CN115903122A - 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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- CN115903122A CN115903122A CN202310018538.4A CN202310018538A CN115903122A CN 115903122 A CN115903122 A CN 115903122A CN 202310018538 A CN202310018538 A CN 202310018538A CN 115903122 A CN115903122 A CN 115903122A
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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 area; the grating area is arranged on the substrate; the grating vector of each grating area is expressed as the superposition of integral multiples of n grating vectors of the same virtual two-dimensional grating, wherein n is an integer not less than 2. By adopting the design, the grating waveguide device realizes that the displayed image of the grating waveguide scheme keeps 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 is intended to provide additional information (so-called "augmentation") to a user in the real world by some technical means, such as intelligently displaying each part while a worker is operating the machine (see fig. 1), and indicating a left-turn or straight directional arrow on a real road while a driver is driving a vehicle. The technology organically integrates the image of the virtual world and the scene of the real world, and provides richer information and immersion experience for a user by deeply integrating the calculated information with the real world. In the information age, augmented reality is the most direct way to acquire information, has extremely wide application scenarios, such as military training, medical assistance, educational learning, game industry, entertainment art and the like, and is widely considered as the next generation computing platform following computers.
Augmented reality technology can be implemented by many hardware platforms, wherein grating waveguides have become one of the most mainstream technical routes in the industry. The basic principle of the grating waveguide scheme is shown in fig. 2, at least one grating region (schematically illustrated as an incoupling grating 1 and an outcoupling grating 2) is arranged on the surface or inside of an optical substrate 3, an incident beam 5 of a projection mechanism 4 is coupled into the optical substrate 3 by the incoupling grating 1, total reflection occurs in the optical substrate 3, and when encountering another outcoupling grating 2, a part of diffracted beam 6 is coupled out, so that a human eye 7 can see the same image as the output of the projection mechanism 4 behind the outcoupling grating 2, and meanwhile, the human eye 7 can see the image of the real world through the optical substrate 3, and the two images are overlapped to realize the augmented reality function.
But the problem of poor display image definition may exist for the existing complex grating waveguide with a plurality of grating regions.
Disclosure of Invention
In order to overcome the defects of the prior art, the main object of the present 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 area;
the grating area is arranged on the substrate;
the grating vector of each grating area is expressed as the superposition of integral multiples of n grating vectors of the same virtual two-dimensional grating.
Further, the grating area is a plurality of grating areas.
Further, the expression of the grating vectors of different grating regions is the superposition of integer multiples of n grating vectors of the same virtual two-dimensional grating, including:
and expressing the grating vectors of different grating areas as superposition of integral multiples of two grating vectors of the same virtual two-dimensional grating.
Furthermore, the included angle between the two grating vectors of the virtual two-dimensional grating is between 0 degree and 180 degrees or between-180 degrees and 0 degree.
Further, expressing the grating vectors of the grating area as the superposition of integral multiples of n grating vectors of the same virtual two-dimensional grating by adjusting the periodicity of the grating area;
wherein the periodicity of the grating regions comprises the pitch and direction of the grating.
Further, for an incident light beam with a specific wavelength, the size of the waveguide 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 with the specific wavelength in the material outside the substrate, and the size of the waveguide plane component of at least one non- (0,0) order diffracted light beam is smaller than the wave number of the incident light beam with the specific wavelength in the material inside the substrate.
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 more than one in-waveguide-plane component of the K-vector of the diffracted light beam of the non-outcoupling order with a magnitude larger than the wave number of the light beam of the specific wavelength in the material outside the substrate and smaller than the wave number of the light beam of the specific wavelength in the material inside the substrate.
Further, the grating region has one or more of functions of coupling in, expanding pupil and coupling out for the light beam.
Further, the whole grating layout formed by the 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 the region to propagate in the opposite direction.
