Optically Enhanced Waveguide

Abstract

An optical expansion waveguide is disclosed, which includes a first waveguide base (1) and a second waveguide base (2). The first waveguide base (1) expands the light entering therein along a first dimension, the first waveguide base (1) includes a plurality of first reflecting surfaces (101) arranged in sequence, and the second waveguide base (2) expands the light inside therein along a second dimension, the second waveguide base (2) includes a plurality of second reflecting surfaces (201) arranged in sequence. At least one of the first reflecting surface (101) and the second reflecting surface (201) is curved at least locally, thereby changing the exit angle of the light, and the image distance formed from the light emitted by the second waveguide base (2) meets a predetermined requirement.

Description

cross reference

[0001] This application claims priority to a Chinese patent application filed with the China Patent Office on January 20, 2022, bearing application number 202210065286.6, and entitled "Optical Enhanced Waveguide," the entire contents of which are incorporated herein by reference. [Technical field]

[0002] The present invention relates to the field of optical devices, and more particularly to optically enhanced waveguides. [Background technology]

[0003] Near-eye display is a technology field that has attracted a lot of attention, and its optical system includes microdisplay and optical element. At present, there are many optical solutions for near-eye display on the market.

[0004] In addition, the arrayed waveguide solution uses semi-transparent and semi-reflective optical surfaces to realize light expansion and exit pupil, and follows the law of reflection that the angle of incidence is equal to the angle of reflection, so there is no dispersion effect on the incident light of the three primary colors forming a full-color display, and it can ensure that the formed image has no obvious color shift, which meets the most basic requirements of a display device and has obvious advantages in optimizing the design of head-mounted devices and beautifying the aesthetics.

[0005] However, due to the characteristic of forming an image at an infinite distance, the display device according to this solution is applied to people with a visual acuity of about 1.2, while the visual acuity of normal people (including vision correction) is about 1.0, so when using such a display device, the wearer cannot see a clear and good image, which brings great trouble to the user. To solve this problem, the mainstream solution uses an external device for assistance and adjustment, which not only increases the volume and weight of the display device, but also reduces the comfort and perception experience of the user. Summary of the Invention [Problem to be solved by the invention]

[0006] In view of this, an object of the present invention is to provide an optical extension waveguide that can be applied to an optical display device to change the focused image distance, is suitable for users with visual impairments, and has a thin and lightweight structure. [Means for solving the problem]

[0007] To achieve the above objectives, the present invention provides the following technical solutions: an optically extended waveguide, the optically extended waveguide including a first waveguide base and a second waveguide base; the first waveguide base expands the beam entering the first waveguide base along a first dimension, the first waveguide base includes a plurality of first reflective surfaces arranged in sequence, the first reflective surfaces at least partially reflecting light incident on the first reflective surfaces to couple at least a portion of the light into the second waveguide base; the second waveguide base expands the beam entering the second waveguide base along a second dimension, the second waveguide base includes a plurality of second reflective surfaces arranged in sequence, the second reflective surfaces at least partially reflect the light entering the second reflective surfaces, and emit at least a portion of the light to the outside of the second waveguide base; At least one of the first reflecting surface and the second reflecting surface is curved at least locally, so that an image distance formed from the light emitted by the second waveguide base satisfies a predetermined requirement.

[0008] Preferably, at least a portion of the first reflecting surface is curved, and the first reflecting surface diverges light reflected by the first reflecting surface. Alternatively, at least a local portion of the second reflecting surface is a curved surface, and the second reflecting surface diverges the light reflected by the second reflecting surface.

[0009] Preferably, each of the first reflecting surfaces forms an inclination angle with respect to the first dimensional direction.

[0010] Preferably, the first waveguide base further comprises at least a first set of opposing surfaces, and light entering the first waveguide base is reflected at each surface of the first set of opposing surfaces to propagate forward.

[0011] Preferably, at least one of the first set of opposing surfaces is curved, at least locally, to change the angle at which light reflected from that surface strikes the first reflecting surface, thereby helping to ensure that the image distance formed from the light emitted by the second waveguide base meets a specified requirement.

