Diffractive waveguide beam density control device based on birefringence effect

Abstract

The utility model relates to a kind of diffraction waveguide light beam density regulation and control devices based on birefringence effect.The diffraction waveguide light beam density regulation and control devices based on birefringence effect include: waveguide substrate, made of material with birefringence effect;Coupling-in port, set in the incident plane of waveguide substrate, for coupling incident light;Coupling-out port, set in the exit plane of waveguide substrate, for coupling transmission light;Temperature regulation module, set in the side of waveguide substrate, for controlling the temperature of waveguide substrate, adjusting the propagation path of TE mode incident light and TM mode incident light inside waveguide substrate.The above-mentioned device utilizes the different diffraction angles of TE mode incident light and TM mode incident light due to different refractive indices, increases the propagation path width of light inside waveguide substrate, and improves the beam transmission density.Meanwhile, the temperature of waveguide substrate can be accurately controlled by temperature regulation module, to realize dark area distribution programmable and beam density dynamic optimization.

Description

Technical Field

[0001] This utility model relates to the field of augmented reality display technology, and in particular to a diffraction waveguide beam density control device based on birefringence effect. Background Technology

[0002] With the rapid development of augmented reality technology, diffractive waveguides have attracted widespread attention as a thin and compact display solution. Diffractive waveguides utilize the principle of total internal reflection within the waveguide to transmit light by setting structures such as coupling gratings and output gratings on the waveguide substrate. This projects virtual information into the viewer's eye, blending it with the real environment to achieve an augmented reality effect. However, existing diffractive waveguides have shortcomings in beam transmission density and dark area distribution, affecting the uniformity and clarity of the displayed image.

[0003] Specifically, please see Figure 1 Traditional optical waveguide 100' includes a waveguide substrate 110' with a refractive index of n' and a beam width of w'. During light propagation, due to the limitation of the thickness h' of the waveguide substrate 110', the primary and secondary total internal reflections may not be completely tightly fitted, leading to the appearance of a dark area A'. This dark area affects the uniformity of light intensity distribution in the coupling region, reducing the display experience. To reduce the dark area, designers typically increase the beam width, decrease the waveguide thickness, or increase the waveguide refractive index. However, these methods suffer from drawbacks such as wasted light energy and limited control amplitude, making it difficult to fundamentally solve the problem. Utility Model Content

[0004] Therefore, it is necessary to provide a diffraction waveguide beam density control device based on birefringence effect to address the problem of how to improve beam transmission density to optimize display effect.

[0005] A diffraction waveguide beam density control device based on birefringence effect, comprising:

[0006] The waveguide substrate is made of a material with birefringence effect, and incident light is naturally separated into TE mode and TM mode when it enters the waveguide substrate.

[0007] The coupling port is located on the incident surface of the waveguide substrate and is used to couple incident light.

[0008] A coupling port, disposed on the exit surface of the waveguide substrate, is used for coupling and guiding light; and

[0009] A temperature control module is disposed on one side of the waveguide substrate and is used to control the temperature of the waveguide substrate and adjust the propagation path of the incident light in TE mode and TM mode inside the waveguide substrate.

[0010] This invention discloses a diffraction waveguide beam density control device based on birefringence. It utilizes the different diffraction angles produced by the different refractive indices of TE and TM mode incident light, thereby increasing the propagation path width of the incident light within the waveguide substrate and improving beam density. Simultaneously, the temperature of the waveguide substrate can be precisely controlled via a temperature control module, altering the propagation paths of TE and TM mode incident light within the waveguide substrate, enabling programmable dark area distribution and dynamic optimization of beam density. Therefore, it can improve beam density and optimize display performance.

[0011] In one embodiment, the temperature control module has a temperature control range of 20℃ to 80℃ and a resolution of 0.1℃. The temperature control module includes:

[0012] A heating element for heating the waveguide substrate;

[0013] A temperature sensor is used to detect the real-time temperature of the waveguide substrate; and

[0014] The control circuit, based on the feedback signal from the temperature sensor, precisely controls the heating element to achieve dynamic adjustment of the waveguide substrate temperature.

