CN113885212B

CN113885212B - Pupil expanding device

Info

Publication number: CN113885212B
Application number: CN202111324166.5A
Authority: CN
Inventors: 顾志远; 赵鑫; 郑昱
Original assignee: Journey Technology Ltd
Current assignee: Journey Technology Ltd
Priority date: 2021-11-10
Filing date: 2021-11-10
Publication date: 2022-07-22
Anticipated expiration: 2041-11-10
Also published as: CN113885212A

Abstract

The invention discloses a pupil expanding device, wherein a second structure subsection is added in an upper waveguide structure of a two-dimensional waveguide sheet in the prior art, an entrance pupil light beam is split into a left field and a right field after being expanded in the horizontal direction for one time, and then is emitted from the lower waveguide structure after being expanded in the horizontal direction, so that the light beam realizes secondary pupil expansion in the horizontal direction in the upper waveguide structure, the lower waveguide structure performs pupil expansion in the vertical direction, and under the condition of adopting common low-refractive-index materials, the field angle, the eye box and the exit pupil distance can be kept unchanged, the size of the two-dimensional waveguide sheet is effectively reduced, the image display of the full field is realized, the device is more suitable for the optimal position of human vision, the machining difficulty is reduced, and the light energy utilization rate is improved.

Description

Pupil expanding device

Technical Field

The embodiment of the invention relates to the technical field of display, in particular to a pupil expanding device.

Background

Augmented Reality (AR) technology is a technology that skillfully fuses virtual information and the real world, and can be used in the real world after simulating virtual information such as characters, images, three-dimensional models, music, videos and the like generated by a computer, so as to supplement the real information in the real world and realize the 'enhancement' of the real world. The head-mounted display utilizing the augmented reality technology can enable people to project virtual images to human eyes while looking up the surrounding environment, and has important significance in the fields of military affairs, industry, entertainment, medical treatment, transportation and the like.

In the transmissive type head mounted display currently used for augmented reality, the main techniques include: the Birdbath, prism, free form surface and optical waveguide technology, compared with other technologies, the head-mounted display adopting the optical waveguide technology has smaller volume and is more like a pair of glasses. The optical waveguide technology mainly includes an array optical waveguide, a surface relief grating waveguide and a volume holographic waveguide, wherein the color expression and the light energy utilization rate of the array optical waveguide are superior to those of a diffraction optical waveguide and a volume holographic waveguide, and particularly, the array optical waveguide adopting the two-dimensional exit pupil expansion technology also has the advantages of small coupled light organism volume, large exit pupil distance, large eye box and the like.

As people demand more and more for immersive experiences and the appearance of AR glasses, technicians need to increase the field angle of the display system and also require the display system to be similar in shape and volume to ordinary glasses. Due to the asymmetry of the existing two-dimensional exit pupil expanding technology, if a common material with a lower refractive index (e.g. H-BAK5, n is 1.56) is used to transmit a larger field angle (e.g. 55 ° of diagonal), the volume of the two-dimensional waveguide sheet will increase, and the deviation between the effective display area center and the optimal position of human eyes is larger; if a material with a high refractive index is used, the processing difficulty and cost of the two-dimensional waveguide sheet will be greatly increased, the asymmetry of the structure of the two-dimensional waveguide sheet cannot be changed, and the two-dimensional waveguide sheet also faces the problem of volume increase when a larger field angle is transmitted.

Disclosure of Invention

In view of this, embodiments of the present invention provide a pupil expanding device, in which a second structure subsection is added in an upper waveguide structure of a two-dimensional waveguide plate in the prior art, and an entrance pupil beam is split into left and right view fields after being expanded in a horizontal direction once in a horizontal direction, and then reaches a lower waveguide structure for emergence, so that the light beam realizes secondary pupil expansion in a horizontal direction in the upper waveguide structure, and the lower waveguide structure performs pupil expansion in a vertical direction.

