Eye movement tracking lens optical system and AR / VR device

Abstract

The application discloses an eye movement tracking lens optical system and an AR / VR device. The eye movement tracking lens optical system comprises, in sequence along the optical axis direction from the object side to the image side, a first lens with a negative focal length, a second lens with a positive focal length, a third lens with a positive focal length, and a fourth lens with a negative focal length. The optical system satisfies the following conditional expressions: 1.8<=|f1| / F<=2.5; 0.8<=|f2| / F<=1.0; 3.5<=|f3| / F<=4.0; 4.0<=|f4| / F<=6.0; 1.6mm<=TTL<=1.7mm; wherein f1, f2, f3 and f4 represent the focal lengths of the lenses; F represents the focal length of the optical system; and TTL represents the distance on the optical axis from the object side of the first lens to the image side. The application reduces the total length of the optical system by reasonably matching the focal length proportion of the lenses through the mutual combination of the lenses and the mutual compensation of the positive and negative focal lengths of the lenses.

Description

Technical Field

[0001] The present application relates to the field of optical lenses, and in particular to an eye-tracking lens optical system and AR / VR equipment. Background Art

[0002] With the development of AR / VR technology, more and more AR / VR smart devices will add eye tracking functions to help users obtain the relative position of virtual objects and feel the depth information of objects, so as to provide users with a better interactive experience and immersion in AR / VR smart devices. AR / VR technology can also be used for target recognition, identity authentication, health detection, social interaction, multi-person collaboration, etc.; eye tracking technology can cover every aspect of the use of AR / VR smart devices, so eye tracking technology is crucial to the development of AR / VR smart devices. However, the existing eye tracking optical solutions have the problem of a large total lens length. Taking the Quest pro eye tracking lens as an example, its total optical system length (TTL) is greater than 2mm, which takes up more space in the entire device and is not conducive to the miniaturization of the entire device. Summary of the Invention

[0003] This application discloses an eye-tracking lens optical system and AR / VR equipment, which can effectively shorten the total length of the optical system and solve the problem of large lens space occupation.

[0004] To achieve the above objectives, this application provides the following technical solutions:

[0005] An eye tracking lens optical system comprises, from the object side to the image side, a first lens having a negative focal length, a second lens having a positive focal length, a third lens having a positive focal length, and a fourth lens having a negative focal length, in order from the object side to the image side along the optical axis;

[0006] The optical system satisfies the following conditional formula:

[0007] 1.8≤|f1| / F≤2.5;

[0008] 0.8≤|f2| / F≤1.0;

[0009] 3.5≤|f3| / F≤4.0;

[0010] 4.0≤|f4| / F≤6.0;

[0011] 1.6mm≤TTL≤1.7mm;

[0012] Wherein, f1 represents the focal length of the first lens, f2 represents the focal length of the second lens, f3 represents the focal length of the third lens, f4 represents the focal length of the fourth lens, F represents the focal length of the optical system, and TTL represents the distance from the object side to the image side of the first lens on the optical axis.

[0013] The above-mentioned eye tracking lens optical system includes a first lens, a second lens, a third lens and a fourth lens arranged in sequence. Specifically, light is emitted from the object side, passes through the first lens, the second lens, the third lens and the fourth lens, and finally reaches the image side, and finally forms an image after processing. Among them, the first lens has a negative focal length, the second lens has a positive focal length, the third lens has a positive focal length, and the fourth lens has a negative focal length, that is, a negative-positive-positive-negative optical path structure is adopted, so that the light first diverges and then converges twice, and finally diverges again. Through the reasonable distribution and regular combination of the positive and negative focal lengths of the lenses, the spherical aberration caused by the irregular combination of the focal lengths of the lenses can be eliminated, the sensitivity can be reduced, and the clarity of the entire optical system can be improved. Secondly, by reasonably matching the focal lengths of the lenses so that the focal lengths of each lens meet the conditional formula, the total length of the optical system can be reduced to 1.6mm-1.7mm, which is conducive to saving the stacking space of the whole machine and making the optical system have a relatively compact structure, so as to realize the miniaturization design of the whole machine. The present application reduces the total length of the optical system by combining the first lens, the second lens, the third lens, and the fourth lens, rationally matching the focal length ratios of the four lenses, and compensating the positive and negative focal lengths of the four lenses.

[0014] In some embodiments, the optical system further includes a stop disposed between the first lens and the second lens.

[0015] By placing the iris between the first and second lenses, light emanating from the object side first passes through the first lens, then the iris aperture, and finally the second lens. Compared to placing the iris before the first lens, this effectively reduces lens distortion, eliminating the need for post-processing algorithms to correct distortion and lowering algorithm requirements. This central iris reduces the difficulty of correcting optical system distortion, ensures optical structural stability, and improves the imaging quality of the optical system.

