Polarization multiplexing dodging device, polarization multiplexing dodging method and micro projection light engine

Abstract

The invention provides a polarization multiplexing dodging device, a polarization multiplexing dodging method and a micro-projection light engine. The polarization multiplexing dodging device comprises: a light-transmitting substrate; the super-lens layer comprises a plurality of super-lens units which are arranged on the light incident surface in a two-dimensional array mode and is used for converging the first circularly polarized light and the second circularly polarized light to different focal points respectively; the phase delay array layer comprises a plurality of phase delay units which are arranged on the light emitting surface in a one-dimensional array mode and correspond to the row of super-lens units, each phase delay unit comprises a first phase delay piece and a second phase delay piece, fast axes of the first phase delay piece and the second phase delay piece are perpendicular to each other, and the first phase delay piece and the second phase delay piece are used for converting the first circularly polarized light and the second circularly polarized light into linearly polarized light in the same polarization state; the CLC array layer comprises a plurality of CLC prisms which are arranged on the super-lens layer in a one-dimensional array mode and correspond to the phase delay units in a one-to-one mode, each CLC prism comprises a first prism, a second prism and a cholesteric liquid crystal film arranged between the first prism and the second prism, and the CLC prisms are used for transmitting the first circularly polarized light and reflecting the second circularly polarized light.

Description

Technical Field

[0001] The present invention relates to the technical field of optical projection, and particularly to a polarization multiplexing light homogenizing device, a polarization multiplexing light homogenizing method, and a micro-projection optical engine. Background Art

[0002] In a projection system based on liquid crystal displays such as LCOS (Liquid Crystal on Silicon), to meet its polarized light illumination conditions, a polarization multiplexing device is usually adopted in the projection system to convert the natural light emitted by the light source into polarized light. Since a PCS (polarizing conversion system) cycle unit in the existing polarization multiplexing device includes two prisms, one of which is a polarized beamsplitter (abbreviated as PBS), and a half-wave plate is arranged on the light-emitting side of the polarized beamsplitter, and the other prism is a beamsplitter with a high-reflection film plated on its inclined surface. Therefore, in order to ensure the normal operation of the polarization multiplexing device, an additional fly-eye lens array needs to be added between the polarization multiplexing device and the light source, so that the parallel incident natural light is respectively focused on the centers of multiple polarized beamsplitters through the fly-eye lens array. One path of P light first passes through the polarized beamsplitter and then is converted into S light through the half-wave plate, and the other path of S light is first reflected by the polarized beamsplitter and then reflected by the high-reflection film and emitted, ensuring that a beam of light with the same polarization state (S light) is formed after the output of the polarization multiplexing device to meet the polarized light illumination requirements of the LCOS display device.

[0003] However, the scheme of this polarization multiplexing device + fly-eye lens array has the following disadvantages: on the one hand, in the actual optical path assembly process of the polarization multiplexing device, the polarized beamsplitters in a PCS cycle unit need to correspond to the half-wave plates one by one, resulting in a relatively complex process assembly. And once there is an assembly error, it will reduce the purity of the polarized light emitted from the polarization multiplexing device, seriously affecting the projection quality; on the other hand, since the lens units in the fly-eye lens array are traditional curved lenses and need to correspond to the PCS cycle units in the polarization multiplexing device one by one, the assembly process of the fly-eye lens array and the polarization multiplexing device is relatively complex, and there is more efficiency waste due to assembly errors, seriously affecting the projection brightness. Summary of the Invention

[0004] An advantage of the present application is to provide a polarization multiplexing light homogenizing device, a polarization multiplexing light homogenizing method, and a micro-projection optical engine, which can effectively convert non-polarized light into polarized light with the same polarization state while reducing the assembly difficulty, improving the light efficiency and purity.

[0005] Another advantage of the present application lies in providing a polarization multiplexing light homogenizing device, a polarization multiplexing light homogenizing method, and a micro-projection optical engine. Among them, in one embodiment of the present invention, the polarization multiplexing light homogenizing device can be easily integrated into the system through planar design.

[0006] Another advantage of the present application lies in providing a polarization multiplexing light homogenizing device, a polarization multiplexing light homogenizing method, and a micro-projection optical engine. Among them, in one embodiment of the present invention, the polarization multiplexing light homogenizing device does not need to be aligned during installation and adjustment, which is beneficial to improving the light efficiency and purity of the system.

