Optical-mechanical systems and near-eye display devices

Abstract

This application discloses an optical-mechanical system and a near-eye display device, comprising: an illumination assembly including a light source and a turning prism; a display chip; a relay imaging assembly including a polarization beam splitter, a first corrective lens group, and a reflective element. The display chip and the reflective element are disposed on opposite sides of the polarization beam splitter, and the display chip and the turning prism are disposed on adjacent sides of the polarization beam splitter. The first corrective lens group is disposed between the polarization beam splitter and the display chip. The first corrective lens group includes a cemented fourth lens and a fifth lens. The fourth lens, having positive optical power, is disposed on the side proximal to the polarization beam splitter, and the fifth lens, having negative optical power, is disposed on the side proximal to the display chip. The reflective element has positive optical power, and the focal length f3 of the reflective element satisfies the following relationship with the focal length f of the optical-mechanical system: 0.6 < f / f3 < 1. This application aims to achieve a wide-angle, high-resolution full-color optical-mechanical system while maintaining a compact lens size.

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] The rapid development of AR display technology has led to higher requirements for display devices' field of view (FOV), resolution, brightness, and compactness. Liquid crystal on silicon (LCoS)-based AR display technology, with its advantages of high resolution, high brightness, low cost, and full-color display, has become the preferred solution for AR optical machine manufacturers and demonstrates significant development potential. However, existing LCoS optical machines typically have a relatively small FOV of only around 20-40°. While this meets the needs of enterprise applications, it lacks immersion in consumer applications, hindering the user experience.

[0003] As silicon carbide-based optical waveguide technology matures, diffractive waveguides can now achieve a FOV exceeding 70°. Furthermore, the advancement of LCoS display technology has enabled higher resolutions within the same display area, making wide-viewing-angle, high-resolution, and highly immersive AR displays possible.

[0004] However, to match the waveguide, the AR optical engine's aperture stop must be placed at the very front of the lens. In this case, the aperture stop coincides with the lens' exit pupil, whose exit pupil diameter (EPD) is typically 2-4mm. Since the F-number is proportional to the focal length f', this leads to a rapid decrease in the lens's F-number while maintaining the same EPD size. This leads to the demand for higher resolution at a smaller F-number. Therefore, the demands for a large FOV, high resolution, and miniaturization pose challenges to full-color AR optical engine design. Summary of the Invention

[0005] One purpose of this 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 machine system while reducing the chromatic aberration produced in the optical machine system.

[0008] To achieve the above objectives, the technical solution adopted in this application is: an optical-mechanical system, comprising:

[0009] An illumination assembly comprising a light source and a turning prism, wherein the light source is used to provide illumination 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 illumination light;

[0010] A display chip, used to modulate illumination light into image light;

[0011] The relay imaging assembly includes the polarization splitter element, a first corrective lens group and a reflective element, the display chip and the reflective element are arranged on opposite sides of the polarization splitter element, and the display chip and the turning prism are arranged on adjacent sides of the polarization splitter element, the first corrective lens group is arranged between the polarization 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 power is arranged on the side close to the polarization splitter element, and the fifth lens with negative optical power is arranged on the side close to the display chip; the reflective element has positive optical power, 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.

[0012] Preferably, a surface of the reflective element away from the polarization beam splitting element is an aspheric surface, an inner side of the aspheric surface is coated with a reflective film, and a surface of the reflective element close to the polarization beam splitting element is a plane.

[0013] Preferably, the refractive index of the fourth lens is smaller than that of the fifth lens, and the Abbe number of the fourth lens is larger than that of the fifth lens.

[0014] 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.

[0015] As a preference, 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 including a first lens with positive optical power and a second lens with negative optical power, the first lens being arranged on a side away from the polarization splitter element, and the second lens being arranged on a side close to the polarization splitter element.

[0016] As a preference, the refractive index of the first lens is smaller than the refractive index of the second lens, and the Abbe number of the first lens is smaller than the Abbe number of the second lens.

[0017] Preferably, both side surfaces of the first lens are convex, and the side of the second lens close to the light-emitting side is concave, and the side away from the light-emitting side is flat.