Further, the substrate is 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 area comprises a one-dimensional grating area, a first two-dimensional grating area and a second two-dimensional grating area;
the one-dimensional grating area is used as an in-coupling grating area and is arranged on the first surface and/or the second surface of the substrate;
the first two-dimensional grating region is arranged on the first surface of the substrate as a pupil expanding-coupling grating region;
the second two-dimensional grating region is arranged on the second surface of the substrate as an expanded pupil-coupling 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;
at least one grating waveguide 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 region arranged on the substrate, wherein the grating vector of each grating region is expressed as the superposition of integral multiples of two grating vectors of the same virtual two-dimensional grating, so that the higher image definition of the light beam transmission of different grating regions is always kept, the definition of the diffracted light beam coupling out human eyes is further ensured, and the higher definition of the displayed image of a grating waveguide scheme is further kept. The grating waveguide system also has the advantages of small size, high optical efficiency, large pupil expanding range, good pupil expanding uniformity, large field angle, good imaging uniformity, no ghost and the like.
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, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
FIG. 1 is a schematic view of a scene in which a user uses an augmented reality technique during operation of a machine;
FIG. 2 is a schematic diagram of the basic principle of a grating waveguide scheme;
FIG. 3 is a diagram illustrating grating vectors of a one-dimensional grating;
FIG. 4 is a grating vector diagram of a two-dimensional grating;
FIG. 5 is a schematic diagram of a first example of a grating waveguide apparatus for an augmented reality display of the present invention;
FIG. 6 is a diagram of raster vectors for the raster region shown in FIG. 5;
FIG. 7 is a schematic diagram of a second example of a grating waveguide apparatus for an augmented reality display of the present invention;
FIG. 8 is a diagram of raster vectors for the raster region shown in FIG. 7;
FIG. 9 is a schematic diagram of a K vector of an incident beam of a particular wavelength coupled into a diffracted beam formed by the grating waveguide apparatus of FIG. 5;
FIG. 10 is a schematic diagram of a K vector of a diffracted beam formed by coupling an incident beam of a specific wavelength into the grating waveguide device of FIG. 7;
FIG. 11 is a schematic diagram of a prior art grating design for a grating waveguide arrangement;
figure 12 is another schematic of a grating design in a prior art grating waveguide scheme.
Description of the reference numerals
1-incoupling grating, 2-outcoupling grating, 3-optical substrate, 4-projection mechanism, 5-incident beam, 6-diffracted beam, 7-human eye, 8-turning grating.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments of the present invention, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Description of the meanings:
1. raster vector
The grating has a grating vector, e.g. for a one-dimensional grating, the size of the grating vector is K =2 pi/d, as shown in fig. 3, and the direction of the grating vector is the same as the direction of the period of the grating structure, where d is the period of said one-dimensional grating.
For a two-dimensional grating, as shown in FIG. 4, two grating vectors are illustrated, the first grating vector having a magnitude of K 1 =2 pi/d 1/sin (a), the size of the second raster vector is K 2 =2 pi/d 2/sin (a), the direction of the first grating vector being perpendicular to the second period direction of the grating structure, the direction of the second grating vector being perpendicular to the first period direction of the grating structure, wherein d 1 Is the period of the first grating, d 2 And a is the period of the second grating, and a is the included angle between the period direction of the first grating and the period direction of the second grating.
2. K-space representation of grating waveguides
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 associates K-vectors with 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 input and output beams with respective propagation angles to be understood as a group of points (e.g., a rectangle) in K-space. A diffractive feature that changes the direction of propagation of a light beam while propagating 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 translated K-space positions correspond to a new set of K-vectors, which in turn represent new propagation angles of the light beam or rays after interaction with the grating diffractive features.
In the K-space of the grating waveguide, the particular K-vector is determined by the addition of the K-vector component of the beam in the plane of the grating to the vector of the grating vector.
3. Diffraction order
The diffraction orders of a two-dimensional grating are generally represented in the form of coordinates (x, y), where x and y represent the diffraction orders of two dimensions of the two-dimensional grating, respectively. Such as the (1,0) diffraction order, the (1,1) diffraction order, and so on.
