CN118426101A - Light guide devices and wearable devices - Google Patents

Abstract

The embodiment of the application discloses a light guide device and wearable equipment; the light guide device comprises a waveguide substrate, and a coupling-in area, a coupling-out area and a pupil expansion area which are arranged on the waveguide substrate; the pupil expansion area is arranged on the surface of the waveguide substrate and along the peripheral side, or embedded into the waveguide substrate and arranged along the thickness direction of the waveguide substrate; the coupling-in area is used for coupling light into the waveguide substrate and enabling the light to propagate in the waveguide substrate in a total reflection mode; the coupling-out region is used for coupling out the light rays transmitted to the coupling-out region; the pupil expansion area is used for expanding the pupil of the light reflected by the side wall of the waveguide substrate and then transmitting the light to the coupling-out area. The light guide device provided by the embodiment of the application can reduce the occupied area of the diffraction element on the surface of the waveguide substrate, is beneficial to enabling the structure of the optical waveguide to be more compact, and can also improve the transmittance of ambient light when the light guide device is used.

Description

Light guide devices and wearable devices

Technical Field

The present application relates to the field of near-eye display technology, and more specifically, to a light guide device and a wearable device.

Background technique

Optical waveguide components are the core components of augmented reality (AR) devices. Optical waveguide components mainly use the principle of total reflection to achieve light transmission, and combined with diffraction optical elements, they achieve directional transmission of light, and then guide the imaging light to the human eye, so that users can see the projected image.

In the prior art, in order to meet the needs of people with different eye distances, the optical waveguide must not only meet the requirements of light transmission, but also have the function of beam expansion. This requires the provision of multiple diffraction gratings on the surface of the waveguide substrate. For example, an in-coupling grating, a turning grating, and an out-coupling grating are provided on the surface of the waveguide substrate. However, in the design of a diffraction optical waveguide, an independent turning grating area generally occupies a larger space in the optical waveguide, which limits the design space of the optical waveguide and also affects the transmittance of ambient light when the AR device is in use.

Summary of the invention

The purpose of the present application is to provide a new technical solution for a light-guiding device and a wearable device, which helps to make the structure of the light-guiding device compact by reasonably setting the pupil expansion area, and at the same time improves the transmittance of ambient light when the light-guiding device is in use.

According to a first aspect of the present application, a light guide device is provided, the light guide device comprising a waveguide substrate and an incoupling region, an outcoupling region and a pupil expansion region arranged on the waveguide substrate;

Wherein, the pupil expansion area is arranged on the surface of the waveguide substrate and arranged along the peripheral side, or is embedded in the waveguide substrate and arranged along the thickness direction of the waveguide substrate;

The coupling-in region is used to couple light into the waveguide substrate, and make the light propagate in the waveguide substrate in a total reflection manner;

The outcoupling region is used to outcouple the light propagating to the outcoupling region;

The pupil expansion area is used to expand the pupil of the light reflected by the side wall of the waveguide substrate and then propagate it to the outcoupling area.

Optionally, the pupil expansion area includes a first diffraction element, which is located on a surface of the waveguide substrate and arranged close to a first side edge of the surface; wherein the first side edge is arranged along the length direction of the waveguide substrate.

Optionally, the light guide device further comprises a turning area, and the turning area comprises a second diffraction element;

The turning zone is located between the pupil expansion zone and the outcoupling zone, and the turning zone is used to modulate the propagation direction of the light after the pupil expansion in the pupil expansion zone, so that the light after the pupil expansion can propagate toward the outcoupling zone.

Optionally, the turning area and the pupil expansion area are adjacent to and close to each other.

Optionally, the first diffraction element and the second diffraction element are configured as one-dimensional gratings.

Optionally, the pupil expansion area includes a spectroscopic device, which is located in the waveguide substrate and is adjacent to and spaced apart from a side wall of the waveguide substrate, and the side wall is arranged along the length direction of the waveguide substrate.

Optionally, the light splitting device is configured as a semi-reflective and semi-transparent membrane, and the configuration direction of the semi-reflective and semi-transparent membrane is perpendicular to two surfaces of the waveguide substrate.