[0018] As a preference, the first lens and the second lens are glued together.

[0019] As a preference, the relay imaging assembly further includes a first polarizer and a quarter-wave plate, wherein 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.

[0020] Preferably, the lighting assembly further includes a second polarizer, and the second polarizer is arranged between the exit surface of the turning prism and the polarization beam splitting element.

[0021] Preferably, the relay imaging assembly further includes a first diffuser, which is arranged between the exit surface of the turning prism and the second polarizer.

[0022] As a preferred embodiment, 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.

[0023] Compared with the existing technology, the advantages of this application are as follows: In the optical machine system provided by this application, the reflective element can bear the main optical focal length, achieving the short focal length required for the optical machine system at a large angle, ensuring that a wide field of view can be provided; at the same time, by providing a corrective lens group, the aberration and chromatic aberration caused by the increased field of view can be corrected, thereby realizing a high-definition full-color AR optical machine; the reuse of the reflective element, the turning prism, and the corrective lens group can reduce the size of the optical machine. In this way, a large FOV, high resolution, and miniaturized full-color AR optical machine can be realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of the structure of the optical-mechanical system in an embodiment of the present application.

[0025] Figure 2 This is the green light MTF diagram of the optical-mechanical system in Example 1 of the present application.

[0026] Figure 3 This is the red light MTF diagram of the optical-mechanical system in Example 1 of the present application.

[0027] Figure 4 This is the blue light MTF diagram of the optical-mechanical system in Example 1 of the present application.

[0028] Figure 5 This is a diagram of vertical axis chromatic aberration of the optical-mechanical system in Example 1 of the present application.

[0029] Figure 6 This is the LCoS illumination diagram of the optical-mechanical system in Example 1 of the present application.

[0030] Figure 7This is the projection intensity distribution diagram of the optical-mechanical system in Example 1 of the present application.

[0031] Figure 8 This is the green light MTF diagram of the optical-mechanical system in Example 2 of this application.

[0032] Figure 9 This is the red light MTF diagram of the optical-mechanical system in Example 2 of this application.

[0033] Figure 10 This is the blue light MTF diagram of the optical-mechanical system in Example 2 of this application.

[0034] Figure 11 This is a diagram of vertical axis chromatic aberration of the optical-mechanical system in Example 2 of the present application.

[0035] Figure 12 Schematic diagram of the optical-mechanical system in the comparative example (the lighting component is not shown).

[0036] Figure 13 This is the vertical axis chromatic aberration diagram of the optical mechanical system in the comparative example.

[0037] In the figure: 1. Illumination component; 11. Light source; 12. Collimating lens; 13. Microlens array; 14. Turning prism; 141. Incident surface; 142. Reflection surface; 143. Exit surface; 15. Second polarizer; 2. Display chip; 3. Relay imaging component; 31. Polarization splitter element; 32. Reflection 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 splitter film. DETAILED DESCRIPTION

[0038] 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.

[0039] In the description of this application, it should be noted that for directional words, such as the terms "center", "horizontal", "longitudinal", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and so on, indicating the orientation and position relationship are based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and cannot be understood as limiting the specific scope of protection of this application.

[0040] It should be noted that the terms "first", "second", etc. in the description and claims of this application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0041] The terms "comprises" 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 that includes a series of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, product or apparatus.

[0042] like Figure 1 As shown, the optical-mechanical system of the present application includes an illumination assembly 1, a display chip 2, and a relay imaging assembly 3. The illumination assembly 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 assembly 3 is correspondingly arranged in the optical path between the illumination assembly 1 and the display chip 2, and is used to transmit the illumination light provided by the illumination assembly 1 to the display chip 2 and perform imaging projection on the image light modulated by the display chip 2.

[0043] like Figure 1 As shown, the relay imaging assembly 3 includes a polarization beam splitter element 31 and a reflective element 32. The display chip 2 and the reflective element 32 are disposed on opposite sides of the polarization beam splitter element 31, and the display chip 2 and the turning prism 14 are disposed 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-entering 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 then reflects back 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 reenters the polarization beam splitter element 31 and is refracted by the polarization beam splitter element 31 before being emitted from the light-exiting side.

