Volume holographic optical waveguide and augmented reality equipment
By setting multiple support columns in the non-grating region of the bulk holographic optical waveguide to control their density and distribution, the problems of poor flatness, large haze and low contrast in the prior art have been solved, and better results have been achieved display effect.
Patent Information
- Application Number
- CN202421386589.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-17
- Publication Date
- 2025-02-18
- Estimated Expiration
- 2034-06-17
AI Technical Summary
The existing holographic optical waveguides have problems such as poor flatness, large haze and low contrast, which affects their display effect.
By providing a plurality of support columns in the non-grating region between the two waveguide substrates, the density and distribution of the support columns are controlled, instead of the bulk holographic waveguide substrate structure of the glass beads.
The haze of the device is reduced, the contrast of the bulk holographic diffraction optical waveguide device is improved, and the display effect is improved.
Smart Images
Figure CN222506599U_ABST
Abstract
Description
Technical Field
[0001] The embodiments of the present application relate to the field of electronic technology, and in particular to a volume holographic optical waveguide and an augmented reality device. Background Art
[0002] At present, augmented reality (AR) technology can combine virtuality and reality, and has been increasingly widely used. Volume holographic optical waveguides are essential components of augmented reality devices. The packaging technology used by volume holographic waveguides is based on spraying glass beads on a glass sheet, filling it with materials, and finally sealing it with cover glass to complete the semi-finished product of the waveguide.
[0003] However, compared with surface relief waveguides, this type of volume holographic waveguide has problems such as poor flatness, high haze, and low contrast, which affect the display and application of volume holographic waveguide sheets. Utility Model Content
[0004] The present application provides a volume holographic optical waveguide, which can control the density and distribution of support columns on the waveguide substrate, reduce the haze of the device, improve the contrast of the final volume holographic diffraction waveguide device, and improve the display effect.
[0005] In a first aspect, the present application provides a volume holographic optical waveguide comprising:
[0006] Two waveguide substrates, the two waveguide substrates are arranged opposite to each other;
[0007] A plurality of supporting pillars, the volume holographic optical waveguide further comprises a grating region and a non-grating region; the plurality of supporting pillars are located between the two waveguide substrates in the non-grating region and are in contact with the two waveguide substrates respectively.
[0008] Optionally, the plurality of support columns are evenly distributed or unevenly distributed.
[0009] Optionally, the support column includes a first support column and a second support column;
[0010] The second support column at least partially surrounds the grating region; the first support column is located on a side of the second support column away from the grating region.
[0011] Optionally, an orthographic projection area of the first support column on the waveguide substrate is smaller than an orthographic projection area of the second support column on the waveguide substrate.
[0012] Optionally, the cross-sectional shape of the support column is any one of rectangular, circular and polygonal.
[0013] Optionally, a ratio of a contact area between one end of the support column and the waveguide substrate to an orthographic projection area of the support column on the waveguide substrate is greater than or equal to 20%.
[0014] Optionally, the haze of the volume holographic optical waveguide is less than 0.8, and the supporting force of the supporting column is greater than 0.3N / cm 2 The unit density of the support column ranges from 0.78% to 2%.
[0015] Optionally, the refractive index of the support column is greater than the refractive index of the two waveguide substrates.
[0016] Optionally, the difference between the refractive index of the support column and the refractive index of the two waveguide substrates is less than or equal to 0.02.
[0017] Based on the same inventive concept, an embodiment of the present application further provides an augmented reality device, including the volume holographic optical waveguide provided in the first aspect, and further including:
[0018] Image source; the grating region comprises an in-coupling grating and an out-coupling grating, and the light emitted by the image source is coupled into the waveguide substrate through the in-coupling grating and then coupled out through the out-coupling grating.
[0019] In summary, the volume holographic optical waveguide provided in the embodiment of the present application, by setting a plurality of support columns in the non-grating area between the two waveguide substrates and using support columns instead of the volume holographic waveguide substrate structure of glass beads, can control the density and distribution of the support columns on the waveguide substrate, reduce the haze of the device, improve the contrast of the final volume holographic diffraction optical waveguide device, and ultimately improve the display effect. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 It is a schematic diagram of a volume holographic optical waveguide provided by the prior art;
[0021] Figure 2 is a schematic diagram of a volume holographic optical waveguide provided in an embodiment of the present application;
[0022] Figure 3 yes Figure 2 Schematic diagram of the cross section of three types of volume holographic optical waveguides along the AA direction;
[0023] Figure 4 is a schematic diagram of another volume holographic optical waveguide provided in an embodiment of the present application;
[0024] Figure 5 This is a schematic diagram of another volume holographic optical waveguide provided in an embodiment of the present application. DETAILED DESCRIPTION
[0025] The present application will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present application, rather than to limit the present application. It should also be noted that, for ease of description, only the parts related to the present application, rather than all structures, are shown in the accompanying drawings.
