Optical system and head-mounted display device

Abstract

The embodiment of the invention 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 Art

[0002] At present, head-mounted display devices are increasingly widely used. Head-mounted display devices can be used to display content. For example, head-mounted display devices can be used to display movie images, game images, web pages, etc. The optical system is an important component of the head-mounted display device. Summary of the invention

[0003] According to one 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; and a lens, the lens being located on a side of the second prism away from the first prism, the first angle between the first surface of the second prism and the optical axis of the lens and the second angle between the third surface of the first prism and the optical axis of the lens being both acute angles, and The first angle is equal to the second angle; the first film layer, the first film layer is located on the second surface of the first prism, and can reflect and transmit light; the second film layer, the second film layer is located on the side of the lens away from the second prism, and can reflect light; wherein, the light emitted by the image source enters the first prism from the first surface of the first prism, is reflected by the first film layer after at least one total reflection in the first prism, is emitted from the third surface of the first prism and enters the second prism from the first surface of the second prism, is reflected by the second film layer after passing through the second prism and the lens, 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 through the first film layer.

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

[0005] The technical solution of the present disclosure is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The above and other purposes, features and advantages of the present disclosure will become more apparent by describing the embodiments of the present disclosure in more detail in conjunction with the accompanying drawings. The accompanying drawings are used to provide a further understanding of the embodiments of the present disclosure and constitute a part of the specification. Together with the embodiments of the present disclosure, they are used to explain the present disclosure and do not constitute a limitation of the present disclosure. In the drawings, the same reference numerals generally represent the same components or steps; Figure 1 is a schematic diagram of the structure of an optical system provided by some exemplary embodiments of the present disclosure; Figure 2 is a schematic diagram of the structure of an optical system provided by some other exemplary embodiments of the present disclosure; Figure 3-1 is a schematic structural diagram of an optical system provided by some further exemplary embodiments of the present disclosure; Figure 3-2 is a schematic structural diagram of an optical system provided by some further exemplary embodiments of the present disclosure; Figure 4 is a schematic structural diagram of an optical system provided by some further exemplary embodiments of the present disclosure; Figure 5 is a schematic structural diagram of an optical system provided by some further exemplary embodiments of the present disclosure; Figure 6 is a schematic structural diagram of an optical system provided by some further exemplary embodiments of the present disclosure; Figure 7 is a schematic structural diagram of an optical system provided by some further exemplary embodiments of the present disclosure; Figure 8 is a schematic structural diagram of an optical system provided by some further exemplary embodiments of the present disclosure; Figure 9-1 is a schematic structural diagram of an optical system provided by some further exemplary embodiments of the present disclosure; Figure 9-2 is a schematic structural diagram of an optical system provided by some further exemplary embodiments of the present disclosure; Figure 10-1 is a schematic diagram of the effect of an optical system provided by some exemplary embodiments of the present disclosure; Figure 10-2 is a schematic diagram of the effects of optical systems provided by other exemplary embodiments of the present disclosure; Figure 10-3 is a schematic diagram of the effect of an optical system provided by some further exemplary embodiments of the present disclosure; Figure 11-1 is a schematic structural diagram of an optical system provided by some further exemplary embodiments of the present disclosure; Figure 11-2 is a schematic structural diagram of an optical system provided by some further exemplary embodiments of the present disclosure; Figure 11-3 is a schematic structural diagram of an optical system provided by some further exemplary embodiments of the present disclosure; Figure 11-4 is a schematic structural diagram of an optical system provided by some further exemplary embodiments of the present disclosure; Fig.12 is a schematic diagram of a frame structure in some exemplary embodiments of the present disclosure.

[0007] In the figure, 10, image source; 20, first prism; 30, second prism; 40, lens; 45, first film layer; 50, second film layer; 201, first surface of first prism; 203, second surface of first prism; 205, third surface of first prism; 207, groove; 100, human eye; 301, first surface of second prism; V: light incident on first prism from first surface of first prism; 60, third prism; 601, first surface of third prism; 603, second surface of third prism; 70, first additional lens; 80, second additional lens; Z, axis; ∠R1, angle between first surface of second prism and optical axis of lens; ∠R2, angle between third surface of first prism and optical axis of lens Angle; U1, center thickness of one optical system; U2, center thickness of another optical system; P, position to which the first common edge needs to be moved; ∠A, angle between the second surface of the first prism and the target plane; ∠C, angle between the first surface of the first prism and the third surface of the first prism; ∠B, angle between the third surface of the first prism and the target plane; ∠Q, angle between the first surface of the second prism and the target plane; ∠E, angle between the light incident from the first surface of the first prism and the third surface of the first prism when projected onto the third surface of the first prism; ∠R3, angle between the normal of the image source and the optical axis of the lens; ∠R4, angle between the second surface of the first prism and the optical axis of the lens; 90, frame structure. DETAILED DESCRIPTION

[0008] Below, the exemplary embodiments according to the present disclosure will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all the embodiments of the present disclosure, and it should be understood that the present disclosure is not limited to the exemplary embodiments described here.

[0009] In the description of the present disclosure, the terms "up", "down", "left", "right", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present disclosure and simplifying the description, rather than indicating or implying that the device referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present disclosure.

[0010] In the description of the present disclosure, unless otherwise clearly specified and limited, the terms "installation", "connection", "fixation" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present disclosure can be understood according to specific circumstances.

[0011] Exemplary Overview Head-mounted display devices can also be called head-mounted displays (HMD) or head-mounted displays. Head-mounted display devices can be used to achieve augmented reality (AR) effects, virtual reality (VR) effects, mixed reality (MR) effects, etc. Head-mounted display devices can be presented in the form of glasses, helmets, etc.

[0012] The optical system is an important part of the head-mounted display device. The optical system can also be called an optical machine. The optical system can be used to emit light and process the light so that the light enters the eye box of the optical system. When the user wears the head-mounted display device, the user's eyes can be located in the eye box, the light can be projected to the user's eyes, and the user can see the display screen. Therefore, in order to ensure the user experience, it is necessary to design the optical system reasonably.

