CN112630969B - A grating waveguide display device - Google Patents
A grating waveguide display device Download PDFInfo
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- CN112630969B CN112630969B CN202011547773.3A CN202011547773A CN112630969B CN 112630969 B CN112630969 B CN 112630969B CN 202011547773 A CN202011547773 A CN 202011547773A CN 112630969 B CN112630969 B CN 112630969B
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- G—PHYSICS
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- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- 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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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/0081—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 with means for altering, e.g. enlarging, the entrance or exit pupil
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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
- G02B5/1814—Diffraction gratings structurally combined with one or more further optical elements, e.g. lenses, mirrors, prisms or other diffraction gratings
- G02B5/1819—Plural gratings positioned on the same surface, e.g. array of gratings
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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
- G02B5/1842—Gratings for image generation
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- G—PHYSICS
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- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
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Abstract
本发明公开了一种光栅波导显示装置，其包括波导基底，光栅工作机构，第一光栅耦入区及第二光栅耦入区。其中波导基底为对可见光透明的光学平板结构，其中设置在光学波导基底某一侧的第一光栅耦入区域将经过光学系统分光后的两束光线耦合入波导基底，其中设置在光学波导基底同一侧的光栅工作机构用于将光线扩展并耦出波导基底，设置在波导基底的另一侧的耦入光栅通过复耦入的方式提高光线耦入效率。本发明通过对称式耦入方案，简化了光学波导的设计结构，增强耦入光线强度及提升系统显示均匀性，提升人眼感知效果。
The invention discloses a grating waveguide display device, which comprises a waveguide substrate, a grating working mechanism, a first grating coupling-in region and a second grating coupling-in region. The waveguide substrate is an optical flat plate structure that is transparent to visible light, wherein the first grating coupling region disposed on one side of the optical waveguide substrate couples the two beams of light split by the optical system into the waveguide substrate, and the first grating coupling region disposed on the optical waveguide substrate is the same as the optical waveguide substrate. The grating working mechanism on the side is used to expand and couple light out of the waveguide substrate, and the coupling-in grating arranged on the other side of the waveguide substrate improves the light coupling efficiency by means of complex coupling. Through the symmetrical coupling scheme, the present invention simplifies the design structure of the optical waveguide, enhances the intensity of coupled light, improves the display uniformity of the system, and improves the perception effect of the human eye.
Description
Technical Field
The invention relates to the field of augmented reality display devices (AR), in particular to a grating waveguide display device.
Background
Augmented Reality (AR) technology simulates virtual graphics through computer graphics, and superimposes virtual information into a real physical environment, so that the Augmented Reality (AR) technology provides a sense experience beyond reality for a user, and provides more information on the premise of not influencing the acquisition of environmental information. Nowadays, the method has great application value in the fields of education, military, entertainment and industrial production.
According to the traditional optical transmission type augmented reality display scheme, light rays are redirected through a waveguide in the modes of a free-form surface prism, a semi-reflecting and semi-transparent mirror array, holography, a diffraction grating and the like, and imaging light of an image is guided to the direction of human eyes, so that the purposes of reducing the structure of a square optical machine and reducing visual shielding are achieved.
The existing two-dimensional pupil expanding diffraction light waveguide technology mostly adopts a combined design of an in-coupling grating, a folding grating and an out-coupling grating, images are not displayed in the areas of the in-coupling grating and the folding grating, and the size of an available display area is limited. Some designs have therefore proposed the use of an entrance pupil, expanded pupil, out-coupling integrated two-dimensional grating-based planar optical waveguide. However, the optical waveguide does not serve as display due to the action of the optical machine on the coupling-in surface, a part of light is emitted along other directions when the two-dimensional grating is coupled, a large amount of light effect is wasted, and meanwhile, the uniformity of the two-dimensional grating is influenced by grating modulation, so that the design difficulty is high.
Disclosure of Invention
In order to solve the problems, the invention provides a grating waveguide display device, which is based on a two-dimensional pupil expanding mode of a surface relief grating, realizes the symmetric coupling of light rays through two input diffraction optical elements of a first grating coupling-in area which are symmetrically arranged and have symmetric grating shape angles, and two input diffraction optical elements of a second grating coupling-in area which are positioned on the other side are used for improving the light efficiency of the coupled light rays. The coupling-in area adopts a one-dimensional grating design, the scheme is mature, the structure is simple, the diffraction efficiency is high, and the mass production is facilitated.
