A Diffraction Optical Waveguide with a Compact Grating Distribution and an AR Device

Abstract

The present invention discloses a diffractive optical waveguide with a compact grating distribution, an AR device, a diffractive optical waveguide sheet; an entrance pupil region; at least one turning region, disposed on the side at the same horizontal height as the entrance pupil region, and the turning region is located on the +1 order diffracted light path of the entrance pupil region and / or the second turning region is located on the -1 order diffracted light path of the entrance pupil region; at least one pupil expansion region, located on the path of the sum of the grating vectors of the entrance pupil diffraction grating and the turning diffraction grating; at least one exit pupil region, located on the path of the sum of the grating vectors of the entrance pupil diffraction grating, the turning diffraction grating and the pupil expansion diffraction grating. The present invention adopts a four-section diffractive grating distribution, which can make the structure of the grating region more compact while maintaining the diffraction efficiency, and can be compatible with waveguide modules of bilateral diffraction at the same time.

Description

Technical Field

[0001] The present invention relates to the technical field of AR display, and particularly to a diffractive optical waveguide with a compact grating distribution and an AR device. Background Art

[0002] With the progress of imaging technology, people's demand for immersive experiences is getting higher and higher. In recent years, the development of VR / AR technology has gradually met people's pursuit of visual experiences. Head-mounted devices can free people's hands, reduce dependence on screens, and at the same time create better visual effects. For head-mounted devices, near-eye display is the key technology, and imaging quality and thinness are the main considerations. A near-eye display system generally consists of an image far-near light transmission system. The image screen emitted by the image source is transmitted to the human eye through the optical transmission system. Here, different from VR's blocking of the external environment, AR requires a certain transmittance so that the wearer can see the external environment while seeing the image screen.

[0003] For the optical transmission system, there are many solutions in the industry. For example, free space optics, free-form optics, and display optical waveguides. Among them, the optical waveguide technology is significantly superior to other optical solutions due to its large eye box and thin and light characteristics, and has become the mainstream path for major companies.

[0004] Currently, there are two ways of grating distribution on most diffractive optical waveguides on the market. One is the three-stage diffraction of entrance pupil - pupil expansion - exit pupil, such as Hololens, and the other is the two-stage diffraction of entrance pupil - exit pupil, such as Wave optics. The three-stage diffraction uses three one-dimensional gratings to perform lateral and longitudinal pupil expansion respectively, and finally emits light. The diffraction efficiency is relatively high, but the overall area is relatively large. The other is the two-stage diffraction, that is, using one one-dimensional grating and one two-dimensional grating. The two-axis pupil expansion is simultaneously performed in the two-dimensional grating, and the overall area is more compact, but the diffraction efficiency is lower.

[0005] For the three-stage grating distribution, it is easy to see that the area occupied by the grating region is relatively large, especially in the y-axis direction. The distance between the exit pupil center and the upper edge of the waveguide plate is relatively large, and it is easy to appear bulky and unaesthetic when forming a product. For the two-stage diffractive optical waveguide, the grating distribution is compact, and the overall shape is more similar to that of ordinary glasses. However, the low diffraction efficiency of the two-dimensional grating is a serious defect for the two-stage diffractive optical waveguide. Summary of the Invention

[0006] Embodiments of the present invention provide a diffractive optical waveguide with a compact grating distribution and an AR device, aiming to improve the existing grating distribution and make the structure of the grating region more compact while maintaining the diffraction efficiency.

[0007] An embodiment of the present invention provides a diffractive optical waveguide with a compact grating distribution, including:

[0008] A diffractive optical waveguide sheet;

[0009] An entrance pupil area, adopting an entrance pupil diffractive grating;

[0010] At least one turning area, adopting a turning diffractive grating, the turning area is arranged on the side at the same horizontal height as the entrance pupil area, and the turning area is located on the +1 order diffractive optical path of the entrance pupil area and / or the second turning area is located on the -1 order diffractive optical path of the entrance pupil area; wherein, the +1 order diffractive optical path is the diffractive optical path of the entrance pupil area towards the positive x-axis direction, and the -1 order diffractive optical path is the diffractive optical path of the entrance pupil area towards the negative x-axis direction;

[0011] At least one pupil expansion area, adopting a pupil expansion diffractive grating, the pupil expansion area is arranged below the turning area and is located on the path of the grating vector sum of the entrance pupil diffractive grating and the turning diffractive grating;

[0012] At least one exit pupil area, adopting an exit pupil diffractive grating, the exit pupil area is arranged on the side of the turning area away from the entrance pupil area and is located on the path of the grating vector sum of the entrance pupil diffractive grating, the turning diffractive grating and the pupil expansion diffractive grating;

[0013] Light is coupled into the diffractive optical waveguide sheet from the entrance pupil area, the direction of the light is rotated through the turning area, and then is coupled out of the diffractive optical waveguide sheet after passing through the pupil expansion area and the exit pupil area in sequence.

[0014] Further, the diffractive optical waveguide is a binocular diffractive optical waveguide;

[0015] The binocular diffractive optical waveguide includes the binocular-shaped diffractive optical waveguide sheet and the entrance pupil area arranged at the middle position of the diffractive optical waveguide sheet, and the binocular diffractive optical waveguide further includes:

[0016] Two turning areas, the two turning areas are the first turning area and the second turning area symmetrically arranged on both sides of the entrance pupil area, the first turning area is located on the +1 order diffractive optical path of the entrance pupil area, and the second turning area is located on the -1 order diffractive optical path of the entrance pupil area;

[0017] Two pupil expansion areas, the two pupil expansion areas are the first pupil expansion area corresponding to the first turning area and the second pupil expansion area corresponding to the second turning area;

[0018] Two exit pupil areas, the two exit pupil areas are the first exit pupil area corresponding to the first pupil expansion area and the second exit pupil area corresponding to the second pupil expansion area.

