned in front of the right eye and the left eye, light can be output to the right eye at second points (P2) distributed on the right side of the second surface (123) with respect to an axis passing through the center of the polygon-curved optical waveguide (120) and parallel to the plane (XY) containing the viewing direction of the right eye and the left eye, and light can be output to the left eye at second points (P2) distributed on the left side of the second surface (123).

[0022] In various embodiments, the polygon-curved optical waveguide (120) may have a plurality of planes. Here, each plane may be formed, for example, as a polygon. The planes are each placed at points (P) where light is totally reflected in the polygon-curved optical waveguide (120) to compensate for convergence distortion caused by the curvature of the curved surface of the curved optical waveguide. That is, the first surface (121) and the second surface (123) may be composed of a plurality of planes. Thus, the first surface (121) and the second surface (123) may be implemented as a polygonal structure. In this case, the polygon-curved optical waveguide (120) may be designed so that light is symmetrically reflected at the planes. Planes are each positioned at different angles to compensate for convergence distortion caused by the curvature of the curved surface of the curved optical waveguide at each of the points (P), and can be connected at angles rotated considering the radius of curvature (radius; R) of the curved optical waveguide. Planes may include first planes and second planes. First planes are each positioned at first points (P1) on the first surface (121) to compensate for convergence distortion caused by the curvature of the first surface (121). Second planes are each positioned at second points (P2) on the second surface (123) to compensate for convergence distortion caused by the curvature of the second surface (123). For example, the first planes and the second planes may be arranged to face each other in a one-to-one manner, and the first and second planes facing each other may be positioned at the same angle.

[0023] An incoupler (130) may be positioned at least one of the two ends of the polygon-curved optical waveguide (120). The incoupler (130) may cause light from a source (110) to be incident on the polygon-curved optical waveguide (120). In one embodiment, when the polygon-curved optical waveguide holographic coupler is positioned in front of the right eye, one incoupler (130) may be positioned at one end of the polygon-curved optical waveguide (120) on the right eye side of the user to provide light to one end of the polygon-curved optical waveguide (120). In another embodiment, when the polygon-curved optical waveguide holographic coupler is positioned in front of the left eye, one incoupler (130) may be positioned at the other end of the polygon-curved optical waveguide (120) on the user's left eye side to provide light to the other end of the polygon-curved optical waveguide (120). In yet another embodiment, when the polygon-curved optical waveguide holographic coupler is positioned in front of both the right and left eyes, two incouplers (130) may be positioned at both ends of the polygon-curved optical waveguide (120) on the user's right eye side and left eye side, respectively, to provide light to both ends of the polygon-curved optical waveguide (120).

[0024] An expander (140) (shown in FIG. 4) may be positioned adjacent to an incoupler (130) with respect to a polygon-curved optical waveguide (120). For example, the expander (140) may be positioned in the upper region of the polygon-curved optical waveguide (120) where the incoupler (130) is not positioned. The expander (140) may bend light incident through the incoupler (130) in a vertical direction (Z) while totally reflecting it into the polygon-curved optical waveguide (120). Thus, the polygon-curved optical waveguide (120) can replicate light from the expander (140) while totally reflecting it internally.

[0025] The outcoupler (150) may be positioned adjacent to the expander (140) with respect to the polygon-curved optical waveguide (120). For example, the outcoupler (140) may be positioned in the lower region of the polygon-curved optical waveguide (120) where the incoupler (130) is not positioned, i.e., below the expander (140). The outcoupler (150) may output the light duplicated from the polygon-curved optical waveguide (120).

[0026] At this time, the incoupler (130), expander (140), and outcoupler (150) can be designed as binary diffractive optional optical elements (BDOE).

[0027] In this way, the polygon-curved optical waveguide (120) can cause light with the same angle to propagate to the outcoupler (150) through symmetric reflection of diffracted light from the incoupler (130). Thus, in the polygon-curved optical waveguide holographic coupler, light can be output without distortion in the designed direction. In other words, light is identically replicated inside the polygon-curved optical waveguide (120) without convergence distortion caused by the curvature of the curved surface of the curved optical waveguide, and light can be output as a planar wave from the polygon-curved optical waveguide (120). At this time, it is important to design the light so that when it is diffracted from the incoupler (120) and reflected onto the first surface (121) of the polygon-curved optical waveguide (120), the light reaches the normal vector of the curved surface; that is, the key idea for the polygon-curved optical waveguide (120) is to ensure that the light accurately reaches the center of each plane so that incidence and reflection occur symmetrically. Through this, the convergence distortion problem that occurs in the curved optical waveguide is resolved. In addition, as shown in FIGS. 2 and 3, light output from the second planes of the second surface (123) of the polygon-curved optical waveguide (120) converges to one place, and by utilizing this principle, a large horizontal viewing angle can be secured.

