Optical system and head-mounted display device

Abstract

The embodiment of the utility model discloses an optical system and head-mounted display equipment. In a specific implementation scheme, the optical system comprises an image source; the first prism is provided with a first surface, a second surface and a third surface, and the first surface of the first prism is close to the image source; the second surface of the first prism is located on the side, away from the second prism, of the first prism, the third surface of the first prism is located on the side, close to the second prism, of the first prism, the second prism is provided with a first surface, and the first surface of the second prism is close to the third surface of the first prism; the lens is located on the side, away from the first prism, of the second prism, a first included angle between the first surface of the second prism and the optical axis of the lens and a second included angle between the third surface of the first prism and the optical axis of the lens are acute angles, and the first included angle is equal to the second included angle; the first film layer is located on the second surface of the first prism and can reflect and transmit light; the second film layer is located on the side, away from the second prism, of the lens and can reflect light.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the field of optical imaging technology, and in particular, to an optical system and a head-mounted display device. BACKGROUND

[0002] At present, the head-mounted display device is applied more and more widely. The head-mounted display device can be used for content display. For example, the head-mounted display device can be used for displaying movie pictures, game pictures, web pages, etc. The optical system is an important component of the head-mounted display device. SUMMARY

[0003] According to an aspect of an embodiment of the present disclosure, an optical system is provided, comprising: an image source; a first prism, the first prism having a first surface, a second surface and a third surface, the first surface of the first prism being close to the image source; a second prism, the second surface of the first prism being located on a side of the first prism away from the second prism, the third surface of the first prism being located on a side of the first prism close to the second prism, the second prism having a first surface, the first surface of the second prism being close to the third surface of the first prism; a lens, the lens being located on a side of the second prism away from the first prism, a first included angle between the first surface of the second prism and an optical axis of the lens and a second included angle between the third surface of the first prism and the optical axis of the lens being acute angles, and the first included angle being equal to the second included angle; a first film layer, the first film layer being located on the second surface of the first prism and capable of reflecting light and transmitting light; a second film layer, the second film layer being located on a side of the lens away from the second prism and capable of reflecting light; wherein the light emitted by the image source is incident on the first prism from the first surface of the first prism, after at least one total reflection in the first prism, the light is reflected by the first film layer, the light is emitted from the third surface of the first prism and incident on the second prism from the first surface of the second prism, after passing through the second prism and the lens, the light is reflected by the second film layer, and the light reflected by the second film layer passes through the lens, the first surface of the second prism, the third surface of the first prism and the second surface of the first prism in sequence and is emitted from the first film layer.

[0004] According to another aspect of an embodiment of the present disclosure, a head-mounted display device is provided, comprising: a frame structure; the above-mentioned optical system, the optical system being mounted on the frame structure.

[0005] The technical solutions of the present disclosure are described in further detail below with the aid of the accompanying drawings and embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0006] The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings in which like reference characters refer to like elements throughout. The accompanying drawings are intended to provide a further understanding of embodiments of the present disclosure and are incorporated in and constitute a part of this specification, illustrate embodiments of the present disclosure and serve to explain the principles of the present disclosure, but do not limit the present disclosure. In the drawings:

[0007] Figure 1 is a structural schematic diagram of an optical system provided by some exemplary embodiments of the present disclosure;

[0008] Figure 2 is a structural schematic diagram of an optical system provided by some exemplary embodiments of the present disclosure;

[0009] Figure 3-1 is a structural schematic diagram of an optical system provided by some exemplary embodiments of the present disclosure;

[0010] Figure 3-2 is a structural schematic diagram of an optical system provided by some exemplary embodiments of the present disclosure;

[0011] Figure 4 is a structural schematic diagram of an optical system provided by some exemplary embodiments of the present disclosure;

[0012] Figure 5 is a structural schematic diagram of an optical system provided by some exemplary embodiments of the present disclosure;

[0013] Figure 6 is a structural schematic diagram of an optical system provided by some exemplary embodiments of the present disclosure;

[0014] Figure 7 is a structural schematic diagram of an optical system provided by some exemplary embodiments of the present disclosure;

[0015] Figure 8 is a structural schematic diagram of an optical system provided by some exemplary embodiments of the present disclosure;

[0016] Figure 9-1 is a structural schematic diagram of an optical system provided by some exemplary embodiments of the present disclosure;

[0017] Figure 9-2 is a structural schematic diagram of an optical system provided by some exemplary embodiments of the present disclosure;

[0018] Figure 10-1 is a structural schematic diagram of an optical system provided by some exemplary embodiments of the present disclosure;

[0019] Figure 10-2 is a structural schematic diagram of an optical system provided by some exemplary embodiments of the present disclosure;

[0020] Figure 10-3 is a schematic diagram of the effect of an optical system according to some exemplary embodiments of the present disclosure;

[0021] Figure 11-1 is a schematic diagram of the structure of an optical system according to some exemplary embodiments of the present disclosure;

[0022] Figure 11-2 is a schematic diagram of the structure of an optical system according to some exemplary embodiments of the present disclosure;

[0023] Figure 11-3 is a schematic diagram of the structure of an optical system according to some exemplary embodiments of the present disclosure;

[0024] Figure 11-4 is a schematic diagram of the structure of an optical system according to some exemplary embodiments of the present disclosure;

[0025] Figure 12 is a schematic diagram of the structure of a frame according to some exemplary embodiments of the present disclosure.

[0026] In the figure, 10, an image source; 20, a first prism; 30, a second prism; 40, a lens; 45, a first film layer; 50, a second film layer; 201, a first surface of the first prism; 203, a second surface of the first prism; 205, a third surface of the first prism; 207, a groove; 100, a human eye; 301, a first surface of the second prism; V, a light ray incident on the first prism from the first surface of the first prism; 60, a third prism; 601, a first surface of the third prism; 603, a second surface of the third prism; 70, a first additional lens; 80, a second additional lens; Z, an axis; ∠R1, an included angle between the first surface of the second prism and the optical axis of the lens; ∠R2, an included angle between the third surface of the first prism and the optical axis of the lens; U1, a central thickness of an optical system; U2, a central thickness of another optical system; P, a position to which a first common edge needs to be moved; ∠A, an included angle between the second surface of the first prism and a target plane; ∠C, an included angle between the first surface of the first prism and the third surface of the first prism; ∠B, an included angle between the third surface of the first prism and the target plane; ∠Q, an included angle between the first surface of the second prism and the target plane; ∠E, an included angle between the third surface of the first prism and a light ray incident on the first surface of the first prism; ∠R3, an included angle between the normal of the image source and the optical axis of the lens; ∠R4, an included angle between the second surface of the first prism and the optical axis of the lens; 90, a frame structure. DETAILED DESCRIPTION

[0027] Hereinafter, exemplary embodiments according to the present disclosure will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present disclosure, and not all embodiments of the present disclosure, and it should be understood that the present disclosure is not limited to the exemplary embodiments described herein.

[0028] In the description of this disclosure, the terms "upper," "lower," "left," "right," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this disclosure and simplifying the description, and are not intended to indicate or imply that the device referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this disclosure.

[0029] In the description of this disclosure, unless otherwise expressly specified and limited, the terms "installation," "connection," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this disclosure according to the specific circumstances.

[0030] Exemplary Overview

[0031] Head-mounted displays, also known as head-mounted displays (HMDs) or head-mounted devices, can be used to achieve augmented reality (AR), virtual reality (VR), and mixed reality (MR) effects. They can take the form of glasses, helmets, or other similar devices.

[0032] The optical system is a crucial component of head-mounted display devices. It can also be called an optomechanical system. The optical system emits light and processes it, directing the light into the eye socket. When a user wears the head-mounted display, their eyes are positioned within the eye socket, light is projected onto their eyes, and the user sees the displayed image. Therefore, to ensure a superior user experience, it is essential to design the optical system effectively.

