Optical-mechanical system and near-to-eye display device

Abstract

The invention discloses an optical-mechanical system and a near-to-eye display device, and the system comprises an illumination assembly which comprises a light source and a turning prism; a display chip; the relay imaging assembly comprises a polarization beam-splitting element, a first correction lens group and a reflection element, the display chip and the reflection element are arranged on the opposite side of the polarization beam-splitting element, the display chip and the turning prism are arranged on the adjacent side of the polarization beam-splitting element, and the first correction lens group is arranged between the polarization beam-splitting element and the display chip; the first correction lens group comprises a fourth lens and a fifth lens which are glued, the fourth lens with positive focal power is arranged on one side close to the polarization beam splitting element, and the fifth lens with negative focal power is arranged on one side close to the display chip; the reflecting element has positive focal power, and the focal length f3 of the reflecting element and the focal length f of the optical-mechanical system meet the condition that f / f3 is larger than 0.6 and smaller than 1. According to the invention, the large angle and high resolution of the full-color optical-mechanical system are realized, and the small size of the lens is maintained at the same time.

Description

Technical Field

[0001] The present application relates to the field of near-eye display technology, and in particular to an optical-mechanical system and a near-eye display device. Background Art

[0002] With the rapid development of AR display technology, higher requirements are placed on the field of view (FOV), resolution, brightness, and compactness of display devices. AR display technology based on liquid crystal silicon (LCoS) has become the preferred solution for AR optical machine manufacturers at this stage due to its advantages such as high resolution, high brightness, low cost, and full-color display, and has shown great development potential. However, the FOV of existing LCoS optical machines is usually small, only around 20-40°. Although it can meet the needs of enterprise-level application scenarios, it lacks immersion in consumer-level applications, affecting user experience.

[0003] As the optical waveguide technology based on silicon carbide materials gradually matures, the FOV of diffraction waveguides can achieve a display of more than 70°. At the same time, the development of LCoS display technology enables higher resolution within the same size display area, making large viewing angle, high resolution, and high immersion AR display possible.

[0004] However, to match the waveguide, the aperture stop of the AR optical machine needs to be placed in front of the lens. In this case, the aperture stop coincides with the exit pupil of the lens, and the exit pupil diameter (EPD) is usually 2-4mm. Since the F number is proportional to the focal length f', this leads to a rapid decrease in the F number of the lens when the EPD size remains unchanged. The lens has a higher resolution requirement at a smaller F number. Therefore, the requirements of large FOV, high resolution, and miniaturization pose challenges to the design of full-color AR optical machines. Summary of the invention

[0005] One purpose of the present application is to achieve a large FOV and high resolution for a full-color optical machine system while maintaining a small size of the lens.

[0006] Another object of the present application is to achieve a large FOV for a full-color optical-mechanical system while reducing the aberrations generated in the optical-mechanical system.

[0007] Another object of the present application is to achieve a large FOV for a full-color optical-mechanical system while reducing the chromatic aberration produced in the optical-mechanical system.

[0008] In order to achieve the above objectives, the technical solution adopted in this application is: an optical-mechanical system, comprising: The lighting assembly comprises a light source and a turning prism, wherein the light source is used to provide lighting light, and the turning prism has an incident surface facing the light source, a reflection surface and an exit surface facing the polarization beam splitting element, and is used to deflect the lighting light; A display chip, used to modulate illumination light into image light; The relay imaging component comprises the polarization beam splitter, a first correction lens group and a reflection element, wherein the display chip and the reflection element are arranged on opposite sides of the polarization beam splitter, and the display chip and the turning prism are arranged on adjacent sides of the polarization beam splitter, the first correction lens group is arranged between the polarization beam splitter and the display chip, the first correction lens group comprises a glued fourth lens and a fifth lens, the fourth lens having a positive focal length is arranged on a side close to the polarization beam splitter, and the fifth lens having a negative focal length is arranged on a side close to the display chip; the reflection element has a positive focal length, and the focal length f of the reflection element is 3 The focal length f of the optical-mechanical system satisfies: 0.6<f / f 3 <1.

[0009] Preferably, a surface of the reflective element away from the polarization beam splitting element is an aspherical surface, an inner side of the aspherical surface is coated with a reflective film, and a surface of the reflective element close to the polarization beam splitting element is a plane.

[0010] As a preference, a refractive index of the fourth lens is smaller than a refractive index of the fifth lens, and an Abbe number of the fourth lens is larger than an Abbe number of the fifth lens.

[0011] Preferably, both side surfaces of the fourth lens are convex, the surface of the fifth lens away from the display chip is concave, and the surface close to the display chip is convex.

[0012] Preferably, the relay imaging assembly also includes a second corrective lens group arranged on the light-emitting side of the polarization splitter element, the second corrective lens group includes a first lens with positive optical power and a second lens with negative optical power, the first lens is arranged on a side away from the polarization splitter element, and the second lens is arranged on a side close to the polarization splitter element.

[0013] As a preference, a refractive index of the first lens is smaller than a refractive index of the second lens, and an Abbe number of the first lens is smaller than an Abbe number of the second lens.

[0014] Preferably, both side surfaces of the first lens are convex, a surface of the second lens close to the light-emitting side is concave, and a surface away from the light-emitting side is flat.

[0015] As a preference, the first lens and the second lens are glued together.

[0016] Preferably, the relay imaging assembly further comprises a first polarizer and a quarter wave plate, wherein the first polarizer is arranged on the light output side of the polarization splitter element and between the second lens and the polarization splitter element; and the quarter wave plate is arranged between the reflective element and the polarization splitter element.

[0017] Preferably, the lighting assembly further comprises a second polarizer, and the second polarizer is arranged between the exit surface of the turning prism and the polarization beam splitting element.

