Micro-nano optical waveguide system, display device and grating period design method

Abstract

The invention relates to the technical field of diffractive optics, and provides a micro-nano optical waveguide system, a display device and a grating period design method, and the micro-nano optical waveguide system comprises a waveguide substrate, and a coupling-in grating and a coupling-out grating which are respectively arranged on the waveguide substrate; the coupling-in grating is used for coupling input light into the waveguide substrate; the coupling-out grating is used for coupling out the diffracted light in the waveguide substrate from the waveguide substrate for imaging; wherein the grating period d coupled out of the grating meets the following formula: # imgabs0 #; wherein # imgabs 1 # represents the wavelength of natural light; # imgabs2 represents the length of the coupled-out grating; and # imgabs3 # represents an exit pupil distance. According to the mode, the size of the grating area is coupled out of the period of the micro-nano structure through reasonable layout, stray light entering human eyes can be effectively reduced without coating a film or increasing the thickness of the lens, and the visual experience is greatly improved.

Description

Technical Field

[0001] The present invention relates to the field of diffraction optical technology, and in particular to a micro-nano optical waveguide system, a display device and a grating period design method. Background Art

[0002] Optical waveguide technology is recognized as the ultimate near-eye optical solution for the AR (Augmented Reality) industry. Like optical fiber, optical waveguides also use the principle of total reflection, allowing images to be transmitted losslessly within the glass. Compared to optical solutions such as prisms and curved surface reflections, optical waveguide technology can project a wide field of view on extremely thin lenses, with the advantages of being light, thin, highly transparent, and less obstructed. These advantages make optical waveguide AR glasses the closest in form to traditional glasses, and they can be moved and worn for a long time like ordinary glasses.

[0003] In the prior art, in order to absorb or reflect large-angle stray light, a thin film with angle-selective transmission is generally added to the outside of the waveguide. However, this method increases the thickness of the lens, and the angle-selective coating reduces the transmittance of the lens, affecting the line of sight. Summary of the invention

[0004] The present invention provides a micro-nano optical waveguide system, a display device and a grating period design method, which can realize the deflection of external stray light without the need for additional thin film and other structures, reduce the interference of ambient light on the field of vision, and greatly improve the visual experience and wearing safety.

[0005] The present invention provides a micro-nano optical waveguide system, comprising: a waveguide substrate and an in-coupling grating and an out-coupling grating respectively arranged on the waveguide substrate; the in-coupling grating is used to couple input light into the waveguide substrate; the out-coupling grating is used to couple light diffracted in the waveguide substrate out of the waveguide substrate for imaging; wherein the grating period d of the out-coupling grating satisfies the following formula: ;in, Indicates the wavelength of natural light; represents the length of the outcoupling grating; Indicates the pupil distance.

[0006] According to a micro-nano optical waveguide system provided by the present invention, the grating period d of the out-coupling grating also satisfies the following formula: ;in, Indicates the maximum wavelength of the light beam emitted by the optical machine; represents the refractive index of the waveguide substrate; It represents the angle between the input light and the normal direction of the waveguide substrate plane.

[0007] According to a micro-nano optical waveguide system provided by the present invention, the length of the out-coupling grating includes a horizontal length x and a vertical length y; the grating period d of the out-coupling grating is: ,or ; Wherein, α is the angle between the period direction of the outcoupling grating and the +x axis direction.

[0008] A micro-nano optical waveguide system provided by the present invention also includes a turning grating arranged on a waveguide substrate; the turning grating is used to receive light after passing through the coupling-in grating, and the coupling-out grating is used to receive light after passing through the turning grating; wherein, a line connecting the center of the coupling-in grating and the center of the turning grating is perpendicular to a line connecting the center of the coupling-out grating and the center of the turning grating, and the turning grating is used to change the transmission direction of the light after passing through the coupling-in grating.

