Optical modules and head-mounted display devices

Abstract

The present application discloses an optical module and a head-mounted display device. The optical module includes, from the object side to the image side, a first lens group, a reflective element, a third lens, an aperture, and a second lens group, wherein: the reflective element includes a reflective surface, the first lens group is arranged along the first optical axis; the third lens and the second lens group are arranged along the second optical axis; the third lens has a positive optical power, and the third lens is a biconvex spherical lens. The optical solution of the present application embodiment, by providing a reflective element in the optical path, can separate multiple optical devices into two optical paths. When the optical module is applied to a head-mounted display device, for example, it is beneficial to reduce the device's thickness, achieving the requirements of thinning and compactness of the optical module as a whole, while also achieving good imaging effects.

Description

Technical Field

[0001] The present application belongs to the field of optical lens technology. Specifically, the present application relates to an optical module and a head-mounted display device. Background Art

[0002] In recent years, with the rapid development of optical technology, the requirements for imaging clarity in optical modules have become increasingly higher. To achieve higher pixel counts, optical modules typically require larger chips. At the same time, as the chip size increases, the overall size of the optical module also increases. When optical modules are applied to products such as head-mounted display devices, the entire head-mounted display device becomes larger, affecting user comfort.

[0003] Due to design requirements such as thinness and compactness of the entire device, existing technologies generally require the miniaturization of optical modules. However, excessive compression of the volume will result in poor imaging quality of the optical module. Summary of the Invention

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

[0005] According to a first aspect of an embodiment of the present application, an optical module is provided, comprising, from the object side to the image side, a first lens group, a reflective element, a third lens, an aperture, and a second lens group, wherein:

[0006] The reflective element includes a reflective surface;

[0007] The first lens group is arranged along a first optical axis;

[0008] The third lens and the second lens group are arranged along the second optical axis;

[0009] The optical power of the third lens is positive, and the third lens is a biconvex spherical lens.

[0010] Optionally, the first lens group includes a first lens, the first lens is a meniscus spherical lens, and the optical power of the first lens is negative.

[0011] Optionally, the refractive index N of the first lens is d1 >1.65, the Abbe number V of the first lens d1 >45.

[0012] Optionally, a side of the second lens group away from the aperture is the image side;

[0013] The distance from the first lens to the center of the reflecting surface is T1, the distance from the reflecting surface to the center of the image side is T2, and the ratio of T2 to T1 satisfies: 1.2<T2 / T1<1.6.

[0014] Optionally, the first lens group includes a second lens, and the reflective element is located between the second lens and the third lens;

[0015] The second lens is a meniscus aspheric lens.

[0016] Optionally, the optical power of the second lens is negative, and the Abbe number V of the second lens is d2 >50.

[0017] Optionally, the reflective element is a right-angle prism, and the reflective element further includes an incident surface and an exit surface perpendicular to each other, and the reflective surface is tilted;

[0018] The incident surface is perpendicular to the first optical axis, the exit surface is perpendicular to the second optical axis, and the center of the reflective surface is located at the intersection of the first optical axis and the second optical axis.

[0019] Optionally, the focal length of the second lens is F2, and the ratio of F2 to the effective focal length EFL of the optical module satisfies: -3.6<F2 / EFL<-2.4.

[0020] Optionally, the total optical length of the optical module is TTL, the maximum field of view of the optical module is FOV, and the ratio of FOV to TTL satisfies 3<FOV / TTL<5.

[0021] Optionally, the refractive index N of the third lens is d3 >1.7, the Abbe number V of the third lens d3 <30.

[0022] Optionally, the second lens group includes a fourth lens, a fifth lens, a sixth lens, and a seventh lens sequentially arranged along the second optical axis, and the optical power of the second lens group is positive;

[0023] The aperture is located between the third lens and the fourth lens;

[0024] The fourth lens and the fifth lens are cemented together to form a cemented lens group, and the cemented lens group has positive optical power.

[0025] Optionally, the fourth lens is a biconvex spherical lens, the optical power of the fourth lens is positive, and the Abbe number V of the fourth lens is d4 >50;

[0026] The fifth lens is a spherical lens, the optical power of the fifth lens is negative, and the refractive index N of the fifth lens is d5 >1.7, the Abbe number V of the fifth lens d5 <30.

[0027] Optionally, the sixth lens is a spherical lens, and the optical power of the sixth lens is positive.

[0028] Optionally, the seventh lens is a meniscus aspheric lens, and the optical power of the seventh lens is positive.

[0029] Optionally, the Abbe number V of the sixth lens is d6 >45; Abbe number V of the seventh lens d7 >40.

[0030] Optionally, the optical module further includes a filter element, and the filter element is located between the second lens group and the image side.

[0031] Optionally, the aperture value FNO of the optical module is ≤2.0.

[0032] According to a second aspect of the embodiments of the present application, a head-mounted display device is further provided, wherein the head-mounted display device includes the optical module described in the first aspect.

[0033] According to an embodiment of the present application, an optical module is provided. By arranging a reflective element in the optical path structure, multiple optical devices in the module can be separated into two mutually perpendicular optical paths, thereby reducing the length of the optical module, achieving thinning and compactness of the optical module while also achieving good imaging effects.