In a first aspect, an embodiment of the present invention provides a pupil expanding device, including a first plane, a second plane, and a first waveguide structure and a second waveguide structure, which are disposed between the first plane and the second plane, and sequentially disposed along a first direction; the first waveguide structure comprises a first structure subsection, a second structure subsection and a third structure subsection arranged in sequence along a second direction, the first direction being parallel to the first plane; the second direction intersects the first direction;

the second structure subsection comprises a plurality of second beam splitters and a plurality of second beam splitters, wherein the plurality of second beam splitters are sequentially arranged along a third direction, the plurality of second beam splitters extend along a fourth direction, the plurality of second beam splitters are sequentially arranged along the fourth direction, the plurality of second beam splitters extend along the third direction, and the first direction, the second direction, the third direction and the fourth direction are intersected in pairs;

after a part of light rays entering the second structure subsection pass through the plurality of second beam splitters to realize a first pupil expansion, the part of light rays sequentially enter the first structure subsection and the second waveguide structure to complete a second pupil expansion and a third pupil expansion;

and the other part of light rays entering the second structure subsection realize a first pupil expansion through the second beam splitters and then sequentially enter the third structure subsection and the second waveguide structure to complete a second pupil expansion and a third pupil expansion.

Optionally, the first structure subsection includes a plurality of first beam splitters, the plurality of first beam splitters are sequentially arranged in parallel along the second direction, and the plurality of first beam splitters extend along the fourth direction.

Optionally, the third structural subsection includes a plurality of third beam splitters, the plurality of third beam splitters are sequentially arranged in parallel along the second direction, and the plurality of third beam splitters extend along the third direction.

Optionally, the first structural subsection and the third structural subsection are symmetrically arranged along the first direction.

Optionally, the second waveguide structure includes a plurality of fourth beam splitters, and the plurality of fourth beam splitters are sequentially arranged in parallel along the first direction.

Optionally, the plurality of first beam splitters are sequentially arranged in parallel at equal intervals along the second direction;

the third beam splitters are arranged in parallel at equal intervals along the second direction in sequence;

the fourth beam splitters are sequentially arranged in parallel at equal intervals along the first direction.

Optionally, the second beam splitter and the second beam splitter are symmetrically arranged along the first direction.

Optionally, a plurality of the second beam splitters are arranged at equal intervals; the second beam splitters are arranged at equal intervals.

Optionally, an included angle between the fourth direction and the first direction is α, and an included angle between a normal direction of the second beam splitter and a normal direction of the first plane is γ; an included angle between the third direction and the first direction is beta, and an included angle between the normal direction of the second beam splitter and the normal direction of the first plane is gamma; the included angle between the third direction and the fourth direction is 180 degrees- (alpha + beta);

an included angle between the normal direction of the fourth beam splitter and the normal direction of the first plane is theta;

wherein alpha is more than 0 and less than 90 degrees, beta is more than 0 and less than 90 degrees, gamma is more than 80 degrees and less than 90 degrees, and theta is more than 20 degrees and less than 28 degrees.

Optionally, the pupil expanding device further comprises a coupling-in structure;

the coupling-in structure comprises a triangular prism and is used for coupling parallel beams emitted by the optical machine into the second structure subsection.

The pupil expanding device provided by the embodiment of the invention comprises a first waveguide structure and a second waveguide structure which are sequentially arranged along a first direction, wherein a second structure subsection is added to the first waveguide structure, and the second structure subsection comprises a plurality of second beam splitters and a plurality of second beam splitters. The second beam splitters are sequentially arranged along a third direction and extend along a fourth direction, and the second beam splitters are sequentially arranged along the fourth direction and extend along the third direction. And after a part of light rays entering the second structure part pass through the second beam splitters to realize a first pupil expansion, the part of light rays sequentially enter the first structure part and the second waveguide structure to complete a second pupil expansion and a third pupil expansion. And the other part of light rays entering the second structure subsection realize a first pupil expansion through the second beam splitters and then sequentially enter the third structure subsection and the second waveguide structure to complete a second pupil expansion and a third pupil expansion. Under the unchangeable condition in angle of vision, eye box and exit pupil distance, can effectively reduce the size of two-dimensional waveguide piece through the pupil expanding device of this application, realize the image display of full visual field, be fit for people's eye vision best position more, reduce the machining degree of difficulty simultaneously, improved light energy utilization.

