CN109656026B - Holographic optical waveguide display device with large field angle and method - Google Patents
Holographic optical waveguide display device with large field angle and method Download PDFInfo
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- CN109656026B CN109656026B CN201910138491.9A CN201910138491A CN109656026B CN 109656026 B CN109656026 B CN 109656026B CN 201910138491 A CN201910138491 A CN 201910138491A CN 109656026 B CN109656026 B CN 109656026B
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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
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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
- G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
- G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
- G02B6/0013—Means for improving the coupling-in of light from the light source into the light guide
- G02B6/0023—Means for improving the coupling-in of light from the light source into the light guide provided by one optical element, or plurality thereof, placed between the light guide and the light source, or around the light source
- G02B6/0026—Wavelength selective element, sheet or layer, e.g. filter or grating
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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
- G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
- G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
- G02B6/0033—Means for improving the coupling-out of light from the light guide
- G02B6/005—Means for improving the coupling-out of light from the light guide provided by one optical element, or plurality thereof, placed on the light output side of the light guide
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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
- G02B2027/0123—Head-up displays characterised by optical features comprising devices increasing the field of view
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Abstract
The invention discloses a holographic optical waveguide display device with a large field angle and a method thereof, wherein the display device comprises: an optical waveguide, further comprising: the first relay grating and the second relay grating are respectively arranged on the lower surface and the upper surface of the light transmission area of the optical waveguide; the coupling-in grating and the coupling-out grating are respectively arranged in the light incident area and the light emergent area at the two ends of the optical waveguide; the grating periods of the first relay grating and the second relay grating are consistent, and the first relay grating and the second relay grating work in the same reflection diffraction order. The invention can ensure that the incident angle of view of the light is not limited by the total reflection condition of the light waveguide, and improves the angle of view of the holographic optical waveguide of the display device.
Description
Technical Field
The invention relates to the technical field of optical waveguides, in particular to a holographic optical waveguide display device with a large field angle and a method thereof.
Background
AR (Augmented Reality) display devices can integrate a real background environment while displaying virtual image information, and realize organic combination of virtual and Reality, and thus have been widely used in many fields such as simulation training, electronic games, microscopy, surgical operations, and the like. AR display devices are mainly head-mounted, and therefore, the devices are required to be thin and light to satisfy comfort for long-term wearing. In various implementation schemes of the AR display device, the holographic optical waveguide technology uses a slab waveguide as a light propagation medium, and uses a holographic element as a light path folding device, which has the advantages of simple structure, light weight and small volume, and is a key technology of the next generation of AR display.
The technical principle of holographic optical waveguides is shown in fig. 1. Incident light is coupled into the optical grating to be diffracted and coupled into the optical waveguide, and the deflection direction of the light meets the total reflection condition of the optical waveguide, so that the light forwards propagates in the optical waveguide in a total reflection mode. The structure of the coupling-out grating is symmetrical to that of the coupling-in grating, so that the light is transmitted to the coupling-out grating to be diffracted, and the angle is recovered to the direction of the incident light to be emitted from the light waveguide. The incoupling grating and the outcoupling grating may be transmissive or reflective, both transmissive in fig. 1. In order to ensure that human eyes can observe images within a certain range, pupil expansion needs to be carried out, and by reasonably setting the diffraction efficiency distribution of the coupling-out grating, partial energy is coupled out of the light waveguide when light passes through the coupling-out grating, and the residual energy is continuously transmitted forwards, so that the light passes through the coupling-out grating for multiple times, and the expansion of the pupil is realized.
According to the principle of the holographic optical waveguide technology, when light rays with different viewing angles enter, the direction deflected after being coupled into the optical grating must satisfy the total reflection condition of the optical waveguide, so the size of the viewing angle is limited by the total reflection condition, and the size of the viewing angle is expressed as formula one:
in the formula I, theta is a half field angle, n1 is an ambient refractive index, n2 is a refractive index of the optical waveguide substrate, and lambda min and lambda max are minimum and maximum wavelengths of incident light. The angle of view can be increased by increasing the refractive index of the optical waveguide substrate, but the requirement for materials is high, and the increase range of the refractive index of the materials is limited, so that the angle of view of the current holographic optical waveguide is only 50 degrees at most.
