Optical waveguide and near-to-eye display module

Abstract

The invention discloses an optical waveguide and a near-to-eye display module. The optical waveguide comprises a waveguide substrate and a coupling-out region, wherein the coupling-out region comprises a plurality of sub-regions, a set distance is formed between every two sub-regions, and a plurality of optical structures which are periodically arranged are arranged in each sub-region. According to the waveguide arrangement structure, the interference fringe phenomenon caused by interference between light of different propagation levels can be effectively weakened, and the imaging effect and the watching experience of a user are improved.

Description

Technical Field

[0001] The present invention relates to the field of scanning display, and in particular to an optical waveguide and a near-eye display module. Background Art

[0002] When using a laser source as an AR (Augmented Reality) display source, interference occurs during transmission due to the narrow spectrum width of the laser light source. In AR display, due to the different propagation angles and azimuths of different fields of view, regular interference fringes will be formed in the display area. These interference fringes are mainly divided into two categories: interference fringes caused by mirror reflection light and interference fringes between light of different propagation orders.

[0003] like Figure 1 As shown in the figure, the first type of interference fringes is caused by mirror reflected light, which can be weakened by coating and other methods. The second type of interference fringes is the interference fringes between lights of different propagation orders, which cannot be eliminated by simple coating treatment, so the existence of interference fringes will greatly affect the display effect and reduce the user's viewing experience. Summary of the invention

[0004] The purpose of the present invention is to provide an optical waveguide and a near-eye display module, which are used to alleviate the technical problem existing in the prior art that the interference fringes between lights of different propagation orders cannot be eliminated by simple coating treatment, so that the existence of the interference fringes will greatly affect the display effect.

[0005] In order to achieve the above-mentioned purpose of the invention, a first aspect of an embodiment of the present invention provides an optical waveguide, which includes a waveguide substrate and a coupling-out region; wherein the coupling-out region includes a plurality of sub-regions, each of which has a set spacing between them, and each of the sub-regions is provided with a plurality of periodically arranged optical structures.

[0006] Optionally, after the spacing between the sub-regions is increased, the emitted light rays passing through the sub-regions are given a fixed phase, thereby adjusting the phase difference between the emitted light rays.

[0007] Optionally, the spacing between the sub-regions ranges from [(k+0.1)P, (k+0.9)P], where P is the grating period and k is an arbitrary integer.

[0008] Optionally, the intervals between the sub-regions are the same.

[0009] Optionally, the intervals between the sub-regions are different.

[0010] Optionally, the sub-regions are arranged in an array or in a non-array.

[0011] Optionally, the shapes of the sub-regions are the same or different.

[0012] Optionally, the shape of each sub-area is one or more of square, circle, triangle or irregular shape.

[0013] A second aspect of an embodiment of the present invention provides a near-eye display module, comprising an image projection device and the optical waveguide described in the first aspect, wherein the image projection device is used to generate image light and project it onto a corresponding coupling-in area on the optical waveguide, and after being transmitted through the optical waveguide, the light is diffracted and output through an out-coupling area.

[0014] Optionally, the light source of the image transmission device is a laser light source.

[0015] One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0016] In the solution of the embodiment of the present invention, the optical waveguide includes a waveguide matrix and an outcoupling region; wherein the outcoupling region includes a plurality of sub-regions, each of which has a set spacing between them, and each of which is provided with a plurality of periodically arranged optical structures. The above waveguide arrangement structure can effectively reduce the interference fringe phenomenon caused by the interference between lights of different propagation orders, thereby alleviating the technical problem existing in the prior art that the interference fringes between lights of different propagation orders cannot be eliminated by simple coating treatment, so that the existence of interference fringes will greatly affect the display effect, thereby achieving the technical effect of improving the imaging effect and the user's viewing experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative labor:

[0018] Figure 1 Schematic diagram of different types of interference fringes provided by an embodiment of the present invention;

[0019] Figure 2 A schematic diagram of an optical waveguide structure provided by an embodiment of the present invention;

[0020] Figure 3 A schematic diagram of the principle of generating interference provided by an embodiment of the present invention;

[0021] Figure 4 A schematic diagram of the arrangement structure of sub-regions provided in an embodiment of the present invention;

[0022] Figure 5 A schematic diagram of light intensity superposition provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] Please refer to Figure 2 , Figure 2 An optical waveguide 100 provided in an embodiment of the present invention includes: a waveguide substrate 101, an incoupling region 102 and an outcoupling region 103, wherein a grating structure is arranged in the incoupling region 102 and the outcoupling region 103, and the grating structure can be realized by processes such as imprinting, coating, and etching, which are not limited here. Generally, the grating structure arranged in the incoupling region 102 can be referred to as an incoupling grating, and the specific grating type can be a one-dimensional grating or a two-dimensional diffraction grating; the grating structure arranged in the outcoupling region 103 can be referred to as an outcoupling grating, and the specific grating type can be a two-dimensional diffraction grating.