Drawings

Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments thereof, made with reference to the following drawings:

FIG. 1 is a three-dimensional view of a conventional two-dimensional waveguide slice structure in the prior art;

FIG. 2 is a diagram of a light path from point A 'to point B' in a conventional two-dimensional waveguide structure according to the prior art;

FIG. 3 is an equivalent optical path diagram of a light ray in a general two-dimensional waveguide structure in the prior art;

FIG. 4 is a schematic shape diagram of a conventional two-dimensional waveguide slice structure with a diagonal viewing angle of 55 degrees in the prior art;

figure 5 is a schematic structural diagram of a triple pupil expansion device according to an embodiment of the present invention;

FIG. 6 is a schematic structural diagram of a second structural subsection;

FIG. 7 is a schematic structural view of a second alternative structural subsection provided in accordance with an embodiment of the present invention;

figure 8 is a schematic diagram of an optical path of a triple pupil expanding device according to an embodiment of the present invention;

figure 9 is a schematic diagram of the left field of view optical path of a pupil expanding device according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be described in detail below by way of specific embodiments in conjunction with the accompanying drawings in the embodiments of the present invention. It is to be understood that the embodiments described are only a few embodiments of the present invention and that all other embodiments, which can be derived by one of ordinary skill in the art without inventive faculty, based on the embodiments of the present invention, are within the scope of the present invention.

Examples

FIG. 1 shows three views of a conventional two-dimensional waveguide sheet; FIG. 2 is a diagram of a light path from a point A 'to a point B' in a conventional two-dimensional waveguide structure according to the prior art; FIG. 3 is an equivalent optical path diagram of a light ray in a general two-dimensional waveguide structure in the prior art; fig. 4 is a shape diagram of a conventional two-dimensional waveguide structure with a diagonal field angle of 55 ° in the prior art. As shown in fig. 1 to 4, a structure of a general two-dimensional waveguide sheet includes an upper structure waveguide sheet and a lower structure waveguide sheet; the upper and lower structured waveguide sheets are both arranged between two mutually

parallel surfaces

1 and 2. The upper structure waveguide plate also comprises a series of parallel beam splitters (beam splitter 1-beam splitter 12) embedded in the surface 1 and the surface 2, the structure mainly functions to turn the light beam coupled into the structure to exit, and each beam splitter can form an image once for the exit pupil, thereby realizing the pupil expansion in the horizontal direction; the lower structure waveguide plate is similar to a common one-dimensional array waveguide, and the lower structure waveguide plate also comprises a series of parallel beam splitters (beam splitter 1 '-beam splitter 6') embedded in the surface 1 and the surface 2, and the main function of the structure is to couple out the light beam which is turned by the upper structure waveguide plate, so that the light beam is received by human eyes and the pupil expansion in the vertical direction is realized. The existing two-dimensional waveguide sheet has the problems of large volume and weight, large deviation between the actual position of human eyes and the optimal position of human eyes and low light energy utilization rate, and is analyzed by combining the figures 1 to 4 as follows:

fig. 2(a) shows a light path diagram of a light ray transmitted from a point a 'to a point B' in the upper structured waveguide sheet, and fig. 2(B) shows a light path diagram of a light ray transmitted from a point a 'to a point B' on the surface of the upper structured waveguide sheet, wherein the path length traveled by the light ray in the waveguide sheet is 2L, the path length traveled by the light ray on the surface of the waveguide sheet is D, the light ray has an incident angle α, and the geometric relationship in the diagram satisfies equation 1.1:

D＝2L*sinα， (1.1)；

according to the formula 1.1, it can be understood that the waveguide sheet with the width D has an equivalent length or spread length D/sin α for the light with the incident angle α, and therefore, the separation distance of the beam splitter is D, the incident angle of the light is α, and the equivalent separation or spread interval is D/sin α.

Taking the ordinary two-dimensional waveguide plate shown in fig. 1 as an example, assuming that the mirror spacing d is sufficiently small, referring to fig. 3, fig. 3 shows an equivalent optical path diagram, in which the tilt angle of the beam splitter 1 with respect to the X direction (i.e., the horizontal direction) is 45 °, the thickness H of the two-dimensional waveguide plate is 1.7mm, H-BAK5 (refractive index n is 1.56) is used as a glass material, the diagonal field angle of the coupled-in image in the waveguide plate is 55 ° (16: 9 screen is used, the horizontal field × the longitudinal field is 48.8 ° × 28.63 °), the exit pupil of the coupled-in optical machine is 5.5mm, and the exit pupil is 5.5mmThe interpupillary distance is 20mm, and the horizontal eye box is 10 mm. According to the given parameters, the critical angle alpha of total reflection can be obtained_cSatisfies equation 1.2:

