Optical structure, display device and depolarization beam splitting structure

Abstract

The invention provides an optical structure, a display device and a depolarization beam splitting structure. The optical structure is provided with a light inlet side and a light outlet side and comprises a lens structure, a beam splitting film, a light-transmitting protection film, a phase delay film and a polarization reflection film. The lens structure comprises a first surface and a second surface, the first surface is the surface of the light incident side of the lens structure and is a curved surface, the beam splitting film is located on the side, away from the second surface, of the first surface, and the light-transmitting protection film is located on the side, away from the first surface, of the beam splitting film and makes contact with the beam splitting film. The phase retardation film is located at one side of the second surface away from the first surface, and the polarization reflection film is located at one side of the second surface away from the first surface. The beam splitting film comprises a metal layer, the light-transmitting protective film comprises a structural layer, the refractive index of the structural layer is gradually reduced along a reference direction, and the reference direction is a direction from the beam splitting film to the light-transmitting protective film. Therefore, when the incident angle of the light incident to the beam splitting film is large, the beam splitting film can keep the beam splitting characteristic, and the metal layer of the beam splitting film cannot be corroded and oxidized.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to an optical structure, a display device, and a depolarizing beam splitting structure. Background Art

[0002] In virtual reality (VR) and mixed reality (MR) devices, a near-eye display device magnifies the image of a display screen through a lens, giving people an immersive experience. Currently, the main lens technologies are Fresnel lenses and Pancake (ultra-short focal length folded optical path) lenses. Among them, the Pancake (ultra-short focal length folded optical path) lens greatly reduces the distance required between the near-eye display device and the human eye by folding the optical path, making VR devices and MR devices thinner and lighter. Summary of the Invention

[0003] Embodiments of the present disclosure provide an optical structure, a display device, and a depolarizing beam splitting structure. The beam splitting film of the optical structure includes a metal layer, so that when the incident angle of the light incident on the beam splitting film is large, the beam splitting film can also have good beam splitting performance. And by providing a light-transmitting protective film, not only can the metal layer be protected, but the light-transmitting protective film does not affect the broadband beam splitting characteristics of the beam splitting film.

[0004] At least one embodiment of the present disclosure provides an optical structure having an incident light side and an emergent light side, including: a lens structure including a first surface and a second surface arranged opposite to each other, the first surface being the surface of the incident light side of the lens structure and the first surface being a curved surface; a beam splitting film located on the side of the first surface away from the second surface; a light-transmitting protective film located on the side of the beam splitting film away from the first surface and in contact with the beam splitting film; a phase delay film located on the side of the second surface away from the first surface; and a polarization reflection film located on the side of the second surface away from the first surface. The beam splitting film includes a metal layer, and the light-transmitting protective film includes a structural layer, and the refractive index of the structural layer gradually decreases along a reference direction, and the reference direction is the direction from the beam splitting film to the light-transmitting protective film.

[0005] For example, in the optical structure provided by an embodiment of the present disclosure, the light-transmitting protective film further includes a base layer, the base layer is closer to the beam splitting film than the structural layer, and the base layer is in contact with the beam splitting film and is configured to protect the beam splitting film.

[0006] For example, in the optical structure provided by an embodiment of the present disclosure, the refractive index of the base layer is not less than the maximum refractive index of the structural layer.

[0007] For example, in the optical structure provided by an embodiment of the present disclosure, the structure layer includes a plurality of convex structures. Along the reference direction, the cross-sectional dimensions of the convex structures gradually decrease, and the cross-sectional dimensions of the convex structures are perpendicular to the reference direction.

[0008] For example, in the optical structure provided by an embodiment of the present disclosure, the side of the longitudinal section of the convex structure includes at least one of a straight line segment or a curved line segment, and the longitudinal section is parallel to the reference direction.

[0009] For example, in the optical structure provided by an embodiment of the present disclosure, the value range of the maximum height of the convex structure in the reference direction is 50 nm to 200 nm, and the value range of the minimum distance between adjacent two convex structures is 0 to 200 nm.

[0010] For example, in the optical structure provided by an embodiment of the present disclosure, the refractive index of the structure layer decreases step by step along the reference direction and has at least 3 decreasing steps.

[0011] For example, in the optical structure provided by an embodiment of the present disclosure, the structure layer includes at least three structural sub-layers, the at least three structural sub-layers are arranged in sequence along the reference direction, and the refractive indices of the at least three structural sub-layers decrease in sequence along the reference direction.

[0012] For example, in the optical structure provided by an embodiment of the present disclosure, the material densities of the at least three structural sub-layers decrease in sequence along the reference direction.

[0013] For example, in the optical structure provided by an embodiment of the present disclosure, the structural sub-layer includes a nanoparticle coating, and the porosities of the at least three structural sub-layers increase in sequence along the reference direction.

[0014] For example, in the optical structure provided by an embodiment of the present disclosure, the material of the base layer of the light-transmitting protective film includes at least one of acrylic acid, polyurethane, epoxy, amino resin, polyester resin, silicone, poly(p-xylene) and its derivatives, polyhexamethyldisiloxane, polytetrafluoroethylene, and polyvinylidene fluoride, and the material of the structure layer of the light-transmitting protective film includes at least one of acrylic acid, polyurethane, epoxy, amino resin, polyester resin, silicone, poly(p-xylene) and its derivatives, polyhexamethyldisiloxane, polytetrafluoroethylene, and polyvinylidene fluoride.

[0015] For example, in the optical structure provided by an embodiment of the present disclosure, the value range of the thickness of the base layer is 100 nm to 5 μm, and the value range of the thickness of the structure layer is 50 nm to 200 nm.

[0016] For example, in the optical structure provided by an embodiment of the present disclosure, the beam splitting film further includes at least one non-metal layer stacked with the metal layer.

[0017] For example, the optical structure provided by an embodiment of the present disclosure further includes: a polarization absorption film located on a side of the polarization reflection film away from the first surface.

[0018] At least one embodiment of the present disclosure provides a display device, including a display screen and the optical structure as described in any one of the above, and the display screen is located on a light incident side of the optical structure.

[0019] For example, in the display device provided by an embodiment of the present disclosure, the display screen includes a micro organic light emitting diode display screen.

[0020] At least one embodiment of the present disclosure provides a depolarization beam splitting structure, including a beam splitting film and a light transmissive protective film stacked, the light transmissive protective film is in contact with the beam splitting film, the beam splitting film includes a metal layer and at least one non-metal layer stacked with the metal layer, the light transmissive protective film includes a structural layer, and a refractive index of the structural layer gradually decreases along a reference direction, and the reference direction is a direction from the beam splitting film to the light transmissive protective film. Description of the Drawings

[0021] To more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings of the embodiments will be briefly introduced below. Obviously, the drawings in the following description only relate to some embodiments of the present disclosure and do not limit the present disclosure.

[0022] Figure 1 It is a schematic structural diagram of a display device;

[0023] Figure 2 It is a schematic structural diagram of another display device;

[0024] Figure 3 It is a curve graph of reflectivity and transmittance of light incident on a dielectric beam splitter at different incident angles;

[0025] Figure 4 It is a schematic cross-sectional view of an optical structure provided by an embodiment of the present disclosure;

[0026] Figure 5 It is Figure 4 a partially enlarged schematic cross-sectional view of the optical structure shown;

[0027] Figure 6 It is Figure 4 another partially enlarged schematic cross-sectional view of the optical structure shown;

[0028] Figure 7A graph showing the reflectivity and transmittance of light incident on a beam-splitting film provided by an embodiment of the present disclosure at different incident angles;

[0029] Figure 8 A partially enlarged cross-sectional schematic diagram of the beam-splitting film provided by an embodiment of the present disclosure after coating with a protective layer;

[0030] Figure 9 For Figure 8 A graph showing the reflectivity and transmittance of light incident on the shown beam-splitting film and protective layer at different incident angles;

[0031] Figure 10 For Figure 8 Another graph showing the reflectivity and transmittance of light incident on the shown beam-splitting film and protective layer at different incident angles;

[0032] Figure 11 A schematic diagram showing a change in refractive index of a structural layer of a light-transmitting protective film provided by an embodiment of the present disclosure;

[0033] Figure 12 Another partially enlarged cross-sectional schematic diagram of the light-transmitting protective film provided by an embodiment of the present disclosure;

[0034] Figure 13 Another partially enlarged cross-sectional schematic diagram of the light-transmitting protective film provided by an embodiment of the present disclosure;

[0035] Figure 14 Another partially enlarged cross-sectional schematic diagram of the light-transmitting protective film provided by an embodiment of the present disclosure;

