CN116400501A - Light transmission structure and head-mounted display device - Google Patents
Light transmission structure and head-mounted display device Download PDFInfo
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- CN116400501A CN116400501A CN202111618570.3A CN202111618570A CN116400501A CN 116400501 A CN116400501 A CN 116400501A CN 202111618570 A CN202111618570 A CN 202111618570A CN 116400501 A CN116400501 A CN 116400501A
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- G—PHYSICS
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- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/01—Head-up displays
- G02B27/017—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
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Abstract
The invention discloses a light transmission structure and head-mounted display equipment, wherein the light transmission structure comprises a substrate, a coupling-in grating, a coupling-out grating and two pupil-expanding gratings, wherein the coupling-in grating is arranged on the surface of the substrate; the coupling-out grating is arranged on the surface of the substrate; the two pupil expansion gratings are arranged between the coupling-in grating and the coupling-out grating and are arranged side by side in the direction perpendicular to the coupling-in grating and the coupling-out grating; light rays coupled out of the coupling-in grating are all directed to the two pupil expansion gratings, the two pupil expansion gratings respectively expand pupils of the light rays and then are directed to the coupling-out grating, and the light rays in the coupling-out grating are emitted after being expanded pupils. The light transmission structure of the technical scheme of the invention provides a novel pupil expansion mode, can conveniently hide the pupil expansion grating, ensures an image display area and improves viewing experience.
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. It is known that an optical waveguide generally has three or more grating regions, such as a functional region of light in-coupling, pupil expanding, light out-coupling, etc., and is a device capable of expanding the pupil. However, in the existing light transmission structure, the size of the pupil is larger, and the distance between the pupil and the light coupling-out area is required to be smaller, so that the occupied area of the imaging area is small, and the external light is also greatly influenced, which is not beneficial to the watching experience of users.
Disclosure of Invention
Based on this, it is necessary to provide a light transmission structure and a head-mounted display device, which aims to provide a brand new pupil expansion mode, so as to better hide the pupil expansion area, reduce the interference on the incident light, and improve the viewing experience of the user.
In order to achieve the above object, the present invention provides an optical transmission structure comprising:
a substrate;
the coupling grating is arranged on the surface of the substrate;
the coupling-out grating is arranged on the surface of the substrate; and
The two pupil expansion gratings are arranged between the coupling-in grating and the coupling-out grating and are arranged side by side in the direction perpendicular to the coupling-in grating to the coupling-out grating;
light rays coupled out of the coupling-in grating are all directed to the two pupil expansion gratings, the two pupil expansion gratings respectively expand pupils of the light rays and then are directed to the coupling-out grating, and the light rays in the coupling-out grating are emitted to form images after being expanded pupils.
Optionally, the two pupil expansion gratings are one-dimensional gratings and are arranged on the same surface of the substrate, and two opposite edges of the two pupil expansion gratings are in butt joint.
Optionally, the pupil expansion grating is a one-dimensional grating, the two pupil expansion gratings are respectively arranged on two surfaces of the substrate, and projection parts of the two pupil expansion gratings on the substrate are overlapped.
Optionally, the coupling grating is located on a midpoint line in the arrangement direction of the two pupil expansion gratings.
Optionally, the grating vectors of the coupling-in grating and the coupling-out grating have the same direction, and the period lengths of the coupling-in grating and the coupling-out grating are the same, and the sum of vectors of the two pupil expansion gratings and the grating vectors of the coupling-in grating in a vector direction space is 0;
and/or the sum of vectors of the two pupil expansion gratings and the grating vector of the coupling grating in vector direction space is 0.
Optionally, the period lengths of the two pupil expansion gratings are the same, the grating vector directions of the two coupling gratings are symmetrically arranged by taking the edge where the two coupling gratings are abutted against each other as an axis, the two pupil expansion gratings are all provided with pupils in a first direction, one pupil expansion grating is provided with a pupil expansion in a second direction, the other pupil expansion grating is provided with a pupil expansion in a direction deviating from the second direction, and the first direction and the second direction form an included angle.
Optionally, the period lengths of the coupling-in grating and the pupil expanding grating are different, and the period lengths of the coupling-in grating and the coupling-out grating are T1, so that T1 is greater than or equal to 200nm and less than or equal to 600nm;
and/or, if the period length of the pupil expanding grating is T2, T2 is more than or equal to 200nm and less than or equal to 600nm.
Optionally, the included angle between the pupil expansion grating and the vector direction of the coupling-in grating is in a range of 30-70 degrees.