[0016] In some embodiments, each lens has an object-side surface and an image-side surface, and both the object-side surface and the image-side surface are aspherical surfaces;

[0017] The object side surface of the first lens is convex at the near optical axis, and the image side surface is concave at the near optical axis;

[0018] The object side surface of the second lens is convex at the near optical axis, and the image side surface is convex at the near optical axis;

[0019] The object side surface of the third lens is convex at the near optical axis, and the image side surface is convex at the near optical axis;

[0020] The object side surface of the fourth lens is concave at the near optical axis, and the image side surface is concave at the near optical axis.

[0021] The object side surface of the first lens is convex at the near optical axis, and the image side surface is concave at the near optical axis, so that the light emitted from the object side is first diverged. In conjunction with the subsequent lens, the imaging effect can be improved to better meet the observation needs; the object side surfaces of the second and third lenses are convex at the near optical axis, and the image side surfaces are convex at the near optical axis. By converging the light, aberrations can be reduced and clarity can be improved; the object side surface of the fourth lens is concave at the near optical axis, and the image side surface is concave at the near optical axis, so that the light is diverged, meeting the imaging needs and helping to reduce the total length of the optical system. The lenses of the optical system of the present application use aspherical lenses and adopt different combinations of surface shapes to make the optical system have better imaging effects and improve user experience.

[0022] In some embodiments, the optical system further comprises a parallel plate, wherein the parallel plate is disposed between the fourth lens and the image side;

[0023] The optical system also satisfies the following conditional formula:

[0024] 0.2≤CT1 / ∑CT≤0.25;

[0025] 0.2≤CT2 / ∑CT≤0.23;

[0026] 0.19≤CT3 / ∑CT≤0.26;

[0027] 0.12≤CT4 / ∑CT≤0.15;

[0028] Wherein, CT1, CT2, CT3, and CT4 represent the center thicknesses of the first lens, the second lens, the third lens, and the fourth lens on the optical axis, respectively, and ΣCT represents the sum of the center thicknesses of the first lens, the second lens, the third lens, the fourth lens, and the parallel plate on the optical axis.

[0029] By satisfying the constraints of the conditional formula and rationally configuring the thicknesses of the first lens, the second lens, the third lens, and the fourth lens, it is beneficial to correct aberrations and compensate for each other, which can reduce the sensitivity of the lens and reduce the difficulty of the molding process. At the same time, it is beneficial to reduce the overall length of the optical system and achieve ultra-thin and miniaturized lenses.

[0030] In some embodiments, the air distance between the object side and the first lens on the optical axis is 20 mm;

[0031] The air distance between the first lens and the second lens on the optical axis is 0.15mm-0.192mm;

[0032] The air distance between the second lens and the third lens on the optical axis is 0.02mm-0.05mm;

[0033] The air distance between the third lens and the fourth lens on the optical axis is 0.05mm-0.052mm;

[0034] An air distance between the fourth lens and the image side on the optical axis is 0.561 mm-0.6 mm.

[0035] By meeting the limits of each range and rationally configuring the distances between adjacent lenses in the first, second, third, and fourth lenses, the overall length of the optical system is reduced, leading to a more compact lens. Furthermore, the air distance between the fourth lens and the image side on the optical axis is the optical back focus. A larger optical back focus improves the adaptability of the optical system while also meeting the wearing needs of different users.

[0036] In some embodiments, the optical system further satisfies the following conditional formula:

[0037] 8.11≤R12-R11≤21.06;

[0038] -4.90≤R22-R21≤-4.35;

[0039] 2849.39≤R32-R31≤256298.39;

[0040] -10.99≤R42-R41≤-10.46;

[0041] Among them, R11, R12, R31, and R41 respectively represent the curvature radii of the object side surfaces of the first lens, the second lens, the third lens, and the fourth lens, and R21, R22, R32, and R42 respectively represent the curvature radii of the image side surfaces of the first lens, the second lens, the third lens, and the fourth lens.

[0042] By satisfying the constraints of the conditional expression, the curvature radii of the object-side surface and the image-side surface of the first lens, the second lens, the third lens, and the fourth lens are reasonably configured to achieve a good imaging effect.

[0043] In some embodiments, the first lens, the second lens, the third lens, the fourth lens, and the parallel plate are made of plastic.

[0044] The lens of the present application is made of all-plastic material, which has low processing cost and is conducive to achieving a lightweight design of the entire device compared to all-glass material.

[0045] In some embodiments, the refractive index of the first lens and the second lens is 1.544, the refractive index of the third lens is 1.64, and the refractive index of the fourth lens is 1.66;

[0046] Alternatively, the Abbe number of the first lens and the second lens is 56, the Abbe number of the third lens is 23.5, and the Abbe number of the fourth lens is 20.4.

[0047] By adopting a combination of low-low-high-high refractive index, or high-high-low-low Abbe number, chromatic aberration can be effectively eliminated and image quality can be improved.

