Optical system and optical apparatus

Abstract

This invention provides an optical system and optical device, comprising: at least one concave reflecting / partial reflecting surface; and at least one convex reflecting / partial reflecting surface, and / or a concave transmitting / partial transmitting surface; the optical system further comprises a waveguide device, wherein during the propagation of light between the concave reflecting surface, the partial reflecting surface, or the convex reflecting surface, and / or the concave transmitting / partial transmitting surface, at least one total internal reflection occurs on the surface of the waveguide device. This invention proposes an optical system incorporating off-axis concave and convex reflecting surfaces (or concave transmitting surfaces) combined with a waveguide, which can effectively compensate for aberrations caused by large off-axis angles of light, achieving better optical performance.

Description

Technical Field

[0001] This invention relates to the field of optical components, and more specifically, to an optical system and optical device. Background Technology

[0002] In some optical applications, there are strict requirements regarding the size of optical systems. Examples include wearable AR / VR devices, automotive HUD devices, and mobile phone lenses (such as periscope lenses). The industry generally uses diffractive waveguides and arrayed waveguides to reduce system thickness. However, diffractive waveguides suffer from low optical efficiency, while the mass production feasibility and cost of arrayed waveguides also pose challenges. The industry urgently needs new optical solutions to simultaneously address the issues of performance, size, and cost.

[0003] Patent documents CN202010814795.5 and CN202311491615.4 describe optical systems that reduce the size of the optical path by combining waveguide devices with optical components such as lenses and mirrors. When further reduction in size and improvement in system optical efficiency are required, off-axis optical systems combined with waveguide devices can be considered. Generally, the larger the off-axis angle of the light rays, the smaller the system size tends to be. However, when the off-axis angle is large, the asymmetric off-axis light rays can pose a significant challenge to the optical performance of the imaging system (such as image quality). Summary of the Invention

[0004] In view of the deficiencies in the prior art, the purpose of this invention is to provide an optical system and optical device.

[0005] According to the present invention, an optical system includes at least one concave reflecting surface / partial reflecting surface (e.g., Figure 1 As shown, taking a concave reflecting surface 201 as an example, and at least one convex reflecting surface / partial reflecting surface (as shown). Figure 1 Taking a convex reflecting surface 301 as an example), and / or a concave transmitting surface (such as...) Figure 8 (307). The optical system also includes a waveguide device 10, in which light undergoes at least one total internal reflection at the surface of the waveguide system as it propagates between the concave reflecting surface / partial reflecting surface 201 and the convex reflecting surface 301 / partial reflecting surface and / or the concave transmitting surface. In some applications, the waveguide device 10 and the concave reflecting surface 201 are two separate devices (e.g., ...). Figure 1The device containing the concave reflector 201 is designated as 20). A gap exists between the concave reflector and the waveguide (the gap may be an air gap or filled with a low-refractive-index medium). After being reflected by the concave reflector 201, the light undergoes at least one total internal reflection on the surface 102 opposite to the device 20 containing the concave reflector 201 (or at least one total internal reflection on the surface 102 opposite to the device 20 containing the concave reflector 201 before incident on the concave reflector 201). In some embodiments, the light travels on both surfaces of the waveguide device (e.g., ...). Figure 1 The waveguide device 10 (101 and 102) reflects light once and / or twice. The concave reflecting surface refers to a surface where parallel light rays incident on it converge after reflection, while the convex reflecting surface refers to a surface where parallel light rays incident on it diverge (similarly, the concave transmitting surface refers to a surface where parallel light rays incident on it diverge, for example, parallel light rays propagating from the direction of the concave reflecting surface 201 will diverge upon incident). Generally, total internal reflection refers to reflection caused by an incident angle greater than the total internal reflection angle when light rays incident on the surface of the waveguide device 10 (generally, total reflection independent of the reflective coating). The concave and convex surfaces can be spherical, aspherical, part of a rotationally symmetric surface, freeform, Fresnel surfaces containing microstructures, microlens arrays, micromirror arrays, microprism arrays, metasurfaces with optical power (their shape can be planar or curved), grating devices (their shape can be planar or curved), equivalent curved surfaces composed of planar liquid crystal devices (dynamically modulated or non-dynamically modulated), and various other surface types. The light rays are generally image rays (containing image information). The waveguide device 10 can be a wedge-shaped, triangular, or curved prism in which the light undergoes total internal reflection, or it can contain multiple sub-devices (which may contain multiple wedge-shaped or triangular prisms, or multiple prisms with curved surfaces), with gaps between the prisms (air gaps or filled with a low-refractive-index medium). A reflective film or a partially reflective film (such as a metal reflective film, a dielectric reflective film, a polarizing reflective film, a film with a specific transmission and reflection ratio, a film that reflects a specific wavelength, a reflective film that reflects at a certain angle, etc.) is prepared on the reflecting surface or part of the reflecting surface.

[0006] Furthermore, the central ray of the incident light (in some applications, all rays or all effective / image rays) is not coaxial with the concave reflecting / partial reflecting surface. This coaxiality means that the central ray of the incident light (e.g., the central ray of a certain field of view or the entire field of view) is not parallel to the central axis 2011 of the concave reflecting / partial reflecting surface 201 (if it is a rotationally symmetric surface, the central axis is the axis of rotational symmetry; if it is not a rotationally symmetric surface, the central axis can be defined as the normal / perpendicular line of the tangent at a point on the surface); or the central ray of the central field of view of the incident light does not coincide with the central axis 2011 of the concave reflecting surface 201 (they can be parallel but there is an eccentricity); or all effective incident rays, after being reflected by the concave reflecting surface 201, are not parallel to the original incident rays (if there are rays in the incident light that are parallel to and coincide with the central axis of the reflecting surface, then there must be rays in the reflected light that are parallel to the original incident rays but propagate in the opposite direction). The purpose of setting a reflecting surface that is off-axis from the light rays (which can be all incident light rays) is to allow light rays that originally made an angle greater than the total internal reflection angle with a certain surface of the waveguide device 10 to be reflected by the concave reflecting surface 201 and then transmitted through the same surface, or to change the angle so that the light rays can be received or viewed by subsequent systems (in which case the light rays can also directly enter the subsequent system or be viewed without passing through the waveguide device 10); or to allow light rays that originally could pass through certain surfaces of the waveguide device 10 or had a small angle with the surface normal (not passing through the waveguide) to be reflected and coupled into the waveguide device 10 and then propagated by total internal reflection by certain surfaces. The concave reflecting surface 201 can be on a separate concave reflecting mirror or a surface inside the waveguide device 10.

