Optical modules and head-mounted display devices

Abstract

The present application provides an optical module and a head-mounted display device; wherein the optical module includes a free-form surface prism, a first lens, and a second lens; the free-form surface prism includes a first surface, a second surface, and a third surface, the first surface and the third surface being free-form surfaces, the second surface including a first region and a second region, wherein the second region is provided with a total reflection film; the first lens is located on one side of the first surface, a first light ray is transmitted through the first lens, enters the free-form surface prism, and is reflected by the second region before being totally reflected on the first surface, the first light ray being refracted ≥3 times in the free-form surface prism; the second lens is located on one side of the third surface, a second light ray is transmitted through the second lens, enters the free-form surface prism, and exits through the first region. In the optical module of the present application, light can be reflected at least three times in the free-form surface prism, thereby extending the light propagation path, which can reduce the thickness of the optical module while ensuring imaging quality.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of optical imaging technology. More specifically, the embodiments of the present application relate to an optical module and a head-mounted display device. Background Art

[0002] Augmented Reality (AR) technology refers to the use of certain technical means to provide users with additional information in the real world (the so-called "enhancement"). This technology organically combines images in the virtual world and scenes in the real world, and deeply integrates the calculated information with the real world to provide users with richer information and immersive experience.

[0003] Wearable AR devices, such as AR glasses, are the most widely used hardware implementations of augmented reality technology. As consumer demand for these products grows, demand for AR glasses that are compact and capable of high-definition imaging demands a thin, lightweight, and high-resolution front-end optical module. However, existing optical modules struggle to achieve both thinness and high-definition imaging. Summary of the Invention

[0004] The purpose of this application is to provide a new technical solution for an optical module and a head-mounted display device.

[0005] In a first aspect, the present application provides an optical module, comprising:

[0006] A free-form surface prism, the free-form surface prism comprising a first surface, a second surface, and a third surface, wherein the first surface and the third surface are both free-form surfaces, the second surface comprises a first area and a second area, wherein the second area is provided with a total reflection film;

[0007] a first lens, the first lens being located on one side of the first surface, wherein a first light ray is transmitted through the first lens and then enters the free-form surface prism, and then is reflected by the second area and then is totally reflected on the first surface, and the first light ray is refracted ≥3 times in the free-form surface prism; and

[0008] The second lens is located on one side of the third surface, and the second light is transmitted through the second lens and then enters the free-form surface prism and is emitted through the first area.

[0009] Optionally, the optical module further includes a polarized reflective element, and the polarized reflective element is located between the free-form surface prism and the second lens.

[0010] Optionally, the surface of the second lens close to the free-form surface prism and the third surface are both free-form surfaces, and the two are glued together.

[0011] Optionally, a polarizing reflective element is provided on a surface of the second lens close to the free-form surface prism.

[0012] Optionally, the second lens is used to transmit the second light, and the second light is light in the real world;

[0013] An anti-reflection film is provided on a surface of the second lens away from the free-form surface prism.

[0014] Optionally, the optical module further includes a display screen, and the display screen is located on a side of the first lens away from the first surface;

[0015] The display screen is used to emit the first light, which is transmitted through the first lens and the first surface, reflected by the second area, totally reflected by the first surface, totally reflected by the first area, reflected by the third surface, and then transmitted through the first area before entering the human eye.

[0016] Optionally, the display screen is arranged along a first direction, and an angle between the display screen and the first direction is -30° to +30°;

[0017] The first direction is perpendicular to the thickness direction of the optical module.

[0018] Optionally, the first region is provided with an anti-reflection film;

[0019] The length ratio of the second region to the first region is 0.9-3.

[0020] Optionally, the first lens includes two surfaces, and both surfaces of the first lens are free-form surfaces.

[0021] Optionally, an anti-reflection film is applied to at least one of the two surfaces of the first lens.

[0022] Optionally, the free-form surface prism has a thickness of T3, and T3 satisfies: 0.5 mm < T3 < 15 mm.

