CN218675355U - Coupling-in super-structured grating, image combiner and AR optical system - Google Patents
Coupling-in super-structured grating, image combiner and AR optical system Download PDFInfo
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Abstract
The utility model provides a super structure grating, image combiner and AR optical system of coupling, wherein, should couple super structure grating includes: a plurality of coupling grating units which are arranged periodically; the coupling grating unit is configured to output the incident multiple target light beams in corresponding target diffraction orders, and the output angles of the different target light beams are the same; the different kinds of target beams have different wavelengths, and the target diffraction order is the diffraction order of the corresponding target beam regulated and controlled by the coupling-in grating unit. The embodiment of the utility model provides an incoupling super structure grating, image combiner and AR optical system, incoupling super structure grating can be with the target beam of different wavelengths of same angle incoupling, for example with the target beam incoupling of different wavelengths to the optical waveguide in the same angle for the target beam of the multiple wavelength of incoupling can be propagated by unifying, can effectively restrain the rainbow effect.
Description
Technical Field
The utility model relates to a super structure grating technical field particularly, relates to a coupling super structure grating, image combiner and AR optical system.
Background
The diffraction light waveguide can couple light beams into the light waveguide by using the diffraction grating contained in the diffraction light waveguide, so that the diffraction light waveguide has wide application scenes, for example, the diffraction light waveguide can be applied to imaging scenes such as AR (Augmented Reality) glasses and the like; however, when the diffractive light waveguide is used for imaging, the diffraction grating (e.g., the surface relief grating SRG) in the diffractive light waveguide has different diffraction angles for light beams with different wavelengths (e.g., red, green, and blue RGB light beams), and due to the difference in the angles, the angles when the light enters the coupling-out grating are also different after being transmitted by total reflection in the light waveguide, so that the times of total internal reflection of light with different colors in the waveguide are different, and as a result, the proportion of three RGB colors at different positions in the visual field is not uniform, and a rainbow effect is formed.
At present, light of RGB colors is mainly processed by designing a multilayer optical waveguide (for example, three layers of optical waveguides) so as to be able to alleviate the rainbow effect; the structure of the three-layer optical waveguide is schematically shown in fig. 1. However, the multilayer optical waveguide has the defect of large volume, and the weight of the multilayer optical waveguide is large, so that the multilayer optical waveguide is not suitable for scenes needing light and thin optical waveguides, such as AR glasses.
SUMMERY OF THE UTILITY MODEL
To solve the above problem, an embodiment of the present invention provides a coupled-in super grating, an image combiner and an AR optical system.
In a first aspect, an embodiment of the present invention provides a coupled-in super grating, including: a plurality of coupling grating units which are arranged periodically;
the coupling grating unit is configured to output the incident multiple target light beams in corresponding target diffraction orders, and the output angles of the different target light beams are the same; the different kinds of target beams have different wavelengths, and the target diffraction order is the diffraction order of the corresponding target beam regulated and controlled by the coupling-in grating unit.
In one possible implementation, the incoupling grating unit is configured to modulate a plurality of kinds of the target beams incident at the same incident angle;
the different kinds of the target beams correspond to different target diffraction orders.
In one possible implementation, the period length of the incoupling grating unit is such that the wavelength of the target light beam is inversely proportional to the corresponding target diffraction order.
In one possible implementation, the incoupling grating unit is configured to modulate a plurality of kinds of the target beams incident at different incident angles.
In one possible implementation, the target diffraction order comprises a first target diffraction order and a second target diffraction order;
first exit angles corresponding to the first target diffraction orders of different types of target beams are the same, and second exit angles corresponding to the second target diffraction orders of different types of target beams are the same;
the first exit angle and the second exit angle are biased towards different arrangement directions of the incoupling grating units.
In one possible implementation, the incoupling grating unit is configured to modulate a plurality of target beams that are vertically incident.
In one possible implementation, the plurality of target beams includes: red band light beams, green band light beams, and blue band light beams.
In one possible implementation, the incoupling grating unit includes a plurality of incoupling nanostructures arranged in a line along the shape of the incoupling grating unit; at least some of the coupled-in nanostructures differ in shape.
In a second aspect, the present invention provides a coupled-out super grating, including: the light source comprises a plurality of light source units, a plurality of light source units and a plurality of light source units, wherein the light source units are arranged in the light source units;
the coupling-out grating unit is configured to couple out a plurality of kinds of target beams incident at the same incident angle; different kinds of the target beams have different wavelengths;
the multiple target beams are integrally transmitted along the preset direction, and the diffraction efficiency of the coupling-out areas is gradually increased along the preset direction.
In one possible implementation, the diffraction efficiency of the coupling-out region satisfies:
wherein eff (N) represents diffraction efficiency of the nth coupling-out region arranged along the preset direction, and N represents the total number of the coupling-out regions.
In one possible implementation, the outcoupling grating unit includes a plurality of outcoupling nanostructures arranged in a line along the shape of the outcoupling grating unit; at least a portion of the coupling-out nanostructures are different in shape.
In a third aspect, an embodiment of the present invention provides an image combiner, including: a coupling-in element, an optical waveguide and a coupling-out element; the coupling-in element is positioned at the coupling-in end of the optical waveguide, and the coupling-out element is positioned at the coupling-out end of the optical waveguide;
the coupling-in element is the coupling-in super grating as described above, and/or the coupling-out element is the coupling-out super grating as described above;
the optical waveguide comprises an optical waveguide, a plurality of coupling-in grating units and a plurality of coupling-out grating units, wherein the plurality of coupling-in grating units in the coupling-in super grating are arranged along the overall propagation direction of light beams, the plurality of coupling-out grating units in the coupling-out super grating are arranged along the overall propagation direction, and the overall propagation direction is the direction from the coupling-in end to the coupling-out end of the optical waveguide.
In a fourth aspect, an embodiment of the present invention provides an AR optical system, including the image combiner, the image source, and the relay lens group as described above;
the image source is positioned at the light inlet side of the coupling-in element of the image combiner and is configured to input an imaging light beam containing at least three target light beams to the coupling-in element;
the relay lens group is located in the optical path of the image source and the image combiner and is configured to direct the object beam 1:1 projection or magnification projection into the image combiner.
