Projection display device, optical system and manufacturing method thereof

Abstract

The application provides a projection display device, an optical system and a manufacturing method thereof. The projection display device comprises a polarization splitting element, at least one image generating element and an optical compensation element. The polarization splitting element is configured to polarize an incident light beam into at least two different directions of outgoing light beams. The image generating element is located on the propagation path of the at least one outgoing light beam and is configured to modulate the outgoing light beam into information light based on image information. The optical compensation element is located between the polarization splitting element and the image generating element and allows at least part of the outgoing light beam and the information light to pass through. In this way, by arranging the optical compensation element allowing at least part of the outgoing light beam and the information light to pass through, multi-screen display under different projection distances can be achieved, the structure is simple, and the cost is low. Moreover, by arranging the optical compensation element, the dark state stray light can be reduced, thereby improving the overall contrast of the bright and dark areas of the projection display device.

Description

Technical Field

[0001] This application relates to the field of display technology, and more specifically, to a projection display device, an optical system, and a method for manufacturing the same. Background Technology

[0002] With the development of 3D display technology, its application in the automotive field is becoming more and more widespread, such as in-vehicle head-up displays (HUDs).

[0003] Currently, Liquid Crystal On Silicon (LCOS) technology boasts advantages such as high light utilization, smooth pixel distribution, and natural image quality, and is commonly used in AR HUDs. LCOS offers better imaging performance than Liquid Crystal Display (LCD) technology and can break the technological monopoly of DMD chips in Digital Light Processing (DLP) solutions, achieving technological self-reliance and control. However, it also has the following problems:

[0004] 1. Currently, achieving the effect of multi-screen images at different projection distances in vehicle HUDs requires a complex multi-system structure, which is bulky and costly.

[0005] 2. In the dark state of LCOS, the S-light incident on the LCOS chip does not change its polarization state after being modulated by LCOS and remains S-polarized light, but a phase shift occurs, resulting in an impure polarization state of the S-light. Some of the light will pass through the PBS prism and enter the image plane to form dark stray light.

[0006] 3. Due to stray light, the overall contrast of the machine is relatively low. Summary of the Invention

[0007] This application provides a projection display device, an optical system, and a method for manufacturing the same, which can at least partially solve the aforementioned problems existing in the related art.

[0008] This application provides a projection display device, including a polarization beam splitter, at least one image generating element, and an optical compensation element. The polarization beam splitter is configured to polarize an incident light beam incident upon it into at least two outgoing light beams in at least two different directions. The image generating element is located in the propagation path of at least one outgoing light beam and is configured to modulate the outgoing light beam into information light based on image information. The optical compensation element is located between the polarization beam splitter and the image generating element, allowing at least a portion of the outgoing light beam and the information light to pass through.

[0009] In some implementations, the projection of the optical compensation element in the direction of the emitted beam at least covers a portion of the image generating element.

[0010] In some implementations, the projection of the optical compensation element onto the direction of the emitted beam does not exceed half that of the image generating element.

[0011] In some implementations, the thickness of the optical compensation element is less than or equal to 2 mm.

[0012] In some implementations, the optical compensation element has multiple different thickness dimensions in the direction of the emitted beam.

[0013] In some embodiments, the side of the optical compensation element facing the polarization beam splitter is a stepped surface, and the side of the optical compensation element facing the image generating element is a plane.

[0014] In some implementations, the maximum thickness of the optical compensation element is less than or equal to 2 mm.

[0015] In some embodiments, the wavelength of the optical compensation element is greater than or equal to 400 nm and less than or equal to 700 nm; and the refractive index of the optical compensation element is greater than or equal to 1.4 and less than or equal to 1.8.

[0016] In some implementations, the fast axis rotation angle of the optical compensation element is greater than or equal to -20° and less than or equal to 20°.

[0017] In some implementations, the image generating element is a reflective liquid crystal display chip.

[0018] In some embodiments, the projection display device further includes a light source assembly disposed in the incident light path of the polarizing beam splitter and forming an incident beam.

[0019] In some implementations, the light source component is an LD light source system or an LED light source system.

[0020] Another aspect of this application provides an optical system including the projection display device as described above and an imaging lens, wherein the imaging lens is configured to project information light carrying image information output by the projection display device onto at least two imaging surfaces.

[0021] In some implementations, the distance between at least two imaging planes is greater than or equal to 20 mm and less than or equal to 50 mm.

[0022] In some implementations, the ratio between the focal length of the imaging lens and the thickness of the optical compensation element is greater than or equal to 10 and less than or equal to 100.

[0023] In some implementations, the ratio between the lens length of the imaging lens and the focal length of the imaging lens is less than or equal to 4.9.

[0024] In some implementations, the ratio between the optical back focal length of the imaging lens and the lens length of the imaging lens is greater than or equal to 0.3.

[0025] This application, in another aspect, provides a method for manufacturing an optical system, comprising: placing a polarizing beam splitter in the propagation direction of an incident beam, the polarizing beam splitter being configured to polarize the incident beam into at least two outgoing beams in different directions; placing at least one image generating element in the propagation path of the outgoing beam, the image generating element being configured to modulate the outgoing beam into information light based on image information; placing an optical compensation element between the polarizing beam splitter and the image generating element, the optical compensation element being configured to allow at least a portion of the outgoing beam and the information light to pass through; and placing an imaging lens in the propagation direction of the information light, the imaging lens being configured to project the information light onto at least two imaging surfaces.

[0026] In some embodiments, the optical compensation element is disposed between the polarization beam splitter and the image generating element, including: the optical compensation element, whose projection in the direction of the outgoing beam at least covers a portion of the image generating element, is disposed between the polarization beam splitter and the image generating element.

[0027] In some implementations, the projection of the optical compensation element onto the direction of the emitted beam does not exceed half that of the image generating element.

[0028] In some implementations, the thickness of the optical compensation element is less than or equal to 2 mm.

[0029] In some embodiments, the optical compensation element is disposed between the polarization beam splitter and the image generation element, including: disposing optical compensation elements having multiple different thicknesses in the direction of the emitted beam between the polarization beam splitter and the image generation element.

[0030] In some embodiments, the side of the optical compensation element facing the polarization beam splitter is configured as a stepped surface; and the side of the optical compensation element facing the image generating element is configured as a plane.

[0031] In some implementations, the maximum thickness of the optical compensation element is less than or equal to 2 mm.

[0032] In some embodiments, the wavelength of the optical compensation element is greater than or equal to 400 nm and less than or equal to 700 nm; and the refractive index of the optical compensation element is greater than or equal to 1.4 and less than or equal to 1.8.

