阅读说明：本技术 一种光波导器件及近眼显示设备 (Optical waveguide device and near-to-eye display equipment ) 是由 王启蒙 赵宇暄 冒新宇 于 2021-03-19 设计创作，主要内容包括：本发明公开了一种光波导器件,第一光学元件使波导基体内传播光束发生衍射而使光束的至少一部分传播形式改变。其中,第一光学元件包括周期性排布的单元结构,单元结构的预设参量随单元结构所处位置变化,能够使得传播步长较大光束在相同范围内各个位置传播形式改变部分的能量总和,与传播步长较小光束在相同范围内各个位置传播形式改变部分的能量总和趋于一致,能够改善现有光波导方案由于光波导内传播步长不同的各光束耦出能量不均匀导致存在图像信息失真的情况。本发明还公开一种近眼显示设备。(A first optical element diffracts a light beam propagating in a waveguide substrate to change at least a part of a propagation form of the light beam. The first optical element comprises unit structures which are periodically arranged, preset parameters of the unit structures are changed along with the positions of the unit structures, the energy sum of the transmission form change parts of the light beams with larger transmission step lengths at all positions in the same range can be enabled to be approximately consistent with the energy sum of the transmission form change parts of the light beams with smaller transmission step lengths at all positions in the same range, and the condition that image information distortion exists due to the fact that coupling-out energy of the light beams with different transmission step lengths in the optical waveguide in the existing optical waveguide scheme can be improved. The invention also discloses a near-to-eye display device.)

1. An optical waveguide device comprising a waveguide substrate and a first optical element for diffracting a light beam propagating within the waveguide substrate to cause a change in the propagation form of at least a portion of the light beam;

the first optical element comprises unit structures which are arranged periodically, and the preset parameters of the unit structures are changed along with the positions of the unit structures, so that the energy sum of the transmission form change parts of the light beams with the larger transmission step length at each position in the same range is consistent with the energy sum of the transmission form change parts of the light beams with the smaller transmission step length at each position in the same range.

2. The optical waveguide device of claim 1 wherein the predetermined parameters of the cell structure include a groove depth of the cell structure, an angle of inclination of a side of the cell structure with respect to a normal to a surface of the waveguide substrate, a lateral dimension of the cell structure, or a refractive index of the cell structure.

3. The optical waveguide device according to claim 1, wherein the predetermined parameter of the unit structure varies with the position of the unit structure in the one-dimensional direction so that the sum of the energies of the portions of the beam having a larger propagation step size and the portions of the beam having a smaller propagation step size, which have changed their propagation forms at respective positions in the same range in the one-dimensional direction, tends to coincide with the sum of the energies of the portions of the beam having a smaller propagation step size and the portions of the beam having a changed their propagation forms at respective positions in the same range in the one-dimensional direction.

4. The optical waveguide device according to claim 1, wherein the first optical element includes a unit structure group arranged in sequence, the unit structure group includes the unit structures arranged periodically, and a length of the unit structure group along a light beam transmission direction in the waveguide substrate is matched with a maximum propagation step of a light beam propagating in the waveguide substrate.

5. The optical waveguide device according to claim 4, wherein the variation form of the preset parameter of the unit structure of one of the unit structure groups in the one-dimensional direction is a linear variation, or the variation form of the preset parameter of the unit structure of one of the unit structure groups in the one-dimensional direction is a step variation, or the preset parameter of the unit structure of one of the unit structure groups and the position of the unit structure in the one-dimensional direction satisfy an arc functional relationship.

6. The optical waveguide device according to claim 4, wherein the diffraction efficiency of each unit structure of the latter unit structure group on the light beam is greater than the diffraction efficiency of the unit structure of the corresponding position in the former unit structure group on the light beam of the same wavelength as the transmission distance of the light beam in the waveguide matrix is increased.

7. The optical waveguide device according to claim 1, wherein the predetermined parameter of the unit structure varies with the position of the unit structure in the first dimension direction so that the sum of the energies of the portions of the beam having a larger propagation step that have changed in propagation form at the respective positions in the same range in the first dimension direction tends to coincide with the sum of the energies of the portions of the beam having a smaller propagation step that have changed in propagation form at the respective positions in the same range in the first dimension direction;

the preset parameters of the unit structure are changed along with the position of the unit structure along the second dimension direction, so that the energy sum of the transmission form change parts of the light beam with the larger transmission step length at each position in the same range along the second dimension direction is consistent with the energy sum of the transmission form change parts of the light beam with the smaller transmission step length at each position in the same range along the second dimension direction.

8. The optical waveguide device according to claim 7, further comprising a second optical element from which the light beam transmitted to the first optical element comes, wherein the first dimension direction is parallel to a direction in which the second optical element is directed to the first optical element, and an angle between the second dimension direction and the first dimension direction is greater than zero degrees.

9. The optical waveguide device according to claim 1, further comprising a second optical element from which the light beam transmitted to the first optical element comes, the unit structure of the first optical element being symmetrical about a predetermined boundary on the first optical element, the predetermined boundary being a central axis of the first optical element parallel to a direction in which the second optical element is directed toward the first optical element.