In order to achieve the above and other objects, the present invention provides a grating waveguide display device, which includes an optical-mechanical system, a light splitting system, a waveguide substrate, a grating operating mechanism, a first grating coupling-in area and a second grating coupling-in area; the first grating coupling-in area and the second grating coupling-in area are respectively provided with a left input diffraction optical element and a right input diffraction optical element which are both one-dimensional linear diffraction optical elements; the grating working mechanism is a two-dimensional diffraction optical element with an included angle of 60 degrees between a first periodic line and a second periodic line.
The light beam output by the optical-mechanical system is divided into a first beam and a second beam through a light splitting system, the first beam and the second beam enter a waveguide substrate through a left input diffraction optical element and a right input diffraction optical element of a first grating coupling-in area respectively, and are totally reflected in the waveguide substrate to form a first propagation array; the remaining 0-order light entering the left input diffractive optical element beam of the first grating coupling-in area is diffracted to enter the waveguide substrate through the left input diffractive optical element of the second grating coupling-in area, the remaining 0-order light entering the right input diffractive optical element beam of the first grating coupling-in area is diffracted to enter the waveguide substrate through the right input diffractive optical element of the second grating coupling-in area, the two remaining 0-order lights are totally reflected in the waveguide substrate to form a second propagation array, and the first propagation array and the second propagation array have the same angle; the first transmission array and the second transmission array are subjected to two-dimensional transmission, pupil expansion and exit pupil by the grating working mechanism to form two groups of virtual images, and the two groups of virtual images are overlapped to form a visual image.
Further, the waveguide substrate is a flat plate structure made of an optical material transparent to visible light, and the upper and lower surfaces thereof are parallel. The grating light source is used for transmitting the light coupled into the waveguide substrate to all places of the grating working mechanism in a transmission mode of total reflection.
Furthermore, the beam splitting system is composed of a cemented prism and a beam splitting film, and plays a role in splitting an incident beam into two parallel beams with equal intensity.
Furthermore, the first grating coupling-in area and the second grating coupling-in area are surface relief gratings and comprise micro-nano structure gratings or volume holographic diffraction gratings.
Further, the first grating coupling-in region includes:
the input diffraction optical element on the left side of the first grating coupling-in area is a one-dimensional linear grating, is arranged on one surface of the waveguide substrate on the same side of the grating working mechanism, is used for transmitting and diffracting a first beam of light to enable the first beam of light to propagate along the first period line direction of the two-dimensional grating working mechanism, and meets the condition that the diffraction angle is larger than the critical angle of total reflection.
The right input diffraction optical element of the first grating coupling-in area is a one-dimensional linear grating, is arranged on the same surface as the left input diffraction optical element of the first grating coupling-in area and is symmetrically arranged with the left input diffraction optical element of the first grating coupling-in area along the central line of the waveguide substrate, the grating line direction is symmetrical to the left input diffraction optical element of the first grating coupling-in area, the period is equal, and the grating surface type is the same. The second light is transmitted and diffracted to be transmitted along the direction of the second periodic line of the two-dimensional grating working mechanism, and the diffraction angle is larger than the critical angle of total reflection.
Further, the second grating coupling-in region includes:
and the left input diffraction optical element of the second grating coupling-in area is a one-dimensional linear grating, is arranged on the surface of the waveguide substrate different from the surface of the waveguide substrate of the first grating coupling-in area, and diffracts the residual 0-order light of the left input diffraction optical element of the first grating coupling-in area into the grating waveguide at the same angle.
The right input diffraction optical element of the second grating coupling-in area is a one-dimensional linear grating, is arranged on the same surface as the left input diffraction optical element of the second grating coupling-in area and is symmetrically arranged with the left input diffraction optical element of the second grating coupling-in area along the central line of the waveguide substrate, the grating line direction is symmetrical to the left input diffraction optical element of the second grating coupling-in area, the period is equal, and the grating surface type is the same. The remaining 0 th order light entering the diffractive optical element to the right of the first grating incoupling region is diffracted into the grating waveguide at the same angle.