[0033] Exemplary Structure

[0034] This disclosure provides an optical system through several exemplary embodiments. The optical system provided by the embodiments of this disclosure may include an image source, a prism, and a lens.

[0035] For example, such as Figure 1 As shown, the optical system provided in the embodiments of this disclosure may include an image source 10, a first prism 20, and a lens 40.

[0036] In some alternative embodiments of the present disclosure, the image source 10 can be configured to emit light rays of a display picture. The image source 10 can include, but is not limited to, an Organic Light Emitting Diode (OLED) image source, a Liquid Crystal image source, a Liquid Crystal on Silicon (LCOS) image source, a Micro Electro Mechanical System (MEMS) image source, a Digital Micromirror Device (DMD), etc. For example, the image source 10 can be an OLED display screen.

[0037] In some alternative embodiments of the present disclosure, the first prism 20 can be configured to extend an optical path of the optical system. The first prism 20 can have a first surface 201, a second surface 203, and a third surface 205. For example, the first surface 201 of the first prism 20 can intersect the second surface 203, the first surface 201 can intersect the third surface 205, and the second surface 203 can intersect the third surface 205. The first surface 201, the second surface 203, and the third surface 205 of the first prism 20 can all be planar surfaces, and the first prism 20 can be a triple prism. In an alternative example, the first surface 201 of the first prism 20 can be perpendicular to the second surface 203 of the first prism 20, and the first prism 20 can be a right-angle prism.

[0038] It can be understood that the "intersection" or "included angle" described in the present disclosure can be an actual intersection or an actual included angle between two elements. If two elements do not actually intersect or do not form an included angle, the extended parts of the two elements after extending along their respective directions of extension can also intersect or form an included angle, which satisfies the relevant definitions in the embodiments of the present disclosure.

[0039] In some embodiments, the first surface 201 of the first prism 20 can also be a curved surface to facilitate optimization of field curvature and pupil shift distortion.

[0040] In some alternative embodiments of the present disclosure, the lens 40 can be configured to bear optical power and correct aberrations. The first surface 201 of the first prism 20 can be close to the image source 10. The second surface 203 of the first prism 20 can be located on a side of the first prism 20 away from the lens 40. The third surface 205 of the first prism 20 can be located on a side of the first prism 20 close to the lens 40. For example, the first surface 201 of the first prism 20 can be opposite to the image source 10. The first surface 201 and the second surface 203 of the first prism 20 can both be located on a side of the first prism 20 close to an eyebox of the optical system.

[0041] It can be understood that the eyebox of the optical system can be a movable area of the human eye (for example Figure 1 the human eye 100 in FIG. 1), in which the human eye 100 can see the display picture. The eyebox of the optical system can also be referred to as Eye Box or EB. The size of the eyebox of the optical system is an important design index in the optical system.

[0042] In some optional embodiments of the present disclosure, as shown in Figure 1 FIG. 1, the optical system provided by the embodiments of the present disclosure can further include film layers, for example, a first film layer 45 and a second film layer 50. The first film layer 45 can be located on the second surface 203 of the first prism 20 and can reflect and transmit light. The first film layer 45 can be a semi-transmissive and semi-reflective film without light splitting capability or a polarized light splitting film. The first film layer 45 can be arranged on the second surface 203 of the first prism 20 by adhesion, film plating or the like. The second film layer 50 can be located on the side of the lens 40 away from the first prism 20 and can reflect light. The second film layer 50 can be used for total reflection or partial reflection of light, so that the second film layer 50 can be a total reflection film or a semi-transmissive and semi-reflective film. The second film layer 50 can be arranged on the side of the lens 40 away from the first prism 20 by adhesion, film plating or the like.

[0043] Optionally, the film layer of the optical system can further include an antireflection film. For example, the antireflection film can be located on at least one surface of the first prism 20. For example, the antireflection film can be located on at least one surface of the lens 40.

[0044] It should be noted that the light emitted by the image source 10 can be incident on the first prism 20 from the first surface 201 of the first prism 20, be reflected by the first film layer 45 after at least one total reflection in the first prism 20, be emitted from the third surface 205 of the first prism 20, be reflected by the second film layer 50 after passing through the lens 40, and be emitted from the first film layer 45 in sequence after passing through the lens 40, the third surface 205 of the first prism 20 and the second surface 203 of the first prism 20. The light emitted from the first film layer 45 can enter the eyebox of the optical system.

[0045] In the optical system provided by the embodiments of the present disclosure, the light emitted by the image source 10 can enter the eyebox of the optical system through the cooperation of the image source 10, the first prism 20, the lens 40, the first film layer 45 and the second film layer 50. In this way, the human eye 100 can see the display picture provided by the image source 10. Therefore, the head-mounted display device can normally display content to meet the use requirements of the user, for example, to meet the viewing requirements of the user.

[0046] In some optional embodiments of the present disclosure, as shown in Figure 2 , Figure 3-1 ,Figure 3-2 As shown, the optical system provided by the embodiments of the present disclosure can further include a second prism 30 in addition to the image source 10, the first prism 20, the lens 40, the first film layer 45 and the second film layer 50. The second surface 203 of the first prism 20 can be located on the side of the first prism 20 away from the second prism 30. The third surface 205 of the first prism 20 can be located on the side of the first prism 20 close to the second prism 30. The second prism 30 can have a first surface 301. The first surface 301 of the second prism 30 can be close to the third surface 205 of the first prism 20. The first surface 301 of the second prism 30 can be a plane. The first surface 301 of the second prism 30 and the third surface 205 of the first prism 20 can be opposite and have a gap.

[0047] In the embodiments in which the optical system includes the second prism 30, the film layer of the optical system can include an anti-reflection film located on at least one surface of the second prism 30.

[0048] In some optional embodiments of the present disclosure, the lens 40 can be located on the side of the second prism 30 away from the first prism 20. The lens 40 and the second prism 30 can be an integral piece, for example, see Figure 2 Figure 3-2 Alternatively, the lens 40 and the second prism 30 can be separately arranged, for example, see Figure 3-1 If the lens 40 and the second prism 30 are an integral piece, it can be understood that one surface of the second prism 30 is a curved surface, and the part constituting the lens 40 and the part constituting the second prism 30 can be integrally injection molded. If the lens 40 and the second prism 30 are separately arranged, the lens 40 and the second prism 30 can be injection molded respectively and fixed by bonding or the like. In addition, the surface of the lens 40 away from the second prism 30 can be a spherical surface or a non-spherical surface. For example, the surface of the lens 40 away from the second prism 30 can be a rotationally symmetric non-spherical surface.

[0049] It should be noted that the light emitted by the image source 10 can be incident on the first prism 20 from the first surface 201 of the first prism 20, after at least one total reflection in the first prism 20, be reflected by the first film layer 45, be emitted from the third surface 205 of the first prism 20 and be incident on the second prism 30 from the first surface 301 of the second prism 30, after passing through the second prism 30 and the lens 40, be reflected by the second film layer 50, and the light reflected by the second film layer 50 passes through the lens 40, the first surface 301 of the second prism 30, the third surface 205 of the first prism 20 and the second surface 203 of the first prism 20 in turn, and is emitted from the first film layer 45.

