CN219799825U - Light guide system, light source device and display equipment - Google Patents

Abstract

The utility model relates to a light guide system, a light source device and display equipment. The surface of the optical waveguide is provided with a coupling-in area and a coupling-out area, the optical waveguide is provided with a first surface and a second surface which are opposite, the coupling-in area is arranged on the first surface, and the coupling-in area and the coupling-out area are arranged at intervals in the light propagation direction defined by the optical waveguide. The first coupling-in device is arranged in the coupling-in area and is used for being opposite to the light source, and the first coupling-in device is sensitive to light of a first polarization state. The quarter wave plate is arranged opposite to the second surface at intervals, and the quarter wave plate is positioned on the light path of the light with the second polarization state penetrating the optical waveguide. The reflecting mirror is arranged on one side of the quarter wave plate, which is far away from the optical waveguide, and the second polarized light reflected by the reflecting mirror is converted into the first polarized light after passing through the quarter wave plate again and enters the optical waveguide to propagate along the light propagation direction. The light guide system provided by the utility model can improve the coupling-in efficiency.

Description

Light guide system, light source device and display equipment

Technical field

The present application relates to the field of light-emitting display technology, and in particular to a light guide system, a light source device and a display device.

Background technique

Augmented reality is a display technology that collects real-world information in real time and combines virtual information, images, etc. with the real world. The micro-optical machine used in augmented reality equipment is a device used to generate image light. The micro-projection system of LCoS (liquid crystal on silicon) and DMD (digital micromirror device) is the mainstream of non-active light-emitting chip projection solutions. For non-active light-emitting chips, illumination waveguides can be used to uniformly illuminate the light beam emitted by the light source on the surface of LCoS and DMD chips according to a preset path, thereby generating high-quality projection images.

When using LCoS as an image modulator, the polarization state of the illumination beam must be a single polarization state. When the incident light source is unpolarized light, a polarizer is generally used to convert the incident light into a single polarization state. However, the polarization efficiency of this solution is generally less than 50%, which will cause serious loss of light source energy, increase the overall energy consumption of the optical machine, affect battery life, and increase the heat generated by the optical machine.

Utility model content

Embodiments of the present application provide a light guide system, a light source device and a display device.

In a first aspect, embodiments of the present application provide a light guide system for guiding light emitted by a light source to a target location. The light includes a first polarized light and a second polarized light with different polarization states. The light guide system includes a light Waveguide, first coupling device, quarter wave plate and reflector. The surface of the optical waveguide is provided with a coupling-in area and a coupling-out area. The optical waveguide has a first surface and a second surface that are opposite to each other. The coupling-in area is arranged on the first surface. The coupling-in area and the coupling-out area are defined by the optical waveguide. Interval settings in the direction of light propagation. The first coupling device is disposed in the coupling area and is used to be opposite to the light source. The first coupling device is sensitive to the first polarized light, so that after the light is coupled into the optical waveguide through the first coupling device, the first polarized light Able to propagate along the direction of light propagation, the second polarized light penetrates the optical waveguide. The quarter-wave plate is spaced apart from the second surface, and the quarter-wave plate is located on an optical path where the second polarized light penetrates the optical waveguide. The reflector is disposed on a side of the quarter-wave plate away from the optical waveguide and is used to reflect the second polarized light that penetrates the quarter-wave plate. The second polarized light reflected by the reflector passes through the quarter-wave plate again. After a wave plate, it is converted into the first polarized light, enters the optical waveguide, and propagates along the light propagation direction.

In some optional embodiments, the diffraction efficiency of the first coupling device for the first polarized light is greater than or equal to 50%.

In some optional embodiments, the diffraction efficiency of the first coupling device for the second polarized light is less than or equal to 5%.

In some optional embodiments, the outcoupling region is provided with a first outcoupling device, and the first outcoupling device includes at least one of the following structures: surface relief grating, Bragg grating, holographic volume grating, metasurface, photonic crystal, diffraction Optical element.

