Eye movement tracking iris imaging lens

Abstract

The utility model relates to the technical field of optical imaging, and discloses an eye movement tracking iris imaging lens which comprises a lens body, and a first lens, a second lens, a third lens and an optical filter which are sequentially arranged on the lens body in the direction from the object side to the mirror surface. The first lens, the second lens and the third lens are all aspheric lenses, the first lens is a plano-concave lens, the second lens and the third lens are both biconvex lenses, and the two sides of the optical filter are both plane lenses. The high performance of the system is ensured, a large field angle and a small aperture are provided, and the limitation of a large lens on the size of the whole machine is solved; in addition, the three-piece plastic lens is adopted, so that the overall cost of the lens is effectively reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of optical imaging, and particularly relates to an eye movement tracking iris imaging lens. Background Art

[0002] With the rapid progress of AR and VR technologies, smart devices in the market are constantly innovating. Nowadays, more and more AR / VR devices are starting to add eye movement tracking technology. This innovative function not only improves the user experience but also brings more interaction possibilities for developers. Through precisely tracking the user's gaze and eye movements, AR / VR devices can adjust the rendered content in real time to ensure the accuracy and interactivity of the images, thus greatly enhancing the comfort and satisfaction of the user experience. Eye movement tracking not only enhances the user's navigation ability in the virtual environment but also improves the intuitiveness and efficiency of operations. The addition of this function makes the application scenarios of AR / VR devices more extensive and adds a new dimension to the market competitiveness of AR / VR devices. All in all, with the continuous maturity and development of AR / VR technologies, the eye movement tracking function has become an important feature of the new generation of smart devices.

[0003] However, the existing eye movement tracking optical design solutions have a large aperture and a long overall length, which limits the reduction of the overall size of the machine, not only increasing the volume and weight of the device but also affecting the overall aesthetics. Content of the Utility Model

[0004] In order to overcome the defects existing in the above-mentioned prior art, the purpose of the utility model is to provide an eye movement tracking iris imaging lens to solve the technical problems of large aperture and long overall length in the existing eye movement tracking optical design.

[0005] The utility model is realized through the following technical solutions:

[0006] An eye movement tracking iris imaging lens includes a lens body, and the lens body is sequentially provided with a first lens, a second lens, a third lens, and a filter from the object side to the mirror side; the first lens, the second lens, and the third lens are all aspherical lenses, wherein the first lens is a plano-concave lens, and the second lens and the third lens are both biconvex lenses, and both sides of the filter are plano lenses.

[0007] Preferably, one side of the first lens close to the object side is a first spherical surface, and the first spherical surface is a plane; one side of the first lens close to the mirror side is a second spherical surface, and the second spherical surface is a concave surface.

[0008] Preferably, one side of the second lens close to the object side is a third spherical surface, and the third spherical surface is a convex surface; one side of the second lens close to the mirror side is a fourth spherical surface, and the fourth spherical surface is a convex surface.

[0009] Preferably, one side of the third lens close to the object side is a fifth spherical surface, which is a convex surface, and one side of the third lens close to the mirror surface is a sixth spherical surface, which is a convex surface.

[0010] Preferably, the focal length f1 of the first lens ranges from -1.0 mm ≤ f1 ≤ -0.6 mm; the focal length f2 of the second lens ranges from 0.7 mm ≤ f2 ≤ 1.0 mm; the focal length f3 of the third lens ranges from 1.3 mm ≤ f3 ≤ 1.6 mm.

[0011] Preferably, an optical cable is provided between one side of the second lens close to the mirror surface and one side of the third lens close to the object side, and the diameter Sd of the optical cable ranges from 0.53 mm ≤ Sd ≤ 0.58 mm.

[0012] Preferably, the effective focal length f of the lens body satisfies the range of 0.9 mm ≤ f ≤ 1.1 mm, and the overall optical length TTL of the lens body satisfies the range of 3.30 mm ≤ TTL ≤ 3.45 mm.

[0013] Preferably, the diameter Smax of the lens body ranges from 1.60 mm ≤ Smax ≤ 1.65 mm.