The embodiment of the utility model provides an in the above-mentioned first aspect scheme that provides, including periodic arrangement's a plurality of couple in grating unit, this couple in grating unit carries out corresponding regulation and control to the target beam of different wavelengths, regulates and control the target diffraction order that different target beams correspond to make different target beams incide to couple in grating unit after, can be with the emergence angle outgoing of the same. The incoupling super-structure grating can incouple target beams with different wavelengths at the same angle, for example, the target beams with different wavelengths are incoupled into the optical waveguide at the same angle, so that the incoupled target beams with multiple wavelengths can be uniformly transmitted, and the rainbow effect can be effectively inhibited; moreover, the coupling-in super-structure grating is of a single-layer structure as a whole, does not need to be provided with multiple layers of optical waveguides, is light and thin in structure, and can be applied to scenes with high requirements on volume and weight, such as AR glasses and the like.
In order to make the aforementioned and other objects, features and advantages of the present invention comprehensible, preferred embodiments accompanied with figures are described in detail below.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the description below are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 shows a schematic of the structure of a prior art three-layer optical waveguide;
fig. 2 is a schematic diagram illustrating a top view structure of a coupled-in super grating according to an embodiment of the present invention;
fig. 3 is a schematic diagram illustrating a first side view structure of a coupled-in super grating according to an embodiment of the present invention;
fig. 4 is a schematic diagram illustrating a second side view structure of a coupled-in super grating provided in an embodiment of the present invention;
fig. 5 is a schematic diagram illustrating a third side view structure of a coupled-in super grating provided in an embodiment of the present invention;
fig. 6 is a schematic diagram illustrating a fourth side view structure of a coupled-in super grating according to an embodiment of the present invention;
fig. 7 is a schematic diagram illustrating a fifth side view of a coupled-in super grating according to an embodiment of the present invention;
fig. 8 is a schematic diagram illustrating another top-view structure of a coupled-in super grating provided in an embodiment of the present invention;
fig. 9 is a schematic diagram illustrating a further top view structure of a coupled-in super grating provided in an embodiment of the present invention;
fig. 10 is a schematic diagram illustrating a top view structure of a coupled-out super grating provided by an embodiment of the present invention;
fig. 11 is a schematic diagram illustrating a side view of a coupled-in super grating according to an embodiment of the present invention;
fig. 12 is a schematic diagram illustrating another top-view structure of a coupled-out super grating provided in an embodiment of the present invention;
fig. 13 is a schematic diagram illustrating a side view of an image combiner according to an embodiment of the present invention;
fig. 14 is a schematic structural diagram of AR glasses according to an embodiment of the present invention;
fig. 15 is a schematic structural diagram illustrating an incoupling grating unit according to an embodiment of the present invention;
fig. 16 shows a schematic structural diagram of a outcoupling grating unit provided by the embodiment of the present invention.
Icon:
10-coupling-in grating unit, 101-coupling-in nanostructure, 102-coupling-in super grating substrate, 20-coupling-out region, 21-coupling-out grating unit, 211-coupling-out nanostructure, 212, coupling-out super grating substrate, 1-coupling-in super grating, 2-coupling-out super grating, 3-optical waveguide, 4-image source, and 5-relay lens group.
Detailed Description
In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplification of the description, but do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore, should not be construed as limiting the present invention.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically limited otherwise.
In the present invention, unless otherwise explicitly specified or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly, e.g., as being fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood according to specific situations by those skilled in the art.
The embodiment of the utility model provides a coupling-in super-structure grating, which is a super-structure grating capable of realizing the coupling-in function; referring to fig. 2, the incoupling superstructure grating comprises: a plurality of coupling grating cells 10 are arranged periodically. The incoupling grating unit 10 is configured to emit the incident plural kinds of target light beams at respective target diffraction orders, and the emission angles of the different kinds of target light beams are the same; different kinds of target beams have different wavelengths, and the target diffraction order is the diffraction order of the corresponding target beam modulated and emitted by the coupling-in grating unit 10. For example, after the super-structure grating is designed, only light rays with a specific diffraction order can be emitted, and the diffraction order emitted by the super-structure grating is the target diffraction order.
In the embodiment of the present invention, the coupling-in super-structured grating includes a plurality of grating units, i.e. coupling-in grating units 10; also, a plurality of incoupling grating units 10 are periodically arranged, for example, a plurality of incoupling grating units 10 can be periodically arranged along a predetermined direction. As shown in fig. 2, the stripe-shaped incoupling grating units 10 are arranged along a direction perpendicular to the x-direction, and a plurality of incoupling grating units 10 are periodically arranged along the x-direction. As shown in fig. 2, a plurality of incoupling grating units 10 may be arranged on a substrate 102 coupled into a super-structured grating, and the substrate 102 may serve as a fixed support.
In addition, the incoupling super-structure grating can regulate and control the incident light beams with multiple wavelengths, in this embodiment, the light beams incident to the incoupling super-structure grating are called target light beams, and each target light beam corresponds to one wavelength. Under the effect of coupling grating unit 10, the diffraction effect to every kind of target beam can be regulated and control to the coupling super structure grating for every kind of target beam can be according to the diffraction order outgoing of being coupled grating unit 10 regulation and control outgoing, the embodiment of the utility model provides a be called target diffraction order with this diffraction order. By designing the diffraction effect of the incoupling grating unit 10 on different kinds of target beams, the exit angles of different target beams are the same when each kind of target beam exits according to the corresponding target diffraction order; for example, the target diffraction orders corresponding to different kinds of target beams are different, and the incoupling grating unit 10 can realize that the plurality of kinds of target beams exit at the same exit angle.
For example, the incoupling superstructure grating may be used for imaging, i.e. incident light to the incoupling superstructure grating comprises at least: red band light beams, green band light beams, and blue band light beams. As shown in fig. 3, fig. 3 is shown as L R 、L G 、L B Respectively representing a red waveband light beam, a green waveband light beam and a blue waveband light beam; red, green and blue three wave band light beam L R 、L G 、L B After being diffracted by the incoupling super-structure grating, the light beams can be emitted at the same angle, namely the emission angles of the target light beams of the three wave bands are the same. In order to conveniently show that the incoupling super-structured grating can emit target beams with different wavelengths at the same angle, fig. 3 shows beams with three wave bands of red, green and blue at intervals; those skilled in the art will appreciate that the light beams may be overlapped, and the following fig. 4 to fig. 7 and so on are similar, and will not be described in detail later.