[0007] Furthermore, the central ray of the light (in some applications this could be all rays or all effective / image rays) and the convex reflecting surface / partial reflecting surface (such as...) Figure 1 In this context, the convex reflecting surface 301 (with its central axis 3011) and / or the concave transmitting / partial transmitting surface are not coaxial with the light beam. The definition of the convex reflecting surface / partial reflecting surface or the concave transmitting / partial transmitting surface being coaxial with the light beam is similar to the definition of the concave reflecting surface being coaxial with the light beam. The convex reflecting surface / partial reflecting surface or the concave transmitting / partial transmitting surface can be a surface of the waveguide (such as an end face, integrally manufactured with the waveguide); or the convex reflecting surface / partial reflecting surface can also be a surface of the waveguide device (total internal reflection surface), on which the light beam is totally internally reflected (or reflected by a specific reflective film) while changing the optical power; or it can be a separate reflector or lens, with a gap between it and the waveguide device.

[0008] Furthermore, convex reflecting / partial reflecting surfaces and / or concave transmitting / partial transmitting surfaces are used to compensate for the aberrations (off-axis aberrations) caused by the concave reflecting / partial reflecting surfaces. The main purpose of providing concave reflecting / partial reflecting surfaces, as well as convex reflecting / partial reflecting surfaces and / or concave transmitting / partial transmitting surfaces, is to compensate for off-axis aberrations caused by their non-axis relationship with the light rays (especially the principal ray / central ray) (such asymmetric aberrations are often difficult to completely compensate for by an axisymmetric system).

[0009] Furthermore, the waveguide device includes at least two non-parallel surfaces (e.g., Figure 1 (Surface 101 and Surface 102). The waveguide device can be a wedge-shaped or triangular waveguide with a small light-in / out surface (end face) and at least two non-parallel surfaces (both are planes, or one is a plane and the other is a curved surface, or both are curved surfaces; non-parallel surfaces can be defined as the principal axes / rotational symmetry axes of the curved surfaces being non-parallel or non-coincident, or the angle of the same light ray after being reflected once by the two curved surfaces being different from that before being reflected). Alternatively, the in / out surface can be one of the non-parallel surfaces, or one of the non-parallel surfaces can serve as the in-surface and the other as the out-of-surface. After light enters from the coupling surface, it undergoes one or more total internal reflections on the surface of the waveguide device. Due to the non-parallelism of the two surfaces, the incident angle changes (reducing to below the total internal reflection angle), causing the light to exit from the surface. After being reflected by the concave reflecting surface 201, the angle between the light and the waveguide device surface further decreases, allowing it to be transmitted through both surfaces, thus completely exiting the waveguide device 10. Alternatively, after being reflected by the concave reflecting surface 201, the light can directly enter the subsequent system or the viewer's eye (based on the principle of optical path reversibility, the above light propagation process / direction can also be completely reversed, for example, when used as a camera module). If the surface generating total internal reflection is curved, it can be a convex reflecting surface (such as an off-axis convex reflecting surface), compensating for the off-axis aberrations caused or to be caused by the concave reflecting surface while allowing the light to propagate through total internal reflection. Alternatively, the coupling / exit surface (e.g., end face or surface) can be an off-axis concave transmitting / partial transmitting surface or a convex reflecting / partial reflecting surface (or a combination of a convex reflecting / partial reflecting surface and other surfaces, such as...). Figure 6 (Middle surface 301 and surface 303). The waveguide device may also include multiple non-parallel surfaces or multiple sub-devices, for example, composed of two or more triangular or wedge-shaped prisms (e.g., ...). Figure 5There is a gap filled with air or a low-refractive-index medium between a pair of opposing surfaces 103 and 104. Light can undergo total internal reflection on the surface of the sub-device, or it can first pass through the interface of the sub-device (or the sub-surface inside the waveguide), and then be totally reflected by the interface of the sub-device again after the incident angle changes due to the non-parallelism of the surfaces (the angle increases). (Or, based on the reversibility of the optical path, the above process can also be reversed, with the light first being totally reflected by the interface of the two sub-devices, and then the angle changes and it is transmitted through the interface again).

[0010] Furthermore, the principal axis or central axis of the surface containing the concave reflecting surface / partial reflecting surface is not perpendicular to at least one surface of the waveguide device (e.g., Figure 1 The principal axis / central axis 2011 of the concave reflecting surface and the waveguide surface 101). When the surface containing the concave surface is a rotationally symmetric surface (the concave surface itself can be non-rotationally symmetric, but only a part of the rotationally symmetric surface), its principal axis / central axis (central axis / rotational symmetry axis) is not perpendicular to one surface of the waveguide device, but there is no restriction on its perpendicularity to the other surface; it can be non-perpendicular, perpendicular, or nearly perpendicular.

[0011] Furthermore, the light rays incident on the concave reflecting surface / partial reflecting surface, are reflected or partially reflected, and then enter the waveguide device, undergoing at least one total internal reflection within the waveguide device; or the light rays undergo at least one total internal reflection within the waveguide device, exit the waveguide device, and then incident on the concave reflecting surface / partial reflecting surface, are reflected or partially reflected, and then exit the system. Other optical devices, such as lenses, may also be present outside the surface of the waveguide device. Figure 10 Lens 303 or a lens group is used to modulate light before it is coupled into the waveguide, or to modulate light emitted from the waveguide.