[0036] Figure 15 Another schematic diagram showing a change in refractive index of a structural layer of the light-transmitting protective film provided by an embodiment of the present disclosure;

[0037] Figure 16 Another partially enlarged cross-sectional schematic diagram of the beam-splitting film and the light-transmitting protective film of the optical structure provided by an embodiment of the present disclosure;

[0038] Figure 17 For Figure 16 A refractive index schematic diagram of the shown beam-splitting film and light-transmitting protective film;

[0039] Figure 18 For Figure 16 A graph showing the reflectivity and transmittance of light incident on the shown beam-splitting film and light-transmitting protective film at different incident angles;

[0040] Figure 19 A partially enlarged cross-sectional schematic diagram of the beam-splitting film provided by an embodiment of the present disclosure after coating with a protective layer;

[0041] Figure 20 For Figure 19A graph showing the reflectance and transmittance of light incident on the beam splitting film and the protective layer at different incident angles;

[0042] Figure 21 Another partial enlarged cross-sectional schematic diagram of the beam splitting film and the light-transmitting protective film of the optical structure provided by the embodiments of the present disclosure;

[0043] Figure 22 is Figure 21 A schematic diagram of the refractive indices of the beam splitting film and the light-transmitting protective film shown;

[0044] Figure 23 is Figure 21 A graph showing the reflectance and transmittance of light incident on the beam splitting film and the light-transmitting protective film at different incident angles;

[0045] Figure 24 Another partial enlarged cross-sectional schematic diagram of the beam splitting film and the light-transmitting protective film of the optical structure provided by the embodiments of the present disclosure;

[0046] Figure 25 A cross-sectional schematic diagram of a display device provided by the embodiments of the present disclosure; and

[0047] Figure 26 A partial enlarged cross-sectional schematic diagram of a depolarization beam splitting structure provided by the embodiments of the present disclosure. Detailed implementation manners

[0048] To make the objectives, technical solutions and advantages of the embodiments of the present disclosure clearer, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present disclosure. Obviously, the described embodiments are some, but not all, of the embodiments of the present disclosure. All other embodiments obtained by those of ordinary skill in the art based on the described embodiments of the present disclosure without creative efforts shall fall within the scope of protection of the present disclosure.

[0049] Unless otherwise defined, the technical terms or scientific terms used in the present disclosure shall have the ordinary meanings understood by those of ordinary skill in the art to which the present disclosure pertains. The "first", "second" and similar terms used in the present disclosure do not denote any order, quantity or importance, but are only used to distinguish different components. The terms such as "including" or "comprising" mean that the elements or items appearing before this word cover the elements or items listed after this word and their equivalents, without excluding other elements or items. The terms such as "connected" or "coupled" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

[0050] Unless otherwise defined, features such as "parallel", "perpendicular", and "identical" used in the embodiments of the present disclosure include strict "parallel", "perpendicular", "identical", etc., as well as cases with certain errors such as "substantially parallel", "substantially perpendicular", and "substantially identical". For example, the above "substantially" may mean that the difference between the compared objects is within 10% or 5% of the average value of the compared objects. When the number of a component or element is not specifically indicated in the following text of the embodiments of the present disclosure, it means that the component or element can be one or more, or can be understood as at least one. "At least one" means one or more, and "a plurality" means at least two. The "same-layer setting" in the embodiments of the present disclosure refers to the relationship between multiple film layers formed of the same material after the same step (for example, one-step patterning process). Here, "same layer" does not always mean that the thicknesses of multiple film layers are the same or the heights of multiple film layers in the cross-sectional view are the same.

[0051] Pancake lens technology has become the mainstream lens technology for virtual reality and mixed reality near-eye display systems and is adopted by various virtual reality and mixed reality near-eye display manufacturers. A Pancake lens generally includes a lens and a transmissive-reflective film, a phase retardation film, a polarization reflection film, and a polarization absorption film formed on the lens. The transmissive-reflective film can reflect light and transmit light at the same time. For example, the transmissive-reflective film can be a semi-transmissive and semi-reflective film. The phase retardation film has a fast axis and a slow axis, and can change circularly polarized light into linearly polarized light, or change linearly polarized light into circularly polarized light. The polarization reflection film has a reflection axis and a transmission axis, reflects linearly polarized light parallel to the reflection axis direction and keeps the polarization state of the linearly polarized light unchanged, and transmits linearly polarized light parallel to the transmission axis direction and keeps the polarization state of the linearly polarized light unchanged. The polarization absorption film has a transmission axis, the transmission axis direction of the polarization absorption film is parallel to the transmission axis of the polarization reflection film, and the fast axis of the phase retardation film forms an angle of 45 degrees or 135 degrees with the transmission axis of the polarization reflection film.

[0052] Figure 1 It is a schematic structural diagram of a display device. As Figure 1 shown, the display device includes a Pancake lens and a display screen 05. The Pancake lens includes a lens 01, a beam splitter 02, a quarter-wave phase retardation film 03, and a polarization reflection film 04. The beam splitter 02 is located on the curved surface of the lens 01 close to the display screen 05. The quarter-wave phase retardation film 03 can change the polarization state of light and convert circularly polarized light and linearly polarized light into each other. The reflective polarization film 04 is located on the surface of the lens 01. The reflective polarization film 04 can transmit polarized light in one direction (such as S light) and reflect polarized light in the other direction (such as P light). The light emitted by the display screen 05 completes the folding of the light path through the Pancake lens, greatly reducing the distance required between the near-eye display device and the human eye.

[0053] For a Pancake lens, the key to forming a folded optical path lies in the mutual conversion between circularly polarized light and linearly polarized light, and the ellipticity of the circularly polarized light within the folded optical path is an important physical quantity determining the optical quality of the Pancake lens. When the ellipticity is 1, it means the polarized light is completely circularly polarized light; when the ellipticity is 0, it means the polarized light is completely linearly polarized light; and when the ellipticity is between 0 and 1, it is elliptically polarized light, and the closer it is to 1, the closer it is to circularly polarized light. The principle of the Pancake lens requires that the ellipticity of the circularly polarized light within the folded optical path (for example, the optical paths 2, 3, and 4 as shown in Figure 1 Figure) is as close to 1 as possible. If the ellipticity is low, a part of the light will not follow the designed folded optical path, resulting in stray light or ghost images, which will affect the optical quality of imaging.

[0054] For a Pancake lens, the primary determining factor of ellipticity is the 1 / 4-wave plate phase retardation film (QWP, Quarter Wave Plate). An ideal QWP needs to have a retardation amount exactly 1 / 4 of its wavelength for the linearly polarized light when the linearly polarized light is incident at an angle of 45 degrees to its optical axis, then circularly polarized light with an ellipticity of 1 can be formed. If the retardation amount is insufficient or higher than 1 / 4 of the wavelength, elliptically polarized light with an ellipticity lower than 1 will be formed.

[0055] For a Pancake lens, other determining factors of ellipticity also include the material of the lens. The Pancake lens requires that the material of the lens has an extremely low birefringence. Otherwise, when polarized light passes through the lens, the phase of the polarized light will be retarded due to the birefringence characteristics of the lens, affecting the ellipticity and its distribution.

[0056] However, for a Pancake lens, there is also a determining factor affecting ellipticity that has been overlooked, namely the beam splitter. Traditional beam splitters are coated with 6 - 10 layers of dielectric films to achieve specific transmittance and reflectance (such as transmittance and reflectance of 50% respectively). However, according to the optical characteristics of the dielectric films of the beam splitter, when light is obliquely incident, the reflectance of its S-polarized component and P-polarized component with respect to the incident plane is inconsistent, and the transmittance of its S-polarized component and P-polarized component with respect to the incident plane is also inconsistent. That is to say, when completely circularly polarized light is obliquely incident on the surface of the beam splitter, both its transmitted light and reflected light will become elliptically polarized light, that is, the ellipticity decreases.

[0057] In existing VR devices based on Pancake lenses, the screen in the near-eye display module is a liquid crystal display (LCD, Liquid Crystal Display). For example, the typical size of the liquid crystal display is more than 2 inches, and the size of the screen is comparable to that of the lens. For example, as shown in Figure 1As shown, the surface of the display screen 05 cooperates with a wave plate to emit circularly polarized light. When the circularly polarized light is incident on the beam splitter of the Pancake lens, the incident angle α of the circularly polarized light is relatively small. For example, the incident angle α is less than 20 degrees. In the case where the incident angle α is relatively small, the difference between the transmittance Tp of the P-polarized component and the transmittance Ts of the S-polarized component of the dielectric beam splitter 02 is not large. Therefore, the decrease in ellipticity is also not large.

