CN117031617A - Curved surface holographic waveguide combiner with two-dimensional pupil expansion and application thereof - Google Patents
Curved surface holographic waveguide combiner with two-dimensional pupil expansion and application thereof Download PDFInfo
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- CN117031617A CN117031617A CN202311073141.1A CN202311073141A CN117031617A CN 117031617 A CN117031617 A CN 117031617A CN 202311073141 A CN202311073141 A CN 202311073141A CN 117031617 A CN117031617 A CN 117031617A
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- 210000001747 pupil Anatomy 0.000 title claims abstract description 27
- 230000000644 propagated effect Effects 0.000 claims abstract description 3
- 238000010168 coupling process Methods 0.000 claims description 20
- 238000005859 coupling reaction Methods 0.000 claims description 20
- 230000003287 optical effect Effects 0.000 claims description 17
- 230000003190 augmentative effect Effects 0.000 claims description 5
- 208000006550 Mydriasis Diseases 0.000 claims 3
- 230000000694 effects Effects 0.000 abstract description 4
- 230000003993 interaction Effects 0.000 abstract description 2
- 238000000034 method Methods 0.000 description 8
- 230000004075 alteration Effects 0.000 description 7
- 230000008878 coupling Effects 0.000 description 7
- 230000005540 biological transmission Effects 0.000 description 6
- 239000000758 substrate Substances 0.000 description 5
- 239000011521 glass Substances 0.000 description 3
- 201000009310 astigmatism Diseases 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 210000003128 head Anatomy 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 230000001902 propagating effect Effects 0.000 description 2
- 230000010076 replication Effects 0.000 description 2
- 208000003464 asthenopia Diseases 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000001427 coherent effect Effects 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 230000001186 cumulative effect Effects 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Classifications
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- G—PHYSICS
- G02—OPTICS
- 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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- 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
- 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
- G02B27/0103—Head-up displays characterised by optical features comprising holographic elements
-
- 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
Abstract
The invention discloses a curved surface holographic waveguide combiner with a two-dimensional pupil expansion, which comprises an image source, a curved surface waveguide, a coupling-in holographic grating, a turning holographic grating and a coupling-out holographic grating, wherein light rays emitted by the image source are subjected to total reflection in the curved surface waveguide after being reacted with the coupling-in holographic grating, are propagated in the curved surface waveguide, and are respectively subjected to interaction with the turning holographic grating and the coupling-out holographic grating and then are incident into the field of vision of an observer; the coupling-in holographic grating, the turning holographic grating and the coupling-out holographic grating are all of curved structures and have the same curvature at the joint of the coupling-in holographic grating, the turning holographic grating and the coupling-out holographic grating and the curved waveguide. The invention also discloses application of the curved surface holographic waveguide combiner with the two-dimensional pupil expansion in head-up display HUD. The curved surface holographic waveguide combiner provided by the invention can realize the display effect of a large exit pupil range, and can be directly combined with the front windshield of an automobile.
Description
Technical Field
The invention relates to the technical field of head-up display and augmented reality, in particular to a curved holographic waveguide combiner with two-dimensional pupil expansion and application thereof.
Background
Head Up Displays (HUDs), also known as heads up displays, were first used on fighters to prevent pilots from frequently looking down at the dashboard, thereby displaying important information on a transparent glass panel in front of their line of sight. Later, the HUD is introduced to the automobile, and the main purpose is to enable a driver to see some key information without transferring vision, so that the driver can concentrate on observing road surface conditions, driving distraction is reduced, driving activity safety is guaranteed, and meanwhile, visual fatigue caused by frequent focal length conversion due to the fact that the driver continuously observes the road conditions at a distance, the navigation information at a near position and the vehicle information is reduced.
As AR technology matures, AR-HUD combined with AR technology has a wider application range, can more effectively improve driving safety, and holographic waveguides for Augmented Reality (AR) show significant advantages compared to other types of combiners. This is because the waveguide can add to the eye box without affecting the field of view (FOV) due to pupil replication. The Chinese patent with publication number CN115016128A discloses a holographic waveguide HUD device based on a polarizer, which comprises a collimation optical system, a waveguide transmission module, an in-coupling element and an out-coupling element; the in-coupling element and the out-coupling element are polarizer holographic gratings; the first collimating optical system is used for collimating light emitted by the image source into the in-coupling element; the in-coupling element is used for coupling the collimated light into the waveguide transmission module; the out-coupling element is used for diffracting light transmitted in the waveguide transmission module out of the waveguide to form a virtual image. And as disclosed in chinese patent publication No. CN217238442U, a waveguide assembly and a head-up display, the waveguide assembly comprising: a waveguide substrate; the entrance pupil grating is arranged on one side of the waveguide substrate and is used for coupling incident light rays into the waveguide substrate for transmission; the exit pupil grating is arranged on one side of the waveguide substrate and is used for coupling light rays transmitted in the waveguide substrate so as to form refracted light rays and reflected light rays; and the light reflection structure is arranged opposite to the exit pupil grating and is used for reflecting the refraction light rays or the reflection light rays.