[0015] In one embodiment, the temperature control module is a non-uniform temperature field construction module, used to construct a spatial temperature gradient on the waveguide substrate to achieve regional birefringence control. The non-uniform temperature field construction module includes multiple independently controllable heating units.

[0016] In one embodiment, an electric field control module is also included for applying an electric field to the waveguide substrate.

[0017] In one embodiment, the electric field control module includes a power supply and an electrode pair, the electrode pair being disposed on both sides or the same side of the waveguide substrate.

[0018] In one embodiment, a machine learning optimization system is also included, the machine learning optimization system comprising:

[0019] An ambient light sensor is used to detect the intensity of ambient light.

[0020] The image feedback module is used to acquire image information of the user's eyes;

[0021] The deep neural network model, based on the input information from the ambient light sensor and the image feedback module, combined with the data from the temperature sensor, outputs the target temperature distribution and voltage setting;

[0022] The control module, based on the output of the deep neural network model, performs integrated control of the temperature regulation module and the electric field control module.

[0023] In one embodiment, the waveguide substrate is a lithium niobate waveguide substrate, a quartz waveguide substrate, a calcite waveguide substrate, or a sodium thiosulfate waveguide substrate.

[0024] In one embodiment, the thickness of the waveguide substrate is 0.5 mm to 4 mm.

[0025] In one embodiment, the coupling port is a surface relief grating or a volume holographic grating with a period range of 200nm to 800nm.

[0026] In one embodiment, the output port is a two-dimensional grating pupil or a one-dimensional grating pupil with a period range of 200nm~800nm. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of a traditional optical waveguide;

[0028] Figure 2 This is a schematic diagram of a diffraction waveguide beam density control device based on birefringence effect according to one embodiment of the present invention.

[0029] Figure 3 This is a schematic diagram of a diffraction waveguide beam density control device based on birefringence effect, according to another embodiment of the present invention.

[0030] Figure 4 This is a schematic diagram of a diffraction waveguide beam density control device based on birefringence effect, according to another embodiment of the present invention.

[0031] Figure 5 This is a flowchart of a method for controlling the beam density of a diffractive waveguide based on the birefringence effect according to one embodiment of the present invention.

[0032] Figure 6 This is a flowchart of another embodiment of the present invention, which describes a method for controlling the beam density of a diffractive waveguide based on the birefringence effect. Detailed Implementation

[0033] To make the above-mentioned objects, features, and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a full understanding of this utility model. However, this utility model can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this utility model. Therefore, this utility model is not limited to the specific embodiments disclosed below.

[0034] It should be noted that when a component is said to be "fixed to" another component, it can be directly attached to the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0036] Please see Figure 2 The diffraction waveguide beam density control device 100 based on birefringence effect according to one embodiment of the present invention includes a waveguide substrate 110, an input port 120, an output port 130, and a temperature control module 140. In the figure, the arrow above the input port 120 indicates the irradiation direction of the incident light, and the arrow above the output port 130 indicates the output direction of the emitted light.

[0037] The waveguide substrate 110 is made of a material with birefringence. By using a birefringent material such as lithium niobate as the waveguide substrate, when incident light enters the waveguide substrate 110, due to the birefringence effect, the incident light is naturally separated into TE mode incident light and TM mode incident light, each mode corresponding to a different diffraction angle. This increases the propagation path width of the incident light within the waveguide substrate, making the beam more uniformly distributed within the waveguide, thereby significantly improving the beam transmission density and avoiding the problem of wasted light energy due to secondary diffraction caused by increasing the beam width w in traditional methods.

[0038] The coupling port 120 is located on the incident surface of the waveguide substrate 110 and is used to couple incident light, the beam width of which is w.

[0039] The coupling port 130 is located on the exit surface of the waveguide substrate 110 and is used to couple the transmitted light. Further, the transmitted light, after being coupled out from the waveguide substrate, enters the human eye to generate a virtual image.