[0048] In some embodiments, the maximum full field of view of the eye tracking lens optical system is 97°-103°.

[0049] By meeting the field of view angle range limit, the optical system can achieve an effect close to the human eye's field of view, provide a larger eye movement range, and bring an immersive sensory experience to users.

[0050] In some embodiments, the aperture of the eye tracking lens optical system is 1.9-2.1.

[0051] The aperture range of the optical system of the present application is relatively small, and a small aperture is beneficial for improving image quality and overall brightness, and reducing aberrations and chromatic aberrations.

[0052] The present application also provides an AR / VR device, including the eye-tracking lens optical system, which has good imaging quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 This is a schematic diagram of the structure of the eye tracking lens optical system according to an embodiment of the present application;

[0054] Figure 2 This is a schematic structural diagram of the eye tracking lens optical system according to the first embodiment of the present application;

[0055] Figure 3 This is a distortion curve diagram of the first embodiment of the present application;

[0056] Figure 4 This is a full-screen image quality diagram of the first embodiment of this application;

[0057] Figure 5 This is a half-screen image quality diagram of the first embodiment of the present application;

[0058] Figure 6 This is a schematic structural diagram of the eye tracking lens optical system according to the second embodiment of the present application;

[0059] Figure 7 This is a distortion curve diagram of the second embodiment of the present application;

[0060] Figure 8 This is a full-screen image quality diagram of the second embodiment of this application;

[0061] Figure 9This is a half-screen image quality diagram of the second embodiment of the present application. DETAILED DESCRIPTION

[0062] The following will clearly and completely describe the technical solutions in the embodiments of the present application in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. Among them, in the description of the embodiments of the present application, unless otherwise specified, " / " means or, for example, A / B can mean A or B; "and / or" in the text is only a description of the association relationship of associated objects, indicating that there can be three relationships, for example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, in the description of the embodiments of the present application, "multiple" refers to two or more than two.

[0063] In the following, the terms "first" and "second" are used for descriptive purposes only and should not be understood to imply or suggest relative importance or implicitly indicate the number of the technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of this application, unless otherwise specified, "plurality" means two or more.

[0064] First, refer to Figure 1 The present invention provides an eye-tracking lens optical system, which includes, from object side A to image side B along the optical axis, a first lens 1 with a negative focal length, a second lens 2 with a positive focal length, a third lens 3 with a positive focal length, and a fourth lens 4 with a negative focal length.

[0065] The optical system satisfies the following conditions:

[0066] 1.8≤|f1| / F≤2.5;

[0067] 0.8≤|f2| / F≤1.0;

[0068] 3.5≤|f3| / F≤4.0;

[0069] 4.0≤|f4| / F≤6.0;

[0070] 1.6mm≤TTL≤1.7mm;

[0071] Wherein, f1 represents the focal length of the first lens 1, f2 represents the focal length of the second lens 2; f3 represents the focal length of the third lens 3; f4 represents the focal length of the fourth lens 4; F represents the focal length of the optical system; TTL represents the distance from the object side surface S1 of the first lens 1 to the image side surface B on the optical axis. That is, |f1| / F can be any value in the range of [1.8, 2.5], for example, the values ​​can be 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, etc.; |f2| / F can be any value in the range of [0.8, 1.0], for example, the values ​​can be 0.8, 0.836, 0.864, 0.885, 0.917, 0.939, 0.978, 1.0, etc.; |f3| / F can be any value in the range of [3.5, 4.0], for example, the value can be 3. 5, 3.25, 3.67, 3.75, 3.82, 3.92, 4.0, etc.; |f4| / F can be any value in the range of [4.0, 6.0], for example, 4.0, 4.27, 4.69, 4.91, 5.13, 5.48, 5.82, 6.0, etc.; TTL can be any value in the range of [1.6mm, 1.7mm], for example, 1.6mm, 1.624mm, 1.659mm, 1.682mm, 1.698mm, 1.7mm, etc.

[0072] The eye-tracking lens optical system includes a first lens 1, a second lens 2, a third lens 3, and a fourth lens 4, arranged in sequence. Specifically, light is emitted from the object side A, passes through the first lens 1, the second lens 2, the third lens 3, and the fourth lens 4, and finally reaches the image side B, where it is processed to form an image. The first lens 1 has a negative focal length, the second lens 2 has a positive focal length, the third lens 3 has a positive focal length, and the fourth lens 4 has a negative focal length. This employs a negative-positive-positive-negative optical path structure, causing the light to first diverge, then converge twice, and finally diverge again. By rationally allocating and regularly combining the positive and negative focal lengths of the lenses, spherical aberration caused by irregular lens focal length combinations can be eliminated, reducing sensitivity and improving the clarity of the entire optical system. Secondly, by rationally matching the focal lengths of the lenses so that the focal lengths of each lens meet the constraints of the conditional formula, the total length of the optical system can be reduced to 1.6mm-1.7mm, which helps save stacking space for the entire device and gives the optical system a relatively compact structure, thereby achieving a miniaturized design for the entire device. The present application reduces the total length of the optical system by combining the first lens 1, the second lens 2, the third lens 3 and the fourth lens 4, reasonably matching the focal length ratios of the four lenses, and compensating the positive and negative focal lengths of the four lenses.