in consideration of assembly tolerance and optical-mechanical design distortion, the minimum incident angle in the two-dimensional waveguide plate should be slightly larger than the critical angle of 39.87 °, so that the total reflection transmission angle of light in the two-dimensional waveguide plate is in the range of (40.88 °, 61.92 °), and the central incident angle is 50 °. Combining with the formula (1.1), the equivalent length or the expansion length of the light ray in the lower structural waveguide plate is about 21.12mm, and combining the obtained data, the equivalent height of the upper structural waveguide plate is about 28.98mm and the equivalent length is about 65.9mm can be obtained by using the principle that the light path is reversible, as shown in fig. 3, the actual size of the upper structural waveguide plate is about 50.48mm × 22.2mm by reverse pushing according to the formula (1.1). For example, 6 reflectors 2 are embedded in the lower structured waveguide sheet, and the height of the lower structured waveguide sheet is at least 23mm in consideration of the processing technology according to the design concept of the common one-dimensional waveguide sheet.

From the above analysis, referring to fig. 4, fig. 4 shows the structural shape of a general two-dimensional waveguide sheet having a diagonal angle of view of 55 °. It can be seen that in the structure, the deviation between the actual position of the human eye and the optimal position of the human eye is large, the actual position of the human eye is probably positioned at the position of the waveguide sheet 3, the redundancy is too much, and the structure of the common two-dimensional waveguide sheet 4 not only increases the volume and the weight of the two-dimensional waveguide sheet, but also reduces the light energy utilization rate.

In view of the above problems, embodiments of the present invention provide a pupil expanding device, which can perform secondary pupil expansion in the horizontal direction and primary pupil expansion in the vertical direction. Figure 5 is a three-view diagram of a pupil expanding device configuration according to an embodiment of the present invention; figure 8 is a schematic optical path diagram of a triple pupil expanding device according to an embodiment of the present invention. As shown in fig. 5 and 8, the pupil expanding device provided by the embodiment of the invention includes a first plane S1, a second plane S2, and a first waveguide structure 1 and a second waveguide structure 2 disposed between a first plane S1 and a second plane S2, wherein the first waveguide structure 1 and the second waveguide structure 2 are sequentially disposed along a first direction (as shown in the Y direction in fig. 5); the first waveguide structure 1 comprises a first structural subsection 11, a second structural subsection 12 and a third structural subsection 13 arranged in sequence along a second direction (shown as the X-direction in fig. 5), the first direction being parallel to a first plane S1, the second direction intersecting the first direction;

the second structural unit 12 includes a plurality of second beam splitters 121 and a plurality of second beam splitters 122, wherein the plurality of second beam splitters 121 are sequentially arranged along a third direction (e.g., Z direction in fig. 5), the plurality of second beam splitters 121 extend along a fourth direction (e.g., P direction in fig. 5), the plurality of second beam splitters 122 are sequentially arranged along a fourth direction, the plurality of second beam splitters 122 extend along the third direction, and the first direction, the second direction, the third direction, and the fourth direction intersect each other two by two. After a part of the light entering the second structural subsection 12 passes through the second plurality of beam splitters 121 to realize the first pupil expansion, the part of the light enters the first structural subsection 11 and the second waveguide structure 2 in sequence to complete the second pupil expansion and the third pupil expansion. The other part of the light entering the second structural subsection 12 passes through the second beam splitters 122 to realize the first pupil expansion, and then enters the third structural subsection 13 and the second waveguide structure 2 in sequence to complete the second pupil expansion and the third pupil expansion.

Exemplarily, as shown in fig. 5 and 8, a first waveguide structure 1 and a second waveguide structure 2 are disposed between a first plane S1 and a second plane S2 of the triple-pupil expansion device, the first waveguide structure 1 and the second waveguide structure 2 are disposed up and down along the Y direction in fig. 3, the first waveguide structure 1 and the second waveguide structure 2 may use a common material with a lower refractive index, for example, H-BAK5, the refractive index n is 1.56, the first waveguide structure 1 performs twice X-direction (horizontal direction) pupil expansion on incident parallel light beams, the second waveguide structure 2 performs once Y-direction (vertical direction) pupil expansion on light beams after the pupil expansion through the first waveguide structure 1, so as to meet the requirement of the two-dimensional waveguide structure on pupil expansion, and implement triple-pupil expansion of the incident light beams. Specifically, the first waveguide structure 1 includes a first structure subsection 11, a second structure subsection 12, and a third structure subsection 13, which are sequentially arranged in the X direction in fig. 3. Where the X direction is parallel to the first plane S1 and the Y direction intersects the first direction, e.g., the Y direction is orthogonal to the X direction.

