CN116400502A - Light transmission structure and head-mounted display device - Google Patents
Light transmission structure and head-mounted display device Download PDFInfo
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- CN116400502A CN116400502A CN202111618571.8A CN202111618571A CN116400502A CN 116400502 A CN116400502 A CN 116400502A CN 202111618571 A CN202111618571 A CN 202111618571A CN 116400502 A CN116400502 A CN 116400502A
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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
- G02B27/017—Head mounted
- G02B27/0172—Head mounted 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
- G02B27/01—Head-up displays
Abstract
The invention discloses an optical transmission structure and a head-mounted display device, wherein the optical transmission structure comprises a substrate, at least two coupling-in gratings and at least two coupling-out gratings, wherein the at least two coupling-in gratings are arranged on one surface of the substrate at intervals; the at least two coupling-out gratings are arranged on any surface of the substrate, and the projections of the at least two coupling-out gratings on the substrate are arranged side by side and are positioned on the same side of the two coupling-in gratings; the light received by at least two coupling-in gratings is respectively emitted to at least two coupling-out gratings after passing through the substrate, wherein the light is emitted after passing through one coupling-out grating and then the other coupling-out grating. The optical transmission structure of the technical scheme of the invention can realize a two-dimensional pupil expansion effect and realize an efficient and compact optical transmission structure.
Description
Technical Field
The present invention relates to the field of diffractive optical devices, and in particular, to a light transmission structure and a head-mounted display device.
Background
AR (Augmented Reality ) display is a technique that calculates the position and angle of camera images in real time and adds corresponding image, video, 3d models, the goal of which is to fit the virtual world around the real world and interact on the screen.
AR displays are typically viewed by the human eye after incident light is emitted from an image source and passed through an optical waveguide. For better viewing of the presented image by the human eye, the exit pupil of the AR product is large enough, and it is known that the optical waveguide usually has three or more grating areas, such as light in-coupling, light out-pupil, light out-coupling, etc., which are devices capable of expanding the pupil.
However, in the existing optical transmission structure, three functional areas of optical coupling-in, optical pupil expansion and optical coupling-out are independently distributed, only a small part of the coupled area is occupied by the whole optical waveguide, and the light propagation is unidirectionally asymmetric, so that the displayed image is asymmetric in brightness.
Disclosure of Invention
Based on this, it is necessary to provide a light transmission structure and a head-mounted display device, which have pupil expansion and coupling-out functions by providing at least two one-dimensional gratings and receive light of at least two coupling-in gratings, so as to achieve a compact light transmission structure by reducing the occupation area of the light transmission structure while enlarging the area where a human eye can observe a complete image.
In order to achieve the above object, the present invention provides an optical transmission structure comprising:
a substrate;
at least two coupling-in gratings, wherein the at least two coupling-in gratings are arranged on one surface of the substrate at intervals; a kind of electronic device with high-pressure air-conditioning system
At least two coupling-out gratings, wherein the at least two coupling-out gratings are arranged on any surface of the substrate, and the projections of the at least two coupling-out gratings on the substrate are arranged side by side and are positioned on the same side of the two coupling-in gratings;
the light received by at least two coupling-in gratings is respectively emitted to at least two coupling-out gratings after passing through the substrate, wherein the light is emitted after passing through one coupling-out grating and then passing through the other coupling-out grating.
Optionally, two coupling-in gratings and two coupling-out gratings are provided, and the two coupling-in gratings are located at two sides of a perpendicular bisector in the connecting line direction of the two coupling-out gratings.
Optionally, the vector directions of the two coupling-in gratings are the same, and the sum of vectors of the two coupling-out gratings and the grating vectors of the two coupling-in gratings in the vector direction space is 0.
Optionally, the coupling-out grating is a one-dimensional grating, the two coupling-out gratings are arranged on the same surface of the substrate, and two edges of the two coupling-out gratings are abutted;
the period lengths of the two coupling-out gratings are the same;
and/or the grating vector directions of the two coupled gratings are symmetrically arranged by taking the abutted edges as axes.
Optionally, the coupling-out grating is a one-dimensional grating, the two coupling-out gratings are respectively arranged on two surfaces of the substrate, and projection parts of the two coupling-out gratings on the substrate are overlapped.
Optionally, the period lengths of the two coupling-in gratings are the same, and are set to be T1, the period lengths of the two coupling-out gratings are the same, and are set to be T2, and then T1 is not equal to T2, and both T1 and T2 are greater than or equal to 200nm and less than or equal to 600nm.
Optionally, the vector direction included angle between each coupling-out grating and one coupling-in grating ranges from 30 degrees to 70 degrees.