[0014] Preferably, the field of view FOV of the lens body satisfies the condition that FOV ≤ 70°.

[0015] Preferably, the angle between the principal ray of the incident surface and the principal ray of the exit surface of the lens body, i.e., the viewing angle θ, is 0°.

[0016] Compared with the prior art, the present utility model has the following beneficial technical effects:

[0017] The present utility model provides an eye movement tracking iris imaging lens, including a lens body, and the lens body is sequentially provided with a first lens, a second lens, a third lens, and a filter from the object side to the mirror surface direction; the first lens, the second lens, and the third lens are all aspherical lenses, wherein the first lens is a plano-concave lens, the second lens and the third lens are both biconvex lenses, and both sides of the filter are plano lenses. By using aspherical lenses and combining positive and negative focal lengths, while ensuring high performance of the system, a large field of view and a small diameter are provided, solving the limitation of the large size of the lens on the overall size of the whole machine; in addition, by using three-piece plastic lenses, the overall cost of the lens is effectively reduced.

[0018] Furthermore, one side of the first lens close to the object side is the first spherical surface, and the first spherical surface is a plane; one side of the first lens close to the mirror surface is the second spherical surface, and the second spherical surface is a concave surface, which reduces the processing difficulty and makes the imaging performance of the optical system more stable and reliable; one side of the second lens close to the object side is the third spherical surface, and the third spherical surface is a convex surface, one side of the second lens close to the mirror surface is the fourth spherical surface, and the fourth spherical surface is a convex surface, one side of the third lens close to the object side is the fifth spherical surface, and the fifth spherical surface is a convex surface, one side of the third lens close to the mirror surface is the sixth spherical surface, and the sixth spherical surface is a convex surface, which greatly improves the imaging efficiency, not only improves the imaging clarity, but also effectively reduces the marginal distortion and chromatic aberration. The combination of different surfaces is used, so that the optical system can maintain excellent performance in complex usage environments.

[0019] Furthermore, an optical cable is provided between one side of the second lens close to the mirror surface and one side of the third lens close to the object side, wherein the caliber Sd of the optical cable ranges from 0.53 mm ≤ Sd ≤ 0.58 mm to ensure the best optical fiber transmission efficiency and image clarity. Description of the Drawings

[0020] Figure 1 Schematic diagram of the structure of the eye movement tracking iris imaging lens in the embodiment of the present invention;

[0021] Figure 2 Schematic diagram of the diffraction MTF of the eye movement tracking iris imaging lens structure in the present invention at a 40 mm object distance in the 750 nm - 900 nm wavelength band;

[0022] Figure 3 Schematic diagram of the diffraction MTF of the eye movement tracking iris imaging lens structure in the present invention at a 20 mm object distance in the 750 nm - 900 nm wavelength band;

[0023] Figure 4 Diffraction MTF & field of view diagram of the eye movement tracking iris imaging lens structure in the present invention at a 40 mm object distance in the 750 nm - 900 nm wavelength band;

[0024] Figure 5 Relative illuminance diagram of the eye movement tracking iris imaging lens structure in the present invention in the 750 nm - 900 nm wavelength band;

[0025] Figure 6 Field curvature & distortion diagram of the eye movement tracking iris imaging lens structure in the present invention in the 750 nm - 900 nm wavelength band;

[0026] Figure 7 Spot diagram of the eye movement tracking iris imaging lens structure in the present invention in the 750 nm - 900 nm wavelength band;

[0027] In the figure: 1 - first lens; 2 - second lens; 3 - third lens; 4 - filter; 5 - mirror surface; 6 - optical cable; 11 - first spherical surface; 12 - second spherical surface; 21 - third spherical surface; 22 - fourth spherical surface; 31 - fifth spherical surface; 32 - sixth spherical surface. Detailed implementation manners

[0028] In order to enable those skilled in the art of the present technology to better understand the solution of the present utility model, the technical solutions in the embodiments of the present utility model will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present utility model.

