CN115903122B - Grating waveguide device and waveguide system for augmented reality display - Google Patents
Grating waveguide device and waveguide system for augmented reality display Download PDFInfo
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- CN115903122B CN115903122B CN202310018538.4A CN202310018538A CN115903122B CN 115903122 B CN115903122 B CN 115903122B CN 202310018538 A CN202310018538 A CN 202310018538A CN 115903122 B CN115903122 B CN 115903122B
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Abstract
The invention provides a grating waveguide device and a waveguide system for augmented reality display, wherein the grating waveguide device comprises a substrate and at least one grating region; the grating area is arranged on the substrate; the grating vector of each grating region is expressed as a superposition of integer multiples of n grating vectors of the same virtual two-dimensional grating, where n is an integer not less than 2. The grating waveguide device adopts the design, so that the display image of the grating waveguide scheme can keep higher definition.
Description
Technical Field
The invention belongs to the technical field of augmented reality display, and particularly relates to a grating waveguide device and a waveguide system for augmented reality display.
Background
Augmented Reality (AR) technology refers to providing a user with additional information (so-called "augmentation") in the real world by some technical means, such as intelligently displaying each part (fig. 1) while a worker is operating a machine, and indicating a left turn or straight directional arrow on a real road while a driver is driving. The technology organically integrates the image of the virtual world and the scene of the real world, and the calculated information is deeply integrated with the real world, so that richer information and immersive experience are provided for a user. In the information age, augmented reality has very wide application scenarios, such as military training, medical assistance, educational learning, game industry, entertainment arts, etc., as one of the most direct information acquisition approaches, and is widely regarded as the next generation computing platform following a computer.
The augmented reality technology can be implemented by a number of hardware platforms, with grating waveguides having become one of the most popular technological routes in the industry. The basic principle of the grating waveguide scheme is shown in fig. 2, where at least one grating area (shown schematically as coupling-in grating 1 and coupling-out grating 2) is provided on the surface or inside of the optical substrate 3, the incident light beam 5 of the projection mechanism 4 is coupled into the optical substrate 3 by the coupling-in grating 1, total reflection occurs in the optical substrate 3, and a part of the diffracted light beam 6 is coupled out whenever encountering another coupling-out grating 2, so that the human eye 7 can see the same image as the output of the projection mechanism 4 behind the coupling-out grating 2, at the same time, the human eye 7 can see the image of the real world through the optical substrate 3, and the two images overlap to realize the function of augmented reality.
But there may be a problem of poor display image definition for the existing complex grating waveguide having a plurality of grating regions.
Disclosure of Invention
In order to overcome the defects in the prior art, the main object of the invention is to provide a grating waveguide device and a waveguide system for augmented reality display.
The invention is realized by the following technical scheme:
the invention provides a grating waveguide device for augmented reality display, which comprises a substrate and at least one grating region;
the grating area is arranged on the substrate;
the grating vector of each grating region is expressed as a superposition of integer multiples of n grating vectors of the same virtual two-dimensional grating.
Further, the grating region is a plurality of grating regions.
Further, the grating vectors of the different grating regions are expressed as a superposition of integer multiples of n grating vectors of the same virtual two-dimensional grating, including:
and expressing the grating vectors of the different grating areas as the superposition of integer multiples of two grating vectors of the same virtual two-dimensional grating.
Further, the included angle between two grating vectors of the virtual two-dimensional grating is between 0 and 180 degrees or between-180 and 0 degrees.
Further, the grating vector of the grating region is expressed as the superposition of integer multiples of n grating vectors of the same virtual two-dimensional grating by adjusting the periodicity of the grating region;
wherein the periodicity of the grating region includes the pitch and direction of the grating.
Further, for an incident light beam of a specific wavelength, the magnitude of the K-vector waveguide in-plane component of any non- (0, 0) order diffracted light beam formed by the grating waveguide device is larger than the wavenumber of the incident light beam of the specific wavelength in the substrate exterior material, and the magnitude of the K-vector waveguide in-plane component of at least one non- (0, 0) order diffracted light beam is smaller than the wavenumber of the incident light beam of the specific wavelength in the substrate interior material.
Furthermore, on the basis of the virtual two-dimensional grating, the refractive index of the material inside the substrate and the refractive index of the material outside the substrate can be adjusted.
Further, for a light beam of a specific wavelength, at least one of the grating regions has a magnitude of a waveguide in-plane component of a K vector of the diffracted light beam of more than one non-coupling order that is greater than a wavenumber of the light beam of the specific wavelength in the substrate exterior material and less than a wavenumber of the light beam of the specific wavelength in the substrate interior material.
Further, the grating region has one or more of coupling in, pupil expanding and coupling out functions for the light beam.
Further, the integral grating layout formed by the plurality of grating regions satisfies the functions of coupling in, expanding pupil and coupling out light beams.
Further, at least one of the plurality of grating regions diffracts the light beam reaching that region to propagate in the opposite direction.
Further, the substrate adopts a light-transmitting substrate;
the substrate has a first surface and a second surface;
the first surface and the second surface are oppositely arranged;
the grating region is located on the first surface, the second surface or inside the substrate.