[0044] It is worth mentioning that the reflective element 32 has positive optical focal length, and the focal length f3 of the reflective element 32 and the focal length f of the optical-mechanical system satisfy the following relationship: 0.6<f / f3<1. From the relationship between f3 and f, it can be seen that the reflective element 32 is used to bear the main optical focal length of the optical-mechanical system, to achieve the short focal length required for large angles, and to 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 full-color projection lenses. Based on this, the relay imaging component 3 of the present application also includes a first corrective lens group 33 for correcting system chromatic aberration and other residual aberrations.

[0045] In some embodiments, a first corrective lens group 33 is disposed between the display chip 2 and the polarization beam splitter 31. The first corrective lens group 33 includes a fourth lens 331 having positive optical power and a fifth lens 332 having negative optical power. The fourth lens 331 and the fifth lens 332 can be cemented together. The positive optical power of the fourth lens 331 typically produces negative chromatic aberration, while the negative optical power of the fifth lens 332 typically produces positive chromatic aberration. Optimizing the optical power ratio of the fourth lens 331 and the fifth lens 332 can offset the negative chromatic aberration of the positive lens and the positive chromatic aberration of the negative lens, thereby significantly reducing chromatic aberration. Furthermore, adjusting the shape and position of the fourth lens 331 and the fifth lens 332 can effectively correct the aberrations of the optical-mechanical system.

[0046] Furthermore, the fourth lens 331 is positioned near the polarization beam splitter 31, and the fifth lens 332 is positioned near the display chip 2. Light emitted by the illumination assembly 1 is refracted by the polarization beam splitter 31 before reaching the display chip 2. The light is then converged and diverged by the fourth lens 331 and the fifth lens 332. The light undergoes chromatic aberration and aberration correction to better meet the imaging requirements of the display chip 2, resulting in a higher-quality image with more saturated colors and higher contrast on the display screen.

[0047] In some embodiments, the fourth lens 331 has a lower refractive index than the fifth lens 332, and the fourth lens 331 has a greater Abbe number than 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, light is more significantly refracted upon entering the higher-refractive-index fifth lens 332, thereby changing the direction of light propagation and focusing the light on the display chip 2 to form a clearer and more uniform image. The high Abbe number material used for the fourth lens 331 significantly reduces chromatic aberration, allowing light of different wavelengths to be more closely focused on the same point. The low Abbe number of the fifth lens 332 further adjusts the focusing characteristics of the light. This combination of high and low Abbe numbers effectively corrects chromatic aberration in the optical system.

[0048] Furthermore, both sides of the fourth lens element 331, which has positive power, have convex surfaces, helping to converge light, ensuring that it is fully focused on the fifth lens element 332. The fifth lens element 332, which has negative power, has a concave surface facing away from the display chip 2 and a convex surface facing closer to the display chip 2. The combination of the concave and convex surfaces of the fifth lens element 332 helps optimize the distribution of light on the display chip 2, thereby improving the display chip 2's utilization of light from the fourth and fifth lenses 331, 332. Furthermore, the surface of the fourth lens element 331, which is closer to the polarization beam splitter 31, is aspherical, converging light to a more precise focus, reducing blur and enhancing image clarity and sharpness.

[0049] Furthermore, the relay imaging assembly 3 of the present application also includes a second corrective lens group 34 disposed on the light-exiting side of the polarization beam splitter 31 to further reduce chromatic aberration and residual aberration in the system. It is worth noting that the light-exiting side and light-incoming side of the polarization beam splitter 31 are disposed opposite each other. In the present application, the first corrective lens group 33 is disposed at the position where the image light just emerges from the display chip 2, and the second corrective lens group 34 is disposed at the final exit position of the image light. By placing corrective lens groups at these two positions, the chromatic aberration and aberration of the full-color optical system can be more effectively reduced.

[0050] 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 after 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.