Optionally, a mirror reflector is at least partially disposed on the side wall of the waveguide substrate, and the pupil expansion area is disposed opposite to the mirror reflector.

Optionally, the coupling-in region and the coupling-out region are located on the same surface of the waveguide substrate; or,

The coupling-in region and the coupling-out region are arranged on two surfaces of the waveguide substrate.

Optionally, the light coupled into the waveguide substrate through the coupling-in region propagates in a total reflection manner after diffraction, and the light is divided into a first light and a second light, and the first light and the second light are respectively a primary light and a secondary light of the same field of view;

At least one of the first light and the second light is totally reflected to the pupil expansion area after encountering the side wall of the waveguide substrate. After the pupil is expanded once in the pupil expansion area, the light after the pupil expansion is divided into reflected light and diffracted light. The reflected light propagates to the outcoupling area and is coupled out. The diffracted light is totally reflected by the side wall of the waveguide substrate and returns to the pupil expansion area.

Optionally, an in-coupling grating is provided in the in-coupling region, and an out-coupling grating is provided in the out-coupling region;

The coupling-in grating and the coupling-out grating are both configured as one-dimensional gratings.

According to a second aspect of the present application, a wearable device is also provided, including:

The light guide device as described in the first aspect;

an optical machine, the optical machine being used to inject light or an image into the coupling-in region; and

The housing is provided with the light guide device and the optical machine inside the housing.

The beneficial effects of this application are:

The light-guiding device solution proposed in the embodiment of the present application utilizes the side edge of the surface of the waveguide substrate or the side wall of the waveguide substrate to arrange a pupil expansion area. In conjunction with the light reflected by the side wall of the waveguide substrate, pupil expansion occurs in the pupil expansion area. This can reduce the area of the pupil expansion area while achieving a good light pupil expansion effect. The light originally reflected by the side wall of the waveguide substrate can be utilized, reducing the waste of light energy. Moreover, the reduction in the area of the pupil expansion area can also increase the transmittance of the entire light-guiding device, thereby improving the optical performance of the entire light-guiding device.

Other features and advantages of the present application will become apparent from the following detailed description of exemplary embodiments of the present application with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present application and, together with the description, serve to explain the principles of the present application.

FIG1 is a schematic diagram of a structure of a light guide device according to an embodiment of the present application;

FIG2 is a top view of the light guide device shown in FIG1 ;

FIG3 is a K-Space distribution diagram of the light guide device shown in FIG1 ;

FIG4 is a schematic diagram of a light propagation path of an outcoupling region in the light guide device shown in FIG1 ;

FIG5 is a second schematic diagram of the structure of the light guide device provided in an embodiment of the present application;

FIG6 is a K-Space distribution diagram of the light guide device shown in FIG5 ;

FIG7 is a third schematic diagram of the structure of the light guide device provided in an embodiment of the present application;

FIG. 8 is a fourth schematic diagram of the structure of the light guide device provided in an embodiment of the present application.

Description of reference numerals:

1. Waveguide substrate; 11. Side wall; 12. First side; 2. Incoupling region; 21. Incoupling grating; 3. Outcoupling region; 31. Outcoupling grating; 4. Pupil expansion region; 41. First diffraction element; 5. Turning region; 51. Second diffraction element; 6. Mirror reflector; 01. Light; 011. First light; 012. Second light.

Detailed ways

Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that unless otherwise specifically stated, the relative arrangement of components and steps, numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present application.

The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present application, its application, or uses.

Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered as part of the specification.

In all examples shown and discussed herein, any specific values should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

The light guide device and the wearable device provided in the embodiments of the present application are described in detail below with reference to the accompanying drawings.

Among various forms of wearable devices, AR head-mounted display devices are taken as an example. AR head-mounted display devices usually include a micro display screen and an optical module. The commonly used optical elements in the optical module of AR head-mounted display devices include prisms, free-form lenses, and optical waveguide devices. Among the above-mentioned optical elements, optical waveguide devices include geometric optical waveguides and diffraction optical waveguides. Due to the good optical properties of diffraction optical waveguides, they have been widely used in AR head-mounted display devices. However, most diffraction optical waveguides currently have problems such as obvious dispersion and low diffraction efficiency.

