CN118033808A - Light guide device and wearable equipment - Google Patents
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- CN118033808A CN118033808A CN202211362772.0A CN202211362772A CN118033808A CN 118033808 A CN118033808 A CN 118033808A CN 202211362772 A CN202211362772 A CN 202211362772A CN 118033808 A CN118033808 A CN 118033808A
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/01—Head-up displays
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/09—Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/18—Diffraction gratings
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/02—Optical fibres with cladding with or without a coating
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/02—Optical fibres with cladding with or without a coating
- G02B6/028—Optical fibres with cladding with or without a coating with core or cladding having graded refractive index
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
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Abstract
The embodiment of the application discloses a light guide device and wearable equipment; the light guide device comprises a waveguide substrate, and a coupling-in area and a coupling-out area which are arranged on the waveguide substrate; wherein the waveguide substrate comprises at least two different refractive indices; the coupling-in region is used for coupling incident light into the waveguide substrate; the waveguide substrate is used for transmitting the incident light to the coupling-out region in a total reflection way, and different light beams in the incident light can have the same or similar light transmission path length after being subjected to reflection modulation of different refractive indexes in the waveguide substrate; the coupling-out region is used for coupling out the light beam transmitted to the coupling-out region. According to the light guide device provided by the embodiment of the application, the path length of the partial light beam propagating through the primary total reflection in the waveguide substrate can be corrected by designing the waveguide substrate with the refractive index being changed, so that the rainbow effect in the coupling-out area and the light leakage (Backcoupling) in the coupling-in area are avoided, and the light efficiency can be improved.
Description
Technical Field
The application relates to the technical field of near-eye display, in particular to a light guide device and wearable equipment.
Background
Diffractive optical waveguides are the core of Augmented Reality (AR) devices. For the existing diffractive optical waveguide solution, a waveguide substrate design solution with a single refractive index is generally adopted, and in practical application, the solution has more defects such as rainbow effect of the coupling-out area and light effect reduction caused by Backcoupling of the coupling-in area, which affect the picture display performance of the Augmented Reality (AR) device, thereby affecting the visual experience and immersion experience of the user. In particular, the rainbow effect of the coupling-out region is a very obvious disadvantage of the current diffractive optical waveguide solution design, but with current technology, this effect can only be reduced as much as possible by new design/modification of the grating structure on the waveguide substrate, but the effect is not ideal.
Disclosure of Invention
The application aims to provide a novel technical scheme of a light guide device and wearable equipment.
In a first aspect, an embodiment of the present application provides a light guide device. The light guide device comprises a waveguide substrate, and a coupling-in region and a coupling-out region which are arranged on the waveguide substrate;
Wherein the waveguide substrate comprises at least two different refractive indices;
the coupling-in region is used for coupling incident light into the waveguide substrate;
The waveguide substrate is used for transmitting the incident light to the coupling-out region in a total reflection way, and different light beams in the incident light can have the same or similar light transmission path length after being subjected to reflection modulation of different refractive indexes in the waveguide substrate;
The coupling-out region is used for coupling out the light beam transmitted to the coupling-out region.
Optionally, the coupling-in region is located in a high refractive index region with the highest refractive index on the waveguide substrate, and a gradient distribution with the decreasing refractive index is formed on the waveguide substrate from the coupling-in region to a direction away from the coupling-in region.
Optionally, the waveguide substrate has a single-layer structure with graded refractive index.
Optionally, the waveguide substrate is a laminated structure made of two or more layers of materials with different refractive indexes, where each material may form at least one layer on the waveguide substrate and make the waveguide substrate have a refractive index, so that the waveguide substrate forms a gradient distribution with gradually changed refractive indexes.
Optionally, the coupling-in region is located on at least one surface of the waveguide substrate .
Alternatively, when the coupling-in region is provided on one surface of the waveguide substrate, a gradient distribution in which the refractive index gradually becomes smaller from the surface on which the coupling-in region is provided to the other surface opposite thereto is formed on the waveguide substrate in the thickness direction thereof.
Alternatively, when the coupling-in regions are provided on both surfaces of the waveguide substrate, a gradient distribution in which refractive indexes gradually decrease from the surfaces on both sides toward the middle region is formed on the waveguide substrate in the thickness direction thereof.
Optionally, the coupling-in region is located at a side surface of the waveguide substrate, the side surface is an inclined surface or a plane, and gradient distribution with reduced refractive index is formed on the waveguide substrate from the coupling-in region to a direction away from the coupling-in region;
when the side surface is a plane, an in-coupling prism is arranged at one side of the in-coupling region.