The first structural subsection 11 comprises a first beam splitter 111, the third structural subsection 13 comprises a third beam splitter 131 and the second waveguide structure 2 comprises a plurality of fourth beam splitters 21. The second structure subsection 12 is additionally arranged in the middle area of the first waveguide structure 1, the second structure subsection 12 comprises a plurality of second beam splitters 121 and a plurality of second beam splitters 122, parallel light beams are split into left view field light beams, middle view field light beams and right view field light beams, and the first beam splitter 111, the plurality of second beam splitters 121, the plurality of second beam splitters 122, the third beam splitter 131 and the fourth beam splitter 21 have the functions of splitting and turning the light beams and adjusting the propagation direction of the light beams. For example, the incident beam is split by additionally plating a reflective film and a transmissive film on the surface of the lens. Specifically, the middle position of the entrance pupil in the first waveguide structure 1 is adjusted, and along the Y direction in the figure, when parallel light beams emitted by the optical engine enter the second beam splitter 121 and the second beam splitter 122 of the second structure subsection 12 in sequence from the entrance pupil, the light beams reaching the second structure subsection 12 are split into a first part of light and a second part of light, the first part of light is reflected by the second beam splitter 121 to realize the first pupil expansion along the horizontal direction and then reach the first beam splitter 111, the light beams are reflected by the first beam splitter 111 to realize the second pupil expansion along the horizontal direction and then reach the fourth beam splitter 21, the light beams are reflected by the fourth beam splitter 21 to realize the first pupil expansion along the vertical direction and then are emitted to the user's eye for imaging, and the right triple-view-field pupil imaging is formed; the second part of light is reflected by the second beam splitter 122 to realize the first pupil expansion along the horizontal direction and then reach the third beam splitter 131, reflected by the third beam splitter 131 to realize the second pupil expansion along the horizontal direction and then reach the fourth beam splitter 21, reflected by the fourth beam splitter 21 to realize the first pupil expansion along the vertical direction and then exit to the eyes of the user for imaging, and thus the left view field triple pupil expansion imaging is formed. The field angle, the eye box and the exit pupil distance are kept unchanged, the second structure subsection 12 is added, the pupil expanding times of incident light rays in the horizontal direction are increased, the pupil expanding range in the horizontal direction is enlarged, the position of an entrance pupil is adjusted, the size of the two-dimensional waveguide sheet can be effectively reduced, image display of a full field of view is realized, the two-dimensional waveguide sheet is more suitable for the optimal position of human vision, the machining difficulty is reduced, and the light energy utilization rate is improved.

Further, as shown in fig. 6 and 7, the second beam splitter 121 and the second beam splitter 122 have a plurality of structural arrangements, and theoretically, the larger the number of the second beam splitter 121 and the second beam splitter 122 is, the wider the pupil is expanded in the horizontal direction for the first time of the entrance pupil light beam, and the specific number needs to be set in accordance with actual needs.

Alternatively, the second beam splitter 121 and the second beam splitter 122 are symmetrically disposed along the first direction (indicated by X direction in the figure). By adopting the symmetrical structure, the parallel light beams which are emitted by the control light machine and carry virtual image information enter through the entrance pupil to sequentially reach the second beam splitter 121 and the second beam splitter 122, the left and right view field range formed by beam splitting is controlled, and full view field virtual image display is realized.

When second splitter 121 and second splitter 122 are symmetrically disposed along the first direction, the number of

second splitters

121 and 122 is equal. It is understood that the number of the second beam splitter 121 and the number of the second beam splitter 122 may not be equal, and the structural diagram of the second structural sub-part may be as shown in fig. 7.

It should be noted that adjacent beam splitters in the second structural subsection 12 may be fixedly attached by gluing. A certain gap may be formed between adjacent beam splitters in the second structural sub-portion 12 (as shown in fig. 6), as long as it can be ensured that parallel light beams carrying virtual image information emitted from the optical engine sequentially reach the second beam splitter 121 and the second beam splitter 122 through the entrance pupil, and the left and right field ranges formed by beam splitting are controlled, so as to realize full-field virtual image display.

