Optical device, optical imaging system, and optical apparatus

Abstract

The invention provides an optical device, an optical imaging system and optical equipment, and the optical device comprises at least three surfaces: a first surface, a second surface and a third surface. Light can be transmitted between the first surface and the second surface and is reflected at least once on the first surface and / or the second surface, and the third surface can reflect the light; the third surface is not perpendicular to a surface perpendicular to the first surface and the second surface at the same time. The invention provides an optical path folding scheme (especially optical path folding in a waveguide system), which can orderly guide light to a relatively insensitive direction, can be applied to near-eye display systems such as AR / VR / MR and the like, and can also be applied to various imaging and non-imaging optical systems with strict requirements on volume sizes.

Description

Technical Field

[0001] The present invention relates to the field of optical elements, and in particular to an optical device, an optical imaging system and an optical equipment. Background Art

[0002] In some optical applications, there are often strict requirements on the volume of devices and systems, especially for the size of devices or systems in certain directions, but sometimes the size in other directions is relatively loose. For example, in AR / VR systems, there are often strict requirements on the system size in the thickness and height directions, but relatively loose in the width direction.

[0003] In traditional AR / VR systems, the image coupling-in / out plane is often parallel to the object plane where the display device is located (such as waveguide system, Pancake system, etc.), or at least the object plane where the display device is located shares a vertical plane with the coupling-in / out plane of the image coupling-in / out optical system (BB scheme, free-form surface scheme, etc.). However, the above directions are often extremely sensitive to size (thickness direction, height direction, etc.), which seriously affects the volume of the system (equipment). Summary of the invention

[0004] In view of the defects in the prior art, an object of the present invention is to provide an optical device, an optical imaging system and an optical equipment.

[0005] According to an optical device provided by the present invention (such as Figure 1 As shown), comprising at least three surfaces: a first surface 11, a second surface 21 and a third surface 31;

[0006] The light can propagate between the first surface 11 and the second surface 21 and experience at least one reflection on the first surface and / or the second surface (for example, total reflection or reflection by a specific coating), and the third surface 31 can reflect the light;

[0007] The third surface 31 is not perpendicular to the surface that is perpendicular to the first surface 11 and the second surface 21 at the same time. For example, the vertical surface is the side surface connecting the first and second surfaces on the device, or the vertical surface can be a virtual surface in space and does not exist in the actual device. The non-perpendicularity means that the absolute value of the angle between the vertical line of the third surface and the surface that is perpendicular to the first and second surfaces at the same time is greater than a certain angle (for example, at least greater than 1°, and for example, greater than 25° in some cases), so that the light will no longer contact (transmit or be reflected) the first and / or second surface after being reflected. In addition, it can be further specified that the third surface is not parallel to the vertical surface that is perpendicular to the first and second surfaces at the same time. In most cases, the first and second surfaces are not parallel, there is an angle between the first and second surfaces (the above angle generally meets the conditions: greater than 1° and less than 60°), the first and second surfaces can directly intersect with the third surface; or they may not directly intersect with the third surface, and there are one or more connecting surfaces connecting the three surfaces (the connecting surfaces may be parallel or non-parallel to each other, or they may be parallel to the first or second surface). In some applications, the first and / or second and / or third surfaces are planes. In some applications, the first and / or second and / or third surfaces may also be curved surfaces. When the surfaces are curved surfaces, the vertical plane may be defined as a plane that is perpendicular to a specific section plane. The specific section plane is a section plane at the intersection of the principal optical axis in the effective light (e.g., the principal light ray / central light ray in the central field of view of the image light ray) and the first and / or second surface. The section plane at the intersection of the principal optical axis and the third surface is not perpendicular to the above-mentioned vertical plane.

[0008] Preferably, the first surface is not parallel to the second surface, and the third surface is determined by:

[0009] The first surface or the second surface is rotated by a preset angle around a first axis in space, and then rotated by a preset angle around a second axis perpendicular to the first axis to obtain a third surface. For example, the first surface may not be parallel to the second surface. The first or second surface is rotated by an angle (the first axis) (which may be 1° to 179°) about the intersection of the planes where the first and second surfaces are located, and then rotated by an angle (the second axis) (which may be 1° to 179°) around another axis perpendicular to the above axis, and then the obtained surface is translated and the boundary is defined to obtain the third surface. In some embodiments, if the angle between the first and second surfaces is θ, Figure 1 , the first surface (or second surface) can be rotated 2θ (or within the range of 2θ±30°, if the first and second surfaces do not intersect, it can also be rotated around the intersection of the planes where the first and second surfaces are located), and then rotated 45° (or within the range of 45°±30°) around a straight line perpendicular to the first or second surface as an axis, and then the third surface can be obtained by translating the obtained surface and limiting its range. The order of the above steps can be interchanged to obtain the same or similar results.