[0034] Other features and advantages of the present application will become apparent from the following detailed description of exemplary embodiments of the present application with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the application and, together with the description, serve to explain the principles of the application.

[0036] Figure 1 This is one of the structural diagrams of the optical module provided in an embodiment of the present application;

[0037] Figure 2 for Figure 1 Modulation transfer function diagram of the provided optical module;

[0038] Figure 3 for Figure 1 Spot diagram of the provided optical module;

[0039] Figure 4 for Figure 1 Provided field curvature and distortion diagrams of the optical module;

[0040] Figure 5 for Figure 1 Provide vertical axis chromatic aberration diagram of the optical module;

[0041] Figure 6 The second structural diagram of the optical module provided in the embodiment of the present application;

[0042] Figure 7 for Figure 6 Modulation transfer function diagram of the provided optical module;

[0043] Figure 8 for Figure 6 Spot diagram of the provided optical module;

[0044] Figure 9 for Figure 6 Provided field curvature and distortion diagrams of the optical module;

[0045] Figure 10 for Figure 6 Provide vertical axis chromatic aberration diagram of the optical module;

[0046] Figure 11 The third structural diagram of the optical module provided in the embodiment of the present application;

[0047] Figure 12 for Figure 11 Spot diagram of the provided optical module;

[0048] Figure 13 for Figure 11 Modulation transfer function diagram of the provided optical module;

[0049] Figure 14 for Figure 11 Provided field curvature and distortion diagrams of the optical module;

[0050] Figure 15 for Figure 11 Provided diagram of vertical axis chromatic aberration of the optical module.

[0051] Description of reference numerals:

[0052] 100, first lens group;

[0053] 110, first lens; S1, object-side surface of the first lens; S2, image-side surface of the first lens;

[0054] 120, second lens; S3, object-side surface of the second lens; S4, image-side surface of the second lens;

[0055] 200, second lens group;

[0056] 210, fourth lens; S9, object-side surface of the fourth lens; S10, cemented surface;

[0057] 220, fifth lens; S11, image-side surface of the fifth lens;

[0058] 230, sixth lens; S12, object-side surface of the sixth lens; S13, image-side surface of the sixth lens;

[0059] 240, seventh lens; S14, object-side surface of the seventh lens; S15, image-side surface of the seventh lens;

[0060] 300, third lens; S5, object-side surface of the third lens; S6, image-side surface of the third lens;

[0061] 400, reflecting element; 410, reflecting surface; 420, incident surface; 430, exit surface;

[0062] 500, aperture; 600, image side;

[0063] 700, filter element; S16, object-side surface of the filter element; S17, image-side surface of the filter element. DETAILED DESCRIPTION

[0064] 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.

[0065] 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.

[0066] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0067] 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.

[0068] 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.

[0069] The embodiment of the present application provides an optical module, which can be applied to a head-mounted display device, such as VR smart glasses, etc. The optical module can form a wide-angle lens, for example.

[0070] In the embodiments of the present application, Figure 1 As shown, the optical module includes a first lens group 100, a reflective element 400, a third lens 300, an aperture 500 and a second lens group 200, which are sequentially distributed from the object side to the image side, wherein:

[0071] The reflective element 400 has a reflective surface 410 , the first lens group 100 is arranged along a first optical axis, and the third lens 300 and the second lens group 200 are arranged along a second optical axis;

[0072] The third lens 300 has positive refractive power and is a biconvex spherical lens.

[0073] In other words, the optical module provided in the embodiments of the present application has an optical structure designed to be divided into a first optical axis and a second optical axis, with the reflective element 400 as the boundary. A first lens group 100 is disposed along the first optical axis, and the first lens group 100 is disposed on the object-side of the reflective element 400. A third lens 300, an aperture 500, and a second lens group 200 are sequentially disposed along the second optical axis, and the third lens 300, the aperture 500, and the second lens group 200 are located on the image-side of the reflective element 400.

[0074] It should be noted that the object side refers to the side where the object to be photographed is located, such as Figure 1 The image side refers to the side where the optical module forms an image, such as Figure 1 The top side.

[0075] The optical module of the embodiment of the present application is as follows: Figure 1 As shown, the propagation path of the light is as follows: the light reflected from the object side first passes through the first lens group 100 along the first optical axis, then changes direction after being reflected by the reflective surface 410 of the reflective element 400, and then passes through the third lens 300, the aperture 500 and the second lens group 200 in sequence along the second optical axis, and finally obtains the desired image on the image side.

[0076] In the present application, it is preferred that a reflective surface 410 is provided on the reflective element 400, the reflective surface 410 is tilted, the first optical axis forms an angle of 45° with the reflective surface 410, and the first optical axis is perpendicular to the second optical axis.

[0077] When the first optical axis is perpendicular to the second optical axis, light passes through the first lens group 100 and is incident vertically on the third lens 300 and the second lens group 200 via the reflective surface 410. The arrangement of the reflective element 400 achieves a vertical deflection of light reflected from the object side between the first and second optical axes, which helps reduce the tolerance sensitivity of the reflective element 400, improves image quality, and avoids undesirable phenomena such as half-clear images and half-blurred images caused by an asymmetric arrangement.