[0040] The temperature control module 140 is located on one side of the waveguide substrate 110 and is used to control the temperature of the waveguide substrate 110. The refractive index of the waveguide substrate 110 changes with the temperature, which further adjusts the propagation path of the incident light in TE mode and the incident light in TM mode.

[0041] The diffraction waveguide beam density control device 100 based on birefringence effect in this embodiment firstly increases the beam density by utilizing the different diffraction angles corresponding to the incident light in TE mode and TM mode. Secondly, due to the increased beam density, the misalignment between primary and secondary total internal reflections is reduced, effectively decreasing the width of the dark area A. This results in a more uniform light intensity distribution in the coupling region, significantly improving the quality of the displayed image and reducing the impact of the dark area on the visual experience. The combined effect of increased beam density and reduced dark area makes the augmented reality image clearer, brighter, and more uniform. Users can obtain better visual effects in both indoor and outdoor environments, enhancing the realism and immersion of the displayed information. Furthermore, the temperature of the waveguide substrate can be precisely controlled by the temperature control module, changing the refractive index of the waveguide substrate 110 and further altering the propagation paths of the incident light in TE mode and TM mode. This enables programmable dark area distribution and dynamic optimization of beam density, overcoming the limitations of traditional fixed-parameter designs.

[0042] Based on the aforementioned embodiments, the temperature control module 140 has a temperature control range of 20℃ to 80℃ and a resolution of 0.1℃. The temperature control module 140 includes a heating element, a temperature sensor, and a control circuit. The heating element is used to heat the waveguide substrate 110. The heating element can be a resistance heating wire or an infrared heating lamp, etc. The temperature sensor is used to detect the real-time temperature of the waveguide substrate 110. The temperature sensor can be a thermocouple or a resistance temperature detector (RTD), etc. The control circuit, based on the feedback signal from the temperature sensor, precisely controls the heating element to achieve dynamic adjustment of the temperature of the waveguide substrate 110.

[0043] Based on the aforementioned embodiments, the waveguide substrate 110 is a lithium niobate waveguide substrate, a quartz waveguide substrate, a calcite waveguide substrate, or a sodium thiosulfate waveguide substrate. That is, the material of the waveguide substrate 110 is lithium niobate, quartz, calcite, or sodium thiosulfate. Specifically, at a wavelength of 633 nm, the refractive index of the lithium niobate crystal in TE mode (Ex polarization) is no≈2.286, sinβ1=0.61534, β1=37.97; the refractive index in TM mode (Ey polarization) is ne≈2.200, sinβ2=0.6394, β2=39.74, and the birefringence difference Δn reaches 0.086; the dark region = tanβ*h*2-di, assuming di=1mm, h=3mm, and the dark region = 3.68mm. At a wavelength of 589 nm, the ordinary refractive index of the quartz crystal is no≈1.544, the anomalous refractive index is ne≈1.553, and the birefringence difference Δn is approximately 0.009. When incident light enters the waveguide substrate 110, due to the birefringence effect, the incident light is naturally separated into TE mode incident light and TM mode incident light, each mode corresponding to a different diffraction angle. This invention can be implemented using a variety of materials with birefringence effects, providing more material selection space for different application scenarios and needs.

[0044] Based on the aforementioned embodiments, the thickness h of the waveguide substrate 110 is 0.5 mm to 4 mm. Further, the thickness h of the waveguide substrate 110 can be, but is not limited to, 0.5 mm, 1 mm, 2 mm, 3 mm, or 4 mm.

[0045] Based on the aforementioned embodiments, the coupling port 120 is a surface relief grating or a volume holographic grating with a period ranging from 200nm to 800nm. Further, the grating period of the coupling port 120 may be, but is not limited to, 200nm, 300nm, 400nm, 500nm, 600nm, 700nm, or 800nm.