[0013] Exemplary Structure Some exemplary embodiments of the present disclosure provide an optical system. The optical system provided by the embodiments of the present disclosure may include an image source, a prism, and a lens.

[0014] For example, Figure 1 As shown, the optical system provided by the embodiment of the present disclosure may include an image source 10 , a first prism 20 and a lens 40 .

[0015] In some optional embodiments of the present disclosure, the image source 10 can be used to emit light for displaying a picture. The image source 10 can include, but is not limited to, an organic light emitting diode (OLED) image source, a liquid crystal (LCOS) image source, a microelectromechanical system (MEMS) image source, a digital micromirror device (DMD), etc. For example, the image source 10 can be an OLED display screen.

[0016] In some optional embodiments of the present disclosure, the first prism 20 can be used to extend the 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 with the second surface 203, the first surface 201 can intersect with the third surface 205, and the second surface 203 can intersect with 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 planes, and the first prism 20 can be a triangular prism. In an optional 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.

[0017] It can be understood that the "intersection" or "angle" described in the present disclosure can be the actual intersection of two elements or the actual angle between the two elements. If the two elements do not actually intersect or form an angle between the two elements, after the two elements are extended along their respective extension directions, the expanded parts that do not actually exist can also intersect or form an angle, satisfying the relevant limitations in the embodiments of the present disclosure.

[0018] In some embodiments, the first surface 201 of the first prism 20 may also be a curved surface to optimize field curvature and pupil distortion.

[0019] In some optional embodiments of the present disclosure, the lens 40 can be used to assume 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 the side of the first prism 20 away from the lens 40. The third surface 205 of the first prism 20 can be located on the 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 the side of the first prism 20 close to the eye box of the optical system.

[0020] It will be appreciated that the eye box of the optical system may be a human eye (e.g. Figure 1 The eye box of the optical system is also called the Eye Box or EB. The size of the eye box of the optical system is an important design indicator in the optical system.

[0021] In some optional embodiments of the present disclosure, Figure 1As shown, the optical system provided by the embodiment of the present disclosure may also include a film layer, for example, a first film layer 45 and a second film layer 50. The first film layer 45 may be located on the second surface 203 of the first prism 20, and may reflect and transmit light. The first film layer 45 may be a semi-transparent and semi-reflective film without a light splitting capability, or a polarized light splitting film. The first film layer 45 may be disposed on the second surface 203 of the first prism 20 by bonding, coating, or the like. The second film layer 50 may be located on a side of the lens 40 away from the first prism 20, and may reflect light. The second film layer 50 may be used to fully reflect or partially reflect light, and thus, the second film layer 50 may be a fully reflective film or a semi-transparent and semi-reflective film. The second film layer 50 may be disposed on a side of the lens 40 away from the first prism 20 by bonding, coating, or the like.

[0022] It should be noted that the light emitted by the image source 10 can enter the first prism 20 from the first surface 201 of the first prism 20, and after at least one total reflection in the first prism 20, it is reflected by the first film layer 45, and is emitted from the third surface 205 of the first prism 20, and is reflected by the second film layer 50 after passing through the lens 40. The light reflected by the second film layer 50 passes through the lens 40, the third surface 205 of the first prism 20, and the second surface 203 of the first prism 20 in sequence, and is emitted through the first film layer 45. The light emitted from the first film layer 45 can enter the eye box of the optical system.

[0023] In the optical system provided by the embodiment of the present disclosure, the light emitted by the image source 10 can enter the eye box of the optical system through the coordinated use 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 image provided by the image source 10. Therefore, the head-mounted display device can display content normally to meet the user's usage needs, such as meeting the user's viewing needs.

[0024] In some optional embodiments of the present disclosure, Figure 2 , Figure 3-1 , Figure 3-2 As shown, the optical system provided by the embodiment of the present disclosure may 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 may 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 may be located on the side of the first prism 20 close to the second prism 30. The second prism 30 may have a first surface 301. The first surface 301 of the second prism 30 may be close to the third surface 205 of the first prism 20. The first surface 301 of the second prism 30 may be a plane. The first surface 301 of the second prism 30 and the third surface 205 of the first prism 20 may be opposite to each other and there is a gap.

[0025] In some optional embodiments of the present disclosure, the lens 40 may be located on a side of the second prism 30 away from the first prism 20. The lens 40 and the second prism 30 may be an integral part, for example, Figure 2 , Figure 3-2 Alternatively, the lens 40 and the second prism 30 may be disposed separately, for example, see Figure 3-1 . If the lens 40 and the second prism 30 are an integral part, 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 provided, the lens 40 and the second prism 30 can be injection molded separately and fixedly connected 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 an aspherical surface. For example, the surface of the lens 40 away from the second prism 30 can be a rotationally symmetric aspherical surface.

[0026] 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, and after at least one total reflection in the first prism 20, it is reflected by the first film layer 45, emitted from the third surface 205 of the first prism 20 and incident on the second prism 30 from the first surface 301 of the second prism 30, and is reflected by the second film layer 50 after passing through the second prism 30 and the lens 40. 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 sequence, and is emitted through the first film layer 45.

[0027] In some optional embodiments of the present disclosure, the light (eg, Figure 2 The light V in the figure may first be totally reflected once on the third surface 205 of the first prism 20, then be reflected once on the second surface 203 of the first prism 20 (may be reflected by the first film layer 45), then be emitted 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 number of total reflections experienced by the light incident on the first prism 20 from the first surface 201 of the first prism 20 in the first prism 20 before being emitted from the third surface 205 of the first prism 20 may not be limited to one, and the number of reflections experienced in the first prism 20 may not be limited to one. For example, after a total reflection occurs once on the third surface 205 of the first prism 20 and a reflection occurs once on the second surface 203 of the first prism 20, a total reflection may occur again on the third surface 205 of the first prism 20, and a reflection may occur again on the second surface 203 of the first prism 20, and then be emitted from the third surface 205 of the first prism 20.