[0050] In some optional embodiments of the present disclosure, the light incident on the first prism 20 from the first surface 201 of the first prism 20 (for example, the light emitted by the image source 10) can be incident on the first prism 20 from the second surface 203 of the first prism 20. Figure 2 ​The light ray V) in the first prism 20 can first undergo total reflection at the third surface 205 of the first prism 20, then undergo reflection (which can be reflected by the first film layer 45) at the second surface 203 of the first prism 20, and then exit from the third surface 205 of the first prism 20 and enter the second prism 30 from the first surface 301 of the second prism 30. Of course, the light ray entering the first prism 20 from the first surface 201 of the first prism 20 can undergo total reflection more than once in the first prism 20 before exiting from the third surface 205 of the first prism 20, and can undergo reflection more than once in the first prism 20. For example, after undergoing total reflection once at the third surface 205 of the first prism 20 and undergoing reflection once at the second surface 203 of the first prism 20, the light ray can undergo total reflection again at the third surface 205 of the first prism 20 and undergo reflection again at the second surface 203 of the first prism 20 before exiting from the third surface 205 of the first prism 20.

[0051] The light ray exiting from the third surface 205 of the first prism 20 can enter the second prism 30 from the first surface 301 of the second prism 30. The light ray entering the second prism 30 can propagate to the second film layer 50 after sequentially passing through the second prism 30 and the lens 40. The second film layer 50 can reflect the light ray to adjust the propagation direction of the light ray. For example, referring to Figure 2 , the second film layer 50 can adjust the propagation direction of the light ray from horizontal right to horizontal left. In this way, the light ray with the adjusted propagation direction can sequentially pass through the lens 40, the first surface 301 of the second prism 30, the third surface 205 of the first prism 20, the second surface 203 of the first prism 20, the first film layer 45, and finally the eyebox of the optical system.

[0052] The optical system provided by the embodiments of the present disclosure can enable the light ray emitted by the image source 10 to enter the eyebox of the optical system through the cooperation of the image source 10, the first prism 20, the second prism 30, the lens 40, the first film layer 45, and the second film layer 50. In this way, the human eye 100 can see the display picture provided by the image source 10. Therefore, the head-mounted display device can normally display content to meet the use requirements of the user, for example, to meet the viewing requirements of the user.

[0053] In some alternative embodiments of the present disclosure, the optical system can further comprise a compensation member. The compensation member can compensate for the deflection of the light rays in the first prism 20, and can also compensate for the optical path difference of the light rays emitted from different light emitting positions on the image source 10. The compensation member can be located close to the second surface 203 of the first prism 20. The light rays reflected by the second film layer 50 can exit through the compensation member after passing through the first prism 20 again. For example, the light rays emitted by the image source 10 can propagate along the following target path: the first prism 20→the first film layer 45→the first prism 20→the second prism 30→the lens 40→the second film layer 50→the lens 40→the second prism 30→the first prism 20→the first film layer 45→the compensation member→the eyebox of the optical system.

[0054] In this way, the light rays emitted by the image source 10 can enter the eyebox of the optical system with the compensation member. Thus, the human eye 100 can see the display image provided by the image source 10. In addition, the compensation member can also compensate for the deflection of the light rays in the first prism 20, and can also compensate for the optical path difference of the light rays emitted from different light emitting positions on the image source 10, thereby improving the imaging quality of the optical system.

[0055] In some alternative embodiments of the present disclosure, as shown in Figures 2 to 5 , the compensation member can be a third prism 60. The third prism 60 can have a first surface 601 and a second surface 603. The first surface 601 of the third prism 60 can be located on the side of the third prism 60 away from the first prism 20. The second surface 603 of the third prism 60 can be located on the side of the third prism 60 close to the first prism 20. The light rays reflected by the second film layer 50 can exit through the second surface 603 of the third prism 60 and the first surface 601 of the third prism 60 after passing through the first prism 20 again.

[0056] In the embodiments in which the optical system comprises the third prism 60, the film layer of the optical system can comprise an anti-reflection film on at least one surface of the third prism 60.

[0057] Alternatively, the first surface 601 and the second surface 603 of the third prism 60 can both be planar, for example, as shown in Figure 2 、 Figure 3-1 、 Figure 3-2 . Alternatively, the first surface 601 of the third prism 60 can be curved, and the second surface 603 of the third prism 60 can be planar, for example, as shown in Figure 4 、 Figure 5The first surface 601 and the second surface 603 of the third prism 60 can intersect. The first film layer 45 can be a polarization beam-splitting film located between the second surface 603 of the third prism 60 and the second surface 203 of the first prism 20, and a 1 / 4 wave plate can be arranged between the third surface 205 of the first prism 20 and the first surface 301 of the second prism 30, and the polarization beam-splitting film and the 1 / 4 wave plate can be used in cooperation to make the light emitted by the image source 10 propagate according to the target path described above.

[0058] After the light reflected by the second film layer 50 passes through the first prism 20 again, the light can be emitted from the second surface 203 of the first prism 20 and incident on the third prism 60 from the second surface 603 of the third prism 60, and then emitted from the first surface 601 of the third prism 60 until the eyebox of the optical system.

[0059] In this way, in the case where the compensation member is the third prism 60, the light emitted by the image source 10 can enter the eyebox of the optical system. In this way, the display image provided by the image source 10 can be viewed by the human eye 100. In addition, the third prism 60 is beneficial to ensuring that the optical paths of the light emitted by different light emitting positions are substantially the same, and is beneficial to compensating for the deflection of the light in the first prism 20, thereby improving the imaging quality of the optical system. Moreover, the third prism 60 has a simple face type and is easy to process.

[0060] In some optional embodiments of the present disclosure, as shown in Figures 4 to 8 The optical system can further include a first additional lens 70. The first additional lens 70 can be located between the image source 10 and the first surface 201 of the first prism 20. The light emitted by the image source 10 can be incident on the first prism 20 after passing through the first additional lens 70.

[0061] In the embodiments in which the optical system includes the first additional lens 70, the film layer of the optical system can include an anti-reflection film located on at least one surface of the first additional lens 70.

[0062] Optionally, the first additional lens 70 can belong to a positive lens. For example, the first additional lens 70 can be a plano-convex lens. For another example, the first additional lens 70 can be a biconvex lens.

[0063] Due to the arrangement of the first additional lens 70, the light emitted by the image source 10 can first pass through the first additional lens 70 and then be incident on the first prism 20 from the first surface 201 of the first prism 20. The first additional lens 70 can be an aspherical lens, thereby being beneficial to correcting aberration to ensure the imaging quality of the optical system.

[0064] In some embodiments of the present disclosure, at least one of the image source 10 and the first additional lens 70 can be moved relative to the first prism 20 to perform diopter adjustment.

[0065] In some optional embodiments of the present disclosure, the second film layer 50 can be a semi-transparent semi-reflective film. As shown in Figure 5 、 Figure 7 、 Figure 8 The optical system can further include a second additional lens 80, as shown in

[0066] In the embodiments in which the optical system includes the second additional lens 80, the film layers of the optical system can include an anti-reflection film on at least one surface of the second additional lens 80.

[0067] Optionally, the second additional lens 80 can be attached to the second film layer 50. Alternatively, there can be a gap between the second additional lens 80 and the second film layer 50.

[0068] Here, the second additional lens 80 can be used as a compensating lens for the lens 40. Since the second additional lens 80 is located on the side of the second film layer 50 away from the lens 40, the light rays in the external environment (which can also be referred to as ambient light rays) can pass through the second additional lens 80, the second film layer 50, the lens 40, the second prism 30, the first prism 20, the third prism 60, and finally the eyebox of the optical system in sequence. In this way, the ambient light rays can enter the human eye 100 without deflection, and the user can see the un-distorted image of the external environment when observing the external environment while wearing the head-mounted display device.

[0069] In some embodiments, the first surface 601 of the third prism 60 can be a curved surface, for example, a concave surface, which can effectively compensate for the optical power of the lens 40. In this case, the second additional lens 80 used as a compensating lens for the lens 40 can not be additionally provided.

