Optical waveguide system for large-field-angle full-color display and near-to-eye display

Abstract

The invention relates to an optical waveguide system for large-field-angle full-color display and a near-to-eye display. The optical waveguide system comprises an optical waveguide sheet, a coupling-in grating, a turning grating and a coupling-out grating, wherein the turning grating and the coupling-out grating are respectively arranged on two opposite side surfaces of the optical waveguide sheet, the orthographic projection of the section, far away from the coupling-in grating, of the turning grating and the orthographic projection of the section, close to the coupling-in grating, of the coupling-out grating in the thickness direction are crossed and overlapped, and an even-order expansion area is formed; the near-eye display comprises an image source device and the optical waveguide system, and the image source device is arranged on the light incident side of the coupling-in grating and used for emitting light beams to the coupling-in grating. The large-field-angle full-color display device has the advantages that the structural size is reduced under large-field-angle full-color display, the bright band phenomenon is avoided, and uniformity is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of optical elements, and in particular to an optical waveguide system and a near-eye display for full-color display with a large viewing angle. Background Art

[0002] Augmented reality (AR) technology involves integrating display modules into glasses, loading virtual information into the user's field of view and integrating it with the real environment. As a representative of the future of information interaction, AR technology is expected to significantly free humans from hands and enhance social productivity. AR technology is considered a next-generation computing platform with the potential to replace current mobile phones. With the rapid development of artificial intelligence (AI), the emergence of numerous large-scale AI models, and the rise of AI glasses, sales have surged in the international market, and the integration of AI and AR glasses has garnered increasing attention and recognition. Over the years, AR technology has evolved from its initial prism approach to freeform surfaces or freeform prisms, and further to waveguide solutions. Waveguide solutions initially encompassed three technologies: grating waveguides, arrayed waveguides, and holographic waveguides, all of which were developed in parallel. Grating waveguide technology, with its high degree of design freedom and scalability based on semiconductor processes, has become a focus of attention for many AR manufacturers. The development of grating waveguide technology has evolved from initially narrow-field-of-view single-green displays to today's narrow-field-of-view full-color displays. Simultaneously, international research is also underway to develop large-field-of-view full-color grating waveguide displays. Meta's 70° monolithic full-color grating waveguide display technology, launched in 2024, has attracted widespread attention and discussion. Further development of grating waveguide technology will inevitably require breaking through the bottleneck of large-field-of-view full-color display technology and further reducing the thickness and area of large-field-of-view full-color grating waveguides.

[0003] At present, there are two main schemes for large field of view grating waveguide technology: (1) one-dimensional grating scheme, in which the light beam is coupled in the coupling-in region, and longitudinal pupil expansion is achieved in the turning region, and transverse pupil expansion and outcoupling are achieved in the outcoupling region; (2) two-dimensional grating scheme, in which the light beam is coupled through a one-dimensional grating in the coupling-in region, and two-dimensional pupil expansion and outcoupling are achieved in the outcoupling region. However, both of these large field of view full-color grating waveguide schemes have significant defects. Specifically, under large field of view conditions, the area of the turning region of the one-dimensional grating scheme is significantly increased, making it difficult to adapt this large area of grating area to the current eyeglass design. Under large field of view conditions, although the area of the grating area of the two-dimensional grating scheme can be effectively controlled, bright bands will appear in the light field or beam tracking process within the range of eye movement, which has a significant negative impact on the display effect; at the same time, suppressing the bright bands will also damage the performance of the grating waveguide. Therefore, the above two schemes face difficult-to-overcome obstacles in achieving large field of view full-color display.