[0018] Preferably, the relay imaging assembly further comprises a first diffuser, and the first diffuser is arranged between the exit surface of the turning prism and the second polarizer.

[0019] As a preference, a near-eye display device comprises any of the above-mentioned optomechanical systems and waveguide devices, wherein the optomechanical system is arranged on the coupling-in side of the waveguide device, and is used to project the image light to the coupling-in port of the waveguide device.

[0020] Compared with the prior art, the beneficial effects of the present application are as follows: in the optical machine system provided by the present application, the reflective element can bear the main optical focal length, realize the short focal length required by the optical machine system at a large angle, and ensure that a large field of view can be provided; at the same time, by setting a correction lens group, the aberration and chromatic aberration caused by the increase in the field of view can be corrected to realize a high-definition full-color AR optical machine; the reuse of the reflective element, the turning prism and the correction lens group can reduce the size of the optical machine. In this way, a full-color AR optical machine with a large FOV, high resolution and miniaturization can be realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the structure of the optical-mechanical system in the embodiment of the present application.

[0022] Figure 2 This is the green light MTF diagram of the optical-mechanical system in Example 1 of the present application.

[0023] Figure 3 This is the red light MTF diagram of the optical-mechanical system in Example 1 of the present application.

[0024] Figure 4 This is the blue light MTF diagram of the optical-mechanical system in Example 1 of the present application.

[0025] Figure 5 This is a diagram of the vertical axis chromatic aberration of the optical-mechanical system in Example 1 of the present application.

[0026] Figure 6 This is the LCoS illumination diagram of the optomechanical system in Example 1 of the present application.

[0027] Figure 7This is a projection intensity distribution diagram of the optical-mechanical system in Example 1 of the present application.

[0028] Figure 8 This is the green light MTF diagram of the optical-mechanical system in Example 2 of the present application.

[0029] Fig. 9 This is the red light MTF diagram of the optical-mechanical system in Example 2 of the present application.

[0030] Fig.10 This is the blue light MTF diagram of the optical-mechanical system in Example 2 of the present application.

[0031] Fig.11 This is a diagram of the vertical axis chromatic aberration of the optical-mechanical system in Example 2 of the present application.

[0032] Fig.12 Schematic diagram of the optomechanical system in a comparative example (the lighting component is not shown).

[0033] Fig.13 This is the vertical axis chromatic aberration diagram of the optical mechanical system in the comparative example.

[0034] In the figure: 1. lighting component; 11. light source; 12. collimating lens; 13. microlens array; 14. turning prism; 141. incident surface; 142. reflecting surface; 143. exit surface; 15. second polarizer; 2. display chip; 3. relay imaging component; 31. polarization beam splitter element; 32. reflecting element; 33. first corrective lens group; 331. fourth lens; 332. fifth lens; 34. second corrective lens group; 341. first lens; 342. second lens; 35. first polarizer; 36. quarter wave plate; 37. polarization beam splitter film. DETAILED DESCRIPTION

[0035] Below, the present application is further described in conjunction with specific implementation methods. It should be noted that, under the premise of no conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0036] In the description of the present application, it should be noted that directional words, such as the terms "center", "lateral", "longitudinal", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", etc., indicating directions and positional relationships are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of narrating the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and cannot be understood as limiting the specific scope of protection of the present application.

[0037] It should be noted that the terms "first", "second", etc. in the description and claims of the present application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0038] The terms "including" and "having" and any variations thereof in the specification and claims of this application are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products or apparatuses.

[0039] like Figure 1 As shown, the optical-mechanical system of the present application includes an illumination component 1, a display chip 2, and a relay imaging component 3. The illumination component 1 includes a light source 11 and a turning prism 14. The light source 11 is used to provide illumination light, and the turning prism 14 is used to deflect the illumination light. The display chip 2 is used to modulate the illumination light into image light. The relay imaging component 3 is correspondingly arranged in the optical path between the illumination component 1 and the display chip 2, and is used to transmit the illumination light provided by the illumination component 1 to the display chip 2, and perform imaging projection on the image light modulated by the display chip 2.

[0040] like Figure 1 As shown, the relay imaging component 3 includes a polarization beam splitter element 31 and a reflective element 32. The display chip 2 and the reflective element 32 are arranged on opposite sides of the polarization beam splitter element 31, and the display chip 2 and the turning prism 14 are arranged on adjacent sides of the polarization beam splitter element 31. The turning prism 14 has an incident surface 141, a reflective surface 142, and an exit surface 143. The incident surface 141 faces the light source 11, and the exit surface 143 faces the light-incoming side of the polarization beam splitter element 31. The light source 11 emits illumination light, which is deflected by the turning prism 14 and then incident on the polarization beam splitter element 31. After being refracted by the polarization beam splitter element 31, it reaches the display chip 2. The illumination light is modulated by the display chip 2 and converted into image light. The image light is folded back again and passes through the polarization beam splitter element 31 to reach the reflective element 32. After being reflected by the reflective element 32, the image light enters the polarization beam splitter element 31 again, and is refracted by the polarization beam splitter element 31 and then emitted from the light-exiting side.

[0041] It is worth mentioning that the reflective element 32 has positive optical power, and the focal length f of the reflective element 32 is 3 The focal length f of the optical system satisfies: 0.6<f / f 3 <1. From f 3From the relationship with f, it can be seen that the reflective element 32 is used to bear the main optical focal length of the optical machine system, realize the short focal length required for large angles, and ensure that a large field of view can be provided. However, usually when the FOV (field of view) is large, the chromatic aberration of the lens will increase sharply for a full-color projection lens. Based on this, the relay imaging component 3 of the present application also includes a first correction lens group 33 for correcting system chromatic aberration and other residual aberrations.