Optionally, the coupling-out gratings are two-dimensional gratings, and the two coupling-out gratings are symmetrically arranged along the central axis of the substrate;
the period lengths of the two coupling-out gratings are the same.
Optionally, the number of the coupling-out gratings is four, two coupling-out gratings are respectively arranged on two opposite surfaces of the substrate, and the coupling-out gratings on two opposite surfaces of the substrate have the same structure.
Optionally, the coupling-out grating is provided with three;
the two coupling-out gratings are arranged on one surface of the substrate, and grating vector directions of the two coupling-out gratings arranged on the same surface are symmetrically arranged by taking edges of the two coupling-out gratings which are abutted against each other as axes;
the other coupling-out grating is arranged on the other surface of the substrate, and the grating vector direction of the coupling-out grating arranged on the other surface of the substrate is consistent with the grating vector direction of the coupling-in grating.
Optionally, the coupling-in grating is a surface relief grating, a liquid crystal polarization grating or a polymer body grating;
and/or the coupling-out grating is a surface relief grating, a liquid crystal polarization grating or a polymer grating.
In order to achieve the above object, the present invention further proposes a head-mounted display device comprising an image source and a light transmission structure as described above, the light transmission structure being located on the light exit side of the image source.
In the technical scheme provided by the invention, the light transmission structure comprises a substrate, at least two coupling-in gratings and at least two coupling-out gratings, wherein the at least two coupling-in gratings and the at least two coupling-out gratings are arranged on the substrate, and the two coupling-in gratings are arranged side by side and positioned on the same side of the two coupling-in gratings, so that the two coupling-in gratings can receive emergent light rays of the coupling-in gratings, and the coupling-in grating which is firstly injected can be used as a pupil expansion foundation of the coupling-in grating which is subsequently injected. Therefore, the two coupling-out gratings can emit imaging light after passing through the pupil expansion, the two-dimensional pupil expansion effect is realized, the effective image area is increased, and the size of the light transmission structure can be smaller when the image area with the same size is required. Meanwhile, the light is decoupled from at least two coupling-in gratings, so that the two coupling-out gratings can be shot in under the coupling-in light with multiple angles, the coupling-out areas are fully filled with the coupling-out light, and the brightness and uniformity of the image are improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to the structures shown in these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a transverse cross-sectional view of one embodiment of a light transmission structure of the present invention;
fig. 2 is a transverse cross-sectional view of another embodiment of the light transmission structure of the present invention;
FIG. 3 is a transverse cross-sectional view of yet another embodiment of the light transmission structure of the present invention;
FIG. 4 is a ray propagation diagram of the optical transmission structure shown in FIG. 1;
FIG. 5 is a front view of a further embodiment of the light transmission structure of the present invention;
FIG. 6 is a cross-sectional view of the two surfaces of the light transmitting structure of FIG. 5;
FIG. 7 is a cross-sectional view of two surfaces of an additional embodiment of a light transmission structure according to the present invention;
fig. 8 is a ray propagation route diagram of the optical transmission structure shown in fig. 7.
Reference numerals illustrate:
| reference numerals | Name of the name | Reference numerals | Name of the |
| 100 | Light transmission structure | 12 | A |
| 10 | |
20 | Coupling in grating |
| 11 | A |
30 | Coupling out grating |
The achievement of the objects, functional features and advantages of the present invention will be further described with reference to the accompanying drawings, in conjunction with the embodiments.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
It should be noted that all directional indicators (such as up, down, left, right, front, and rear … …) in the embodiments of the present invention are merely used to explain the relative positional relationship, movement, etc. between the components in a particular posture (as shown in the drawings), and if the particular posture is changed, the directional indicator is changed accordingly.
In addition, descriptions such as those related to "first," "second," and the like in the present invention are provided for descriptive purposes only, but rather should not be construed as indicating or implying a relative importance or implying that the number of technical features is indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present invention, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.
In the present invention, unless specifically stated and limited otherwise, the terms "connected," "affixed," and the like are to be construed broadly, and for example, "affixed" may be a fixed connection, a removable connection, or an integral body; can be mechanically or electrically connected; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.
In addition, the technical solutions of the embodiments of the present invention may be combined with each other, but it is necessary to be based on the fact that those skilled in the art can implement the technical solutions, and when the technical solutions are contradictory or cannot be implemented, the combination of the technical solutions should be considered as not existing, and not falling within the scope of protection claimed by the present invention.