[0051] Furthermore, the second corrective 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 positioned away from the polarization beam splitter 31, and the second lens 342 is positioned closer to the polarization beam splitter 31. The image light passing through the second corrective lens group 34 can effectively remove chromatic aberration and aberration, thereby optimizing image quality.

[0052] In some embodiments, the refractive index of the first lens 341 is lower than that of the second lens 342, and the Abbe number of the first lens 341 is lower than that of the second lens 342. The first lens 341, with its lower refractive index, typically has weaker light focusing ability, while the second lens 342, with its higher refractive index, has stronger focusing ability. By properly pairing the first lens 341 and the second lens 342, better light control can be achieved at different wavelengths, optimizing the overall optical performance of the system. The combination of the low-Abbe-number first lens 341 and the high-Abbe-number second lens 342 can effectively correct chromatic aberration, reduce color halos or blurring, and significantly improve the imaging quality of the optical system.

[0053] Furthermore, both side surfaces of the first lens 341 with positive optical power are convex, and the second lens 342 with negative optical power has a concave surface on the side close to the light-emitting side and a flat surface on the side away from the light-emitting side. The divergent effect of the second lens 342 with negative optical power can cooperate with the convergent effect of the first lens 341 with positive optical 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 31 enters the combined lens of the first lens 341 and the second lens 342 after being refracted by the polarization beam splitter 31. The flat surface of the second lens 342 with negative optical 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 optical power, both sides of which are convex, to converge, and finally outputs image light with uniform brightness and high clarity from the light-emitting side.

[0054] The first and second corrective lens groups 33 and 34 are primarily used to improve dispersion and aberrations. The two lenses in the first corrective lens group 33 are very close to the image plane, acting as a field lens and not contributing significantly to the optical power. The combined optical power of the two lenses in the second corrective lens group 34 is very low, contributing little to the system's optical power. Therefore, the optical power of the optical machine system is primarily borne by the reflective element 32.

[0055] In some embodiments, the first corrective lens group 33 is formed by gluing a fourth lens 331 and a fifth lens 332 together to form a doublet lens. By optimizing the curvature radius and shape of the fourth lens 331 and the fifth lens 332, 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 doublet lens can change the optical path of light through the lens, thereby correcting the aberration.

[0056] 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.

[0057] In some embodiments, the bonding material may be photosensitive glue, UV curing adhesive, optical epoxy resin glue, etc.

[0058] Similarly, the second corrective lens group 34 is formed by cementing a first lens 341 and a second lens 342 together to form a doublet lens.

[0059] Furthermore, the relay imaging assembly 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 is located between the second lens 342 and the polarization beam splitter 31. It can selectively pass light of a specific polarization direction, reduce interference from stray light and reflected light, and protect subsequent optical components. 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. It can cause the incident light to produce a phase delay of a quarter wavelength in a specific direction, converting linearly polarized light into circularly polarized light, or vice versa.

[0060] In some embodiments, the first polarizer 35 is an absorbing linear polarizer, which is disposed in the light path between the second lens 342 and the polarization splitter 31 and attached to the polarization splitter 31 to absorb the outgoing stray light and improve the optical-mechanical contrast.

[0061] Furthermore, the lighting assembly 1 also includes a second polarizer 15, which is arranged between the exit surface 143 of the turning prism 14 and the polarization splitter element 31, ensuring that the light emitted from the exit surface 143 of the turning prism 14 has a uniform polarization direction, providing consistent polarized light for the polarization splitter element 31.

[0062] 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.

[0063] The illumination light passes through the second polarizer 15 and becomes first polarized light (exemplarily, s-polarized light). The first polarized light is reflected by the polarization splitter 31 and enters the first corrective lens group 33. After being emitted from the first corrective lens group 33, it enters the display chip 2 and is modulated by the display chip 2 to form second polarized light (exemplarily, p-polarized light). The second polarized light then passes through the first corrective lens group 33 and the polarization splitter 31 again to reach the quarter-wave plate 36. After adjustment by the quarter-wave plate 36, it is converted into third polarized light (exemplarily, circularly polarized light). 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 fourth polarized light (exemplarily, s-polarized light). The fourth polarized light then passes through the polarization splitter 31 again, is emitted, and enters the second corrective lens group 34 from the light output side. After chromatic aberration correction, the image is output.

