Optical system and optical apparatus

Abstract

Provided in the present invention are an optical system and an optical apparatus. By means of placing a micro display laterally, after image light is coupled into a first device, the distance of an optical path perpendicular to a human eye is shortened by utilizing the lateral propagation of the light in the first device, such that the thickness of the device is greatly reduced. On this basis, the system can also be designed so that image light rays enter and exit the first device multiple times, thereby further reducing the thickness of the device. Moreover, total reflection is used for replacing a semi-transparent and semi-reflective surface in a PANCAKE scheme and a Birdbath scheme, such that a light effect is greatly improved. In addition, since the micro display is placed laterally and is not located on a light path along which the human eye observes ambient light, a see-through system can be realized, and the observation effect of an optical see-through method for an external environment is much better than the observation effect of Video See Through schemes of existing VR systems.

Description

Optical systems and optical equipment

[0001] This application claims priority based on the following patent application:

[0002] Priority 1:

[0003] Application number: 202311110423.4

[0004] Application date: 2023-08-30

[0005] Name:Optical systems and optical equipment

[0006] Priority 2:

[0007] Application number: 202311491615.4

[0008] Application date: 2023-11-09

[0009] Name:Optical systems and optical equipment Technical Field

[0010] The present invention relates to the field of optical technology, and in particular to an optical system and optical equipment. Background Art

[0011] Some optical applications place stringent requirements on the size of the optical system. For example, wearable AR / VR devices are an example. Early VR devices used free-form lenses or Fresnel lenses. To achieve a field of view (FOV) of 90° or greater, the optical path length was typically over 50mm, resulting in a bulky, heavy, and uncomfortable system. The latest PANCAKE optical solution, by altering polarization to cause light to be folded back once between the lenses, can reduce the optical path length to 15-25mm while maintaining a wide FOV. This significantly reduces the size of the optical system and improves wearing comfort.

[0012] However, because the image light passes through the translucent and reflective surfaces twice, the PANCAKE solution has a theoretical maximum light efficiency of only 25%, resulting in a series of issues such as low light efficiency and the generation of ghosting images. Furthermore, whether using a free-form surface or a Fresnel lens, the optical path is configured with the imaging device centered in the optical path, preventing external ambient light from passing through. Consequently, existing VR systems use cameras to capture images of the external environment, which are then synthesized into the display system after image processing. This Video See Through (VST) approach provides significantly inferior visual quality compared to optical direct see-through systems and imposes a significant burden on system power consumption and cost. Meanwhile, the more mature Birdbath solution, a traditional AR system, utilizes an obliquely arranged translucent and reflective mirror to achieve imaging. However, this approach is relatively thick (a system with a 50° field of view is often greater than 15mm thick, making it difficult to achieve a wider field of view). Furthermore, the close proximity of the microdisplay to the reflective lens often obstructs the wearer's view of the external environment.

[0013] Summary of the Invention

[0014] To address the shortcomings of the prior art, the present invention provides an optical system and optical device. This system utilizes total internal reflection within a waveguide to replace or partially replace the semi-transparent and semi-reflective mirrors used in pancake and birdbath systems. This improves light efficiency while further folding the optical path through total internal reflection within the waveguide, reducing system size. Furthermore, a side-mounted imaging device enables the system to function as an optically transmissive AR system.

[0015] According to the present invention, an optical system is provided, comprising: a first device and a second device;

[0016] The first device includes a first surface. Image light is coupled into the first device. After entering the first device, the image light undergoes at least one total internal reflection on the first surface. For example, if the first device is a waveguide, the image light undergoes one total internal reflection on the upper surface (first surface) before being coupled out of the first device. For another example, the image light undergoes one total internal reflection on each of the upper and lower surfaces of the waveguide before being coupled out of the first device.

[0017] The first device further includes a first reflective surface that couples the image light, which has been totally reflected by the first surface, out of the first device. The first reflective surface may be located within the first device. For example, after reflection from the first reflective surface, the angle of the image light changes (e.g., the angle with the first surface changes), thereby allowing the image light to be coupled out of the first device.

[0018] The image light coupled out of the first device is modulated by the second device, and the modulated image light is then coupled back into the first device and partially or completely passes through the first reflective surface one or more times. A key difference between this implementation and existing waveguide-based solutions is that the image light is guided back to the first device by the second device and passes through the first reflective surface again. This allows the optical path to be repeatedly extended within the same space, reducing system size and enabling designs with larger fields of view (e.g., greater than 90°) that waveguide-based solutions cannot achieve.

[0019] Alternatively, in another embodiment, the image light can be directly incident on the viewer's eye through a second device without returning to the first device. In this embodiment, the second device has optical power, and the image plane of the image light coupled out of the first device is near the focal point or equivalent focal point of the second device (e.g., the image plane is located between the optical center of the second device and its focal point), so that the image light is modulated into a virtual image at a certain distance before entering the human eye. This solution differs from existing waveguide devices in that, after the image light is coupled out of the waveguide, it already forms a virtual image that is visible to the human eye at a certain distance, thus eliminating the need for a second device. Furthermore, existing waveguide devices must use multiple transmissive surfaces or gratings to achieve pupil expansion (such as arrayed waveguides or diffraction waveguides), or a free-form surface embedded in the waveguide to perform the final adjustment of the image light (curved surfaces change the optical power of the image light, but since curved surfaces within the waveguide are necessarily off-axis, they introduce difficult-to-correct off-axis aberrations). In contrast, this embodiment of the present invention uses a single, flat surface as the first reflective surface (which avoids off-axis aberrations introduced by the curved surface, thus simplifying the optical design).

[0020] Furthermore, the first device further includes a first sub-device and a second sub-device (as shown in Figures 4, 5, 6 and 21). The first sub-device includes a first sub-surface that is not parallel to the first surface. After the light undergoes at least one total reflection between the first surface and the first sub-surface, the angle between the light and the normal of the first sub-surface decreases and the light is emitted from the first sub-surface. The second sub-device includes a second sub-surface and a first reflective surface or the second sub-surface is the first reflective surface. The light emitted from the first sub-surface enters the second sub-device from the second sub-surface and is reflected by the first reflective surface or directly reflected by the first reflective surface, then passes through the first sub-device again and is emitted from the first surface (or is reflected from the first surface into the second sub-device and is emitted from the second sub-device). The advantage of further dividing the first device into two sub-devices is that each time the light undergoes a total reflection on the two non-parallel surfaces of the first sub-device, its angle of incidence with the first surface or the first sub-surface will change. In this way, the angle at which the light is incident on the first reflective surface of the second sub-device can be changed, thereby adjusting the parameters of the first reflective surface (outcoupling surface) (such as the angle with the first and second surfaces, length and width, etc.). In this design, the first surface can also be coated with an angle-selective film layer. For example, the refractive index of the first sub-device is 1.6, and its total reflection angle is approximately 38°. An angle-selective anti-reflection film layer is coated on the first surface so that light with an incident angle greater than 32° incident on the first surface of the first sub-device still has a reflectivity greater than 99% (close to total reflection), thereby increasing the angle range of the total reflection light, and light with an angle less than 30° can still be transmitted normally from the first surface (or its transmittance is increased, such as a transmittance greater than 99%).

[0021] Furthermore, the second device may also include a polarized reflective surface and / or a semi-transparent and semi-reflective surface and a wave plate-type device. As shown in FIG26 , after the image light is coupled into the first sub-device of the first device, it is totally reflected on the first sub-surface 101, and the incident angle is reduced and incident on the first surface 104. A polarized reflective film 109 is prepared on the first surface. The incident image light is S light. Regardless of whether the image light meets the total reflection condition at this time, it will be reflected back to the first sub-surface 101 again. At this time, the angle between the image light and the first sub-surface is smaller than the total reflection angle, and it will be emitted from the first sub-surface, pass through the gap (the gap is air or a medium with a certain refractive index), and be incident on the second sub-surface 102. In this example, the second sub-surface is the first reflective surface 103. A quarter wave plate 106 and a reflective coating with a certain reflectivity (such as 50% transmittance and 50% reflection) are prepared on it. After the image light enters the quarter wave plate 106, it becomes circularly polarized light. After that, part of it is reflected by the semi-transparent and semi-reflective reflective surface 103 and passes through the quarter wave plate 106 again. It is modulated into P light and returns to the first sub-device again. At this time, the angles between the image light and the first sub-surface and the first surface are all smaller than the total reflection angle (the central light can be perpendicular or nearly perpendicular to the first surface), and it has been modulated into P light, which can pass through the first surface and then enter the second device. A half wave plate 110 is prepared on the surface of the second device (or it can also be prepared on the outside of the first surface 104. In this case, there can be no gap between the first and second devices).