Further, the grating region comprises a one-dimensional grating region, a first two-dimensional grating region and a second two-dimensional grating region;
the one-dimensional grating area is used as a coupling-in grating area and is arranged on the first surface and/or the second surface of the substrate;
the first two-dimensional grating area is used as a pupil expansion-coupling-out grating area and is arranged on the first surface of the substrate;
the second two-dimensional grating region is arranged on the second surface of the substrate as a pupil-expanding-coupling-out grating region.
Further, the second two-dimensional grating region diffracts the light beam reaching the region to propagate in the opposite direction.
The invention also provides a waveguide system for augmented reality display, comprising a grating waveguide;
wherein at least one of the grating waveguides adopts the grating waveguide device for augmented reality display.
Compared with the prior art, the technical scheme of the invention has the following beneficial effects:
the invention provides a grating waveguide device for augmented reality display, which comprises a substrate and at least one grating area arranged on the substrate, wherein the grating vector of each grating area is expressed as the superposition of integer multiples of two grating vectors of the same virtual two-dimensional grating, so that the light beam propagation of different grating areas always keeps higher image definition, the definition of the coupled human eye diffraction light beam is further ensured, and the higher definition of the grating waveguide scheme display image is realized. The grating waveguide system also has the advantages of smaller size, higher optical efficiency, larger pupil expansion range, better pupil expansion uniformity, larger field angle, better imaging uniformity, no ghost image and the like.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions of the prior art, the drawings which are used in the description of the embodiments or the prior art will be briefly described, it being obvious that the drawings in the description below are only some embodiments of the invention, and that other drawings can be obtained according to these drawings without inventive faculty for a person skilled in the art.
FIG. 1 is a schematic illustration of a scenario in which augmented reality technology is used during operation of a machine by a user;
FIG. 2 is a schematic diagram of the basic principle of a grating waveguide solution;
FIG. 3 is a schematic diagram of a grating vector of a one-dimensional grating;
FIG. 4 is a schematic diagram of a grating vector of a two-dimensional grating;
FIG. 5 is a first exemplary schematic diagram of a grating waveguide apparatus for augmented reality display of the present invention;
FIG. 6 is a schematic diagram of a grating vector of the grating region shown in FIG. 5;
FIG. 7 is a second exemplary schematic diagram of a grating waveguide apparatus for augmented reality display of the present invention;
FIG. 8 is a schematic view of a grating vector of the grating region shown in FIG. 7;
FIG. 9 is a schematic diagram of a diffraction beam K vector formed by coupling an incident beam of a particular wavelength into the grating waveguide device of FIG. 5;
FIG. 10 is a schematic diagram of a diffraction beam K vector formed by coupling an incident beam of a particular wavelength into the grating waveguide device of FIG. 7;
FIG. 11 is a schematic diagram of a grating design in a prior art grating waveguide solution;
fig. 12 is another schematic diagram of a grating design in a prior art grating waveguide scheme.
Description of the reference numerals
1-in grating, 2-out grating, 3-optical substrate, 4-projection mechanism, 5-incident beam, 6-diffracted beam, 7-human eye, 8-turn grating.
Detailed Description
The technical solutions of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Meaning description:
1. grating vector
The grating has a grating vector, for example, for a one-dimensional grating, as shown in fig. 3, the magnitude of the grating vector is k=2pi/d, the direction of the grating vector is the same as the periodic direction of the grating structure, where d is the period of the one-dimensional grating.
For a two-dimensional grating, as shown in FIG. 4, two grating vectors are illustrated, the first grating vector having a size K 1 =2pi/d 1/sin (a), the second raster vector has a size of K 2 =2pi/d 2/sin (a), the direction of the first grating vector being perpendicular to the second periodic direction of the grating structure, the direction of the second grating vector being perpendicular to the first periodic direction of the grating structure, wherein d 1 D is the period of the first grating 2 And a is an included angle between the period direction of the first grating and the period direction of the second grating.
2. K-space representation of grating waveguide
The various light beams entering, propagating within, and exiting the grating waveguide may all be described using one or more K vectors that describe the direction of propagation of the light beams. K-space is an analysis framework that relates K-vectors to geometric points. In K-space, each point in space corresponds to a unique K-vector, which in turn may represent a beam or ray of light having a particular direction of propagation.
This allows the input and output beams with corresponding propagation angles to be understood as a set of points (e.g. rectangles) in K-space. The diffraction feature of changing the direction of propagation of a light beam while it propagates through a grating waveguide can be understood as simply translating the position of a set of K-space points that make up an image in K-space. The new translational K-space position corresponds to a new set of K-vectors, which in turn represent the new propagation angle of the beam or ray after interaction with the grating diffraction signature.
In the K-space of the grating waveguide, a specific K-vector is determined by the K-vector component of the beam in the grating plane plus the vector of the grating vector.