[0070] In some optional embodiments of the present disclosure, as shown in Figure 8 、 Figure 9-1 、 Figure 9-2 The portion of the second surface 203 of the first prism 20 near the image source 10 can have a groove 207, as shown in

[0071] Optionally, the common edge of the first surface 601 of the third prism 60 and the second surface 603 of the third prism 60 can be referred to as the first common edge. The target region can be located on the second surface 203 of the first prism 20, between the first surface 201 of the first prism 20 and the first common edge. The groove 207 can be a V-shaped groove.

[0072] It should be noted that the edge region of the image source 10 (for example, the edge region of the image source 10 shown in Figures 2 to 9-2The light emitted from the lower left edge region of the image source 10 and incident on the first surface 201 of the first prism 20 can be directly projected to the target region of the second surface 203 of the first prism 20 (i.e. without being first projected to the third surface 205 of the first prism 20 according to the designed light path). The light directly projected to the target region of the second surface 203 of the first prism 20 can cause ghosting if it subsequently reaches the eyebox of the optical system together with the normal light path, and thus the imaging quality of the optical system cannot be guaranteed. It is found through research that the groove 207 provided on the portion of the second surface 203 of the first prism 20 close to the image source 10 can change the propagation path of the light directly projected to the target region of the second surface 203 of the first prism 20, so that the light cannot reach the eyebox of the optical system. For example, the light does not satisfy the total reflection condition (e.g. does not satisfy the condition that the incident angle is greater than or equal to the critical angle), thus helping to eliminate ghosting and guarantee the imaging quality of the optical system.

[0073] In some optional embodiments of the present disclosure, the portion of the second surface 203 of the first prism 20 close to the image source 10 can be coated black. For example, the groove wall of the groove 207 can be coated black.

[0074] Alternatively, the groove wall of the groove 207 can be coated black through a coating process. In this way, the light directly projected to the target region of the second surface 203 of the first prism 20 can be absorbed and thus does not undergo total reflection, thus helping to eliminate ghosting and guarantee the imaging quality of the optical system.

[0075] In some optional embodiments of the present disclosure, the portion of the second surface 203 of the first prism 20 close to the image source 10 can be a rough surface. For example, the groove wall of the groove 207 can be a rough surface.

[0076] Alternatively, the groove wall of the groove 207 can have a large surface roughness. In this way, the light directly projected to the target region of the second surface 203 of the first prism 20 can undergo diffuse reflection and thus does not undergo total reflection, thus helping to eliminate ghosting and guarantee the imaging quality of the optical system.

[0077] In some optional embodiments of the present disclosure, the first included angle between the first surface 301 of the second prism 30 and the optical axis of the lens 40 and the second included angle between the third surface 205 of the first prism 20 and the optical axis of the lens 40 can each be an acute angle, and the first included angle can be equal to the second included angle. Herein, the first included angle can be equal to the second included angle can be understood as the two included angles can be equal or substantially the same.

[0078] Alternatively, the optical axis of the lens 40 can be represented as Figure 2The first surface 301 of the second prism 30 can be tilted relative to the optical axis of the lens 40, such that the first included angle between the first surface 301 of the second prism 30 and the optical axis of the lens 40 is an acute angle. The third surface 205 of the first prism 20 can be tilted relative to the optical axis of the lens 40, such that the second included angle between the third surface 205 of the first prism 20 and the optical axis of the lens 40 is an acute angle. The tilt angle of the third surface 205 of the first prism 20 relative to the optical axis of the lens 40 can be the same as the tilt angle of the first surface 301 of the second prism 30 relative to the optical axis of the lens 40. The tilt angle of the third surface 205 of the first prism 20 relative to the optical axis of the lens 40 can be characterized by the first included angle between the first surface 301 of the second prism 30 and the optical axis of the lens 40. The first included angle can be referred to... Figure 2 ∠R1 in the diagram. The inclination of the first surface 301 of the second prism 30 relative to the optical axis of the lens 40 can be characterized by the second included angle between the third surface 205 of the first prism 20 and the optical axis of the lens 40. The second included angle can be found in [reference needed]. Figure 2 In the equation ∠R2, both ∠R1 and ∠R2 can be located between 0 degrees and 90 degrees, and ∠R1 and ∠R2 can be equal.

[0079] Figure 10-1 , Figure 10-2 , Figure 10-3 Two optical systems are shown in each. Figure 10-1 , Figure 10-2 , Figure 10-3 Of the three optical systems, the one on the right exhibits a situation where the third surface 205 of the first prism 20 and the first surface 301 of the second prism 30 are both tilted relative to the optical axis of the lens 40, and the tilt angle of the third surface 205 of the first prism 20 relative to the optical axis of the lens 40 is the same as the tilt angle of the first surface 301 of the second prism 30 relative to the optical axis of the lens 40. The one on the left exhibits a situation where the third surface 205 of the first prism 20 and the first surface 301 of the second prism 30 are not tilted relative to the optical axis of the lens 40 (i.e., ∠R1 and ∠R2 are approximately right angles). Furthermore, the thickness (center thickness) of the optical system on the left along the optical axis of the lens 40 can be represented as U1, and the thickness (center thickness) of the optical system on the right along the optical axis of the lens 40 can be represented as U2, where U1 and U2 are the same. It should be noted that... Figure 10-1 It means Figures 2 to 9-2 The direction of light emitted from a point in the right half of the region of image source 10. Figure 10-2 It means Figures 2 to 9-2 The direction of light emitted from a point in the left half of the image source 10. Figure 10-3 At the same time, it indicated Figures 2 to 9-2The directions of the light rays emitted by a certain point in the left half region of the image source 10 and a certain point in the right half region of the image source 10. The dashed lines in the figure represent the optical axis of the optical system.

[0080] The eyebox of the optical system needs to cover the light rays of each region of the image source 10 to ensure the user experience. In the prior art, the eyebox of the optical system is usually designed to be as large as possible. In the prior art, the eyebox of the optical system is usually designed to be as large as possible. Figure 10-3 In the prior art, the thick vertical line in the figure schematically shows the size of the eyebox of the optical system in the cross section. By comparing the two optical systems, it can be seen that, under the condition that the central thickness is the same and the same field of view angle is achieved, the size of the eyebox of the optical system located on the left is smaller than the size of the eyebox of the optical system located on the right. Therefore, in the embodiments of the present disclosure, by tilting the third surface 205 of the first prism 20 and the first surface 301 of the second prism 30 relative to the optical axis of the lens 40, and by making the tilt of the third surface 205 of the first prism 20 relative to the optical axis of the lens 40 consistent with the tilt of the first surface 301 of the second prism 30 relative to the optical axis of the lens 40, it is beneficial to achieve a larger eyebox under the condition that the central thickness is the same and the field of view angle is the same. In addition, it can be observed that, if the size of the eyebox of the optical system located on the right is to be reduced to the size of the eyebox of the optical system located on the left, the first common edge (i.e., the common edge of the first surface 601 of the third prism 60 and the second surface 603 of the third prism 60) in the above can be moved to the position P in the figure. Figure 10-1 In the prior art, the thick vertical line in the figure schematically shows the size of the eyebox of the optical system in the cross section. By comparing the two optical systems, it can be seen that, under the condition that the central thickness is the same and the same field of view angle is achieved, the size of the eyebox of the optical system located on the left is smaller than the size of the eyebox of the optical system located on the right. Therefore, in the embodiments of the present disclosure, by tilting the third surface 205 of the first prism 20 and the first surface 301 of the second prism 30 relative to the optical axis of the lens 40, and by making the tilt of the third surface 205 of the first prism 20 relative to the optical axis of the lens 40 consistent with the tilt of the first surface 301 of the second prism 30 relative to the optical axis of the lens 40, it is beneficial to achieve a larger eyebox under the condition that the central thickness is the same and the field of view angle is the same. In addition, it can be observed that, if the size of the eyebox of the optical system located on the right is to be reduced to the size of the eyebox of the optical system located on the left, the first common edge (i.e., the common edge of the first surface 601 of the third prism 60 and the second surface 603 of the third prism 60) in the above can be moved to the position P in the figure.