[0009] According to a micro-nano optical waveguide system provided by the present invention, the turning grating includes a first turning grating and a second turning grating; the outcoupling grating includes a first outcoupling grating and a second outcoupling grating; the first turning grating is used to receive light after passing through the coupling-in grating, and the first outcoupling grating is used to receive light after passing through the first turning grating; the second turning grating is used to receive light after passing through the coupling-in grating, and the second outcoupling grating is used to receive light after passing through the second turning grating; wherein a first connecting line between the center of the coupling-in grating and the center of the first turning grating is perpendicular to a second connecting line between the center of the first outcoupling grating and the center of the first turning grating; a third connecting line between the center of the coupling-in grating and the center of the second turning grating is perpendicular to a fourth connecting line between the center of the second outcoupling grating and the center of the second turning grating; the first connecting line is parallel to the third connecting line; and the second connecting line is parallel to the fourth connecting line.

[0010] According to a micro-nano optical waveguide system provided by the present invention, the coupling-in grating is a region provided with a first periodic micro-nano unit structure; the coupling-out grating is a region provided with a second periodic micro-nano unit structure; and the turning grating is a region provided with a third periodic micro-nano unit structure.

[0011] The present invention also provides a display device, comprising the above-mentioned micro-nano optical waveguide system.

[0012] The present invention also provides a method for designing a grating period of an out-coupling grating, comprising: obtaining a theoretical value of a waveguide that does not generate rainbow patterns through K-vector analysis to obtain a first relationship; the first relationship is: ; Obtain the relationship between the field of view of the waveguide and the outcoupling grating parameters, and obtain the second relationship; The second relationship is: According to the first relation and the second relation, it is determined that the grating period d of the outcoupling grating satisfies the following formula: ;in, Indicates the wavelength of natural light; represents the length of the outcoupling grating; Indicates the pupil distance; Indicates the maximum angle of the light.

[0013] According to a grating period design method for an out-coupling grating provided by the present invention, a theoretical value of a waveguide not generating rainbow stripes is obtained by K vector diagram analysis, and a first relational expression is obtained, including: when external light is directly irradiated on the out-coupling grating and diffracted, an inner circle with a radius of 1 is obtained by combining the K vector diagram analysis to move a distance λ / d along the out-coupling grating vector direction, and if the inner circle after moving the distance λ / d does not overlap with the field of view area, the waveguide does not generate rainbow stripes; assuming that the angle between the out-coupling grating period direction and the +x-axis direction is α, then when the inner circle does not overlap with the field of view area, the first relational expression is obtained as follows: ,or ; Wherein, x is the horizontal length of the outcoupling grating; y is the vertical length of the outcoupling grating.

[0014] According to a grating period design method for an out-coupling grating provided by the present invention, according to the first relational expression and the second relational expression, it is determined that the grating period d of the out-coupling grating satisfies the following formula: ,or ; wherein α is the angle between the period direction of the out-coupling grating and the +x axis direction; the method for designing the grating period of the out-coupling grating also includes: obtaining a third relationship according to the transmission relationship of the waveguide to the light beam in the field of view; determining according to the third relationship that the grating period d of the out-coupling grating also satisfies the following formula: ;in, Indicates the maximum wavelength of the light beam emitted by the optical machine; represents the refractive index of the waveguide substrate; It represents the angle between the input light and the normal direction of the waveguide substrate plane.

[0015] The present invention provides a micro-nano optical waveguide system, a display device and a grating period design method. The micro-nano optical waveguide system comprises: a waveguide substrate and an in-coupling grating and an out-coupling grating respectively arranged on the waveguide substrate; the in-coupling grating is used to couple input light into the waveguide substrate; the out-coupling grating is used to couple light diffracted in the waveguide substrate out of the waveguide substrate for imaging; wherein the grating period d of the out-coupling grating satisfies the following formula: ;in, Indicates the wavelength of natural light; represents the length of the outcoupling grating; In the above manner, the present invention can effectively reduce the stray light entering the human eye and greatly improve the visual experience by reasonably arranging the period of the size of the out-coupling grating area without coating or increasing the thickness of the lens. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 This is one of the structural schematic diagrams of the micro-nano optical waveguide system provided by an embodiment of the present invention.

[0018] Figure 2 This is one of the structural schematic diagrams of the micro-nano optical waveguide system provided by an embodiment of the present invention.

[0019] Figure 3 4 is a schematic diagram of the field of view coordinates of the waveguide provided in an embodiment of the present invention.