[0029] It should be noted that the terms "first", "second", etc. in the description and claims of the present utility model and the above accompanying drawings are used to distinguish similar objects, and do not necessarily need to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present utility model described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0030] The present utility model will be further described in detail below in conjunction with the accompanying drawings:

[0031] The purpose of the present utility model is to provide an eye movement tracking iris imaging lens to solve the technical problems of large aperture and long total length in the prior art of eye movement tracking optical design.

[0032] See Figure 1 , in an embodiment of the present utility model, an eye movement tracking iris imaging lens is provided, including a lens body. The lens body is sequentially provided with a first lens 1, a second lens 2, a third lens 3, and a filter 4 in the direction from the object side to the mirror surface 5; the first lens 1, the second lens 2, and the third lens 3 are all aspherical lenses, wherein the first lens 1 is a plano-concave lens, and the second lens 2 and the third lens 3 are both biconvex lenses. Both sides of the filter 4 are plano-convex lenses.

[0033] Specifically, one side of the first lens 1 close to the object side is the first spherical surface 11, and the first spherical surface 11 is a plane; one side of the first lens 1 close to the mirror surface 5 is the second spherical surface 12, and the second spherical surface 12 is a concave surface.

[0034] Specifically, one side of the second lens 2 close to the object side is the third spherical surface 21, and the third spherical surface 21 is a convex surface; one side of the second lens 2 close to the mirror surface 5 is the fourth spherical surface 22, and the fourth spherical surface 22 is a convex surface.

[0035] Specifically, one side of the third lens 3 close to the object side is the fifth spherical surface 31, and the fifth spherical surface 31 is a convex surface; one side of the third lens 3 close to the mirror surface 5 is the sixth spherical surface 32, and the sixth spherical surface 32 is a convex surface.

[0036] Specifically, the range of the focal length f1 of the first lens 1 is -1.0 mm ≤ f1 ≤ -0.6 mm; the range of the focal length f2 of the second lens 2 is 0.7 mm ≤ f2 ≤ 1.0 mm; the range of the focal length f3 of the third lens 3 is 1.3 mm ≤ f3 ≤ 1.6 mm.

[0037] Specifically, an optical cable 6 is provided between one side of the second lens 2 close to the mirror surface 5 and one side of the third lens 3 close to the object side, and the aperture Sd of the optical cable 6 ranges from 0.53 mm ≤ Sd ≤ 0.58 mm.

[0038] Specifically, the effective focal length f of the lens body satisfies the range of 0.9 mm ≤ f ≤ 1.1 mm, the optical total length TTL of the lens body satisfies the range of 3.30 mm ≤ TTL ≤ 3.45 mm; the f / TTL of the lens body satisfies the range of 0.26 ≤ f / TTL ≤ 0.33; the Imeg / f of the lens body satisfies the range of 0.63 < Imeg / f < 0.77; the Imeg / TTL of the lens body satisfies the range of 0.20 < Imeg / TTL < 0.25; where Imeg is the maximum semi-image height and TTL is the axial distance from the object side surface of the first lens to the imaging surface.

[0039] Specifically, the aperture Smax of the lens body ranges from 1.60 mm ≤ Smax ≤ 1.65 mm; the field of view FOV of the lens body satisfies the condition of FOV ≤ 70°, and the angle θ between the principal ray of the incident surface and the principal ray of the exit surface of the lens body, i.e., the viewing angle, is 0°.

[0040] In this embodiment, the paraxial working F# of the lens body satisfies 2 ≤ F#, and the first lens 1, the second lens 2, and the third lens 3 in the lens body are all aspherical plastic lenses. The characteristic conditions of the material refractive index Nd and Abbe number Vd are as follows:

[0041] 1.50 ≤ Nd1 ≤ 1.55, 52 ≤ Vd1 ≤ 58;

[0042] 1.60 ≤ Nd2 ≤ 1.68, 20 ≤ Vd2 ≤ 28;

[0043] 1.50 ≤ Nd3 ≤ 1.55, 52 ≤ Vd3 ≤ 58;

[0044] Among them, the refractive index of the first lens is Nd1, and the dispersion coefficient is Vd1; the refractive index of the second lens is Nd2, and the dispersion coefficient is Vd2; the refractive index of the third lens is Nd3, and the dispersion coefficient is Vd3. Using all-plastic materials can reduce costs, lighten the weight of the lens, improve manufacturing efficiency, and correct the aberration of the optical system by reasonably matching materials with high and low dispersion coefficients, ensuring the resolution.