[0081] In some optional embodiments of the present disclosure, the angle between the second surface 203 of the first prism 20 and the plane perpendicular to the optical axis of the lens 40 is a third angle, and the angle between the first surface 201 of the first prism 20 and the third surface 205 of the first prism 20 is a fourth angle. The fourth angle can be greater than twice the third angle.

[0082] For ease of description, the plane perpendicular to the optical axis of the lens 40 can be referred to as a target plane. The angle between the second surface 203 of the first prism 20 and the target plane (i.e., the third angle) can be represented as Figure 2 ∠A shown in the figure. The angle between the third surface 205 of the first prism 20 and the target plane (i.e., the fifth angle in the following) can be represented as Figure 2The angle between the first surface 201 of the first prism 20 and the third surface 205 of the first prism 20 (i.e., the third angle) can be denoted as Figure 2 The angle between the second surface 203 of the first prism 20 and the third surface 205 of the first prism 20 (i.e., the fourth angle) can be denoted as

[0083] In some optional embodiments of the present disclosure, ∠C≠2∠A. For example, ∠C>2∠A.

[0084] Optionally, the common edge of the second surface 203 of the first prism 20 and the third surface 205 of the first prism 20 can be referred to as the second common edge. The target plane can be a plane passing through the second common edge and being perpendicular to the axis Z in the first prism 20. Figure 2

[0085] It can be understood that, when the prism has a tip, the two adjacent surfaces extend to each other to form an actual common edge. When the prism does not have a tip, i.e., the two adjacent surfaces cannot extend to each other to form an actual common edge, the common edge can be an edge formed by the two adjacent surfaces in theory.

[0086] For the case that the third surface 205 of the first prism 20 and the first surface 301 of the second prism 30 are both not inclined relative to the optical axis of the lens 40, ∠C can be equal to 2∠A. By setting ∠C≠2∠A, the optical system provided by the embodiments of the present disclosure can be obviously distinguished from the optical system in this case. For example, in the optical system provided by the embodiments of the present disclosure, the third surface 205 of the first prism 20 and the first surface 301 of the second prism 30 are both inclined relative to the optical axis of the lens 40, and the inclination of the third surface 205 of the first prism 20 relative to the optical axis of the lens 40 can be consistent with the inclination of the first surface 301 of the second prism 30 relative to the optical axis of the lens 40. In this way, it is beneficial to realize a larger eyebox under the same center thickness and the same field of view angle, and it is beneficial to realize a smaller center thickness under the same field of view angle and the same eyebox, thereby facilitating the miniaturization and lightening of the optical system.

[0087] In some optional embodiments of the present disclosure, the fourth angle can be equal to the sum of the fifth angle and twice the third angle. That is, ∠C=2∠A+∠B.

[0088] In some optional embodiments of the present disclosure, the absolute value of the difference between the sum of the fifth angle and twice the third angle and the fourth angle is less than or equal to 0.8 degrees. That is, ︱∠C-(2∠A+∠B)︱≤0.8°.

[0089] ​Optionally, | ∠C - (2 ∠A + ∠B) | can be equal to 0, i.e., ∠C can be the same as (2 ∠A + ∠B). Of course, ∠C can not be the same as (2 ∠A + ∠B) but close enough, i.e., ∠C can be substantially the same as (2 ∠A + ∠B). For example, | ∠C - (2 ∠A + ∠B) | can be equal to 0.1°, 0.2°, 0.7°, etc., which will not be listed one by one here.

[0090] By the restriction condition of | ∠C - (2 ∠A + ∠B) | ≤ 0.8°, ∠C can be the same as (2 ∠A + ∠B) or substantially the same. It is found through research that ∠C being the same as (2 ∠A + ∠B) or substantially the same is conducive to ensuring that the light rays emitted by the image source 10 propagate along the target path introduced above for the optical system provided by the embodiments of the present disclosure.

[0091] In some optional embodiments of the present disclosure, the ratio of twice the sum of the third and fifth angles to the complement of the third angle is greater than 0.9. That is, 2(∠A + ∠B) / (90° - ∠A) > 0.9.

[0092] In some optional embodiments of the present disclosure, the difference between twice the sum of the third and fifth angles and the complement of the third angle is greater than -6 degrees. That is, 2(∠A + ∠B) - (90° - ∠A) > -6°. 2(∠A + ∠B) - (90° - ∠A) > -6° can also be transformed into 3 ∠A + ∠2B - 90° > -6°.

[0093] It can be known through geometric derivation that 2(∠A + ∠B) can be equal to the angle between the normal line of the image source 10 and the optical axis of the lens 40, which can be represented as ∠R3 in Figure 2 . In addition, 90° - ∠A can be equal to the angle between the second surface 203 of the first prism 20 and the optical axis of the lens 40, which can be represented as ∠R4 in Figure 2 . It is found through research that limiting ∠A and ∠B to 2(∠A + ∠B) / (90° - ∠A) > 0.9, 3 ∠A + ∠2B - 90° > -6° is conducive to making the light rays that can form ghost images as far away from the effective display screen as possible, so as to ensure the imaging quality of the optical system.

[0094] In some optional embodiments of the present disclosure, the fifth angle can be greater than 5 degrees and less than 15 degrees. That is, ∠B can be greater than 5° and less than 15°. In other words, ∠B can be limited within the range of (5°, 15°). For example, ∠B can be 6°, 7°, 8°, 9°, 10°, 11°, 12°, 13°, 14°, etc., which will not be listed one by one here.

[0095] It is found through research that limiting ∠B to the range of (5°, 15°) is conducive to ensuring the rationality of the parameters of the first prism 20, thereby being conducive to ensuring the imaging quality of the optical system.

[0096] In some optional embodiments of the present disclosure, the fifth included angle can be greater than 5 degrees and less than 8 degrees, or the fifth included angle can be greater than 8 degrees and less than 15 degrees. That is, ∠B can be greater than 5° and less than 8°, or ∠B can be greater than 8° and less than 15°. In other words, ∠B can be limited to the range of (5°, 8°)∪(8°, 15°). For example, ∠B can be 6°, 7°, 9°, 10°, 11°, 12°, 13°, 14°, and the like, which will not be listed one by one here.

[0097] In some optional embodiments of the present disclosure, the fifth included angle can be greater than or equal to 7.5 degrees and less than or equal to 8 degrees. That is, ∠B can be greater than or equal to 7.5° and less than or equal to 8°. In other words, ∠B can be limited to the range of [7.5°, 8°]. For example, ∠B can be 7.5°, 7.7°, 7.8°, 7.9°, 8°, and the like, which will not be listed one by one here.

[0098] In some optional embodiments of the present disclosure, the fifth included angle can be greater than 8.1 degrees and less than 8.7 degrees. That is, ∠B can be greater than 8.1° and less than 8.7°. In other words, ∠B can be limited to the range of (8.1°, 8.7°). For example, ∠B can be 8.2°, 8.3°, 8.4°, 8.5°, 8.6°, and the like, which will not be listed one by one here.

[0099] In some optional embodiments of the present disclosure, the fifth included angle can be greater than or equal to 8.7 degrees and less than or equal to 9.3 degrees. That is, ∠B can be greater than or equal to 8.7° and less than or equal to 9.3°. In other words, ∠B can be limited to the range of [8.7°, 9.3°]. For example, ∠B can be 8.7°, 8.8°, 8.9°, 9.1°, 9.2°, 9.3°, and the like, which will not be listed one by one here.

[0100] In some optional embodiments of the present disclosure, the fifth included angle can be greater than or equal to 9.4 degrees and less than or equal to 9.8 degrees. That is, ∠B can be greater than or equal to 9.4° and less than or equal to 9.8°. In other words, ∠B can be limited to the range of [9.4°, 9.8°]. For example, ∠B can be 9.4°, 9.5°, 9.6°, 9.7°, 9.8°, and the like, which will not be listed one by one here.