Disclosure of Invention
In view of the above, an object of the present invention is to provide a large-viewing-angle holographic optical waveguide display device and method, which can improve the viewing angle of the holographic optical waveguide of the display device by preventing the viewing angle of light incident thereon from being limited by the total reflection condition of the optical waveguide.
In view of the above object, the present invention provides a large field angle holographic optical waveguide display device, comprising: an optical waveguide, further comprising:
the first relay grating and the second relay grating are respectively arranged on the lower surface and the upper surface of the light transmission area of the optical waveguide;
the coupling-in grating and the coupling-out grating are respectively arranged in the light incident area and the light emergent area at the two ends of the optical waveguide;
the grating periods of the first relay grating and the second relay grating are consistent, and the first relay grating and the second relay grating work in the same reflection diffraction order.
Further, the display device further includes:
the third relay grating is arranged on the surface of the light emergent area of the optical waveguide and is covered by the light coupling grating;
the third relay grating has the same grating period as the first and second relay gratings, and works in the same reflection diffraction order, and the third relay grating also works in transmission 0 order.
Preferably, the diffraction efficiency of the third relay grating for transmitting 0 th order in the light propagation direction increases, and the diffraction efficiency of the reflection diffraction order decreases.
PreferablyThe third relay grating divides N regions along the light propagation direction, wherein the diffraction efficiency of the transmission 0 order of the ith region is etaTiThe following formula two shows:
the diffraction efficiency of the reflection diffraction order of the i-th zone operation is etaRiThe following formula three shows:
ηRi＝1-ηTi(formula three).
Further, the display device further includes:
and the micro display is used for displaying a two-dimensional image and emitting light with image information to the coupling-in grating.
Preferably, the microdisplay is specifically configured to display a two-dimensional image with a higher brightness for image areas where the more light is refracted into the coupled-out grating.
The invention also provides a large-field angle holographic optical waveguide display method, which comprises the following steps:
the light is incident into the coupling grating arranged in the light incident area of the optical waveguide and then is diffracted;
the light diffracted by the coupling-in grating is reflected and diffracted for multiple times by the first relay grating and the second relay grating which are arranged on the lower surface and the upper surface of the light transmission area of the optical waveguide, and is transmitted in the optical waveguide;
and after the light transmitted in the optical waveguide enters the coupling-out grating arranged in the light exit area of the optical waveguide, the light is diffracted by the coupling-out grating and then is emitted.
Further, before the light propagating in the optical waveguide enters the coupling grating disposed in the light exit area of the optical waveguide, the method further includes:
the light rays transmitted in the optical waveguide enter a third relay grating which is arranged on the surface of the light ray outgoing area of the optical waveguide and covered by the coupling grating;
a part of the light rays entering the third relay grating are transmitted to the coupling-out grating and are emitted after being diffracted by the coupling-out grating; and the other part of the light is reflected and diffracted for at least one time between the third relay grating and the first/second relay grating, and is transmitted to the coupling grating by the third relay grating to be emitted.
Further, before the light is diffracted after entering the coupling-in grating disposed in the light entrance region of the optical waveguide, the method further includes:
the micro display displays a two-dimensional image and emits light with image information to the coupling grating; wherein the brightness of the display is higher for image areas where the more the refraction times the light has propagated to the outcoupling grating.
In the large-view-angle holographic optical waveguide display device of the embodiment of the invention, the first relay grating and the second relay grating are respectively arranged on the lower surface and the upper surface of the light transmission area of the optical waveguide, so that the deflection angle of the coupled grating to incident light can not meet the total reflection condition of the optical waveguide substrate, and the light is not propagated in the optical waveguide in a total reflection manner any more, therefore, the propagation angle is not limited by the total reflection condition, the angular bandwidth of light path propagation in the optical waveguide is improved, namely, the view angle of the holographic optical waveguide is improved, and no special requirement is provided for the refractive index of the optical waveguide substrate material.
Preferably, in the large-field-angle holographic optical waveguide display device according to the embodiment of the present invention, a third relay grating covered by the coupling grating is disposed in the light exit region of the optical waveguide, the third relay grating has a same grating period as the first and second relay gratings and operates at the same reflection diffraction order, and the third relay grating also operates at transmission 0 level. Thus, when light enters the third relay grating, part of energy is transmitted to the coupling-out grating and is emitted after being diffracted by the coupling-out grating; the residual energy continues to be transmitted forwards, so that the light rays pass through the third relay grating for multiple times and are then diffracted and emitted by the coupling grating, and the pupil expansion is realized.