[0058] Figure 2 It is a schematic structural diagram of another display device. As Figure 2 shown, when the display screen 05 of this display device is a smaller-sized screen such as a micro organic light-emitting diode display screen (microOLED), since the size of the lens 01 needs to match the viewing angle of the human eye, the size of the lens 01 cannot be reduced proportionally with the size of the display screen 05. Then, the size of the display screen 05 will be much smaller than the size of the lens 01. At this time, when the circularly polarized light emitted from the display screen 05 passes through the wave plate and is incident on the beam splitter 02 of the lens 01, the incident angle α of a part of the circularly polarized light is relatively large. For example, the incident angle α is between 20 degrees and 50 degrees. In the case where the incident angle α is relatively large, the difference between the transmittance Tp of the P-polarized component and the transmittance Ts of the S-polarized component of the dielectric beam splitter 02 is very large. Therefore, after the circularly polarized light passes through the beam splitter 02, the ellipticity will be greatly reduced, forming stray light and ghost images, which affect the viewing effect.

[0059] Figure 3 It is a curve graph of the reflectivity and transmittance of light incident on a dielectric beam splitter at different incident angles. Figure 3 It shows the reflectivity Ra and transmittance Ta of the incident light when the incident angle of the incident light on a dielectric beam splitter is 0 degree, and the transmittance Ts of the S-polarized component and the transmittance Tp of the P-polarized component in the incident light when the incident angle of the incident light is 40 degrees. As Figure 3 shown, when the incident angle is 40 degrees, both the transmittance Ts of the S-polarized component and the transmittance Tp of the P-polarized component deviate from the target values (the target values are both 50%), and the difference between the transmittance Ts of the S-polarized component and the transmittance Tp of the P-polarized component is relatively large, and the beam splitting effect of the beam splitter is not ideal.

[0060] Embodiments of the present disclosure provide an optical structure and a display device. The optical structure has a light incident side and a light exit side, and the optical structure includes a lens structure, a beam splitting film, a light transmissive protective film, a phase retardation film, and a polarization reflection film. The lens structure includes a first surface and a second surface disposed opposite to each other. The first surface is the surface of the light incident side of the lens structure and the first surface is a curved surface. The beam splitting film is located on the side of the first surface away from the second surface. The light transmissive protective film is located on the side of the beam splitting film away from the first surface and is in contact with the beam splitting film. The phase retardation film is located on the side of the second surface away from the first surface. The polarization reflection film is located on the side of the second surface away from the first surface. The beam splitting film includes a metal layer, and the light transmissive protective film includes a structural layer, and the refractive index of the structural layer gradually decreases along a reference direction, and the reference direction is the direction from the beam splitting film to the light transmissive protective film.

[0061] In the optical structure provided by the embodiments of the present disclosure, the beam splitting film includes a metal layer. Since the reflection and transmission of the metal material are insensitive to polarization, when the incident angle of the light incident on the beam splitting film is relatively large (for example, when the incident angle is greater than 20 degrees), the difference between the transmittance of the P polarization component and the transmittance Ts of the S polarization component of the incident light is not large. Compared with the dielectric beam splitting film, the beam splitting film provided with the metal layer can improve the consistency of the transmittance Tp of the P polarization component and the transmittance Ts of the S polarization component of the incident light, thereby reducing the influence on the ellipticity of the incident light and making the ellipticity of the incident light as close to 1 as possible. It should be noted that the dielectric beam splitting film in this application refers to a beam splitting film without a metal layer.

[0062] In this embodiment, a light transmissive protective film in contact with the beam splitting film is further provided on the side of the beam splitting film away from the first surface. The light transmissive protective film can protect the metal layer in the beam splitting film and prevent corrosion and oxidation of the metal layer in the beam splitting film. Moreover, the light transmissive protective film includes a structural layer, and the refractive index of the structural layer gradually decreases along the reference direction. This structural layer can prevent interference fringes from being generated on the structural layer by the incident light and avoid the influence of the light transmissive protective film on the reflection spectrum and transmission spectrum of the beam splitting film. Thus, while protecting the metal layer in the beam splitting film, the light transmissive protective film does not affect the broadband beam splitting characteristics of the beam splitting film.

[0063] Next, the optical structure and the display device provided by the embodiments of the present disclosure will be described in detail with reference to the drawings.

[0064] Embodiments of the present disclosure provide an optical structure. Figure 4 is a schematic cross-sectional view of an optical structure provided by an embodiment of the present disclosure; Figure 5 is Figure 4 a partially enlarged schematic cross-sectional view of the optical structure shown in. As Figure 4 and Figure 5As shown, the optical structure 100 has an incident light side S1 and an outgoing light side S2. The optical structure 100 includes a lens structure 110, a beam splitting film 120, a light-transmitting protective film 130, a phase retardation film 140, and a polarization reflection film 150. The lens structure 110 includes a first surface 110a and a second surface 110b that are oppositely arranged. The first surface 110a is the surface on the incident light side of the lens structure 110 and the first surface 110a is a curved surface. The beam splitting film 120 is located on the side of the first surface 110a away from the second surface 110b. The light-transmitting protective film 130 is located on the side of the beam splitting film 120 away from the first surface 110a and is in contact with the beam splitting film 120. The phase retardation film 140 is located on the side of the second surface 110b away from the first surface 110a. The polarization reflection film 150 is located on the side of the second surface 110b away from the first surface 110a. The beam splitting film 120 includes a metal layer 121. The light-transmitting protective film 130 includes a structural layer 131. The refractive index of the structural layer 131 gradually decreases along the reference direction X. The reference direction X is the direction from the beam splitting film 120 to the light-transmitting protective film 130.

[0065] In the optical structure 100 provided by the embodiment of the present disclosure, the beam splitting film 120 includes a metal layer 121. Since the reflection and transmission of the metal material are insensitive to polarization, when the incident angle θ of the incident light incident on the beam splitting film 120 is relatively large, for example, the incident angle θ is greater than 20 degrees, for example, the incident angle θ is between 20 degrees and 50 degrees, compared with the dielectric beam splitting film, the beam splitting film 120 provided with the metal layer 121 can make the transmittance Tp of the P polarization component of the incident light and the transmittance Ts of the S polarization component have a smaller difference, which can improve the consistency of the transmittance of the P polarization component of the incident light and the transmittance Ts of the S polarization component, thereby reducing the influence on the ellipticity of the incident light and making the ellipticity of the incident light as close to 1 as possible.

[0066] In this embodiment, a light-transmitting protective film 130 in contact with the beam splitting film 120 is provided on the side of the beam splitting film 120 away from the first surface 110a. The light-transmitting protective film 130 can protect the metal layer 121 in the beam splitting film 120, avoiding corrosion and oxidation of the metal layer 121 in the beam splitting film 120. Moreover, the light-transmitting protective film 130 includes a structural layer 131. The refractive index of the structural layer 131 gradually decreases along the reference direction X. This structural layer 131 can prevent interference fringes from being generated on the structural layer 131 by the incident light, avoiding adverse effects on the reflection spectrum and transmission spectrum of the beam splitting film 120 by the light-transmitting protective film 130. Thus, the light-transmitting protective film 130 can not only protect the metal layer 121 of the beam splitting film 120, but also the light-transmitting protective film 130 does not affect the broadband beam splitting characteristics of the beam splitting film 120.

[0067] It should be noted that the lens structure 110 is schematically shown in the figure to include a single lens, and the first surface 110a and the second surface 110b of the lens structure 110 are opposite outer surfaces. However, the embodiments of the present disclosure are not limited thereto, and the lens structure 110 may also include multiple lenses. For example, when the lens structure 110 includes multiple lenses, the multiple lenses include multiple surfaces, and the second surface 110b may be the outer surface close to the light-emitting side among the multiple surfaces, or may be the surface between two outermost surfaces. For example, when the lens structure 110 includes multiple lenses, the first surface 110a and the second surface 110b may be the two outer surfaces of the same lens, or may be the outer surfaces located on different lenses respectively. For example, the lens structure 110 may include two, three, or four lenses, etc. For example, the second surface 110b may be a flat surface or a curved surface. For example, the multiple lenses of the lens structure 110 may be spaced apart or may be adhered together. The embodiments of the present disclosure do not limit the lens structure 110. Additionally, Figure 5 is schematically shown Figure 4 a schematic diagram of a partial enlarged cross-section at position A. It can be understood that the structures of the beam splitting film 120 and the light-transmitting protective film 130 at other positions on the first surface 110a of the lens structure 110 are the same as Figure 5 each other.

