Diffractive optical waveguide device and augmented reality display device

Abstract

The invention discloses a diffractive optical waveguide device and augmented reality display equipment, and the diffractive optical waveguide device comprises a diffractive optical waveguide and an optical film layer disposed on the world side of the diffractive optical waveguide. In the visible light range: for light irradiated from the outside toward the diffractive optical waveguide and having an incidence angle theta in the range of phi 1 < = theta < = 85 degrees, the light has a first average reflectance R1, 30% lt averaged at different wavelengths corresponding to the same incidence angle; r1 is smaller than or equal to 70%, phi 1 is a first angle threshold value, and phi 1 is larger than or equal to 60 degrees and smaller than or equal to 70 degrees; and has a second average reflectance R2, 1% < = R2lt, averaged at different wavelengths corresponding to the same incident angle for light irradiated from the outside toward the diffractive optical waveguide and having an incident angle theta in the range of 0 DEG < = theta < = phi2; phi 2 is a second angle threshold value and meets the condition that phi 2 is larger than or equal to 30 degrees and smaller than or equal to 45 degrees. The diffraction optical waveguide device not only can effectively restrain rainbow fringes, but also avoids influence on visual experience of human eyes in a normal field angle range to the environment as much as possible.

Description

Technical Field

[0001] The present invention relates to a display technology based on a diffractive optical waveguide; specifically, it relates to a diffractive optical waveguide device and a display device for augmented reality display. Background Art

[0002] The display technology based on a diffractive optical waveguide is one of the mainstream solutions for realizing augmented reality display at present. A diffractive optical device can be provided on a waveguide substrate as an optical coupling device. The diffractive optical device can adopt a waveguide grating. For example, the diffractive optical waveguide can include an input grating and an output grating. The input grating receives the input light carrying image information from an optical engine and couples it into the waveguide substrate; the output grating propagates and expands the light carrying image information while coupling the light out of the waveguide substrate to form an output light field. The eye receives the light of the output light field, so that the image carried by the incident light can be observed, for example. The waveguide grating can also include a turning grating, which expands the light from the input grating in one direction and deflects it to propagate towards the output grating.

[0003] Existing diffractive optical waveguides may produce a rainbow pattern effect under ambient light irradiation conditions. The formation mechanism of the rainbow pattern is as Figure 1 shown. When the external ambient light AL (such as the light from a spotlight in the overhead direction or the sun) irradiates the waveguide grating g on the diffractive optical waveguide W at a large incident angle, due to the diffraction of the grating on these ambient lights, diffracted lights of different wavelengths entering the human eye in different directions are formed (the diffracted lights entering the human eye E shown in the figure, represented by solid lines, dotted lines, and dashed lines respectively, have different wavelengths), so that rainbow-like multi-color energy bands are formed at certain angles. The human eye observes a colored dispersion pattern, which greatly affects the viewing experience of people.

[0004] Therefore, there is a need to provide a diffractive optical waveguide-based display technology that can suppress this rainbow pattern effect to improve the usage experience. Summary of the Invention

[0005] The object of the present invention is to provide a diffractive optical waveguide device for augmented reality display and an augmented reality display device including the diffractive optical waveguide device, which at least partially overcome the problems in the prior art.

[0006] According to one aspect of the present invention, there is provided a diffractive optical waveguide device for augmented reality display, including a diffractive optical waveguide and an optical film layer provided on the world side of the diffractive optical waveguide. The diffractive optical waveguide has a waveguide substrate and an input grating and an output grating provided on the waveguide substrate. The input grating and the output grating are used to couple the input light carrying image information into the waveguide substrate, expand its pupil, and couple it out of the waveguide substrate to realize image display, wherein

[0007] The optical film layer structure is such that in the visible light range:

[0008] For light irradiated from the outside towards the diffractive optical waveguide with an incident angle θ within the range of Φ 1 ≤ θ ≤ 85°, it has a first average reflectance R averaged over different wavelengths corresponding to the same incident angle 1 , where 30% < R 1 ≤ 70%, and Φ 1 is the first angle threshold, and 60° ≤ Φ 1 ≤ 70°; and

[0009] For light irradiated from the outside towards the diffractive optical waveguide with an incident angle θ within the range of 0° ≤ θ ≤ Φ 2 , it has a second average reflectance R averaged over different wavelengths corresponding to the same incident angle 2 , where 1% ≤ R 2 < 30%, and Φ 2 is the second angle threshold, and 30° ≤ Φ 2 ≤ 45°.