[0010] Preferably, the first axis may be an intersection line of the first surface and the second surface (or the planes where the surfaces are located).

[0011] Preferably, the optical device further comprises: a fourth surface 41, and the light is incident on and / or emitted from the optical device from the fourth surface. The light is an image light, and the fourth surface is perpendicular to the principal optical axis (principal ray) of the central field of view of the image light, or the angle between the fourth surface and the principal optical axis of the central field of view of the image light (the angle between the principal optical axis and its projection on the surface) is greater than 30°. For example, in a centrosymmetric application, the principal ray (principal optical axis) of the central field of view of the image light is incident on or emitted from the fourth surface perpendicularly. In some non-centrosymmetric systems, the principal ray of the central field of view of the image may also form a certain angle (for example, in the range of ±30°) with the vertical axis of the fourth surface.

[0012] Preferably, the light is an image light, and the optical axis of the fourth surface is perpendicular to the principal optical axis (central light) of the central field of view of the image light, or the angle between the optical axis of the fourth surface and the principal optical axis of the central field of view of the image light is greater than 30°.

[0013] Preferably, the optical device further comprises one or more connecting surfaces, wherein the connecting surfaces connect the third surface with the first surface and / or the second surface. For example, the third surface does not intersect with the first and / or the second surface, and there is a connecting surface that intersects with the third surface and the second surface at the same time, such as Figure 4 In some applications, there may be another connecting surface intersecting the third surface and the first surface. The connecting surfaces may be parallel or non-parallel to each other, and may be parallel or non-parallel to other surfaces.

[0014] Preferably, the third surface satisfies the following conditions:

[0015] The light is incident on the third surface after experiencing the same number of reflections on the first surface and the second surface; or, after being reflected by the third surface, the light is incident on the first surface and the second surface. The same number of reflections means that all light rays are reflected x times (such as 1 time) on the first surface and y times (such as 0 times) on the second surface. x may be equal to y or may not be equal to y. In some applications, after the effective light (such as imaging light) is incident on the device, it is reflected once on the first and second surfaces respectively and then incident on the third surface, wherein the reflection on the first surface is total reflection caused by the incident angle of the effective light being greater than the total reflection angle. If the device includes a connecting surface, the above constraints may also apply to the connecting surface, that is, the effective light also experiences the same number of reflections on the connecting surface (all 0 times, all 1 time or all multiple times).

[0016] Preferably, the optical device is composed of a plurality of sub-devices, for example, a plurality of prisms, and the surfaces of the plurality of prisms form the first, second and third surfaces, and the surfaces may also be curved surfaces.

[0017] Preferably, the optical device further comprises a fifth surface, and the fifth surface satisfies the following conditions:

[0018] Two parallel light beams in the optical device are respectively reflected by different surfaces before entering the third surface, wherein the light beam that was previously reflected by the preset surface before entering the third surface does not enter the fifth surface, and the light beam that was previously not reflected by the preset surface enters the fifth surface (i.e., in some applications, the light beam must be and only be reflected by the fifth surface or the preset surface), and the light beam that enters the fifth surface is parallel to the light beam that did not enter the fifth surface (after being reflected by the third surface) after being reflected by the fifth surface;

[0019] And / or, two beams of parallel light in the optical device are respectively reflected by different surfaces after being emitted from the third surface, among which the light reflected by the fifth surface and then reflected by the third surface will not be reflected by the preset surface (referring to the first reflection after emitting from the third surface is not reflected by the preset surface, and can still be reflected by the preset surface after being reflected by other surfaces), the light that is not reflected by the fifth surface but directly reflected by the third surface will be reflected by the preset surface (that is, in some applications, the light must be and only reflected by the fifth surface or the preset surface), and the light reflected by the preset surface is parallel to the light that is not reflected by the preset surface after being reflected by the preset surface (generally referring to the light reflected by the preset surface after the first reflection after emitting from the third surface, that is, the light reflected by the preset surface is parallel to the light that is not reflected by the preset surface but directly reflected by the third surface after being reflected by the preset surface).