Furthermore, the grating working mechanism is provided with one or two sheets, the two sheets are placed on the surface of the waveguide substrate, and the grating working mechanism has the function of expanding the pupil of the first propagation array and the second propagation array in the waveguide to the whole grating working mechanism area in a symmetrical mode and synchronously realizing the exit pupil. To complete the superimposition of the images.
Furthermore, symmetrical light ray input is realized in the deflection direction of the one-dimensional diffraction grating, and the image is uniformly imaged in human eyes through the expanding pupil and the exit pupil of the two-dimensional diffraction grating.
Further, the optical-mechanical system provides a collimated image source in a projection mode.
The grating waveguide element provided by the invention has the beneficial effects that: compared with the prior art, the invention transmits and reflects the incident light twice at the optical machine, so that the light energy utilization efficiency is higher; the advantages of one-dimensional and two-dimensional gratings are combined in a left-right light splitting mode, so that the eye movement range is larger after transmission, meanwhile, the uniformity of an optical image is enhanced in a symmetrical superposition mode, and the use experience of a user is improved.
Drawings
FIG. 1 shows a schematic diagram of a prior art two-dimensional grating waveguide;
figure 2 shows a schematic perspective view of a two-dimensional pupil-expanding waveguide element according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram illustrating an optical mechanical spectrometer provided in embodiment 1 of the present invention;
fig. 4 is a schematic structural diagram illustrating an optical mechanical spectrometer provided in embodiment 2 of the present invention;
fig. 5 is a schematic structural diagram illustrating an optical mechanical spectrometer provided in embodiment 3 of the present invention;
figure 6 shows a schematic cross-sectional view of a two-dimensional expanding pupil waveguide device according to an embodiment of the present invention;
figure 7 shows a schematic top view of a two-dimensional expanding pupil waveguide arrangement according to an embodiment of the present invention;
fig. 8 is a diagram illustrating a grating region division of a grating waveguide component according to an embodiment of the present invention.
Detailed Description
In order to make the achievement of the objects and the technical means of the invention easier to understand, the invention is further explained below with reference to the accompanying drawings and the specific implementation examples.
The invention provides a grating waveguide display device, which comprises an optical-mechanical system, a light splitting system, a waveguide substrate, a grating working mechanism, a first grating coupling-in area and a second grating coupling-in area, wherein the optical-mechanical system is arranged on the waveguide substrate; the first grating coupling-in area and the second grating coupling-in area are respectively provided with a left input diffraction optical element and a right input diffraction optical element which are both one-dimensional linear diffraction optical elements; the grating working mechanism is a two-dimensional diffraction optical element with an included angle of 60 degrees between a first periodic line and a second periodic line. The waveguide substrate is a flat plate structure made of optical materials transparent to visible light, and the upper surface and the lower surface of the waveguide substrate are parallel. The grating light source is used for transmitting the light coupled into the waveguide substrate to all places of the grating working mechanism in a transmission mode of total reflection. The light splitting system consists of a glued prism and a light splitting film and has the function of splitting an incident light beam into two parallel light beams with equal intensity. The first grating coupling-in area and the second grating coupling-in area are surface relief gratings and comprise micro-nano structure gratings or volume holographic diffraction gratings. The grating working mechanism is provided with one or two pieces, is placed on the surface of the waveguide substrate and is a visual area of the waveguide, and has the functions of expanding a pupil of a first propagation array and a second propagation array in the waveguide to the whole grating working mechanism area in a symmetrical mode, synchronously realizing an exit pupil, respectively propagating along the periodic direction of a grating line after receiving the left light beam array and the right light beam array, coupling and emitting a part of light rays to enter human eyes, and continuously transmitting the other part of light rays along the original direction. The emergent light of the left and right light beam arrays are mutually overlapped, so that the light intensity uniformity of the receiving area of the human eyes is enhanced. To complete the superimposition of the images. The optical-mechanical system provides an image source after collimation in a projection mode.