Optionally, the incident light includes at least a first light beam and a second light beam, and when the diffraction angle of the second light beam is greater than that of the first light beam on the interface of the high refractive index and the low refractive index of the waveguide substrate, the first light beam can penetrate through the interface to enter the low refractive index area, and be reflected and modulated by the low refractive index area, and then be transmitted to the interface and enter the high refractive index area, so that the light propagation path length of the first light beam in the waveguide substrate in one total reflection is the same as or similar to the light propagation path length of the second light beam in the waveguide substrate in one total reflection.
Optionally, the coupling-in region and the coupling-out region are provided with a single diffractive optical element or a diffractive optical element formed by combining a plurality of diffractive optical elements.
Optionally, the coupling-in region and the coupling-out region are provided with diffractive optical elements, and the diffractive optical elements include one or more of a surface relief grating, a volume hologram grating, a liquid crystal grating, and a photonic crystal.
Optionally, the coupling-in region and the coupling-out region are located on the same side of the waveguide substrate; or alternatively
The coupling-in region and the coupling-out region are arranged on opposite sides of the waveguide substrate.
Optionally, the incident light includes at least two light beams of the same wavelength incident on the coupling-in region at different incident angles;
Or alternatively
The incident light is multi-wavelength light comprising at least two light beams with different wavelengths, and the light beams with different wavelengths are all incident into the coupling-in area at the same incident angle.
In a second aspect, embodiments of the present application provide a wearable device. The wearable device includes:
the light guide device of the first aspect; and
And the optical machine is used for injecting the incident light rays or the image into the coupling-in area on the light guide device.
The application has the beneficial effects that:
The embodiment of the application provides an optical waveguide design scheme, which can be used for correcting the path length of light beams which are coupled into the waveguide substrate and are propagated through total reflection by designing the waveguide substrate with different refractive indexes, so that all the light beams which are coupled into the waveguide substrate and propagated through total reflection can have the same or similar path length of light propagation, and the phenomena of rainbow effect, light leakage (Backcoupling) and the like in a coupling-out area can be effectively avoided, thereby being beneficial to improving the light efficiency and imaging quality.
Other features of the present application and its advantages will become apparent from the following detailed description of exemplary embodiments of the application, which proceeds with reference to the accompanying drawings.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description, serve to explain the principles of the application.
FIG. 1 is a schematic diagram of a light guide device according to an embodiment of the present application;
FIG. 2 is a second schematic diagram of a light guide device according to an embodiment of the present application;
FIG. 3 is a schematic illustration of the light propagation path of a conventional diffractive optical waveguide;
FIG. 4 is a second schematic diagram of the light propagation path of a conventional diffractive optical waveguide;
FIG. 5 is a third schematic view of the light propagation path of a conventional diffractive optical waveguide;
FIG. 6 is a schematic diagram of a light propagation path of a conventional diffractive optical waveguide;
FIG. 7 is a schematic diagram of a light propagation path of a light guide device according to an embodiment of the present application;
Fig. 8 is a second schematic view of a light propagation path of the light guide device according to the embodiment of the present application.
Reference numerals illustrate:
1. A waveguide substrate; 11. a high refractive index layer; 12. a low refractive index layer; 2. a coupling-in region; 3. a coupling-out region; 01. incident light;
011. a first light beam; 012. a second light beam;
001. A substrate; 002. coupled into the grating.
Detailed Description
Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that: the relative arrangement of the components and steps, numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present application unless it is specifically stated otherwise.
The following description of at least one exemplary embodiment is merely exemplary in nature and is in no way intended to limit the application, its application, or uses.
Techniques, methods, and apparatus known to one of ordinary skill in the relevant art may not be discussed in detail, but are intended to be part of the specification where appropriate.
In all examples shown and discussed herein, any specific values should be construed as merely illustrative, and not a limitation. Thus, other examples of exemplary embodiments may have different values.
It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further discussion thereof is necessary in subsequent figures.
The light guide device and the wearable device provided by the embodiment of the application are described in detail below with reference to the accompanying drawings.
Among the various forms of wearable devices, taking an AR head mounted display device as an example, the AR head mounted display device generally includes a micro display screen and an optical module. Examples of optical elements commonly used in the optical module of the AR head-mounted display device include a prism, a free-form surface lens, and an optical waveguide device. In these optical elements described above, the optical waveguide device includes a geometric optical waveguide and a diffractive optical waveguide. The diffraction optical waveguide has good optical performance, so that the diffraction optical waveguide is widely applied to AR equipment.
According to an embodiment of the present application, there is provided a light guide device, for example, an optical waveguide device, for example, a diffractive optical waveguide.