However, the conventional pupil replication is limited to the planar waveguide, and the planar waveguide and the space are poorly fused, so that aesthetic appeal is lacking, and integration and miniaturization of the HUD are not facilitated. Thus, the existing planar waveguide combiner is insufficient to meet the HUD requirements, and improvements are needed.
Disclosure of Invention
The invention aims to provide a curved surface holographic waveguide combiner with a two-dimensional pupil expansion and application thereof, which can realize the display effect of a large exit pupil range and can be directly combined with a front windshield of an automobile.
The invention provides the following technical scheme:
the curved surface holographic waveguide combiner comprises an image source, a curved surface waveguide, a coupling-in holographic grating, a turning holographic grating and a coupling-out holographic grating, wherein light rays emitted by the image source and the coupling-in holographic grating interact and then are subjected to total reflection in the curved surface waveguide, are propagated in the curved surface waveguide, and are respectively interacted with the turning holographic grating and the coupling-out holographic grating and then are incident into the field of view of an observer;
the coupling-in holographic grating, the turning holographic grating and the coupling-out holographic grating are all of curved structures and have the same curvature at the joint of the coupling-in holographic grating, the turning holographic grating and the coupling-out holographic grating and the curved waveguide.
Further, the curvature centers of the curved waveguide, the coupling-in holographic grating, the turning holographic grating and the coupling-out holographic grating are all positioned at one side close to the observer.
The coupling-in holographic grating and the turning holographic grating are positioned on the surface of one side of the curved waveguide far away from the observer, and the coupling-out holographic grating is positioned on the surface of one side of the curved waveguide close to the observer.
The coupling-in holographic grating, the turning holographic grating and the coupling-out holographic grating are directly prepared on the surface of the curved waveguide during preparation.
The curved waveguide is selected from a cylindrical waveguide, a spherical waveguide or a hyperboloid waveguide.
Further, a collimating lens is arranged between the image source and the coupling-in holographic grating; and light rays emitted by the image source pass through the collimating lens and then react with the coupling-in holographic grating to enter the curved waveguide.
Further, the coupling-in holographic grating and the coupling-out holographic grating are respectively added with different optical powers aiming at different curved waveguides, so that aberration generated in the propagation process of the curved waveguides by light rays is corrected.
Further, when the curved waveguide is a single-curvature curved waveguide: adopting plane wave and cylindrical wave exposure to add unidirectional focal power for correction;
further, when the curved waveguide is a double curvature waveguide: and respectively adding two directional focal powers to perform correction by adopting cylindrical wave exposure with different directions.
The invention also provides application of the curved holographic waveguide combiner with the two-dimensional pupil expansion in head-up display HUD.
Further, the curved holographic waveguide combiner with the two-dimensional pupil expansion is directly integrated on the front windshield of the automobile.
The invention also provides application of the curved surface holographic waveguide combiner with the two-dimensional pupil expansion in an augmented reality glasses scene.
Compared with the prior art, the invention has the following technical effects:
the curved surface holographic waveguide combiner with the two-dimensional expansion pupil provided by the invention adjusts and corrects the aberration generated by light propagation in the curved surface waveguide by utilizing the method of coupling in the holographic grating and coupling out the additional optical power at the holographic grating, realizes a larger exit pupil range and a larger field angle by utilizing the structure of the curved surface waveguide, reduces the limitation of the shape factor on the waveguide, can directly integrate the curved surface waveguide on the front windshield of an automobile, and saves a large space.
Drawings
FIG. 1 is a schematic diagram of a curved holographic waveguide combiner with two-dimensional pupil expansion according to an embodiment of the present invention;
FIG. 2 is a schematic view of light propagation from another view angle of FIG. 1;
FIG. 3 is a schematic diagram of light propagation in a curved waveguide;
FIG. 4 is a graph of curved waveguide curvature versus add power magnitude for the present invention;
FIG. 5 is a graph showing the result of light propagation in a curved waveguide after additional power adjustment in accordance with the present invention.
Detailed Description
The invention will be described in detail below with reference to the drawings and the specific embodiments.
As shown in fig. 1, the present embodiment provides a curved holographic waveguide combiner with two-dimensional pupil expansion, including: the image source 1, the curved waveguide 2, the coupling-in holographic grating 3, the turning holographic grating 4, the coupling-out holographic grating 5 and the collimating lens 6 between the image source 1 and the coupling-in holographic grating 3. The coupling-in holographic grating 3, the turning holographic grating 4 and the coupling-out holographic grating 5 are all of curved structures and have the same curvature at the joint of the curved waveguide 2.