[0073] In some embodiments, the optical system further includes an aperture 5 , which is disposed between the first lens 1 and the second lens 2 .

[0074] By placing aperture 5 between first lens 1 and second lens 2, light emanating from object side A first passes through first lens 1, then aperture 5, and finally through second lens 2. Compared to placing aperture 5 before first lens 1, this effectively reduces lens distortion, eliminating the need for post-processing algorithmic distortion correction and lowering algorithmic requirements. In other words, the central placement of aperture 5 reduces the difficulty of correcting optical system distortion, ensures optical structural stability, and improves the imaging quality of the optical system.

[0075] In some embodiments, each lens has an object-side surface and an image-side surface, and both the object-side surface and the image-side surface are aspherical;

[0076] The object-side surface S1 of the first lens 1 is convex near the optical axis, and the image-side surface S2 is concave near the optical axis;

[0077] The object-side surface S3 of the second lens element 2 is convex near the optical axis, and the image-side surface S4 is convex near the optical axis;

[0078] The object-side surface S5 of the third lens element 3 is convex near the optical axis, and the image-side surface S6 is convex near the optical axis.

[0079] The object-side surface S7 of the fourth lens element 4 is concave near the optical axis, and the image-side surface S8 is concave near the optical axis.

[0080] The object side surface S1 of the first lens 1 is convex at the near optical axis, and the image side surface S2 is concave at the near optical axis, so that the light emitted from the object side A is first diverged, which can improve the imaging effect when combined with the subsequent lenses and better meet the observation needs; the object side surfaces S3 and S5 of the second lens 2 and the third lens 3 are convex at the near optical axis, and the image side surfaces S4 and S6 are convex at the near optical axis, which can reduce aberrations and improve clarity by converging light; the object side surface S7 of the fourth lens 4 is concave at the near optical axis, and the image side surface S8 is concave at the near optical axis, which realizes the divergence of light, meets the imaging needs, and is conducive to reducing the total length of the optical system. The lenses of the optical system of the present application use aspherical lenses and adopt different combinations of surface shapes to make the optical system have better imaging effects and improve user experience.

[0081] In some embodiments, the optical system further includes a parallel plate 6 , which is disposed between the fourth lens 4 and the image side B;

[0082] The optical system also satisfies the following conditions:

[0083] 0.2≤CT1 / ∑CT≤0.25;

[0084] 0.2≤CT2 / ∑CT≤0.23;

[0085] 0.19≤CT3 / ∑CT≤0.26;

[0086] 0.12≤CT4 / ∑CT≤0.15;

[0087] Wherein, CT1, CT2, CT3, and CT4 represent the center thicknesses of the first lens 1, the second lens 2, the third lens 3, and the fourth lens 4 on the optical axis, respectively, and ∑CT represents the sum of the center thicknesses of the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, and the parallel plate 6 on the optical axis. That is, CT1 / ∑CT can be any value in the range of [0.2, 0.25], for example, the values ​​can be 0.208, 0.219, 0.229, 0.236, 0.246, 0.25, etc.; CT2 / ∑CT can be any value in the range of [0.2, 0.23], for example, the values ​​can be 0.209, 0.219, 0.225, 0.23, etc.; CT3 / ∑CT can be any value in the range of [0.19, 0.26], for example, the values ​​can be 0.198, 0.208, 0.215, 0.226, 0.234, 0.247, 0.258, 0.26, etc.; CT4 / ∑CT can be any value in the range of [0.12, 0.15], for example, the values ​​can be 0.123, 0.136, 0.147, 0.15, etc.

[0088] By satisfying the constraints of the conditional formula and rationally configuring the thicknesses of the first lens 1, the second lens 2, the third lens 3, and the fourth lens 4, it is beneficial to correct aberrations and compensate for each other, which can reduce the sensitivity of the lens and reduce the difficulty in the molding process. At the same time, it is beneficial to reduce the overall length of the optical system and realize ultra-thin and miniaturized lenses.

[0089] In some embodiments, the air distance between the object side A and the first lens 1 on the optical axis is 20 mm;

[0090] The air distance between the first lens 1 and the second lens 2 on the optical axis is 0.15mm-0.192mm;

[0091] The air distance between the second lens 2 and the third lens 3 on the optical axis is 0.02mm-0.05mm;

[0092] The air distance between the third lens 3 and the fourth lens 4 on the optical axis is 0.05mm-0.052mm;

[0093] The air distance between the fourth lens 4 and the image side B on the optical axis is 0.561 mm-0.6 mm.

