CN118759725A - Array optical waveguide device and near-eye display device - Google Patents

Abstract

The present invention relates to an array optical waveguide device and a near-eye display device, wherein the array optical waveguide device comprises: a waveguide substrate, comprising a first surface and a second surface parallel to each other, wherein the first surface located at a coupling-out region is provided with a first grating, and the second surface located at the coupling-out region is provided with a second grating; an array spectroscopic film, comprising a plurality of spectroscopic films arranged at intervals and arranged in parallel and arranged obliquely between the first grating and the second grating; an incident light beam is totally reflected and propagated in the waveguide substrate, wherein the array spectroscopic film can split all or part of the incident light beam into a reflected light beam and a transmitted light beam, and when all or part of the incident light beam is incident from the other side of the spectroscopic film to the first grating or the second grating, the direction of the reflected light beam of the totally reflected light beam is rotated and offset by an angle γ in the clockwise direction, thereby reducing the process difficulty, reducing the ghost image phenomenon, and improving the light uniformity, and for large-angle incidence, it is easy to achieve the reflectivity control below 0.5%.

Description

Array optical waveguide device and near-eye display device

Technical Field

The present invention relates to the field of augmented reality technology, and in particular to an array optical waveguide device and a near-eye display device.

Background Art

There are usually two types of waveguide solutions in augmented reality display technology: array waveguide and diffraction waveguide. Array waveguide is mainly derived using geometric optics. It uses the coated optical surface to perform semi-transparent and semi-reflective operations to affect the light path, thereby achieving pupil expansion and coupling in and out. Diffraction waveguide uses the diffraction effect of light and uses gratings to make the required turns on the light, which can also achieve coupling in and out and pupil expansion.

Compared with the two, the advantage of array waveguides is that traditional coatings have a wide response to wavelengths or angles, while diffraction waveguides cannot effectively guarantee a wider wavelength range and angle range, that is, a large field of view, due to physical and process limitations. The advantage of diffraction waveguides is that the pupil continuity is better, and there are no film layer splicing gaps in array waveguides. At the same time, the physical and process limitations that may exist in the design and coating process of films with different polarizations do not exist in the design of diffraction systems.

According to FIG1 , the coupling-out structure of the conventional array waveguide is that the light is transmitted by total reflection on the first surface 10' and the second surface 20', that is, it is transmitted between the upper surface and the lower surface of the substrate. The same beam of light incident from two directions of the film layer will have different incident angles α and β: when incident at a small angle α, the reflected light is coupled out, and the transmitted light continues to be transmitted; when incident at a large angle β from the other side, the transmitted light continues to be transmitted, and the reflected light becomes a ghost image, that is, a ghost light M. For the film layer design of the array waveguide, the reflectivity is as low as possible for large angle incidence, that is, β incidence, but due to physical and process limitations, it is difficult to control the reflectivity very low for large angle incidence in actual coating.

Summary of the invention

In view of the problems existing in the prior art, the present invention provides an array optical waveguide device and a near-eye display device.

The technical solution of the present invention is as follows:

This specification provides an array optical waveguide device, comprising:

A waveguide substrate comprises a first surface and a second surface parallel to each other, and at least a coupling-out region is included between the first surface and the second surface, wherein a first grating is provided on the first surface at the coupling-out region, and a second grating is provided on the second surface at the coupling-out region;

An array of beam splitters, comprising a plurality of beam splitters arranged at intervals and in parallel, and tilted between the first grating and the second grating;

The incident light beam propagates by total reflection in the waveguide matrix, wherein the arrayed beam splitter film can split all or part of the incident light beam into a reflected light beam and a transmitted light beam, the reflected light beam is emitted from the waveguide matrix, and the transmitted light beam is transmitted to the next beam splitter film or the waveguide matrix. When all or part of the incident light beam is emitted from the other side of the beam splitter film to the first grating or the second grating, the direction of the total reflection of all or part of the light is rotated and offset by an angle γ in the clockwise direction.

As a preferred technical solution, the first grating and the second grating are the same.

