CN111221064A - Grating structure and near-to-eye display system - Google Patents
Grating structure and near-to-eye display system Download PDFInfo
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- CN111221064A CN111221064A CN202010297633.9A CN202010297633A CN111221064A CN 111221064 A CN111221064 A CN 111221064A CN 202010297633 A CN202010297633 A CN 202010297633A CN 111221064 A CN111221064 A CN 111221064A
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/18—Diffraction gratings
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- G—PHYSICS
- G02—OPTICS
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- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/01—Head-up displays
- G02B27/0101—Head-up displays characterised by optical features
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Abstract
The embodiment of the invention relates to the technical field of optics, and discloses a grating structure which is applied to a near-to-eye display system and comprises: the grating structure provided by the embodiment of the invention is easy to process, high in degree of freedom, good in uniformity and capable of realizing more variable diffraction order distribution.
Description
Technical Field
The embodiment of the invention relates to the technical field of optics, in particular to a grating structure and a near-to-eye display system.
Background
The augmented reality is a technology of fusing virtual information and a real world, wherein the design of a near-to-eye display system is a key link in the augmented reality technology, and for small-volume augmented reality glasses with better portability, the main scheme in the market is to adopt an optical waveguide as a transmission medium of light, and the optical waveguide is divided into a geometric array waveguide, a diffraction grating waveguide and a volume holographic waveguide, wherein the diffraction grating waveguide is more and more emphasized due to the convenience of nanoimprint processing, and the diffraction grating acts as a thin film in the array waveguide, so that the transmission direction of the light is mainly changed.
In implementing the embodiments of the present invention, the inventors found that at least the following problems exist in the above related art: at present, in an optical waveguide scheme adopting a two-dimensional diffraction grating, a cylindrical structure or a rhombic structure which is arranged in a hexagon is generally adopted, the structure is very simple, the design freedom is low, the realized efficiency modulation is also very simple, and the uniformity and the efficiency of the whole diffraction waveguide are poor.
Disclosure of Invention
In view of the foregoing defects in the prior art, an object of the embodiments of the present invention is to provide a grating structure and a near-eye display system with good uniformity and easy processing.
The purpose of the embodiment of the invention is realized by the following technical scheme:
to solve the above technical problem, in a first aspect, an embodiment of the present invention provides a grating structure, including: a substrate, and a two-dimensional grating having at least one grating period, the two-dimensional grating being disposed on a surface of the substrate,
the two-dimensional grating is of a pixelized structure, in each grating period, the two-dimensional grating comprises at least one row of two-dimensional rectangular gratings in the horizontal direction and at least one column of two-dimensional rectangular gratings in the vertical direction, and the sum of the row number and the column number of the two-dimensional grating is at least three.
In some embodiments, every two adjacent two-dimensional rectangular gratings are arranged in a fitting manner.
In some embodiments, the period size of the two-dimensional rectangular grating in the horizontal direction is 200-.
In some embodiments, the two-dimensional rectangular grating has a dimension of 10-200 nm.
In some embodiments, the two-dimensional rectangular grating has a height of 0-1000 nm.
In some embodiments, the surface of the two-dimensional grating is provided with a coating.
In order to solve the above technical problem, in a second aspect, an embodiment of the present invention provides a near-eye display system, including: a micro-projector, an optical waveguide, and the grating structure according to the first aspect, wherein the grating structure is disposed in a coupling-in area and/or a coupling-out area of the optical waveguide.
Compared with the prior art, the invention has the beneficial effects that: in contrast to the prior art, in an embodiment of the present invention, a grating structure is provided, which is applied to a near-eye display system, and includes: the grating structure provided by the embodiment of the invention is easy to process, high in degree of freedom, good in uniformity and capable of realizing more variable diffraction order distribution.
Drawings
One or more embodiments are illustrated by the accompanying figures in the drawings that correspond thereto and are not to be construed as limiting the embodiments, wherein elements/modules and steps having the same reference numerals are represented by like elements/modules and steps, unless otherwise specified, and the drawings are not to scale.