According to an embodiment of the present application, a light guide device solution is proposed, and the light guide device is, for example, an optical waveguide device. The light guide device proposed in the embodiment of the present application can be applied to a wearable device, for example. The wearable device includes a head-mounted display device, and the head-mounted display device is, for example, AR smart glasses, AR helmets, etc.

The light guide device provided in the embodiment of the present application, as shown in FIG. 1 , FIG. 5 , FIG. 7 and FIG. 8 , comprises a waveguide substrate 1 and an incoupling region 2, an outcoupling region 3 and a pupil expansion region 4 provided on the waveguide substrate 1; wherein the pupil expansion region 4 is provided on the surface of the waveguide substrate 1 and arranged along the circumference, or is embedded in the waveguide substrate 1 and arranged along the thickness direction of the waveguide substrate 1;

The coupling-in zone 2 is used to couple the light 01 into the waveguide substrate 1, and make the light 01 propagate in the waveguide substrate 1 in a total reflection manner; the coupling-out zone 3 is used to couple out the light 01 propagated to the coupling-out zone 3; the pupil expansion zone 4 is used to propagate the light reflected by the side wall of the waveguide substrate 1 to the coupling-out zone 3 after the pupil is expanded.

According to the technical solution of the light-guiding device provided in the above-mentioned embodiment of the present application, a pupil expansion area 4 is arranged by utilizing the edge portion of the surface of the waveguide substrate 1 (for example, the first side 12 shown in FIG. 1 ) or a position close to the side wall 11 of the waveguide substrate 1. In conjunction with the light reflected by the side wall 11 of the waveguide substrate 1, pupil expansion can occur in the pupil expansion area 4. In this way, the area of the pupil expansion area 4 can be designed to be relatively small (the size of the pupil expansion area 4 is relatively small), while also having the light pupil expansion effect.

In the embodiment of the present application, the light originally reflected by the side wall 11 of the waveguide substrate 1 can be used to expand the pupil, thereby reducing the waste of light energy. Moreover, when the size of the pupil expansion area 4 is designed to be small, the transmittance of the entire light guide device can be improved, thereby improving the optical performance of the entire light guide device.

The above-mentioned embodiment of the present application proposes a compact diffraction light waveguide structure design. Although the light guide device is provided with a plurality of different functional areas, such as the coupling-in area 2, the coupling-out area 3 and the pupil expansion area 4, etc., the entire light guide device can be different from the traditional diffraction light waveguide by reasonably arranging the position of the pupil expansion area 4 and reducing the size. Specifically, by utilizing the position of the surface side edge or side wall 11 of the waveguide substrate 1, combined with at least one pupil expansion, the effect of light beam expansion is taken into account while reducing the area of the pupil expansion area 4. Moreover, based on the setting position of the pupil expansion area 4, the light reflected by the side wall of the waveguide substrate 1 can also be utilized, and this part of the light is originally wasted, thereby improving the light efficiency.

That is to say, the light-guiding device provided in the embodiment of the present application utilizes the space on the side of the waveguide substrate 1 and combines it with the pupil expansion design. The two work together to effectively reduce the size of the pupil expansion area 4 while achieving the light beam expansion effect.

When the pupil expansion area 4 is small in size, the space occupied on the waveguide substrate 1 can be greatly saved to avoid large-area/large-size obstruction. In this way, the transmittance of ambient light when the light-guiding device is in use can be improved, which can improve the brightness and clarity of the image and help improve the user's visual experience.

In addition, the light guide device provided in the embodiment of the present application has a simple structural design and does not increase production costs.

In some examples of the present application, referring to FIG. 1 and FIG. 2 , the pupil expansion area 4 includes a first diffraction element 41, which is located on a surface of the waveguide substrate 1 and is arranged close to a first side edge 12 of the surface; wherein the first side edge 12 is arranged along the length direction of the waveguide substrate 1.

The waveguide substrate 1 of the light guide device is, for example, a thin sheet structure, and the waveguide substrate 1 includes two surfaces and a side portion. The pupil expansion area 4 can be configured as an optical diffraction element such as a diffraction grating.