3. Diffraction orders
The diffraction orders of a two-dimensional grating are typically expressed in terms of coordinates (x, y), where x, y represent the diffraction orders of two dimensions of the two-dimensional grating, respectively. Such as (1, 0) diffraction orders, (1, 1) diffraction orders, etc.
It should be noted that, although the diffraction orders of the two-dimensional grating are expressed in terms of coordinates (x, y), they do not represent that the same diffraction orders have the same diffraction direction under the definition of the dimensions of different two-dimensional gratings. The diffraction direction corresponding to the diffraction order is defined by the dimensions of the two-dimensional grating, for example, the (1, 0) diffraction order may correspond to the 1 o 'clock direction of the timepiece under one definition of the dimensions, or may correspond to the 3 o' clock direction of the timepiece under another definition of the dimensions.
4. Virtual two-dimensional grating
Reference herein to a "virtual two-dimensional grating" refers to a theoretically designed grating period size and direction and does not necessarily exist on a physically fabricated grating waveguide.
The invention provides a grating waveguide device for augmented reality display, which comprises a substrate and at least one grating region.
The substrate may be a substrate made of a light-transmitting material.
The substrate is provided with a first surface and a second surface, and the first surface and the second surface are oppositely arranged.
The grating region is disposed on the substrate, and in particular, the grating region may be disposed on the first surface, the second surface, or the inside of the substrate.
The grating vector of each grating region is expressed as a superposition of integer multiples of n grating vectors of the same virtual two-dimensional grating. That is, whether the grating region is a single one-dimensional grating, a single two-dimensional grating, a one-dimensional grating combination, a two-dimensional grating combination, or a combination of a one-dimensional grating and a two-dimensional grating, the grating vectors of all the grating regions disposed on the grating waveguide are expressed as an integer multiple superposition of n grating vectors of the same virtual two-dimensional grating. Wherein n is an integer of not less than 2.
Illustratively, as shown in fig. 5, one scenario is where multiple grating regions are employed for a grating waveguide. The grating vectors of the different grating regions in fig. 5 can be expressed as a superposition of integer multiples of n grating vectors of the same virtual two-dimensional grating.
Illustratively, as shown in FIG. 6, the different grating regions in FIG. 5 are expressed as a superposition of integer multiples of two grating vectors of the same virtual two-dimensional grating:
the two grating vectors of the virtual two-dimensional grating are K 1 ，K 2 . The grating vectors of the grating regions shown in FIG. 5 are respectively K 1 、K 2 Is an integer multiple of the superposition of:
grating vector K of one-dimensional grating w1 =K 1 +K 2 ；
Two grating vectors K of two-dimensional grating A WA_1 =K 1 ，K WA_2 =K 2 ；
Two grating vectors K of two-dimensional grating B WB_1 =-K 1 -2K 2 ，K WB_2 =-2K 1 -K 2 。
Illustratively, as shown in FIG. 7, another scenario is that a grating waveguide employs multiple grating regions. The grating vectors of the different grating regions in fig. 7 can be expressed as a superposition of integer multiples of n grating vectors of the same virtual two-dimensional grating.
Illustratively, as shown in FIG. 8, the different grating regions in FIG. 7 are expressed as a superposition of integer multiples of two grating vectors of the same virtual two-dimensional grating:
the two grating vectors of the virtual two-dimensional grating are K 1 ，K 2 . The grating vectors of the grating regions shown in FIG. 7 are respectively K 1 、K 2 Is an integer multiple of the superposition of:
one-dimensional grating A, its grating vector K WA =K 1 ；
One-dimensional grating C, its grating vector K WC =K 1 -K 2 ；
One-dimensional grating D, its grating vector K WD =K 1 +K 2 ；
Two-dimensional grating E, two grating vectors K thereof WE_1 =-K 1 -K 2 、K WE_2 =-K 1 +K 2 ；
One-dimensional grating B, its grating vector K WB =K 2 ；
Two-dimensional grating F, two grating vectors K WF_1 =K 1 、K WF_2 =K 2 。
Based on the above description, for the grating waveguide device shown in fig. 5 or fig. 7, the K vector of the coupled-in waveguide beam can be expressed as the external incident beam K vector component and two grating vectors K of the virtual two-dimensional grating 1 ，K 2 Is a superposition of integer multiples of (a). The K vector of the diffracted beam propagating through total reflection in the waveguide and the diffracted beam coupled out of the human eye can be expressed as the K vector component of the incident beam reaching the region and the two grating vectors K of the virtual two-dimensional grating 1 ，K 2 Is a superposition of integer multiples of (a).
More specifically, the grating vector of the grating region may be expressed as a superposition of integer multiples of n grating vectors of the same virtual two-dimensional grating by adjusting the periodicity of the grating region. Wherein the periodicity of the grating region includes the pitch and direction of the grating.
The grating vectors of different grating areas are expressed as the superposition of integer multiples of n grating vectors of the same virtual two-dimensional grating, so that the light beam propagation of different grating areas can always keep higher image definition, the definition of the coupled human eye diffraction light beam is further ensured, and the higher definition of the grating waveguide scheme display image is realized.