[0042] In some embodiments, the first correction lens group 33 is arranged between the display chip 2 and the polarization beam splitter 31. The first correction lens group 33 includes a fourth lens 331 with positive focal length and a fifth lens 332 with negative focal length. The fourth lens 331 and the fifth lens 332 can be glued together. The fourth lens 331 with positive focal length usually produces negative chromatic aberration, and the fifth lens 332 with negative focal length usually produces positive chromatic aberration. Optimizing the focal length ratio of the fourth lens 331 and the fifth lens 332 can make the negative chromatic aberration of the positive lens and the positive chromatic aberration of the negative lens offset each other, thereby significantly reducing chromatic aberration. In addition, adjusting the shape and position of the fourth lens 331 and the fifth lens 332 can also effectively correct the aberration of the optical machine system.

[0043] Furthermore, the fourth lens 331 is arranged on a side close to the polarization beam splitter 31, and the fifth lens 332 is arranged on a side close to the display chip 2. The illumination component 1 emits illumination light, and before the illumination light reaches the display chip 2 after being refracted by the polarization beam splitter 31, it is first converged and diverged by the fourth lens 331 and the fifth lens 332, and the chromatic aberration and aberration correction are performed on the illumination light to better meet the imaging requirements of the display chip 2, thereby presenting a higher quality image on the display screen, with more saturated colors and higher contrast.

[0044] In some embodiments, the refractive index of the fourth lens 331 is less than that of the fifth lens 332, and the Abbe number of the fourth lens 331 is greater than that of the fifth lens 332. In the combination of the fourth lens 331 and the fifth lens 332, due to the lower refractive index of the fourth lens 331, the light will be more obviously refracted when entering the fifth lens 332 with a high refractive index, thereby changing the propagation direction of the light, so that the light is focused on the display chip 2 to form a clearer and more uniform image light. The fourth lens 331 uses a high Abbe number material, which can significantly reduce chromatic aberration, so that light of different wavelengths can be more closely focused on the same point, and the low Abbe number of the fifth lens 332 can be used to further adjust the focusing characteristics of the light. Through this combination of high and low Abbe numbers, chromatic aberration in the optical system can be effectively corrected.

[0045] Furthermore, both sides of the fourth lens 331 with positive focal length are convex, which helps to converge light, so that the light is fully converged to the fifth lens 332, while the surface of the fifth lens 332 with negative focal length away from the display chip 2 is concave, and the surface close to the display chip 2 is convex. The combination of the concave and convex surfaces of the fifth lens 332 helps to optimize the distribution range of light on the display chip 2, thereby improving the utilization rate of the display chip 2 for the light from the fourth lens 331 and the fifth lens 332. Furthermore, the surface of the fourth lens 331 close to the polarization beam splitter 31 is aspherical, which can converge light to a more precise focus, reduce blur, and improve the clarity and sharpness of the image.

[0046] Furthermore, the relay imaging component 3 of the present application also includes a second corrective lens group 34 arranged at the light-outgoing side of the polarization beam splitter 31 to further reduce the chromatic aberration and residual aberration in the system. It is worth mentioning that the light-outgoing side and the light-incoming side of the polarization beam splitter 31 are arranged opposite to each other. In the present application, the first corrective lens group 33 is arranged at the position where the image light just emerges from the display chip 2, and the second corrective lens group 34 is arranged at the final exit position of the image light. By arranging the corrective lens groups at these two positions, the chromatic aberration and aberration of the full-color optical machine system can be more efficiently reduced.

[0047] Specifically, after the display chip 2 modulates the incident illumination light into image light, it first passes through the first correction lens group 33 for chromatic aberration correction, then passes through the polarization splitter element 31 and reaches the reflective element 32. Subsequently, the image light changes direction through the reflective element 32 and reaches the polarization splitter element 31 again. After being refracted by the polarization splitter element 31, it enters the second correction lens group 34 for chromatic aberration correction again, and the corrected image light is emitted from the output end.

[0048] Furthermore, the second correction lens group 34 includes a first lens 341 with positive optical power and a second lens 342 with negative optical power. By optimizing the optical power ratio of the first lens 341 and the second lens 342, spherical aberration and coma can be effectively corrected. The first lens 341 is arranged on a side away from the polarization beam splitter 31, and the second lens 342 is arranged on a side close to the polarization beam splitter 31. The image light can effectively remove chromatic aberration and aberration through the second correction lens group 34, thereby optimizing the image quality.

[0049] In some embodiments, the refractive index of the first lens 341 is less than that of the second lens 342, and the Abbe number of the first lens 341 is less than that of the second lens 342. The first lens 341 with a lower refractive index generally has a weaker light focusing ability, while the second lens 342 with a higher refractive index has a stronger focusing ability. By properly matching the first lens 341 and the second lens 342, better light control can be achieved at different wavelengths, and the overall optical performance of the system can be optimized. The combination of the first lens 341 with a low Abbe number and the second lens 342 with a high Abbe number can effectively correct chromatic aberration, reduce color halo or blur, and significantly improve the imaging quality of the optical system.

[0050] Furthermore, both side surfaces of the first lens 341 with positive focal power are convex, and the second lens 342 with negative focal power has a concave surface on the side close to the light-emitting side and a plane on the side away from the light-emitting side. The divergent effect of the second lens 342 with negative focal power can cooperate with the convergent effect of the first lens 341 with positive focal power in the previous stage to jointly correct aberrations in the optical system, such as spherical aberration and chromatic aberration. The image light reflected by the reflective element 32 onto the polarization beam splitter element 31 enters the combined lens of the first lens 341 and the second lens 342 after being refracted by the polarization beam splitter element 31. The plane of the second lens 342 with negative focal power away from the light-emitting side can transmit the image light in a stable direction to the concave surface close to the light-emitting side. After being evenly dispersed by the concave surface, the image light enters the first lens 341 with positive focal power, both sides of which are convex, to be converged, and finally outputs image light with uniform brightness and high clarity from the light-emitting side.