The embodiment of the utility model provides a pair of incoupling super grating, a plurality of incoupling grating units 10 including periodic arrangement, this incoupling grating unit 10 carries out corresponding regulation and control to the target beam of different wavelengths, regulates and control the target diffraction order that different target beams correspond to make different target beams incide to after incoupling grating unit 10, can be with the emergence angle outgoing of the same. The incoupling super-structure grating can incouple target beams with different wavelengths at the same angle, for example, the target beams with different wavelengths are incoupled into the optical waveguide at the same angle, so that the incoupled target beams with multiple wavelengths can be uniformly transmitted, and the rainbow effect can be effectively inhibited; moreover, the coupling-in super-structure grating is of a single-layer structure as a whole, does not need to be provided with multiple layers of optical waveguides, is light and thin in structure, and can be applied to scenes with high requirements on volume and weight, such as AR glasses and the like.
Optionally, due to the circumference of the grating elementsThe phase length can influence the relation between light beam incident angle, emergence angle and the diffraction order, so the embodiment of the utility model provides a through the suitable cycle length of design for this incoupling superstructure grating can regulate and control the light beam of inciding with corresponding incident angle. For example, the general form of a metamorphic grating may be represented as (n) out sinθ out -n inc sinθ inc )/λ i ＝m i /p，λ i The wavelength of the corresponding working wavelength of the super-structured grating, such as the wavelength of the ith target beam; n is inc And n out Refractive indices of the outer and the superstructured gratings, respectively, theta inc And theta out Is the angle of incidence of the light beam incident on the metamaterial grating and the angle of emergence of the light beam coupled into the metamaterial grating, e.g. theta out Representing the exit angle of the light beam coupled into the optical waveguide by the super-structured grating; in general, θ out Larger than the critical angle of total internal reflection, m, of the optical waveguide i Is a diffraction order, e.g., a target diffraction order corresponding to the wavelength of the ith target beam, which is an integer; p is the period length of the grating unit, and the period length p of the incoupling grating unit 10 can be seen in fig. 2.
Wherein the incoupling super-structure grating allows the plurality of target beams to be incident at different incident angles, and the incoupling super-structure grating unit 10 is configured to regulate the plurality of target beams incident at different incident angles. The incident angle of the target beam changes, and the corresponding exit angle of the target beam after the target beam is modulated by the coupled-in super-structured grating also changes, so that the exit angles of different target beams can be conveniently the same by setting the incident angles of the target beams with different wavelengths.
Optionally, at least some of the different target beams correspond to the same target diffraction order; for example, all target beams correspond to the same target diffraction order, e.g., the target diffraction orders of all target beams are +2 diffraction orders. In the embodiment of the present invention, by setting the appropriate period length p, and the incident angles and the exit angles of different target beams, different target beams can exit at the same exit angle; also, at least some (e.g., all) of the different target beams correspond to the same target diffraction order, thereby enabling parameters such as the period length of the incoupling grating cell 10 to be determined simply and quickly.
The incident light incident on the coupled-in super-structure grating comprises a red waveband light beam L R Green band light beam L G And a blue band light beam L B For example, referring to fig. 4, the incoupling super-structure grating 1 is located at the incoupling end of the optical waveguide 3, and is used for incoupling the light beams of three wavelength bands into the optical waveguide 3, so that the light beams of three wavelength bands can propagate along the optical waveguide 3. As shown in fig. 4, the light beams with three wavelength bands enter the incoupling super-structured grating 1 at different incident angles, and under the control of the incoupling super-structured grating 1, the light beams with three wavelength bands all enter at the same exit angle θ out Is coupled into the optical waveguide 3. If the incident angles of the red, green and blue three wave band light beams are respectively theta R 、θ G 、θ B Then, based on the general form of the super-structured grating, the following formula (1) can be obtained:
wherein λ is R 、λ G 、λ B Representing the wavelength of three beams of red, green and blue, respectively, e.g. lambda R ≈720nm，λ G ≈540nm，λ B ≈432nm；m R 、m G 、m B Respectively, the target diffraction orders corresponding to the three target beams of red, green and blue, and p represents the period length of the coupling grating unit 10. Also, the three target diffraction orders may be the same, i.e., m R ＝m G ＝m B (ii) a Based on the above formula (1), there is a corresponding relationship between the incident angle and the period length, and under the condition that the period length p is determined, the incident angles required by the three red, green and blue light beams can be conveniently calculated, so that the three red, green and blue light beams can be incident to the incoupling super-structured grating 1 at the corresponding incident angles, and the incoupling super-structured grating 1 can couple out the light beams at the same angle.
Or, the conventional grating generally mainly uses the same diffraction order (generally +1 or-1 diffraction order), and when light beams with different wavelengths are incident on the conventional diffraction grating at the same angle, the light beams with different wavelengths have different diffraction angles for the diffraction order, that is, different exit angles, thereby causing a rainbow effect; in the embodiment of the present invention, the incoupling grating unit 10 can also realize the emission of multiple target beams at the same emission angle by diffracting the target beams with different wavelengths at different target diffraction orders. Specifically, the incoupling grating unit 10 is configured to modulate a plurality of kinds of target light beams incident at the same incident angle; and, different target beams correspond to different target diffraction orders.
Based on the general form of the diffraction grating, when a plurality of target beams with different wavelengths are incident on the incoupling super-structure grating at the same incident angle, there is a one-to-one correspondence between the wavelengths of the target beams and the target diffraction orders. Specifically, the embodiment of the present invention can make different target light beams exit at the same exit angle under the constraint that the diffraction order is an integer by setting the period length p of a suitable size for the incoupling grating unit 10; at this time, the wavelength of the target beam and the corresponding diffraction order of the target are in an inversely proportional relationship.
The incident light incident on the coupled-in super-structure grating comprises a red waveband light beam L R Green band light beam L G And a blue band light beam L B For example, referring to fig. 5, the incoupling super-structure grating 1 is located at the incoupling end of the optical waveguide 3, and is used for incoupling the light beams of three wavelength bands into the optical waveguide 3, so that the light beams of three wavelength bands can propagate along the optical waveguide 3. As shown in fig. 5, the light beams of the three wave bands are incident to the incoupling super-structured grating 1 at the same incident angle, if the incident angles of the light beams of the three wave bands of red, green and blue are θ respectively R 、θ G 、θ B Then theta R ＝θ G ＝θ B . Under the regulation and control action of the coupling-in super-structured grating 1, the light beams in the three wave bands all have the same emergent angle theta out Is coupled into the optical waveguide 3. Based on the above formula (1), the wavelength of the target beam and the corresponding target diffraction order are in inverse proportional relation, that is, the product of the wavelength of the target beam and the target diffraction order is a fixed value; e.g. by theta inc Indicating incidence ofAngle, i.e. theta R ＝θ G ＝θ B ＝θ inc Then:
(n out sinθ out -n inc sinθ inc )p＝λ i ×m i (2)
wherein λ is i Denotes the wavelength of the i-th target beam, which may be λ, for example R 、λ G 、λ B ；m i Indicating the target diffraction order corresponding to the ith target beam.