[0010] In some advantageous examples, the first average reflectance R 1 has a minimum value R 1min , the second average reflectance R 2 has a maximum value R 2max , and R 1min - R 2max ≥ 20%, preferably R 1min - R 2max ≥ 30%.

[0011] In some advantageous examples, the optical film layer is further structured such that for light with an incident angle θ within the range of Φ 2 < θ < Φ 1 , it has a third average reflectance R averaged over different wavelengths corresponding to the same incident angle 3 , and the third average reflectance R 3 gradually increases as the incident angle increases.

[0012] In some advantageous examples, 5% ≤ R 2 ≤ 25%.

[0013] In some advantageous examples, 10% ≤ R 2 ≤ 25%.

[0014] In some advantageous examples, the second angle threshold Φ 2 = 45°, and 5% ≤ R 2 ≤ 30%.

[0015] In some advantageous examples, the second angle threshold Φ 2 = 30°, and 10% ≤ R 2 ≤ 25%. In such examples, advantageously, the first angle threshold Φ 1 = 60°, and 40% ≤ R 1 ≤ 60%.

[0016] In some examples where the refractive index n of the waveguide substrate ≥ 1.9, advantageously, the first angle threshold Φ 1 = 60°.

[0017] In some advantageous examples, the output grating is disposed on the first surface of the waveguide substrate, and the optical film layer is disposed on the second surface of the waveguide substrate opposite to the first surface.

[0018] In some other advantageous examples, the diffractive optical waveguide device further includes a cover plate disposed on the world side of the diffractive optical waveguide, and the optical film layer is disposed on the cover plate. In such examples, advantageously, the cover plate can be movably mounted relative to the diffractive optical waveguide, so as to be able to switch between a protection position that shields directly in front of the diffractive optical waveguide and a retracted position that deviates from the protection position.

[0019] According to another aspect of the present invention, there is provided an augmented reality display device, which includes a lens, and the lens includes the diffractive optical waveguide device as described above.

[0020] Advantageously, the augmented reality display device is a near-eye display device and further includes a frame for holding the lens close to the eyes.

[0021] In the diffractive optical waveguide device according to an embodiment of the present invention, by providing an optical film layer on the world side of the diffractive optical waveguide and configuring the optical film layer to have a relatively high average reflectivity for visible light incident at a large angle and a relatively low average reflectivity for visible light incident at a small angle, it is possible to effectively suppress the rainbow pattern effect while minimizing the impact on the visual experience of the environment within the normal field of view of the human eye. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Other features, objects, and advantages of the present invention will become more apparent by reading the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0023] Figure 1 Schematic diagram of a waveguide grating of an existing diffractive optical waveguide forming rainbow patterns under ambient light irradiation;

[0024] Figure 2Schematic diagrams of different examples of a diffractive optical waveguide device for augmented reality display according to Embodiment 1 of the present invention;

[0025] Figure 3 Schematic diagrams of different examples of a diffractive optical waveguide device for augmented reality display according to Embodiment 2 of the present invention;

[0026] Figure 4 Reflectivity - incident angle curve graph of Design Example 1 of the optical film layer of the diffractive optical waveguide device according to the embodiment of the present invention;

[0027] Figure 5 Reflectivity - wavelength curve graph of Design Example 1 of the optical film layer of the diffractive optical waveguide device according to the embodiment of the present invention;

[0028] Figure 6 Reflectivity - incident angle curve graph of Design Example 2 of the optical film layer of the diffractive optical waveguide device according to the embodiment of the present invention;