[0020] For example Figure 2 As shown, the device comprises a fifth surface 51. The configuration of the fifth surface satisfies at least one of the following conditions:

[0021] Two parallel light beams in the device become non-parallel after being reflected by different surfaces before being incident on the third surface (generally referring to the last reflection before being incident on the third surface, such as two parallel light beams being reflected by the first and second surfaces respectively, or different connecting surfaces, or connecting surfaces and surfaces), wherein the light reflected by a specific surface (such as the first surface) before being incident on the third surface does not enter the fifth surface (does not contact the fifth surface), and the light that was not reflected by the specific surface before is incident on the fifth surface, and the light incident on the fifth surface is still parallel to the light reflected by the third surface but not incident on the fifth surface after being reflected by the fifth surface;

[0022] Or two parallel light beams in the device (such as Figure 2The light 711, 712) is respectively reflected by different surfaces after being emitted from the third surface 31 (here generally refers to the first reflection after being emitted from the third surface, such as reaching the first surface 11 and the second surface 21 respectively and being reflected by the first and second surfaces respectively, or it can also reach different connecting surfaces, or connecting surfaces and surfaces), wherein the light 712 reflected by the fifth surface 51 and then reflected by the third surface will not be reflected by a specific surface (for example, not reflected by the first surface 11, and directly incident on the second surface 21), and the light 711 that is directly reflected by the third surface without being reflected by the fifth surface will be reflected by a specific surface (such as 11), and the light 711 reflected by the specific surface 11 is still parallel to the light 712 that is not reflected by the specific surface 11 after being reflected by the specific surface 11.

[0023] Preferably, the optical device comprises a plurality of first surfaces and / or second surfaces. Figure 5 , Figure 6 As shown, in some applications, the device may include a first surface 11 and two second surfaces 211, 212 (for example, both second surfaces are not parallel to the first surface, and the two second surfaces may be parallel or non-parallel), such as the effective light is reflected by the third surface and then incident on one second surface 212, reflected by the second surface 212 (such as total reflection) and then incident on the first surface 11, reflected by the first surface 11 (such as total reflection) and then incident on another second surface 211, and reflected by another second surface 211 and then emitted through the first surface 11, that is, it experiences one reflection on each of the two second surfaces and the first surface. If the device includes a connecting surface, the above constraints can also be applied to the connecting surface, that is, the effective light also experiences the same number of reflections on the connecting surface (all experience 0 times, or all experience 1 time or more).

[0024] Preferably, the light is coupled into and out of the optical device multiple times. Figure 3 As shown, light is coupled into the device from the fourth surface 41. All light (effective light) is reflected by the third surface 31 and then incident on the first surface 11, and then reflected by the first surface 11 (it can be total reflection, or a specific reflection film can be prepared on the first surface) and then incident on the second surface 21, and then reflected by the second surface and then emitted through the first surface, and then incident on another optical device 91 (such as a semi-transparent and semi-reflective mirror) in the system, and then modulated and reflected (effective light is reflected) and then incident on the device again through the first surface 11, and then emitted from the optical device (such as entering the eyes of the viewer) after passing through the first surface 11 and the second surface 21.

[0025] Preferably, at least one surface of the optical device is prepared with one or more of the following films:

[0026] Anti-reflection film, dielectric reflective film, metal reflective film, polarized reflective film, angle selective reflective film, wavelength selective reflective film, grating. For example, an anti-reflection film is prepared on the first surface, which can increase the transmittance of light when it is emitted from or incident on the first surface, but the anti-reflection film will not affect the light that is totally reflected on the first surface. For example, an anti-reflection film and a polarized reflective film are prepared on the second surface, which can reflect light in a specific polarization direction and increase the transmittance of the transmitted light. For another example, an anti-reflection film and an angle selective film layer (low refractive index medium or multi-layer dielectric film) are prepared on another second surface (which can be a surface inside the device), so that light with an incident angle less than a certain value can pass through the above surface with a very high transmittance, while light with an incident angle greater than a certain value can be totally reflected.

[0027] An optical imaging system provided according to the present invention includes the optical device. The light is an image light, and the image light is focused at least once in the system (such as in the optical device) (forming an intermediate image plane). For example, the image light is emitted from an imaging device (such as OLED, MicroLED, LCD, LCoS, DMD, MEMS SCANNER, etc.) and coupled into the optical device (such as coupled into through the fourth surface) after modulation (such as lens reflector, etc.). After being reflected by the third surface, the image light is focused once in the device to form an intermediate image plane (it can also be focused before being reflected by the third surface or part of the light is focused before being reflected by the third surface and part of the light is focused after being reflected by the third surface to form an intermediate image plane). The intermediate image plane is a real image formed by focusing the light in the internal space of the device. The image of the intermediate image plane can have a certain aberration to compensate for the aberration that may be generated by subsequent devices. After being reflected and transmitted by the first and second surfaces, the image light is coupled out from the device and enters other components of the system (such as a semi-transparent and semi-reflective mirror) and is modulated into a virtual image at a farther distance.