[0028] The light emitted 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 entering the second prism 30 can propagate to the second film layer 50 after passing through the second prism 30 and the lens 40 in sequence. The second film layer 50 can reflect the light to adjust the propagation direction of the light. For example, see Figure 2 The second film layer 50 can adjust the propagation direction of the light from horizontal rightward to horizontal leftward. In this way, the light 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 reach the eye box of the optical system.

[0029] In the optical system provided by the embodiment of the present disclosure, the light emitted by the image source 10 can enter the eye box of the optical system through the coordinated use 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 image provided by the image source 10. Therefore, the head-mounted display device can display content normally to meet the user's usage needs, such as meeting the user's viewing needs.

[0030] In some optional embodiments of the present disclosure, the optical system may further include a compensating member. The compensating member may play a role in compensating for the deflection of light in the first prism 20, and may also play a role in optical path compensation, so as to compensate for the optical path difference generated by light emitted from different light-emitting positions on the image source 10 after propagating in the first prism 20, so that the optical paths of light emitted from different light-emitting positions are substantially the same. The compensating member may be close to the second surface 203 of the first prism 20. After the light reflected by the second film layer 50 passes through the first prism 20 again, it is emitted through the compensating member. For example, the light emitted by the image source 10 may propagate along the following target path: first prism 20 → first film layer 45 → first prism 20 → second prism 30 → lens 40 → second film layer 50 → lens 40 → second prism 30 → first prism 20 → first film layer 45 → compensating member → eye box of the optical system.

[0031] In this way, when the compensating element is introduced, the light emitted by the image source 10 can enter the eye box of the optical system. In this way, the human eye 100 can see the display image provided by the image source 10. In addition, when the compensating element is introduced, it is also beneficial to ensure that the optical path of the light emitted from different light-emitting positions is basically the same, and it is beneficial to compensate for the deflection of the light in the first prism 20, thereby improving the imaging quality of the optical system.

[0032] In some optional embodiments of the present disclosure, Figures 2 to 5As shown, the compensating member may be a third prism 60. The third prism 60 may have a first surface 601 and a second surface 603. The first surface 601 of the third prism 60 may be located on a side of the third prism 60 away from the first prism 20. The second surface 603 of the third prism 60 may be located on a side of the third prism 60 close to the first prism 20. After the light reflected by the second film layer 50 passes through the first prism 20 again, it is emitted after passing through the second surface 603 of the third prism 60 and the first surface 601 of the third prism 60.

[0033] Optionally, the first surface 601 and the second surface 603 of the third prism 60 may both be planes, for example, see Figure 2 , Figure 3-1 , Figure 3-2 Alternatively, the first surface 601 of the third prism 60 may be a curved surface, and the second surface 603 of the third prism 60 may be a flat surface. For example, see Figure 4 , Figure 5 The first surface 601 and the second surface 603 of the third prism 60 may intersect. The first film layer 45 may be a polarization beam splitter film located between the second surface 603 of the third prism 60 and the second surface 203 of the first prism 20. A quarter wave plate may be provided between the third surface 205 of the first prism 20 and the first surface 301 of the second prism 30. The polarization beam splitter film and the quarter wave plate may be used in conjunction with each other so that the light emitted by the image source 10 propagates along the target path described above.

[0034] After the light reflected by the second film layer 50 passes through the first prism 20 again, it can be emitted from the second surface 203 of the first prism 20 and enter 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 it reaches the eye box of the optical system.

[0035] In this way, when the compensating member is the third prism 60, the light emitted by the image source 10 can enter the eye box of the optical system. In this way, the human eye 100 can see the display screen provided by the image source 10. In addition, the third prism 60 is conducive to ensuring that the optical path of the light emitted from different light-emitting positions is basically the same, and is conducive to compensating for the deflection of the light in the first prism 20, thereby improving the imaging quality of the optical system. In addition, the surface shape of the third prism 60 is simple and easy to process.

[0036] In some optional embodiments of the present disclosure, Figures 4 to 8 As shown, the optical system may further include a first additional lens 70. The first additional lens 70 may 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 may enter the first prism 20 after passing through the first additional lens 70.

[0037] Optionally, the first additional lens 70 may be a positive lens. For example, the first additional lens 70 may be a plano-convex lens. For another example, the first additional lens 70 may be a biconvex lens.

[0038] 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 enter the first prism 20 from the first surface 201 of the first prism 20. The first additional lens 70 can be an aspherical lens, which is beneficial to correct aberrations to ensure the imaging quality of the optical system.

[0039] 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.

[0040] In some optional embodiments of the present disclosure, the second film layer 50 may be a semi-transparent and semi-reflective film. Figure 5 , Figure 7 , Figure 8 As shown, the optical system may further include a second additional lens 80. The second additional lens 80 may be located on a side of the second film layer 50 away from the lens 40.

[0041] Optionally, the second additional lens 80 may be attached to the second film layer 50 . Alternatively, there may be a gap between the second additional lens 80 and the second film layer 50 .

[0042] 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 in the external environment (also referred to as ambient light) can sequentially 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 reach the eye box of the optical system. In this way, the ambient light can enter the human eye 100 without deflection, and the user can see the non-distorted ambient image when wearing the head-mounted display device to observe the external environment.

[0043] In some embodiments, the first surface 601 of the third prism 60 may be a curved surface, for example, a concave surface, which can effectively compensate for the optical focal length of the lens 40. In this case, there is no need to additionally set up a second additional lens 80 serving as a compensating lens for the lens 40.

[0044] In some optional embodiments of the present disclosure, Figure 8 , Figure 9-1 , Figure 9-2 As shown, a partial area of ​​the second surface 203 of the first prism 20 close to the image source 10 may have a groove 207. The groove 207 may be recessed from the partial area (hereinafter referred to as the target area) toward the inside of the first prism 20.

[0045] Optionally, the common edge between the first surface 601 of the third prism 60 and the second surface 603 of the third prism 60 may be represented as a first common edge. The target area may be located in an area of ​​the second surface 203 of the first prism 20, located between the first surface 201 of the first prism 20 and the first common edge. The groove 207 may be a V-shaped groove.