[0046] Based on the aforementioned embodiments, the coupling port 130 is a two-dimensional grating pupil expander or a one-dimensional grating pupil expander, with a period ranging from 200nm to 800nm. Further, the grating period of the coupling port 130 may be, but is not limited to, 200nm, 300nm, 400nm, 500nm, 600nm, 700nm, or 800nm.

[0047] It should be noted that the diffraction waveguide beam density control device based on birefringence effect of this invention is not limited to the above-described embodiments, and some improvements can be made on this basis.

[0048] Please see Figure 3Another embodiment of the present invention provides a diffraction waveguide beam density control device 200 based on birefringence effect, comprising a waveguide substrate 210, an input port 220, an output port 230, and a temperature control module 240. The arrow above the input port 220 in the figure indicates the direction of incident light illumination.

[0049] The waveguide substrate 210 is made of a material with birefringence and has a thickness of h. The coupling port 220 is located on the incident surface of the waveguide substrate 210 and is used to couple incident light with a beam width of w. The coupling port 230 is located on the exit surface of the waveguide substrate 210 and is used to couple guided light. A temperature control module 240 is located on one side of the waveguide substrate 210 and is used to control the temperature of the waveguide substrate 210 and adjust the propagation paths of the TE mode incident light and the TM mode incident light.

[0050] In this embodiment, the temperature control module 240 is a non-uniform temperature field construction module used to construct a spatial temperature gradient on the waveguide substrate 210 to achieve regional birefringence control. The non-uniform temperature field construction module includes multiple independently controllable heating units. Each heating unit corresponds to a region of the waveguide substrate 210 and can be independently heated. By applying different temperatures to different regions, the desired temperature field distribution can be constructed. By constructing a non-uniform temperature field, regional birefringence control can be achieved. The high-temperature region has high beam overlap, suitable for displaying the core region, while the low-temperature region has significant beam separation, suitable for edge compensation.

[0051] Specifically, in this embodiment, the waveguide substrate 210 is divided into regions corresponding to different field of view angles. Correspondingly, the temperature control module 240 includes a first heating unit 241, a second heating unit 242, and a third heating unit 243. These three heating units correspond to different regions of the waveguide substrate 210 and heat those regions independently. The second heating unit 242 corresponds to a region of the waveguide substrate 210 with high beam overlap and can be designated as a high-temperature region. The first heating unit 241 and the third heating unit 243 correspond to regions of the waveguide substrate 210 with significant beam separation and can therefore be designated as low-temperature regions for edge compensation. Through this non-uniform temperature field design, the beam density can be finely controlled according to the different requirements of the displayed image regions, further optimizing the display effect.

[0052] Please see Figure 4 Another embodiment of the present invention provides a diffraction waveguide beam density control device 300 based on birefringence effect, comprising a waveguide substrate 310, an input port 320, an output port 330, a temperature control module 340, and an electric field control module 350. In the figure, the arrow above the input port 320 indicates the direction of incident light illumination, and the arrow above the output port 330 indicates the direction of output light coupling.

[0053] The waveguide substrate 310 is made of a material with birefringence and has a thickness of h. An input port 320 is located on the incident surface of the waveguide substrate 310 to couple incident light, the beam width of which is w. An output port 330 is located on the exit surface of the waveguide substrate 310 to couple guided light. A temperature control module 340 is located on one side of the waveguide substrate 310 to control its temperature. An electric field control module 350 applies an electric field to the waveguide substrate 310. Adjusting the temperature and applying an electric field to the waveguide substrate 310 both change its refractive index, thereby further adjusting the propagation paths of the incident light in TE and TM modes. This embodiment combines electric field control to form a composite control system, enabling coarse temperature adjustment and fine voltage adjustment, thus improving control resolution.

[0054] Based on the aforementioned embodiment, the electric field control module 350 includes an electrode pair and a power supply. The electrode pairs are respectively disposed on both sides or the same side of the waveguide substrate 310. The power supply is located on one side of the electrode pair and is used to provide an adjustable DC voltage of 0~5kV to the electrode pair. By changing the magnitude of the voltage applied to the electrodes, the birefringence difference Δn of the waveguide substrate can be precisely controlled.