In the second structural unit 12, the plurality of second beam splitters 121 and the plurality of second beam splitters 122 may be a single beam splitter or a plurality of mirror surfaces of one prism. For example, four sides of one quadrangular prism may serve as two second beam splitters 121 and two second beam splitters 122 as in fig. 5.

Optionally, the second beam splitters 121 are arranged in parallel and at equal intervals; the second plurality of second beam splitters 122 are arranged in parallel at equal intervals. The light machine is controlled to emit parallel light beams carrying virtual image information to sequentially reach the second beam splitter 121 and the second beam splitter 122 through entrance pupil incidence, and primary imaging is performed in the horizontal direction respectively, so that the imaging uniformity of virtual images is improved, and the visual imaging effect is improved.

On the basis of the above embodiment, as shown in fig. 5 to 8, optionally, an included angle between the second beam splitter and the first direction is α, and an included angle between the normal direction of the second beam splitter and the normal direction of the first plane is γ; the angle between the second beam splitter and the first direction is beta, and the angle between the normal direction of the second beam splitter and the normal direction of the first plane is gamma (not shown in the figure); the included angle between the second beam splitter and the second beam splitter is 180 degrees- (alpha + beta); an included angle between the normal direction of the fourth beam splitter and the normal direction of the first plane is theta;

Exemplarily, as shown in the front view and the left view of the pupil expanding device in fig. 5, the second beam splitter 121 is arranged to have an angle α with respect to the first direction (X direction in the figure), 0 < α <90 °, preferably, α ═ 45 °, the angle γ (not shown in the figure) between the normal direction of the second beam splitter and the normal direction of the first plane, 80 ° < γ <90 °, and the light beam incident on the entrance pupil reaches the second beam splitter 121 and is reflected to the first beam splitter 111 to form a left field of view light beam; an included angle between the second beam splitter 122 and the first direction is set to be β, 0 < β <90 °, preferably, β is 45 °, and an included angle between a normal direction of the second beam splitter 122 and a normal direction of the first plane is γ (not shown in the figure), so that a light beam incident on the entrance pupil reaches the second beam splitter 122 and is reflected to the third beam splitter 131 to form a left field of view light beam, and meanwhile, an included angle between the second beam splitter 121 and the second beam splitter 122 is set to be 180 ° - (α + β), so that the entrance pupil light beam completely irradiates the surfaces of the second beam splitter 121 and the second beam splitter 122, and the energy utilization rate of the entrance pupil light beam is improved.

Further, as shown in the left view of the pupil expanding device in fig. 5, in consideration of the most comfortable field of view of human eyes, the angle between the normal direction of the fourth beam splitter 21 and the normal direction of the first plane S1 is set to be θ, where θ is more than 20 and less than 28 °, and the exit pupil light beam reflected and coupled out by the fourth beam splitter 21 is adjusted to couple into the user' S eyes at the optimal viewing angle, so that the visual effect is optimal.

In conclusion, the pupil expanding device provided by the invention can increase the pupil expanding times of incident light rays in the horizontal direction and expand the pupil expanding range in the horizontal direction under the condition of keeping the angle of view, the eye box and the exit pupil distance unchanged by adding the second structure part, can effectively reduce the size of the two-dimensional waveguide sheet, realizes image display in a full field of view, is more suitable for the optimal visual position of human eyes, simultaneously reduces the machining difficulty and improves the light energy utilization rate.

Optionally, a certain proportion of reflective films are additionally plated on the surfaces of the second beam splitter 121 and the second beam splitter 122. In this structure, as shown in fig. 6, the parallel light beams carrying the virtual image information emitted from the optical engine enter the surface of the second structure subsection 12 through the entrance pupil and are split into a first part of light and a second part of light, and the entire visual field of the virtual image is split into two parts, i.e., a left visual field and a right visual field, by the second beam splitter 121 and the second beam splitter 122. In the right field of view direction, the first part of light is reflected by the 2 second beam splitters 121 and then sequentially reaches the plurality of first beam splitters 111 arranged in parallel, the light beam is turned for multiple times and then reaches the second waveguide structure 2 along the Y direction and then enters the eyes of the user, each second beam splitter 121 and each first beam splitter 111 form a primary image of the exit pupil, namely, the first pupil expansion is performed along the second beam splitter 121 in the horizontal direction, and the second pupil expansion is performed along the horizontal direction by the first beam splitter 111, so that the secondary pupil expansion of the right field of view in the horizontal direction is realized; in the left visual field direction, the second part of light rays are reflected by the second beam splitter 122 and then sequentially reach a plurality of third beam splitters 131 which are arranged in parallel, the light beams are turned for a plurality of times and then reach the second waveguide structure 2 and then enter the eyes of the user, each second beam splitter 122 and each third beam splitter 131 form primary images for the exit pupil, namely, the first pupil expansion is carried out on the second beam splitter 122 along the horizontal direction, and the second pupil expansion is carried out on the third beam splitters 131 along the horizontal direction, so that the secondary pupil expansion of the left visual field in the horizontal direction is realized; the light beam reaching the second waveguide structure 2 is sequentially deflected and coupled out to the eyes of the user by the plurality of fourth beam splitters 21 so as to be received by the eyes of the user, and each fourth beam splitter 21 forms an image once for the exit pupil and realizes the pupil expansion in the vertical direction, thereby realizing the full-field imaging of the virtual image information in the eyes of the user.