[0051] The first correction lens group 33 and the second correction lens group 34 are mainly used to improve dispersion and aberration. The two lenses in the first correction lens group 33 are very close to the image plane, and they act as a field lens and do not make a major contribution to the optical focal length. The combined optical focal length of the two lenses in the second correction lens group 34 is very small, and contributes very little to the optical focal length of the system. Therefore, the optical focal length of the optical machine system is mainly borne by the reflective element 32.

[0052] In some embodiments, the first corrective lens group 33 is formed by gluing a fourth lens 331 and a fifth lens 332 to form a double-glued lens. By optimizing the curvature radius and shape of the fourth lens 331 and the fifth lens 332, the light can be focused more evenly when passing through the lens, thereby reducing coma. By adjusting the thickness and relative position of the fourth lens 331 and the fifth lens 332, the double-glued lens can change the optical path of the light through the lens, thereby correcting the aberration.

[0053] The optical-mechanical system of the present application reuses the fourth lens 331 and the fifth lens 332 in the imaging lens, reducing the number of relay lenses required and effectively reducing the volume of the lighting assembly 1 and the system complexity.

[0054] In some embodiments, the bonding material may be photosensitive glue, UV curable adhesive, optical epoxy resin glue, etc.

[0055] Similarly, the second corrective lens group 34 is formed by gluing a first lens 341 and a second lens 342 together to form a double gluing lens.

[0056] Furthermore, the relay imaging component 3 also includes a first polarizer 35 and a quarter wave plate 36. The first polarizer 35 is arranged on the light-emitting side of the polarization beam splitter 31 and between the second lens 342 and the polarization beam splitter 31, and can selectively pass light of a specific polarization direction, reduce interference from stray light and reflected light, and protect subsequent optical elements; the quarter wave plate 36 is arranged between the reflective element 32 and the polarization beam splitter 31, and is glued to the reflective element 32, and can cause the incident light to generate a quarter wavelength phase delay in a specific direction, converting linear polarized light into circular polarized light, or converting circular polarized light into linear polarized light.

[0057] In some embodiments, the first polarizer 35 is an absorption type linear polarizer, which is disposed in the light path between the second lens 342 and the polarization beam splitter 31 and attached to the polarization beam splitter 31 to absorb the emitted stray light and improve the optical-mechanical contrast.

[0058] Furthermore, the lighting assembly 1 also includes a second polarizer 15, which is arranged between the output surface 143 of the turning prism 14 and the polarization splitter element 31, ensuring that the light emitted from the output surface 143 of the turning prism 14 has a uniform polarization direction, providing consistent polarized light for the polarization splitter element 31.

[0059] In some embodiments, the second polarizer 15 is an absorption polarizer, which is disposed in the light path between the turning prism 14 and the polarization splitter 31 and attached to the polarization splitter 31 to better control the polarization state of light, thereby optimizing the performance of the entire system.

[0060] The illumination light passes through the second polarizer 15 and becomes the first polarized light (exemplarily, it can be s-polarized light). The first polarized light enters the first corrective lens group 33 after being reflected by the polarization splitter element 31, and enters the display chip 2 after being emitted from the first corrective lens group 33. After being modulated by the display chip 2, the second polarized light is formed (exemplarily, it can be p-polarized light). Then, the second polarized light passes through the first corrective lens group 33 and the polarization splitter element 31 again to reach the quarter-wave plate 36, and is converted into the third polarized light (exemplarily, it can be circularly polarized light) after being adjusted by the quarter-wave plate 36. The third polarized light is reflected by the reflective element 32 and then passes through the quarter-wave plate 36 again to be converted into the fourth polarized light (exemplarily, it can be s-polarized light). Then, the fourth polarized light passes through the polarization splitter element 31 again, and after being emitted, it enters the second corrective lens group 34 from the light output side, and is output as an image after chromatic aberration correction.

[0061] Furthermore, the lighting assembly 1 also includes a collimating lens 12 and a microlens array 13 which are sequentially arranged on the light incident side of the polarization splitter element 31. The light source 11 is used to emit light, the collimating lens 12 is used to collimate the light emitted by the light source 11, the microlens array 13 is used to homogenize the collimated light, and the turning prism 14 can be used to reflect the homogenized light so that it deflects 90 degrees and then enters the polarization splitter element 31.

[0062] Furthermore, the light source 11 can be a three-in-one LED with a single-channel lighting design, so that the light source 11 occupies less space in the lighting assembly 1, which can reduce the size of the optical machine. Furthermore, the double-cemented lens composed of the fourth lens 331 and the fifth lens 332 in the imaging lens can be reused in the optical machine system, which can better reduce the size of the optical machine. In this way, by using the combined design of the lighting assembly 1, the relay imaging assembly 3, the display chip 2, etc., the size of the optical machine can be miniaturized while ensuring the uniformity of the lighting of the optical machine system.

[0063] Furthermore, both side surfaces of the collimating lens 12 are aspherical. The aspherical collimating lens 12 can minimize aberrations by adjusting the cone constant and the aspherical coefficient, so that the light can be focused to the same point more accurately, thereby improving the collimation of the light and thus improving the imaging quality.