When the waveguide of this embodiment works, the light from the image source 1 is collimated by the collimating lens 6, then enters the curved waveguide 2 through the coupling-in holographic grating 3, and then is transmitted in a total reflection way, and then is continuously transmitted to the coupling-out holographic grating 5 through the turning holographic grating 4, and the total reflection is broken due to the existence of the coupling-out holographic grating 5, and enters the eyes of an observer after transmission, so that the transmission of image information is completed.
It should be noted that the coupling-in holographic grating 3 of the present embodiment may be located on the side of the curved waveguide 2 away from the observer, or may be located on the side of the curved waveguide 2 close to the observer; the same is true for the coupling-out holographic grating 5.
When the coupling-in holographic grating 3 is located on the side of the curved waveguide 2 close to the observer, the working procedure of the grating waveguide according to the embodiment of the present invention may be: light from the image source 1 is collimated by the collimating lens 6, then enters the curved waveguide 2, and then continuously propagates to the coupling-in holographic grating 3, and after reacting with the light, the light continuously propagates to the coupling-out holographic grating 5 after passing through the turning holographic grating 4, and enters the human eye of an observer after being transmitted.
When the out-coupling holographic grating 5 is located on the side of the curved waveguide 2 remote from the observer, the grating waveguide according to the embodiments of the present invention operates in a similar manner to that described above, except that reflection occurs into the observer's eye when light eventually propagates to the out-coupling holographic grating 5.
It should be noted that the curvature centers of the curved waveguide 2, the coupling-in holographic grating 3, the turning holographic grating 4, and the coupling-out holographic grating 5 in the embodiment of the present invention are all located at the side close to the observer.
Referring to fig. 3 to 5, the principle of curved waveguide correction is mainly: the diffraction, total reflection, and the addition power of the holographic grating.
Specifically, as shown in fig. 3, if the light is not corrected while propagating through the curved waveguide 2, the incident light beam will be reshaped by refraction induced by the curved waveguide surface during injection and by multiple TIR reflections on the curved waveguide surface during propagation, thereby switching back and forth between divergence and focusing, as indicated by light segments 11, 13 and light segments 12, 14.
For curved waveguides of fixed thickness, the light rays will generate some extra optical power after each total reflection (TIR), resulting in astigmatism and defocus after long propagation through a waveguide of relatively large thickness compared to the radius of curvature, due to the different radii of curvature of the two curved surfaces. In order to propagate light inside a curved waveguide, when light interacts with the top and bottom surfaces by TIR, the light must be balanced between expansion and focusing, allowing the outcoupling holographic grating to couple out light with little aberration. At the same time, total reflection is independent of wavelength, so curved waveguides allow a certain bandwidth of spectrum to propagate through the waveguide.
Further, taking a cylindrical curved waveguide as an example, since it has curvature in only one direction, defocus occurs in only one direction, and the other direction remains undisturbed. The main aberration experienced upon total reflection (TIR) in a one-dimensional curved waveguide is cumulative astigmatism due to the interaction of light with the front and back surfaces of curved waveguides having different optical powers.
Therefore, when the curved waveguide 2 is a single curvature curved waveguide, when the coupling-in holographic grating 3 is prepared, only the optical power along the curvature direction is required to be added, and meanwhile, the negative optical power along the same direction is added to the coupling-out holographic grating 5, so that the aberration can be corrected.
When the curved waveguide 2 is a double curvature curved waveguide, defocus occurs in both directions due to curvature in both directions, so that when the coupling-in holographic grating 3 and the coupling-out holographic grating 5 are prepared, optical power needs to be added to both directions to achieve the purpose of aberration correction.
The exposure method of the coupling holographic grating is different from the traditional plane wave and plane wave or spherical wave exposure. The aberration correction of the curved waveguide needs to add unidirectional optical power, so that the holographic grating exposure of the invention adopts a cylindrical wave and plane wave exposure method to add unidirectional optical power. And the hyperbolic curved waveguide is added with optical power in two directions, and is realized by adopting a method of exposing two beams of orthogonal cylindrical waves.
Specifically, as shown in fig. 4, the relationship between the curvature of the curved waveguide 2 and the required magnitude of the additional power is enumerated. In the embodiment of the invention, the curvature of the curved waveguide is 168.175-171.45mm, and a double-conical waveguide is taken as an example, as shown in fig. 5, optical power in two directions is respectively added at the coupling-in holographic grating 3, the optical power along the propagation direction is 2.13D, and the optical power perpendicular to the propagation direction is 1.10D. The size of the corrected light ray segment 21 and the size of the corrected light ray segment 22 are not changed, so that the image cannot be deformed in the propagation process. The coupling-out holographic grating 5 also has an additional optical power, which converts the light propagating in the curved waveguide 2 into parallel light for incidence into the human eye when the light is coupled out.