Through setting up a plurality of parallel arrangement's second beam splitter 121 and a plurality of parallel arrangement's second beam splitter 122 structure, change the visual field to the middle zone, the light beam gets into the middle zone of first waveguide structure 1 from the entrance pupil, this kind of mode that can realize will controlling the visual field separately transmission, the transmission that the height of first waveguide structure 1 (upper structure waveguide piece) only need satisfy half visual field just can realize the demonstration of full visual field, and in ordinary two-dimensional waveguide piece, the height of upper structure waveguide piece only needs to satisfy the transmission of whole visual field just can show complete image, therefore this kind of structure can reduce the volume of two-dimensional waveguide piece greatly, make people's eye position more close to the best position of watching the image simultaneously, not only, in the left and right structures, also can reduce beam splitter quantity, thereby reduce the processing degree of difficulty, improve the light energy utilization ratio. In addition, because the second structure subsection 12 (middle structure) also plays a role of pupil expansion for the first time in the horizontal direction, the distance between two beam splitters in the first waveguide structure 1 (upper structure) can be increased, the processing difficulty of the upper structure is indirectly reduced, and the field angle, the eye box and the exit pupil distance can be kept unchanged by adopting common low-refractive-index materials, so that the purpose of reasonably adjusting the imaging field range of the triple pupil expansion device and improving the visual experience of a user is achieved.

Optionally, the triple pupil expansion device further comprises a coupling-in structure 30; the incoupling structure 30 comprises a prism for incoupling the parallel light beams exiting the light engine into the second structural section 12. The capacity utilization rate of light can be improved, and the field-of-view imaging effect can be improved.

On the basis of the above embodiment, as shown in fig. 5 and 8, optionally, the number of the first beam splitter 111 is multiple. The plurality of first beam splitters 111 are sequentially arranged in parallel along a third direction (shown as an X direction in the figure), and the plurality of first beam splitters 111 extend along the fourth direction.

The number of the third beam splitter 131 may be plural, a plurality of the third beam splitters 131 are sequentially arranged in parallel along a fourth direction, and the plurality of the third beam splitters 131 extend along the third direction. The fourth beam splitter 21 includes a plurality of fourth beam splitters 21, and the plurality of fourth beam splitters 21 are sequentially arranged in parallel along the first direction (as shown in the Y direction in the figure).

Illustratively, the first structural subsection 11 and the third structural subsection 13 are symmetrically arranged along the first direction. Along the direction X in the figure, the plurality of first beam splitters 111 and the plurality of third beam splitters 131 are arranged at equal intervals, the light beam incident from the entrance pupil forms an image with equal intervals to the exit pupil after being split by the second structure subsection 12 and then is respectively bent by the plurality of first beam splitters 111 and the plurality of third beam splitters 131, so that the pupil expanding with equal intervals in the horizontal direction is realized, when the light beam reaches the plurality of fourth beam splitters 21 arranged in parallel at intervals, the beam splitting and the bending form an image with equal intervals, the image enters the eyes (eye boxes) of the user, the pupil expanding with equal intervals in the vertical direction is realized, the processing difficulty can be reduced on one hand through the parallel arrangement with equal intervals, the field angle is increased on the other hand, and the visual imaging effect of the user is improved.