[0064] Furthermore, the incident surface 141 and the exit surface 143 of the turning prism 14 are aspherical surfaces for converging light, and the reflection surface 142 is a plane coated with a high-reflection film. The exit surface 143 faces the polarization beam splitter 31. The illumination light enters the turning prism 14, converges through the incident surface 141 and reaches the reflection surface 142, and then converges through the exit surface 143 and propagates to the polarization beam splitter 31 after being reflected by the reflection surface 142. The turning prism 14 can converge the light beam, diverge the focal length, and deflect the propagation direction of the light by 90°, which can effectively reduce the volume of the lighting component 1, thereby reducing the volume of the optical machine system.

[0065] In some embodiments, the microlens array 13 is preferably a compound eye microlens array. After the illumination light beam enters the microlens array 13, it can form more sub-light sources, and then after being converged by the turning prism 14, the light uniformity effect of the optical machine system can be further improved. In addition, compared with the traditional compound eye lens array, the compound eye microlens array of the present application can weaken the array image of the projection imaging coupling port, improve the door curtain effect when used in conjunction with the waveguide device, and help improve the near-eye display effect.

[0066] In some embodiments, the surface of the reflective element 32 away from the polarization splitter element 31 is aspherical, and the surface curvature radius of the aspherical reflective element 32 varies with the central axis, which can effectively eliminate the aberrations such as spherical aberration, coma and astigmatism inherent in the spherical reflector. The surface of the reflective element 32 close to the polarization splitter element 31 is a plane, which can simplify the alignment and assembly process of the optical system and reduce the additional aberrations caused by the curved surface.

[0067] In some embodiments, the inner side of the aspheric surface of the reflective element 32 away from the polarization beam splitting element 31 is coated with a reflective film layer to form a reflector, which can significantly improve the reflectivity, reduce light loss, and ensure that more light is reflected and utilized. In some embodiments, the reflective film layer material coated on the aspheric surface can be selected from aluminum, nickel-cobalt alloy, etc.

[0068] In some embodiments, the reflective element 32 is a plano-convex lens, which can focus the incident light to a point to achieve an efficient focusing effect. The convex surface of the reflective element 32 has a high-reflective film, which is suitable as a reflector to bear the main optical focal length of the optical-mechanical system. It can significantly reduce the loss of light in the reflection process and improve the luminous flux and efficiency of the system.

[0069] In some embodiments, the quarter wave plate 36 may be made of, but not limited to, PC (polycarbonate), COP (cyclic olefin polymer) or liquid crystal material. The inverse wavelength dispersion quarter wave plate 36 is designed with special materials and processes to maintain a stable phase delay in a wide wavelength range, thereby improving the performance and stability of the optical system.

[0070] In some embodiments, an absorbing second polarizer 15 is attached to the light incident side surface of the polarization beam splitting element 31 . The second polarizer 15 acts as a polarizer to change the incident light into linearly polarized light.

[0071] In some embodiments, the polarization beam splitting element 31 is formed by gluing two right-angle prisms together for polarization beam splitting, wherein the gluing surface formed by gluing the two right-angle prisms together is coated with a polarization beam splitting film 37, which is a special optical film, and its main function is to decompose the incident non-polarized light into two beams of light with different polarization directions, namely, P polarized light (parallel to the incident surface 141) and S polarized light (perpendicular to the incident surface 141). By separating the polarized light, the influence of stray light on imaging can be effectively reduced, thereby improving the contrast and clarity of the optical system. It is worth mentioning that the polarization beam splitting film 37 includes but is not limited to Wire-Grid PBS (metal wire grid polarization beam splitting film) and Cartesian PBS (Cartesian polarization beam splitting film), which can provide high extinction ratio and high contrast, and is suitable for applications with extremely high requirements for optical performance.

[0072] In some embodiments, the fourth lens 331 and the fifth lens 332 can be trimmed, that is, after the trimming process, the fourth lens 331 and the fifth lens 332 have the same surface shape and size as the polarization splitter element 31 on the side close to the display chip 2, so that the overall volume of the optical machine system is further reduced and the size of the optical machine is miniaturized.

[0073] In some embodiments, the side of the reflective element 32 close to the polarization splitter element 31 is a plane, and the side away from the polarization splitter element 31 is a convex surface. A square silk screen is provided on one side of the plane of the reflective element 32 so that the reflective element 32 forms a vignetting stop to block stray light.

[0074] In some embodiments, a compensation plate is arranged between the polarization splitter element 31 and the display chip 2. The compensation plate is arranged in the light path between the fourth lens 331 and the polarization splitter element 31, or in the light path between the fifth lens 332 and the display chip 2. It can effectively compensate for the phase difference, optimize the utilization efficiency of the polarized light, further effectively improve the display visibility, and reduce problems such as color deviation and insufficient contrast.

[0075] Furthermore, the relay imaging assembly 3 also includes a first diffuser, which is disposed between the exit surface 143 of the turning prism 14 and the second polarizer 15 , and is suitable for uniformizing the intensity distribution of the incident light and reducing the non-uniformity of the light.

[0076] In some embodiments, the first diffuser is attached to the second polarizer 15, that is, the first diffuser is close to the turning prism 14, and the second polarizer 15 is close to the polarization beam splitter 31. In addition, the first diffuser and the second polarizer 15 can also be replaced by composite films to improve the array image.

[0077] Normally, the exit pupil of the projection lens, that is, the position of the aperture stop, is conjugate with the light-emitting surface of the compound eye, that is, the illuminated image of the light-emitting surface of the compound eye will be imaged to the exit pupil position of the projection lens, which forms an array image at the exit pupil position of the projection lens, thereby affecting the waveguide imaging effect. In order to improve this problem, a diffuser can be added at any position between the compound eye and the polarization beam splitter 31. The diffuser can scatter the light passing through it, causing the imaging quality of the optical path forming the array image to drop sharply, and the entire column of images of the compound eye projected to the exit pupil position of the lens becomes blurred, thereby improving the image uniformity at the exit pupil position of the projection lens. Furthermore, the farther the diffuser is from the compound eye, the better the homogenization effect. In order to achieve the best homogenization effect, the first diffuser is preferably installed on the side of the second polarizer 15 close to the turning prism 14.