It is further preferred that the angle between the two grating vectors of the virtual two-dimensional grating is between 0 and 180 degrees or between-180 and 0 degrees, so as to ensure that the two grating vectors are not collinear, and it should be noted that the end point values are not included between 0 and 180 degrees or between-180 and 0 degrees.
Further, in the grating waveguide device of the present invention, on the basis of expressing the grating vector of the grating region as a superposition of integer multiples of n grating vectors of the same virtual two-dimensional grating, for an incident light beam of a specific wavelength on the grating waveguide device, the magnitude of the in-plane component of the K vector of any non (0, 0) order diffracted light beam formed by the grating waveguide device is larger than the wave number of the incident light beam of the specific wavelength in the substrate external material, and the magnitude of the in-plane component of the K vector of at least one non (0, 0) order diffracted light beam is smaller than the wave number of the incident light beam of the specific wavelength in the substrate internal material.
Description: the (0, 0) order diffracted beam is an undiffracted beam, and includes a K vector of an incident beam and a K vector of an outcoupled human eye beam.
Specifically, the refractive index of the substrate interior material and the refractive index of the substrate exterior material may be adjusted such that, for an incident light beam of a specific wavelength, the magnitude of the K-vector waveguide in-plane component of any non- (0, 0) order diffracted light beam formed by the incident light beam is larger than the wavenumber of the incident light beam of the specific wavelength in the substrate exterior material, and the magnitude of the K-vector waveguide in-plane component of at least one non- (0, 0) order diffracted light beam is smaller than the wavenumber of the incident light beam of the specific wavelength in the substrate interior material.
As shown in fig. 9, a schematic diagram of a diffraction beam K vector formed by coupling an incident beam with a specific wavelength into the grating waveguide device shown in fig. 5, where the outer circle size represents the wave number of the incident beam with the specific wavelength in the material inside the substrate, and the inner circle size represents the wave number of the incident beam with the specific wavelength in the material outside the substrate, as can be seen from the figure, the magnitude of the K vector in-plane component of the non (0, 0) order diffraction beam is larger than the wave number of the incident beam with the specific wavelength in the material outside the substrate, so that the coupled beam of the waveguide system is only the (0, 0) order diffraction beam, and no ghost of other orders is generated.
Meanwhile, the magnitudes of the K vector waveguide plane components of the (1, 0), (1, 1), (0, 1), (-1, 0), (-1, -1) and (0, -1) order diffraction beams are smaller than the wave numbers of the incident beams with specific wavelengths in the material inside the substrate, so that the total reflection propagation inside the waveguide can be realized, and the functions of coupling in and expanding the pupil are achieved.
As shown in fig. 10, a schematic diagram of a K vector of a diffracted beam formed by coupling an incident beam with a specific wavelength into the grating waveguide device shown in fig. 7, where the outer circle size represents the wave number of the incident beam with the specific wavelength in the material inside the substrate, and the inner circle size represents the wave number of the incident beam with the specific wavelength in the material outside the substrate, as can be seen from the figure, the K vector of the non (0, 0) order diffracted beam has a larger in-plane component than the wave number of the incident beam with the specific wavelength in the material outside the substrate, so that the coupled beam of the waveguide system is only the (0, 0) order diffracted beam, and no ghost of other orders is generated.
Meanwhile, the magnitudes of the K vector waveguide plane components of the (1, 0), (0, -1) and the (1, 0) diffraction beams are smaller than the wave numbers of the incident beams with specific wavelengths in the material inside the substrate, so that the total reflection propagation inside the waveguide can be realized, and the effects of coupling in and expanding the pupil are achieved.
In order to ensure that the light beam is capable of total reflection propagation within the grating waveguide, for light beams of a specific wavelength (including both incident and propagating light beams), at least one of the grating regions has a magnitude of the in-plane waveguide component of the K vector of the diffracted light beam of more than one non-outcoupling order that is greater than the wavenumber of the light beam of the specific wavelength in the substrate outer material and less than the wavenumber of the light beam of the specific wavelength in the substrate inner material.
Description: the non-outcoupling order refers herein to the non-outcoupling human eye order.
The first surface and the second surface of the substrate may be planar, or at least one of the first surface and the second surface of the substrate may be a non-planar continuous curved surface.
The arrangement of the grating areas described above needs to be such that the beam has one or more of a coupling-in, a pupil-expanding and a coupling-out function. Each grating region can have one or more of coupling-in, pupil expansion and coupling-out functions for a light beam projected and incident on the waveguide or a light beam transmitted to the grating region, which is determined by grating diffraction characteristics.
When the grating area adopts a plurality of grating areas, the integral grating layout formed by the plurality of grating areas meets the functions of coupling in, expanding pupil and coupling out light beams. I.e. the combination of grating areas has the complete functions of coupling in, expanding the pupil, coupling out the light beam.
The grating regions described above may have other grating groove type parameters, including dimensions and materials, within them, other than the same or different grating periods.
The shape of the grating region may be any continuous closed pattern including, but not limited to, triangular, rectangular, parallelogram, polygonal, circular, smooth-shaped, matte-shaped, etc.