Specifically, when the pupil expansion area 4 is set as the above-mentioned first diffractive optical element (i.e., diffraction grating), the pupil expansion area 4 can be arranged on a surface of the waveguide substrate 1 and close to one side of the surface, referring to Figures 1 and 2, the pupil expansion area 4 is, for example, located close to the first side edge 12 on the surface. The pupil expansion area 4 can be designed as a strip structure, for example, which is small in size and does not occupy too much space on the surface of the waveguide substrate 1.

It should be noted that the pupil expansion area 4 is designed to be located on the side edge of a surface of the waveguide substrate 1, which is conducive to utilizing the light reflected by the side wall 11 of the waveguide substrate 1 to expand the pupil, and the light that was originally wasted can be utilized, thereby improving the light efficiency and avoiding the waste of light energy.

Refer to Figure 3, which is a K-Space diagram of light propagation of the light-guiding device provided in the above example, which shows the light vector propagation process. Specifically, the radial direction size in Figure 3 represents the sine value of the vertex angle of the light direction. Therefore, the annular area in Figure 3 represents the range in which the light is allowed to propagate in the waveguide substrate 1 by total reflection. Among them, the central rectangular area represents the field of view of the transmitted image. Under the action of the coupling-in area 2, the light 01 enters the total reflection annular area shown in Figure 3. It should be noted that the entire field of view cannot exceed the total internal reflection critical angle A1 of the first side 12 marked by the dotted line in Figure 3, otherwise part of the light in the field of view will not be able to complete the total internal reflection at the first side 12 and leak out of the waveguide substrate 1. The path that the light 01 takes from the coupling-in area 2 to the waveguide substrate 1 and then to the coupling-out area 3 to the outside of the waveguide substrate 1 is as follows:

The coupling-in area 2 is diffraction modulated - (total reflection propagation in the waveguide substrate 1 - pupil dilation modulation in the pupil dilation area 4) the waveguide substrate 1 is totally reflected and propagated - the coupling-out area 3 is diffraction modulated and then coupled out; wherein, the path shown in the brackets can be 0 times, 1 time or multiple times. For example, the design in this application is once, which can reduce the size design of the pupil dilation area 4.

It can be seen from the grating vector relationship shown in FIG. 3 that the vector direction of the pupil expansion area 4 is, for example, along the y-axis direction, and the sum of the vectors of the coupling-in area 2 , the coupling-out area 3 and the pupil expansion area 4 is zero.

Referring to FIG. 4 , FIG. 4 is a schematic diagram showing the light beam expansion and outcoupling in the outcoupling region 3 . It can be seen that the light beam can be evenly outcoupled at the same diffraction angle, so that the human eye can see a clear and complete picture.

In addition, it should be noted that the present application does not limit the first diffraction element 41 to be disposed on the first side edge 12 on the surface of the waveguide substrate 1 , and may also be disposed on other side edges as required.

In some examples of the present application, referring to FIG. 5 , the light guiding device further includes a turning zone 5, which includes a second diffraction element 51; the turning zone 5 is located between the pupil expansion zone 4 and the outcoupling zone 3, and the turning zone 5 is used to modulate the propagation direction of the light after pupil expansion in the pupil expansion zone 4, so that the light after pupil expansion can propagate toward the outcoupling zone 3.

In the above example, four areas are arranged on the waveguide substrate 1, including: a coupling-in area 2, a coupling-out area 3, a pupil expansion area 4 and a turning area 5; wherein the coupling-in area 2 serves to couple the light 01 into the waveguide substrate 1, the coupling-out area 3 serves to couple the light 01 out of the waveguide substrate 1, the pupil expansion area 4 serves to expand the light beam, and the newly introduced turning area 5 serves to turn the light beam.

The principle of the above example is basically the same as the principle of the example shown in Figures 1 and 2, with the difference being that an additional turning zone 5 is provided on the waveguide substrate 1, and the turning zone 5 can be used to modulate the propagation direction of the light modulated in the pupil expansion zone 4, so that the light after the pupil expansion can be concentrated and coupled into the outcoupling zone 3 in large quantities, thereby increasing the outcoupling light without designing a larger pupil expansion zone 4, which is also conducive to the compact layout of the functional areas on the waveguide substrate 1, thereby reducing the space occupied on the waveguide substrate 1, thereby facilitating the miniaturization design of the entire light-guiding device.