[0012] Preferably, at least one surface of the first set of opposing surfaces is divergent in the light reflected therefrom.

[0013] Preferably, the second waveguide base further comprises at least a third set of opposing surfaces, and light entering the second waveguide base at each surface of the third set of opposing surfaces is reflected and propagated forward.

[0014] Preferably, each of the second reflecting surfaces forms an inclination angle with respect to any one of the third set of opposing surfaces.

[0015] Preferably, the inclination angle formed by the second reflecting surface with respect to one surface of the third set of opposing surfaces as a coupling output surface is greater than 0° and less than 45°, and when the second reflecting surface rotates along a counterclockwise direction with respect to the one surface, the inclination angle formed by the second reflecting surface with respect to the surface is positive.

[0016] Preferably, at least one of the third set of opposing surfaces is curved, at least locally, to change the angle at which light reflected from that surface strikes the second reflective surface, thereby helping to ensure that the image distance formed from the light emitted by the second waveguide base meets a specified requirement.

[0017] Preferably, at least one surface of the third set of opposing surfaces diverges light reflected by that surface.

[0018] Preferably, the first waveguide base further includes a first coupling output surface that causes the reflected light of the first reflecting surface to be emitted outside the first waveguide base, and the second waveguide base further includes a second coupling input surface that causes the light emitted by the first waveguide base to enter the second waveguide base, and the first coupling output surface and the second coupling input surface are optically coaxial.

[0019] Preferably, the first coupling output surface is a flat surface, an inclined surface, a sawtooth surface or a curved surface, and the second coupling input surface is a flat surface, an inclined surface, a sawtooth surface or a curved surface.

[0020] Preferably, the first waveguide base is provided in front of, behind or above the second waveguide base. Effect of the Invention

[0021] As can be seen from the above technical solution, the optical expansion waveguide provided by the present invention includes a first waveguide base and a second waveguide base, the first waveguide base expands the beam entering the first waveguide base along a first dimension, the first waveguide base includes a plurality of first reflecting surfaces arranged in sequence, the first reflecting surface at least partially reflects the light entering the first reflecting surface to couple at least a portion of the light into the second waveguide base, the second waveguide base expands the beam entering the second waveguide base along a second dimension, the second waveguide base includes a plurality of second reflecting surfaces arranged in sequence, the second reflecting surface at least partially reflects the light entering the second reflecting surface to emit at least a portion of the light out of the second waveguide base. At least one of the first reflecting surface and the second reflecting surface is curved at least locally, so that the light emission angle is changed by the first reflecting surface and / or the second reflecting surface, and the image distance formed from the light emitted by the second waveguide base meets a predetermined requirement. Therefore, when the optical expansion waveguide of the present invention is applied to an optical display device, it can change the focused image distance, is suitable for users with visual impairments, and has a thin and light structure. [Brief description of the drawings]