[0020] Figure 4 It is a schematic diagram of K-vector diagram analysis provided by an embodiment of the present invention.

[0021] Figure 5 It is a schematic diagram of the structure of a two-partition waveguide provided in an embodiment of the present invention.

[0022] Figure 6 It is a schematic diagram of the structure of a three-partition waveguide provided in an embodiment of the present invention.

[0023] Figure 7 It is a schematic diagram of the structure of a five-partition waveguide provided in an embodiment of the present invention.

[0024] Figure 8 It is a flow chart of a method for designing a grating period of an outcoupling grating provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are 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.

[0026] In the description of the embodiments of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limitations on the embodiments of the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0027] In the embodiments of the present invention, unless otherwise clearly specified and limited, the first feature being "above" or "below" the second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "above" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0028] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0029] The present invention provides a micro-nano optical waveguide system, please refer to Figure 1 , Figure 1 It is one of the structural schematic diagrams of the micro-nano optical waveguide system provided by the embodiment of the present invention. In this embodiment, the micro-nano optical waveguide system may include a waveguide substrate 300 and an in-coupling grating 200 and an out-coupling grating 400 respectively disposed on the waveguide substrate 300.

[0030] The coupling-in grating 200 is used to couple the input light into the waveguide substrate 300 ; the coupling-out grating 400 is used to couple the light diffracted in the waveguide substrate 300 out of the waveguide substrate 300 for imaging.

[0031] Optionally, the input light can be external natural light or light emitted by an optical machine.

[0032] Micro-nano optical waveguide system is a technology that uses micron and nanometer scale waveguide structures to guide and manipulate light. Micro-nano optical waveguide system sets micro-nano unit structures on the surface of light waves, and by changing its period, the diffraction angle of the light beam at the coupling position can meet the total reflection condition, while the diffraction of the micro-nano structure at the coupling position destroys the total reflection condition and the output waveguide.

[0033] The micro-nano optical waveguide system is composed of a glass substrate provided with a periodic micro-nano unit structure, on which at least two regions of periodic micro-nano unit structures are provided, namely, an out-coupling grating and an in-coupling grating. The in-coupling grating 200 is a micro-nano structure for coupling a micro-image source light beam into the waveguide, and the out-coupling grating 400 is a micro-nano unit structure provided in front of the human eye 100 for diffracting the transmission light beam in the substrate out.

[0034] Therefore, the coupling-in grating 200 couples the input light into the waveguide substrate 300 and transmits it to the coupling-out grating 400 by total reflection. The coupling-out grating 400 couples the diffracted light out of the waveguide substrate 300 to enter the human eye 100 for imaging.

[0035] Since the outcoupling grating 400 is arranged in front of the human eye, in addition to the light beam in the waveguide, the external ambient light will be diffracted by the outcoupling grating in front of the human eye and emitted from the human eye, forming rainbow-shaped stray light.

[0036] Based on this, the embodiment of the present invention proposes a design method that can be used to eliminate external stray light from micro-nano optical waveguides. Based on ergonomics, through the special matching design of micro-nano structural areas and periods, no additional thin films or other structures are required to achieve the deviated emission of external stray light and prevent it from being received by the human eye. Reduce the interference of ambient light on the field of vision, greatly improve the visual experience and wearing safety. Compared with the original angle absorption film and other solutions, there is no need to add redundant structures, and it has the advantages of high transmittance, light and simple structure, and low cost.

[0037] Specifically, the grating period d of the outcoupling grating satisfies the following formula: .

[0038] in, Indicates the wavelength of natural light; represents the length of the outcoupling grating; Indicates the pupil distance.

[0039] When the grating period d of the out-coupling grating satisfies the above formula, the external stray light of the micro-nano optical waveguide can be eliminated.

[0040] In some embodiments, the grating period d of the outcoupling grating also satisfies the following formula: .

[0041] in, Indicates the maximum wavelength of the light beam emitted by the optical machine; represents the refractive index of the waveguide substrate; It represents the angle between the input light and the normal direction of the waveguide substrate plane.

[0042] In some embodiments, the length of the outcoupling grating includes a horizontal length x and a vertical length y; the grating period d of the outcoupling grating is: ,or ; Wherein, α is the angle between the period direction of the outcoupling grating and the +x axis direction.