Optionally, the incoupling super-structure grating may diffract a target beam in two different diffraction orders, so that the target beam may be diffracted to two different positions, so that the target beam coupled into the incoupling super-structure grating may be received at different positions, for example, the incoupling super-structure grating may enable binocular imaging with a single image source. The embodiment of the utility model provides an in, to arbitrary a target light beam, its target diffraction order includes first target diffraction order and second target diffraction order. First emergence angles corresponding to first target diffraction orders of different kinds of target beams are the same, and second emergence angles corresponding to second target diffraction orders of different kinds of target beams are the same; the first exit angle and the second exit angle are biased toward different arrangement directions of the coupled-in grating units 10.
In the embodiment of the present invention, the incoupling super-structure grating can diffract a part of the target beam according to the first target diffraction order, and the exit angle is the first exit angle; the incoupling super-structured grating may also diffract another part of the target beam according to a second target diffraction order, the exit angle of which is a second exit angle. And the first emergence angles of all the target beams are the same, and the second emergence angles of all the target beams are the same.
The first exit angle and the second exit angle are different, i.e. all target beams can be directed to two different positions in an overlapping manner. The first exit angle and the second exit angle are biased toward different arrangement directions of the incoupling grating units 10. In the embodiment of the present invention, the coupling grating units 10 are arranged periodically, and the arrangement essentially corresponds to two coupling grating unitsThe arrangement direction; accordingly, the incoupling grating unit 10 deflects the target beams toward different arrangement directions, that is, two exit angles (a first exit angle and a second exit angle) of the target beams toward different arrangement directions. For example, as shown in fig. 2 and 6, a plurality of incoupling grating cells 10 are arranged in the x direction (or + x direction), and a plurality of incoupling grating cells 10 are also arranged in the direction opposite to the x direction (or-x direction); accordingly, referring to fig. 6, the incoupling grating unit 10 couples a part of the target beam at a first exit angle θ 1 Emitting at a first emission angle theta 1 Biased to the + x direction; the incoupling grating unit 10 couples another part of the target beam at a second exit angle θ 2 Emitting at a second emission angle theta 2 And the light beams are deflected to the-x direction, so that the target light beams can be respectively transmitted to two sides of the coupling-in super-structured grating, and binocular imaging and the like can be realized under the condition of a single image source.
Alternatively, as shown in fig. 7, the incoupling grating unit 10 is configured to modulate a plurality of target beams that are vertically incident. At this time, for a certain target beam, the diffraction orders of the incoupling grating unit 10 for the target beam are in a positive-negative relationship; for example, the first target diffraction order is + m and the second target diffraction order is-m.
On the basis of any of the above embodiments, referring to fig. 8, the incoupling grating cell 10 includes a plurality of incoupling nanostructures 101 arranged in a line along the shape of the incoupling grating cell 10; and, the shape of at least some of the incoupling nanostructures 101 is different; therein, the incoupling nanostructures 101 in fig. 8 are all represented by circles, and the different shapes of the incoupling nanostructures 101 are not shown.
The coupling-in grating unit 10 has a stripe structure as a whole, the coupling-in grating unit 10 includes a plurality of coupling-in nanostructures 101, and the plurality of coupling-in nanostructures 101 are arranged in a row along the shape of the coupling-in grating unit 10. As shown in fig. 8, the incoupling grating cells 10 are stripe structures along the direction perpendicular to the x-direction, and accordingly, a plurality of incoupling nanostructures 101 are arranged in a row along the direction perpendicular to the x-direction. Alternatively, the incoupling grating cell 10 may comprise only a plurality of incoupling nanostructures 101, i.e. the incoupling grating cell 10 is composed of a plurality of incoupling nanostructures 101, and the plurality of incoupling nanostructures 101 arranged in a row form a strip-shaped structure of the incoupling grating cell 10.
In the embodiment of the present invention, all the incoupling grating units 10 are the same, but in the incoupling grating units 10, at least some of the incoupling nanostructures 101 have different shapes, for example, all the incoupling nanostructures 101 in the incoupling grating units 10 have different shapes. Optionally, the shape of the incoupling nanostructure 101 is a polarization insensitive shape, for example, the incoupling nanostructure 101 has two orthogonal planes of symmetry, and each portion of the incoupling nanostructure 101 divided by the two planes of symmetry is identical; for example, the incoupling nanostructure 101 has an axis of symmetry along which the incoupling nanostructure 101 is rotated by 90 ° and its shape is unchanged. For example, the shape of the incoupling nanostructure 101 includes: at least one of a cylinder, a circular ring column, a square ring column and a cross column.
As shown in fig. 8, the incoupling super grating may include only one row of incoupling grating units 10; alternatively, as shown in fig. 9, the incoupling super grating may also include a plurality of rows of incoupling grating units 10, where the incoupling grating units 10 in each row are arranged along the x-direction.
In order to realize that the incoupling grating unit 10 can emit target light beams with different wavelengths according to a specific diffraction order (i.e. a target diffraction order), only the parameters of the incoupling grating unit 10 (e.g. the period length p of the incoupling grating unit 10) are designed, it is difficult to realize that the light beams with different wavelengths are all emitted according to the corresponding target diffraction order, which easily causes that the incoupling super grating cannot realize the required function; this may result, for example, in a coupling-in super-structured grating having a low diffraction efficiency for a certain wavelength. Optionally, in the embodiment of the present invention, the incoupling grating unit 10 is designed with different shapes of nanostructures (i.e. incoupling nanostructures 101), so that the freedom of designing the shapes of the nanostructures can be introduced, and the incoupling grating unit 10 has more possibilities, so that the incoupling grating unit 10 meeting the required requirements can be designed, that is, the incoupling grating unit 10 can better realize that target beams with different wavelengths exit at the same exit angle.
Alternatively, when designing the incoupling grating unit 10, diffraction efficiency may be targeted, so that the finally obtained incoupling grating unit 10 can emit any one of the target beams with relatively high diffraction efficiency. Specifically, the incoupling nanostructure 101 is a nanostructure determined by maximizing the minimum diffraction efficiency, which is the minimum of the diffraction efficiencies of all target beams.