[0029] Figure 7 Reflectivity - wavelength curve graph of Design Example 2 of the optical film layer of the diffractive optical waveguide device according to the embodiment of the present invention;

[0030] Figure 8 Reflectivity - incident angle curve graph of Design Example 3 of the optical film layer of the diffractive optical waveguide device according to the embodiment of the present invention;

[0031] Figure 9 Reflectivity - wavelength curve graph of Design Example 4 of the optical film layer of the diffractive optical waveguide device according to the embodiment of the present invention;

[0032] Figure 10 Schematic diagram of an example of an augmented reality display device according to the embodiment of the present invention. Detailed implementation manners

[0033] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the related invention, rather than limiting the invention. For the sake of description, only the parts related to the invention are shown in the drawings. It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0034] First, a diffractive optical waveguide device for augmented reality display according to the embodiment of the present invention will be introduced. Figure 2 Two examples of the diffractive optical waveguide device according to Embodiment 1 of the present invention are schematically shown, namely, diffractive optical waveguide devices 1 and 1'; Figure 3 Two examples of the diffractive optical waveguide device according to Embodiment 2 of the present invention are schematically shown, namely, diffractive optical waveguide devices 2 and 2'.

[0035] As Figure 2 and Figure 3 shown, each of the diffractive optical waveguide devices 1, 1', 2, 2' according to embodiments of the present invention includes a diffractive optical waveguide 10 and an optical film layer 20 disposed on the world side ws of the diffractive optical waveguide 10. The diffractive optical waveguide 10 has a waveguide substrate 11 and a coupling-in grating 12 and a coupling-out grating 13 disposed on the waveguide substrate 11. Figure 2 and Figure 3 The world side of the corresponding diffractive optical waveguide 10 is marked with the reference sign "ws", where the "world side" refers to the side of the diffractive optical waveguide opposite to the user's eyes during normal use. Although not shown in the figures, the coupling-out grating 13 of the diffractive optical waveguide 10 projects the coupling-out light toward a predetermined eyebox region, which is the position where the eyes are located during normal use. Therefore, the "world side" is also the side of the diffractive optical waveguide 10 opposite to the predetermined eyebox. By disposing the optical film layer 20 on the world side, ambient light (especially ambient light incident at a large angle) can be blocked from irradiating the grating, thereby suppressing the generation of rainbow patterns.

[0036] According to embodiments of the present invention, the optical film layer 20 is configured such that, within the visible light range:

[0037] For light irradiated from the outside toward the diffractive optical waveguide 10 with an incident angle θ in the range of Φ 1 ≤ θ ≤ 85°, it has a first average reflectance R averaged over different wavelengths corresponding to the same incident angle 1 , 30% < R 1 ≤ 70%, where Φ 1 is a first angle threshold, and 60° ≤ Φ 1 ≤ 70°; and

[0038] For light irradiated from the outside toward the diffractive optical waveguide 10 with an incident angle θ in the range of 0° ≤ θ ≤ Φ 2 , it has a second average reflectance R averaged over different wavelengths corresponding to the same incident angle 2 , 1% ≤ R 2 < 30%, where Φ 2 is a second angle threshold, and 30° ≤ Φ 2 ≤ 45°.

[0039] Since the rainbow pattern effect is particularly prominent in the case of large-angle incidence (especially when the incident angle is greater than 70°), the optical film layer 20 is configured to have a relatively high first average reflectance R for visible light incident at a large angle (Φ 1 ≤ θ ≤ 85°, where 60° ≤ Φ 1 ≤ 70°) 1It can effectively suppress the rainbow pattern effect. Considering that the amount of light received by the human eye through refraction for light incident at a very small angle close to 90° is already very small, there is no strict requirement for the optical film layer 20 to achieve a predetermined level of reflectivity for visible light within the angle range of 85° - 90°. This provides some flexibility for the design and manufacture of the optical film layer 20.