As a preferred technical solution, the first grating and the second grating both satisfy the following relationship:

The scale intervals of the first grating and the second grating are both d, and d is the grating constant; the incident angle of the incident light beam incident on the first grating and the incident angle of the second grating are both θ; λ is the wavelength of the incident light beam.

As a preferred technical solution, the incident angle of the first grating is greater than the diffraction angle of the first grating, and the diffraction angle of the first grating is greater than zero; the incident angle of the second grating is greater than the diffraction angle of the second grating, and the diffraction angle of the second grating is greater than zero.

As a preferred technical solution, the incident light beam is red light, or green light, or blue light.

As a preferred technical solution, the reflectivity of each diaphragm film to incident light having a first incident angle is greater than the reflectivity of the diaphragm film to incident light having a second incident angle.

As a preferred technical solution, the reflectivity of the incident light at the first incident angle is 5%-15%; the reflectivity of the incident light at the second incident angle is 0-0.5%.

As a preferred technical solution, the γ angle is greater than zero and less than the first incident angle.

As a preferred technical solution, a plurality of dichroic films are tilted and arranged between the first grating and the second grating at a preset angle, wherein the preset angle is 20°-30°.

This specification also provides a near-eye display device, including the above-mentioned array optical waveguide device.

The beneficial effects achieved by the technical solution adopted by the present invention are:

The present specification provides an array optical waveguide device and a near-eye display device, which are provided with diffraction gratings on the upper and lower surfaces of a traditional waveguide plate, and utilize the light deflection effect of the diffraction grating to act on the two surfaces of a single-layer waveguide, so that the totally reflected outgoing light is deflected clockwise by an angle of γ, and the angle of γ is reduced compared to the large-angle β incident angle of the traditional array film, thereby effectively reducing the difficulty of coating a high-transmittance film, thereby reducing the ghost image phenomenon and improving the uniformity of the light. For large-angle incident light, it is easy to control its reflectivity below 0.5%.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments, which constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions explain the present invention and do not constitute improper limitations on the present invention. In the drawings:

FIG1 is a schematic diagram of the structure of an array optical waveguide device in the prior art;

FIG. 2 is a schematic diagram of the structure of the array optical waveguide device disclosed in this embodiment.

Description of reference numerals:

The first surface 10 ; the second surface 20 ; the first grating 11 ; the second grating 21 ; and the arrayed beam splitter film 30 .

DETAILED DESCRIPTION

In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention and the corresponding drawings. In the description of the present invention, it should be noted that the term "or" is usually used in the sense of including "and/or", unless the content clearly indicates otherwise.

In the description of the present invention, it should be understood that "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through a medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

In addition, those skilled in the art should understand that, in the disclosure of the present invention, the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the above terms should not be understood as limiting the present invention.

Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Example

According to FIG. 2 , an embodiment of the present invention provides an array optical waveguide device, including:

A waveguide substrate comprises a first surface 10 and a second surface 20 which are parallel to each other, and at least a coupling-out region is included between the first surface 10 and the second surface 20, wherein the first surface 10 located at the coupling-out region is provided with a first grating 11, and the second surface 20 located at the coupling-out region is provided with a second grating 21;

The array beam splitter film 30 includes a plurality of beam splitters which are spaced apart and arranged in parallel, and are tiltedly disposed between the first grating 11 and the second grating 21;

The incident light beam propagates by total reflection in the waveguide matrix, wherein the arrayed beam splitter film 30 can split all or part of the incident light beam into a reflected light beam and a transmitted light beam, the reflected light beam is emitted from the waveguide matrix, and the transmitted light beam is transmitted to the next beam splitter film or the waveguide matrix. When all or part of the incident light beam is emitted from the other side of the beam splitter film to the first grating 11 or the second grating 21, the direction of the total reflection of all or part of the light is rotated and offset by an angle γ in the clockwise direction.

In this embodiment, the angle γ is understood in combination with the traditional technical solution of Figure 1. The same beam of light will have different incident angles α and β when it is incident from two directions of the film layer: when it is incident at a small angle α, the reflected light is coupled out and the transmitted light continues to be transmitted; when it is incident at a large angle β from the other side, the transmitted light continues to be transmitted, and the reflected light becomes a ghost light M. In order to avoid this phenomenon, it is proposed to set a grating on the two surfaces of the traditional waveguide substrate, and use the light deflection effect of the diffraction grating to achieve total reflection of the outgoing light when it is incident at a large angle β from the other side, and deflect the γ angle clockwise. That is to say, compared with the large angle β incident on the traditional array film, the γ angle is reduced.