[0033] In some implementations, the fast axis rotation angle of the optical compensation element is greater than or equal to -20° and less than or equal to 20°.

[0034] In some implementations, the image generating element is a reflective liquid crystal display chip.

[0035] In some embodiments, the manufacturing method further includes: placing a light source assembly in the incident light path of the polarizing beam splitter, the light source assembly being configured to emit an incident light beam.

[0036] In some embodiments, placing the light source assembly in the incident light path of the polarization beam splitter includes placing an LD light source system or an LED light source system in the incident light path of the polarization beam splitter.

[0037] In some implementations, the distance between at least two imaging planes is greater than or equal to 20 mm and less than or equal to 50 mm.

[0038] In some implementations, the ratio between the focal length of the imaging lens and the thickness of the optical compensation element is greater than or equal to 10 and less than or equal to 100.

[0039] In some implementations, the ratio between the lens length of the imaging lens and the focal length of the imaging lens is less than or equal to 4.9.

[0040] In some implementations, the ratio between the optical back focal length of the imaging lens and the lens length of the imaging lens is greater than or equal to 0.3.

[0041] In at least one embodiment of the projection display device provided in this application, by providing an optical compensation element that allows at least a portion of the emitted light beam and information light to pass through, multi-screen display at different projection distances can be achieved. This method is simple in structure and low in cost. Furthermore, by providing the optical compensation element, stray light in dark states can be reduced, thereby improving the overall contrast ratio of the bright and dark areas of the projection display device. Attached Figure Description

[0042] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings. Wherein:

[0043] Figure 1 This is a schematic diagram of the structure of the optical system 100 according to the first embodiment of this application;

[0044] Figure 2 This is a schematic diagram of the structure of the optical system 200 according to the second embodiment of this application;

[0045] Figure 3 This is a schematic diagram of the structure of the optical system 300 according to the third embodiment of this application; and

[0046] Figure 4 This is a schematic flowchart of a method for manufacturing an optical system according to an embodiment of this application. Detailed Implementation

[0047] To better understand this application, various aspects of this application will be described in more detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely illustrative of exemplary embodiments of this application and are not intended to limit the scope of this application in any way. Throughout the specification, the same reference numerals refer to the same elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0048] It should be noted that in this specification, the terms "first," "second," "third," etc., are used only to distinguish one feature from another and do not imply any limitation on the features, especially not any order of precedence. Therefore, without departing from the teachings of this application, the first part discussed herein may also be referred to as the second part, and vice versa.

[0049] In the accompanying drawings, the thickness, dimensions, and shapes of the parts have been slightly adjusted for ease of illustration. The drawings are for illustrative purposes only and are not drawn to scale. As used herein, the terms “approximately,” “about,” and similar terms are used as expressions of approximation, not as expressions of degree, and are intended to illustrate inherent deviations in measured or calculated values ​​that will be recognized by one of ordinary skill in the art.

[0050] It should also be understood that expressions such as "comprising," "including," "having," "containing," and / or "comprising" are open-ended rather than closed-ended expressions in this specification, indicating the presence of the stated features, elements, and / or components, but not excluding the presence of one or more other features, elements, components, and / or combinations thereof. Furthermore, when describing embodiments of this application, the word "may" is used to mean "one or more embodiments of this application." And the term "exemplary" is intended to refer to examples or illustrations.

[0051] Unless otherwise specified, all terms used herein (including engineering and technical terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should also be understood that, unless expressly stated herein, terms defined in common dictionaries shall be interpreted as having the meaning consistent with their meaning in the context of the relevant art, and not as having an idealized or overly formalized meaning.

[0052] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. Furthermore, unless explicitly limited or contradicted by the context, the specific steps included in the methods described in this application are not limited to the order in which they are described, but can be performed in any order or in parallel. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0053] This application provides a projection display device, including a polarizing beam splitter, at least one image generating element, and an optical compensation element. The polarizing beam splitter is configured to polarize an incident light beam into at least two outgoing beams in different directions. The image generating element is located in the propagation path of at least one outgoing beam and is configured to modulate the outgoing beam into information light based on image information. The optical compensation element is located between the polarizing beam splitter and the image generating element, allowing at least a portion of the outgoing beam and information light to pass through. In this way, by providing an optical compensation element that allows at least a portion of the outgoing beam and information light to pass through, multi-screen display at different projection distances can be achieved, resulting in a simple structure and low cost. Furthermore, by providing the optical compensation element, stray light in dark states can be reduced, thereby improving the overall contrast ratio of the bright and dark areas of the projection display device.

[0054] Figure 1 A schematic diagram of the structure of an optical system 100 according to the first embodiment of this application is shown.

[0055] like Figure 1 As shown, the optical system 100 includes a projection display device 110 and an imaging lens 150. The projection display device 110 includes a polarization beam splitter 111, an image generating element 112, and an optical compensation element 113. The imaging lens 150 is configured to project light carrying the image information output from the projection display device 110 onto at least two imaging surfaces.

[0056] In some embodiments, the polarization beam splitter 111 is configured to polarize an incident beam incident on it into at least two outgoing beams in at least two different directions. Exemplarily, the polarization beam splitter 111 is a PBS prism. An image generating element 112 is located in the propagation path of at least one outgoing beam and is configured to modulate the outgoing beam into information light based on image information. An optical compensation element 113 is located between the polarization beam splitter 111 and the image generating element 112, and the projection of the optical compensation element 113 in the direction of the outgoing beam partially covers the image generating element 112, as shown in the reference. Figure 1 As shown.

[0057] Detailed, such as Figure 1 As shown, the incident beam incident on the polarization beam splitter 111 includes P-polarized light and S-polarized light. The P-polarized light comprises mostly P-rays and a small amount of stray light, while the S-polarized light comprises mostly S-rays and a small amount of stray light. The polarization beam splitter 111 has the characteristic of transmitting P-polarized light while reflecting S-polarized light. Therefore, when both P-polarized and S-polarized light are incident on the polarization beam splitter 111 simultaneously, the S-polarized light is reflected by the polarization beam splitter 111 to form the S-polarized outgoing beam.

[0058] The first portion of the S-polarized light emitted passes through the optical compensation element 113 and then enters the image generating element 112. The optical compensation element 113 can improve the purity of this portion of S-polarized light, reduce stray light, and does not affect the polarization state of the P-polarized light. Optionally, the image generating element 112 is a reflective image generating element 112. When the image generating element 112 is in a bright state, the first portion of S-polarized light can be modulated into P-polarized light and reflected. The reflected first portion of P-polarized light passes through the optical compensation element 113 and then enters the polarization beam splitter 111. Since the optical compensation element 113 does not affect the polarization state of the P-polarized light, and the polarization beam splitter 111 has the characteristic of transmitting P-polarized light, the first portion of P-polarized light passes through the polarization beam splitter 111 and is transmitted into the imaging lens 150 and projected onto the first imaging surface 151.