[0078] Of course, the angle between the reflective surface 410 and the first optical axis can also be set to other angles as needed, and the angle between the first optical axis and the second optical axis can also be set as needed. This application does not limit this.

[0079] In the present application, it is preferred that the reflective element 400 be made of a glass material with a high refractive index, which is beneficial to improving the reflection efficiency of the reflective element. Of course, the reflective element 400 can also be made of other materials, such as plastic materials, and the material of the reflective element 400 is not specifically limited in the present application.

[0080] It should be noted that the reflective surface 410 can be formed by coating an optical reflective film on one surface of the reflective element 400. Of course, the reflective surface 410 can also be formed in other ways.

[0081] In the embodiment of the present application, the third lens 300 is a biconvex spherical lens with positive optical power. The side of the third lens 300 close to the object is the object side, and the object side S5 of the third lens is a convex surface. Figure 1 The side of the third lens 300 close to the image side is the image side surface, and the image side surface S6 of the third lens can also be set as a convex surface, as shown in FIG. Figure 1 The upper surface of the third lens 300 is shown in FIG. The surface design of the third lens 300 is conducive to converging the light reflected by the reflective element 400 in the entire optical path.

[0082] The aperture 500 is, for example, an aperture stop. It can be used to control the optical module's clear aperture, adjust the light flux entering the second lens group 200, and control the diameters of the optical module's front and rear ports. It also reduces stray light interference generated by reflections from other lenses, thereby enhancing the clarity of the optical module's imaging. Furthermore, the provision of the aperture 500 helps reduce the incident angle of the principal ray, converging the light reflected by the reflective element 400.

[0083] Typically, the aperture of the diaphragm 500 is a fixed value. Of course, in order to flexibly adjust the amount of light passing according to actual needs, the diaphragm 500 can also be set in a manner that the aperture size can be adjusted.

[0084] In the embodiment of the present application, by placing a reflective element 400 in the optical path and distributing multiple optical components on both sides of the reflective element 400, that is, distributing the multiple optical components in the module on two optical paths, not only can the thickness and length of the optical module be effectively reduced, but the overall volume of the reflective element 400 can also be effectively compressed, achieving the requirements of thinning and compacting the optical module as a whole. Furthermore, the optical module provided by the present application also has the characteristics of a wide field of view and excellent imaging quality.

[0085] The optical module of the embodiment of the present application is compact and has good imaging quality. When applied to a head-mounted display device, it can achieve lightweight and thin equipment and high-quality imaging, thereby improving the user's wearing comfort and visual experience.

[0086] In some examples of the present application, the first lens group 100 includes a first lens 110 , which is a meniscus spherical lens and has negative optical power.

[0087] like Figure 1 As shown, the left side of the first lens 110 is the object side surface, and the object side surface S1 of the first lens can be set as a convex surface. The right side of the first lens 110 is the image side surface, and the image side surface S2 of the first lens can be set as a concave surface.

[0088] Optionally, the refractive index N of the first lens 110 is d1 >1.65, Abbe number V of the first lens 110 d1 >45.

[0089] It should be noted that the first lens 110 can be made of glass material, and of course other materials such as plastic material can also be selected, and this application is not limited to this.

[0090] The first lens 110 is made of a glass material with a high refractive index and low dispersion, which is conducive to quickly deflecting light and reducing the front port diameter and overall chromatic aberration of the optical module.

[0091] In some examples of this application, reference is made to Figure 1 The side of the second lens group 200 away from the aperture 500 is the image side.

[0092] The distance from the first lens 110 to the center of the reflective surface 410 is T1, and the distance from the center of the reflective surface 410 to the image side 600 is T2. The ratio of T2 to T1 satisfies: 1.2<T2 / T1<1.6.

[0093] In the embodiment of the present application, an image side 600 is provided at the image side for imaging, that is, the image side 600 is provided on the side of the second lens group 200 away from the aperture 500. Figure 1 The middle image side 600 is located above the second lens group 200. The incident light reflected from the object side is reflected by the reflective element 400, passes through the third lens 300, the aperture 500 and the second lens group 200 along the second optical axis, and finally illuminates the image side 600 and forms an image.

[0094] It should be noted that image element 600 may be a CCD, which stands for Charge Coupled Device (CCD), and can be referred to as a CCD image sensor. A CCD is a semiconductor device that converts optical images into digital signals. Tiny photosensitive materials embedded in a CCD are called pixels. The more pixels a CCD contains, the higher the image resolution it provides. A CCD functions like film, but it converts image pixels into digital signals. The CCD has many neatly arranged capacitors that sense light and convert images into digital signals. Controlled by an external circuit, each small capacitor transfers its charge to its adjacent capacitor.

[0095] Controlling the distance between the center position of the reflective surface 410 and the first lens 110 and the image side 600 according to the above-mentioned constraints is beneficial to controlling the dimensions of the optical module in the directions of the first optical axis and the second optical axis, that is, controlling the dimensions of the optical module in the thickness / length direction of the entire device, and compressing the volume of the reflective element 400, thereby effectively achieving the requirements of thinning and compactness of the overall optical module.