As a preferred embodiment, for the case where a grating waveguide device employs a plurality of grating regions, at least one grating region diffracts a light beam reaching the region to propagate in the opposite direction, i.e. the incident light beam differs from the diffracted light beam by 90 degrees to 180 degrees or-180 degrees to-90 degrees in azimuth. Thereby improving the light energy utilization rate of the grating waveguide device for the coupled light beam.
There are two main technical routes for the grating waveguide scheme:
1. a technical route using three one-dimensional gratings is shown in fig. 11. Arrows represent the direction of light propagation in the grating waveguide. The coupling-in grating 1 couples the light beam of the projection system into the optical lens and propagates to the turning grating 8, the turning grating 8 converts the coupled light beam by 90 degrees through the diffraction effect of the grating to be input into the coupling-out grating 2, and finally the coupling-out grating couples the light beam to the human eye. This solution requires three gratings, typically requiring a large grating area to achieve a certain field angle and a certain pupil expansion range. The proposal needs to use larger grating area, so that the size of the waveguide system is increased, which is not beneficial to the miniaturization of the system, in particular to the augmented reality application under the requirement of large field angle facing to consumer level.
2. A technical route using two gratings, one-dimensional grating as coupling in and one two-dimensional grating as coupling out. As shown in fig. 12, the coupling-in grating 1 couples the light beam of the projection system into the optical lens and propagates to the coupling-out grating 2, and the coupling-out grating 2 is a two-dimensional grating capable of diffracting in multiple directions simultaneously, thereby playing roles of coupling-out and pupil expansion simultaneously. This approach saves grating area compared to approach 1, but because the two-dimensional grating has more diffraction orders, part of the diffracted beam is wasted propagating outside the outcoupling region, reducing the optical efficiency of the waveguide system. On the other hand, in higher optical efficiency applications, other performance metrics such as pupil expansion uniformity, imaging uniformity, etc. may be correspondingly reduced.
In order to solve the above problems, the diffraction propagation direction of the light beam on the waveguide needs to be optimized, and then a grating waveguide structure with better comprehensive performance needs to be adopted.
Thus, the present invention selects a particular one-dimensional or two-dimensional grating structure in a particular region of the grating waveguide.
Specifically, the grating region includes a one-dimensional grating region, a first two-dimensional grating region, and a second two-dimensional grating region.
The one-dimensional grating region is arranged on the first surface and/or the second surface of the substrate as a coupling-in grating region.
The first two-dimensional grating region is arranged on the first surface of the substrate as a pupil-expanding-coupling-out grating region.
The second two-dimensional grating region is arranged on the second surface of the substrate as a pupil-expanding-coupling-out grating region.
As shown in fig. 5, the one-dimensional grating region includes only a single one-dimensional grating, the single one-dimensional grating is disposed on the first surface of the substrate, the first two-dimensional grating region (two-dimensional grating a) is disposed on the first surface of the substrate, and the second two-dimensional grating region (two-dimensional grating B) is disposed on the second surface of the substrate.
As shown in fig. 7, the one-dimensional grating region includes a one-dimensional grating a, a one-dimensional grating B, a one-dimensional grating C, and a one-dimensional grating D, where the one-dimensional grating a, the one-dimensional grating C, and the one-dimensional grating D are disposed on a first surface of the substrate, the one-dimensional grating B is disposed on a second surface of the substrate, the first two-dimensional grating region (two-dimensional grating E) is disposed on the first surface of the substrate, and the second two-dimensional grating region (two-dimensional grating F) is disposed on the second surface of the substrate.
Based on the above description, the grating waveguide of the present invention adopts a combination of a plurality of two-dimensional gratings as turning-coupling-out gratings, which improves the light energy utilization rate of the grating waveguide for the coupling-in light beam, while maintaining a small system size. Moreover, due to the advantages of size and light energy utilization rate, the grating waveguide can exert higher degree of freedom to improve performance indexes such as the pupil expansion range, pupil expansion uniformity (namely, the uniformity of light effect at different positions in the pupil expansion range), field angle, imaging uniformity and the like of the waveguide.
As a preferred embodiment, the first two-dimensional grating region and the second two-dimensional grating region diffract the light beam reaching the region to propagate in opposite directions, i.e. the incident light beam differs from the diffracted light beam by 90 degrees to 180 degrees or-180 degrees to-90 degrees in azimuth. The light energy utilization rate of the grating waveguide to the coupled light beam is further improved.
