An off-axis optical module and a head-mounted display device

Abstract

The present invention discloses an off-axis optical module, comprising: a first lens group for receiving image light from a micro display in an off-axis manner; the first lens group includes a plurality of lenses, and the plurality of lenses in the first lens group are coaxially arranged; the first lens group further includes a first wedge prism; the first wedge prism is arranged at a position close to the image source relative to the plurality of lenses in the first lens group; a second lens group for receiving the image light that has passed through the first lens group; the second lens group includes a plurality of lenses, and the plurality of lenses in the second lens group are coaxially arranged; the first lens group and the second lens group are arranged off-axis from each other, and the first lens group and the second lens group form a relay optical system; a curved mirror, the image light passing through the first lens group and the second lens group forms an intermediate image plane, and then is reflected by the curved mirror and enters the human eye. The present invention also provides a head-mounted display device including the above off-axis optical module.

Description

Technical Field

[0001] The present invention relates to an off-axis optical module, and also relates to a head-mounted display device including the above off-axis optical module. Background Art

[0002] The main feature of augmented reality technology is to superimpose virtual information on the real scene to achieve the enhancement of reality. Augmented reality technology can integrate virtual information (such as objects, pictures, videos, sounds, etc.) into the real environment, enrich the real world, and build a more comprehensive and better world. With the gradual entry of wearable devices into people's careers and lives in recent years, especially the development of the smart glasses industry, the distance between people and augmented reality technology has been further reduced.

[0003] Currently, augmented reality technology has made great progress in helmet image display devices. Among them, some products use off-axis reflection imaging technology. In off-axis reflection imaging technology, multiple lenses placed off-axis from each other are usually used to correct off-axis aberrations. For example, the off-axis large exit pupil distance smart AR glasses disclosed in the utility model patent with the publication number CN206594387U, and the head-mounted display device disclosed in the invention patent application with the publication number CN107290857A. However, the multiple lenses placed off-axis from each other used in the current off-axis reflection module increase the design and manufacturing difficulty of the structural part cooperating with the optical module on the one hand, and on the other hand, only part of the area of some lenses transmits light, resulting in waste of the lenses.

[0004] In addition, in the optical design scheme of the existing off-axis reflection imaging technology, the inclination angle of the curved mirror used is generally relatively small, generally within 30°, which causes problems of interference with other structures in the helmet display system. Summary of the Invention

[0005] The primary technical problem to be solved by the present invention is to provide an off-axis optical module.

[0006] Another technical problem to be solved by the present invention is to provide a head-mounted display device including the above off-axis optical module.

[0007] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0008] An off-axis optical module, comprising:

[0009] The first lens group is configured to receive image light from a micro display in an off-axis manner; the first lens group includes a plurality of lenses, and the plurality of lenses in the first lens group are coaxially arranged; the first lens group further includes a first wedge prism; the first wedge prism is disposed closer to the image source relative to the plurality of lenses in the first lens group;

[0010] The second lens group is configured to receive the image light that has passed through the first lens group; the second lens group includes a plurality of lenses, and the plurality of lenses in the second lens group are coaxially arranged;

[0011] The first lens group and the second lens group are arranged off-axis with respect to each other, and the first lens group and the second lens group form a relay optical system;

[0012] The curved mirror forms an intermediate image plane for the image light that has passed through the first lens group and the second lens group, and then is reflected by the curved mirror and enters the human eye.

[0013] Preferably, the angle between the image source and the upper surface of the first wedge prism is controlled within 15 degrees;

[0014] The included angle between the two planes of the first wedge prism is within 10 degrees;

[0015] The angle between the Z-axis of the first lens group and the Z-axis of the second lens group is about 5 degrees.

[0016] Preferably, the plurality of lenses in the first lens group include at least one positive-negative doublet lens and a convex lens with aspherical surfaces on both sides.

[0017] Preferably, the second lens group further includes a second wedge prism; the second wedge prism is disposed closer to the curved mirror relative to the plurality of lenses in the second lens group.

[0018] Preferably, the included angle between the two planes of the second wedge prism is within 10 degrees.

[0019] Preferably, the plurality of lenses in the second lens group include at least one convex lens with aspherical surfaces on both sides and a meniscus lens that curves towards the curved mirror side.

[0020] Preferably, the off-axis optical module further includes a mirror disposed between the second lens group and the curved mirror for reflecting the image light that has passed through the second lens group to the surface of the curved mirror, and the mirror is a plane mirror or a curved mirror.