The light beam output by the optical-mechanical system is divided into a first beam and a second beam through a light splitting system, the first beam and the second beam enter a waveguide substrate through a left input diffraction optical element and a right input diffraction optical element of a first grating coupling-in area respectively, and are totally reflected in the waveguide substrate to form a first propagation array; the remaining 0-order light entering the left input diffractive optical element beam of the first grating coupling-in area is diffracted to enter the waveguide substrate through the left input diffractive optical element of the second grating coupling-in area, the remaining 0-order light entering the right input diffractive optical element beam of the first grating coupling-in area is diffracted to enter the waveguide substrate through the right input diffractive optical element of the second grating coupling-in area, the two remaining 0-order lights are totally reflected in the waveguide substrate to form a second propagation array, and the first propagation array and the second propagation array have the same angle; the first transmission array and the second transmission array are subjected to two-dimensional transmission, pupil expansion and exit pupil by the grating working mechanism to form two groups of virtual images, and the two groups of virtual images are overlapped to form a visual image.
The first grating coupling-in region includes:
the left side of the first grating coupling-in area is input into a diffraction optical element, which is marked as a first grating coupling-in area (left), is a one-dimensional linear grating, is arranged on one surface of the waveguide substrate on the same side of the grating working mechanism, and is used for transmitting and diffracting a first beam of light to enable the first beam of light to propagate along the first period line direction of the two-dimensional grating working mechanism and meet the condition that the diffraction angle is larger than the critical angle of total reflection.
The right input diffraction optical element of the first grating coupling-in area is marked as a first grating coupling-in area (right) and is a one-dimensional linear grating, is arranged on the same surface as the left input diffraction optical element of the first grating coupling-in area and is symmetrically arranged along the central line of the waveguide substrate with the left input diffraction optical element of the first grating coupling-in area, the grating line direction is symmetrical to the left input diffraction optical element of the first grating coupling-in area, the period is equal, and the grating surface type is the same. The second light is transmitted and diffracted to be transmitted along the direction of the second periodic line of the two-dimensional grating working mechanism, and the diffraction angle is larger than the critical angle of total reflection.
The second grating coupling-in region includes:
and the left input diffraction optical element of the second grating coupling-in area is marked as a second grating coupling-in area (left) and is a one-dimensional linear grating, is arranged on one surface of the waveguide substrate, which is different from the first grating coupling-in area, and diffracts the residual 0-order light input into the diffraction optical element on the left side of the first grating coupling-in area into the grating waveguide at the same angle.
The right input diffraction optical element of the second grating coupling-in area is marked as a second grating coupling-in area (right) and is a one-dimensional linear grating, is arranged on the same surface as the left input diffraction optical element of the second grating coupling-in area, and is symmetrically arranged along the central line of the waveguide substrate with the left input diffraction optical element of the second grating coupling-in area, the grating line direction is symmetrical to the left input diffraction optical element of the second grating coupling-in area, the period is equal, and the grating surface type is the same. The remaining 0 th order light entering the diffractive optical element to the right of the first grating incoupling region is diffracted into the grating waveguide at the same angle.
The included angle theta between the light coupled into the waveguide substrate and the waveguide substrate satisfies the following condition:
θ>arcsin(n0/n1)
where n1 is the refractive index of the waveguide substrate and n0 is the refractive index of air.
The invention modulates the diffraction efficiency of the surface relief grating, and because the light ray is gradually weakened along with the transmission intensity, the diffraction efficiency of the surface relief grating is gradually enhanced along the light ray transmission direction, thereby ensuring that the light intensity is uniform within the eye movement range of a user. The one-dimensional diffraction grating realizes symmetrical light input in the deflection direction, and images are uniformly formed in human eyes through the expanding pupil and the exit pupil of the two-dimensional diffraction grating.