It should be noted that although the diffraction orders of the two-dimensional grating are expressed in the form of coordinates (x, y), the diffraction orders do not represent the same diffraction directions under different definitions of the dimensions of the two-dimensional grating. The diffraction direction corresponding to the diffraction order is defined by the dimension of the two-dimensional grating, for example, (1,0) the diffraction order may correspond to the 1 o 'clock direction of the clock under a certain dimension definition, and may also correspond to the 3 o' clock direction of the clock under another dimension definition.
4. Virtual two-dimensional grating
Reference herein to a "virtual two-dimensional grating" denotes the 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 has 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 specifically, the grating region may be disposed on the first surface, the second surface, or inside the substrate.
The grating vector of each grating area is expressed as the superposition of integral 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 arranged on the grating waveguide are expressed as the superposition of integral multiples 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 case of using multiple grating regions for a grating waveguide. The grating vectors of different grating regions in fig. 5 may be expressed as a superposition of integer multiples of the 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:
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 K 1 、K 2 Superposition of integer multiples of:
raster vector K of one-dimensional raster 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, another scenario in which multiple grating regions are employed for a grating waveguide is shown in FIG. 7. The grating vectors of different grating regions in fig. 7 may be expressed as a superposition of integer multiples of the 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:
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 K 1 、K 2 Superposition of integer multiples of:
one-dimensional grating A with a 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 with two grating vectors K WE_1 =-K 1 -K 2 、K WE_2 =-K 1 +K 2 ；
One-dimensional grating B with grating vector K WB =K 2 ；
Two-dimensional grating F with 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 K vector component of the external incident beam and two grating vectors K of the virtual two-dimensional grating 1 ，K 2 The superposition of integer multiples of. The K-vector of the diffracted beam which propagates totally reflected in the waveguide and which is coupled out of the human eye can likewise be expressed as the K-vector component of the incident beam reaching this region and the two grating vectors K of the virtual two-dimensional grating 1 ，K 2 And superposition of integer multiples of the sum of the two.
More specifically, the grating vectors of the grating regions can be expressed as a superposition of integer multiples of the n grating vectors of the same virtual two-dimensional grating by adjusting the periodicity of the grating regions. Wherein the periodicity of the grating regions comprises the pitch and direction of the grating.
The grating vectors of different grating areas are expressed as the superposition of integral multiples of n grating vectors of the same virtual two-dimensional grating, so that the light beam transmission of different grating areas can always keep higher image definition, the definition of the diffracted light beams of the human eyes can be guaranteed, and the higher definition of the displayed image of the grating waveguide scheme can be realized.
It is further preferable that the angle between the two raster vectors of the virtual two-dimensional raster is between 0 degree and 180 degrees or between-180 degrees and 0 degrees, so as to ensure that the two raster vectors are not in the same line, and it should be noted that the value between 0 degree and 180 degrees or between-180 degrees and 0 degrees does not include an endpoint value here.
Furthermore, the grating waveguide device of the present invention expresses the grating vectors of the grating region as the superposition of integral multiples of n grating vectors of the same virtual two-dimensional grating, and for the incident light beams with specific wavelength on the grating waveguide device, the magnitude of any waveguide in-plane component of the K vector of the (0,0) order diffraction light beam is larger than the wave number of the incident light beam with specific wavelength in the substrate external material, and the magnitude of at least one waveguide in-plane component of the K vector of the (0,0) order diffraction light beam is smaller than the wave number of the incident light beam with specific wavelength in the substrate internal material.
Description of the drawings: here, the (0,0) order diffracted light beams are undiffracted light beams, including the K vector of the incident light beam and the K vector of the coupled-out human eye light beam.
Specifically, the refractive index of the material inside the substrate and the refractive index of the material outside the substrate may be adjusted so that, for an incident light beam of a specific wavelength, the magnitude of any waveguide in-plane component other than the K vector of the (0,0) order diffracted light beam is larger than the wave number of the incident light beam of the specific wavelength in the material outside the substrate, and the magnitude of at least one waveguide in-plane component other than the K vector of the (0,0) order diffracted light beam is smaller than the wave number of the incident light beam of the specific wavelength in the material inside the substrate.