[0019] Furthermore, the diffractive optical waveguide is a monocular diffractive optical waveguide;

[0020] The monocular diffractive optical waveguide includes the monocular diffractive optical waveguide sheet and the entrance pupil region arranged at the side position of the diffractive optical waveguide sheet. The monocular diffractive optical waveguide further includes:

[0021] A turning region, which is a turning region on the +1 order diffractive optical path or the -1 order diffractive optical path of the entrance pupil region;

[0022] An expanding pupil region, which is located below the turning region;

[0023] An exit pupil region, which is located on the side of the turning region away from the entrance pupil region.

[0024] Furthermore, the grating distributions, sizes, and diffractive characteristics of the +1 order diffractive optical path and the -1 order diffractive optical path are mirror symmetric.

[0025] Furthermore, the region diameter of the entrance pupil region is D11, where the value range of D11 is 3 - 7 mm;

[0026] The maximum size of the turning region on the x-axis is L21, and the maximum size on the y-axis is W21, where the values of L21 and W21 are both 1 - 2 times D11;

[0027] The minimum size of the expanding pupil region on the x-axis is L31a, the maximum size is L31b, and the maximum size on the y-axis is W31, where L31b > L31a, the value of L31 is 2 - 4 times D11, and the value of W31 is 2 - 6 times D11;

[0028] The maximum size of the exit pupil region on the x-axis is L41, and the maximum size on the y-axis is W41, where the value of L41 is 4 - 7 times D11, and the value of W41 is 2 - 5 times D11;

[0029] Furthermore, the upper edge of the expanding pupil region is parallel to the lower edge of the turning region, and the interval is th, where the value of th is 0 - 1 mm, and the length of the upper edge of the expanding pupil region is greater than or equal to the length of the lower edge of the turning region;

[0030] The geometric center of the exit pupil region and the geometric center of the entrance pupil region are spaced by L in the x direction and W in the y-axis direction, where the value of L is half of the human eye pupil distance, and the value of W is 0.5 - 2 times D11.

[0031] Furthermore, the grating characteristics of the +1 order diffractive optical path and the -1 order diffractive optical path are mirror symmetric;

[0032] Among them, on the +1 order diffraction optical path, the entrance pupil diffraction grating has an entrance pupil grating vector, and the grating direction of the entrance pupil diffraction grating is the first included angle between the entrance pupil grating vector and the x-axis; wherein, the first included angle is -30° to 30°, and the period of the entrance pupil diffraction grating is 300 nm to 450 nm;

[0033] The turning diffraction grating has a turning grating vector, and the grating direction of the turning diffraction grating is the second included angle between the turning grating vector and the x-axis; wherein, the second included angle is -120° to -150°, and the turning diffraction grating is 200 nm to 400 nm;

[0034] The pupil-expanding diffraction grating has a pupil-expanding grating vector, and the grating direction of the pupil-expanding diffraction grating is the third included angle between the pupil-expanding grating vector and the x-axis; wherein, the third included angle is 30° to 60°, and the period of the pupil-expanding diffraction grating is 200 nm to 400 nm;

[0035] The exit pupil diffraction grating has an exit pupil grating vector, and the grating direction of the exit pupil diffraction grating is the fourth included angle between the exit pupil grating vector and the x-axis; wherein, the fourth included angle is -150° to -180° and / or 150° to 180°, and the period of the exit pupil diffraction grating is 300 nm to 450 nm.

[0036] Further, an efficiency partition is selectively set in the turning area;

[0037] Efficiency partitions are set in both the pupil-expanding area and the exit pupil area.

[0038] There are 10 to 15 efficiency partitions respectively set in the efficiency partition of the pupil-expanding area and the efficiency partition of the exit pupil area, and the diffraction efficiency gradually increases in the grating direction.

[0039] Further, the entrance pupil diffraction grating, the turning diffraction grating, the pupil-expanding diffraction grating, and the exit pupil diffraction grating are all symmetric structure gratings or tilted gratings, and the grating forms of the entrance pupil diffraction grating, the turning diffraction grating, the pupil-expanding diffraction grating, and the exit pupil diffraction grating are surface relief gratings or volume holographic gratings.

[0040] Further, the turning area is a reflecting surface, and the included angle between the normal line of the reflecting surface and the diffracted light in the entrance pupil area is 30° to 60°.

[0041] An embodiment of the present invention also provides an AR device, including the diffractive optical waveguide with the compact grating distribution as described in any one of the above.

[0042] An embodiment of the present invention provides a diffractive optical waveguide with a compact grating distribution and an AR device. The diffractive optical waveguide adopts a four-segment diffractive grating distribution, including an entrance pupil diffractive grating, a turning diffractive grating, an expanding pupil diffractive grating, and an exit pupil diffractive grating. After light is coupled into the waveguide from the entrance pupil region, it first passes through the turning diffractive grating to rotate the light direction by 90°, then sequentially passes through the expanding pupil region and the exit pupil region, and finally is coupled out of the waveguide from the exit pupil region and enters the human eye. Based on the three-segment diffraction, the embodiment of the present invention improves the grating distribution, making the structure of the grating region more compact while maintaining the diffraction efficiency, and at the same time being compatible with the waveguide module of bilateral diffraction. Description of the Drawings

[0043] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0044] Figure 1 Schematic structural diagram of a diffractive optical waveguide with a compact grating distribution provided by an embodiment of the present invention;

[0045] Figure 2 Schematic unilateral structure diagram of a diffractive optical waveguide with a compact grating distribution provided by an embodiment of the present invention;

[0046] Figure 3 Schematic size diagram of a unilateral structure of a diffractive optical waveguide with a compact grating distribution provided by an embodiment of the present invention;