[0045] In this embodiment, the first lens, the second lens, and the third lens are aspherical lenses. Their surface shapes satisfy the following equations:

[0046]

[0047] Among them, y represents the radial coordinate value of the lens perpendicular to the optical axis, Z is the distance sag from the vertex of the aspherical surface when the aspherical lens is at a position with a height of y along the optical axis direction, c = 1 / R, R represents the central curvature radius of the corresponding aspherical lens surface shape, k represents the conic coefficient, and the parameters A, B, C, D, and E are high-order aspherical coefficients.

[0048] The detailed optical data in this embodiment are shown in Table 1-1.

[0049] Serial Number Item Value 1 System Focal Length f / mm 1.1 2 F# @ Object Distance 40mm 2.5 3 Total Optical Length TTL / mm 3.4 4 Field of View FOV / ° 70 <![CDATA[Diaphragm aperture S d / mm]]> 0.55 4 Imeg / f 0.64 5 Imeg / TTL 0.21 6 Chief Ray Angle CRA / ° 21.73

[0050] Table 1-1 Main design parameters

[0051] The detailed optical data of this embodiment in this table are shown in Table 1-2:

[0052] Surf Radius Thickness Glass Semi-Diameter (D / 2) OBJ Infinity 10.000 27.506 1 Infinity 0.300 Nd: 1.51, Vd: 52.7 0.810 2 0.293 0.500 0.520 3 0.659 0.575 Nd: 1.63, Vd: 27.3 0.520 4 -210.592 0.425 0.456 STP Infinity 0.100 0.397 6 1.356 0.425 Nd: 1.51, Vd: 52.7 0.465 7 -2.981 0.070 0.494 IMA Infinity / 0.510

[0053] Table 1-2 Lens parameters

[0054] The high-order term coefficients of the aspherical lens in this embodiment are shown in Table 1-3:

[0055] Surf Conic A4 A6 A8 2 -0.895 -1.063 1.754 -7.578 3 -0.287 -0.566 -0.064 -3.542 4 -127.8 -0.468 -1.275 -0.009 8 -2.871 0.154 -4.749 13.005 9 -15.15 0.433 -2.314 1.985

[0056] Table 1-3 High-order term coefficients of the aspherical lens

[0057] In this example, the performance of the lens is evaluated by the modulation transfer function (MTF) curve in the visible light band. The MTF curve of the lens at a 40 mm object distance in the 750 nm - 900 nm band is as Figure 2, as shown in the figure, when the MTF frequency reaches 180 lp / mm, the MTF value of the central field of view exceeds 0.3, indicating that the central region of the image can maintain high resolution and clarity. The MTF curve graph of the lens at a object distance of 20 mm in the wavelength range of 750 nm - 900 nm is as Figure 3 , when the MTF frequency reaches 90 lp / mm, the MTF value of the central field of view exceeds 0.2, indicating that the optical system can ensure clear imaging when the object distance is greater than 20 mm.

[0058] According to Figure 4 Shown is the field of view & MTF graph of the imaging system. It can be seen that the OTF modulus of the MTF in the sagittal direction and the meridional direction remains stable from the central field of view to the edge field of view, ensuring the consistency of the imaging of the center and the edge of the lens and the quality of the out-of-focus imaging.

[0059] According to Figure 5 Shown is the illuminance curve of the imaging system. It can be seen that the relative illuminance ≥ 70%, ensuring the clarity and contrast of the imaging.

[0060] According to Figure 6 The shown distortion graph shows that the distortion in this embodiment is strictly controlled within 8%. It can effectively capture the structure of the imaging target with less deformation, thus ensuring the authenticity and accuracy of the image and providing a reliable basis for subsequent image processing. At the same time, the field curvature graph shows that the field curvature value of this embodiment ≤ 0.01 mm, and both the central field of view and the edge field of view are well corrected, ensuring the uniform image quality throughout the imaging area. The smaller the spot radius, the better the convergence of light and the better the imaging effect, as Figure 7 shown.