In a conventional diffractive light transmission structure, an in-coupling grating and an out-coupling grating are generally arranged independently, and the out-coupling grating occupies only a small part and cannot realize pupil expansion of a two-dimensional image. When the distance is far, part of non-vertical light with a certain azimuth angle is incident to the coupling-in grating, then the non-vertical light is diffracted to one grating of the coupling-out area at a certain azimuth angle, and the light entering one grating is coupled out after passing through the other grating, so that the light can be coupled out only in one grating of the coupling-out area, and occupies half or a small part of the coupling-out area, finally, when the human eyes move and observe, the light with the angle of view cannot be observed in the other coupling-out area, and therefore, the light with certain angle cannot cover the whole coupling-out area during coupling-out, so that the corresponding Eyebox cannot be expanded in the direction. Therefore, the invention provides the light transmission structure, which has the functions of expanding the pupil and coupling out through at least two adjacent grating areas and is matched with at least two coupling-in gratings, so that the pupil expansion in the two-dimensional direction is realized, and the coupled-out light rays can be spread over the whole coupling-out area.
Referring to fig. 1 and 2, in an embodiment of the invention, an optical transmission structure 100 according to the present invention includes: the optical fiber array comprises a substrate 10, at least two coupling-in gratings 20 and at least two coupling-out gratings 30, wherein at least two coupling-in gratings 20 are arranged on one surface of the substrate 10 at intervals;
at least two out-coupling gratings 30 are disposed on any surface of the substrate 10, and the projections of the at least two out-coupling gratings 30 on the substrate 10 are disposed side by side and on the same side of the two in-coupling gratings 20;
the light received by at least two of the in-coupling gratings 20 is emitted to at least two of the out-coupling gratings 30 after passing through the substrate 10, wherein the light is emitted after passing through one of the out-coupling gratings 30 and then passing through another of the out-coupling gratings 30.
In this embodiment, the light transmission structure 100 is applied to the AR display field, for example, the light transmission structure 100 is applied to AR glasses, which may be an optical waveguide or other components capable of conducting light. The substrate 10, also referred to as a dielectric optical waveguide, is generally planar and has a coupling-in region for receiving incident light and a coupling-out region for projecting the incident light out of the coupling-in region, through which the incident light is incident, transmitted within the substrate 10, and exits the coupling-out region. Specifically, one surface of the substrate 10 is provided as a first surface 11, and the other surface is provided as a second surface 12. Of course, in other embodiments, the substrate 10 may be configured in a cylindrical shape, and may be designed according to the desired product. The material of the substrate 10 may be epoxy resin or other organic material, or may be inorganic material such as heavy flint glass, which is not limited herein.
It can be known that the transmission of the incident light in the substrate 10 needs to satisfy two conditions, namely, the light is emitted from the optically dense medium to the optically sparse medium, the refractive index of the medium inside the substrate 10 is greater than that of the medium outside, that is, the refractive index of the substrate 10 needs to be greater than 1 (the refractive index of air is 1); the other is that the incident angle of the light is larger than the critical angle.
For this purpose, the optical substrate 10 further includes a coupling-in grating 20, where the coupling-in grating 20 is disposed on the surface of the substrate 10 and located in the coupling-in region for coupling light into the substrate 10. The coupling-in grating 20 can change the incident angle of the incident light into the substrate 10, so that the incident angle is greater than or equal to the critical angle, and the light can be totally reflected in the substrate 10, thereby completing the transmission of the light. The incoupling grating 20 may be imprinted in the incoupling region as a separate optical element, or the structure of the incoupling grating 20 may be machined in the incoupling region of the substrate 10.
The out-coupling grating 30 is located in the out-coupling region, and similarly, the out-coupling grating 30 may be applied to the out-coupling region as an independent optical element, or the structure of the out-coupling grating 30 may be formed in the out-coupling region of the substrate 10. When the light beam coupled into the substrate 10 by the coupling-in grating 20 is emitted to the coupling-out grating 30, the incident angle is deflected again, for example, the incident angle is smaller than the critical angle of total reflection, and the incident light beam is transmitted to the substrate 10, so that the incident light beam exits to form a display image and is acquired by human eyes.