FIG. 1(a) is a first K-threshold analysis diagram of a grating structure provided in an embodiment of the present invention;
FIG. 1(b) is a diagram of a second K-threshold analysis of a grating structure provided in one embodiment of the present invention;
FIG. 1(c) is a third K-threshold analysis diagram of a grating structure provided in one embodiment of the present invention;
FIG. 1(d) is a diagram of a fourth K-threshold analysis of a grating structure provided in one embodiment of the present invention;
fig. 2 is a schematic top view of a grating structure according to an embodiment of the present invention;
FIG. 3 is a schematic perspective view of a grating structure provided in accordance with an embodiment of the present invention;
FIG. 4 is a schematic perspective view of another grating structure provided in accordance with an embodiment of the present invention;
fig. 5 is a schematic side view of an optical structure of a near-eye display system according to a second embodiment of the present invention;
fig. 6(a) is a schematic top view of a first grating structure and an optical structure of an optical waveguide in a near-eye display system according to a second embodiment of the present invention;
fig. 6(b) is a schematic top view of a second optical structure of a grating structure and an optical waveguide in a near-eye display system according to a second embodiment of the present invention;
fig. 6(c) is a schematic top view of a third grating structure and an optical structure of an optical waveguide in a near-eye display system according to a second embodiment of the present invention;
fig. 6(d) is a schematic top view of a fourth grating structure and an optical structure of an optical waveguide in a near-eye display system according to a second embodiment of the present invention;
fig. 6(e) is a schematic top view of a fifth grating structure and an optical structure of an optical waveguide in a near-eye display system according to a second embodiment of the present invention.
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications can be made by persons skilled in the art without departing from the spirit of the invention. All falling within the scope of the present invention.
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application. In order to facilitate the connection structure definition, the embodiment of the invention performs the position definition of the component with reference to the light path traveling/exit direction of the optical axis.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
Specifically, the embodiments of the present invention will be further explained below with reference to the drawings.
Example one
An embodiment of the present invention provides a grating structure, including: the grating structure comprises a substrate and a two-dimensional grating with at least one grating period, wherein the two-dimensional grating is arranged on one surface of the substrate and is of a pixelized structure, in each grating period, the two-dimensional grating comprises at least one row of two-dimensional rectangular grating in the horizontal direction and at least one column of two-dimensional rectangular grating in the vertical direction, and the sum of the row number and the column number of the two-dimensional grating is at least three.
In some embodiments, every two adjacent two-dimensional rectangular gratings are arranged in a fitting manner.
In some embodiments, the surface of the two-dimensional grating is provided with a coating. The coating layer is made of a material with a high refractive index, and preferably, in the embodiment of the invention, the refractive index of the coating layer is greater than 1.7.
The grating structure provided by the embodiment of the invention has the characteristics of easiness in processing, high degree of freedom and better uniformity when being applied to the optical waveguide in a near-to-eye display system, and can realize more variable diffraction order distribution.
For understanding the reflection diffraction orders, reference may be made to fig. 1(a), fig. 1(b), fig. 1(c), and fig. 1(d) together, which show the distribution of four diffraction orders of the grating structure shown in the embodiment of the present invention, and in each K-domain analysis diagram shown in fig. 1(a), fig. 1(b), fig. 1(c), and fig. 1(d), the outer circle represents the maximum K value that can be achieved by the optical waveguide material to which the grating structure is currently applied, and the inner circle represents the K value corresponding to the total reflection condition. If the grating structure described in the embodiment of the present invention is used in the coupling-in region of the optical waveguide, the K value of the light beam coupled into the optical waveguide is shifted between the inner and outer rings, so that the light beam can be propagated in the optical waveguide by total reflection. If the grating structure is used in the coupling-out area of the optical waveguide, the light beam propagated by total reflection meets the grating structure, part of the generated diffraction orders are translated to the inner ring, so that the diffraction waveguide is coupled out, and the total reflection propagation is continuously maintained between the inner ring and the outer ring of the generated other diffraction orders.