[0007] Another advantage of the present application lies in providing a polarization multiplexing light homogenizing device, a polarization multiplexing light homogenizing method, and a micro-projection optical engine. To achieve the above object, expensive materials or complex structures are not required in the present invention. Therefore, the present invention successfully and effectively provides a solution, not only providing a simple polarization multiplexing light homogenizing device, a polarization multiplexing light homogenizing method, and a micro-projection optical engine, but also increasing the practicability and reliability of the polarization multiplexing light homogenizing device, the polarization multiplexing light homogenizing method, and the micro-projection optical engine.

[0008] To achieve at least one of the above advantages or other advantages and objects of the present application, the present invention provides a polarization multiplexing light homogenizing device, including:

[0009] A light-transmitting substrate having an incident light surface and an outgoing light surface arranged opposite to each other;

[0010] A meta-lens layer including a plurality of nano-columns periodically arranged on the incident light surface to form a plurality of meta-lens units arranged in a two-dimensional array, wherein each meta-lens unit is used to converge the first circularly polarized light and the second circularly polarized light with opposite rotation directions to different focal points respectively;

[0011] A phase retardation array layer including a plurality of phase retardation units arranged in a one-dimensional array on the outgoing light surface, wherein each phase retardation unit corresponds to a row of the meta-lens units, and each phase retardation unit includes a first phase retardation member and a second phase retardation member with their fast axes perpendicular to each other. The first phase retardation member and the second phase retardation member are respectively used to modulate the phases of the first circularly polarized light and the second circularly polarized light to emit linearly polarized light with the same polarization state; and

[0012] A CLC array layer including a plurality of CLC prisms corresponding to the phase retardation units one by one. The plurality of CLC prisms are arranged in a one-dimensional array on the side of the meta-lens layer away from the phase retardation array layer, and each CLC prism includes a first prism, a second prism, and a cholesteric liquid crystal film disposed between the first prism and the second prism, which is used to transmit the first circularly polarized light and reflect the second circularly polarized light.

[0013] According to an embodiment of the present application, both the first phase retardation member and the second phase retardation member are quarter-wave plates, and the fast axis direction of the quarter-wave plate forms an angle of ±45° with the array arrangement direction of the phase retardation unit.

[0014] According to an embodiment of the present application, the period of the nanocolumns of the superlens units in the superlens layer is equal to the size of the CLC prism and / or the phase retardation unit in the array arrangement direction.

[0015] According to an embodiment of the present application, the phase retardation array layer is located at the focal plane of the superlens layer.

[0016] According to an embodiment of the present application, both the first prism and the second prism are right-angled prisms; the cholesteric liquid crystal film is located between the inclined surfaces of the first prism and the second prism.

[0017] According to an embodiment of the present application, both the first prism and the second prism are isosceles right-angled prisms.

[0018] According to an embodiment of the present application, the first prism in the CLC prism is integrally connected to the second prism in the adjacent CLC prism, so that the adjacent first prism and second prism jointly form a common prism with a parallelogram cross-section.

[0019] According to another aspect of the present application, the present application further provides a micro-projection light engine, including:

[0020] A light source assembly for emitting unpolarized light;

[0021] A polarization display assembly located on the light-emitting side of the light source assembly; and

[0022] Any one of the above-mentioned polarization multiplexing light homogenizing devices, which is disposed in the optical path between the light source assembly and the polarization display assembly, and is used to convert the unpolarized light from the light source assembly into linearly polarized light with the same polarization state to irradiate the polarization display assembly.

[0023] According to an embodiment of the present application, the polarization display assembly includes a relay unit, a display unit, and an imaging unit. The relay unit is disposed between the polarization multiplexing light homogenizing device, the display unit, and the imaging unit, and is used to first relay and transmit the linearly polarized light from the polarization multiplexing light homogenizing device to the display unit to be modulated into image light, and then relay and transmit the image light from the display unit to the imaging unit for projection imaging.

[0024] According to an embodiment of the present application, the display unit is an LCOS display device; the imaging unit is an imaging lens group; the relay unit includes a polarization beam splitting device and a polarization folding device. The polarization beam splitting device is located on the light output side of the polarization multiplexing light homogenizing device. The polarization folding device and the LCOS display device are respectively located on opposite sides of the polarization beam splitting device. The imaging lens group is located on the side of the polarization beam splitting device away from the polarization multiplexing light homogenizing device.