Here, at least two coupling-in gratings 20 are disposed at intervals, at least two coupling-in regions are disposed correspondingly, and one coupling-in grating 20 is located correspondingly in one coupling-in region. At the same time, at least two out-coupling gratings 30 are disposed, at least two out-coupling regions are disposed on the corresponding substrate 10, and the two out-coupling gratings 30 are disposed side by side and can receive the light transmitted by the in-coupling gratings 20 at the same time. Referring to fig. 3, at least two out-coupling gratings 30 may be disposed on the same surface of the substrate 10, or may be disposed on two opposite surfaces of the substrate 10, i.e., on the first surface 11 and the second surface 12, respectively. The at least two out-coupling gratings 30 are arranged side by side, and may be arranged at intervals in the projection of the substrate 10, or may be arranged in an abutting manner, or may be arranged in an overlapping manner, which is not limited herein. When the two out-coupling gratings 30 are overlapped, the two out-coupling gratings 30 can be respectively arranged on the first surface 11 and the second surface 12, so that the two out-coupling gratings are one-dimensional gratings, and the processing is convenient. And the two out-coupling gratings 30 and the two in-coupling gratings 20 are positioned on the same line in the direction along the in-coupling region to the out-coupling region. Of course, the two out-coupling gratings 30 may also be offset in the direction from the in-coupling region to the out-coupling region, and the spacing therebetween should not exceed 0.5mm. Alternatively, when both out-coupling gratings 30 are on the first surface 11 or the second surface 12, and both are arranged with an overlap, the overlap may be arranged as a two-dimensional grating or a two-dimensional photonic crystal.
On this basis, at least two in-coupling gratings 20 may also be located on the same surface of the substrate 10, or on opposite surfaces, which is not limited herein. The shapes of the coupling-out gratings 30 are not limited, and the cross-sectional shapes thereof may be rectangular or square, etc., and the shapes of at least two coupling-out gratings 30 may be the same or different, and of course, microstructures for changing the incident angle of light are disposed on the surfaces of the coupling-out gratings 30, such as the arrangement of grating lines in the drawings, which is not described herein. The shape of the coupling-in grating 20 is not limited, and the cross-sectional shape thereof may be circular or rectangular or irregular, etc. Of course, when the coupling-in grating 20 is closer to the light machine, the cross-sectional shape of the coupling-in grating 20 may be set to be circular, which matches the shape of the light machine exit cylinder, so as to be able to better receive light. Of course, the coupling-in grating 20 is composed of a plurality of micro-optical structures arranged in an array, such as grating lines in the figure, so as to deflect the incident angle of the incident light. Whereas the cross-sectional shape of the coupling-in grating 20 may be set to be rectangular or circular when the coupling-in grating 20 is at a large distance from the light engine.
Referring to fig. 4, since at least two in-coupling gratings 20 are disposed, the amount of in-coupling light can be increased in the arrangement direction of at least two out-coupling gratings 30, and even light deviated from the direction of the perpendicular bisector between the two out-coupling gratings 30 can be injected into the two out-coupling gratings 30, so as to achieve the effects of both pupil expansion and out-coupling light. Taking two coupling-in gratings 20 and two coupling-out gratings 30 as an example, after the incident light is coupled into the substrate 10 by the two coupling-in gratings 20, the incident light is transmitted to the position of the coupling-out gratings 30 through total reflection of the substrate 10, after the grating directions of the two coupling-out gratings 30 are designed, namely, the grating vector directions are perpendicular to the grating line directions, the light 1001 entering one coupling-out grating 30 first passes through pupil expansion and turning and then enters the other coupling-out grating 30, namely, the light 1001 can generate the diffracted light 1002 towards the other coupling-out grating 30, and the light 1002 continuously propagates along the original direction, the light 1002 finishes pupil expansion in the coupling-out grating 30 and generates the coupled-out light 1003 reaches human eyes, and the light 1001 continuously propagating along the original direction can generate the diffracted light 1004 again, and the path of the diffracted light 1004 is the same as that of the diffracted light 1002, and finally the light is coupled out by the other coupling-out grating 30. Similarly, light that enters the other out-coupling grating 30 will be emitted as described above. The light rays can generate new light rays after passing through the pupil expansion, the new light rays can continue to propagate and expand the pupil and circulate continuously, and the final image fills the whole exit pupil after expanding the pupil, so that the human eyes can see the image in a large area, and the display effect is improved.
In the technical solution provided in the present invention, the optical transmission structure 100 includes a substrate 10, at least two in-coupling gratings 20 and at least two out-coupling gratings 30 disposed on the substrate 10, and by disposing two out-coupling gratings 30 disposed in parallel and on the same side of the two in-coupling gratings 20, both of the two in-coupling gratings can receive the outgoing light of the in-coupling gratings 20, and the first-incident in-coupling grating 20 can be used as the pupil expanding base of the last-incident in-coupling grating 20. In this way, the two coupling-out gratings 30 can both emit imaging light after passing through the pupil expansion, so as to realize a two-dimensional pupil expansion effect, increase the effective image area, and reduce the size of the light transmission structure 100 when the image area with the same size is required. Meanwhile, the decoupling light rays by the at least two coupling-in gratings 20 can ensure that the two coupling-out gratings 30 can be shot under the coupling-in light rays with multiple angles, so that the coupling-out light rays are ensured to be full of the coupling-out areas, the longitudinal area of the image which can be completely observed by human eyes is improved, and the brightness and uniformity of the image are improved.
