WO2023123920A1 - 光传输结构和头戴显示设备 - Google Patents

光传输结构和头戴显示设备 Download PDF

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Publication number
WO2023123920A1
WO2023123920A1 PCT/CN2022/100331 CN2022100331W WO2023123920A1 WO 2023123920 A1 WO2023123920 A1 WO 2023123920A1 CN 2022100331 W CN2022100331 W CN 2022100331W WO 2023123920 A1 WO2023123920 A1 WO 2023123920A1
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gratings
grating
outcoupling
coupling
substrate
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PCT/CN2022/100331
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English (en)
French (fr)
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程鑫
吾晓
饶轶
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歌尔光学科技有限公司
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Publication of WO2023123920A1 publication Critical patent/WO2023123920A1/zh

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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
    • 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

Definitions

  • the invention relates to the technical field of diffractive optical devices, in particular to a light transmission structure and a head-mounted display device.
  • AR Augmented Reality, Augmented Reality
  • display is a technology that calculates the position and angle of camera images in real time and adds corresponding images, videos, and 3D models.
  • the goal of this technology is to put the virtual world on the screen in reality. world and interact with it.
  • the AR display generally emits incident light from the image source, passes through the optical waveguide, and then enters the human eye for viewing.
  • the exit pupil of the AR product must be large enough.
  • the optical waveguide usually has three or more grating areas, such as optical coupling, optical pupil expansion, optical coupling, etc.
  • the functional area is a device that can expand the pupil.
  • the three functional areas of light coupling, optical pupil expansion, and light coupling are distributed independently, and the outcoupling area is only a small part, while the entire optical waveguide occupies a large area, and the light propagation They are all asymmetrical in one direction, resulting in the asymmetrical brightness of the image presented.
  • the optical transmission structure proposed by the present invention includes:
  • At least two coupling-in gratings at least two coupling-in gratings are arranged at intervals on a surface of the substrate;
  • At least two outcoupling gratings are arranged on any surface of the substrate, projections of at least two outcoupling gratings on the substrate are arranged side by side, and are located on the same side of the two incoupling gratings side;
  • the light received by at least two of the in-coupling gratings passes through the substrate and then respectively shoots to at least two of the out-coupling gratings, wherein the light passes through one out-coupling grating and then passes through the other out-coupling grating before being emitted.
  • the two in-coupling gratings are located on both sides of a perpendicular line in a direction connecting the two out-coupling gratings.
  • the vector directions of the two coupled-in gratings are the same, and the sum of the grating vectors of the two coupled-out gratings and the grating vectors of the two coupled-in gratings in the vector direction space is 0.
  • the outcoupling grating is a one-dimensional grating, the two outcoupling gratings are arranged on the same surface of the substrate, and the two edges of the two outcoupling gratings abut against each other;
  • the period lengths of the two outcoupling gratings are the same;
  • the grating vector directions of the two outcoupling gratings are arranged symmetrically with respect to the abutting edge of the two gratings.
  • the outcoupling grating is a one-dimensional grating
  • the two outcoupling gratings are respectively arranged on two surfaces of the substrate, and the projections of the two outcoupling gratings on the substrate overlap.
  • the period lengths of the two in-coupling gratings are the same, which is set as T1, and the period lengths of the two out-coupling gratings are the same, and are set as T2, then T1 is not equal to T2, and both T1 and T2 are greater than or equal to 200nm is less than or equal to 600nm.
  • the angle between each outcoupling grating and a vector direction of an incoupling grating ranges from 30° to 70°.
  • the outcoupling grating is a two-dimensional grating, and two outcoupling gratings are arranged symmetrically along the central axis of the substrate;
  • the cycle lengths of the two outcoupling gratings are the same.
  • outcoupling gratings there are four outcoupling gratings, two outcoupling gratings are respectively arranged on two opposite surfaces of the substrate, and the outcoupling gratings on the two opposite surfaces of the substrate have the same structure.
  • the two outcoupling gratings are arranged on a surface of the substrate, and the grating vector directions of the two outcoupling gratings arranged on the same surface are arranged symmetrically with respect to the abutting edge of the two as the axis;
  • Another outcoupling grating is arranged on the other surface of the substrate, and the grating vector direction of the outcoupling grating arranged on the other surface of the substrate is consistent with the grating vector direction of the incoupling grating.
  • the coupling-in grating is a surface relief grating, a liquid crystal polarization grating or a polymer bulk grating;
  • the outcoupling grating is a surface relief grating, a liquid crystal polarization grating, or a polymer bulk grating.
  • the present invention further proposes a head-mounted display device, the head-mounted display device includes an image source and the above-mentioned light transmission structure, and the light transmission structure is located on the light output side of the image source.
  • the light transmission structure includes a substrate and at least two coupling-in gratings and at least two coupling-out gratings arranged on the substrate.
  • the same side of the grating allows both of them to receive the outgoing light coupled into the grating, and the coupled-in grating that enters first can serve as the basis for pupil expansion of the coupled-in grating that enters later.
  • the two outcoupling gratings can both emit imaging light after pupil expansion, realize a two-dimensional pupil expansion effect, and increase the effective image area. In this way, when the image area of the same size is required, the size of the light transmission structure can be set smaller.
  • the decoupling of the light by at least two in-coupling gratings can ensure that the two out-coupling gratings can be injected into the two out-coupling gratings under the multi-angle in-coupling light, thereby ensuring that the out-coupling light is full of the out-coupling area and improving the image quality. brightness and uniformity.
  • Fig. 1 is a transverse sectional view of an embodiment of the 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 another embodiment of the light transmission structure of the present invention.
  • Fig. 4 is a light propagation route diagram of the light transmission structure shown in Fig. 1;
  • FIG. 5 is a front view of another embodiment of the light transmission structure of the present invention.
  • Fig. 6 is a cross-sectional comparison diagram of two surfaces of the light transmission structure shown in Fig. 5;
  • Fig. 7 is a cross-sectional comparative view of two surfaces of an additional embodiment of the light transmission structure of the present invention.
  • FIG. 8 is a light propagation route diagram of the light transmission structure shown in FIG. 7 .
  • label name label name 100 light transmission structure 12 second surface 10 base 20 Coupled into the grating 11 first surface 30 outcoupling grating
  • connection and “fixation” should be understood in a broad sense, for example, “fixation” can be a fixed connection, a detachable connection, or an integral body; It can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediary, and it can be an internal communication between two elements or an interaction relationship between two elements, unless otherwise clearly defined.
  • fixation can be a fixed connection, a detachable connection, or an integral body; It can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediary, and it can be an internal communication between two elements or an interaction relationship between two elements, unless otherwise clearly defined.
  • independent in-coupling gratings and out-coupling gratings are generally installed, and the out-coupling gratings only occupy a small part, which cannot realize the pupil expansion of two-dimensional images.