[0096] In some examples of the present application, the first lens group 100 includes a second lens 120, and the reflective element 400 is located between the second lens 120 and the third lens 300. The second lens 120 is a meniscus aspheric lens.

[0097] like Figure 1 As shown, the left side of the second lens 120 is the object side surface, and the object side surface S3 of the second lens can be set as a convex surface. The right side of the second lens 120 is the image side surface, and the image side surface S4 of the second lens can be set as a concave surface.

[0098] In the embodiment of the present application, the second lens 120 may adopt the aspheric design in the above example, which can effectively reduce the distortion and field curvature aberration of the optical module, thereby improving image quality.

[0099] In some examples of the present application, the optical power of the second lens 120 is negative, and the Abbe number V of the second lens 120 is d2 >50.

[0100] Optionally, the second lens 120 is made of glass. Using glass for the second lens 120 is beneficial for further reducing the distortion of the second lens 120 and improving temperature stability.

[0101] Of course, the second lens 120 may also be made of other materials, and this application does not impose any specific limitation on this.

[0102] In some examples of the present application, the reflective element 400 is a right-angle prism, and the reflective element 400 further includes a mutually perpendicular incident surface 420 and an exit surface 430, and the reflective surface 410 is tilted. The incident surface 420 is perpendicular to the first optical axis, the exit surface 430 is perpendicular to the second optical axis, and the center of the reflective surface 410 is located at the intersection of the first and second optical axes.

[0103] In the embodiment of the present application, the side surface of the reflective element 400 close to the first lens group 100 is the incident surface 420, that is, Figure 1 The left side surface of the reflective element 400. The incident surface 420 is perpendicular to the first optical axis. The side surface of the reflective element 400 close to the third lens 300 is the exit surface 430, that is, Figure 1 The incident surface 420 is perpendicular to the upper surface of the reflective element 400. The exit surface 430 is perpendicular to the second optical axis.

[0104] The reflective element 400 has a reflective surface 410 that is tilted. Figure 1 The right side slope of the middle reflective element 400. The reflective surface 410 forms an angle of 45° with the first optical axis, and the reflective surface 410 also forms an angle of 45° with the second optical axis.

[0105] The center of reflective surface 410 is located at the intersection of the first and second optical axes. In other words, the first optical axis deflects 90° at the center of reflective surface 410 to form the second optical axis. This arrangement allows multiple optical elements to be positioned along these two optical axes in different directions, reducing the tolerance sensitivity of reflective element 400, improving image quality, and avoiding undesirable effects such as half-clear images and half-blurred images caused by asymmetrical placement.

[0106] In some examples of the present application, the focal length of the second lens 120 is F2, and the ratio of F2 to the effective focal length EFL of the optical module satisfies: -3.6<F2 / EFL<-2.4.

[0107] In the embodiments of the present application, the effective focal length (EFL) of the optical module can be optimized by properly adjusting the focal length of the second lens 120. Adjusting the focal length (F2) of the second lens 120 and the effective focal length (EFL) according to the aforementioned constraints facilitates the optical module of the present application to rapidly narrow the wide-angle light beam, reduce the front port diameter, and increase the aperture of the optical module.

[0108] It's important to note that the aperture of an optical module, also known as the absolute aperture or effective aperture, represents the maximum light-entering hole in the optical module, or in other words, the maximum aperture of the optical module. The aperture is expressed using the aperture coefficient F, which is calculated as: F = focal length of the optical module / maximum aperture diameter. It can also be expressed as the reciprocal of the F coefficient, such as F2.8 or 1:2.8. A smaller F indicates a larger aperture.

[0109] The larger the aperture of an optical module, the greater its practical value. The advantages of a large-aperture optical module include: (1) facilitating handheld shooting in dim light using the available light; (2) facilitating capturing a small depth of field effect, combining virtual and real images; and (3) facilitating the use of a higher shutter speed to freeze moving objects. The optical module of the present application, due to its large aperture, can combine the aforementioned advantages.

[0110] In some examples of the present application, the total optical length of the optical module is TTL, the maximum field of view of the optical module is FOV, and the ratio of FOV to TTL satisfies 3<FOV / TTL<5.

[0111] It should be noted that the total optical length TTL of the optical module is the sum of T1 and T2, where T1 is the distance from the first lens 110 to the center of the reflective surface 410, and T2 is the distance from the center of the reflective surface 410 to the image side 600.

[0112] In optical engineering, the field of view (FOV) determines the visual range of an optical instrument. The FOV is expressed as FOV. In the optical module of this application, the ratio of the maximum FOV to the total optical length is adjusted according to the aforementioned constraints. This results in a larger FOV, reaching 140° or greater, which is beneficial for wide-angle photography and improves the shooting effect.

[0113] Optionally, the refractive index N of the third lens 300 is d3 >1.7, Abbe number V of the third lens 300 d3 <30.

[0114] In the embodiment of the present application, the third lens 300 is made of a high refractive index and low dispersion material, which is beneficial for converging the main light reflected by the reflective element 400, reducing light loss and improving imaging quality.

[0115] In some examples of the present application, the second lens group 200 includes a fourth lens 210, a fifth lens 220, a sixth lens 230, and a seventh lens 240 sequentially arranged along the second optical axis, and the optical power of the second lens group 200 is positive;

[0116] The aperture 500 is located between the third lens 300 and the fourth lens 210 . The fourth lens 210 and the fifth lens 220 are cemented together to form a cemented lens group. The cemented lens group has positive optical power.