Preferably, in the large-field-angle holographic optical waveguide display device according to the embodiment of the present invention, the diffraction efficiency of the third relay grating is distributed in a gradient manner, so as to ensure uniformity of exit light after pupil expansion.
Preferably, in the large-field-angle holographic optical waveguide display device according to the embodiment of the present invention, the microdisplay may perform non-uniform processing on the brightness of an image displayed by an image source in advance: when displaying a two-dimensional image, the brightness of the display is higher for image areas where the number of refraction and reflection of light rays to the outcoupling grating is larger, thereby compensating for the brightness non-uniformity of images of different field angles emitted from the outcoupling grating.
Drawings
FIG. 1 is a technical schematic diagram of a prior art holographic optical waveguide;
FIG. 2 is a schematic structural diagram of a large-field angle holographic optical waveguide display device according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of light rays with different angles of view according to an embodiment of the present invention, which are refracted at different times during propagation in an optical waveguide;
FIG. 4 is a flow chart of a method for displaying a large field angle holographic optical waveguide according to an embodiment of the present invention;
FIG. 5a is a schematic diagram illustrating the angle of light propagation in a large field angle holographic optical waveguide display device according to an embodiment of the present invention;
fig. 5b is a schematic diagram of a light outcoupling process in the large-field angle holographic optical waveguide display device according to the embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to specific embodiments and the accompanying drawings.
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative only and should not be construed as limiting the invention.
As used herein, the singular forms "a", "an", "the" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. As used herein, the term "and/or" includes all or any element and all combinations of one or more of the associated listed items.
It should be noted that all expressions using "first" and "second" in the embodiments of the present invention are used for distinguishing two entities with the same name but different names or different parameters, and it should be noted that "first" and "second" are merely for convenience of description and should not be construed as limitations of the embodiments of the present invention, and they are not described in any more detail in the following embodiments.
In the technical scheme of the invention, the relay gratings are arranged on the upper surface and the lower surface of the optical waveguide, so that the propagation of light rays in the optical waveguide is not limited by total reflection conditions any more, the field angle of the holographic optical waveguide technology is improved, and the requirement on the refractive index of an optical waveguide substrate material is reduced.
The technical scheme of the invention is explained in detail in the following with the accompanying drawings.
The holographic optical waveguide display device with a large field angle provided by the embodiment of the invention is shown in fig. 2, and comprises: an optical waveguide, an incoupling grating 201, an outcoupling grating 202, a first relay grating 203, and a second relay grating 204.
For convenience of description, a region where light is incident into the optical waveguide is referred to as a light incident region of the optical waveguide, and a region where light is emitted out of the optical waveguide is referred to as a light emitting region of the optical waveguide; the region in which light propagates in the optical waveguide after entering the optical waveguide and before exiting the light exit region is referred to as a light transmission region of the optical waveguide. The light incident area and the light emergent area of the light guide are respectively positioned at two ends of the light guide.
The optical waveguide may be a slab waveguide, and the incoupling grating 201 and the outcoupling grating 202 are respectively disposed in a light incident region and a light exiting region at two ends of the optical waveguide; the first relay grating 203 and the second relay grating 204 are respectively disposed on the lower surface and the upper surface of the light transmission region of the optical waveguide.
Wherein, the grating period of the in-grating 201 is the same as that of the out-grating 202; the incoupling grating 201 may be a reflective grating or a transmissive grating and the outcoupling grating 202 may be a transmissive grating.
The grating periods of the first relay grating 203 and the second relay grating 204 are consistent and work in the same reflection diffraction order; for example, the first and second relay gratings may both operate at the +1 st order of reflection, or both operate at the-1 st order of reflection. Preferably, the diffraction efficiency of the reflection diffraction orders of the first and second relay gratings is designed to be 100% to reduce the loss of light propagating in the optical waveguide.
Preferably, in view of the application of the technical solution to pupil expansion, the large-field-angle holographic optical waveguide display device provided in the embodiment of the present invention may further include: and a third relay grating 205 disposed on the surface of the light exit region of the optical waveguide and covered by the coupling grating.