Fig. 1 is a schematic diagram of a principle of a conventional two-dimensional grating waveguide, and a transmission waveguide 101 and a two-dimensional grating operating mechanism 102 are used, wherein incident light is directly incident into the two-dimensional grating 102 along a direction K1, part of 0-level light is continuously emitted along a direction K1, and part of the 0-level light is diffracted along a direction opposite to that of K2 and K3, and does not participate in subsequent pupil expansion. The rest part is divided into two directions of K2 and K3 at the grating 102, and the included angle between K2 and K3 can be 60 degrees or 90 degrees or slightly smaller than 90 degrees. The light continues to be split when it again encounters other portions of the grating active structure 102, some of which are coupled out in the direction K4 and some of which continue to be diffracted in the directions K2 and K3.
Refer to fig. 2. The grating coupler comprises a waveguide substrate 201, a first grating coupling-in area (left) 202a, a first grating coupling-in area (right) 202b, a second grating coupling-in area (left) 203a, a second grating coupling-in area (right) 203b and a grating working mechanism 204. The grating working mechanism 204 is a two-dimensional grating, is located on one side of the waveguide substrate 201, and is a first grating coupling-in area (left) 202a, and the first grating coupling-in area (right) 202b are all one-dimensional gratings, and have mirror symmetry structures, and are located on the same side of the waveguide substrate 201, and the second grating coupling-in area (left) 203a, and the second grating coupling-in area (right) 203b are all one-dimensional gratings, have mirror symmetry structures, and are located on the other side of the waveguide substrate 201 opposite to the first grating coupling-in area. The first grating coupling-in region and the second grating coupling-in region integrally form an optical waveguide sheet for coupling in light, expanding light and coupling out light.
Example 1
Refer to fig. 3. The optical machine 301 projects the image source through the collimating optical path and emits the image source in the form of parallel light. The light is split by an optical prism splitting system 401, wherein the optical prism is made of K9 glass, or other transparent optical materials with critical angle larger than 45 degrees are used as a substrate. After exiting the optical engine, the light beam is split into two beams of light beams with equal intensity, i.e. left and down beams, by the beam splitter 311, wherein the left light beam continues to pass through the first reflecting surface 312 forming an angle of 45 ° with the exit surface, and then turns 90 ° to reach the first grating coupling-in area (left) 202a through the exit surface. Meanwhile, the downward light is reflected twice by the second reflecting surface 313 and the third reflecting surface 314 and then enters the first grating coupling-in area (right) 202b in the same direction as the first light. And then further passes through an entrance pupil, an expansion pupil and an exit pupil of the optical waveguide element.
Referring to fig. 6, after passing through the beam splitting system 401, the collimated incident light 411 emitted by the optical engine 301 is split into two first light beams 412a and second light beams 412b with the same intensity and direction on the left and right, the two light beams are respectively incident on the first grating coupling-in areas 202a and 202b, a plurality of beam angles are generated to satisfy the total reflection condition, meanwhile, special angle light beams 413a and 413b satisfying the transmission and diffraction conditions in the grating working mechanism 204 are satisfied, part of the 0-level light is continuously emitted along the directions 412a and 412b, meets the second grating coupling-in areas 203a and 203b, and is diffracted thereon to form another set of light beam arrays with the same direction and angle parallel to the diffracted light beams 413a and 413 b. Since the two sets of light rays have the same spatial direction, the diffraction characteristics generated on the grating work mechanism 204 should be the same, and no additional coupling-out device needs to be designed. The emergent ray 414 passes through the expanding pupil and the exit pupil and is received by the human eye 421.
Referring to fig. 7, two groups of light rays 413a and 413b enter the waveguide respectively along the first period line and the second period line of the two-dimensional grating at an included angle of 60 °, where 413a is taken as an example, 413a may be diffracted when encountering the grating unit a to generate transmission light rays in three directions b, c, and d toward the inside of the waveguide, and the diffraction angle of the transmission light rays should be greater than the critical angle at which total reflection can be generated in the waveguide, so that the light rays have no loss of light intensity when being transmitted inside the waveguide; simultaneously emitting an outgoing ray 414. The transmitted light is, for example, in the direction c, when encountering the grating unit structure c, the light will be diffracted again, so as to generate transmitted light in the directions e, f, and g, which also satisfies the total reflection condition, and will continue to propagate in the grating, and at the same time, will generate an outgoing light 414 coupled out of the grating, so that the human eye 421 can observe the image. Since e, f, g still repeat the above in-waveguide transmission and coupling-out processes, finally, the human eye 231 can observe the image emitted by the optical engine completely and continuously in the range of the two-dimensional grating working mechanism 204. 413b enters at a symmetrical angle, so that the diffraction efficiency is expanded in the same diffraction mode in the grating working mechanism 204, the problem of unbalanced diffraction efficiency expanded by 413a is solved, and the aim of balancing the efficiency of the exit pupil position is fulfilled.
