Diffraction optical waveguide device and augmented reality display device

Abstract

The invention discloses a diffraction optical waveguide device and an augmented reality display device. The diffraction optical waveguide device comprises a diffraction waveguide layer, a dielectric layer and a white sheet waveguide layer which are sequentially arranged in a laminated mode. The diffraction waveguide layer is used for coupling an image light beam output by an optical machine, diffracting the image light beam to form diffracted light beams with different diffraction angles and transmitting the diffracted light beams to the dielectric layer; the dielectric layer is used for acting on the diffracted light beam to form a transmission light beam and a reflection light beam; the transparent waveguide layer is also used for transmitting a transmission light beam, so that the transmission light beam is reflected back and forth between the top surface of the diffraction waveguide layer and the bottom surface of the white sheet waveguide layer and is coupled out by the diffraction waveguide layer; the diffraction waveguide layer is also used for reflecting the reflected light beam, so that the reflected light beam is reflected back and forth in the diffraction waveguide layer and is coupled out by the diffraction waveguide layer; the reflectivity of the dielectric layer to the diffracted light beam is increased along with the increase of the diffraction angle of the diffracted light beam, the diffracted light beam can be reflected and transmitted through the dielectric layer, and the color uniformity of the device is optimized.

Description

Technical Field

[0001] Embodiments of the present invention relate to the field of optical technologies, and in particular, to a diffractive optical waveguide device and an augmented reality display device. Background Art

[0002] Augmented Reality (AR) technology is a technology that combines virtual information generated by a computer with the real environment, and can superimpose virtual information on the real world in real time and dynamically, thereby enhancing the user's perception and understanding of the real world.

[0003] An optical waveguide is an optical device used in augmented reality near-eye display devices. It can project a virtual image into the user's eyes while ensuring that the user's view of the real world is not blocked. Currently, optical waveguides are mainly divided into array optical waveguides and diffractive optical waveguides from an optical principle. Different types of optical waveguides have differences in performance, cost, and application scenarios. Currently, representative products of these two different types of optical waveguides are available on the market.

[0004] Among them, diffractive optical waveguides have a high market share due to their low cost and mass production. However, diffractive optical waveguides have the problem of poor color uniformity, resulting in the existing diffractive optical waveguide products mainly being single-green displays. Therefore, the color deviation problem of diffractive waveguide displays needs to be further improved. Summary of the Invention

[0005] Embodiments of the present invention provide a diffractive optical waveguide device and an augmented reality display device to optimize the color uniformity of the diffractive optical waveguide device.

[0006] In a first aspect, embodiments of the present invention provide a diffractive optical waveguide device, including: a diffractive waveguide layer, a dielectric layer, and a white sheet waveguide layer that are sequentially stacked; The diffractive waveguide layer is configured to couple in an image beam output by an optical engine, diffract the image beam to form diffracted beams with different diffraction angles, and transmit the diffracted beams to the dielectric layer; The dielectric layer is configured to act on the diffracted beams to form transmitted beams and reflected beams; is further configured to transmit the transmitted beams, so that the transmitted beams are reflected back and forth between two surfaces of the top surface of the diffractive waveguide layer and the bottom surface of the white sheet waveguide layer, and are coupled out by the diffractive waveguide layer; is further configured to reflect the reflected beams, so that the reflected beams are reflected back and forth in the diffractive waveguide layer and are coupled out by the diffractive waveguide layer; wherein, the reflectivity of the dielectric layer to the diffracted beams increases as the diffraction angle of the diffracted beams increases.

[0007] Optionally, the diffracted beams passing through the dielectric layer satisfy the principle of frustrated total reflection.

[0008] Optionally, the reflectivity of the dielectric layer and the diffraction angle of the diffracted light beam satisfy the following relationship: The dielectric layer mainly transmits the diffracted light beam with a small diffraction angle, mainly reflects the diffracted light beam with a large diffraction angle, and mainly has a semi-transmissive and semi-reflective effect on the diffracted light beam with an intermediate diffraction angle, where the minimum value of the intermediate diffraction angle is greater than or equal to the maximum value of the small diffraction angle, and the maximum value of the intermediate diffraction angle is less than or equal to the minimum value of the large diffraction angle.

[0009] Optionally, the reflectivity of the dielectric layer and the diffraction angle of the diffracted light beam satisfy the following relationship: The reflectivity of the dielectric layer for the diffracted light beam with a diffraction angle ranging from 0° to 30° is greater than 0 and less than 5%; The reflectivity of the dielectric layer for the diffracted light beam with a diffraction angle ranging from 30° to 50° is greater than or equal to 1% and less than 30%; The reflectivity of the dielectric layer for the diffracted light beam with a diffraction angle ranging from 50° to 90° is greater than or equal to 10% and less than 100%.

[0010] Optionally, the rate of change of the reflectivity of the dielectric layer and the diffraction angle of the diffracted light beam satisfy the following relationship: As the diffraction angle of the diffracted light beam increases, the change process of the rate of change of the reflectivity of the dielectric layer changes from a slow increase to a rapid increase, and then from a rapid increase to a slow decrease.

[0011] Optionally, the diffracted light beam includes at least one color light beam; the at least one color light beam includes red light, blue light, and green light.

[0012] Optionally, a grating structure is provided on the top surface of the diffraction waveguide layer, and the dielectric layer is provided on the bottom surface of the diffraction waveguide layer or the top surface of the white sheet waveguide layer.