Referring to the light-guiding device shown in FIG5 , the path that the light 01 takes from the coupling-in area 2 into the waveguide substrate 1, and then coupled out of the waveguide substrate 1 through the coupling-out area 3 is: the coupling-in area 2 diffraction modulation - (the waveguide substrate 1 total reflection propagation - the pupil dilation area 4 pupil dilation modulation -) the waveguide substrate 1 total reflection propagation - the turning area 5 modulates the light propagation direction - the coupling-out area 3 diffraction coupling; wherein, the path shown in brackets can be 0 times, 1 time or multiple times. For example, in the embodiment of the present application, it is designed to be once, which can reduce the size design of the pupil dilation area 4.

Optionally, the turning area 5 and the pupil expansion area 4 are adjacent to and close to each other.

The above design can make the turning area 5 and the pupil expansion area 4 more compact, which can reduce the occupied area and help to achieve a compact structure of the entire light guide device, thereby reducing the volume.

Optionally, the first diffraction element 41 and the second diffraction element 51 are configured as one-dimensional gratings.

For example, the pupil expansion area 4 and the turning area 5 both adopt one-dimensional gratings.

The above-mentioned one-dimensional grating types include but are not limited to surface relief grating, step grating, tilted grating, blazed grating or holographic grating, etc. Among them, the blazed grating includes sinusoidal grating, etc. The holographic grating includes liquid crystal grating, polymer grating, polymer dispersed liquid crystal grating, etc.

The grating period range of the first diffraction element 41 and the second diffraction element 51 is set to be, for example, 200 nm-1000 nm, which is applicable to the visible light band (390 nm-780 nm).

In the embodiment of the present application, the wavelength of the light 01 is within the visible light range (390nm-780nm), and the polarization state of the light 01 includes polarized coherent light and unpolarized light.

The first diffraction element 41 and the second diffraction element 42 may be the same or different, which is not limited in the embodiment of the present application.

Referring to Fig. 6, Fig. 6 shows a light propagation K-Space diagram of the light guide device in Fig. 5, which shows the relationship of the grating vectors in this example. Similar to the example shown in Fig. 1, the grating vector of the pupil expansion area 4 is along the y-axis direction, and the sum of the grating vector K1 of the coupling-in area 2, the grating vector K2 of the coupling-out area 3, and the grating vector K3 of the pupil expansion area 4 is zero.

In some examples of the present application, referring to FIG. 8 , the pupil expansion area 4 includes a spectroscopic device 42 , which is located in the waveguide substrate 1 and is adjacent to and spaced apart from the side wall 11 of the waveguide substrate 1 , and the side wall 11 is arranged along the length direction of the waveguide substrate 1 .

Optionally, the light splitting device is configured as a semi-reflective and semi-transparent membrane, and the configuration direction of the semi-reflective and semi-transparent membrane is perpendicular to the two surfaces of the waveguide substrate 1 .

FIG8 is another example of the present application, in which the pupil expansion area 4 uses a beam splitter 42 instead of a diffraction solution, and the beam splitter 42 is designed to transmit part of the light and reflect part of the light. This design can reduce the dispersion of the light and help improve the optical performance of the outcoupled light.

For example, the light splitting device 42 is configured as the above-mentioned semi-reflective and semi-transmissive membrane, and the transmittance of the semi-reflective and semi-transmissive membrane may be 47% to 53%.

Specifically, the semi-reflective and semi-transmissive membrane can be supported by a glass plate and disposed in the waveguide substrate 1 , and disposed close to the side wall 11 of the waveguide substrate 1 .

It should be noted that the side wall 11 includes but is not limited to being arranged along the length direction of the waveguide substrate 1 .

Optionally, referring to FIG. 7 and FIG. 8 , a mirror reflector 6 is at least partially disposed on the side wall 11 of the waveguide substrate 1 , and the pupil expansion area 4 and the mirror reflector 6 are disposed opposite to each other.