[0047] Figure 4 Schematic grating characteristic diagram of a unilateral structure of a diffractive optical waveguide with a compact grating distribution provided by an embodiment of the present invention;

[0048] Figure 5 Schematic diagram of the regional diffraction efficiency distribution of a unilateral structure of a diffractive optical waveguide with a compact grating distribution provided by an embodiment of the present invention;

[0049] Figure 6 K-space diagram of waveguide diffraction of a diffractive optical waveguide with a compact grating distribution provided by an embodiment of the present invention;

[0050] Figure 7 Schematic diffraction optical path diagram of a diffractive optical waveguide with a compact grating distribution provided by an embodiment of the present invention;

[0051] Figure 8 Schematic grating characteristic diagram of a diffractive optical waveguide with a compact grating distribution provided by an embodiment of the present invention;

[0052] Figure 9Another schematic diagram of one-sided structure of a diffractive optical waveguide with a compact grating distribution provided by an embodiment of the present invention. Detailed implementation manners

[0053] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are only a part rather than all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0054] It should be understood that when used in this specification and the appended claims, the terms "comprises" and "comprising" indicate the presence of the described features, wholes, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or their combinations.

[0055] It should also be understood that the terms used in this specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in this specification of the present invention and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an", and "the" are intended to include the plural forms.

[0056] It should be further understood that the term " / and" as used in this specification of the present invention and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0057] Please refer to the following Figure 1 , an embodiment of the present invention provides a diffractive optical waveguide with a compact grating distribution, including:

[0058] Diffractive optical waveguide sheet 1000;

[0059] Entrance pupil region 1011, adopting an entrance pupil diffraction grating;

[0060] At least one turning region (such as Figure 1 1021 and 1022 in Figure 2 1021 in

[0061] At least one pupil expansion region (such as 1031 and 1032 in Figure 1 or 1031 in Figure 2 ) uses a pupil expansion diffraction grating. The pupil expansion region is disposed below the turning region and on the path of the sum of the grating vectors of the entrance pupil diffraction grating and the turning diffraction grating;

[0062] At least one exit pupil region (such as 1041 and 1042 in Figure 1 or 1041 in Figure 2 ) uses an exit pupil diffraction grating. The exit pupil region is disposed on the side of the turning region away from the entrance pupil region 1011 and on the path of the sum of the grating vectors of the entrance pupil diffraction grating, the turning diffraction grating, and the pupil expansion diffraction grating;

[0063] Light is coupled into the diffractive optical waveguide sheet from the entrance pupil region 1011, the direction of the light is rotated through the turning region, and then coupled out of the diffractive optical waveguide sheet after passing through the pupil expansion region and the exit pupil region in sequence.

[0064] In this embodiment, the shown diffractive optical waveguide includes a diffractive optical waveguide sheet 1000. An entrance pupil region 1011, a turning region, a pupil expansion region, and an exit pupil region are provided on the diffractive optical waveguide sheet 1000. Among them, the entrance pupil region 1011, the turning region, the pupil expansion region, and the exit pupil region constitute a waveguide grating distribution of four-stage diffraction. Two turning regions, pupil expansion regions, and exit pupil regions are provided, which together with the entrance pupil region form a binocular waveguide.

[0065] This embodiment proposes a waveguide grating distribution of four-stage diffraction. Briefly speaking, it changes the traditional up-and-down distribution of gratings to a left-and-right distribution to compress the length of the y-axis. At the same time, in order to take into account both monocular waveguides and binocular waveguides, the interval between the entrance pupil center and the exit pupil center is basically unique, that is, half of the IPD (IPD is the interpupillary distance of the human eye, generally between 60 and 70 mm). Different from the structure of the existing gratings with a left-and-right distribution, the pupil expansion region in this embodiment is not placed directly below the entrance pupil region because this structure cannot be compatible with bilateral diffraction modules (space for the bridge of the nose needs to be reserved). At the same time, the grating characteristics of the two grating regions of the turning region and the pupil expansion region can be the same or different to provide more grating combination characteristics.

[0066] The existing three-stage diffractive waveguide has low space utilization rate, and the two-stage diffraction efficiency is not ideal. In this embodiment, on the premise of ensuring the diffraction efficiency, through the way of four-stage diffraction, the grating space is extremely compressed, making the overall structure more flattened and more in line with the structure of traditional glasses.

[0067] In a specific embodiment, in combination with Figure 1 , the diffractive optical waveguide is a binocular diffractive optical waveguide;

[0068] The binocular diffractive waveguide includes the binocular-shaped diffractive optical waveguide sheet 1000 and the entrance pupil region 1011 disposed at the middle position of the diffractive optical waveguide sheet 1000. The binocular diffractive waveguide further includes:

[0069] Two turning regions, which are the first turning region 1021 and the second turning region 1022 symmetrically disposed on both sides of the entrance pupil region 1011. The first turning region 1021 is located on the +1 order diffractive optical path of the entrance pupil region 1011, and the second turning region 1022 is located on the -1 order diffractive optical path of the entrance pupil region 1011;

[0070] Two pupil expansion regions, which are the first pupil expansion region 1031 corresponding to the first turning region 1021 and the second pupil expansion region 1032 corresponding to the second turning region 1022;

[0071] Two exit pupil regions, which are the first exit pupil region 1041 corresponding to the first pupil expansion region 1031 and the second exit pupil region 1042 corresponding to the second pupil expansion region 1032.