[0004] The Chinese patent with the authorization announcement number CN113703091B discloses an optical waveguide system, comprising: an optical waveguide plate; an in-coupling grating, the in-coupling grating being arranged on a side surface of the optical waveguide plate, the in-coupling grating being a one-dimensional grating, the in-coupling grating being used to couple light emitted by an external micro-projector into the optical waveguide plate; a turning grating, the turning grating being arranged on the optical waveguide plate and being located on the same side surface or on a different side surface as the in-coupling grating, the turning grating being a two-dimensional grating, the turning grating being used to receive light from the in-coupling grating; and an out-coupling grating being arranged on the optical waveguide plate. On the other side surface of the optical waveguide plate, projections of the turning grating and the outcoupling grating on the optical waveguide plate at least partially overlap, the outcoupling grating is a one-dimensional grating, and is used to receive light from the turning grating and the incoupling grating and couple the light out of the optical waveguide plate; the turning grating is a two-dimensional multilayer grating, the number of layers of the two-dimensional multilayer grating is greater than 1 and less than or equal to 10, and the height of each layer is greater than or equal to 30 nanometers and less than or equal to 300 nanometers, and the gratings of each layer are two-dimensional and have the same structure; the period of the turning grating is the value of the period of the incoupling grating divided by the square root of two.

[0005] The above-mentioned existing technical solutions have the following defects: the above-mentioned optical waveguide system belongs to the odd-order extended grating waveguide type, which means that the light beam reaches the outcoupling area after undergoing an odd number of diffraction turns in the turning area. This process not only increases the lateral size of the product, but also significantly increases the size of the turning area and the outcoupling area under large field of view conditions. Even if a cross-design is performed to a certain extent, the longitudinal size is still huge, which makes it difficult to effectively match the appearance design of current augmented reality glasses; in addition, this design will inevitably lead to the bright band problem in the display effect, that is, the coupled light beam directly enters the outcoupling area without pupil expansion, thereby causing the bright band phenomenon. The appearance of the bright band will weaken the display effect of the grating waveguide and, as a display defect, affect the visual experience. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the first object of the present invention is to provide an optical waveguide system for full-color display with a large field of view, which has the advantages of reducing structural size, avoiding bright band phenomenon, and improving uniformity under full-color display with a large field of view.

[0007] The second object of the present invention is to provide a near-eye display, which has the advantages of being easy to match the appearance of augmented reality glasses worn by the public and avoiding the appearance of bright bands that weaken the display effect.

[0008] To achieve the above first object, the present invention provides the following technical solutions: An optical waveguide system for full-color display with a large viewing angle comprises an optical waveguide plate, an incoupling grating, a turning grating and an outcoupling grating; wherein, The coupling-in grating, the turning grating and the coupling-out grating are each independently a one-dimensional grating; The coupling-in grating is disposed on one side surface of the optical waveguide plate, and is used to couple the light beam into the optical waveguide plate and propagate the light beam within the optical waveguide plate; The turning grating and the outcoupling grating are respectively arranged on two opposite side surfaces of the optical waveguide plate, and the orthographic projections of the section of the turning grating away from the incoupling grating and the section of the outcoupling grating close to the incoupling grating in the thickness direction cross and overlap to form an even-order expansion area; The turning grating is used to receive the light beam transmitted by the coupling-in grating and guide the light beam to the coupling-out grating after being refracted by even-order diffraction; The outcoupling grating is used to receive the light beam propagated by the turning grating and couple the light beam out of the optical waveguide plate.

[0009] Furthermore, the material of the optical waveguide is one of optical glass, optical resin and silicon carbide; And / or, the refractive index of the optical waveguide is 1.7 to 2.7; And / or, the thickness of the optical waveguide sheet is 0.2-1.5 mm.

[0010] Furthermore, the optical waveguide sheet is provided with one or more; And / or, when there are a plurality of optical waveguide sheets, these optical waveguide sheets are stacked in a thickness direction, and at least one optical waveguide sheet is provided with the coupling-in grating, the turning grating and the coupling-out grating; And / or, when there are multiple optical waveguide sheets, a portion of an upper optical waveguide sheet is embedded in the grating gap of the one-dimensional grating on the lower optical waveguide sheet.