The mirror reflector 6 on the side wall 11 of the waveguide substrate 1 can be realized by plating silver nitrate or aluminum alloy.

A mirror reflector 6 is provided, and the light 01 does not necessarily need to meet the total internal reflection condition of the side wall when reflecting on the side wall 11 (as shown by the dotted line in the K-space diagram of FIG3 ). Therefore, the reflection angle on the side wall 11 can be smaller than the example shown in FIG1 , so that the light beam is expanded more times in the pupil expansion area 4 .

It should be noted that the mirror reflector 6 is also applicable to the example shown in FIG. 4 .

In some examples of the present application, the coupling-in region 2 and the coupling-out region 3 are located on the same surface of the waveguide substrate 1 ; or, the coupling-in region 2 and the coupling-out region 3 are located on two surfaces of the waveguide substrate 1 .

In a specific example, referring to FIG. 1 and FIG. 2, the optical propagation path of the light guide device is as follows: the light 01 coupled into the waveguide substrate 1 through the coupling-in area 2 is propagated in a total reflection manner after diffraction, and the light 01 is divided into a first light 011 and a second light 012, and the first light 011 and the second light 012 are respectively the main light and the secondary light of the same field of view; at least one of the first light 011 and the second light 012 is totally reflected to the pupil expansion area 4 after encountering the side wall 11 of the waveguide substrate, and after a pupil expansion occurs once in the pupil expansion area 4, the light after the pupil expansion is divided into reflected light and diffracted light, and the reflected light is propagated to the coupling-out area 3 and then coupled out, and the diffracted light is returned to the pupil expansion area 4 after being totally reflected by the side wall 11 of the waveguide substrate 1.

In some examples of the present application, an in-coupling grating 21 is disposed in the in-coupling region 2, and an out-coupling grating 31 is disposed in the out-coupling region 3; the in-coupling grating 21 and the out-coupling grating 31 are both configured as one-dimensional gratings.

The above-mentioned one-dimensional grating types include but are not limited to surface relief grating, step grating, tilted grating, blazed grating or holographic grating, etc. Among them, the blazed grating includes sinusoidal grating, etc. The holographic grating includes liquid crystal grating, polymer grating, polymer dispersed liquid crystal grating, etc.

The grating period range of the coupling-in grating 21 and the coupling-out grating 31 is set to be, for example, 200 nm-1000 nm, which is applicable to the visible light band (390 nm-780 nm).

In the embodiment of the present application, the wavelength of the light 01 is within the visible light range (390nm-780nm), and the polarization state of the light 01 includes polarized coherent light and unpolarized light.

In addition, in order to obtain better optical performance, in the light-guiding device provided in the embodiment of the present application, the area where the diffraction grating is used can be zoned and designed based on parameters such as grating thickness, duty cycle, grating tilt angle, coating depth, coating material, volume grating Bragg tilt angle, and refractive index of the volume grating material.

The embodiment of the present application further provides a wearable device. The wearable device comprises:

The light guide device as described above;

An optical machine, the optical machine is used to inject light or an image into the coupling-in area 2; and

The housing is provided with the light guide device and the optical machine inside the housing.

The head mounted display device is, for example, an AR device. The AR device includes AR smart glasses or an AR smart helmet, etc., which is not limited in this application.

The specific implementation of the wearable device of the embodiment of the present application can refer to the embodiment of the light guide device mentioned above, so it at least has all the beneficial effects brought by the technical solution of the above embodiment, which will not be repeated here one by one.

The above embodiments focus on the differences between the various embodiments. As long as the different optimization features between the various embodiments are not contradictory, they can be combined to form a better embodiment. Considering the simplicity of the text, they will not be repeated here.

Although some specific embodiments of the present application have been described in detail by way of example, it should be understood by those skilled in the art that the above examples are only for illustration, not for limiting the scope of the present application. It should be understood by those skilled in the art that the above embodiments may be modified without departing from the scope and spirit of the present application. The scope of the present application is defined by the appended claims.