[0043] See also Figure 2-Figure 4 , Figure 2 is one of the structural schematic diagrams of the micro-nano optical waveguide system provided by an embodiment of the present invention, Figure 3 is a schematic diagram of the field of view coordinates of a waveguide provided in an embodiment of the present invention; Figure 4 It is a schematic diagram of K-vector diagram analysis provided by an embodiment of the present invention.

[0044] The see-through FOV of the waveguide is related to the length of the outcoupling region L and the size of the pupil distance D, and the formula is tan Where see-through is the field of view that the human eye can see when the waveguide is placed in front of the human eye.

[0045] The see-through FOV is located at a radius of sin In the circle, such as Figure 4 As shown. External light is diffracted on the outcoupling grating area. In the k-diagram, it is equivalent to the inner circle with a radius of 1 moving along the grating vector direction. At this time, if the moved circle overlaps with the see-through FOV area, rainbow patterns may be observed in the corresponding area of ​​the waveguide, such as Figure 4 The middle dotted circle ① is shown as the light-colored overlapping area with the see-through FOV; if the moved circle does not overlap with the see-through FOV area, the waveguide will not produce rainbow patterns, as shown by the dotted circle ②.

[0046] If the waveguide does not produce rainbow patterns, the relationship must be satisfied: .

[0047] in, Can be seen as , The main wavelength of natural blue light can be used, which is usually 450nm.

[0048] So we can get .

[0049] Furthermore, since the optical waveguide needs to transmit the light beam within the field of view: , where n is the substrate refractive index. It is the maximum wavelength of the light beam emitted by the optical machine, usually 650nm for red light. is the periodic angle of the incident light beam along the coupling direction of the grating.

[0050] Optionally, n is the substrate refractive index, typically n≥1.8.

[0051] Furthermore, if Figure 3 As shown in the k-vector diagram, the coordinates of the upper right, upper left, lower left, and lower right of the See-through FOV area are: , , , ; Wherein, x is the horizontal length of the outcoupling grating region, and y is the vertical length.

[0052] Continue reading Figure 4 , the horizontal coordinate of the k-vector is kx / k0, and the vertical coordinate is ky / k0; where kx and ky represent the k-vector in the x-direction and the k-vector in the y-direction, respectively, and k0=2π / λ0; the k-vector is marked with the see-throughFOV represented by the large rectangle, the waveguide incident field of view FOV represented by the small rectangle, the inner circle represents the corresponding air refractive index n=1, the outer circle represents the corresponding air refractive index n>1, and the dotted circle ① represents the corresponding external light 1 (wavelength is ) The distance that the direct irradiation moves after diffraction occurs in the outcoupling grating area is ; The dotted circle ② represents the corresponding external light 2 (wavelength is ) The distance that the direct irradiation moves after diffraction occurs in the outcoupling grating area is The small rectangles and arrows indicate the propagation of the incident field of view inside the waveguide.

[0053] External light directly shines on the out-coupling grating area and diffracts. In the k-diagram, it is equivalent to the inner circle with a radius of 1 moving along the out-coupling grating vector direction. At this time, if the moved circle overlaps with the see-through FOV area, rainbow patterns may be observed in the corresponding area of ​​the waveguide, such as Figure 4The middle dotted circle ① is shown as the light-colored overlapping area with the see-through FOV; if the moved circle does not overlap with the see-through FOV area, the waveguide will not produce rainbow patterns, as shown by the dotted circle ②.

[0054] Assuming that the angle between the period direction of the out-coupling grating and the +x-axis direction is α, when the inner circle does not overlap with the See-through FOV area, the distance required to move is (divided into two angles): When: ; arctan( When: ; therefore, or .

[0055] In summary, the grating period d can be expressed as: or .

[0056] As described above, an embodiment of the present invention provides a micro-nano optical waveguide system, comprising: a waveguide substrate and an in-coupling grating and an out-coupling grating respectively arranged on the waveguide substrate; the in-coupling grating is used to couple input light into the waveguide substrate; the out-coupling grating is used to couple the light diffracted in the waveguide substrate out of the waveguide substrate for imaging; wherein the grating period d of the out-coupling grating satisfies the following formula: ; Wherein, λ represents the wavelength of natural light; L represents the length of the out-coupling grating; and D represents the pupil distance. In the above manner, the embodiment of the present invention can effectively reduce the stray light entering the human eye and greatly improve the visual experience by rationally arranging the period of the micro-nano structure of the out-coupling grating area without adding an angle selective film.