[0021] Preferably, the surface shape of the curved mirror is a free-form surface; the inclination angle of the curved mirror is greater than 30 degrees and less than 40 degrees.

[0022] A head-mounted display device includes the above-mentioned off-axis optical module.

[0023] Preferably, the first lens group and the second lens group are disposed above the curved mirror near the top of the head.

[0024] The off-axis optical module provided by the present invention realizes a larger magnification by adding at least one wedge prism and two off-axis lens groups without increasing the size of the microdisplay screen. The exit pupil distance of the above-mentioned head-mounted display device is 75 mm, the exit pupil diameter can reach 16 mm, and the field of view angle can reach more than 65°. The curved mirror has a larger tilt angle, and the tilt angle can be more than 30° and within 40°, so as to realize a large field of view head-mounted display for use with a helmet. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic structural diagram of the head-mounted display device provided by the present invention;

[0026] Figure 2 is a schematic structural diagram of the off-axis optical module provided by the first embodiment;

[0027] Figure 3 is Figure 2 a schematic diagram of the numbers of different optical surfaces in each lens group in the off-axis optical module shown;

[0028] Figure 4 is a schematic structural diagram of the off-axis optical module provided by the second embodiment;

[0029] Figure 5 is Figure 4 a schematic diagram of the numbers of different optical surfaces in each lens group in the off-axis optical module shown. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] The technical solutions of the present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0031] As Figure 1 shown, the head-mounted display device provided by the present invention includes a housing and an off-axis optical module disposed inside the housing. Among them, the off-axis optical module is disposed in front of the forehead, and the microdisplay in the off-axis optical module is disposed above the curved mirror and near the top of the head. Hereinafter, a three-dimensional rectangular coordinate system is established with the human eye 50 as the coordinate origin, the visual axis direction as the Z direction, the direction perpendicular to the visual axis upward as the Y direction, and the direction perpendicular to the YZ plane and inward into the paper as the X direction.

[0032] The off-axis optical module disposed in the head-mounted display device includes a first lens group 20, a second lens group 30, and a curved mirror 40 arranged in sequence from the image source 100 to the human eye 50. The curved mirror 40 can be a beam splitter or a total reflection mirror.

[0033] Among them, the image source 100 can be a micro display device such as an LCD, an OLED, or an Lcos. Preferably, when there is a beam splitter in the optical system, the energy utilization rate of the system generally does not exceed 60%. Therefore, an Lcos or OLED display device that can greatly adjust the display brightness is selected as the image source.

[0034] The first lens group 20 and the second lens group 30 form a relay optical system. By adjusting the focal length of the first lens group 20 and the second lens group 30, the magnification of the field of view is achieved, and the off-axis aberration is corrected.

[0035] The image source 100, the first lens group 20, and the second lens group 30 are arranged off-axis with respect to each other. The lenses within the first lens group 20 are coaxially arranged, and the lenses within the second lens group 30 are coaxially arranged. Thus, while correcting the off-axis aberration, the assembly difficulty of the lenses in the off-axis optical module is reduced.

[0036] The first lens group 20 and / or the second lens group 30 further includes a wedge prism for compensating the optical path difference of light. Alternatively, a reflector is introduced between the second lens group 30 and the curved mirror 40, and the combination of the wedge prism and the reflector is used to compensate the optical path difference of light.

[0037] The concave surface of the curved mirror 40 faces the human eye 50, and a beam splitter film with a predetermined transmittance ratio is attached to one side surface of the curved mirror 40. The specific attachment process of the beam splitter film is not limited. For example, it can be evaporation coating, ion sputtering, or pasting, etc. The image light emitted from the image source 100 passes through the first lens group 20 and the second lens group 30 to form an intermediate image plane, and then irradiates onto the curved mirror 40 and is reflected by the curved mirror 40 into the human eye 50. It can be understood that the light on the environment side can also be projected into the human eye 50 through the curved mirror 40 to achieve augmented reality display.

[0038] A total reflection film can also be attached to the surface of the curved mirror 40. When a total reflection film is attached to the surface of the curved mirror 40, a virtual reality display effect can be achieved.

[0039] Taking augmented reality display as an example below, the off-axis optical module disposed in the housing will be described in combination with specific embodiments.