[0064] Furthermore, the lighting assembly 1 also includes a collimating lens 12 and a microlens array 13, which are arranged in sequence 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.

[0065] Furthermore, light source 11 can be a three-in-one LED with a single-path illumination design, which reduces the space occupied by light source 11 within the illumination assembly 1 and reduces the size of the optical machine. Furthermore, the optical machine system can reuse the doublet lens consisting of the fourth lens 331 and the fifth lens 332 in the imaging lens, further reducing the size of the optical machine. This combined design of the illumination assembly 1, the relay imaging assembly 3, the display chip 2, and other components allows for miniaturization of the optical machine while ensuring uniform illumination.

[0066] Furthermore, both side surfaces of the collimating lens 12 are aspherical. The aspheric collimating lens 12 can minimize aberration by adjusting the cone constant and the aspheric 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.

[0067] Furthermore, the incident surface 141 and the exit surface 143 of the turning prism 14 are aspherical surfaces for converging light, and the reflective surface 142 is flat and coated with a high-reflection film. The exit surface 143 faces the polarization beam splitter 31. The illumination light enters the turning prism 14, is converged by the incident surface 141, and then reaches the reflective surface 142. After being reflected by the reflective surface 142, it is converged by the exit surface 143 and propagates to the polarization beam splitter 31. The turning prism 14 can converge the light beam, diverge the focal length, and deflect the light propagation direction by 90°, which can effectively reduce the volume of the lighting assembly 1, thereby reducing the volume of the optical machine system.

[0068] In some embodiments, the microlens array 13 is preferably a fly-eye microlens array. After the illumination beam enters the microlens array 13, it can form more sub-light sources. Furthermore, after being converged by the turning prism 14, the uniform light effect of the optical-mechanical system can be further improved. Furthermore, compared to traditional fly-eye lens arrays, the fly-eye microlens array of the present application can reduce the array image at the projection imaging coupling port, improve the door curtain effect that occurs when used in conjunction with waveguide devices, and help improve near-eye display effects.

[0069] 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 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 flat, which can simplify the alignment and assembly process of the optical system and reduce additional aberrations caused by the curved surface.

[0070] In some embodiments, the inner side of the aspheric surface of reflective element 32, away from polarization beam splitter 31, is coated with a reflective film to form a reflector. This significantly improves reflectivity, reduces light loss, and ensures that more light is reflected and utilized. In some embodiments, the reflective film on the aspheric surface can be made of aluminum, nickel-cobalt alloy, or the like.

[0071] 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, and can significantly reduce the loss of light in the reflection process, thereby improving the luminous flux and efficiency of the system.

[0072] 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. The inverse wavelength dispersion quarter-wave plate 36 is designed with special materials and processes to maintain stable phase delay over a wide wavelength range, thereby improving the performance and stability of the optical system.

[0073] 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 convert the incident light into linearly polarized light.

[0074] In some embodiments, the polarization beam splitter element 31 is formed by gluing two right-angle prisms together for polarization beam splitting. The gluing surface formed by the two right-angle prisms is coated with a polarization beam splitter film 37. The polarization beam splitter film 37 is a special optical film whose primary function is to decompose incident unpolarized light into two beams of light with different polarization directions: 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 effect of stray light on imaging can be effectively reduced, thereby improving the contrast and clarity of the optical system. It is worth noting that the polarization beam splitter film 37 includes but is not limited to wire-grid PBS (metal wire grid polarization beam splitter film) and Cartesian PBS (Cartesian polarization beam splitter film), which can provide high extinction ratio and high contrast, making it suitable for applications with extremely high optical performance requirements.

[0075] 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.

[0076] In some embodiments, the side of the reflective element 32 close to the polarization splitter element 31 is flat, and the side away from the polarization splitter element 31 is convex. A square silk screen is provided on one side of the flat surface of the reflective element 32 so that the reflective element 32 forms a vignetting stop to block stray light.