10. The optical waveguide device of claim 1 wherein the predetermined parameters of the cell structure include a groove depth of the cell structure, a top of each cell structure of the first optical element being flat, or a bottom of each cell structure of the first optical element being flat.

11. The optical waveguide device according to any of claims 1 to 10, wherein the first optical element is in particular adapted to diffract the light beam propagating within the waveguide matrix such that at least a part of the light beam is coupled out of the waveguide matrix, or wherein the first optical element is in particular adapted to diffract the light beam propagating within the waveguide matrix such that at least a part of the light beam is deflected in a propagation direction within the waveguide matrix with respect to the original propagation direction.

12. A near-eye display device comprising the light guide device of any one of claims 1-11.

Technical Field

The invention relates to the technical field of optical devices, in particular to an optical waveguide device. The invention also relates to a near-eye display device.

Background

The near-to-eye display equipment is equipment for realizing augmented reality display, is not different from common glasses in a common wearing mode, and is characterized by being capable of transmitting light rays emitted by real world objects and also capable of enabling light rays of virtual images to enter human eyes.

The imaging system of the near-eye display device comprises an optical-mechanical system and an optical waveguide, wherein the optical-mechanical system is a micro projector or a screen and is responsible for converting an electric signal into an optical signal and outputting a virtual image; the optical waveguide is responsible for transmitting the output virtual image light to the position in front of the human eyes, and the light enters the human eyes to realize virtual image imaging.

The light propagates along the optical waveguide by total reflection at the optical waveguide interface, wherein the propagation step of the light beam represents the distance between the incident positions of two adjacent total reflections of the light beam on the same interface of the optical waveguide. In practical scenarios, different light beams traveling within the optical waveguide will produce different propagation steps due to different angles of incidence of the light or different wavelengths of the light. Referring to FIG. 1, the light 102 propagating in the optical waveguide 100 has a propagation step d₁The propagation step of the light ray 103 is d₂Propagation step length d₁Less than the propagation step d₂. When light propagates to the outcoupling region 101, the light is diffracted, and when the light propagates forward, a part of the light is coupled out of the optical waveguide 100, and the distance between the light outcoupling positions is the same as the propagation step length of the light beam in the optical waveguide 100. As shown in fig. 1, the light 102 has a shorter propagation step, so the coupled light is more dense, and similarly, the light 103 has a longer propagation step, so the coupled light is less dense. If the relative positions of the eye 104 and the coupling-out region 101 are fixed, for example, as in the case shown in fig. 1, the entrance pupil range of the eye 104 is fixed, so that more closely spaced light rays 102 enter the eye 104 (2 beams in the figure), and less closely spaced light rays 103 are received by the eye 104 (1 beam in the figure). The brightness of light imaged by human eyes is the superposition of the brightness of a plurality of beams of light received by human eyes, so that in a virtual image formed by human eyes, an image formed by the light 102 is brighter, and an image formed by the light 103 is darker.

That is, the position of the human eye relative to the optical waveguide is fixed, and the brightness of the image formed by the light beams with different propagation step lengths is different, which may cause distortion of the virtual image information acquired by the human eye, for example, the virtual image information is directly reflected in the virtual image imaging effect received by the human eye in the forms of "dark band", "image brightness distortion", and the like, which greatly restricts the practical use of the optical waveguide scheme.

Disclosure of Invention

The invention aims to provide an optical waveguide device which can improve the situation that the image information is distorted in the existing optical waveguide scheme. The invention also provides a near-eye display device.

In order to achieve the purpose, the invention provides the following technical scheme:

an optical waveguide device comprising a waveguide body and a first optical element for diffracting a light beam propagating within the waveguide body to cause a change in the propagation form of at least a portion of the light beam;

the first optical element comprises unit structures which are arranged periodically, and the preset parameters of the unit structures are changed along with the positions of the unit structures, so that the energy sum of the transmission form change parts of the light beams with the larger transmission step length at each position in the same range is consistent with the energy sum of the transmission form change parts of the light beams with the smaller transmission step length at each position in the same range.

Preferably, the preset parameters of the unit structure include a groove depth of the unit structure, an inclination angle of a side surface of the unit structure with respect to a normal direction of the waveguide substrate surface, a lateral dimension of the unit structure, or a refractive index of the unit structure.

Preferably, the preset parameters of the unit structure are changed along with the position of the unit structure along the one-dimensional direction, so that the sum of the energy of the part of the light beam with the larger propagation step length, which is changed in propagation form at each position in the same range along the one-dimensional direction, and the sum of the energy of the part of the light beam with the smaller propagation step length, which is changed in propagation form at each position in the same range along the one-dimensional direction tend to be consistent.

Preferably, the first optical element includes unit structure groups arranged in sequence, the unit structure groups include unit structures arranged periodically, and the length of the unit structure group along the transmission direction of the light beam in the waveguide substrate is matched with the maximum propagation step length of the light beam propagating in the waveguide substrate.