[0059] The S-polarized light beam emitted from the second part does not pass through the optical compensation element 113, but directly enters the image generating element 112. The image generating element 112 modulates the S-polarized light of the second part into P-polarized light and reflects it. The reflected P-polarized light of the second part passes through the polarization beam splitter 111 and is transmitted into the imaging lens 150 and projected onto the second imaging surface 152.

[0060] In the above scheme, since only a portion of the S-polarized light emitted passes through the optical compensation element 113, the optical compensation element 113 only reduces stray light in this portion of the S-polarized light. Moreover, the material of the optical compensation element 113 has a corresponding refractive index, so the P-polarized light carrying image information reflected by the image generating element 112 can be displayed on the first imaging surface 151 and the second imaging surface 152 at different positions, forming a dual-screen system with a simple structure and low cost.

[0061] Furthermore, when the image generating element 112 is in a dark state, the S-polarized light incident on the image generating element 112 does not change its polarization state. The light modulated by the image generating element 112 is still S-polarized light, but the angle has been deflected. If some of the light directly enters the imaging surface, it will form dark stray light. The optical compensation element 113 of this application can shift the phase of the modulated S-polarized light in the dark state to suppress the angular deviation of the polarization axis caused by the direction of the S-polarized light illuminating the polarization beam splitter 111. This can effectively improve the polarization state purity of the S-polarized light in the dark state, so that it can be reflected as much as possible when passing through the polarization beam splitter 111, avoiding some light from being transmitted to the imaging lens 150 to form dark stray light, thereby improving the overall contrast of the optical system 100.

[0062] In some embodiments, the fast axis rotation angle θ of the optical compensation element 113 can be adjusted by rotating the optical compensation element 113. For example, the fast axis rotation angle θ of the optical compensation element 113 can be adjusted between -20° and 20° to find the lowest value in the dark state, at which point the purity of the dark-state S-polarized light is the highest, which can suppress the phase shift of the S-polarized light modulated by the image generating element 112 in the dark state.

[0063] For example, the wavelength range of the optical compensation element 113 is 400nm-700nm, and the refractive index n of the optical compensation element 113 is greater than or equal to 1.4 and less than or equal to 1.8. When fabricating the optical compensation element 113, multiple waveplates can be stacked with their optical axes intersecting each other at an angle to achieve different phase delay effects.

[0064] Furthermore, the P-polarized light in the incident light passes through the polarization beam splitter 111 along the incident direction. Optionally, another image generating element (not shown) may also be provided in the outgoing light path of the P-polarized light.

[0065] In some embodiments, the projection of the optical compensation element 113 in the direction of the emitted beam approximately covers half of the image generating element 112.

[0066] In some embodiments, the thickness of the optical compensation element 113 is less than or equal to 2 mm, which can reduce the difficulty of assembling and adjusting the optical compensation element 113. For example, if the thickness of the optical compensation element 113 is too thick, it will cause the back focal length of the imaging lens 150 to increase, and the imaging lens 150 will be under greater pressure.

[0067] In some embodiments, the distance between the first imaging surface 151 and the second imaging surface 152 satisfies the following relationship:

[0068]

[0069] Where ΔL is the distance between the first imaging surface 151 and the second imaging surface 152, ΔL = L2 - L1, L2 is the distance between the first imaging surface 151 and the imaging lens 150, and L1 is the distance between the second imaging surface 152 and the imaging lens 150. L1 can also be understood as the distance between the imaging surface closer to the imaging lens 150 and the imaging lens 150, and L2 can also be understood as the distance between the imaging surface farther from the imaging lens 150 and the imaging lens 150 (refer to...). Figure 1 ), d is the thickness of the optical compensation element 113, n is the refractive index of the optical compensation element 113, and f' is the focal length of the imaging lens 150.

[0070] In some embodiments, the ratio between the focal length f' of the imaging lens 150 and the thickness d of the optical compensation element 113 is greater than or equal to 10 and less than or equal to 100. Optionally, the imaging lens 150 is a combination of multiple lenses, and the focal length f' of the imaging lens 150 is the focal length of the entire set.

[0071] For example, the range of ΔL is approximately greater than or equal to 20 mm and less than or equal to 50 mm.

[0072] In the above solution, controlling the distance between the imaging surfaces and the thickness of the optical compensation element 113 can ensure the overall size of the device while making full use of the optical compensation element 113. Moreover, when the optical system 100 of this application is applied to an automotive HUD, controlling the overall size of the HUD can simultaneously ensure the comfort of the human eye.

[0073] In some embodiments, the ratio between the lens length TL of the imaging lens 150 and the focal length f' of the imaging lens 150 is less than or equal to 4.9.

[0074] It is understandable that when the imaging lens 150 is a combination of multiple lenses, the lens length TL of the imaging lens 150 is the distance from the center of the front face of the first lens to the center of the rear face of the last lens.

[0075] In the above scheme, the lens group is short and the structure is compact, which is conducive to the miniaturization of the imaging lens 150, reduces lens sensitivity, improves production yield, and reduces production costs.

[0076] In some embodiments, the ratio between the optical back focal length (BFL) of the imaging lens 150 and the lens length (TL) of the imaging lens 150 is greater than or equal to 0.3.

[0077] The optical back focal length (BFL) of the imaging lens 150 mentioned above is the distance from the rear end face of the last lens of the imaging lens 150 to the imaging surface.

[0078] The above solution can achieve miniaturization while maintaining a long back focal length, which is beneficial for the assembly of lighting elements such as prisms.

[0079] In some embodiments, the image generating element 112 is a reflective liquid crystal display chip (LCOS chip). The LCOS chip has a high resolution, so that the clarity is not affected even when a dual-screen system is formed as described above.

[0080] In some embodiments, the projection display device 110 further includes a light source assembly 114, which is disposed in the incident light path of the polarizing beam splitter 111 and forms an incident beam.

[0081] In some embodiments, the light source assembly 114 is an LD light source 1141 system. Optionally, the LD light source 1141 system includes an LD light source 1141, a beam expander system 1142, a compound eye 1143, and a relay system 1144. The beam emitted by the LD light source 1141 needs to be expanded by the beam expander system 1142, homogenized by the compound eye 1143, and then passed through the relay system 1144 to form an incident beam (P-polarized light and S-polarized light) which is then incident on the polarization beam splitter 111.