[0055] Building upon the aforementioned embodiments, the diffraction waveguide beam density control device 300 based on birefringence further includes a machine learning optimization system. This system comprises an ambient light sensor, an image feedback module, a deep neural network model, and a control module. The ambient light sensor detects the intensity of surrounding light. The image feedback module acquires image information from the user's eyes. The deep neural network model, based on the input information from the ambient light sensor and the image feedback module, and combined with data from the temperature sensor, outputs the target temperature distribution and voltage setting (the optimal temperature distribution and voltage setting). The control module, based on the output of the deep neural network model, comprehensively controls the temperature control module and the electric field control module, thereby achieving programmable dark zone A-distribution, dynamic beam density optimization, and flexible configuration of mode coupling. By employing machine learning optimization methods to train the deep neural network, a mapping relationship is established between the input ambient light, temperature sensor data, image feedback, and the output optimal temperature distribution, enabling advanced control strategies.

[0056] This invention discloses a diffraction waveguide beam density control device based on birefringence. It utilizes the different diffraction angles produced by the different refractive indices of TE and TM mode incident light, thereby increasing the propagation path width of light within the waveguide substrate and improving beam density. Simultaneously, the temperature of the waveguide substrate can be precisely controlled via a temperature control module, altering the propagation paths of TE and TM mode incident light within the waveguide substrate, enabling programmable dark area distribution and dynamic optimization of beam density. Therefore, it can improve beam density and optimize display performance.

[0057] Please see Figure 5 One embodiment of the diffraction waveguide beam density control method based on birefringence effect includes the following steps:

[0058] S10. Provide a waveguide substrate, which is made of a material with birefringence effect, and provide an input port and an output port on the incident surface and the output surface of the waveguide substrate, respectively.

[0059] S20. The incident light is coupled into the waveguide substrate through the coupling port. The incident light is separated into TE mode incident light and TM mode incident light by utilizing the birefringence effect of the waveguide substrate.

[0060] S30. By controlling the temperature of the waveguide substrate through the temperature control module, the propagation paths of the incident light in TE mode and TM mode are changed, thereby enabling programmable dark area distribution and dynamic optimization of beam density.

[0061] The temperature control module has a temperature control range of 20℃ to 80℃ and a resolution of 0.1℃. By precisely controlling the temperature of the lithium niobate waveguide, the propagation paths of the incident light in TE mode and TM mode can be adjusted, enabling programmable dark area distribution and dynamic optimization of beam density, thus overcoming the limitations of traditional fixed parameter designs.

[0062] Based on the aforementioned implementation method, the diffraction waveguide beam density control method based on birefringence effect further includes the following steps:

[0063] S40. Apply an electric field to the waveguide substrate through the electric field modulation module to fine-tune the propagation paths of the incident light in TE mode and TM mode.

[0064] S50 utilizes machine learning to optimize the system, outputting target temperature distribution and voltage settings based on ambient light intensity, temperature sensor data, and image feedback, and comprehensively controlling the temperature control module and electric field control module;

[0065] S60. The incident light in TE mode and the incident light in TM mode are coupled out of the waveguide substrate through the coupling port and enter the human eye.

[0066] In the above steps, the adjustable DC voltage range is 0~5kV. By changing the applied voltage, the birefringence difference Δn of the waveguide substrate can be precisely controlled.

[0067] The diffraction waveguide beam density control method based on birefringence effect of this invention can be implemented using any of the diffraction waveguide beam density control devices based on birefringence effect described above.

[0068] Based on the aforementioned embodiments, the waveguide substrate material is lithium niobate, quartz, calcite, or sodium thiosulfate.

[0069] Based on the aforementioned implementation method, the thickness of the waveguide substrate is 0.5mm to 4mm.

[0070] Based on the aforementioned implementation, the coupling port is a surface relief grating or a volume holographic grating with a period range of 200nm~800nm.