As shown in fig. 9, a schematic diagram of K vectors of diffracted light beams formed by the grating waveguide device shown in fig. 5 for coupling incident light beams with specific wavelengths, wherein the size of the outer circle represents the wave number of the incident light beams with specific wavelengths in the material inside the substrate, and the size of the inner circle represents the wave number of the incident light beams with specific wavelengths in the material outside the substrate, and it can be seen from the diagram that the size of the in-waveguide plane component of the K vector of the incident light beams without the (0,0) order is larger than the wave number of the incident light beams with specific wavelengths in the material outside the substrate, so that the coupled-out light beams of the waveguide system are only the (0,0) order diffracted light beams, and no ghost image of other orders is generated.
Meanwhile, the sizes of the in-waveguide-plane components of the K vectors of (1,0), (1,1), (0,1), (-1,0), (-1, -1), (0, -1) order diffracted light beams are smaller than the wave number of the incident light beam with the specific wavelength in the material in the substrate, so that the incident light beam can be propagated in the waveguide by total reflection, and the effects of coupling and pupil expanding are achieved.
As shown in fig. 10, a schematic diagram of K vectors of diffracted light beams formed by coupling incident light beams with specific wavelengths into the grating waveguide device shown in fig. 7 is shown, wherein the size of the outer circle represents the wave number of the incident light beams with specific wavelengths in the material inside the substrate, and the size of the inner circle represents the wave number of the incident light beams with specific wavelengths in the material outside the substrate, and it can be seen from the diagram that the size of the components in the waveguide plane of the K vectors of the incident light beams without the (0,0) order diffracted light beams is larger than the wave number of the incident light beams with specific wavelengths in the material outside the substrate, so that the coupled light beams of the waveguide system are only (0,0) order diffracted light beams, and no ghost image of other orders is generated.
Meanwhile, the sizes of the in-waveguide-plane components of the K vectors of (1,0), (0, -1), (-1,0) and (0,1) order diffracted light beams are smaller than the wave number of the incident light beams with the specific wavelength in the material in the substrate, so that the total reflection propagation in the waveguide can be realized, and the effects of coupling and pupil expanding are realized.
In order to ensure that the light beams can realize total reflection propagation in the grating waveguide, for the light beams with specific wavelengths (including incident light beams and propagating light beams), the size of the in-waveguide plane component of the K vector of at least one grating region with more than one non-outcoupled-order diffracted light beams in the grating region is larger than the wave number of the light beams with specific wavelengths in the material outside the substrate and smaller than the wave number of the light beams with specific wavelengths in the material inside the substrate.
Description of the invention: the non-coupled-out order is referred to herein as the non-coupled-out eye order.
The first surface and the second surface of the substrate may be flat, or at least one of the first surface and the second surface of the substrate may be a non-flat continuous curved surface.
The arrangement of the grating region needs to satisfy one or more of the functions of coupling in, expanding pupil and coupling out of the light beam. Each grating region can have one or more of the functions of coupling in, expanding pupil and coupling out for the light beam projected and incident to the waveguide or the light beam propagating to the grating region, which is determined by the diffraction characteristics of the grating.
When the grating regions adopt a plurality of grating regions, the whole grating layout formed by the grating regions meets the functions of coupling in, expanding the pupil and coupling out the light beams. Namely, the combination of the grating regions has the functions of complete light beam coupling-in, pupil expanding and light beam coupling-out.
The grating region may have other grating groove parameters, including size and material, inside the grating region, besides the same or different grating periods.
The shape of the grating region may be any continuous closed figure, including but not limited to a triangle, a rectangle, a parallelogram, a polygon, a circle, a smooth shaped figure, a non-smooth shaped figure, etc.