[0023] Optionally, the thickness of the first lens is T1, and T1 satisfies: 1mm<T3<10mm;

[0024] The thickness of the second lens is T2, and T2 satisfies: 0.5 mm < T2 < 15 mm.

[0025] Optionally, at least one of the free-form surface prism, the first lens, and the second lens is made of plastic material.

[0026] In a second aspect, the present application provides a head-mounted display device, comprising:

[0027] a housing; and

[0028] An optical module as described above.

[0029] According to an embodiment of the present application, an optical module is provided. This optical module can be used, for example, in AR devices. A free-form prism with three optical surfaces is introduced into the optical path. By causing light in the virtual optical path to be reflected multiple times in the free-form prism, the light propagation path can be extended. This can reduce the thickness of the optical module while ensuring the imaging quality of the optical module. This results in the optical module being compact and having high resolution.

[0030] Other features and advantages of the present specification will become apparent from the following detailed description of exemplary embodiments of the present specification with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the specification and, together with the description, serve to explain the principles of the specification.

[0032] Figure 1 A schematic structural diagram of an optical module provided in an embodiment of the present application;

[0033] Figure 2 for Figure 1 MTF curve diagram of the optical module shown;

[0034] Figure 3 for Figure 1 The spot diagram of the optical module is shown;

[0035] Figure 4 for Figure 1 Field curvature distortion diagram of the optical module shown;

[0036] Figure 5 for Figure 1 The vertical axis chromatic aberration diagram of the optical module is shown.

[0037] Description of reference numerals:

[0038] 10. First lens; 20. Second lens; 30. Free-form prism; 31. First surface; 32. Second surface; 321. First region; 322. Second region; 33. Third surface; 40. Display screen; 41. Screen protector; 01. Human eye; 02. First light ray; 03. Second light ray. DETAILED DESCRIPTION

[0039] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that unless otherwise specifically stated, the relative arrangements of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present application.

[0040] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present disclosure, its application, or uses.

[0041] Techniques and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the techniques and equipment should be considered part of the specification.

[0042] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0043] It should be noted that like reference numerals and letters refer to like items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0044] According to one aspect of an embodiment of the present application, an optical module is provided, which has a small size and high resolution. The optical module can be suitable for use in a head-mounted display (HMD), such as an augmented reality (AR) headset. The AR headset may include AR glasses or an AR helmet, etc., which are not specifically limited in the present embodiment.

[0045] The present application embodiment provides an optical module, such as Figure 1 As shown, the optical module includes: a free-form surface prism 30, a first lens 10 and a second lens 20;

[0046] The free-form surface prism 30 includes a first surface 31, a second surface 32, and a third surface 33. The first surface 31 and the third surface 33 are both free-form surfaces. The second surface 32 includes a first area 321 and a second area 322. The second area 322 is provided with a total reflection film.

[0047] The first lens 10 is located on one side of the first surface 31. The first light 02 is transmitted through the first lens 10 and enters the free-form surface prism 30. After being reflected by the second area 322, the first light 02 is totally reflected on the first surface 31. The first light 02 is refracted ≥3 times in the free-form surface prism 30.

[0048] The second lens 20 is located on one side of the third surface 33 . The second light 03 is transmitted through the second lens 20 and then enters the free-form surface prism 30 and exits through the first area 321 .

[0049] In the optical module of the embodiment of the present application, the first lens 10 can be used to transmit the virtual imaging light emitted by the display screen 40, that is, Figure 1 The second lens 20 can be used to transmit, for example, light from the real world, i.e. Figure 1 The entire optical module can receive both virtual and real light, and after processing, it can be imaged in the human eye 01. The optical module of the embodiment of the present application can be applied to AR devices, and users can view virtual reality images.

[0050] The optical module of the embodiment of the present application introduces a free-form surface prism 30 in the optical path. The introduction of the free-form surface prism 30 can be used to adjust the incident virtual imaging light (i.e. Figure 1 The first light 02) shown in the figure is folded multiple times, wherein the number of folds can reach ≥3, which can extend the propagation path of the imaging light and ensure better imaging quality while reducing the thickness of the optical module.