[0082] Figure 2 A schematic diagram of the structure of an optical system 200 according to a second embodiment of this application is shown.

[0083] like Figure 2 As shown, the optical system 200 includes a projection display device 210 and an imaging lens 250. The projection display device 210 includes a polarization beam splitter 211, an image generating element 212, and an optical compensation element 213. The imaging lens 250 is configured to project light carrying the image information output from the projection display device 210 onto at least two imaging surfaces (a first imaging surface 251 and a second imaging surface 252).

[0084] In some embodiments, the polarization beam splitter 211 is configured to polarize an incident beam incident on it into at least two outgoing beams in at least two different directions. An image generating element 212 is located in the propagation path of at least one outgoing beam and is configured to modulate the outgoing beam into information light based on image information. An optical compensation element 213 is located between the polarization beam splitter 211 and the image generating element 212, and the projection of the optical compensation element 213 onto the direction of the outgoing beam at least partially covers the image generating element 212.

[0085] and Figure 1 Unlike the first embodiment shown, the light source assembly 214 in this embodiment is an LED light source system. Optionally, such as... Figure 2 As shown, the LED light source system includes an LED light source 2141, a collimation and beam combining system 2142, a compound eye 2143, and a relay system 2144. The diverging beam emitted by the LED light source 2141 needs to be collimated by the collimation and beam combining system 2142 and homogenized by the compound eye 2143 before passing through the relay system 2144 to form an incident beam (P-polarized light and S-polarized light) which is then incident on the polarization beam splitter 211.

[0086] It should be noted that, unless otherwise specified, other features in this embodiment can be referred to as follows: Figure 1 The features of the first embodiment shown will not be repeated here.

[0087] Figure 3A schematic diagram of the structure of an optical system 300 according to a third embodiment of this application is shown.

[0088] like Figure 3 As shown, the optical system 300 includes a projection display device 310 and an imaging lens 350. The projection display device 310 includes a polarization beam splitter 311, an image generating element 312, and an optical compensation element 313. The imaging lens 350 is configured to project light carrying the image information output from the projection display device 310 onto at least two imaging surfaces.

[0089] In some embodiments, the polarization beam splitter 311 is configured to polarize an incident beam incident on it into at least two outgoing beams in at least two different directions. An image generating element 312 is located in the propagation path of at least one outgoing beam and is configured to modulate the outgoing beam into information light based on image information. An optical compensation element 313 is located between the polarization beam splitter 311 and the image generating element 312, and has multiple different thicknesses in the direction of the outgoing beam. For example, the optical compensation element 313 has a first thickness, a second thickness, and a third thickness that increase sequentially in the direction of the outgoing beam, such as... Figure 3 As shown. The optical compensation element 313 includes a first portion 3131 having a first thickness, a second portion 3132 having a second thickness, and a third portion 3133 having a third thickness.

[0090] Detailed, such as Figure 3 As shown, the incident beam incident on the polarization beam splitter 311 includes P-polarized light and S-polarized light. The P-polarized light consists mostly of P-polarized light and a small amount of stray light, while the S-polarized light consists mostly of S-polarized light and a small amount of stray light. The polarization beam splitter 311 has the characteristic of transmitting P-polarized light while reflecting S-polarized light. Therefore, when both P-polarized and S-polarized light are incident on the polarization beam splitter 311 simultaneously, the S-polarized light is reflected by the polarization beam splitter 311 to form the S-polarized outgoing beam.

[0091] The first portion of the S-polarized light emitted passes through a first portion of the optical compensation element 3131 with a first thickness and then enters the image generating element 312. The optical compensation element 3131 can improve the purity of this portion of S-polarized light, reduce stray light, and does not affect the polarization state of the P-polarized light. Optionally, the image generating element 312 is a reflective image generating element 312. When the image generating element 312 is in a bright state, the first portion of S-polarized light can be modulated into P-polarized light and reflected. The reflected first portion of P-polarized light passes through the first portion of the optical compensation element 3131 and then enters the polarization beam splitter 311. Since the optical compensation element 3131 does not affect the polarization state of the P-polarized light, and the polarization beam splitter 311 has the characteristic of transmitting P-polarized light, the first portion of P-polarized light passes through the polarization beam splitter 311 and is transmitted into the imaging lens 350 and projected onto the first imaging surface 351.

[0092] Similarly, the second portion of the S-polarized light emitted passes through the second portion of the optical compensation element 3132 with a second thickness and then enters the image generating element 312. The optical compensation element 3132 can improve the purity of this portion of S-polarized light, reduce stray light, and does not affect the polarization state of the P-polarized light. When the image generating element 312 is in a bright state, the second portion of the S-polarized light can be modulated into P-polarized light and reflected. The reflected second portion of the P-polarized light passes through the second portion of the optical compensation element 3132 and then enters the polarization beam splitter 311. Since the optical compensation element 3132 does not affect the polarization state of the P-polarized light, and the polarization beam splitter 311 has the characteristic of transmitting P-polarized light, the second portion of the P-polarized light passes through the polarization beam splitter 311 and is transmitted into the imaging lens 350 and projected onto the second imaging surface 352.

[0093] Similarly, the S-polarized light emitted from the third portion enters the image generating element 312 after passing through the third portion optical compensation element 3133 with a third thickness. The optical compensation element 3133 can improve the purity of this portion of S-polarized light, reduce stray light, and does not affect the polarization state of the P-polarized light. When the image generating element 312 is in a bright state, the S-polarized light from the third portion can be modulated into P-polarized light and reflected. The reflected P-polarized light from the third portion passes through the third portion optical compensation element 3133 and is incident on the polarization beam splitter 311. Since the optical compensation element 3133 does not affect the polarization state of the P-polarized light, and the polarization beam splitter 311 has the characteristic of transmitting P-polarized light, the P-polarized light from the third portion passes through the polarization beam splitter 311 and is transmitted into the imaging lens 350 and projected onto the third imaging surface 353.

[0094] In the above scheme, since the optical compensation element 313 has a first thickness, a second thickness, and a third thickness that increase sequentially, the materials of the optical compensation element 313 with different thicknesses result in different refractive indices in different parts of the optical compensation element 313. Therefore, the P-polarized light carrying image information reflected by the image generating element 312 can be displayed on the first imaging surface 351, the second imaging surface 352, and the third imaging surface 353 at different positions, forming a three-screen system with a simple structure and low cost.