[0117] Optionally, the fourth lens 210 is a biconvex spherical lens, the optical power of the fourth lens 210 is positive, and the Abbe number V of the fourth lens 210 is d4 >50;

[0118] The fifth lens 220 is a spherical lens, the optical power of the fifth lens 220 is negative, and the refractive index N of the fifth lens 220 is d5 >1.7, the Abbe number V of the fifth lens 220 d5 <30.

[0119] like Figure 1 As shown, the lower surface of the fourth lens 210 is the object side surface, and the object side surface S9 of the fourth lens can be set as a convex surface. The upper surface of the fourth lens is the image side surface, and the image side surface of the fourth lens is a convex surface.

[0120] like Figure 1 As shown, the lower surface of the fifth lens 220 is the object side surface, and the object side surface of the fifth lens is concave. The upper surface of the fifth lens 220 is the image side surface, and the image side surface S11 of the fifth lens is concave.

[0121] The fourth lens 210 and the fifth lens 220 are combined into a cemented lens, that is, the upper surface of the fourth lens 210 and the lower surface of the fifth lens 220 are cemented to each other, forming a cemented surface S10. The cemented lens group has positive refractive power.

[0122] In the present application, the fourth lens 210 is made of a low-dispersion material, and the fifth lens 220 is made of a high-dispersion material. By gluing the two together, they can effectively reduce chromatic aberration and spherical aberration, improve problems such as purple fringing that are prone to occur in wide-angle lenses, and improve shooting effects.

[0123] In some examples of the present application, the sixth lens 230 is a spherical lens, and the optical power of the sixth lens 230 is positive.

[0124] like Figure 1 As shown, the lower surface of the sixth lens 230 is the object side surface, and the object side surface S12 of the sixth lens is a convex surface. The upper surface of the sixth lens 230 is the image side surface, and the image side surface S13 of the sixth lens is a convex surface.

[0125] In some examples of the present application, the seventh lens 240 is a meniscus aspheric lens, and the optical power of the seventh lens 240 is positive.

[0126] like Figure 1 As shown, the lower surface of the seventh lens element 240 is the object side surface, and the object side surface S14 of the seventh lens element is convex. The upper surface of the seventh lens element 240 is the image side surface, and the image side surface S15 of the seventh lens element is concave. The seventh lens element 240 is an aspherical lens, which helps correct coma and field curvature, thereby improving image quality.

[0127] Optionally, the seventh lens 240 may be made of glass, which is beneficial for improving image quality and temperature stability.

[0128] In some examples of the present application, the Abbe number V of the sixth lens 230 is d6>45, the Abbe number V of the seventh lens 240 d7 >40.

[0129] The sixth lens is made of high-refractive-index, low-dispersion material, which helps reduce chromatic aberration and improve image clarity.

[0130] Optionally, the surface shape of the second lens 120 and the seventh lens 240 is an even aspheric surface shape, and the surface shape satisfies the following formula:

[0131] Z=cy 2 / {1+[1-(1+k)c 2 y 2 ] 1 / 2}+a1y 2 +a2y 4 +a3y 6 +a4y 8 +a5y 10 +a6y 12 +a7y 14 +a8y 16

[0132] Here, parameter c is the curvature corresponding to the radius, y is the radial coordinate (its unit is the same as the lens length unit), and k is the conic coefficient. When k is less than -1, the surface curve is a hyperbola; when k is equal to -1, the surface curve is a parabola; when k is between -1 and 0, the surface curve is an ellipse; when k is equal to 0, the surface curve is a circle; when k is greater than 0, the surface curve is an oblate curve. a1 to a8 represent the coefficients corresponding to each radial coordinate. These parameters can be used to precisely set the shape and size of the aspheric surface of the lens imaging optical surface.

[0133] It should be noted that in the embodiments of the present application, all lenses in the optical module can be made of, for example, glass. Due to the price advantage of glass, this can reduce the production cost of the entire optical module. Furthermore, glass also has the characteristic of high temperature resistance. Glass has a low thermal distortion rate and high stability. Therefore, each lens in the optical path can be designed to be made of glass to avoid the impact of high temperatures on the performance of the optical module.

[0134] Of course, those skilled in the art can reasonably select the material of each lens in the optical module according to specific needs, and this is not limited in the embodiments of the present application.

[0135] In some examples of this application, reference is made to Figure 1 The optical module further includes a filter element 700 , which is located between the second lens group 200 and the image side 600 .

[0136] It should be noted that the filter element 700 is a flat glass lens with optical filtering function. The object-side surface S16 and the image-side surface S17 of the filter element are both flat, that is, the upper surface and the lower surface of the filter element are both flat.

[0137] By providing the filter element 700 , light waves in non-working bands can be filtered according to actual needs, thereby effectively reducing imaging stray light and color deviation problems and improving the imaging performance of the optical element.

[0138] It should be noted that stray light in an optical system is non-effective light. For example, it can be caused by multiple reflections within the effective aperture, mechanical reflections, or reflections outside the effective aperture, resulting in ghost images or flares. These stray lights may affect normal imaging.