[0012] Furthermore, after passing through the waveguide device, the light enters the concave reflecting surface / partial reflecting surface, is reflected or partially reflected, and then re-enters the waveguide device, undergoing at least one total internal reflection within the waveguide device (e.g., Figure 10 Alternatively, the light undergoes at least one total internal reflection within the waveguide device before exiting the waveguide device, then incident on the concave reflecting surface / partial reflecting surface, is reflected or partially reflected, and re-enters the waveguide device, and is transmitted through the waveguide device. For example... Figure 1The light rays shown are totally reflected by a waveguide surface that is not perpendicular to the principal axis (central axis) 2011 of the concave reflecting surface 201. The angle of incidence decreases, and the light rays pass through another surface, exiting the waveguide and entering the concave reflecting or partially reflecting surface 201 (reflecting / partial reflecting mirror). After being reflected by the concave surface, because the principal axis 2011 of the concave surface is not parallel to the aforementioned surface, the angle of the light rays will be changed (the angle change is significant). The light rays can then re-enter and directly pass through all surfaces of the waveguide device 10, or be output at a more suitable angle to subsequent systems (lenses, lens groups, functional films, etc.) or be viewed by the human eye. Since the light path is reversible, the process or direction of the light propagation can also be completely reversed. Generally, in this system, the light rays entering the waveguide device and undergoing total internal reflection, or exiting the waveguide device after total internal reflection, are due to a change in angle, rather than a change in polarization direction, reflection, or reflection by a partially reflective film. Therefore, the system does not require additional polarizing reflective films (or reflective / partial reflective films) and waveplates, which can significantly improve system luminous efficiency and reduce costs. Of course, in some cases, a polarizing reflective film can be added to the surface of the waveguide device 10, and a waveplate can be added to the system to further enhance the optical properties and meet specific requirements. Alternatively, a wavelength-selective thin film (partial transmission, partial reflection, etc.) or an angle-selective thin film (light transmission at certain angles, light reflection at certain angles, which can be a dielectric coating or a grating-type thin film) can be added to meet specific requirements.

[0013] Furthermore, a gap exists between the waveguide device and the concave reflecting surface / partial reflecting surface. One surface of the device containing the concave reflecting surface is opposite to one surface of the waveguide device, and a gap exists between the two surfaces (e.g., Figure 1 The gap can be an air gap, or it can be filled with a certain medium (e.g., a low-refractive-index medium, with a refractive index lower than that of the waveguide device). Alternatively, different regions of the interface can be made of media with different refractive indices, or some regions can be air and some regions can be media. The aforementioned opposing surface shapes can be completely identical or different (e.g., ...). Figure 4 , Figure 7 It can be a plane or a curved surface (such as...). Figure 4 , Figure 7 The purpose of the gap is to allow the light reflected by the concave reflecting surface 201 to be completely reflected on the surface of the waveguide device 10 corresponding to the concave reflecting surface 201 (e.g., 102) and then by another inclined surface (a surface not perpendicular to the principal axis of the concave surface, e.g., surface 101), so that the light can be completely reflected on the surface of the waveguide device 10 corresponding to the concave reflecting surface 201 (e.g., surface 102). (According to the principle of reversibility of light paths, the outgoing and incoming directions of the light in the device can also be opposite.)

[0014] Furthermore, a gap exists between the convex reflecting surface / partial reflecting surface or the concave transmitting surface / partial transmitting surface and the waveguide device (e.g., Figure 8 , Figure 10 Alternatively, the convex reflective surface / partial reflective surface or concave transmissive surface can also be within the waveguide device, serving as a surface of the waveguide device. The convex reflective surface can also be a separate device. When it is a separate device (e.g., a single convex surface), its surface corresponding to the waveguide device can be directly fabricated and connected (by bonding / gluing, etc.) to the end face of the waveguide device, or a gap can exist between it and the end face of the waveguide device. This gap can be an air gap or filled with a low-refractive-index material. The advantage of having a gap is that it can filter stray light. Some light rays whose angles do not meet the conditions (e.g., design parameters) will be totally reflected by the gap surface and cannot enter or exit the waveguide device (e.g., ...). Figure 8 (As shown).

[0015] Furthermore, after the light enters the optical system, it first passes through the convex reflecting surface / partial reflecting surface, and is then reflected by another surface in the system (such as...). Figure 6 In some applications, surface 303 can also be fabricated on a separate device and bonded to the waveguide, or with a gap between it and the waveguide, and then incident again on the convex reflecting surface 301 and reflected by it; or the light entering the optical system is reflected by the convex reflecting surface / partial reflecting surface, then reflected by another surface in the system, and then incident again on the convex reflecting surface (e.g., ...). Figure 6 (The diagram illustrates the backlight path of the light source) and it passes through the convex reflective surface. For example... Figure 6 As shown, by introducing surface 303, light can be reflected multiple times within the space of waveguide device 10, further reducing the system volume. In some cases, a partial reflective film (such as a thin film with a certain reflectivity and transmittance, or a polarizing reflective film that transmits P-light and reflects S-light) can be fabricated on the convex reflective surface / partial reflective surface. If a waveplate (such as a quarter waveplate, or a waveplate fabricated on the surface of the independent device where surface 303 is located opposite the waveguide) and a reflective film layer (metal reflective film or dielectric reflective film) are fabricated on surface 303, then the light previously transmitted through the convex reflective surface 301 will be reflected (polarization properties changed) when it re-enters the convex reflective surface 301 after being reflected by surface 303, or the light previously reflected by the convex reflective surface 301 will be transmitted when it re-enters the convex reflective surface 301 after being reflected by 303. The convex reflecting surface 301 can be a convex surface (e.g., a surface coaxial or non-axial with the incident image light rays) for the light rays reflected by it, and the surface 303 can be a plane or a curved surface (e.g., a convex or concave surface, coaxial or non-axial with the image light rays).