[0068] In some examples, as Figure 5 shown, the light-transmitting protective film 130 further includes a base layer 132. The base layer 132 is closer to the beam splitting film 120 than the structural layer 131. The base layer 132 is in contact with the beam splitting film 120 and is configured to protect the beam splitting film 120. The base layer 132 of the light-transmitting protective film 130 can protect the metal layer 121 of the beam splitting film 120, isolate water vapor and oxygen in the air, and avoid corrosion and oxidation of the metal layer 121.

[0069] In some examples, as Figure 5 shown, the refractive index of the base layer 132 is not less than the maximum refractive index of the structural layer 131. For example, the refractive index of the base layer 132 may be equal to or greater than the maximum refractive index. For example, the refractive index of the structural layer 131 gradually decreases along the reference direction X, and the maximum refractive index of the structural layer 131 may be the refractive index of a material layer with a set thickness on the side of the structural layer 131 close to the base layer 132. The set thickness may be the minimum thickness at which the refractive index value can be measured, or may also be 1 / 20 or less of the total thickness of the structural layer 131. Of course, the embodiments of the present disclosure do not limit the refractive index of the base layer 132, and the material of the base layer 132 and the corresponding refractive index can be selected according to requirements.

[0070] In some examples, as Figure 4 and Figure 5As shown, the reference direction X is the direction from the beam splitting film 120 to the light transmissive protective film 130. For example, the reference direction X can be the optical axis direction of the lens structure 110. For example, the reference direction X can also be the normal direction of the light transmissive protective film 130. In this case, the reference direction X at any position of the light transmissive protective film 130 is different. For example, the reference direction X is related to the manufacturing process of the light transmissive protective film 130. The embodiments of the present disclosure do not limit the reference direction X, as long as it satisfies the condition of pointing from the beam splitting film 120 to the light transmissive protective film 130.

[0071] In some examples, such as Figure 4 and Figure 5 As shown, the light transmissive protective film 130 is located on the outermost surface of the lens structure 110, and the side of the light transmissive protective film 130 away from the lens structure 110 is in contact with air.

[0072] In some examples, such as Figure 4 As shown, the light transmissive protective film 130 covers the beam splitting film 120, so that the beam splitting film 120 can be completely isolated from air.

[0073] In some examples, such as Figure 5 As shown, the beam splitting film 120 includes a metal layer 121 and at least one non-metal layer 122 stacked with the metal layer 121. Figure 5 It is schematically shown that the beam splitting film 120 includes a metal layer 121 and multiple non-metal layers 122, and the multiple non-metal layers 122 are respectively located on both sides of the metal layer 121. The embodiments of the present disclosure do not limit the number of the non-metal layers 122 and the positions of stacking with the metal layer 121.

[0074] For example, the material of the metal layer 121 can be silver, aluminum, gold, chromium, molybdenum, indium, silver-gold alloy, silver-indium alloy, indium-zinc alloy, etc. For example, the thickness of the metal layer 121 ranges from 1 nm to 50 nm. For example, the thickness of the metal layer 121 can be 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, etc., and will not be listed one by one here. The embodiments of the present disclosure do not limit the material, thickness, etc. of the metal layer 121.

[0075] For example, the material of the non-metal layer 122 may be silicon dioxide (SiO2), titanium dioxide (TiO2), niobium pentoxide (Nb2O5), tantalum pentoxide (Ta2O5), aluminum oxide (Al2O3), zirconium dioxide (ZrO2), cerium dioxide (CeO2), hafnium dioxide (HfO2), silicon nitride (Si3N4), zinc sulfide (ZnS), etc. For example, the thickness of the non-metal layer 122 ranges from 1 nm to 250 nm. For example, the thickness of the non-metal layer 122 may be 5 nm, 50 nm, 100 nm, 150 nm, 200 nm, etc., which will not be listed one by one here. The embodiments of the present disclosure do not limit the number, material, thickness, etc. of the non-metal layer 122.

[0076] In some examples, the visible light transmittance and reflectance of the beam splitting film 120 are 20 - 80% respectively, and the visible light absorptance of the beam splitting film 120 is not greater than 25%. For example, the transmittance and reflectance of the beam splitting film 120 are 50% and 50% respectively, or the transmittance and reflectance of the beam splitting film 120 are 40% and 60% respectively, which will not be elaborated one by one here.

[0077] In some examples, as Figure 4 shown, the polarization reflection film 150 of the optical structure 100 is located on the side of the phase retardation film 140 away from the first surface 110a. However, the embodiments of the present disclosure do not limit this.

[0078] In some examples, as Figure 4 shown, the optical structure 100 further includes a polarization absorption film 160, and the polarization absorption film 160 is located on the side of the polarization reflection film 150 away from the first surface 110a.

[0079] In some examples, as Figure 5 shown, the beam splitting film 120 may be in contact with the lens, and the beam splitting film 120 is directly attached to the lens structure 110. However, the embodiments of the present disclosure do not limit this. Figure 6 For Figure 4 another partial enlarged cross-sectional schematic diagram of the optical structure shown. As Figure 6 shown, the optical structure 100 may further include an adhesive film 170, and the adhesive film 170 is located between the beam splitting film 120 and the lens structure 110. The adhesive film 170 is configured to bond the beam splitting film 120 to the lens structure 110. The embodiments of the present disclosure do not limit the material, thickness, etc. of the adhesive film 170.

[0080] Figure 7 It is a graph showing the reflectance and transmittance of light incident on a beam splitting film provided by an embodiment of the present disclosure at different incident angles. Figure 7shows the reflectivity Ra and transmittance Ta of an incident light when the incident angle of the incident light on the beam splitting film provided by the embodiment of the present disclosure is 0 degree, as well as the transmittance Ts of the S polarization component and the transmittance Tp of the P polarization component of the incident light when the incident angle of the incident light is 40 degrees. As Figure 7 shown, when the incident angle is 40 degrees, the transmittance Ts of the S polarization component and the transmittance Tp of the P polarization component of the incident light are both basically equal to the target values (the target values are both 50%), and the difference between the transmittance Ts of the S polarization component and the transmittance Tp of the P polarization component is small. In contrast Figure 3 shown, when the incident angle is 40 degrees, the difference between the transmittance Ts of the S polarization component and the transmittance Tp of the P polarization component of the beam splitting film provided with a metal layer for the incident light is much smaller than the difference between the transmittance Ts of the S polarization component and the transmittance Tp of the P polarization component of the dielectric beam splitting film. Thus, by providing a metal layer in the beam splitting film, the consistency between the transmittance of the P polarization component of the incident light and the transmittance Ts of the S polarization component can be improved, the influence on the ellipticity of the incident light can be reduced, and the ellipticity of the incident light can be made as close to 1 as possible.

[0081] Figure 8 is a partially enlarged cross-sectional schematic diagram of the beam splitting film provided by the embodiment of the present disclosure after coating with a protective layer; Figure 9 is Figure 8 a graph showing the reflectivity and transmittance of the light incident on the beam splitting film and the protective layer shown in Figure 10 is Figure 8 another graph showing the reflectivity and transmittance of the light incident on the beam splitting film and the protective layer shown in

[0082] As Figure 8As shown, the beam splitting film 120 includes a metal layer 121 and multiple non-metal layers 122. The material of the metal layer 121 is silver (Ag), and its thickness is 19.9 nm. The materials of the non-metal layers 122a and 122b of the metal layer 121 close to the lens structure 110 are aluminum oxide (Al2O3) and titanium dioxide (TiO2) respectively, and their thicknesses are 215.3 nm and 63.6 nm respectively; the materials of the non-metal layers 122c and 122d of the metal layer 121 far from the lens structure 110 are aluminum oxide (Al2O3) and silicon dioxide (SiO2) respectively, and their thicknesses are 79.1 nm and 286.1 nm respectively. In order to protect the metal layer 121 of the beam splitting film 120 from being corroded and oxidized, a protective layer 10 can be coated or plated on the surface of the beam splitting film 120. For example, an acrylic coating with a thickness of 2 μm can be coated by wet method, or a parylene C barrier layer with a thickness of about 200 nm can be plated by chemical vapor deposition (CVD). The protective layer 10 shown in the figure is an acrylic coating.