Optionally, the two pupil expansion gratings are two-dimensional gratings, and are symmetrically arranged along the central axis of the substrate, and the cycle lengths of the two pupil expansion gratings are the same;
or two pupil-expanding gratings are two-dimensional gratings or two-dimensional photonic crystals with integrated structures.
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 body grating;
and/or the pupil expanding grating is a surface relief grating, a liquid crystal polarization grating or a polymer object 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, and a coupling-in grating, two pupil expansion gratings and a coupling-out grating which are arranged on the substrate, wherein the two pupil expansion gratings are arranged on the light outlet side of the coupling-in grating side by side, so that the two pupil expansion gratings can both receive light coupled in by the coupling-in grating, and the two pupil expansion gratings directly shoot to the coupling-out grating on the rear side after pupil expansion, and the coupling-out grating can couple out light after pupil expansion. In this structure, since the two pupil expansion gratings perform pupil expansion simultaneously, the pupil expansion effect can be enhanced, and the two-dimensional pupil expansion effect in the arrangement direction and the rear side direction can be realized, and the display image area can be enlarged. Meanwhile, the structure can increase the distance between the pupil expansion grating and the coupling-out grating, so that the coupling-in grating and the pupil expansion grating can be conveniently hidden, the area of the coupling-out grating for viewing is reserved, and the occupied area of the coupling-out area is increased; and when external light enters the light transmission structure, the light is not influenced by the pupil expansion grating, so that the interference on the display surface is reduced, and the viewing experience is 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 ray propagation diagram of the optical transmission structure shown in FIG. 1;
fig. 3 is a transverse cross-sectional view of another embodiment of the light transmission structure of the present invention.
Reference numerals illustrate:
| reference numerals | Name of the name | Reference numerals | Name of the |
| 100 | |
30 | Coupling out grating |
| 10 | |
40 | Pupil expanding grating |
| 20 | Coupling in 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.
Furthermore, descriptions such as those referred to as "first," "second," and the like, are provided for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implying an order of magnitude of the indicated technical features in the present disclosure. 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.
Referring to fig. 1 and 2, in an embodiment of the invention, a light transmission structure 100 includes a substrate 10, an in-coupling grating 20, an out-coupling grating 30, and two pupil expansion gratings 40, wherein the in-coupling grating 20 is disposed on a surface of the substrate 10; the coupling-out grating 30 is disposed on the surface of the substrate 10; the two pupil expansion gratings 40 are arranged between the coupling-in grating 20 and the coupling-out grating 30, and are arranged side by side in a direction perpendicular to the coupling-in grating 20 to the coupling-out grating 30;
the light rays coupled out of the coupling-in grating 20 are all directed to the two pupil expansion gratings 40, the two pupil expansion gratings 40 respectively expand the pupils of the light rays and then are directed to the coupling-out grating 30, and the light rays in the coupling-out grating 30 are subjected to pupil expansion and then are emitted for imaging.
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, and the light transmission structure 100 may be an optical waveguide or other components for implementing light conduction. 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 set as a first surface, and the other surface is set as a second surface. 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.
Meanwhile, the optical system further comprises a pupil expansion grating 40 and an out-coupling grating 30, wherein the out-coupling grating 30 is positioned in the out-coupling region, and the pupil expansion grating 40 is used for expanding pupils of the coupled light, so that the output light with a larger range is emitted to the out-coupling grating 30, and the area of the out-coupling image is increased. Similarly, the coupling-out grating 30 and the pupil-expanding grating 40 may be attached to the substrate 10 as separate optical elements, or may be directly formed on the substrate 10. When the light rays expanded by the pupil expansion grating 40 are directed 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 rays are transmitted to the substrate 10, so that the emergent light rays form a display image to be acquired by human eyes.
Referring to fig. 1 and 3, two pupil expansion gratings 40 are disposed, and the two pupil expansion gratings 40 are disposed side by side, and the side by side direction is perpendicular to the direction from the coupling-in grating 20 to the coupling-out grating 30, so that the light transmitted by the coupling-in grating 20 can be received at the same time, and the light after pupil expansion is all injected into the coupling-out grating 30. The two pupil-expanding gratings 40 may be located on the same surface of the substrate 10, or may be located on two opposite surfaces of the substrate 10, i.e. on the first surface and the second surface, respectively. The two pupil expansion gratings 40 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. Optionally, the pupil expansion grating 40 is a one-dimensional grating, the two pupil expansion gratings 40 are respectively disposed on two surfaces of the substrate 10, and projection portions of the two pupil expansion gratings 40 on the substrate 10 are overlapped. When the two pupil expansion gratings 40 are overlapped, they can be respectively arranged on the first surface and the second surface, so that the two pupil expansion gratings are one-dimensional gratings, and the processing is convenient. And the two mydriatic gratings 40 are positioned on the same straight line in the direction along the coupling-in area to the coupling-out area. Of course, the two pupil-expanding gratings 40 may also be arranged offset in the direction along the coupling-in region to the coupling-out region, and the spacing therebetween should not exceed 0.5mm. Alternatively, when both the pupil-expanding gratings 40 are on the first surface or the second surface and there is a partial overlap between them, the overlapping portion may be set as a two-dimensional grating or a two-dimensional photonic crystal.