[0072] In another specific embodiment, in combination with Figure 2 , the diffractive optical waveguide is a monocular diffractive waveguide;

[0073] The monocular diffractive waveguide includes the monocular-shaped diffractive optical waveguide sheet 1000 and the entrance pupil region 1011 disposed at the side position of the diffractive optical waveguide sheet 1000. The monocular diffractive waveguide further includes:

[0074] One turning region, which is a turning region (such as 1021 in Figure 2 ) located on the +1 order diffractive optical path or the -1 order diffractive optical path of the entrance pupil region 1011;

[0075] One pupil expansion region (such as 1031 in Figure 2 ), located below the turning region;

[0076] One exit pupil region (such as 1041 in Figure 2 ), located on the side of the turning region away from the entrance pupil region.

[0077] The diffractive optical waveguide sheet 1000 with four-segment diffraction can specifically be a binocular diffractive module, that is, the +1 order diffracted light beam in the entrance pupil region 1011 is used to transmit an image for one eye, and the -1 order diffracted light beam in the entrance pupil region 1011 is used to transmit an image for the other eye to achieve the single light engine binocular display effect. At the same time, the diffractive optical waveguide sheet 1000 with four-segment diffraction can also be a monocular diffractive module, that is, the +1 order diffracted light beam in the entrance pupil region 1011 is used to transmit an image for one eye to achieve the single light engine monocular display effect.

[0078] Furthermore, the grating distribution, size, and diffraction characteristics of the +1 order diffractive optical path and the -1 order diffractive optical path are mirror-symmetrical. Among them, 1 is the diffraction in the positive x-axis direction at the entrance pupil, also known as the +1 order diffraction, and is also the right region in the binocular waveguide; -1 is the diffraction in the negative x-axis direction at the entrance pupil, also known as the -1 order diffraction, and is also the left region in the binocular waveguide.

[0079] In one embodiment, the diameter of the region of the entrance pupil region 1011 is D11, where the value range of D11 is 3 - 7 mm;

[0080] The maximum size of the turning region on the x-axis is L21, and the maximum size on the y-axis is W21, where the values of L21 and W21 are both 1 - 2 times D11;

[0081] The minimum size of the pupil expansion region on the x-axis is L31a, the maximum size is L31b, and the maximum size on the y-axis is W31, where L31b > L31a, the value of L31 is 2 - 4 times D11, and the value of W31 is 2 - 6 times D11;

[0082] The maximum size of the exit pupil region on the x-axis is L41, and the maximum size on the y-axis is W41, where the value of L41 is 4 - 7 times D11, and the value of W41 is 2 - 5 times D11;

[0083] Furthermore, the upper edge of the pupil expansion region and the lower edge of the turning region are parallel, with a spacing of th, where the value of th is 0 - 1 mm, and the length of the upper edge of the pupil expansion region is greater than or equal to the length of the lower edge of the turning region;

[0084] The geometric center of the exit pupil region and the geometric center of the entrance pupil region have a spacing of L in the x direction and a spacing of W in the y-axis direction, where the value of L is half of the human eye pupil distance, and the value of W is 0.5 - 2 times D11.

[0085] In this embodiment, as Figure 3 shown, taking the +1 order diffraction direction of the entrance pupil as an example (defining the +1 order diffraction direction of the entrance pupil as the positive x-axis direction), the diameter of the entrance pupil region 1011 is D11, with a value between 3 - 7 mm.

[0086] The first turning region 1021 is disposed on the +1 order diffraction optical path of the entrance pupil region 1011. Its maximum dimension on the x-axis is L21, and its maximum dimension on the y-axis is W21. The values of L21 and W21 can be 1 to 2 times D11.

[0087] The first pupil expansion region 1031 is disposed below the first turning region 1021, specifically on the path of the sum of the grating vectors of the entrance pupil grating and the turning grating. The minimum dimension of the first pupil expansion region 1031 on the x-axis is L31a, the maximum dimension is L31b, and the maximum dimension on the y-axis is W31, where L31b > L31a. The upper edge of the first pupil expansion region 1031 is parallel to the lower edge of the first turning region 1021, and the interval is th, where the value of th is between 0 and 1 mm, and the length of the upper edge of the first pupil expansion region 1031 shall not be less than the lower edge of the first turning region 1021. The value of L31 can be 2 to 4 times D11, and the value of W31 can be 2 to 6 times D11.

[0088] The first exit pupil region 1041 is disposed on the right side of the pupil expansion region, specifically on the path of the sum of the grating vectors of the entrance pupil, turning, and pupil expansion gratings. The maximum dimension of the first exit pupil region 1041 on the x-axis is L41, and the maximum dimension on the y-axis is W41. The value of L41 can be 4 to 7 times D11, and the value of W41 can be 2 to 5 times D11. The geometric center of the first exit pupil region 1041 is spaced from the geometric center of the entrance pupil region 1011 by L in the x direction and by W in the y-axis direction. The value of L can be half of the IPD, and the value of W can be 0.5 to 2 times D11.

[0089] It should be noted that in this embodiment, only the maximum dimensions of each region in the x and y axis directions are limited, and the specific shape is not limited.

[0090] In one embodiment, the grating characteristics of the +1 order diffraction optical path and the -1 order diffraction optical path are mirror symmetric;

[0091] Among them, on the +1 order diffraction optical path, the entrance pupil diffraction grating has an entrance pupil grating vector, and the grating direction of the entrance pupil diffraction grating is the first included angle between the entrance pupil grating vector and the x-axis; among them, the first included angle is -30° to 30°, and the period of the entrance pupil diffraction grating is 300 nm to 450 nm;

[0092] The turning diffraction grating has a turning grating vector, and the grating direction of the turning diffraction grating is the second included angle between the turning grating vector and the x-axis; among them, the second included angle is -120° to -150°, and the turning diffraction grating is 200 nm to 400 nm;

[0093] The pupil-expanding diffraction grating has a pupil-expanding grating vector, and the grating direction of the pupil-expanding diffraction grating is the third included angle between the pupil-expanding grating vector and the x-axis; wherein, the third included angle is 30° to 60°, and the period of the pupil-expanding diffraction grating is 200 nm to 400 nm;

[0094] The exit pupil diffraction grating has an exit pupil grating vector, and the grating direction of the exit pupil diffraction grating is the fourth included angle between the exit pupil grating vector and the x-axis; wherein, the fourth included angle is -150° to -180° and / or 150° to 180°, and the period of the exit pupil diffraction grating is 300 nm to 450 nm.