In some optional embodiments, the light guide system further includes a second coupling device, the second coupling device is disposed on the second surface, the second coupling device is located on the optical path of the light reflected by the mirror to the optical waveguide, and the second coupling device is disposed on the second surface. A polarized light is incident on the second coupling device and diffracted; the second polarized light reflected by the mirror is converted into the first polarized light through the quarter wave plate, and is coupled into the light through the second coupling device waveguide.

In some optional embodiments, the light guide system further includes a second coupling device. The second coupling device is disposed on the second surface or/and the first surface and is located between the coupling region and the coupling region. The optical waveguide The second polarized light is coupled out through the second coupling device.

In some optional embodiments, the second outcoupling device includes at least one of the following structures: grating, metasurface, photonic crystal, diffractive optical element.

In some optional embodiments, the first coupling device includes at least one of the following structures: grating, metasurface, photonic crystal, diffractive optical element.

In a second aspect, embodiments of the present application also provide a light source device, which includes a light source and any one of the above light guide systems. The light source is disposed on a side of the optical waveguide with a coupling area, and the light source is opposite to the first coupling device.

In some optional embodiments, the light source includes an unpolarized light source, the first polarized light is s-polarized light, and the second polarized light is p-polarized light; or the light source includes an unpolarized light source, and the first polarized light is p-polarized light. , the second polarized light is s-polarized light.

In a third aspect, embodiments of the present application further provide a display device, including any one of the above light source devices, a display, and a projection lens. The display is disposed on the side of the optical waveguide that is provided with the outcoupling area and is opposite to the outcoupling area; projection The lens is arranged on the side of the optical waveguide away from the display.

In some optional embodiments, the display device further includes a polarizer, which is disposed between the projection lens and the optical waveguide; the display includes bright pixels and dark pixels, and the bright pixels are used to modulate the first polarized light into the second The dark pixel is used to reflect the first polarized light, and the analyzer is used to block the first polarized light from propagating to the projection lens.

Compared with the existing technology, the light guide system provided by the embodiment of the present application is applied to the light source device. When working, the light source emits a light beam, and the light is incident on the first coupling device. The first polarized light in the incident light is diffracted and enters. The light propagates along the direction of light propagation in the optical waveguide. The second polarized light penetrates the optical waveguide and is reflected by the mirror and is coupled into the optical waveguide again. During this process, the quarter wave plate converts the second polarized light into the first Polarized light. The characteristic of the first coupling device being sensitive to the first polarized light is used to propagate the second polarized light out of the optical waveguide. Under the action of the quarter wave plate and the reflector, the second polarized light is converted into the first polarized light. The light is then coupled into the optical waveguide again to improve the coupling efficiency, thus improving the energy transfer efficiency of the entire light guide system.

Description of the drawings

In order to explain the technical solution of the present application more clearly, the following will briefly introduce the drawings required for the implementation. Obviously, the drawings in the following description are only some implementations of the present application. For ordinary people in the art, For technical personnel, other drawings can also be obtained based on these drawings without exerting creative work.

FIG. 1 is a simplified structural schematic diagram of a display device provided by an embodiment of the present application.

FIG. 2 is a simplified structural schematic diagram of a light guide system provided by an embodiment of the present application.

FIG. 3 is a schematic structural diagram of the optical waveguide of the light guide system shown in FIG. 2 .

FIG. 4 is a schematic structural diagram of another embodiment of the light guide system shown in FIG. 2 .

FIG. 5 is a schematic structural diagram of another embodiment of the light guide system shown in FIG. 2 .

Marking description: 100. Light guide system; 10. Optical waveguide; 12. Coupling area; 14. Coupling area; 16. First surface; 17. Side wall; 18. Second surface; 20. First coupling device ; 30. First coupling out device; 40. Quarter wave plate; 50. Reflector; 60. Second coupling device; 70. Second coupling out device; 200. Light source device; 201. Light source; 300. Display device; 301, monitor; 3012, bright pixels; 3014, dark pixels; 302, projection lens; 303, polarizer.

Detailed ways

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of this application.

In the description of the present invention, it should be understood that the terms "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", vertical The orientations or positional relationships indicated by "straight", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description. , rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be construed as a limitation of the present invention.

