Optical system and augmented reality device
By using a combination of three aspheric lenses, the problem of large volume caused by the large number of lenses in augmented reality devices is solved, the device is made lighter and the imaging quality is improved, thereby improving the user experience.
Patent Information
- Application Number
- CN202422809467.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-18
- Publication Date
- 2025-10-21
- Estimated Expiration
- 2034-11-18
AI Technical Summary
The large number of lenses in existing augmented reality devices results in a larger effective diameter of the optical system and a larger device size, affecting the user experience.
Three aspheric lenses are used, including two plastic and one glass, designed as a combination of positive and negative optical power, to optimize the optical system to reduce the number of lenses and reduce the size.
The lightweighting of augmented reality devices and the improvement of imaging quality have been achieved, thus improving the user experience.
Smart Images
Figure CN223461741U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to the field of imaging display technology, especially to an optical system and an augmented reality device. BACKGROUND
[0002] Wearable devices are a new development direction in the field of photoelectric imaging, and augmented reality devices as wearable devices are gradually developing towards lightness and miniaturization.
[0003] In the augmented reality device using an optical waveguide, at least four lenses are usually used to adjust the optical path of the optical system to ensure the imaging quality of the augmented reality device. Since the display unit and the optical system are mainly concentrated in the augmented reality device worn by the user, when there are many lenses, the effective diameter of the optical system is likely to be too large, and the volume of the augmented reality device is likely to be too large, which deviates the overall experience of the user. UTILITY MODEL CONTENT
[0004] Therefore, the utility model embodiment provides an optical system and an augmented reality device, which can meet the imaging quality and reduce the volume by using three aspheric lenses, and effectively realize the lightness of the augmented reality device.
[0005] In a first aspect, the utility model embodiment further provides an optical system, which comprises a display unit, a first lens, a second lens and a third lens in sequence along the light transmission direction.
[0006] Two of the first lens, the second lens and the third lens are made of plastic, and the other one is made of glass.
[0007] The first lens, the second lens and the third lens are all aspheric lenses.
[0008] The first lens and the third lens have positive focal power, and the second lens has negative focal power.
[0009] The refractive index of the first lens, the second lens and the third lens is 1.4-2.0, the Abbe number of the first lens and the second lens is 20-40, and the Abbe number of the third lens is 50-80.
[0010] Optionally, the refractive index of the first lens is 1.65, and the Abbe number is 21.5.
[0011] The refractive index of the second lens is 1.65, and the Abbe number is 21.5.
[0012] The refractive index of the third lens is 1.62, and the Abbe number is 63.85.
[0013] Optionally, the first lens and the second lens are made of plastic material, and the third lens is made of glass material.
[0014] Optionally, the light entrance surface of the first lens is a convex structure, and the light exit surface of the first lens is a convex structure.
[0015] The light entrance surface of the second lens is a convex structure, and the light exit surface of the second lens is a concave structure.
[0016] The light entrance surface of the third lens is a convex structure, and the light exit surface of the third lens is a convex structure.
[0017] Optionally, the focal length f1 of the first lens satisfies 6mm < f1 < 10mm.
[0018] The focal length f2 of the second lens satisfies -5mm < f2 < -1mm.
[0019] The focal length f3 of the third lens satisfies 2mm < f3 < 6mm.
[0020] Optionally, the effective diameter of the first lens, the second lens and the third lens ranges from 3.7mm to 4mm.
[0021] Optionally, the total length of the optical system is less than or equal to 5.5mm, the effective diameter of the optical system is less than 4mm, and the total effective focal length f of the optical system satisfies 5.5mm < f < 6.5mm.
[0022] Optionally, the display unit is one of a micro light emitting diode, an organic light emitting diode, a liquid crystal display and a silicon-based liquid crystal display.
[0023] Optionally, the optical system further comprises a diaphragm, and the diaphragm is arranged on the light exit side of the third lens.
[0024] In a second aspect, the utility model embodiment further provides an augmented reality device, the augmented reality device includes the optical system and the shell as described in the first aspect, and the optical system is arranged in the shell.