Referring to the figures, a specific embodiment is listed below, and referring to fig. 9, a triple pupil expansion device provided by the above embodiment is adopted, and fig. 9 is a schematic left-view optical path diagram of a pupil expansion device provided by an embodiment of the present invention. Taking 7

first beam splitters

111, 7

third beam splitters

131, and 5 fourth beam splitters 21 as examples, the triple pupil expanding device provided by the embodiment of the present invention is adopted, referring to fig. 8, in combination with formula 1.3 and formula 1.4, where the length units in fig. 5-9 are: mm (millimeters):

n*sinαh_-in＝sinαh，(1.3)；

h≈L/2*tanαh_-in，(1.4)；

where n is the refractive index of the beam splitter, h is the height of the first waveguide structure 1 after decreasing in the first direction, α h is the longitudinal field angle of the exit pupil beam, α h_-inAt the longitudinal field angle of the exit pupil light beam in the second waveguide structure 2, 2L is the path length traveled by the light beam within the first waveguide structure 1.

As shown in fig. 9, by adding a plurality of second parallel beam splitters 121 and a plurality of second parallel beam splitters 122, the entrance pupil of the incident beam is incident from the middle area of the first waveguide structure 1, and the field of view is changed to the middle area, under the condition of keeping the field angle 55 °, the eye box 10 and the exit pupil distance 20 unchanged, the size of the two-dimensional waveguide plate can be effectively reduced, i.e. the height h of the first waveguide structure 1 is about 14.18mm, and compared with the height of the structural waveguide plate on the existing ordinary two-dimensional waveguide structure of 22.2mm, the height is reduced, the size is reduced, the processing difficulty and cost are reduced, the structure is more compact, and the light energy utilization rate is improved; the pupil expanding device not only expands the pupil for 2 times in the horizontal direction, but also expands the pupil once in the vertical direction, so that the full field range is expanded, the positions of human eyes are closer to the optimal positions for watching images, and the visual experience effect is improved.

It is to be noted that the foregoing description is only exemplary of the invention and that the principles of the technology may be employed. Those skilled in the art will appreciate that the present invention is not limited to the specific embodiments described herein, but rather, features of the various embodiments of the invention may be partially or fully coupled or combined with each other and yet still cooperate with each other and be technically driven in various ways. Numerous variations, rearrangements, combinations, and substitutions will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. The pupil expanding device is characterized by comprising a first plane, a second plane, a first waveguide structure and a second waveguide structure, wherein the first plane and the second plane are arranged in parallel, and the first waveguide structure and the second waveguide structure are arranged between the first plane and the second plane in sequence along a first direction; the first waveguide structure comprises a first structure subsection, a second structure subsection and a third structure subsection which are arranged in sequence along a second direction, and the first direction is parallel to the first plane;

2. The pupil expanding device according to claim 1, wherein the first structural subdivision comprises a plurality of first beam splitters, the plurality of first beam splitters being arranged in parallel one after the other in the third direction, and the plurality of first beam splitters extending in the fourth direction.

3. The pupil expanding device according to claim 2, wherein the third structural element comprises a plurality of third beam splitters, the plurality of third beam splitters being arranged in parallel one after another in the fourth direction, and the plurality of third beam splitters extending in the third direction.

4. The pupil expanding device according to claim 3, wherein the first and third structural sections are symmetrically arranged along the first direction.

5. The pupil expanding device according to claim 4, wherein the second waveguide structure comprises a plurality of fourth beam splitters, which are arranged in parallel in sequence along the first direction.

6. The pupil expanding device according to claim 5, wherein a plurality of the first beam splitters are sequentially arranged in parallel at equal intervals along the second direction;

the third beam splitters are arranged in parallel along the second direction at equal intervals in sequence;

7. The pupil expanding device according to claim 1, wherein the second sub-mirror and the second sub-mirror are symmetrically arranged along the first direction.

8. The pupil expanding device according to claim 1, wherein a plurality of the second sub-beam splitters are equally spaced; the second beam splitters are arranged at equal intervals.

9. The pupil expanding device according to claim 5, wherein the fourth direction is at an angle α to the first direction, and the normal direction of the second beam splitter is at an angle γ to the normal direction of the first plane; an included angle between the third direction and the first direction is beta, and an included angle between the normal direction of the second beam splitter and the normal direction of the first plane is gamma; the angle between the third direction and the fourth direction is 180 ° - (α + β);

10. The pupil expanding device according to claim 1, characterized in that it further comprises a coupling structure;

the coupling-in structure comprises a triangular prism and is used for coupling parallel light beams emitted by the light machine into the second structure subsection.