[0051] For example, the optical module of the embodiment of the present application has a thickness (thickness along the eye axis or Figure 1 The horizontal direction (shown in the figure) can be less than 15 mm. The entire optical module is compact, enabling a lightweight and thin design. Furthermore, because the virtual imaging light undergoes multiple deflections within the free-form surface prism 30, this improves imaging quality, facilitating high-definition imaging of the optical module.

[0052] In the embodiments of the present application, Figure 1 As shown, the second surface 32 of the free-form surface prism 30, that is, the surface close to the human eye 01, is divided into two different areas, and a total reflection film is provided on the second area 322 of the free-form surface prism 30. This allows the first light ray 02 incident on the free-form surface prism 30 to reach the condition of total reflection on the first surface 31 after being reflected by the second area 322 of the second surface 32, so that it can be totally reflected on the first surface 31 and then totally reflected in the first area 321 on the second surface 32. This can increase the number of deflections of the first light ray 02 in the free-form surface prism 30. Specifically, the number of deflections can reach three or more.

[0053] According to the optical module provided in the embodiment of the present application, Figure 1 As shown, the propagation process of light is as follows:

[0054] First light 02 (i.e., virtual imaging light) emitted from display screen 40 passes through first lens 10, passes through first surface 31 of free-form prism 30, reflects from second region 322 of second surface 32, is totally reflected from first surface 31, totally reflected from first region 321 of second surface 32, reflects from third surface 33, passes through first region 321, and finally enters eye 01. Second light 03 (i.e., real-world light) also enters eye 01 after passing through second lens 20 and free-form prism 30. This allows the virtual world image and the real-world scene to be organically integrated, forming a high-definition image for eye 01.

[0055] Please continue as Figure 1 As shown, in the optical module of the embodiment of the present application, the first lens 10, the second lens 20 and the free-form surface prism 30 are not arranged in a set order on the same optical axis, but the first lens 10 and the second lens 20 are respectively arranged at two optical surfaces close to the free-form surface prism 30. This design can structurally reduce the thickness dimension of the optical module.

[0056] According to an embodiment of the present application, an optical module is provided. This optical module can be used, for example, in AR devices. A free-form prism 30 having three optical surfaces is introduced into the optical path. By causing light in a virtual optical path to be reflected multiple times in the free-form prism 30, the light propagation path can be extended. This can reduce the thickness of the optical module while ensuring the imaging quality of the optical module. This results in the optical module being compact and having high resolution.

[0057] In some examples of this application, such as Figure 1 As shown, the optical module further includes a polarized reflective element, and the polarized reflective element is located between the free-form surface prism 30 and the second lens 20 .

[0058] In the embodiment of the present application, a polarizing reflective film is disposed between the free-form surface prism 30 and the second lens 20. The introduction of the polarizing reflective film improves the optical efficiency of the virtual light path, thereby improving imaging quality. This improvement in optical efficiency is achieved by ensuring that the first light ray 02 of the virtual light path participates as much (or all) as possible in reflection on the third surface 33 of the free-form surface prism 30 before being transmitted through the first region 321 and entering the human eye 01. This prevents the first light ray 02 from significantly transmitting through the third surface 33 after incident on the first light ray 02, thereby affecting the imaging effect.

[0059] It should be noted that the polarizing reflective film can be attached to the third surface 33 of the free-form prism 30. The polarizing reflective film can also be used as an independent optical device, supported by a transparent flat element, for example, at a suitable position between the third surface 33 of the free-form prism 30 and the second lens 20, which is not limited in the embodiments of the present application.

[0060] In some examples of this application, such as Figure 1 As shown, the surface of the second lens 20 close to the free-form surface prism 30 has the same surface shape as the third surface 33 , both of which are free-form surfaces, and the two are glued together.