[0083] Figure 9 It shows the reflectivity Ra and transmittance Ta of the incident light when the incident light does not pass through air but directly enters the beam splitting film 120 from within the protective layer 10 and then enters the lens structure 110 at an incident angle of 0 degrees, as well as the transmittance Ts of the S polarization component and the transmittance Tp of the P polarization component of the incident light when the incident angle of the incident light is 40 degrees, as Figure 9 shown, when the incident angle of the incident light is 0 degrees, both the reflectivity Ra and transmittance Ta of the incident light are basically equal to the target values (both target values are 50%), and when the incident angle of the incident light is 40 degrees, both the transmittance Ts of the S polarization component and the transmittance Tp of the P polarization component of the incident light are basically equal to the target values (both target values are 50%), and the beam splitting film 120 has an ideal beam splitting effect.

[0084] However, when a protective layer 10 with a thickness ranging from several hundred nanometers to several micrometers is formed on the surface of the beam splitting film 120, the protective layer 10 always has a limited thickness and the thickness is in the micrometer order of magnitude, and there is always an interface between the protective layer 10 and air. Due to the interference of light on the upper and lower surfaces of the protective layer 10, the reflection spectrum and transmission spectrum of the beam splitting film 120 will be superimposed with interference fringes, making the beam splitting film 120 no longer meet its due broadband beam splitting characteristics.

[0085] Figure 10 It shows the reflectivity Ra and transmittance Ta of the incident light when the incident light enters from air into the protective layer 10, the beam splitting film 120 and then enters the lens structure 110 at an incident angle of 0 degrees, as well as the transmittance Ts of the S polarization component and the transmittance Tp of the P polarization component of the incident light when the incident angle of the incident light is 40 degrees. AsFigure 10 As shown, when the incident angle of the incident light is 0 degrees, both the reflectance Ra and the transmittance Ta of the incident light deviate from the target values (both target values are 50%), and when the incident angle of the incident light is 40 degrees, both the transmittance Ts of the S polarization component and the transmittance Tp of the P polarization component deviate from the target values (both target values are 50%), and the beam splitting film 120 has lost its beam splitting function.

[0086] Therefore, directly disposing the protective layer 10 with a constant refractive index on the surface of the beam splitting film 120 will damage the beam splitting effect of the beam splitting film 120. However, by disposing the structural layer 131 with a refractive index gradually decreasing along the reference direction X on the surface of the beam splitting film 120, the structural layer 131 can avoid the generation of interference fringes of the incident light on the structural layer 131 and avoid the adverse effects of the light-transmitting protective film 130 on the reflection spectrum and the transmission spectrum of the beam splitting film 120. Thus, the light-transmitting protective film 130 can not only protect the metal layer 121 of the beam splitting film 120, but also the light-transmitting protective film 130 does not affect the broadband beam splitting characteristics of the beam splitting film 120.

[0087] Figure 11 It is a schematic diagram of a refractive index change of a structural layer of the light-transmitting protective film provided by an embodiment of the present disclosure. As Figure 11 shown, the refractive index of the structural layer of the light-transmitting protective film may be continuously decreasing along the reference direction. The left end of the abscissa is the side of the structural layer close to the beam splitting film, and the right end of the abscissa is the side of the structural layer far from the beam splitting film. The refractive index of the structural layer may be continuously decreasing along the reference direction. The embodiment of the present disclosure does not specifically limit the continuously decreasing trend. For example, the continuously decreasing trend may be a straight line with a linear change, a curve with an exponential change, or a change trend in other forms of change. For example, the curve with an exponential change may be a square, a cube, or a fifth power, etc.

[0088] Figure 12 It is another partial enlarged cross-sectional schematic diagram of the light-transmitting protective film provided by an embodiment of the present disclosure. As Figure 12 shown, the structural layer 131 of the light-transmitting protective film 130 includes a plurality of convex structures 1310. Along the reference direction X, the cross-sectional dimension d1 of the convex structure 1310 gradually decreases, and the cross-sectional dimension d1 of the convex structure 1310 is perpendicular to the reference direction X. By providing the convex structure 1310 and the cross-sectional dimension d1 of the convex structure 1310 gradually decreasing, the refractive index of the structural layer 131 can be continuously decreased along the reference direction X. For example, the plurality of convex structures may be evenly distributed, and the height ratio of different convex structures is 0.8 to 1.2.

[0089] In some examples, as Figure 12 shown, along the reference direction X, the cross-sectional areas of the plurality of convex structures 1310 are continuously decreasing, and the cross-section of the convex structure 1310 is perpendicular to the reference direction X.

[0090] In some examples, such as Figure 12 shown, the side L of the longitudinal section of the convex structure 1310 includes a straight line segment, and the longitudinal section is parallel to the reference direction X. For example, the slope of the straight line segment can be designed according to the requirements of the light-transmissive protective film 130 or the manufacturing process, etc. The present disclosure embodiment does not limit the outer contour of the convex structure 1310, and can be designed according to requirements and the manufacturing process, etc.

[0091] For example, as Figure 12 shown, the shape of the convex structure 1310 can be conical, and the shape of the longitudinal section of the cone can be triangular.

[0092] Figure 13 Another partial enlarged cross-sectional schematic diagram of the light-transmissive protective film provided by the embodiment of the present disclosure. As Figure 13 shown, the structural layer 131 of the light-transmissive protective film 130 includes a plurality of convex structures 1310. Along the reference direction X, the cross-sectional dimension d1 of the convex structure 1310 gradually decreases, and the cross-sectional dimension d1 of the convex structure 1310 is perpendicular to the reference direction X. By providing the convex structure 1310 and the cross-sectional dimension d1 of the convex structure 1310 gradually decreasing, the refractive index of the structural layer 131 can be continuously decreased along the reference direction X.

[0093] In some examples, such as Figure 13 shown, the side L of the longitudinal section of the convex structure 1310 includes a curved line segment, and the longitudinal section is parallel to the reference direction X. For example, the shape of the convex structure 1310 can be a shape similar to a warhead.

[0094] Figure 14 Another partial enlarged cross-sectional schematic diagram of the light-transmissive protective film provided by the embodiment of the present disclosure. As Figure 14 shown, the structural layer 131 of the light-transmissive protective film 130 includes a plurality of convex structures 1310. Along the reference direction X, the cross-sectional dimension d1 of the convex structure 1310 gradually decreases, and the cross-sectional dimension d1 of the convex structure 1310 is perpendicular to the reference direction X. For example, the shape of the convex structure 1310 can be frustum-shaped, and the shape of the longitudinal section of the frustum can be trapezoidal.

[0095] In some examples, such as Figures 12 to 14 shown, the value range of the maximum height H of the convex structure 1310 in the reference direction X is 50 nm to 200 nm. The maximum height H of the convex structure 1310 in the reference direction X is also the maximum thickness of the convex structure 1310 in the reference direction X. The present disclosure embodiment does not limit the value of the maximum height H, and can be designed according to the requirements of the light-transmissive protective film 130 and the manufacturing process, etc. For example, the value of the maximum height H can be 80 nm, 100 nm, 130 nm, 150 nm, 180 nm, etc., and will not be listed one by one here.

[0096] Figures 12 to 14 It is schematically shown that the heights of the convex structures 1310 in the reference direction X are equal. However, the embodiments of the present disclosure do not limit this. The heights of the convex structures 1310 at different positions in the reference direction X may also be different, and can be specifically designed according to the requirements of the light-transmitting protective film 130 and the manufacturing process, etc.

[0097] In some examples, such as Figures 12 to 14 shown, the transverse dimension d1 of the convex structure 1310 gradually decreases along the reference direction X, and the convex structure 1310 has a maximum transverse dimension d1. The value range of the maximum value of the transverse dimension d1 of the convex structure 1310 is from 10 nm to 200 nm. The embodiments of the present disclosure do not limit the numerical value of the maximum value of the transverse dimension d1, and can be designed according to the requirements of the light-transmitting protective film 130 and the manufacturing process, etc. For example, the numerical value of the maximum value of the transverse dimension d1 can be 20 nm, 50 nm, 80 nm, 100 nm, 130 nm, 150 nm, 180 nm, etc., and will not be listed one by one here.

[0098] In some examples, such as Figures 12 to 14 shown, along the reference direction X, the spacing between two adjacent convex structures 1310 gradually increases, and there is a minimum spacing between two adjacent convex structures 1310. Figures 12 to 14 It is schematically shown that the minimum spacing between two adjacent convex structures 1310 is 0. However, the embodiments of the present disclosure do not limit this. The value range of the minimum spacing between two adjacent convex structures 1310 is from 0 to 200 nm, and can be designed according to the requirements of the light-transmitting protective film 130 and the manufacturing process, etc. For example, the numerical value of the minimum spacing d2 can be 10 nm, 50 nm, 100 nm, 130 nm, 150 nm, 180 nm, etc., and will not be listed one by one here.