[0061] In summary, the present utility model provides an eye movement tracking iris imaging lens, including a lens body. The lens body is sequentially provided with a first lens, a second lens, a third lens, and a filter from the object side to the mirror surface direction; the first lens, the second lens, and the third lens are all aspherical lenses, wherein the first lens is a plano-concave lens, and the second lens and the third lens are both biconvex lenses. Both sides of the filter are plano-convex lenses. By using aspherical lenses and matching positive and negative focal lengths, while ensuring the high performance of the system, a large field of view angle and a small aperture are provided, solving the limitation of the large size of the lens on the overall size of the machine; in addition, by using three-piece plastic lenses, the overall cost of the lens is effectively reduced.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present utility model and are not intended to limit it. Although the present utility model has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications or equivalent replacements can still be made to the specific implementation manners of the present utility model, and any modification or equivalent replacement that does not depart from the spirit and scope of the present utility model should be covered within the protection scope of the claims of the present utility model.

Claims

1. An eye movement tracking iris imaging lens, characterized in that, It includes a lens body, and the lens body is successively provided with a first lens (1), a second lens (2), a third lens (3), and a filter (4) from the object side to the mirror surface (5) direction; the first lens (1), the second lens (2), and the third lens (3) are all aspherical lenses, wherein the first lens (1) is a plano-concave lens, and the second lens (2) and the third lens (3) are both biconvex lenses, and both sides of the filter (4) are plano lenses.

2. The eye movement tracking iris imaging lens according to claim 1, characterized in that One side of the first lens (1) close to the object side is a first spherical surface (11), and the first spherical surface (11) is a plane; one side of the first lens (1) close to the mirror surface (5) is a second spherical surface (12), and the second spherical surface (12) is a concave surface.

3. The eye movement tracking iris imaging lens according to claim 1, wherein One side of the second lens (2) close to the object side is a third spherical surface (21), and the third spherical surface (21) is a convex surface. One side of the second lens (2) close to the mirror surface (5) is a fourth spherical surface (22), and the fourth spherical surface (22) is a convex surface.

4. The eye movement tracking iris imaging lens according to claim 1, characterized in that, One side of the third lens (3) close to the object side is a fifth spherical surface (31), and the fifth spherical surface (31) is a convex surface. One side of the third lens (3) close to the mirror surface (5) is a sixth spherical surface (32), and the sixth spherical surface (32) is a convex surface.

5. The eye movement tracking iris imaging lens according to claim 1, wherein, The range of the focal length f1 of the first lens (1) is -1.0 mm ≤ f1 ≤ -0.6 mm; the range of the focal length f2 of the second lens (2) is 0.7 mm ≤ f2 ≤ 1.0 mm; the range of the focal length f3 of the third lens (3) is 1.3 mm ≤ f3 ≤ 1.6 mm.

6. The eye movement tracking iris imaging lens according to claim 1, characterized in that, An optical cable (6) is provided between one side of the second lens (2) close to the mirror surface (5) and one side of the third lens (3) close to the object side, and the diameter Sd of the optical cable (6) ranges from 0.53 mm to 0.58 mm.

7. An eye movement tracking iris imaging lens according to claim 1, characterized in that, The range satisfied by the effective focal length f of the lens body is 0.9 mm ≤ f ≤ 1.1 mm, and the range satisfied by the optical total length TTL of the lens body is 3.30 mm ≤ TTL ≤ 3.45 mm.

8. An eye movement tracking iris imaging lens according to claim 1, wherein The range of the diameter Smax of the lens body is 1.60 mm ≤ Smax ≤ 1.65 mm.

9. The eye movement tracking iris imaging lens according to claim 1, wherein The condition satisfied by the field of view angle FOV of the lens body is FOV ≤ 70°.

10. The eye movement tracking iris imaging lens according to claim 1, characterized in that, The angle between the principal ray of the incident surface and the principal ray of the exit surface of the lens body, that is, the view angle θ, is 0°.

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