[0028] FIG. 4 is a diagram showing an example of a polygon-curved optical waveguide holographic coupler of FIG. 2 and the propagation of light in it. Here, FIG. 4 (a) is a perspective view and FIG. 4 (b) is a side view.

[0029] Referring to FIG. 4, the polygon-curved optical waveguide (120) may include a first part (421) and a second part (423). For example, the first part (421) and the second part (423) may be arranged vertically along a direction (Z) perpendicular to the plane (XY). One incoupler (130) and an expander (140) may be placed in the first part (421). The second part (423) may replicate the light bent through the expander (140) by total reflection, and one outcoupler (150) may be placed in the second part (423). The incoupler (130), the expander (140), and the outcoupler (150) may be placed on a second surface (123). Here, the thickness of the first part (421) and the thickness of the second part (423) can be determined according to the purpose in the polygon-curved optical waveguide holographic coupler. In particular, the diffraction angle in the incoupler (130) can be determined by the polygonal structure center of the polygon-curved optical waveguide (120), and the design degrees of freedom for the diffraction angle in the incoupler (130) can be determined by the thickness of the first part (421). Accordingly, the distribution of planes is calculated to perform the desired function on each surface (121, 123) of the first part (421) and the second part (423), so that the polygon-curved optical waveguide holographic coupler can be implemented to resolve convergence distortion.

[0030] Two sources (110), namely the first source and the second source, are each positioned adjacent to one end of the polygon-curved optical waveguide (120), and the polygon-curved optical waveguide (120) can be positioned in front of the user's eyeball (E). At this time, the polygon-curved optical waveguide (120) can be concavely curved with respect to the eyeball (E) on a plane (XY) that includes the viewing direction of the eyeball (E). The polygon-curved optical waveguide (120) can replicate light from the sources (110) through one end while internally reflecting it, and output the replicated light to the eyeball (E). Here, the light from the sources (110) can each travel along zigzag paths. Thus, the polygon-curved optical waveguide (120) can operate as a partial cylindrical lens or a spherical lens to converge the light replicated for the eye (E). This allows for a large horizontal field of view (HFOW). Here, the eye (E) can be positioned ahead of the actual convergence position, that is, closer to the polygon-curved optical waveguide holographic coupler. At this time, planes are placed at points (P1, P2) where light is totally reflected from the polygon-curved optical waveguide (120), respectively, to compensate for convergence distortion caused by the curvature of the curved surface of the curved optical waveguide. Therefore, light can be output as a plane wave from the polygon-curved optical waveguide (120) without convergence distortion caused by the curvature of the curved surface of the curved optical waveguide.

[0031] FIG. 5 is a diagram showing another example of the polygon-curved optical waveguide holographic coupler of FIG. 2 and the propagation of light therein. Here, FIG. 5 (a) is a perspective view and FIG. 5 (b) is a side view.

[0032] Referring to FIG. 5, the polygon-curved optical waveguide (120) may include a first part (521) and a second part (523). For example, the first part (521) and the second part (523) may be arranged vertically along a direction (Z) perpendicular to the plane (XY). One incoupler (130) and an expander (140) may be arranged in the first part (521). The second part (523) may replicate the light bent through the expander (140) by total reflection, and four outcouplers (150) may be arranged vertically along a vertical direction (Z) in the second part (523). The incoupler (130), the expander (140), and the outcouplers (150) may be arranged on a second surface (123). Here, the thickness of the first part (521) and the thickness of the second part (53) can be determined according to the purpose in the polygon-curved optical waveguide holographic coupler. In particular, the diffraction angle in the incoupler (130) can be determined by the polygonal structure center of the polygon-curved optical waveguide (120), and the design degrees of freedom for the diffraction angle in the incoupler (130) can be determined by the thickness of the first part (521). Accordingly, the distribution of planes is calculated to perform the desired function on each surface (121, 123) of the first part (521) and the second part (523), so that the polygon-curved optical waveguide holographic coupler can be implemented to resolve convergence distortion.