[0011] Furthermore, a pair of turning gratings are provided and are respectively arranged on both sides of the coupling-in grating; There are two outcoupling gratings, which are arranged in one-to-one correspondence with the pair of turning gratings respectively; Alternatively, the outcoupling grating is provided with one and is arranged corresponding to the pair of turning gratings.

[0012] Furthermore, in the optical waveguide system, the light beam transmission path must satisfy the grating vector closure relationship, that is, the grating vectors of the coupling-in grating, the turning grating and the coupling-out grating can form a closed triangle to ensure that the light beam entering the coupling-in grating can be coupled out from the coupling-out grating at the same angle.

[0013] Furthermore, the one-dimensional grating in the even-order expansion region satisfies the condition that the light beam is diffracted an even number of times by the turning grating, and expands the pupil of the light beam in the longitudinal direction.

[0014] Furthermore, the one-dimensional grating is a straight grating, a blazed grating, a tilted grating, a double-ridge grating and a one-dimensional multi-layer grating, or a combination thereof; And / or, the material of the one-dimensional grating is one or a composite material of several of optical glass, optical resin, silicon carbide, titanium dioxide and silicon nitride.

[0015] Furthermore, the coupling grating is arranged on a circular coupling area with a diameter of 3 to 5 mm, or on a polygonal coupling area; And / or, the duty cycle of the coupling-in grating is 20-80%; And / or, the height of the coupling-in grating is 20-300 nm; And / or, the period of the coupling-in grating is 200-2000 nm; And / or, when the coupling-in grating includes a tilted grating, the tilt angle of the tilted grating is 20-90°; And / or, when the coupling-in grating comprises a blazed grating, the blazed grating has a blaze angle of 10-45° and a reverse blaze angle of 60-90°; And / or, when the coupling-in grating includes a one-dimensional multilayer grating, the number of layers of the one-dimensional multilayer grating is 2 to 4.

[0016] Furthermore, the coupling grating is arranged on a circular coupling area with a diameter of 3 to 5 mm, or on a polygonal coupling area; And / or, the duty cycle of the coupling-in grating is 60-80%; And / or, the height of the coupling-in grating is 130-200 nm; And / or, the period of the coupling-in grating is 250-350 nm; And / or, when the coupling-in grating includes a tilted grating, the tilt angle of the tilted grating is 45-60°; And / or, when the coupling-in grating comprises a blazed grating, the blazed grating has a blaze angle of 15-45° and a reverse blaze angle of 60-90°; And / or, when the coupling-in grating includes a one-dimensional multilayer grating, the number of layers of the one-dimensional multilayer grating is 2 to 4.

[0017] Furthermore, the turning grating is arranged on a polygonal turning area; And / or, the duty cycle of the turning grating is 20-80%; And / or, the height of the turning grating is 20-300 nm; And / or, the period of the turning grating is 200-2000 nm; And / or, when the turning grating includes an inclined grating, the inclined grating has an inclination angle of 20 to 90°; And / or, when the turning grating includes a blazed grating, the blazed grating has a blaze angle of 10 to 45° and a reverse blaze angle of 60 to 90°; And / or, when the turning grating includes a one-dimensional multilayer grating, the number of layers of the one-dimensional multilayer grating is 2 to 4.

[0018] Furthermore, the turning grating is arranged on a polygonal turning area; And / or, the duty cycle of the turning grating is 40-80%; And / or, the height of the turning grating is 50-170 nm; And / or, the period of the turning grating is 250-350 nm; And / or, when the turning grating includes an inclined grating, the inclined grating has an inclination angle of 45° to 75°; And / or, when the turning grating includes a blazed grating, the blazed grating has a blaze angle of 15 to 45° and a reverse blaze angle of 60 to 90°; And / or, when the turning grating includes a one-dimensional multilayer grating, the number of layers of the one-dimensional multilayer grating is 2 to 4.