[0095] In this embodiment, as Figure 4 shown, taking the diffraction region in the +1st order diffraction direction of the entrance pupil as an example:

[0096] An entrance pupil diffraction grating DOE11 is provided in the entrance pupil region 1011, and the grating vector is The grating direction θ11 is the included angle with the x-axis, and the value can be between -30° and 30°, and the period is d11, and the value can be between 300 and 450 nm;

[0097] A turning diffraction grating DOE21 is provided in the first turning region 1021, and the grating vector is The grating direction θ21 is the included angle with the x-axis, and the value can be between -120° and -150°, and the period is d21, and the value can be between 200 and 400 nm;

[0098] A pupil-expanding diffraction grating DOE31 is provided in the first pupil-expanding region 1031, and the grating vector is The grating direction θ31 is the included angle with the x-axis, and the value can be between 30° and 60°, and the period is d31, and the value is between 200 and 400 nm;

[0099] An exit pupil diffraction grating DOE41 is provided in the first exit pupil region 1041, and the grating vector is The grating direction θ41 is the included angle with the x-axis, and the value can be between -150° and -180° and 150° and 180°, and the period is d41, and the value is between 300 and 450 nm.

[0100] Here, in the diffraction region in the -1st order diffraction direction of the entrance pupil, the grating directions of the diffraction gratings in each region are mirror-symmetrical to the grating directions of the diffraction gratings in the corresponding regions in the +1st order diffraction optical path, and the grating periods are the same as those in the corresponding regions.

[0101] In one embodiment, an efficiency partition is selectively provided in the turning region;

[0102] Both the pupil expansion region and the exit pupil region are provided with efficiency sub-regions.

[0103] Furthermore, the efficiency sub-regions of the pupil expansion region and the efficiency sub-regions of the exit pupil region are respectively provided with 10 to 15.

[0104] In this embodiment, in the schematic diagram of the diffraction efficiency distribution of each region as shown in Figure 5 , the color of the filled region gradually becomes darker from light, and the corresponding diffraction efficiency gradually increases. The sub-regional diffraction efficiency is mainly to improve the brightness uniformity of the outgoing image. Based on the principle of pupil expansion of the diffraction waveguide, during the process of the light beam propagating in the waveguide, each time it contacts the grating, a diffraction occurs, and a part of the energy in the main light beam will change the propagation direction due to diffraction and become a sub-light beam propagating towards another diffraction region, while the main light beam continues to propagate by total reflection in the original direction. Each total reflection of the main light beam will contact the grating, thereby generating diffraction and splitting off part of the energy. If the overall diffraction efficiency of the grating remains unchanged, the energy of the sub-light beam split off each time will become less and less, resulting in an obvious brightness gradient in the finally outgoing image. To optimize this problem, the waveguide grating usually sets efficiency sub-regions. The diffraction efficiency of the front end of the grating (the position where the light beam enters the grating) is relatively low, and the diffraction efficiency of the rear end of the grating (the position where the light beam leaves the grating) is the highest. The diffraction efficiency gradually increases step by step from the front end to the rear end of the grating, so that the energy of all the diffracted sub-light beams finally remains highly consistent.

[0105] In this embodiment, the entrance pupil region 1011 does not need to be provided with efficiency sub-regions. The first turning region 1021 needs to diffract all the light beams coming from the entrance pupil to the first pupil expansion region 1031, so its diffraction efficiency needs to be set quite high. Here, efficiency sub-regions can be set or not. The first pupil expansion region 1031 needs to be provided with efficiency sub-regions. As shown in Figure 5 , the efficiency gradually increases from top to bottom. Preferably, for the brightness uniformity of the outgoing image, 10 to 15 efficiency sub-regions can be set. The first exit pupil region 1041 also needs to be provided with efficiency sub-regions. As shown in Figure 5 , the efficiency gradually increases from left to right. Preferably, for the brightness uniformity of the outgoing image, 10 to 15 efficiency sub-regions can be set.

[0106] Of course, in this embodiment, the grating efficiency sub-regions of the entrance pupil -1st order diffraction region and the corresponding regions of the +1st order diffraction region are mirror symmetric.

[0107] The specific principle of the four-stage diffraction provided by the embodiment of the present invention is as follows:

[0108] Combined with Figure 6 , according to the grating equation, k can be expressed as: In the formula, α and β represent the incident angle and the diffraction angle respectively, n1 and n2 represent the refractive indices of air and glass respectively, and λ is the wavelength of the incident light. is the grating vector, including the grating period and the grating direction. It can be seen from the formula that the light propagation in the waveguide needs to satisfy the total reflection formula, that is Therefore, BND1 is the total reflection boundary condition with a radius equal to 1; at the same time, the diffraction angle shall not be greater than 90°, that is Therefore, BND2 is the maximum value of the wave vector with a radius less than or equal to n2.

[0109] BND1 represents the first boundary for satisfying the total internal reflection (TIR) standard in the diffractive optical waveguide sheet 1000. BND2 represents the second boundary of the maximum wave vector in the diffractive optical waveguide sheet 1000. The maximum wave vector can be determined by the refractive index of the waveguide sheet. Only when the wave vector of the light is in the region ZONE1 between the first boundary BND1 and the second boundary BND2 can the light propagate in the waveguide sheet. If the wave vector of the light is outside the region ZONE1, the light may leak out of the waveguide sheet or not propagate at all.