The shape of the coupling-out grating 30 is not limited, and the cross-section shape thereof may be cuboid or cube, of course, a microstructure for changing the incident angle of the light is provided on the surface of the coupling-out grating 30, such as the arrangement of grating lines in the drawings, which will not be 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-light structures arranged in an array, such as the coupling-in grating 20 lines in the figure, so as to deflect the incident angle of the incident light.
Referring to fig. 2, after an incident light is coupled into the substrate 10 by the coupling-in grating 20, the incident light is transmitted to the two pupil expansion gratings 40 through total reflection of the substrate 10, after the grating directions of the two pupil expansion gratings 40 are designed, that is, the grating vector direction is perpendicular to the grating line direction, the 1001 light generates an upward-propagating diffracted light 1002 and a light continuously propagating along the original direction when entering one of the pupil expansion gratings 40, the 1002 light is again incident into the pupil expansion grating 40, and the diffracted light 1003 is generated, and the diffracted direction is the same as the diffracted light 1001, and the 1002 continuously propagates along the original direction, thereby completing pupil expansion in the upper half. When light such as 1001 and 1003 is incident on the out-coupling grating 30, the out-coupled diffracted light 1004 is generated while continuing to propagate forward. All of the outcoupled light will cover the upper half area of the outcoupling grating 30. The light entering the other mydriatic grating 40 via the coupling-in grating 20 behaves like the above-mentioned mydriatic grating 40, assuming a symmetrical state, and the coupling-out light will cover the lower half area of the coupling-out grating 30. Finally, through the two-dimensional pupil expansion of the two pupil expansion gratings 40, the light rays are paved in the coupling-out area watched by human eyes, and the display effect is improved.
In the technical solution provided in the present invention, the light transmission structure 100 includes a substrate 10, and a coupling-in grating 20, two pupil expansion gratings 40 and a coupling-out grating 30 disposed on the substrate 10, where the two pupil expansion gratings 40 are disposed side by side on the light-emitting side of the coupling-in grating 20, so that both can receive the light coupled in by the coupling-in grating 20, and the two pupil expansion gratings 40 directly shoot to the coupling-out grating 30 on the rear side after pupil expansion, and the coupling-out grating 30 can couple out the light after pupil expansion. In this structure, since the two pupil-expanding gratings 40 simultaneously perform pupil expansion, the pupil-expanding effect can be enhanced, and the two-dimensional pupil-expanding effect in the arrangement direction and the rear side direction can be realized, and the display image area can be increased. Meanwhile, the distance between the coupling-in grating 20 and the coupling-out grating 40 can be increased by the structure, and the coupling-in grating 20 and the coupling-out grating 40 can be conveniently hidden, for example, the coupling-in grating 20 and the coupling-out grating 40 are wrapped by using the glasses legs, the area of the coupling-out grating 30 for viewing is reserved, and the area occupied by the coupling-out area in the lens is increased; and when external light enters the light transmission structure 100, the external light is not affected by the pupil expansion grating 40, so that the interference on the display surface is reduced, and the viewing experience is improved.
With continued reference to fig. 1, alternatively, the two pupil expansion gratings 40 are one-dimensional gratings and are disposed on the same surface of the substrate 10, and two opposite edges of the two pupil expansion gratings 40 are disposed in contact with each other.
Here, the cross-sectional shape of the pupil-expanding grating 40 may be set to be rectangular, facilitating processing. Specifically, the two pupil expansion gratings 40 are all one-dimensional gratings and are distributed on the same surface of the substrate 10, and edges of the two gratings are abutted, so that the one-dimensional gratings are simpler in structure and 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 gratings.
Of course, in other embodiments, in order to improve the coupling-out efficiency, the two pupil expansion gratings 40 may be two-dimensional gratings, which are symmetrically arranged along the central axis of the substrate 10, and have the same period length; alternatively, the two pupil-expanding gratings 40 may be two-dimensional gratings or two-dimensional photonic crystals with integrated structures, so as to improve the stability of the structure.