[0099] In some examples, Figure 12 and Figure 13 It is schematically shown that the materials of the base layer 132 and the structure layer 131 of the light-transmitting protective film 130 are the same. For example, the base layer 132 and the structure layer 131 can be an integrally arranged structure. Figure 14 It is schematically shown that the materials of the base layer 132 and the structure layer 131 of the light-transmitting protective film 130 are different. The embodiments of the present disclosure do not limit this. The materials of the base layer 132 and the structure layer 131 can be the same or different.

[0100] For example, multiple convex structures 1310 are arranged in an array in the plane where the light-transmitting protective film 130 is located.

[0101] In some examples, such as Figure 12 and Figure 13As shown, when the materials of the base layer 132 and the structural layer 131 of the light-transmitting protective film 130 are the same, the materials constituting the base layer 132 and the structural layer 131 can be deposited first, and then a plurality of convex structures 1310 can be directly formed on the surface of the deposited materials. For example, a plurality of convex structures 1310 can be formed by chemical etching, plasma etching, or nanoimprinting technology, etc.

[0102] In some examples, as Figure 14 shown, when the materials of the base layer 132 and the structural layer 131 of the light-transmitting protective film 130 are different, a first material can be used to form the base layer 132 first, then a second material is coated on the surface of the base layer 132, and then a plurality of convex structures 1310 are directly formed on the surface of the second material. For example, a plurality of convex structures 1310 can be formed by chemical etching, plasma etching, or nanoimprinting technology, etc.

[0103] Figure 15 This is another schematic diagram of the refractive index change of the structural layer of the light-transmitting protective film provided by the embodiments of the present disclosure. As Figure 15 shown, the refractive index of the structural layer of the light-transmitting protective film can be stepwise decreasing along the reference direction X. The figure shows that the structural layer of the light-transmitting protective film has 4 decreasing steps. The embodiments of the present disclosure do not specifically limit the number of decreasing steps of the refractive index of the structural layer of the light-transmitting protective film, nor do they specifically limit the difference between the gradients. For example, the number of decreasing steps of the refractive index of the structural layer is greater than or equal to 3.

[0104] Figure 16 This is another partial enlarged cross-sectional schematic diagram of the beam splitting film and the light-transmitting protective film of the optical structure provided by the embodiments of the present disclosure. As Figure 16 shown, the structural layer 131 includes at least three structural sub-layers 1311. The at least three structural sub-layers 1311 are arranged in sequence along the reference direction X and the refractive indices of the at least three structural sub-layers 1311 decrease in sequence along the reference direction X. The figure schematically shows that the structural layer 131 includes six structural sub-layers 1311. The six structural sub-layers 1311 are arranged in sequence along the reference direction X and the refractive indices of the six structural sub-layers 1311 decrease in sequence along the reference direction X. Of course, the embodiments of the present disclosure do not limit the number of structural sub-layers 1311 included in the structural layer 131.

[0105] In some examples, as Figure 16 shown, the material densities of the six structural sub-layers 1311 decrease in sequence along the reference direction X. The material density of the structural sub-layer 1311 is the proportion of the material in the unit volume. The material density of the structural sub-layer 1311 is positively correlated with the refractive index. The greater the density, the greater the refractive index, and the smaller the density, the smaller the refractive index. By making the material densities of the multiple structural sub-layers 1311 decrease in sequence along the reference direction X, the refractive indices of the multiple structural sub-layers 1311 can be made to decrease in sequence along the reference direction X.

[0106] For example, as Figure 16 shown, the materials of the six-layer structure sub-layer 1311 can be the same, and the refractive index can be changed by changing the material density. For example, the materials of the six-layer structure sub-layer 1311 and the base layer 132 can be the same. Of course, the embodiments of the present disclosure do not limit this. The materials of the multi-layer structure sub-layer 1311 can also be different, and the refractive index of the multi-layer structure sub-layer 1311 can be changed by the different refractive indices of different materials.

[0107] For example, as Figure 16 shown, the base layer 132 can be formed first, and then the refractive index of the subsequently deposited material can be gradually decreased by changing the deposition conditions, so that a multi-layer structure sub-layer 1311 with a gradually decreasing refractive index along the reference direction X can be formed. For example, by changing the deposition conditions, the deposited material can have pores, and different deposition conditions result in different pore densities or pore numbers, so that the material density of the structure sub-layer 1311 can be changed, and the refractive index of the multi-layer structure sub-layer 1311 can be achieved.

[0108] For example, the embodiments of the present disclosure are not limited thereto, and materials with different refractive indices can also be deposited separately to form a multi-layer structure sub-layer that gradually decreases along the reference direction X.

[0109] For example, as Figure 16 shown, the beam splitting film 120 includes a metal layer 121 and a multi-layer non-metal layer 122. The material of the metal layer 121 is silver (Ag), and the thickness is 19.8 nm; the materials of the non-metal layers 122a, 122b, 122c, and 122d are aluminum oxide (Al2O3), titanium dioxide (TiO2), aluminum oxide (Al2O3), and silicon dioxide (SiO2) respectively, and the thicknesses are 208.5 nm, 63.9 nm, 79.8 nm, and 260.8 nm respectively.

[0110] For example, as Figure 16 shown, the base layer 132 of the light-transmitting protective film 130 is an acrylic coating with a thickness of 2000 nm. The six-layer structure sub-layers 1311a, 1311b, 1311c, 1311d, 1311e, and 1311f are acrylic coatings with densities of 90%, 80%, 60%, 30%, 10%, and 5% respectively, and the thicknesses are 74.8 nm, 38.4 nm, 96.9 nm, 114.6 nm, 88.7 nm, and 70.8 nm respectively. The base layer 132 is also an acrylic coating with a density of 100%. For example, the thickness of the base layer 132 is greater than the thickness of at least one structure sub-layer 1311.

[0111] Figure 17 For Figure 16 the schematic diagram of the refractive index of the beam splitting film and the light-transmitting protective film shown; Figure 18 ForFigure 16 Graphs of the reflectance and transmittance of light incident on the beam splitting film and the light transmissive protective film at different incident angles. Figure 18 Shows Figure 16 the reflectance Ra and transmittance Ta of the incident light when the incident angle of the incident light on the beam splitting film and the light transmissive protective film is 0 degrees, and the transmittance Ts of the S polarization component and the transmittance Tp of the P polarization component of the incident light when the incident angle of the incident light is 40 degrees. As Figure 17 shown, the refractive indices of the six-layer structural sub-layer 1311 of the optical structure decrease in sequence. Figure 18 shown, when the incident angle of the incident light is 0 degrees, both the reflectance Ra and the transmittance Ta of the incident light are basically equal to the target values (both target values are 50%), and when the incident angle θ of the incident light is 40 degrees, both the transmittance Ts of the S polarization component and the transmittance Tp of the P polarization component of the incident light are basically equal to the target values (both target values are 50%), and the beam splitting film 120 has an ideal beam splitting effect.

[0112] In this example, a light transmissive protective film 130 is provided on the side of the beam splitting film 120 away from the lens structure 110. The structural layer 131 of the light transmissive protective film 130 includes multiple structural sub-layers 1311, and the refractive indices or densities of the multiple structural sub-layers 1311 decrease in sequence along the reference direction X. This structural layer 131 can prevent interference fringes from being generated on the structural layer 131 by the incident light, and prevent the light transmissive protective film 130 from having an adverse effect on the reflection spectrum and transmission spectrum of the beam splitting film 120. Thus, the light transmissive protective film 130 can not only protect the metal layer 121 of the beam splitting film 120, but also the light transmissive protective film 130 does not affect the broadband beam splitting characteristics of the beam splitting film 120.

[0113] Figure 19 Partial enlarged cross-sectional schematic diagram of the beam splitting film provided by the embodiment of the present disclosure after coating the protective layer; Figure 20 Is Figure 19 A graph of the reflectance and transmittance of light incident on the beam splitting film and the protective layer shown at different incident angles. Figure 20 Shows Figure 19 the reflectance Ra and transmittance Ta of the incident light when the incident angle of the incident light on the beam splitting film and the protective layer is 0 degrees, and the transmittance Ts of the S polarization component and the transmittance Tp of the P polarization component of the incident light when the incident angle of the incident light is 40 degrees. As Figure 19As shown, the beam splitting film 120 of the optical structure includes a metal layer 121 and multiple non-metal layers 122. The material of the metal layer 121 is silver (Ag), and its thickness is 19.3 nm. The materials of the non-metal layers 122a, 122b, and 122c are aluminum oxide (Al2O3), titanium dioxide (TiO2), and aluminum oxide (Al2O3) respectively, and their thicknesses are 161.2 nm, 61.0 nm, and 53.1 nm respectively. The surface of the beam splitting film 120 of the optical structure is also coated with a protective layer 10. The material of the protective layer 10 is parylene C, and its thickness is 500 nm. Figure 20 is a graph showing the incident light entering the lens structure 110 from the air through the protective layer 10 and the beam splitting film 120. As Figure 20 shown, when the incident angle of the incident light is 0 degrees, both the reflectivity Ra and the transmittance Ta of the incident light deviate from the target values (both target values are 50%). When the incident angle θ of the incident light is 40 degrees, both the transmittance Ts of the S polarization component and the transmittance Tp of the P polarization component of the incident light deviate from the target values (both target values are 50%), and the beam splitting film 120 has lost its beam splitting function. Therefore, directly coating the protective layer 10 with a constant refractive index on the surface of the beam splitting film 120 will damage the beam splitting effect of the beam splitting film 120.