[0139] In some examples of the present application, the aperture value FNO of the optical module is ≤2.0.

[0140] It should be noted that the aperture value (FNO) refers to the aperture ratio of the projection lens. Specifically, the aperture value (FNO) is the ratio of the focal length to the aperture diameter. When the aperture value (FNO) is smaller, the relative diameter of the projection lens is larger, and the amount of light passing through is greater. When the aperture ratio is larger, the relative diameter of the projection lens is smaller, and the amount of light passing through is less.

[0141] The aperture value of the optical module of the present application is ≤2.0, which ensures that the optical module has sufficient light transmittance, thereby improving the photosensitivity of the chip in dark environments.

[0142] In order to further optimize the performance of the optical module, three examples are used below to illustrate.

[0143] Example 1

[0144] like Figure 1 As shown, the optical module includes, from the object side to the image side, a first lens 110, a second lens 120, a reflective element 400, a third lens 300, an aperture 500, a fourth lens 210, a fifth lens 220, a sixth lens 230, a seventh lens 240, and a filter element 700. Among them:

[0145] The first lens 110 and the second lens 120 are disposed along a first optical axis.

[0146] Reflective element 400 has a right-angled edge. The surface of reflective element 400 near first lens group 100 is an incident surface 420, which is perpendicular to the first optical axis. The surface of reflective element 400 near third lens 300 is an exit surface 430, which is perpendicular to the second optical axis. Reflective element 400 includes an inclined reflective surface 410, which forms a 45° angle with the first optical axis.

[0147] The third lens 300 , the fourth lens 210 , the fifth lens 220 , the sixth lens 230 and the seventh lens 240 are arranged along the second optical axis. The second optical axis is perpendicular to the first optical axis and forms an angle of 45° with the reflective surface 410 .

[0148] See Table 1 below, which contains Figure 1 The surface type, curvature radius, thickness, material refractive index, Abbe number, refractive mode, half-aperture and coordinate turning data of each lens in the optical module shown.

[0149] Table 1

[0150]

[0151] The aspheric coefficients of the second lens 120 and the seventh lens 240 of Example 1 disclosed in this application are shown in Table 2 below:

[0152] Table 2

[0153]

[0154] The main parameters of Example 1 disclosed in this application are shown in Table 3:

[0155] Table 3

[0156]

[0157] In Example 1, the aperture value FNO is 2, and the field of view angle FOV is 120°.

[0158] Based on the data in Tables 1 to 3, Figure 2 As shown, Figure 2 The figure shows the MTF curve of the optical module. The MTF curve refers to the relationship between the modulation degree and the number of line pairs per millimeter in the image, which is used to evaluate the ability to restore the details of the scene. Figure 2 It can be seen that the MTF value of the central field of view of the optical module is as high as 0.6 at a field frequency of 230 lp / mm, and the MTF value of the maximum field of view at a field frequency of 100 lp / mm is also above 0.5. The optical module provided in this embodiment 1 has high resolution and good imaging quality.

[0159] Based on the data in Tables 1 to 3, Figure 3 The figure shows the point diagram of the optical module. After many light rays emitted from one point pass through the optical system, due to aberration, their intersection with the image plane is no longer concentrated at the same point, but forms a diffuse pattern spread over a certain range, which is called a point diagram. Figure 3 It can be seen that the maximum diameter of the point diagram in the optical module provided in the first embodiment is 3.2 μm, the light diffusion range is small, and the imaging quality is good.

[0160] Based on the data in Tables 1 to 3, Figure 4 The figure shows the field curvature distortion curve of the optical module. Field curvature refers to the curvature of the image field, which is mainly used to indicate the degree of non-coincidence between the intersection of the entire light beam and the ideal image point in the optical module. Distortion refers to the aberration of different magnifications of different parts of an object when it is imaged through a projection lens. Distortion will cause the similarity of the object and image to deteriorate, but will not affect the clarity of the image. Figure 4 It can be seen that the field curvature of the spot diagram of the optical module provided in this embodiment 1 is less than 0.03 mm, and the optical distortion is less than -30%, which meets the viewing requirements of the human eye.

[0161] Based on the data in Tables 1 to 3, Figure 5 The vertical axis chromatic aberration curve of the optical module is shown in the figure. Vertical axis chromatic aberration is also called magnification chromatic aberration, which mainly refers to the difference between the focal positions of hydrogen blue light and hydrogen red light on the image plane when a complex main light ray is transformed into multiple light rays due to the dispersion of the refractive system. Figure 5 It can be seen that the vertical axis chromatic aberration of the optical module provided in this embodiment 1 is less than 3.2 μm, the imaging smear degree is extremely low, and the imaging quality is good.

[0162] Example 2

[0163] The optical module in Example 2 disclosed in this application is substantially the same as that in Example 1. The difference between this optical module and Example 1 is that:

[0164] Refer to Table 4 below, which contains Figure 6 The surface type, curvature radius, thickness, material refractive index, Abbe number, refractive mode, half-aperture and coordinate turning data of each lens in the optical module are shown.