[0026] Figure 1 Schematic diagram of a volume holographic optical waveguide provided by the prior art. Figure 1 As shown, Figure 1 The volume holographic optical waveguide structure 12 formed based on glass microbeads 11 commonly used in the prior art is adopted. The glass microbeads 11 are commonly manufactured by spraying, so they are irregularly distributed on the waveguide substrate of the volume holographic optical waveguide structure 12. Since it is difficult to control the uniformity of the glass microbeads 11 on the waveguide substrate, the controllability is poor. When the material thickness increases, the volume of the glass microbeads 11 also increases, and the contrast problem of the volume holographic optical waveguide device is difficult to solve.
[0027] Based on this, the present application proposes a volume holographic optical waveguide in view of one or more of the above-mentioned problems existing in the prior art. Figure 2 is a schematic diagram of a volume holographic optical waveguide provided in an embodiment of the present application;
[0028] Figure 3 yes Figure 2 Schematic diagram of the cross section of three types of volume holographic waveguides along the AA direction. Figure 2 and Figure 3 As shown, a volume holographic optical waveguide provided in an embodiment of the present application includes two waveguide substrates 10 and a plurality of support pillars 20, and the two waveguide substrates 10 are arranged opposite to each other; the volume holographic optical waveguide also includes a grating area G10 and a non-grating area G20, and the plurality of support pillars 20 are located between the two waveguide substrates 10 in the non-grating area G20, and are in contact with the two waveguide substrates 10 respectively.
[0029] Specific, combined Figure 2 and Figure 3 The material of the two waveguide substrates 10 can be glass with a high refractive index. The two waveguide substrates 10 are arranged opposite to each other. The grating structure is arranged in the grating area G10, and there is no grating structure in the non-grating area G20. The grating area G10 is exposed to form a volume holographic grating. The grating structure can be a reflective grating and / or a transmissive grating, which is not limited in the embodiment of the present application.
[0030] A plurality of support columns 20 are arranged between the two waveguide substrates 10 corresponding to the non-grating region G20. The two end faces of the support columns 20 are in contact with the waveguide substrate 10 respectively, so as to support the non-grating region G20 and the entire volume holographic optical waveguide.
[0031] The manufacturing process of the support column 20 may be photolithography or chemical etching in etching, or may be a process such as embossing, etc., which is not limited in the embodiment of the present application. As an example, Figure 2 and Figure 3 As shown in Figure (a), the manufacturing process steps are as follows:
[0032] Step S1: etching or imprinting the support pillars 20 on the surface of the bottom waveguide substrate 10.
[0033] Step S2, using a dispensing process to dispense glue on the outer contour of the bottom waveguide substrate 10, then using a vacuum suction head to absorb the upper waveguide substrate 10 and press it on the bottom waveguide substrate 10, and the two waveguide substrates 10 are bonded together to form the initial structure of the volume holographic optical waveguide.
[0034] Specifically, Figure 2 and Figure 3 As shown in Figure (a), the support column 20 is a uniformly distributed cylinder, and the upper and lower surfaces are circular with a diameter of 4um. The uniform upper and lower design has good support force, the material after bonding has good flatness, and the final volume holographic optical waveguide device has a small haze.
[0035] Furthermore, the distribution of the support pillars 20 on the waveguide substrate 10 can be arbitrarily designed. In one feasible implementation, the plurality of support pillars 20 are evenly distributed; in another feasible implementation, the plurality of support pillars 20 are non-evenly distributed.
[0036] Among them, the unit density of the support column 20 is defined as the area ratio of the support column 20 per unit area. The greater the density of the support column 20, the greater the haze of the obtained volume holographic grating; the smaller the density of the support column 20, the smaller the supporting force on the upper waveguide substrate 10, resulting in poor material flatness between the two waveguide substrates 10, and finally the obtained volume holographic grating has poor diffraction efficiency uniformity.
[0037] It can be seen that it is necessary to maintain a balance between the unit density of the support column 20, the haze of the volume holographic waveguide, and the supporting force performance of the support column 20. Optionally, the haze of the volume holographic waveguide is set to be less than 0.8, and the supporting force of the support column 20 is set to be greater than 0.3N / cm 2 The unit density of the support column 20 is in the range of 0.78% to 2%. Such an arrangement can make the haze of the holographic optical waveguide smaller and the supporting force larger, and finally the diffraction efficiency uniformity of the volume holographic grating obtained is better.