[0110] Taking the entrance pupil +1 order diffraction path as an example, light of a specific wavelength can propagate in the waveguide sheet along the right path. The wave vector of the input light IN0 can exist in a region BOX00 of the wave vector space defined by the initial wave vectors kx and ky. According to the wave vector formula, each point in the region BOX00 can be represented by the formula which represents the wave vectors of the light waves corresponding to different incident angles of an input image IMG00.

[0111] The grating period (d) and the grating direction (θ) of the diffraction grating can be determined by the grating vector V of the diffraction grating. The grating vector V can be defined as a vector having a direction perpendicular to the diffracted ray of the diffraction grating and an amplitude given by 2π / d, where d is the grating period (i.e., the fringe spacing).

[0112] The entrance pupil region 1011 is provided with an entrance pupil diffraction grating DOE11, and there is a grating vector in DOE11 having a direction θ11 and a magnitude 2π / d11; the first turning region 1021 is provided with a turning diffraction grating DOE21, and there is a grating vector in DOE21 having a direction θ21 and a magnitude 2π / d21; the first pupil expansion region 1031 is provided with a pupil expansion diffraction grating DOE31, and there is a grating vector in DOE31 having a direction θ31 and a magnitude 2π / d31; the first exit pupil region 1041 is provided with an exit pupil diffraction grating DOE41, and there is a grating vector in DOE41 having a direction θ41 and a magnitude 2π / d41.

[0113] The grating period (d) and direction (θ) of the grating vector can satisfy the vector sum That is, the conduction of the wave vector forms a closed path. Where i is the regional position identifier, such as 1 = entrance pupil, 2 = turning, 3 = pupil expansion, 4 = exit pupil; j is the path identifier, such as 1 = entrance pupil + first-order diffraction path, 2 = entrance pupil - first-order diffraction path (for example, the wave vector sum of the entrance pupil + first-order diffraction path is ). The wave vector sum being 0 in the wave vector space is a necessary condition to ensure the same dispersion of the exit pupil beam and the entrance pupil beam.

[0114] The grating period (d) of the optical units DOE11, DOE21, DOE31, DOE41 and the direction (θ) of the diffraction grating can be selected such that the regions BOX00 and BOX41 in the wave vector space are almost coincident. At the same time, for the wavelengths of the three colors RGB, the wave vectors of the regions BOX11, BOX21 and BOX31 are all within the region ZONE1 defined by the boundaries BND1 and BND2 to satisfy the total internal reflection (TIR) condition.

[0115] For a monocular four-stage diffractive waveguide module, its specific waveguide process is as follows:

[0116] Combined with Figure 7 , the incident light IN0 is coupled into the waveguide from the wave vector region BOX00 and conducts in the direction of the grating vector to form the first diffracted light B11, and the wave vector region BOX00, the entrance pupil region 1011 and the diffraction grating DOE11 coincide; the first diffracted light B11 diffracts at the wave vector region BOX11 to generate the second diffracted light B21, and the second diffracted light B21 conducts in the direction of the grating vector sum and the wave vector region BOX11, the first turning region 1021 and the diffraction grating DOE21 coincide; the second diffracted light B21 diffracts at the wave vector region BOX21 to generate the third diffracted light B31, and the third diffracted light B31 conducts in the direction of the grating vector sum and the wave vector region BOX21, the first pupil expansion region 1031 and the diffraction grating DOE31 coincide; the third diffracted light B31 diffracts at the wave vector region BOX31 to generate the fourth diffracted light OUT1 and is coupled out of the waveguide sheet. The fourth diffracted light OUT1 conducts in the direction of the grating vector sum in the wave vector space, and the wave vector region BOX41, the first exit pupil region 1041 and the diffraction grating DOE41 coincide.

[0117] The grating period (d) and grating direction (θ) of the optical units DOE11, DOE21, DOE31, DOE41 can be selected such that the regions BOX00 and BOX41 in the wave vector space are almost coincident, that is, make Couple the fourth diffracted light OUT1 out of the waveguide and keep it in the same direction as or in a mirror image relationship with the wave vector direction of the incident light IN0. At the same time, for the wavelengths of the three colors RGB, the wave vectors of the regions BOX11, BOX21, and BOX31 are all within the region ZONE1 defined by the boundaries BND1 and BND2 to satisfy the total internal reflection (TIR) condition.

[0118] For a binocular four-section diffractive waveguide module, the +1 order diffractive region is predefined as the right region of the waveguide, and the -1 order diffractive region is predefined as the left region of the waveguide. The specific waveguide process is as follows:

[0119] The incident light IN0 is coupled into the diffractive optical waveguide sheet 1000 from the wave vector region BOX00, generating two diffracted lights. One of them propagates in the direction of the grating vector to form the first diffracted light B11 on the right side. The wave vector region BOX00, the entrance pupil region 1011, and the entrance pupil diffractive grating DOE11 coincide with each other; the first diffracted light B11 on the right side diffracts at the wave vector region BOX11, generating the second diffracted light B21 on the right side. The second diffracted light B21 on the right side propagates in the direction of the grating vector and. The wave vector region BOX11, the first turning region 1021, and the turning diffractive grating DOE21 coincide with each other; the second diffracted light B21 on the right side diffracts at the wave vector region BOX21, generating the third diffracted light B31 on the right side. The third diffracted light B31 on the right side propagates in the direction of the grating vector and. The wave vector region BOX21, the first pupil expansion region 1031, and the pupil expansion diffractive grating DOE31 coincide with each other; the third diffracted light B31 on the right side diffracts at the wave vector region BOX31, generating the fourth diffracted light OUT1 on the right side and coupling it out of the diffractive optical waveguide sheet 1000. The fourth diffracted light OUT1 on the right side propagates in the wave vector space in the direction of the grating vector and. The wave vector region BOX41, the first exit pupil region 1041, and the diffractive grating DOE41 coincide with each other.