[0013] Optionally, the dielectric layer is coated on the bottom surface of the diffraction waveguide layer or the top surface of the white sheet waveguide layer; The surface of the diffraction waveguide layer coated with the dielectric layer and the top surface of the white sheet waveguide layer are connected by glue bonding or molecular bonding; Alternatively, the bottom surface of the diffraction waveguide layer and the surface of the white sheet waveguide layer coated with the dielectric layer are connected by glue bonding or molecular bonding.

[0014] Optionally, the thickness H1 of the dielectric layer satisfies: H1 ≤ 1.5 μm.

[0015] In a second aspect, an embodiment of the present invention further provides an augmented reality display device, including an optical engine module and the diffraction optical waveguide device according to any one of the first aspect.

[0016] The technical solution provided by the embodiment of the present invention is to provide a dielectric layer between the diffraction waveguide layer and the blank waveguide layer, and the dielectric layer can transmit and reflect the diffracted light beam. Specifically, the dielectric layer can act on the diffracted light beam to form a transmitted light beam and a reflected light beam. The dielectric layer transmits the transmitted light beam, causing the transmitted light beam to be reflected back and forth between the two surfaces of the top surface of the diffraction waveguide layer and the bottom surface of the blank waveguide layer, and then coupled out by the diffraction waveguide layer; the dielectric layer reflects the reflected light beam, causing the reflected light beam to be reflected back and forth within the diffraction waveguide layer, and then coupled out by the diffraction waveguide layer. In addition, since the diffracted light beam with a large diffraction angle has a long step length and the diffracted light beam with a small diffraction angle has a short step length, the reflectivity of the dielectric layer to the diffracted light beam increases as the diffraction angle of the diffracted light beam increases. In this way, it can be ensured that the step length change of the diffracted light beams with different diffraction angles within the diffractive optical waveguide device is a uniform transition without sudden changes, thereby preventing color deviation in the diffractive optical waveguide device and achieving optimization of color uniformity.

[0017] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present invention, nor is it used to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the introduced drawings are only the drawings of a part of the embodiments to be described by the present invention, rather than all the drawings. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0019] Figure 1 is a schematic structural diagram of a diffractive optical waveguide device in the prior art; Figure 2 is Figure 1 a simulation schematic diagram of the coupled-out light spot corresponding to the smallest diffraction angle of blue light; Figure 3 is Figure 1 a simulation schematic diagram of the coupled-out light spot corresponding to the largest diffraction angle of red light; Figure 4 is a schematic structural diagram of a diffractive optical waveguide device provided by the embodiment of the present invention; Figure 5 is a transmission schematic diagram of blue light by the diffractive optical waveguide device provided by the embodiment of the present invention; Figure 6 is a transmission schematic diagram of red light by the diffractive optical waveguide device provided by the embodiment of the present invention; Figure 7 is Figure 4Schematic diagram of the coupling-out light spot with the smallest corresponding blue light diffraction angle; Figure 8 is Figure 4 Schematic diagram of the coupling-out light spot with the largest corresponding red light diffraction angle; Figure 9 Schematic diagram of the reflectivity of the first dielectric layer provided by the embodiment of the present invention for diffracted light beams with different diffraction angles; Figure 10 Schematic diagram of the reflectivity of the second dielectric layer provided by the embodiment of the present invention for diffracted light beams with different diffraction angles; Figure 11 Schematic diagram of the reflectivity of the third dielectric layer provided by the embodiment of the present invention for diffracted light beams with different diffraction angles. Detailed implementation manners

[0020] The present invention will be further described in detail below with reference to the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the present invention, rather than limiting the present invention. In addition, it should be noted that for the convenience of description, only parts related to the present invention rather than all structures are shown in the drawings. It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above drawings are used to distinguish similar objects, and do not have to be used to describe a specific order or sequence. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion.

[0021] Before elaborating on the technical solution of the present invention in detail, the diffractive optical waveguide devices in the prior art will be introduced first.

[0022] Figure 1 Schematic diagram of the structure of a diffractive optical waveguide device in the prior art, as Figure 1 shown. Exemplarily, the diffraction angle range of the red light 100' is 46° - 84°. The total reflection step length of the red light 100' is relatively long, which will cause one side of the display screen to be reddish, that is, the coupling-out light spots are completely discontinuous, thus resulting in poor color uniformity of the display screen.

[0023] Continue to refer to Figure 1, taking a one-dimensional single-chip full-color diffractive optical waveguide as an example, assuming that the refractive index of the waveguide is 2 and the wavelengths of the incident red, green, and blue lights are 617 nm, 532 nm, and 460 nm respectively, the total internal reflection angle of the light beam in the waveguide can be calculated to be 30°. Limiting the maximum total internal reflection angle to be less than 85° allows the calculation of the coupling-in and coupling-out grating periods to be 360 nm, and the maximum field of view for full-color display can be achieved to be 32° along the pupil expansion direction of the coupling-in and coupling-out. Along the pupil expansion direction, the diffraction angle range of the blue light at 200’ is 30° - 50°, the diffraction angle range of the green light is 37° - 61°, and the diffraction angle range of the red light at 100’ is 46° - 84°. That is, the total internal reflection transmission step length of the blue light at 200’ is shorter, and the total internal reflection step length of the red light at 100’ is longer, which will cause one side of the display screen to be biased towards red and the other side to be biased towards blue.