Preferably, a change form of the preset parameters of the unit structures of one group of unit structure groups along the one-dimensional direction is a linear change, or a change form of the preset parameters of the unit structures of one group of unit structure groups along the one-dimensional direction is a step change, or the preset parameters of the unit structures of one group of unit structure groups and the positions of the unit structures along the one-dimensional direction satisfy an arc function relationship.

Preferably, as the transmission distance of the light beam in the waveguide substrate is extended, the diffraction efficiency of each unit structure of the latter unit structure group on the light beam is greater than the diffraction efficiency of the unit structure at the corresponding position in the former unit structure group on the light beam with the same wavelength.

Preferably, the preset parameters of the unit structure are changed along with the position of the unit structure along the first dimension direction, so that the energy sum of the propagation form change parts of the light beam with the larger propagation step at each position in the same range along the first dimension direction is consistent with the energy sum of the propagation form change parts of the light beam with the smaller propagation step at each position in the same range along the first dimension direction;

the preset parameters of the unit structure are changed along with the position of the unit structure along the second dimension direction, so that the energy sum of the transmission form change parts of the light beam with the larger transmission step length at each position in the same range along the second dimension direction is consistent with the energy sum of the transmission form change parts of the light beam with the smaller transmission step length at each position in the same range along the second dimension direction.

Preferably, the optical device further comprises a second optical element, the light beam transmitted to the first optical element comes from the second optical element, the first dimension direction is parallel to a direction in which the second optical element points to the first optical element, and an included angle between the second dimension direction and the first dimension direction is greater than zero degrees.

Preferably, the optical device further comprises a second optical element, the light beam transmitted to the first optical element comes from the second optical element, the unit structure of the first optical element is symmetrical to a preset boundary on the first optical element, and the preset boundary is a central axis of the first optical element parallel to the direction in which the second optical element points to the first optical element.

Preferably, the preset parameters of the unit structures include groove depths of the unit structures, and tops of the unit structures of the first optical element are equal to each other, or bottoms of the unit structures of the first optical element are equal to each other.

Preferably, the first optical element is specifically configured to diffract the light beam propagating in the waveguide substrate to couple at least a portion of the light beam out of the waveguide substrate, or the first optical element is specifically configured to diffract the light beam propagating in the waveguide substrate to deflect a transmission direction of at least a portion of the light beam in the waveguide substrate with respect to an original transmission direction.

A near-eye display device comprising the optical waveguide device described above.

As can be seen from the above technical solutions, an optical waveguide device provided by the present invention includes a waveguide substrate and a first optical element, where the first optical element diffracts a light beam propagating in the waveguide substrate to change at least a part of a propagation form of the light beam. The first optical element comprises unit structures which are periodically arranged, preset parameters of the unit structures are changed along with the positions of the unit structures, the energy sum of the transmission form change parts of the light beams with larger transmission step lengths at all positions in the same range can be enabled to be approximately consistent with the energy sum of the transmission form change parts of the light beams with smaller transmission step lengths at all positions in the same range, and the condition that image information distortion exists due to the fact that coupling-out energy of the light beams with different transmission step lengths in the optical waveguide in the existing optical waveguide scheme can be improved.

The near-eye display equipment provided by the invention can achieve the beneficial effects.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a schematic illustration of light propagation for a prior art optical waveguide scheme;

FIG. 2 is a schematic diagram of an optical waveguide device according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of an optical waveguide device according to yet another embodiment of the present invention;

FIG. 4 is a schematic diagram of an optical waveguide device according to yet another embodiment of the present invention;

FIG. 5 is a schematic diagram of an optical waveguide device according to yet another embodiment of the present invention;

FIG. 6 is a schematic diagram of an optical waveguide device according to yet another embodiment of the present invention;

fig. 7(a) is a cross-sectional view of an optical waveguide device provided in accordance with yet another embodiment of the present invention, taken along direction 1;

FIG. 7(b) is a cross-sectional view of the optical waveguide device shown in FIG. 7(a) taken along direction 2;

FIGS. 8(a) and 8(b) are schematic diagrams illustrating propagation of light beams of different wavelengths through the optical waveguide devices shown in FIGS. 7(a) and 7(b), respectively;

FIGS. 9(a) and 9(b) are schematic diagrams illustrating propagation of light beams with different incident angles through the optical waveguide device shown in FIGS. 7(a) and 7(b), respectively;

FIG. 10 is a schematic diagram of an optical waveguide device provided in accordance with yet another embodiment of the present invention;

FIG. 11 is a schematic diagram of an optical waveguide device according to yet another embodiment of the present invention;

fig. 12 is a schematic diagram of an optical waveguide device according to yet another embodiment of the present invention.