  • the setting of the single-coupling grating when the distance is relatively long, some non-perpendicular light with a certain azimuth angle is incident on the in-coupling grating, and will diffract to a certain grating in the out-coupling area at a certain azimuth angle, and enter one of the gratings
  • the light is coupled out after passing through another grating, so that it can only be coupled out in one grating in the out-coupling area, occupying half or a small part of the out-coupling area.
  • the present invention proposes a light transmission structure, through which at least two adjacent grating regions have pupil expansion and outcoupling functions at the same time, and cooperate with at least two coupling gratings, so as to realize pupil expansion in two-dimensional directions, and can The outcoupled light covers the entire outcoupling area.
  • the light transmission structure 100 proposed by the present invention includes: a substrate 10, at least two coupling-in gratings 20 and at least two coupling-out gratings 30, at least two of the coupling-in gratings
  • the gratings 20 are arranged at intervals on a surface of the substrate 10;
  • At least two of the outcoupling gratings 30 are arranged on any surface of the substrate 10, and the projections of at least two of the outcoupling gratings 30 on the substrate 10 are arranged side by side, and are located on the same side of the two incoupling gratings 20 ;
  • the light received by at least two of the in-coupling gratings 20 passes through the substrate 10 and then respectively goes to at least two of the out-coupling gratings 30 , where the light passes through one out-coupling grating 30 and then passes through the other out-coupling grating 30 before being emitted.
  • the light transmission structure 100 is applied in the field of AR display, for example, the light transmission structure 100 is applied in AR glasses, which may be an optical waveguide or other components capable of light transmission.
  • the substrate 10 is also called a dielectric optical waveguide, which is generally planar and has an in-coupling area for receiving incident light and an out-coupling area for projecting the light out. Shot out of zone.
  • one surface of the substrate 10 is set as the first surface 11
  • the other surface is set as the second surface 12 .
  • the base 10 can also be configured as a cylinder, which can be designed according to the desired product.
  • the material of the substrate 10 may be epoxy resin or other organic materials, or inorganic materials such as heavy flint glass, which is not limited here.
  • the transmission of incident light in the substrate 10 needs to meet two conditions.
  • One is that the light is emitted from the optically denser medium to the optically rarer medium, and the refractive index of the medium inside the substrate 10 is greater than that of the external medium, that is, the refractive index of the substrate 10
  • the rate must be greater than 1 (the refractive index of air is 1); the other is that the incident angle of light must be greater than the critical angle.
  • the optical substrate 10 further includes an in-coupling grating 20 disposed on the surface of the substrate 10 and located in an in-coupling region for coupling light into the substrate 10 .
  • the coupling grating 20 can change the incident angle of the incident light entering the substrate 10 , so that the incident angle is greater than or equal to the critical angle, and then the light can be totally reflected in the substrate 10 to complete the light transmission.
  • the coupling-in grating 20 can be embossed in the coupling-in area as a separate optical element, or the structure of the coupling-in grating 20 can be formed in the coupling-in area of the substrate 10 .
  • the outcoupling grating 30 is located in the outcoupling area. Similarly, the outcoupling grating 30 can be attached to the outcoupling area as a separate optical element, or the structure of the outcoupling grating 30 can be formed in the outcoupling area of the substrate 10 .
  • the incident angle is deflected again. The human eye acquires.
  • at least two outcoupling gratings 30 are provided, and the corresponding substrate 10 is also provided with at least two outcoupling regions.
  • the two outcoupling gratings 30 are arranged side by side, and can simultaneously receive light transmitted from the incoupling grating 20 . Please refer to FIG.
  • At least two outcoupling gratings 30 may be located on the same surface of the substrate 10 , or may be located on two opposite surfaces of the substrate 10 , ie respectively located on the first surface 11 and the second surface 12 . At least two outcoupling gratings 30 are arranged side by side, and the projections of the two outcoupling gratings 30 on the substrate 10 may be arranged at intervals, arranged in contact with each other, or arranged in an overlapping manner, which is not limited here. When two outcoupling gratings 30 are arranged overlappingly, the two outcoupling gratings 30 can be arranged on the first surface 11 and the second surface 12 respectively, so that both are one-dimensional gratings, which is convenient for processing.
  • the two outcoupling gratings 30 and the two incoupling gratings 20 are located on the same straight line along the direction from the incoupling region to the outcoupling region.
  • the two outcoupling gratings 30 can also be arranged in a misaligned direction along the direction from the coupling-in region to the outcoupling region, and the distance between them should not exceed 0.5 mm.
  • the overlapping portion can be set as a two-dimensional grating or a two-dimensional photonic crystal.
  • At least two coupling-in gratings 20 may also be located on the same surface of the substrate 10 , or on opposite surfaces, which is not limited here.
  • the shape of the outcoupling grating 30 is not limited, and its cross-sectional shape can be a cuboid or a cube, etc., and the shapes of at least two outcoupling gratings 30 can be the same or different.
  • the microscopic structure for changing the incident angle of light such as the arrangement of the grating lines in the figure, will not be described here.
  • the shape of the coupling-in grating 20 is also not limited, and its cross-sectional shape may be circular, rectangular, or irregular.
  • the cross-sectional shape of the coupling-in grating 20 can be set to be circular, which matches the shape of the output tube of the optical machine, so as to better receive light.
  • the coupling-in grating 20 is composed of a plurality of micro-optical structures arranged in an array, such as the grating lines in the figure, so as to deflect the incident angle of the incident light.
  • the cross-sectional shape of the coupling-in grating 20 can be set to be a rectangle or a circle.
  • the amount of coupled-in light can be increased in the arrangement direction of at least two coupling-out gratings 30, even if it deviates from the distance between the two coupling-out gratings 30.
  • the light in the direction of the vertical line can also be injected into the two outcoupling gratings 30 to achieve the effect of dilating both pupils and outcoupling the light.
  • the incident light is coupled into the substrate 10 by the two in-coupling gratings 20, it is transmitted to the positions of the out-coupling gratings 30 through the total reflection of the substrate 10, where the two out-coupling gratings
  • the grating direction of the output grating 30 is designed, that is, the direction of the grating vector is perpendicular to the direction of the grating lines
  • the light 1001 that first enters one of the out-coupling gratings 30 will enter the other out-coupling grating 30 after pupil expansion and turning, that is, 1001 light will generate diffracted light 1002 to another outcoupling grating 30, and continue to propagate along the original direction
  • 1002 will generate outcoupling light 1003 after the completion of pupil expansion in the outcoupling grating 30, reach the human eye, and continue along the original direction
  • the ray propagating in the direction 1001 will generate a diffracted ray 1004
  • the light that first enters the other outcoupling grating 30 will also be emitted through the same process as above. After the pupil dilation, the light will generate new light, and the new light will continue to spread and dilate the pupil, and the cycle will continue. Finally, the image will fill the entire exit pupil after the pupil dilation, so that the human eye can see the image in a large area , to improve the display effect.