[0057] The micro-nano optical waveguide system of the embodiment of the present invention can be applied to waveguide structures of different partitions. Several embodiments are described below.

[0058] See also Figure 5 , Figure 5 It is a schematic diagram of the structure of a two-partition waveguide provided in an embodiment of the present invention.

[0059] The two-part waveguide includes a waveguide substrate 300, an in-coupling grating 200 and an out-coupling grating 400. The light passing through the in-coupling grating 200 is coupled out through the out-coupling grating 400.

[0060] In some embodiments, the micro-nano optical waveguide system further includes a turning grating disposed on the waveguide substrate, wherein the turning grating is used to receive light after passing through the in-coupled grating, and the out-coupled grating is used to receive light after passing through the turning grating.

[0061] The line connecting the center of the coupling-in grating and the center of the turning grating is perpendicular to the line connecting the center of the coupling-out grating and the center of the turning grating. The turning grating is used to change the transmission direction of the light after passing through the coupling-in grating.

[0062] In some embodiments, the coupling-in grating is a region provided with a first periodic micro-nano unit structure; the coupling-out grating is a region provided with a second periodic micro-nano unit structure; and the turning grating is a region provided with a third periodic micro-nano unit structure.

[0063] See also Figure 6 , Figure 6 It is a schematic diagram of the structure of a three-partition waveguide provided in an embodiment of the present invention.

[0064] The three-partition waveguide includes a waveguide substrate 300, an incoupling grating 200, a turning grating 600 and an outcoupling grating 400. The light passing through the incoupling grating 200 enters the turning grating 600 to change the propagation direction, and then is coupled out through the outcoupling grating 400.

[0065] In some embodiments, the turning grating includes a first turning grating and a second turning grating; the outcoupling grating includes a first outcoupling grating and a second outcoupling grating.

[0066] The first turning grating is used to receive light after passing through the coupling-in grating, and the first coupling-out grating is used to receive light after passing through the first turning grating; the second turning grating is used to receive light after passing through the coupling-in grating, and the second coupling-out grating is used to receive light after passing through the second turning grating.

[0067] Among them, a first line connecting the center of the coupling-in grating and the center of the first turning grating is perpendicular to a second line connecting the center of the first coupling-out grating and the center of the first turning grating; a third line connecting the center of the coupling-in grating and the center of the second turning grating is perpendicular to a fourth line connecting the center of the second coupling-out grating and the center of the second turning grating; the first line and the third line are parallel; and the second line and the fourth line are parallel.

[0068] See also Figure 7 , Figure 7 It is a schematic diagram of the structure of a five-partition waveguide provided in an embodiment of the present invention.

[0069] The five-partition waveguide includes a waveguide substrate, an in-coupling grating, a turning grating 1, a turning grating 2, an out-coupling grating 1 and an out-coupling grating 2. The light after passing through the in-coupling grating is divided into two paths, the first path is coupled out after passing through the turning grating 1 and the out-coupling grating 1, and the second path is coupled out after passing through the turning grating 2 and the out-coupling grating 2.

[0070] The present invention also provides a method for designing the grating period of an outcoupling grating, see Figure 8 , Figure 8: is a flow chart of a method for designing a grating period of an out-coupling grating provided in an embodiment of the present invention. In this embodiment, the method for designing a grating period of an out-coupling grating includes steps S810 to S830, and each step is specifically as follows: S810: Obtain a theoretical value of a waveguide that does not generate rainbow patterns through K-vector diagram analysis, and obtain a first relationship.

[0071] S820: Obtain the relationship between the field of view of the waveguide and the outcoupling grating parameters to obtain a second relationship.

[0072] S830: Determine the grating period of the outcoupling grating according to the first relational expression and the second relational expression.

[0073] Among them, the first relationship is: .

[0074] The second relationship is: .