In the description of the present invention, it should be noted that, unless otherwise clearly stated and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense. For example, it can be a fixed connection or a detachable connection. , or integrally connected. It can be a mechanical connection or an electrical connection. It can be a direct connection or an indirect connection through an intermediate medium. It can be an internal connection between the two components. For those of ordinary skill in the art, it can The specific meanings of the above terms in the present invention will be understood in specific circumstances.

Referring to FIG. 1 , an embodiment of the present application provides a light source device 200 . The light source device 200 is applied in a display device 300 and is used to generate a projection display image.

This specification does not limit the specific type of the display device 300. For example, the display device 300 can be applied to a helmet-mounted display (HMD), a head-up display (HUD), and other wearable eyewear devices. Of course, the display device 300 can also be a projector. In this embodiment, the display device 300 includes a light source device 200, a display 301 and a projection lens 302. The light source device 200 includes a light source 201 and a light guide system 100, wherein the light source 201 is used to emit a light beam, and the light guide system 100 is disposed on one side of the light source 201. The optical waveguide of the light guide system 100 is provided with an in-coupling area 12 and an out-coupling area 14. The in-coupling area 12 is located on the optical path of the light beam emitted by the light source 201. The display 301 is disposed on the side of the optical waveguide provided with the outcoupling area 14 and is located on the optical path of the light coupled out by the outcoupling area 14 . The projection lens 302 is disposed on the side of the optical waveguide of the light guide system 100 away from the display 301 and corresponds to the position of the display 301 along the thickness direction of the optical waveguide of the light guide system 100 .

During operation, the light source 201 emits a light beam. The light beam enters the optical waveguide of the light guide system 100 through the coupling area 12 and propagates in the optical waveguide of the light guide system 100 at a certain angle. The light beam is incident on the optical waveguide of the light guide system 100 and the air. Total reflection will occur at the interface of The waveguide enters the display 301, which modulates the light beam and reflects the modulated light beam to the projection lens 302, and finally enters the human eye.

In the description of this application, it needs to be understood that the terms "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", " The directions or positional relationships indicated by "ri" and "ri" are based on the orientations or positional relationships shown in the drawings. They are only used to simplify the description for the convenience of describing the present application, and are not intended to indicate or imply that the device or element referred to must have a specific orientation. To specify orientation construction and operation, and therefore cannot be construed as a limitation on this application.

This specification does not limit the specific type of the light source 201. For example, the light source 201 can use a linearly polarized laser, or a non-polarized light source such as an LED (light emitting diode) or a combination of other lasers and polarizers to collimate and emit a light beam. Homogenize into a uniform spot. In this embodiment, the light source 201 uses a non-polarized light source. This embodiment has no restrictions on the wavelength and spectral width of the light emitted from the light source 201.

The display 301 is spaced apart from the coupling area 14 and is used to modulate the light beam coupled out through the coupling area 14 and reflect the modulated light beam to the projection lens 302 . The display 301 is used to generate an image source and control the brightness of pixels in the image. The display 301 is an optical display device that does not actively emit light. This specification does not limit the specific type of the display 301. For example, the display 301 can be an LCOS (liquid crystal on silicon) display panel. , or LCD (liquid crystal display). In this embodiment, the display 301 is an LCOS display panel. The display 301 may include a plurality of bright pixels 3012 and a plurality of dark pixels 3014. The plurality of bright pixels 3012 and the plurality of dark pixels 3014 are arranged in an array at intervals, and the bright pixels 3012 and the dark pixels 3014 are arranged at cross intervals. Among them, bright pixels 3012 are used to modulate and reflect light, and dark pixels 3014 are used to directly reflect light.

In this embodiment, the projection lens 302 is used to map the image source of the display 301 into human eyes. In order to improve the clarity of imaging, in this embodiment, the display device 300 may further include an analyzer 303 , which is disposed between the projection lens 302 and the light guide system 100 and opposite to the projection lens 302 . The projection lens 302 , the analyzer 303 , the optical waveguide 10 and the display 301 are arranged in parallel and at intervals along the thickness direction of the optical waveguide 10 . The analyzer 303 is a polarizing plate, and its main function is to convert the incident light into linearly polarized light for output. In this embodiment, the analyzer 303 is an absorptive polarizer, which only allows light of a certain polarization state to pass through and reflects or absorbs light of other polarization states, thereby ensuring the clarity of the image.