  • the light transmission structure 100 includes a substrate 10 and at least two in-coupling gratings 20 and at least two out-coupling gratings 30 arranged on the substrate 10, by setting two one-dimensional out-coupling gratings 30 arranged side by side, And located on the same side of the two in-coupling gratings 20, so that both can accept the outgoing light from the in-coupling gratings 20, and the in-coupling grating 20 that enters first can serve as the basis for pupil expansion of the in-coupling grating 20 that enters later.
  • the two outcoupling gratings 30 can both emit imaging light after pupil expansion, realize a two-dimensional pupil expansion effect, and increase the effective image area.
  • the size of the light transmission structure 100 can be set smaller.
  • the decoupling of light by at least two in-coupling gratings 20 can ensure that under the multi-angle in-coupling light, both can be injected into two out-coupling gratings 30, thereby ensuring that the out-coupling light is filled with the out-coupling area, improving human
  • the vertical area of the image that can be completely observed by the eye improves the brightness and uniformity of the image.
  • FIG. 1 Please continue to refer to FIG. 1.
  • the two coupling-in gratings 20 and two coupling-out gratings 30 are located on the perpendicular line in the direction of the line connecting the two coupling-out gratings 30. on both sides.
  • the two in-coupling gratings 20 are arranged on both sides of the perpendicular line in the arrangement direction of the two out-coupling gratings 30, so that the light coupled by the two in-coupling gratings 20 can be directed to the two in-coupling gratings.
  • the probability of exiting the grating 30 is approximately equal, ensuring that each outcoupling grating 30 has light entering, thereby producing pupil dilation and outcoupling light, so that the brightness of the light emitted from each outcoupling grating 30 is the same, enabling the human eye to observe
  • the symmetrical distribution of image brightness further improves the display effect.
  • the distance between the two in-coupling gratings 20 and the out-coupling grating 30 on the corresponding side is not limited, and may be the same or different.
  • the two in-coupling gratings 20 can be arranged symmetrically with the perpendicular line on the line connecting the two out-coupling gratings 30 as the axis, so as to further improve the uniformity of the in-coupling light and ensure the effect of two-dimensional pupil expansion and outcoupling .
  • each outcoupling grating 30 is rectangular, and the length direction of each outcoupling grating 30 is consistent with the direction from the incoupling grating 20 to the outcoupling grating 30, and the two outcoupling gratings 30 are in the width direction Arranged side by side, so that the area of the base 10 can be fully utilized and the utilization rate can be improved.
  • the vector directions of the two in-coupling gratings 20 are the same, and the sum of the grating vectors of the two out-coupling gratings 30 and the two in-coupling gratings 20 in the vector direction space is 0.
  • the grating vectors of the two incoupling gratings 20 are set to be the same, so as to obtain light rays with approximately the same incident angle.
  • the grating vector directions of the two in-coupling gratings 20 are set to be perpendicular to the direction in which the two out-coupling gratings 30 are arranged, so as to further ensure the uniformity of the light rays incident on the two out-coupling gratings 30, and further improve the longitudinal direction of the image. on the display area.
  • the sum of the vector directions of the coupled-in grating 20 and the vector directions of the two out-coupled gratings 30 in the vector direction space must be 0, that is,
  • the vector coupled into the grating 20 and the two vectors coupled out of the grating 30 can form a closed triangle, which is convenient for designing the display direction of the image for users to watch.
  • the outcoupling grating 30 is a one-dimensional grating, the two outcoupling gratings 30 are arranged on the same surface of the substrate 10, and the two edges of the two outcoupling gratings 30 abut against each other;
  • the period lengths of the two outcoupling gratings 30 are the same;
  • the grating vector directions of the two outcoupling gratings 30 are set symmetrically with respect to the abutting edge of the two.
  • the cross-sectional shape of the outcoupling grating 30 can be set as a rectangle, which is convenient for processing.
  • the two outcoupling gratings 30 are both one-dimensional gratings, and are distributed on the same surface, and the edges of the two abut against each other. In this way, the structure of the one-dimensional gratings is simpler and easier to process. Reduce the occupation of the surface area of the substrate 10, reduce the size of the light transmission structure 100, and improve the surface utilization of the substrate 10; and after the incident light is transmitted to the outcoupling grating 30, there is a large space for propagation to the right and pupil expansion, realizing A larger out-coupling image area realizes a more compact light transmission structure 100 .
  • each outcoupling grating 30 is set to be the same, and the grating vector directions of the two outcoupling gratings 30 are arranged symmetrically with respect to the abutment of the two axes, so that, on the one hand, it can facilitate processing and improve Processing efficiency; on the other hand, it can make the direction and quantity of the two pupil dilated and coupled light rays roughly the same, so as to ensure the uniformity of the output image brightness.
  • the grating vector of each outcoupling grating 30 is set gradually close to another outcoupling grating 30 in the direction from the incoupling grating 20 to the outcoupling grating 30, so that the light entering the outcoupling grating 30 can be diffracted into another
  • One outcoupling grating 30 achieves the effect of pupil dilation and outcoupling, and makes the two grating vectors symmetrically arranged.
  • the cross-sectional shape of the outcoupling grating 30 can be set to be a combination of a trapezoid and a rectangle, that is, a figure formed by cutting off one corner of the original rectangle, and the cut corner needs to face the incoupling grating 20 and away from the other.
  • Outcoupling the grating 30 to form a hypotenuse so that the incident light can be expanded when it just enters the outcoupling grating 30, and can reduce unnecessary light energy loss at the corner of the square and improve light utilization. rate, and reduce the use of grating material.
  • the outcoupling grating 30 is a one-dimensional grating, and the two outcoupling gratings 30 are respectively arranged on the two surfaces of the substrate 10, and the projections of the two outcoupling gratings 30 on the substrate 10 overlap. .
  • the arrangement of the structure can effectively reduce the processing difficulty, thereby reducing the processing cost.
  • the two outcoupling gratings 30 partially overlap on the two surfaces, and the outcoupling can be realized through one total reflection, thereby increasing the outcoupling density.
  • the outcoupling grating 30 is a two-dimensional grating, the two outcoupling gratings 30 are arranged symmetrically along the central axis of the substrate 10, and the period lengths of the two outcoupling gratings 30 are the same.
  • the two outcoupling gratings 30 may also be two-dimensional gratings with an integrated structure. The arrangement of the structure can effectively improve the coupling-out efficiency and increase the stability of the structure.
  • the period lengths of the two in-coupling gratings 20 are the same, which is set as T1
  • the period lengths of the two out-coupling gratings 30 are the same, and are set as T2
  • T1 is not equal to T2
  • T1 and T2 are both Greater than or equal to 200nm and less than or equal to 600nm.