[0078] The aspheric curve equations of the first lens 341, the second lens 342, the reflective element 32, the fourth lens 331, and the fifth lens 332 of the present application are expressed as follows: . Among them, X(Y): represents the longitudinal coordinate of a point on the aspheric surface (usually in the direction of the optical axis), which is a function of the transverse coordinate Y. Y: represents the transverse coordinate of a point on the aspheric surface (usually in the direction perpendicular to the optical axis). R: represents the radius of curvature of the aspheric curve at the vertex. The larger the radius of curvature, the flatter the surface; the smaller the radius of curvature, the more curved the surface. k: represents the cone constant, which is used to describe the shape of the aspheric surface. Different k values ​​correspond to different surface types: k=0: spherical surface; k>-1: ellipsoidal surface; k=-1: paraboloid; k<-1: hyperbolic surface. sqrt: represents the square root function. Ai: represents the aspheric coefficient, which is used to describe the degree of deviation of the aspheric curve from the reference spherical curve. Yi: represents the i-th power of the transverse coordinate Y, which is used to describe the higher-order terms of the aspheric curve. ∑i(Ai)×(Yi): represents the sum of the higher-order terms of the aspheric curve, which is used to more accurately describe the shape of the aspheric surface. This equation is used to describe the surface shape of an aspheric lens. By adjusting parameters such as R, k, and Ai, the optical performance of the lens can be optimized, aberrations can be reduced, and imaging quality can be improved.

[0079] The following are specific embodiments of the optical-mechanical system of the present application.

[0080] Example 1 Optical machine system Figure 1 As shown, it includes an illumination component 1, a display chip 2, and a relay imaging component 3. The FOV (field of view) of the optical-mechanical system is 58±1°, and the F# (F number or aperture number) is 1.77.

[0081] The display chip 2 is an LCoS chip of a non-self-luminous display panel, and has a size of 0.24 inches.

[0082] The lighting assembly 1 includes a light source 11 (RGB three-color LED light source), a collimating lens 12 (aspherical collimating lens), a microlens array 13, a turning prism 14 and a second polarizer 15. The LED light source is a red, green and blue three-color combination, and the light-emitting area is less than 1.1×1.1mm. RGB (the three primary colors of light) are on one lamp and are lit in turn. The collimating lens 12 is a convex lens, and both surfaces are aspherical. The microlens array 13 is a compound eye microlens array, 13×13, and the length and width of a single compound eye unit are 0.3mm. The turning prism 14 has an incident surface 141, a reflecting surface 142 and an exit surface 143, wherein the incident surface 141 and the exit surface 143 are aspherical surfaces for converging light. The reflecting surface 142 is a plane and is coated with a high-reflection film. The turning prism 14 can converge the divergent focal length of the light beam and deflect the propagation direction of the light by 90°, which can effectively reduce the volume of the lighting system. The second polarizer 15 serves as a polarizer to convert incident light into linearly polarized light.

[0083] The relay imaging assembly 3 includes a polarization splitter element 31 , a reflective element 32 , a fourth lens 331 , a fifth lens 332 , a first lens 341 , a second lens 342 , a first polarizer 35 , a quarter wave plate 36 and a polarization splitter film 37 . Figure 1 In the figure, the first lens 341 is a positive lens; the second lens 342 is a negative lens, whose side close to the light-emitting side is concave, and the side away from the light-emitting side is flat; the first polarizer 35 is an absorption-type linear polarizer, which is glued between the second lens 342 and the polarization beam splitter 31; the polarization beam splitter 31 is composed of two right-angle prisms glued together; the reflective element 32 is a plano-convex lens, and the convex surface is coated with a high-reflection film. The quarter-wave plate 36 is glued between the reflective element 32 and the polarization beam splitter 31. The fourth lens 331 and the fifth lens 332 form a double-cemented lens for correcting chromatic aberration. Among them, the fourth lens 331 is a positive lens, and the surface close to the polarization beam splitter 31 is aspherical, with a low refractive index and a high Abbe number; the fifth lens 332 is a negative lens, with a high refractive index and a low Abbe number.

[0084] Table 1 shows the specific parameters of each lens in the relay imaging component 3. In Table 1, the surface 1 of the first lens 341 is a convex surface away from the polarization beam splitter 31, and the surface 2 is a convex surface close to the polarization beam splitter 31; the surface 3 of the second lens 342 is a concave surface close to the light-emitting side, and the surface 4 is a plane away from the light-emitting side; the surface 5 of the polarization beam splitter 31 is an inclined surface close to the reflective element 32, and the surface 6 is an inclined surface close to the display chip 2; the surface 7 of the reflective element 32 is an aspheric surface away from the polarization beam splitter 31, and the surface 8 is a plane close to the polarization beam splitter 31; the surface 9 of the fourth lens 331 is a convex surface away from the display chip 2, and the surface 10 is a convex surface close to the display chip 2; the surface 11 of the fifth lens 332 is a concave surface away from the display chip 2, and the surface 12 is a convex surface close to the display chip 2.

[0085] Table 1

[0086] As shown in Table 2 below, the aspheric coefficients of the aspheric curve equations of surface 7 and surface 9 are specifically shown, where K represents the quadratic surface coefficient, which is used to describe the basic deviation of the optical surface from the ideal sphere; A4, A6, A8, A10, and A12 represent high-order aspheric coefficients, which are used to describe the complex shape deviation of the optical surface.