[0101] In some optional embodiments of this disclosure, the third included angle can be greater than 20 degrees and less than 30 degrees. That is, ∠A can be greater than 20° and less than 30°. In other words, ∠A can be limited to the range of (20°, 30°). For example, ∠A can be 21°, 23°, 24°, 25°, 27°, 28°, 29°, etc., which will not be listed here.

[0102] Research has shown that limiting ∠A to the range of (20°, 30°) helps to ensure the rationality of the parameters of the first prism 20, thereby helping to ensure the imaging quality of the optical system.

[0103] In some alternative embodiments of this disclosure, the angle between the third surface 205 of the first prism 20 and the target plane may be equal to the angle between the first surface 301 of the second prism 30 and the target plane.

[0104] Optionally, the angle between the third surface 205 of the first prism 20 and the target plane can be equal to... Figure 2 As shown, ∠B, the angle between the first surface 301 of the second prism 30 and the target plane can be equal to Figure 2 If ∠Q is a given value, then ∠Q = ∠B. In this case, the third surface 205 of the first prism 20 and the first surface 301 of the second prism 30 can be parallel to each other.

[0105] Research has shown that if ∠Q = ∠B, then ∠R2 = ∠R1, and ∠C = 2∠A + ∠B. This ensures that, for the optical system provided in the embodiments of this disclosure, the light emitted from image source 10 propagates along the target path described above.

[0106] Through observation Figure 2 It can be seen that ∠R1 = 90° - ∠Q = 90° - ∠B. Assuming that the light ray incident from the first surface 201 of the first prism 20 is projected onto the third surface 205 of the first prism 20, the angle between the light ray and the third surface 205 of the first prism 20 is expressed as... Figure 2 Given ∠E, we can deduce geometrically that ∠R1 = 2∠A + ∠E and ∠C + ∠E = 90°. Therefore, 90° - ∠B = 2∠A + ∠E. Since ∠C + ∠E = 90°, we can also have ∠C + ∠E - ∠B = 2∠A + ∠E, thus ∠C = 2∠A + ∠B.

[0107] Of course, the structure of the optical system provided in the embodiments of this disclosure is not limited to... Figures 1 to 9-2 The structure shown in the diagram.

[0108] For example, the structure of the optical system provided in the embodiments of this disclosure can also be found in... Figure 11-1 or Figure 11-2 .like Figure 11-1 ,Figure 11-2 As shown in FIG. 6, the first surface 601 of the third prism 60 can be a plane, and the surface of the second additional lens 80 close to the ambient environment can be a curved surface. By setting the surface of the second additional lens 80 close to the ambient environment as a curved surface, such as a convex surface or a concave surface, compensation of ambient light is facilitated, so that the user can see an undistorted environmental image.

[0109] For another example, the structure of the optical system provided by the embodiments of the present disclosure can refer to Figure 11-3 Or Figure 11-4 As shown in FIG. 6, the first surface 601 of the third prism 60 can be a plane, and the surface of the second additional lens 80 close to the ambient environment can be a curved surface. By setting the surface of the second additional lens 80 close to the ambient environment as a curved surface, such as a convex surface or a concave surface, compensation of ambient light is facilitated, so that the user can see an undistorted environmental image. Figure 11-3 、 Figure 11-4 As shown in FIG. 6, the first surface 601 of the third prism 60 can be a plane, and the surface of the second additional lens 80 close to the ambient environment can be a curved surface. By setting the surface of the second additional lens 80 close to the ambient environment as a curved surface, such as a convex surface or a concave surface, compensation of ambient light is facilitated, so that the user can see an undistorted environmental image.

[0110] In some optional embodiments of the present disclosure, the refractive indices of the first prism 20, the second prism 30, and the third prism 60 can be consistent.

[0111] Here, the refractive indices of the first prism 20, the second prism 30, and the third prism 60 being consistent can be understood as the refractive indices of the three being the same or substantially the same.

[0112] Through research, it is found that by setting the refractive indices of the first prism 20, the second prism 30, and the third prism 60 to be consistent, it can be ensured that, in the case that the first surface 301 of the second prism 30 is arranged to be inclined relative to the optical axis of the lens 40, the third surface 205 of the first prism 20 is arranged to be inclined relative to the optical axis of the lens 40, and the inclination of the third surface 205 of the first prism 20 relative to the optical axis of the lens 40 is consistent with the inclination of the first surface 301 of the second prism 30 relative to the optical axis of the lens 40, the light emitted by the light source 10 propagates along the target path in the above through the same optical path.

[0113] In some optional embodiments of the present disclosure, the refractive index of the third prism 60 can be greater than or equal to 1.45 and less than or equal to 1.85. That is, the refractive index of the third prism 60 can be limited to the range of [1.45, 1.85]. For example, the refractive index of the third prism 60 can be 1.45, 1.55, 1.65, 1.75, 1.85, and the like, which will not be listed one by one here.

[0114] It is found through research that limiting the refractive index of the third prism 60 to the range of [1.45, 1.85] is conducive to effectively compensating for the optical path difference caused by the light emitted by different light-emitting positions on the image source 10 after propagating in the first prism 20, thereby facilitating the guarantee of the imaging quality of the optical system.

[0115] In some optional embodiments of the present disclosure, the refractive index of the third prism 60 can be greater than or equal to 1.45 and less than 1.547, or the refractive index of the third prism 60 can be greater than 1.547 and less than or equal to 1.85. That is, the refractive index of the third prism 60 can be limited to the range of [1.45, 1.547) U (1.547, 1.85]. For example, the refractive index of the third prism 60 can be 1.45, 1.52, 1.54, 1.546, 1.55, 1.65, 1.75, 1.85, and the like, which will not be listed one by one here.

[0116] In some optional embodiments of the present disclosure, the Abbe number of the third prism 60 can be greater than or equal to 40 and less than or equal to 80. That is, the Abbe number of the third prism 60 can be limited to the range of [40, 80]. For example, the Abbe number of the third prism 60 can be 40, 50, 60, 70, 80, and the like, which will not be listed one by one here.

[0117] It is found through research that limiting the Abbe number of the third prism 60 to the range of [40, 80] is conducive to effectively compensating for the optical path difference caused by the light emitted by different light-emitting positions on the image source 10 after propagating in the first prism 20, thereby facilitating the guarantee of the imaging quality of the optical system.

[0118] In some optional embodiments of the present disclosure, the refractive index of the lens 40 and the second prism 30 can be consistent. Here, the refractive index of the lens 40 and the second prism 30 being consistent can be understood as the refractive index of the two being the same or substantially the same.

[0119] In some optional embodiments of the present disclosure, if the refractive index of the lens 40 and the second prism 30 is consistent, the lens 40 and the second prism 30 can be an integral piece. In this way, the lens 40 and the second prism 30 can be integrally formed. Since the lens 40 and the second prism 30 are integrally formed, compared with the separate lens 40, the edge thickness (for example, the left edge thickness in Figure 2 、 Figures 3-2 to 9-2 a large edge thickness is conducive to reducing the processing difficulty and facilitating mass production.

[0120] In some optional embodiments of the present disclosure, for the light rays in the light rays emitted by the light source 10 that propagate along the optical axis of the lens 40, the optical path length passed by the light rays from the first surface 201 of the first prism 20 to the first time reaching the second film layer 50 is denoted as d, and the focal length of the lens 40 is denoted as f. Then f / d can be greater than or equal to 0.4 and less than or equal to 0.6. That is, f / d can be limited in the range of [0.4, 0.6]. For example, f / d can be 0.4, 0.45, 0.5, 0.51, 0.52, 0.54, 0.57, 0.6, and the like, which will not be listed one by one here.