[0114] Figure 21 is another partially enlarged cross-sectional schematic diagram of the beam splitting film and the light-transmitting protective film of the optical structure provided by the embodiment of the present disclosure. As Figure 21 shown, the structural layer 131 includes three structural sub-layers 1311. The three structural sub-layers 1311 are arranged in sequence along the reference direction X, and the refractive indices of the three structural sub-layers 1311 decrease in sequence along the reference direction X.

[0115] In some examples, as Figure 21 shown, the material densities of the three structural sub-layers 1311 decrease in sequence along the reference direction X.

[0116] For example, as Figure 21 shown, the beam splitting film 120 includes a metal layer 121 and multiple non-metal layers 122. The material of the metal layer 121 is silver (Ag), and its thickness is 19.3 nm. The materials of the non-metal layers 122a, 122b, and 122c are aluminum oxide (Al2O3), titanium dioxide (TiO2), and aluminum oxide (Al2O3) respectively, and their thicknesses are 161.2 nm, 61.0 nm, and 53.1 nm respectively.

[0117] For example, as Figure 21As shown, the material of the base layer 132 of the light-transmitting protective film 130 is parylene C, with a thickness of 300 nm. The three-layer sub-layers 1311a, 1311b, and 1311c are parylene C with densities of 90%, 40%, and 10% respectively, and the thicknesses are 102.2 nm, 103.2 nm, and 90.7 nm respectively. The base layer 132 is also parylene C with a density of 100%. Parylene C is a commonly used polymer waterproof barrier film, which can form a transparent film and has a low water vapor transmission rate.

[0118] Figure 22 is Figure 21 a schematic diagram of the refractive indices of the beam splitting film and the light-transmitting protective film shown; Figure 23 is Figure 21 a graph of the reflectance and transmittance of the light incident on the beam splitting film and the light-transmitting protective film at different incident angles shown. Figure 23 shows Figure 21 the reflectance Ra and transmittance Ta of the incident light when the incident angle of the incident light on the beam splitting film and the light-transmitting protective film shown is 0 degrees, and the transmittance Ts of the S polarization component and the transmittance Tp of the P polarization component of the incident light when the incident angle of the incident light is 40 degrees. As Figure 22 shown, the refractive indices of the three-layer sub-layers 1311 of the optical structure 100 decrease in sequence. As Figure 23 shown, when the incident angle of the incident light is 0 degrees, both the reflectance Ra and the transmittance Ta of the incident light are near the target values (both target values are 50%). When the incident angle of the incident light is 40 degrees, both the transmittance Ts of the S polarization component and the transmittance Tp of the P polarization component of the incident light are near the target values (both target values are 50%). The beam splitting film 120 has an ideal beam splitting effect.

[0119] Figure 24 This is another partial enlarged cross-sectional schematic diagram of the beam splitting film and the light-transmitting protective film of the optical structure provided by the embodiment of the present disclosure. As Figure 24 shown, the sub-layer 1311 includes a nanoparticle coating, and the porosity of at least three sub-layers 1311 increases in sequence along the reference direction X. The porosity of the nanoparticle coating is the proportion of the pores between the nanoparticles in the unit volume. The porosity of the nanoparticle coating is negatively correlated with the refractive index. The larger the porosity, the smaller the refractive index, and the smaller the porosity, the larger the refractive index. By making the porosity of the multi-layer sub-layers 1311 increase in sequence along the reference direction X, the refractive indices of the multi-layer sub-layers 1311 can be made to decrease in sequence along the reference direction X.

[0120] In this example, as schematically shown in the figure, the structural layer 131 includes four structural sub-layers 1311a, 1311b, 1311c, and 1311d. The four structural sub-layers 1311a, 1311b, 1311c, and 1311d are all nanoparticle coatings, and the porosity of the four nanoparticle coatings 1311a, 1311b, 1311c, and 1311d increases sequentially along the reference direction X. Of course, the embodiments of the present disclosure do not limit the number of nanoparticle coatings included in the structural layer 131.

[0121] In some examples, such as Figure 24 shown, the material of the base layer 132 may be the same as or different from the material of the nanoparticle coating, and no limitation is made here.

[0122] In some examples, the materials of the base layer of the light-transmissive protective film include acrylic, polyurethane, epoxy, amino resin, polyester resin, silicone, etc. For example, the base layer can be formed by solution coating, chemical bath deposition (CBD), or sol-gel method. For example, the material of the base layer can also be parylene and its derivatives, poly(hexamethyldisiloxane) (ppHMDSO), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), etc. For example, it can be formed by chemical vapor deposition (CVD), physical vapor deposition (PVD), plasma polymerization (PP), molecular layer deposition (MLD), atomic layer deposition (ALD), etc. The embodiments of the present disclosure do not limit the material and formation process of the base layer.

[0123] In some examples, the materials of the structural layer of the light-transmissive protective film include at least one of acrylic, polyurethane, epoxy, amino resin, polyester resin, silicone, parylene and its derivatives, poly(hexamethyldisiloxane), polytetrafluoroethylene, and polyvinylidene fluoride.

[0124] For example, the material of the base layer may be the same as or different from the material of the structural layer.

[0125] In some examples, the thickness of the base layer ranges from 100 nm to 5 μm. The embodiments of the present disclosure do not limit the thickness of the base layer, which can be designed according to the requirements of the light-transmissive protective film and the manufacturing process, etc. For example, the thickness of the base layer can be 200 nm, 600 nm, 800 nm, 1 μm, 2 μm, 3 μm, 4 μm, etc., and will not be listed one by one here.

[0126] In some examples, the thickness of the structural layer ranges from 50 nm to 200 nm. The embodiments of the present disclosure do not limit the thickness of the structural layer, and it can be designed according to the requirements of the light-transmissive protective film and the manufacturing process, etc. For example, the thickness of the structural layer can be 60 nm, 80 nm, 100 nm, 150 nm, etc., and will not be listed one by one here.

[0127] In some examples, the total thickness of the light-transmissive protective film ranges from 100 nm to 10 μm. The embodiments of the present disclosure do not limit the total thickness of the light-transmissive protective film, and it can be designed according to the requirements of the light-transmissive protective film and the manufacturing process, etc. For example, the total thickness of the light-transmissive protective film can be 200 nm, 600 nm, 800 nm, 1 μm, 3 μm, 5 μm, 8 μm, etc., and will not be listed one by one here. The structural layer with a decreasing refractive index of the light-transmissive protective film can avoid the generation of interference fringes of incident light on the structural layer, so that the light-transmissive protective film with a micron or sub-micron thickness will not affect the broadband beam splitting characteristics of the beam splitting film.

[0128] The embodiments of the present disclosure provide a display device. Figure 25 It is a schematic cross-sectional view of a display device provided by the embodiments of the present disclosure. As Figure 25 shown, the display device 200 includes a display screen 210 and any one of the above optical structures 100, and the display screen 210 is located on the light incident side S1 of the optical structure 100. Thus, the display device 200 has the beneficial effects corresponding to those of the optical structure 100, which will not be elaborated here.

[0129] In some examples, as Figure 25 shown, the display screen 210 includes a micro organic light emitting diode display screen (microOLED). When the display screen is a micro organic light emitting diode display screen (microOLED), the maximum incident angle θ of the light emitted from the display screen 210 to the beam splitting film 120 is relatively large. For example, the incident angle θ is greater than 20 degrees. For example, the incident angle θ is between 20 degrees and 50 degrees. Through the optical structure 100 described above, the consistency of the transmittance of the P polarization component and the transmittance Ts of the S polarization component of the incident light can be improved, and the light-transmissive protective film 130 can protect the metal layer 121 of the beam splitting film 120, and the light-transmissive protective film 130 will not affect the broadband beam splitting characteristics of the beam splitting film 120.