[0046] It should be noted that, from the edge area of ​​the image source 10 (for example Figure 2 to Figure 9-2 After the light emitted from the first surface 201 of the first prism 20 enters the first prism 20, it may be directly projected to the target area of ​​the second surface 203 of the first prism 20 (that is, it is not first projected to the third surface 205 of the first prism 20 according to the designed light path). If the light directly projected to the target area of ​​the second surface 203 of the first prism 20 subsequently reaches the eye box of the optical system together with the normal light path, it may cause ghosting, and the imaging quality of the optical system cannot be guaranteed. Through research, it is found that by setting a groove 207 in a part of the second surface 203 of the first prism 20 close to the image source 10, the propagation path of the light directly projected to the target area of ​​the second surface 203 of the first prism 20 can be changed, so that the light cannot reach the eye box of the optical system. For example, the light does not meet the total reflection condition (for example, the condition that the incident angle is greater than or equal to the critical angle is not met), which is conducive to eliminating ghosting and ensuring the imaging quality of the optical system.

[0047] In some optional embodiments of the present disclosure, a portion of the second surface 203 of the first prism 20 close to the image source 10 may be coated black. For example, the groove wall of the groove 207 may be coated black.

[0048] Optionally, the groove wall of the groove 207 can be coated black by a coating process. In this way, the light directly projected to the target area of ​​the second surface 203 of the first prism 20 will be absorbed without total reflection, which is conducive to eliminating ghost images and ensuring the imaging quality of the optical system.

[0049] In some optional embodiments of the present disclosure, a portion of the second surface 203 of the first prism 20 close to the image source 10 may be a rough surface. For example, the groove wall of the groove 207 may be a rough surface.

[0050] Optionally, the groove wall of the groove 207 may have a greater surface roughness. In this way, the light directly projected onto the target area of ​​the second surface 203 of the first prism 20 will be diffusely reflected instead of totally reflected, which is beneficial to eliminate ghost images and ensure the imaging quality of the optical system.

[0051] In some optional embodiments of the present disclosure, the first angle between the first surface 301 of the second prism 30 and the optical axis of the lens 40 and the second angle between the third surface 205 of the first prism 20 and the optical axis of the lens 40 may both be acute angles, and the first angle may be equal to the second angle. Herein, the first angle may be equal to the second angle, which may be understood as the two angles being equal or substantially the same.

[0052] Alternatively, the optical axis of lens 40 may be expressed as Figure 2 The axis Z in the lens 40. The first surface 301 of the second prism 30 can be tilted relative to the optical axis of the lens 40 so that a first 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 so that a second angle between the third surface 205 of the first prism 20 and the optical axis of the lens 40 is an acute angle. The inclination of the third surface 205 of the first prism 20 relative to the optical axis of the lens 40 and the inclination of the first surface 301 of the second prism 30 relative to the optical axis of the lens 40 can be consistent. The inclination 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 angle between the first surface 301 of the second prism 30 and the optical axis of the lens 40. The first angle can be referred to Figure 2 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 angle between the third surface 205 of the first prism 20 and the optical axis of the lens 40. The second angle can be seen in Figure 2 Here, ∠R1 and ∠R2 may both be between 0 degrees and 90 degrees, and ∠R1 and ∠R2 may be equal.

[0053] Figure 10-1 , Figure 10-2 , Figure 10-3 Two optical systems are shown in each. Figure 10-1 , Figure 10-2 , Figure 10-3In any of the three, the optical system on the right side presents a situation where 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 is consistent with the inclination of the first surface 301 of the second prism 30 relative to the optical axis of the lens 40, and the optical system on the left side presents a situation where the third surface 205 of the first prism 20 and the first surface 301 of the second prism 30 are not inclined relative to the optical axis of the lens 40 (that is, ∠R1 and ∠R2 are basically right angles). In addition, the thickness (center thickness) of the optical system on the left side along the optical axis of the lens 40 can be expressed as U1, and the thickness (center thickness) of the optical system on the right side along the optical axis of the lens 40 can be expressed as U2, and U1 and U2 are the same. It should be noted that Figure 10-1 It indicates Figure 2 to Figure 9-2 The direction of the light emitted from a certain point in the right half of the image source 10, Figure 10-2 It indicates Figure 2 to Figure 9-2 The direction of the light emitted from a certain point in the left half of the middle image source 10, Figure 10-3 At the same time, Figure 2 to Figure 9-2 The direction of light emitted from a certain point in the left half area and a certain point in the right half area of ​​the central image source 10. The dotted line in the figure represents the optical axis of the optical system.

[0054] The eye box of the optical system needs to cover the light from all areas of the image source 10 to ensure the user experience. Figure 10-3 In the figure, the bold vertical line indicates the size of the eye box of the optical system in the cross section. By comparing the two optical systems, it can be seen that when the center thickness is the same and the same field of view angle is achieved, the size of the eye box of the optical system on the left is smaller than the size of the eye box of the optical system on the right. Therefore, in the embodiment of the present disclosure, by making the third surface 205 of the first prism 20 and the first surface 301 of the second prism 30 both inclined relative to the optical axis of the lens 40, and making the inclination of the third surface 205 of the first prism 20 relative to the optical axis of the lens 40 consistent with the inclination 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 eye box at the same center thickness and the same field of view. In addition, it can be seen by observation that if the size of the eye box of the optical system on the right is to be reduced to the size of the eye box of the optical system on the left, the first common edge mentioned above (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) can be moved to Figure 10-1Position P in the image. Obviously, if the first common edge is moved to position P, U2, which is the center thickness of the optical system located on the right side, will also be reduced. Therefore, in the embodiment of the present disclosure, by making the third surface 205 of the first prism 20 and the first surface 301 of the second prism 30 both inclined relative to the optical axis of the lens 40, and making the inclination of the third surface 205 of the first prism 20 relative to the optical axis of the lens 40 consistent with the inclination of the first surface 301 of the second prism 30 relative to the optical axis of the lens 40, it is also beneficial to achieve a smaller center thickness under the same field of view angle and the same size of eye box, thereby facilitating the miniaturization and lightweight of the optical system.