[0040] According to an embodiment of the present invention, the first average reflectivity R 1 is controlled within a range not exceeding 70%. This is because the fixation field of view of the human eye is approximately within the range of 40 degrees upward, 50 degrees downward, and 55 degrees to the left and right, and the human eye has a relatively low sensitivity to light outside the fixation field of view; when the first average reflectivity R 1 increases from 70% to a higher value, the difference in the rainbow pattern suppression effect that the human eye can perceive is very small. On the other hand, when the first average reflectivity R 1 increases from 70% to a higher value, it will significantly increase the design and processing difficulty of the optical film layer 20. Therefore, controlling the first average reflectivity R 1 within a range not exceeding 70% will help reduce the design and processing of the optical film layer 20 and is beneficial to cost reduction.

[0041] Meanwhile, the optical film layer 20 is configured to have a lower second average reflectivity R 2 for visible light incident at a small angle. The small angle range is selected as 0° ≤ θ ≤ Φ 2 , where 30° ≤ Φ 2 ≤ 45°. This is because the fixation field of view of the human eye is approximately within the range of 40 degrees upward, 50 degrees downward, and 55 degrees to the left and right, and the color-sensitive field of view of the human eye is approximately the half-angle range of the fixation field of view, that is, basically within the range of the incident angle θ ≤ 30°. In this way, on the one hand, reducing the reflectivity within the fixation field of view of the human eye (especially within the color-sensitive field of view of the human eye) can effectively avoid the diffraction optical waveguide device from affecting the human eye's visual experience of the environment. On the other hand, restricting the incident angle range that requires a lower reflectivity to within the fixation field of view of the human eye enables the optical film layer 20 to have an intermediate transition interval within the range of Φ 2 ≤ θ ≤ Φ 1 , and within this intermediate transition interval, the reflectivity can be flexibly configured, which is beneficial to improving the design flexibility of the optical film layer 20 and reducing the processing difficulty.

[0042] According to an embodiment of the present invention, the second average reflectivity R 2 is in the range of 1% ≤ R 2Within the range of < 30%, compared with the reflectance of traditional antireflection films, which is usually below 1%, the difficulty of designing and processing the corresponding optical film layer 20 is significantly reduced. This is considering that a major application scenario of augmented reality display is outdoor scenarios, such as driving or outdoor sports. In outdoor scenarios, rainbow stripe effects are likely to occur, and at the same time, the ambient brightness is usually high (e.g., higher than the image display brightness of the display screen). Therefore, moderately weakening the ambient light incident at a small angle has little impact on enhancing the visual experience.

[0043] In some advantageous implementations, the second average reflectance R 2 can be in the range of 5% ≤ R 2 ≤ 25%. In some other advantageous implementations, the second average reflectance R 2 can be in the range of 10% ≤ R 2 ≤ 25%. In these examples, by increasing the lower limit value of the second average reflectance R 2 to help suppress the fluctuation of reflectance with wavelength and avoid color cast caused by such reflectance fluctuations, and at the same time, by reducing the upper limit value of the second average reflectance R 2 to avoid overly weakening the ambient light intensity within the fixation field of view.

[0044] In some advantageous implementations, the second angle threshold Φ 2 = 45°, and 5% ≤ R 2 ≤ 30%.

[0045] In some advantageous implementations, the optical film layer 20 is configured to satisfy: the second angle threshold Φ 2 = 30°, and 10% ≤ R 2 ≤ 25%. In such an implementation, the optical film layer 20 can be further configured to satisfy: the first angle threshold Φ 1 = 60°, and 40% ≤ R 1 ≤ 60%.

[0046] Currently, in order to make, for example, diffractive optical waveguides thinner and / or increase the field of view, there is a technological trend to choose to use waveguide substrates with a high refractive index. However, as the refractive index increases, rainbow stripes also start to occur when ambient light enters the diffractive optical waveguide at a smaller incident angle. Considering such a situation of applying a waveguide substrate with a high refractive index, it is preferable to use a smaller first angle threshold. For example, in an implementation where the refractive index n of the waveguide substrate 11 ≥ 1.9, advantageously, the first angle threshold Φ 1 = 60°.