[0019] Furthermore, the outcoupling grating is arranged on a polygonal outcoupling area; And / or, the duty cycle of the outcoupling grating is 20-80%; And / or, the height of the outcoupling grating is 20-300 nm; And / or, the period of the outcoupling grating is 200-2000 nm; And / or, when the outcoupling grating includes a tilted grating, the tilt angle of the tilted grating is 20-90°; And / or, when the outcoupling grating comprises a blazed grating, the blazed grating has a blaze angle of 10 to 45° and a reverse blaze angle of 60 to 90°; And / or, when the outcoupling grating includes a one-dimensional multilayer grating, the number of layers of the one-dimensional multilayer grating is 2 to 4.

[0020] Furthermore, the outcoupling grating is arranged on a polygonal outcoupling area; And / or, the duty cycle of the outcoupling grating is 50-80%; And / or, the height of the outcoupling grating is 70-170 nm; And / or, the period of the outcoupling grating is 250-350 nm; And / or, when the outcoupling grating includes a tilted grating, the tilt angle of the tilted grating is 45-60°; And / or, when the outcoupling grating comprises a blazed grating, the blazed grating has a blaze angle of 15-45° and a reverse blaze angle of 60-90°; And / or, when the outcoupling grating includes a one-dimensional multilayer grating, the number of layers of the one-dimensional multilayer grating is 2 to 4.

[0021] To achieve the above second purpose, the present invention provides the following technical solutions: A near-eye display comprises an image source device and the optical waveguide system according to the above, wherein the image source device is arranged on the light incident side of the coupling grating and is used to incident a light beam onto the coupling grating.

[0022] In summary, the beneficial technical effects of the present invention are: 1. The optical waveguide system of the present invention arranges an in-coupling grating, a turning grating, and an out-coupling grating laterally on an optical waveguide sheet. Adjacent sections of the turning grating and the out-coupling grating overlap on both sides of the waveguide sheet to form even-order expansion regions. Since commonly used augmented reality glasses and existing myopia glasses are similar in shape—flat, with significantly larger lateral dimensions than longitudinal dimensions—this crossing arrangement can directly reduce the lateral dimensions of the optical waveguide system at wide viewing angles, thereby adapting to the shape of commonly used lenses. Furthermore, after even-order expansion at the turning grating, light reaches the out-coupling grating, avoiding the appearance of bright bands in light fields or ray chasing within the eye's range, thereby improving the uniformity of the optical waveguide system. 2. Compared with traditional solutions, the turning grating is usually located above or below the coupling grating. This layout will increase the longitudinal size of the optical waveguide system. By using an even-order turning grating and overlapping the coupling grating, the present invention can effectively suppress the longitudinal size of the optical waveguide system, thereby adapting to the shape of commonly used lenses. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the structure of the optical waveguide system of embodiment 1 of the present invention.

[0024] Figure 2 It is a schematic structural diagram of the even-numbered extension area of Example 1 of the present invention.

[0025] Figure 3 Schematic diagram of the connection relationship between the coupling-in grating, the turning grating and the coupling-out grating in embodiment 2 of the present invention.

[0026] Figure 4 Schematic diagram of the structure of the one-dimensional grating of Examples 2 to 4 of the present invention.

[0027] Figure 5 It is a schematic cross-sectional structural diagram of the optical waveguide system of Example 5 of the present invention.

[0028] Figure 6 Schematic diagram of the structure of the optical waveguide system of Example 6 of the present invention.

[0029] Figure 7 2 is a schematic structural diagram of an optical waveguide system according to a seventh embodiment of the present invention.

[0030] Figure 8 It is a schematic structural diagram of the near-eye display of Example 8 of the present invention.

[0031] Figure 9 Schematic diagram of the structure of the optical waveguide system of comparative example 1 of the present invention.

[0032] Figure 10 Schematic diagram of the K domain of the optical waveguide system of Example 1 of the present invention.

[0033] Figure 11 This is a simulation diagram of the out-coupling light field of the optical waveguide system of Example 1 of the present invention.

[0034] Figure 12 This is a simulation diagram of the out-coupling light field of the optical waveguide system of comparative example 1 of the present invention.