[0016] Furthermore, the surface of the optical device is coated with a thin film with specific functions. The optical device refers to optical components included in a system such as waveguide devices, concave reflective / partial reflective surfaces (concave reflective / partial reflective mirrors), convex reflective / partial reflective surfaces (convex reflective / partial reflective mirrors), and concave transmittant / partial transmittant surfaces (concave transmittant / partial transmittant mirrors). The specific function coating refers to a thin film that changes the transmittance / reflection ratio of light (or specific light rays) on a surface, or a thin film that changes the optical properties of light (such as waveplates that change the polarization direction). Examples include antireflective coatings that increase light transmittance, thin films that increase the reflectivity of light incident at large angles on the surface of waveguide devices (thin films that make the light reflectivity of the surface of waveguide devices at large angles greater than 90% or even reach 100%), thin films that reflect specific wavelengths (e.g., making the reflectivity of incident light in certain wavelength ranges approach total internal reflection when incident at large angles), polarization reflective films, etc. One purpose of these thin films is to increase the transmittance of light incident on the surface of waveguide devices at small angles, and another purpose is to increase the reflectance of light incident on the surface of waveguide devices at large angles (light incident on the surface of waveguide devices at large angles refers to light with a large angle to the normal of the waveguide surface) (which serves a similar purpose to reducing the angle of total internal reflection of light under certain conditions).

[0017] Furthermore, the system also includes a planar lens / mirror or a dynamic lens. The planar lens / mirror can be a superlens / mirror (metasurface, etc.), a grating device, a near-planar microlens (spherical, aspherical, cylindrical, etc.) / microlens array, a microprism array, a liquid crystal lens / liquid crystal mirror, a Fresnel mirror, or other planar or near-planar devices with optical power. The dynamic lens / mirror is a lens / mirror that can be dynamically modulated by optical or electrical signals. For example... Figure 11 As shown, the system also includes a planar device 60 (superlens) to adjust the optical power. In AR applications, this allows viewers with myopia, hyperopia, or astigmatism to see corrected images, functioning as a spectacle lens. Device 60 can also be an optical component such as a Fresnel lens or a liquid crystal lens, or an electrically adjustable spatial light modulator (such as a phase-modulated LCoS or liquid crystal device) or liquid lens, enabling dynamic matching for people with different prescriptions or dynamic adjustment of the image display distance to achieve light field functionality. In some applications, it can also be a lens / lens group (such as... Figure 11 Device 302 in the figure serves as an optical device for dynamically adjusting the image imaging distance, while device 60 is used solely as a lens for correcting eye defects in the wearer. Alternatively, device 60 can be positioned on the other side of the system, modulating only the ambient light and not the image light. The above system can also be applied in reverse as a camera lens or module (such as an ultra-thin telephoto lens module in a mobile phone, or an eye-tracking camera in an AR / VR system).

[0018] Furthermore, the optical system includes multiple imaging devices. For example... Figure 12 As shown, the system includes imaging devices 401 and 402 (such as LCD, LCOS, DMD, OLED screen, Micro LED screen, MEMS SCANNER, etc.), and modulation device 302 includes a light-combining prism (polarizing prism or semi-transparent / semi-reflective prism) and a lens / lens group. When using LCoS, DMD, LCD, MEMS SCANNER, etc. screens, the system also includes a light source module (such as LD, LED, polarizing prism, X-prism, TIR prism, dichroic mirror, etc.). Imaging devices 401 and 402 can be set at different focusing positions to achieve an output image containing images at different imaging distances. The multiple imaging devices can also be display devices (such as LCD, LCOS, DMD, OLED screen, Micro LED screen, MEMS SCANNER, etc.) and photosensitive imaging devices (such as CMOS, CCD, film, etc.).

[0019] An optical device according to the present invention includes the aforementioned optical system.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] This invention proposes an optical system that combines a waveguide with an off-axis concave and a convex reflecting surface (or a concave transmitting surface), which can effectively compensate for aberrations caused by large off-axis angles of light, and achieve better optical performance while reducing system size. Attached Figure Description

[0022] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0023] Figure 1 This is a schematic diagram of a structure according to an embodiment of the present invention;

[0024] Figure 2 This is a schematic diagram of a structure according to an embodiment of the present invention;

[0025] Figure 3 This is a schematic diagram of a structure according to an embodiment of the present invention;

[0026] Figure 4 This is a schematic diagram of a structure according to an embodiment of the present invention;

[0027] Figure 5 This is a schematic diagram of a structure according to an embodiment of the present invention;

[0028] Figure 6 This is a schematic diagram of a structure according to an embodiment of the present invention;

[0029] Figure 7This is a schematic diagram of a structure according to an embodiment of the present invention;

[0030] Figure 8 This is a schematic diagram of a structure according to an embodiment of the present invention.

[0031] Figure 9 This is a schematic diagram of a structure according to an embodiment of the present invention.

[0032] Figure 10 This is a schematic diagram of a structure according to an embodiment of the present invention.

[0033] Figure 11 This is a schematic diagram of a structure according to an embodiment of the present invention.

[0034] Figure 12 This is a schematic diagram of a structure according to an embodiment of the present invention. Detailed Implementation