[0024] Exemplarily, continuing to refer to Figure 1 , assuming that the thickness of the diffractive waveguide layer 10’ is 0.8 mm, the distances of the coupling-out spots of the red and blue light beams with different wavelengths are simulated. To clearly show the step difference, the diameter of the coupling-in light beam is set to 2 mm. Figure 2 For Figure 1 The simulation schematic diagram of the coupling-out spot corresponding to the minimum diffraction angle of the blue light is as Figure 2 shown. The coupling-out spots corresponding to the minimum diffraction angle of the blue light at 200’ are closely overlapped, that is, the spots are continuous. Figure 3 For Figure 1 The simulation schematic diagram of the coupling-out spot corresponding to the maximum diffraction angle of the red light is as Figure 3 shown. The coupling-out spots corresponding to the maximum diffraction angle of the red light at 100’ are completely discontinuous, which will cause one side of the display screen to be biased towards red and the other side to be biased towards blue.

[0025] In view of the above technical problems existing in the prior art, the technical solutions of the embodiments of the present invention are provided. Next, the technical solutions provided by the embodiments of the present invention will be elaborated in detail.

[0026] Figure 4 The structural schematic diagram of a diffractive optical waveguide device provided by an embodiment of the present invention Figure 5 The transmission schematic diagram of the diffractive optical waveguide device provided by an embodiment of the present invention for blue light Figure 6 The transmission schematic diagram of the diffractive optical waveguide device provided by an embodiment of the present invention for red light is as Figures 4 to 6As shown, the diffractive optical waveguide device includes a diffractive waveguide layer 10, a dielectric layer 20, and a blank waveguide layer 30 that are sequentially stacked; the diffractive waveguide layer 10 is used to couple in the image light beam output by the optical engine, diffract the image light beam to form diffracted light beams a with different diffraction angles, and transmit the diffracted light beam a to the dielectric layer 20; the dielectric layer 20 is used to act on the diffracted light beam a to form a transmitted light beam b and a reflected light beam c; it is also used to transmit the transmitted light beam b, so that the transmitted light beam b is reflected back and forth between the two surfaces of the top surface of the diffractive waveguide layer 10 and the bottom surface of the blank waveguide layer 30, and is coupled out by the diffractive waveguide layer 10; it is also used to reflect the reflected light beam c, so that the reflected light beam c is reflected back and forth in the diffractive waveguide layer 10 and is coupled out by the diffractive waveguide layer 10; wherein, the reflectivity of the dielectric layer 20 to the diffracted light beam a increases with the increase of the diffraction angle of the diffracted light beam a.

[0027] Specifically, the image light beam output by the optical engine is coupled into the diffractive waveguide layer 10, and the diffractive waveguide layer 10 can diffract the image light beam to form diffracted light beams a with different diffraction angles, and transmit the diffracted light beam a to the dielectric layer 20.

[0028] Specifically, the dielectric layer 20 can act on the diffracted light beam a to form a transmitted light beam b and a reflected light beam c. The dielectric layer 20 can transmit the transmitted light beam b, so that the transmitted light beam b is reflected back and forth between the two surfaces of the top surface of the diffractive waveguide layer 10 and the bottom surface of the blank waveguide layer 30, and is coupled out by the diffractive waveguide layer 10. The dielectric layer 20 can reflect the reflected light beam c, so that the reflected light beam c is reflected back and forth in the diffractive waveguide layer 10 and is coupled out by the diffractive waveguide layer 10. That is to say, on the one hand, the dielectric layer 20 can transmit the diffracted light beam a, so that the light beam undergoes total internal reflection in the entire diffractive optical waveguide device, and on the other hand, the dielectric layer 20 can reflect the diffracted light beam a, that is, the light beam is reflected in the diffractive waveguide layer 10.

[0029] Furthermore, the reflectivity of the dielectric layer 20 to the diffracted light beam a increases with the increase of the diffraction angle of the diffracted light beam a. That is to say, the larger the diffraction angle of the diffracted light beam a, the greater the reflectivity of the dielectric layer 20 to the diffracted light beam a. Since the diffracted light beam a with a large diffraction angle has a long step length, and the diffracted light beam a with a small diffraction angle has a short step length, that is, the diffracted light beam a with a large diffraction angle has a long step length, and the dielectric layer 20 has a greater reflectivity to this diffracted light beam, the diffracted light beam a with a small diffraction angle has a short step length, and the dielectric layer 20 has a smaller reflectivity to this diffracted light beam. In this way, the diffracted light beam a with a large diffraction angle is reflected to the diffractive waveguide layer 10 by the action of the dielectric layer 20, and then is reflected back and forth in the diffractive waveguide layer 10. In this way, it can be ensured that the step length change of the diffracted light beams a with different diffraction angles in the diffractive optical waveguide device is evenly transitioned without sudden changes, thereby preventing color deviation in the diffractive optical waveguide device and realizing the optimization of color uniformity.