It is noted that the coupling elements (the coupling-in holographic grating 3, the turning holographic grating 4 and the coupling-out holographic grating 5) are all bulk phase gratings, and are directly prepared on the curved waveguide 2, and the specific preparation method is as follows: firstly, a photosensitive material is coated on the surface of a curved waveguide 2, and coherent fringes of cylindrical light waves and planar light waves are exposed and recorded by a holographic method to prepare the curved waveguide 2 with a specific phase grating on the surface.
It should be noted that, the curved surface holographic waveguide combiner of the embodiment of the present invention can be applied not only to a head-up display scene, but also to an augmented reality glasses scene.
In summary, the beneficial effects of the invention are as follows:
1. compared with the traditional planar waveguide, the curved waveguide has a larger field angle, and a larger exit pupil range can be obtained under the condition of two-dimensional pupil expansion.
2. In head-up display (HUD) of an automobile, the curved surface holographic waveguide combiner can be directly integrated on a front windshield of the automobile, so that the system volume of the HUD is greatly reduced, and the HUD is more attractive.
In this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a list of elements is included, and may include other elements not expressly listed.
The foregoing is merely illustrative of the present invention, and the present invention is not limited thereto, and any person skilled in the art will readily recognize that variations or substitutions are within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (9)
1. The curved surface holographic waveguide combiner is characterized by comprising an image source, a curved surface waveguide, a coupling-in holographic grating, a turning holographic grating and a coupling-out holographic grating, wherein light rays emitted by the image source and the coupling-in holographic grating interact and then are subjected to total reflection in the curved surface waveguide, are propagated in the curved surface waveguide, and are respectively interacted with the turning holographic grating and the coupling-out holographic grating and then are incident into the field of view of an observer;
the coupling-in holographic grating, the turning holographic grating and the coupling-out holographic grating are all of curved structures and have the same curvature at the joint of the coupling-in holographic grating, the turning holographic grating and the coupling-out holographic grating and the curved waveguide.
2. The curved surface holographic waveguide combiner with two-dimensional pupil expansion of claim 1, wherein the centers of curvature of the curved surface waveguide, the in-coupling holographic grating, the turning holographic grating, and the out-coupling holographic grating are all located on a side near the observer.
3. The curved holographic waveguide combiner with two-dimensional mydriasis of claim 1, wherein the curved waveguide is selected from a cylindrical waveguide, a spherical waveguide, or a hyperbolic waveguide.
4. The curved holographic waveguide combiner with two-dimensional pupil expansion of claim 1, wherein a collimating lens is disposed between the image source and the incoupling holographic grating; and light rays emitted by the image source pass through the collimating lens and then react with the coupling-in holographic grating to enter the curved waveguide.
5. The curved holographic waveguide combiner with two-dimensional pupil expansion of claim 1, wherein the in-coupling holographic grating and the out-coupling holographic grating are each attached with different optical powers for different curved waveguides.
6. The curved holographic waveguide combiner with two-dimensional mydriasis of claim 5, wherein when the curved waveguide is a single curvature curved waveguide: adopting plane wave and cylindrical wave exposure to add unidirectional focal power for correction;
when the curved waveguide is a double curvature waveguide: and respectively adding two directional focal powers to perform correction by adopting cylindrical wave exposure with different directions.
7. Use of a curved holographic waveguide combiner with two-dimensional pupil expansion according to any of claims 1-6 in a heads-up display HUD.
8. The use of claim 7, wherein the curved holographic waveguide combiner with two-dimensional pupil expansion is integrated directly onto the front windshield of an automobile.
9. Use of a curved holographic waveguide combiner with two-dimensional mydriasis according to any of claims 1-6 in an augmented reality eyewear scene.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311073141.1A CN117031617A (en) | 2023-08-24 | 2023-08-24 | Curved surface holographic waveguide combiner with two-dimensional pupil expansion and application thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311073141.1A CN117031617A (en) | 2023-08-24 | 2023-08-24 | Curved surface holographic waveguide combiner with two-dimensional pupil expansion and application thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117031617A true CN117031617A (en) | 2023-11-10 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202311073141.1A Pending CN117031617A (en) | 2023-08-24 | 2023-08-24 | Curved surface holographic waveguide combiner with two-dimensional pupil expansion and application thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN117031617A (en) |
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2023
- 2023-08-24 CN CN202311073141.1A patent/CN117031617A/en active Pending
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