Detailed Description

In order to make those skilled in the art better understand the technical solution of the present invention, the technical solution in the embodiment of the present invention will be clearly and completely described below with reference to the drawings in the embodiment of the present invention, and it is obvious that the described embodiment is only a part of the embodiment of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The embodiment of the invention provides an optical waveguide device, which comprises a waveguide substrate and a first optical element, wherein the first optical element is used for diffracting a light beam propagating in the waveguide substrate so as to change at least one part of the propagation form of the light beam;

the first optical element comprises unit structures which are arranged periodically, the preset parameters of the unit structures are changed along with the positions of the unit structures, so that the sum of the energy of the transmission form change parts of the light beams with the larger transmission step size at each position in the same range is consistent with the sum of the energy of the transmission form change parts of the light beams with the smaller transmission step size at each position in the same range, namely, the difference between the sum of the energy of the transmission form change parts of the light beams with the larger transmission step size at each position in the same range and the sum of the energy of the transmission form change parts of the light beams with the smaller transmission step size at each position in the same range is reduced.

The first optical element includes a unit structure arranged periodically so that a light beam is diffracted when it is incident on the first optical element, and a light beam transmitted in a total reflection form within the waveguide substrate is diffracted when it passes through the first optical element so that a propagation form of at least a part of the light beam is changed.

The propagation step of the light beam refers to the distance between the incident positions of two adjacent total reflections of the light beam on the same interface of the waveguide substrate. The preset parameters of the unit structure can influence the diffraction efficiency of the light beam incident to the unit structure to be diffracted. The diffraction efficiency refers to the ratio of the energy of the part of the beam which changes in propagation form after undergoing one diffraction to the energy of the beam before diffraction.

The preset parameters of the unit structures arranged on the first optical element change along with the positions of the unit structures, so that the diffraction efficiency of the unit structures at different positions where light beams enter are different in diffraction. And in particular, the unit structure of the first optical element arrangement enables the energy sum of the propagation form change parts of the light beam with the larger propagation step length at each diffraction position in the same range to be consistent with the energy sum of the propagation form change parts of the light beam with the smaller propagation step length at each diffraction position in the same range.

Therefore, compared with the existing optical waveguide scheme, the optical waveguide device of the embodiment can improve the situation that the image information is distorted due to the uneven coupling energy of the light beams with different propagation steps in the optical waveguide in the existing optical waveguide scheme.

Alternatively, the predetermined parameter of the cell structure may be a geometric parameter of the cell structure, including but not limited to a groove depth of the cell structure, an inclination angle of a side surface of the cell structure with respect to a normal direction of a surface of the waveguide substrate, or a lateral dimension of the cell structure. Alternatively, the predetermined parameter of the cell structure may be an optical parameter of the cell structure, including but not limited to the refractive index of the cell structure.

Illustratively, the larger the groove depth of the cell structure, the higher the diffraction efficiency of the light beam, and the smaller the groove depth of the cell structure, the lower the diffraction efficiency of the light beam. The larger the inclination angle of the unit structure, the higher the diffraction efficiency for the light beam, and the smaller the inclination angle of the unit structure, the lower the diffraction efficiency for the light beam.

Alternatively, the unit structures arranged on the first optical element may be unit structures periodically arranged along a one-dimensional direction, or the unit structures arranged on the first optical element may also be unit structures periodically arranged along two dimensional directions at the same time.

Referring to fig. 2, fig. 2 is a schematic diagram of an optical waveguide device according to an embodiment, in which a light beam transmitted along a waveguide substrate 200 reaches a first optical element 201, and diffraction occurs in the first optical element 201, so that a part of energy of the light beam is coupled out of the waveguide substrate 200. The propagation step of beam 203 is smaller than the propagation step of beam 204, the diffraction positions of beam 203 are denser and the diffraction positions of beam 204 are sparser. As shown in the figure, the groove depth of the unit structure 202 at the incident position of the light beam 204 on the first optical element 201 is greater than the groove depth of the unit structure 202 at the incident position of the light beam 203, so that the diffraction efficiency of the light beam 204 is greater than that of the light beam 203, and the energy coupled out by the light beam 204 through one-time diffraction is relatively more, so that the energy of the light beam 204 and the energy of the light beam 203 coupled out from the waveguide substrate 200 in the same range tend to be uniform.

In the optical waveguide device shown in fig. 2, two light beams with different propagation steps in the waveguide substrate are taken as an example for illustration, in practical application, the light beams transmitted along the waveguide substrate will form a greater number of light beams with different propagation steps to propagate along the waveguide substrate, and the corresponding groove depth variation form of the periodic unit structure on the first optical element is designed according to the propagation conditions of the light beams with different propagation steps in the waveguide substrate.

In one embodiment, the predetermined parameter of the unit structure varies with the position of the unit structure along a one-dimensional direction, so that the sum of the energies of the portions of the beam with the larger propagation step propagating at the respective positions within the same range along the one-dimensional direction tends to coincide with the sum of the energies of the portions of the beam with the smaller propagation step propagating at the respective positions within the same range along the one-dimensional direction.