[0030] Continue to refer to Figure 5, the diffraction angle of the blue light 200 is small, the step length of the blue light 200 is short, and the reflectivity of the dielectric layer 20 to the blue light 200 is low, that is, the dielectric layer 20 mainly transmits the blue light 200. The dielectric layer 20 transmits more blue light 200, and the transmitted light beam b is reflected back and forth between the two surfaces of the top surface of the diffraction waveguide layer 10 and the bottom surface of the white sheet waveguide layer 30, and is coupled out by the diffraction waveguide layer 10. Only a small part of the blue light is reflected by the dielectric layer 20 and diffracted into the waveguide layer 10, reflected back and forth in the diffraction waveguide layer 10, and coupled out by the diffraction waveguide layer 10.

[0031] Continue to refer to Figure 6 , the diffraction angle of the red light 100 is large, the step length of the red light 100 is long, and the reflectivity of the dielectric layer 20 to the red light 100 is high, that is, the dielectric layer 20 mainly reflects the red light 100. The dielectric layer 20 reflects more red light to the diffraction waveguide layer 10, and then the red light 100 is reflected back and forth in the diffraction waveguide layer 10 and coupled out by the diffraction waveguide layer 10. Only a small part of the red light 100 is transmitted through the dielectric layer 20, reflected back and forth between the two surfaces of the top surface of the diffraction waveguide layer 10 and the bottom surface of the white sheet waveguide layer 30, and coupled out by the diffraction waveguide layer 10. In this way, it can be ensured that the step length change of the red light in the diffraction optical waveguide device is evenly transitioned without mutation, and the continuity of the coupled-out light spot corresponding to the red light is better, so as to prevent color deviation of the diffraction optical waveguide device and optimize color uniformity.

[0032] Specifically, taking the total thickness of the diffraction optical waveguide device as 0.8 mm, where the thickness of the diffraction waveguide layer 10 is about 0.1 mm, the thickness of the white sheet waveguide layer 30 is about 0.7 mm, the thickness of the dielectric layer 20 is 110 nm, and the diameter of the coupled-in light beam is 2 mm as an example for illustration, Figure 7 For Figure 4 the simulation schematic diagram of the coupled-out light spot with the smallest diffraction angle of the corresponding blue light, compared with Figure 2 and Figure 7 , by setting the dielectric layer 20 between the diffraction waveguide layer 10 and the white sheet waveguide layer 30, the step length change of the coupled-out light spot with the smallest diffraction angle of the blue light is not large. Figure 8 For Figure 4 the simulation schematic diagram of the coupled-out light spot with the largest diffraction angle of the corresponding red light, compared with Figure 3 and Figure 8 , by setting the dielectric layer 20 between the diffraction waveguide layer 10 and the white sheet waveguide layer 30, the coupled-out light spot with the largest diffraction angle of the red light changes from completely discontinuous to continuous, so as to improve color deviation and optimize color uniformity.

[0033] In the diffractive optical waveguide device provided by the embodiment of the present invention, a dielectric layer is arranged between the diffractive waveguide layer and the blank waveguide layer. The dielectric layer transmits the transmitted light beam, causing the transmitted light beam to be reflected back and forth between the two surfaces of the top surface of the diffractive waveguide layer and the bottom surface of the blank waveguide layer, and coupled out by the diffractive waveguide layer; the dielectric layer reflects the reflected light beam, causing the reflected light beam to be reflected back and forth within the diffractive waveguide layer, and coupled out by the diffractive waveguide layer. In addition, since the diffractive light beam with a large diffraction angle has a long step length and the diffractive light beam with a small diffraction angle has a short step length, the reflectivity of the dielectric layer to the diffractive light beam increases with the increase of the diffraction angle of the diffractive light beam. In this way, it can be ensured that the step length change of the diffractive light beams with different diffraction angles in the diffractive optical waveguide device is evenly transitioned without sudden changes, thereby preventing color deviation in the diffractive optical waveguide device and realizing the optimization of color uniformity.

[0034] Optionally, continue to refer to Figure 4 , the diffractive light beam satisfies the principle of frustrated total reflection when passing through the dielectric layer 20.

[0035] Specifically, taking the diffractive waveguide layer 10 and the blank waveguide layer 30 as optically dense media and the dielectric layer 20 as an optically sparse medium as an example, when there is a very thin optically sparse medium between two optically dense medium regions and light enters the dielectric layer 20 from one optically dense medium at an angle greater than the total reflection angle, part of the light will pass through the dielectric layer 20 and enter the other optically dense medium to realize the function of the dielectric layer 20, thereby realizing the transmission and reflection of part of the diffractive light beam a. The greater the incident angle of the diffractive light beam a incident on the dielectric layer 20, the greater the reflectivity and the smaller the transmittance; the smaller the incident angle, the smaller the reflectivity and the greater the transmittance. The sum of the transmittance and reflectivity of the dielectric layer 20 to the diffractive light beam a is 1.

[0036] Optionally, continue to refer to Figure 4 , the reflectivity of the dielectric layer 20 and the diffraction angle of the diffractive light beam satisfy the following relationship: the dielectric layer 20 mainly transmits the diffractive light beam with a small diffraction angle, mainly reflects the diffractive light beam with a large diffraction angle, and mainly has a semi-transmissive and semi-reflective effect on the diffractive light beam with an intermediate diffraction angle, where the minimum value of the intermediate diffraction angle is greater than or equal to the maximum value of the small diffraction angle, and the maximum value of the intermediate diffraction angle is less than or equal to the minimum value of the large diffraction angle.