[0022] In order to more clearly describe the technical solutions in the embodiments of the present invention or the prior art, the following briefly introduces the necessary drawings in the embodiments or prior art description, and the drawings described below are merely some embodiments of the present invention, and other drawings can be obtained based on these drawings on the premise that no inventive effort is required for those skilled in the art. [Figure 1] FIG. 2 is a schematic diagram of light propagation on a first reflecting surface in one embodiment of the present invention. [Figure 2-1] FIG. 2-3 is a left side view of the optical extension waveguide of FIG. 2-2. [Figure 2-2] FIG. 2 is a front view of an optical extension waveguide provided by one embodiment of the present invention. [Diagram 3] FIG. 2 is a schematic diagram of a first waveguide-based ray propagation in one embodiment of the present invention; [Figure 4] 4 is a schematic diagram of ray propagation through one surface of a first set of opposing surfaces and a first reflecting surface in one embodiment of the present invention. [Diagram 5] FIG. 13 is a schematic diagram of a second waveguide-based ray propagation in one embodiment of the present invention. [Figure 6] FIG. 2 is a schematic diagram of a light ray propagating at a second waveguide base to form a corresponding effective light passing aperture in one embodiment of the present invention. [Figure 7] FIG. 2 is a schematic diagram of a waveguide-based reflector using a curved surface and the structural parameters of the surface in one embodiment of the present invention. [Figure 8-1] FIG. 2 is a schematic diagram of a curved surface used for one of the opposing surfaces of the waveguide base in one of the embodiments of the present invention. [Figure 8-2] FIG. 13 is a schematic diagram of another curved surface used by any of the opposing surfaces of the waveguide base of any of the embodiments of the present invention. [Figure 9-1-9-4] 2A-2C are schematic diagrams of four embodiments of a first waveguide-based first coupling output surface and a second waveguide-based second coupling input surface according to an embodiment of the present invention; [Figure 10-1-10-3] 3A to 3C are schematic diagrams of three embodiments of the arrangement positions of a first waveguide base and a second waveguide base in an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] In order to allow those skilled in the art to better understand the technical solution of the present invention, the following clearly and completely describes the technical solution of the embodiments of the present invention in combination with the drawings of the embodiments of the present invention, and the described embodiments are not all the embodiments, but only some embodiments of the present invention. Based on the embodiments of the present invention, on the premise that those skilled in the art do not make any inventive efforts, all other embodiments obtained fall within the protection scope of the present invention.

[0024] The optical expansion waveguide provided in this embodiment includes a first waveguide base and a second waveguide base; the first waveguide base expands the beam entering the first waveguide base along a first dimension, the first waveguide base includes a plurality of first reflective surfaces arranged in sequence, the first reflective surfaces at least partially reflect the light incident on the first reflective surfaces, and couple at least a portion of the light into the second waveguide base; the second waveguide base expands the beam entering the second waveguide base along a second dimension, the second waveguide base includes a plurality of second reflective surfaces arranged in sequence, the second reflective surfaces at least partially reflect the light entering the second reflective surfaces, and emit at least a portion of the light to the outside of the second waveguide base; By making at least one of the first reflecting surface and the second reflecting surface at least locally curved, an image distance formed from the light emitted by the second waveguide base satisfies a predetermined requirement.

[0025] The beam entering the first waveguide base is propagated through the first waveguide base, with each portion of the beam incident on a respective first reflective surface, which at least partially reflects the light incident on it and couples at least a portion of the light into the second waveguide base, thereby achieving expansion of the beam entering the first waveguide base in a first dimension.

[0026] The beam entering the second waveguide base is propagated through the second waveguide base, with each portion of the beam incident on a respective second reflective surface, which at least partially reflects the light incident thereon and causes at least a portion of the light to exit the second waveguide base, thereby realizing the expansion of the beam entering the second waveguide base in a second dimension.

[0027] The image distance formed from the light emitted by the second waveguide base is the distance from a viewing position to a corresponding virtual image of the image formed from the light emitted by the second waveguide base.

[0028] If the first reflecting surface of the first waveguide base is at least locally curved, the curved surface can change the reflection angle of the light at the first reflecting surface, the incident angle at which the light is coupled to the second waveguide base, and the exit angle at which the light exits the second waveguide base. If the second reflecting surface of the second waveguide base is at least locally curved, the curved surface can change the reflection angle of the light at the second reflecting surface and the exit angle at which the light exits the second waveguide base. Thus, by using a curved surface for at least one of the first reflecting surface and the second reflecting surface, the optical expansion waveguide can change the exit angle of the output light and the image distance formed from the output light of the optical expansion waveguide, and the image distance formed meets a predetermined requirement.

[0029] Therefore, when the optical expansion waveguide of this embodiment is applied to an optical display device, the image distance can be changed, which is suitable for users with visual impairments, and users with visual impairments can see clear and good images. Furthermore, the structure of the optical expansion waveguide of this embodiment is thin and light.