Referring to fig. 3, fig. 3 is a schematic diagram of an optical waveguide device according to another embodiment, wherein a light beam transmitted along a waveguide substrate 200 reaches a first optical element 201, and is diffracted at the first optical element 201 to couple a part of energy of the light beam out of the waveguide substrate 200. Light beams 203 and 204 with different propagation steps propagate in the waveguide substrate 200 in direction 1. Wherein, the groove depth of the unit structure 205 on the first optical element 201 varies with the position of the unit structure 205 along the direction 1, as shown in fig. 3, in the range of the unit structure 205 arranged as shown in fig. 3, the groove depth of the diffraction position of the light beam 204 is larger, so that the diffraction efficiency of the light beam 204 undergoing primary diffraction is high; while the diffraction positions of the light beam 203 with a smaller propagation step have a smaller groove depth, and the diffraction efficiency of the first diffraction is lower, but the diffraction positions of the light beam 203 are denser, so that the energy of the light beam 204 and the light beam 203 coupled out of the waveguide substrate 200 in the same range along the direction 1 tends to be uniform.

Optionally, the variation form of the unit structure groove depth along the one-dimensional direction may be linear variation, the groove depth of each unit structure and the position of the unit structure along the one-dimensional direction satisfy a linear relationship, and the groove depth of each unit structure is different along with the difference of the position of the unit structure along the one-dimensional direction.

Optionally, the change form of the unit structure groove depth along the one-dimensional direction may also be a step change, and the change of the unit structure groove depth along the one-dimensional direction of the unit structure is in a step shape. For example, in the optical waveguide device shown in fig. 3, the first optical element 201 is grouped into two unit structures 205 along the direction 1, the groove depths of the unit structures 205 of the same group are the same, and the groove depths of the unit structures 205 of each group are gradually increased along the direction 1.

Alternatively, the variation of the unit structure groove depth along the one-dimensional direction may also be such that the unit structure groove depth and the unit structure position along the one-dimensional direction satisfy an arc function relationship, such as shown with reference to fig. 4 or fig. 5. In addition, in practical application, the variation form of the groove depth of the periodic unit structure on the first optical element along the one-dimensional direction is not limited to the above-mentioned several forms, and other variations can also be adopted, and are also within the protection scope of the present invention.

In addition, the top of each unit structure of the first optical element may be designed to be flat, for example, as shown in fig. 5, the top of each unit structure of the first optical element 201 fabricated on the waveguide substrate 200 is flat. Or the bottom of each cell structure groove of the first optical element may be designed to be flat. For example, as shown in fig. 4, the bottom of each unit structure groove of the first optical element 201 formed on the waveguide substrate 200 is flat.

In a preferred embodiment, the first optical element includes a unit structure group arranged in sequence, the unit structure group includes the unit structures arranged periodically, and the length of the unit structure group along the light beam transmission direction in the waveguide matrix is matched with the maximum propagation step length of the light beam propagating in the waveguide matrix. The matching of the length of the unit structure group and the maximum propagation step length of the light beam propagating in the waveguide substrate means that the length of the unit structure group is set according to the maximum propagation step length of the light beam propagating in the waveguide substrate.

For example, the length of the unit structure group along the transmission direction of the light beam in the waveguide substrate is set to be consistent with the maximum propagation step length of the light beam propagating in the waveguide substrate or to be slightly greater than the maximum propagation step length of the light beam propagating in the waveguide substrate, and under the structural design, the periodic unit structure of the first optical element is divided into groups along the transmission direction of the light beam in the waveguide substrate by taking the maximum propagation step length in the transmitted light beam as a period, and the diffraction efficiency of the transmitted light beam with different propagation step lengths is modulated by taking the unit structure group as a modulation period.

The change rule of the unit structure preset parameters of each unit structure group along the light beam transmission direction in the waveguide matrix is preferably the same. But the design is more flexible, and the change rules of the preset parameters of the unit structures of each unit structure group along the transmission direction of the light beam in the waveguide matrix can also be different.

Alternatively, the variation form of the preset parameters of the unit structures of one unit structure group along the one-dimensional direction may be a linear variation. Referring to fig. 6, fig. 6 is a schematic diagram of an optical waveguide device according to yet another embodiment, in which a first optical element 301 diffracts a light beam propagating in a waveguide matrix 300 to change at least a portion of a propagation form of the light beam. The propagation step of beam 304 is the maximum propagation step in each beam propagating along waveguide matrix 300. As shown, the first optical element 301 includes a unit structure group 302 arranged in sequence, and the length of the unit structure group 302 along the direction 1 is consistent with the propagation step of the light beam 304. The unit structure groove depth of the unit structure group 302 and the position of the unit structure along the direction 1 satisfy a linear relationship, and the unit structure groove depth is different according to the position of the unit structure along the direction 1.