  • the period ranges of the coupling-in grating 20 and the coupling-out grating 30 are set to be greater than or equal to 200nm and less than or equal to 600nm, for example, 200nm, 300nm, 400nm, 500nm, 600nm, etc., to ensure the processing technology and improve the image display at the same time.
  • the included angle between each outcoupling grating 30 and a vector direction of an incoupling grating 20 ranges from 30° to 70°.
  • the angle range between the outcoupling grating 30 and the vector direction of an incoupling grating 20 is set to be 30° to 70°, for example, 30° , 40°, 50°, 60°, 70°, etc., to ensure smooth outcoupling of light.
  • outcoupling gratings 30 are provided, and two outcoupling gratings 30 are respectively provided on opposite surfaces of the substrate 10, and the opposite surfaces of the substrate 10
  • the structures of the outcoupling gratings 30 on both surfaces are the same.
  • two outcoupling gratings 30 at the above positions are arranged on the first surface 11, and two outcoupling gratings 30 same as the first surface 11 are also arranged on the second surface 12. 30.
  • the coupled-in light enters the out-coupling grating 30, the number of diffraction behaviors of the light is increased, and the light is coupled out through the first surface 11 and the second surface 12, that is, one total reflection can The light is coupled out, effectively increasing the pupil dilation density.
  • outcoupling gratings 30 there are three outcoupling gratings 30; two outcoupling gratings 30 are arranged on one surface of the substrate 10, and two outcoupling gratings 30 are arranged on the same surface.
  • the grating vector directions of the two outcoupling gratings 30 are arranged symmetrically with respect to the abutting edge of the two;
  • the direction of the grating vector of the grating 30 is consistent with the direction of the grating vector of the coupled-in grating 20 .
  • one outcoupling grating 30 is set on the second surface 12, and the vector direction of the outcoupling grating 30 is the same as the direction of the incoupling grating 20, and the period of the two outcoupling gratings 30 on the first surface 11 is The same and the vector direction is set symmetrically, so, after the in-coupling grating 20 receives the light, it is coupled into the substrate 10, and the diffracted light 2001 to the first surface 11 is generated. When the light enters one of the out-coupling gratings 30, it will generate Another diffracted ray 2002 that is coupled out of the grating 30 continues to propagate forward.
  • the outcoupling grating 30 When 2002 enters the outcoupling grating 30 again, it will generate a diffracted ray 2003 in the same direction as 2001. The diffracted rays 2003 and 2001 are incident on the second surface 12. When the grating 30 is coupled out, the outcoupled light 2004 and 2005 will be generated. Finally, the outcoupled light from one of the gratings 20 will cover the entire outcoupled grating 30. In the case of two coupled in gratings 20, the outcoupled light can be further improved. The emission of the grating 30 improves the brightness of the emitted image and ensures the uniformity of the image brightness.
  • the coupling-in grating 20 is a surface relief grating, a liquid crystal polarization grating or a polymer bulk grating;
  • the outcoupling grating 30 is a surface relief grating, a liquid crystal polarization grating, or a polymer bulk grating.
  • the in-coupling grating 20 may be a surface relief grating, which has a larger refractive index difference compared to air, which enables the light to obtain a larger deflection angle, thereby making it easier to design the incident light transmission structure 100 angle.
  • the coupling-in grating 20 may also be set as a liquid crystal polarization grating or a polymer grating.
  • the out-coupling grating 30 can be a surface relief grating, which can conveniently adjust the angle of out-coupling light, and more conveniently design the image display area.
  • the outcoupling grating 30 may also be set as a liquid crystal polarization grating or a polymer grating.
  • the present invention further proposes a head-mounted display device (not shown), the head-mounted display device includes an image source and the above-mentioned light transmission structure 100, the light transmission structure 100 is located in the image The light emitting side of the 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-mentioned embodiment, the beneficial effects brought by the above-mentioned embodiment will not be repeated again.
  • the head-mounted display device may be AR glasses or MR glasses, which include an image source that provides incident light for the light transmission structure 100.
  • the incident light enters the light transmission structure 100 from the air medium, it first passes through Diffraction coupled into the grating 20 enters the substrate 10 again, is transmitted through total reflection, passes through the outcoupling grating 30, and enters the human eye.
  • the head-mounted display device may also be a near-eye display (NED), a head-mounted display (HMD), or a head-up display (HUD).
  • the in-coupling grating 20 is arranged opposite to the image source, that is, the image source coincides with the projection of the in-coupling grating 20 on the substrate 10, so as to ensure that all incident light is coupled into The light received by the grating 20 improves the light transmission efficiency.
  • the image source includes a light source and a display panel.
  • the light source may be an LED light source, which provides a light source for the display panel, forms incident light after passing through the display panel, and irradiates to the light transmission structure 100 .
  • the display panel can be a liquid crystal display module on silicon (Liquid Crystal on Silicon, LCOS), a transmissive liquid crystal display module (LCD), a digital light processing display module (digital Light Processing, DLP) and a laser scanning (Laser Beam Scanning, LBS) A sort of.