The diffraction order distribution of the grating structure provided in the embodiment of the present invention is not limited to the distribution of diffraction orders shown in fig. 1(a), 1(b), 1(c), and 1(d), and may be set according to actual conditions, and is not limited to the embodiment of the present invention.
In the grating structure provided by the embodiment of the invention, the limitation of the number of rows and columns of the two-dimensional grating is more than or equal to three, so that a two-dimensional pixilated grating structure formed by the two-dimensional rectangular grating is formed, the grating structure has the advantages of easiness in processing, high degree of freedom, good uniformity and capability of realizing more variable diffraction order distribution, and the grating structure can effectively adjust the efficiency of each diffraction order by optimizing and adjusting the width, height, coating condition and the like of the two-dimensional rectangular grating in each row and each column, thereby optimizing the function of the grating structure applied to the optical waveguide.
Specifically, referring to fig. 2 and 3, which show a schematic top view and a schematic perspective view of a grating structure provided in an embodiment of the present invention, in the grating structure shown in fig. 2 and 3, three rows of two-dimensional rectangular gratings are arranged in a horizontal direction (Y direction) of the two-dimensional grating, and four columns of two-dimensional rectangular gratings are arranged in a vertical direction (X direction), which satisfies a limitation that the sum of the number of rows and the number of columns of the two-dimensional grating is at least three.
In the embodiment of the invention, the transverse-longitudinal ratio of the two-dimensional grating in one grating period is 0.866:1, the period size of the two-dimensional rectangular grating in the horizontal direction is 200-1000nm, the period size of the two-dimensional rectangular grating in the vertical direction is 200-1000nm, the size of the two-dimensional rectangular grating is 10-200nm, and the height of the two-dimensional rectangular grating is 0-1000 nm. And the heights of the two-dimensional rectangular gratings in one grating period are different.
In the actual simulation of the grating structure shown in the embodiment of the present invention, in the reflection order, the 0-order diffraction efficiency is 63.8%, such as reflection1 in fig. 1(a), and the efficiencies of two expansion orders around the zero order are 4.7%, such as reflection2 and reflection3 in fig. 1(a), and the diffraction efficiency of the transmission coupling-out order is 1%.
It should be noted that fig. 2 and fig. 3 and the illustrated embodiments thereof only show one grating period of the grating structure, and in practical applications, the grating period of the grating structure may be set according to practical needs, and is not limited by the embodiments of the present invention. The number of rows and columns of the two-dimensional rectangular grating in the two-dimensional grating also does not need to be limited by the embodiment of the invention, and the number of rows and columns can be set according to actual needs.
Preferably, in the embodiment of the present invention, the wafer may be processed by using a diffraction grating processing apparatus such as an electron beam/ion beam apparatus, an extreme/deep ultraviolet lithography apparatus, or an interference lithography apparatus, and the grating structure according to the embodiment of the present invention may be manufactured by performing imprint replication using a nanoimprint apparatus.
In some embodiments, please refer to fig. 4, which shows a schematic perspective view of another grating structure provided in the embodiments of the present invention, and in the grating structure shown in fig. 4, the same as the grating structure shown in fig. 3 and the embodiments thereof are: the two-dimensional grating is provided with three rows of two-dimensional rectangular gratings in the horizontal direction (Y direction), four rows of two-dimensional rectangular gratings in the vertical direction (X direction), the intervals of the two-dimensional rectangular gratings adjacent to each other are the same, the horizontal-longitudinal proportion of the two-dimensional grating in one grating period is 0.866:1, the period size of the two-dimensional rectangular grating in the horizontal direction is 200-1000nm, the period size of the two-dimensional rectangular grating in the vertical direction is 200-1000nm, the size of the two-dimensional rectangular grating is 10-200nm, and the height of the two-dimensional rectangular grating is 0-1000nm, so that the plan view schematic diagram of the grating structure shown in FIG. 4 is consistent with the plan view schematic diagram shown in FIG. 2.