[0040] First Embodiment

[0041] In the first embodiment, the structure of the off-axis optical module is as Figure 2 shown, including an image source 1, a first wedge prism 2, a first lens 3, a positive-negative doublet lens 4, a second lens 5, a third lens 6, a fourth lens 7, a fifth lens 8, a second wedge prism 9, and a curved mirror 10.

[0042] Among them, the first wedge prism 2, the first lens 3, the positive-negative doublet lens 4, and the second lens 5 form the first lens group 20. The mechanical axes (defined as the first axis A) of the first wedge prism 2, the first lens 3, the positive-negative doublet lens 4, and the second lens 5 coincide and are coaxially arranged.

[0043] The first lens group 20 can be a set of coaxial spherical, cylindrical, aspherical, and free-form lenses. Preferably, in order to effectively correct the system chromatic aberration, the first lens group 20 includes a positive-negative doublet lens. Preferably, in order to correct the high-order aberration, a convex lens with aspherical surfaces on both sides is selected. The focal length of the first lens group 20 is about 19.5 mm.

[0044] Relative to the other lenses in the first lens group 20, the first wedge prism 2 is arranged at a position close to the image source 1. The function of the first wedge prism 2 is to compensate for the optical path difference of the off-axis system. Preferably, for ease of alignment, the surface of the first wedge prism 2 in contact with other lenses is coaxially placed. Preferably, for ease of processing, the surface of the first wedge prism 2 is a plane. The angle between the two planes of the first wedge prism is less than 10 degrees.

[0045] The third lens 6, the fourth lens 7, the fifth lens 8, and the second wedge prism 9 form the second lens group 30. The mechanical axes (defined as the second axis B) of the third lens 6, the fourth lens 7, the fifth lens 8, and the second wedge prism 9 coincide and are coaxially arranged.

[0046] The second lens group 30 can be a set of coaxial spherical, cylindrical, aspherical, and free-form lenses. Preferably, in order to correct the high-order aberration, a convex lens with aspherical surfaces on both sides is selected; preferably, in order to minimize the spherical aberration, a meniscus lens is selected and bent towards the curved mirror 10, that is, the bilateral surfaces of the meniscus lens bulge towards the curved mirror 10 side. The focal length of the second lens group 30 is about 49.5 mm.

[0047] Among them, relative to the other lenses in the second lens group 30, the second wedge prism 9 is arranged at a position close to the curved mirror 10. The function of the second wedge prism 9 is to compensate for the optical path difference of the off-axis system. Preferably, for ease of alignment, the surface of the second wedge prism 9 in contact with other lenses is coaxially placed; preferably, for ease of processing, the surface of the second wedge prism 9 is a plane. The angle between the two plane surfaces of the second wedge prism 9 is less than 10 degrees.

[0048] The curved mirror 10 can be a spherical, cylindrical, aspherical, or free-form reflector. Preferably, the curved mirror 10 is a free-form surface, which can effectively correct the system aberration.

[0049] The image signal emitted by the image source 1 first passes through the first wedge prism 2, reaches the first lens 3, passes through the positive-negative doublet lens 4, then passes through the second lens 5, then passes through the third lens 6, the fourth lens 7, the fifth lens 8, and the second wedge prism 9. The curved mirror 10 reflects the image signal, and finally the image signal reaches the human eye.

[0050] The positional relationship of each part of this embodiment is as Figure 2 shown. Among them, the included angle θ1 between the image source 1 and the upper surface of the first prism 2 is controlled within 15°. The included angle θ2 (i.e., the included angle between the first axis A and the second axis B) of the z-axis between the two lens groups is about 5°. The included angle θ3 between the connection line of the local coordinate origin of the curved mirror 10 and the local coordinate origin of the lower surface of the second wedge prism 9 and the z-axis of the lower surface of the second wedge prism 9 is about 10°. Define the included angle between the normal line of the curved mirror 10 and the visual axis as the inclination angle θ4 of the curved mirror 10, and the inclination angle θ4 of the curved mirror 10 is about 36°. The included angle a1 between the two planes of the first wedge prism 2 is within 10°, and the included angle a2 between the two planes of the second wedge prism 9 is within 10°. The height d1 of the entire optical part is about 188 mm. The inclination angle of the curved mirror in this solution is 36°, the exit pupil distance is 75 mm, the exit pupil diameter is 16 mm, and the field of view angle is 67°.