[0035] In the figure, 1. Optical waveguide; 2. In-coupling grating; 3. Turning grating; 4. Out-coupling grating; 5. Image source device. DETAILED DESCRIPTION

[0036] In order to make the technical means, creative features, objectives and functions achieved by the present invention clearer and easier to understand, the present invention is further explained below with reference to the accompanying drawings and specific implementation methods. Example

[0037] Example 1: Reference Figure 1 and Figure 2 , is an optical waveguide system for full-color display with a large viewing angle disclosed in the present invention, comprising an optical waveguide plate, an incoupling grating, a turning grating and an outcoupling grating; wherein, The coupling-in grating, the turning grating and the coupling-out grating are each independently a one-dimensional grating; The coupling-in grating is arranged on one side surface of the optical waveguide plate, and is used to couple the light beam into the optical waveguide plate and propagate the light beam in the optical waveguide plate; The turning grating and the outcoupling grating are respectively arranged on two opposite sides of the optical waveguide plate, and the orthographic projections of the section of the turning grating away from the incoupling grating and the section of the outcoupling grating close to the incoupling grating in the thickness direction cross and overlap to form an even-order expansion area; The turning grating is used to receive the light beam transmitted by the coupling-in grating and guide the light beam to the coupling-out grating after being refracted by even-order diffraction. The outcoupling grating is used to receive the light beam transmitted by the turning grating and couple the light beam out of the optical waveguide.

[0038] In an optical waveguide system, the light beam transmission path must satisfy the grating vector closure relationship, that is, the grating vectors of the coupling-in grating, the turning grating, and the coupling-out grating can form a closed triangle to ensure that the light beam entering the coupling-in grating can be coupled out from the coupling-out grating at the same angle.

[0039] The one-dimensional grating in the even-order expansion area satisfies the condition that the light beam is diffracted an even number of times by the turning grating and expands the pupil of the light beam in the longitudinal direction.

[0040] Example 2: Reference Figure 3 , is an optical waveguide system for full-color display with a large field of view disclosed by the present invention. The difference from Example 1 is that the material of the optical waveguide plate is silicon carbide; the refractive index of the optical waveguide plate is 2.6; and the thickness is 0.7 mm.

[0041] Reference Figure 4 The type of coupling grating is a blazed grating; the material of the coupling grating is silicon carbide; the coupling grating is arranged on a circular outcoupling area with a diameter of 3.4 mm; the duty cycle of the coupling grating is 80%; the height of the coupling grating is 136 nm; the period of the coupling grating is 301 nm; when the coupling grating includes a blazed grating, the blazed angle of the blazed grating is 30° and the anti-blazed angle is 88°.

[0042] The type of the turning grating is a blazed grating; the material of the turning grating is silicon carbide; the turning grating is arranged on a polygonal turning area; the duty cycle of the turning grating is 50~80%; the height of the turning grating is 88nm; and the period of the turning grating is 301nm.

[0043] The outcoupling grating is a blazed grating made of silicon carbide. The outcoupling grating is arranged on a 26.2×18.2mm rectangular outcoupling area, which can achieve an eye movement range of 12×10mm and an exit pupil distance of 18mm. The duty cycle of the outcoupling grating is 50~80%. The height of the outcoupling grating is 70nm. The period of the outcoupling grating is 301nm.

[0044] Example 3: This is an optical waveguide system for full-color display with a large viewing angle disclosed by the present invention. The difference from Example 1 is that the material of the optical waveguide plate is silicon carbide; the refractive index of the optical waveguide plate is 2.6; and the thickness is 0.7 mm.

[0045] Reference Figure 4The type of coupling-in grating is tilted grating; the material of the coupling-in grating is silicon carbide; the coupling-in grating is arranged on a circular out-coupling area; the duty cycle of the coupling-in grating is 61%; the height of the coupling-in grating is 150nm; the period of the coupling-in grating is 301nm; the tilt angle of the tilted grating is 51° (angle with the horizontal direction).