That is to say, the coupling grating 202 covers the outer side of the third relay grating 205, that is, one side of the third relay grating 205 faces the inside of the optical waveguide, and the other side covers the coupling grating 202; the outcoupling grating 202 corresponds to the third relay grating 205 in size. The third relay grating 205 has the same grating period as the first and second relay gratings, and operates at the same reflection diffraction order, and the third relay grating also operates at transmission 0. Thus, when light enters the third relay grating 205, part of the energy is transmitted to the coupling-out grating 202, and is diffracted by the coupling-out grating 202 and then emitted; the remaining energy continues to propagate forward, so that the light passes through the third relay grating 205 a plurality of times and is diffracted out by the coupling-out grating 202, and the pupil expansion is realized.
Preferably, in order to ensure the uniformity of emergent light after pupil expansion, the diffraction efficiency of the third relay grating is distributed in a gradient manner; specifically, the diffraction efficiency of the third relay grating 205 that transmits 0 th order in the light propagation direction increases, and the diffraction efficiency of the reflection diffraction order that operates decreases in the light propagation direction.
Specifically, the third relay grating 205 divides N regions in the light propagation direction, where the i-th region has a diffraction efficiency of η of transmitting 0 th orderTiThe following formula two shows:
the diffraction efficiency of the reflection diffraction order of the i-th zone operation is etaRiThe following formula three shows:
ηRi＝1-ηTi(formula three)
Since the third relay grating 205 is designed to operate at two diffraction orders: the first and second relay gratings work with a reflection diffraction order and a transmission 0 order, and the third relay grating 205 has an i-th zone with a diffraction efficiency of the transmission 0 order of ηTiThe diffraction efficiency of the reflection diffraction order of the i-th zone operation is etaRiSo that the light energy transmitted from the third relay grating 205 is equal in each area, so that the light coupled out from the coupling-out grating 202 is uniform in brightness.
Further, the holographic optical waveguide display device with a large field angle provided by the embodiment of the present invention may further include: a microdisplay 206.
The microdisplay 206 is used to display a two-dimensional image and emits diverging light with image information towards the incoupling grating 201.
For the holographic grating, although the diffraction efficiency can reach 100% theoretically, the diffraction efficiency is difficult to achieve in the actual design and processing, so that the light has certain energy loss in the transmission process. As shown in fig. 3, the optical paths shown by the dotted lines and the optical paths shown by the solid lines experience different numbers of refraction and reflection when propagating to the coupling-out grating, and when the actual diffraction efficiencies of the first and second relay gratings are not 100%, the energy losses of the two optical paths are different, so that the brightness of images with different viewing angles when the light exits from the coupling-out grating is not uniform.
In order to compensate for the brightness non-uniformity of the images with different field angles emitted from the coupled grating, the microdisplay 206 in the large-field-angle holographic optical waveguide display device provided by the embodiment of the invention can perform the brightness non-uniformity processing on the image displayed by the image source in advance.
Thus, preferably, the microdisplay 206 can display a higher brightness when displaying a two-dimensional image for regions of the image where the more the light is refracted to the out-coupling grating.
In particular, the microdisplay 206 displays L for the region of the image where the light propagates to the coupled-out grating with k-j inflectionsk-j＝η2j×Lk(ii) a Wherein eta is the actual diffraction efficiency of the reflection diffraction orders of the first and second relay gratings; l iskThe brightness displayed by the micro display for the image area with k refraction times of light rays transmitted to the coupled-out grating; k is the highest number of refraction and reflection; j is a natural number less than k.
Further, the holographic optical waveguide display device with a large field angle provided by the embodiment of the present invention may further include: a collimating lens 207 disposed between the microdisplay 206 and the incoupling grating 201.
The collimating lens 207 is used to collimate the diverging light emitted by the microdisplay 206 before entering the incoupling grating 201.
Based on the above holographic optical waveguide display device with a large field angle, a specific flow of the holographic optical waveguide display method with a large field angle provided by the embodiment of the present invention is shown in fig. 4, and the method includes the following steps:
step S401: light is incident on the incoupling grating 201.