As a preferred embodiment, a plurality of grating regions is used for the grating waveguide device, wherein at least one grating region diffracts the light beam arriving at the region to propagate in the opposite direction, i.e. the incident light beam differs in azimuth angle from the diffracted light beam by 90 to 180 degrees or-180 to-90 degrees. Thereby improving the light energy utilization rate of the grating waveguide device to the coupled-in light beam.
Currently, there are two main technical routes using the grating waveguide scheme:
1. the technical route using three one-dimensional gratings is shown in fig. 11. The 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 transmits to the turning grating 8, the turning grating 8 transfers the coupled-in light beam by 90 degrees through the diffraction effect of the grating and inputs the light beam into the coupling-out grating 2, and finally the light beam is coupled out to human eyes by the coupling-out grating. This solution requires three gratings, and usually requires a large grating area to achieve a certain field angle and a certain pupil expansion range. The scheme needs to use a larger grating area, so that the waveguide system is increased in size, the miniaturization of the system is not facilitated, and particularly the waveguide system is applied to augmented reality under the requirement of a large field angle facing to the consumption level.
2. The technical route of using two gratings, one-dimensional grating as incoupling and one two-dimensional grating as outcoupling. 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 and can diffract in multiple directions simultaneously, thereby functioning as both coupling-out and pupil expansion. Compared with the scheme 1, the scheme saves the grating area, but because the diffraction order of the two-dimensional grating is more, part of diffracted light beams are wasted after being transmitted to the outside of the coupling-out area, and the optical efficiency of the waveguide system is reduced. On the other hand, in higher optical efficiency applications, other performance metrics such as pupil uniformity, imaging uniformity, etc. may be correspondingly degraded.
In order to solve the above problems, the diffraction propagation direction of the light beam on the waveguide needs to be optimized, and a grating waveguide structure with better comprehensive performance needs to be adopted.
Therefore, the invention selects a specific one-dimensional or two-dimensional grating structure in a specific area 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 an in-coupling grating region.
The first two-dimensional grating region is arranged on the first surface of the substrate as a pupil expanding-coupling grating region.
The second two-dimensional grating region is arranged on the second surface of the substrate as a pupil expanding-coupling 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, the one-dimensional grating a, the one-dimensional grating C, and the one-dimensional grating D are disposed on the first surface of the substrate, the one-dimensional grating B is disposed on the 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 a turning-coupling-out grating, so as to improve the optical energy utilization rate of the grating waveguide for the coupled-in light beam, and simultaneously maintain a smaller system size. In addition, due to the advantages of size and light energy utilization rate, the grating waveguide can exert higher degree of freedom to improve performance indexes of the waveguide such as a pupil expanding range, pupil expanding uniformity (namely, light efficiency uniformity at different positions in the pupil expanding range), a field angle, imaging uniformity and the like.
As a preferred embodiment, the first two-dimensional grating region and the second two-dimensional grating region diffract the light beam arriving at the regions to propagate in opposite directions, i.e. the incident light beam and the diffracted light beam differ in azimuth angle by 90 to 180 degrees or-180 to-90 degrees. The optical energy utilization rate of the grating waveguide to the coupled-in light beam is further improved.