Please refer to FIGS. 1 and 2 at the same time. The light guide system 100 is used to constrain the propagation path of the light beam emitted by the light source 201 and guide the light emitted by the light source 201 to a target position. The "target position" may be a non-active light-emitting chip of the display device. In this embodiment, the "target position" is the surface of the display 301 close to the light guide system 100 . The light includes a first polarized light O1 and a second polarized light O2 with different polarization states. In this embodiment, the light guide system 100 may include an optical waveguide 10 , a first coupling device 20 , a first coupling device 30 , a quarter wave plate 40 and a reflecting mirror 50 . The first coupling device 20 is disposed in the coupling area 12, the first coupling device 30 is disposed in the outcoupling area 14, the quarter wave plate 40 and the reflector 50 are both disposed on the side of the optical waveguide 10 away from the light source 201. And are arranged side by side in a direction away from the optical waveguide 10 .

The first coupling device 20 is sensitive to the first polarized light O1. When light is incident on the first coupling device 20, the first polarized light O1 in the incident light is diffracted and enters the optical waveguide 10 along the light propagation direction. z propagates, the second polarized light O2 penetrates the optical waveguide 10 and is reflected by the reflecting mirror 50, and is coupled into the optical waveguide 10 again. During this process, the quarter wave plate 40 converts the second polarized light O2 into the first Polarized light O1. Therefore, in this embodiment, the characteristic of the first coupling device 20 that is sensitive to the first polarized light O1 is used to propagate the second polarized light O2 out of the optical waveguide 10 , under the action of the quarter-wave plate 40 and the reflecting mirror 50 , the second polarized light O2 is converted into the first polarized light O1 and then coupled into the optical waveguide 10 again, thereby improving the coupling efficiency, thereby improving the energy transfer efficiency of the entire light guide system 100.

Please refer to Figure 3. In this embodiment, the optical waveguide 10 is a guide structure made of an optically transparent medium (such as quartz glass) for transmitting light frequency electromagnetic waves. It is a device that guides the propagation of waves therein and is used to limit the direction of the light beam. Propagation path in space, when the propagation angle of the light beam satisfies the total reflection condition, it can only propagate within the optical waveguide 10 . This specification does not limit the specific type of the optical waveguide 10. The optical waveguide 10 can be made into a very light and thin flat glass form. In this embodiment, the optical waveguide 10 may be a glass plate 101. The refractive index of the glass plate 101 is n, the thickness is d, and the total reflection critical angle of the glass plate 101 is θ ₀ =arcsin(n _a /n), where n _a is the refractive index of air. The larger the refractive index n of the optical waveguide 10 is, the smaller the total reflection critical angle θ ₀ is. At this time, the angle range in which total reflection of light can occur in the optical waveguide 10 increases, which increases the degree of design freedom.

Please refer to FIGS. 1 and 2 again. The optical waveguide 10 includes a first surface 16 , a second surface 18 and a side wall 17 . The first surface 16 and the second surface 18 are away from each other, wherein the first surface 16 is disposed toward the light source 201 , the second surface 18 is disposed toward the projection lens 302 , and the side wall 17 is connected between the first surface 16 and the second surface 18 . The optical waveguide 10 may be in the shape of a flat plate as a whole, so the first surface 16 and the second surface 18 may be flat. In other embodiments, the optical waveguide 10 may be in the shape of a curved plate, and the first surface 16 and the second surface 18 may be flat. They can be concave and convex respectively; the shape of the optical waveguide 10 can be a circular plate shape, and both the first surface 16 and the second surface 18 can be arc-shaped surfaces.

In this application, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Therefore, features defined as "first" and "second" may explicitly or implicitly include at least one of these features. In the description of this application, "plurality" means at least two, such as two, three, etc., unless otherwise expressly and specifically limited.