[0033] Two sources (110), namely the first source and the second source, are each positioned adjacent to one end of the polygon-curved optical waveguide (120), and the polygon-curved optical waveguide (120) can be positioned in front of the user's eyeball (E). At this time, the polygon-curved optical waveguide (120) can be concavely curved with respect to the eyeball (E) on a plane (XY) that includes the viewing direction of the eyeball (E). The polygon-curved optical waveguide (120) can replicate light from the sources (110) through one end while internally reflecting it, and can output the replicated light to the eyeball (E). Here, the light from the sources (110) can each travel along zigzag paths. Thus, the polygon-curved optical waveguide (120) can operate as a partial cylindrical lens or a spherical lens to converge the light replicated for the eye (E). This ensures a large vertical field of view (VFOV) as well as a large horizontal field of view. Here, the eye (E) can be positioned ahead of the actual convergence position, that is, closer to the polygon-curved optical waveguide holographic coupler. At this time, planes are respectively placed at points (P1, P2) where light is totally reflected from the polygon-curved optical waveguide (120) to compensate for convergence distortion caused by the curvature of the curved surface of the curved optical waveguide. Therefore, light can be output as a plane wave from the polygon-curved optical waveguide (120) without convergence distortion caused by the curvature of the curved surface of the curved optical waveguide.

[0034] In this polygon-curved optical waveguide holographic combiner, the reason for using a zigzag path is to make the gaps, i.e., the seams, between the replicated SLMs in the polygon-curved optical waveguide (120) invisible.

[0035] For example, as illustrated in FIGS. 3, 4, and 5, indices from 1 may be sequentially assigned to the planes from one end of the polygon-curved optical waveguide (120) toward the other end. Here, the planes of the first and second indices are set so that light from the source (110) is incident, i.e., so that the incoupler (120) is positioned, and the planes of the remaining indices are set so that total reflection occurs at the center, i.e., symmetrical reflection where the angle of incidence and the angle of reflection are equal. Thus, the replicated SLMs inside the polygon-curved optical waveguide (120) can be designed to fill the empty gaps. Additionally, by adjusting the thickness of the first part (421) and the second part (423), the replicated SLMs inside the polygon-curved optical waveguide (120) can be designed to overlap or fill the empty gaps.

[0036] Figures 6 and 7 illustrate a computer-generated holography (CGH) algorithm for designing the polygon-curved optical waveguide holography coupler of Figure 1.

[0037] Referring to Fig. 6, the virtual display replicates the information that entered the input display exactly due to total internal reflection of the optical waveguide. Accordingly, most optical waveguide AR devices implement an imaging system in the form of a Maxwellian view. However, if the optical information data contained varies depending on the direction of light, it is possible to implement a hologram with a large field of view even in an optical waveguide AR system.

[0038] The method of projecting a hologram onto a flat optical waveguide is as shown in Fig. 6. The virtual display is delayed by the total reflection of the optical path, and a direction vector toward the eye is calculated at that position. The CGHs of target images 1 to 3 corresponding to virtual displays 1 to 3 are calculated by considering the direction vectors for each, and superimposed into one. At this time, the superimposed CGH is defined as an angular multiplexing computer-generated hologram (AMCGH).

[0039] When AMCGH is applied to the input display, the same AMCGH is replicated on virtual displays 1 to 3, and only CGH information corresponding to the direction vector toward each eye reaches the eye, allowing the images of target images 1 to 3 to be viewed in a larger size. The AMCGH algorithm is intended to be applied to the structure shown in Fig. 5 described earlier, namely, a spherical lens. Instead of placing the user's eye where light is gathered by each architecture, the user's eye is positioned 3 cm away from the architecture.

[0040] The AMCGH calculation algorithm is as shown in Fig. 6. It is an algorithm that applies the cascaded Fresnel transform and field mapping to light originating from the retina. First, the angle between the retinal region and the light rays entering the eye is calculated to transform the target image from a global coordinate system to a local coordinate system and calculate the CGH.

[0041] Subsequently, the angle formed by the display and the CGH field is calculated and converted once again from the local coordinate system to the band coordinate system. The CGH generated at this time is the data used for the input display, and the CGHs corresponding to target images 3 through 9 are calculated respectively and superimposed according to even and odd numbers. Since the direction vector from the virtual display toward the eye is considered when the CGH is calculated by converting from the band coordinate system to the local coordinate system, when the hologram is restored in the AMCGH, only the target image of each virtual display reaches the eye and is restored, appearing as shown in the simulation result above.