Based on the ghost phenomenon of the existing array waveguide outcoupling structure and the problem that the reflectivity at large angles is difficult to control due to physical and process limitations, in this embodiment, diffraction gratings are set on the two surfaces of the traditional waveguide plate, and the light deflection effect of the diffraction grating is used to act on the two surfaces of the single-layer waveguide. The totally reflected outgoing light is deflected clockwise by an angle of γ, which reduces the γ angle compared to the large-angle β incident angle of the traditional array film, effectively reducing the difficulty of coating high-transmittance films, thereby reducing the ghost phenomenon and improving the uniformity of light.

Preferably, the first grating 11 and the second grating 21 are the same and are both reflection gratings.

Preferably, the first grating 11 and the second grating 21 both satisfy the following relationship:

The scale intervals of the first grating 11 and the second grating 21 are both d, and d is the grating constant; the incident angles of the incident light beam incident on the first grating 11 and the second grating 21 are both θ; and λ is the wavelength of the incident light beam.

Preferably, the incident angle of the first grating 11 is greater than the diffraction angle of the first grating 11 , and the diffraction angle of the first grating 11 is greater than zero; the incident angle of the second grating 21 is greater than the diffraction angle of the second grating 21 , and the diffraction angle of the second grating 21 is greater than zero.

Specifically, this embodiment mainly provides a new solution for the reflectivity control of the outcoupling film layer under the condition of large angle incidence. According to FIG2 , the waveguide substrate includes a first surface 10 and a second surface 20, i.e., an upper surface and a lower surface, which are parallel to each other. The upper surface and the lower surface at least include an outcoupling region. A first grating 11 is arranged on the upper surface, and a second grating 21 is arranged on the lower surface. That is, the waveguide plate and the first grating 11 and the second grating constitute the waveguide substrate as a whole. The first grating 11 and the second grating 21 are parallel to each other and arranged oppositely. For example, a two-dimensional array waveguide generally includes a coupling structure, a turning structure and an outcoupling structure. The first grating 11 and the second grating 21 can be arranged on the upper and lower surfaces of the outcoupling structure. Preferably, the first grating 11 and the second grating 21 are the same, such as the size, the internal structure, etc., which is conducive to the total reflection transmission of light inside the waveguide, and can effectively improve the uniformity of light. When the light is incident at a large angle, it is easy to control its reflectivity below 0.5%.

In another preferred embodiment, if the grating is a material that can be coated on the upper and lower surfaces, a layer of protective glass can be added on the outside in actual operation to protect the grating and help extend the service life of the array waveguide device.

Furthermore, the diffraction gratings on the upper and lower surfaces of the waveguide plate can deflect the originally totally reflected light. The grating on the upper surface is used to rotate the light propagating from the upper surface of the waveguide plate to the lower surface clockwise by an angle of γ, and the light transmitted by the waveguide becomes "steeper"; and the grating on the lower surface also rotates the light propagating from the lower surface of the waveguide plate to the upper surface clockwise by an angle of γ, and the light transmitted by the waveguide restores the original angle. This can effectively reduce the difficulty of coating high-transmittance films, thereby reducing ghost images and improving the uniformity of light. In other words, the incident angle β of the light incident from the other end of the film layer becomes β', and β'=β-γ, that is, the incident angle β of the large-angle incident light is reduced by an angle of γ, as shown in Figure 2. The dotted line with an arrow indicates the propagation direction of the original totally reflected reflected light, and the adjacent solid line with an arrow indicates that the totally reflected reflected light propagates in the direction rotated clockwise by an angle of γ.