[0028] An optical device provided according to the present invention comprises the optical device.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The present invention provides an optical path folding scheme (especially optical path folding in a waveguide system), which can guide light in an orderly manner to a relatively insensitive direction. The scheme can be applied to near-eye display systems such as AR / VR / MR, and can also be applied to various imaging and non-imaging optical systems with strict requirements on volume size. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0032] Figure 1A schematic diagram of the structure of an embodiment of the present invention;

[0033] Figure 2 A schematic diagram of the structure of an embodiment of the present invention;

[0034] Figure 3 A schematic diagram of the structure of an embodiment of the present invention;

[0035] Figure 4 A schematic diagram of the structure of an embodiment of the present invention;

[0036] Figure 5 A schematic diagram of the structure of an embodiment of the present invention;

[0037] Figure 6 A schematic diagram of the structure of an embodiment of the present invention;

[0038] Figure 7 The figure is a schematic structural diagram of an embodiment of the present invention. DETAILED DESCRIPTION

[0039] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments 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 of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0040] like Figure 3As shown, an AR / VR imaging system includes multiple optical devices, one of which includes a first surface 11, a second surface 21, a third surface 31, and a fourth surface 41. The optical device is a single prism including the first, second, third, and fourth surfaces, wherein an anti-reflection film is prepared on the first surface 11, a polarized reflective film is prepared on the second surface 21 (an anti-reflection film may also be added), a dielectric reflective film or a metal reflective film is prepared on the third surface 31, an anti-reflection film is prepared on the fourth surface 41, and the third surface intersects with the first and second surfaces. The first surface and the second surface form an angle of 25°, and the third surface is the first surface rotated 50° (or rotated to an angle within a range of 50±15°) around the intersection of the plane where the first surface is located and the plane where the second surface is located, and then rotated 45° around the vertical axis of the first surface (or rotated to an angle within a range of 45±20°, or can also be rotated to a certain angle around a straight line in the first surface that is perpendicular to the intersection of the first and second surfaces), and then translated to obtain the third surface (such as translating to a suitable position and taking the part of the surface surrounded by the intersection of the first and second surfaces in the plane as the third surface). The order of the above rotation and translation can also be interchanged, and the same surface can be obtained after adjusting the relevant parameters. The system also includes a Micro OLED screen (such as 0.6 inches), and the image light emitted by the OLED screen is modulated by a series of lenses / reflector groups 81 and coupled into the optical device from the fourth surface (the main light of the central field of view is perpendicular to the fourth surface), and the plane where the fourth surface is located is perpendicular to the planes where the first and second surfaces are located. The light (effective light) coupled into the device is reflected by the third surface and then incident on the first surface. At this time, the angle between the light (effective light) and the normal of the first surface is greater than the total reflection angle (for example, the optical device is made of a material with a refractive index of 1.54, and the medium outside the first surface is air, and its total reflection angle is about 40.5°). After the light is reflected by the first surface (total reflection, or an angle and / or wavelength selective reflection film or a polarization reflection film is prepared on the first surface), it is incident on the second surface. A reflection film is prepared on the second surface (for example, 3M's IQPE or APF type polarization selective reflection film, or an angle and / or wavelength selective reflection film is prepared on the second surface). After the light is reflected by the second surface (for example, input The light is linearly polarized light in the S direction and is reflected by the second surface prepared with a polarizing reflective film). Since the second surface is not parallel to the first surface, the angle between the image light reflected by the second surface and the first surface will be smaller than the total reflection angle, and thus it will be emitted from the first surface (an anti-reflection film can be prepared on the first surface). There is also a semi-transparent and semi-reflective mirror 91 (spherical, aspherical or free-form surface) in the system. There is a gap (air or low refractive index medium) between the semi-transparent and semi-reflective mirror and the first surface. After the image light is emitted from the first surface, it will be incident on the semi-transparent and semi-reflective mirror, and a part of it will be modulated (the image light is modulated into a virtual image at a longer distance, which is equivalent to the human eye seeing a magnified image in the distance) and then reflected and then enter the optical device through the first surface again.A quarter wave plate is prepared on the surface of the semi-transparent and semi-reflective mirror corresponding to the first surface. When the light is reflected from the semi-transparent and semi-reflective surface back to the optical device, it has been modulated into P light, and will pass through the first and second surfaces, and then enter the human eye after passing through the compensation device opposite to the second surface.