[0025] According to an embodiment of the present application, the display unit is an LCOS display device; the imaging unit is an imaging lens group; the relay unit includes a polarization beam splitting device and a polarization folding device. The polarization beam splitting device is located on the light output side of the polarization multiplexing light homogenizing device. The imaging lens group and the LCOS display device are respectively located on opposite sides of the polarization beam splitting device. The polarization folding device is located on the side of the polarization beam splitting device away from the polarization multiplexing light homogenizing device.

[0026] On the other hand of the present application, the present application further provides a polarization multiplexing light homogenizing method, including the steps of:

[0027] Transmitting the first circularly polarized light in the unpolarized light through a CLC prism in the CLC array layer to propagate to the meta-lens unit corresponding to the CLC prism in the meta-lens layer, and reflecting the second circularly polarized light in the unpolarized light with the opposite circular polarization direction to the first circularly polarized light to propagate to another CLC prism in the CLC array layer and be reflected to the meta-lens unit corresponding to the another CLC prism in the meta-lens layer;

[0028] Converging the first circularly polarized light by the meta-lens unit corresponding to the CLC prism in the meta-lens layer onto the first phase retardation element of the phase retardation unit corresponding to the CLC prism in the phase retardation array layer to be converted into linearly polarized light with a first polarization state; and

[0029] Converging the second circularly polarized light by the meta-lens unit corresponding to the another CLC prism in the meta-lens layer onto the second phase retardation element of the phase retardation unit corresponding to the another CLC prism in the phase retardation array layer to be converted into linearly polarized light with the first polarization state. Description of the Drawings

[0030] Figure 1 is a schematic structural diagram of a micro-projection optical engine according to an embodiment of the present application;

[0031] Figure 2 shows a first example of the polarization multiplexing light homogenizing device in the micro-projection optical engine according to the above embodiment of the present application;

[0032] Figure 3Shows a schematic diagram of the principle of the polarization multiplexing light homogenizing device according to the above first example of the present application;

[0033] Figure 4 Shows a schematic diagram of the structure of the metalens layer in the polarization multiplexing light homogenizing device according to the above first example of the present application;

[0034] Figure 5 Shows a schematic diagram of the structure of the phase retardation array layer in the polarization multiplexing light homogenizing device according to the above first example of the present application;

[0035] Figure 6 Shows a second example of the polarization multiplexing light homogenizing device in the micro - projection optical engine according to the above embodiment of the present application;

[0036] Figure 7 Shows a modified embodiment of the micro - projection optical engine according to the above embodiment of the present application;

[0037] Figure 8 Is a schematic flowchart of a polarization multiplexing light homogenizing method according to an embodiment of the present application.

[0038] Main element symbol description: 1. Micro - projection optical engine; 10. Light source assembly; 20. Polarization display assembly; 21. Relay unit; 211. Polarization beam splitter device; 212. Polarization retro - reflection device; 213. Relay lens group; 22. Display unit; 220. LCOS display device; 23. Imaging unit; 230. Imaging lens group; 30. Polarization multiplexing light homogenizing device; 31. Transparent substrate; 311. Light incident surface; 312. Light exit surface; 32. Metalens layer; 320. Metalens unit; 33. Phase retardation array layer; 330. Phase retardation unit; 331. First phase retardation element; 332. Second phase retardation element; 34. CLC array layer; 340. CLC prism; 3400. Common prism; 341. First prism; 342. Second prism; 343. Cholesteric liquid crystal film.

[0039] The above main element symbol description further elaborates on the present application in combination with the accompanying drawings and specific embodiments. Detailed Description of the Invention

[0040] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art can think of other obvious variations. The basic principles defined in the following description can be applied to other implementation schemes, variant schemes, improvement schemes, equivalent schemes, and other technical schemes without departing from the spirit and scope of the present invention.

[0041] Those skilled in the art should understand that in the disclosure of the present invention, the orientation or positional relationships indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings. These 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. Therefore, the above terms should not be construed as limitations on the present invention.

[0042] In the present invention, the term "a" in the claims and the specification should be understood as "one or more". That is, in one embodiment, the number of an element can be one, while in other embodiments, the number of this element can be multiple. Unless it is clearly indicated in the disclosure of the present invention that the number of the element is only one, the term "a" should not be understood as being unique or single, and the term "a" should not be construed as a limitation on the quantity.