In the embodiment of the present invention, in the process of designing the incoupling grating unit 10, at least part of the plurality of nanostructures with different shapes may be formed into a candidate grating unit, and the diffraction efficiency of the candidate grating unit for each target beam is determined; for example, the electric field intensity of the target beam passing through the super-structured grating composed of the candidate grating units can be decomposed into plane waves with different fourier orders, and the electric field intensity of the target diffraction order of the target beam can be determined, and the diffraction efficiency of the candidate grating units on the target beam can be expressed by the electric field intensity. The embodiment of the utility model provides a confirm the minimum of diffraction efficiency among all target beams, minimum diffraction efficiency promptly, regard this minimum diffraction efficiency as optimization target to through this minimum diffraction efficiency of maximize, finally can obtain minimum diffraction efficiency still bigger candidate grating unit, this candidate grating unit can regard as required coupling grating unit 10. For example, the incoupling grating unit 10 needs to modulate target beams in three bands of red, green and blue, and the diffraction efficiency of each target beam is: f R 、F G 、F B Then the optimization objective F can be expressed as F = min (F) R ,F G ,F B ) By maximizing the optimization objective F, it is finally possible to design a desired incoupling grating cell 10, which has a high diffraction efficiency.
The above-mentioned embodiments of the present invention provide an incoupling super-structured grating, which can incouple the target beams with multiple wavelengths at the same exit angle, that is, the incoupled target beams with multiple wavelengths can be overlapped; accordingly, embodiments of the present invention also provide an outcoupling super-structure grating, which can outcouple the target beams with multiple wavelengths incident at the same angle, for example, the outcoupling super-structure grating can outcouple the target beams with multiple wavelengths outcoupled by the outcoupling super-structure grating.
Specifically, referring to fig. 10, the outcoupling super grating includes: the outcoupling region 20 includes a plurality of outcoupling gate units 21 arranged in a predetermined direction, and the outcoupling region 20 includes a plurality of outcoupling gate units 21 arranged in the predetermined direction. The coupling-out grating unit 21 is configured to couple out a plurality of kinds of target light beams incident at the same incident angle; different kinds of target beams have different wavelengths; the plurality of target beams are entirely propagated along the predetermined direction, and the diffraction efficiency of the plurality of coupling-out regions 20 arranged in sequence along the predetermined direction is gradually increased. As shown in fig. 10, a plurality of coupled-out grating units 21 may be arranged on a substrate 212 coupled out of the super grating, and the substrate 212 may serve as a fixing support.
As shown in fig. 10, the preset direction is represented by an x direction along which a plurality of coupling-out regions 20 are sequentially arranged; and, for each outcoupling region 20, it includes a plurality of grating units, i.e., outcoupling grating units 21, and the plurality of outcoupling grating units 21 are also arranged along the x-direction. The outcoupling superstructure grating is exemplarily shown in fig. 10 to comprise three outcoupling regions 20, and each outcoupling region 20 comprises three outcoupling grating units 21. It will be understood by those skilled in the art that the outcoupling region 20 is a part of the region divided from the outcoupling super grating, but this does not mean that a plurality of outcoupling regions 20 need to be divided, i.e., the outcoupling super grating is still a unitary structure. For example, as shown in fig. 10, the outcoupling super grating includes 9 outcoupling grating units 21, and the 9 outcoupling grating units 21 may be divided into three parts along the x-direction, each corresponding to one outcoupling region 20.
The coupling-out super-structure grating is used for coupling out target beams with various wavelengths which are propagated along the x direction integrally, and each target beam is incident to the coupling-out super-structure grating at the same incidence angle; wherein the diffraction efficiency of the outcoupling region 20 gradually increases in the x-direction. The target beam as a whole is propagating in the x-direction in fig. 10, i.e. from left to right as a whole; the diffraction efficiency of the coupling-out region 20 gradually increases, that is, the diffraction efficiency of the leftmost coupling-out region 20 is the smallest, the diffraction efficiency of the middle coupling-out region 20 is larger, and the diffraction efficiency of the rightmost coupling-out region 20 is the largest in fig. 10.
In an embodiment of the invention, the outcoupling superstructure grating is used for outcoupling a light beam, which is generally used for outcoupling a light beam propagating along the optical waveguide. As shown in fig. 11, the optical waveguide 3 is disposed along the x direction, and the target beams of a plurality of wavelengths can propagate along the optical waveguide 3 by reflection (e.g., total reflection) of the optical waveguide 3, so that the target beams propagate along the x direction as a whole. The outcoupling super grating 2 is disposed at the outcoupling end of the optical waveguide 3, and the outcoupling grating units 21 in the outcoupling super grating 2 are arranged in the x direction; in fig. 11, the boundary between two adjacent outcoupling regions 20 is shown by a dotted line, and the outcoupling grating cells 21 in different outcoupling regions 20 are shown by different gradations. The light beam a (which includes light beams of multiple wavelengths) propagating along the optical waveguide 3 may be first incident on the leftmost coupling-out region 20 in the coupling-out superstructure grating, and since the diffraction efficiency of the coupling-out region 20 is the smallest, a small part of the light beam a can be coupled out, i.e., the light beam A1 is coupled out, and the rest can continue to propagate along the optical waveguide 3, i.e., the light beam B continues to propagate along the optical waveguide 3. The light beam B can be incident on the middle coupling-out region 20 of the coupling-out super-structured grating, although the light intensity of the light beam B is lower than that of the light beam a (because a part of the light beam A1 in the light beam a is coupled out), the middle coupling-out region 20 has higher diffraction efficiency, so that the coupling-out region can still couple out a proper amount of the light beam B1, the rest of the light beam C (i.e. the rest of the light beam B) can still continue to propagate along the optical waveguide 3 and is incident on the rightmost coupling-out region 20, and the rightmost coupling-out region 20 has the highest diffraction efficiency, so that the right-most coupling-out region can still couple out a proper amount of the light beam C1; for example, the rightmost outcoupling region 20 has a diffraction efficiency of 1, which can outcouple all light beams. The embodiment of the utility model provides an utilize a plurality of coupling-out regions 20 of diffraction efficiency crescent, can couple out the target beam of multiple wavelength uniformly, the light intensity distribution of the light-emitting side of this coupling-out super structure grating is more even.
Optionally, the diffraction efficiency of the coupling-out region 20 satisfies:
where eff (N) denotes a diffraction efficiency of the nth outcoupling region 20 arranged in the predetermined direction, and N denotes the total number of the outcoupling regions 20.