The beam propagation process of the grating waveguide structure of fig. 5 and 7 is further described in detail below:
the grating waveguide structure shown in fig. 5:
s1: preparing an incident projection beam of a grating waveguide, the incident K vector of the incident projection beam being identical to the (0, 0) order diffracted beam K vector in FIG. 9 (only the in-grating plane component of the wave vector is considered here);
s2: the incident projection beam is coupled into the one-dimensional grating on the first surface of the substrate, and the K vector of the diffracted beam is the K vector component of the incident projection beam and the K vector of the one-dimensional grating in FIG. 6 w1 To obtain a diffraction beam K vector capable of total reflection propagation in the waveguide, namely a (1, 1) order diffraction beam K vector in FIG. 9, wherein the propagation direction of the diffraction beam is 3 o' clock;
s3: the 3 o' clock direction propagating beam propagates by total reflection inside the substrate to the two-dimensional grating A of the first surface of the substrate, where the diffraction beam K vector is the (1, 1) order diffraction beam K vector component and the grating vector K of the two-dimensional grating A in FIG. 6 WA_1 、K WA_2 The (1, 0) order diffracted beam K vector, (0, 1) order diffracted beam K vector, and (0, 0) order diffracted beam K vector in fig. 9 are newly added to the diffracted beam K vector capable of total reflection propagation within the waveguide; therefore, on one hand, the diffracted light beam continues to propagate along the original propagation direction (3 o ' clock direction), and on the other hand, the diffracted light beam is respectively turned to 1 o ' clock, 5 o ' clock and coupled out to propagate along the direction of entering human eyes;
s4: 1 Point in step S3The two-dimensional grating B of the second surface of the substrate, the propagation light beam in the clock direction and the propagation light beam in the 5 o' clock direction are propagated, and the K vector of the newly added diffraction light beam is the K vector component of the (1, 0) order diffraction light beam, the K vector component of the (0, 1) order diffraction light beam and the grating vector K of the two-dimensional grating B in fig. 6 WB_2 、K WB_1 I.e., the (-1, -1) order diffracted beam K vector in fig. 9, the diffracted beam propagation direction is 9 o' clock; the 3 o' clock direction propagating beam in step S3 is propagated to the two-dimensional grating B of the second surface of the substrate, and the K vector of the newly added diffracted beam is the K vector component of the (1, 1) order diffracted beam and the grating vector K of the two-dimensional grating B in FIG. 6 WB_1 、K WB_2 I.e., (0, -1) order diffracted beam K vector, (-1, 0) order diffracted beam K vector in fig. 9, the diffracted beam propagation directions are 11 o 'clock and 7 o' clock;
s5: the 1 o 'clock direction propagating beam, the 3 o' clock direction propagating beam and the 5 o 'clock direction propagating beam in the step S3 and the 7 o' clock direction propagating beam, the 9 o 'clock direction propagating beam and the 11 o' clock direction propagating beam in the step S4 continue to propagate to the two-dimensional grating a of the first surface of the substrate, and the diffracted beam K vector is a grating vector K corresponding to the K vector component of the diffracted beam K of the order and the two-dimensional grating a in fig. 6 WA_1 、K WA_2 To obtain the K vectors of all the diffracted beams of the orders shown in fig. 9, i.e. the diffracted beams are respectively turned to the 1 o 'clock direction, the 3 o' clock direction, the 5 o 'clock direction, the 7 o' clock direction, the 9 o 'clock direction and the 11 o' clock direction for propagation, and are coupled out into human eyes at the same time;
s6: the 7 o 'clock direction propagation beam and the 11 o' clock direction propagation beam in the step S4 and the 7 o 'clock direction propagation beam and the 11 o' clock direction propagation beam in the step S5 continue to propagate to the two-dimensional grating B of the second surface of the substrate, and the newly added diffraction K vector is a (-1, 0) order diffraction beam K vector component, a (0, -1) order diffraction beam K vector component, and a grating vector K of the two-dimensional grating B in fig. 6 WB_2 、K WB_1 I.e. the (1, 1) order diffracted beam K vector in fig. 9, the diffracted beam propagates in the 3 o' clock direction; the (-1, -1) order propagating beams in step S4 and step S5 arePropagating to two-dimensional grating B, and adding diffraction K vector of (-1, -1) order diffraction beam K vector component and grating vector K of two-dimensional grating B in figure 6 WB_1 、K WB_2 The superposition of (0, 1) order diffracted beam K vector, (1, 0) order diffracted beam K vector in fig. 9, the diffracted beams propagate in the 5, 1 o' clock directions, respectively;
s7: steps S4-S6 are continuously cycled to achieve multi-directional expansion of the coupled-in beam in the grating waveguide, including counter-propagation.