  • LCOS Liquid Crystal on Silicon
  • LCD transmissive liquid crystal display module
  • DLP digital Light Processing
  • LBS laser scanning

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Abstract

一种光传输结构（100），光传输结构（100）包括基底（10）、至少两耦入光栅（20）及至少两耦出光栅（30），至少两耦入光栅（20）间隔排布于基底（10）的一表面（11,12）；至少两耦出光栅（30）设于基底（10）的任一表面（11,12），至少两耦出光栅（30）在基底（10）的投影呈并排设置，并位于两耦入光栅（20）的同一侧；至少两耦入光栅（20）接收的光线经基底（10）后分别射向至少两耦出光栅（30），其中光线经一耦出光栅（30）的光线再经另一耦出光栅（30）后射出。这种光传输结构（100）可实现二维扩瞳效果，实现高效且紧凑的光传输结构（100）。还公开了一种头戴显示设备。

Description

光传输结构和头戴显示设备 技术领域
本发明涉及衍射光学器件技术领域，尤其涉及一种光传输结构和头戴显示设备。
背景技术
AR(Augmented Reality，增强现实)显示是一种实时地计算摄影机影像的位置及角度并加上相应的图像、视频、3d模型的技术，这种技术的目标是在屏幕上把虚拟世界套在现实世界并进行互动。
AR显示一般是从图像源发出入射光，经光波导之后进入人眼观看。为了更好的让人眼看到呈现的图像，AR产品的出瞳要足够大，可知的，光波导通常具有三个或三个以上光栅区域，如光耦入、光扩瞳、光耦出等功能区域，是能够将光瞳进行扩展的器件。
然而现有的光传输结构中，光耦入、光扩瞳、光耦出三个功能区域独立分布，耦出的区域只有一小部分，而整个光波导占据的面积却很大，且光线传播都是单方向非对称的，导致呈现的图像在亮度上也是非对称的。
发明内容
基于此，有必要提供一种光传输结构和头戴显示设备，通过设置至少两个一维的光栅同时具有扩瞳和耦出功能，并接收至少两个耦入光栅的光线，旨在实现扩大人眼可观察到完整图像的区域的同时减小光传输结构的占据面积，实现紧凑的光传输结构。
为实现上述目的，本发明提出的光传输结构包括：
基底；
至少两耦入光栅，至少两所述耦入光栅间隔排布于所述基底的一表面；及
至少两耦出光栅，至少两所述耦出光栅设于所述基底的任一表面，至少 两所述耦出光栅在所述基底的投影呈并排设置，并位于两所述耦入光栅的同一侧；
至少两所述耦入光栅接收的光线经所述基底后分别射向至少两所述耦出光栅，其中光线经一耦出光栅后再经另一耦出光栅后射出。
可选地，所述耦入光栅和耦出光栅均设置有两个，两所述耦入光栅位于两所述耦出光栅连线方向上的中垂线的两侧。
可选地，两所述耦入光栅的矢量方向相同，两所述耦出光栅与两所述耦入光栅的光栅矢量在矢量方向空间上的矢量之和为0。
可选地，所述耦出光栅为一维光栅，两所述耦出光栅设于所述基底的同一表面，两所述耦出光栅的两边缘相抵接；
两所述耦出光栅的周期长度相同；
和/或，两所述耦出光栅的光栅矢量方向以两者相抵接的边缘为轴线对称设置。
可选地，所述耦出光栅为一维光栅，两所述耦出光栅分别设于所述基底的两表面，两所述耦出光栅在所述基底上的投影部分重合。
可选地，两所述耦入光栅的周期长度相同，设定为T1，两所述耦出光栅的周期长度相同，且设定为T2，则，T1不等于T2，T1和T2均大于等于200nm小于等于600nm。
可选地，每一所述耦出光栅与一耦入光栅的矢量方向夹角范围为30°～70°。
可选地，所述耦出光栅为二维光栅，两所述耦出光栅沿所述基底的中轴线对称设置；
两所述耦出光栅的周期长度相同。
可选地，所述耦出光栅设置有四个，所述基底相对的两表面分别设置有两个所述耦出光栅，且所述基底相对的两表面的耦出光栅的结构相同。
可选地，所述耦出光栅设置有三个；
其中两耦出光栅设于所述基底的一表面，设于同一表面的两耦出光栅的光栅矢量方向以两者相抵接的边缘为轴线对称设置；
另一耦出光栅设于所述基底的另一表面，设于所述基底另一表面的耦出光栅的光栅矢量方向与所述耦入光栅的光栅矢量方向一致。
可选地，所述耦入光栅为表面浮雕光栅、液晶偏振光栅或聚合物体光栅；
和/或，所述耦出光栅为表面浮雕光栅、液晶偏振光栅、聚合物体光栅。
为了实现上述目的，本发明又提出一种头戴显示设备，所述头戴显示设备包括图像源和如上所述的光传输结构，所述光传输结构位于所述图像源的出光侧。
本发明提出的技术方案中，光传输结构包括基底和设于基底的至少两耦入光栅和至少两个耦出光栅，通过设置并排设置的一维的两耦出光栅，并位于两个耦入光栅的同一侧，使得两者均能接受耦入光栅的出射光线，且首先射入的耦入光栅可以作为后射入的耦入光栅的扩瞳基础。如此，使得两个耦出光栅均能够经过扩瞳后射出成像光线，实现二维的扩瞳效果，增大有效图像区域，如此，在同样尺寸的图像区域需求时，光传输结构可以设置的尺寸更小。同时，由至少两个耦入光栅去耦入光线，可以保证在多角度的耦入光线下，均能射入两个耦出光栅，从而保证耦出光线均充满耦出区域，并提高了图像亮度和均匀性。
附图说明
为了更清楚地说明本发明实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图示出的结构获得其他的附图。
图1为本发明光传输结构一实施例的横向剖视图；
图2为本发明光传输结构另一实施例的横向剖视图；
图3为本发明光传输结构又一实施例的横向剖视图；
图4为图1所示光传输结构的光线传播路线图；
图5为本发明光传输结构再一实施例的正视图；
图6为图5所示光传输结构两个表面的横向剖视对比图；
图7为本发明光传输结构额外一实施例的两个表面的横向剖视对比图；
图8为图7所示光传输结构的光线传播路线图。
附图标号说明：
标号 名称 标号 名称
100 光传输结构 12 第二表面
10 基底 20 耦入光栅
11 第一表面 30 耦出光栅
本发明目的的实现、功能特点及优点将结合实施例，参照附图做进一步说明。
具体实施方式
下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本发明的一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。
需要说明，本发明实施例中所有方向性指示(诸如上、下、左、右、前、后……)仅用于解释在某一特定姿态(如附图所示)下各部件之间的相对位置关系、运动情况等，如果该特定姿态发生改变时，则该方向性指示也相应地随之改变。