[0035] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0036] Example

[0037] like Figure 1As shown, an optical system and device / equipment for AR / VR / MR includes a concave reflective surface 201. In this example, surface 201 is a spherical reflective surface with a radius of curvature between 10 and 100 mm (or the concave surface can be a portion of a rotationally symmetric aspherical surface, or an asymmetric freeform surface). The material used is resin or glass with a refractive index between 1.3 and 2.0 (or materials with a higher refractive index, such as silicon carbide). The system includes a waveguide device 10, made of the same material as the concave reflector 20 containing the concave reflective surface 201. The waveguide 10 includes three working surfaces (transmitting or reflecting effective light): surface 101, surface 102, and surface 301. Surface 102 is opposite to surface 202 of the concave reflector 20, and a gap exists between the two surfaces (an air gap or a gap filled with low-refractive-index adhesive). In this embodiment, surfaces 101 and 102 are planar, and light undergoes at least one total internal reflection on each surface. The angle between the two surfaces of the waveguide is in the range of 5 to 45°. The convex reflecting surface 301 is spherical (or, in some applications, part of a rotationally symmetric aspherical surface, or an asymmetric freeform surface). The system also includes an imaging device 401, which can be a Micro OLED, LCoS, Micro LED, DMD / DLP, LCD, MEMS scanner, etc., or, when the device or device is for photographic or video applications, an optical sensor such as a CCD or CMOS. A lens / lens group 302 is included before the imaging device to modulate the light incident on the waveguide or the light emitted from the waveguide device 10 (adjusting optical power, correcting aberrations, etc.). The lens / lens group 302 may also include apertures, filters, waveplates, polarizing devices, etc. Alternatively, the lens / lens group 302 may also include an electronically adjustable spatial light modulator (such as a phase-modulated LCD or LCoS device) or a variable lens (such as an adjustable liquid lens) to dynamically adjust the imaging distance (light field display) or compensate for human eye defects (myopia, hyperopia, astigmatism, etc.). The system also includes a compensation device 21 for the concave reflector 20. One surface of the compensation device 21 has the same shape as the surface 201 of the concave reflector 20, and the two surfaces are bonded together (glued or bonded). The other surface 203 of the compensation device 21 has the same shape as the surface 101 of the waveguide device 10 (in this example, it is a plane, but in some solutions it can also be a curved surface, or the two surfaces have different optical powers). In this way, when ambient light 51 passes through the entire device, it is equivalent to passing through two surfaces of equal thickness, and the optical power does not change (in some applications, the optical powers of surfaces 101 and 203 can also be different, and the entire system also serves as glasses to correct vision).Specifically, in this embodiment, the light emitted by the Micro OLED imaging device 401 is modulated by the lens / lens group 302 and enters the waveguide device 10 from the surface 101. It is reflected on the convex reflective surface 301 (a metal reflective film or a dielectric reflective film is prepared on the surface 301). The convex reflective surface 301 is part of a rotationally symmetric surface (it can be a sphere or an aspherical surface, and the truncated convex reflective surface 301 can be non-rotationally symmetric). The rotational symmetry axis (central axis 3011) of the surface where the convex reflective surface 301 is located is not parallel to the principal ray 50 of the image light (the principal ray can refer to the central ray of the central field of view. In a rotationally symmetric optical system, it generally coincides with the optical axis of the system. Non-parallelism is similar to the tilt of the system). Alternatively, the principal ray 50 does not pass through the center point of the rotationally symmetric surface where the convex reflective surface 301 is located (similar to the discenter in a rotationally symmetric system. In an off-axis system, the central ray is generally discentered and / or tilted with the principal optical axis of the system). Because the convex reflecting surface 301 is off-axis from the image light rays, the image light rays modulated by the convex reflecting surface 301 will produce large off-axis aberrations (astigmatism, coma, distortion, etc.). In this example, after the image light rays are reflected by the convex reflecting surface 301, the angle of incidence is greater than the total internal reflection angle of surfaces 101 and 102 (the angle between the light rays and the normals of the surfaces 101 and 102 is greater than the total internal reflection angle). Therefore, the light rays will undergo two total internal reflections on surface 101 and one total internal reflection on surface 102. When the light rays are incident on surface 102 again, because there is an angle between surfaces 101 and 102 (~18° in this example), the angle of incidence of the light rays relative to surface 102 will decrease to below the total internal reflection angle. Therefore, the light rays can exit from surface 102 and enter the concave reflecting mirror 20, where at least part of the image light rays are reflected on the concave reflecting surface 201. A thin film with a certain reflectivity is prepared on the concave reflective surface 201 (e.g., 20% reflection, 80% transmission; in some waveguides used for non-transparent applications, it can also be 100% reflection). The surface of the concave reflective surface 201 is a rotationally symmetric surface (spherical or aspherical, or in some embodiments, an asymmetric freeform surface without an axis of symmetry). Its axis of rotational symmetry (central axis 2011) is off-axis (not parallel and / or eccentric) with the principal ray 50 of the image light. The angle of the reflected image light will be significantly changed, allowing it to exit through surfaces 101 and 102 of the waveguide device 10 (e.g., the principal ray 50 of the central field of view exits at an angle close to perpendicular to surface 101). The off-axis nature of the concave reflective surface 201 will also produce a large off-axis aberration, and the off-axis aberration produced by its concave surface shape is exactly complementary to the off-axis aberration of the convex reflective surface 301 (they cancel each other out or the off-axis aberration is greatly reduced). Meanwhile, as an AR / VR system, ambient light 51 can also be incident on concave reflector 20 through concave compensation mirror 21. On concave reflector 201, part of the ambient light (e.g., 80%) will pass through 201 and be combined with the image light before entering the viewer's eyes through the entire system.

[0038] In a variation of the previous embodiment, the imaging device 401 uses an LCoS (a beam combining prism with a light source and polarization in the system, or a front-illuminated LCoS with a waveguide homogenizing device, such as HIMAX's 7079FL). Since the LCoS is a polarizing device, a polarizing reflective film (such as a 3M APF or IQPE film with a reflectivity greater than 90% for S-light and most of the P-light is transmitted) can also be fabricated on the concave reflective surface 201. This can greatly improve the image light utilization rate while allowing ~50% of ambient light to pass through. In addition, reflective films for specific wavelength bands can be fabricated (such as reflecting 450, 532, and 650 nm while transmitting other wavelength bands). Combined with specific imaging devices (such as a laser light source + LCoS / DLP / MEMS Scanner), it is possible to improve the ambient light transmittance while providing image light utilization. Furthermore, films that reflect infrared wavelengths (such as those greater than 700 nm) can be fabricated to make it an infrared imaging device, serving as a transmitting and / or receiving device for a TOF or DOE structured light system. Since the light path is reversible, all light rays in this embodiment are reversible. If the imaging device 401 is replaced with a photosensitive device (or a photosensitive device such as CCD or CMOS is added to the system, or an image generating device such as OLED or LCOS is used at the same time as the photosensitive device), it can become an image shooting system (or have both shooting and projection imaging functions).