[0046] The type of turning grating is tilted grating; the material of the turning grating is silicon carbide; the turning grating is arranged on a polygonal turning area; the turning grating is arranged on a polygonal turning area; the duty cycle of the turning grating is 53%; the height of the turning grating is 93~170nm; the tilt angle of the tilted grating is 62° (angle with the horizontal direction).

[0047] The outcoupling grating is a tilted grating. The outcoupling grating is made of silicon carbide and is arranged on a rectangular outcoupling area. The duty cycle of the outcoupling grating is 71%. The height of the outcoupling grating is 100-162 nm. The period of the outcoupling grating is 301 nm. The tilt angle of the tilted grating is 49° (with respect to the horizontal direction).

[0048] The one-dimensional grating in the even-order expansion area satisfies the condition that the light beam is diffracted an even number of times by the turning grating and expands the pupil of the light beam in the longitudinal direction.

[0049] Example 4: This is an optical waveguide system for full-color display with a large field of view disclosed by the present invention. The difference from Example 1 is that the material of the optical waveguide plate is silicon carbide; the refractive index of the optical waveguide plate is 2.6; and the thickness is 0.7 mm.

[0050] Reference Figure 4 The type of the coupling-in grating is a straight grating; the material of the coupling-in grating is silicon carbide; the coupling-in grating is arranged on a circular out-coupling area; the duty cycle of the coupling-in grating is 71%; the height of the coupling-in grating is 189nm; and the period of the coupling-in grating is 301nm.

[0051] The type of the turning grating is straight grating; the material of the turning grating is silicon carbide; the turning grating is arranged on a polygonal turning area; the duty cycle of the turning grating is 40~70%; the height of the turning grating is 50~150nm; and the period of the turning grating is 301nm.

[0052] The outcoupling grating is a straight grating; the material of the outcoupling grating is silicon carbide; the outcoupling grating is arranged on a rectangular outcoupling area; the duty cycle of the outcoupling grating is 50~70%; the height of the outcoupling grating is 50~150nm; and the period of the outcoupling grating is 301nm.

[0053] The one-dimensional grating in the even-order expansion area satisfies the condition that the light beam is diffracted an even number of times by the turning grating and expands the pupil of the light beam in the longitudinal direction.

[0054] Example 5: Reference Figure 5 , is an optical waveguide system for full-color display with a large field of view disclosed in the present invention. The difference from Example 2 is that a plurality of optical waveguide sheets are provided, and these optical waveguide sheets are stacked along the thickness direction, and at least one optical waveguide sheet is provided with an in-coupling grating, a turning grating, and an out-coupling grating; the optical waveguide sheet on the upper layer is partially embedded in the grating gap of the one-dimensional grating on the optical waveguide sheet on the lower layer.

[0055] Example 6: Reference Figure 6 , is an optical waveguide system for full-color display with a large field of view disclosed in the present invention. The difference from Example 2 is that a pair of turning gratings are provided and are arranged on both sides of the coupling-in grating respectively; two out-coupling gratings are provided and are arranged in one-to-one correspondence with the pair of turning gratings respectively.

[0056] In an optical waveguide system, the light beam transmission path must satisfy the grating vector closure relationship, that is, the grating vectors of the coupling-in grating, the turning grating, and the coupling-out grating can form a closed triangle to ensure that the light beam entering the coupling-in grating can be coupled out from the coupling-out grating at the same angle.

[0057] Example 7: Reference Figure 7 , is an optical waveguide system for full-color display with a large field of view disclosed in the present invention. The difference from Example 2 is that a pair of turning gratings are provided and arranged on both sides of the coupling-in grating respectively; one outcoupling grating is provided and arranged corresponding to the pair of turning gratings.

[0058] In an optical waveguide system, the light beam transmission path must satisfy the grating vector closure relationship, that is, the grating vectors of the coupling-in grating, the turning grating, and the coupling-out grating can form a closed triangle to ensure that the light beam entering the coupling-in grating can be coupled out from the coupling-out grating at the same angle.