[0043] In the description of the present invention, it should be understood that terms such as "first", "second", etc. are only used for descriptive purposes and cannot be construed as indicating or implying relative importance. In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "connected" and "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through a medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0044] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0045] Considering that in the actual optical path assembly process of the existing polarization multiplexing device + compound eye lens array solution, not only does a PCS cycle unit need to correspond the polarization beam splitter prism and the half-wave plate one by one, but also the lens units in the compound eye lens array need to correspond one by one, resulting in a relatively complex assembly process. And once there is an assembly error, it will reduce the purity and brightness of the emitted polarized light, seriously affecting the projection quality. Therefore, the present application creatively proposes a polarization multiplexing light homogenizing device, a polarization multiplexing light homogenizing method, and a micro-projection optical engine, which can effectively convert unpolarized light into polarized light with the same polarization state while reducing the assembly difficulty and improving the light efficiency and purity.

[0046] Specifically, referring to the accompanying drawings of the specification of the present application Figure 1 According to an embodiment of the present application, a micro-projection optical engine 1 is provided, which may include a light source assembly 10 for emitting unpolarized light, a polarization display assembly 20 located on the light-emitting side of the light source assembly 10, and a polarization multiplexing light homogenizing device 30 disposed in the optical path between the light source assembly 10 and the polarization display assembly 20. The polarization multiplexing light homogenizing device 30 is configured to convert the unpolarized light from the light source assembly 10 into linearly polarized light with the same polarization state to irradiate the polarization display assembly 20, and the polarization display assembly 20 is configured to generate image light based on the linearly polarized light for projection imaging. It can be understood that the unpolarized light mentioned in the present application may but is not limited to being implemented as natural light, which usually includes a first circularly polarized light and a second circularly polarized light with opposite rotation directions; for example, when the first circularly polarized light is implemented as left-handed circularly polarized light, the second circularly polarized light is implemented as right-handed circularly polarized light; vice versa, and the present application will not elaborate further on this.

[0047] More specifically, as Figures 2 to 6As shown in the figure, the polarization multiplexing light homogenizing device 30 may include a light-transmitting substrate 31, a metalens layer 32, a phase delay array layer 33, and a CLC array layer 34. The light-transmitting substrate 31 has a light-incident surface 311 and a light-emitting surface 312 arranged opposite to each other. The metalens layer 32 includes a plurality of nanocolumns periodically arranged on the light-incident surface 311 to form a plurality of metalens units 320 arranged in a two-dimensional array, wherein each metalens unit 320 is configured to converge the first circularly polarized light and the second circularly polarized light with opposite rotation directions to different focal points respectively. The phase delay array layer 33 includes a plurality of phase delay units 330 arranged in a one-dimensional array on the light-emitting surface 312, wherein each phase delay unit 330 corresponds to a row of metalens units 320, and each phase delay unit 330 includes a first phase delay element 331 and a second phase delay element 332 with fast axes perpendicular to each other. The first phase delay element 331 and the second phase delay element 332 are respectively configured to modulate the phases of the first circularly polarized light and the second circularly polarized light to emit linearly polarized light with the same polarization state. The CLC array layer 34 includes a plurality of CLC prisms 340 in one-to-one correspondence with the phase delay units 330. The plurality of CLC prisms 340 are arranged in a one-dimensional array on a side of the metalens layer 32 away from the phase delay array layer 33, and each CLC prism 340 includes a first prism 341, a second prism 342, and a cholesteric liquid crystal film 343 disposed between the first prism 341 and the second prism 342, and is configured to transmit the first circularly polarized light and reflect the second circularly polarized light.

[0048] In this way: on the one hand, as Figure 3 shown, the first circularly polarized light in the unpolarized light emitted by the light source assembly 10 will directly pass through the CLC array layer 34 to propagate to the metalens layer 32, and then be converged by the metalens unit 320 in the metalens layer 32 to the first phase delay element 331 of the phase delay unit 330 in the phase delay array layer 33, so as to be modulated by the first phase delay element 331 into a certain linearly polarized light (such as P-polarized light or S-polarized light) to irradiate the polarization display assembly 20; on the other hand, as Figure 3 shown, the second circularly polarized light in the unpolarized light emitted by the light source assembly 10 is first reflected by the cholesteric liquid crystal film 343 of a CLC prism 340 in the CLC array layer 34 to propagate to another adjacent CLC prism 340, and then be reflected by the cholesteric liquid crystal film 343 of the other CLC prism 340 to propagate to the metalens layer 32, and then be converged by the metalens unit 320 in the metalens layer 32 to the second phase delay element 332 of the phase delay unit 330 in the phase delay array layer 33, so as to be modulated by the second phase delay element 332 into linearly polarized light with the same polarization state (such as P-polarized light or S-polarized light) to irradiate the polarization display assembly 20, thereby effectively converting the unpolarized light into polarized light with the same polarization state.