With continued reference to fig. 1, alternatively, two coupling-in gratings 20 and two coupling-out gratings 30 are provided, and the two coupling-in gratings 20 are located at two sides of a perpendicular bisector in the connecting direction of the two coupling-out gratings 30.
In this embodiment, the two coupling-in gratings 20 are disposed at two sides of the perpendicular bisectors in the arrangement direction of the two coupling-out gratings 30, so that the probability that the light coupled by the two coupling-in gratings 20 is emitted to the two coupling-out gratings 30 is approximately equal, and each coupling-out grating 30 is guaranteed to have light entering, so that pupil expansion and coupling-out light are generated, the brightness of the light emitted from each coupling-out grating 30 is the same, and the brightness of the image observed by human eyes is symmetrically distributed, so that the display effect is further improved. Here, the distance between the two in-gratings 20 and the out-grating 30 on the corresponding side is not limited, and may be the same or different. And preferably, the two coupling-in gratings 20 can be symmetrically arranged by taking the perpendicular bisectors on the connecting lines of the two coupling-out gratings 30 as axes, so that the uniformity of the coupling-in light is further improved, and the two-dimensional pupil expansion and coupling-out effects are ensured.
Specifically, the cross section of each coupling-out grating 30 is rectangular, the length direction of each coupling-out grating 30 is consistent with the direction from the coupling-in grating 20 to the coupling-out grating 30, and the two coupling-out gratings 30 are arranged side by side in the width direction, so that the area of the substrate 10 can be fully utilized, and the utilization rate is improved.
Optionally, the vector directions of the two coupling-in gratings 20 are the same, and the sum of vectors of the two coupling-out gratings 30 and the grating vectors of the two coupling-in gratings 20 in the vector direction space is 0.
It will be appreciated that in order to make the light rays all incident towards the out-coupling grating 30, the grating vectors of the two in-coupling gratings 20 are set to be the same, so that light rays with substantially the same incident angle are obtained. Here, the direction of the grating vectors of the two in-coupling gratings 20 is set to be perpendicular to the arrangement direction of the two out-coupling gratings 30, so that the uniformity of light rays emitted to the two out-coupling gratings 30 can be further ensured, and the display area of the image in the longitudinal direction can be further improved.
In addition, in order to make the incident angle the same as the outgoing angle of the coupled light, the sum of the vector directions of the coupled grating 20 and the vector directions of the two coupled gratings 30 in the vector direction space is required to be 0, that is, the vector of the coupled grating 20 and the vector of the two coupled gratings 30 can form a closed triangle, so that the image display direction is conveniently designed for the user to watch.
Optionally, the coupling-out gratings 30 are one-dimensional gratings, the two coupling-out gratings 30 are disposed on the same surface of the substrate 10, and two edges of the two coupling-out gratings 30 are abutted;
the period lengths of the two coupling-out gratings 30 are the same;
and/or, the grating vector directions of the two coupling gratings 30 are symmetrically arranged with the abutting edges as axes.
In this embodiment, the cross-sectional shape of the coupling-out grating 30 may be set to be rectangular, which is convenient for processing. Specifically, the two coupling-out gratings 30 are all one-dimensional gratings and are distributed on the same surface, and the edges of the two coupling-out gratings are abutted, so that the one-dimensional grating structure is simpler and is convenient to process, and the occupation of the surface area of the substrate 10 can be further reduced, the size of the light transmission structure 100 is reduced, and the surface utilization rate of the substrate 10 is improved through the adjacent arrangement of the two coupling-out gratings; and after the incident light is transmitted to the coupling-out grating 30, the space for propagating and expanding the pupil to the right is larger, so that a coupling-out image area with a larger size is realized, and further, a more compact light transmission structure 100 is realized. Optionally, the cycle length of each coupling-out grating 30 is set to be the same, and the grating vector directions of the two coupling-out gratings 30 are symmetrically arranged by taking the abutting edges of the two coupling-out gratings as axes, so that on one hand, the processing is convenient, and the processing efficiency is improved; on the other hand, the directions and the amounts of the light rays which are subjected to pupil expansion and coupling out are approximately the same, so that the uniformity of the brightness of the output image is ensured. Here, the grating vector of each out-coupling grating 30 is gradually close to the other out-coupling grating 30 in the direction from the in-coupling grating 20 to the out-coupling grating 30, so that the light entering the out-coupling grating 30 can be diffracted into the other out-coupling grating 30, the effect of pupil expansion and out-coupling is achieved, and the grating vectors of the two are symmetrically arranged.