The light guide device provided by the embodiment of the application can be applied to head-mounted display equipment, such as AR intelligent glasses, AR helmets and the like, for example, so that a user can obtain visual experience with better immersion.
Referring to fig. 1 and 2, and fig. 7 and 8, the light guide device provided by the embodiment of the application includes a waveguide substrate 1, and a coupling-in region 2 and a coupling-out region 3 disposed on the waveguide substrate 1; wherein the waveguide substrate 1 comprises at least two different refractive indices; the coupling-in region 2 is used for coupling incident light rays 01 into the waveguide substrate 1; the waveguide substrate 1 is configured to transmit the incident light ray 01 to the coupling-out region 3 in a total reflection manner, and different light beams in the incident light ray 01 can have the same or similar light propagation path length after being subjected to reflection modulation with different refractive indexes in the waveguide substrate 1; the out-coupling region 3 is used for out-coupling the light beam propagating to the out-coupling region 3.
The conventional diffractive optical waveguide is generally made of materials with the same refractive index, based on the dispersion effect of the coupling grating, different light beams in incident light rays can have different transmission channels after entering the substrate through the coupling grating, namely, different light beams can be transmitted to the coupling grating through total reflection in the substrate at different total reflection angles, so that obvious differences exist in the light transmission path lengths of the different light beams when the light beams are transmitted through the total reflection in the substrate, rainbow effect can be caused in human eyes when the light beams are coupled out of the coupling grating, and in addition, light leakage phenomenon (Backcoupling) can be generated at the coupling grating by the light beams, and the phenomena can reduce light efficiency, influence imaging quality and further influence the viewing experience of users.
Specifically, referring to fig. 3 to 6, the light source may emit an incident light ray 01, for example, RGB three-color light, that is, the incident light ray 01 includes, for example, a red light beam R, a blue light beam B, and a green light beam G, wherein the wavelength of the blue light beam B is shortest, and the wavelength of the red light beam R is longest. For the existing single refractive index substrate 001, the diffraction angle of the incident light 01 generated by the light beams with different wavelengths and/or different incident angles when the incident light 01 is coupled into the substrate 001 from the outside through the coupling-in grating 002 will be different due to the diffraction effect of the coupling-in grating 002.
For example, referring to fig. 3, three light beams of different wavelengths (e.g., RGB) are coupled into the substrate 001 at the same incident angle, and the diffraction angles of the three different light beams are different. In addition, referring to fig. 4, three beams with the same wavelength are coupled into the substrate 001 through the coupling grating 002 at different incident angles, which also results in different diffraction angles.
The light propagation path lengths of the light beams with different wavelengths or different incident angles for the primary total reflection in the substrate 001 with the same refractive index material may be different, which may cause two problems: the first aspect is that the intensities of the light emitted from different wavelengths at the same position of the coupling-out grating are hard to balance due to pupil expansion, so that the rainbow phenomenon of uneven color observed by human eyes is caused, and fig. 5 can be seen; in the second aspect, the diffraction angles of the different light beams may cause the light beams with partial diffraction angles to be incident again on the coupling-in grating 002 by total reflection when being coupled into the substrate 001, which may cause light leakage, called Backcoupling, especially often occurring on the blue light beam B with a shorter wavelength, see fig. 6.
The light guide device provided by the embodiment of the application is a novel diffraction light guide structure, and the waveguide substrate 1 is designed to have at least two different refractive indexes, so that the waveguide substrate 1 with a refractive index change is formed, and the different refractive indexes can modulate the light propagation path length of partial light beams in the incident light 01, which are totally reflected in the waveguide substrate 1 at one time, so that the problems of the prior art that the light propagation path length of the incident light 01 coupled into the waveguide substrate is different due to different diffraction angles are solved, and the rainbow effect of the coupling-out region 3 and the light leakage phenomenon of the coupling-in region 2 are caused.
The embodiment of the application provides the light guide device, wherein the waveguide substrate 1 has at least two different refractive indexes. Alternatively, the waveguide substrate 1 may be, for example, a single-layer structure with graded refractive index, or may be a multi-layer structure formed by stacking a plurality of materials with different refractive indexes. So that the waveguide substrate 1 of the embodiment of the present application is a graded index/refractive index changing waveguide substrate.
It should be noted that, in the embodiment of the present application, the waveguide substrate 1 is not limited to have only two different refractive indices, but may have three or more different refractive indices, which is related to the case of the incident light ray 01. Specifically, the more wavelengths or angles of incidence the incident light ray 01 contains a light beam, the more refractive indices the waveguide substrate 1 should employ. It will also be appreciated that the waveguide substrate 1 may be made of a number of materials of different refractive indices.