[0039] In one embodiment, the system includes a concave transmissive / partial transmissive surface (e.g., Figure 2 It includes a concave transmitting surface 307, but does not include a convex reflecting surface (or in some applications, it may include both a concave transmitting surface and a convex reflecting surface). The concave transmitting surface is off-axis from the central ray. The concave transmitting surface is a sphere or an aspherical surface (the surface on which it is located is a rotationally symmetric sphere or an aspherical surface, the part on which the concave transmitting surface itself is not rotationally symmetric, or the transmitting surface itself may also be an asymmetric freeform surface). The axis (if the surface on which it is located is a rotationally symmetric surface, then it is the axis of rotational symmetry; if it is not rotationally symmetric, it can also be defined as the change in the propagation direction of all rays / image rays / effective rays after passing through the concave transmitting / partial transmitting surface, i.e., there are no rays / effective rays / image rays that do not refract after passing through the concave transmitting surface) is eccentric and / or tilted from the central ray of the image, thereby compensating for off-axis aberrations caused by the off-axis concave reflecting surface.

[0040] In one embodiment, the system does not include a compensating mirror with a concave reflective surface (such as...). Figure 3This embodiment can be applied to applications where there is no need for ambient light transmission (e.g., periscope telephoto lenses in mobile phones) or applications where the optical system itself is not used as a combining device (e.g., automotive HUDs, where the combiner is the windshield); or in AR systems that transmit ambient light, the concave reflective surface 201 can be used as the base curve of the spectacle lens to modulate the incident ambient light, and the surface 101 can also be made curved (e.g. Figure 8 This allows the concave reflective surface 201, when superimposed on surface 101, to form a pair of glasses capable of correcting human vision (or surface 101 and the concave reflective surface 201 can have the same surface shape, making the system similar to a pair of plano glasses). In some applications, one surface 202 of the compensation device 21 of the concave reflective surface can be a curved surface (similar to the base curve of a spectacle lens), and a device 60 is added to one side of surface 101 of the waveguide device 10 (such as...). Figure 9 The surface 602 of the device 60 can be set to a curved surface with a certain curvature according to the requirements. In AR / VR applications, the device 60 can be a lens customized for different users to adapt to the myopia, hyperopia, astigmatism and other problems of different individuals.

[0041] In one embodiment, a gap exists between the convex reflecting surface 301 and the waveguide device 10 (e.g., Figure 4 The principal ray 50 (image ray) is reflected by the convex reflector 301 and enters the waveguide through the gap. Since the surfaces 101 and 102 of the waveguide device are not parallel, the image ray undergoes several total internal reflections, reducing the angle of incidence with the waveguide surface. It will then exit the waveguide device and be reflected by the concave reflector 201 of the concave reflector. In this example, the concave reflector 201 is opposite to the waveguide surface 102 (i.e., there are no other surfaces between the reflector 201 and the surface 102), with only an air gap (or filled with a low-refractive-index medium) in between. After the principal ray 50 in the center field of view is reflected back to the waveguide by the concave reflector 201, the angle of incidence with the waveguide surface is further reduced, and it will exit from the surface 101 at an angle perpendicular to the surface 101 or a small angle (e.g., the angle with the normal of the surface 101 is within ±25°). In this embodiment, light emitted by the display device at an excessively large angle will undergo total internal reflection (such as ambient light 51) at the interface between the convex reflectors and the waveguide (e.g., where there is an air gap in the middle), thereby preventing large-angle light that does not conform to the design from becoming stray light or ghosting and affecting normal imaging.

[0042] In one embodiment, the waveguide device includes multiple sub-surfaces / sub-devices (such as...) Figure 5In this example, the waveguide includes two sub-waveguide devices, sub-waveguide device 11 and sub-waveguide device 12, which each contain two opposing sub-surfaces, surface 103 and surface 104 (in this example, surface 103 and surface 104 have the same surface shape; in some applications, the surface shapes of the sub-surfaces can be different). The space between surface 103 and surface 104 is filled with a low refractive index medium (such as optical adhesive with a refractive index <1.4; in some applications, it can also be an air gap). In some applications, different refractive index media can be filled at different locations of the gap. For example, the area near the convex reflecting surface 301 is filled with a medium with a lower refractive index, such as a refractive index <1.36 or air, while the area away from the convex reflecting surface 301 is filled with a medium with a slightly higher refractive index, such as a medium with a refractive index ~1.4). After the image light is reflected by the convex reflecting surface 301, it enters the surface 103 of the sub-waveguide device 11. Since the incident angle is greater than the total reflection angle, the light will be totally reflected and enter the surface 102. Because the surface 102 and the surface 103 are not parallel, when the light is totally reflected by the surface 102 and then enters the surface 103 again, its incident angle will be less than the total reflection angle of the surface 103. After that, the light will pass through the surface 103 and the gap between the surface 103 and the surface 104 and enter the waveguide sub-device 12. After being totally reflected on the surface 101 (or it could be the surface...), the light will enter the sub-waveguide device 12. A reflective film (such as a polarizing reflective film or a partial reflective film) is prepared on 101. The light passes through surfaces 104 and 103 again. Due to the reduced incident angle, the light passes through surface 102 and then enters the concave reflector. After being reflected by the concave reflector 201, the light enters the waveguide again. Due to the change in angle (in some applications, a quarter-wave plate can be prepared on the surface of the concave reflector to change the polarization direction of the reflected light), the light passes through surfaces 102, 103, 104, and 101 and exits from the waveguide device 10.