[0094] The spacing between the first lens 1 and the second lens 2 can be any value within the range of [0.15mm, 0.192mm], for example, the values ​​can be 0.153mm, 0.167mm, 0.174mm, 0.182mm, 0.191mm, etc.; the spacing between the second lens 2 and the third lens 3 can be any value within the range of [0.02mm, 0.05mm], for example, the values ​​can be 0.023mm, 0.028mm, 0.031mm, 0.037mm, 0.043mm, 0.048mm, etc.; the spacing between the second lens 2 and the third lens 3 can be any value within the range of [0.02mm, 0.05mm], for example, the values ​​can be 0.023mm, 0.028mm, 0.031mm, 0.037mm, 0.043mm, 0.048mm, etc. The distance between the lens 3 and the fourth lens 4 can be any value in the range of [0.05mm, 0.052mm], for example, the value can be 0.0502mm, 0.0512mm, 0.0515mm, 0.0519mm, etc.; the distance between the fourth lens 4 and the image side B can be any value in the range of [0.561mm, 0.6mm], for example, the value can be 0.564mm, 0.569mm, 0.573mm, 0.579mm, 0.584mm, 0.589mm, 0.595mm, 0.6mm, etc.

[0095] By meeting the limits of each range and rationally configuring the distances between adjacent lenses in the first, second, third, and fourth lenses, the overall length of the optical system is reduced, leading to a more compact lens. Furthermore, the air distance between the fourth lens 4 and the image side B on the optical axis is the optical back focus. A larger optical back focus improves the adaptability of the optical system while also meeting the wearing needs of different users.

[0096] In some embodiments, the optical system further satisfies the following conditional formula:

[0097] 8.11≤R12-R11≤21.06;

[0098] -4.90≤R22-R21≤-4.35;

[0099] 2849.39≤R32-R31≤256298.39;

[0100] -10.99≤R42-R41≤-10.46;

[0101] Among them, R11, R12, R31, and R41 respectively represent the curvature radii of the object-side surfaces of the first lens 1, the second lens 2, the third lens 3, and the fourth lens 4, and R21, R22, R32, and R42 respectively represent the curvature radii of the image-side surfaces of the first lens 1, the second lens 2, the third lens 3, and the fourth lens 4. That is, R12-R11 can be any value in the range of [8.11, 21.06], for example, the values ​​can be 8.23, 9.56, 10.47, 13.89, 15.34, 16.89, 18.03, 19.87, 20.32, 21.05, etc.; R22-R21 can be any value in the range of [-4.90, -4.35], for example, the values ​​can be -4.87, -4.76, -4.63, -4.58, -4.41, -4.35, etc.; R32-R31 can be in the range of [2849.39, 256298.39] For example, the values ​​can be 2867, 4789, 5902, 6378, 8904, 9578, 10784, 15789, 18943, 19045, 23678, 55347, 118974, 156834, 179056, 209845, 234578, 254671, etc.; R42-R41 can be any value in the range of [-10.99, -10.46], for example, the values ​​can be -10.98, -10.84, -10.74, -10.63, -10.57, -10.46, etc.

[0102] By satisfying the conditional expression, the curvature radii of the object-side surface and the image-side surface of the first lens 1 , the second lens 2 , the third lens 3 , and the fourth lens 4 are reasonably configured to achieve a good imaging effect.

[0103] In some embodiments, the first lens 1 , the second lens 2 , the third lens 3 , the fourth lens 4 and the parallel plate 6 are made of plastic.

[0104] The lens of the present application is made of all-plastic material, which has low processing cost and is conducive to achieving a lightweight design of the entire device compared to all-glass material.

[0105] In some embodiments, the refractive index of the first lens 1 and the second lens 2 is 1.544, the refractive index of the third lens 3 is 1.64, and the refractive index of the fourth lens 4 is 1.66;

[0106] Alternatively, the Abbe number of the first lens 1 and the second lens 2 is 56, the Abbe number of the third lens 3 is 23.5, and the Abbe number of the fourth lens 4 is 20.4.

[0107] By adopting a combination of low-low-high-high refractive index, or high-high-low-low Abbe number, chromatic aberration can be effectively eliminated and image quality can be improved.

[0108] In some embodiments, the maximum full field of view angle of the eye tracking lens optical system is 97°-103°, for example, it can be 97°, 98°, 99°, 100°, 101°, 102°, 103°, etc.

[0109] By meeting the field of view angle range limit, the optical system can achieve an effect close to the human eye's field of view, provide a larger eye movement range, and bring an immersive sensory experience to users.

[0110] In some embodiments, the aperture of the eye tracking lens optical system is 1.9-2.1, for example, it can be 1.9, 2.0, 2.1, etc.