In the cell structure groove depth distribution shown in fig. 6, since the period of change of the cell structure groove depth matches the beam having a large propagation step, the beam 304 having a large propagation step can always diffract at a position having a large groove depth, while the beam 303 having a small propagation step diffracts at a position having a small groove depth in most cases because the propagation step does not match the period of the cell structure group, and the diffraction efficiency of one-time diffraction is low. Thus, the coupled-out energy of the sparsely distributed light beams 304 is stronger, the coupled-out energy of the densely distributed light beams 303 is weaker, and after the specific groove depth variation parameters are designed according to the material parameters, brightness unevenness caused by density in the same range and brightness unevenness caused by light intensity difference at the primary diffraction position can be mutually complemented and offset, so that the effect of uniform brightness is achieved.

In the first optical element shown in fig. 6, the variation of the cell structures of the respective cell structure groups 302 in the direction 1 is the same, and the variation of the cell structures of the respective cell structure groups in the direction 1 may be different in other embodiments.

Optionally, the change form of the preset parameter of the unit structure of one unit structure group along the one-dimensional direction may also be a step change. The preset parameters of each unit structure are in a step shape along with the position change of the unit structure along the one-dimensional direction. In addition, the variation form of the preset parameters of the unit structures of one group of unit structure groups along the one-dimensional direction can also be that the preset parameters of the unit structures and the positions of the unit structures along the one-dimensional direction meet the arc function relationship, and the invention also belongs to the protection scope of the invention.

The unit structures of the unit structure groups may be unit structures periodically arranged along a one-dimensional direction, or the unit structures of the unit structure groups may be unit structures periodically arranged along two dimensional directions at the same time.

Preferably, in one embodiment, the preset parameters of the periodic unit structures on the first optical element are changed in two dimensional directions, wherein the preset parameters of the unit structures are changed along with the positions of the unit structures along the first dimensional direction, so that the sum of the energies of the parts, with changed propagation forms, of the light beams with larger propagation step sizes at all positions in the same range along the first dimensional direction is consistent with the sum of the energies of the parts, with changed propagation forms, of the light beams with smaller propagation step sizes at all positions in the same range along the first dimensional direction; the preset parameters of the unit structure are changed along with the position of the unit structure along the second dimension direction, so that the energy sum of the propagation form change parts of the light beam with the larger propagation step length at each position in the same range along the second dimension direction is consistent with the energy sum of the propagation form change parts of the light beam with the smaller propagation step length at each position in the same range along the second dimension direction.

In this embodiment, the preset parameters of the periodic unit structure on the first optical element are changed in two dimensions, and the first optical element can modulate the diffraction efficiency of each light beam with different propagation step lengths in the waveguide substrate in the two dimensions, so that the energy of the changed part of each light beam propagation form with different propagation step lengths in the same range tends to be uniform in a two-dimensional plane.

In this embodiment, a change rule of the preset parameter of the unit structure along the first dimension direction may be consistent with a change rule of the preset parameter of the unit structure along the second dimension direction. Or the change rule of the preset parameters of the unit structure along the first dimension direction can be different from the change rule of the preset parameters of the unit structure along the second dimension direction, and the change rule can be set according to the application requirements of the optical waveguide device in practical application.

Illustratively, referring to fig. 7(a) and 7(b), fig. 7(a) is a cross-sectional view of an optical waveguide device along a direction 1 according to yet another embodiment, and fig. 7(b) is a cross-sectional view of the optical waveguide device along a direction 2 shown in fig. 7(a), wherein the direction 1 and the direction 2 are perpendicular to each other.

As can be seen from fig. 7(a), the first optical element 401 includes a plurality of unit structure groups 402 arranged along the direction 1, the unit structure groups 402 include unit structures arranged periodically, and the unit structure groove depth within one unit structure group 402 varies with the position of the unit structure along the direction 1. As can be seen from fig. 7(b), the first optical element 401 includes a plurality of unit structure groups 403 arranged along the direction 2, the unit structure groups 403 include unit structures arranged periodically, and the unit structure groove depth of each unit structure group 403 varies with the position of the unit structure along the direction 2. As can be seen from fig. 7(a) and 7(b), the variation of the groove depth of the periodic cell structure in the direction 1 on the first optical element 401 is different from the variation of the groove depth of the cell structure in the direction 2.

For example, please refer to fig. 8(a) and 8(b), fig. 8(a) and 8(b) are schematic diagrams illustrating the propagation of light beams with different wavelengths through the optical waveguide devices shown in fig. 7(a) and 7(b), respectively. A second optical element 404 and a first optical element 401 are provided on the waveguide base 400. The light beam 410 and the light beam 411 have different wavelengths, and the two light beams are incident on the second optical element 404 at the same incident angle. The second optical element 404 diffracts the light beam to couple at least a portion of the light beam into the waveguide matrix 400. The two beams propagate in different steps in the waveguide matrix 400 due to the different wavelengths of the beams 410 and 411.