另外，在本发明中如涉及“第一”、“第二”等的描述仅用于描述目的，而不能理解为指示或暗示其相对重要性或者隐含指明所指示的技术特征的数量。由此，限定有“第一”、“第二”的特征可以明示或者隐含地包括至少一个该特征。在本发明的描述中，“多个”的含义是至少两个，例如两个，三个等，除非另有明确具体的限定。
在本发明中，除非另有明确的规定和限定，术语“连接”、“固定”等应做广义理解，例如，“固定”可以是固定连接，也可以是可拆卸连接，或成一体；可以是机械连接，也可以是电连接；可以是直接相连，也可以通过中间媒介间接相连，可以是两个元件内部的连通或两个元件的相互作用关系，除非另有明确的限定。对于本领域的普通技术人员而言，可以根据具体情况理解上述术语在本发明中的具体含义。
另外，本发明各个实施例之间的技术方案可以相互结合，但是必须是以本领域普通技术人员能够实现为基础，当技术方案的结合出现相互矛盾或无法实现时应当认为这种技术方案的结合不存在，也不在本发明要求的保护范 围之内。
传统的衍射光传输结构中一般都设置独立的耦入光栅和耦出光栅，耦出光栅仅占很小部分，并不能实现二维图像的扩瞳。且单耦入光栅的设置，在距离较远时，部分带有一定方位角的非垂直光入射至耦入光栅后，会以一定方位角衍射向耦出区域的某一个光栅，进入其中一个光栅的光线经过另一个光栅后耦出，从而只能在耦出区域的一个光栅内耦出，占据耦出区域的一半或一小部分，最后人眼在移动观察时，在其他的耦出区域无法观察到该视场角的光线，如此，某些角度的光线在耦出时无法铺满整个耦出区域，使得对应的Eyebox在此方向上无法扩展。因此，本发明提出一种光传输结构，通过至少两个相邻的光栅区域同时具有扩瞳和耦出功能，并配合至少两个耦入光栅，从而实现二维方向上的扩瞳，并能够使得耦出的光线均铺满整个耦出区域。
请参照图1和图2，在本发明的一实施例中，本发明提出的光传输结构100包括：基底10、至少两耦入光栅20及至少两耦出光栅30，至少两所述耦入光栅20间隔排布于所述基底10的一表面；
至少两所述耦出光栅30设于所述基底10的任一表面，至少两所述耦出光栅30在所述基底10的投影呈并排设置，并位于两所述耦入光栅20的同一侧；
至少两所述耦入光栅20接收的光线经所述基底10后分别射向至少两所述耦出光栅30，其中光线经一耦出光栅30后再经另一耦出光栅30后射出。
本实施例中，光传输结构100应用于AR显示领域，例如，光传输结构100应用于AR眼镜中，其可以为光波导或者其他可进行光传导的部件。基底10也称介质光波导，其一般为平面状，具有接收入射光线的耦入区和将光线投影出射的耦出区，入射光线经过耦入区射入，在基底10内传输，并从耦出区射出。具体地，设置基底10的一表面为第一表面11，另一表面为第二表面12。当然，于其他实施例中，基底10也可以设置为圆柱形，可以根据所应有的产品进行设计。基底10的材料可以是环氧树脂或其他有机材料，也可以是重火石玻璃等无机材料，在此不做限定。
可知的，入射光线在基底10内传输需要满足两个条件，一是光线由光密 介质射向光疏介质，基底10内部的介质折射率大于外部介质的折射率，也即，基底10的折射率需大于1(空气的折射率为1)；另一个是光线的入射角度要大于临界角度。
为此，光基底10还包括耦入光栅20，耦入光栅20设于基底10的表面，并位于耦入区，用于将光线耦合进入基底10内。耦入光栅20能够改变入射光线射入基底10内部的入射角度，从而使得入射角度大于或等于临界角度，进而使得光线能够在基底10内发生全反射，完成光线的传输。耦入光栅20可以作为单独的光学元件压印在耦入区，也可以在基底10的耦入区加工成型耦入光栅20的结构。
耦出光栅30位于耦出区，同理，该耦出光栅30可作为单独的光学元件贴覆在耦出区，也可以在基底10的耦出区加工成型耦出光栅30的结构。由耦入光栅20耦入基底10内的光线在射向耦出光栅30时，入射角度再次发生偏转，例如，入射角度小于全反射临界角，入射光线透射于基底10，从而出射形成显示画面被人眼获取。
此处，耦入光栅20设置有至少两个，且间隔设置，耦入区对应设置有至少两个，一个耦入光栅20对应位于一个耦入区内。同时，设置至少两个耦出光栅30，对应的基底10也设置有至少两个耦出区，两个耦出光栅30并排设置，并可以同时接收到耦入光栅20传输过来的光线。请结合图3，至少两个耦出光栅30可以位于基底10的同一表面，也可以位于基底10相对的两表面，即分别位于第一表面11和第二表面12。至少两个耦出光栅30并排设置，可以是两个耦出光栅30在基底10的投影相间隔排布，或相抵接排布，也可以是相重叠排布，在此不做限定。在两个耦出光栅30相重叠设置时，可以将两耦出光栅30分别设置在第一表面11和第二表面12，使得两者为一维光栅，方便加工。且两个耦出光栅30和两耦入光栅20在沿耦入区至耦出区的方向上位于同一直线上。当然，两个耦出光栅30在沿耦入区至耦出区的方向上也可以错位设置，且错位设置时的间距不宜超过0.5mm。可选的，当两个耦出光栅30均在第一表面11或第二表面12时，且两者与重叠部分设置时，可以将该重叠部分设置为二维光栅或二维光子晶体。
在此基础上，至少两个耦入光栅20也可以位于基底10的同一表面，或者是相对的两表面，在此不做限定。耦出光栅30的形状并不限定，其横截面形 状可以是长方体或正方体等，至少两个耦出光栅30的形状可以相同，也可以不相同，当然，在耦出光栅30的表面会设有用于改变光线入射角度的微观结构，如图中的光栅线的设置，在此不做赘述。耦入光栅20的形状也不限定，其横截面的形状可以是圆形或矩形或不规则形状等。当然，当耦入光栅20距离光机的距离较近时，可以设定耦入光栅20的横截面形状为圆形，这与光机出筒的形状相匹配，从而能够更好地接收光线。当然，耦入光栅20是由多个呈阵列排布的微光结构组成的，如图中的光栅线，以实现对入射光线的入射角度的偏转。而在耦入光栅20距离光机的距离较远时，可以设定耦入光栅20的横截面形状为矩形或圆形。
请结合图4，由于设置有至少两个耦入光栅20，故而在至少两个耦出光栅30的排布方向上可以增加耦入光线的量，即使是偏离于两耦出光栅30之间的中垂线方向的光线，也可以均射入两个耦出光栅30内，达到两者均扩瞳并有耦出光线的效果。以两个耦入光栅20和两个耦出光栅30为例，入射光线由两耦入光栅20耦合进入基底10后，经过基底10的全反射传输至耦出光栅30位置处，在两个耦出光栅30的光栅方向经过设计后，即光栅矢量方向垂直于光栅线的方向，先进入其中一个耦出光栅30的光线1001会经过扩瞳、转折后再进入另一耦出光栅30内，即1001光线会产生向另一耦出光栅30的衍射光线1002，以及继续沿原方向传播，1002在该耦出光栅30内完成扩瞳后并产生耦出光线1003，到达人眼，而继续沿原方向传播的1001光线会再产生衍射光线1004，该衍射光线1004与衍射光线1002的路径相同，最终由另一耦出光栅30耦出。同理，先进入另一个耦出光栅30的光线也会经历如上一样的过程射出。光线在经历扩瞳后都会产生新的光线，新的光线会继续传播和扩瞳，不断循环，最终图像在扩瞳后充满整个出瞳，从而使得人眼在很大一片区域均可以看到图像，提高显示效果。