[0042] A notable feature of the planar and curved optical waveguide structures is the virtual displays No. 3 and No. 8, indicated by the red circles in Fig. 7. By comparing the angle formed by the optical axis of the virtual display and the green light beam directed toward the eye, it can be confirmed that the curved optical waveguide structure has a smaller angle. Since the diffraction angle of the display pixel is fixed, a smaller angle between the optical axis and the light beam directed toward the eye allows for a larger viewing angle.

[0043] FIG. 8 is a drawing illustrating the operation method of a near-eye display (100) for augmented reality according to various embodiments.

[0044] Referring to FIG. 8, in step 810, at least one source (110) can cause light to be incident through at least one of the two ends of the polygon-curved optical waveguide. The source (110) can be positioned adjacent to one of the two ends of the polygon-curved optical waveguide (120). In one embodiment, when the polygon-curved optical waveguide holographic coupler is positioned in front of the right eye, at least one source (110) can be positioned adjacent to one end of the polygon-curved optical waveguide (120) on the right eye side of the user to cause light to be incident on one end of the polygon-curved optical waveguide (120). In another embodiment, when a polygon-curved optical waveguide holographic coupler is positioned in front of the left eye, at least one source (110) is positioned adjacent to the other end of the polygon-curved optical waveguide (120) on the user's left eye side so as to cause light to be incident on the other end of the polygon-curved optical waveguide (120). In yet another embodiment, the sources (110) are each positioned adjacent to both ends of the polygon-curved optical waveguide (120) so as to cause light to be incident on both ends of the polygon-curved optical waveguide (120).

[0045] Next, in step 820, the polygon-curved optical waveguide (120) can replicate light from the source (110) by internally reflecting it and output the replicated light. The polygon-curved optical waveguide (120) can be positioned in front of the user's eye (E), that is, at least one of the right or left eye. At this time, the polygon-curved optical waveguide (120) can be concavely curved with respect to the eye (E) on a plane (XY) that includes the viewing direction of the eye (E). And, the polygon-curved optical waveguide (120) can replicate light from the source (110) by internally reflecting it through at least one of its two ends and output the replicated light to the eye (E). Here, the light from the source (110) can travel along a zigzag path within the polygon-curved optical waveguide (120). At this time, in the polygon-curved optical waveguide (120), there may be points (P1, P2) where light from the source (110) is totally reflected. In one embodiment, when two sources (110), namely a first source and a second source, are each placed adjacent to one end of the polygon-curved optical waveguide (120), as shown in FIG. 3, light from the sources (110) may each travel along zigzag paths that do not intersect each other within the polygon-curved optical waveguide (120). Here, in the polygon-curved optical waveguide (120), there may be points (P1, P2) where light from the second source is totally reflected between the points (P1, P2) where light from the first source is totally reflected.

[0046] Specifically, the polygon-curved optical waveguide (120) may have a first surface (121) that is concave for light traveling inside the polygon-curved optical waveguide (120), and a second surface (123) that is convex for light traveling inside the polygon-curved optical waveguide (120). When incident from a source (110), light may be repeatedly totally reflected on the first surface (121) and the second surface (123). Thus, first points (P1) where light is totally reflected may be distributed on the first surface (121), and second points (P2) where light is totally reflected may be distributed on the second surface (123). At the second points (P2) distributed on the second surface (123), light may not only be totally reflected but may also be output to the eyeball (E). In one embodiment, when a polygon-curved optical waveguide holographic coupler is positioned in front of the right eye and the left eye, light can be output to the right eye at second points (P2) distributed on the right side of the second surface (123) with respect to an axis passing through the center of the polygon-curved optical waveguide (120) and parallel to the plane (XY) containing the viewing direction of the right eye and the left eye, and light can be output to the left eye at second points (P2) distributed on the left side of the second surface (123).