[0030] In this embodiment, as long as at least a portion of the first reflecting surface of the first waveguide base is curved, there is no specific limitation on the shape of the curved surface included in the first reflecting surface or the size of the curved surface area, as long as the emission angle of the light emitted by the second waveguide base can be changed and the image distance formed from the light emitted by the second waveguide base meets a predetermined requirement. The curved surface included in the first reflecting surface may be a curved surface having a certain curvature or a free-form surface. Preferably, the curved surface is used for the first reflecting surface to diverge or converge the light reflected by the first reflecting surface.

[0031] In this embodiment, as long as at least a portion of the second reflecting surface of the second waveguide base is curved, there is no specific limitation on the shape of the curved surface included in the second reflecting surface or the size of the curved surface area, as long as the emission angle of the light emitted by the second waveguide base can be changed and the image distance formed from the light emitted by the second waveguide base meets a predetermined requirement. The curved surface included in the second reflecting surface may be a curved surface having a certain curvature or a free-form surface. Preferably, the curved surface is used for the second reflecting surface to diverge or converge the light reflected by the second reflecting surface.

[0032] For illustration, refer to FIG. 1, which is a schematic diagram of light propagation at a first reflecting surface in one embodiment. As shown in the drawing, the light beam L1 and the light beam L2 reflected by the surface 100 of the first waveguide base are respectively incident on the first reflecting surface 101, which is a curved surface. They form reflected light beams L1' and L2' through the first reflecting surface 101. When the light beams L1 and L2 are reflected through the reference flat surface 102 of the first reflecting surface 101, they form reflected light beams L1'', L2'', through the reference flat surface 102 of the first reflecting surface 101, and the reflected light beams L1' and L2' are divergent. In this way, the image distance formed from the light emitted by the second waveguide base is reduced. For a user with visual impairment, the image can be focused on the retina of the user with visual impairment.

[0033] Based on FIG. 1, taking the light propagation on the first reflecting surface of the first waveguide base as an example, the principle of image distance change is realized by using a curved surface for the first reflecting surface; similarly, for the second waveguide base, the change of image distance is also realized by using a curved surface for its second reflecting surface, based on the above principle.

[0034] In the first waveguide base, each of the first reflecting surfaces forms an inclination angle with respect to the first dimension direction. The inclination angle of the first reflecting surfaces with respect to the first dimension direction refers to the chord of the first reflecting surfaces being neither parallel nor perpendicular to the first dimension direction. Correspondingly, the inclination angle formed by the first reflecting surfaces with respect to the first dimension direction is the included angle between the chord of the first reflecting surfaces and the first dimension direction. When the light propagated through the first waveguide base is incident on the first reflecting surfaces, a portion of the light energy is transmitted through the first reflecting surfaces and continues to propagate, and another portion of the light energy is reflected and coupled into the second waveguide base.

[0035] In this embodiment, the magnitude of the inclination angle formed by each of the first reflecting surfaces with respect to the first dimension is not limited, as long as the light propagating in the first waveguide base is reflected and coupled into the second waveguide base when the light is incident on the first reflecting surface. In practical application, the expansion requirement of the light in the first dimension is set according to the size of the first waveguide base and the size of the second waveguide base, and preferably, the structure of the optical expansion waveguide is thin and light while meeting the expansion requirement of the light.

[0036] For the projection surface of the first reflecting surface on a plane parallel to the first dimension direction, the plane parallel to the first dimension direction is located on the light-reflecting side of the first reflecting surface, and determines the light passing aperture of the output light of the optical expansion waveguide in the first dimension direction. When applied to an optical display device, the light passing aperture of the output light of the optical expansion waveguide in the first dimension direction must ensure that the image from the image source is fully expanded, that is, the image formed by the output light of the optical expansion waveguide contains the complete information of the image in the first dimension direction.

[0037] The first waveguide base further includes at least a first set of opposing surfaces, and light entering the first waveguide base is reflected by each of the first set of opposing surfaces and propagates forward. Specifically, if light is incident on each of the first set of opposing surfaces, the total internal reflection condition is satisfied. The first set of opposing surfaces may or may not be parallel to each other, and light may be reflected by each of the first set of opposing surfaces and propagate forward.