The embodiment of the application provides an optical waveguide design scheme, by designing the waveguide substrate 1 with different refractive indexes, the optical waveguide design scheme can be used for correcting the path length of light rays of partial light beams coupled into the waveguide substrate 1 for total reflection propagation, so that each light beam of the primary total reflection propagation in the waveguide substrate 1 can have the same or similar path length of light rays, and thus the phenomena of rainbow effect generated in the coupling-out area 3, light leakage (Backcoupling) generated in the coupling-in area 2 and the like can be effectively avoided, and the optical efficiency and imaging quality are improved.
That is, in the embodiment of the present application, the novel waveguide substrate structural design manner realizes the colorless propagation of the incident light ray 01 in the waveguide substrate 1, improves the overall optical efficiency of the light guide device, and well solves the rainbow effect easily occurring at the coupling-out region 3.
The incident light ray 01 may, for example, include at least two light beams of the same wavelength, which are incident on the coupling-in region 2 at different incident angles.
Alternatively, the incident light ray 01 may be a multi-wavelength light ray including at least two light beams with different wavelengths, and the light beams with different wavelengths all enter the coupling-in area 2 at the same incident angle.
The light guide device provided by the embodiment of the application is not limited to the specific form of the incident light ray 01. The incident light ray 01 may be a plurality of single-wavelength light rays emitted by a single-wavelength light source, or may be a plurality of wavelength light rays emitted by a multi-wavelength light source, such as RGB light, etc.
According to the light guide device provided by the embodiment of the application, after the incident light rays 01 in any form are coupled into the waveguide substrate 1 through the coupling-in area 2, the waveguide substrate 1 can correspondingly modulate the light propagation paths of primary total reflection of different light beams in the incident light rays 01 based on the change of refractive indexes, so that each light beam has the same or similar light propagation path length, and the light intensity of the light beams which are different at the same position of the coupling-out area 3 after pupil expansion can be ensured to be balanced, so that the color observed by human eyes is uniform; meanwhile, light leakage caused by the fact that light beams with partial angles are incident to the coupling-in region 2 again through total reflection when the light beams are coupled into the waveguide substrate 1 due to different diffraction angles of different light beams can be avoided, so that coupling-in efficiency can be improved, and light energy waste is avoided.
In some examples of the present application, referring to fig. 7 and 8, the coupling-in region 2 is located in a high refractive index region with the highest refractive index on the waveguide substrate 1, and a gradient distribution of decreasing refractive index is formed on the waveguide substrate 1 from the coupling-in region 2 to a direction away from the coupling-in region 2.
In the light guide device of the embodiment of the present application, the coupling-in region 2 is designed to be located in the region with the highest refractive index on the waveguide substrate 1, and the refractive index tends to be gradually smaller as the coupling-in region 2 is further away. The design can modulate the light beam (such as blue light beam B) with shorter wavelength in the incident light ray 01, so as to avoid the light leakage phenomenon of the light beam in the coupling-in area 2 as much as possible, thereby improving the coupling-in efficiency, and the design mode is beneficial to the fact that different light beams transmitted to the coupling-out area 3 can have identical or similar transmission paths in the process of one total reflection, so that the light beams with different colors coupled out from the coupling-out area 3 are uniformly distributed, and the human eyes can see pictures with uniform colors.
In one example of the present application, the waveguide substrate 1 has a single-layer structure with graded refractive index.
That is, one form of the waveguide substrate 1 is a unitary structure having different refractive indices. For example, the waveguide substrate 1 is a single-layer film or sheet-like structure having a set thickness and exhibiting a gradually decreasing or increasing refractive index thereon in a set direction.
In the above example, referring to fig. 8, the trend of the refractive index change is related to the position of the coupling-in region 2 provided on the waveguide substrate 1. That is, the coupling-in region 2 is designed to be located in the region of highest refractive index, whereas the farther from the coupling-in region 2 the refractive index is smaller.
It can be understood that, based on the waveguide substrate 1 in the above example, when the coupling-in region 2 is provided on one surface of the waveguide substrate 1, the refractive index exhibits a gradient distribution that gradually becomes smaller from the coupling-in region 2 to a direction away from the coupling-in region 2 in the thickness direction of the waveguide substrate 1.
Further, when the waveguide substrate 1 has two different refractive indexes and the coupling-in region 2 is located on one surface of the waveguide substrate 1, the refractive index of the surface on which the coupling-in region 2 is located should be high of the two refractive indexes, and the other surface of the waveguide substrate 1 should be low of the two refractive indexes. Alternatively, the out-coupling region 3 may be on the same surface as the in-coupling region 2, both in the high refractive index region. Of course, the coupling-out region 3 may be located on the opposite side, i.e. on a different surface, of the waveguide substrate 1 than the coupling-in region 2, where the coupling-in region 2 is located in a high-refractive-index region of the two refractive indices and the coupling-out region 3 is located in a low-refractive-index region of the two refractive indices.