The coupling area 12 is disposed on the first surface 16 , and the coupling area 12 and the light source 201 are spaced apart and opposite to each other. The outcoupling area 14 is disposed on the surface of the optical waveguide 10 , and the outcoupling area 14 is spaced opposite to the display 301 . This specification does not limit the specific location of the coupling-out area 14. For example, the coupling-out area 14 can be on the same side as the coupling-in area 12, and can also be disposed on the first surface 16. The coupling-out area 14 may also be on a different side from the coupling-in area 12 . For example, the coupling-out area 14 may be disposed on the second surface 18 or on the side wall 17 . In order to facilitate processing, the coupling-in region 12 and the coupling-out region 14 in this embodiment are disposed on the same side. In this embodiment, the coupling-in region 12 and the coupling-out region 14 are both disposed on the first surface 16, and the coupling-in region 12 The outcoupling regions 14 are spaced apart in the light propagation direction z defined by the optical waveguide 10 . This specification does not limit the specific direction of the light propagation direction z. For example, the light propagation direction z can be the length direction of the optical waveguide 10 or the width direction of the optical waveguide 10 . In this embodiment, the light propagation direction z is the optical waveguide 10 length direction.

In this embodiment, the first coupling device 20 is disposed in the coupling area 12 and is opposite to the light source 201. The first coupling device 20 is sensitive to the first polarized light O1, so that the light is coupled through the first coupling device 20. After entering the optical waveguide 10, the first polarized light O1 in the light can be diffracted by the first coupling device 20 to propagate along the light propagation direction z, and part of the second polarized light O2 passes in a direction perpendicular to the first surface 16. In the light-transmitting waveguide 10 , part of the second polarized light O2 is incident on the light waveguide 10 in a direction perpendicular to the first surface 16 , and is diffracted based on the first coupling device 20 to propagate along the light propagation direction z. This specification does not limit the specific type of the first coupling device 20. For example, the first coupling device 20 includes at least one of the following structures: grating, metasurface, photonic crystal, and diffractive optical element (DOE). Among them, the grating is a dispersion element that uses the interference and diffraction phenomena of light to separate light. Metasurface refers to an artificial layered material with a thickness smaller than the wavelength. Metasurface can realize flexible and effective control of electromagnetic wave polarization, amplitude, phase, polarization mode, propagation mode and other characteristics. Photonic crystal refers to an artificial periodic dielectric structure with photonic band gap characteristics, sometimes also called PBG (photonic band gap) photonic crystal structure. Diffractive optical elements are a series of movable lenses in lithography machines, mainly used to generate the light sources required for lithography.

The minimum characteristic size of the first coupling device 20 is from microns to nanometers, which can achieve strong diffraction efficiency for a certain polarization state. For example, as mentioned above, it has strong diffraction efficiency for the first polarization state light O1 and other polarization states. For example, the second polarization state light O2 has lower diffraction efficiency. This specification does not limit the specific types of the first polarized light O1 and the second polarized light O2. For example, the first polarized light O1 can be s-polarized light, and the second polarized light O2 can be p-polarized light; or the first polarized light O1 can be p-polarized light; The polarized light O1 may be p-polarized light, and the second polarized light O2 may be s-polarized light. In this embodiment, the first polarized light O1 is s-polarized light, and the second polarized light O2 is p-polarized light. That is, the diffraction efficiency of the first coupling device 20 for s-polarized light is higher and the diffraction efficiency of p-polarized light is lower. That is, the diffraction efficiency of the first coupling device 20 for s-polarized light is much greater than the diffraction efficiency of p-polarized light. efficiency. The higher the diffraction order efficiency of the first polarized light O1 coupled to the optical waveguide 10 , the better. In this embodiment, the diffraction efficiency of the first coupling device 20 for the first polarized light O1 is greater than or equal to 50%. The increase in the diffraction efficiency of the above-mentioned p-polarized light, that is, the second polarized light O2, will lead to a reduction in the projection contrast. The higher the diffraction order efficiency of the second polarized light O2 coupled to the optical waveguide 10, the better. The first coupling device 20 has The diffraction efficiency of the second polarized light O2 is less than or equal to 5%.