[0038] Preferably, the first waveguide base further includes a second set of opposing surfaces, the second set of opposing surfaces and the first set of opposing surfaces form a closed cross section, and the light entering the first waveguide base is reflected by each of the first set of opposing surfaces and the second set of opposing surfaces to propagate forward. Specifically, if the light is incident on each of the second set of opposing surfaces, the total reflection condition is satisfied. The second set of opposing surfaces may or may not be parallel to each other, as long as the light is reflected by each of the second set of opposing surfaces to propagate forward.

[0039] For example, referring to Fig. 2-1, Fig. 2-2 and Fig. 3 in combination, Fig. 2-1 is a left side view of the optical extension waveguide of Fig. 2-2, Fig. 2-2 is a front view of the optical extension waveguide provided by one embodiment, and Fig. 3 is a schematic diagram of light propagation in the first waveguide base in one embodiment. As shown in the drawing, within the cross section formed by four surfaces 1-A, 1-B, 1-C and 1-D of the first waveguide base 1, the light entering the first waveguide base 1 is reflected by each surface and propagates forward. During the propagation process, when the light meets the first reflecting surface 101, it reflects a part of the light energy at a certain energy ratio, so that the light is coupled into the second waveguide base 2.

[0040] In the first waveguide base 1 of Fig. 3, the first set of opposing surfaces 1-A and 1-B are parallel to each other, and the second set of opposing surfaces 1-C and 1-D are parallel to each other, and Fig. 3 is merely illustrative. In other embodiments, the first set of opposing surfaces may not be parallel, and the second set of opposing surfaces may not be parallel.

[0041] In one preferred embodiment, at least one surface of the first set of opposing surfaces is curved at least locally to change the angle of incidence of the reflected light from the surface on the first reflecting surface, thereby helping to realize that the image distance formed from the light emitted from the second waveguide base meets a predetermined requirement. At least one surface of the first set of opposing surfaces is curved at least locally to change the reflection angle of the light after passing through the surface, and the angle of incidence of the reflected light from the surface on the first reflecting surface can be changed, thereby helping to realize the change in the image distance formed from the light emitted from the optical expansion waveguide.

[0042] In this embodiment, there is no specific limitation on the shape of the curved surface or the size of the curved surface area included in any of the first set of opposing surfaces, as long as the emission angle of the light emitted by the second waveguide base can be changed and the image distance formed from the light emitted by the second waveguide base meets a predetermined requirement. The curved surface included in any of the first set of opposing surfaces may be a curved surface having a certain curvature or a free-form surface. Preferably, the curved surface included in any of the first set of opposing surfaces diverges or focuses the reflected light from the surface.

[0043] As an example, as shown in FIG. 4, FIG. 4 is a schematic diagram of light propagation on one surface of the first set of opposing surfaces and the first reflecting surface in one embodiment. As shown in the drawing, surface 100 is one of the first set of opposing surfaces of the first waveguide base 1. By making surface 100 a curved surface (its reference plane is surface 103), the reflected light rays L3, L4 of the incident light rays L3 and L4 on surface 100 become divergent, and the reflected light rays L3', L4' after the light rays are reflected by the first reflecting surface 101 become divergent. As a result, the image distance formed from the light emitted by the second waveguide base 2 is reduced.

[0044] The second waveguide base further includes at least a third set of opposing surfaces, and the light entering the second waveguide base is reflected and propagated forward by each of the third set of opposing surfaces. Specifically, when the light is incident on each of the third set of opposing surfaces, the total internal reflection condition is satisfied. The third set of opposing surfaces may or may not be parallel to each other, and the light may be reflected and propagated forward by each of the third set of opposing surfaces.

[0045] Preferably, each of the second reflecting surfaces forms an inclination angle with any one of the surfaces of the third set of opposing surfaces. The inclination angle of the second reflecting surface with respect to a surface refers to the chord of the second reflecting surface and the surface being neither parallel nor perpendicular. Correspondingly, the inclination angle formed by the second reflecting surface with respect to a surface is the included angle between the chord of the second reflecting surface and the surface, and if the surface is curved, the inclination angle formed by the second reflecting surface with respect to the surface is the included angle between the chord of the second reflecting surface and the chord of the surface. When the light propagated through the second waveguide base is incident on the second reflecting surface, a part of the light energy is transmitted through the second reflecting surface and continues to propagate, and another part of the light energy is reflected and exits from the second waveguide base.