Specifically, the microdisplay 206 displays a two-dimensional image, and emits light with image information to the in-coupling grating 201 through the collimating lens 207; wherein the microdisplay 206 displays a higher brightness for image regions where the more the light is transmitted to the coupled-out grating; specifically, for an image region with a k-j number of refraction and reflection of light propagating to the coupled-out grating, the display brightness may be Lk-j＝η2j×Lk(ii) a Wherein eta is the actual diffraction efficiency of the reflection diffraction orders of the first and second relay gratings; l iskThe brightness displayed by the micro display for the image area with k refraction times of light rays transmitted to the coupled-out grating; k is the highest number of refraction and reflection; j is a natural number less than k.
Light emitted by the microdisplay 206 is incident onThe light incident region of the optical waveguide is diffracted after being coupled into the grating 201. For example, as shown in fig. 5a, a light ray with a certain angle of view is incident on the reflective coupling grating 201 and is diffracted, and the diffraction angle θ1The total reflection condition may not be necessarily satisfied.
Step S402: light is reflected and diffracted for many times through the first relay grating and the second relay grating which are arranged on the lower surface and the upper surface of the light transmission area of the optical waveguide, and then is transmitted in the optical waveguide.
Specifically, the light diffracted by the coupling-in grating 201 propagates in the optical waveguide through multiple reflection diffraction by the first and second relay gratings disposed on the lower and upper surfaces of the light transmission region of the optical waveguide; for example, as shown in FIG. 5a, light diffracted by the in-coupling grating 201 is at an angle θ1Incident on the first relay grating 203, the angle of incidence i of this light with respect to the first relay grating 2032＝θ1The light is diffracted at the first relay grating 203, for example, with +1 order of diffraction order, diffraction efficiency of 100%, and diffraction angle θ2(ii) a The light is incident on the second relay grating 204 at an angle of incidence i3＝θ2Since the first relay grating 203 and the second relay grating 204 have the same grating period, the diffraction angle θ of the light ray at the second relay grating 204 is the same order (+1 order)3＝i2. It follows that the light will periodically propagate forward in the optical waveguide in a "zig-zag" manner between the first relay grating 203 and the second relay grating 204.
Because the light is not propagated in the optical waveguide in a total reflection mode any more, the propagation angle is not limited by the total reflection condition, the angular bandwidth of the optical path propagation in the optical waveguide is improved, namely the field angle of the holographic optical waveguide is improved, and no special requirement is made on the refractive index of the optical waveguide substrate material.
Step S403: after the light enters the coupling grating 202 arranged in the light exit area of the optical waveguide, the light is diffracted by the coupling grating 202 and then emitted.
Preferably, in the case that the third relay grating 205 is disposed on the surface of the light exit area of the optical waveguide, and the third relay grating 205 is covered by the coupling-out grating 202, before the light enters the coupling-out grating 202 disposed on the light exit area of the optical waveguide, the light propagating in the optical waveguide first enters the third relay grating 205 disposed on the surface of the light exit area of the optical waveguide and covered by the coupling-out grating; furthermore, a part of the light incident on the third relay grating 205 is transmitted to the coupling-out grating 202, and is diffracted by the coupling-out grating and then emitted; the other part of the light is reflected and diffracted at least once between the third relay grating and the first/second relay grating, and is finally transmitted to the coupling-out grating 202 by the third relay grating 205.
Specifically, the light coupling-out process from the large-field angle holographic optical waveguide display device provided by the embodiment of the present invention can be as shown in fig. 5 b. The third relay grating 205 has the same grating period as the first and second relay gratings, so that the light incident on the third relay grating 205 has the same diffraction angle in the same reflection diffraction order; whereas light exiting the third relay grating 205 with transmission 0 diffraction order enters the outcoupling grating 202 without changing direction, the angle of incidence iO＝θ1Since the grating periods of the coupling-out grating 202 and the coupling-in grating 201 are equal, the light is diffracted by the coupling-out grating 202 and then emitted in the direction of the original incident coupling-in grating 201, i.e. the light returns to the original field angle direction for propagation.
In the large-view-angle holographic optical waveguide display device of the embodiment of the invention, the first relay grating and the second relay grating are respectively arranged on the lower surface and the upper surface of the light transmission area of the optical waveguide, so that the deflection angle of the coupled grating to incident light can not meet the total reflection condition of the optical waveguide substrate, and the light is not propagated in the optical waveguide in a total reflection manner any more, therefore, the propagation angle is not limited by the total reflection condition, the angular bandwidth of light path propagation in the optical waveguide is improved, namely, the view angle of the holographic optical waveguide is improved, and no special requirement is provided for the refractive index of the optical waveguide substrate material.