[0095] It is understood that this application only describes the case where the optical compensation element 313 has three different thicknesses. Depending on the actual situation, the optical compensation element 313 can be configured to have four or more different thicknesses to realize a four-screen system or a multi-screen system. This application does not limit this.

[0096] Furthermore, when the image generating element 312 is in a dark state, the S-polarized light incident on the image generating element 312 does not change its polarization state. The light modulated by the image generating element 312 is still S-polarized light, but the angle has been deflected. The function of the optical compensation element 313 is to shift the phase of the modulated S-polarized light in the dark state, so as to suppress the angle deviation of the polarization axis caused by the direction of the S-polarized light illuminating the polarization beam splitter 311. This can effectively improve the polarization state purity of the S-polarized light in the dark state, so that it can be reflected as much as possible when passing through the polarization beam splitter 311, avoiding some light from being transmitted to the imaging lens 350 to form dark stray light, thereby improving the overall contrast of the optical system 300.

[0097] In some embodiments, the side of the optical compensation element 313 facing the polarization beam splitter 311 is a stepped surface, while the side of the optical compensation element 313 facing the image generating element 312 is a flat surface. By setting the surface to a stepped shape, the optical compensation element 313 can have multiple different thicknesses, and the manufacturing process is simple and feasible. For example, as... Figure 3 As shown, the optical compensation element 313 has a first step surface, a second step surface, and a third step surface on the side facing the polarization beam splitter 311.

[0098] In some embodiments, the relative distances between the first imaging surface 351 and the second imaging surface 352, and between the second imaging surface 352 and the third imaging surface 353, are approximately greater than or equal to 20 mm and less than or equal to 50 mm. In the above scheme, controlling the distance between the imaging surfaces and the position of the optical compensation element 313 can ensure the overall size of the device while ensuring the full utilization of the optical compensation element 313.

[0099] It should be noted that, unless otherwise specified, other features in this embodiment can be referred to as follows: Figure 1 The first embodiment shown or Figure 2 The features of the second embodiment shown will not be repeated here.

[0100] Figure 4 The diagram shown is a flow chart of a method 400 for manufacturing an optical system according to an embodiment of this application. Figure 4 As shown, the manufacturing method 400 of the optical system includes the following steps:

[0101] S420. The polarization beam splitter is positioned in the propagation direction of the incident beam, and the polarization beam splitter is configured to polarize the incident beam into at least two outgoing beams in different directions.

[0102] S440. At least one image generating element is disposed in the propagation path of the outgoing beam, and the image generating element is configured to modulate the outgoing beam into information light based on image information.

[0103] S460. An optical compensation element is disposed between the polarization beam splitter and the image generating element, the optical compensation element being configured to allow at least a portion of the outgoing beam and the information beam to pass through; and

[0104] S480, The imaging lens is positioned in the direction of information light propagation, and the imaging lens is configured to project information light onto at least two imaging surfaces.

[0105] It should be understood that the steps shown in manufacturing method 400 are not exclusive, and other steps may be performed before, after, or between any of the steps shown. Furthermore, some of the steps may be performed simultaneously or in a manner different from [the steps described]. Figure 4 The process is carried out in the order shown.

[0106] In some embodiments, the step S460 of placing the optical compensation element between the polarization beam splitter and the image generating element includes: placing the optical compensation element, whose projection in the direction of the outgoing beam at least covers a portion of the image generating element, between the polarization beam splitter and the image generating element.

[0107] Specifically, such as Figure 1 As shown, the following is adopted Figure 4 The optical system 100 manufactured by the method shown includes a projection display device 110 and an imaging lens 150. The projection display device 110 includes a polarization beam splitter 111, an image generating element 112, and an optical compensation element 113. The imaging lens 150 is configured to project light carrying the image information output from the projection display device 110 onto at least two imaging surfaces.

[0108] A polarization beam splitter 111 is configured to polarize an incident beam incident upon it into at least two outgoing beams in at least two different directions. Exemplarily, the polarization beam splitter 111 is a PBS prism. An image generating element 112 is located in the propagation path of at least one outgoing beam and is configured to modulate the outgoing beam into information light based on image information. An optical compensation element 113 is located between the polarization beam splitter 111 and the image generating element 112, and the projection of the optical compensation element 113 in the direction of the outgoing beam partially covers the image generating element 112, as shown in the reference. Figure 1 As shown.

[0109] Detailed, such as Figure 1 As shown, the incident beam incident on the polarization beam splitter 111 includes P-polarized light and S-polarized light. The P-polarized light comprises mostly P-rays and a small amount of stray light, while the S-polarized light comprises mostly S-rays and a small amount of stray light. The polarization beam splitter 111 has the characteristic of transmitting P-polarized light while reflecting S-polarized light. Therefore, when both P-polarized and S-polarized light are incident on the polarization beam splitter 111 simultaneously, the S-polarized light is reflected by the polarization beam splitter 111 to form the S-polarized outgoing beam.

[0110] The first portion of the S-polarized light emitted passes through the optical compensation element 113 and then enters the image generating element 112. The optical compensation element 113 can improve the purity of this portion of S-polarized light, reduce stray light, and does not affect the polarization state of the P-polarized light. Optionally, the image generating element 112 is a reflective image generating element 112. When the image generating element 112 is in a bright state, the first portion of S-polarized light can be modulated into P-polarized light and reflected. The reflected first portion of P-polarized light passes through the optical compensation element 113 and then enters the polarization beam splitter 111. Since the optical compensation element 113 does not affect the polarization state of the P-polarized light, and the polarization beam splitter 111 has the characteristic of transmitting P-polarized light, the first portion of P-polarized light passes through the polarization beam splitter 111 and is transmitted into the imaging lens 150 and projected onto the first imaging surface 151.

[0111] The S-polarized light beam emitted from the second part does not pass through the optical compensation element 113, but directly enters the image generating element 112. The image generating element 112 modulates the S-polarized light of the second part into P-polarized light and reflects it. The reflected P-polarized light of the second part passes through the polarization beam splitter 111 and is transmitted into the imaging lens 150 and projected onto the second imaging surface 152.

[0112] In the above scheme, since only a portion of the S-polarized light emitted passes through the optical compensation element 113, the optical compensation element 113 only reduces stray light in this portion of the S-polarized light. Moreover, the material of the optical compensation element 113 has a corresponding refractive index, so the P-polarized light carrying image information reflected by the image generating element 112 can be displayed on the first imaging surface 151 and the second imaging surface 152 at different positions, forming a dual-screen system with a simple structure and low cost.