[0130] For example, the size of the display screen 210 or the micro organic light emitting diode display screen 210 is between 0.8 inches and 1.6 inches. For example, the diameter size of the lens of the lens structure 110 is 4 - 5 cm. For example, the ratio of the diameter of the lens of the lens structure 110 to the diagonal size of the display screen 210 is greater than or equal to 1.5.

[0131] For example, the display device 200 may be a near-eye display device 200 for virtual reality (VR) or mixed reality (MR).

[0132] Embodiments of the present disclosure also provide a depolarization beam splitting structure. Figure 26 FIG. is a partial enlarged cross-sectional schematic diagram of a depolarization beam splitting structure provided by an embodiment of the present disclosure. As Figure 26 shown, the depolarization beam splitting structure 300 includes a beam splitting film 120 and a light-transmitting protective film 130 which are stacked, and the light-transmitting protective film 130 is located on the surface of the beam splitting film 120 and in contact with the beam splitting film 120. The beam splitting film 120 includes a metal layer 121 and at least one non-metal layer 122 stacked with the metal layer 121. The light-transmitting protective film 130 includes a structural layer 131, and the refractive index of the structural layer 131 gradually decreases along the reference direction X, and the reference direction X is the direction from the beam splitting film 120 to the light-transmitting protective film 130. In the figure, it is schematically shown that the beam splitting film 120 includes a metal layer 121 and multiple non-metal layers 122, and the multiple non-metal layers 122 are respectively located on both sides of the metal layer 121, but the embodiments of the present disclosure do not limit this.

[0133] In the depolarization beam splitting structure provided by the embodiments of the present disclosure, the beam splitting film 120 includes a metal layer 121. Since the reflection and transmission of the metal material are insensitive to polarization, when the incident angle θ of the incident light L0 incident on the beam splitting film 120 is relatively large (for example, when the incident angle θ is greater than 20 degrees), compared with a dielectric beam splitting film, the beam splitting film 120 provided with the metal layer 121 can make the transmittance Tp of the P polarization component of the incident light L0 and the transmittance Ts of the S polarization component have a smaller difference, which can improve the consistency of the transmittance of the P polarization component of the incident light L0 and the transmittance Ts of the S polarization component, thereby reducing the influence on the ellipticity of the incident light L0 and making the ellipticity of the incident light L0 as close to 1 as possible.

[0134] In this embodiment, a light-transmitting protective film 130 in contact with the beam splitting film 120 is further provided on the surface of the beam splitting film 120. The light-transmitting protective film 130 can protect the metal layer 121 in the beam splitting film 120 from corrosion and oxidation. Moreover, the light-transmitting protective film 130 includes a structural layer 131, and the refractive index of the structural layer 131 gradually decreases along the reference direction X. This structural layer 131 can prevent interference fringes from being generated on the structural layer 131 by the incident light, and avoid adverse effects on the reflection spectrum and transmission spectrum of the beam splitting film 120 by the light-transmitting protective film 130. Thus, the light-transmitting protective film 130 can not only protect the metal layer 121 of the beam splitting film 120, but also the light-transmitting protective film 130 does not affect the broadband beam splitting characteristics of the beam splitting film 120.

[0135] In some examples, such as Figure 26As shown, the light-transmitting protective film 130 further includes a base layer 132, which is closer to the beam-splitting film 120 than the structural layer 131. The base layer 132 is in contact with the beam-splitting film 120 and is configured to protect the beam-splitting film 120. The base layer 132 of the light-transmitting protective film 130 can protect the metal layer 121 of the beam-splitting film 120, isolate water vapor and oxygen in the air, and avoid corrosion and oxidation of the metal layer 121.

[0136] For example, the beam-splitting film 120 and the light-transmitting protective film 130 in the depolarization beam-splitting structure provided by the embodiments of the present disclosure are the same as the beam-splitting film 120 and the light-transmitting protective film 130 in the optical structure 100 described above, and will not be described in detail herein.

[0137] For example, the depolarization beam-splitting structure 300 can be used in a head-up display (HUD) scenario or the like.

[0138] The following points need to be noted:

[0139] (1) In the drawings of the embodiments of the present disclosure, only the structures related to the embodiments of the present disclosure are involved, and other structures can refer to the general design.

[0140] (2) Without conflict, the features in the same embodiment and different embodiments of the present disclosure can be combined with each other.

[0141] The above is only the specific implementation manner of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present disclosure, and all should be covered by the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be subject to the protection scope of the claims.

Claims

1. An optical structure having a light incident side and a light exit side, comprising: A lens structure including a first surface and a second surface disposed opposite to each other, wherein the first surface is the surface of the light incident side of the lens structure and the first surface is a curved surface; A beam splitting film located on the side of the first surface away from the second surface; A light transmissive protective film located on the side of the beam splitting film away from the first surface and in contact with the beam splitting film; A phase retardation film located on the side of the second surface away from the first surface; And A polarization reflective film located on the side of the second surface away from the first surface, wherein the beam splitting film includes a metal layer, the light transmissive protective film includes a structural layer, and the refractive index of the structural layer gradually decreases along a reference direction, and the reference direction is the direction from the beam splitting film to the light transmissive protective film.

2. The optical structure according to claim 1, wherein The light transmissive protective film further includes a base layer, the base layer is closer to the beam splitting film than the structural layer, the base layer is in contact with the beam splitting film and is configured to protect the beam splitting film.

3. The optical structure according to claim 2, wherein, The refractive index of the base layer is not less than the maximum refractive index of the structural layer.

4. The optical structure according to claim 3, wherein, The structural layer includes a plurality of protruding structures, and along the reference direction, the cross-sectional dimension of the protruding structures gradually decreases, and the cross-sectional dimension of the protruding structures is perpendicular to the reference direction.

5. The optical structure according to claim 4, wherein, The side of the longitudinal section of the protruding structure includes at least one of a straight line segment or a curved line segment, and the longitudinal section is parallel to the reference direction.

6. The optical structure according to claim 4, wherein, The value range of the maximum height of the protruding structure in the reference direction is 50 nm to 200 nm, and the value range of the minimum distance between adjacent two protruding structures is 0 to 200 nm.

7. The optical structure according to any one of claims 1-3, wherein, The refractive index of the structural layer decreases step by step along the reference direction and has at least 3 decreasing steps.

8. The optical structure according to claim 7, wherein, The structural layer includes at least three structural sub-layers, the at least three structural sub-layers are arranged in sequence along the reference direction, and the refractive indices of the at least three structural sub-layers gradually decrease along the reference direction.

9. The optical structure according to claim 8, wherein, The material densities of the at least three structural sub-layers gradually decrease along the reference direction.

10. The optical structure according to claim 8, wherein, The structural sub-layer includes a nanoparticle coating, and the porosities of the at least three structural sub-layers gradually increase along the reference direction.

11. The optical structure according to claim 2 or 3, wherein, The material of the base layer of the light transmissive protective film includes at least one of acrylic acid, polyurethane, epoxy, amino resin, polyester resin, silicone, poly-p-xylene and its derivatives, polydimethylsiloxane, polytetrafluoroethylene, and polyvinylidene fluoride, and the material of the structural layer of the light transmissive protective film includes at least one of acrylic acid, polyurethane, epoxy, amino resin, polyester resin, silicone, poly-p-xylene and its derivatives, polydimethylsiloxane, polytetrafluoroethylene, and polyvinylidene fluoride.

12. The optical structure according to claim 2 or 3, wherein, The value range of the thickness of the base layer is 100 nm to 5 μm, and the value range of the thickness of the structural layer is 50 nm to 200 nm.

13. The optical structure according to any one of claims 1-3, wherein, The beam splitting film further includes at least one non-metallic layer stacked with the metal layer.

14. The optical structure according to any one of claims 1-3, further comprising: A polarization absorption film located on the side of the polarization reflective film away from the first surface.

15. A display device, comprising a display screen and the optical structure according to any one of claims 1-14, wherein, The display screen is located on the light incident side of the optical structure.

16. The display device according to claim 15, wherein, The display screen includes a micro-organic light-emitting diode display screen.

17. A depolarizing beam splitting structure, comprising a beam splitting film and a light-transmitting protective film which are stacked, Among them, The light-transmitting protective film is in contact with the beam splitting film. The beam splitting film includes a metal layer and at least one non-metal layer stacked with the metal layer. The light-transmitting protective film includes a structural layer, and the refractive index of the structural layer gradually decreases along a reference direction, and the reference direction is the direction from the beam splitting film to the light-transmitting protective film.

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