[0047] In various embodiments, the polygon-curved optical waveguide (120) may have a plurality of planes. Here, the planes may be formed, for example, as polygons. The planes are each placed at points (P) where light is totally reflected in the polygon-curved optical waveguide (120) to compensate for convergence distortion caused by the curvature of the curved surface of the curved optical waveguide. That is, the first surface (121) and the second surface (123) may be composed of a plurality of planes. Thus, the first surface (121) and the second surface (123) may be implemented as a polygonal structure. In this case, the polygon-curved optical waveguide (120) may be designed so that light is symmetrically reflected at the planes. Planes are each positioned at different angles to compensate for convergence distortion caused by the curvature of the curved surface of the curved optical waveguide at each of the points (P), and can be connected at angles rotated considering the radius of curvature (R) of the curved optical waveguide. The planes may include first planes and second planes. First planes are each positioned at first points (P1) on the first surface (121) to compensate for convergence distortion caused by the curvature of the first surface (121). Second planes are each positioned at second points (P2) on the second surface (123) to compensate for convergence distortion caused by the curvature of the second surface (123). For example, the first planes and the second planes may be arranged to face each other in a one-to-one manner, and the first and second planes facing each other may be positioned at the same angle.

[0048] More specifically, at least one incoupler (130) can incident light from a source (110) onto a polygon-curved optical waveguide (120). At this time, the incoupler (130) may be positioned at least one of the two ends of the polygon-curved optical waveguide (120). In one embodiment, when the polygon-curved optical waveguide holographic coupler is positioned in front of the right eye, one incoupler (130) may be positioned at one end of the polygon-curved optical waveguide (120) on the right eye side of the user to provide light to one end of the polygon-curved optical waveguide (120). In another embodiment, when the polygon-curved optical waveguide holographic coupler is positioned in front of the left eye, one incoupler (130) may be positioned at the other end of the polygon-curved optical waveguide (120) on the user's left eye side to provide light to the other end of the polygon-curved optical waveguide (120). In yet another embodiment, when the polygon-curved optical waveguide holographic coupler is positioned in front of both the right and left eyes, two incouplers (130) may be positioned at both ends of the polygon-curved optical waveguide (120) on the user's right eye side and left eye side, respectively, to provide light to both ends of the polygon-curved optical waveguide (120).

[0049] Then, the expander (140) can serve to bend the light incident through the incoupler (130) into the polygon-curved optical waveguide (120) while total reflecting it in a vertical direction (Z). The expander (140) may be positioned adjacent to the incoupler (130) with respect to the polygon-curved optical waveguide (120). For example, the expander (140) may be positioned in the upper region of the polygon-curved optical waveguide (120) where the incoupler (130) is not positioned. Thus, the polygon-curved optical waveguide (120) can replicate the light from the expander (140) while total reflecting it internally.

[0050] Then, at least one outcoupler (150) can output the light replicated from the polygon-curved optical waveguide (120). It may be positioned adjacent to the expander (140) with respect to the polygon-curved optical waveguide (120). For example, the outcoupler (140) may be positioned in the lower region of the polygon-curved optical waveguide (120) where the incoupler (130) is not positioned, i.e., below the expander (140).

[0051] At this time, the incoupler (130), expander (140), and outcoupler (150) can be designed as binary diffraction optical elements (BDOE).

[0052] In this way, the polygon-curved optical waveguide (120) can cause light with the same angle to propagate to the outcoupler (150) through symmetric reflection of diffracted light from the incoupler (130). Thus, in the polygon-curved optical waveguide holographic coupler, light can be output without distortion in the designed direction. In other words, light is identically replicated inside the polygon-curved optical waveguide (120) without convergence distortion caused by the curvature of the curved surface of the curved optical waveguide, and light can be output as a planar wave from the polygon-curved optical waveguide (120). At this time, it is important to design the light so that when it is diffracted from the incoupler (120) and reflected onto the first surface (121) of the polygon-curved optical waveguide (120), the light reaches the normal vector of the curved surface; that is, the key idea for the polygon-curved optical waveguide (120) is to ensure that the light accurately reaches the center of each plane so that incidence and reflection occur symmetrically. Through this, the convergence distortion problem that occurs in the curved optical waveguide is resolved. In addition, the light output from the second planes of the second surface (123) of the polygon-curved optical waveguide (120) converges to one place, and by utilizing this principle, a large horizontal viewing angle can be secured.

[0053] According to the present disclosure, a polygon-curved optical waveguide holographic coupler can provide a user with high degrees of freedom of the eye and a large field of view by utilizing a polygon-curved optical waveguide (120). Specifically, light can be identically replicated within the polygon-curved optical waveguide (120) without convergence distortion caused by the curvature of the curved surface of the curved optical waveguide, and light can be output as a planar wave from the polygon-curved optical waveguide (120). Thus, the polygon-curved optical waveguide holographic coupler will be a structure for improving the user's immersive experience. In addition, since the polygon-curved optical waveguide (120) can be manufactured by flattening the curved surface of the curved optical waveguide, only the design of three diffraction gratings, namely the incoupler (130), the expander (140), and the outcoupler (150), is required to manufacture the polygon-curved optical waveguide holographic coupler. Therefore, the manufacturing process of the polygon-curved optical waveguide holographic coupler is easy.