In the embodiment of the present invention, n represents the serial number of the coupling-out area 20 arranged along the preset direction, and the diffraction efficiency of each coupling-out area 20 can be determined based on the above formula (3). For example, as shown in fig. 11, the outcoupling super grating includes three outcoupling regions 20, i.e., N =3; accordingly, the three coupling-out regions 20 from left to right in fig. 11 are numbered 1, 2, and 3 in sequence, and the diffraction efficiency thereof may be 1/3, 1/2, and 1 in sequence. In this case, the light intensity of the light beam coupled out by each coupling-out region 20 is substantially the same, i.e., the light intensity of the light beam A1, the light beam B1, the light beam C1 is substantially the same; the light intensity of the light beam A1, the light beam B1, and the light beam C1 is one third of the light intensity of the incident light beam a, regardless of the loss.
It should be noted that the diffraction efficiency eff (n) refers to the actual diffraction efficiency of the nth outcoupling region 20, and the actual diffraction efficiency eff (n) of the nth outcoupling region 20 is difficult to satisfy the above formula (3) completely due to the process and difficulty in determining the coupling-out grating unit 21 that completely meets the requirement; in the embodiment of the present invention, within the tolerance range, as long as the nth coupling-out region 20 has the diffraction efficiency eff (n) and
the difference is not so great that, for example,
in this case, the diffraction efficiency of the nth outcoupling region 20 can be considered to satisfy the above expression (3).
On the basis of any of the above embodiments, referring to fig. 12, the outcoupling grating unit 21 includes a plurality of outcoupling nanostructures 211 arranged in line along the shape of the outcoupling grating unit 21; also, at least part of the coupling nano-structures 211 are different in shape; wherein fig. 12 does not show the different shape of the coupling-out nanostructure 211.
Similar to the incoupling grating unit 10, the outcoupling grating unit 21 has a stripe structure as a whole, the outcoupling grating unit 21 includes a plurality of outcoupling nanostructures 211, and the outcoupling nanostructures 211 are arranged in a line along the shape of the outcoupling grating unit 21. As shown in fig. 12, the coupling-out grating unit 21 is a stripe structure along the direction perpendicular to the x-direction, and accordingly, the coupling-out nanostructures 211 are arranged in a line along the direction perpendicular to the x-direction. Alternatively, the outcoupling gate unit 21 may only include a plurality of outcoupling nanostructures 211, that is, the outcoupling gate unit 21 is composed of a plurality of outcoupling nanostructures 211, and the plurality of outcoupling nanostructures 211 arranged in a line form the outcoupling gate unit 21 in a stripe structure.
In the embodiment of the present invention, all the outcoupling grating units 21 in one outcoupling region 20 are the same, but in the outcoupling grating units 21, at least some of the outcoupling nanostructures 211 have different shapes, for example, all the outcoupling nanostructures 211 in the outcoupling grating units 21 have different shapes. Alternatively, the shape of the coupling-out nanostructure 211 is a polarization insensitive shape, for example, the coupling-out nanostructure 211 has two orthogonal symmetry planes, and each portion of the coupling-out nanostructure 211 divided by the two symmetry planes is identical; for example, the coupling-out nanostructure 211 has an axis of symmetry, along which the coupling-out nanostructure 211 is rotated by 90 ° and its shape is unchanged. For example, the shape of the coupling-out nanostructure 211 includes: at least one of a cylinder, a circular ring column, a square ring column and a cross column.
Alternatively, as described above, the diffraction efficiencies of the outcoupling grating elements 21 in different outcoupling regions 20 for the target light beams are different, but the diffraction efficiencies of one outcoupling region 20 for target light beams of different wavelengths should be the same; further, the outcoupling grating unit 21 may also be configured to emit a plurality of kinds of target light beams incident at the same incident angle at the same exit angle; that is, the outcoupling grating unit 21 also controls the diffraction orders for target beams of different wavelengths. In order to realize that the outcoupling grating unit 21 can emit target light beams with different wavelengths according to a specific diffraction efficiency, only parameters of the outcoupling grating unit 21 (for example, a period length of the outcoupling grating unit 21) are designed, which easily causes the outcoupling super grating not to realize a desired function; this may result, for example, in a partial outcoupling region 20 with an unsatisfactory diffraction efficiency for a certain wavelength. Optionally, in the embodiment of the present invention, the outcoupling grating unit 21 is designed with the nanostructures (i.e. the outcoupling nanostructures 211) of different shapes, and this design freedom of the nanostructure shape can be introduced, so that the outcoupling grating unit 21 has more possibilities, and thus the outcoupling grating unit 21 meeting the required requirements can be designed, i.e. the outcoupling grating unit 21 can diffract the target light beams of multiple wavelengths according to the required diffraction efficiency.
Optionally, in order to ensure that the diffraction efficiency of each coupling-out area 20 meets the required requirements, for example, the above formula (3) is met, embodiments of the present invention set an objective function, which is maximized to achieve optimization of the coupling-out nanostructure 211, thereby determining the coupling-out nanostructure 211 that enables the diffraction efficiency of the corresponding coupling-out area 20 to meet the required requirements. Wherein the objective function satisfies:
wherein, F i (n) represents the diffraction efficiency of the ith target beam by the nth outcoupling region 20 arranged in the preset direction,
indicating the diffracted intensity of the ith target beam by the nth outcoupling region 20,
indicating the reflected light intensity of the nth outcoupling region 20 for the ith target beam, eff (N) indicating the theoretical diffraction efficiency corresponding to the nth outcoupling region 20, i.e. the diffraction efficiency that the nth outcoupling region 20 should have, and N indicating the total number of outcoupling regions 20.
In the embodiment of the present invention, for the nth coupling-out area 20, the higher its theoretical diffraction efficiency Eff (n) is, the corresponding diffraction light intensity
The larger. For the last coupling-out area 20, i.e. n =N, directly diffracting the light intensity
As an optimization objective to enable the real diffraction efficiency eff (n) of the last outcoupling region 20 to approach 1. For the other outcoupling region 20, as shown in the above equation (4), the difference between the theoretical diffraction efficiency Eff (n) and the current true diffraction efficiency Eff (n) is determined based on the theoretical diffraction efficiency Eff (n) in its ideal case, and the present embodiment uses
And
the smaller value of (F) represents the difference between the two, the larger the smaller value is, the closer the current real diffraction efficiency Eff (n) is to the theoretical diffraction efficiency Eff (n) that should be had, by maximizing the minimum value (i.e., maximizing F) i (n)) the actual diffraction efficiency Eff (n) of the finally determined nth outcoupling region 20 can be brought into agreement with the theoretical diffraction efficiency Eff (n) which it should have.