[0049] It should be noted that, compared with the existing polarization multiplexing device + compound eye lens array solution, the polarization multiplexing light homogenizing device 30 of the present application not only does not require an additional compound eye lens array, but the integrated metalens layer 32 plays a role in light homogenization when converging the first circularly polarized light and the second circularly polarized light respectively; moreover, it does not need to be aligned and installed in the actual optical path assembly, which is beneficial to improving the optical efficiency of the system. In other words, the polarization multiplexing light homogenizing device 30 of the present application adopts a planar design, integrating the polarization multiplexing function and the light homogenizing function in one device, without the need for alignment and installation during assembly and adjustment, and completely solving the problem of reduced optical efficiency caused by installation errors.

[0050] In addition, as Figure 2 and Figure 5 shown, since the first phase retardation element 331 and the second phase retardation element 332 of the phase retardation array layer 33 in the polarization multiplexing light homogenizing device 30 of the present application are continuously and alternately distributed, rather than being spaced apart like the half-wave plates in the existing polarization multiplexing devices, the assembly difficulty of the polarization multiplexing light homogenizing device 30 of the present application is greatly reduced, which is beneficial to ensuring that the CLC prism 340, the metalens unit 320, and the phase retardation unit 330 are aligned with each other in sequence, facilitating the improvement of the output purity of linearly polarized light.

[0051] It can be understood that the CLC mentioned in the present application refers to cholesteric liquid crystal (English: Cholesteric liquid crystal), which, as a material with strong polarization selectivity, totally reflects circularly polarized light of a certain specific handedness (i.e., the second circularly polarized light) at an angle that satisfies Bragg's law, and can totally transmit / pass through circularly polarized light of the other handedness (i.e., the first circularly polarized light). In addition, the optical properties of cholesteric liquid crystal are determined by the alignment layer, and based on specific alignment layer design and exposure, it can have a focal power similar to that of a lens and is a planar optical element.

[0052] Optionally, as Figure 5 shown, both the first phase retardation element 331 and the second phase retardation element 332 are implemented as quarter-wave plates (English: Quarter-Wave Plate, abbreviated as QWP), and the fast axis direction of the quarter-wave plate forms an angle of ±45° with the array arrangement direction of the phase retardation unit 330. For example, when the angle between the fast axis direction of the first phase retardation element 331 and the array arrangement direction of the phase retardation array layer 33 is +45°, the angle between the fast axis direction of the second phase retardation element 332 and the array arrangement direction of the phase retardation array layer 33 is -45°.

[0053] It should be noted that, as Figure 2 and Figure 4As shown, the period of the nanocolumns of the metalens unit 320 in the metalens layer 32 is equal to the size (i.e., height) of the CLC prism 340 and / or the phase retardation unit 330 in the array arrangement direction, so as to ensure that each CLC prism 340 and / or phase retardation unit 330 can be aligned with a row of metalens units 320.

[0054] In addition, the phase retardation array layer 33 is located at the focal plane of the metalens layer 32, so that the first circularly polarized light and the second circularly polarized light can be better focused on the first phase retardation element 331 and the second phase retardation element 332 respectively through the metalens layer 32, which is beneficial to improving the purity of the emitted linearly polarized light.

[0055] Exemplarily, in the first example of the present application, as Figure 2 and Figure 3 shown, both the first prism 341 and the second prism 342 are implemented as right-angled prisms, that is, they have a right-angled triangle cross-section; wherein the cholesteric liquid crystal film 343 is located between the inclined surfaces of the first prism 341 and the second prism 342 to form the CLC prism 340 with a rectangular cross-section. In this way, one right-angled surface of the first prism 341 serves as the incident surface of the CLC prism 340, one right-angled surface of the second prism 342 serves as the exit surface of the CLC prism 340, and the other right-angled surface of the first prism 341 is attached face-to-face with the other right-angled surface of the adjacent second prism 342, so that the CLC prism 340 is longitudinally arranged end-to-end in a row.