[0059] Example 8: Reference Figure 8 , is a near-eye display disclosed in the present invention, comprising an image source device and an optical waveguide system of any one of embodiments 2 to 7, wherein the image source device is arranged on the light incident side of the coupling grating, and the image source device is used to incident a light beam onto the coupling grating. Comparative Example

[0060] Comparative Example 1: Reference Figure 9 , is an optical waveguide system for full-color display with a large field of view disclosed in the present invention. The difference from Example 2 is that the orthographic projections of the section of the turning grating away from the coupling-in grating and the section of the out-coupling grating close to the coupling-in grating in the thickness direction do not overlap.

[0061] The material of the optical waveguide is glass; the refractive index of the optical waveguide is glass; and the thickness is 0.7 mm.

[0062] The type of the coupling grating is a blazed grating; the material of the coupling grating is titanium oxide; the coupling grating is arranged with a diameter of 4 mm; the duty cycle of the coupling grating is 100%; and the period of the coupling grating is 348 nm.

[0063] The type of the turning grating is straight grating; the material of the turning grating is titanium oxide; the turning grating is arranged in the polygonal area as shown in the figure; the duty cycle of the turning grating is 40~60%; the height of the turning grating is 70nm; and the period of the turning grating is 246nm.

[0064] The outcoupling grating is a straight grating; the material of the outcoupling grating is titanium oxide; the outcoupling grating is arranged in 26.2x18mm; the duty cycle of the outcoupling grating is 30~60%; the height of the outcoupling grating is 70nm; and the period of the outcoupling grating is 348nm. Performance testing

[0065] Experimental Example 1: Visualization of the optical waveguide K-domain layout of the optical waveguide system obtained in Example 1 was performed. Figure 10 The figure shows a schematic diagram of the K domain of an even-order one-dimensional grating waveguide, where the inner circle is a schematic diagram of the refractive index of air, the outer circle is a schematic diagram of the refractive index of the waveguide, the shaded box is the field of view angle range of the optical machine projection beam, and the different positions of the box and the corresponding arrows represent the coupling-in, turning and coupling-out of the optical machine projection beam.

[0066] The outcoupling light field simulation diagram of the optical waveguide system obtained in Example 1 and Comparative Example 1 is shown in the following figure: Figures 11-12 As shown in the figure, it can be seen that in the solution of comparative example 1, bright bands are unavoidable in the display effect. The coupled light beam directly enters the outcoupling area without pupil expansion, which will cause the appearance of bright bands. The appearance of bright bands will inhibit the display effect of the grating waveguide, and the bright bands are also a display defect.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. An optical waveguide system for full-color display with a wide viewing angle, characterized by: It includes an optical waveguide, an in-coupling grating, a turning grating and an out-coupling grating; wherein, The coupling-in grating, the turning grating and the coupling-out grating are each independently a one-dimensional grating; The coupling-in grating is disposed on one side surface of the optical waveguide plate, and is used to couple the light beam into the optical waveguide plate and propagate the light beam within the optical waveguide plate; The turning grating and the outcoupling grating are respectively arranged on two opposite side surfaces of the optical waveguide plate, and the orthographic projections of the section of the turning grating away from the incoupling grating and the section of the outcoupling grating close to the incoupling grating in the thickness direction cross and overlap to form an even-order expansion area; The turning grating is used to receive the light beam transmitted by the coupling-in grating and guide the light beam to the coupling-out grating after being refracted by even-order diffraction; The outcoupling grating is used to receive the light beam propagated by the turning grating and couple the light beam out of the optical waveguide plate.

2. The optical waveguide system for full-color display with a large viewing angle according to claim 1, characterized in that: The material of the optical waveguide is one of optical glass, optical resin and silicon carbide; And / or, the refractive index of the optical waveguide is 1.7 to 2.7; And / or, the thickness of the optical waveguide sheet is 0.2-1.5 mm.