Example 2
Refer to fig. 4. The optical machine 301 projects the image source through the collimating optical path and emits the image source in the form of parallel light. The light passes through the optical prism beam splitting system 401, wherein the optical prism is made of K9 glass, or other transparent optical materials with critical angle less than 45 ° can be used as a substrate. After exiting the light machine, the light is split into two beams of light with equal intensity in the right direction and the downward direction by the beam splitting prism 321, and the light machine can also enter in the left direction of the prism according to the characteristics of the beam splitting film, so that the same effect can be achieved. Wherein the right light continues to turn 90 ° through the reflection surface 322 forming an angle of 45 ° with the exit surface, and reaches the second grating coupling-in region (right) 202b through the exit surface. While the downward light is directly irradiated on the first grating coupling-in area (left) 202 a. And then further passes through an entrance pupil, an expansion pupil and an exit pupil of the optical waveguide element.
The remaining components and principles of this embodiment are the same as those of embodiment 1, and are not described again.
Example 3
Refer to fig. 5. The optical machine 301 projects the image source through the collimating optical path and emits the image source in the form of parallel light. The light passes through the optical prism beam splitting system 401, wherein the optical prism is made of K9 glass, or other transparent optical materials with critical angle larger than 45 ° can be used as a substrate. After exiting the light machine, the light beam is split into two beams of light beams with equal intensity in the left direction and the right direction by the beam splitter 331, wherein the light beam in the left direction continues to turn 135 degrees by passing through the reflecting surface 312 forming an included angle of 67.5 degrees with the exit surface, and reaches the first grating coupling-in area (left) 202a through the exit surface. Meanwhile, the right light is turned 135 ° by the reflecting surface 333 forming an angle of 67.5 ° with the exit surface, and then enters the first grating coupling-in region (right) 202b in the same direction as the first light. And then further passes through an entrance pupil, an expansion pupil and an exit pupil of the optical waveguide element.
The remaining components and principles of this embodiment are the same as those of embodiment 1, and are not described again.
Example 4
Referring to fig. 8, the two-dimensional grating operating mechanism 204 preferably adjusts diffraction efficiency in different regions by presetting height, duty ratio, curvature radius, etc., so that the brightness of the coupled image is uniform. The working area of the grating working mechanism 204 is divided into 4 areas of 2041-2044, and the grating unit structures of the four areas are the same, so as to ensure that the diffracted beams 212 in the same direction have the same diffraction angle and direction change. However, by modulating their height, duty cycle, and radius of curvature, the grating work mechanism 204 can be made to have different diffraction efficiencies at the output in different regions when coupled out. The output diffraction efficiency is higher as the output point is farther away from the input point, and the luminous flux of the unit area in the effective output area is finally ensured to be equal or approximate, so that a user has more uniform image brightness experience. That is, the diffraction efficiency of 2041-. The out-coupling diffraction efficiency of each region should satisfy the following equation:
wherein etaNIs the outcoupling diffraction efficiency of the Nth region, NTIs the total number of divided regions.