[0041] The system may also include a compensating prism and / or a compensating lens. One surface of the compensating prism (whose refractive index is generally the same as that of the optical device) corresponds to the second surface 21 and is connected to the second surface by gluing or bonding. The other surface of the compensating prism is parallel to the first surface 11, so that the light passing through the first and second surfaces is equivalent to passing through a piece of flat glass after passing through the compensating prism, and will not deflect the light like an angled prism. Alternatively, the other surface of the compensating prism may also be a curved surface, and the image light (including the light emitted by the screen and the light transmitted from the external environment) is equivalent to passing through a spectacle lens after passing through the above surface, which can change the imaging distance of the image and compensate for the defects of the human eye (myopia, hyperopia, astigmatism, etc.). Alternatively, the other surface of the compensating prism may be the same as the curved surface of the curved semi-transparent and semi-reflective mirror, so that the external ambient light passing through the system is equivalent to passing through a device of equal thickness everywhere, which is equivalent to a lens without optical focal length (or the two curved surfaces may have different optical focal lengths, which is equivalent to passing through a spectacle lens with optical focal length).

[0042] The above system may also include a compensation lens, one surface of which is the same or similar to the semi-transparent and semi-reflective mirror, and is connected to the semi-transparent and semi-reflective mirror by gluing or bonding, and the other surface of the compensation lens is a plane, so that the ambient light passes through the compensation lens and the semi-transparent and semi-reflective mirror like passing through a piece of flat glass (when there is no compensation prism, the plane surface of the compensation lens is parallel to the second surface, and when there is a compensation prism, it is parallel to one surface of the compensation prism); or the other surface of the compensation lens is a curved surface, and the ambient light passes through the above surface, which is equivalent to passing through the lens of glasses, and the distance of the ambient light imaging can be adjusted to compensate for the defects of the human eye (myopia, hyperopia, astigmatism, etc.). The surface shapes of the above compensation prism and compensation lens can also be combined with each other to compensate for the defects of the human eye and adjust the distance of the image at the same time, or to adjust the image distance in combination with adjusting the distance of the screen or lens group (for example, only adjusting the displayed image, not adjusting the distance of the ambient light), and can also be combined with devices such as variable lenses and SLM to realize the light field display function.

[0043] In the above embodiment, the optical device may also be formed by splicing (bonding or gluing) two or more prisms.

[0044] like Figure 7As shown, in a modified example, the difference from the above-mentioned embodiment is that the optical device includes two fourth surfaces (411, 412), and a polarized reflective film is prepared on the third surface 31. After the image light emitted by the display screen passes through the lens group 81 (there is a polarizing filter in the lens group, and the emitted image light is P light), it enters the optical device from the first fourth surface 411, passes through the third surface 31, and exits from the second fourth surface 412. A 1 / 4 wave plate and a curved reflector 101 (spherical, aspherical or free-form surface) are prepared outside the second fourth surface. After the light is reflected by the curved reflector, it passes through the 1 / 4 wave plate again and is coupled into the optical device from the second fourth surface 412 again. At this time, the image light has been converted into S light, which will be reflected by the third surface and then enter the first and second surfaces and be modulated by subsequent devices.

[0045] like Figure 4 As shown, in a variation, in addition to the first, second, third and fourth surfaces, the optical device also has a connecting surface 61. The connecting surface in this example is a surface that is parallel to the first surface and connects the second and third surfaces (it can also connect to the fourth surface, and to the surface of the aforementioned compensation prism facing the outside world / viewer, or the connecting surface and the surface of the aforementioned compensation prism facing the outside world / viewer are the same surface). All effective light or part of the effective light can be reflected by the connecting surface once or several times after being reflected by the third surface (in some examples, the light may not contact the connecting surface), and then enter the first or second surface. In another variation of the embodiment, two or more connecting surfaces may be included, connecting the first surface with the third surface, and the second surface with the third surface respectively.