[0046] 2-1, 2-2 and 5 are combined for illustration, and FIG. 5 is a schematic diagram of light propagation in the second waveguide base in one embodiment. As shown in the drawing, the light coupled from the first waveguide base 1 to the second waveguide base 2 is reflected by the surfaces 2-A and 2-B of the second waveguide base 2 and propagates forward. During the propagation, when the light meets the second reflecting surface 201, it reflects a part of the light energy at a certain energy ratio, so that a part of the light is emitted out of the second waveguide base 2.

[0047] In this embodiment, the magnitude of the inclination angle formed by each second reflecting surface with respect to any of the opposing surfaces of the third set is not limited, as long as the light propagating in the second waveguide base is reflected and emitted out of the second reflecting surface when the light is incident on the second reflecting surface. In practical application, the expansion requirement of the light in the second dimension may be set according to the size of the first waveguide base and the size of the second waveguide base.

[0048] As an example, as shown in FIG. 6, FIG. 6 is a schematic diagram of a light ray propagating through the second waveguide base in one embodiment to form an effective light passing aperture correspondingly, when the light propagating through the second waveguide base 2 meets each of the second reflecting surfaces S1, S2, S3, S4 and S5 respectively, it is reflected and at least a part of the light is emitted out of the second waveguide base 2. The total projection surface S of each of the second reflecting surfaces S1, S2, S3, S4 and S5 on the surface 2-A determines the effective light passing aperture of the optical extension waveguide. When applied to an optical display device, the effective light passing aperture of the optical extension waveguide must ensure that the image from the image source is fully expanded, that is, the image formed by the output light of the optical extension waveguide contains the complete information of the image in the first dimension direction and the second dimension direction.

[0049] Preferably, the inclination angle formed by the second reflecting surface with respect to one of the surfaces of the third set as the coupling output surface is greater than 0° and less than 45°, and is indicated as 0°<β≦45°, and when the second reflecting surface rotates along a counterclockwise direction with respect to one of the surfaces, the inclination angle formed by the second reflecting surface with respect to the surface is positive. With respect to one of the surfaces of the third set as the coupling output surface, the light reflected by the second reflecting surface is emitted out of the second waveguide base through the surface. In this way, the light is expanded by the second reflecting surface, and the thickness of the second waveguide base can be reduced, and the entire waveguide becomes thinner and lighter.

[0050] In one preferred embodiment, at least one surface of the third set of opposing surfaces is curved at least locally to change the incident angle of the reflected light from the surface to the second reflecting surface, thereby helping to realize that the image distance formed from the light emitted from the second waveguide base meets a predetermined requirement. At least one surface of the third set of opposing surfaces is curved at least locally to change the reflection angle of the light after passing through the surface, and change the incident angle of the reflected light from the surface to the second reflecting surface, thereby realizing the change of the image distance formed from the light emitted from the optical expansion waveguide in combination with the first reflecting surface using a curved surface or the second reflecting surface using a curved surface.

[0051] In this embodiment, there is no specific limitation on the shape of the curved surface or the size of the curved surface area included in any of the opposing surfaces of the third set, as long as the emission angle of the light emitted by the second waveguide base can be changed and the image distance formed from the light emitted by the second waveguide base meets a predetermined requirement. The curved surface included in any of the opposing surfaces of the third set may be a curved surface having a certain curvature or a free-form surface. Preferably, the curved surface included in any of the opposing surfaces of the third set diverges or focuses the reflected light of the surface.