Therefore, the first coupling device 20 disposed in the coupling region 12 changes the propagation angle of the first polarized light O1 in the light beam emitted by the light source 201 through the diffraction effect, so that the angle of the first polarized light O1 satisfies the requirements in the optical waveguide 10 Total reflection condition, thereby achieving substantially lossless transmission of the first polarized light O1 in the optical waveguide 10 (ignoring the light absorption effect of the optical waveguide 10 material). The first coupling device 20 basically does not change the propagation angle and propagation path of the second polarized light O2, so that the second polarized light O2 can penetrate the optical waveguide 10 and reach the quarter-wave plate 40. In this embodiment, the optical waveguide 10 can also serve as the base of the first coupling device 20 so that the first coupling device 20 can be attached thereto.

In this embodiment, the quarter-wave plate 40 is relatively spaced apart from the second surface 18 of the optical waveguide 10 and is located on the optical path where the second polarized light O2 penetrates the optical waveguide 10 . The projection of the quarter-wave plate 40 on the optical waveguide 10 covers the projection of the first coupling device 20 on the optical waveguide 10 . The quarter wave plate 40, also known as the "quarter delay plate", is a birefringent single crystal wave plate with a certain thickness. When light is incident from the normal direction and passes through a quarter-wave plate, the phase difference between ordinary light and extraordinary light is equal to π/2 or an odd multiple thereof. Such a plate is called a quarter-wave plate or 1/4 Wave plate. In the optical path, the quarter wave plate 40 is often used to change linearly polarized light into circularly polarized light or elliptically polarized light, or to change circularly polarized light or elliptically polarized light into linearly polarized light.

In this embodiment, the reflector 50 is disposed on a side of the quarter-wave plate 40 away from the optical waveguide 10 , and is used to reflect the second polarized light O2 that penetrates the quarter-wave plate 40 . The reflector 50 is an optical element that works based on the law of reflection and has high reflectivity. This specification does not limit the specific structure of the reflector 50. For example, the reflector 50 can be an integrated form of an anti-reflection dielectric film, a metal film, an optical microstructure, etc. coated on the quarter-wave plate 40, or it can be Independent reflective device.

During operation, light is incident on the first coupling device 20, and the second polarized light O2 in the incident light penetrates the optical waveguide 10 and first passes through the quarter wave plate 40 and is reflected by the reflector 50, and then passes through the quarter wave plate 40 again. A wave plate 40 enters the optical waveguide 10 . After passing through the quarter-wave plate 40 twice, the second polarized light O2 is converted into the first polarized light O1. The first polarized light O1 enters the optical waveguide 10 and is transmitted to the first coupling device 20 where it is diffracted. Propagate along the light propagation direction z, improving the coupling efficiency.

In this embodiment, the first outcoupling device 30 is disposed in the outcoupling area 14 to break the total reflection condition and cause the first polarized light O1 to pass from the first surface 16 at the same angle and in the opposite direction as when it is incident. Coupling out. This specification does not limit the specific structure of the first coupling device 30. For example, the first coupling device 30 includes at least one of the following structures: surface relief grating, Bragg grating, holographic volume grating, metasurface, photonic crystal, diffractive optics element. The first polarized light O1 in the incident light and the first polarized light O1 converted from the second polarized light O2 propagate along the light propagation direction z in the optical waveguide 10 to the outcoupling region 14 and then pass through the first outcoupling device. 30 coupling out. The coupled light beam uniformly illuminates the display 301. The display 301 modulates the polarization state of the light. The bright pixel 3012 modulates the incident first polarized light O1 into the second polarized light O2 and reflects it. The dark pixel 3014 directly reflects the first polarized light. State light O1, the modulated beam is reflected and passes through the optical waveguide 10 to illuminate the analyzer 303. The analyzer 303 can only pass the second polarization state light O2, and only the image corresponding to the bright pixel 3012 enters the projection lens 302 for display. .

Please refer to Figure 4. If the first coupling device 20 has direction selectivity, that is, the diffraction efficiency of the first polarized light O1 emitted by the light source 201 (shown in Figure 1) incident on the first coupling device 20 and the reflected The diffraction efficiency of the first polarized light O1 reflected by the mirror 50 into the optical waveguide 10 and incident on the first coupling device 20 is different. In order to improve the diffraction efficiency of the first polarized light O1 reflected by the mirror 50 into the optical waveguide 10 and incident on the first coupling device 20 , in some embodiments, the light guide system 100 may further include a second coupling device 60 .