Unlike the grating structure shown in fig. 3 and its embodiments: the embodiment of the invention optimizes the height of the two-dimensional rectangular grating, and solves the problem that the two-dimensional rectangular grating is difficult to process at different heights. In the actual simulation of the grating structure shown in the embodiment of the present invention, in the reflection order, the 0-order diffraction efficiency is 79.79%, such as reflection1 in fig. 1(a), and the efficiencies of two expansion orders around the zero order are 1.38%, such as reflection2 and reflection3 in fig. 1(a), and the diffraction efficiency of the transmission coupling-out order is 1.21%.
It should be noted that fig. 4 and the illustrated embodiment thereof only show one grating period of the grating structure, and in practical applications, the grating period of the grating structure may be set according to actual needs, and is not limited by the embodiment of the present invention. The number of rows and columns of the two-dimensional rectangular grating in the two-dimensional grating also does not need to be limited by the embodiment of the invention, and the number of rows and columns can be set according to actual needs.
Preferably, in the embodiment of the present invention, the wafer may be processed by using a diffraction grating processing apparatus such as an electron beam/ion beam apparatus, an extreme/deep ultraviolet lithography apparatus, or an interference lithography apparatus, and the grating structure according to the embodiment of the present invention may be manufactured by performing imprint replication using a nanoimprint apparatus.
Example two
An embodiment of the present invention provides a near-eye display system, which is shown in fig. 5 and illustrates an optical structure schematic diagram of the near-eye display system provided in the embodiment of the present invention, where the near-eye display system includes: a micro-projector 1, an optical waveguide 3, and a grating structure as described in the first or second embodiment, wherein the grating structure is disposed in the coupling-in region 2 and/or the coupling-out region 4 of the optical waveguide 3.
It should be noted that the grating structure according to the embodiment of the present invention is the grating structure according to the first embodiment, and has the same structure and characteristics, and specific structures, parameters, effects, and the like of the grating structure according to the embodiment of the present invention can be referred to in the first embodiment, and are not described in detail herein.
In the embodiment of the present invention, the image source in the micro-projection optical machine 1 may be one of LCOS, DMD, OLED and MEMS, the light emitted from the micro-projection optical machine 1 is coupled into the optical waveguide 3 through the grating structure disposed on the coupling-in area 2, the light coupled into the optical waveguide 3 is propagated in the optical waveguide 3 by total reflection, when the light is propagated to the coupling-out area 4, a part of the light is expanded in pupil through the grating structure disposed on the coupling-out area 4 and coupled out of the optical waveguide 3, and then propagated into the human eye 5 for imaging. Further, the grating structure may also be arranged inside the optical waveguide 3 to enable the light to change the propagation direction in the optical waveguide 3.
In some embodiments, the coupling-in region 2 or the coupling-out region 4 may not be provided with the grating structure as described in the first embodiment, and the coupling-in region 2, the coupling-out region 4, or the interior of the optical waveguide 3 may also be provided with a super-surface structure, a resonant grating structure, a volume holographic structure, a two-dimensional grating structure, or a one-dimensional grating structure such as an inclined grating, a trapezoidal grating, a blazed grating, or a rectangular grating, specifically, the grating structures on the coupling-in region 2 and the coupling-out region 4 may be provided according to actual needs, and do not need to be limited by the embodiments of the present invention.
Specifically, reference may be made to the grating structures and the optical structures of the optical waveguide shown in fig. 6(a), 6(b), 6(c), 6(d) and 6(e), which show various arrangement situations and light propagation directions of the coupling-in region 2 and the coupling-out region 4 on the optical waveguide 3, wherein the grating structure described in the above embodiment may be used for both the circular coupling-in region and the square coupling-out region, or the grating structure described in the above embodiment may be used for only the coupling-in region or the coupling-out region, or other grating structures described above may be used for the coupling-in region or the coupling-out region that does not use the grating structure described in the above embodiment.