[0165] Table 4

[0166]

[0167]

[0168] The aspheric coefficients of the second lens 120 and the seventh lens 240 of Example 2 disclosed in this application are shown in Table 5 below:

[0169] Table 5

[0170]

[0171] The main parameters of Example 2 disclosed in this application are shown in Table 6:

[0172] Table 6

[0173]

[0174] In Example 2, the FNO is 1.85 and the field of view (FOV) is 140°. Compared with Example 1, the aperture in Example 2 is slightly larger, and the image circle size is slightly smaller to accommodate a smaller photosensitive chip, resulting in a slightly reduced overall volume of the optical module.

[0175] Based on the data in Tables 4 to 6, Figure 7 The figure shows the MTF curve of the optical module. The MTF curve refers to the relationship between the modulation degree and the number of line pairs per millimeter in the image, which is used to evaluate the ability to restore the details of the scene. Figure 7 It can be seen that the MTF value of the optical module's central field of view at a field frequency of 230 lp / mm is as high as 0.6, and the MTF value of the maximum field of view at a field frequency of 100 lp / mm is also above 0.5. The optical module provided in this embodiment 2 has high resolution and good imaging quality.

[0176] Based on the data in Tables 4 to 6, Figure 8 The figure shows the point diagram of the optical module. After many light rays emitted from one point pass through the optical system, due to aberration, their intersection with the image plane is no longer concentrated at the same point, but forms a diffuse pattern spread over a certain range, which is called a point diagram. Figure 8 It can be seen that the maximum diameter of the point diagram in the optical module provided in this embodiment 2 is 3.2 μm, the light diffusion range is small, and the imaging quality is good.

[0177] Based on the data in Tables 4 to 6, Figure 9 The figure shows the field curvature distortion curve of the optical module. Field curvature refers to the curvature of the image field, which is mainly used to indicate the degree of non-coincidence between the intersection of the entire light beam and the ideal image point in the optical module. Distortion refers to the aberration of different magnifications of different parts of an object when it is imaged through a projection lens. Distortion will cause the similarity of the object and image to deteriorate, but will not affect the clarity of the image. Figure 9 It can be seen that the field curvature of the spot diagram of the optical module provided in this embodiment 2 is less than 0.01 mm, and the optical distortion is less than -30%, which meets the viewing requirements of the human eye.

[0178] Based on the data in Tables 4 to 6, Figure 10 The vertical axis chromatic aberration curve of the optical module is shown in the figure. Vertical axis chromatic aberration is also called magnification chromatic aberration, which mainly refers to the difference between the focal positions of hydrogen blue light and hydrogen red light on the image plane when a complex main light ray is transformed into multiple light rays due to the dispersion of the refractive system. Figure 10 It can be seen that the vertical axis chromatic aberration of the optical module provided in this embodiment 2 is less than 3 μm, the imaging smear degree is extremely low, and the imaging quality is good.

[0179] Example 3

[0180] The optical module in Example 3 disclosed in this application is substantially the same as that in Example 2. The difference between this optical module and Example 2 is that:

[0181] Refer to Table 7 below, which contains Figure 11 The surface type, curvature radius, thickness, material refractive index, Abbe number, refractive mode, half-aperture and coordinate turning data of each lens in the optical module are shown.

[0182] Table 7

[0183]

[0184]

[0185] The aspheric coefficients of the second lens 120 and the seventh lens 240 of Example 3 disclosed in this application are shown in Table 8 below:

[0186] Table 8

[0187]

[0188] The main parameters of the optical module of Example 3 disclosed in this application are shown in Table 9 below:

[0189] Table 9

[0190]

[0191] In Example 3, the FNO is 1.85 and the FOV is 140°. The FOV in Example 3 is larger than that in Example 2 to achieve a wider field of view. Furthermore, the aperture in Example 3 is slightly smaller than that in Example 2.

[0192] Based on the data in Tables 7 to 9, Figure 12 The figure shows the MTF curve of the optical module. The MTF curve refers to the relationship between the modulation degree and the number of line pairs per millimeter in the image, which is used to evaluate the ability to restore the details of the scene. Figure 12 It can be seen that the MTF value of the central field of view of the optical module is as high as 0.6 at a field frequency of 230 lp / mm, and the MTF value of the maximum field of view at a field frequency of 100 lp / mm is also above 0.5. The optical module provided in this embodiment 3 has high resolution and good imaging quality.

[0193] Based on the data in Tables 7 to 9, Figure 13 The figure shows the point diagram of the optical module. After many light rays emitted from one point pass through the optical system, due to aberration, their intersection with the image plane is no longer concentrated at the same point, but forms a diffuse pattern spread over a certain range, which is called a point diagram. Figure 13It can be seen that the maximum diameter of the point diagram in the optical module provided in this embodiment 3 is 3.7 μm, the light diffusion range is small, and the imaging quality is good.

[0194] Based on the data in Tables 7 to 9, Figure 14 The figure shows the field curvature distortion curve of the optical module. Field curvature refers to the curvature of the image field, which is mainly used to indicate the degree of non-coincidence between the intersection of the entire light beam and the ideal image point in the optical module. Distortion refers to the aberration of different magnifications of different parts of an object when it is imaged through a projection lens. Distortion will cause the similarity of the object and image to deteriorate, but will not affect the clarity of the image. Figure 14 It can be seen that the field curvature of the spot diagram of the optical module provided in this embodiment 3 is less than 0.02 mm, and the optical distortion is less than -40%, which meets the viewing requirements of the human eye.