[0038] Furthermore, the material of the support column 20 also needs to be reasonably designed, and the refractive index of the support column 20 is set to be greater than the refractive index of the two waveguide substrates 10, and the difference between the refractive index of the support column 20 and the refractive index of the two waveguide substrates 10 is less than or equal to 0.02.
[0039] In this way, the material's own transmittance and haze performance are both good. The better the material's own performance, the lower the haze of the volume holographic grating. Exemplarily, the transmittance of the support column 20 is greater than 90%, and the haze of the volume holographic grating is less than 0.5, wherein the material of the support column 20 can be resin.
[0040] Furthermore, the shape of the support column 20 can also be arbitrarily designed. Optionally, the cross-sectional shape of the support column 20 is any one of a rectangle, a circle and a polygon.
[0041] in, Figure 2 In the figure, only the orthographic projection shape of the support column 20 on the waveguide substrate 10 is a circle as an example, and more embodiments are not shown here one by one.
[0042] For example, Figure 3 As shown in Figure (a), the support column 20 may be cylindrical; Figure 3 As shown in Figure (b), the support column 20 may be trapezoidal; Figure 3 As shown in Figure (c), the support column 20 can be a barrel-shaped column with small cross-sections at both ends and a large cross-section in the middle, and its cross-section can be circular or hexagonal. The haze of the volume holographic waveguide can be further reduced by designing the contact area of the support column 20. It can be seen that the contact area between the support column 20 and the glass is larger than the contact area between the glass beads and the glass, the support performance of the support column 20 is better, and the density of the support column 20 is controllable, which will not affect the exposure result of the material.
[0043] In the prior art, when glass beads are used, there is a problem that when the size of some of the glass beads is smaller than the required size, they will slide inside the two glass pieces. However, the support pillars 20 used in this application are made on the non-grating area G20, and the position of each support pillar 20 is fixed and will not move at will. Therefore, the subsequent device exposure process will be more stable.
[0044] Furthermore, setting the ratio of the contact area between one end of the support column 20 and the waveguide substrate 10 to its orthographic projection area on the waveguide substrate 10 to be greater than or equal to 20% is beneficial to improving the firmness of the support column 20 and the waveguide substrate 10 .
[0045] Figure 4 It is a schematic diagram of another volume holographic optical waveguide provided in an embodiment of the present application.
[0046] Based on the above embodiments, Figure 4 As shown, the support column 20 includes a first support column 21 and a second support column 22 ; the second support column 22 at least partially surrounds the grating region G10 ; the first support column 21 is located on a side of the second support column 22 away from the grating region G10 .
[0047] Specifically, Figure 4 As shown, the support column 20 is only arranged in the non-grating area G20, the first support column 21 is in the shape of a cylinder, and the upper and lower surfaces are circular with a diameter of 4um; the second support column 22 is in the shape of a rectangular parallelepiped, at least partially surrounding the grating area G10, and is in the form of a wall outside the grating area G10. Figure 2 The absence of the second support pillars 22 around the middle grating region G10 can ensure a better supporting force and the flatness of the material in the grating region G10.
[0048] There is a certain gap between adjacent second support columns 22, which can ensure that the material of the grating area G10 and the non-grating area G20 can flow and ensure the thickness of the material. By arranging the second support column 20 on the periphery of the grating area G10, the haze of the device is reduced, so that the grating area G10 will not produce serious light scattering when diffracting and propagating image light, which greatly improves the contrast of the volume holographic optical waveguide.
[0049] Optional, continue to refer to Figure 4 As shown, the orthographic projection area of the first support column 21 on the waveguide substrate 10 is smaller than the orthographic projection area of the second support column 22 on the waveguide substrate 10 .
[0050] Specifically, Figure 4 As shown, the differentiated design of the first support column 21 and the second support column 22 can reduce the orthographic projection area of the first support column 21 on the waveguide substrate 10, and densely arrange multiple first support columns 21 in the non-grating G20, which is beneficial to reducing the haze of the device and improving the supporting performance; the orthographic projection area of the second support column 22 on the waveguide substrate 10 can be increased, and the number of second support columns 22 can be reduced, and the outer side of the grating area G10 is supported by a wall to ensure the stability of the volume holographic grating structure of the grating area G10.