The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (9)
1. A grating waveguide display device is characterized by comprising an optical-mechanical system, a light splitting system, a waveguide substrate, a grating working mechanism, a first grating coupling-in area and a second grating coupling-in area; the first grating coupling-in area and the second grating coupling-in area are respectively provided with a left input diffraction optical element and a right input diffraction optical element, the left input diffraction optical element and the right input diffraction optical element are symmetrically arranged along the central line of the waveguide substrate and are both one-dimensional linear diffraction optical elements; the grating working mechanism is a two-dimensional diffraction optical element with an included angle of 60 degrees between a first periodic line and a second periodic line;
the light beam output by the optical-mechanical system is divided into a first light beam and a second light beam which are parallel and have equal intensity through a light splitting system, the first light beam and the second light beam enter a waveguide substrate through a left input diffraction optical element and a right input diffraction optical element of a first grating coupling-in area respectively, and the first light beam and the second light beam are totally reflected in the waveguide substrate to form a first propagation array; the remaining 0-order light entering the left input diffractive optical element beam of the first grating coupling-in area is diffracted to enter the waveguide substrate through the left input diffractive optical element of the second grating coupling-in area, the remaining 0-order light entering the right input diffractive optical element beam of the first grating coupling-in area is diffracted to enter the waveguide substrate through the right input diffractive optical element of the second grating coupling-in area, the two remaining 0-order lights are totally reflected in the waveguide substrate to form a second propagation array, and the first propagation array and the second propagation array have the same angle; the first transmission array and the second transmission array are subjected to two-dimensional transmission, pupil expansion and exit pupil by the grating working mechanism to form two groups of virtual images, and the two groups of virtual images are overlapped to form a visual image.
2. A grating waveguide display device according to claim 1, wherein the waveguide substrate is a flat structure of optical material transparent to visible light, with parallel upper and lower surfaces; the grating light source is used for transmitting the light coupled into the waveguide substrate to all places of the grating working mechanism in a transmission mode of total reflection.
3. A grating waveguide display device according to claim 1 wherein the beam splitting system is comprised of cemented prism and splitting film that act to split the incident beam into two parallel beams of equal intensity.
4. A grating waveguide display device according to claim 1, wherein the first and second grating coupling-in regions are surface relief gratings, including micro-nano structured gratings or volume holographic diffraction gratings.
5. A grating waveguide display device according to claim 1, wherein the first grating coupling-in region comprises:
the left input diffraction optical element of the first grating coupling-in area is a one-dimensional linear grating, is arranged on one surface of the waveguide substrate on the same side of the grating working mechanism, is used for transmitting and diffracting a first beam of light to enable the first beam of light to propagate along the first period line direction of the two-dimensional grating working mechanism, and meets the condition that the diffraction angle is larger than the critical angle of total reflection;
the right input diffraction optical element of the first grating coupling-in area is a one-dimensional linear grating and is arranged on the same surface as the left input diffraction optical element of the first grating coupling-in area, the grating line direction is symmetrical to the left input diffraction optical element of the first grating coupling-in area, the periods are equal, and the grating surface types are the same; and the second light is used for transmitting and diffracting the second light beam to enable the second light beam to propagate along the direction of a second period line of the two-dimensional grating working mechanism, and the diffraction angle is larger than the critical angle of total reflection.
6. A grating waveguide display device according to claim 1, wherein the second grating coupling-in region comprises:
the left input diffraction optical element of the second grating coupling-in area is a one-dimensional linear grating, is arranged on the surface of the waveguide substrate different from the first grating coupling-in area, and diffracts the residual 0-order light of the left input diffraction optical element of the first grating coupling-in area into the grating waveguide at the same angle;
the right input diffraction optical element of the second grating coupling-in area is a one-dimensional linear grating and is arranged on the same surface as the left input diffraction optical element of the second grating coupling-in area, the grating line direction is symmetrical to the left input diffraction optical element of the second grating coupling-in area, the period is equal, and the grating surface type is the same; the remaining 0 th order light entering the diffractive optical element to the right of the first grating incoupling region is diffracted into the grating waveguide at the same angle.
7. A grating waveguide display device according to claim 2, wherein the grating working mechanism has one or two pieces, which are placed on the surface of the waveguide substrate, and are used to expand the pupil of the first and second propagation arrays in the waveguide to the whole grating working mechanism area in a symmetrical manner, and to realize the exit pupil synchronously; to complete the superimposition of the images.
8. A grating waveguide display device according to any one of claims 1 to 7 wherein the one-dimensional diffraction grating has a direction of refraction that provides symmetrical light input, and the two-dimensional diffraction grating has an exit pupil and an extended pupil, through which an image is uniformly imaged in the human eye.
9. A grating waveguide display device according to any one of claims 1 to 7, wherein the opto-mechanical system provides a collimated image source by means of projection.
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