[0087] Table 2

[0088] The focal length f of the lens of the optical-mechanical system of this embodiment is 6.08 mm. The focal length f of the lens is equal to the focal length f of the reflective element 32. 3 The ratio is 0.6<f / f 3 <1; The combined focal length of the first lens 341 and the second lens 342 is 106.2mm, and the combined optical focal length is very small, and the contribution to the optical focal length of the optical-mechanical system is very small; The combined focal length of the fourth lens 331 and the fifth lens 332 is 12.46mm, and the fourth lens 331 and the fifth lens 332 are close to the image plane, and mainly play the role of field lenses, and the contribution to the optical focal length is small. The optical focal length of the optical-mechanical system of this embodiment is mainly contributed by the reflective element 32.

[0089] The light path of the optical-mechanical system of this embodiment is as follows: after the light is emitted from the light source 11 (LED), it passes through the single-chip collimating lens 12 for light beam collimation. After the collimated light beam passes through the microlens array 13 for light homogenization, it enters the polarization beam splitter element 31 after passing through the turning prism 14, and enters the cemented lens composed of the fourth lens 331 and the fifth lens 332, forming a square uniform illumination pattern to illuminate the display area of ​​the display chip 2 (LCoS). Specifically, after the homogenization, the light enters the turning prism 14, is deflected by 90 degrees, and becomes the first polarized light (exemplarily, it can be s-polarized light) through the second polarizer 15 between the turning prism 14 and the polarization splitter element 31. The first polarized light enters the polarization splitter element 31, is reflected on the splitting surface of the polarization splitter element 31, passes through the cemented lens composed of the fourth lens 331 and the fifth lens 332, and is incident on the LCoS. The first polarized light is modulated and reflected by the LCoS and converted into the second polarized light (exemplarily, it can be p-polarized light). The second polarized light enters the polarization splitter element 31 again and passes through the splitting surface of the polarization splitter element 31 and is converted into the third polarized light (exemplarily, it can be circularly polarized light) through the quarter wave plate 36. The third polarized light is reflected by the reflective element 32 and then passes through the quarter wave plate 36 again and is converted into the fourth polarized light (exemplarily, it can be s-polarized light) and enters the polarization splitter element 31. It is reflected on the splitting surface of the polarization splitter element 31 and passes through the first lens 341 and the second lens 342 to the output end.

[0090] Table 3 below shows the optical efficiency and intensity uniformity data of this embodiment obtained through non-sequential ray tracing simulation using the simulation software (LightTools). These are theoretical values ​​without considering manufacturing tolerances. The table lists the design values ​​of optical efficiency and intensity uniformity under different color channels, providing a theoretical basis for the performance evaluation of the optomechanical system under different colors of light.

[0091] Table 3

[0092] Attached Figure 2 , 3 , 4 are the MTF diagrams of red, green, and blue light of the optomechanical system, respectively. The MTF diagrams of red, green, and blue light provide the imaging quality information of the optical system at different wavelengths. The optomechanical system of the present application realizes a projection lens design with a FOV of 58°. At the same time, at 166lp / mm, under red, green, and blue light, the MTF (modulation transfer function) is greater than 50%. Therefore, the optomechanical system provided in Example 1 of the present application has a higher optomechanical lens resolution, can resolve finer image details, helps to improve imaging quality, resolution, and color performance, and meets the needs of a variety of high-precision imaging applications.

[0093] Attached Figure 5The vertical axis chromatic aberration diagram of Example 1 shows the vertical offset of light of different wavelengths (colors) on the image plane after passing through the optical system. As the field of view increases, the curve of the vertical axis chromatic aberration diagram approaches 0mm, and the vertical axis chromatic aberration is less than 3μm, indicating that in Example 1 of the present application, as the field of view of the full-color optical machine system increases, the focus position difference of light of different wavelengths on the image plane gradually decreases, resulting in better chromatic aberration correction effect and high imaging quality.

[0094] like Figure 6 The figure shows the LCoS illumination result of the optical-mechanical system. The light intensity ranges from 1.4E+05 to 7E+05, and the light intensity gradually decreases from the center to the edge. The light intensity in the center is the highest at 7E+05, and the light intensity in the edge is the lowest at 1.4E+05. The illumination of the LCoS center light reaches a relatively high level. Figure 7 The figure shows the distribution of the optical projection intensity of the optical system. The brightness uniformity of the optical projection is greater than 65%, the overall luminous efficiency is greater than 10lm / w, and the length, width and height of the optical machine are less than 1.71cc, which effectively shortens the size of the optical system and is more convenient for integration.

[0095] Example 2 The difference between Example 2 and Example 1 is that: The first lens 341 is made of plastic, and the optical parameters of each lens (curvature radius, thickness, refractive index, Abbe number, focal length) are shown in Table 4 below.

[0096] Table 4

[0097] As shown in Table 5 below, the aspheric coefficients of the aspheric curve equations of surface 1, surface 2, surface 7 and surface 9 are specifically shown, where K determines the basic shape of the surface, and the high-order aspheric coefficients (A4, A6, A8, A10, A12) are used to further optimize the surface shape and correct aberrations.

[0098] Table 5

[0099] The focal length f of the lens of the optical-mechanical system of this embodiment is 5.98 mm. The focal length f of the lens is equal to the focal length f of the reflective element 32. 3 The ratio is 0.6<f / f 3 <1; The combined focal length of the first lens 341 and the second lens 342 is 103.4mm, and the combined optical focal length is very small, and the contribution to the optical focal length of the optical-mechanical system is very small; The combined focal length of the fourth lens 331 and the fifth lens 332 is 12.21mm, and the fourth lens 331 and the fifth lens 332 are close to the image plane, and mainly play the role of field lenses, and the contribution to the optical focal length is small. The optical focal length of the optical-mechanical system of this embodiment is mainly contributed by the reflective element 32.