[0022] Furthermore, the image light undergoes total reflection once on the first sub-surface 101 (which may be the same surface as the first reflective surface) and the first surface 104 of the first sub-device, and then is reflected by the first reflective surface 103 (which may be prepared with a polarizing reflective film) and emitted from 104 (a 1 / 4 wave plate may be prepared on the surface of the second device to modulate the image light into circularly polarized light), and then enters the second device. A film with a certain reflectivity and transmittance (such as 50% reflection and 50% transmission) is prepared on the second reflective surface 201 in the second device. After entering the second device, a part of the image light first passes through the second reflective surface 201 (as shown in Figure 27). Since 201 is a curved surface, part of the light reflected back will diverge and cannot enter the imaging optical path. Therefore, the above-mentioned reflected light will not affect the imaging. The image light passing through 201 will be incident on the 1 / 4 wave plate 206 and modulated into S light. It will then be reflected back by the reflective surface 205 prepared with a polarizing reflective film (circularly polarized light). Part of the image light will be reflected and modulated by the second reflective surface 201, and then after passing through the 1 / 4 wave plate, it will become P light and pass through the reflective surface 205 to enter the viewer's eyes. The external ambient light will be P light after passing through the first reflective surface 103. Before entering the second reflective surface 201, it will be modulated into circular polarization and then again modulated into P light by the 1 / 4 wave plate 206. It will pass through 205 to enter the viewer's eyes. Furthermore, after being modulated by the image generation system, the image light on the display can be focused once in the first or second device. The image at the focused position is then modulated as the intermediate image plane by the second device (such as the second reflective surface) before entering the viewer's eyes. Furthermore, the surface of the second device facing the external environment can be prepared with an electrochromic film (such as an electrochromic film / glass with light transmittance controlled by voltage), thereby realizing the switching between non-transparent VR and transparent AR (controllable light transmittance).

[0023] Furthermore, the second sub-surface and the first sub-surface have the same or complementary surface shapes.

[0024] Furthermore, there is a gap between the second sub-surface and the first sub-surface, or a medium with a different refractive index is filled between the second sub-surface and the first sub-surface. For example, the first sub-surface and the second sub-surface have complementary surface shapes (as shown in Figure 21), and there is a 5um air gap in the middle, so that the light can be totally reflected in the first sub-component, and can also be incident on the second sub-component as soon as possible when it is emitted from the first sub-component. Alternatively, a medium with a low refractive index (such as a medium with a refractive index of 1.32) can be used to fill the gap (the medium can be optical glue, which is cured by light or heat after gluing). Furthermore, the medium in the gap can use different refractive indices in different areas, such as filling the first half of the gap with a medium with a refractive index of 1.30 (such as pure water), and filling the second half with a medium with a refractive index of 1.40. Furthermore, the angle formed by the first reflecting surface and the first surface can be equal to the angle formed by the first sub-surface and the first surface, or can be greater than or less than the angle formed by the first reflecting surface and the first surface (for example, the angle formed by the extension line of the first reflecting surface and the first surface in Figure 21 is less than the angle formed by the first sub-surface and the first surface. In this case, the overall thickness of the device will generally not increase). If the angle formed by the extension line of the first reflecting surface and the first surface is set to be greater than the angle formed by the first sub-surface and the first surface, the incident angle of the image light propagating in the first sub-device can be made larger, ensuring that it better meets the total reflection condition. At the same time, in some cases, the central light can be made closer to the vertical exit first surface.

[0025] Furthermore, the first device further includes a plurality of sub-devices, each of which includes at least one sub-surface that is not parallel to the first surface (the sub-surfaces may also be at a certain angle to each other), and the image light undergoes one or more total reflections between the one or more sub-surfaces, and the angle between the image light and the first surface or other sub-surfaces changes (in some cases, the image light may first undergo total reflection on a sub-surface, and then be transmitted from the same sub-surface due to the change in angle), and is emitted from one of the sub-devices. A sub-surface of one of the plurality of sub-devices is the first reflective surface. For example, the first device includes a first, second, and third sub-devices, which respectively include a first surface and a first sub-surface, a second sub-surface, a third sub-surface, and a first reflective surface. After the image light enters the first sub-component, it is totally reflected or reflected by the first sub-surface and then enters the first surface (the first surface is not parallel to the first sub-surface). After being reflected back to the first sub-surface by the first surface, the angle between the light and the first sub-surface does not meet the total reflection condition (the first sub-surface and the corresponding surface of the second sub-component are filled with a medium with a low refractive index or an air gap). After entering the second component, the angle between the light and the normal of the second sub-surface is greater than the total reflection angle (the second sub-surface is not parallel to the first sub-surface). It will be reflected by the second sub-surface and reflected back to the first sub-component through the surface of the second sub-component corresponding to the first sub-surface of the first sub-component. At this time, the angle between the light (or most of the image light) and the normal of the first surface is still less than the total reflection angle (if a small part of the light no longer meets the total reflection angle If the total internal reflection condition is met, a thin film that increases its reflectivity when the angle approaches the critical angle can be prepared on the first surface to ensure that most of the energy is still reflected back). After reflection, the above-mentioned light will pass through the first sub-surface and enter the second sub-component. At this time, the angle between it and the second sub-surface no longer meets the total internal reflection condition (the second sub-surface of the second sub-component corresponds to the third sub-surface of the third sub-component, and there is a low-refractive-index medium or air gap in between). The light will enter the third sub-component and be reflected by the first reflective surface that is not parallel to the second sub-surface / third sub-surface (the first reflective surface can be prepared with a reflective film). After reflection, the light will pass through the second sub-component and enter the first sub-component. At this time, the angle between it and the normal of the first surface is less than the total internal reflection angle, and it will be emitted from the first surface. The advantage of this is that by setting the angles of the first sub-surface, the second sub-surface, and the first reflective surface (for example, each surface is not parallel to each other), the angle change experienced by the light in each total internal reflection within the first component is different, which can provide greater design flexibility. If necessary, the number of sub-components and sub-surfaces can be increased (for example, four, five, or more) to meet design requirements.

[0026] Furthermore, the first sub-surface and / or the second sub-surface may be coated with one or more of the following films: an anti-reflection film, an anti-reflection film, a wave plate, a hardened film, a polarized reflective film, a wavelength-dependent reflective film, a film with varying refractive indices in different regions, a film with varying refractive indices in different regions, an angle-selective reflective film, or an anti-reflection film. For example, the anti-reflection film layers on the first and second sub-surfaces can ensure that the transmittance of light passing through the first and second sub-surfaces exceeds 99%.

[0027] Furthermore, the first sub-component and the second sub-component have the same or similar refractive indexes. For example, the first and second sub-components are made of the same material.

[0028] Furthermore, the first sub-device is a triangular or wedge-shaped waveguide, for example, a triangular waveguide with a vertex angle of 20° (or the vertex angle can be cut off to form a wedge shape). The image light is coupled into the waveguide from the side of the triangular or wedge-shaped waveguide, and is totally reflected onto the first surface after entering the first sub-surface. Since the incident angle is still greater than the total reflection angle (or most of the light that is less than the total reflection angle is still reflected back due to the angle-selective coating of the first surface), the image light will enter the first sub-surface again. Due to the existence of the vertex angle, the incident angle of the image light when entering the first sub-surface again will be reduced by 40° compared with the last time. The light no longer meets the total reflection condition and will be emitted from the first sub-surface.

[0029] Furthermore, when the image light is coupled out of the first device, the angle between the principal optical axis of the optical path and the vertical axis of the first surface is less than ±40°. For example, the image viewed by the viewer is located in the center of the field of view, and the principal optical axis of the optical path is parallel to the angle between the vertical axis of the first surface. In this case, the principal axis of the second device can also be parallel to the principal optical axis of the optical path. Then, there will be no off-axis aberration in the system, and all devices with optical power can be axisymmetric, which can greatly reduce the difficulty of optical design. Alternatively, the principal optical axis and the vertical axis of the surface can have a certain angle, such as 10°, to provide a certain degree of freedom in system design, or the field of view of the image can be set to be asymmetrical left to right or up to down, such as the field of view from the center of the eye to the nose is 45°, and the field of view on the ear side is 55°.

[0030] Furthermore, there is a gap between the second device and the first device, such as 0.1 mm, to allow light to be totally reflected within the first device. This gap can be empty or filled with a low-refractive-index medium (such as low-refractive-index optical adhesive).

[0031] Furthermore, the first reflective surface changes the angle of the image light so that the image light does not meet the total reflection condition and is emitted from the first device.

[0032] Furthermore, the first reflective surface includes a polarized reflective surface or a surface prepared with a film having a preset reflectivity. For example, a polarizing film that reflects S light and transmits P light is attached, or a film with a certain transmittance and reflectivity (such as 70% transmittance and 30% reflection) can be coated.

[0033] Furthermore, the first reflective surface includes a flat surface or a curved surface.

[0034] Furthermore, the first surface includes a flat surface or a curved surface.

[0035] Furthermore, any one or more of the following films are prepared on the first surface: an anti-reflection film, an anti-reflection film, a hardened film for increasing the surface hardness, a wave plate, a polarized reflective film, a wavelength-based reflective film, a film with different refractive indices in different regions, a film with changing refractive indices in different regions, an angle-selective anti-reflection film or an anti-reflection film (for example, 99% of the light inside the medium is reflected when the thermal reflection angle is greater than 5° of the total reflection angle, and 99% of the incident light is transmitted after the incident angle is greater than 8° of the total reflection angle).

[0036] Furthermore, the first device further includes a second surface, the second surface is parallel to the first surface or at a preset angle, and the image light undergoes at least one total internal reflection between the first surface and the second surface, and is reflected by the first reflective surface and coupled out of the first device. The first reflective surface can be located between the first and second surfaces.