It should be noted that the waveguide substrate 1 is not limited to have only two different refractive indexes, and more materials having different refractive indexes may be introduced to make the waveguide substrate 1 so that the waveguide substrate 1 includes three or more refractive indexes.
In the waveguide substrate 1, as more materials are added, the gradient of the refractive index change is more, so that the length of the light propagation path of the light beams with different wavelengths and FOV, which are totally reflected in the waveguide substrate 1, can be precisely controlled, and the defects in the prior art can be better overcome.
For example, referring to fig. 8, although the waveguide substrate 1 is a single layer, when the waveguide substrate 1 has a graded refractive index, by controlling the gradient change of the refractive index, it is possible to achieve that light beams of different wavelengths, such as a red light beam R, a green light beam G, and a blue light beam B (the three of which constitute an incident light ray 01), have the same or close light ray propagation path lengths in one total reflection propagation within the waveguide substrate 1.
When the waveguide substrate 1 includes three or more refractive indexes, the refractive indexes should be designed to be gradually decreased in gradient distribution in a direction away from the coupling-in region 2, but the difference between any adjacent two refractive indexes may be the same or different, which is not limited in the embodiment of the present application.
In another example of the present application, referring to fig. 7, the waveguide substrate 1 is a laminated structure of two or more layers made of materials with different refractive indexes, wherein each material may form at least one layer on the waveguide substrate 1 and provide the waveguide substrate 1 with a refractive index such that the waveguide substrate 1 forms a gradient distribution in which the refractive index gradually changes from layer to layer.
Referring to fig. 7, the waveguide substrate 1 of the light guide device may also have another form, such as a multi-layered stacked structure. On the basis of this, the refractive index of each layer of the waveguide substrate 1 may be different, which may form a refractive index gradient distribution in which the refractive index varies layer by layer. The coupling-in region 2 is for example arranged on a layer of material with the highest refractive index, and likewise the refractive index decreases progressively further away from the coupling-in region 2. That is, the layer with the highest refractive index on the waveguide substrate 1 is closer to the coupling-in region 2 where the external light is incident, and the refractive index is lower as it is farther from the coupling-in region 2.
The waveguide substrate 1 is not limited to the double-layer structure shown in fig. 7, and the waveguide substrate 1 may be a three-layer or more composite structure, so that more variation in refractive index is formed in thickness, for example. On this basis, the more the number of layers the waveguide substrate 1 contains, the more the gradient of the refractive index change.
Specifically, the refractive index gradient of the waveguide substrate 1 may be designed according to the incident light ray 01, which is not limited in the embodiment of the present application. It should be noted that the thickness of the waveguide substrate 1 is not too thick, which would affect the light and thin performance of the entire light guide device, which would affect the wearing experience of the user.
For example, referring to fig. 7, the waveguide substrate 1 is a double-layer structure formed of two materials having different refractive indexes, in which one layer is a high refractive index layer 11 and the other layer is a low refractive index layer 12. The coupling-in region 2 is for example arranged on the high refractive index layer 11, while the coupling-out region 3 may be arranged on the high refractive index layer 11 or on the low refractive index layer 12, without being limited thereto.
For another example, the waveguide substrate 1 is a three-layer structure formed by three materials with different refractive indexes, and specifically includes a high refractive index layer and a low refractive index layer, where the refractive index of the material layer between the two layers is also between the refractive indexes of the two layers. This also forms a gradient profile of stepwise refractive index changes. In this case, the coupling-in region 2 is located on the high refractive index layer, and the coupling-out region 3 may be located on the same surface as the coupling-in region 2 or may be located on a different side from the coupling-in region 2.
It should be noted that, when the waveguide substrate 1 has three or more layers, the refractive index should be designed to be gradually reduced along the direction away from the coupling-in region 2, but the refractive index difference between any two adjacent layers may be the same or different, which is not limited in the embodiment of the present application.
In some examples of the application, the coupling-in region 2 is located on at least one surface of the waveguide substrate 1 as described with reference to fig. 7 and 8 .
Alternatively, when the coupling-in region 2 is provided on one surface of the waveguide substrate 1, a gradient distribution in which the refractive index gradually becomes smaller from the surface on which the coupling-in region 2 is provided to the other surface opposite thereto is formed on the waveguide substrate 1 in the thickness direction thereof.