[0055] 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, then the fourth angle may be greater than twice the third angle.

[0056] For ease of description, the plane perpendicular to the optical axis of the lens 40 may be referred to as the target plane. The angle (ie, the third angle) between the second surface 203 of the first prism 20 and the target plane may be expressed as Figure 2 The angle between the third surface 205 of the first prism 20 and the target plane (ie, the fifth angle hereinafter) can be expressed as: Figure 2 The angle between the first surface 201 of the first prism 20 and the third surface 205 of the first prism 20 (ie, the third angle) can be expressed as: Figure 2 ∠C shown.

[0057] In some optional embodiments of the present disclosure, ∠C≠2∠A. For example, ∠C>2∠A.

[0058] Optionally, the common edge between the second surface 203 of the first prism 20 and the third surface 205 of the first prism 20 may be referred to as a second common edge. The target plane may be a plane passing through the second common edge and having a plane that is parallel to the first prism 20. Figure 2 The plane perpendicular to the axis Z in the.

[0059] It can be understood that when the prism has a tip, the two adjacent surfaces extend until they touch each other, forming an actual common edge. When the prism does not have a tip, that is, the two adjacent surfaces cannot extend until they touch each other, but are terminated at different positions, the common edge can be the edge formed by the two adjacent surfaces theoretically extending and touching each other.

[0060] For the case where the third surface 205 of the first prism 20 and the first surface 301 of the second prism 30 described above are not tilted relative to the optical axis of the lens 40, ∠C=2∠A can be obtained. By setting ∠C≠2∠A, the optical system provided by the embodiment of the present disclosure can be clearly distinguished from the optical system in this case. For example, in the optical system provided by the embodiment 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 tilted 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 conducive to achieving a larger eye box at the same center thickness and the same field of view, and it is conducive to achieving a smaller center thickness at the same field of view and the same size of the eye box, thereby facilitating the miniaturization and lightweighting of the optical system.

[0061] In some optional embodiments of the present disclosure, the fourth angle may be equal to the sum of the fifth angle and twice the third angle, that is, ∠C=2∠A+∠B.

[0062] 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°.

[0063] Optionally, |∠C-(2∠A+∠B)| may be equal to 0, that is, ∠C and (2∠A+∠B) may be the same. Of course, ∠C and (2∠A+∠B) may be different but close enough, that is, ∠C and (2∠A+∠B) may be substantially the same. For example, |∠C-(2∠A+∠B)| may be equal to 0.1°, 0.2°, 0.7°, etc., which are not listed here one by one.

[0064] By using the constraint condition of |∠C-(2∠A+∠B)|≤0.8°, ∠C can be made the same or substantially the same as (2∠A+∠B). Through research, it is found that ∠C is the same or substantially the same as (2∠A+∠B), which is conducive to ensuring that for the optical system provided by the embodiment of the present disclosure, the light emitted by the image source 10 propagates along the target path introduced above.

[0065] In some optional embodiments of the present disclosure, the ratio of twice the sum of the third angle and the fifth angle to the complementary angle of the third angle is greater than 0.9, that is, 2(∠A+∠B) / (90°-∠A)>0.9.

[0066] In some optional embodiments of the present disclosure, the difference between twice the sum of the third angle and the fifth angle and the complementary angle of the third angle is greater than negative 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°.

[0067] Through geometric derivation, it can be known 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. The angle between the normal line of the image source 10 and the optical axis of the lens 40 can be expressed as 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. The angle between the second surface 203 of the first prism 20 and the optical axis of the lens 40 can be expressed as Figure 2 ∠R4 in the figure. Through research, it is found that limiting ∠A and ∠B to 2(∠A+∠B) / (90°-∠A)>0.9, 3∠A+∠2B-90°>-6° is conducive to keeping the light that may form ghost images as far away from the effective display screen as possible, so as to ensure the imaging quality of the optical system.

[0068] In some optional embodiments of the present disclosure, the fifth angle may be greater than 5 degrees and less than 15 degrees. That is, ∠B may be greater than 5° and less than 15°. In other words, ∠B may be limited to the range of (5°, 15°). For example, ∠B may be 6°, 7°, 8°, 9°, 10°, 11°, 12°, 13°, 14°, etc., which are not listed here one by one.

[0069] Through research, it is found that limiting ∠B within the range of (5°, 15°) is beneficial to ensuring the rationality of the parameters of the first prism 20, thereby ensuring the imaging quality of the optical system.

[0070] In some optional embodiments of the present disclosure, the fifth angle may be greater than 5 degrees and less than 8 degrees, or the fifth angle may be greater than 8 degrees and less than 15 degrees. That is, ∠B may be greater than 5° and less than 8°, or ∠B may be greater than 8° and less than 15°. In other words, ∠B may be limited to the range of (5°, 8°) ∪ (8°, 15°). For example, ∠B may be 6°, 7°, 9°, 10°, 11°, 12°, 13°, 14°, etc., which are not listed here one by one.

[0071] In some optional embodiments of the present disclosure, the fifth angle may be greater than or equal to 7.5 degrees and less than or equal to 8 degrees. That is, ∠B may be greater than or equal to 7.5° and less than or equal to 8°. In other words, ∠B may be limited to the range of [7.5°, 8°]. For example, ∠B may be 7.5°, 7.7°, 7.8°, 7.9°, 8°, etc., which are not listed here one by one.

[0072] In some optional embodiments of the present disclosure, the fifth angle may be greater than 8.1 degrees and less than 8.7 degrees. That is, ∠B may be greater than 8.1 degrees and less than 8.7 degrees. In other words, ∠B may be limited to the range of (8.1 degrees, 8.7 degrees). For example, ∠B may be 8.2 degrees, 8.3 degrees, 8.4 degrees, 8.5 degrees, 8.6 degrees, etc., which are not listed here one by one.