[0051] In the above embodiment, the parameters of the lenses and prisms used are as follows. The numbers of each optical surface in the lenses and prisms can be referred to Figure 3 . Among them, the parameters of each optical surface are shown in Table 1. In the following table, only the design parameters of the optical surfaces of each optical element are exemplified. It can be understood that in addition to each optical surface, the optical element may also include other surfaces, and the other surfaces are not used as optical surfaces.

[0052] Referring to the data given in the following table, the surface type of the curved mirror 10 given in this embodiment is a free-form surface, and the surface types of the optical surfaces of the remaining lenses are all spherical or aspherical.

[0053] Table 1 Parameters of each optical surface in the first embodiment

[0054] Serial number Surface type Radius of curvature Thickness Refractive index Abbe number Eccentricity 50 Spherical surface Infinity 75 10 XY polynomial -93.24 -103.13 Eccentricity and curvature 192 Spherical surface Infinity -3.78 1.517 6.42 Basic eccentricity 191 Spherical surface Infinity -0.87 Basic eccentricity 182 Spherical surface -27.46 -4.6 1.911 35.2 181 Spherical surface -52.8 -2.49 172 Spherical surface -130.60 -1.5 1.739 23.0 171 Spherical surface -33.61 -1.16 162 Aspherical surface -29.69 -5.35 1.569 67.9 161 Aspherical surface 364.85 -4.88 152 Aspherical surface -29.42 -5.5 1.594 67.3 Basic eccentricity 151 Aspherical surface 225.51 -2.80 143 Spherical surface -166.17 -2.0 1.915 18.4 142 Spherical surface -27.37 -6.15 1.871 37.7 141 Spherical surface Infinity -2.0 132 Spherical surface -47.21 -6.0 1.848 39.4 131 Spherical surface 125.81 -0.59 122 Spherical surface Infinity -6.04 1.654 29.3 121 Spherical surface Infinity -3.5 Basic eccentricity 1 Spherical surface Infinity Basic eccentricity

[0055] Second embodiment

[0056] As Figure 4 shown, the off-axis optical module includes an image source 1, a first wedge prism 2, a first lens 3, a positive-negative doublet lens 4, a second lens 5, a third lens 6, a fourth lens 7, a fifth lens 8, a mirror 11, and a curved mirror 10.

[0057] Among them, the first wedge prism 2, the first lens 3, the positive-negative doublet lens 4, and the second lens 5 form the first lens group 20. The mechanical axes (defined as the first axis A) of the first wedge prism 2, the first lens 3, the positive-negative doublet lens 4, and the second lens 5 coincide and are coaxially arranged.

[0058] The first lens group 20 can be a set of coaxial spherical, cylindrical, aspherical, and free-form surface lenses. Preferably, in order to effectively correct the chromatic aberration of the system, the first lens group 20 includes a positive-negative doublet lens. Preferably, in order to correct the higher-order aberration, a convex lens with aspherical surfaces on both sides is selected.

[0059] The first wedge prism 2 is arranged at a position close to the image source 1. The function of the first wedge prism 2 is to compensate for the optical path difference of the off-axis system. Preferably, for easy alignment, the surface of the first wedge prism 2 in contact with other lenses is coaxially placed. Preferably, for easy processing, the surface of the first wedge prism 2 is a plane.

[0060] The third lens 6, the fourth lens 7, and the fifth lens 8 form the second lens group 30. The mechanical axes (defined as the second axis B) of the third lens 6, the fourth lens 7, and the fifth lens 8 coincide and are coaxially arranged.

[0061] The second lens group 30 can be a set of coaxial spherical, cylindrical, aspherical, and free-form surface lenses. Preferably, in order to correct the higher-order aberration, a convex lens with aspherical surfaces on both sides is selected; preferably, in order to minimize the spherical aberration, a meniscus lens is selected as one of the lenses.

[0062] In this embodiment, a mirror 11 is arranged between the second lens group 30 and the curved mirror 10. By arranging the mirror 11, the image source 1, the first lens group 20, and the second lens group 30 can be pushed to a position farther away from the head, so as to adapt to the structural design of the head-mounted display device.

[0063] The mirror 11 can be a plane mirror, a spherical mirror, an aspherical mirror, or a free-form surface mirror. Preferably, in the illustrated embodiment, a plane mirror is used, which can change the optical path, avoid interference between the optical system and other structures of the helmet, and at the same time can change the optical path difference of different field-of-view optical paths, so as to achieve the purpose of reducing the use of one prism.