The second coupling device 60 is disposed on the second surface 18 and is located on the optical path of the light reflected by the reflector 50 to the optical waveguide 10 . Like the first coupling device 20 , the second coupling device 60 is also sensitive to the first polarized light O1 , that is, the first polarized light O1 is incident on the second coupling device 60 and diffracted. Under the action of the reflecting mirror 50 and the quarter-wave plate 40 , the second polarized light O2 is converted into the first polarized light O1 , and is coupled into the optical waveguide 10 through the second coupling device 60 . The second coupling device 60 enables the converted first polarized light O1 to be coupled into the optical waveguide 10 with higher efficiency, further improving the energy transfer efficiency of the light guide system 100 .

Please refer to Figure 5. As mentioned above, an increase in the diffraction efficiency of the second polarized light O2 will lead to a reduction in the contrast of the projected image. In order to improve the purity of the first polarized light O1 in the optical waveguide 10, in some embodiments, the light guide system 100 may also include a second coupling-out device 70 disposed on the second surface 18 or/and the first surface 16 and located between the coupling-in region 12 and the coupling-out region 14 . The second coupling out device 70 is sensitive to the second polarized light O2, that is, the diffraction efficiency of the second coupling device 70 for the second polarized light O2 is greater than the diffraction efficiency for the first polarized light O1. For example, the second coupling device 70 is sensitive to the second polarized light O2. The diffraction efficiency of the second outcoupling device 70 for the second polarized light O2 is greater than or equal to 50%, and the diffraction efficiency of the second outcoupling device 70 for the first polarized light O1 is less than or equal to 5%. As a result, the second polarized light O2 in the optical waveguide 10 is coupled out of the optical waveguide 10 through the second coupling device 70 , thereby improving the contrast of the projected image without affecting the transmission efficiency of the first polarized light O1 in the optical waveguide 10 . This specification does not limit the specific structure of the second outcoupling device 70. For example, the second outcoupling device 70 may include at least one of the following structures: grating, metasurface, photonic crystal, and diffractive optical element (DOE). Among them, the grating is a dispersion element that uses the interference and diffraction phenomena of light to separate light. Metasurface refers to an artificial layered material with a thickness smaller than the wavelength. Metasurface can realize flexible and effective control of electromagnetic wave polarization, amplitude, phase, polarization mode, propagation mode and other characteristics. Photonic crystal refers to an artificial periodic dielectric structure with photonic band gap characteristics, sometimes also called PBG (photonic band gap) photonic crystal structure. Diffractive optical elements are a series of movable lenses in lithography machines, mainly used to generate the light sources required for lithography.

In the light guide system 100 provided by the embodiment of the present application, the first coupling device 20 is sensitive to the first polarized light O1. Light is incident on the first coupling device 20, and the first polarized light O1 in the incident light is diffracted. And enters the optical waveguide 10 and propagates along the light propagation direction z. The second polarized light O2 in the incident light penetrates the optical waveguide 10 and first passes through the quarter wave plate 40 and is reflected by the reflector 50, and then passes through the quarter wave plate 40 again. A wave plate 40 enters the optical waveguide 10 . After passing through the quarter-wave plate 40 twice, the second polarized light O2 is converted into the first polarized light O1, enters the optical waveguide 10 and is transmitted to the first coupling device 20 where it is diffracted and propagates along the light propagation direction z. , improving the coupling efficiency. The first coupling device 20 is sensitive to the first polarized light O1 to propagate the second polarized light O2 out of the optical waveguide 10. Under the action of the quarter wave plate 40 and the reflector 50, the second polarized light O2 is O2 is converted into the first polarized light O1 and then coupled into the optical waveguide 10 again, thereby improving the coupling efficiency and thereby improving the energy transfer efficiency of the entire light guide system 100 .

In the description of this specification, reference to the terms "one embodiment," "some embodiments," "an example," "specific examples," or "some examples" or the like means that specific features are described in connection with the embodiment or example. , structures, materials or features are included in at least one embodiment or example of the present application. In this specification, the schematic expressions of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the specific features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, those skilled in the art may combine and combine different embodiments or examples and features of different embodiments or examples described in this specification unless they are inconsistent with each other.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art will understand that: it can still Modifications are made to the technical solutions described in the foregoing embodiments, or equivalent substitutions are made to some of the technical features; however, these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions in the embodiments of the present application.