[0037] Specifically, the image light beam coupled into the optical engine output is diffracted by the diffraction waveguide layer 10 to form diffracted light beams with different diffraction angles. The diffracted light beams with different diffraction angles are transmitted to the dielectric layer 20. The dielectric layer 20 mainly plays a transmission role for the diffracted light beams with small diffraction angles, that is, the dielectric layer 20 transmits most of the diffracted light beams with small diffraction angles, so that the transmitted light beams are reflected back and forth between the two surfaces of the top surface of the diffraction waveguide layer 10 and the bottom surface of the white sheet waveguide layer 30, and are coupled out by the diffraction waveguide layer 10. The dielectric layer 20 reflects a small part of the diffracted light beams with small diffraction angles. The dielectric layer 20 mainly plays a reflection role for the diffracted light beams with large diffraction angles, that is, the dielectric layer 20 reflects most of the diffracted light beams with large diffraction angles, and the reflected light is reflected back and forth in the diffraction waveguide layer 10 and is coupled out by the diffraction waveguide layer 10. The dielectric layer 20 transmits a small part of the diffracted light beams with large diffraction angles. The dielectric layer 20 mainly plays a semi-transmissive and semi-reflective role for the diffracted light beams with intermediate diffraction angles, that is, the dielectric layer 20 transmits a part of the diffracted light beams with intermediate diffraction angles, so that the transmitted light beams are reflected back and forth between the two surfaces of the top surface of the diffraction waveguide layer 10 and the bottom surface of the white sheet waveguide layer 30, and are coupled out by the diffraction waveguide layer 10. In addition, the dielectric layer 20 reflects a part of the diffracted light beams with intermediate diffraction angles, and the reflected light is reflected back and forth in the diffraction waveguide layer 10 and is coupled out by the diffraction waveguide layer 10. In this way, it can be ensured that the step change of the diffracted light beams with different diffraction angles in the diffractive optical waveguide device is evenly transitioned without sudden changes, and the continuity of the coupled-out light spots of the diffracted light rays with different diffraction angles is better, so as to prevent color deviation of the diffractive optical waveguide device and optimize color uniformity.

[0038] Exemplarily, the diffracted light beam with a small diffraction angle can be blue light. The dielectric layer 20 mainly plays a transmission role for blue light. The diffracted light beam with an intermediate diffraction angle can be green light. The dielectric layer 20 mainly plays a semi-transmissive and semi-reflective role for green light. The diffracted light beam with a large diffraction angle can be red light. The dielectric layer 20 mainly plays a reflection role for red light. In this way, it can be ensured that the step change of the diffracted light beams with different diffraction angles in the diffractive optical waveguide device is evenly transitioned without sudden changes, so as to prevent color deviation of the diffractive optical waveguide device and optimize color uniformity.

[0039] Optionally, Figure 9 is a schematic diagram of the reflectivity of the first dielectric layer for diffracted light beams with different diffraction angles provided by an embodiment of the present invention. Figure 10 is a schematic diagram of the reflectivity of the second dielectric layer for diffracted light beams with different diffraction angles provided by an embodiment of the present invention. Figure 11 is a schematic diagram of the reflectivity of the third dielectric layer for diffracted light beams with different diffraction angles provided by an embodiment of the present invention, as Figure 4 、 Figures 9 to 11As shown in the figure, the reflectivity of the dielectric layer 20 and the diffraction angle of the diffracted light beam satisfy the following relationship: the reflectivity of the dielectric layer 20 for the diffracted light beam with a diffraction angle ranging from 0° to 30° is greater than 0 and less than 5%; the reflectivity of the dielectric layer 20 for the diffracted light beam with a diffraction angle ranging from 30° to 50° is greater than or equal to 1% and less than 30%; the reflectivity of the dielectric layer 20 for the diffracted light beam with a diffraction angle ranging from 50° to 90° is greater than or equal to 10% and less than 100%.

[0040] Specifically, Figures 9 to 11 taking the one-dimensional single-chip full-color diffractive optical waveguide device as an example, the principle of the dielectric layer improving color uniformity is analyzed. As a feasible implementation manner, continue to refer to Figure 9 , the dielectric layer 20 is made of Al with a lower refractive index 2 O 3 as an example, and the diffractive waveguide layer 10 and the white sheet waveguide layer 30 are both made of TAFD55 with a higher refractive index. When the thickness of the Al 2 O 3 dielectric layer is much larger than the visible light wavelength and both sides are made of TAFD55 with a high refractive index, the light is totally reflected at the interface of TAFD55 incident on Al 2 O 3 at an incident angle of about 56°. Thus, the reflectivity of the dielectric layer 20 for the diffracted light beam with a diffraction angle ranging from 50° to 90° is relatively large. In this embodiment, the reflectivity of the dielectric layer 20 for the diffracted light beam with a diffraction angle ranging from 0° to 30° is 0% - 3%, and the reflectivity of the dielectric layer 20 for the diffracted light beam with a diffraction angle ranging from 30° to 50° is greater than or equal to 3% and less than 30%; the reflectivity of the dielectric layer 20 for the diffracted light beam with a diffraction angle ranging from 50° to 90° is greater than or equal to 30% and less than 100%, which is beneficial to ensuring that the step change of the diffracted light beam with different diffraction angles in the diffractive optical waveguide device is uniformly transitional, and thus optimizing the color uniformity of the diffractive optical waveguide device.