Optionally, the coupling grating 20 is located on a midpoint line in the arrangement direction of the two pupil expansion gratings 40.
In this embodiment, the coupling-in gratings 20 are disposed on the middle vertical lines in the arrangement direction of the two pupil expansion gratings 40, so that the probability that the coupled light rays of the coupling-in gratings 20 are emitted to the two pupil expansion gratings 40 is equal, and the number and the brightness of the pupil expansion light rays emitted from each pupil expansion grating 40 are approximately the same, so that more uniform coupling-out light rays can be obtained, the brightness of the image observed by human eyes is symmetrically distributed, and the display effect is effectively improved.
Optionally, the grating vectors of the coupling-in grating 20 and the coupling-out grating 30 have the same direction, and the period lengths of the two are the same, and the sum of vectors of the two pupil expansion gratings 40 and the grating vector of the coupling-in grating 20 in the vector direction space is 0;
and/or, the sum of vectors of the two pupil expansion gratings 40 and the grating vector of the coupling-out grating 30 in the vector direction space is 0.
It will be appreciated that, in order to make the incident angle the same as the exit angle of the coupled light, the sum of the vectors of the vector direction of the coupled grating 20 and the vector direction of the two pupil expansion gratings 40 in the vector direction space is required to be 0, and the sum of the vectors of the vector direction of the two pupil expansion gratings 40 and the vector direction of the coupled grating 30 in the vector direction space is also required to be 0, that is, the vector of the coupled grating 20 and the vector of the two pupil expansion gratings 40 can form a closed triangle, and the vector of the coupled grating 30 and the vector of the two pupil expansion gratings 40 can form a closed triangle, so that the image display direction is convenient to design for the user to watch.
Referring to fig. 1 again, alternatively, the period lengths of the two pupil expansion gratings 40 are the same, the grating vector directions of the two coupling gratings 30 are symmetrically arranged with the edge where the two coupling gratings abut against each other as an axis, the two pupil expansion gratings 40 each have a pupil expansion in a first direction, one pupil expansion grating 40 has a pupil expansion in a second direction, the other pupil expansion grating has a pupil expansion in a direction away from the second direction, and the first direction and the second direction form an included angle.
In this embodiment, the period length of each pupil expansion grating 40 is set to be the same, and the grating vector directions of the two pupil expansion gratings 40 are symmetrically set by taking the edge where the two pupil expansion gratings are abutted against as an axis, so that on one hand, the processing can be facilitated, 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 emitted are approximately the same, so that the uniformity of the brightness of the output image is ensured. Here, the grating line of each pupil expansion grating 40 is gradually far away from the other pupil expansion grating 40 in the direction from the coupling grating 20 to the coupling grating 30, so that the light entering one pupil expansion grating 40 expands the pupil towards the second direction, i.e. away from the other pupil expansion grating 40, and simultaneously expands the pupil towards the first direction, i.e. in the direction from the coupling grating 20 to the coupling grating 30, thereby achieving the effect of two-dimensional pupil expansion and enabling the grating vectors of the two to be symmetrically arranged. The pupil expansion grating 40 of the structure can propagate rightward and expand the pupil in a larger space, so as to realize a larger-sized coupled image area and further realize a more compact light transmission structure 100.
Optionally, the period lengths of the coupling-in grating 20 and the pupil-expanding grating 40 are different, and the period lengths of the coupling-in grating 20 and the coupling-out grating 30 are T1, where T1 is greater than or equal to 200nm and less than or equal to 600nm;
and/or, the period length of the pupil expansion grating 40 is T2, where T2 is 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. The period lengths of the coupling-in grating 20 and the pupil expansion grating 40 are set to be different, and the period lengths of the coupling-in grating 20 and the coupling-out grating 30 are generally set to be the same and smaller than the period of the pupil expansion grating 40, so that the pupil expansion and display effects are improved.
Optionally, the angle between the pupil expansion grating 40 and the vector direction of the coupling-in grating 20 is in the range of 30 ° to 70 °.
The vector directions of the coupling-in grating 20 and the coupling-out grating 30 are the same, so that the vector direction included angle between the pupil expansion grating 40 and the coupling-in grating 20, that is, the vector direction included angle between the pupil expansion grating 40 and the coupling-out grating 30. When the angle between the coupling-out grating 30 and the vector direction of the coupling-in grating 20 is too small, light reflection 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 vector directions of the coupling-out gratings 30 and 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 pupil expansion and coupling-out of the light, and the incident angle and the emission angle of the light are the same.