Claims (12)

1. A light guide system for directing light from a light source to a target location, the light comprising first and second polarized light of different polarization states, the light guide system comprising:

the optical waveguide comprises an optical waveguide body, wherein the surface of the optical waveguide body is provided with a coupling-in area and a coupling-out area, the optical waveguide body is provided with a first surface and a second surface which are opposite, the coupling-in area is arranged on the first surface, and the coupling-in area and the coupling-out area are arranged at intervals in the light propagation direction defined by the optical waveguide body;

the first coupling-in device is arranged in the coupling-in area and is used for being opposite to the light source, the first coupling-in device is sensitive to the light with the first polarization state, so that after the light is coupled into the optical waveguide through the first coupling-in device, the light with the first polarization state can propagate along the light propagation direction, and the light with the second polarization state penetrates through the optical waveguide;

the quarter wave plate is arranged at an interval opposite to the second surface and is positioned on a light path of the second polarized light penetrating through the optical waveguide; and

the reflecting mirror is arranged on one side of the quarter wave plate, which is away from the optical waveguide, and is used for reflecting the second polarized light penetrating through the quarter wave plate, and the second polarized light reflected by the reflecting mirror passes through the quarter wave plate again and is converted into first polarized light, enters the optical waveguide and propagates along the light propagation direction.

2. The light guide system of claim 1, wherein the first incoupling device has a diffraction efficiency of greater than or equal to 50% for the light of the first polarization state.

3. The light guide system of claim 1, wherein the first incoupling device has a diffraction efficiency of less than or equal to 5% for light of the second polarization state.

4. The light guide system of claim 1, wherein the out-coupling region is provided with a first out-coupling means comprising at least one of the following structures: surface relief gratings, bragg gratings, holographic volume gratings, supersurfaces, photonic crystals, diffractive optical elements.

5. The light guide system of any one of claims 1-4, further comprising a second in-coupling device disposed on the second surface, the second in-coupling device being in an optical path of light reflected by the mirror to the light guide, the first polarization state light being incident on the second in-coupling device for diffraction; the second polarized light reflected by the reflecting mirror is converted into the first polarized light via the quarter wave plate and coupled into the optical waveguide via the second coupling-in device.

6. The light guide system of any of claims 1-4, further comprising a second out-coupling device disposed on the second surface or/and the first surface and between the in-coupling region and the out-coupling region, wherein light of a second polarization within the optical waveguide is coupled out by the second out-coupling device.

7. The light guide system of claim 6, wherein the second out-coupling means comprises at least one of the following structures: gratings, supersurfaces, photonic crystals, diffractive optical elements.

8. The light guiding system according to any of claims 1-4, wherein the first coupling-in means comprises at least one of the following structures: gratings, supersurfaces, photonic crystals, diffractive optical elements.

9. A light source device, comprising:

a light source; and

the light guide system according to any one of claims 1 to 8, wherein the light source is arranged on a side of the light guide where the coupling-in region is arranged, the light source being opposite to the first coupling-in device.

10. A light source device according to claim 9, wherein,

the light source comprises an unpolarized light source, the first polarized light is s polarized light, and the second polarized light is p polarized light; or alternatively

The light source comprises an unpolarized light source, the first polarized light is p-polarized light, and the second polarized light is s-polarized light.

11. A display device, characterized by comprising:

the light source device according to any one of claims 9 to 10;

the display is arranged at one side of the optical waveguide, provided with the coupling-out region, and is opposite to the coupling-out region; and

the projection lens is arranged on one side of the optical waveguide, which is away from the display.

12. The display device of claim 11, further comprising an analyzer disposed between the projection lens and the optical waveguide; the display includes a bright pixel for modulating the first polarization state light into the second polarization state light and reflecting the second polarization state light, and a dark pixel for reflecting the first polarization state light, and an analyzer for blocking the first polarization state light from propagating to the projection lens.