[0041] As another feasible implementation manner, continue to refer to Figure 10 , when the dielectric layer uses Al 2 O 3When the material is [material name] and the thickness is 110 nm, the reflectivity of the dielectric layer 20 for diffracted light beams with diffraction angles ranging from 0° to 30° is relatively low, the reflectivity of the dielectric layer 20 for diffracted light beams with diffraction angles ranging from 60° to 90° is relatively high, and the overall reflectivity of the dielectric layer 20 for diffracted light beams with diffraction angles ranging from 30° to 90° increases with the increase of the diffraction angle. Using this characteristic, the dielectric layer can mainly transmit small-angle diffracted light beams and mainly reflect large-angle diffracted light beams. In this embodiment, the reflectivity of the dielectric layer 20 for diffracted light beams with diffraction angles ranging from 0° to 30° is 0% - 5%, and the reflectivity of the dielectric layer 20 for diffracted light beams with diffraction angles ranging from 30° to 50° is greater than or equal to 5% and less than 18%; the reflectivity of the dielectric layer 20 for diffracted light beams with diffraction angles ranging from 50° to 90° is greater than or equal to 18% and less than 100%, and the dielectric layer plays a semi-transmissive and semi-reflective role for diffracted light beams with intermediate angles, thereby optimizing the color uniformity of the diffractive optical waveguide device.

[0042] As another feasible implementation manner, the following table shows the variation of the optical parameters of a diffractive optical waveguide device provided by an embodiment of the present invention with the film layer structure. Specifically:

[0043] Continue to refer to Figure 11 As shown in the above table, the materials of the diffractive waveguide layer 10 and the blank waveguide layer 30 can both be TAFD55, and the dielectric layer 20 can include four dielectric sub-layers arranged in a stacked manner. Exemplarily, the materials of the four dielectric sub-layers arranged in a stacked manner can be Ta 2 O 5 、SiO 2 、Ta 2 O 5 and SiO 2 in sequence. The reflectivity of the dielectric layer 20 for diffracted light beams with diffraction angles ranging from 0° to 30° is less than 1%, which is beneficial to ensuring that increasing the dielectric layer will not affect the light transmittance of the diffractive optical waveguide device. The reflectivity of the dielectric layer 20 for diffracted light beams with diffraction angles ranging from 30° to 50° is relatively low, the reflectivity of the dielectric layer 20 for diffracted light beams with diffraction angles ranging from 46° to 84° is relatively high, and the higher the diffraction angle of the diffracted light beam, the higher the reflectivity of the dielectric layer 20. In this embodiment, the reflectivity of the dielectric layer 20 for diffracted light beams with diffraction angles ranging from 0° to 30° is 0% - 1%, and the reflectivity of the dielectric layer 20 for diffracted light beams with diffraction angles ranging from 30° to 50° is greater than or equal to 1% and less than 10%; the reflectivity of the dielectric layer 20 for diffracted light beams with diffraction angles ranging from 50° to 90° is greater than or equal to 10% and less than 100%, which significantly improves the continuity of light beams with larger total reflection step lengths and has little impact on light beams with smaller total reflection step lengths, thus significantly improving the color deviation problem.

[0044] Therefore, from the above embodiments, it can be seen that the dielectric layer 20 can be composed of one or more layers, and the material of each layer can be SiO 2 、Al 2 O 3 、Ta 2 O 5 、HfO 2 、CeO 2 、TiO 2 or other available materials. The thickness of the dielectric layer 20 can be adjusted accordingly according to the color uniformity of the light beam finally coupled out by the diffractive waveguide layer 10.

[0045] Optionally, continuing to refer to Figure 4 、 Figures 9 to 11 , the change rate of the reflectivity of the dielectric layer 20 and the diffraction angle of the diffracted light beam satisfy the following relationship: as the diffraction angle of the diffracted light beam increases, the change process of the change rate of the reflectivity of the dielectric layer 20 changes from a slow increase to a rapid increase, and then changes from a rapid increase to a slow decrease.

[0046] Specifically, as the diffraction angle of the diffracted light beam increases, the change process of the change rate of the reflectivity of the dielectric layer 20 changes from a slow increase to a rapid increase, and then changes from a rapid increase to a slow decrease, that is, as the diffraction angle of the diffracted light beam increases, the change of the change rate of the reflectivity of the dielectric layer 20 first increases relatively gently, then increases sharply, and finally returns to a stable state. In this way, when the diffraction angle is a small angle, the reflectivity is small and the change is slow; when the diffraction angle is a medium angle, the reflectivity is in the middle and the change is fast; when the diffraction angle is a large angle, the reflectivity is large and the change is slow. In this way, the continuity of the light beam with a large total reflection step length can be significantly improved, and the influence on the light beam with a small total reflection step length is small, thereby significantly improving the color deviation problem.

[0047] Optionally, continuing to refer to Figure 4 , the diffracted light beam includes at least one color light beam; the at least one color light beam includes red light, blue light and green light.

[0048] Specifically, the diffracted light beam includes at least one color light beam. By setting the dielectric layer 20 to reflect and transmit a certain color of diffracted light beam, and the reflectivity of the dielectric layer 20 for the diffracted light beam increases as the diffraction angle of the diffracted light beam increases. For example, the spot continuity of this color of diffracted light beam in the coupling out area is better, so that the color deviation can be improved and the performance of the diffractive optical waveguide device can be improved.