Further, according to the realization of the above-mentioned angle change requirements, for the convenience of description, in this embodiment, the diffraction order of the first grating 11 and the second grating 21 is set to 1, then the grating equation is d(sinθ+sinφ)=λ, in Figure 2, in order to make the specific situation clear, arrows are used to indicate the propagation of light, and different dotted lines indicate the normal and the position of the dichroic film. In addition, Figure 2 shows a partial schematic diagram, and the first surface 10, the second surface 20, the first grating 11, and the second grating 21 in the figure are only schematic, and are not a limitation of the embodiment of the present invention. The specific implementation can be designed according to the actual situation.

In the present structure, the incident angle of the first grating 11 is greater than the diffraction angle of the first grating 11, and the diffraction angle of the first grating 11 is greater than zero; the incident angle of the second grating 21 is greater than the diffraction angle of the second grating 21, and the diffraction angle of the second grating 21 is greater than zero. According to FIG. 2 , for the incident angle and the diffraction angle on the grating plane, the incident angles of the first grating 11 and the second grating 21 are both θ, and the diffraction angles of the first grating 11 and the second grating 21 are both φ, then 0<φ<θ, and the following relationship can be further obtained:

The scale intervals of the first grating 11 and the second grating 21 are both d, and d is the grating constant; λ is the central wavelength of the incident light beam.

The above formula gives the relationship between the grating coefficient, wavelength and incident angle. The first grating 11 and the second grating 21 maintain the same grating constant d. For the same wavelength, the relationship between the incident angle and the diffraction angle is reversed: the two parameters of the initial incident light are (λ, θ), and after diffraction by the first grating 11, the outgoing light becomes (λ, φ) with reference to the diffraction grating formula; when passing through the second grating 21 again, the incident light is (λ, φ), and then according to the diffraction grating formula, the outgoing light changes back to (λ, θ), so that the normal transmission of the image light of the waveguide is not affected, and at the same time, the temporary adjustment of the light angle is achieved between the two gratings.

For light rays with different wavelengths and incident angles (λ ₁ , θ ₁ ) and (λ ₂ , θ ₂ ), their diffraction angles are φ ₁ and φ ₂ . Regardless of whether φ ₁ = φ ₂ , (φ ₁ , λ ₁ ) and (φ ₂ , λ ₂ ) will be transformed back into (θ ₁ , λ ₁ ) and (θ ₂ , λ ₂ ) at the time of the second diffraction. It is not required that all light rays have the same deflection angle. Therefore, the γ angle can be a constant or a variable depending on the actual situation.

Considering the overall implementation efficiency, the bandwidth range of the grating should be set smaller than the actual wavelength range of the image light. No matter which wavelength band is used as the incident light beam, it will not affect the normal waveguide image transmission. Only the light within a certain band is adjusted in angle to effectively reduce the ghost phenomenon. The coating design and process difficulty of this band will be reduced accordingly. Preferably, the incident light beam is red light, green light, or blue light, and the clockwise rotation γ angle is the best, which can effectively reduce or even eliminate the ghost phenomenon, improve the imaging quality, and thus enhance the user's visual experience.

In actual coating design, in order to improve the light uniformity effect, more attention can be paid to the angle adjustment of light in a shorter wavelength range. For example, the grating design is only for blue light, while red and green light remain in the original full reflection state.

The clockwise rotating γ angle is preferably greater than zero and less than the first incident angle. In particular, when incident at a large angle β from the other side, the reflected light of total reflection will rotate clockwise and deviate by the γ angle, thereby effectively suppressing the occurrence of ghosting.

Preferably, the reflectivity of each prismatic film to incident light having a first incident angle is greater than the reflectivity of the prismatic film to incident light having a second incident angle.

Specifically, the film layer design of the arrayed waveguide in the present embodiment is to control the reflection law at a small angle α to about 10%, and the reflectivity at a large angle β is as low as possible, that is, below 0.5%. In the present embodiment, preferably, the reflectivity of the incident light at the first incident angle is 5%-15%; the reflectivity of the incident light at the second incident angle is 0-0.5%. The arrayed waveguide plate out-coupling structure is provided with a diffraction grating method, which can reduce the incident angle and reduce the difficulty of coating design and manufacturing, making it easier to control it below 0.5%, that is, reduce the process difficulty, and easily achieve low reflectivity at a large angle β. The present structure is simple and can be widely used.