3. The optical waveguide system for full-color display with a large viewing angle according to claim 1, characterized in that: The optical waveguide sheet is provided with one or more; And / or, when there are a plurality of optical waveguide sheets, these optical waveguide sheets are stacked in a thickness direction, and at least one optical waveguide sheet is provided with the coupling-in grating, the turning grating and the coupling-out grating; And / or, when there are multiple optical waveguide sheets, a portion of an upper optical waveguide sheet is embedded in the grating gap of the one-dimensional grating on the lower optical waveguide sheet.

4. The optical waveguide system for full-color display with a large viewing angle according to claim 1, characterized in that: The turning grating is provided in a pair and is respectively arranged on both sides of the coupling-in grating; There are two outcoupling gratings, which are arranged in one-to-one correspondence with the pair of turning gratings respectively; Alternatively, the outcoupling grating is provided with one and is arranged corresponding to the pair of turning gratings.

5. The optical waveguide system for full-color display with a large viewing angle according to claim 1, characterized in that: The one-dimensional grating in the even-order expansion region satisfies the condition that the light beam is diffracted an even number of times by the turning grating, and expands the pupil of the light beam in the longitudinal direction.

6. The optical waveguide system for full-color display with a large viewing angle according to claim 1, characterized in that: The one-dimensional grating is one or a combination of straight grating, blazed grating, tilted grating, double-ridge grating and one-dimensional multi-layer grating; And / or, the material of the one-dimensional grating is one or a composite material of several of optical glass, optical resin, silicon carbide, titanium dioxide and silicon nitride.

7. The optical waveguide system for full-color display with a large viewing angle according to claim 6, characterized in that: The coupling grating is arranged on a circular coupling area with a diameter of 3 to 5 mm, or arranged on a polygonal coupling area; And / or, the duty cycle of the coupling-in grating is 20-80%; And / or, the height of the coupling-in grating is 20-300 nm; And / or, the period of the coupling-in grating is 200-2000 nm; And / or, when the coupling-in grating includes a tilted grating, the tilt angle of the tilted grating is 20-90°; And / or, when the coupling-in grating comprises a blazed grating, the blazed grating has a blaze angle of 10-45° and a reverse blaze angle of 60-90°; And / or, when the coupling-in grating includes a one-dimensional multilayer grating, the number of layers of the one-dimensional multilayer grating is 2 to 4.

8. The optical waveguide system for full-color display with a large viewing angle according to claim 6, characterized in that: The turning grating is arranged on a polygonal turning area; And / or, the duty cycle of the turning grating is 20-80%; And / or, the height of the turning grating is 20-300 nm; And / or, the period of the turning grating is 200-2000 nm; And / or, when the turning grating includes an inclined grating, the inclined grating has an inclination angle of 20 to 90°; And / or, when the turning grating includes a blazed grating, the blazed grating has a blaze angle of 10 to 45° and a reverse blaze angle of 60 to 90°; And / or, when the turning grating includes a one-dimensional multilayer grating, the number of layers of the one-dimensional multilayer grating is 2 to 4.

9. The optical waveguide system for full-color display with a large viewing angle according to claim 6, characterized in that: The outcoupling grating is arranged on a polygonal outcoupling area; And / or, the duty cycle of the outcoupling grating is 20-80%; And / or, the height of the outcoupling grating is 20-300 nm; And / or, the period of the outcoupling grating is 200-2000 nm; And / or, when the outcoupling grating includes a tilted grating, the tilt angle of the tilted grating is 20-90°; And / or, when the outcoupling grating comprises a blazed grating, the blazed grating has a blaze angle of 10 to 45° and a reverse blaze angle of 60 to 90°; And / or, when the outcoupling grating includes a one-dimensional multilayer grating, the number of layers of the one-dimensional multilayer grating is 2 to 4.

10. A near-eye display, characterized in that: The optical waveguide system comprises an image source device and the optical waveguide system according to any one of claims 1 to 9, wherein the image source device is arranged on the light incident side of the coupling grating, and the image source device is used to incident a light beam onto the coupling grating.

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