[0047] Preferably, the first average reflectance R 1 has a minimum value R 1min , and the second average reflectance R 2 has a maximum value R2max , and R 1min -R 2max ≥20%, preferably R 1min -R 2max ≥30%. This is conducive to the optical film layer 20 achieving a more significant effect in suppressing rainbow patterns and providing a good visual experience.

[0048] Preferably, the optical film layer 20 can be further configured as follows: for an incident angle θ in Φ 2 <θ<Φ 1 The light in the range has a third average reflectivity R averaged over different wavelengths corresponding to the same incident angle. 3 , the third average reflectivity R 3 The optical film layer 20 gradually increases with the increase of the incident angle, which is beneficial to improving the design flexibility of the optical film layer 20 and reducing the difficulty of processing.

[0049] The above describes the configuration of the reflective characteristics of the optical film layer in the diffractive optical waveguide device according to the embodiment of the present invention. The following describes other features of the diffractive optical waveguide device.

[0050] The coupling-in grating 12 and the coupling-out grating 13 are used to couple input light carrying image information into the waveguide substrate 11 and expand the pupil thereof, and couple it out of the waveguide substrate 11 to realize image display.

[0051] Specifically, the coupling-in grating 12 is used to couple input light with image information, such as optical machine projection, into the waveguide substrate 11 through a specific order of diffraction, and propagate it toward the coupling-out grating 13 through total reflection in the waveguide substrate 11.

[0052] The outcoupling grating 13 expands the light propagating therein by total reflection in at least one direction and gradually couples it out from the waveguide substrate 11 during the pupil expansion process to form an outcoupling light field on the observation side (not shown, the side opposite to the world side ws) of the diffraction light waveguide 10, in which the human eye can observe an image.

[0053] In some implementations, the outcoupling grating 13 may be a one-dimensional grating, which can expand the pupil of the light propagating therein in one direction; in this case, the diffractive optical waveguide 10 may also include a turning grating (not shown) for changing the total reflection propagation direction of the light from the incoupling grating 12 and expanding the pupil in another direction different from the outcoupling grating 13. Although only the incoupling grating 12 and the outcoupling grating 13 are shown in the figure, it should be understood that the diffractive optical waveguide device according to the embodiment of the present invention is not limited thereto; according to different applications, the diffractive optical waveguide 10 may also include a turning grating or other optical elements.

[0054] In some other implementations, the out-coupling grating 13 can be a two-dimensional grating, which can expand the pupil of light in two intersecting directions and simultaneously couple out light. The diffractive optical waveguide device according to an embodiment of the present invention is particularly advantageous in such an implementation. This is because the diffractive optical waveguide architecture / configuration based on a two-dimensional out-coupling grating is not as flexible as that based on a one-dimensional out-coupling grating, and it is difficult to weaken the rainbow pattern by adjusting, for example, the direction or magnitude of the grating vector of the out-coupling grating; while weakening the rainbow pattern by adding an optical film layer is not restricted by the above.

[0055] Figure 2 and Figure 3 Fig. shows an example of the arrangement of the optical film layer 20 in the diffractive optical waveguide device according to an embodiment of the present invention.

[0056] As Figure 2 shown, in the diffractive optical waveguide devices 1, 1' according to Embodiment 1 of the present invention, the out-coupling grating 13 is provided on the first surface 11a of the waveguide substrate 11, and the optical film layer 20 is provided on the second surface 11b of the waveguide substrate 11 opposite to the first surface 11a.

[0057] In Figure 2 the diffractive optical waveguide device 1 shown in FIG. (a), both the in-coupling grating 12 and the out-coupling grating 13 are provided on the first surface 11a; in this case, preferably, the optical film layer 20 can cover the area of the waveguide substrate 11 where the in-coupling grating 12 and the out-coupling grating 13 are provided, and even can cover the entire second surface 11b.