[0025] The utility model embodiment provides an optical system and an augmented reality device, and three aspheric lenses are used to meet the imaging quality and the volume reduction requirement, so that the light weight of the augmented reality device is effectively realized, and the user experience is improved. BRIEF DESCRIPTION OF DRAWINGS
[0026] The above and other objects, features and advantages of the utility model will become more apparent from the following description of the utility model embodiments with reference to the accompanying drawings, in which:
[0027] Figure 1is a structural schematic diagram of an optical system of an embodiment of the utility model;
[0028] Figure 2 is a modulation transfer function diagram of an optical system of an embodiment of the utility model;
[0029] Figure 3 is a relative luminance diagram of an optical system of an embodiment of the utility model;
[0030] Figure 4 is a defocus curve diagram of an optical system of an embodiment of the utility model.
[0031] Reference signs:
[0032] 1 - display unit;2 - first lens;3 - second lens;4 - third lens;5 - diaphragm. DETAILED DESCRIPTION
[0033] The present application is described below based on embodiments, but the present application is not limited to only these embodiments. In the following detailed description of the present application, some specific details are described in detail. The present application can also be fully understood without the description of these details by those skilled in the art. In order to avoid confusion of the essence of the present application, well-known methods, processes, procedures, elements and circuits are not described in detail.
[0034] In addition, those of ordinary skill in the art should understand that the drawings provided herein are for illustrative purposes only and the drawings are not necessarily drawn to scale.
[0035] Unless otherwise explicitly defined and limited, the terms "mounting", "connecting", "connecting", "fixing" and the like should be broadly understood, for example, can be fixedly connected, or can be detachably connected, or can be integrated; can be mechanically connected, or can be electrically connected; can be directly connected, or can be indirectly connected through an intermediate medium, can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited. For those of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.
[0036] Unless the context clearly requires otherwise, the terms "including", "including", and the like in the entire application should be interpreted as having an inclusive meaning rather than an exclusive or exhaustive meaning; that is, as "including but not limited to".
[0037] In the description of the present application, it should be understood that the terms "first", "second" and the like are only for the purpose of description, and cannot be understood as indicating or implying relative importance. In addition, in the description of the present application, unless otherwise stated, the meaning of "multiple" is two or more.
[0038] In the drawings, the thickness, size and shape of the lenses have been exaggerated slightly for ease of explanation. Specifically, the shape of the aspheric surface shown in the drawings is shown by way of example. That is, the shape of the aspheric surface is not limited to the shape of the aspheric surface shown in the drawings. The drawings are merely examples and are not drawn strictly to scale. The surface of each lens closest to the display unit is referred to as the entrance surface of the lens, and the surface of each lens closest to the imaging surface is referred to as the exit surface of the lens.
[0039] Figure 1 is a schematic diagram of the structure of the optical system of the present embodiment. Referring to Figure 1 As shown, the optical system includes the display unit 1, the first lens 2, the second lens 3 and the third lens 4 in order along the direction of light transmission. The light emitted by the display unit 1 passes through the first lens 2, the second lens 3 and the third lens 4 in order and then exits the optical system and is transmitted to the human eye.
[0040] In order to reduce the number of lenses used in the optical system, the first lens 2, the second lens 3 and the third lens 4 are all aspheric lenses with a refractive index of 1.4-2.0. This can reduce the number of lenses in the optical system while ensuring the imaging quality of the optical system, thereby enabling the device to be miniaturized and lightened. The aspheric lens has the characteristic that the curvature continuously changes from the center of the lens to the periphery of the lens. Unlike a spherical lens having a constant curvature from the center of the lens to the periphery of the lens, the aspheric lens has better curvature radius characteristics and has the advantages of improving the distortion aberration and improving the astigmatism aberration. The use of the aspheric lens can eliminate the aberration that occurs during imaging as much as possible, thereby improving the imaging quality and shortening the total length of the entire optical system.
[0041] Specifically, the first lens 2 and the third lens 4 have positive focal power, and the second lens 3 has negative focal power. The combination of the first lens 2 and the third lens 4 enables the optical system to have high imaging quality and a small number of lenses, thereby solving the problem of a large volume caused by a large number of lenses in the projection device in the prior art.
[0042] In the present embodiment, the Abbe number of the first lens 2 and the second lens 3 is 20-40, and the Abbe number of the third lens 4 is 50-80. The dispersion coefficient is an important index for measuring the imaging quality of a lens and is usually expressed by the Abbe number. The greater the dispersion coefficient, the less obvious the dispersion, and the better the imaging quality of the lens. The smaller the dispersion coefficient, the more obvious the dispersion, and the poorer the imaging quality of the lens. Generally, the dispersion coefficient is inversely proportional to the refractive index of the lens, that is, the greater the refractive index, the smaller the dispersion coefficient, and the more obvious the dispersion.