[0061] In the optical module of the present embodiment, the free-form prism 30 includes three optical surfaces: the aforementioned first surface 31, second surface 32, and third surface 33. The second surface 32 is independently located on the side closest to the human eye 01. The first surface 31 is adjacent to the first lens 10 and, in conjunction with the display screen 40, forms a virtual light path. The third surface 33 is adjacent to the second lens 20, which transmits real-world light (the second light ray 03).

[0062] The surface of the second lens 20 near the third surface 33 is designed to have the same surface shape as the third surface 33. Both are free-form surfaces, which helps improve the clarity of the optical module imaging. In addition, the same surface shape of the two surfaces also facilitates gluing and connecting the two surfaces.

[0063] The surface of the second lens 20 adjacent to the free-form surface prism 30 can be bonded to the third surface 33 of the free-form surface prism 30 using, for example, optical adhesive. This allows the second lens 20 and the free-form surface prism 30 to form a bonded lens assembly. This design can reduce chromatic aberration of the optical module and also makes assembly of the optical module easier.

[0064] Optionally, if Figure 1 As shown, a polarizing reflective film is provided on the surface of the second lens 20 close to the free-form surface prism 30 .

[0065] The introduction of polarized reflective film can improve the light efficiency of the virtual light path and enhance the imaging quality. In this example, the polarized reflective film is sandwiched between the two surfaces of the second lens 20 and the free-form surface prism 30 that are glued together. This setting can reduce the difficulty of assembling the optical film.

[0066] Furthermore, since the surface of the second lens 20 adjacent to the free-form prism 30 is a free-form surface, when a polarizing reflective film is provided thereon, the polarizing reflective film can be bonded to the surface of the second lens 20, for example, by coating, thereby achieving a strong bond. Of course, optical adhesive can also be used, and this is not limited in the present embodiment.

[0067] The second lens 20 can be used to transmit the second light 03, which is light in the real world; the surface of the second lens 20 away from the free-form prism is provided with an anti-reflection film.

[0068] Optionally, the surface of the second lens 20 away from the free-form prism 30 can be designed to be flat, so as to facilitate smooth mounting of an anti-reflection film or other types of optical film layers thereon.

[0069] Of course, the surface of the second lens 20 away from the free-form prism 30 may also be a non-planar surface, which is not limited in the present application.

[0070] In some examples of this application, such as Figure 1 As shown, the optical module also includes a display screen 40, which is located on the side of the first lens 10 away from the first surface 31; the display screen 40 is used to emit the first light 02, which is transmitted through the first lens 10 and the first surface 31, reflected by the second area 322, totally reflected by the first surface 31, totally reflected by the first area 321, reflected by the third surface 33, and transmitted through the first area 321 before entering the human eye 01.

[0071] In the implementation of the present application, the display screen 40 can be used to emit linearly polarized light or circularly polarized light. However, it should be noted that the light incident on the first lens 10 should be linearly polarized light.

[0072] Optionally, the light-emitting surface of the display screen 40 is provided with a screen protector 41, which is made of, for example, glass. The first light 02 emitted by the display screen 40 is transmitted through the screen protector 41 on the surface and then enters the first lens 10. The first light 02 (i.e., the virtual imaging light) is transmitted through the first lens 10, transmitted through the first surface 31 of the free-form surface prism 30, reflected by the second area 322 of the second surface 32, totally reflected by the first surface 31, totally reflected by the first area 321 of the second surface 32, reflected by the third surface 33, and then transmitted through the first area 321 before entering the human eye 01. It can be seen that the first light 02 is incident on the free-form surface prism 30 and undergoes at least three reflections, which can extend the propagation path of the light.

[0073] In some examples of this application, such as Figure 1 As shown, the display screen 40 is arranged along a first direction, and the angle between the display screen 40 and the first direction is -30° to +30°; wherein, the first direction is perpendicular to the thickness direction of the optical module.

[0074] It should be noted that if Figure 1 As shown, the thickness direction of the optical module is Figure 1 The horizontal direction shown may also be referred to as the length direction of the optical module. The optical module of the embodiment of the present application has a relatively small thickness, which may be less than 15 mm.