[0120] The incident light IN0 is coupled into the diffractive optical waveguide chip 1000 from the wave vector region BOX00, generating two diffracted lights. The other diffracted light is conducted in the direction of the grating vector, forming the first diffracted light B12 on the left. The wave vector region BOX00, the entrance pupil region 1011, and the entrance pupil diffractive grating DOE11 coincide with each other. The first diffracted light B12 on the left diffracts at the wave vector region BOX12, generating the second diffracted light B22 on the left. The second diffracted light B22 on the left is conducted in the direction of the grating vector and [direction]. The wave vector region BOX12, the second turning region 1022, and the turning diffractive grating DOE22 coincide with each other. The second diffracted light B22 on the left diffracts at the wave vector region BOX22, generating the third diffracted light B32 on the left. The third diffracted light B32 on the left is conducted in the direction of the grating vector and [direction]. The wave vector region BOX22, the second pupil expansion region 1032, and the pupil expansion diffractive grating DOE32 coincide with each other. The third diffracted light B32 on the left diffracts at the wave vector region BOX32, generating the fourth diffracted light OUT2 on the left and coupling it out of the diffractive optical waveguide chip 1000. The fourth diffracted light OUT2 on the left is conducted in the wave vector space in the direction of the grating vector and [direction]. The wave vector region BOX42, the second exit pupil region 1042, and the exit pupil diffractive grating DOE42 coincide with each other.

[0121] The grating periods (d) and grating directions (θ) of the optical elements DOE11, DOE21, DOE22, DOE31, DOE32, DOE41, and DOE42 can be selected such that the regions BOX00, BOX41, and BOX42 in the wave vector space almost coincide, that is, The fourth diffracted light OUT1 on the right and the fourth diffracted light OUT2 on the left are coupled out of the waveguide and are kept consistent with the wave vector direction of the incident light IN0 or are in a mirror image relationship.

[0122] At the same time, for the wavelengths of the three colors RGB, the wave vectors of the regions BOX11 and BOX12, the regions BOX21 and BOX22, and the regions BOX31 and BOX32 are all within the region ZONE1 defined by the boundaries BND1 and BND2 to satisfy the total internal reflection (TIR) condition.

[0123] In a specific embodiment, as Figure 8 shown, the wave vector regions BOX11 and BOX31 coincide in the wave vector space. In this case, the grating characteristics of the first turning region 1021 and the first pupil expansion region 1031 are the same. In particular, when an oblique grating is used, the turning diffractive grating DOE21 of the first turning region 1021 and the pupil expansion diffractive grating DOE31 of the first pupil expansion region 1031 have the same grating period and opposite main diffraction directions.

[0124] Further, the entrance pupil diffraction grating, the turning diffraction grating, the pupil expansion diffraction grating, and the exit pupil diffraction grating are all symmetric structure gratings or tilted gratings. The gratings on both sides of the binocular diffraction module are symmetric structures, and all corresponding grating regions, grating characteristics, and region sizes are in a mirror-symmetric relationship. Also, the diffraction grating in this embodiment can be a surface relief grating or a volume holographic grating. In addition, the diffractive optical waveguide sheet 1000 can be made of glass or plastic, and it needs to have the characteristics of high hardness and high flatness.

[0125] In one embodiment, the turning region is a reflecting surface, and the angle between the normal of the reflecting surface and the diffracted light in the entrance pupil region is 30° to 60°.

[0126] In this embodiment, as Figure 9 shown, the first turning region 1021 can be replaced with a reflecting surface 1121. Correspondingly, the second turning region 1022 can also be replaced with a reflecting surface. The use of the reflecting surface 1121 can reduce the processing cost of the template, and at the same time, it can effectively reflect more first diffracted light B11 into the first pupil expansion region 1031 and prevent leakage into the first exit pupil region 1041 to form ghost images. In addition, the angle between the normal of the reflecting surface 1121 and the first diffracted light B11 is 30° to 60°.

[0127] An embodiment of the present invention also provides an AR device, including a diffractive optical waveguide with the compact grating distribution as described in any one of the above.

[0128] It can be understood that the AR device described in this embodiment can specifically be AR glasses. Of course, in other embodiments, it may also be other device equipment, such as in-vehicle devices, etc.

[0129] The various embodiments in the specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The same or similar parts among the various embodiments can be referred to each other. For the system disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the description of the method part. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the principle of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application.

[0130] It should also be noted that in this specification, relational terms such as first and second are only used to separate one entity or operation from another entity or operation area, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the element.