[0043] In an optional embodiment, the refractive indexes of the first lens 2 and the second lens 3 can be equal, and the Abbe numbers can also be equal. For example, the refractive index of the first lens 2 is 1.65, and the Abbe number of the first lens 2 is 21.5; the refractive index of the second lens 3 is 1.65, and the Abbe number of the second lens 3 is 21.5; the refractive index of the third lens 4 is 1.62, and the Abbe number of the third lens 4 is 63.85. The refractive index refers to the ratio of the propagation speed of light in vacuum to the propagation speed of light in the medium. The higher the refractive index of the material, the stronger the ability to refract incident light.
[0044] Among the first lens 2, the second lens 3 and the third lens 4, two lenses are made of plastic material, and the other lens is made of glass material, and the surface shape is aspherical. The lenses are made of a mixture of glass and plastic, so that the optical system has good thermal stability, can effectively reduce the temperature drift, and improve the performance and reliability of the equipment. The temperature drift refers to the phenomenon that the performance parameters of electronic components or systems deviate when the temperature changes.
[0045] In an optional embodiment, the first lens 2 and the second lens 3 are made of plastic material, and the third lens 4 is made of glass material.
[0046] In an optional embodiment, the light entrance surface S1 of the first lens 2 is a convex structure, and the light exit surface S2 of the first lens 2 is a convex structure; the light entrance surface S3 of the second lens 3 is a convex structure, and the light exit surface S4 of the second lens 3 is a concave structure; the light entrance surface S5 of the third lens 4 is a convex structure, and the light exit surface S6 of the third lens 4 is a convex structure.
[0047] In an optional embodiment, the focal length f1 of the first lens 2 satisfies: 6mm < f1 < 10mm; the focal length f2 of the second lens 3 satisfies: -5mm < f2 < -1mm; and the focal length f3 of the third lens 4 satisfies: 2mm < f3 < 6mm. The effective diameter of the first lens 2, the second lens 3 and the third lens 4 ranges from 3.7mm to 4mm. The effective diameter of the optical system is <4mm, the total effective focal length f of the optical system satisfies: 5.5mm < f < 6.5mm; and the total length of the optical system is ≤5.5mm, which greatly reduces the volume and weight of the equipment and improves the user experience.
[0048] In an optional embodiment, the display unit 1 is one of a micro light emitting diode, an organic light emitting diode, a liquid crystal display and a silicon-based liquid crystal display. It can be understood that the display unit 1 is not limited to this, and in other embodiments, the display unit 1 can also be a light emitting diode or a mini light emitting diode or a laser light source of different wavelengths or other light sources capable of emitting light beams.
[0049] In an optional embodiment, the optical system can further include a mirror and a protective glass, which are not shown in the figure. The mirror can be arranged between the display unit 1 and the first lens 2, and can deflect the light in the optical system to reduce the overall length of the optical system. The structure and form of the mirror are not limited, as long as the light is deflected. The protective glass can be arranged between the display unit 1 and the first lens 2, and is used to protect the display unit 1 from being affected by the impact of the external environment or other elements.
[0050] As shown in Figure 1 , the optical system further includes a diaphragm 5 arranged on the light-emitting side of the third lens 4. The light emitted by the display unit 1 passes through the first lens 2, the second lens 3, and the third lens 4 once, and then is emitted from the diaphragm 5 out of the optical system and transmitted to the human eye.
[0051] In an optional embodiment, Table 1 shows a basic parameter table of each lens in the optical system, wherein the units of the curvature radius and the thickness are millimeters (mm).
[0052] Table 1
[0053]
[0054] The light-in surface and the light-out surface of any one of the first lens 2 to the third lens 4 are even aspheric surface types, which satisfy the following aspheric surface formula:
[0055]
[0056] wherein z is the distance from the vertex of the aspheric surface when the aspheric surface is along the optical axis at a height of Y; Y is the center height of the lens; c is the paraxial curvature of the aspheric surface, c = 1 / R (i.e., the paraxial curvature c is the inverse of the curvature radius R in Table 1 above); k is the conic coefficient; a i is the i-th aspheric correction coefficient.
[0057] Table 2 below shows the conic coefficients k and the high-order term coefficients a4, a6, and a8 of S1-S6 of the first lens 2 to the third lens 4.