[0037] Furthermore, any one or more of the following films are prepared on the second surface: an anti-reflection film, an anti-reflection film, a hardened film for increasing the surface hardness, a wave plate (such as a 1 / 4 wave plate or a 1 / 2 wave plate), a polarized reflective film, a wavelength-based reflective film, a film with different refractive indices in different regions, a film with changing refractive indices in different regions, an anti-reflection film or an anti-reflection film with angle-selective properties, etc.

[0038] Furthermore, the second device includes any one or more of the following: a lens, a superlens / supermirror, a variable lens / variable mirror, a liquid lens / liquid mirror, a liquid crystal lens / liquid mirror, a transmissive or reflective spatial light modulator, a flat or curved mirror, a microlens or micromirror array, a reflective film or polarized reflective film with a certain reflectivity, a wave plate, a Fresnel mirror, a grating, a prism, a mechanical motor, a voice coil motor, or electronic and mechanical structures capable of changing the position of the device. For example, the second device can be a combination of a lens and a mirror (e.g., a first surface is a transmissive curved surface, and a second surface is a reflective or partially reflective curved surface). A lens array, Fresnel mirror, or superlens can also be added to further reduce the size. A mechanical motor, a voice coil motor (VCM), or other mechanical structure can also be included to adjust the spatial position of the optical device, thereby achieving the function of statically or dynamically changing the imaging position of the image (in some embodiments, these position adjustment structures and electrical components such as motors can also be included in the first device).

[0039] Furthermore, the optical system also includes a third device, which includes any one or more of the following devices: a lens, a super lens / super mirror, a variable lens / variable mirror, a liquid lens / liquid mirror, a liquid crystal lens / liquid crystal mirror, a transmissive or reflective spatial light modulator, a flat or curved mirror, a microlens or micromirror array, a reflective film or a polarized reflective film with a certain reflectivity, a wave plate, a Fresnel mirror, a grating, a prism, a mechanical motor, a voice coil motor, and an electronic and mechanical structure that can change the position of the device.

[0040] Furthermore, the first device further includes a second surface. After the image light is coupled into the first device again and partially or completely transmits through the first reflective surface, it is coupled out of the first device through the first or second surface. After being coupled out of the first device, it can directly enter the viewer's eyes, or it can enter the third device for further modulation.

[0041] Furthermore, the image light entering the third device is reflected by the third device and then enters the first device again, for example, enters the first device again and exits through the first reflective surface, and is modulated by the second device again and then exits into the viewer's eyes.

[0042] Furthermore, the optical system includes an image generation system, which includes any one or more of the following devices: a microdisplay, a spatial light modulator, a lens, a superlens / supermirror, a variable lens / variable mirror, a liquid lens / liquid mirror, a liquid crystal lens / liquid crystal mirror, a mirror, a polarizing mirror, a prism, a microlens array, a grating, a polarizer, a wave plate, a Fresnel mirror, a mechanical motor, a voice coil motor, and electronic and mechanical structures that can change the position of a device.

[0043] Furthermore, the micro display includes any one or more of the following devices: OLED, LED, LCoS (Liquid Crystal on Silicon), LCD, DMD (Digital Mirror Device), LBS (Laser Beam Scanner), CRT (Cathode-Ray Tube).

[0044] Furthermore, the image generated by the image generation system is located between the focal point or equivalent focal point of the second device and the second device. For example, the image generation system comprises only a microdisplay, which is located between the equivalent focal point of the second device and the second device (or at the optical center of the second device). Alternatively, the image generation system comprises an optical device such as a lens or reflector, wherein the microdisplay serves as an object, and the lens or reflector of the image generation system projects a virtual or real image of the microdisplay between the equivalent focal point of the second device and the second device.

[0045] Furthermore, the image (image plane) generated after the image light is modulated by the second device is located between the focus of the third device or the equivalent focus and the third device.

[0046] Furthermore, the optical system further includes any one or more of the following devices: a voice coil motor, a spatial light modulator, a mechanical motor, a liquid crystal lens, a liquid lens, and a variable lens.

[0047] Furthermore, the optical system adjusts the imaging distance by changing the physical position between devices (achieved by motors, electrical machines or other electronic or mechanical structures) or changing the refractive power of the devices (such as by changing the phase distribution of a liquid lens, a liquid crystal lens or a spatial light modulator).

[0048] Furthermore, the angle between the main optical axis of the image light path coupled into the first device and the vertical axis of the first surface is less than ±40°. For example, the main optical axis of the image light path is parallel to the vertical axis of the first surface, or the angle between the main optical axis and the vertical axis is 10°.

[0049] Furthermore, the second device and / or the third device modulates the ambient light passing through to compensate for myopia and astigmatism errors in the human eye. For example, the second device is a lens / reflector comprising two working curved surfaces. The curved surface facing the first or second surface transmits incident light, while the curved surface facing away from the first surface reflects or partially reflects the incident light (e.g., fully reflective, semi-transmissive, semi-reflective, or polarized reflective); or the curved surface facing the first or second surface reflects the incident image light while transmitting or partially transmitting the ambient light, while the curved surface facing away from the first surface transmits and modulates the incident ambient light.

[0050] Furthermore, the first device further includes a second surface non-parallel to the first surface. After undergoing at least one total internal reflection between the first and second surfaces, the image light or a portion of the image light changes its angle with the first and / or second surfaces and exits from the first and / or second surfaces. Furthermore, the image light undergoes at least one total internal reflection on the surface from which it exits. In some embodiments, the reflection experienced by the image light or at least a portion of the image light before exiting the first device is due to total internal reflection caused by an angle between the light and the surface exceeding the total internal reflection angle (rather than reflection caused by a reflective coating). The cross-section of the first device can be triangular or wedge-shaped, wherein the first reflective surface is the first or second surface. Unlike some previously described embodiments, in this embodiment, the first reflective surface can be free of a reflective coating. Thus, when ambient light passes through this surface, its transmittance can reach over 90% (or even over 99%), significantly increasing the transmittance of ambient light. As shown in Figures 22 and 23, in this example, the first surface 104 also serves as the first reflective surface 103, i.e., the first surface 104 and the first reflective surface 103 are the same surface. After the image light is coupled into the first device, it undergoes one or more total internal reflections between the first and second surfaces. Due to the angle between the first and second surfaces, the angle between the image light and the normal of the first or second surface decreases after each total internal reflection until the total internal reflection condition is no longer met, resulting in the image light being emitted from the first or second surface. The second device includes a second reflective surface 201. In such solutions, the second reflective surface 201 often utilizes a non-rotationally symmetric curved surface (a free-form surface or a portion of a rotationally symmetric surface). The angle of the central ray of the image light (the principal ray, the central axis of the optical path) is altered after being modulated by the second reflective surface (in contrast to some previously described solutions, where the central ray of the image light is often reflected back along its original path after being modulated by the second reflective surface). The surface of the second reflective surface can be coated with a reflective film with a certain reflectivity (e.g., 25% reflection, 75% transmission, or a polarizing reflective film). The advantage of this solution is that the system can be made thinner, significantly increasing the system's transmittance to ambient light and the utilization rate of image light while reducing the system thickness. In other embodiments, the total reflection is a reflection caused by an angle between the light and the normal of the first and / or second surface being greater than the total reflection angle, or a reflection caused by a coating prepared on the surface (such as a dielectric reflection film, a metal reflection film, or a polarized reflection film of a grating, etc.).

[0051] Furthermore, the image light undergoes at least one total internal reflection on each of the first and second surfaces before exiting the first device from the first or second surface. As shown in Figures 22 or 23, after being coupled into the first device, the image light first undergoes one total internal reflection on the second surface 108 before entering the first surface 104. After being fully or partially reflected again by the first surface, the image light again enters the second surface. At this point, the angle between the image light and the normal of the second surface is less than the total internal reflection angle, and the image light exits from the second surface and enters the second device. After being modulated and reflected by the second reflective surface (the second reflective surface is a curved surface) within the second device, the image light exits the device. Upon re-entering the first device, the image light's angle with the normal of the first and second surfaces is less than the total internal reflection angle, and thus exits the system. In such embodiments, the gap between the second device and the first device can be an air gap, or it can be filled with a medium having a certain refractive index (e.g., glue having a lower refractive index than the first device). An angle-selective anti-reflection film can also be prepared on the surface of the first device that is not facing the second device (such as the first surface 104 in Figures 22 and 23). For example, the refractive index of device 1 is 1.60, and the total reflection angle is about 38.68°. After the thin film is prepared on the first surface 104, the light in device 1 with an angle greater than 30° to the normal of the first surface still has a reflectivity greater than 99%, while the light in device 1 with an angle less than 30° (or less than 25°) to the normal of the first surface has a transmittance of 99%.

[0052] Furthermore, the first device and / or image generation system includes at least one rotationally asymmetric surface. For example, a lens / lens assembly / reflector / reflector assembly / prism assembly in the image generation system includes a rotationally asymmetric surface, and the rotationally symmetric surface is used to compensate for aberrations caused by a second reflective surface in the second device. In particular, aberrations (asymmetric aberrations) generated when the second reflective surface is a rotationally asymmetric surface.