[0043] In one embodiment, a polarization reflective film (reflecting S-beams and transmitting P-beams) is prepared on the convex reflective surface 301. The image light is polarized light, and the P-polarized image light, after being incident on the waveguide, first passes through the convex reflective surface 301 that reflects S-beams (e.g., ...). Figure 6 The propagation extends to surface 303, which can be a plane, or it can be a convex or concave surface. Figure 6 The middle surface 303 is concave. The convex reflecting surface 301, surface 303, and waveguide can be integrally fabricated on the same device body (e.g., through injection molding, compression molding, hot pressing, etc.), or they can be fabricated as two or three separate devices and then glued or bonded together. A quarter-wave plate and a metal or dielectric reflective film are fabricated on surface 303. P-polarized light passes through the quarter-wave plate, is reflected by the reflective film, and passes through the quarter-wave plate again, where it is modulated into S-polarized light. When it is incident again on the convex reflecting surface 301, the S-polarized light is reflected and enters the waveguide for total internal reflection propagation.

[0044] In one embodiment, one surface 102 of the waveguide device 10 is curved (e.g., ...). Figure 7The surface 102, together with the lens / lens group 302, the convex reflecting surface 301, and the concave reflecting surface 201, modulates the image light. A variation of this example may omit this feature. Figure 7 The convex reflecting surface 301 (or it can be a plane) in the middle, wherein the convex reflecting surface is... Figure 7 The surface 102 of the waveguide device. Surface 102 can also function as a concave lens (transmitting ambient light penetrating the waveguide and / or image light that does not meet the total internal reflection condition after being reflected by the concave reflective surface). In another embodiment, the convex reflective surface (which can also be a concave transmittant surface) can also be surface 101 (e.g., Figure 8 In some embodiments, both surface 101 and surface 102 of the waveguide can be curved surfaces to modulate light.

[0045] In one embodiment, such as Figure 8 The system shown includes a rotational symmetry axis (plane 307 is part of a rotational symmetry plane, such as...). Figure 8 The solid line and extended dashed line of 307 in the diagram represent the rotational symmetry plane (the central dashed line 3071 is the axis of rotational symmetry of the rotational symmetry plane). The concave lens 307 is not on the same axis as the principal ray of the image light (such as the central ray of the central field of view). The surface of the concave lens 307 opposite to the waveguide device 10 is flat, and there is a gap between them. The system also includes a lens / lens group 302 that modulates the light. In this embodiment, one surface 101 of the waveguide device 10 is curved (it can be convex or concave) and modulates the light. Surface 101 can also be configured to have the same surface shape as the concave reflective surface 201, so that when ambient light passes through the system composed of the concave reflective surface 201 and surface 101, it is equivalent to passing through a piece of glass of uniform thickness (similar to passing through a flat glass). Alternatively, surface 101 can have a different surface shape from the concave reflective surface 201, thereby modulating the ambient light and enabling the system to correct human vision (equivalent to wearing glasses for nearsightedness, farsightedness, or astigmatism). In addition, the surface 101 can be made with a specific curvature (such as the base curvature of the outer surface of the myopia lens, such as 50 degrees curvature) to fit the eyeglass lens that is further attached to the outside of the surface 101 to correct vision.

[0046] In one embodiment, a compensation device 21 is also bonded to the outer side of the concave reflecting surface 201, and a device 60 (compensation mirror, such as...) is attached to the outer side of the waveguide device surface 101. Figure 9 Surface 101 is convex, serving as both a waveguide surface and a convex reflector. Together with lens / lens group 302, concave reflector 201, and surface 602, it modulates the image light. Surface 202 of compensating mirror 21 has a specific curvature, which, combined with surface 602 of device 60, modulates ambient light, functioning as ordinary nearsighted or presbyopic glasses (and can also adjust astigmatism).

[0047] In one embodiment, the outer side of the surface 101 of the waveguide device 10 further includes a lens / lens group 303 (e.g., ...). Figure 10 Ambient light is modulated by lens / lens group 303 and enters the waveguide. After passing through the waveguide, it is modulated by concave reflector 201 and returns to the waveguide, propagating within the waveguide through total internal reflection. It exits from the side of the waveguide and enters a convex reflector. After being reflected by the convex reflector 301, it exits again, is modulated by lens / lens group 302, and is finally received by imaging device 401 (here, CMOS or CCD). This embodiment is an application of a camera lens (such as a periscope lens in a mobile phone). By reasonably setting the angle between the interface between the convex reflector and the waveguide and the waveguide surface, stray light at large angles can be totally internally reflected at the interface between the waveguide and the convex reflector and coupled out of the system (absorbed or emitted and unable to enter the imaging device), thereby filtering out stray light that may cause ghosting, glare, and other problems.

[0048] In one embodiment, the outer side of the surface 101 of the waveguide device 10 further includes a planar or ultra-thin device 60 with optical power. Device 60 can be a metalens (metasurface), or a planar or near-planar device such as a liquid crystal lens, microlens array, or Fresnel lens, which modulates the light output from the waveguide (image light and ambient light) without significantly increasing the thickness, thereby correcting vision (myopia, hyperopia, astigmatism, etc.). Device 60 can also be a dynamically adjustable device, such as a dynamically modulated liquid crystal lens, a phase-modulated spatial light modulator, or a liquid lens, thereby achieving dynamic matching for different viewers' vision. Furthermore, it can also achieve the function of dynamically adjusting the image distance in a light field display (302 can also be a dynamically adjustable device to achieve dynamic adjustment of the image distance).