[0052] In the optical design, when the optical expansion waveguide is applied to an optical display device, in order to meet the requirements of the resolution, contrast or clarity of the generated image, if the first reflecting surface of the first waveguide base and at least one surface of the first set of opposing surfaces are curved, the curved surface parameters of the first reflecting surface of the first waveguide base and any surface of the first set of opposing surfaces should satisfy a certain relationship. If the second reflecting surface of the second waveguide base and at least one surface of the third set of opposing surfaces are curved, the curved surface parameters of the second reflecting surface of the second waveguide base and any surface of the third set of opposing surfaces should satisfy a certain relationship. With reference to FIG. 7, FIG. 7 is a schematic diagram of a reflecting surface and surface structure parameters using a curved surface of any waveguide base in one embodiment. The optical design is performed based on a collimated main axis beam emitted from an axial object point, and when the main axis beam is perpendicularly incident on the coupling input surface of the waveguide base, the corresponding relationships of each parameter are as follows: α R2 = α R1 -β o ; α R1 =π / 2-β i ; β i is the included angle between the coupling input plane and the horizontal reference plane of the waveguide base surface, and β o is the angle between the plane on which the chord of the curved reflecting surface is located and the horizontal reference plane of the waveguide base surface, and α R1 is the angle between the principal axis ray and the horizontal reference plane normal of the waveguide base surface, and α R2 is the included angle between the principal axis ray and the reference surface normal of the coupling output surface.

[0053] h s =h r =N*(λ / 2); H r =H / (sin(β o )); H s =H / (tan(β o )); h s is the local curvature height of the curved waveguide corresponding to a single reflecting surface, and H sis the local chord length of the curved waveguide corresponding to a single reflecting surface, and h r is the local curved arrow height corresponding to the curved reflecting surface itself, and H r is the local chord length corresponding to the curved reflecting surface itself; N is the number of apertures according to the image distance adjustment needs; λ is the reference wavelength selected during optical design. Based on the specific image distance adjustment needs, the required local curvature of the curved reflecting surface and the local curvature radius of the waveguide-based curved surface can be obtained by calculation according to the corresponding arrow height and chord length.

[0054] For example, refer to Figures 8-1 and 8-2, which are schematic diagrams of using a curved surface for any of the opposing surfaces of any of the waveguide bases in this embodiment, and as shown in the drawings, any of the opposing surfaces of the waveguide base may be a free-form surface, a concave surface or a convex surface.

[0055] The first waveguide base further includes a first coupling output surface that causes the reflected light of the first reflecting surface to radiate outside the first waveguide base, and the second waveguide base further includes a second coupling input surface that causes the light radiated by the first waveguide base to enter the second waveguide base, and the first coupling output surface and the second coupling input surface are optically coaxial. The first coupling output surface and the second coupling input surface being optically coaxial means that the first coupling output surface and the second coupling input surface are parallel to each other corresponding to a local portion of the optical axis.

[0056] In this embodiment, the shape of the first coupling output surface of the first waveguide base and the shape of the second coupling input surface of the second waveguide base are not limited, as long as the first coupling output surface and the second coupling input surface are optically coaxial. The first coupling output surface may be, but is not limited to, a flat surface, an inclined surface, a sawtooth surface, or a curved surface, and the second coupling input surface may be, but is not limited to, a flat surface, an inclined surface, a sawtooth surface, or a curved surface. As an example, refer to Figures 9-1 to 9-4, which respectively show four embodiments of the first coupling output surface of the first waveguide base and the second coupling input surface of the second waveguide base in this embodiment.

[0057] In this embodiment, the relative positions of the first and second waveguide bases are not limited, and the light coupled out from the first waveguide base may be made to enter the second waveguide base. As an example, refer to Fig. 10-1 to Fig. 10-3, which respectively show three embodiments of the arrangement positions of the first and second waveguide bases in this embodiment, and as shown in the drawings, the first waveguide base 1 is provided in front of, behind, or above the second waveguide base 2.

[0058] The optical extension waveguide of this embodiment is applicable to near-eye display devices, such as head-mounted devices, and can change the focused image distance, making it suitable for users with visual impairments, with a thin and light structure, and improving the user's comfort and perception experience.