[0111] The aperture range of the optical system of the present application is relatively small, and a small aperture is beneficial for improving image quality and overall brightness, and reducing aberrations and chromatic aberrations.

[0112] In order to further illustrate the present application, the eye tracking lens optical system provided by the present application is described in detail below in combination with specific embodiments.

[0113] First embodiment

[0114] Reference Figure 2-Figure 5 The eye-tracking lens optical system of the first embodiment has an aperture of 2.0, a maximum full field of view of 100°, and an operating wavelength of infrared light. The optical system comprises, along the optical axis from object side A to image side B, a first lens 1 with a negative focal length, an aperture 5, a second lens 2 with a positive focal length, a third lens 3 with a positive focal length, a fourth lens 4 with a negative focal length, and a parallel plate 6. Referring to Tables 1 and 2, the focal length f1 of the first lens 1 is -1.19 mm, the focal length f2 of the second lens 2 is 0.62 mm, the focal length f3 of the third lens 3 is 2.52 mm, and the focal length f4 of the fourth lens 4 is -3.31 mm, resulting in a focal length F of the optical system of 0.63 mm.

[0115] The first lens 1, the second lens 2, the third lens 3 and the fourth lens 4 are all aspherical lenses. Among them, the object-side surface S1 of the first lens 1 is convex at the near optical axis, and the image-side surface S2 is concave at the near optical axis; the object-side surface S3 of the second lens 2 is convex at the near optical axis, and the image-side surface S4 is convex at the near optical axis; the object-side surface S5 of the third lens 3 is convex at the near optical axis, and the image-side surface S6 is convex at the near optical axis; the object-side surface S7 of the fourth lens 4 is concave at the near optical axis, and the image-side surface S8 is concave at the near optical axis.

[0116] The center thickness of the first lens 1 is 0.25mm, the center thickness of the second lens 2 is 0.24mm, the center thickness of the third lens 3 is 0.21mm, and the center thickness of the fourth lens 4 is 0.15mm. The distance between the object side A and the first lens 1 is 20mm; the distance between the first lens 1 and the second lens 2 is 0.15mm; the distance between the second lens 2 and the third lens 3 is 0.05mm; the distance between the third lens 3 and the fourth lens 4 is 0.05mm; and the distance between the fourth lens 4 and the image side B is 0.6mm. The total length (TTL) of the optical system of the first embodiment is 1.7mm, which facilitates the miniaturization of the entire device.

[0117] Reference Figure 3 , is a distortion curve diagram of the optical system of the first embodiment, in which the horizontal axis represents the distortion percentage and the vertical axis represents the field angle. Figure 2 It can be seen from the figure that the distortion is controlled within -25% and is a negative value, which means that the central aperture 5 can well correct the distortion of the optical system, which is beneficial to improving the imaging quality of the optical system.

[0118] Reference Figure 4 and Figure 5 , is the response and resolution of the optical system of the first embodiment in the spatial frequency range at full screen and half screen. The horizontal axis represents the spatial frequency and the vertical axis represents the percentage. Each curve represents a different field of view. The larger the value at the end of each curve, the better the image quality. Figure 4 and Figure 5 As shown, the OTF modulus is controlled above 30% when the full screen is used, and above 70% when the half screen is used, indicating that the optical system has good clarity and good imaging effect. For other parameters of the optical system of the first embodiment, please refer to Table 1 and Table 2.

[0119] Table 1

[0120] Surface serial number Surface type Radius of curvature thickness Refractive index / Abbe number Cone coefficient Remark 0 Standard surface unlimited 20 / Object side A 1 Aspheric -7.411E+00 0.25 1.544 / 56 1.194E+01 S1 2 Aspheric 7.011E-01 0.1 9.024E+00 S2 3 Standard surface unlimited 0.05 / aperture 4 Aspheric 3.991E+00 0.24 1.544 / 56 -7.901E+00 S3 5 Aspheric -3.532E-01 0.05 -3.039E-01 S4 6 Aspheric 1.601E+00 0.21 1.64 / 23.5 1.012E+00 S5 7 Aspheric 2.851E+03 0.05 -7.638E+00 S6 8 Aspheric -1.812E+00 0.15 1.66 / 20.4 -1.275E+00 S7 9 Aspheric -1.228E+01 0.12 2.410E+01 S8 10 Standard surface unlimited 0.21 1.52 / 64.2 / S9 11 Standard surface unlimited 0.27 / S10 12 Standard surface unlimited 0 / Image side B