[0073] In some optional embodiments of the present disclosure, the fifth angle may be greater than or equal to 8.7 degrees and less than or equal to 9.3 degrees. That is, ∠B may be greater than or equal to 8.7° and less than or equal to 9.3°. In other words, ∠B may be limited to the range of [8.7°, 9.3°]. For example, ∠B may be 8.7°, 8.8°, 8.9°, 9.1°, 9.2°, 9.3°, etc., which are not listed here one by one.

[0074] In some optional embodiments of the present disclosure, the fifth angle may be greater than or equal to 9.4 degrees and less than or equal to 9.8 degrees. That is, ∠B may be greater than or equal to 9.4° and less than or equal to 9.8°. In other words, ∠B may be limited to the range of [9.4°, 9.8°]. For example, ∠B may be 9.4°, 9.5°, 9.6°, 9.7°, 9.8°, etc., which are not listed here one by one.

[0075] In some optional embodiments of the present disclosure, the third angle may be greater than 20 degrees and less than 30 degrees. That is, ∠A may be greater than 20° and less than 30°. In other words, ∠A may be limited to the range of (20°, 30°). For example, ∠A may be 21°, 23°, 24°, 25°, 27°, 28°, 29°, etc., which are not listed here one by one.

[0076] Through research, it is found that limiting ∠A within the range of (20°, 30°) is beneficial to ensuring the rationality of the parameters of the first prism 20, thereby ensuring the imaging quality of the optical system.

[0077] In some optional embodiments of the present 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.

[0078] Optionally, the angle between the third surface 205 of the first prism 20 and the target plane may be equal to Figure 2 As shown in ∠B, the angle between the first surface 301 of the second prism 30 and the target plane can be equal to Figure 2 ∠Q in , 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 may be parallel to each other.

[0079] Through research, it is found that if ∠Q=∠B, then ∠R2=∠R1, ∠C=2∠A+∠B. In this way, it can be ensured that for the optical system provided by the embodiment of the present disclosure, the light emitted by the image source 10 propagates along the target path mentioned above.

[0080] By observation Figure 2 It can be seen that ∠R1=90°-∠Q=90°-∠B. Assuming that the light 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 incident from the first surface 201 and the third surface 205 of the first prism 20 is expressed as Figure 2 ∠E in the figure, through geometric deduction, we know that ∠R1=2∠A+∠E, ∠C+∠E=90°. Then we can have 90°-∠B=2∠A+∠E. Since ∠C+∠E=90°, we can have ∠C+∠E-∠B=2∠A+∠E, and thus we can get ∠C=2∠A+∠B.

[0081] Of course, the structure of the optical system provided by the embodiment of the present disclosure is not limited to Figure 1 to Figure 9-2 Schematic structure.

[0082] For example, the structure of the optical system provided by the embodiment of the present disclosure can also be seen in Figure 11-1 or Figure 11-2 .like Figure 11-1 , Figure 11-2 As shown, 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 external environment can be a curved surface. By setting the surface of the second additional lens 80 close to the external environment to be a curved surface, such as a convex surface or a concave surface, it is beneficial to compensate for external light, so that the user can see the environment image without distortion.

[0083] For another example, the structure of the optical system provided by the embodiment of the present disclosure can be seen in Figure 11-3 or Figure 11-4 .like Figure 11-3 , Figure 11-4 As shown, the first surface 601 of the third prism 60 can be a curved surface, and the surface of the second additional lens 80 close to the external environment can also be a curved surface, for example, both can be a free combination of convex surfaces and concave surfaces. By setting the first surface 601 of the third prism 60 as a curved surface, it is beneficial to achieve a larger eye box under the same field of view, and it is also beneficial to improve aberration. By setting the surface of the second additional lens 80 close to the external environment as a curved surface, it is beneficial to compensate for external light, so that the user can see the environmental image without deformation.

[0084] In some optional embodiments of the present disclosure, the refractive indexes of the first prism 20 , the second prism 30 , and the third prism 60 may be consistent.

[0085] Here, the refractive indexes of the first prism 20 , the second prism 30 , and the third prism 60 being consistent can be understood as the refractive indexes of the three being the same or substantially the same.

[0086] Through research, it is found that setting the refractive indices of the first prism 20, the second prism 30, and the third prism 60 to be consistent can ensure that when the first surface 301 of the second prism 30 is tilted relative to the optical axis of the lens 40, the third surface 205 of the first prism 20 is tilted 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 image source 10 propagates through the same optical path along the target path mentioned above.

[0087] In some optional embodiments of the present disclosure, the refractive index of the third prism 60 may 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 may be limited to the range of [1.45, 1.85]. For example, the refractive index of the third prism 60 may be 1.45, 1.55, 1.65, 1.75, 1.85, etc., which are not listed here one by one.

[0088] Through research, it is found that limiting the refractive index of the third prism 60 to the range of [1.45, 1.85] is beneficial to effectively compensate for the optical path difference generated by light emitted from different light-emitting positions on the image source 10 after propagating in the first prism 20, thereby helping to ensure the imaging quality of the optical system.

[0089] In some optional embodiments of the present disclosure, the refractive index of the third prism 60 may be greater than or equal to 1.45 and less than 1.547, or the refractive index of the third prism 60 may be greater than 1.547 and less than or equal to 1.85. That is, the refractive index of the third prism 60 may be limited to the range of [1.45, 1.547)∪(1.547, 1.85]. For example, the refractive index of the third prism 60 may be 1.45, 1.52, 1.54, 1.546, 1.55, 1.65, 1.75, 1.85, etc., which are not listed here one by one.

[0090] In some optional embodiments of the present disclosure, the Abbe number of the third prism 60 may be greater than or equal to 40 and less than or equal to 80. That is, the Abbe number of the third prism 60 may be limited to the range of [40, 80]. For example, the Abbe number of the third prism 60 may be 40, 50, 60, 70, 80, etc., which are not listed here one by one.