[0075] The grating period d of the outcoupling grating satisfies the following formula: ;in, Indicates the wavelength of natural light; represents the length of the outcoupling grating; Indicates the pupil distance; Indicates the maximum angle of the light.

[0076] In an embodiment of the present invention, a grating period design method for a coupling grating is provided. The method reasonably arranges the period of the micro-nano structure of the grating area so that the micro-nano optical waveguide can eliminate external stray light, effectively reducing the stray light entering the human eye and greatly improving the visual experience.

[0077] In some embodiments, the step of obtaining a theoretical value of a waveguide that does not generate rainbow patterns by K-vector analysis to obtain the first relationship may specifically include: When external light directly shines on the out-coupling grating and diffracts, combined with the K vector diagram, the inner circle with a radius of 1 moves a distance of λ / d along the out-coupling grating vector direction. If the inner circle after moving a distance of λ / d does not overlap with the field of view, the waveguide will not produce rainbow patterns. Assuming that the angle between the out-coupling grating period direction and the +x axis direction is α, when the inner circle does not overlap with the field of view, the first relationship is obtained: ,or ; Wherein, x is the horizontal length of the outcoupling grating; y is the vertical length of the outcoupling grating.

[0078] In some embodiments, according to the first relation and the second relation, it is determined that the grating period d of the outcoupling grating satisfies the following formula: ,or ; Wherein, α is the angle between the period direction of the outcoupling grating and the +x axis direction.

[0079] The grating period design method of the outcoupling grating also includes: According to the transmission relationship of the waveguide to the light beam in the field of view, the third relationship is obtained; According to the third relationship, the grating period d of the outcoupling grating also satisfies the following formula: .

[0080] in, represents the maximum wavelength of the light beam emitted by the optical machine 500; represents the refractive index of the waveguide substrate; It represents the angle between the input light and the normal direction of the waveguide substrate plane.

[0081] On the other hand, the present invention further provides a display device, comprising the above-mentioned micro-nano optical waveguide system.

[0082] The display device is, for example, a near-eye display device. The near-eye display device includes a lens. The lens may include the diffraction light waveguide result of an embodiment of the present invention.

[0083] Near-Eye Display (NED) is a device that can display images directly within the user's field of view and can be used in applications such as virtual reality (VR), augmented reality (AR) and head-mounted display (HMD). The optomechanical system of a near-eye display device is responsible for converting electronic signals into visible light and presenting images in front of the user's eyes.

[0084] The display device may also be an augmented reality display device or a virtual reality display device.

[0085] In summary, the present invention provides a micro-nano optical waveguide system, a display device, and a grating period design method. The micro-nano optical waveguide system includes: a waveguide substrate, and an in-coupling grating and an out-coupling grating respectively arranged on the waveguide substrate; the in-coupling grating is used to couple the input light into the waveguide substrate; the out-coupling grating is used to couple the light diffracted in the waveguide substrate out of the waveguide substrate for imaging; wherein the grating period d of the out-coupling grating satisfies the following formula: ;in, Indicates the wavelength of natural light; represents the length of the outcoupling grating; In the above manner, the present invention can effectively reduce the stray light entering the human eye and greatly improve the visual experience by reasonably arranging the period of the size of the out-coupling grating area without coating or increasing the thickness of the lens.

[0086] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0087] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A micro-nano optical waveguide system, characterized in that: include: A waveguide substrate and an in-coupling grating and an out-coupling grating respectively arranged on the waveguide substrate; The coupling-in grating is used to couple the input light into the waveguide substrate; the coupling-out grating is used to couple the light diffracted in the waveguide substrate out of the waveguide substrate for imaging; Wherein, the grating period d of the outcoupling grating satisfies the following formula: ； in, Indicates the wavelength of natural light; represents the length of the outcoupling grating; Indicates the pupil distance.

2. The micro-nano optical waveguide system according to claim 1, characterized in that: The grating period d of the outcoupling grating also satisfies the following formula: ； in, Indicates the maximum wavelength of the light beam emitted by the optical machine; represents the refractive index of the waveguide substrate; It represents the angle between the input light and the normal direction of the plane where the waveguide substrate is located.