[0121] It is found through research that limiting f / d in the range of [0.4, 0.6] is conducive to achieving a larger eye relief (ER) and a larger eye box (EB) by a smaller volume of optical system. Limiting f / d in the range of [0.4, 0.6] is also conducive to the correction of field curvature and pupil shift distortion.

[0122] It should be noted that the eye relief (ER) is an important design index in the optical system. The eye relief can refer to the distance from the preset eye position to the plane of the first optical element placed in the optical system (which can be considered as the optical element closest to the preset eye position). For example, Figure 2 Figure 3-1 Figure 3-2 For example, the distance between the human eye 100 and the first surface 601 of the third prism 60 can be used as the eye relief.

[0123] In some optional embodiments of the present disclosure, the refractive index of the first prism 20 can be greater than or equal to 1.45 and less than or equal to 1.85. That is, the refractive index of the first prism 20 can be limited in the range of [1.45, 1.85]. For example, the refractive index of the first prism 20 can be 1.45, 1.5, 1.6, 1.7, 1.8, 1.85, and the like, which will not be listed one by one here.

[0124] It is found through research that limiting the refractive index of the first prism 20 in the range of [1.45, 1.85] is conducive to ensuring the rationality of the parameters of the first prism 20, thereby being conducive to ensuring the imaging quality of the optical system.

[0125] In some optional embodiments of the present disclosure, the refractive index of the first prism 20 is greater than or equal to 1.45 and less than 1.547, or the refractive index of the first prism 20 is greater than 1.547 and less than or equal to 1.85.

[0126] ​​That is, the refractive index of the first prism 20 can be limited in the range of [1.45, 1.547)∪(1.547, 1.85]. For example, the refractive index of the first prism 20 can be 1.45, 1.457, 1.542, 1.546, 1.549, 1.6, 1.7, 1.8, 1.85, and the like, which will not be listed one by one here.

[0127] In some optional embodiments of the present disclosure, the Abbe number of the first prism 20 can be greater than or equal to 40 and less than or equal to 80. That is, the Abbe number of the first prism 20 can be limited in the range of [40, 80]. For example, the Abbe number of the first prism 20 can be 40, 50, 60, 70, 80, and the like, which will not be listed one by one here.

[0128] It is found through research that limiting the Abbe number of the first prism 20 in the range of [40, 80] is conducive to ensuring the rationality of the parameters of the first prism 20, thereby being conducive to ensuring the imaging quality of the optical system.

[0129] In some optional embodiments of the present disclosure, the refractive index of the second prism 30 can be greater than or equal to 1.45 and less than or equal to 1.85. That is, the refractive index of the second prism 30 can be limited in the range of [1.45, 1.85]. For example, the refractive index of the second prism 30 can be 1.45, 1.5, 1.6, 1.7, 1.8, 1.85, and the like, which will not be listed one by one here.

[0130] It is found through research that limiting the refractive index of the second prism 30 in the range of [1.45, 1.85] is conducive to ensuring the rationality of the parameters of the second prism 30, thereby being conducive to ensuring the imaging quality of the optical system.

[0131] In some optional embodiments of the present disclosure, the refractive index of the second prism 30 can be greater than or equal to 1.45 and less than 1.547, or the refractive index of the second prism 30 can be greater than 1.547 and less than or equal to 1.85.

[0132] That is, the refractive index of the second prism 30 can be limited in the range of [1.45, 1.547)∪(1.547, 1.85]. For example, the refractive index of the second prism 30 can be 1.45, 1.5, 1.52, 1.54, 1.545, 1.6, 1.7, 1.8, 1.85, and the like, which will not be listed one by one here.

[0133] In some optional embodiments of the present disclosure, the Abbe number of the second prism 30 can be greater than or equal to 40 and less than or equal to 80. That is, the Abbe number of the second prism 30 can be limited in the range of [40, 80]. For example, the Abbe number of the second prism 30 can be 40, 50, 60, 70, 80, and the like, which will not be listed one by one here.

[0134] It is found through research that limiting the Abbe number of the second prism 30 to the range of [40, 80] is conducive to ensuring the rationality of the parameters of the second prism 30, thereby being conducive to ensuring the imaging quality of the optical system.

[0135] In some optional embodiments of the present disclosure, the lens 40 and the second prism 30 can be separately arranged, and the refractive index of the lens 40 can be greater than or equal to 1.4 and less than or equal to 1.95. That is, if the lens 40 and the second prism 30 are separately arranged, the refractive index of the lens 40 can be different from that of the second prism 30, and can be limited to the range of [1.4, 1.95]. For example, the refractive index of the lens 40 can be 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 1.95, and the like, which will not be listed one by one here.

[0136] It is found through research that, for the case where the lens 40 and the second prism 30 are separately arranged, limiting the refractive index of the lens 40 to the range of [1.4, 1.95] is conducive to ensuring the rationality of the parameters of the lens 40, thereby being conducive to ensuring the imaging quality of the optical system.

[0137] In some optional embodiments of the present disclosure, the Abbe number of the lens 40 can be greater than or equal to 40 and less than or equal to 100. That is, the Abbe number of the lens 40 can be limited to the range of [40, 100]. For example, the Abbe number of the lens 40 can be 40, 50, 60, 70, 80, 90, 100, and the like, which will not be listed one by one here.

[0138] It is found through research that limiting the Abbe number of the lens 40 to the range of [40, 100] is conducive to ensuring the rationality of the parameters of the lens 40, thereby being conducive to ensuring the imaging quality of the optical system.

[0139] In some optional embodiments of the present disclosure, the refractive index of the first additional lens 70 can be greater than or equal to 1.45 and less than or equal to 2.0. That is, the refractive index of the first additional lens 70 can be limited to the range of [1.45, 2.0]. For example, the refractive index of the first additional lens 70 can be 1.45, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, and the like, which will not be listed one by one here.

[0140] It is found through research that limiting the refractive index of the first additional lens 70 to the range of [1.45, 2.0] is conducive to ensuring the rationality of the parameters of the first additional lens 70, thereby being conducive to ensuring the imaging quality of the optical system.

[0141] In some optional embodiments of the present disclosure, the Abbe number of the first additional lens 70 can be greater than or equal to 15 and less than or equal to 100. That is, the Abbe number of the first additional lens 70 can be limited in the range of [15, 100]. For example, the Abbe number of the first additional lens 70 can be 15, 20, 30, 40, 50, 60, 80, 90, 100, etc., which are not listed one by one here.

[0142] It is found through research that limiting the Abbe number of the first additional lens 70 in the range of [15, 100] is conducive to ensuring the rationality of the parameters of the first additional lens 70, thereby being conducive to ensuring the imaging quality of the optical system.

[0143] Some exemplary embodiments of the present disclosure also provide a head-mounted display device. The head-mounted display device can include Figure 12 The frame structure 90 shown and the optical system in any of the above embodiments. The optical system can be mounted on the frame structure 90.

[0144] In some optional embodiments of the present disclosure, the frame structure 90 can be a structure capable of supporting and accommodating the optical system. For example, the frame structure 90 can include, but is not limited to, a glasses frame, a headband, etc.

[0145] In embodiments of the present disclosure, the installation of the optical system can be reliably achieved through the frame structure 90. Through the cooperation of various optical elements in the optical system, the human eye 100 can see the display picture provided by the image source 10, so as to meet the use requirements of the user. In some embodiments, the human eye 100 can also see the external environment.

[0146] It should be noted that the various optional embodiments and optional embodiments disclosed above can be flexibly selected and combined as needed to achieve the corresponding functions and effects, and the present disclosure does not enumerate one by one.