Wherein the theoretical diffraction efficiency Eff (n) can be predetermined; for example, the outcoupling superstructure grating comprises three outcoupling regions 20, i.e. N =3, the theoretical diffraction efficiencies Eff (N) that the three outcoupling regions 20 should have in turn are: 1/3, 1/2 and 1. As will be understood by those skilled in the art, eff (n) represents the diffraction efficiency of the nth outcoupling region 20 in an ideal case, which may slightly deviate from the true diffraction efficiency Eff (n) of the nth outcoupling region 20. In an ideal case, eff (n) = Eff (n).
The embodiment of the utility model provides a couple-out super-structure grating, it includes a plurality of couple-out areas 20 arranged along the preset direction, and the diffraction efficiency of couple-out area 20 increases in proper order; when the object beam propagating in the predetermined direction as a whole is incident on the outcoupling super grating, it can be uniformly outcoupled by the plurality of outcoupling regions 20, pupil replication is achieved, and the eye movement (eyebox) range can be increased. Also, by optimizing the nanostructure with the above optimization objective, the coupling-out nanostructure 211 required for each coupling-out region 20 can be determined so that the diffraction efficiency of each coupling-out region 20 can satisfy the required requirements.
Optionally, the embodiment of the present invention further provides an image combiner, as shown in fig. 13, the image combiner includes: a coupling-in element, an optical waveguide 3 and a coupling-out element; the coupling-in element is located at the coupling-in end of the optical waveguide, and the coupling-out element is located at the coupling-out end of the optical waveguide. Wherein the coupling-in element is the coupling-in super grating 1 provided in any of the above embodiments, and/or the coupling-out element is the coupling-out super grating 2 provided in any of the above embodiments. As shown in fig. 13, the incoupling super-structured grating 1 is located at the incoupling end of the optical waveguide, and the outcoupling super-structured grating 2 is located at the outcoupling end of the optical waveguide. Wherein the plurality of incoupling grating units 10 in the incoupling superstructure grating 1 are arranged along the overall propagation direction of the light beam, and the plurality of outcoupling grating units 21 in the outcoupling superstructure grating 2 are also arranged along the overall propagation direction, which is the direction from the incoupling end to the outcoupling end of the optical waveguide 3.
In the embodiment of the present invention, a plurality of coupling-in grating units 10 in the coupling-in super-structure grating 1 and a plurality of coupling-out grating units 21 in the coupling-out super-structure grating 2 are all arranged along the whole propagation direction of the light beam in the optical waveguide 3, i.e. arranged along the setting direction of the optical waveguide 3. As shown in fig. 13, the coupling-in end of the optical waveguide 3 is located at the lower surface of the left end thereof, and the coupling-out end of the optical waveguide 3 is located at the lower surface of the right end thereof, so that the light beam can propagate entirely within the optical waveguide 3 from left to right, i.e., along the x direction in fig. 13; accordingly, the incoupling grating cells 10 and the outcoupling grating cells 21 are arranged in the x direction. Under the action of the coupled-in super-structure grating 1, target beams with various wavelengths can be transmitted in the optical waveguide 3 at the same angle, so that the rainbow effect can be effectively inhibited; and at the coupling-out end, target light beams with various wavelengths can be uniformly coupled out by the coupling-out super-structure grating 2, pupil replication can be realized, the eye movement range is enlarged, and the visual comfort of human eyes can be improved.
Optionally, embodiments of the present invention further provide an AR optical system, which includes the image combiner and the image source 4 as described above, such as the image source 4 shown in fig. 13; the image source 4 is located at the light entrance side of the incoupling element and is configured to enter an imaging beam comprising at least three target beams into the incoupling element. For example, the image source 4 may emit an imaging beam including three wavelengths of red, green, and blue, and direct the imaging beam toward the incoupling super-structured grating 1; the incoupling superstructure grating 1 couples the imaging beam into the optical waveguide 3 and propagates along the optical waveguide 3, and finally the imaging beam is coupled out by the outcoupling superstructure grating 2. An observer situated at the coupled-out super grating 2 can view the image formed by the image source 4.
And, the AR optical system further comprises a relay lens group 5, the relay lens group 5 being located in the optical path of the image source 4 and the image combiner, configured to direct the object beam 1:1 projection or magnification projection into an image combiner. As shown in fig. 14, the image source 4 is disposed at the temple of the AR glasses, and the imaging light emitted from the image source 4 is incident on the incoupling element through the relay lens group 5, which is not shown in fig. 14. Also, the lens (or a part of the lens) of the AR glasses may serve as the optical waveguide 3 and propagate the imaging light; finally, the imaging light is coupled out by the coupling-out element and emitted to the human eye.
The structure and function of the image combiner will be described in detail below by way of an embodiment.
In the embodiment of the present invention, the schematic structural diagram of the image combiner can be seen in fig. 13. The light emitted by the image source 4 is RGB three-color light, i.e. light beams containing three wavelengths of red, green and blue. The RGB light beams are modulated by the incoupling superstructure grating 1, enter the light guide 3 at a total reflection angle, and are totally reflected in the light guide 3, and finally are coupled out by the outcoupling superstructure grating 2 to the human eye. The basic structure of the coupling-in super-structure grating 1 can be seen in fig. 8 or fig. 9, and the basic structure of the coupling-out super-structure grating 2 can be seen in fig. 12.
In the embodiment of the present invention, the size of the coupling-in super-structured grating 1 is 10mm × 10mm, the thickness of the optical waveguide 3 is 4mm, the width is 10mm, the length can be determined according to the actual situation, for example, according to the size of the glasses, and the length is usually about 20 mm. The incoupling superstructure grating 1 comprises tens of millions of incoupling nanostructures 101, wherein each 8 incoupling nanostructures 101 form an incoupling grating unit 10, that is, each incoupling grating unit 10 corresponds to 8 incoupling nanostructures 101. Wherein the shapes of the 8 incoupling nanostructures 101 are different from each other, fig. 15 shows a top view of an incoupling grating unit 10, and the shapes of the 8 incoupling nanostructures 101 can be specifically seen in fig. 15. As shown in fig. 15, each of the incoupling nanostructures 101 is insensitive to polarization; the dimensions of the 8 coupled-in nanostructures 101 are shown in table 1 below.