The following further describes the light beam propagation process of the grating waveguide structure shown in fig. 5 and 7:
the grating waveguide structure shown in fig. 5:
s1: preparing an incident projection beam of the grating waveguide whose incident K vector is the same as the (0,0) order diffracted beam K vector in fig. 9 (here, only the in-grating-plane component of the wave vector is considered);
s2: the incident projection beam is coupled in by the one-dimensional grating 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 in FIG. 6 w1 The diffraction beam K vector capable of propagating by total reflection in the waveguide, namely the (1,1) order diffraction beam K vector in FIG. 9,the propagation direction of the diffracted beam is 3 o' clock;
s3: the 3 o' clock direction propagated light beam propagates to the two-dimensional grating A on the first surface of the substrate through total reflection in the substrate, and at this time, the diffracted light beam K vector is the (1,1) order diffracted light beam K vector component and the grating vector K of the two-dimensional grating A in FIG. 6 WA_1 、K WA_2 Adding diffraction beam K vectors capable of being propagated in a waveguide through total reflection, namely (1,0) order diffraction beam K vectors, (0,1) order diffraction beam K vectors and (0,0) order diffraction beam K vectors in the graph 9; therefore, on one hand, the diffracted light beams continue to propagate along the original propagation direction (3 o ' clock direction), and on the other hand, the diffracted light beams respectively turn to 1 o ' clock and 5 o ' clock and are coupled out to enter the human eyes for propagation;
s4: the light beam propagating in the 1 o 'clock direction and the light beam propagating in the 5 o' clock direction in the step S3 are propagated to the two-dimensional grating B on the second surface of the substrate, and the newly added diffraction light beam K vector is the (1,0) order diffraction light beam K vector component, the (0,1) order diffraction light beam K vector component and the grating vector K of the two-dimensional grating B in fig. 6 WB_2 、K WB_1 The K vector of the (-1, -1) order diffracted beam in fig. 9, the propagation direction of the diffracted beam is 9 o' clock; the 3 o' clock direction transmission light beam in the step S3 is transmitted to the two-dimensional grating B on the second surface of the substrate, and the newly added diffraction light beam K vector is the (1,1) level diffraction light beam K vector component and the grating vector K of the two-dimensional grating B in the figure 6 WB_1 、K WB_2 The (0, -1) order diffracted beam K vector, the (-1,0) order diffracted beam K vector in fig. 9, the diffracted beam propagation directions being 11 o 'clock and 7 o' clock;
s5: the 1 o 'clock direction propagation light beam, the 3 o' clock direction propagation light beam and the 5 o 'clock direction propagation light beam in the step S3 and the 7 o' clock direction propagation light beam, the 9 o 'clock direction propagation light beam and the 11 o' clock direction propagation light beam in the step S4 continue to propagate to the two-dimensional grating A on the first surface of the substrate, and the diffraction light beam K vector is the vector component of the corresponding order diffraction light beam K and the grating vector K of the two-dimensional grating A in the figure 6 WA_1 、K WA_2 Are superimposed to obtain all of the components shown in FIG. 9The first order diffracted light beam K vector, namely the diffracted light beam, respectively turns 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 is coupled out to enter human eyes;
s6: the light beam propagating in the 7 o 'clock direction and the light beam propagating in the 11 o' clock direction in the step S4, the light beam propagating in the 7 o 'clock direction and the light beam propagating in the 11 o' clock direction in the step S5 continue to propagate to the two-dimensional grating B on the second surface of the substrate, and newly added diffraction K vectors are K vector components of the (-1,0) order diffraction light beam, K vector components of the (0, -1) order diffraction light beam and the grating vector K of the two-dimensional grating B in the figure 6 WB_2 、K WB_1 The (1,1) order diffracted beam K vector in fig. 9, the diffracted beam is turned to the 3 o' clock direction for propagation; the (-1, -1) order transmission light beam in the step S4 and the step S5 is transmitted to the two-dimensional grating B, and the newly added diffraction K vector is the K vector component of the (-1, -1) order diffraction light beam and the grating vector K of the two-dimensional grating B in the figure 6 WB_1 、K WB_2 The (0,1) order diffracted beam K vector and the (1,0) order diffracted beam K vector in the graph of FIG. 9, and the diffracted beams are respectively turned to the 5 o 'clock direction and the 1 o' clock direction to be transmitted;
s7: and continuously circulating the steps S4-S6 to realize the multidirectional expansion including the backward propagation of the coupled light beam in the grating waveguide.