[0049] Specifically, at least one color beam includes red light, blue light, and green light. Due to the reflectivity of the dielectric layer 20 for the diffracted beam, which increases as the diffraction angle of the diffracted beam increases. Exemplarily, the diffraction angle of red light is in the range of 46° to 84°. Thus, the dielectric layer 20 has a relatively high reflectivity for red light and a relatively low transmittance for red light. The ratio of the reflectivity to the transmittance of the dielectric layer 20 for red light is greater than 1, that is, the dielectric layer 20 mainly acts as a reflector for red light. Exemplarily, the diffraction angle of blue light is in the range of 30° to 50°. Thus, the dielectric layer 20 has a relatively low reflectivity for blue light and a relatively high transmittance for blue light. The ratio of the reflectivity to the transmittance of the dielectric layer 20 for blue light is less than 1, that is, the dielectric layer 20 mainly acts as a transmitter for blue light. Exemplarily, the diffraction angle of green light is in the range of 37° to 61°. The ratio of the reflectivity to the transmittance of the dielectric layer 20 for blue light is approximately equal to 1, that is, the dielectric layer 20 mainly acts as a semi-transmissive and semi-reflective layer for green light. In this way, it can be ensured that the step change of the diffracted beams with different diffraction angles in the diffractive optical waveguide device is a uniform transition without sudden changes, thereby preventing color deviation in the diffractive optical waveguide device and achieving optimization of color uniformity.

[0050] Optionally, continuing to refer to Figure 4 , a grating structure is provided on the top surface of the diffractive waveguide layer 10, and the dielectric layer 20 is provided on the bottom surface of the diffractive waveguide layer 10 or on the top surface of the blank waveguide layer 30.

[0051] Specifically, the grating structure may include an input diffractive microstructure 101 and an output diffractive microstructure 102. Among them, the input diffractive microstructure 101 is used to efficiently couple the image beam output by the optical engine into the optical waveguide, and the output diffractive microstructure 102 is used to efficiently couple out the beam in the optical waveguide and then incident on the human eye.

[0052] It should be noted that for a two-dimensional pupil-expanding diffractive waveguide, the grating structure may further include a turning grating, and the turning grating is used to expand the pupil of the light in the horizontal direction and guide the light to the output grating.

[0053] Exemplarily, the input diffractive microstructure 101 and the output diffractive microstructure 102 may be spaced apart on the top surface of the diffractive waveguide layer 10.

[0054] As a feasible implementation manner, during the preparation process of the diffractive optical waveguide device, the dielectric layer 20 may be provided on the bottom surface of the diffractive waveguide layer 10, that is, the dielectric layer 20 is deposited on the bottom surface of the diffractive waveguide layer 10, and then the diffractive waveguide layer 10 coated with the dielectric layer 20 is fixed to the blank waveguide layer 30 to form the diffractive optical waveguide device.

[0055] As another feasible implementation, during the preparation process of the diffractive optical waveguide device, the dielectric layer 20 can be disposed on the top surface of the blank waveguide layer 30, that is, the dielectric layer 20 is deposited on the top surface of the blank waveguide layer 30, and then the blank waveguide layer 30 with the deposited dielectric layer 20 is fixed to the diffractive waveguide layer 10, thereby forming the diffractive optical waveguide device.

[0056] Optionally, continuing to refer to Figure 4 , the dielectric layer 20 is deposited on the bottom surface of the diffractive waveguide layer 10 or the top surface of the blank waveguide layer 30; the surface of the diffractive waveguide layer 10 with the deposited dielectric layer 20 is connected to the top surface of the blank waveguide layer 30 by glue bonding or molecular bonding; or, the bottom surface of the diffractive waveguide layer 10 is connected to the surface of the blank waveguide layer 30 with the deposited dielectric layer by glue bonding or molecular bonding.

[0057] Specifically, when the dielectric layer 20 is disposed on the bottom surface of the diffractive waveguide layer 10, the dielectric layer 20 is first deposited on the bottom surface of the diffractive waveguide layer 10, and then the surface of the diffractive waveguide layer 10 with the deposited dielectric layer 20 is connected to the top surface of the blank waveguide layer 30 by glue bonding or molecular bonding, thereby forming the diffractive optical waveguide device.

[0058] Specifically, when the dielectric layer 20 is disposed on the top surface of the blank waveguide layer 30, the dielectric layer 20 is first deposited on the top surface of the blank waveguide layer 30, and then the bottom surface of the diffractive waveguide layer 10 is connected to the surface of the blank waveguide layer 30 with the deposited dielectric layer by glue bonding or molecular bonding, thereby forming the diffractive optical waveguide device.

[0059] Optionally, continuing to refer to Figure 4 , the thickness H1 of the dielectric layer 20 satisfies: H1 ≤ 1.5 μm.

[0060] Exemplarily, when H1 > 1.5 μm, the thickness of the dielectric layer 20 is relatively large. On the one hand, it will increase the preparation difficulty of the dielectric layer 20, and on the other hand, it will affect the reflection and transmission of the diffracted light beam, thereby affecting the performance of the diffractive optical waveguide device. Therefore, in the embodiments of the present invention, by setting H1 ≤ 1.5 μm, the thickness of the dielectric layer 20 is appropriate. On the one hand, it can ensure matching with the coating process, and the preparation process of the dielectric layer 20 is simple. On the other hand, it can ensure the reflection and transmission of the dielectric layer 20 to the light beam, thereby affecting the performance of the diffractive optical waveguide device.