Alternatively, when the coupling-in regions 2 are separately provided on both surfaces of the waveguide substrate 1, a gradient distribution in which refractive indexes gradually decrease from both surfaces toward a middle region is formed on the waveguide substrate 1 in the thickness direction thereof.
That is, when the coupling-in region 2 is laid on the surface of the waveguide substrate 1, the variation in refractive index on the waveguide substrate 1 may be in the thickness direction of the waveguide substrate 1. More specifically, the refractive index shows a gradient distribution that gradually decreases from the position of the coupling-in region 2 toward the direction away from the coupling-in region 2. I.e. the waveguide substrate 1 exhibits a graded refractive index in the thickness direction. The manufacturing process of the waveguide substrate 1 is simpler and is beneficial to mass production.
On other waveguide substrates 1, the coupling-in region 2 is not limited to be provided on only one surface, i.e., the coupling-in region 2 may be provided separately on both surfaces of the waveguide substrate 1. On the basis, each coupling-in region 2 is located in the high refractive index region, and the waveguide substrate 1 forms a gradient distribution of gradually decreasing refractive index from two surfaces to a middle region along the thickness direction. While the refractive index of the middle region is smallest as seen from the entire thickness direction of the waveguide substrate 1.
Specifically, the single-layer waveguide substrate 1 has a minimum refractive index in a central region thereof. The refractive index of the intermediate material layer of the multilayer waveguide substrate 1 is the smallest. In this way, a gradient change trend gradually decreasing and gradually increasing is formed in the thickness direction of the waveguide substrate 1.
Furthermore, it is optional that on some light guides the coupling-in region 2 is not located on the surface of the waveguide substrate 1, but is located at the side of the waveguide substrate 1.
In some examples of the application, the coupling-in region 2 is located on a side surface of the waveguide substrate 1, the side surface is an inclined surface or a plane, and a gradient distribution of refractive index decrease is formed on the waveguide substrate 1 from the coupling-in region 2 to a direction away from the coupling-in region 2; wherein, when the side surface is a plane, an incoupling prism is arranged at one side of the incoupling region 2.
When the coupling-in region 2 is located on the side surface of the waveguide substrate 1, the light leakage phenomenon of the coupling-in region 2 can be solved, and the refractive index gradient of the waveguide substrate 1 can better improve the coupling-in efficiency, so as to completely avoid the light leakage phenomenon of the coupling-in region, and solve the rainbow effect of the coupling-out region 3.
In the light guide device provided in the embodiment of the present application, the incident light 01 includes at least a first light beam 011 and a second light beam 012, when the diffraction angle of the second light beam 012 is greater than the diffraction angle of the first light beam 011 on the interface between the high refractive index and the low refractive index of the waveguide substrate 1, the first light beam 011 can penetrate through the interface to enter the low refractive index region, and be reflected and modulated by the low refractive index region, and then propagates to the interface and is transmitted into the high refractive index region, so that the propagation path length of the light beam of the first light beam 011 that is totally reflected once in the waveguide substrate 1 is the same as or is close to the propagation path length of the light beam of the second light beam 012 that is totally reflected once in the waveguide substrate 1.
The basic optical Snell's law states that the angular variation of light rays at the interface of different media follows the following formula:
n1*sin(θ1)＝n2*sin(θ2)；
Wherein n1 and n2 are refractive indexes of the two dielectric materials respectively, and theta 1 and theta 2 are normal angles between light rays in the two dielectric materials and an interface respectively.
For example, taking the red light beam R and the blue light beam B with the largest diffraction angle difference as an example, referring to fig. 7, the red light beam R is the second light beam 012 in fig. 7, and the blue light beam B is the first light beam 011. At the interface of the high refractive index layer 11 and the low refractive index layer 12, the red light beam R still follows the law of total reflection according to the snell's law, as the diffraction angle is larger compared to the blue light beam B, substantially consistent with the optical behavior when a single layer waveguide substrate is used. Whereas the blue light beam B has a smaller diffraction angle and thus can enter the low refractive index layer 12 through the interface. The light beam propagates in the low refractive index layer 12 through a distance to enter the bottom interface of the low refractive index layer 12, and is totally emitted to return to the interface of the low refractive index layer 12 and the high refractive index layer 11 and is transmitted into the high refractive index layer 11, the light angle is consistent with that of the single-layer waveguide substrate after total reflection, but the propagation path length is longer and is closer to that of the red light beam R, which can effectively weaken the rainbow effect of the coupling-out region 3 and avoid Backcoupling phenomenon of the coupling-in region 2.