[0055] In summary, the present disclosure provides a near-eye display (100) for augmented reality having a polygon-curved optical waveguide holographic coupler and a method of operating the same.

[0056] The augmented reality near-eye display (100) of the present disclosure may include at least one source (110) and a curved optical waveguide positioned in front of at least one of the user's right eye and left eye, which replicates light from the source (110) by internally reflecting it through at least one of its two ends and outputs the replicated light to at least one of the right eye and left eye.

[0057] In the present disclosure, the curved optical waveguide may be a polygon-curved optical waveguide (120) having a plurality of planes each disposed at points where light is totally reflected.

[0058] In the present disclosure, the polygon-curved optical waveguide (120) can be designed so that light is symmetrically reflected in planes.

[0059] In the present disclosure, planes may be arranged at different angles to compensate for convergence distortion caused by the curvature of the curved optical waveguide at each of the points.

[0060] In the present disclosure, the curved optical waveguide may be concavely curved with respect to at least one of the right eye and the left eye on a plane (XY) including at least one of the viewing directions of the right eye and the left eye.

[0061] In the present disclosure, the polygon-curved optical waveguide (120) may have a first surface (121) that is concave with respect to light traveling inside the curved optical waveguide, and a second surface (123) that is convex with respect to light traveling inside the curved optical waveguide.

[0062] In the present disclosure, planes may include first planes disposed on a first surface (121) to compensate for convergence distortion caused by the curvature of the first surface (121), and second planes disposed on a second surface (123) to compensate for convergence distortion caused by the curvature of the second surface (123).

[0063] In the present disclosure, the first planes and the second planes are arranged to face each other in a one-to-one manner, and the first plane and the second plane facing each other may be positioned at the same angle.

[0064] In the present disclosure, a near-eye display (100) for augmented reality further comprises at least one incoupler (130) that incidents light from a source (110) onto a polygon-curved optical waveguide (120), an expander (140) that totally reflects light from the incoupler (130) into the polygon-curved optical waveguide (120), and at least one outcoupler (150) that outputs the replicated light from the polygon-curved optical waveguide (120), and the incoupler (130), expander (140), and outcoupler (150) may be attached to second planes.

[0065] In the present disclosure, the polygon-curved optical waveguide (120) has a first portion (421, 521) in which an incoupler (130) and an expander (140) are disposed, and a second portion (423, 523) in which an outcoupler (150) is disposed, and the first portion (421, 521) and the second portion (423, 523) may be arranged vertically along a direction (Z) perpendicular to a plane (XY).

[0066] The method of operation of the augmented reality near-eye display (100) of the present disclosure may include the step (step 810) of at least one source (110) causing light to be incident through at least one of two ends of a curved optical waveguide positioned in front of at least one of the right eye and left eye of a user, and the step (step 820) of the curved optical waveguide duplicating the light from the source (110) while internally reflecting it and outputting the duplicated light for at least one of the right eye and left eye.

[0067] In the present disclosure, the curved optical waveguide may be a polygon-curved optical waveguide (120) having a plurality of planes each disposed at points where light is totally reflected.

[0068] Although the present disclosure has been described in relation to some embodiments, various modifications and changes may be made without departing from the scope of the present disclosure as understood by a person skilled in the art to which the invention of the present disclosure pertains. Furthermore, such modifications and changes should be considered to fall within the scope of the claims appended to this specification.

[0069] The various embodiments of this document and the terms used therein are not intended to limit the technology described in this document to specific embodiments and should be understood to include various modifications, equivalents, and / or substitutions of such embodiments. In relation to the description of the drawings, similar reference numerals may be used for similar components. A singular expression may include a plural expression unless the context clearly indicates otherwise. In this document, expressions such as "A or B," "at least one of A and / or B," "A, B or C," or "at least one of A, B and / or C" may include all possible combinations of items listed together. Expressions such as "first," "second," "first," or "second" may modify the components, regardless of order or importance, and are used only to distinguish one component from another and do not limit the components. When it is mentioned that a certain (e.g., first) component is "(functionally or telecommunicationally) connected" or "connected" to another (e.g., second) component, said certain component may be directly connected to said other component or connected through another component (e.g., third component).