[0075] In the embodiments of the present application, Figure 1 As shown, the display screen 40 is located on the side of the first lens 10 facing away from the first surface 31 of the free-form prism 30, and the display screen 40 is tilted along a direction perpendicular to the thickness of the entire optical module, with a tilt range of -30° to +30° as mentioned above. This design is adopted because both surfaces of the first lens 10 are free-form surfaces. The display screen 40 is tilted in this manner so that the first light ray 02 emitted by the display screen 40 can meet the conditions for total internal reflection when it hits the first surface 31 of the free-form prism 30, thereby being able to undergo total internal reflection on the first surface 31. This can increase the number of reflections of the first light ray 02 in the free-form prism 30.

[0076] In some examples of the present application, the first region 321 is provided with an anti-reflection film; and the length ratio of the second region 322 to the first region 321 is 0.9-3.

[0077] In an embodiment of the present application, the free-form surface prism 30 is designed to include three optical surfaces, wherein the second surface 32 is the surface close to the human eye 01, and two different optical film layers are mounted on the second surface 32 in different regions, namely: an anti-reflection film provided in the first region 321 and a total reflection film provided in the second region 322. When the first light ray 02 of the virtual light path is incident on the second surface 32 and reflected, total reflection can occur on the first surface 31 of the free-form surface prism 30, which can increase the light propagation path of the virtual light path, and can improve the resolution of the optical module while reducing the thickness of the optical module. The second light ray 03 in the real world can pass through the first region of the second surface 32 as completely as possible. This ultimately presents a high-definition virtual reality image in the human eye 01, which can enhance the user's viewing experience.

[0078] It should be noted that, on the second surface 32 of the free-form prism 30, when the length ratio of the second region 322 to the first region 321 is 0.9 to 3, all first light rays 02 emitted by the display screen 40 can be totally reflected on the first surface 31. The length directions of the first region 321 and the second region 322 can be as follows: Figure 1 The direction shown is perpendicular to the thickness of the optical module (or the horizontal direction).

[0079] In some examples of this application, such as Figure 1 As shown, the first lens 10 includes two surfaces, and both surfaces of the first lens 10 are free-form surfaces.

[0080] In the optical module of the embodiment of the present application, by disposing a free-form surface lens, namely the above-mentioned first lens 10 , on one side of the first surface 31 of the free-form surface prism 30 , high-definition imaging of the optical module can be achieved.

[0081] In the entire optical module, the use of multiple free-form surfaces can increase the degree of freedom in optical module design and effectively improve the imaging quality of the optical module.

[0082] Optionally, an anti-reflection film is mounted on at least one of the two surfaces of the first lens 10 .

[0083] For example, both surfaces of the first lens 10 are free-form surfaces, and anti-reflection films are mounted on both surfaces.

[0084] In some examples of the present application, the thickness of the free-form surface prism 30 is T3, and T3 satisfies: 0.5 mm < T3 < 15 mm.

[0085] The thickness of the free-form surface prism 30 varies at different locations. Within the above-mentioned thickness range, the imaging quality of the optical module can be guaranteed without affecting the thickness and weight of the entire optical module.

[0086] Optionally, the thickness of the first lens 10 is T1, where T1 satisfies the following conditions: 1mm < T1 < 10mm; and the thickness of the second lens 20 is T2, where T2 satisfies the following conditions: 0.5mm < T2 < 15mm. Both the first lens 10 and the second lens 20 have free-form surfaces, with varying thicknesses at different locations. The thickness ranges of the first lens 10 and the second lens 20 in this application help reduce the size and weight of the optical module while also effectively cooperating with the free-form surface prism 30 to improve imaging quality.

[0087] In some examples of the present application, at least one of the free-form prism 30, the first lens 10, and the second lens 20 is made of plastic. When each lens in the optical module is made of plastic, the weight of the optical module can be effectively reduced.

[0088] The second lens 20 and the free-form surface prism 30 are glued together. For example, the two can be made of the same material, which can reduce chromatic aberration and aberration.