[0046] A variation is a non-see-through VR system, in which a polarized reflective film (transmitting P light and reflecting S light) is prepared on the first surface, and a quarter wave plate and a high-reflectivity dielectric reflective film (such as a reflectivity > 99.9%) or a metal reflective film is prepared on the second surface. The light (S polarized light) is reflected by the third surface and then incident on the first surface (due to the presence of the polarized reflective film, the angle of the incident light can be made smaller, and there is no need to consider whether it is greater than the total reflection angle). After being reflected by the first surface, it is incident on the second surface, and after being reflected by the second surface and passing through the quarter wave plate twice, it is modulated into P polarized light and then incident on the first surface again and emerges. In this embodiment, the system also includes a semi-transparent and semi-reflective mirror device (similar to Figure 5 Figure 6The device 91 in FIG. 1 is composed of a reflector having a flat surface (prepared with a quarter wave plate and a polarized reflective film) and a curved surface (prepared with a semi-transparent and semi-reflective film), and a compensating mirror having a flat surface (prepared with a quarter wave plate) and a curved surface complementary to the semi-transparent and semi-reflective mirror (the compensating mirror and the reflector are made of the same material). The compensating mirror and the reflector are glued (the curved surfaces are glued) into a whole. The light (P polarized light) is emitted from the first surface and then enters the flat surface of the compensating mirror and is reflected by 1 The 1 / 4 wave plate is modulated into circular polarization, and the effective light passing through the semi-transparent and semi-reflective surface (the semi-transparent and semi-reflective mirrors have the same or similar refractive index as the compensation mirror, so the light passing through the curved surface is similar to propagating in a uniform medium and will not be modulated by the curved surface) enters the 1 / 4 wave plate and is modulated into S light and reflected by the polarized reflective film. After that, the effective light reflected by the semi-transparent and semi-reflective curved surface (modulated into a virtual image at a farther distance) will pass through the 1 / 4 wave plate again and be modulated into P light, and then be emitted from the polarized reflective film into the viewer's eyes. In the above embodiment, after the image light is emitted from the screen and modulated by the lens group, it can be focused once in the optical device to form an intermediate image plane, such as focusing near the third surface, or between the first and second surfaces. The advantage of the existence of an intermediate image plane is that the FOV size of the image entering the human eye can be independent of the screen size, thereby achieving the decoupling of the field of view angle and the screen size, and realizing a small screen with a large field of view, thereby reducing system costs. The above embodiment can also remove the polarized reflective film on the first surface, remove the 1 / 4 wave plate and the reflective film on the second surface, only prepare the polarized reflective film on the second surface, and then add a compensation prism to make an MR system. The P light in the ambient light can enter the human eye through the two layers of polarized reflective film and the semi-transparent and semi-reflective surface.

[0047] like Figure 5 , Figure 6As shown, in one embodiment, the device includes two second surfaces 211 and 212, wherein the first second surface 211 has an angle of 20° with the first surface 11, the second second surface 212 has an angle of 14° with the first surface 11, and an angle of 6° with the first second surface 211, and the two second surfaces are perpendicular to the same plane (which can be a virtual plane in space) with the first surface. The third surface 31 can be obtained by the following method: first, the first surface (or a second surface) is rotated 68° (or an angle within the range of plus or minus 10°) around the intersection of the plane where the first surface is located and the plane where the first second surface 211 is located (it can also be the intersection with the plane where the second second surface is located, or the intersection of the two second surfaces and the first surface is the same straight line), and then the obtained plane is rotated 45° (or an angle within 45±30° according to the system design) around a perpendicular line of the first surface, and finally translated to a suitable position to obtain the third surface (such as the partial surface enclosed by the intersection line of the obtained plane after translation and the first and second surfaces is appropriately intercepted, or the partial surface enclosed by the intersection line of the intersection surface is appropriately intercepted). The optical device is formed by splicing two prisms with a refractive index of 1.67. The first prism includes a first surface 11, a third surface 31, a fourth surface 41 and a second second surface 212. The second prism includes a first second surface 211 and a complementary surface with the same surface shape as the second second surface 212. There is a gap between the complementary surface and the second second surface 212 (such as an air gap of 0.05 mm or a gap filled with glue with a refractive index of 1.38, or a reflective film with angle selectivity), and an anti-reflection film is prepared between the complementary surface and the second second surface 212. Anti-reflection films are also prepared on the first surface and the fourth surface, a polarized reflective film is prepared on the first second surface 211, and a reflective film is prepared on the third surface 31. The light (which can be filtered into S-polarized light) is coupled into the optical device from the fourth surface and reflected by the third surface, and then enters the second second surface 212. At this time, its incident angle is greater than the total reflection angle (there is a low-refractive index glue or air gap or an angle selective reflection film that reflects large-angle light between the second surface 212 and the corresponding compensation surface), and will be reflected by the second surface 212 (such as total reflection). After being reflected to the first surface 11, its incident angle is still greater than the total reflection angle (there is an air gap or a low-refractive index glue gap or an angle selective reflection film that reflects large-angle light outside the first surface). After being reflected, since the first surface 11 is not parallel to the second surface 212, when the light reaches the second surface 212 again, the incident angle of the light is less than the total reflection angle and will be transmitted from the second surface 212, pass through the compensation surface and enter the first second surface 211. The polarized reflection film on the first second surface 211 will reflect the S-polarized light back. The reflected light passes through the second surface 212 again and reaches the first surface. At this time, the angle between it and the first surface 11 is less than the total reflection angle and will be emitted from the optical device.In the above embodiment, for the convenience of manufacturing, the prism including the first surface 11, the second second surface 212, the third surface 31, and the fourth surface 41 can also be formed by splicing two or more prisms. For example, the third surface 31 and the fourth surface 41 are on one prism, and the first surface 11 and the second second surface 212 are on another prism, and the two prisms are glued or bonded to form the desired device.