[0113] Furthermore, when the image generating element 112 is in a dark state, the S-polarized light incident on the image generating element 112 does not change its polarization state. The light modulated by the image generating element 112 is still S-polarized light, but the angle has been deflected. If some of the light directly enters the imaging surface, it will form dark stray light. The optical compensation element 113 of this application can shift the phase of the modulated S-polarized light in the dark state to suppress the angular deviation of the polarization axis caused by the direction of the S-polarized light illuminating the polarization beam splitter 111. This can effectively improve the polarization state purity of the S-polarized light in the dark state, so that it can be reflected as much as possible when passing through the polarization beam splitter 111, avoiding some light from being transmitted to the imaging lens 150 to form dark stray light, thereby improving the overall contrast of the optical system 100.

[0114] In some embodiments, the fast axis rotation angle θ of the optical compensation element 113 can be adjusted by rotating the optical compensation element 113. For example, the fast axis rotation angle θ of the optical compensation element 113 can be adjusted between -20° and 20° to find the lowest value in the dark state, at which point the purity of the dark-state S-polarized light is the highest, which can suppress the phase shift of the S-polarized light modulated by the image generating element 112 in the dark state.

[0115] For example, the wavelength range of the optical compensation element 113 is 400nm-700nm, and the refractive index n of the optical compensation element 113 is greater than or equal to 1.4 and less than or equal to 1.8. When fabricating the optical compensation element 113, multiple waveplates can be stacked with their optical axes intersecting each other at an angle to achieve different phase delay effects.

[0116] Furthermore, the P-polarized light in the incident light passes through the polarization beam splitter 111 along the incident direction. Optionally, another image generating element (not shown) may also be provided in the outgoing light path of the P-polarized light.

[0117] In some embodiments, the projection of the optical compensation element 113 in the direction of the emitted beam approximately covers half of the image generating element 112.

[0118] In some embodiments, the thickness of the optical compensation element 113 is less than or equal to 2 mm, which can reduce the difficulty of assembling and adjusting the optical compensation element 113. For example, if the thickness of the optical compensation element 113 is too thick, it will cause the back focal length of the imaging lens 150 to increase, and the imaging lens 150 will be under greater pressure.

[0119] In some embodiments, the distance between the first imaging surface 151 and the second imaging surface 152 satisfies the following relationship:

[0120]

[0121] Where ΔL is the distance between the first imaging surface 151 and the second imaging surface 152, ΔL = L2 - L1, L2 is the distance between the first imaging surface 151 and the imaging lens 150, and L1 is the distance between the second imaging surface 152 and the imaging lens 150. L1 can also be understood as the distance between the imaging surface closer to the imaging lens 150 and the imaging lens 150, and L2 can also be understood as the distance between the imaging surface farther from the imaging lens 150 and the imaging lens 150 (refer to...). Figure 1 ), d is the thickness of the optical compensation element 113, n is the refractive index of the optical compensation element 113, and f' is the focal length of the imaging lens 150.

[0122] In some embodiments, the ratio between the focal length f' of the imaging lens 150 and the thickness d of the optical compensation element 113 is greater than or equal to 10 and less than or equal to 100. Optionally, the imaging lens 150 is a combination of multiple lenses, and the focal length f' of the imaging lens 150 is the focal length of the entire set.

[0123] For example, the range of ΔL is approximately greater than or equal to 20 mm and less than or equal to 50 mm.

[0124] In the above solution, controlling the distance between the imaging surfaces and the thickness of the optical compensation element 113 can ensure the overall size of the device while making full use of the optical compensation element 113. Moreover, when the optical system 100 of this application is applied to an automotive HUD, controlling the overall size of the HUD can simultaneously ensure the comfort of the human eye.

[0125] In some embodiments, the ratio between the lens length TL of the imaging lens 150 and the focal length f' of the imaging lens 150 is less than or equal to 4.9.

[0126] It is understandable that when the imaging lens 150 is a combination of multiple lenses, the lens length TL of the imaging lens 150 is the distance from the center of the front face of the first lens to the center of the rear face of the last lens.

[0127] In the above scheme, the lens group is short and the structure is compact, which is conducive to the miniaturization of the imaging lens 150, reduces lens sensitivity, improves production yield, and reduces production costs.

[0128] In some embodiments, the ratio between the optical back focal length (BFL) of the imaging lens 150 and the lens length (TL) of the imaging lens 150 is greater than or equal to 0.3.

[0129] The optical back focal length (BFL) of the imaging lens 150 mentioned above is the distance from the rear end face of the last lens of the imaging lens 150 to the imaging surface.

[0130] The above solution can achieve miniaturization while maintaining a long back focal length, which is beneficial for the assembly of lighting elements such as prisms.

[0131] In some embodiments, the image generating element 112 is a reflective liquid crystal display chip (LCOS chip). The LCOS chip has a high resolution, so that the clarity is not affected even when a dual-screen system is formed as described above.

[0132] In some embodiments, the manufacturing method further includes: placing a light source assembly in the incident light path of the polarizing beam splitter, the light source assembly being configured to emit an incident light beam.

[0133] Optional, such as Figure 1 As shown, the light source assembly 114 is an LD light source 1141 system. Optionally, the LD light source 1141 system includes an LD light source 1141, a beam expander system 1142, a compound eye 1143, and a relay system 1144. The beam emitted by the LD light source 1141 needs to be expanded by the beam expander system 1142, homogenized by the compound eye 1143, and then passed through the relay system 1144 to form an incident beam (P-polarized light and S-polarized light) which is then incident on the polarization beam splitter 111.

[0134] Replaceable, such as Figure 2 As shown, the light source assembly 214 is an LED light source system. The LED light source system includes an LED light source 2141, a collimation and beam combining system 2142, a compound eye 2143, and a relay system 2144. The diverging beam emitted by the LED light source 2141 needs to be collimated by the collimation and beam combining system 2142 and homogenized by the compound eye 2143 before passing through the relay system 2144 to form an incident beam (P-polarized light and S-polarized light) which is then incident on the polarization beam splitter 211.

[0135] In some embodiments, the step S460 of placing the optical compensation element between the polarization beam splitter and the image generation element includes: placing an optical compensation element having multiple different thicknesses in the direction of the emitted beam between the polarization beam splitter and the image generation element.

[0136] Specifically, such as Figure 3 As shown, the following is adopted Figure 4 The optical system 300 manufactured by the method shown includes a projection display device 310 and an imaging lens 350. The projection display device 310 includes a polarization beam splitter 311, an image generating element 312, and an optical compensation element 313. The imaging lens 350 is configured to project light carrying the image information output from the projection display device 310 onto at least two imaging surfaces.