Preferably, the plurality of dichroic films are tilted at a preset angle between the first grating 11 and the second grating 21 , wherein the preset angle is 20°-30°.

Specifically, the arrayed waveguide plate includes an upper surface and a lower surface, a first grating 11 is arranged on the upper surface, and a second grating 21 is arranged on the lower surface, the first grating 11 and the second grating 21 are arranged opposite to each other, and a plurality of dichroic films are arranged between the first grating 11 and the second grating 21, the plurality of dichroic films are preferably arranged in parallel with equal spacing, and are tilted at a preset angle between the first grating 11 and the second grating 21, wherein the first grating 11 and the second grating 21 are preferably semi-transparent and semi-reflective mirrors, the preset angle is 20°-30°, and the diffraction grating has the best optimization effect on the ghost phenomenon. In this embodiment, the specific setting methods such as the number, spacing, and tilt angle of the dichroic films can be selected as needed, or those skilled in the art can set them according to actual needs, and this is not limited in the embodiment of the present application.

This embodiment also provides a near-eye display device, including the above-mentioned array optical waveguide device, which has a simple structural design and is easy to achieve low reflectivity at a large angle β incidence, effectively reducing ghosting phenomena, reducing process difficulty, and improving light uniformity.

The above is a detailed introduction to an array optical waveguide device and a near-eye display device according to an embodiment of the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method and core idea of the present application. At the same time, for a person skilled in the art, according to the idea of the present application, there may be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims (10)

1. An array optical waveguide device, comprising: A waveguide substrate, comprising a first surface and a second surface parallel to each other, and at least a coupling-out region between the first surface and the second surface, wherein the first surface located at the coupling-out region is provided with a first grating, and the second surface located at the coupling-out region is provided with a second grating; An array of splitter films, comprising a plurality of splitter films arranged at intervals and in parallel, and tilted between the first grating and the second grating; The incident light beam is totally reflected and propagates in the waveguide matrix, wherein the arrayed beam splitter film can split all or part of the incident light beam into a reflected light beam and a transmitted light beam, wherein the reflected light beam is emitted from the waveguide matrix, and the transmitted light beam is transmitted to the next beam splitter film or the waveguide matrix, and when all or part of the incident light beam is emitted from the other side of the beam splitter film to the first grating or the second grating, the direction of the total reflection of all or part of the light beam is rotated and offset by an angle γ in the clockwise direction. 2 . The arrayed optical waveguide device according to claim 1 , wherein the first grating and the second grating are identical. 3. The arrayed optical waveguide device according to claim 2, wherein the first grating and the second grating both satisfy the following relationship: The scale intervals of the first grating and the second grating are both d, and d is the grating constant; the incident angles of the incident light beam incident on the first grating and the incident angles of the second grating are both θ; and λ is the wavelength of the incident light beam. 4. The arrayed optical waveguide device according to claim 3, characterized in that the incident angle of the first grating is greater than the diffraction angle of the first grating, and the diffraction angle of the first grating is greater than zero; the incident angle of the second grating is greater than the diffraction angle of the second grating, and the diffraction angle of the second grating is greater than zero. 5 . The arrayed optical waveguide device according to claim 3 , wherein the incident light beam is red light, green light, or blue light. 6. The arrayed optical waveguide device according to claim 1, wherein the reflectivity of each of the beam splitting films to the incident light having a first incident angle is greater than the reflectivity of the beam splitting films to the incident light having a second incident angle. 7. The arrayed optical waveguide device according to claim 5, wherein the reflectivity of the incident light at the first incident angle is 5%-15%; and the reflectivity of the incident light at the second incident angle is 0-0.5%. 8 . The arrayed optical waveguide device according to claim 6 , wherein the γ angle is greater than zero and less than the first incident angle. 9. The arrayed optical waveguide device according to any one of claims 1 to 8, characterized in that the plurality of beam splitting films are tilted at a preset angle between the first grating and the second grating, wherein the preset angle is 20°-30°. 10. A near-eye display device, characterized in that it comprises the array optical waveguide device according to any one of claims 1 to 9.