[0048] In a variation of the above embodiment, the system may further include a curved semi-transparent and semi-reflective mirror with a 1 / 4 wave plate on the surface, which modulates and converts the light into P-polarized light and then reflects it back to the device, and the reflected light passes through the first surface 11 and the two second surfaces 211 and 212 and then exits from the second surface 212. The system may also include a compensation prism and a compensation lens to compensate for the transmitted image light and ambient light.

[0049] like Figure 2 As shown, in a variation, the optical device further includes a fifth surface 51. The fifth surface 51 is connected to (intersects) the first surface 11 and the fourth surface 41. The fifth surface 51 may also be connected to the third surface 31 (in some embodiments, it may also be connected to the second surface, or connected to the first, second and third surfaces at the same time). The fifth surface may be obtained by rotating the plane where the first or second surface is located around the intersection of the vertical plane perpendicular to both the first and second surfaces and the first or second surface by a certain angle and then translating, or by rotating around the above axis and then rotating around the intersection of the plane where the first and second surfaces are located by a certain angle and then translating. A portion of the light 711 (for example, the image light whose incident area is below -3 mm in the y direction of the principal optical axis when incident on the fourth surface and all the light whose angle with the central light of the central field of view of the image is less than -10°) is directly incident on the third surface after being coupled into the optical device from the fourth surface, and is reflected by the third surface 31 to the first surface 11, and then reflected by the first surface 11 to the second surface 21. The remaining light 712 will first be incident on the fifth surface 51, and then be reflected by the fifth surface (total reflection or reflection by the reflective film) and then be incident on the third surface 31, and then be directly reflected by the third surface to the second surface 21. In this system, two parallel light beams 711 and 712 are incident on the fourth surface 41. 712 is reflected by the fifth surface 51, and 711 propagates backward without passing through the fifth surface. Light 712 is reflected by the third surface, and light 711 is reflected by the third surface and the first surface. Before light beams 711 and 712 are incident on the second surface, the two light beams will still be parallel light.

[0050] In another embodiment, there are four working surfaces, namely the first, second, third and fourth surfaces. Antireflection films are prepared on the first, second and fourth surfaces, and a reflective film is prepared on the third surface. The second surface forms an angle of about 15° with the first surface. After the image light is coupled into the fourth surface, it is reflected by the third surface to the second surface, and then is incident on the first surface after being totally reflected on the second surface. At this time, the incident angle of the light is greater than the total reflection angle and is reflected back to the second surface again. Since the incident angle is still greater than the total reflection angle, the light will be reflected back to the first surface again. After multiple reflections, the angle of the light is less than the total reflection angle and will be emitted from the first surface. On the outside of the first surface, there is a curved reflector prepared with a polarized reflective film (or a semi-transparent and semi-reflective film with a certain reflectivity and a certain transmittance, or a curved reflector with a reflective film layer that reflects a specific wavelength). One side of the curved reflector is a compensation surface with the same shape as the first surface. There is a gap (air or low-refractive medium) between the compensation surface and the first surface. After the light is emitted from the first surface, it will pass through the compensation surface and be reflected by the curved reflector, and then pass through the first surface again. At this time, the incident angles when it is incident on the first and second surfaces are both less than the total reflection angle, and it will be transmitted out of the device from the second surface. The system also includes a compensation mirror, one surface of which is complementary to the curved surface of the curved reflector and is assembled with the curved reflector by gluing or bonding, and the other surface is the same as the second surface (or made into a specific curved surface to compensate for the myopia, hyperopia, astigmatism and other problems of the viewer's eyes), and is parallel to the second surface after assembly. Ambient light can penetrate the compensation mirror, the curved reflector and the optical device and then enter the viewer's eyes (such as through a piece of flat glass).