[0056] Set as follows: as Figure 3 shown, first, the unpolarized light emitted by the light source assembly 10 enters the CLC prism 340 from one right-angled surface of the first prism 341 and propagates to the cholesteric liquid crystal film 343; then, the first circularly polarized light in the unpolarized light directly passes through the cholesteric liquid crystal film 343 and exits from one right-angled surface of the second prism 342; at the same time, the second circularly polarized light in the unpolarized light is first reflected by the cholesteric liquid crystal film 343 and exits from the other right-angled surface of the first prism 341, enters the other right-angled surface of the second prism 342 in the adjacent CLC prism 340 and propagates to the corresponding cholesteric liquid crystal film 343, and is then reflected by the corresponding cholesteric liquid crystal film 343 and exits from one right-angled surface of the corresponding second prism 342; finally, the first circularly polarized light and the second circularly polarized light emitted from the CLC prism 340 are respectively focused on the first phase retardation element 331 and the second phase retardation element 332 of the phase retardation array layer 33 through the metalens units 320 of the metalens layer 32, so as to be modulated into linearly polarized light with the same polarization state, achieving the effects of polarization multiplexing and light homogenization.

[0057] Optionally, as Figure 3As shown, the cross-sections of the first prism 341 and the second prism 342 are both implemented as isosceles right triangles, so that the cholesteric liquid crystal film 343 forms an angle of 45° with the array direction of the CLC prism 340. It can be understood that in other examples of the present application, the angle between the cholesteric liquid crystal film 343 and the array direction of the CLC prism 340 can be between 40° and 50°, as long as the angle of the second circularly polarized light incident on the cholesteric liquid crystal film 343 satisfies the Bragg's law and can be fully reflected. This application will not elaborate further on this.

[0058] It should be noted that in the second example of the present application, as Figure 6 shown, in the CLC array layer 34, the first prism 341 of any CLC prism 340 is integrally connected to the second prism 342 of the adjacent CLC prism 340, so that the adjacent first prism 341 and second prism 342 together form a common prism 3400 with a parallelogram cross-section, and each cholesteric liquid crystal film 343 is pasted between the inclined surfaces of two adjacent common prisms 3400; that is to say, the first prism 341 is a part of the common prism 3400, and the second prism 342 is another part of the common prism 3400, so as to eliminate the bonding interface between the first prism 341 and the second prism 342 and completely avoid stray light caused by interface reflection. In this way, when manufacturing the CLC array layer 34, it is not necessary to additionally bond the adjacent first prism 341 and second prism 342 together, which helps to simplify the manufacturing process of the polarization multiplexing light homogenizing device 30.

[0059] According to the above embodiments of the present application, as Figure 1 shown, the polarization display component 20 in the micro-projection light engine 1 may include a relay unit 21, a display unit 22, and an imaging unit 23. The relay unit 21 is disposed between the polarization multiplexing light homogenizing device 30, the display unit 22, and the imaging unit 23, and is used to first relay and transmit the linearly polarized light from the polarization multiplexing light homogenizing device 30 to the display unit 22 to be modulated into image light, and then relay and transmit the image light from the display unit 22 to the imaging unit 23 for projection imaging. It can be understood that the image light mentioned in this application refers to polarized light carrying image information.

[0060] Exemplarily, as Figure 1As shown, the display unit 22 can be implemented as an LCOS display device 220 for modulating linearly polarized light into image light and reflecting the image light. The imaging unit 23 can be implemented as an imaging lens group 230 for projecting the image light to form an image. The relay unit 21 can include a polarization beam splitting device 211 and a polarization folding device 212. The polarization beam splitting device 211 is located on the light-emitting side of the polarization multiplexing light homogenizing device 30. The polarization folding device 212 and the LCOS display device 220 are respectively located on opposite sides of the polarization beam splitting device 211. The imaging lens group 230 is located on the side of the polarization beam splitting device 211 away from the polarization multiplexing light homogenizing device 30. In this way, the linearly polarized light with the first polarization state from the polarization multiplexing light homogenizing device 30 is first reflected by the polarization beam splitting device 211 to propagate to the polarization folding device 212, and then the polarization direction is changed by the polarization folding device 212 to form linearly polarized light with the second polarization state and then folded back to the polarization beam splitting device 211. Then, the linearly polarized light with the second polarization state first passes through the polarization beam splitting device 211 to propagate to the LCOS display device 220, and then is modulated by the LCOS display device 220 into image light with the first polarization state and reflected back to the polarization beam splitting device 211. Finally, the image light with the first polarization state is first reflected by the polarization beam splitting device 211 to propagate to the imaging lens group 230, and then is modulated by the imaging lens group 230 to project and form an image.