[0058] In Figure 2 the diffractive optical waveguide device 1' shown in FIG. (b), the in-coupling grating 12 is provided on the second surface 11b opposite to the surface where the out-coupling grating 13 is located; at this time, the optical film layer 20 may not cover the second surface 11b of the area where the in-coupling grating 12 is located. Since generally the area of the in-coupling grating is much smaller than that of the out-coupling grating, and in some cases, the world side of the in-coupling grating will be shielded to block any ambient light from irradiating on the in-coupling grating, the optical film layer arrangement shown in FIG. (b) is advantageous.

[0059] As Figure 3 shown, the diffractive optical waveguide devices 2, 2' according to Embodiment 2 of the present invention further include a cover plate 30 provided on the world side ws of the diffractive optical waveguide 10, and the optical film layer 20 is provided on the cover plate 30. The cover plate 30 can not only be a carrier of the optical film layer 20, but also protect the diffractive optical waveguide 10 from pollution or damage in the environment.

[0060] The optical film layer 20 can be provided on the side of the cover plate 30 opposite to the diffractive optical waveguide 10, as Figure 3as shown in Figure (a); alternatively, the optical film layer 20 may also be disposed on the side of the cover plate 30 facing the diffractive optical waveguide 10, such as Figure 3 Figure (b). The latter is beneficial to protecting the optical film layer 20.

[0061] In the example as Figure 3 shown, the cover plate 30 may be movably mounted relative to the diffractive optical waveguide 10, so as to be able to switch between a protection position (for example, used in an outdoor strong light environment) that blocks the front of the diffractive optical waveguide 10 and a retracted position (for example, used in an environment with soft ambient light or an environment where the ambient light irradiates only within a small field of view).

[0062] The following combines Figures 4 - 9 to introduce several design examples of the optical film layer of the diffractive optical waveguide device according to the embodiments of the present invention. These design examples are exemplary rather than restrictive. In the design examples, a wide spectral range of wavelengths 440nm - 650nm is considered; and for the convenience of observation and discussion, the first angle threshold Φ 1 = 60°, and the second angle threshold Φ 2 = 30°.

[0063] (Design Example 1)

[0064] In Design Example 1, with R 2 ≤ 5% as a constraint and R 1 as high as possible as an optimization goal, the optical film layer (hereinafter referred to as "optical film layer 20A") obtained through optimization design includes 41 film layers, which are film layers with different materials for each layer and different reflectivities at specific wavelength bands. The thickness of the optical film layer 20A reaches 40 - 50 microns.

[0065] Figure 4 is the reflectivity - incident angle curve graph of the optical film layer 20A, Figure 5 is the reflectivity - wavelength curve graph of the optical film layer 20A, which respectively shows the changes in the reflectivity of the optical film layer 20A with the incident angle and wavelength.

[0066] From Figure 4 the shown reflectivity - incident angle curve, the optical film layer 20A achieves high transmittance in the range of 0° ≤ θ ≤ 30° (the corresponding second average reflectivity R 2 is suppressed below 5%), and achieves high reflectivity in the range of 70° ≤ θ ≤ 85° (the first average reflectivity R 1 is above 45%, and the overall reflectivity is close to 60%). Although the reflectivity R 2Only about 30%, but since it is not easy to appear rainbow patterns at this incident angle (the large angles of 70 - 85° are the areas where rainbow patterns are severe), the optical film layer 20A can effectively suppress rainbow patterns.

[0067] From Figure 5 the shown reflectivity - wavelength curve, the reflectivity of the optical film layer 20A fluctuates greatly with the wavelength, especially in the green light wavelength range and the curves corresponding to the incident angles of 70° and 80°. This indicates that reducing the reflectivity to a very low state will cause large variations in reflectivity with the wavelength, especially sharp oscillations in the reflectivity in the short - wavelength range and at large incident angles. This will result in a small processing tolerance for the optical film layer, thus causing problems such as difficult processing and high costs. Moreover, due to the above - mentioned oscillations of the reflectivity with the wavelength, there may be a situation where the reflectivities corresponding to different incident angles differ greatly within a local wavelength range, which will cause a certain degree of color cast.