Preferably, in the large-field-angle holographic optical waveguide display device according to the embodiment of the present invention, a third relay grating covered by the coupling grating is disposed in the light exit region of the optical waveguide, the third relay grating has a same grating period as the first and second relay gratings and operates at the same reflection diffraction order, and the third relay grating also operates at transmission 0 level. Thus, when light enters the third relay grating, part of energy is transmitted to the coupling-out grating and is emitted after being diffracted by the coupling-out grating; the residual energy continues to be transmitted forwards, so that the light rays pass through the third relay grating for multiple times and are then diffracted and emitted by the coupling grating, and the pupil expansion is realized.
Preferably, in the large-field-angle holographic optical waveguide display device according to the embodiment of the present invention, the diffraction efficiency of the third relay grating is distributed in a gradient manner, so as to ensure uniformity of exit light after pupil expansion.
Preferably, in the large-field-angle holographic optical waveguide display device according to the embodiment of the present invention, the microdisplay may perform non-uniform processing on the brightness of an image displayed by an image source in advance: when displaying a two-dimensional image, the brightness of the display is higher for image areas where the number of refraction and reflection of light rays to the outcoupling grating is larger, thereby compensating for the brightness non-uniformity of images of different field angles emitted from the outcoupling grating.
Those of skill in the art will appreciate that various operations, methods, steps in the processes, acts, or solutions discussed in the present application may be alternated, modified, combined, or deleted. Further, various operations, methods, steps in the flows, which have been discussed in the present application, may be interchanged, modified, rearranged, decomposed, combined, or eliminated. Further, steps, measures, schemes in the various operations, methods, procedures disclosed in the prior art and the present invention can also be alternated, changed, rearranged, decomposed, combined, or deleted.
Those of ordinary skill in the art will understand that: the discussion of any embodiment above is meant to be exemplary only, and is not intended to intimate that the scope of the disclosure, including the claims, is limited to these examples; within the idea of the invention, also 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. Therefore, any omissions, modifications, substitutions, improvements and the like that may be made without departing from the spirit and principles of the invention are intended to be included within the scope of the invention.
Claims (8)
1. A large field angle holographic optical waveguide display device comprising: an optical waveguide, further comprising:
the first relay grating and the second relay grating are respectively arranged on the lower surface and the upper surface of the light transmission area of the optical waveguide;
the coupling-in grating and the coupling-out grating are respectively arranged in the light incident area and the light emergent area at the two ends of the optical waveguide;
the third relay grating is arranged on the surface of the light emergent area of the optical waveguide and is covered by the light coupling grating;
the grating periods of the first relay grating and the second relay grating are consistent, and the first relay grating and the second relay grating work in the same reflection diffraction order; the third relay grating has the same grating period as the first and second relay gratings, and works in the same reflection diffraction order, and the third relay grating also works in transmission 0 order.
2. The large field angle holographic optical waveguide display of claim 1, wherein the diffraction efficiency of the third relay grating for transmitting 0 th order in the light propagation direction increases and the diffraction efficiency of the reflective diffraction order decreases.
3. The large field angle holographic optical waveguide display device of claim 2, wherein the third relay grating divides N regions in the light propagation direction, wherein the i-th region has a diffraction efficiency of η in transmission of 0 th orderTiThe following formula two shows:
the diffraction efficiency of the reflection diffraction order of the i-th zone operation is etaRiThe following formula three shows:
ηRi＝1-ηTi(formula three).
4. The large field angle holographic optical waveguide display of claim 1, further comprising:
and the micro display is used for displaying a two-dimensional image and emitting light with image information to the coupling-in grating.
5. The large field angle holographic optical waveguide display of claim 4,
the microdisplay is particularly useful for displaying two-dimensional images with higher brightness for image areas where the more the light is refracted to the coupled-out grating.