As shown in fig. 8(a), the light beam 410 and the light beam 411 entering the waveguide substrate 400 propagate to the first optical element 401 through total reflection, and the light beam 410 and the light beam 411 respectively enter different positions of the first optical element 401 to be diffracted and respectively couple out light rays to the waveguide substrate 400. As shown in fig. 8(b), the light beam 410 and the light beam 411 entering the waveguide substrate 400 propagate to the first optical element 401, and the light beam 410 and the light beam 411 respectively propagate from the middle portion to both sides of the first optical element 401. The optical waveguide device can improve the condition that the coupled-out energy of beams with different wavelengths in the existing optical waveguide scheme is not uniform, so that the image color is distorted.

For example, please refer to fig. 9(a) and 9(b), fig. 9(a) and 9(b) are schematic diagrams illustrating propagation of light beams with different incident angles through the optical waveguide device shown in fig. 7(a) and 7(b), respectively. A second optical element 404 and a first optical element 401 are provided on the waveguide base 400. The beams 412 and 413 have the same wavelength, but the beams are incident on the second optical element 404 at different angles of incidence. The second optical element 404 diffracts the light beam to couple at least a portion of the light beam into the waveguide matrix 400. Since the incident angles of the light beams 412 and 413 are different, the diffraction angles of the two light beams entering the waveguide substrate 400 are different, so that the propagation step size for total reflection in the waveguide substrate 400 is different.

As shown in fig. 9(a), the light beam 412 and the light beam 413 entering the waveguide substrate 400 propagate to the first optical element 401 through total reflection, the light beam 412 and the light beam 413 are respectively incident to different positions of the first optical element 401 and are diffracted, and are respectively coupled out of the waveguide substrate 400, and due to different groove depths of the unit structures at the positions, the diffraction efficiencies of the light beam 412 and the light beam 413 are different. As shown in fig. 9(b), the light beams 412 and 413 entering the waveguide substrate 400 propagate to the first optical element 401, and the light beams 412 and 413 respectively propagate from the middle portion to both sides of the first optical element 401. Therefore, the optical waveguide device can be applied to the situation that the coupled-out energy of the light beams with different incident angles in the existing optical waveguide scheme is not uniform, so that the image information is distorted.

Preferably, in practical applications, the optical waveguide device further includes a second optical element, the light beam transmitted to the first optical element comes from the second optical element, the first dimension direction is parallel to a direction in which the second optical element points to the first optical element, and an included angle between the second dimension direction and the first dimension direction is greater than zero degrees.

Referring to fig. 10, fig. 10 is a top view of an optical waveguide device according to yet another embodiment, which includes a waveguide substrate 400, a second optical element 404 and a first optical element 401, wherein the second optical element 404 is used for coupling a light beam into the waveguide substrate 400, and the first optical element 401 diffracts the light beam to couple a part of energy of the light beam out of the waveguide substrate 400. The first dimension direction 1 is parallel to a direction in which the second optical element 404 points to the first optical element 401, an included angle between the second dimension direction 2 and the first dimension direction 1 is greater than zero degrees, for example, an included angle between the second dimension direction 2 and the first dimension direction 1 may be 90 degrees.

Alternatively, in other embodiments, the first optical element may be a diffractive optical element for diffracting a propagating light beam within the waveguide substrate to couple at least a portion of the light beam out of the waveguide substrate, and the second optical element may be a diffractive optical element for diffracting a propagating light beam within the waveguide substrate to deflect a propagation direction of at least a portion of the light beam within the waveguide substrate relative to the original propagation direction.

In one embodiment, the optical waveguide device further includes a second optical element from which the light beam transmitted to the first optical element comes, and the unit structure of the first optical element is symmetrical about a predetermined boundary on the first optical element, where the predetermined boundary is a central axis of the first optical element parallel to a direction in which the second optical element points to the first optical element.

Therefore, the light beam transmitted from the second optical element to the first optical element through the waveguide substrate is symmetrically transmitted due to the symmetrical distribution of the unit structures arranged on the first optical element along the central axis, and the diffraction positions of the light beam on the first optical element are symmetrically distributed during the transmission through the first optical element. Helping to homogenize the energy of the varying form of propagation of the regions of the first optical element.

Referring to fig. 10, the unit structure of the first optical element 401 may be symmetrical about a central axis 405 of the first optical element 401, and the central axis 405 is parallel to a direction in which the second optical element 404 points to the first optical element 401.

In the above embodiments, the first optical element may be a diffractive optical element for coupling at least a part of the light beam out of the waveguide substrate, and in this case, the second optical element may be a diffractive optical element for coupling the light beam into the waveguide substrate, or the second optical element may be a diffractive optical element for diffracting the light beam propagating in the waveguide substrate to deflect the propagation direction of at least a part of the light beam in the waveguide substrate from the original propagation direction.

Alternatively, the first optical element may be a diffractive optical element which diffracts the light beam propagating in the waveguide substrate so that the propagation direction of at least a part of the light beam in the waveguide substrate is deflected with respect to the original propagation direction. In this case, the second optical element may be a diffractive optical element for coupling the light beam into the waveguide matrix.