It should be noted that the optical structures of the grating structure and the optical waveguide in the near-eye display system according to the embodiment of the present invention are not limited to the grating structures shown in fig. 6(a), 6(b), 6(c), 6(d), and 6(e), and may be specifically set according to actual circumstances, and are not limited to the embodiment of the present invention.
The embodiment of the invention provides a near-to-eye display system, which comprises a micro-projection light machine for emitting light rays for imaging and an optical waveguide with the surface provided with the grating structure as in the first embodiment.
The embodiment of the invention provides a grating structure, which is applied to a near-eye display system and comprises: the grating structure provided by the embodiment of the invention is easy to process, high in degree of freedom, good in uniformity and capable of realizing more variable diffraction order distribution.
It should be noted that the above-described device embodiments are merely illustrative, where the units described as separate parts may or may not be physically separate, and the parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; within the idea of the invention, also technical features in the above embodiments or in different embodiments may be combined, steps may be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (7)
1. A grating structure, comprising: a substrate, and a two-dimensional grating having at least one grating period, the two-dimensional grating being disposed on a surface of the substrate,
the two-dimensional grating is of a pixelized structure, in each grating period, the two-dimensional grating comprises at least one row of two-dimensional rectangular gratings in the horizontal direction and at least one column of two-dimensional rectangular gratings in the vertical direction, and the sum of the row number and the column number of the two-dimensional grating is at least three.
2. The grating structure of claim 1,
every two adjacent two-dimensional rectangular gratings are arranged in an attaching mode.
3. The grating structure of claim 2,
the period size of the two-dimensional rectangular grating in the horizontal direction is 200-1000nm, and the period size of the two-dimensional rectangular grating in the vertical direction is 200-1000 nm.
4. Grating structure in accordance with claim 3,
the size of the two-dimensional rectangular grating is 10-200 nm.
5. Grating structure in accordance with claim 4,
the height of the two-dimensional rectangular grating is 0-1000 nm.
6. Grating structure in accordance with claim 5,
and a coating layer is arranged on the surface of the two-dimensional grating.
7. A near-eye display system, comprising: micro-projection optics, an optical waveguide, and a grating structure according to any of the claims 1-6, said grating structure being provided in a coupling-in area and/or a coupling-out area of said optical waveguide.
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| CN202120775689.0U CN214669691U (en) | 2020-04-16 | 2021-04-15 | Grating structure and near-to-eye display system |
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| WO2022160825A1 (en) * | 2021-01-26 | 2022-08-04 | 华为技术有限公司 | Optical diffractive device and terminal device |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2005077966A (en) * | 2003-09-03 | 2005-03-24 | Dainippon Printing Co Ltd | Diffraction optical element |
| CN209525483U (en) * | 2019-04-03 | 2019-10-22 | 深圳市灵明光子科技有限公司 | Optical field imaging device |
| CN110651204A (en) * | 2017-05-08 | 2020-01-03 | 迪斯帕列斯有限公司 | Diffraction grating with variable diffraction efficiency and method for displaying an image |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005077966A (en) * | 2003-09-03 | 2005-03-24 | Dainippon Printing Co Ltd | Diffraction optical element |
| CN110651204A (en) * | 2017-05-08 | 2020-01-03 | 迪斯帕列斯有限公司 | Diffraction grating with variable diffraction efficiency and method for displaying an image |
| CN209525483U (en) * | 2019-04-03 | 2019-10-22 | 深圳市灵明光子科技有限公司 | Optical field imaging device |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2022160825A1 (en) * | 2021-01-26 | 2022-08-04 | 华为技术有限公司 | Optical diffractive device and terminal device |
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