[0121] Table 2

[0122] Surface serial number 4th-order coefficients 6th-order coefficient 8th-order coefficient 10th-order coefficient 12th-order coefficients Remark 0 / / / / / Object side A 1 1.856E+00 -1.830E+00 5.985E-01 3.481E+00 8.465E+00 S1 2 1.642E+00 1.036E+02 -6.292E-04 3.658E-03 -8.315E-02 S2 3 / / / / / aperture 4 -3.130E-02 5.246E-01 -2.312E+00 -2.694E+01 -2.147E+02 S3 5 2.780E-01 1.193E+00 4.347E-02 6.905E-01 1.047E+01 S4 6 -5.208E-01 1.143E+00 4.051E-03 3.100E-02 2.544E-01 S5 7 -1.604E+00 3.738E+00 -4.869E-03 -1.068E-01 -8.392E-01 S6 8 -3.210E-01 -2.179E+00 3.102E-03 4.927E-02 2.730E-01 S7 9 1.227E+00 -2.518E+00 4.158E-03 -2.193E-02 -1.166E-01 S8 10 / / / / / S9 11 / / / / / S10 12 / / / / / Image side B

[0123] Second embodiment

[0124] Reference Figure 6-Figure 9The eye-tracking lens optical system of the second embodiment has an aperture of 2.0, a maximum full field of view of 100°, and an operating wavelength of infrared light. The optical system comprises, along the optical axis from object side A to image side B, a first lens 1 with a negative focal length, an aperture 5, a second lens 2 with a positive focal length, a third lens 3 with a positive focal length, a fourth lens 4 with a negative focal length, and a parallel plate 6. Referring to Tables 3 and 4, the focal length f1 of the first lens 1 is -1.51 mm, the focal length f2 of the second lens 2 is 0.6 mm, the focal length f3 of the third lens 3 is 2.46 mm, and the focal length f4 of the fourth lens 4 is -2.6 mm, resulting in a focal length F of the optical system of 0.64 mm.

[0125] The first lens 1, the second lens 2, the third lens 3 and the fourth lens 4 are all aspherical lenses. Among them, the object-side surface S1 of the first lens 1 is convex at the near optical axis, and the image-side surface S2 is concave at the near optical axis; the object-side surface S3 of the second lens 2 is convex at the near optical axis, and the image-side surface S4 is convex at the near optical axis; the object-side surface S5 of the third lens 3 is convex at the near optical axis, and the image-side surface S6 is convex at the near optical axis; the object-side surface S7 of the fourth lens 4 is concave at the near optical axis, and the image-side surface S8 is concave at the near optical axis.

[0126] The center thickness of the first lens 1 is 0.2mm, the center thickness of the second lens 2 is 0.2mm, the center thickness of the third lens 3 is 0.25mm, and the center thickness of the fourth lens 4 is 0.12mm. The distance between the object side A and the first lens 1 is 20mm; the distance between the first lens 1 and the second lens 2 is 0.1913mm; the distance between the second lens 2 and the third lens 3 is 0.02mm; the distance between the third lens 3 and the fourth lens 4 is 0.052mm; and the distance between the fourth lens 4 and the image side B is 0.561mm. The total length (TTL) of the optical system of the second embodiment is further reduced to 1.6mm, facilitating a compact design of the entire device.

[0127] Reference Figure 7 , is a distortion curve diagram of the optical system of the second embodiment, in which the horizontal axis represents the distortion percentage and the vertical axis represents the field angle. Figure 2 It can be seen from the figure that the distortion is controlled within -25% and is a negative value, which means that the central aperture 5 can well correct the distortion of the optical system, which is beneficial to improving the imaging quality of the optical system.

[0128] Reference Figure 8 and Figure 9 , is the response and resolution of the optical system of the second embodiment in the spatial frequency range at full screen and half screen. The horizontal axis represents the spatial frequency and the vertical axis represents the percentage. Each curve represents a different field of view. The larger the value at the end of each curve, the better the image quality. Figure 8 and Figure 9As shown, the OTF modulus is controlled above 30% when the full screen is on, and above 60% when the half screen is on, indicating that the optical system has good clarity and good imaging effect. For other parameters of the optical system of the first embodiment, please refer to Table 3 and Table 4.

[0129] Table 3

[0130] Surface serial number Surface type Radius of curvature thickness Refractive index / Abbe number Cone coefficient Remark 0 Standard surface unlimited 20 / Object side A 1 Aspheric -2.02E+01 0.2 1.544 / 56 1.469E+01 S1 2 Aspheric 8.57E-01 0.1213 1.742E+01 S2 3 Standard surface unlimited 0.07 / aperture 4 Aspheric 4.557E+00 0.2 1.544 / 56 -1.544E+01 S3 5 Aspheric -3.423E-01 0.02 -1.654E-01 S4 6 Aspheric 1.607E+00 0.25 1.64 / 23.5 3.224E-01 S5 7 Aspheric 2.563E+05 0.052 -1.255E+01 S6 8 Aspheric -1.583E+00 0.12 1.66 / 20.4 -1.542E+00 S7 9 Aspheric -1.257E+01 0.181 4.049E+01 S8 10 Standard surface unlimited 0.21 1.52 / 64.2 / S9 11 Standard surface unlimited 0.17 / S10 12 Standard surface unlimited 0 / Image side B

[0131] Table 4

[0132]

[0133]

[0134] The present application also provides an AR / VR device including the eye-tracking lens optical system of the first aspect, which exhibits excellent imaging quality. Because the AR / VR device includes all the technical features of the eye-tracking lens optical system, the AR / VR device also includes all the beneficial effects of the eye-tracking lens optical system, which will not be further elaborated here.