本发明提出的技术方案中，光传输结构100包括基底10和设于基底10的至少两耦入光栅20和至少两个耦出光栅30，通过设置并排设置的一维的两耦出光栅30，并位于两个耦入光栅20的同一侧，使得两者均能接受耦入光栅20的出射光线，且首先射入的耦入光栅20可以作为后射入的耦入光栅20的扩瞳基础。如此，使得两个耦出光栅30均能够经过扩瞳后射出成像光线，实现二维的扩瞳效果，增大有效图像区域，在同样尺寸的图像区域需求时，光传输结 构100可以设置的尺寸更小。同时，由至少两个耦入光栅20去耦入光线，可以保证在多角度的耦入光线下，均能射入两个耦出光栅30，从而保证耦出光线均充满耦出区域，提升人眼可完整观察到的图像纵向区域，并提高了图像亮度和均匀性。
请继续参照图1，可选地，所述耦入光栅20和耦出光栅30均设置有两个，两所述耦入光栅20位于两所述耦出光栅30连线方向上的中垂线的两侧。
本实施例中，将两个耦入光栅20设置在两个耦出光栅30排布方向上的中垂线的两侧，如此，可以使得两个耦入光栅20耦合的光线射向两个耦出光栅30的几率大致相等，保证每个耦出光栅30均有光线的进入，从而产生扩瞳和耦出光线，使得从每个耦出光栅30射出的光线亮度相同，能够使得人眼观察到的图像亮度对称分布，进一步提高显示效果。此处，不限定两耦入光栅20距离相对应侧的耦出光栅30的距离，可以相同，也可以不同。且优选的，可以将两个耦入光栅20以两耦出光栅30连线上的中垂线为轴线对称设置，从而进一步提升耦入光线的均匀性，保证二维扩瞳与耦出的效果。
具体地，每一耦出光栅30的横截面为矩形，每一耦出光栅30的长度方向与耦入光栅20至耦出光栅30的方向一致，两所述耦出光栅30在其宽度方向上并排设置，从而能够充分利用基底10的面积，提高利用率。
可选地，两所述耦入光栅20的矢量方向相同，两所述耦出光栅30与两所述耦入光栅20的光栅矢量在矢量方向空间上的矢量之和为0。
可以理解的，为了使得光线均朝向耦出光栅30射入，故而将两个耦入光栅20的光栅矢量设置相同，从而得到入射角度大致相同的光线。此处，设定两个耦入光栅20的光栅矢量方向垂直于两个耦出光栅30排布的方向，从而能够进一步保证射向两耦出光栅30的光线的均匀性，进一步提升图像在纵向上的显示区域。
且，为了使得入射角度与耦出的光线的出射角度相同，需要将耦入光栅20的矢量方向与两个耦出光栅30的矢量方向在矢量方向空间上的矢量之和为0，也即，耦入光栅20的矢量与两个耦出光栅30的矢量能够组成一个闭合的三角形，进而方便设计图像显示方向，供用户观看。
可选地，所述耦出光栅30为一维光栅，两所述耦出光栅30设于所述基底10的同一表面，两所述耦出光栅30的两边缘相抵接；
两所述耦出光栅30的周期长度相同；
和/或，两所述耦出光栅30的光栅矢量方向以两者相抵接的边缘为轴线对称设置。
本实施例中，可以设定耦出光栅30的横截面形状为矩形，方便加工。具体地，两耦出光栅30均为一维光栅，且分布在同一表面上，两者的边缘相抵接，如此，一维光栅结构更加简单，方便加工，且通过两者相邻设置，能够进一步减少对基底10的表面积占用，减小光传输结构100的尺寸，提升基底10的表面利用率；且入射光线传输至耦出光栅30后，可以向右进行传播和扩瞳的空间较大，实现更大尺寸的耦出图像区域，进而实现更加紧凑的光传输结构100。可选的，设定每一耦出光栅30的周期长度均相同，且两个耦出光栅30的光栅矢量方向以两者相抵接的边缘为轴线对称设置，如此，一方面可以方便加工，提高加工效率；另一方面可以使得两者进行扩瞳和耦出的光线方向和量大致相同，从而保证输出的图像亮度均匀性。此处，每一耦出光栅30的光栅矢量为在耦入光栅20至耦出光栅30的方向上逐渐靠近另一耦出光栅30设置，从而实现进入该耦出光栅30的光线可以衍射进入另一耦出光栅30，达到扩瞳耦出的效果，并使得两者的光栅矢量呈对称设置。
当然，于其他实施例中，还可以单独设置两个耦出光栅30的周期长度相同，或者设置两所述耦出光栅30的光栅矢量方向以两者相抵接的边缘为轴线对称。
此外，可设定耦出光栅30的横截面形状为梯形和矩形的合体，也即将原来的矩形切除一个顶角后形成的图形，且切除的顶角需要朝向耦入光栅20，并背离另一耦出光栅30，从而形成一个斜边，如此，可以使得入射光在刚进入耦出光栅30时就进行扩瞳，并能够减少在方形的顶角处的不必要的光能损耗，提升光线利用率，并减少光栅材料的使用。
于其他实施例中，耦出光栅30为一维光栅，两所述耦出光栅30分别设于所述基底10的两表面，两所述耦出光栅30在所述基底10上的投影部分重合。该结构的设置相比二维光栅能够有效降低加工难度，从而减少加工成本。且两个耦出光栅30在两表面上部分重叠，能够通过一次全反射实现耦出，从而增大了耦出密度。
可选地，耦出光栅30为二维光栅，两所述耦出光栅30沿所述基底10的中 轴线对称设置，两所述耦出光栅30的周期长度相同。或者，两耦出光栅30也可为一体化结构的二维光栅。该结构的设置能够有效提高耦出效率，增加结构的稳定性。
可选地，两所述耦入光栅20的周期长度相同，设定为T1，两所述耦出光栅30的周期长度相同，且设定为T2，则，T1不等于T2，T1和T2均大于等于200nm小于等于600nm。
可以理解的，当光栅的周期过小时，不利于工艺加工，当然，当周期过大时，会使得耦出光线的密度较小，不利于图像的显示。故而此处将耦入光栅20和耦出光栅30的周期范围均设置为大于等于200nm小于等于600nm，例如，200nm、300nm、400nm、500nm、600nm等，保证加工工艺，同时提升图像显示。
可选地，每一所述耦出光栅30与一耦入光栅20的矢量方向夹角范围为30°～70°。
本实施例中，耦出光栅30与一耦入光栅20的矢量方向夹角过小时，会出现光线的反射，不利于扩瞳耦出；而当该夹角过大时，不能使得耦入光栅20与两耦出光栅30的矢量形成闭合形状，不利于光线角度的调节，故而设定耦出光栅30与一耦入光栅20的矢量方向夹角范围为30°～70°，例如，30°、40°、50°、60°、70°等，以保证光线的顺利耦出。
请结合图5和图6，可选地，所述耦出光栅30设置有四个，所述基底10相对的两表面分别设置有两个所述耦出光栅30，且所述基底10相对的两表面的耦出光栅30的结构相同。
本实施例中，为了进一步提高耦出光线的密度，在第一表面11设置有两个如上位置的耦出光栅30，在第二表面12也设置两个同第一表面11相同的耦出光栅30，如此，在耦入光线射入耦出光栅30时，增加了光线的衍射行为发生的次数，光线经过第一表面11和第二表面12均发生耦出，也即一次全反射就可以将光线耦出，有效增大了扩瞳密度。