[0061] In summary, for the diffractive optical waveguide device provided by the embodiments of the present invention, by disposing a dielectric layer between the diffractive waveguide layer and the blank waveguide layer, the chromatic aberration of the diffractive optical waveguide can be improved, thereby achieving the optimization of color uniformity. In addition, the dielectric layer provided by the embodiments of the present invention is not limited to one-dimensional diffractive optical waveguides, and can also be applied to diffractive optical waveguide devices such as two-dimensional pupil-expanding diffractive optical waveguides.

[0062] Based on the same inventive concept, an embodiment of the present invention further provides an augmented reality display device, which includes an optical engine module and the diffractive optical waveguide device in the above embodiment. The optical engine module is used to emit an image beam. The augmented reality display device provided by the embodiment of the present invention also has the beneficial effects described in the above embodiment, which will not be elaborated here.

[0063] Note that the above is only the preferred embodiment of the present invention and the technical principles applied. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein. Various obvious changes, re-adjustments, and substitutions can be made by those skilled in the art without departing from the protection scope of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments. Without departing from the inventive concept of the present invention, it may also include more other equivalent embodiments, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A diffractive optical waveguide device, characterized in that: include: A diffraction waveguide layer, a dielectric layer and a white sheet waveguide layer are stacked in sequence; The diffraction waveguide layer is used to couple the image light beam output by the optical machine, diffract the image light beam to form diffraction light beams with different diffraction angles, and transmit the diffraction light beam to the dielectric layer; The dielectric layer is used to act on the diffracted light beam to form a transmitted light beam and a reflected light beam; it is also used to transmit the transmitted light beam, so that the transmitted light beam is reflected back and forth between the two surfaces of the top surface of the diffraction waveguide layer and the bottom surface of the white sheet waveguide layer, and is coupled out by the diffraction waveguide layer; it is also used to reflect the reflected light beam, so that the reflected light beam is reflected back and forth in the diffraction waveguide layer, and is coupled out by the diffraction waveguide layer; wherein the reflectivity of the dielectric layer to the diffracted light beam tends to increase with the increase of the diffraction angle of the diffracted light beam.

2. The diffractive optical waveguide device according to claim 1, characterized in that: The diffracted light beam satisfies the frustrated total reflection principle when passing through the dielectric layer.

3. The diffractive optical waveguide device according to claim 1, characterized in that: The reflectivity of the dielectric layer and the diffraction angle of the diffracted light beam satisfy the following relationship: The medium layer mainly plays a transmitting role for the diffraction light beam with a small diffraction angle, mainly plays a reflecting role for the diffraction light beam with a large diffraction angle, and mainly plays a semi-transmissive and semi-reflective role for the diffraction light beam with an intermediate diffraction angle, wherein the minimum value of the intermediate-angle diffraction angle is greater than or equal to the maximum value of the small-angle diffraction angle, and the maximum value of the intermediate-angle diffraction angle is less than or equal to the minimum value of the large-angle diffraction angle.

4. The diffractive optical waveguide device according to claim 1, characterized in that: The reflectivity of the dielectric layer and the diffraction angle of the diffracted light beam satisfy the following relationship: The reflectivity of the medium layer to the diffracted light beam with a diffraction angle between 0° and 30° is greater than 0 and less than 5%; The reflectivity of the medium layer to the diffracted light beam with a diffraction angle between 30° and 50° is greater than or equal to 1% and less than 30%; The reflectivity of the medium layer to the diffracted light beam with a diffraction angle between 50° and 90° is greater than or equal to 10% and less than 100%.

5. The diffractive optical waveguide device according to claim 1, characterized in that: The change rate of the reflectivity of the dielectric layer and the diffraction angle of the diffracted light beam satisfy the following relationship: As the diffraction angle of the diffracted light beam increases, the change rate of the reflectivity of the dielectric layer changes from a slow increase to a fast increase, and then changes from a fast increase to a slow decrease.

6. The diffractive optical waveguide device according to claim 1, characterized in that: The diffracted light beam includes at least one color light beam; the at least one color light beam includes red light, blue light and green light.

7. The diffractive optical waveguide device according to claim 1, characterized in that: The top surface of the diffraction waveguide layer is provided with a grating structure, and the dielectric layer is provided on the bottom surface of the diffraction waveguide layer or on the top surface of the white sheet waveguide layer.

8. The diffractive optical waveguide device according to claim 7, characterized in that: The dielectric layer coating is arranged on the bottom surface of the diffraction waveguide layer or on the top surface of the white sheet waveguide layer; The surface of the diffraction waveguide layer plated with the dielectric layer is connected to the top surface of the white sheet waveguide layer by glue bonding or molecular bonding; Alternatively, the bottom surface of the diffraction waveguide layer and the surface of the white sheet waveguide layer coated with the dielectric layer are connected by glue bonding or molecular bonding.

9. The diffractive optical waveguide device according to claim 1, characterized in that: The thickness H1 of the dielectric layer satisfies: H1≤1.5 μm.

10. An augmented reality display device, characterized in that: It comprises an optical-mechanical module and a diffraction optical waveguide device as described in any one of claims 1 to 9.

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