[0195] Based on the data in Tables 7 to 9, Figure 15 The vertical axis chromatic aberration curve of the optical module is shown in the figure. Vertical axis chromatic aberration is also called magnification chromatic aberration, which mainly refers to the difference between the focal positions of hydrogen blue light and hydrogen red light on the image plane when a complex main light ray is transformed into multiple light rays due to the dispersion of the refractive system. Figure 15 It can be seen that the vertical axis chromatic aberration of the optical module provided in this embodiment 3 is less than 4.2 μm, the imaging smear degree is extremely low, and the imaging quality is good.

[0196] An embodiment of the present application further provides a head-mounted display device, which includes a body and an optical module as shown above, and the optical module is arranged inside the head-mounted display device.

[0197] The specific structure of the optical module can be found in the above embodiments.

[0198] Since the head-mounted display device of the present application adopts the optical modules of all the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be described one by one here.

[0199] 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.

[0200] Although some specific embodiments of the present application have been described in detail by way of examples, 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 embodiments 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 lens system includes, from the object side to the image side, a first lens group (100), a reflective element (400), a third lens (300), an aperture (500), and a second lens group (200), wherein: The reflective element (400) includes a reflective surface (410); The first lens group (100) is arranged along a first optical axis, and the first lens group (100) is composed of a first lens (110) and a second lens (120) arranged in sequence from the object side to the image side, the optical power of the first lens (110) is negative, and the optical power of the second lens (120) is negative; The third lens (300) and the second lens group (200) are arranged along the second optical axis, the second lens group (200) is composed of a fourth lens (210), a fifth lens (220), a sixth lens (230), and a seventh lens (240) arranged in sequence from the object side to the image side, the fourth lens (210) has a positive optical power, the fifth lens (220) has a negative optical power, the sixth lens (230) has a positive optical power, and the seventh lens (240) has a positive optical power; The optical power of the third lens (300) is positive, and the third lens (300) is a biconvex spherical lens; The distance from the first lens (110) to the center of the reflecting surface (410) is T1, the distance from the center of the reflecting surface (410) to the image side is T2, the ratio of T2 to T1 satisfies: 1.2<T2 / T1<1.6, the maximum field of view angle of the optical module is FOV, the total optical length of the optical module is TTL, and the ratio of FOV to TTL satisfies: 3<FOV / TTL<5.

2. The optical module according to claim 1, wherein: The first lens (110) is a meniscus spherical lens.

3. The optical module according to claim 2, wherein: The refractive index N of the first lens (110) d1 >1.65, the Abbe number V of the first lens (110) d1 >45.

4. The optical module according to any one of claims 1 to 3, characterized in that: The reflective element (400) is located between the second lens (120) and the third lens (300); The second lens (120) is a meniscus aspheric lens.

5. The optical module according to claim 4, wherein: The Abbe number V of the second lens (120) d2 >50.

6. The optical module according to claim 1, wherein: The reflective element (400) is a right-angle prism, and the reflective element (400) further includes an incident surface (420) and an exit surface (430) that are perpendicular to each other, and the reflective surface (410) is tilted. The incident surface (420) is perpendicular to the first optical axis, the exit surface (430) is perpendicular to the second optical axis, and the center of the reflective surface (410) is located at the intersection of the first optical axis and the second optical axis.

7. The optical module according to claim 4, wherein: The focal length of the second lens (120) is F2, the effective focal length of the optical module is EFL, and the ratio of F2 to EFL satisfies: -3.6<F2 / EFL<-2.

4.

8. The optical module according to claim 1, wherein: The refractive index N of the third lens (300) d3 >1.7, the Abbe number V of the third lens (300) d3 <30.

9. The optical module according to claim 1, wherein: The optical power of the second lens group (200) is positive; The aperture (500) is located between the third lens (300) and the fourth lens (210); The fourth lens (210) and the fifth lens (220) are glued together to form a glued lens group, and the glued lens group has positive optical power.

10. The optical module according to claim 9, wherein: The fourth lens (210) is a biconvex spherical lens, and the Abbe number V of the fourth lens (210) is d4 >50; The fifth lens (220) is a spherical lens, and the refractive index N of the fifth lens (220) is d5 >1.7, the Abbe number V of the fifth lens (220) d5 <30.

11. The optical module according to claim 1, wherein: The sixth lens (230) is a spherical lens.

12. The optical module according to claim 1, wherein: The seventh lens (240) is a meniscus aspheric lens.

13. The optical module according to claim 1, wherein: The Abbe number V of the sixth lens (230) d6 >45, the Abbe number V of the seventh lens (240) d7 >40.

14. The optical module according to claim 1, wherein: The optical module further comprises a filter element (700), and the filter element (700) is located between the second lens group (200) and the image side (600).

15. The optical module according to claim 1, wherein: The aperture value FNO of the optical module is ≤2.

0.

16. A head-mounted display device, characterized in that: The optical module comprises any one of claims 1-15.

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