[0077] 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 optical path between the fourth lens 331 and the polarization splitter element 31, or in the optical path between the fifth lens 332 and the display chip 2. It can effectively compensate for the phase difference, optimize the utilization efficiency of polarized light, further effectively improve the display visibility, and reduce problems such as color deviation and insufficient contrast.

[0078] Furthermore, the relay imaging assembly 3 further includes a first diffuser, which is disposed between the exit surface 143 of the turning prism 14 and the second polarizer 15 . The first diffuser is suitable for uniformizing the intensity distribution of the incident light and reducing light inhomogeneity.

[0079] In some embodiments, the first diffuser is attached to the second polarizer 15, that is, the first diffuser is attached to the side close to the turning prism 14, and the second polarizer 15 is attached to the side close to the polarization beam splitter 31. In addition, the first diffuser and the second polarizer 15 can also be replaced with composite films to improve the array image.

[0080] Normally, the exit pupil of the projection lens, that is, the position of the aperture stop, is conjugate with the light-exiting surface of the compound eye. That is, the illuminated image of the light-exiting 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 splitter element 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 compound eye images 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.

[0081] 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:

[0082] . 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: sphere; k>-1: ellipsoid; k=-1: parabola; k<-1: hyperboloid. 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.

[0083] The following are specific embodiments of the optical-mechanical system of the present application.

[0084] Example 1

[0085] Optical machine system Figure 1 As shown, it includes an illumination component 1, a display chip 2, and a relay imaging component 3. The optical-mechanical system has a FOV (field of view) of 58±1° and an F# (F-number or aperture number) of 1.77.

[0086] The display chip 2 is an LCoS chip of a non-self-luminous display panel, and has a size of 0.24 inches.

[0087] The lighting assembly 1 includes a light source 11 (an LED light source that combines RGB colors), a collimating lens 12 (an aspherical collimating lens), a microlens array 13, a turning prism 14, and a second polarizer 15. The LED light source combines red, green, and blue (RGB) colors, with a light-emitting area smaller than 1.1 x 1.1 mm. The three primary colors of light (RGB) are illuminated in a single lamp, each illuminating in turn. The collimating lens 12 is a convex lens with both surfaces aspherical. The microlens array 13 is a 13 x 13 micro-lens array, with a single compound-eye unit measuring 0.3 mm in length and width. The turning prism 14 has an incident surface 141, a reflecting surface 142, and an exit surface 143. The incident and exit surfaces 141 and 143 are aspherical surfaces, converging the light. The reflecting surface 142 is flat and coated with a high-reflection coating. The turning prism 14 can converge the light beam, diverge the focal length, and deflect the light propagation direction by 90°, effectively reducing the size of the lighting system. The second polarizer 15 acts as a polarizer to convert the incident light into linearly polarized light.

[0088] The relay imaging assembly 3 includes a polarization splitting 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 splitting film 37 . Figure 1 In the figure, the first lens 341 is a positive lens; the second lens 342 is a negative lens, with a concave surface close to the light-emitting side and a flat surface away from the light-emitting side; the first polarizer 35 is an absorbing linear polarizer, cemented between the second lens 342 and the polarization beam splitter 31; the polarization beam splitter 31 is composed of two right-angle prisms cemented together; the reflective element 32 is a plano-convex lens, with the convex surface coated with a high-reflection film. The quarter-wave plate 36 is cemented between the reflective element 32 and the polarization beam splitter 31. The fourth lens 331 and the fifth lens 332 form a doublet lens for correcting chromatic aberration. The fourth lens 331 is a positive lens, with an aspheric surface close to the polarization beam splitter 31, 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.