[0068] (Design Example 2)

[0069] In Design Example 2, with the constraint that the number of film layers does not exceed 10 and R 2 ≤25%, and with the optimization goal of making R 1 as high as possible, the optical film layer (hereinafter referred to as "optical film layer 20B") obtained through optimization design includes 9 film layers.

[0070] It can be seen that, compared with Design Example 1, in Design Example 2, by restricting the number of film layers and relaxing R 2 from strictly below 5% to below 25%, the design and processing complexity of the optical film layer are reduced. This can make the design and processing of the entire film system much easier. Since the transmittance requirements for the world end in outdoor scenes are not extremely stringent, it is also acceptable to relax the small - angle transmittance R 2 to below 25%.

[0071] Figure 6 is the reflectivity - incident angle curve graph of the optical film layer 20B, Figure 7 is the reflectivity - wavelength curve graph of the optical film layer 20B, which respectively shows the variations of the reflectivity of the optical film layer 20B with the incident angle and the wavelength.

[0072] From Figure 6 the shown reflectivity - incident angle curve, the second average reflectivity R 2 of the optical film layer 20B in the range of 0° ≤ θ ≤ 30° is approximately around 20%, and the first average reflectivity R 1 in the range of 60° ≤ θ ≤ 85° is around 40% to 65%.

[0073] From Figure 7From the shown reflectivity-wavelength curve, the reflectivity of the optical film layer 20B changes little with the wavelength, and the overall curve is relatively smooth. This means that the optical film layer 20B has a large processing tolerance, is easy to process, and will not cause color cast when observing the environment.

[0074] (Design Example 3)

[0075] In Design Example 3, with the constraint that the number of film layers does not exceed 15 and R 2 ≤25%, and with the optimization goal of making R 1 as high as possible, the optical film layer (hereinafter referred to as "optical film layer 20C") obtained through optimization design includes 14 film layers.

[0076] Design Example 3 relaxes the constraint on the number of film layers compared to Design Example 2, enabling further improvement of the reflectivity within a large angular range, thereby enhancing the ability to suppress rainbow patterns.

[0077] Figure 8 is the reflectivity-incident angle curve graph of the optical film layer 20C, Figure 9 is the reflectivity-wavelength curve graph of the optical film layer 20C, which respectively shows the variations of the reflectivity of the optical film layer 20C with the incident angle and the wavelength.

[0078] From Figure 8 the shown reflectivity-incident angle curve, the second average reflectivity R of the optical film layer 20C within the range of 0° ≤ θ ≤ 30° 2 is approximately around 20%, and the first average reflectivity R within the range of 60° ≤ θ ≤ 85° 1 is around 50% to 70%.

[0079] From Figure 9 the shown reflectivity-wavelength curve, although the variation amplitude of the reflectivity of the optical film layer 20C with the wavelength has increased compared to the optical film layer 20B, the oscillation / variation frequency is much milder compared to the optical film layer 20A. This indicates that the processing tolerance of the optical film layer 20C has been improved compared to the optical film layer 20A, and it is beneficial to suppressing the color cast phenomenon.

[0080] The above introduced the diffractive optical waveguide device according to the embodiments of the present invention. According to the embodiments of the present invention, there is also provided an augmented reality display device, which includes a diffractive optical waveguide according to the embodiments of the present invention. The augmented reality display device may include a lens, and the lens includes the diffractive optical waveguide introduced above. The augmented reality display device is preferably a near-eye display device, and further includes a frame for holding the lens close to the eyes.

[0081] Figure 10An example of an augmented reality display device according to an embodiment of the present invention is shown, wherein the augmented reality display device 100 includes a lens 110 and a frame 120. The lens 110 includes a fixed lens 111 and a movable cover plate 112. The fixed lens 111 includes a diffraction optical waveguide 10 in a diffraction optical waveguide device according to Embodiment II of the present invention. The movable cover plate 112 includes a cover plate 30 in the diffraction optical waveguide device and an optical film layer 20 disposed on the cover plate.