[0091] Through research, it is found that limiting the Abbe number of the third prism 60 to the range of [40, 80] is beneficial to effectively compensate for the optical path difference generated by light emitted from different light-emitting positions on the image source 10 after propagating in the first prism 20, thereby helping to ensure the imaging quality of the optical system.

[0092] In some optional embodiments of the present disclosure, the refractive index of the lens 40 may be consistent with that of the second prism 30. Here, the refractive index of the lens 40 and the second prism 30 being consistent may be understood as the refractive indexes of the two being the same or substantially the same.

[0093] In some optional embodiments of the present disclosure, if the refractive index of the lens 40 is consistent with that of the second prism 30, the lens 40 and the second prism 30 may be an integral piece. In this way, the lens 40 and the second prism 30 may be integrally formed. Since the lens 40 and the second prism 30 are integrally formed, the edge thickness (e.g., Figure 2 , Figure 3-2 to Figure 9-2 The thickness of the left edge in the figure is increased. The larger edge thickness is conducive to reducing the processing difficulty and facilitating mass production.

[0094] In some optional embodiments of the present disclosure, for the light emitted by the image source 10 and propagating along the optical axis of the lens 40, the optical path length from the first surface 201 of the first prism 20 entering the first prism 20 to the first arrival at the second film layer 50 is represented as d, and the focal length of the lens 40 is represented 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 to 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, etc., which are not listed here one by one.

[0095] Through research, it is found that limiting f / d within the range of [0.4, 0.6] is conducive to achieving a larger eye relief (ER) and a larger eye box (EB) through a smaller optical system. Limiting f / d within the range of [0.4, 0.6] is also conducive to the correction of field curvature and pupil distortion.

[0096] It should be noted that Eye Relief (ER) is an important design indicator in the optical system. Eye Relief can refer to the distance from the preset eye position to the plane where the first optical element in the optical system is placed (which can be considered as the optical element closest to the preset eye position). 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.

[0097] In some optional embodiments of the present disclosure, the refractive index of the first prism 20 may 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 may be limited to the range of [1.45, 1.85]. For example, the refractive index of the first prism 20 may be 1.45, 1.5, 1.6, 1.7, 1.8, 1.85, etc., which are not listed here one by one.

[0098] Through research, it is found that limiting the refractive index of the first prism 20 within the range of [1.45, 1.85] is beneficial to ensuring the rationality of the parameters of the first prism 20, thereby ensuring the imaging quality of the optical system.

[0099] 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.

[0100] That is, the refractive index of the first prism 20 can be limited to 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, etc., which are not listed here one by one.

[0101] In some optional embodiments of the present disclosure, the Abbe number of the first prism 20 may be greater than or equal to 40 and less than or equal to 80. That is, the Abbe number of the first prism 20 may be limited to the range of [40, 80]. For example, the Abbe number of the first prism 20 may be 40, 50, 60, 70, 80, etc., which are not listed here one by one.

[0102] Through research, it is found that limiting the Abbe number of the first prism 20 within the range of [40, 80] is beneficial to ensuring the rationality of the parameters of the first prism 20, thereby ensuring the imaging quality of the optical system.

[0103] In some optional embodiments of the present disclosure, the refractive index of the second prism 30 may 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 may be limited to the range of [1.45, 1.85]. For example, the refractive index of the second prism 30 may be 1.45, 1.5, 1.6, 1.7, 1.8, 1.85, etc., which are not listed here one by one.

[0104] Through research, it is found that limiting the refractive index of the second prism 30 within the range of [1.45, 1.85] is beneficial to ensuring the rationality of the parameters of the second prism 30, thereby helping to ensure the imaging quality of the optical system.

[0105] In some optional embodiments of the present disclosure, the refractive index of the second prism 30 may be greater than or equal to 1.45 and less than 1.547, or the refractive index of the second prism 30 may be greater than 1.547 and less than or equal to 1.85.

[0106] That is, the refractive index of the second prism 30 can be limited to 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, etc., which are not listed here one by one.

[0107] In some optional embodiments of the present disclosure, the Abbe number of the second prism 30 may be greater than or equal to 40 and less than or equal to 80. That is, the Abbe number of the second prism 30 may be limited to the range of [40, 80]. For example, the Abbe number of the second prism 30 may be 40, 50, 60, 70, 80, etc., which are not listed here one by one.

[0108] Through research, it is found that limiting the Abbe number of the second prism 30 within the range of [40, 80] is beneficial to ensuring the rationality of the parameters of the second prism 30, thereby ensuring the imaging quality of the optical system.

[0109] In some optional embodiments of the present disclosure, the lens 40 and the second prism 30 may be separately provided, and the refractive index of the lens 40 may 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 provided, the refractive index of the lens 40 may be different from that of the second prism 30, and may be limited to the range of [1.4, 1.95]. For example, the refractive index of the lens 40 may be 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 1.95, etc., which are not listed here one by one.

[0110] Through research, it is found that, in the case where the lens 40 and the second prism 30 are separately arranged, limiting the refractive index of the lens 40 within the range of [1.4, 1.95] is beneficial to ensuring the rationality of the parameters of the lens 40, thereby ensuring the imaging quality of the optical system.

[0111] In some optional embodiments of the present disclosure, the Abbe number of the lens 40 may be greater than or equal to 40 and less than or equal to 100. That is, the Abbe number of the lens 40 may be limited to the range of [40, 100]. For example, the Abbe number of the lens 40 may be 40, 50, 60, 70, 80, 90, 100, etc., which are not listed here one by one.

[0112] Through research, it is found that limiting the Abbe number of the lens 40 within the range of [40, 100] is beneficial to ensuring the rationality of the parameters of the lens 40, thereby ensuring the imaging quality of the optical system.

[0113] In some optional embodiments of the present disclosure, the refractive index of the first additional lens 70 may 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 may be limited to the range of [1.45, 2.0]. For example, the refractive index of the first additional lens 70 may be 1.45, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, etc., which are not listed here one by one.