[0053] Furthermore, the first device includes a curved surface, and the focus and / or center of the curved surface and at least one surface in the second device (such as the second reflective surface) are at the same position or the distance between the two is less than a preset value, or both are on a specific light ray or its extension line, or the distance between the two and a specific light ray or its extension line is less than a preset value (for example, the main light or central light of the central field of view of the image light, or the main light or central light of a certain field of view, the light changes direction after multiple reflections in the waveguide to form a multi-segment line, and the focus or center of the two surfaces can be respectively on any one of the segments or its extension line, or the distance from any one of the segments or its extension line is less than a preset value). The surface types of the two can also be similar. As shown in Figure 24, the curved surface 105 in the first device and the curved surface 201 of the second device are both parabolic (each is a part of a parabola, or can also be a free-form surface). For example, the image light is incident on the surface facing the focus of 201, while the image light is incident on the surface facing away from the focus of 105. The foci of these two paraboloids are both located on the main ray of the central field of view (or central ray) and its extension line (for example, the focus of surface 105 is on the line segment of the main ray of the central field of view of the image incident on 105 or on its extension line or reverse extension line, while the focus of surface 201 is on or near the reverse extension line of the line segment of the central image ray incident on surface 201), or the distance between these two foci and the above-mentioned ray and its extension line is less than 10 mm. In this way, the two surface shapes are similar and can play a good role in complementing aberrations.

[0054] Furthermore, one surface of the first device is a curved surface, and the curved surface has the same surface shape as at least one surface of the second device or the surface shape difference is within a preset range. As shown in Figure 25, the second surface 108 is the same or similar to the surface 201 of the second device (such as the surface shape error is within 20um). In this way, for the image light, it is equivalent to adding a modulation surface 108. At the same time, since the surface shapes of 108 and 201 are the same or similar, the ambient light is almost unchanged after passing through 201 and 108. The advantage of doing so is that the thickness of the device can be further reduced and the weight can be reduced. In addition, the surface 108 can also be designed to have a preset deviation from 201 (such as a different curvature, etc.), so that the combination can modulate the ambient light while modulating the image light, compensating for defects such as myopia, hyperopia, and astigmatism of the human eye.

[0055] Furthermore, the optical system further includes a detector. The detector is used to detect light coming from the viewer's direction (such as the viewer's eyes) and / or to detect light coming from the external environment. The detector collects the detected light through the first device and / or the second device. The detector can be an image sensor (such as a CCD, CMOS, etc.) or an infrared detector (a proximity detector, an infrared detector, an infrared image sensor, etc.). The detector can be used to determine whether the device is currently being worn. The detector can also be used to capture the viewer's eyes, thereby achieving eye tracking. Compared to the tilted eye tracking system in traditional AR / VR systems, the optical axis of the eye tracking system provided by the present invention is perpendicular or nearly perpendicular to the viewer's eye plane (achieved by light guidance through a waveguide system, as shown in FIG28 ), so it can achieve more accurate eye tracking through simpler calculations. In addition, the sensor can also be used to capture the external environment. Unlike the camera in a traditional AR / VR system, the present invention can make the shooting light path parallel to the optical axis of the human eye and in the same position through the light guidance of the first device (waveguide), that is, the captured image can be exactly the same as the image seen by the human eye. The sensor can be located outside a surface of the first device, and the image of the external environment or the viewer (glasses) is coupled to the detector through the first device through a lens / reflector assembly (or part of a lens / reflector assembly) (as shown in Figure 28). A dedicated image sensor lens / reflector assembly can also be added. Another advantage of this is that imaging, eye tracking, environmental capture, TOF, and DOE modules can all be integrated into the first device (waveguide), making the system more compact, similar to an integrated circuit board.

[0056] Furthermore, the optical system also includes a light emitter, which is used to emit light to the viewer and / or the external environment. The emitter emits the light through the first device and / or the second device. The light emitter can be an infrared light emitter, a structured light (DOE), etc. The light emitter can be arranged on the outside of a certain surface of the first device, and emit light to the viewer through the first device (waveguide) (for realizing proximity detection, eye tracking and other functions), or it can also emit light to the outside (such as a certain form of structured light) to realize functions such as SLAM. The advantage of doing this is that all optical-related modules can be integrated into the first device (waveguide), making the system smaller like an integrated circuit board.

[0057] An optical device provided according to the present invention includes the above-mentioned optical system.

[0058] Compared with the prior art, the present invention has the following beneficial effects:

[0059] The present invention places the microdisplay on its side, couples the image light into a first device (such as a waveguide), and then uses the lateral propagation of light in the first device to compress the distance of the optical path perpendicular to the human eye, thereby greatly shortening the device thickness. On this basis, the system can also be designed so that the image light enters and exits the first device multiple times, thereby further compressing the device thickness. At the same time, total reflection is used to replace the semi-transparent and semi-reflective surfaces in the PANCAKE and Birdbath schemes (in the PANCAKE and BB schemes, the image light is reflected and transmitted once on the semi-transparent and semi-reflective surfaces, and the theoretical maximum light efficiency is only 25%), thereby greatly improving the light efficiency. In addition, because the microdisplay is placed on its side and is not on the light path for the human eye to observe ambient light, a see-through system can be realized, and its optical see-through (Optical See Through) method will have a much better observation effect on the external environment than the Video See Through solution of the existing VR system. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0061] FIG1 is a schematic structural diagram of an optical system;

[0062] FIG2 is a schematic structural diagram of an optical system;

[0063] FIG3 is a schematic structural diagram of an optical system;

[0064] FIG4 is a schematic structural diagram of an optical system;

[0065] FIG5 is a schematic structural diagram of an optical system;

[0066] FIG6 is a schematic structural diagram of an optical system;

[0067] FIG7 is a diagram showing the working principle of an optical system;

[0068] FIG8 is a diagram showing the working principle of an optical system;

[0069] FIG9 is a diagram showing the working principle of an optical system;

[0070] FIG10 is a diagram showing the working principle of an optical system;

[0071] FIG11 is a diagram showing the working principle of an optical system;

[0072] FIG12 is a diagram showing the working principle of an optical system;

[0073] FIG13 is a diagram showing the working principle of an optical system;

[0074] FIG14 is a diagram showing the working principle of an optical system;

[0075] FIG15 is a diagram showing the working principle of an optical system;

[0076] FIG16 is a diagram showing the working principle of an optical system;

[0077] FIG17 is a diagram showing the working principle of an optical system;

[0078] FIG18 is a diagram showing the working principle of an optical system;

[0079] FIG19 is a diagram showing the working principle of an optical system;

[0080] FIG20 is a diagram showing the working principle of an optical system;

[0081] FIG21 is a diagram showing the working principle of an optical system;

[0082] FIG22 is a diagram showing the working principle of an optical system;

[0083] FIG23 is a diagram showing the working principle of an optical system;

[0084] FIG24 is a diagram showing the working principle of an optical system;

[0085] FIG25 is a diagram showing the working principle of an optical system;

[0086] FIG26 is a diagram showing the working principle of an optical system;

[0087] FIG27 is a diagram showing the working principle of an optical system;

[0088] FIG28 is a diagram showing the working principle of an optical system;

[0089] FIG29 is a diagram showing the working principle of an optical system;

[0090] In the figure: 1-first device; 2-second device, 3-image generating system; 4-third device; 101-first sub-surface; 102-second sub-surface; 103-first reflecting surface; 104-first surface; 105-image coupling surface; 106-wave plate; 107-third surface; 108-second surface; 109-reflective film; 110-1 / 2 wave plate; 201-second reflecting surface; 202-wave plate; 203-glasses; 204-curved surface; 205-reflective surface; 206-wave plate; 301-micro display; 302-lens / lens group / prism group; 303-image generating lens / reflector group; 304-wave plate; 401-detector. DETAILED DESCRIPTION

[0091] The present invention will be described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several changes and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0092] An AR / VR optical system, as shown in Figure 1, includes an image generation system, a first device 1, and a second device 2. The microdisplay in the image generation system 3 is a high-resolution Micro OLED (e.g., approximately 1 inch in size, with a resolution of 2560x2560), which generates image light based on signals from the electronic system. The image generation system also includes a lens assembly and a prism. The lens assembly modulates the image output by the OLED (e.g., magnifying or reducing it to form a real or virtual image near the focal point of the second device), while the prism is responsible for changing the propagation direction of the image light and directing / coupling it into the first device 1. The image generation system in this embodiment also includes a polarizer that modulates the image light into light polarized in the S direction relative to the first reflective surface.

[0093] The optical system composed of the lens group and prism in the image generation system of this embodiment can be equivalent to a lens with a focal length of approximately -25 mm, projecting a virtual image of the image on the microdisplay into the first device. In the optical path, the position of the virtual image is between the focal point of the second device and the second device.

[0094] As shown in Figures 7 and 8, the first device is approximately 8 mm thick and made of a resin material with a refractive index of 1.6. It comprises an image coupling surface 105, a first surface 104, a second surface 108, and a first reflective surface 103. After the image light is coupled into the first device, because the angle between all image light rays and the first surface 104 (the angle between the light rays and the normal to the tangent line at the point of incidence on the first surface 104) is greater than the total internal reflection angle, the image light rays undergo total internal reflection at the first surface 103 and do not exit. After total internal reflection, the image light rays enter the first reflective surface 103, which is a polarized reflective surface (e.g., with a grating-like polarizing reflective film attached, transmitting P light and reflecting S light), and can reflect the first incident image light. The configuration of the first reflective surface 103 alters the propagation angle of the image light rays (for example, it can be configured so that the principal ray / central ray / principal optical axis of the optical path, after reflection, is perpendicular to or less than a certain angle with the first surface), thereby disrupting the total internal reflection condition for the image light rays and causing them to exit from the first surface 104. In this example (as shown in FIG7 ), the angle between the image coupling surface 105 and the first surface 104 is 60°, the main optical axis of the image light path is perpendicular to the image coupling surface, and the angle between the first reflective surface 103 and the first surface 104 is 30°. The image light is reflected by the first reflective surface 103 and then emitted from the first device.