[0061] Optionally, as Figure 1 shown, the relay unit 21 further includes a relay lens group 213 located between the polarization multiplexing light homogenizing device 30 and the polarization beam splitting device 211, so that the linearly polarized light from the polarization multiplexing light homogenizing device 30 is modulated and shaped by passing through the relay lens group 213 before entering the polarization beam splitting device 211, facilitating the irradiation requirements of the LCOS display device 220.

[0062] It should be noted that the polarization beam splitting device 211 can be but is not limited to being implemented as a PBS prism. The polarization folding device 212 can be but is not limited to being implemented as an optical device composed of a curved mirror and a quarter-wave plate located between the curved mirror and the PBS prism.

[0063] In addition, in the above embodiments of the present application, as Figure 1 shown, the polarization multiplexing light homogenizing device 30 and the imaging unit 23 are respectively located on opposite sides of the polarization beam splitting device 211. The display unit 22 and the polarization folding device 212 are respectively located on the other two sides of the polarization beam splitting device 211. In this way, the propagation direction of the image light emitted from the polarization beam splitting device 211 is the same as the propagation direction of the linearly polarized light entering the polarization beam splitting device 211, so that the micro-projection light engine 1 has a linear structure, in order to reduce the overall height of the light engine.

[0064] Of course, in a variant embodiment of the present application, as Figure 7 shown, the polarization multiplexing light homogenizing device 30 and the polarization folding device 212 are respectively located on opposite sides of the polarization beam splitting device 211; the display unit 22 and the imaging unit 23 are respectively located on the other two sides of the polarization beam splitting device 211, so that the propagation direction of the image light emitted from the polarization beam splitting device 211 is perpendicular to the propagation direction of the linearly polarized light incident on the polarization beam splitting device 211, making the micro-projection light engine 1 have a folded structure to reduce the overall length of the light engine.

[0065] It is worth mentioning that, according to another aspect of the present application, as Figure 8 shown, an embodiment of the present application further provides a polarization multiplexing light homogenizing method, including the steps of:

[0066] S100: Passing the first circularly polarized light in the unpolarized light through a CLC prism in the CLC array layer to propagate to the meta-lens unit corresponding to the CLC prism in the meta-lens layer, and reflecting the second circularly polarized light in the unpolarized light with a rotation direction opposite to that of the first circularly polarized light to propagate to another CLC prism in the CLC array layer and be reflected to the meta-lens unit corresponding to the other CLC prism in the meta-lens layer;

[0067] S200: Converging the first circularly polarized light through the meta-lens unit corresponding to the CLC prism in the meta-lens layer onto the first phase retarder of the phase retardation unit corresponding to the CLC prism in the phase retardation array layer to be converted into linearly polarized light with a first polarization state; and

[0068] S300: Converging the second circularly polarized light through the meta-lens unit corresponding to the other CLC prism in the meta-lens layer onto the second phase retarder of the phase retardation unit corresponding to the other CLC prism in the phase retardation array layer to be converted into linearly polarized light with the first polarization state.

[0069] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0070] The above embodiments only represent several implementation manners of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention.

Claims

1. Polarization multiplexing light homogenizing device, characterized in that, Comprising: A light-transmitting substrate having an incident light surface and an emergent light surface arranged opposite to each other; A metasurface layer including a plurality of nanocolumns periodically arranged on the incident light surface to form a plurality of metasurface units arranged in a two-dimensional array, wherein each of the metasurface units is configured to converge the first circularly polarized light and the second circularly polarized light with opposite handedness to different focal points respectively; A phase retardation array layer including a plurality of phase retardation units arranged in a one-dimensional array on the emergent light surface, wherein each of the phase retardation units corresponds to a row of the metasurface units, and each of the phase retardation units includes a first phase retarder and a second phase retarder with fast axes perpendicular to each other, and the first phase retarder and the second phase retarder are respectively configured to modulate the phases of the first circularly polarized light and the second circularly polarized light correspondingly to emit linearly polarized light with the same polarization state; And A CLC array layer including a plurality of CLC prisms corresponding to the phase retardation units one by one, wherein the plurality of CLC prisms are arranged in a one-dimensional array on a side of the metasurface layer away from the phase retardation array layer, and each of the CLC prisms includes a first prism, a second prism, and a cholesteric liquid crystal film disposed between the first prism and the second prism, and is configured to transmit the first circularly polarized light and reflect the second circularly polarized light.