Claims (12)

1. A light guide device, characterized in that it comprises a waveguide substrate (1) and an incoupling region (2), an outcoupling region (3) and a pupil expansion region (4) arranged on the waveguide substrate (1); The pupil expansion area (4) is arranged on the surface of the waveguide substrate (1) and along the circumference, or is embedded in the waveguide substrate (1) and arranged along the thickness direction of the waveguide substrate (1); The coupling-in region (2) is used to couple the light (01) into the waveguide substrate (1), and to make the light (01) propagate in the waveguide substrate (1) in a total reflection manner; The outcoupling region (3) is used to outcouple the light (01) propagating to the outcoupling region (3); The pupil expansion area (4) is used to expand the pupil of the light reflected by the side wall (11) of the waveguide substrate (1) and then propagate it to the outcoupling area (3). 2. The light-guiding device according to claim 1 is characterized in that the pupil expansion area (4) comprises a first diffraction element (41), and the first diffraction element (41) is located on a surface of the waveguide substrate (1) and is arranged close to a first side edge (12) of the surface; wherein the first side edge (12) is arranged along the length direction of the waveguide substrate (1). 3. The light guide device according to claim 2, characterized in that the light guide device further comprises a turning zone (5), and the turning zone (5) comprises a second diffractive element (51); The turning zone (5) is located between the pupil expansion zone (4) and the outcoupling zone (3), and the turning zone (5) is used to modulate the propagation direction of the light after the pupil is expanded by the pupil expansion zone (4), so that the light after the pupil is expanded can propagate toward the outcoupling zone (3). 4. The light guide device according to claim 3, characterized in that the turning area (5) and the pupil expansion area (4) are adjacent to and close to each other. 5. The light-guiding device according to claim 3, characterized in that the first diffraction element (41) and the second diffraction element (51) are configured as one-dimensional gratings. 6. The light-guiding device according to claim 1 is characterized in that the pupil expansion area (4) includes a spectrometer (42), the spectrometer (42) is located in the waveguide substrate (1), and is adjacent to and spaced apart from the side wall (11) of the waveguide substrate (1), and the side wall (11) is arranged along the length direction of the waveguide substrate (1). 7. The light-guiding device according to claim 6, characterized in that the light-splitting device is configured as a semi-reflective and semi-transparent membrane, and the configuration direction of the semi-reflective and semi-transparent membrane is perpendicular to the two surfaces of the waveguide substrate (1). 8. The light-guiding device according to any one of claims 1 to 7, characterized in that a mirror reflector (6) is at least partially provided on the side wall (11) of the waveguide substrate (1), and the pupil expansion area (4) and the mirror reflector (6) are arranged opposite to each other. 9. The light-guiding device according to claim 8, characterized in that the coupling-in region (2) and the coupling-out region (3) are located on the same surface of the waveguide substrate (1); or, The coupling-in region (2) and the coupling-out region (3) are respectively arranged on two surfaces of the waveguide substrate (1). 10. The light guide device according to claim 1, characterized in that the light (01) coupled into the waveguide substrate (1) through the coupling-in region (2) propagates in a total reflection manner after diffraction, and the light (01) is divided into a first light (011) and a second light (012), and the first light (011) and the second light (012) are respectively the primary light and the secondary light of the same field of view; At least one of the first light ray (011) and the second light ray (012) is totally reflected to the pupil expansion area (4) after encountering the side wall (11) of the waveguide substrate. After the pupil is expanded once in the pupil expansion area (4), the light after the pupil expansion is divided into reflected light and diffracted light. The reflected light propagates to the outcoupling area (3) and is coupled out. The diffracted light is totally reflected by the side wall (11) of the waveguide substrate (1) and then returns to the pupil expansion area (4). 11. The light-guiding device according to claim 1, characterized in that an in-coupling grating (21) is arranged in the in-coupling region (2), and an out-coupling grating (31) is arranged in the out-coupling region (3); The coupling-in grating (21) and the coupling-out grating (31) are both configured as one-dimensional gratings. 12. A wearable device, comprising: The light guide device according to any one of claims 1 to 11; An optical machine, the optical machine is used to inject light or an image into the coupling region (2); and The housing is provided with the light guide device and the optical machine inside the housing.