[0095] The second device is a centrosymmetrical spherical or aspherical reflector (or a lens assembly consisting of multiple lenses and reflectors). In this example, the principal optical axis of the second device is perpendicular to the first surface of the first device. The aperture of the second device is approximately 40 mm, and there is a 0.5 mm air gap between the second device and the first device. A quarter wave plate 202 is attached to the surface of the second device opposite to the first device. In this example, the reflectivity of the second reflective surface 201 is >99.9%. After the image light is emitted from the first device, it first passes through the surface of the second device to which the quarter wave plate 202 is attached and is modulated into circular polarization. After being reflected by the second reflective surface 201, it passes again through the surface of the second device to which the quarter wave plate is attached and becomes P linear polarization. It then enters the first device again. This time, since the image light has been modulated into P light, it will pass through the first reflective surface 103 and be emitted from the second surface 108 of the first device into the viewer's eyes. Since the image generating system modulates the image light to form an image near the focus of the second device, and the aberrations of the image generating system and the second device can be designed to compensate each other, the viewer will eventually clearly see a virtual image formed at a certain distance.

[0096] In a variation of this embodiment, the second reflective surface 201 in the second device can also be made of a semi-transparent, semi-reflective or reflective film with a certain reflectivity (for example, 30% reflection, 70% transmission). A lens with one side complementary to the second device and the other side being flat is prepared (e.g., glued) above the second reflective surface 201 (as shown in FIG8 ). In this way, the VR system can be transformed into an AR system, and external ambient light can enter the human eye after passing through the second device and the first device. In addition, if the viewer's glasses have problems such as myopia, hyperopia, and astigmatism, the plane of the second device facing the ambient light can be made into a curved surface (or a curved mirror can be added, as shown in FIG11 ) to compensate for the person's defects and act like glasses, so that the viewer can view the external environment similarly through glasses. In this case, for the modulation of the distance of the image light, focusing can be achieved by adding devices such as VCM voice coil motors to the image generation system to dynamically change the spatial position of the optical devices therein, or by using devices such as liquid lenses or liquid crystal lenses, or by adding a reflective phase spatial light modulator at the position of the image coupling surface 105 (coupling reflection surface) in Figure 8 to dynamically simulate an arbitrary lens (which can compensate for farsightedness, nearsightedness, and astigmatism). The above schemes can adjust the imaging distance in real time through control signals, and while compensating for errors such as myopia, hyperopia, and astigmatism of the human eye, they can also achieve light field display.

[0097] In another variation, the image generation system and image coupling can be designed as shown in FIG20 . The image light from the microdisplay 301 is P light (a polarizer may be added). This light can be emitted from the first device through the image coupling surface 105 (image coupling reflection surface) coated with a polarizing reflective film. It then enters the image generation lens / reflector assembly 303, which has a quarter-wave plate 304 on its surface. After being reflected, it passes through the quarter-wave plate again and is modulated into S light. It then enters the first device. It is then reflected by the polarized reflection surface of the image coupling, undergoes total internal reflection in the first device, and is then reflected by the first reflection surface 103 and coupled out of the first device. This design has the advantage of increasing the length of the image coupling optical path without increasing the system volume. A longer optical path provides some design freedom. For example, the image light from the microdisplay can be converged and focused into a real image. The converged light can reduce the size of the coupling surface (conventional designs often produce a virtual image, where the image light is initially modulated to diverge and expand, requiring a larger coupling surface). In addition, the direction of the microdisplay can be changed, such as placing the microdisplay on the side of the human eye rather than the side of the external environment.

[0098] In another variation, the image generating system can be arranged on the side of the first device (as shown in Figures 28 and 29, the micro display is located on the extension line of the propagation direction of the image light in the first device, and the propagation direction refers to the propagation direction of the image light in the first device after the propagation direction is changed upon entering the image coupling surface 105 prepared with a polarizing reflective film and before it is reflected by the first reflective surface), and the light is reflected to the image generating lens / reflector group 303 which is parallel to the first surface 104 or the second surface 108 through the image coupling surface 105 prepared with a reflective coating or a polarizing reflective film in the first device (as shown in Figures 28 and 29), wherein the image generating system is arranged on the side of the first device (as shown in Figures 28 and 29), and ... The lens / reflector assembly 303 also includes a quarter-wave plate. After the modulated light enters the first device again, the polarization direction changes and it passes through the image coupling surface 105 provided with a reflective coating or a polarized reflective film. It is then modulated by the image generating lens / reflector assembly parallel to the other surface of the first device (the second surface 108 or the first surface 104). The image generating lens / reflector assembly also includes a quarter-wave plate. After the modulated light enters the first device again, the polarization direction changes again. It is reflected by the image coupling surface 105 provided with a reflective coating or a polarized reflective film and then propagates within the first device until it is emitted from the first device and modulated by the second device. In addition, the display and the image generating lens group can also be arranged on the first surface 104 or the second surface 108 or on a surface nearly parallel thereto, or the display and the image generating lens group can be arranged on a side surface that is parallel or approximately parallel to the propagation direction of the light in the first device (such as the surface enclosed by the image coupling surface 105 and the first surface 104 and the second surface 108 in Figure 28, that is, the side surface parallel to the paper surface). The propagation direction refers to the propagation direction of the image light in the first device after the propagation direction is changed upon incident on the image coupling surface 105 prepared with a polarizing reflective film and before it is reflected by the first reflective surface 103. The adjustment of the above-mentioned coupling surface position can be achieved by adjusting the angle of the image coupling surface 105 where the polarizing reflective film is located.

[0099] The image-generating lens / reflector assembly (e.g., 303 in Figures 28 and 29) can also utilize a dynamically modulated spatial light modulator (e.g., a reflective phase-modulated LCoS chip) to achieve real-time variable image focal length (light field display) based on the signal. In this embodiment, a detector (e.g., an infrared image sensor) can be added after the image-generating lens / reflector assembly. As shown in Figure 28, light from the viewer's eye is coupled out of the first device and into the detector via the first and second components (the light from the eye can be emitted through the uncoated portion of the reflector in 303, or the coating on the reflector in 303 can transmit specific wavelengths, such as infrared, and thus pass through 303 and into the detector). Optical devices can also be added in front of the detector to focus the image, thereby capturing the viewer's eye and achieving eye tracking. The detector can also be a common image sensor such as a CCD or CMOS, which captures images of the external environment through a similar optical path arrangement. A light emitter (such as an infrared emitter, or no emitter and using image light emitted by the display) can also be set behind the image generating lens / reflector group on the other side or on the image generating system side to assist in eye tracking, or to emit structured light to the external environment (such as using a DOE device) to realize SLAM function.

[0100] In another variation, the second device can also be a lens instead of a reflector, so that the image light is reflected by the first reflective surface, coupled out of the first device, and then modulated by the second device and directly enters the human eye. In general, the main optical axis of the image light path after reflection by the first reflective surface is generally set to be parallel to (or coincident with) the optical axis of the first device. This can reduce the aberration caused by the off-axis of the system and simplify the optical design. In this embodiment, if the system is a non-perspective VR, the first reflective surface can be directly coated with a high-reflectivity metal reflective film. If the system is a perspective AR system, the first reflective surface can still be coated with a polarized reflective film or a film. In a variation of this example, the lens may also be a liquid crystal lens or a transmissive phase spatial light modulator. In this case, since the liquid crystal lens or phase spatial light modulator is sensitive to polarization, it may be set to modulate only S light. In this way, the image light reflected by the first reflective surface is S light, which can be modulated by the liquid crystal lens into a virtual image at a certain distance to be viewed, while the ambient light penetrates from the other side of the first device and passes through the first reflective surface and will be filtered into P light. It will not be modulated when passing through the liquid crystal lens and can thus be seen normally by the human eye.

[0101] In a variation of the above embodiment, a quarter-wave plate can also be fabricated on the first surface of the first device (as shown in Figures 9, 10, 11, and 12) or near the first surface within the first device. In this case, the image light initially coupled into the first device is S light, which is modulated into P light after a single total reflection by the first surface. A polarizing reflective film that reflects S light is affixed to the first reflective surface. The image light modulated into P light then passes through the first reflective surface, undergoes a single total reflection by the second surface, and returns to the first surface. After another total reflection, it is modulated into S light, enters the first reflective surface, and is reflected and coupled out of the first device. This approach has the advantage of further increasing the distance the image light travels within the first device, further increasing the lateral optical path length, compressing the optical path length in the direction perpendicular to the glasses 203, and reducing the thickness. Preparing a 1 / 4 wave plate on the first surface of the first device can also bring benefits to some image generation systems and coupling first devices. For example, in the system shown in Figure 3, if a 1 / 4 wave plate 106 is prepared on the first surface, then when the micro display size is large or the image light angle is large, the image light is reflected once by the image coupling reflection surface in the first device, and then it will be incident on the first surface and undergo a total internal reflection. In some designs, the image light should not be reflected a second time by the image coupling reflection surface. However, due to the constraints of light angle and image size, the light often hits the image coupling reflection surface again. At this time, if the image coupling reflection surface is also a polarized reflection surface, the S light that has been reflected once will be modulated into P light by the 1 / 4 wave plate on the first surface after experiencing total internal reflection from the first surface. It will pass through the image coupling reflection surface and then be incident on the second surface or the first reflection surface, thereby ensuring the correctness of the optical path and achieving the design purpose.