Of course, in other embodiments, the period lengths of the two out-coupling gratings 30 may be the same, or the grating vector directions of the two out-coupling gratings 30 may be symmetrical with the abutting edges thereof as the axis.
In addition, the cross section of the coupling-out grating 30 can be set to be a trapezoid-rectangular combination, that is, the original rectangle is cut off to form a figure after one vertex angle is cut off, and the cut vertex angle needs to face the coupling-in grating 20 and deviate from the other coupling-out grating 30, so that a bevel edge is formed, thus, incident light can be subjected to pupil expansion when entering the coupling-out grating 30, unnecessary light energy loss at the square vertex angle can be reduced, the light utilization rate is improved, and the use of grating materials is reduced.
In other embodiments, the coupling-out grating 30 is a one-dimensional grating, the two coupling-out gratings 30 are respectively disposed on two surfaces of the substrate 10, and projection portions of the two coupling-out gratings 30 on the substrate 10 are overlapped. The arrangement of the structure can effectively reduce the processing difficulty compared with the two-dimensional grating, so that the processing cost is reduced. And the two out-coupling gratings 30 are partially overlapped on both surfaces, the out-coupling can be achieved by one total reflection, thereby increasing the out-coupling density.
Optionally, the coupling-out gratings 30 are two-dimensional gratings, and the two coupling-out gratings 30 are symmetrically arranged along the central axis of the substrate 10, and the period lengths of the two coupling-out gratings 30 are the same. Alternatively, the two out-coupling gratings 30 may be two-dimensional gratings of unitary construction. The structure can effectively improve the coupling-out efficiency and increase the stability of the structure.
Optionally, the period lengths of the two coupling-in gratings 20 are the same, and are set to be T1, the period lengths of the two coupling-out gratings 30 are the same, and are set to be T2, and then T1 is not equal to T2, and both T1 and T2 are greater than or equal to 200nm and less than or equal to 600nm.
It can be appreciated that when the period of the grating is too small, the processing is not facilitated, and of course, when the period is too large, the density of the coupled light is smaller, which is not beneficial to the display of the image. Therefore, the period ranges of the coupling-in grating 20 and the coupling-out grating 30 are set to be more than or equal to 200nm and less than or equal to 600nm, for example, 200nm, 300nm, 400nm, 500nm, 600nm and the like, so that the processing technology is ensured, and the image display is improved.
Optionally, each of the coupling-out gratings 30 has an angle ranging from 30 ° to 70 ° with respect to the vector direction of one of the coupling-in gratings 20.
In this embodiment, when the angle between the coupling-out grating 30 and the vector direction of the coupling-in grating 20 is too small, reflection of light occurs, which is not beneficial to pupil expansion coupling-out; when the included angle is too large, the vectors of the coupling-in grating 20 and the two coupling-out gratings 30 cannot form a closed shape, which is not beneficial to the adjustment of the light angle, so that the included angle range of the coupling-out grating 30 and the vector direction of the coupling-in grating 20 is set to be 30-70 degrees, for example, 30 degrees, 40 degrees, 50 degrees, 60 degrees, 70 degrees, etc., so as to ensure the smooth coupling-out of the light.
Referring to fig. 5 and 6, alternatively, four out-coupling gratings 30 are provided, two out-coupling gratings 30 are respectively provided on two opposite surfaces of the substrate 10, and the out-coupling gratings 30 on two opposite surfaces of the substrate 10 have the same structure.
In this embodiment, in order to further increase the density of the coupled light, two coupling-out gratings 30 at the above positions are disposed on the first surface 11, and two coupling-out gratings 30 identical to the first surface 11 are disposed on the second surface 12, so that when the coupled light is incident into the coupling-out gratings 30, the number of times of diffraction of the light is increased, and the light is coupled out through both the first surface 11 and the second surface 12, i.e. the light can be coupled out by one total reflection, thereby effectively increasing the pupil expansion density.