[0051] like Figure 1 As shown, in the above embodiment, a light sensor or a video / photographic system can also be arranged outside the fourth surface. By utilizing the reversible principle of the optical path, the external environment can be photographed, or an eye tracking system can be made to photograph the condition of the human eye and provide signals for subsequent dynamic adjustment of the eye movement.

[0052] In the above embodiment, an air gap or a gap filled with a low refractive index medium at a certain angle to the incident surface of the light can be added to the device to filter the light (stray light, ghosting, etc.) that exceeds the incident angle requirement. For example, an air gap at an angle of 20° to the fourth surface and with a thickness of 0.05 mm is added before or after the fourth surface. The fourth surface is made on a triangular or wedge-shaped prism, and the edge is glued to the prism containing the third surface. In this way, the light with a large angle will be totally reflected on the air gap and emitted (or absorbed) from the side of the prism where the fourth surface is located, thereby ensuring that the light that does not meet the angle requirement cannot enter the system.

[0053] In the description of the present application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0054] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. An optical device, characterized in that: comprising at least three surfaces: a first surface, a second surface and a third surface; The light propagates between the first surface and the second surface and experiences at least one reflection on the first surface and / or the second surface, and the third surface reflects the light; The third surface is not perpendicular to a plane that is perpendicular to both the first surface and the second surface.

2. The optical device according to claim 1, characterized in that The first surface is not parallel to the second surface, and the third surface is determined by: The first surface or the second surface is rotated around a first axis in space by a preset angle, and then rotated around a second axis perpendicular to the first axis by a preset angle, and the rotated surface is translated to obtain a third surface.

3. The optical device according to claim 1, characterized in that: The optical device further includes: a fourth surface, and the light enters and / or exits the optical device from the fourth surface.

4. The optical device according to claim 3, characterized in that: The light is an image light, and the fourth surface is perpendicular to the principal optical axis of the central field of view of the image light, or the angle between the fourth surface and the principal optical axis of the central field of view of the image light is greater than 30°.

5. The optical device according to claim 1, characterized in that: The optical device further comprises one or more connecting surfaces, wherein the connecting surfaces connect the third surface with the first surface and / or the second surface.

6. The optical device according to claim 1, characterized in that: The third surface satisfies the following conditions: The light is incident on the third surface after experiencing the same number of reflections on the first surface and the second surface; or, after being reflected by the third surface, the light is incident on the first surface and the second surface for the same number of reflections.

7. The optical device according to claim 1, characterized in that: The optical device is formed by splicing a plurality of sub-devices.

8. The optical device according to claim 1, characterized in that: The optical device further includes a fifth surface, and the fifth surface satisfies the following conditions: If two parallel light beams in the optical device are respectively reflected by different surfaces before incident on the third surface, the light beam that was incident on the third surface and reflected on the preset surface before incident on the third surface does not incident on the fifth surface, and the light beam that was not reflected on the preset surface before incident on the fifth surface, the light beam that was incident on the fifth surface is parallel to the light beam that was not incident on the fifth surface after being reflected by the fifth surface; And / or, if two parallel light beams in the optical device are reflected by different surfaces after being reflected by the third surface, the light beam reflected by the fifth surface and then reflected by the third surface will not be reflected by the preset surface, and the light beam directly reflected by the third surface without being reflected by the fifth surface will be reflected by the preset surface, and the light beam reflected by the preset surface will be parallel to the light beam not reflected by the preset surface after being reflected by the preset surface.

9. The optical device according to claim 1, characterized in that: The optical device includes a plurality of first surfaces and / or second surfaces.

10. The optical device according to claim 1, characterized in that: The light is coupled into and out of the optical device multiple times.

11. The optical device according to any one of claims 1 to 10, characterized in that: One or more of the following thin films are prepared on at least one surface of the optical device: Anti-reflection film, dielectric reflective film, metal reflective film, polarized reflective film, angle selective reflective film, wavelength selective reflective film, grating.

12. An optical imaging system, characterized in that: An optical device comprising any one of claims 1 to 11, wherein the image light is focused at least once.

13. An optical imaging system, characterized in that: The optical device comprises any one of claims 1 to 11. The optical system further comprises a sensor, which is used to sense the state of the external environment or the state of the viewer's eyes.

14. An optical device, characterized in that: An optical device comprising any one of claims 1 to 11.

Images