[0102] In a variation of the above embodiment, the first surface can be attached with a quarter-wave plate and then coated or attached with a metal reflective film or a partially reflective film (as shown in FIG12 ). In this way, the image light undergoes multiple total reflections before entering the first reflective surface. After being reflected by the first reflective surface, it will be reflected back into the first device by the first surface. Since the polarization direction changes from S light to P light, it will pass through the first reflective surface and exit from the second surface. In this embodiment, the second device can be disposed outside the second surface.

[0103] In another embodiment, the system further includes a third device 4, which is arranged on the second surface side of the first device corresponding to the first surface (as shown in Figures 2, 3, and 13). The third device is a lens or a lens group that further modulates the light reflected by the second device. In a VR system, this can increase the number of optical surfaces and increase the means of light modulation, thereby achieving better optical performance. When the system is an AR, the reflective surface of the second device can be a semi-transparent and semi-reflective surface or a polarized reflective surface, so that external ambient light can pass through the second device, and the third device can also be used to compensate for the impact of the first and second devices on the ambient light (as shown in Figure 14, a curved surface 204 is added to the second reflective surface to compensate for the ambient light, but it does not affect the image light). For example, the third device is designed to have a focal length close to that of the second device, and the focus is set to coincide with the second device. The aberration and the first and second devices compensate each other, so that the ambient light can still be viewed normally by the human eye after passing through the first, second, and third devices. The design of the third device can also consider adjusting the refractive power of the human eye to compensate for the viewer's myopia, hyperopia, astigmatism and other problems. The above-mentioned compensation for human eye aberrations can also be achieved on the second device, so that only the ambient light is affected. The distance of the image light can be realized by changing the spatial position of the optical device in the imaging system (or using liquid lenses, liquid crystal lenses, phase spatial light modulators and other devices) to achieve light field display, realizing real-time adjustment of the image distance while compensating for the myopia, hyperopia and other problems of the human eye.

[0104] In a variation of this embodiment (as shown in FIG15 ), the second device is a transmissive lens or lens group. The image light is emitted from the first device and then directly emitted from the second device into the human eye. The third device 4 serves as a compensation plate and only compensates for the impact of the second device on ambient light and the myopia, hyperopia, astigmatism, etc. of the human eye. The third device does not participate in the modulation of the image light.

[0105] In another embodiment, to further shorten the optical path length, the system can be designed to make multiple folds between the first, second, and third components (as shown in Figure 16). In this example, the first reflective surface is semi-transparent and semi-reflective, the second component has a quarter-wave plate and a polarizing film attached to its two surfaces, and the third component is coated with a high-reflectivity metal reflective film (or alternatively, a semi-transparent and semi-reflective film). Image light is modulated into circular polarization and enters the first component. After first reflecting off the first reflective surface, it exits onto the surface of the second component with the quarter-wave plate attached, where it is modulated into S-polarized linear light. It is then reflected off the surface of the second component with the polarizing film attached, and after passing through the quarter-wave plate again, it becomes circularly polarized and enters the first component. Part of the light that passes through the first reflective surface is incident on the reflective surface of the third component, where it is modulated again and passes through the first reflective surface. Finally, it enters the surface of the second component with the quarter-wave plate attached, where it is modulated into P-polarized light and then passes through the polarizing reflective surface of the second component to enter the human eye. In this embodiment, the image light folds back and forth multiple times between the first, second, and third components, further compressing the optical path and reducing component thickness.

[0106] In another embodiment, the first device further comprises a third surface 107, which is the side opposite the first and second surfaces (as shown in FIG17 ). A quarter-wave plate and a reflective film are formed on the third surface. Image light incident on the first device is P-polarized light, and a polarized reflective film is formed on the first reflective surface. After entering the first device, the image light first passes through the first reflective surface before entering the third surface. After passing through the quarter-wave plate twice, it is modulated into S light and reflected back into the first device. When the image light again enters the first reflective surface, it is reflected by the first reflective surface and coupled out of the first device. The second device is a cemented mirror. The surface closest to the first device is flat, with a quarter-wave plate 202 attached to it. The cemented surface is aspherical and coated with a semi-transparent and semi-reflective film (or a specific transmission-reflection ratio can be set, such as 30% reflection and 70% transmission). Image light incident on the semi-transparent and semi-reflective surface is modulated and partially reflected back to the surface with the quarter-wave plate. After being modulated into P light, it enters the first device again and is coupled out of the first device after passing through the first reflective surface. The surface of the second component facing the external environment is flat (or may have a certain optical power and cylindricality to compensate for the human eye's limitations). Ambient light passes through the second component and the first component and enters the human eye, where it can be seen normally. The advantage of this third surface is that it further increases the optical path length within the limited dimensions of the first component, facilitating optical design.

[0107] In another embodiment (as shown in FIG18 ), the first surface 104 and the second surface 108 of the first device are not parallel, but form an angle between them. Each time the image undergoes total reflection at the first and second surfaces, the angle between the image and the above surfaces decreases (or can also be designed to increase according to system requirements). After several total reflections, the image light is incident on the first reflective surface and then exits. Compared to a system in which the first and second surfaces are parallel, the advantage of the wedge-shaped or triangular first device in this example is that the angle between the image light and the first and second surfaces can be changed during the process of total reflection within the first device. This angle will affect the distance from the image generation system to the first reflective surface and the thickness of the first device, such as the angle between the coupling surface and the first reflective surface and the first and second surfaces. Therefore, this design provides additional degrees of freedom for system design.

[0108] In another embodiment (as shown in FIG19 ), the first and second surfaces are curved surfaces, and the image light is modulated by the first and second surfaces while being transmitted by total internal reflection. This increases the number of curved surfaces that can modulate the image light without increasing the number of components. Furthermore, if the system is a transmissive AR system, the first and second surfaces can also modulate the ambient light, compensating for the effects of the second and third components on the ambient light, allowing the ambient light to pass through the system normally and be viewed by the human eye. Furthermore, the system can compensate for myopia, hyperopia, and astigmatism, acting as glasses.

[0109] In some cases, it is desirable for the principal axis of the image light path of the image generating system to be perpendicular to the image light coupling surface of the first device (to avoid asymmetric aberrations). Since the angle between the principal axis of the image light path and the first and second surfaces is an important system parameter, the angles between the coupling surface and the first reflective surface and the first and second surfaces are directly related to it. The thickness of the first device is also directly related to these parameters. Generally, the smaller the angles between the coupling surface and the first reflective surface and the first and second surfaces, the thinner the first device can be.

[0110] In another embodiment (as shown in FIG21 ), the first device includes a first sub-device and a second sub-device. The first sub-device is a triangular waveguide (or a wedge-shaped waveguide in which the first surface forms a 20° angle with the first sub-surface) made of a resin material with a refractive index of 1.60 and a vertex angle of 20°. The image light is S-polarized and is coupled into the waveguide from the side (the coupling surface can be set perpendicular to the principal optical axis of the image light, or a reflective surface coupling scheme can be used, as in the coupling method shown in FIG3 ). Upon incident on the first sub-surface, since all image light now has an angle (incident angle) with the normal of the first sub-surface greater than 60° and less than 78°, which is greater than the total internal reflection angle (approximately 38.68°), all light is totally reflected by the first sub-surface back to the first surface. Due to the 20° angle between the first surface and the first sub-surface, when the image light enters the first surface, its angle of incidence is reduced by 20° compared to its previous angle of incidence with the first sub-surface, but is still greater than 40°, satisfying the total internal reflection condition. When the image light is totally reflected by the first surface and incident on the first sub-surface again, its incident angle on the first sub-surface will be reduced by another 20°. At this time, the incident angle is within the range of 20 to 38°, and the total reflection condition will not be met and it will be emitted from the first sub-surface. The second sub-component is a triangular waveguide (or wedge-shaped waveguide) with a vertex angle of 20°, which includes a second surface, a first reflecting surface and a second sub-surface, wherein the angle between the second surface and the second sub-surface is 20°, and the first reflecting surface is inside the second sub-component, and the angle between it and the second surface is 14.5°. The second sub-surface corresponds to the first sub-surface (the surface shape is the same and complementary), and there is a gap of about 10um thickness between the second sub-surface and the first sub-surface (which can be an air gap or filled with a low refractive index medium). The two surfaces can be separated by a 10um thick film or metal at the edges or peripheral non-transparent areas of the first and second sub-surfaces, and the edges can be cured with glue, or a structural member can be used to separate the gap. The first reflective surface is coated with a polarizing reflective film (or a semi-transparent, semi-reflective film with a certain transmittance and reflectivity), which can reflect S light and transmit P light. The S-direction image light emitted from the first sub-surface will enter the second sub-component from the second sub-surface, be reflected by the first reflective surface, and then be emitted from the second sub-surface. It will pass through the first sub-surface again, enter the first sub-component, and then be incident on the first surface. At this time, its incident angle relative to the first surface ranges from -9 to 9 degrees, which does not meet the total reflection condition and will be emitted from the first surface. There is also a second device in this system. There is a 50um air gap between the second device and the first surface. The second device consists of two parallel outer surfaces and an internal semi-transparent and semi-reflective reflective surface (or a reflective surface with a certain reflective transmittance or a polarized reflective surface) with a curvature (which can be a spherical surface, an aspherical surface or a free-form surface). A 1 / 4 wave plate is also attached to the surface facing the first surface. After the image light passes through the 1 / 4 wave plate and enters the second device, it is modulated and reflected on the semi-transparent and semi-reflective surface. After passing through the 1 / 4 wave plate again, it is modulated into P light and returns to the first device. It is emitted from the second surface through the first reflective surface and enters the viewer's eyes.When the system is a VR device, a metal reflective film can be prepared on the other surface of the second device to reflect all image light back. When the system is an AR device, the other surface of the second device can be uncoated or coated with an anti-reflection film. External ambient light can pass through the other surface of the second device, partially penetrate the semi-transparent and semi-reflective surface inside the second device, and then partially pass through the first device to enter the viewer's eyes. In this embodiment, the first and second sub-surfaces can also be coated with an anti-reflection film, so that the transmittance of light can reach more than 99% when it is emitted or incident from the first sub-surface and the second sub-surface, while not affecting the total reflection condition.