请参照图7和图8，为了增大耦出密度，可选地，所述耦出光栅30设置有三个；其中两耦出光栅30设于所述基底10的一表面，设于同一表面的两耦出光栅30的光栅矢量方向以两者相抵接的边缘为轴线对称设置；另一耦出光栅30设于所述基底10的另一表面，设于所述基底10另一表面的耦出光栅30的光 栅矢量方向与所述耦入光栅20的光栅矢量方向一致。
本实施例中，将第二表面12的耦出光栅30设置为一个，且该耦出光栅30的矢量方向与耦入光栅20的方向相同，第一表面11的两个耦出光栅30的周期相同且矢量方向呈对称设置，如此，在耦入光栅20接收光线后耦入基底10内，产生向第一表面11的衍射光线2001，该光线在入射至其中一耦出光栅30时会产生向另一耦出光栅30的衍射光线2002，并继续朝前传播，2002再次入射至该耦出光栅30时会产生与2001方向相同的衍射光线2003，衍射光线2003和2001入射至第二表面12的耦出光栅30时会产生耦出光线2004和2005，最终其中一个耦入光栅20的耦出光线将铺满整个耦出光栅30，在两个耦入光栅20的情况下，能够进一步提升耦出光栅30的射出，提升出射图像的亮度，并保证图像亮度的均匀性。
可选地，所述耦入光栅20为表面浮雕光栅、液晶偏振光栅或聚合物体光栅；
和/或，所述耦出光栅30为表面浮雕光栅、液晶偏振光栅、聚合物体光栅。
本实施例中，耦入光栅20可以是表面浮雕光栅，表面浮雕光栅相比于空气具有较大的折射率差异，能够使得光线获得更大的偏转角度，从而更加便于设计光传输结构100的入射角度。当然，于其他实施例中，也可以设置耦入光栅20为液晶偏振光栅或聚合物体光栅等。
可选的，在耦入光栅20为上述任意一光栅时，耦出光栅30可以为表面浮雕光栅，能够方便调节耦出的光线角度，更加方便设计图像显示区域。当然，于其他实施例中，也可以设置耦出光栅30为液晶偏振光栅或聚合物光栅。
为了实现上述目的，本发明又提出一种头戴显示设备(未图示)，所述头戴显示设备包括图像源和如上所述的光传输结构100，所述光传输结构100位于所述图像源的出光侧。由于本发明的头戴显示设备的光传输结构100参照了上述实施例的光传输结构100的结构，因此，由上述实施例所带来的有益效果再次不做赘述。
本实施例中，头戴显示设备可以是AR眼镜或MR眼镜，其包括图像源，该图像源为光传输结构100提供入射光，当入射光由空气介质入射至光传输结构100时，首先通过耦入光栅20的衍射，再进入基底10中，通过全反射传输， 再从耦出光栅30穿出，射入人眼中。当然，头戴显示设备还可以是近眼显示器(NED)、头戴显示器(HMD)或抬头显示器(HUD)等。
在一实施例中，为了尽可能接收图像源，耦入光栅20与图像源正对设置，也即图像源与耦入光栅20在基底10的投影相重合，从而能够保证入射光均被耦入光栅20所接收，提高光传输效率。
可选的，图像源包括光源和显示面板，光源可选的为LED光源，为显示面板提供光源，经显示面板后形成入射光，射向光传输结构100。显示面板可以是硅基液晶显示模块(Liquid Crystal on Silicon，LCOS)、透射液晶显示模块(LCD)、数字光处理显示模块(digital Light Processing，DLP)和激光扫描(Laser Beam Scanning，LBS)中的一种。
以上仅为本发明的优选实施例，并非因此限制本发明的专利范围，凡是在本发明的发明构思下，利用本发明说明书及附图内容所作的等效结构变换，或直接/间接运用在其他相关的技术领域均包括在本发明的专利保护范围内。

Claims (12)

  1. 一种光传输结构，其特征在于，所述光传输结构包括：
    基底；
    至少两耦入光栅，至少两所述耦入光栅间隔排布于所述基底的一表面；及
    至少两耦出光栅，至少两所述耦出光栅设于所述基底的任一表面，至少两所述耦出光栅在所述基底的投影呈并排设置，并位于两所述耦入光栅的同一侧；
    至少两所述耦入光栅接收的光线经所述基底后分别射向至少两所述耦出光栅，其中光线经一耦出光栅再经另一耦出光栅后射出。
  2. 如权利要求1所述的光传输结构，其特征在于，所述耦入光栅和耦出光栅均设置有两个，两所述耦入光栅位于两所述耦出光栅连线方向上的中垂线的两侧。
  3. 如权利要求2所述的光传输结构，其特征在于，两所述耦入光栅的矢量方向相同，两所述耦出光栅与两所述耦入光栅的光栅矢量在矢量方向空间上的矢量之和为0。
  4. 如权利要求3所述的光传输结构，其特征在于，所述耦出光栅为一维光栅，两所述耦出光栅设于所述基底的同一表面，两所述耦出光栅的两边缘相抵接；
    两所述耦出光栅的周期长度相同；
    和/或，两所述耦出光栅的光栅矢量方向以两者相抵接的边缘为轴线对称设置。
  5. 如权利要求3所述的光传输结构，其特征在于，所述耦出光栅为一维光栅，两所述耦出光栅分别设于所述基底的两表面，两所述耦出光栅在所述基底上的投影部分重合。
  6. 如权利要求4或5所述的光传输结构，其特征在于，两所述耦入光栅的周期长度相同，设定为T1，两所述耦出光栅的周期长度相同，且设定为T2，则，T1不等于T2，T1和T2均大于等于200nm小于等于600nm。
  7. 如权利要求4或5所述的光传输结构，其特征在于，每一所述耦出光栅与一耦入光栅的矢量方向夹角范围为30°～70°。
  8. 如权利要求2所述的光传输结构，其特征在于，所述耦出光栅为二维光栅，两所述耦出光栅沿所述基底的中轴线对称设置；
    两所述耦出光栅的周期长度相同。
  9. 如权利要求1所述的光传输结构，其特征在于，所述耦出光栅设置有四个，所述基底相对的两表面分别设置有两个所述耦出光栅，且所述基底相对的两表面的耦出光栅的结构相同。
  10. 如权利要求1所述的光传输结构，其特征在于，所述耦出光栅设置有三个；
    其中两耦出光栅设于所述基底的一表面，设于同一表面的两耦出光栅的光栅矢量方向以两者相抵接的边缘为轴线对称设置；
    另一耦出光栅设于所述基底的另一表面，设于所述基底另一表面的耦出光栅的光栅矢量方向与所述耦入光栅的光栅矢量方向一致。
  11. 如权利要求1所述的光传输结构，其特征在于，所述耦入光栅为表面浮雕光栅、液晶偏振光栅或聚合物体光栅；
    和/或，所述耦出光栅为表面浮雕光栅、液晶偏振光栅、聚合物体光栅。
  12. 一种头戴显示设备，其特征在于，所述头戴显示设备包括图像源和如权利要求1至11中任意一项所述的光传输结构，所述光传输结构位于所述图像源的出光侧。
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