[0089] Optionally, the refractive index n of the first lens 10, the second lens 20, and the free-form surface prism 30 is: 1.45 < n < 1.70; and the dispersion coefficient v of the first lens 10, the second lens 20, and the free-form surface prism 30 is: 20 < v < 70. By adjusting the refractive index and dispersion coefficient of the two lenses to match them, the imaging quality of the optical module can be improved.

[0090] Example

[0091] like Figure 1 As shown, the optical module includes a first lens 10, a second lens 20 and a free-form surface prism 30, and these three lenses are all made of plastic;

[0092] The free-form surface prism 30 includes a first surface 31, a second surface 32, and a third surface 33. The first surface 31 and the third surface 33 are both free-form surfaces. The second surface 32 includes a first region 321 and a second region 322. An anti-reflection film is provided on the first region 321, and a total reflection film is provided on the second region 322. That is, different optical films are provided in two regions on the second surface 32.

[0093] The first lens 10 is located on one side of the first surface 31. The first light 02 is transmitted through the first lens 10 and enters the free-form surface prism 30. After being reflected by the second area 322, it is totally reflected on the first surface 31. The first light is refracted ≥3 times in the free-form surface prism 30. The second lens 20 is located on one side of the third surface 33. The second light 03 is transmitted through the second lens 20 and enters the free-form surface prism 30 and exits through the first area 321.

[0094] The optical parameters of the first lens 10 and the free-form surface prism 30 may be as shown in Tables 1 to 7 below, wherein 11 represents the surface of the first lens 10 away from the free-form surface prism 30, 12 represents the surface of the first lens 10 close to the free-form surface prism 30, 31 represents the first surface of the free-form surface prism 30, and 33 represents the third surface of the free-form surface prism 30.

[0095] Table 1

[0096]

[0097] Table 2

[0098]

[0099] Table 3

[0100]

[0101] Table 4

[0102] A19 A20 A21 A22 A23 A24 A25 A26 0.00E+00 0.00E+00 3.47E-12 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 1.16E-05 -7.08E-06 0.00E+00 1.55E-05 0.00E+00 0.00E+00 0.00E+00 0.00E+00 -2.01E+03 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 4.26E+03 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00

[0103] Table 5

[0104] A27 A28 A29 A30 A31 A32 A33 A34 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 -1.13E-08 0.00E+00 -1.30E-10 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00

[0105] Table 6

[0106]

[0107]

[0108] Table 7

[0109] A40 A41 A42 A43 A44 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 -8.13E-10 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00

[0110] The optical module provided in the above embodiment can be Figures 2 to 5 As shown:

[0111] Figure 2 is an MTF curve diagram of the optical module provided in the embodiment of the present application, Figure 3 is a schematic diagram of a point diagram of an optical module provided in an embodiment of the present application, Figure 4 is a field curvature distortion diagram provided by an embodiment of the present application, Figure 5 This is a vertical axis chromatic aberration diagram provided in an embodiment of the present application.

[0112] The MTF curve is a modulation transfer function graph that represents the imaging clarity of the optical module through the contrast of black and white line pairs. Figure 2 As shown, in this embodiment, the MTF is greater than 0.3 at 38 lp / mm, and the image is clear.

[0113] The point diagram refers to the formation of a diffuse pattern spread over a certain range when many light rays emitted from one point pass through the optical module and their intersection with the image plane is no longer concentrated at the same point due to aberration. It can be used to evaluate the imaging quality of the optical module. Figure 3 As shown, in this embodiment, the maximum value of the image point in the point diagram is less than 11 μm, and the image is clear.

[0114] The field curvature distortion diagram reflects the difference in image plane position when different fields of view form clear images. In this embodiment, Figure 4 As shown, the maximum value of field curvature is less than 0.4 mm, the distortion reflects the deformation of the imaging, and the maximum value of distortion is less than 20% (absolute value).

[0115] Vertical axis chromatic aberration is also called magnification chromatic aberration, which mainly refers to the difference in the focal position of blue light and red light on the image plane due to the dispersion of the refraction system when a complex main light on the object side is transformed into multiple light rays when it is emitted on the image side. Figure 5 As shown, the maximum chromatic aberration value of the optical module is less than 130μm.