[0111] In a variation of the previous embodiment, the refractive index of the first sub-device is still lower than 1.60, and an angle-sensitive anti-reflection coating is further applied to the first surface. This coating provides a reflectivity of over 99% for light propagating through the medium at an incident angle greater than 30° on the first surface (although an incident angle of 30° is already lower than the angle of total reflection, the addition of this coating brings the reflectivity of light at an incident angle greater than 30° close to that of total reflection). Furthermore, light at an incident angle less than 30° still has a relatively high transmittance (e.g., light at an incident angle less than 25° within the waveguide has a transmittance of over 99%). In this variation, the vertex angle of the first sub-device can still be set at 20°, and the incident angle of the image light on the first sub-surface 101 after coupling into the first sub-device is between 50° and 70°. After experiencing total internal reflection, the light enters the first surface at an angle of 30° to 50°. Although light with an angle less than 38.68° no longer meets the total internal reflection condition, due to the presence of the angle-selective coating, light with an angle greater than 30° still has a reflectivity of 99%, thus being similar to having experienced total internal reflection. When the above light enters the first sub-surface again, the angle between it and the first sub-surface becomes 10° to 30°, which no longer meets the total internal reflection condition and will be emitted from the first sub-surface. The second sub-component includes a second sub-surface 102 that is identical to / complementary to the first sub-surface, with a 5um air gap between the two surfaces. Unlike the previous embodiment, the first reflective surface 103 in this example is the second sub-surface 102, and the angle between it and the second surface of the second sub-component is also 20°. A polarizing reflective film (or a semi-transparent and semi-reflective film) is prepared on the first reflective surface. After the image light is reflected by the first reflective surface, it will be incident on the first surface of the first sub-device again at an angle range of -10° to 10°. At this time, its incident angle on the first surface is less than 30°, and it will be emitted from the first surface. In this embodiment, the second device is a lens or a lens group, and the image light passes through the lens / lens group directly into the viewer's eyes. If the system is an AR device, a third device (such as a lens / lens group) can be added behind the second surface of the second sub-device to compensate for the impact of the second device on the ambient light, and can also compensate for errors such as myopia, hyperopia, and astigmatism in the viewer's eyes.

[0112] In the above embodiment, the image light can also be non-polarized light. In this case, the light that first enters the first reflective surface will be partially reflected and partially transmitted. The transmitted light will continue to propagate in the second sub-device. A light-absorbing material can be coated on the edge of the second sub-device to absorb it. This part of the light will not return to the original imaging optical path, and will not become stray light or ghost images to interfere with the imaging.

[0113] The coupling surface of the above embodiment may also be implemented by a reflector, such as the coupling surface in FIG3 , to couple the image light into the first sub-device, or a prism may be added to the image generation system to couple the light into the first device.

[0114] In another embodiment, the first device includes a first surface 104 and a second surface 108. Unlike the previous embodiment, the first reflective surface 103 and the first surface 104 are contiguous in this embodiment (as shown in FIG. 22 ). The first surface 104 and the second surface 108 form an angle of approximately 15°. After being coupled into the device, the image light first strikes the second surface at an angle of 68° to 88° with respect to the normal of the second surface. After being totally reflected by the second surface, it strikes the first surface, where its angle with the normal of the first surface is 38° to 58°. The refractive index of the first device is 1.67, and its total reflection angle is approximately 36.7°. The image light is then totally reflected by the first surface and strikes the second surface again, where its angle with the normal of the second surface is 23° to 43°. A dielectric layer (glue layer) with a refractive index of 1.36 and a thickness of less than 0.01 mm is placed between the second surface and the second device. As a result, the total reflection angle of the second surface is approximately 54.5°. At this point, the angle between the light and the second surface is less than the total reflection angle, and the light exits the second surface and strikes the second device. In this example, the second device is made of a material with the same refractive index as the first device. The second device includes a second reflective surface 201, which is a non-rotationally symmetric free-form surface or a section of a rotationally symmetric surface (if only a section is taken, the section itself is non-rotationally symmetric). After being modulated by the second reflective surface, the image light or a portion of the image light is reflected back to the first device. In this example, after being modulated by the second device, the angle between the image light and the normal of the second surface is further reduced, allowing it to pass through the second surface. At this point, the central light or the central light of the central field of view is nearly perpendicular to the first surface, allowing it to exit the first device. The second device itself consists of two parts (e.g., two cemented lenses with complementary surfaces), with the second reflective surface formed on one of the two complementary surfaces. The second reflective surface can be a polarized reflective surface (transmitting P light and reflecting S light) or a surface with a certain reflectivity (e.g., 25% reflection, 75% transmission). Furthermore, one surface of one of the two parts of the second device can be complementary to the second surface of the first device, and one surface of the other part can be parallel to or form a small angle with the first surface of the first device. In this example, since there is no reflective coating on the first reflective surface, when the image light and ambient light modulated by the second device are incident, since their incident angle is less than the total reflection angle, a very high transmittance (for example, >99%) can be achieved through the anti-reflection film.In a variation of this example, the material of the first device remains unchanged, the angle between the first and second surfaces is 20°, and the angle of the incident light remains unchanged. When the image light first strikes the first surface, its angle with the surface normal is 28° to 48°, leaving some light below the angle of total reflection. This problem can be addressed by applying an angle-selective reflective coating on the first surface, ensuring that light between 28° and 36.7° still has a reflectivity greater than 99%, while light below 25° has a transmittance greater than 90%. (Light with a 25° incident angle within the medium enters the air at an angle of 45°, meaning the perspective field of view is approximately 90°, which does not significantly affect observation of the external environment.) In this example, when the image light strikes the second surface for the second time, its angle with the second surface normal has been reduced to 8° to 28°. Even an air gap between the first and second devices does not affect normal light propagation. Generally, antireflection coatings can be applied to the first and second surfaces, as well as to the corresponding surfaces of the second device, to improve light transmittance. The surface of the second component facing the external environment can generally be configured to match the first surface (e.g., a parallel plane if the first surface is flat, or a curved surface with the same curve if the first surface is curved, or a curved surface that compensates for myopia, hyperopia, or astigmatism). This allows ambient light to pass through the entire system as if through a piece of flat glass, without affecting the viewer's viewing environment. Of course, these surfaces can also be configured to have a certain refractive power to compensate for myopia, astigmatism, and other issues in the viewer's eyes, thus acting as glasses.

[0115] In a variation of the above embodiment, the system's coupling is accomplished using an asymmetric curved reflective surface 105 (as shown in FIG23 ). This approach has the advantage of eliminating aberrations caused by the non-axisymmetric second reflective surface 105. Alternatively, other non-axisymmetric lenses / reflectors can be introduced into the system to eliminate these aberrations. In the above system, the lens / reflector assembly 302 and / or the coupling surface 105 can include a non-rotationally symmetric curved surface or curved reflective surface to compensate for aberrations caused by the non-rotationally symmetric second reflective surface 201.

[0116] Compared to existing Fresnel lens or Birdbath solutions, this system significantly shortens its length perpendicular to the human eye, significantly reducing the thickness of the optical machine. Compared to the PANCAKE solution, while maintaining a similar or even smaller thickness, the absence of a translucent, semi-reflective surface eliminates the 75% energy loss experienced by light passing through it twice. In most implementations, the system boasts several times the optical efficiency of the PANCAKE solution. Furthermore, compared to traditional Fresnel lens or PANCAKE solutions, the side-mounted imaging element allows for a transmissive system, enabling the viewing of ambient light, thus enabling MR / AR designs. Another advantage of this system over the PANCAKE solution is that, because the principal optical axis of the first reflective surface is angled with the first and second elements and the viewing direction of the eye, some image light that is not fully transmitted or reflected as designed is misreflected or transmitted, preventing it from entering the designed imaging optical path and forming ghost images. This significantly reduces the ghosting issue often associated with the PANCAKE solution.