Claims

1. A diffraction optical waveguide with a compact grating distribution, characterized in that, Comprising: A diffractive optical waveguide sheet; An entrance pupil region, with an entrance pupil diffractive grating; At least one turning region, with a turning diffractive grating, the turning region being arranged on the side at the same horizontal height as the entrance pupil region, and the first turning region being on the +1st order diffractive optical path of the entrance pupil region and / or the second turning region being on the -1st order diffractive optical path of the entrance pupil region; wherein, the +1st order diffractive optical path is the diffractive optical path of the entrance pupil region towards the positive x-axis direction, and the -1st order diffractive optical path is the diffractive optical path of the entrance pupil region towards the negative x-axis direction; At least one pupil expansion region, with a pupil expansion diffractive grating, the pupil expansion region being arranged below the turning region and on the path of the grating vector sum of the entrance pupil diffractive grating and the turning diffractive grating; At least one exit pupil region, with an exit pupil diffractive grating, the exit pupil region being arranged on the side of the turning region away from the entrance pupil region and on the path of the grating vector sum of the entrance pupil diffractive grating, the turning diffractive grating and the pupil expansion diffractive grating; The regional diameter of the entrance pupil region is D11; The maximum dimension of the turning region on the x-axis is L21, and the maximum dimension on the y-axis is W21, where the values of L21 and W21 are both 1 to 2 times D11; The minimum dimension of the pupil expansion region on the x-axis is L31a, the maximum dimension is L31b, and the maximum dimension on the y-axis is W31, where L31b > L31a, the value of L31 is 2 to 4 times D11, and the value of W31 is 2 to 6 times D11; The maximum dimension of the exit pupil region on the x-axis is L41, and the maximum dimension on the y-axis is W41, where the value of L41 is 4 to 7 times D11, and the value of W41 is 2 to 5 times D11; The upper edge of the pupil expansion region is parallel to the lower edge of the turning region, with a spacing of th, where th ranges from 0 to 1 mm, and the length of the upper edge of the pupil expansion region is greater than or equal to the length of the lower edge of the turning region; The geometric center of the exit pupil region has a spacing of L in the x-direction and a spacing of W in the y-axis direction from the geometric center of the entrance pupil region, where the value of L is half of the human eye pupil distance, and the value of W is 0.5 to 2 times D11; Light is coupled into the diffractive optical waveguide sheet from the entrance pupil region, the direction of the light is rotated through the turning region, and then is coupled out of the diffractive optical waveguide sheet after passing through the pupil expansion region and the exit pupil region in sequence.

2. The diffractive optical waveguide with a compact grating distribution according to claim 1, characterized in that, The diffractive optical waveguide is a binocular diffractive optical waveguide; The binocular diffractive optical waveguide includes the binocular-shaped diffractive optical waveguide sheet and the entrance pupil region arranged at the middle position of the diffractive optical waveguide sheet, and the binocular diffractive optical waveguide further includes: Two turning regions, the two turning regions being the first turning region and the second turning region symmetrically arranged on both sides of the entrance pupil region, the first turning region being on the +1st order diffractive optical path of the entrance pupil region, and the second turning region being on the -1st order diffractive optical path of the entrance pupil region; Two pupil expansion regions, the two pupil expansion regions being the first pupil expansion region corresponding to the first turning region and the second pupil expansion region corresponding to the second turning region; Two exit pupil regions, the two exit pupil regions being a first exit pupil region corresponding to the first pupil expansion region and a second exit pupil region corresponding to the second pupil expansion region.

3. The diffractive optical waveguide with a compact grating distribution according to claim 1, characterized in that The diffractive optical waveguide is a monocular diffractive optical waveguide; The monocular diffractive optical waveguide includes the monocular diffractive optical waveguide sheet and the entrance pupil region disposed at a side position of the diffractive optical waveguide sheet. The monocular diffractive optical waveguide further includes: A turning region, a turning region on the +1st order diffractive optical path or the -1st order diffractive optical path of the entrance pupil region; A pupil expansion region, located below the turning region; An exit pupil region, located on a side of the turning region away from the entrance pupil region.

4. The diffractive optical waveguide with a compact grating distribution according to claim 1, characterized in that The grating distributions, sizes, and diffractive characteristics of the +1st order diffractive optical path and the -1st order diffractive optical path are mirror symmetric.

5. The diffractive optical waveguide with a compact grating distribution according to claim 1, wherein The value range of D11 is 3 to 7 mm.

6. The diffractive optical waveguide with a compact grating distribution according to claim 1, characterized in that The grating characteristics of the +1st order diffractive optical path and the -1st order diffractive optical path are mirror symmetric; Wherein, on the +1st order diffractive optical path, the entrance pupil diffractive grating has an entrance pupil grating vector, and the angle between the entrance pupil grating vector and the x-axis is a first angle; wherein, the first angle is -30° to 30°, and the period of the entrance pupil diffractive grating is 300 nm to 450 nm; The turning diffractive grating has a turning grating vector, and the angle between the turning grating vector and the x-axis is a second angle; wherein, the second angle is -120° to -150°, and the turning diffractive grating is 200 nm to 400 nm; The pupil expansion diffractive grating has a pupil expansion grating vector, and the angle between the pupil expansion grating vector and the x-axis is a third angle; wherein, the third angle is 30° to 60°, and the period of the pupil expansion diffractive grating is 200 nm to 400 nm; The exit pupil diffractive grating has an exit pupil grating vector, and the angle between the exit pupil grating vector and the x-axis is a fourth angle; wherein, the fourth angle is -150° to -180° and / or 150° to 180°, and the period of the exit pupil diffractive grating is 300 nm to 450 nm.

7. The diffractive optical waveguide with a compact grating distribution according to claim 1, characterized in that, The turning region is selectively provided with an efficiency partition; Both the pupil expansion region and the exit pupil region are provided with efficiency partitions; The efficiency partitions of the pupil expansion region and the efficiency partitions of the exit pupil region are respectively provided with 10 to 15, and the diffractive efficiency gradually increases towards the grating direction.

8. The diffractive optical waveguide with a compact grating distribution according to claim 1, characterized in that, The entrance pupil diffractive grating, the turning diffractive grating, the pupil expansion diffractive grating, and the exit pupil diffractive grating are all symmetric structure gratings or tilted gratings, and the grating forms of the entrance pupil diffractive grating, the turning diffractive grating, the pupil expansion diffractive grating, and the exit pupil diffractive grating are surface relief gratings or volume holographic gratings.

9. The diffractive optical waveguide with a compact grating distribution according to claim 1, characterized in that, The turning region is a reflective surface, and the angle between the normal of the reflective surface and the diffracted light of the entrance pupil region is 30° to 60°.

10. An AR device, characterized in that, Including the diffractive optical waveguide with the compact grating distribution according to any one of claims 1 to 9.

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