In some examples of the application, the coupling-in region 2 and the coupling-out region 3 are provided with a single diffractive optical element or a diffractive optical element composed of a combination of a plurality of diffractive optical elements.
For example, the incoupling region 2 is provided with a one-dimensional grating. One-dimensional gratings are well suited for use in the coupling-in portion of most diffractive optical waveguides. The direction of the one-dimensional grating vector is perpendicular to the grating lines, is the direction of periodic variation, and has a length equal to the reciprocal of the grating period.
For example, the coupling-out region 3 is provided with a two-dimensional grating, a combination of a one-dimensional grating and a two-dimensional grating, a combination of a one-dimensional grating, etc. A pupil expansion effect can be achieved in the out-coupling region 3.
Optionally, the coupling-in area 2 and the coupling-out area 3 are provided with diffractive optical elements, which comprise one or more of surface relief gratings, volume holographic gratings, liquid crystal gratings and photonic crystals.
The various gratings are diffraction gratings, and a proper type of diffraction grating can be selected as required to be applied to the coupling-in region 2 of the light guide device, which is not particularly limited in the embodiment of the present application. That is, the scheme of the present application is not limited to the specific type of the coupling-in area 2, and has a wide application range.
In an embodiment of the application, the coupling-in region 2 and the coupling-out region 3 are located on the same side of the waveguide substrate 1; or the coupling-in region 2 and the coupling-out region 3 are arranged on opposite sides of the waveguide substrate 1.
In another aspect, an embodiment of the present application provides a wearable device. The wearable device comprises the light guide device and the optical machine; the optical machine is used for injecting the incident light ray 01 or the image into the coupling-in area 2 on the light guide device.
The wearable device further comprises a shell, and the light guide device and the optical machine are arranged in the shell.
The wearable device is, for example, a head mounted display device such as an AR head mounted display device.
The AR head-mounted display device includes AR smart glasses or AR smart helmets, etc., which are not limited in the present application.
The specific implementation manner of the wearable device according to the embodiment of the present application may refer to the above embodiment of the light guide device, so at least the technical solution of the above embodiment has all the beneficial effects, which are not described in detail herein.
The foregoing embodiments mainly describe differences between the embodiments, and as long as there is no contradiction between different optimization features of the embodiments, the embodiments may be combined to form a better embodiment, and in consideration of brevity of line text, no further description is given here.
While certain specific embodiments of the application have been described in detail by way of example, it will be appreciated by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the application. It will be appreciated by those skilled in the art that modifications may be made to the above embodiments without departing from the scope and spirit of the application. The scope of the application is defined by the appended claims.
Claims (14)
1. The light guide device is characterized by comprising a waveguide substrate (1), and a coupling-in region (2) and a coupling-out region (3) which are arranged on the waveguide substrate (1);
Wherein the waveguide substrate (1) comprises at least two different refractive indices;
The coupling-in region (2) is used for coupling incident light rays (01) into the waveguide substrate (1);
The waveguide substrate (1) is used for transmitting the incident light rays (01) to the coupling-out region (3) in a total reflection way, and different light beams in the incident light rays (01) can have the same or similar light transmission path length after being subjected to reflection modulation of different refractive indexes in the waveguide substrate (1);
the out-coupling region (3) is used for out-coupling the light beam propagating to the out-coupling region (3).
2. A light-guiding device according to claim 1, characterized in that the coupling-in region (2) is located on the waveguide substrate (1) in a region of highest refractive index, the waveguide substrate (1) forming a gradient profile of decreasing refractive index from the coupling-in region (2) to a direction away from the coupling-in region (2).
3. A light guide device according to claim 1, characterized in that the waveguide substrate (1) is of a single-layer structure with graded refractive index.
4. A light guide device according to claim 1, characterized in that the waveguide substrate (1) is a laminated structure of two or more layers made of materials of different refractive index, wherein each material may form at least one layer on the waveguide substrate (1) and give the waveguide substrate (1) a refractive index such that the waveguide substrate (1) forms a graded profile with graded refractive index layer by layer.
5. A light-guiding device according to claim 1, characterized in that the coupling-in region (2) is located on at least one surface of the waveguide substrate (1) .
6. A light guide device according to claim 5, characterized in that when the coupling-in region (2) is provided on one surface of the waveguide substrate (1), a gradient distribution in which the refractive index gradually decreases from the surface on which the coupling-in region (2) is provided to the other surface opposite thereto is formed on the waveguide substrate (1) in the thickness direction thereof.
7. A light guide device according to claim 5, characterized in that, when the coupling-in regions (2) are provided separately on both surfaces of the waveguide substrate (1), a gradient distribution of refractive index gradually decreasing from the surfaces on both sides to the middle region is formed on the waveguide substrate (1) in the thickness direction thereof.