Referring to fig. 7 and 8, in order to increase the coupling-out density, the coupling-out grating 30 is optionally provided with three; wherein, the two coupling-out gratings 30 are arranged on one surface of the substrate 10, and the grating vector directions of the two coupling-out gratings 30 arranged on the same surface are symmetrically arranged by taking the abutting edges of the two coupling-out gratings as axes; the other coupling-out grating 30 is disposed on the other surface of the substrate 10, and the direction of the grating vector of the coupling-out grating 30 disposed on the other surface of the substrate 10 is consistent with the direction of the grating vector of the coupling-in grating 20.
In this embodiment, the coupling-out grating 30 of the second surface 12 is set to be one, the vector direction of the coupling-out grating 30 is the same as the direction of the coupling-in grating 20, and the periods of the two coupling-out gratings 30 of the first surface 11 are the same and the vector directions are symmetrically set, so that, after the coupling-in grating 20 receives light, the coupling-in grating is coupled into the substrate 10, the diffracted light 2001 of the first surface 11 is generated, when the light is incident to one of the coupling-out gratings 30, the diffracted light 2002 of the other coupling-out grating 30 is generated, and continues to propagate forward, when the 2002 is incident to the coupling-out grating 30 again, the diffracted light 2003 and the diffracted light 2005 of the 2001 are generated when the diffracted light is incident to the coupling-out grating 30 of the second surface 12, and finally, the coupled-out light of one of the coupling-in gratings 20 will spread over the whole coupling-out grating 30, and under the condition of the two coupling-in gratings 20, the coupling-out grating 30 can be further enhanced, the brightness of the emergent image can be further enhanced, and the uniformity of the brightness of the image can be ensured.
Optionally, the incoupling grating 20 is a surface relief grating, a liquid crystal polarization grating or a polymer body grating;
and/or the out-coupling grating 30 is a surface relief grating, a liquid crystal polarization grating, a polymer grating.
In this embodiment, the coupling-in grating 20 may be a surface relief grating, which has a larger refractive index difference than air, so that the light beam can obtain a larger deflection angle, thereby more facilitating the design of the incident angle of the light transmission structure 100. Of course, in other embodiments, the coupling-in grating 20 may be a liquid crystal polarization grating or a polymer grating, etc.
Alternatively, when the coupling-in grating 20 is any one of the gratings, the coupling-out grating 30 may be a surface relief grating, so that the angle of the coupled light can be conveniently adjusted, and the image display area can be more conveniently designed. Of course, in other embodiments, the coupling-out grating 30 may be a liquid crystal polarization grating or a polymer grating.
In order to achieve the above object, the present invention further proposes a head-mounted display device (not shown) comprising an image source and a light transmission structure 100 as described above, the light transmission structure 100 being located on the light exit side of the image source. Since the light transmission structure 100 of the head-mounted display device of the present invention refers to the structure of the light transmission structure 100 of the above embodiment, the beneficial effects brought by the above embodiment are not described again.
In this embodiment, the head-mounted display device may be AR glasses or MR glasses, which includes an image source that provides incident light to the light transmission structure 100, and when the incident light is incident to the light transmission structure 100 from an air medium, the incident light is first diffracted by the coupling-in grating 20, then enters the substrate 10, is transmitted through total reflection, then passes through the coupling-out grating 30, and is injected into the human eye. Of course, the head-mounted display device may also be a near-eye display (NED), head-mounted display (HMD), head-up display (HUD), or the like.
In an embodiment, in order to receive the image source as much as possible, the coupling-in grating 20 is disposed opposite to the image source, that is, the image source coincides with the projection of the coupling-in grating 20 on the substrate 10, so that it can be ensured that the incident light is received by the coupling-in grating 20, and the light transmission efficiency is improved.
Optionally, the image source includes a light source and a display panel, where the light source is optionally an LED light source, which provides a light source for the display panel, and incident light is formed through the display panel and directed to the light transmission structure 100. The display panel may be one of a Liquid Crystal On Silicon (LCOS) display module (Liquid Crystal on Silicon), a transmissive liquid crystal display module (LCD), a digital light processing (digital Light Processing, DLP) display module, and a laser scan (Laser Beam Scanning, LBS).
The foregoing description of the preferred embodiments of the present invention should not be construed as limiting the scope of the invention, but rather should be understood to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the following description and drawings or any application directly or indirectly to other relevant art(s).
Claims (12)
1. An optical transmission structure, the optical transmission structure comprising:
a substrate;
at least two coupling-in gratings, wherein the at least two coupling-in gratings are arranged on one surface of the substrate at intervals; a kind of electronic device with high-pressure air-conditioning system
At least two coupling-out gratings, wherein the at least two coupling-out gratings are arranged on any surface of the substrate, and the projections of the at least two coupling-out gratings on the substrate are arranged side by side and are positioned on the same side of the two coupling-in gratings;
the light received by at least two coupling-in gratings is respectively emitted to at least two coupling-out gratings after passing through the substrate, wherein the light is emitted after passing through one coupling-out grating and then another coupling-out grating.