[0137] In some embodiments, the polarization beam splitter 311 is configured to polarize an incident beam incident on it into at least two outgoing beams in at least two different directions. An image generating element 312 is located in the propagation path of at least one outgoing beam and is configured to modulate the outgoing beam into information light based on image information. An optical compensation element 313 is located between the polarization beam splitter 311 and the image generating element 312, and has multiple different thicknesses in the direction of the outgoing beam. For example, the optical compensation element 313 has a first thickness, a second thickness, and a third thickness that increase sequentially in the direction of the outgoing beam, such as... Figure 3 As shown. The optical compensation element 313 includes a first portion 3131 having a first thickness, a second portion 3132 having a second thickness, and a third portion 3133 having a third thickness.

[0138] Detailed, such as Figure 3 As shown, the incident beam incident on the polarization beam splitter 311 includes P-polarized light and S-polarized light. The P-polarized light comprises mostly P-rays and a small amount of stray light, while the S-polarized light comprises mostly S-rays and a small amount of stray light. The polarization beam splitter 311 has the characteristic of transmitting P-polarized light while reflecting S-polarized light. Therefore, when both P-polarized and S-polarized light are incident on the polarization beam splitter 311 simultaneously, the S-polarized light is reflected by the polarization beam splitter 311 to form the S-polarized outgoing beam.

[0139] The first portion of the S-polarized light emitted passes through a first portion of the optical compensation element 3131 with a first thickness and then enters the image generating element 312. The optical compensation element 3131 can improve the purity of this portion of S-polarized light, reduce stray light, and does not affect the polarization state of the P-polarized light. Optionally, the image generating element 312 is a reflective image generating element 312. When the image generating element 312 is in a bright state, the first portion of S-polarized light can be modulated into P-polarized light and reflected. The reflected first portion of P-polarized light passes through the first portion of the optical compensation element 3131 and then enters the polarization beam splitter 311. Since the optical compensation element 3131 does not affect the polarization state of the P-polarized light, and the polarization beam splitter 311 has the characteristic of transmitting P-polarized light, the first portion of P-polarized light passes through the polarization beam splitter 311 and is transmitted into the imaging lens 350 and projected onto the first imaging surface 351.

[0140] Similarly, the second portion of the S-polarized light emitted passes through the second portion of the optical compensation element 3132 with a second thickness and then enters the image generating element 312. The optical compensation element 3132 can improve the purity of this portion of S-polarized light, reduce stray light, and does not affect the polarization state of the P-polarized light. When the image generating element 312 is in a bright state, the second portion of the S-polarized light can be modulated into P-polarized light and reflected. The reflected second portion of the P-polarized light passes through the second portion of the optical compensation element 3132 and then enters the polarization beam splitter 311. Since the optical compensation element 3132 does not affect the polarization state of the P-polarized light, and the polarization beam splitter 311 has the characteristic of transmitting P-polarized light, the second portion of the P-polarized light passes through the polarization beam splitter 311 and is transmitted into the imaging lens 350 and projected onto the second imaging surface 352.

[0141] Similarly, the S-polarized light emitted from the third portion enters the image generating element 312 after passing through the third portion optical compensation element 3133 with a third thickness. The optical compensation element 3133 can improve the purity of this portion of S-polarized light, reduce stray light, and does not affect the polarization state of the P-polarized light. When the image generating element 312 is in a bright state, the S-polarized light from the third portion can be modulated into P-polarized light and reflected. The reflected P-polarized light from the third portion passes through the third portion optical compensation element 3133 and is incident on the polarization beam splitter 311. Since the optical compensation element 3133 does not affect the polarization state of the P-polarized light, and the polarization beam splitter 311 has the characteristic of transmitting P-polarized light, the P-polarized light from the third portion passes through the polarization beam splitter 311 and is transmitted into the imaging lens 350 and projected onto the third imaging surface 353.

[0142] In the above scheme, since the optical compensation element 313 has a first thickness, a second thickness, and a third thickness that increase sequentially, the materials of the optical compensation element 313 with different thicknesses result in different refractive indices in different parts of the optical compensation element 313. Therefore, the P-polarized light carrying image information reflected by the image generating element 312 can be displayed on the first imaging surface 351, the second imaging surface 352, and the third imaging surface 353 at different positions, forming a three-screen system with a simple structure and low cost.

[0143] It is understood that this application only describes the case where the optical compensation element 313 has three different thicknesses. Depending on the actual situation, the optical compensation element 313 can be configured to have four or more different thicknesses to realize a four-screen system or a multi-screen system. This application does not limit this.

[0144] Furthermore, when the image generating element 312 is in a dark state, the S-polarized light incident on the image generating element 312 does not change its polarization state. The light modulated by the image generating element 312 is still S-polarized light, but the angle has been deflected. The function of the optical compensation element 313 is to shift the phase of the modulated S-polarized light in the dark state, so as to suppress the angle deviation of the polarization axis caused by the direction of the S-polarized light illuminating the polarization beam splitter 311. This can effectively improve the polarization state purity of the S-polarized light in the dark state, so that it can be reflected as much as possible when passing through the polarization beam splitter 311, avoiding some light from being transmitted to the imaging lens 350 to form dark stray light, thereby improving the overall contrast of the optical system 300.

[0145] In some embodiments, the side of the optical compensation element 313 facing the polarization beam splitter 311 is a stepped surface, while the side of the optical compensation element 313 facing the image generating element 312 is a flat surface. By setting the surface to a stepped shape, the optical compensation element 313 can have multiple different thicknesses, and the manufacturing process is simple and feasible. For example, as... Figure 3 As shown, the optical compensation element 313 has a first step surface, a second step surface, and a third step surface on the side facing the polarization beam splitter 311.

[0146] In some embodiments, the relative distances between the first imaging surface 351 and the second imaging surface 352, and between the second imaging surface 352 and the third imaging surface 353, are approximately greater than or equal to 20 mm and less than or equal to 50 mm. In the above scheme, controlling the distance between the imaging surfaces and the position of the optical compensation element 313 can ensure the overall size of the device while ensuring the full utilization of the optical compensation element 313.

[0147] It should be noted that, unless otherwise specified, other features in this embodiment can be referred to as follows: Figure 1 The optical system 100 shown or Figure 2 The optical system 200 shown is not described in detail here.