8. A light-guiding device according to claim 1, characterized in that the coupling-in region (2) is located at a side of the waveguide substrate (1), which side is a bevel or a plane, a gradient distribution of decreasing refractive index being formed on the waveguide substrate (1) from the coupling-in region (2) to a direction away from the coupling-in region (2);
When the side faces are plane, an incoupling prism is arranged on one side of the incoupling region (2).
9. The light guide device according to claim 1, wherein the incident light (01) at least comprises a first light beam (011) and a second light beam (012), and when the diffraction angle of the second light beam (012) is larger than that of the first light beam (011) at the interface between the high refractive index and the low refractive index of the waveguide substrate (1), the first light beam (011) can penetrate through the interface to enter the low refractive index region, and is reflected and modulated by the low refractive index region, and then propagates to the interface and is transmitted into the high refractive index region, so that the light propagation path length of the first light beam (011) in the waveguide substrate (1) in one time is the same as or similar to the light propagation path length of the second light beam (012) in the waveguide substrate (1) in one time.
10. A light guide device according to claim 1, characterized in that the coupling-in region (2) and the coupling-out region (3) are provided with a single diffractive optical element or a diffractive optical element composed of a combination of a plurality of diffractive optical elements.
11. A light guide device according to claim 1, characterized in that the coupling-in region (2) and the coupling-out region (3) are provided with diffractive optical elements comprising one or more of surface relief gratings, volume holographic gratings, liquid crystal gratings and photonic crystals.
12. A light-guiding device according to claim 1, characterized in that the coupling-in region (2) and the coupling-out region (3) are located on the same side of the waveguide substrate (1); or alternatively
The coupling-in region (2) and the coupling-out region (3) are arranged on opposite sides of the waveguide substrate (1).
13. The light guide device according to claim 1, characterized in that the incident light rays (01) comprise at least two light beams of the same wavelength that enter the coupling-in region (2) at different angles of incidence;
Or alternatively
The incident light (01) is multi-wavelength light comprising at least two light beams with different wavelengths, and the light beams with different wavelengths are all incident into the coupling-in area (2) at the same incident angle.
14. A wearable device, the wearable device comprising:
the light guide device of any one of claims 1-13; and
And the optical machine is used for injecting the incident light rays (01) or the images into the coupling-in area (2) on the light guide device.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211362772.0A CN118033808A (en) | 2022-11-02 | 2022-11-02 | Light guide device and wearable equipment |
| PCT/CN2023/106502 WO2024093348A1 (en) | 2022-11-02 | 2023-07-10 | Light guide device and wearable device |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202211362772.0A CN118033808A (en) | 2022-11-02 | 2022-11-02 | Light guide device and wearable equipment |
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| CN118033808A true CN118033808A (en) | 2024-05-14 |
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| CN202211362772.0A Pending CN118033808A (en) | 2022-11-02 | 2022-11-02 | Light guide device and wearable equipment |
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| WO (1) | WO2024093348A1 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7058261B2 (en) * | 2003-09-04 | 2006-06-06 | Sioptical, Inc. | Interfacing multiple wavelength sources to thin optical waveguides utilizing evanescent coupling |
| CN110596807B (en) * | 2019-08-20 | 2021-11-19 | 奥比中光科技集团股份有限公司 | Waveguide structure, display device, and electronic apparatus |
| CN113970847A (en) * | 2020-07-24 | 2022-01-25 | 苏州苏大维格科技集团股份有限公司 | Augmented reality waveguide lens and manufacturing method thereof |
| CN215219321U (en) * | 2021-05-17 | 2021-12-17 | 上海鲲游科技有限公司 | Near-to-eye display device |
| CN113433613A (en) * | 2021-07-22 | 2021-09-24 | Oppo广东移动通信有限公司 | Waveguide assembly, optical device and intelligent glasses |
| CN215264107U (en) * | 2021-07-26 | 2021-12-21 | Oppo广东移动通信有限公司 | Waveguide assembly, optical device and intelligent glasses |
| CN113791470B (en) * | 2021-09-24 | 2022-05-03 | 北京枭龙科技有限公司 | Resonance grating waveguide structure and near-to-eye display device |
| CN113848648A (en) * | 2021-09-24 | 2021-12-28 | 京东方科技集团股份有限公司 | Optical transmission system and display device |
| CN115113324A (en) * | 2022-07-14 | 2022-09-27 | 深圳格多维科技有限公司 | Graded-refractive-index optical waveguide AR glasses and AR imaging method |
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