TABLE 1
Wherein dimension 1 in table 1 represents an outer dimension of the incoupling nanostructure 101, such as half the outer radius or outer length of the incoupling nanostructure 101; dimension 2 represents the inner dimension of the incoupling nanostructure 101, e.g. half the inner radius or inner length of the incoupling nanostructure 101. Where dimension 1 and dimension 2 are both in nm, for a cross-shaped columnar coupled-in nanostructure 101 (e.g., the 7 th nanostructure in fig. 15), dimension 1 represents half the length of the cross, dimension 2 represents half the width of each protruding portion of the cross, and dimension 2 is also half the side length of the square at the center of the cross.
The dimensions of the outcoupling super grating 2 are 10mm × 10mm. Each outcoupling grating unit 21 in the outcoupling superstructure grating 2 comprises 5 outcoupling nanostructures 211; wherein the shapes of the 5 outcoupling nanostructures 211 are different from each other, fig. 16 shows a top view of one outcoupling grating unit 21, and the shapes of the 5 outcoupling nanostructures 211 can be specifically seen in fig. 16; furthermore, the dimensions of the 5 outcoupling nanostructures 211 comprised by the outcoupling grating units 21 are shown in table 2 below.
TABLE 2
Wherein dimension 1 in table 2 represents an outer dimension of the coupling-out nanostructure 211, e.g., half the outer radius or outer length of the coupling-out nanostructure 211; the dimension 2 represents an inner dimension of the coupling-out nanostructure 211, for example half of the inner radius or the inner edge length of the coupling-out nanostructure 211. Dimension 1 and dimension 2 are in nm. The outcoupling super-structured grating 2 can vertically emit visible light both at normal incidence and at 25 °, for example, it can vertically emit ambient light at normal incidence and a target light beam at 25 ° incident propagated by the optical waveguide 3, so that a function of mixing a virtual image and a real image can be realized.
The above description is only for the specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto, and any person skilled in the art can easily think of the technical solutions of the changes or replacements within the technical scope of the present invention, and all should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (13)
1. An incoupled metamaterial grating, comprising: a plurality of coupling-in grating units (10) arranged periodically;
the incoupling grating unit (10) is configured to emit the incident multiple target light beams in corresponding target diffraction orders, and the emission angles of the different target light beams are the same; the different target light beams have different wavelengths, and the target diffraction orders are diffraction orders of the corresponding target light beams which are regulated and controlled by the coupling grating unit (10).
2. An incoupling superstructure grating according to claim 1, characterized in that said incoupling grating unit (10) is configured to condition a plurality of said target beams incident at the same angle of incidence;
the different kinds of the target beams correspond to different target diffraction orders.
3. A incoupling superstructure grating according to claim 2, characterized in that the period length of the incoupling grating cells (10) is such that the wavelength of the target light beam is inversely proportional to the respective target diffraction order.
4. An incoupling superstructure grating according to claim 1, characterized in that said incoupling grating unit (10) is configured to condition a plurality of said target beams incident at different angles of incidence.
5. The coupled-in metamaterial grating of claim 1, wherein the target diffraction orders include a first target diffraction order and a second target diffraction order;
first exit angles corresponding to the first target diffraction orders of different types of target beams are the same, and second exit angles corresponding to the second target diffraction orders of different types of target beams are the same;
the first exit angle and the second exit angle are biased towards different arrangement directions of the incoupling grating units (10).
6. An incoupling superstructure grating according to claim 5, characterized in that said incoupling grating unit (10) is configured to manipulate said plurality of target beams at normal incidence.
7. The incoupling superstructure grating of claim 1, characterized in that said plurality of object beams comprises: red band light beams, green band light beams, and blue band light beams.
8. An incoupling superstructure grating according to claim 1, characterized in that said incoupling grating cells (10) comprise a plurality of incoupling nanostructures (101) arranged in-line along the shape of said incoupling grating cells (10); at least some of the coupled-in nanostructures (101) differ in shape.
9. An image combiner, comprising: a coupling-in element, an optical waveguide (3) and a coupling-out element; the coupling-in element is located at a coupling-in end of the optical waveguide (3) and the coupling-out element is located at a coupling-out end of the optical waveguide (3);
the incoupling element is an incoupling superstructure grating (1) as claimed in any of claims 1-8, wherein a plurality of incoupling grating cells (10) in the incoupling superstructure grating (1) are arranged along the overall propagation direction of the light beam, said overall propagation direction being the direction from the incoupling end to the outcoupling end of the optical waveguide (3).
10. An image combiner as claimed in claim 9, characterized in that the outcoupling elements are outcoupling metamaterials (2);
the outcoupling superstructure grating (2) comprising: the light source comprises a plurality of coupling-out regions (20) which are sequentially arranged along a preset direction, wherein each coupling-out region (20) comprises a plurality of coupling-out grating units (21) which are arranged along the preset direction; a plurality of coupling-out grating units (21) in the coupling-out super grating (2) are arranged along the overall propagation direction;
the coupling-out grating unit (21) is configured to couple out a plurality of kinds of target light beams incident at the same incident angle; different kinds of the target beams have different wavelengths;
the multiple target beams are integrally transmitted along the preset direction, and the diffraction efficiency of the multiple coupling-out areas (20) sequentially arranged along the preset direction is gradually increased.
11. An image combiner as claimed in claim 10, characterized in that the diffraction efficiency of the coupling-out region (20) is such that:
wherein eff (N) represents the diffraction efficiency of the nth coupling-out area (20) arranged along the preset direction, and N represents the total number of the coupling-out areas (20).
12. An image combiner as claimed in claim 11, characterized in that the outcoupling grating elements (21) comprise a plurality of outcoupling nanostructures (211) arranged in line along the shape of the outcoupling grating elements (21); at least part of the coupling-out nanostructures (211) differ in shape.
13. An AR optical system comprising an image combiner according to any of claims 9-12, an image source (4) and a relay lens group (5);
the image source (4) is positioned at the light-in side of the coupling-in element of the image combiner and is configured to input an imaging light beam containing at least three target light beams to the coupling-in element;
the relay lens group (5) is located in the optical path of the image source (4) and the image combiner, and is configured to direct the object beam 1:1 projection or magnification projection into the image combiner.
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| PCT/CN2023/123692 WO2024088055A1 (en) | 2022-10-28 | 2023-10-10 | In-coupling meta-grating, out-coupling meta-grating, image combiner, and ar optical system |
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