2. The polarization multiplexing light homogenizing device according to claim 1, wherein Both the first phase retarder and the second phase retarder are quarter-wave plates, and the fast axis directions of the quarter-wave plates form an angle of ±45° with the array arrangement direction of the phase retardation units.

3. The polarization multiplexing light homogenizing device according to claim 1, characterized in that The period of the nanocolumns of the metasurface units in the metasurface layer is equal to the size of the CLC prisms and / or the phase retardation units in the array arrangement direction.

4. The polarization multiplexing light homogenizing device according to claim 1, wherein The phase retardation array layer is located at the focal plane of the metasurface layer.

5. The polarization multiplexing light homogenizing device according to any one of claims 1 to 4, characterized in that Both the first prism and the second prism are right-angled prisms; the cholesteric liquid crystal film is located between the inclined surfaces of the first prism and the second prism.

6. The polarization multiplexing light homogenizing device according to claim 5, wherein Both the first prism and the second prism are isosceles right-angled prisms.

7. The polarization multiplexing light homogenizing device according to any one of claims 1 to 4, characterized in that, The first prism in the CLC prism is integrally connected to the second prism in the adjacent CLC prism, so that the adjacent first prism and second prism jointly form a common prism with a parallelogram cross-section.

8. The micro-projection optical engine is characterized in that, Comprising: A light source assembly configured to emit unpolarized light; A polarization display assembly located on the light-emitting side of the light source assembly; And A polarization multiplexing light homogenizing device according to any one of claims 1 to 7, disposed in the optical path between the light source assembly and the polarization display assembly, and configured to convert the unpolarized light from the light source assembly into linearly polarized light with the same polarization state to irradiate the polarization display assembly.

9. The micro-projection optical engine according to claim 8, wherein, The polarization display assembly includes a relay unit, a display unit, and an imaging unit. The relay unit is disposed between the polarization multiplexing light homogenizing device, the display unit, and the imaging unit, and is configured to first relay and transmit the linearly polarized light from the polarization multiplexing light homogenizing device to the display unit to be modulated into image light, and then relay and transmit the image light from the display unit to the imaging unit to project an image.

10. The micro-projection optical engine according to claim 9, characterized in that The display unit is an LCOS display device; the imaging unit is an imaging lens group; the relay unit includes a polarization beam splitting device and a polarization folding device. The polarization beam splitting device is located on the light output side of the polarization multiplexing light homogenizing device. The polarization folding device and the LCOS display device are respectively located on opposite sides of the polarization beam splitting device. The imaging lens group is located on the side of the polarization beam splitting device away from the polarization multiplexing light homogenizing device.

11. The micro-projection optical engine according to claim 9, characterized in that, The display unit is an LCOS display device; the imaging unit is an imaging lens group; the relay unit includes a polarization beam splitting device and a polarization folding device. The polarization beam splitting device is located on the light output side of the polarization multiplexing light homogenizing device. The imaging lens group and the LCOS display device are respectively located on opposite sides of the polarization beam splitting device. The polarization folding device is located on the side of the polarization beam splitting device away from the polarization multiplexing light homogenizing device.

12. Polarization multiplexing light homogenization method, characterized in that, Including the steps of: Transmitting the first circularly polarized light in the unpolarized light through a CLC prism in the CLC array layer to propagate to the metasurface unit corresponding to the CLC prism in the metasurface layer, and reflecting the second circularly polarized light in the unpolarized light with a rotation direction opposite to that of the first circularly polarized light to propagate to another CLC prism in the CLC array layer and be reflected to the metasurface unit corresponding to the other CLC prism in the metasurface layer; Converging the first circularly polarized light through the metasurface unit corresponding to the CLC prism in the metasurface layer onto the first phase retarder of the phase retardation unit corresponding to the CLC prism in the phase retardation array layer to be converted into linearly polarized light with a first polarization state; and Converging the second circularly polarized light through the metasurface unit corresponding to the other CLC prism in the metasurface layer onto the second phase retarder of the phase retardation unit corresponding to the other CLC prism in the phase retardation array layer to be converted into linearly polarized light with the first polarization state.

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