6. The large field angle holographic optical waveguide display of claim 5,
the microdisplay is specifically configured to display a luminance L for an image region with k-j of refraction and reflection times when light is transmitted to the coupled-out gratingk-j＝η2j×Lk；
Wherein eta is the actual diffraction efficiency of the reflection diffraction orders of the first and second relay gratings; l iskThe brightness displayed by the micro display for the image area with k refraction times of light rays transmitted to the coupled-out grating; k is the highest number of refraction and reflection; j is a natural number less than k.
7. A method for displaying a holographic optical waveguide with a large field angle, comprising:
the light is incident into the coupling grating arranged in the light incident area of the optical waveguide and then is diffracted;
the light diffracted by the coupling-in grating is reflected and diffracted for multiple times by the first relay grating and the second relay grating which are arranged on the lower surface and the upper surface of the light transmission area of the optical waveguide, and is transmitted in the optical waveguide;
the light rays transmitted in the optical waveguide enter a third relay grating which is arranged on the surface of the light ray outgoing area of the optical waveguide and covered by the coupling grating;
after light transmitted in the optical waveguide enters a coupling-out grating arranged in a light emergent area of the optical waveguide, the light is diffracted by the coupling-out grating and then is emitted;
the third relay grating has the same grating period as the first and second relay gratings and works in the same reflection diffraction order, and the third relay grating also works in the transmission 0 order; a part of the light rays entering the third relay grating are transmitted to the coupling-out grating and are emitted after being diffracted by the coupling-out grating; and the other part of the light is subjected to at least one reflection diffraction between the third relay grating and the second relay grating so as to transmit 0-order diffraction from the third relay grating to the coupling grating for emission.
8. The method for displaying a holographic optical waveguide with a large field angle according to claim 7, wherein before the light is diffracted after being incident on an in-coupling grating provided in a light incident region of the optical waveguide, the method further comprises:
the micro display displays a two-dimensional image and emits light with image information to the coupling grating; wherein the brightness of the display is higher for image areas where the more the refraction times the light has propagated to the outcoupling grating.
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| CN201910138491.9A CN109656026B (en) | 2019-02-25 | 2019-02-25 | Holographic optical waveguide display device with large field angle and method |
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| CN110764265A (en) * | 2019-11-13 | 2020-02-07 | 京东方科技集团股份有限公司 | Near-to-eye light guide assembly and display device |
| CN111308717B (en) * | 2020-03-31 | 2022-03-25 | 京东方科技集团股份有限公司 | Display module, display method and display device |
| CN111323923B (en) * | 2020-04-15 | 2022-05-20 | 杭州光粒科技有限公司 | Optical system for augmented reality display |
| CN115509015A (en) * | 2020-04-29 | 2022-12-23 | 宁波舜宇光电信息有限公司 | Lens unit and AR apparatus including the same |
| CN113568168B (en) * | 2020-04-29 | 2023-02-24 | 宁波舜宇光电信息有限公司 | Lens unit and AR apparatus including the same |
| CN111722317B (en) * | 2020-07-14 | 2022-11-08 | 北京至格科技有限公司 | Diffraction light waveguide lens |
| CN113970805B (en) * | 2020-07-24 | 2023-06-09 | 宁波舜宇光电信息有限公司 | Waveguide assembly and near-eye display device including the same |
| CN113031243B (en) * | 2021-03-26 | 2021-08-31 | 杭州辰景光电科技有限公司 | Reflective on-chip digital holographic microscopic device based on waveguide sheet |
| CN113218627B (en) * | 2021-03-26 | 2022-10-14 | 歌尔股份有限公司 | Grating diffraction efficiency testing device and method |
| CN115509006A (en) * | 2021-06-23 | 2022-12-23 | 华为技术有限公司 | Optical device and electronic device |
| CN115542539A (en) * | 2021-06-29 | 2022-12-30 | 上海海思技术有限公司 | Wearable device and preparation method thereof |
| CN113885119A (en) * | 2021-10-12 | 2022-01-04 | 哈尔滨工业大学（深圳） | Diffraction grating optical waveguide-based under-screen image pickup apparatus, method, and program product |
| CN115166897B (en) * | 2022-01-13 | 2023-04-07 | 北京驭光科技发展有限公司 | Diffractive optical waveguide and display device |
| CN115877560B (en) * | 2023-03-08 | 2023-06-16 | 杭州光粒科技有限公司 | Laser scanning imaging module, device and AR display equipment |
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