[0135] Obviously, those skilled in the art may make various changes and modifications to this application without departing from the spirit and scope of this application. Thus, if these modifications and variations of this application fall within the scope of the claims of this application and their equivalents, this application is intended to include these modifications and variations.

Claims

1. An eye tracking lens optical system, characterized in that: The lens system includes, from the object side to the image side, a first lens having a negative focal length, a second lens having a positive focal length, a third lens having a positive focal length, and a fourth lens having a negative focal length. The optical system satisfies the following conditional formula: 1.8≤|f1| / F≤2.5; 0.8≤|f2| / F≤1.0; 3.5≤|f3| / F≤4.0; 4.0≤|f4| / F≤6.0; 1.6mm≤TTL≤1.7mm; Wherein, f1 represents the focal length of the first lens, f2 represents the focal length of the second lens, f3 represents the focal length of the third lens, f4 represents the focal length of the fourth lens, F represents the focal length of the optical system, and TTL represents the distance from the object side to the image side of the first lens on the optical axis.

2. The eye tracking lens optical system according to claim 1, wherein: The optical system further includes an aperture, and the aperture is disposed between the first lens and the second lens.

3. The eye-tracking lens optical system according to claim 1, wherein: Each lens has an object side surface and an image side surface, and both the object side surface and the image side surface are aspherical; The object side surface of the first lens is convex at the near optical axis, and the image side surface is concave at the near optical axis; The object side surface of the second lens is convex at the near optical axis, and the image side surface is convex at the near optical axis; The object side surface of the third lens is convex at the near optical axis, and the image side surface is convex at the near optical axis; The object side surface of the fourth lens is concave at the near optical axis, and the image side surface is concave at the near optical axis.

4. The eye-tracking lens optical system according to claim 1, wherein: The optical system further includes a parallel plate, wherein the parallel plate is provided between the fourth lens and the image side; The optical system also satisfies the following conditional formula: 0.2≤CT1 / ∑CT≤0.25; 0.2≤CT2 / ∑CT≤0.23; 0.19≤CT3 / ∑CT≤0.26; 0.12≤CT4 / ∑CT≤0.15; Wherein, CT1, CT2, CT3, and CT4 represent the center thicknesses of the first lens, the second lens, the third lens, and the fourth lens on the optical axis, respectively, and ΣCT represents the sum of the center thicknesses of the first lens, the second lens, the third lens, the fourth lens, and the parallel plate on the optical axis.

5. The eye-tracking lens optical system according to claim 4, wherein: The air distance between the object side and the first lens on the optical axis is 20 mm; The air distance between the first lens and the second lens on the optical axis is 0.15mm-0.192mm; The air distance between the second lens and the third lens on the optical axis is 0.02mm-0.05mm; The air distance between the third lens and the fourth lens on the optical axis is 0.05mm-0.052mm; An air distance between the fourth lens and the image side on the optical axis is 0.561 mm-0.6 mm.

6. The eye-tracking lens optical system according to claim 5, wherein: The optical system also satisfies the following conditional formula: 8.11mm≤R12-R11≤21.06mm; -4.90mm≤R22-R21≤-4.35mm; 2849.39mm≤R32-R31≤256298.39mm; -10.99mm≤R42-R41≤-10.46mm; Among them, R11, R12, R31, and R41 respectively represent the curvature radii of the object side surfaces of the first lens, the second lens, the third lens, and the fourth lens, and R21, R22, R32, and R42 respectively represent the curvature radii of the image side surfaces of the first lens, the second lens, the third lens, and the fourth lens.

7. The eye-tracking lens optical system according to claim 6, wherein: The first lens, the second lens, the third lens, the fourth lens and the parallel plate are made of plastic.

8. The eye-tracking lens optical system according to claim 7, wherein: The refractive index of the first lens and the second lens is 1.544, the refractive index of the third lens is 1.64, and the refractive index of the fourth lens is 1.66; Alternatively, the Abbe numbers of the first lens and the second lens are 56, the Abbe number of the third lens is 23.5, and the Abbe number of the fourth lens is 20.

4.

9. The eye-tracking lens optical system according to claim 8, wherein: The maximum full field of view angle of the eye tracking lens optical system is 97°-103°.

10. An AR / VR device, characterized in that: An eye-tracking lens optical system comprising the eye-tracking lens optical system according to any one of claims 1 to 9.

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