The grating waveguide structure shown in fig. 7:
p1: preparing an incident projection beam of the grating waveguide, the incident K vector of which is the same as the (0,0) order diffracted beam K vector in fig. 10 (here, only the grating in-plane component of the wave vector is considered);
p2: a part of the incident projection beam is coupled into the one-dimensional grating a on the first surface of the substrate, and at this time, 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 The diffraction beam K vector which can be propagated in the waveguide by total reflection, namely the (1,0) order diffraction beam K vector in the graph 10 is obtained, and the propagation direction of the diffraction beam is the 3 o' clock direction;
p3: of the incident projection beamThe other part of the diffracted beam K is transmitted through the one-dimensional grating A and coupled into the one-dimensional grating B on the second surface of the substrate in FIG. 7, and the diffracted beam K 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 The diffraction beam K vectors which can be propagated in the waveguide by total reflection, namely (0,1) order diffraction beam K vector and (0, -1) order diffraction beam K vector in figure 10 are obtained, and the propagation directions of the diffraction beams are respectively 12 o 'clock direction and 6 o' clock direction;
p4: the 12 o 'clock direction propagating beam and the 6 o' clock direction propagating beam in the step P3 are totally reflected and propagated to the one-dimensional grating C and the one-dimensional grating D on the first surface of the substrate in fig. 7, and the newly added diffraction beam K vectors are respectively the (0,1) order diffraction beam K vector component and the grating vector K of the one-dimensional grating C in fig. 8 WC And (0, -1) the vector component of the order diffracted beam K and the grating vector K of the one-dimensional grating D in FIG. 8 WD The (1,0) order diffracted beam K vector in fig. 10, the diffracted beam propagation direction is 3 o' clock;
p5: the 3 o' clock direction propagating beams in the steps P2 and P4 are propagated to the two-dimensional grating E on the first surface of the substrate in fig. 7, and the newly added diffraction beam K vector is the (1,0) order diffraction 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 and the (0, -1) order diffracted beam K vector in fig. 10, so that, on the one hand, the diffracted beam continues to propagate along the original propagation direction (3 o ' clock direction), and, on the other hand, the diffracted beam respectively turns to the 12 o ' clock direction to propagate and the 6 o ' clock direction to propagate;
p6: the 12 o ' clock direction propagation light beam, the 3 o ' clock direction propagation light beam and the 6 o ' clock direction propagation light beam in the step P5 are propagated to the two-dimensional grating F on the second surface of the substrate in fig. 7, and the newly added diffraction light beam K vector is the K vector component of the (0,1) order diffraction light beam in fig. 10, (1,0) order diffraction light beam K vector component, (0, -1) order diffraction light beam K vector component and the grating vector K of the two-dimensional grating F in fig. 8 WF_2 、K WF_1 By superposition of, i.e.The diffraction beam is coupled out in the transmission direction and enters human eyes;
p7: after the 12 o 'clock direction propagation beam and the 6 o' clock direction propagation beam in the 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 The K vector of the (-1,0) order diffracted beam in fig. 10, i.e., the diffracted beam is turned to the 9 o' clock direction and is reversely propagated;
p8: after the 12 o 'clock direction propagation light beam, the 3 o' clock direction propagation light beam, the 6 o 'clock direction propagation light beam and the 9 o' clock direction propagation light beam in the step P7 are continuously propagated to the two-dimensional grating F, the newly added diffraction light beam K vector is the (0,1) order diffraction light beam K vector component, the (1,0) order diffraction light beam K vector component, the (0, -1) order diffraction light beam K vector component, the (-1,0) order diffraction light beam K vector component and the grating vector K of the two-dimensional grating F in fig. 8 WF_2 、K WF_1 The diffraction beam is coupled out in the transmission direction and enters human eyes;
p9: after the 12 o 'clock direction propagation light beam, the 3 o' clock direction propagation light beam, the 6 o 'clock direction propagation light beam and the 9 o' clock direction propagation light beam in the step P8 are propagated to the two-dimensional grating E, the newly added diffraction light beam K vector is the (0,1) order diffraction light beam K vector component, the (1,0) order diffraction light beam K vector component, the (0, -1) order diffraction light beam K vector component, the (-1,0) order diffraction light beam K vector component and the grating vector K of the two-dimensional grating E in fig. 8 WE_1 、K WE_2 The (0,1) order diffracted beam K vector, the (1,0) order diffracted beam K vector, the (0, -1) order diffracted beam K vector, and the (-1,0) order diffracted beam K vector, i.e., diffracted beams further travel in 12 o 'clock, 3 o' clock, 6 o 'clock, and 9 o' clock directions;
p10: and continuously circulating the steps P8-P9 to realize the multidirectional expansion including the backward propagation of the coupled light beam in the grating waveguide.