[0064] The curved mirror 10 can be a spherical, cylindrical, aspherical, or free-form surface mirror. Preferably, the curved mirror 10 is a free-form surface, which can effectively correct the system aberration.

[0065] The image signal emitted by the image source 1 first passes through the first wedge prism 2, reaches the first lens 3, passes through the positive-negative doublet lens 4, then passes through the second lens 5, then passes through the third lens 6, the fourth lens 7, and the fifth lens 8, and reaches the mirror 11. The mirror 11 reflects the image signal to the curved mirror 10, and the curved mirror 10 reflects the image signal. Finally, the image signal reaches the human eye.

[0066] Among them, the included angle θ1 between the optical axis of the image source 1 and the upper surface of the first wedge prism 2 is within 10°. The included angle θ2 between the mechanical axes of the two lens groups is about 2°. The included angle θ3 between the connection line of the local coordinate origin of the fifth lens 8 and the local coordinate origin of the plane mirror 11 and the z-axis of the plane mirror 11 is about 10°. The included angle θ5 between the connection line of the local coordinate origin of the plane mirror 11 and the local coordinate origin of the curved mirror 10 and the z-axis of the plane mirror 11 is about 56°. The inclination angle θ4 of the curved mirror 10 is about 36°. The included angle a1 between the two planes of the first wedge prism 2 is within 10°. The height d1 of the entire optical part is about 188 mm.

[0067] In the above embodiment, the parameters of the lenses and prisms used are as follows. The numbers of the optical surfaces in the lenses and prisms can be referred to Figure 5 . Among them, the parameters of each optical surface are shown in Table 2. In the following table, only the design parameters of the optical surfaces of each optical element are exemplified. It can be understood that in addition to each optical surface, the optical element may also include other surfaces, and the other surfaces are not used as optical surfaces.

[0068] Referring to the data given in the following table, the surface type of the curved mirror 10 given in this embodiment is a free-form surface, and the surface types of the optical surfaces of the remaining lenses are all spherical or aspherical.

[0069] Table 2 Parameters of each optical surface in the second embodiment

[0070] Serial number Surface type Radius of curvature Thickness Refractive index Abbe number Eccentricity 50 Spherical surface Infinity 75 10 XY polynomial -139.21 -84.98 Eccentricity and curvature 11 Spherical surface Infinity 30.58 Eccentricity and curvature 282 Spherical surface 27.85 5 1.919 28.5 Basic eccentricity 281 Spherical surface 51.45 5.05 272 Spherical surface 575.13 1.5 1.896 18.8 271 Spherical surface 36.56 0.27 262 Aspherical surface 29.16 5.5 1.708 56.0 261 Aspherical surface 486.53 3.51 252 Aspherical surface 31.49 5.5 1.671 47.2 Basic eccentricity 251 Aspherical surface -128.63 3.57 243 Spherical surface 86.16 1.5 1.849 19.7 242 Spherical surface 19.91 8 1.911 35.3 241 Spherical surface -2794.9 1.61 232 Spherical surface 43.54 6 1.729 54.7 231 Spherical surface -92.02 0.93 222 Spherical surface Infinity 4 1.517 64.2 221 Spherical surface Infinity 3.09 Basic eccentricity 1 Spherical surface Infinity 0.19 Basic eccentricity

[0071] In summary, the off-axis optical module and the head-mounted display device provided by the present invention achieve a larger magnification by adding at least one wedge prism and two groups of off-axis lenses without increasing the size of the microdisplay screen. The exit pupil distance of the above head-mounted display device is 75 mm, the exit pupil diameter can reach 16 mm, and the field of view angle can reach more than 65°. Moreover, in the above optical module, the curved mirror has a larger tilt angle, which can be above 30° and within 40°, to achieve a large field of view head-mounted display for use with a helmet. In addition, in the above off-axis optical module, a plane mirror or a curved mirror can be added to change the overall structure of the optical system and play a role in compensating for part of the optical path difference and correcting aberration. By adopting this solution, the optical path can make full use of the lenses, resulting in better imaging quality and a larger field of view angle.

[0072] The above has described in detail an off-axis optical module and a head-mounted display device provided by the present invention. For those of ordinary skill in the art, any obvious changes made to it without departing from the essence of the present invention will constitute an infringement of the patent right of the present invention and will bear corresponding legal responsibilities.