[0071] Based on the aforementioned implementation, the coupling port is a two-dimensional grating pupil expander or a one-dimensional grating pupil expander, with a period range of 200nm~800nm.

[0072] This invention presents a method for controlling the beam density of a diffractive waveguide based on birefringence. It utilizes the different diffraction angles produced by the different refractive indices of TE and TM mode incident light, thereby increasing the propagation path width of light within the waveguide substrate and improving beam density. Simultaneously, the temperature of the waveguide substrate can be precisely controlled via a temperature control module, altering the propagation paths of TE and TM mode incident light within the waveguide substrate, enabling programmable dark area distribution and dynamic optimization of beam density. Therefore, it can improve beam density and optimize display performance.

[0073] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0074] The embodiments described above are merely illustrative of several implementations of this utility model, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. A diffraction waveguide beam density modulation device based on birefringence effect, characterized in that, include: The waveguide substrate is made of a material with birefringence effect, and incident light is naturally separated into TE mode and TM mode when it enters the waveguide substrate. The coupling port is located on the incident surface of the waveguide substrate and is used to couple incident light. The coupling port is located on the exit surface of the waveguide substrate and is used for coupling the transmitted light; as well as A temperature control module is disposed on one side of the waveguide substrate and is used to control the temperature of the waveguide substrate and adjust the propagation path of the incident light in TE mode and TM mode inside the waveguide substrate.

2. The birefringence effect based diffractive waveguide beam density manipulation device according to claim 1, characterized in that, The temperature control module has a temperature control range of 20℃ to 80℃ and a resolution of 0.1℃. The temperature control module includes: A heating element for heating the waveguide substrate; A temperature sensor is used to detect the real-time temperature of the waveguide substrate; and The control circuit, based on the feedback signal from the temperature sensor, precisely controls the heating element to achieve dynamic adjustment of the waveguide substrate temperature.

3. A birefringence effect based diffractive waveguide beam density manipulation device according to claim 1 or 2, characterized in that, The temperature control module is a non-uniform temperature field construction module, used to construct a spatial temperature gradient on the waveguide substrate to achieve regional birefringence control. The non-uniform temperature field construction module includes multiple independently controllable heating units.

4. The diffraction waveguide beam density control device based on birefringence effect according to claim 1, characterized in that, It also includes an electric field control module for applying an electric field to the waveguide substrate.

5. The birefringence effect based diffractive waveguide beam density manipulation device according to claim 4, characterized in that, The electric field control module includes a power supply and an electrode pair, wherein the electrode pairs are respectively disposed on both sides or the same side of the waveguide substrate.

6. The birefringence effect based diffractive waveguide beam density manipulation device according to claim 4, wherein, It also includes a machine learning optimization system, which comprises: An ambient light sensor is used to detect the intensity of ambient light. The image feedback module is used to acquire image information of the user's eyes; The deep neural network model, based on the input information from the ambient light sensor and the image feedback module, combined with the data from the temperature sensor, outputs the target temperature distribution and voltage setting; The control module, based on the output of the deep neural network model, performs integrated control on the temperature regulation module and the electric field control module.

7. The birefringence effect based diffractive waveguide beam density manipulation device according to claim 1, wherein, The waveguide substrate is a lithium niobate waveguide substrate, a quartz waveguide substrate, a calcite waveguide substrate, or a sodium thiosulfate waveguide substrate.

8. The birefringence effect based diffractive waveguide beam density manipulation device according to claim 1, wherein, The thickness of the waveguide substrate is 0.5mm to 4mm.

9. The diffraction waveguide beam density control device based on birefringence effect according to claim 1, characterized in that, The coupling port is a surface relief grating or a volume holographic grating with a period range of 200nm~800nm.

10. The birefringence effect based diffractive waveguide beam density control device according to claim 1, characterized in that, The output port is a two-dimensional grating pupil expander or a one-dimensional grating pupil expander, with a period range of 200nm~800nm.

Images