[0070] According to various embodiments, each of the described components may include a singular or multiple entities. According to various embodiments, one or more of the aforementioned components or steps may be omitted, or one or more other components or steps may be added. Generally or additionally, multiple components may be integrated into a single component. In this case, the integrated component may perform one or more functions of each of the multiple components in the same or similar manner as those performed by the corresponding components among the multiple components prior to integration.

Claims

Claim 1 In a near-vision display for augmented reality, at least one source; and includes a curved optical waveguide positioned in front of at least one of the user's right eye and left eye, which replicates light from the source by internally total reflecting it through at least one of two ends, and outputs the replicated light to at least one of the right eye and left eye, wherein the curved optical waveguide is a polygon-curved optical waveguide having a plurality of planes positioned at points where the light is total reflected, and the curved optical waveguide is concavely curved with respect to at least one of the right eye and left eye on a plane including the viewing direction of at least one of the right eye and left eye, and the polygon-curved optical waveguide has a first surface concave with respect to light propagating inside the curved optical waveguide, and a second surface convex with respect to light propagating inside the curved optical waveguide, wherein the planes include first planes positioned on the first surface to compensate for convergence distortion due to the curvature of the first surface, and planes positioned on the second surface, A near-vision display for augmented reality comprising second planes that compensate for convergence distortion caused by the curvature of the second surface. Claim 2 In claim 1, the polygon-curved optical waveguide is designed so that light is symmetrically reflected in the planes, for a near-eye display for augmented reality. Claim 3 A near-eye display for augmented reality, wherein, in claim 1, the planes are each arranged at different angles to compensate for convergence distortion caused by the curvature of the curved optical waveguide at each of the points. Claim 4 delete Claim 5 delete Claim 6 A near-vision display for augmented reality according to claim 1, wherein the first planes and the second planes are arranged to face each other in a one-to-one manner, and the facing first plane and second plane are positioned at the same angle. Claim 7 A near-eye display for augmented reality according to claim 1, further comprising: at least one incoupler that incidents light from the source onto the polygon-curved optical waveguide; an expander that totally reflects light from the incoupler into the polygon-curved optical waveguide; and at least one outcoupler that outputs the replicated light from the polygon-curved optical waveguide, wherein the incoupler, the expander, and the outcoupler are attached to the second planes. Claim 8 In claim 7, the polygon-curved optical waveguide has a first portion in which the incoupler and the expander are disposed, and a second portion in which the outcoupler is disposed, wherein the first portion and the second portion are arranged vertically along a direction perpendicular to the plane, for a near-eye display for augmented reality. Claim 9 A method of operating a near-eye display for augmented reality, comprising the step of causing light to be incident through at least one of the two ends of a curved optical waveguide positioned in front of at least one of the user's right eye and left eye, at least one source; The method comprises the step of the curved optical waveguide replicating light from the source while totally reflecting it internally, and outputting the replicated light for at least one of the right eye and the left eye, wherein the curved optical waveguide is a polygon-curved optical waveguide having a plurality of planes disposed at points where the light is totally reflected, and the curved optical waveguide is concavely curved with respect to at least one of the right eye and the left eye on a plane including an observation direction of at least one of the right eye and the left eye, and the polygon-curved optical waveguide has a first surface concave with respect to light propagating inside the curved optical waveguide, and a second surface convex with respect to light propagating inside the curved optical waveguide, wherein the planes include first planes disposed on the first surface to compensate for convergence distortion due to the curvature of the first surface, and second planes disposed on the second surface to compensate for convergence distortion due to the curvature of the second surface. A method of operation of a near-vision display for augmented reality, including Claim 10 In claim 9, the polygon-curved optical waveguide is designed so that light is symmetrically reflected in the planes, a method of operation for a near-eye display for augmented reality. Claim 11 A method of operation for a near-eye display for augmented reality, wherein, in claim 9, the planes are each arranged at different angles to compensate for convergence distortion caused by the curvature of the curved optical waveguide at each of the points. Claim 12 delete Claim 13 delete Claim 14 A method of operation for a near-eye display for augmented reality, wherein, in claim 9, the first planes and the second planes are arranged to face each other in a one-to-one manner, and the first plane and the second plane facing each other are positioned at the same angle.

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