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 or a polymer body grating;
and/or the pupil expansion grating 40 is a surface relief grating, a liquid crystal polarization grating, or a polymer body 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 pupil expansion grating 40 may be one of a surface relief grating, a liquid crystal polarization grating and a polymer grating, and 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, and the three gratings may be combined in various possible ways in the above-mentioned grating types.
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 (11)
1. An optical transmission structure, the optical transmission structure comprising:
a substrate;
the coupling grating is arranged on the surface of the substrate;
the coupling-out grating is arranged on the surface of the substrate; and
The two pupil expansion gratings are arranged between the coupling-in grating and the coupling-out grating and are arranged side by side in the direction perpendicular to the coupling-in grating to the coupling-out grating;
light rays coupled out of the coupling-in grating are all directed to the two pupil expansion gratings, the two pupil expansion gratings respectively expand pupils of the light rays and then are directed to the coupling-out grating, and the light rays in the coupling-out grating are emitted after being expanded pupils.
2. The light transmission structure of claim 1, wherein the two pupil expansion gratings are one-dimensional gratings and are arranged on the same surface of the substrate, and two opposite edges of the two pupil expansion gratings are abutted.
3. The light transmission structure of claim 1, wherein the pupil expansion grating is a one-dimensional grating, the two pupil expansion gratings are respectively arranged on two surfaces of the substrate, and projection parts of the two pupil expansion gratings on the substrate are overlapped.
4. The light-transmitting structure of claim 2, wherein the incoupling gratings are located on a midpoint-and-perpendicular line in the direction of arrangement of the two pupil-expanding gratings.
5. The optical transmission structure of claim 2, wherein the grating vectors of the coupling-in grating and the coupling-out grating have the same direction and the same period length, and the sum of vectors of the two pupil expansion gratings and the grating vector of the coupling-in grating in vector direction space is 0;
and/or the sum of vectors of the two pupil expansion gratings and the grating vector of the coupling grating in vector direction space is 0.
6. The optical transmission structure of claim 5, wherein the period lengths of the two pupil expansion gratings are the same, the grating vector directions of the two coupling gratings are symmetrically arranged with the abutting edges as axes, the two pupil expansion gratings have pupils in a first direction, one pupil expansion grating has a pupil expansion in a second direction, the other pupil expansion grating has a pupil expansion in a direction away from the second direction, and the first direction and the second direction form an included angle.
7. The optical transmission structure of claim 6, wherein the period length of the in-coupling grating is different from the period length of the pupil-expanding grating, and the period length of the in-coupling grating and the out-coupling grating is T1, and then T1 is greater than or equal to 200nm and less than or equal to 600nm;
and/or, if the period length of the pupil expanding grating is T2, T2 is more than or equal to 200nm and less than or equal to 600nm.
8. The light transfer structure of claim 6, wherein the angle between the pupil expansion grating and the coupling-in grating is in the range of 30 ° to 70 °.
9. The light transmission structure of claim 1, wherein the two pupil expansion gratings are two-dimensional gratings, symmetrically arranged along a central axis of the substrate, and have the same period length;
or,
two pupil-expanding gratings are two-dimensional gratings or two-dimensional photonic crystals with integrated structures.
10. 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 body grating;
and/or the pupil expanding grating is a surface relief grating, a liquid crystal polarization grating or a polymer object grating.
11. A head mounted display device comprising an image source and a light transmitting structure according to any one of claims 1 to 10, the light transmitting structure being located on the light exit side of the image source.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111618570.3A CN116400501A (en) | 2021-12-27 | 2021-12-27 | Light transmission structure and head-mounted display device |
| PCT/CN2022/100338 WO2023123921A1 (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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| CN202111618570.3A CN116400501A (en) | 2021-12-27 | 2021-12-27 | Light transmission structure and head-mounted display device |
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| CN101688977B (en) * | 2007-06-04 | 2011-12-07 | 诺基亚公司 | A diffractive beam expander and a virtual display based on a diffractive beam expander |
| CN107329261B (en) * | 2017-06-08 | 2019-04-30 | 东南大学 | A kind of head-mounted display part based on holographical wave guide |
| TWI756691B (en) * | 2019-05-30 | 2022-03-01 | 美商蘋果公司 | Optical system, head-mounted device, and display system |
| CN112817151A (en) * | 2019-11-18 | 2021-05-18 | 苏州苏大维格科技集团股份有限公司 | Waveguide lens and AR display device |
| CN214474235U (en) * | 2021-03-12 | 2021-10-22 | 上海鲲游科技有限公司 | Near-to-eye display device |
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