[0059] The above is a detailed introduction of the optical extension waveguide provided by the present invention. In this specification, specific examples are used to describe the principle and embodiment of the present invention, and the description of the above examples is only used to understand the method and spirit of the present invention. Here, those skilled in the art may make some improvements and modifications to the present invention without departing from the principle of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. an optically extended waveguide, the optically extended waveguide including a first waveguide base and a second waveguide base; the first waveguide base expands the beam entering the first waveguide base along a first dimension, the first waveguide base includes a plurality of first reflective surfaces arranged in sequence, the first reflective surfaces at least partially reflecting light incident on the first reflective surfaces to couple at least a portion of the light into the second waveguide base; the second waveguide base expands the beam entering the second waveguide base along a second dimension, the second waveguide base includes a plurality of second reflective surfaces arranged in sequence, the second reflective surfaces at least partially reflect the light entering the second reflective surfaces, and emit at least a portion of the light to an outside of the second waveguide base; An optical expansion waveguide characterized in that by making at least a portion of at least one of the first reflecting surface and the second reflecting surface curved, an image distance formed from the light emitted by the second waveguide base meets a specified requirement.

2. At least a portion of the first reflecting surface is curved, and the first reflecting surface diverges light reflected by the first reflecting surface; The optical expansion waveguide according to claim 1 , wherein at least a portion of the second reflecting surface is curved, and the second reflecting surface diverges the light reflected by the second reflecting surface.

3. The optical expansion waveguide of claim 1 , wherein each of the first reflecting surfaces forms an inclination angle with respect to the first dimension.

4. 2. The optical extension waveguide of claim 1, wherein the first waveguide base further comprises at least a first set of opposing surfaces, and light entering the first waveguide base is reflected by each of the first set of opposing surfaces and propagates forward.

5. The optical expansion waveguide of claim 4, characterized in that at least one of the first set of opposing surfaces is curved at least locally, thereby changing the angle at which the reflected light from that surface enters the first reflecting surface, thereby helping to ensure that the image distance formed from the light emitted by the second waveguide base meets a specified requirement.

6. 6. The optical enhancement waveguide of claim 5, wherein at least one surface of the first set of opposing surfaces diverges light reflected therefrom.

7. 2. The optical extension waveguide of claim 1, wherein the second waveguide base further comprises at least a third set of opposing surfaces, and light entering the second waveguide base is reflected by each of the third set of opposing surfaces and propagates forward.

8. 8. The optical expansion waveguide of claim 7, wherein each of the second reflecting surfaces forms an inclination angle with respect to one of the opposing surfaces of the third set.

9. 9. The optical expansion waveguide of claim 8, wherein the inclination angle formed by the second reflecting surface with respect to one surface of the third set of opposing surfaces as a coupling output surface is greater than 0° and less than 45°, and when the second reflecting surface rotates along a counterclockwise direction with respect to the one surface, the inclination angle formed by the second reflecting surface with respect to the surface is positive.

10. The optical expansion waveguide of claim 7, characterized in that at least one surface of the third set of opposing surfaces is curved at least locally, thereby changing the angle at which the reflected light from that surface enters the second reflecting surface, thereby helping to ensure that the image distance formed from the light emitted by the second waveguide base meets a specified requirement.

11. 11. The optical enhancement waveguide of claim 10, wherein at least one surface of the third set of opposing surfaces diverges light reflected by that surface.

12. The optical expansion waveguide according to any one of claims 1 to 11, characterized in that the first waveguide base further includes a first coupling output surface that radiates the reflected light of the first reflecting surface to the outside of the first waveguide base, and the second waveguide base further includes a second coupling input surface that causes the light emitted by the first waveguide base to enter the second waveguide base, and the first coupling output surface and the second coupling input surface are optically coaxial.

13. 13. The optical expansion waveguide of claim 12, wherein the first coupling output surface is a flat surface, an inclined surface, a sawtooth surface or a curved surface, and the second coupling input surface is a flat surface, an inclined surface, a sawtooth surface or a curved surface.

14. The optical extension waveguide according to any one of claims 1 to 11, wherein the first waveguide base is provided in front of, behind or above the second waveguide base.

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