The grating waveguide structure shown in fig. 7:
p1: preparing an incident projection beam of a grating waveguide, the incident K vector of the incident projection beam being the same as the (0, 0) order diffracted beam K vector in FIG. 10 (only the in-grating plane component of the wave vector is considered here);
p2: a part of the incident projection beam is coupled into the one-dimensional grating A on the first surface of the substrate, and the diffraction beam K vector is the incident K vector component of the incident projection beam and the grating vector K of the one-dimensional grating A on the first surface of the substrate in FIG. 8 wA To obtain a diffraction beam K vector capable of total reflection propagation in the waveguide, namely a (1, 0) order diffraction beam K vector in FIG. 10, wherein the propagation direction of the diffraction beam is 3 o' clock;
p3: another part of the incident projection beam is transmitted through the one-dimensional grating A and coupled in by the one-dimensional grating B on the second surface of the substrate in FIG. 7, and the diffraction beam K vector is the incident K vector component of the incident projection beam and the grating vector K of the two-dimensional grating B on the second surface of the substrate in FIG. 8 wB To obtain a diffraction beam K vector capable of total reflection propagation in the waveguide, namely a (0, 1) order diffraction beam K vector and a (0, -1) order diffraction beam K vector in fig. 10, wherein the propagation directions of the diffraction beams are respectively 12 o 'clock and 6 o' clock;
p4: the 12 o 'clock direction propagation beam and the 6 o' clock direction propagation beam in the step P3 are propagated to the one-dimensional grating C and the one-dimensional grating D of the first surface of the substrate in FIG. 7 by total reflection inside the substrate, and the K vector of the newly added diffraction beam is the K vector component of the (0, 1) order diffraction beam and the K vector component of the (1) order diffraction beam in FIG. 8 respectivelyGrating vector K of one-dimensional grating C WC And (0, -1) order diffracted beam K vector component with the grating vector K of the one-dimensional grating D of FIG. 8 WD I.e. the (1, 0) order diffracted beam K vector in fig. 10, the direction of propagation of the diffracted beam is 3 o' clock;
p5: the 3 o' clock propagating beams of step P2 and step P4 are propagated to the two-dimensional grating E of the first surface of the substrate in fig. 7, and the K vector of the newly added diffracted beam is the (1, 0) order diffracted beam K vector component and the grating vector K of the two-dimensional grating E in fig. 8 WE_2 、K WE_1 The (0, 1) order diffracted beam K vector, (0, -1) order diffracted beam K vector in fig. 10, so that, on the one hand, the diffracted beam continues to propagate in the original propagation direction (3 o ' clock direction), and, on the other hand, the diffracted beam propagates in the 12 o ' clock direction and in the 6 o ' clock direction, respectively;
p6: the 12 o ' clock direction propagating beam, the 3 o ' clock direction propagating beam, and the 6 o ' clock direction propagating beam in the step P5 are propagated to the two-dimensional grating F of the second surface of the substrate in fig. 7, and the newly added diffraction beam K vector is the (0, 1) order diffraction beam K vector component, (1, 0) order diffraction beam K vector component, (0, -1) order diffraction beam K vector component and the grating vector K of the two-dimensional grating F in fig. 10 WF_2 、K WF_1 I.e. the direction of propagation of the diffracted beam is coupled out into the human eye;
p7: after the 12 o 'clock direction propagation beam and the 6 o' clock direction propagation beam in the above step P6 continue to propagate to the two-dimensional grating E, the newly added diffraction beam K vector is the (0, 1) order diffraction beam K vector component, the (0, -1) order diffraction beam K vector component, and the grating vector K of the two-dimensional grating E in fig. 8 WE_1 、K WE_2 I.e., the (-1, 0) order diffracted beam K vector in fig. 10, i.e., the diffracted beam propagates back toward 9 o' clock;
p8: after the 12 o 'clock direction propagating beam, the 3 o' clock direction propagating beam, the 6 o 'clock direction propagating beam, and the 9 o' clock direction propagating beam in the above step P7 are continuously propagated to the two-dimensional grating F, the K vector of the newly added diffracted beam is (0,1) The (1, 0) order diffracted beam K vector component, (0, -1) order diffracted beam K vector component, (-1, 0) order diffracted beam K vector component, and the grating vector K of the two-dimensional grating F in fig. 8 WF_2 、K WF_1 I.e. the direction of propagation of the diffracted beam is coupled out into the human eye;
p9: after the 12 o 'clock direction propagation beam, the 3 o' clock direction propagation beam, the 6 o 'clock direction propagation beam, and the 9 o' clock direction propagation beam in the above step P8 are propagated to the two-dimensional grating E, the newly added diffraction beam K vector is the (0, 1) order diffraction beam K vector component, the (1, 0) order diffraction beam K vector component, the (0, -1) order diffraction beam K vector component, the (-1, 0) order diffraction beam K vector component, and the grating vector K of the two-dimensional grating E in fig. 8 WE_1 、K WE_2 I.e. the (0, 1) order diffracted beam K vector, (1, 0) order diffracted beam K vector, (0, -1) order diffracted beam K vector, (-1, 0) order diffracted beam K vector, i.e. the diffracted beam propagates further towards 12 o 'clock, 3 o' clock, 6 o 'clock and 9 o' clock directions;
p10: steps P8-P9 are continuously cycled to achieve multi-directional expansion of the coupled-in beam in the grating waveguide, including counter-propagation.
The invention also provides a waveguide system for augmented reality display, which comprises a grating waveguide. Wherein, at least one grating waveguide adopts the grating waveguide device for augmented reality display.
The above embodiments are only for illustrating the technical solution of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the above embodiments, one skilled in the art may make modifications and equivalents to the specific embodiments of the present invention, and any modifications and equivalents not departing from the spirit and scope of the present invention are within the scope of the claims of the present invention.