[0025] certainly, Figure 2 The contours and relative positions of the coupling-in region 102 and the coupling-out region 103 shown in the figure are exemplary. In practical applications, the coupling-in region 102 may not be Figure 2 The circular outline shown in the figure may be a rounded rectangle, a trapezoid, etc. Similarly, the outline of the outcoupling region 103 may also be a trapezoid, a rounded rectangle. The relative positions of the incoupling region 102 and the outcoupling region 103 may be arranged above and below each other, instead of the current Figure 2 Left and right distribution under viewing angle. Figure 2 The illustrated coupling-in region 102 and the coupling-out region 103 should not be understood as limiting the present invention.

[0026] In actual applications, the waveguide 100 is usually used to output image light to the observer's eyes (left eye or right eye). If it is to be used as binocular AR glasses, at least two waveguide 100 structures are required to correspond to the observer's eyes respectively. In some cases, the lateral size of the outcoupling region 103 is sufficient to cover the observer's eyes. When used as binocular AR glasses, only one waveguide 100 structure is required.

[0027] like Figure 3 As shown, taking a two-dimensional waveguide as an example, when light is transmitted from point A to point B, there are many optical paths with the same optical path length. Optical paths with the same optical path length will coherently constructive. Therefore, the light diffracted from point B will form strong interference at point C.

[0028] In order to reduce the interference fringes between lights of different propagation orders, in the embodiment of the present invention, Figure 4 As shown, multiple sub-regions are set in the outcoupling region, and the spacing between each sub-region is controlled. It is well known that in the scalar diffraction theory, the spatial translation will bring about the phase shift in the frequency domain. This phenomenon has also been verified in the vector diffraction theory. Therefore, after adding spacing between each sub-region, a certain phase can be added to the outgoing light. The additional phase can effectively adjust and disrupt the phase difference between each light, so that the coherent constructive phenomenon of each light at point B is weakened, and then the intensity of the diffracted light from point B reaching point C is weakened, thereby reducing the interference contrast.

[0029] Among them, Figure 5 As shown, Figure 5 The light intensity superposition at point B is described, including the light intensity superposition before correction and after adding spacing correction.

[0030] In the embodiment of the present invention, the spacing between each area can be the same or different, depending on the final arrangement of the grating area and the imaging effect. The spacing between each sub-area is generally controlled to be within the interval [(k+0.1)P, (k+0.9)P], where P is the grating period and k can be any integer.

[0031] In the embodiment of the present invention, the sub-regions may be arranged in an array or in a non-array, the shapes of the sub-regions may be the same or different, and the shape of the sub-regions may be one or more combinations of square, circular, triangular or irregular shapes, all of which depend on the final arrangement of the grating area and the corresponding imaging effect, and can therefore be set according to actual needs.

[0032] Based on the optical waveguide described above, a near-eye display module is also provided in an embodiment of the present invention. The near-eye display module can be applied to AR glasses. The near-eye display module includes: an image projection device and the aforementioned optical waveguide. The image projection device is used to generate image light and project it to the corresponding coupling-in area on the optical waveguide, so that the image light can be transmitted in the waveguide and coupled out through the coupling-out area.

[0033] When laser is used as a light source, the optical waveguide structure of the present invention can be optimized with respect to the propagation characteristics of the laser in the waveguide, thereby better reducing or even eliminating the interference generated in the field of view of the diffraction waveguide.

[0034] All features disclosed in this specification, or steps in all methods or processes disclosed, except mutually exclusive features and / or steps, can be combined in any manner.

[0035] Any feature disclosed in this specification (including any additional claims, abstract and drawings), unless otherwise stated, may be replaced by other equivalent or alternative features with similar purposes. That is, unless otherwise stated, each feature is only an example of a series of equivalent or similar features.

[0036] The present invention is not limited to the above-mentioned specific embodiments, but extends to any new features or any new combination disclosed in this specification, as well as any new method or process steps or any new combination disclosed.

Claims

1. An optical waveguide, characterized in that: The optical waveguide includes a waveguide matrix and a coupling-out region; wherein the coupling-out region includes a plurality of sub-regions, each of the sub-regions has a set spacing therebetween, and each of the sub-regions is provided with a plurality of periodically arranged optical structures.

2. The optical waveguide according to claim 1, wherein After the spacing between the sub-areas is increased, the emitted light rays after passing through the sub-areas are given a fixed phase, thereby adjusting the phase difference between the emitted light rays.

3. The optical waveguide according to claim 1, wherein The spacing between the sub-regions is in the interval [(k+0.1)P, (k+0.9)P], where P is the grating period and k is an arbitrary integer.

4. The optical waveguide according to claim 3, wherein The intervals between the sub-regions are the same.

5. The optical waveguide according to claim 3, wherein: The intervals between the sub-regions are different.

6. The optical waveguide according to claim 3, wherein: The sub-areas are arranged in an array or in a non-array.

7. The optical waveguide according to claim 1, wherein The sub-regions may have the same or different shapes.

8. The optical waveguide according to claim 1, wherein The shape of each sub-area is one or more of square, circle, triangle or irregular shape.

9. A near-eye display module, characterized in that: It comprises an image projection device and the optical waveguide as claimed in claims 1 to 8, wherein the image projection device is used to generate image light and project it to the corresponding coupling-in area on the optical waveguide, and after being transmitted through the optical waveguide, it is diffracted and output through the coupling-out area.

10. The near-eye display module according to claim 9, wherein: The light source of the image transmission device is a laser light source.

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