[0058] Table 2
[0059]
[0060]
[0061] Figure 2is a modulation transfer function diagram of the optical system of the embodiment, wherein the modulation transfer function (MTF) refers to the relationship between the modulation degree and the logarithm of the line per millimeter in the image, can quantify the contrast transfer capability of the system at different spatial frequencies, and evaluate the resolution and contrast of the optical system. By optimizing the MTF, the resolution and contrast of the system can be improved, so as to obtain higher quality images. Figure 2 It can be seen from the above that the MTF values of the optical system of the embodiment in each field of view are all greater than 0.7.
[0062] Figure 3 is a relative luminance diagram of the optical system of the embodiment, wherein the relative luminance refers to the ratio of the illuminance of different coordinate points in the image plane to the illuminance of the center point, and is used to evaluate the light uniformity of the lens or other optical elements at different positions. The relative luminance of the embodiment is greater than 0.76.
[0063] Figure 4 is a defocus curve diagram of the optical system of the embodiment, and the defocus curve represents the change of the MTF when the image plane deviates from the design value, and is used to evaluate the focal depth and out-of-focus imaging quality of the optical system.
[0064] The embodiment uses three aspherical lenses to meet the requirements of imaging quality and volume reduction, effectively realizes the lightweight of the augmented reality device, and improves the user experience.
[0065] The embodiment also provides an augmented reality device, which comprises the optical system according to any one of the above embodiments and a shell, and the optical system is arranged in the shell. Since the optical system adopts all the technical solutions of the above embodiments, it at least has all the beneficial effects brought by the technical solutions of the above embodiments, which will not be repeated here.
[0066] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.
Claims
1. An optical system characterized by comprising: The optical system comprises, in sequence along the light transmission direction, a display unit (1), a first lens (2), a second lens (3) and a third lens (4). Two of the first lens (2), the second lens (3) and the third lens (4) are made of plastic, and the other one is made of glass. The first lens (2), the second lens (3) and the third lens (4) are all aspherical lenses. The first lens (2) and the third lens (4) have positive focal power, and the second lens (3) has negative focal power. The refractive index of the first lens (2), the second lens (3) and the third lens (4) is 1.4-2.0, the Abbe number of the first lens (2) and the second lens (3) is 20-40, and the Abbe number of the third lens (4) is 50-80.
2. The optical system of claim 1, wherein The refractive index of the first lens (2) is 1.65, and the Abbe number of the first lens (2) is 21.
5. The refractive index of the second lens (3) is 1.65, and the Abbe number of the second lens (3) is 21.
5. The refractive index of the third lens (4) is 1.62, and the Abbe number of the third lens (4) is 63.
85.
3. The optical system of claim 1, wherein The first lens (2) and the second lens (3) are both made of plastic, and the third lens (4) is made of glass.
4. The optical system of claim 1, wherein The light entrance surface of the first lens (2) is a convex structure, and the light exit surface of the first lens (2) is a convex structure. The light entrance surface of the second lens (3) is a convex structure, and the light exit surface of the second lens (3) is a concave structure. The light entrance surface of the third lens (4) is a convex structure, and the light exit surface of the third lens (4) is a convex structure.
5. The optical system of claim 1, wherein The focal length f1 of the first lens (2) satisfies 6mm < f1 < 10mm. The focal length f2 of the second lens (3) satisfies -5mm < f2 < -1mm. The focal length f3 of the third lens (4) satisfies 2mm < f3 < 6mm.
6. The optical system of claim 1, wherein The effective diameter of the first lens (2), the second lens (3) and the third lens (4) ranges from 3.7mm to 4mm.
7. The optical system of claim 1, wherein The total length of the optical system is ≤5.5mm, the effective diameter of the optical system is <4mm, and the total effective focal length f of the optical system satisfies 5.5mm < f < 6.5mm.
8. The optical system of claim 1, wherein, The display unit (1) is one of a micro light emitting diode, an organic light emitting diode, a liquid crystal display and a silicon-based liquid crystal display.
9. The optical system of claim 1, wherein, The optical system further comprises a diaphragm (5) arranged on the light exit side of the third lens (4).
10. An augmented reality device, characterized by The augmented reality device comprises the optical system and a housing, and the optical system is arranged in the housing. The augmented reality device comprises the optical system and a housing, and the optical system is arranged in the housing.