[0049] In one embodiment, the optical system includes multiple imaging devices. For example... Figure 12As shown, the system includes LCoS imaging devices 401 and 402 (401 and 402 in the figure are LCoS modules, which may include sub-devices such as LED or laser light sources, polarizing prisms, etc., not shown in the figure, or can also be front-illuminated LCoS devices with waveguide homogenizing devices). The modulation device 302 includes a polarizing prism, which combines the image light emitted from 401 and 402 (e.g., 401 is set to output P-polarized light and 402 is set to output S-polarized light). After the two light rays enter the waveguide, they are reflected by the convex mirror 301 and undergo total internal reflection on the waveguide surfaces 101 and 102 respectively before exiting from surface 102. After being reflected by the concave mirror 201, they re-enter the waveguide and exit through surfaces 101 and 102. In this example, imaging devices 401 and 402 are positioned at different back focal lengths in the system, resulting in output image beams 51 and 52 having different virtual image distances. For instance, the virtual image formed by image beam 51 appears to the viewer at a distance of 15 meters, while the virtual image formed by image beam 52 appears at a distance of 1 meter. Multiple imaging devices can be further added to the system to generate images with more different focal lengths. This system can be applied to products requiring two or more focal lengths (such as multi-focal length HUD products or AR / VR glasses).

[0050] In a variation of the previous embodiment, the combiner of the modulation device 302 can also be a dichroic mirror or an X-prism (X-Cube combines light of different wavelengths / colors), thereby enabling images of different colors to be formed into virtual images at different or the same distance. Furthermore, Figure 12 The position of the imaging device 402 can also be set to be parallel to the plane of the paper. Figure 12 The image generating device can be positioned perpendicular to the paper surface (or at a position rotated by a certain angle around an axis perpendicular to the waveguide surface 103). Each image generating device can also be equipped with a separate modulation device (e.g., the light emitted by the image generating device passes through separate lenses, lens groups, waveplates, etc. before entering the combiner), thus bringing greater flexibility to images with different characteristics generated by different image generating devices.

[0051] The multiple imaging devices in the above embodiments can also be display devices (such as the aforementioned LCOS screen) and photosensitive imaging devices (such as CMOS, CCD, film, etc.).

[0052] In the description of this application, it should be understood that, based on the principle of optical path reversibility, the direction of light propagation in this invention and related embodiments is reversible. That is, by replacing light-emitting imaging devices such as OLEDs and MICRO LEDs (AR / VR, HUD applications) with light-receiving imaging devices such as CCDs, CMOS, and film, the same optical equipment can be used in reverse as photographic and video recording equipment (camera lenses, eye tracking, etc.), or photographic and video recording optical equipment can also be used as display devices, or a single device can simultaneously possess display imaging and photographic and video recording functions. The terms "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer" in this invention indicate the orientation or positional relationship based on the orientation or positional 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, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0053] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. An optical system, characterized in that, include: At least one concave reflective / partially reflective surface; In addition, at least one convex reflective / partial reflective surface, and / or a concave transmissive / partial transmissive surface; The optical system also includes a waveguide device, wherein, during the propagation of light between a concave reflecting / partial reflecting surface or a convex reflecting / partial reflecting surface, and / or a concave transmitting / partial transmitting surface, at least one total internal reflection occurs on the surface of the waveguide device.

2. The optical system according to claim 1, characterized in that, The central ray of the light is not coaxial with the concave reflecting / partial reflecting surface.

3. The optical system according to claim 1, characterized in that, The central ray of the light is not coaxial with the convex reflecting / partial reflecting surface and / or the concave transmitting / partial transmitting surface.

4. The optical system according to claim 1, characterized in that, The aberrations of the convex reflective / partial surface and / or the concave transmittance / partial transmittance surface are complementary to those of the concave reflective / partial reflective surface.

5. The optical system according to claim 1, characterized in that, The waveguide device comprises at least two non-parallel surfaces.

6. The optical system according to claim 1, characterized in that, The waveguide device comprises multiple sub-devices or sub-surfaces.

7. The optical system according to claim 1, characterized in that, The principal axis or central axis of the concave reflective / partial reflective surface is not perpendicular to at least one surface of the waveguide device.

8. The optical system according to claim 1, characterized in that, The light rays are incident on the concave reflective / partially reflective surface, and after being reflected or partially reflected, they enter the waveguide device and undergo at least one total internal reflection within the waveguide device; Alternatively, the light undergoes at least one total internal reflection within the waveguide device before exiting the waveguide device, then enters the concave reflective / partial reflective surface, is reflected or partially reflected, and exits the optical system.

9. The optical system according to claim 1, characterized in that, The light passes through the waveguide device and then enters the concave reflective / partially reflective surface. After being reflected or partially reflected, it re-enters the waveguide device and undergoes at least one total internal reflection within the waveguide device. Alternatively, the light undergoes at least one total internal reflection within the waveguide device before exiting the waveguide device, then enters the concave reflective / partial reflective surface, is reflected or partially reflected, and re-enters the waveguide device, and is transmitted through the waveguide device.

10. The optical system according to claim 1, characterized in that, There is a gap between the waveguide device and the concave reflecting surface / partial reflecting surface.

11. The optical system according to claim 1, characterized in that, There is a gap between the convex reflective / partial reflective surface or the concave transmittant / partial transmittant surface and the waveguide device.

12. The optical system according to claim 1, characterized in that, After the light enters the optical system, it first passes through the convex reflective / partial reflective surface, is reflected by another surface in the optical system, and then enters the convex reflective / partial reflective surface again and is reflected by the convex reflective / partial reflective surface. Alternatively, after the light enters the optical system, it is reflected by the convex reflective / partial reflective surface, then reflected by another surface in the optical system, and then enters the convex reflective / partial reflective surface again, passing through the convex reflective / partial reflective surface.

13. The optical system according to claim 1, characterized in that, The optical device surface is prepared with one or more of the following thin films: antireflective film, reflective film, polarizing reflective film, specific wavelength reflective film, reflective film for light at a preset angle, waveplate, grating film, and microstructure film.

14. The optical system according to claim 1, characterized in that, The optical system also includes one or more of the following optical devices: planar lens / mirror, modulated dynamic lens / mirror, superlens / mirror, microlens / micromirror, microlens array / micromirror array, microprism / microprism array, liquid crystal lens / liquid crystal mirror.

15. The optical system according to claim 1, characterized in that, The optical system contains multiple imaging devices.

16. An optical device, characterized in that, Includes the optical system according to any one of claims 1-15.

Images