Claims

1. An off-axis optical module, characterized in that, Comprising a first lens group, a second lens group, and a curved mirror sequentially arranged from an image source to the human eye: The first lens group is used to receive image light from the image source in an off-axis manner. The first lens group is composed of a first wedge prism, a first lens, a positive-negative doublet lens, and a second lens coaxially arranged from the image source to the human eye in sequence; The second lens group is used to receive the image light that has passed through the first lens group; The second lens group is composed of a third lens, a fourth lens, a fifth lens, and a second wedge prism coaxially arranged from the image source to the human eye in sequence; The first lens group and the second lens group are arranged off-axis with respect to each other. The first lens group and the second lens group form a set of relay optical systems; The image light that has passed through the first lens group and the second lens group forms an intermediate image plane, and then is reflected by the curved mirror and enters the human eye; The number of lenses with refractive power in the off-axis optical module is 7. Among them, the first lens is a positive lens with a focal length of 41.13 mm; in the positive-negative doublet lens, the lens close to the first lens is a positive lens with a focal length of 31.42 mm, and the lens close to the second lens is a negative lens with a focal length of -36.05 mm; the second lens is a positive lens with a focal length of 44.16 mm; the third lens is a positive lens with a focal length of 48.49 mm; the fourth lens is a negative lens with a focal length of -61.64 mm, and the fifth lens is a positive lens with a focal length of 57.80 mm; The surface shape of the curved mirror is a free-form surface, and the inclination angle of the curved mirror is 36°; The exit pupil distance of the off-axis optical module is 75 mm, the exit pupil diameter is 16 mm, and the field of view angle is 67°.

2. The off-axis optical module according to claim 1, wherein: The included angle between the image source and the upper surface of the first wedge prism is controlled within 15 degrees; The included angle between the two planes of the first wedge prism is within 10 degrees; The included angle between the mechanical axes of the first lens group and the second lens group is 5 degrees.

3. The off-axis optical module according to claim 1, wherein: The included angle between the two planes of the second wedge prism is within 10 degrees.

4. An off-axis optical module, characterized in that, Comprising a first lens group, a second lens group, a reflector, and a curved mirror sequentially arranged from an image source to the human eye: The first lens group is used to receive image light from the image source in an off-axis manner. The first lens group is composed of a first wedge prism, a first lens, a positive-negative doublet lens, and a second lens coaxially arranged from the image source to the human eye in sequence; The second lens group is used to receive the image light that has passed through the first lens group. The second lens group is composed of a third lens, a fourth lens, and a fifth lens coaxially arranged from the image source to the human eye in sequence; The first lens group and the second lens group are arranged off-axis with respect to each other. The first lens group and the second lens group form a set of relay optical systems; The reflector is used to reflect the image light that has passed through the second lens group to the surface of the curved mirror; The curved mirror is used to reflect the image light, and finally the image light enters the human eye; The number of lenses with refractive power in the off-axis optical module is 7. Among them, the first lens is a positive lens with a focal length of 41.30 mm; in the positive-negative cemented lens, the lens closer to the first lens is a positive lens with a focal length of 21.72 mm, and the lens closer to the second lens is a negative lens with a focal length of -30.79 mm; the second lens is a positive lens with a focal length of 38.20 mm; the third lens is a positive lens with a focal length of 43.58 mm; the fourth lens is a negative lens with a focal length of -43.65 mm, and the fifth lens is a positive lens with a focal length of 59.97 mm; The surface shape of the curved mirror is a free-form surface, and the inclination angle of the curved mirror is 36°; The exit pupil distance of the off-axis optical module is 75 mm, and the exit pupil diameter is 16 mm.

5. The off-axis optical module according to claim 4, wherein: The angle between the image source and the upper surface of the first wedge prism is within 10 degrees; The angle between the two planes of the first wedge prism is within 10 degrees; The angle between the mechanical axes of the first lens group and the second lens group is 2 degrees.

6. The off-axis optical module according to claim 4, wherein: The reflector is a plane reflector.

7. A head-mounted display device, characterized in that: It includes the off-axis optical module according to any one of claims 1 to 6.

8. The head-mounted display device according to claim 7, characterized in that: The first lens group and the second lens group are arranged above the curved mirror, close to the position of the head.

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