[0082] Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solutions formed by the specific combination of the above technical features, and should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the technical solutions formed by mutually replacing the above features with the technical features (but not limited to) having similar functions disclosed in the present application.

Claims

1. A diffractive optical waveguide device for augmented reality display, comprising a diffractive optical waveguide and an optical film layer arranged on the world side of the diffractive optical waveguide, wherein the diffractive optical waveguide has a waveguide substrate and an in-coupling grating and an out-coupling grating arranged on the waveguide substrate, wherein the in-coupling grating and the out-coupling grating are used to couple input light carrying image information into the waveguide substrate and perform pupil expansion on the input light and out-couple the input light out of the waveguide substrate to realize image display, wherein The optical film layer is structured as follows: For light irradiated from the outside toward the diffractive optical waveguide with an incident angle θ in the range of Φ1 ≤ θ ≤ 85 o °, it has a first average reflectance R1 averaged over different wavelengths corresponding to the same incident angle, where 30% < R1 ≤ 70%, Φ1 is a first angle threshold, and 60 o ≤ Φ1 ≤ 70 o ; and For the diffraction light waveguide irradiated from the outside with an incident angle θ of 0 o ≤θ≤Φ2, has a second average reflectivity R2 averaged over different wavelengths corresponding to the same incident angle, 1%≤R2<30%, where Φ2 is the second angle threshold, and satisfies 30 o ≤Φ2≤45 o .

2. The diffractive optical waveguide device according to claim 1, wherein: The first average reflectivity R1 has a minimum value R 1min , the second average reflectivity R2 has a maximum value R 2max , and R 1min -R 2max ≥20%, preferably R 1min -R 2max ≥30%.

3. The diffractive optical waveguide device according to claim 1 or 2, wherein: The optical film layer is further constructed to have a third average reflectivity R3 averaged over different wavelengths corresponding to the same incident angle for light with an incident angle θ in the range of Φ2<θ<Φ1, and the third average reflectivity R3 gradually increases as the incident angle increases.

4. The diffractive optical waveguide device according to claim 1, wherein: 5％≤R2≤25％。 5. The diffractive optical waveguide device according to claim 1, wherein: 10％≤R2≤25％。 6. The diffractive optical waveguide device according to any one of claims 1 to 3, wherein: The second angle threshold Φ2=45 o , and 5%≤R2≤30%.

7. The diffractive optical waveguide device according to any one of claims 1 to 3, wherein: The second angle threshold Φ2=30 o , and 10%≤R2≤25%.

8. The diffractive optical waveguide device according to claim 7, wherein: The first angle threshold Φ1=60 o , and 40%≤R1≤60%.

9. The diffractive optical waveguide device according to any one of claims 1 to 5, wherein: The refractive index n of the waveguide substrate is ≥1.9, and the first angle threshold Φ1 = 60 degrees.

10. The diffraction optical waveguide device according to claim 1, wherein the outcoupling grating is disposed on a first surface of the waveguide substrate, and the optical film layer is disposed on a second surface of the waveguide substrate opposite to the first surface.

11. The diffractive optical waveguide device according to claim 1, further comprising a cover plate disposed on the world side of the diffractive optical waveguide, and the optical film layer is disposed on the cover plate.

12. The diffractive optical waveguide device according to claim 11, wherein: The cover plate is movably mounted relative to the diffractive optical waveguide, so that it can be switched between a protection position shielding the front of the diffractive optical waveguide and a retreat position deviating from the protection position.

13. The diffractive optical waveguide device according to any one of claims 1 to 12, wherein: The outcoupling grating is a two-dimensional grating.

14. An augmented reality display device, comprising a lens, wherein the lens comprises the diffractive optical waveguide device according to any one of claims 1 to 13.

15. The augmented reality display device according to claim 14, wherein: The augmented reality display device is a near-eye display device and also includes a frame for holding the lens close to the eye.

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