3. The micro-nano optical waveguide system according to claim 1 or 2, characterized in that: The length of the outcoupling grating includes a horizontal length x and a vertical length y; The grating period d of the outcoupling grating is: ,or ; Wherein, α is the angle between the period direction of the outcoupling grating and the +x axis direction.

4. The micro-nano optical waveguide system according to claim 1, characterized in that: Also includes a turning grating disposed on the waveguide substrate; The turning grating is used to receive light after passing through the coupling-in grating, and the coupling-out grating is used to receive light after passing through the turning grating; wherein, a line connecting the center of the coupling-in grating and the center of the turning grating is perpendicular to a line connecting the center of the coupling-out grating and the center of the turning grating, and the turning grating is used to change the transmission direction of the light after passing through the coupling-in grating.

5. The micro-nano optical waveguide system according to claim 4, characterized in that: The turning grating includes a first turning grating and a second turning grating; the outcoupling grating includes a first outcoupling grating and a second outcoupling grating; The first turning grating is used to receive the light after passing through the coupling-in grating, and the first coupling-out grating is used to receive the light after passing through the first turning grating; the second turning grating is used to receive the light after passing through the coupling-in grating, and the second coupling-out grating is used to receive the light after passing through the second turning grating; Wherein, a first line connecting the center of the coupling-in grating and the center of the first turning grating is perpendicular to a second line connecting the center of the first coupling-out grating and the center of the first turning grating; a third line connecting the center of the coupling-in grating and the center of the second turning grating is perpendicular to a fourth line connecting the center of the second coupling-out grating and the center of the second turning grating; The first connecting line is parallel to the third connecting line; the second connecting line is parallel to the fourth connecting line.

6. The micro-nano optical waveguide system according to any one of claims 4 or 5, characterized in that: The coupling-in grating is a region provided with a first periodic micro-nano unit structure; the coupling-out grating is a region provided with a second periodic micro-nano unit structure; and the turning grating is a region provided with a third periodic micro-nano unit structure.

7. A display device, characterized in that: The invention comprises the micro-nano optical waveguide system as claimed in any one of claims 1 to 6.

8. A method for designing the grating period of an outcoupling grating, characterized in that: include: The theoretical value of the waveguide without rainbow pattern is obtained by K-vector diagram analysis, and the first relationship is obtained; the first relationship is: ； The relationship between the field of view of the waveguide and the outcoupling grating parameters is obtained to obtain a second relationship; the second relationship is: ； According to the first relational expression and the second relational expression, it is determined that the grating period d of the outcoupling grating satisfies the following formula: ； in, Indicates the wavelength of natural light; represents the length of the outcoupling grating; Indicates the pupil distance; Indicates the maximum angle of the light.

9. The method for designing the grating period of the outcoupling grating according to claim 8, characterized in that: The theoretical value of the waveguide not generating rainbow patterns is obtained by analyzing the K-vector diagram, and the first relationship is obtained, including: When external light is directly irradiated on the out-coupling grating and diffracted, the inner circle with a radius of 1 is analyzed by combining the K vector diagram to move a distance of λ / d along the out-coupling grating vector direction. If the inner circle after moving the distance of λ / d does not overlap with the field of view, the waveguide will not produce rainbow patterns. Assuming that the angle between the period direction of the outcoupling grating and the +x axis direction is α, when the inner circle does not overlap with the field of view, the first relationship is obtained as follows: ,or ; Wherein, x is the horizontal length of the outcoupling grating; y is the vertical length of the outcoupling grating.

10. The method for designing the grating period of the outcoupling grating according to claim 9, characterized in that: According to the first relational expression and the second relational expression, it is determined that the grating period d of the outcoupling grating satisfies the following formula: ,or ; Where α is the angle between the outcoupling grating period direction and the +x axis direction; The method for designing the grating period of the out-coupling grating further includes: obtaining a third relationship according to the transmission relationship of the waveguide to the light beam in the field of view; and determining according to the third relationship that the grating period d of the out-coupling grating also satisfies the following formula: ； in, Indicates the maximum wavelength of the light beam emitted by the optical machine; represents the refractive index of the waveguide substrate; It represents the angle between the input light and the normal direction of the plane where the waveguide substrate is located.

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