[0114] Through research, it is found that limiting the refractive index of the first additional lens 70 within the range of [1.45, 2.0] is beneficial to ensuring the rationality of the parameters of the first additional lens 70, thereby helping to ensure the imaging quality of the optical system.

[0115] In some optional embodiments of the present disclosure, the Abbe number of the first additional lens 70 may 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 may be limited to the range of [15, 100]. For example, the Abbe number of the first additional lens 70 may be 15, 20, 30, 40, 50, 60, 80, 90, 100, etc., which are not listed here one by one.

[0116] Through research, it is found that limiting the Abbe number of the first additional lens 70 within the range of [15, 100] is beneficial to ensuring the rationality of the parameters of the first additional lens 70, thereby ensuring the imaging quality of the optical system.

[0117] Some exemplary embodiments of the present disclosure also provide a head mounted display device. The head mounted display device may include Fig.12 The frame structure 90 and the optical system in any of the above embodiments are shown. The optical system can be installed on the frame structure 90.

[0118] In some optional embodiments of the present disclosure, the frame structure 90 may be a structure capable of supporting and accommodating an optical system. For example, the frame structure 90 may include but is not limited to a glasses frame, a headband, and the like.

[0119] In the embodiment of the present disclosure, the installation of the optical system can be reliably realized by setting the frame structure 90. Through the cooperation of various optical elements in the optical system, the human eye 100 can see the display screen provided by the image source 10 to meet the user's usage requirements. In some embodiments, the human eye 100 can also see the external environment.

[0120] It should be noted that the various optional embodiments and optional implementation methods disclosed above can be flexibly selected and combined as needed to achieve corresponding functions and effects, and the present disclosure does not list them one by one.

[0121] The basic principles of the present disclosure are described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, effects, etc. mentioned in the present disclosure are only examples and not limitations, and it cannot be considered that these advantages, strengths, effects, etc. are required by each embodiment of the present disclosure. In addition, the specific details disclosed above are only for the purpose of illustration and ease of understanding, and are not limitations. The above details do not limit the present disclosure to the necessity of adopting the above specific details to be implemented.

[0122] Each embodiment in this specification is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referenced to each other.

[0123] Those skilled in the art may make various changes and modifications to the present disclosure without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the present disclosure claims and their equivalents, the present disclosure is also intended to include these modifications and variations.

Claims

1. An optical system, comprising: Image source; A first prism, wherein the first prism has a first surface, a second surface and a third surface, and the first surface of the first prism is close to the image source; a second prism, wherein the second surface of the first prism is located on a side of the first prism away from the second prism, the third surface of the first prism is located on a side of the first prism close to the second prism, the second prism has a first surface, and the first surface of the second prism is close to the third surface of the first prism; a lens, wherein the lens is located on a side of the second prism away from the first prism, a first angle between a first surface of the second prism and an optical axis of the lens and a second angle between a third surface of the first prism and the optical axis of the lens are both acute angles, and the first angle is equal to the second angle; A first film layer, the first film layer is located on the second surface of the first prism and can reflect and transmit light; a second film layer, the second film layer is located on a side of the lens away from the second prism and can reflect light; Among them, the light emitted by the image source enters the first prism from the first surface of the first prism, is reflected by the first film layer after at least one total reflection in the first prism, is emitted from the third surface of the first prism and enters the second prism from the first surface of the second prism, is reflected by the second film layer after passing through the second prism and the lens, 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 through the first film layer.

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

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

4. The optical system according to claim 2, wherein: The angle between the third surface of the first prism and the plane perpendicular to the optical axis of the lens is the fifth angle, and 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.

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

9.

6. The optical system according to claim 2, wherein: The angle between the third surface of the first prism and the plane perpendicular to the optical axis of the lens is the fifth angle, and the difference between twice the sum of the third angle and the fifth angle and the complementary angle of the third angle is greater than negative 6 degrees.

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

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

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

10. The optical system according to claim 7, wherein: The fifth angle is greater than 8.1 degrees and less than 8.7 degrees.

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

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

13. The optical system according to claim 2, wherein: The third angle is greater than 20 degrees and less than 30 degrees.

14. The optical system of claim 1, further comprising: A compensating member is provided, and the compensating member is close to the second surface of the first prism. The light reflected by the second film layer passes through the first prism again and then emerges through the compensating member.

15. The optical system according to claim 14, wherein: The compensation member is a third prism, and the third prism has a first surface and a second surface. The first surface of the third prism is located on a side of the third prism away from the first prism, and the second surface of the third prism is located on a side of the third prism close to the first prism. After the light reflected by the second film layer passes through the first prism again, it is emitted after passing through the second surface of the third prism and the first surface of the third prism.

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

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

18. The optical system according to 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 partial area of ​​the second surface of the first prism close to the image source has a groove, and the groove is recessed from the partial area toward the inside of the first prism.

21. The optical system according to claim 1 or 20, wherein: A partial area of ​​the second surface of the first prism close to the image source is coated black.

22. The optical system according to claim 1 or 20, wherein: A partial area 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 index of the lens is consistent with that of the second prism.

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

25. The optical system of claim 1, wherein: For the light emitted by the image source and propagating along the optical axis of the lens, the optical path length from the time when the light enters the first prism from the first surface of the first prism to the time when the light first reaches the second film layer is represented by d, and the focal length of the lens is represented by f, then 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 provided, and 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, the first additional lens being located between the image source and the first surface of the first prism; Wherein, the light emitted by the image source enters the first prism after passing through the first additional lens.

34. An optical system according to claim 33, wherein: The refractive index of the first additional lens is greater than or equal to 1.45 and less than or equal to 2.

0.

35. The optical system of claim 33, wherein: The Abbe number of the first additional lens is 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-transparent and semi-reflective film, and the optical system further comprises: A second additional lens, wherein the second additional lens is located on a side of the second film layer away from the lens.

37. A head mounted display device, comprising: Frame structure; An optical system as described in any one of claims 1-36, wherein the optical system is mounted on the frame structure.

Images