[0100] like Figure 8 , 9 As shown in Figures 10 and 11, the optical-mechanical system in this embodiment realizes a wide-angle image projection with a FOV greater than 58°, and at 166lp / mm, the MTF (modulation transfer function) is also greater than 50% under red, green and blue light. Therefore, the optical-mechanical system provided in Example 2 of the present application can also realize the requirement of further improving the optical-mechanical resolution to 167lp / mm.

[0101] like Fig.11 As shown, as the field of view angle increases, the curve approaches 0mm, and the vertical axis chromatic aberration is less than 3μm, indicating that in Example 2 of the present application, as the field of view angle of the optical-mechanical system increases, the difference in the focusing position of light of different wavelengths on the image plane gradually decreases, resulting in better chromatic aberration correction effect and high imaging quality.

[0102] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that: like Fig.12 As shown, the first correction lens group 33 and the second correction lens group 34 in Comparative Example 1 are both replaced by an integral lens. Since the integral lens is usually made of a single material, the chromatic aberration cannot be offset by the combination of materials. Therefore, the chromatic aberration of the integral lens is mainly determined by the dispersion characteristics of the material, and it is therefore difficult to correct the chromatic aberration by design adjustment.

[0103] like Fig.13 As shown, for the design specification of large field of view (FOV>50°), the optical-mechanical system in comparative example 1 relies only on the reflective element 32, and it is difficult to achieve chromatic aberration correction of the lens. The figure shows that the vertical axis chromatic aberration of the non-cemented mirror system is greater than 25μm, which is much larger than the pixel size, which has a great impact on the imaging quality of the optical-mechanical system.

[0104] The above describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited by the above embodiments, and the above embodiments and the specification only describe the principles of the present application. The present application may have various changes and improvements without departing from the spirit and scope of the present application, and these changes and improvements fall within the scope of the present application for which protection is sought. The scope of protection claimed by the present application is defined by the attached claims and their equivalents.

Claims

1. An optical-mechanical system, characterized in that: include: The lighting assembly comprises a light source and a turning prism, wherein the light source is used to provide lighting light, and the turning prism has an incident surface facing the light source, a reflection surface and an exit surface facing the polarization beam splitting element, and is used to deflect the lighting light; A display chip, used to modulate illumination light into image light; The relay imaging component includes the polarization beam splitter element, a first corrective lens group and a reflective element, wherein the display chip and the reflective element are arranged on opposite sides of the polarization beam splitter element, and the display chip and the turning prism are arranged on adjacent sides of the polarization beam splitter element, the first corrective lens group is arranged between the polarization beam splitter element and the display chip, the first corrective lens group includes a glued fourth lens and a fifth lens, the fourth lens with positive optical focal length is arranged on a side close to the polarization beam splitter element, and the fifth lens with negative optical focal length is arranged on a side close to the display chip; the reflective element has positive optical focal length, and the focal length f3 of the reflective element and the focal length f of the optical-mechanical system satisfy: 0.6<f / f3<1.

2. The optical-mechanical system according to claim 1, characterized in that: The side of the reflective element away from the polarization beam splitting element is an aspherical surface, the inner side of the aspherical surface is coated with a reflective film, and the side of the reflective element close to the polarization beam splitting element is a plane.

3. The optical-mechanical system according to claim 1, wherein: A refractive index of the fourth lens is smaller than a refractive index of the fifth lens, and an Abbe number of the fourth lens is larger than an Abbe number of the fifth lens.

4. The optical-mechanical system according to claim 1, wherein: Both side surfaces of the fourth lens are convex surfaces. The surface of the fifth lens away from the display chip is concave, and the surface close to the display chip is convex.

5. The optical-mechanical system according to any one of claims 1 to 4, characterized in that: The relay imaging assembly also includes a second corrective lens group arranged on the light-emitting side of the polarization splitter element, the second corrective lens group includes a first lens with positive optical power and a second lens with negative optical power, the first lens is arranged on a side away from the polarization splitter element, and the second lens is arranged on a side close to the polarization splitter element.

6. The optical-mechanical system according to claim 5, characterized in that: A refractive index of the first lens is smaller than a refractive index of the second lens, and an Abbe number of the first lens is smaller than an Abbe number of the second lens.

7. The optical-mechanical system according to claim 5, characterized in that: Both side surfaces of the first lens are convex surfaces, the side of the second lens close to the light-emitting side is concave, and the side away from the light-emitting side is a flat surface.

8. The optical-mechanical system according to claim 5, characterized in that: The first lens is cemented with the second lens.

9. The optical-mechanical system according to claim 5, characterized in that: The relay imaging assembly also includes a first polarizer and a quarter wave plate. The first polarizer is arranged on the light-emitting side of the polarization splitter element and is located between the second lens and the polarization splitter element; the quarter wave plate is arranged between the reflective element and the polarization splitter element.

10. The optical-mechanical system according to claim 1, wherein: The lighting assembly further includes a second polarizer, which is arranged between the exit surface of the turning prism and the polarization beam splitting element.

11. The optical-mechanical system according to claim 10, characterized in that: The relay imaging assembly further includes a first diffuser, which is disposed between the exit surface of the turning prism and the second polarizer.

12. A near-eye display device, characterized in that: It comprises the optomechanical system and waveguide device according to any one of claims 1 to 11, wherein the optomechanical system is arranged on the coupling-in side of the waveguide device and is used to project the image light to the coupling-in port of the waveguide device.

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