[0148] The above description is merely an illustration of the embodiments of this application and the technical principles employed. Those skilled in the art should understand that the scope of protection involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the technical concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. A projection display device, characterized in that, include: A polarizing beam splitter configured to polarize an incident beam incident on the polarizing beam splitter into at least two outgoing beams in different directions; At least one image generating element is located in the propagation path of the outgoing light beam and is configured to modulate the outgoing light beam into information light based on image information; as well as An optical compensation element is located between the polarization beam splitter and the image generating element, allowing at least a portion of the outgoing beam and the information light to pass through. The optical compensation element is configured to shift the phase of the polarized light modulated by the at least one image generating element to suppress the angular deviation of the polarization axis caused by the direction in which the polarized light illuminates the polarization beam splitter.

2. The projection display device according to claim 1, characterized in that, The projection of the optical compensation element onto the direction of the emitted beam at least partially covers the image generating element.

3. The projection display device according to claim 2, characterized in that, The projection of the optical compensation element onto the direction of the emitted beam does not exceed one-half of that of the image generating element.

4. The projection display device according to claim 2, characterized in that, The thickness of the optical compensation element is less than or equal to 2 mm.

5. The projection display device according to claim 1, characterized in that, The optical compensation element has multiple different thickness dimensions in the direction of the emitted beam.

6. The projection display device according to claim 5, characterized in that, The side of the optical compensation element facing the polarization beam splitter has a stepped surface; and The side of the optical compensation element facing the image generating element is a plane.

7. The projection display device according to claim 5, characterized in that, The maximum thickness of the optical compensation element is less than or equal to 2 mm.

8. The projection display device according to any one of claims 1-7, characterized in that, The wavelength of the optical compensation element is greater than or equal to 400 nm and less than or equal to 700 nm; and The refractive index of the optical compensation element is greater than or equal to 1.4 and less than or equal to 1.

8.

9. The projection display device according to any one of claims 1-7, characterized in that, The fast axis rotation angle of the optical compensation element is greater than or equal to -20° and less than or equal to 20°.

10. The projection display device according to any one of claims 1-7, characterized in that, The image generating element is a reflective liquid crystal display chip.

11. The projection display device according to any one of claims 1-7, characterized in that, Also includes: A light source assembly is disposed in the incident light path of the polarization beam splitter and forms the incident beam.

12. The projection display device according to claim 11, characterized in that, The light source component is an LD light source system or an LED light source system.

13. An optical system, characterized in that, include: The projection display device as described in any one of claims 1 to 12; as well as An imaging lens is configured to project information light carrying the image information output by the projection display device onto at least two imaging surfaces.

14. The optical system according to claim 13, characterized in that, The distance between the at least two imaging surfaces is greater than or equal to 20 mm and less than or equal to 50 mm.

15. The optical system according to claim 13, characterized in that, The ratio between the focal length of the imaging lens and the thickness of the optical compensation element is greater than or equal to 10 and less than or equal to 100.

16. The optical system according to claim 13, characterized in that, The ratio between the lens length and the focal length of the imaging lens is less than or equal to 4.

9.

17. The optical system according to claim 13, characterized in that, The ratio between the optical back focal length of the imaging lens and the lens length of the imaging lens is greater than or equal to 0.

3.

18. A method for manufacturing an optical system, characterized in that, include: A polarizing beam splitter is positioned in the propagation direction of the incident beam, and the polarizing beam splitter is configured to polarize the incident beam into at least two outgoing beams in different directions. At least one image generating element is disposed in the propagation path of the outgoing light beam, and the image generating element is configured to modulate the outgoing light beam into information light based on image information; An optical compensation element is disposed between the polarization beam splitter and the image generating element. The optical compensation element is configured to allow at least a portion of the outgoing beam and the information light to pass through, and is configured to shift the phase of the polarized light modulated by the at least one image generating element, so as to suppress the angular deviation of the polarization axis caused by the direction of the polarized light illuminating the polarization beam splitter. as well as An imaging lens is positioned in the direction of propagation of the information light, and the imaging lens is configured to project the information light onto at least two imaging surfaces.

19. The manufacturing method according to claim 18, characterized in that, The optical compensation element is disposed between the polarization beam splitter and the image generation element, including: The optical compensation element, whose projection in the direction of the emitted beam covers at least a portion of the image generating element, is disposed between the polarization beam splitter and the image generating element.

20. The manufacturing method according to claim 19, characterized in that, The projection of the optical compensation element onto the direction of the emitted beam does not exceed one-half of that of the image generating element.

21. The manufacturing method according to claim 19, characterized in that, The thickness of the optical compensation element is less than or equal to 2 mm.

22. The manufacturing method according to claim 18, characterized in that, The optical compensation element is disposed between the polarization beam splitter and the image generation element, including: The optical compensation element, having multiple different thicknesses in the direction of the emitted beam, is disposed between the polarization beam splitter and the image generating element.

23. The manufacturing method according to claim 22, characterized in that, The side of the optical compensation element facing the polarization beam splitter is configured as a stepped surface; and The side of the optical compensation element facing the image generating element is set as a plane.

24. The manufacturing method according to claim 22, characterized in that, The maximum thickness of the optical compensation element is less than or equal to 2 mm.

25. The manufacturing method according to any one of claims 18-24, characterized in that, The wavelength of the optical compensation element is greater than or equal to 400 nm and less than or equal to 700 nm; and The refractive index of the optical compensation element is greater than or equal to 1.4 and less than or equal to 1.

8.

26. The manufacturing method according to any one of claims 18-24, characterized in that, The fast axis rotation angle of the optical compensation element is greater than or equal to -20° and less than or equal to 20°.

27. The manufacturing method according to any one of claims 18-24, characterized in that, The image generating element is a reflective liquid crystal display chip.

28. The manufacturing method according to any one of claims 18-24, characterized in that, Also includes: A light source assembly is placed in the incident light path of the polarization beam splitter, and the light source assembly is configured to emit the incident light beam.

29. The manufacturing method according to claim 28, characterized in that, The light source assembly is positioned in the incident light path of the polarization beam splitter, including: An LD light source system or an LED light source system is placed in the incident light path of the polarization beam splitter.

30. The manufacturing method according to any one of claims 18-24, characterized in that, The distance between the at least two imaging surfaces is greater than or equal to 20 mm and less than or equal to 50 mm.

31. The manufacturing method according to any one of claims 18-24, characterized in that, The ratio between the focal length of the imaging lens and the thickness of the optical compensation element is greater than or equal to 10 and less than or equal to 100.

32. The manufacturing method according to any one of claims 18-24, characterized in that, The ratio between the lens length and the focal length of the imaging lens is less than or equal to 4.

9.

33. The manufacturing method according to any one of claims 18-24, characterized in that, The ratio between the optical back focal length of the imaging lens and the lens length of the imaging lens is greater than or equal to 0.3.

Images