[0089] Table 1 shows the specific parameters of each lens in the relay imaging assembly 3. In Table 1, surface 1 of the first lens 341 is a convex surface on the side away from the polarization splitter element 31, and surface 2 is a convex surface on the side close to the polarization splitter element 31. Surface 3 of the second lens 342 is a concave surface close to the light-emitting side, and surface 4 is a flat surface away from the light-emitting side. Surface 5 of the polarization splitter element 31 is an inclined surface close to the reflective element 32, and surface 6 is an inclined surface close to the display chip 2. Surface 7 of the reflective element 32 is an aspheric surface on the side away from the polarization splitter element 31, and surface 8 is a flat surface close to the polarization splitter element 31. Surface 9 of the fourth lens 331 is a convex surface on the side away from the display chip 2, and surface 10 is a convex surface close to the display chip 2. Surface 11 of the fifth lens 332 is a concave surface on the side away from the display chip 2, and surface 12 is a convex surface close to the display chip 2.

[0090] Table 1

[0091]

[0092] As shown in Table 2 below, the aspheric coefficients of the aspheric curve equations of surfaces 7 and 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.

[0093] Table 2

[0094]

[0095] The focal length f of the lens of the optical-mechanical system of this embodiment is 6.08 mm, and the ratio of the focal length f of the lens to the focal length f3 of the reflective element 32 is 0.6<f / f3<1; the combined focal length of the first lens 341 and the second lens 342 is 106.2 mm, 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 12.46 mm, 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 contribute little to the optical focal length. The optical focal length of the optical-mechanical system of this embodiment is mainly contributed by the reflective element 32.

[0096] The light path of the optical-mechanical system of this embodiment is as follows: after being emitted from the light source 11 (LED), the light beam is collimated by the single-chip collimating lens 12. The collimated light beam is homogenized by the microlens array 13, passes through the turning prism 14, enters the polarization beam splitter 31, and then enters the cemented lens composed of the fourth lens 331 and the fifth lens 332, forming a square uniform illumination pattern, illuminating the display area of ​​the display chip 2 (LCoS). Specifically, after homogenization, the light enters the turning prism 14, is deflected 90°, and becomes first polarized light (exemplarily, s-polarized light) after passing 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 second polarized light (exemplarily, p-polarized light). The second polarized light enters the polarization splitter element 31 again, passes through the splitting surface of the polarization splitter element 31, and is converted into third polarized light (exemplarily, circularly polarized light) after passing through the quarter-wave plate 36. The third polarized light is reflected by the reflective element 32, passes through the quarter-wave plate 36 again, and is converted into fourth polarized light (exemplarily, s-polarized light) before entering the polarization splitter element 31 and reflecting on the splitting surface of the polarization splitter element 31. It passes through the first lens 341 and the second lens 342 to the output end.

[0097] 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. By listing the design values ​​of optical efficiency and intensity uniformity under different color channels, the table provides a theoretical basis for the performance evaluation of the optomechanical system under different colors of light.

[0098] Table 3

[0099]

[0100] Attachment Figure 2 、 3 4 and 5 are the MTF graphs for red, green, and blue light of the optical-mechanical system, respectively. These graphs provide information about the imaging quality of the optical system at different wavelengths. The optical-mechanical system of this application implements a projection lens design with a 58° FOV. At 166 lp / mm, the MTF (Modulation Transfer Function) for red, green, and blue light is greater than 50%. Therefore, the optical-mechanical system provided in Example 1 of this application has a high optical-mechanical lens resolution, capable of resolving finer image details, helping to improve image quality, resolution, and color performance, meeting the needs of a variety of high-precision imaging applications.

[0101] Attachment Figure 5This is a diagram of vertical chromatic aberration in Example 1, showing 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 chromatic aberration diagram approaches 0 mm, and the vertical chromatic aberration is less than 3 μm. This indicates that in Example 1 of this application, as the field of view of the full-color optical system increases, the difference in the focus position of light of different wavelengths on the image plane gradually decreases, resulting in better chromatic aberration correction and high image quality.

[0102] like Figure 6 The figure shows the LCoS illumination result of the optical system. The light intensity value ranges from 1.4E+05 to 7E+05, and the light intensity value gradually decreases from the center to the edge. The light intensity in the center area is the highest at 7E+05, and the light intensity in the edge area is the lowest at 1.4E+05. The brightness of the LCoS center light reaches a high level. Figure 7 The figure shows the intensity distribution of the optical projection 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.