[0051] Based on the same inventive concept, an embodiment of the present application also provides an augmented reality device, including any one of the volume holographic optical waveguides provided in the above embodiments, and the augmented reality device also includes: an image source (not shown in the figure); the grating area G10 includes a coupling-in grating G11 and an output grating G12, and the light emitted by the image source is coupled into the waveguide substrate 10 through the coupling-in grating G11 and then coupled out through the output grating G12.
[0052] The coupling-in grating of the coupling-in grating G11 can be a straight grating, a tilted grating, a blazed grating, etc., and the coupling-out grating of the coupling-out grating G12 can be a straight grating, a tilted grating, a blazed grating, a two-dimensional grating, etc.
[0053] Taking the out-coupling grating G12 as a two-dimensional grating as an example, the coupling-in grating of the coupling-in grating G11 couples the light emitted by the image source into the fully transmitted out-coupling grating G12 in the volume holographic optical waveguide. The out-coupling grating G12 can both diffract the light and couple the light out to the user's observation area to achieve AR display.
[0054] Figure 5 This is a schematic diagram of another volume holographic optical waveguide provided in an embodiment of the present application.
[0055] In other embodiments, Figure 5 As shown, the grating region G10 may further include at least one turning region G13, the turning region G13 is located on the propagation path of the diffracted light coupled into the grating G11, and the out-coupled grating G12 is located on the propagation path of the diffracted light of the turning region G13.
[0056] Specifically, the coupling grating in the coupling grating G11, the turning grating in the turning area G13, and the coupling grating in the coupling grating G12 can all be reflective gratings, or all be transmissive gratings, or a combination of reflective gratings and transmissive gratings, which are not specifically shown here. The coupling grating of the coupling grating G11 couples the light emitted by the image source into the volume holographic optical waveguide for total reflection and transmits it to the turning area G13, and after diffraction and pupil expansion in the turning area G13, it is transmitted to the coupling grating G12, and the coupling grating G12 diffracts the light and couples it out to the user observation area to achieve AR display.
[0057] In summary, compared with the prior art, the augmented reality device provided by the embodiment of the present application has the advantages of good flatness, no haze, high contrast, and better display effect.
[0058] Note that the above are only preferred embodiments of the present application and the technical principles used. Those skilled in the art will understand that the present application is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, combinations and substitutions can be made by those skilled in the art without departing from the scope of protection of the present application. Therefore, although the present application is described in more detail through the above embodiments, the present application is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present application, and the scope of the present application is determined by the scope of the appended claims.
Claims
1. A volume holographic optical waveguide, characterized in that: include: Two waveguide substrates, the two waveguide substrates are arranged opposite to each other; A plurality of supporting pillars, the volume holographic optical waveguide further comprises a grating region and a non-grating region; the plurality of supporting pillars are located between the two waveguide substrates in the non-grating region and are in contact with the two waveguide substrates respectively.
2. The volume holographic optical waveguide according to claim 1, characterized in that: The plurality of support columns are evenly distributed or unevenly distributed.
3. The volume holographic optical waveguide according to claim 1, characterized in that: The support column comprises a first support column and a second support column; The second support column at least partially surrounds the grating region; the first support column is located on a side of the second support column away from the grating region.
4. The volume holographic optical waveguide according to claim 3, characterized in that: An orthographic projection area of the first supporting column on the waveguide substrate is smaller than an orthographic projection area of the second supporting column on the waveguide substrate.
5. The volume holographic optical waveguide according to claim 1, characterized in that: The cross-sectional shape of the support column is any one of a rectangular, circular and polygonal shape.
6. The volume holographic optical waveguide according to claim 5, characterized in that: The ratio of the contact area between one end of the support column and the waveguide substrate to the orthographic projection area of the support column on the waveguide substrate is greater than or equal to 20%.
7. The volume holographic optical waveguide according to claim 1, characterized in that: The haze of the volume holographic optical waveguide is less than 0.8, and the supporting force of the supporting column is greater than 0.3N / cm 2 The unit density of the support column ranges from 0.78% to 2%.
8. The volume holographic optical waveguide according to claim 1, characterized in that: The refractive index of the support column is greater than the refractive index of the two waveguide substrates.
9. The volume holographic optical waveguide according to claim 8, characterized in that: The difference between the refractive index of the support column and the refractive index of the two waveguide substrates is less than or equal to 0.
02.
10. An augmented reality device, comprising the volume holographic optical waveguide according to any one of claims 1 to 9, characterized in that: Also includes: Image source; the grating region comprises an in-coupling grating and an out-coupling grating, and the light emitted by the image source is coupled into the waveguide substrate through the in-coupling grating and then coupled out through the out-coupling grating.