[0116] According to another aspect of an embodiment of the present application, a head-mounted display device is further provided, comprising a housing and the optical module as described above.

[0117] The head-mounted display device is, for example, an AR head-mounted device, including AR glasses or an AR helmet, etc., and the embodiments of the present application do not impose specific restrictions on this.

[0118] The specific implementation of the head-mounted display device of the embodiment of the present application can refer to the above-mentioned embodiments of the optical module, and therefore at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be repeated here one by one.

[0119] The above embodiments focus on the differences between the various embodiments. As long as the different optimization features between the various embodiments are not contradictory, they can be combined to form a better embodiment. Considering the simplicity of the text, they will not be repeated here.

[0120] Although some specific embodiments of the present application have been described in detail by way of example, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present application. It should be understood by those skilled in the art that the above examples may be modified without departing from the scope and spirit of the present application. The scope of the present application is defined by the appended claims.

Claims

1. An optical module, characterized in that: The optical module includes: A free-form surface prism (30), the free-form surface prism (30) comprising a first surface (31), a second surface (32), and a third surface (33), the first surface (31) and the third surface (33) being both free-form surfaces, the second surface (32) comprising a first region (321) and a second region (322), wherein the second region (322) is provided with a total reflection film; a first lens (10), the first lens (10) being located on one side of the first surface (31), the first lens (10) comprising two surfaces, both surfaces of the first lens (10) being free-form surfaces; and a second lens (20), the second lens (20) being located on one side of the third surface (33); a display screen (40), the display screen (40) being located on a side of the first lens (10) facing away from the first surface (31); The first light (02) emitted by the display screen (40) is transmitted through the first lens (10), transmitted through the first surface (31) of the free-form surface prism (30), reflected through the second area (322) of the second surface (32), totally reflected through the first surface (31), totally reflected through the first area (321) of the second surface (32), reflected through the third surface (33), and transmitted through the first area (321) before entering the human eye (01); the first light (02) is refracted ≥3 times in the free-form surface prism (30); The second light (03) is a light in the real world. The second light (03) also enters the human eye (01) after passing through the second lens (20) and the first area (321) of the free-form surface prism (30).

2. The optical module according to claim 1, wherein: The optical module further comprises a polarized reflective element, and the polarized reflective element is located between the free-form surface prism (30) and the second lens (20).

3. The optical module according to claim 1, wherein: The surface of the second lens (20) close to the free-form surface prism (30) and the third surface (33) are both free-form surfaces, and the two are glued together.

4. The optical module according to claim 3, wherein: A polarizing reflection element is provided on the surface of the second lens (20) close to the free-form surface prism (30).

5. The optical module according to claim 1, wherein: An anti-reflection film is provided on the surface of the second lens (20) away from the free-form surface prism (30).

6. The optical module according to claim 1, wherein: The display screen (40) is arranged along a first direction, and the angle between the display screen (40) and the first direction is -30° to +30°; The first direction is perpendicular to the thickness direction of the optical module.

7. The optical module according to claim 1, wherein: The first region (321) is provided with an anti-reflection film; The length ratio of the second region (322) to the first region (321) is 0.9 to 3.

8. The optical module according to claim 1, wherein: An anti-reflection film is mounted on at least one of the two surfaces of the first lens (10).

9. The optical module according to claim 1, wherein: The thickness of the free-form surface prism (30) is T3, and T3 satisfies: 0.5 mm < T3 < 15 mm.

10. The optical module according to claim 1, wherein: The thickness of the first lens (10) is T1, and T1 satisfies: 1mm<T1<10mm; The thickness of the second lens (20) is T2, and T2 satisfies: 0.5mm<T2<15mm.

11. The optical module according to claim 1, wherein: At least one of the free-form surface prism (30), the first lens (10) and the second lens (20) is made of plastic material.

12. A head-mounted display device, characterized in that: include: case; as well as The optical module according to any one of claims 1 to 11.

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