2. The optical transmission structure of claim 1, wherein two coupling-in gratings and two coupling-out gratings are arranged on two sides of a perpendicular bisector in the connecting line direction of the two coupling-out gratings.
3. The optical transmission structure of claim 2, wherein the vector directions of the two in-coupling gratings are the same, and the sum of vectors of the two out-coupling gratings and the grating vectors of the two in-coupling gratings in the vector direction space is 0.
4. The optical transmission structure of claim 3, wherein the coupling-out grating is a one-dimensional grating, the two coupling-out gratings are arranged on the same surface of the substrate, and two edges of the two coupling-out gratings are abutted;
the period lengths of the two coupling-out gratings are the same;
and/or the grating vector directions of the two coupled gratings are symmetrically arranged by taking the abutted edges as axes.
5. The optical transmission structure of claim 3, wherein the out-coupling grating is a one-dimensional grating, the two out-coupling gratings are respectively disposed on two surfaces of the substrate, and projection portions of the two out-coupling gratings on the substrate are coincident.
6. The optical transmission structure of claim 4 or 5, wherein the period lengths of the two coupling-in gratings are the same, and are set to be T1, the period lengths of the two coupling-out gratings are the same, and are set to be T2, and then T1 is not equal to T2, and both T1 and T2 are equal to or greater than 200nm and equal to or less than 600nm.
7. The optical transmission structure of claim 4 or 5, wherein each of the out-coupling gratings is oriented at an angle in the range of 30 ° to 70 ° to the vector direction of an in-coupling grating.
8. The optical transmission structure of claim 2, wherein the out-coupling grating is a two-dimensional grating, and the two out-coupling gratings are symmetrically arranged along a central axis of the substrate;
the period lengths of the two coupling-out gratings are the same.
9. The optical transmission structure of claim 1, wherein the number of the coupling-out gratings is four, two coupling-out gratings are respectively arranged on two opposite surfaces of the substrate, and the coupling-out gratings on two opposite surfaces of the substrate have the same structure.
10. The light-transmitting structure of claim 1, wherein the out-coupling grating is provided with three;
the two coupling-out gratings are arranged on one surface of the substrate, and grating vector directions of the two coupling-out gratings arranged on the same surface are symmetrically arranged by taking edges of the two coupling-out gratings which are abutted against each other as axes;
the other coupling-out grating is arranged on the other surface of the substrate, and the grating vector direction of the coupling-out grating arranged on the other surface of the substrate is consistent with the grating vector direction of the coupling-in grating.
11. The light transmission structure of claim 1, wherein the incoupling grating is a surface relief grating, a liquid crystal polarization grating, or a polymer body grating;
and/or the coupling-out grating is a surface relief grating, a liquid crystal polarization grating or a polymer grating.
12. A head mounted display device comprising an image source and a light transmitting structure according to any one of claims 1 to 11, the light transmitting structure being located on the light exit side of the image source.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111618571.8A CN116400502A (en) | 2021-12-27 | 2021-12-27 | Light transmission structure and head-mounted display device |
| PCT/CN2022/100331 WO2023123920A1 (en) | 2021-12-27 | 2022-06-22 | Optical transmission structure and head-mounted display device |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202111618571.8A CN116400502A (en) | 2021-12-27 | 2021-12-27 | Light transmission structure and head-mounted display device |
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| EP3339936A1 (en) * | 2016-12-20 | 2018-06-27 | Oculus VR, LLC | Waveguide display with a small form factor, a large field of view and a large eyebox |
| CN109459813A (en) * | 2018-12-26 | 2019-03-12 | 上海鲲游光电科技有限公司 | A kind of planar optical waveguide based on two-dimensional grating |
| US11428938B2 (en) * | 2019-12-23 | 2022-08-30 | Meta Platforms Technologies, Llc | Switchable diffractive optical element and waveguide containing the same |
| CN213690119U (en) * | 2020-12-17 | 2021-07-13 | 苏州苏大维格科技集团股份有限公司 | Optical pupil expanding waveguide sheet and display device |
| CN113495319A (en) * | 2021-07-30 | 2021-10-12 | Oppo广东移动通信有限公司 | Optical structure and optical device |
| CN113534328A (en) * | 2021-09-02 | 2021-10-22 | 浙江水晶光电科技股份有限公司 | Augmented reality diffraction optical waveguide and augmented reality display device |
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