[0117] In the description of this application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do 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 therefore cannot be understood as a limitation on this application.

[0118] The above describes specific embodiments of the present invention. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. The embodiments of this application and the features in the embodiments may be combined with each other in any manner unless there is a conflict.

Claims

1. An optical system, characterized in that: include: a first device and a second device; The first device comprises a first surface, the image light is coupled into the first device, and the image light undergoes at least one total reflection on the first surface after entering the first device; The first device further comprises a first reflecting surface, and the first reflecting surface couples the image light totally reflected by the first surface out of the first device; The image light coupled out of the first device is modulated by the second device, and the modulated image light is coupled into the first device again and partially or completely passes through the first reflective surface once or multiple times; or the image light is modulated by the second device and then emitted from the optical system.

2. The optical system according to claim 1, characterized in that The first device also includes a first sub-device and a second sub-device, the first sub-device includes a first sub-surface that is not parallel to the first surface, the angle between the light and the normal of the first sub-surface changes after the light undergoes at least one total reflection between the first surface and the first sub-surface, and is emitted from the first sub-surface, the second sub-device includes a second sub-surface and a first reflection surface or the second sub-surface is the first reflection surface, and the light emitted from the first sub-surface enters the second sub-device from the second sub-surface and is reflected by the first reflection surface or directly reflected by the first reflection surface.

3. The optical system according to claim 2, characterized in that The second sub-surface and the first sub-surface have the same or complementary surface shapes.

4. The optical system according to claim 2, characterized in that There is a gap between the second sub-surface and the first sub-surface, or a medium with a different refractive index is filled between the second sub-surface and the first sub-surface.

5. The optical system according to claim 2, characterized in that One or any combination of the following films is prepared on the first sub-surface and / or the second sub-surface: an anti-reflection film, an anti-reflection film, a wave plate, a hardened film, a polarized reflective film, a wavelength-based reflective film, a film with different refractive indices in different regions, a film with varying refractive indices in different regions, an angle-selective reflective film or an anti-reflection film.

6. The optical system according to claim 2, characterized in that The refractive index of the first sub-component and the second sub-component is the same or similar.

7. The optical system according to claim 2, characterized in that The first sub-component is a triangular or wedge-shaped waveguide.

8. The optical system according to claim 1, characterized in that When the image light is coupled out of the first device, the angle between the main optical axis of the optical path and the vertical axis of the first surface is less than ±40°.

9. The optical system according to claim 1, characterized in that There is a gap between the second device and the first device.

10. The optical system according to claim 1, characterized in that The first reflecting surface changes the angle of the image light so that the image light is emitted from the first device.

11. The optical system according to claim 1, characterized in that The first reflective surface includes a polarized reflective surface or a surface prepared with a film of preset reflectivity.

12. The optical system according to claim 1, characterized in that The first reflective surface includes a flat surface or a curved surface.

13. The optical system according to claim 1, characterized in that The first surface includes a flat surface or a curved surface.

14. The optical system according to claim 1, characterized in that Any one or more of the following films are prepared on the first surface: an anti-reflection film, an anti-reflection film, a wave plate, a hardened film, a polarized reflective film, a wavelength-based reflective film, a film with different refractive indices in different regions, a film with varying refractive indices in different regions, an angle-selective reflective film or an anti-reflection film.

15. The optical system according to claim 1, characterized in that The first device further includes a second surface, which is parallel to or at a preset angle to the first surface. After the image light undergoes at least one total reflection on the first surface and / or the second surface, it is reflected by the first reflection surface and coupled out of the first device.

16. The optical system according to claim 15, characterized in that Any one or more of the following films are prepared on the second surface: an anti-reflection film, an anti-reflection film, a wave plate, a hardened film, a polarized reflective film, a wavelength-based reflective film, a film with different refractive indices in different regions, a film with varying refractive indices in different regions, an angle-selective reflective film or an anti-reflection film.

17. The optical system according to claim 1, characterized in that The second device includes any one or more of the following devices: lens, super lens / super mirror, variable lens / variable mirror, liquid lens / liquid mirror, liquid crystal lens / liquid mirror, transmissive or reflective spatial light modulator, flat or curved mirror, microlens or micromirror array, reflective film or polarized reflective film with a certain reflectivity, wave plate, Fresnel mirror, grating, prism, mechanical motor, voice coil motor, electronic and mechanical structure that can change the position of the device.

18. The optical system according to claim 1, characterized in that The optical system also includes a third device, which includes any one or more of the following devices: a lens, a super lens / super mirror, a variable lens / variable mirror, a liquid lens / liquid mirror, a liquid crystal lens / liquid mirror, a transmissive or reflective spatial light modulator, a flat or curved mirror, a microlens or a micromirror array, a reflective film or a polarized reflective film with a certain reflectivity, a wave plate, a Fresnel mirror, a grating, a prism, a mechanical motor, a voice coil motor, and an electronic and mechanical structure that can change the position of the device.

19. The optical system according to claim 1, characterized in that The first device also includes a second surface. The image light is coupled into the first device again and partially or completely passes through the first reflection surface before being coupled out from the first or second surface.

20. The optical system according to claim 18, characterized in that The image light entering the third device is reflected by the third device and then enters the first device again.

21. The optical system according to claim 1, characterized in that The optical system includes an image generating system, and the image generating system includes any one or more of the following devices: a microdisplay, a spatial light modulator, a lens, a superlens / supermirror, a variable lens / variable mirror, a liquid lens / liquid mirror, a liquid crystal lens / liquid crystal mirror, a mirror, a polarized mirror, a prism, a microlens array, a grating, a polarizer, a wave plate, a Fresnel mirror, a mechanical motor, a voice coil motor, and electronic and mechanical structures that can change the position of the device.

22. The optical system according to claim 21, characterized in that The micro display includes any one or more of the following devices: OLED, LED, LCoS, LCD, DMD, LBS, CRT.

23. The optical system according to claim 21, characterized in that The image generated by the image generation system is located between the second device focal point or equivalent focal point and the second device.

24. The optical system according to claim 18, characterized in that The image generated after the image light is modulated by the second device is located between the focus of the third device or the equivalent focus and the third device.

25. The optical system according to claim 21, characterized in that The optical system adjusts the imaging distance by changing the physical position between devices or changing the diopter of the devices.

26. The optical system according to claim 1, characterized in that The angle between the main optical axis of the optical path of the image light once again coupled into the first device and the vertical axis of the first surface is less than ±40°.

27. The optical system according to claim 1 or 18, characterized in that The first and / or second device and / or the third device modulates the transmitted ambient light to compensate for the errors of myopia, hyperopia and astigmatism existing in the human eye.

28. The optical system according to claim 18, characterized in that The first device, the second device and the third device compensate each other, so that the optical parameters do not change after the ambient light passes through the entire system, or the optical parameters change as set.

29. The optical system according to claim 1, characterized in that The first device further includes a third surface, which is located at a side of the first device, and the image light is reflected back to the first device from the third surface.

30. The optical system according to claim 29, characterized in that The third surface is prepared with one or more of the following films: anti-reflection film, anti-reflection film, wave plate, polarized reflective film, wavelength-based reflective film, film with different refractive index in different areas, film with varying refractive index in different areas, angle-selective reflective film or anti-reflection film.

31. The optical system according to claim 1, characterized in that The second device has rotational symmetry.

32. The optical system according to claim 1, characterized in that The first surface of the first device is a plane or a curved surface.

33. The optical system according to claim 1, characterized in that The first device further comprises a second surface which is not parallel to the first surface, and after the image light or at least a part of the image light undergoes at least one total reflection between the first and second surfaces, the angle between the image light and the first and / or second surface changes, and the image light is emitted from the first surface and / or the second surface; The first reflective surface is the first or second surface.

34. The optical system according to claim 33, characterized in that The image light or at least part of the image light is emitted from the first surface or the second surface of the first device after experiencing at least one total reflection on the first surface and the second surface respectively.

35. The optical system according to claim 1, characterized in that The first device includes a curved surface, and the focus and / or center of the curved surface and at least one surface in the second device are at the same position or the distance between the two is less than a preset value, or both are on a specific image light or on its extended axis, or the distance between the two and the specific image light or its extended line is less than a preset value.

36. The optical system according to claim 1, characterized in that One surface of the first component is a curved surface, and the curved surface has the same surface shape as at least one surface of the second component, or the difference in surface shape is within a preset range.

37. The optical system according to claim 1, characterized in that The first device also includes multiple sub-devices, each of which includes at least one sub-surface that is not parallel to the first surface. After the light undergoes one or more total reflections between the one or more sub-surfaces, the angle between the light and the first surface or other sub-surfaces changes, and the light is emitted from one of the sub-devices, wherein one sub-surface of one of the sub-devices is the first reflection surface.

38. The optical system according to claim 1, characterized in that It also includes a detector, which is used to detect light coming from the viewer and / or light coming from the external environment.

39. The optical system according to claim 1, characterized in that Also included is a light emitter, which is used to emit light in the direction of a viewer and / or an external environment.

40. An optical device, characterized in that: An optical system comprising any one of claims 1 to 39.

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