[0103] Example 2

[0104] The difference between Example 2 and Example 1 is that:

[0105] The first lens 341 is made of plastic. The optical parameters of each lens (curvature radius, thickness, refractive index, Abbe number, focal length) are shown in Table 4 below.

[0106] Table 4

[0107]

[0108] 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. Among them, 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.

[0109] Table 5

[0110]

[0111] The focal length f of the lens of the optical-mechanical system of this embodiment is 5.98 mm, and the ratio of the focal length f of the lens to the focal length f3 of the reflective element 32 is 0.6<f / f3<1; the combined focal length of the first lens 341 and the second lens 342 is 103.4 mm, 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 12.21 mm, 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 contribute little to the optical focal length. The optical focal length of the optical-mechanical system of this embodiment is mainly contributed by the reflective element 32.

[0112] like Figure 8 、 9 As shown in Figures 10 and 11, the optomechanical system in this embodiment achieves wide-angle image projection with a FOV greater than 58°. At the same time, at 166 lp / mm, the MTF (Modulation Transfer Function) is greater than 50% for all three colors of red, green, and blue light. Therefore, the optomechanical system provided in Example 2 of this application can also achieve the requirement of further increasing the optomechanical resolution to 167 lp / mm.

[0113] like Figure 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 becomes larger, 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.

[0114] Comparative Example 1

[0115] The difference between Comparative Example 1 and Example 1 is:

[0116] like Figure 12 As shown, the first corrective lens group 33 and the second corrective lens group 34 in Comparative Example 1 are both replaced with a single monolithic lens. Since monolithic lenses are typically made of a single material, chromatic aberration cannot be offset by combining these materials. Therefore, the chromatic aberration of a monolithic lens is primarily determined by the dispersion properties of the material, making it difficult to correct for chromatic aberration through design adjustments.

[0117] like Figure 13 As shown, for the design specification of large field of view (FOV>50°), the optical-mechanical system in Comparative Example 1 relies solely 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 system without a glued mirror 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.

[0118] 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 to the above-described embodiments. The above-described embodiments and the specification merely illustrate the principles of the present application. Various changes and improvements may be made to the present application without departing from the spirit and scope of the present application. 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 appended claims and their equivalents.

Claims

1. An optical-mechanical system, characterized in that: include: An illumination assembly includes a light source and a turning prism. The light source is used to provide illumination light. The turning prism has an incident surface facing the light source, a reflective surface, and an exit surface facing the polarization beam splitter element, and is used to deflect the illumination light. The incident and exit surfaces are aspherical surfaces for converging light. The reflective surface is a plane and is coated with a high-reflection film. The turning prism is used to narrow the divergence angle of the light beam. A display chip, used to modulate illumination light into image light; A relay imaging assembly includes the polarization beam splitter, 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, and the display chip and the turning prism are arranged on adjacent sides of the polarization beam splitter. The first corrective lens group is arranged between the polarization beam splitter and the display chip, and the first corrective lens group includes a cemented fourth lens and a fifth lens. The fourth lens having positive optical power is arranged on a side close to the polarization beam splitter, and the fifth lens having negative optical power is arranged on a side close to the display chip. The reflective element has positive optical power, and the focal length f3 of the reflective element and the focal length f of the optical mechanical system satisfy the following conditions: 0.6 < f / f3 < 1. 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 the side away from the polarization splitter element, and the second lens is arranged on the side close to the polarization splitter element.

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

6. The optical-mechanical system according to claim 1, wherein: Both side surfaces of the first lens are convex surfaces, and the surface of the second lens close to the light-emitting side is concave, and the surface away from the light-emitting side is flat.

7. The optical-mechanical system according to claim 1, wherein: The first lens is cemented to the second lens.

8. The optical-mechanical system according to claim 1, wherein: 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.

9. 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.

10. The optical-mechanical system according to claim 9, wherein: The relay imaging assembly further includes a first diffuser, which is arranged between the exit surface of the turning prism and the second polarizer.

11. A near-eye display device, characterized in that: The optical-mechanical system comprises the optical-mechanical system and the waveguide device according to any one of claims 1 to 10, wherein the optical-mechanical 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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