The light beams transmitted along the waveguide substrate can generate light beams with different propagation step lengths due to different wavelengths, or the light beams with different propagation step lengths can be generated due to different incident angles coupled into the waveguide substrate, so that the optical waveguide device can improve the condition that the coupled-out energy of the light beams with different wavelengths in the existing optical waveguide scheme is not uniform, which causes image color distortion, and can also be applied to improve the condition that the coupled-out energy of the light beams with different incident angles in the existing optical waveguide scheme is not uniform, which causes image information distortion.

Preferably, in an embodiment, the first optical element includes unit structure groups arranged in sequence, the unit structure groups include unit structures arranged periodically, the length of the unit structure group along the transmission direction of the light beam in the waveguide matrix is matched with the maximum propagation step length of the light beam propagating in the waveguide matrix, and along with the extension of the transmission distance of the light beam in the waveguide matrix, the diffraction efficiency of each unit structure of the latter unit structure group on the light beam is greater than the diffraction efficiency of the unit structure at the corresponding position in the former unit structure group on the light beam with the same wavelength.

Referring to fig. 11, fig. 11 is a schematic diagram of an optical waveguide device according to another embodiment, in which a first optical element 501 includes a unit structure group 502, a unit structure group 503, and a unit structure group 504, and a length of each unit structure group along a direction 1 is consistent with a maximum propagation wavelength of a transmission beam in a waveguide matrix 500. The unit structure groove depths of the unit structure group 504, the unit structure group 503 and the unit structure group 502 are sequentially increased by a fixed value, the unit structure groove depth of each unit structure group 504 is greater than the unit structure groove depth of the corresponding position in the unit structure group 503, and the unit structure groove depth of each unit structure group 503 is greater than the unit structure groove depth of the corresponding position in the unit structure group 502. Thus, as the transmission distance of the light beams in the waveguide substrate 500 is increased, although the energy of each light beam is reduced, the depth of the unit structure groove is increased, so that the diffraction efficiency of each light beam is increased, which compensates for the reduction of brightness caused by diffraction loss in light propagation in the direction, and makes the diffraction brightness at different positions in the direction more uniform. In each unit structure group, the groove depth of the unit structure changes along with the position of the unit structure, so that the energy sum of the parts, with the larger propagation step length, of the light beam, which are changed in propagation form at each position in the same range along the direction 1 tends to be consistent with the energy sum of the parts, with the smaller propagation step length, of the light beam, which are changed in propagation form at each position in the same range along the direction 1. Therefore, the optical waveguide device can simultaneously improve the uniformity of the imaging brightness at different positions and the uniformity of the imaging brightness of light beams with different wavelengths, or can simultaneously improve the uniformity of the imaging brightness at different positions and the uniformity of the imaging brightness at different incidence angles.

In addition, in the above embodiments, the groove depth of the unit structure is changed and designed as an example, in other embodiments, the diffraction efficiency of the light beam at different positions modulated by the first optical element can be realized by changing and designing other parameters of the unit structure, and the effect that the energy of the changed part of the light beam propagation form with different propagation steps in the same range tends to be uniform is achieved, and the invention is also within the protection scope of the present invention.

Referring to fig. 12, fig. 12 is a schematic diagram of an optical waveguide device according to another embodiment, wherein a light beam transmitted along a waveguide substrate 600 reaches a first optical element 601, and diffraction occurs in the first optical element 601 to couple a part of energy of the light beam out of the waveguide substrate 600. The propagation step of beam 603 is smaller than the propagation step of beam 604. As shown in the figure, the inclination angle of the unit structure 602 at the incident position of the light beam 604 on the first optical element 601 is greater than the inclination angle of the unit structure 602 at the incident position of the light beam 603, so that the diffraction efficiency of the light beam 604 in the first diffraction is greater than that of the light beam 603, and although the diffraction positions of the light beam 603 are denser and the diffraction positions of the light beam 604 are sparser, the energy coupled out by the light beam 604 in the first diffraction is relatively more, and the energy of the light beam 604 and the energy of the light beam 603 coupled out from the waveguide substrate 600 in the same range can be made uniform.

The embodiment of the invention also provides near-eye display equipment which comprises the optical waveguide device.

The near-eye display device of the present embodiment employs an optical waveguide device in which a first optical element diffracts a light beam propagating in a waveguide substrate to change at least a part of a propagation form of the light beam. The first optical element comprises unit structures which are periodically arranged, preset parameters of the unit structures are changed along with the positions of the unit structures, the energy sum of the transmission form change parts of the light beams with larger transmission step lengths at all positions in the same range can be enabled to be approximately consistent with the energy sum of the transmission form change parts of the light beams with smaller transmission step lengths at all positions in the same range, and the condition that image information distortion exists due to the fact that coupling-out energy of the light beams with different transmission step lengths in the optical waveguide in the existing optical waveguide scheme can be improved.

The optical waveguide device and the near-eye display apparatus provided by the present invention are described in detail above. The principles and embodiments of the present invention are explained herein using specific examples, which are presented only to assist in understanding the method and its core concepts. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.