[0147] The basic principles of the present disclosure are described above in combination with specific embodiments, but it should be noted that the advantages, advantages, effects, etc. mentioned in the present disclosure are only examples and not limitations, and these advantages, advantages, effects, etc. cannot be considered as the must-have of each embodiment of the present disclosure. In addition, the specific details disclosed above are only for the purpose of example and for the purpose of understanding, and the above details do not limit the present disclosure to the above specific details.

[0148] Each embodiment in the specification is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between each embodiment can be mutually referred to.

[0149] Those skilled in the art will appreciate that various adaptations and modifications of the application can be configured without departing from the scope and spirit of the application. Therefore, it is to be understood that, within the scope of the appended claims and their equivalents, the application can be practiced otherwise than as specifically described herein.

Claims

1. An optical system comprising: an image source; a first prism having a first surface, a second surface and a third surface, the first surface of the first prism being proximate to the image source; a second prism, the second surface of the first prism being on a side of the first prism distal to the second prism, the third surface of the first prism being on a side of the first prism proximate to the second prism, the second prism having a first surface, the first surface of the second prism being proximate to the third surface of the first prism; a lens, the lens being on a side of the second prism distal to the first prism, a first included angle between the first surface of the second prism and an optical axis of the lens and a second included angle between the third surface of the first prism and the optical axis of the lens each being an acute angle, and the first included angle being equal to the second included angle; a first film layer, the first film layer being on the second surface of the first prism, capable of reflecting light and transmitting light; a second film layer, the second film layer being on a side of the lens distal to the second prism, capable of reflecting light; an anti-reflection film, the anti-reflection film being on at least one surface of at least one of the first prism, the second prism and the lens; wherein light emitted by the image source is incident on the first prism from the first surface of the first prism, after at least one total internal reflection in the first prism, is reflected by the first film layer, is emitted from the third surface of the first prism and is incident on the second prism from the first surface of the second prism, after passing through the second prism and the lens is reflected by the second film layer, the light after being reflected by the second film layer passes through the lens, the first surface of the second prism, the third surface of the first prism and the second surface of the first prism in sequence and is emitted via the first film layer.

2. The optical system of claim 1, wherein, an included angle between the second surface of the first prism and a plane perpendicular to the optical axis of the lens is a third included angle, an included angle between the first surface of the first prism and the third surface of the first prism is a fourth included angle, and the fourth included angle is greater than twice the third included angle.

3. The optical system of claim 2, wherein, an included angle between the third surface of the first prism and a plane perpendicular to the optical axis of the lens is a fifth included angle, and the fourth included angle is equal to a sum of the fifth included angle and twice the third included angle.

4. The optical system of claim 2, wherein, an included angle between the third surface of the first prism and a plane perpendicular to the optical axis of the lens is a fifth included angle, and an absolute value of a difference between the sum of the fifth included angle and twice the third included angle and the fourth included angle is less than or equal to 0.8 degrees.

5. The optical system of claim 2, wherein, an included angle between the third surface of the first prism and a plane perpendicular to the optical axis of the lens is a fifth included angle, and a ratio of twice a sum of the third included angle and the fifth included angle to a complement of the third included angle is greater than 0.

9.

6. The optical system of claim 2, wherein, an included angle between the third surface of the first prism and a plane perpendicular to the optical axis of the lens is a fifth included angle, and a difference between twice a sum of the third included angle and the fifth included angle and a complement of the third included angle is greater than -6 degrees.

7. The optical system of claim 2, wherein, An included angle between the third surface of the first prism and a plane perpendicular to the optical axis of the lens is a fifth included angle, and the fifth included angle is greater than 5 degrees and less than 15 degrees.

8. The optical system of claim 7, wherein, The fifth included angle is greater than 5 degrees and less than 8 degrees, or the fifth included angle is greater than 8 degrees and less than 15 degrees.

9. The optical system of claim 7, wherein, The fifth included angle is greater than or equal to 7.5 degrees and less than or equal to 8 degrees.

10. The optical system of claim 7, wherein, The fifth included angle is greater than 8.1 degrees and less than 8.7 degrees.

11. The optical system of claim 7, wherein, The fifth included angle is greater than or equal to 8.7 degrees and less than or equal to 9.3 degrees.

12. The optical system of claim 7, wherein, The fifth included angle is greater than or equal to 9.4 degrees and less than or equal to 9.8 degrees.

13. The optical system of claim 2, wherein, The third included angle is greater than 20 degrees and less than 30 degrees.

14. The optical system of claim 1, further comprising: a compensation member, the compensation member being located close to the second surface of the first prism, and the light reflected by the second film layer again passing through the first prism and then passing through the compensation member before exiting.

15. The optical system of claim 14, wherein, The compensation member is a third prism, the third prism having a first surface and a second surface, the first surface of the third prism being located on a side of the third prism away from the first prism, and the second surface of the third prism being located on a side of the third prism close to the first prism, the light reflected by the second film layer again passing through the first prism and then passing through the second surface of the third prism and the first surface of the third prism before exiting.

16. The optical system of claim 15, wherein, The refractive indexes of the first prism, the second prism and the third prism are consistent.

17. The optical system of claim 15, wherein, The first surface of the third prism is a curved surface.

18. The optical system of claim 15, wherein, The refractive index of the third prism is greater than or equal to 1.45 and less than or equal to 1.

85.

19. The optical system of claim 15, wherein, The Abbe number of the third prism is greater than or equal to 40 and less than or equal to 80.

20. The optical system of claim 1, wherein, A part of the second surface of the first prism close to the image source has a groove, the groove being recessed from the part of the second surface to the inside of the first prism.

21. The optical system of claim 1 or 20, wherein, The part of the second surface of the first prism close to the image source is coated black.

22. The optical system of claim 1 or 20, wherein, The part of the second surface of the first prism close to the image source is a rough surface.

23. The optical system of claim 1, wherein, The refractive indexes of the lens and the second prism are consistent.

24. The optical system of claim 23, wherein, The lens and the second prism are an integral part.

25. The optical system of claim 1, wherein, For the light propagating along the optical axis of the lens among the light emitted by the image source, the optical path length from the first surface of the first prism to the second film layer for the first time is represented as d, and the focal length of the lens is represented as f, and f / d is greater than or equal to 0.4 and less than or equal to 0.

6.

26. The optical system of claim 1, wherein, The refractive index of the first prism is greater than or equal to 1.45 and less than or equal to 1.

85.

27. The optical system of claim 1, wherein, The Abbe number of the first prism is greater than or equal to 40 and less than or equal to 80.

28. The optical system of claim 1, wherein, The first surface of the first prism is a curved surface.

29. The optical system of claim 1, wherein, The refractive index of the second prism is greater than or equal to 1.45 and less than or equal to 1.

85.

30. The optical system of claim 1, wherein, The Abbe number of the second prism is greater than or equal to 40 and less than or equal to 80.

31. The optical system of claim 1, wherein, The lens and the second prism are separately arranged, the refractive index of the lens is greater than or equal to 1.4 and less than or equal to 1.

95.

32. The optical system of claim 1, wherein, The Abbe number of the lens is greater than or equal to 40 and less than or equal to 100.

33. The optical system of claim 1, further comprising: a first additional lens between the image source and the first surface of the first prism; wherein the light emitted by the image source is incident on the first prism after passing through the first additional lens.

34. The optical system of claim 33, wherein, The first additional lens has a refractive index greater than or equal to 1.45 and less than or equal to 2.

0.

35. The optical system of claim 33, wherein, The first additional lens has an Abbe number greater than or equal to 15 and less than or equal to 100.

36. The optical system of claim 1, wherein, The second film layer is a semi-transmissive and semi-reflective film, and the optical system further comprises: a second additional lens on a side of the second film layer away from the lens.

37. A head-mounted display device comprising: a frame structure; the optical system of any one of claims 1-36 mounted to the frame structure.

Images