Claims (14)
1. A grating waveguide device for augmented reality display, the grating waveguide device comprising a substrate and at least one grating region;
the grating area is arranged on the substrate;
the grating vector of each grating region is expressed as the superposition of integer multiples of n grating vectors of the same virtual two-dimensional grating;
wherein n is an integer not less than 2;
wherein, the virtual two-dimensional grating represents the size and direction of a grating period which is theoretically designed;
for an incident light beam of a particular wavelength, the magnitude of the K-vector waveguide in-plane component of any non- (0, 0) order diffracted light beam formed by the grating waveguide device is greater than the wavenumber of the incident light beam of the particular wavelength in the substrate exterior material, and the magnitude of the K-vector waveguide in-plane component of at least one non- (0, 0) order diffracted light beam is less than the wavenumber of the incident light beam of the particular wavelength in the substrate interior material.
2. The grating waveguide device for augmented reality display of claim 1, wherein the grating region is a plurality of grating regions.
3. The grating waveguide apparatus for augmented reality display of claim 2, wherein the grating vector of each grating region is expressed as a superposition of integer multiples of n grating vectors of the same virtual two-dimensional grating, comprising:
and expressing the grating vector of each grating region as the superposition of integer multiples of two grating vectors of the same virtual two-dimensional grating.
4. A grating waveguide device for an augmented reality display according to claim 3, wherein the angle between the two grating vectors of the virtual two-dimensional grating is between 0 degrees and 180 degrees or between-180 degrees and 0 degrees.
5. The grating waveguide apparatus for augmented reality display according to claim 1 or 2, wherein the grating vector of the grating region is expressed as a superposition of integer multiples of n grating vectors of the same virtual two-dimensional grating by adjusting the periodicity of the grating region;
wherein the periodicity of the grating region includes the pitch and direction of the grating.
6. The grating waveguide device for augmented reality display of claim 1, wherein the refractive index of the substrate interior material and the refractive index of the substrate exterior material are both adjustable on the basis of the virtual two-dimensional grating.
7. The raster waveguide apparatus for augmented reality display of claim 1,
for a light beam of a particular wavelength, at least one of the grating regions has a magnitude of a waveguide in-plane component of a K-vector of the diffracted light beam of more than one non-coupling order that is greater than a wavenumber of the light beam of the particular wavelength in the substrate outer material and less than a wavenumber of the light beam of the particular wavelength in the substrate inner material.
8. The grating waveguide device for augmented reality display of claim 1, wherein the grating region has one or more of a coupling-in, a mydriasis, and a coupling-out function for the light beam.
9. The grating waveguide device for augmented reality display of claim 2, wherein the plurality of grating regions form an overall grating layout that satisfies the functions of coupling in, pupil expanding, and coupling out light beams.
10. The grating waveguide device for augmented reality display of claim 2, wherein at least one of the plurality of grating regions diffracts a light beam reaching that region to propagate in an opposite direction.
11. The raster waveguide apparatus for augmented reality display of claim 2,
the substrate adopts a light-transmitting substrate;
the substrate has a first surface and a second surface;
the first surface and the second surface are oppositely arranged;
the grating region is located on the first surface, the second surface or inside the substrate.
12. The grating waveguide device for an augmented reality display of claim 11, wherein the grating region comprises a one-dimensional grating region, a first two-dimensional grating region, and a second two-dimensional grating region;
the one-dimensional grating area is used as a coupling-in grating area and is arranged on the first surface and/or the second surface of the substrate;
the first two-dimensional grating area is used as a pupil expansion-coupling-out grating area and is arranged on the first surface of the substrate;
the second two-dimensional grating region is arranged on the second surface of the substrate as a pupil-expanding-coupling-out grating region.
13. The raster waveguide apparatus for augmented reality display of claim 12,
the second two-dimensional grating region diffracts the light beam reaching the region to propagate in the opposite direction.
14. A waveguide system for augmented reality display, characterized in that,
comprises a grating waveguide;
wherein at least one of said grating waveguides employs a grating waveguide device for augmented reality display according to any one of claims 1-13.
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| CN113156581A (en) * | 2021-05-27 | 2021-07-23 | Oppo广东移动通信有限公司 | Diffractive waveguide device, near-to-eye display apparatus and method of manufacture |
| CN113325506A (en) * | 2020-02-28 | 2021-08-31 | 苏州苏大维格科技集团股份有限公司 | Holographic optical waveguide lens and augmented reality display device |
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| IL274977B2 (en) * | 2017-12-15 | 2023-10-01 | Magic Leap Inc | Eyepieces for augmented reality display system |
| EP3884337A4 (en) * | 2018-11-20 | 2022-08-17 | Magic Leap, Inc. | Eyepieces for augmented reality display system |
| GB201905773D0 (en) * | 2019-04-25 | 2019-06-05 | Wave Optics Ltd | Display for augmented reality |
| EP4260127A1 (en) * | 2020-12-10 | 2023-10-18 | Snap, Inc. | Optical device |
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| CN113156581A (en) * | 2021-05-27 | 2021-07-23 | Oppo广东移动通信有限公司 | Diffractive waveguide device, near-to-eye display apparatus and method of manufacture |
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