Moreover, the invention also provides a waveguide system for augmented reality display, which comprises the grating waveguide. Wherein, at least one grating waveguide adopts the grating waveguide device for augmented reality display.
Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can make modifications and equivalents to the embodiments of the present invention without departing from the spirit and scope of the present invention, which is set forth in the claims of the present application.
Claims (15)
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 area is expressed as the superposition of integral multiples of n grating vectors of the same virtual two-dimensional grating;
wherein n is an integer of not less than 2.
2. The grating waveguide apparatus 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 area as the superposition of integral multiples of two grating vectors of the same virtual two-dimensional grating.
4. The grating waveguide apparatus for augmented reality display of claim 3, wherein the angle between two grating vectors of the virtual two-dimensional grating is between 0 degree and 180 degrees or between-180 degrees and 0 degrees.
5. The grating waveguide device for augmented reality display of claim 1 or 2, wherein the grating vectors of the grating region are expressed as a superposition of integer multiples of n grating vectors of one and the same virtual two-dimensional grating by adjusting the periodicity of the grating region;
wherein the periodicity of the grating region comprises the pitch and direction of the grating.
6. The grating waveguide apparatus for augmented reality display of claim 1,
for an incident beam with a specific wavelength, the size of the waveguide in-plane component of the K vector of any non- (0,0) order diffracted beam formed by the grating waveguide device is larger than the wave number of the incident beam with the specific wavelength in the material outside the substrate, and the size of at least one waveguide in-plane component of the K vector of the non- (0,0) order diffracted beam is smaller than the wave number of the incident beam with the specific wavelength in the material inside the substrate.
7. The grating waveguide device for augmented reality display of claim 6, wherein 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 are both adjustable.
8. The grating waveguide apparatus for augmented reality display of claim 1,
for a light beam of a specific wavelength, at least one of the grating regions has more than one in-waveguide-plane component of the K-vector of the diffracted light beam of the non-outcoupling order with a magnitude greater than the wave number of the light beam of the specific wavelength in the material outside the substrate and less than the wave number of the light beam of the specific wavelength in the material inside the substrate.
9. The grating waveguide device for augmented reality display of claim 1, wherein the grating region has one or more of incoupling, pupil expanding and outcoupling functions for light beams.
10. The grating waveguide device for augmented reality display of claim 2, wherein the total grating layout formed by the plurality of grating regions satisfies the functions of in-coupling, pupil expanding and out-coupling of light beams.
11. The grating waveguide device for augmented reality display of claim 2, wherein at least one grating region of the plurality of grating regions diffracts the light beam arriving at the region to propagate in an opposite direction.
12. The grating waveguide apparatus for augmented reality display of claim 2,
the substrate is 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.
13. The grating waveguide apparatus for augmented reality display of claim 12, 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 an in-coupling grating area and is arranged on the first surface and/or the second surface of the substrate;
the first two-dimensional grating region is arranged on the first surface of the substrate as a pupil expanding-coupling grating region;
the second two-dimensional grating region is arranged on the second surface of the substrate as a pupil expanding-coupling grating region.
14. The grating waveguide apparatus for augmented reality display of claim 13,
the second two-dimensional grating region diffracts the light beam arriving at the region to propagate in the opposite direction.
15. A waveguide system for augmented reality display, characterized by,
comprises a grating waveguide;
wherein at least one of the grating waveguides employs the grating waveguide apparatus for augmented reality display of any one of claims 1-14.
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