A large aperture TOF lens

Abstract

This utility model relates to a large-aperture TOF lens, comprising, from the object side to the image side along the optical axis: a first lens with negative optical power, the object side of the first lens being convex and the image side being concave; a second lens with positive optical power, the object side of the second lens being convex and the image side being concave; a third lens with positive optical power, the object side of the third lens being concave and the image side being convex; and a fourth lens with negative optical power, the object side of the fourth lens being convex and the image side being concave. The large-aperture TOF lens satisfies the following conditions: BFL / TTL > 0.35, S42 / BFL > 0.36, where BFL is the axial distance from the center point of the image side of the fourth lens to the imaging plane, TTL is the axial distance from the object side of the first lens to the imaging plane, and S42 is the sag of the image side of the fourth lens. The advantages of this utility model are its small size, light weight, high image quality, and good high and low temperature imaging quality.

Description

Technical Field

[0001] This utility model relates to the field of optical lens technology, specifically to a large aperture TOF lens. Background Technology

[0002] Time-of-Flight (TOF) technology boasts advantages such as Level 1 safety compliance, compact size, fast response speed, high recognition accuracy, low error, direct output of depth data, and strong anti-interference capabilities, making it the preferred technology for depth sensing in various application fields. Therefore, TOF technology is widely used in many fields, including VR / AR gesture interaction, automotive electronic ADAS, smart homes, industrial automation, facial recognition, mobile phones, and robotics.

[0003] Current TOF lenses have too many elements and an excessively long optical length, resulting in high overall cost and limitations in installation and use. They also exhibit significant temperature drift, meaning that even minor temperature changes can severely impact image quality. Furthermore, market applications demand high image quality and large apertures from TOF lenses. To address these needs, a four-lens TOF lens is proposed to adapt to the development of this new technology. Utility Model Content

[0004] The purpose of this invention is to provide a large-aperture TOF lens for the infrared band that is small in size, lightweight, has high imaging quality, and good imaging quality at both high and low temperatures.

[0005] A large-aperture TOF lens, comprising, from the object side to the image side along the optical axis, the following:

[0006] A first lens with negative optical power, wherein the object side of the first lens is convex and the image side is concave;

[0007] A second lens with positive optical power, wherein the object side of the second lens is convex and the image side is concave;

[0008] A third lens with positive optical power, wherein the object side of the third lens is concave and the image side is convex;

[0009] A fourth lens with negative optical power, wherein the object side of the fourth lens is convex and the image side is concave;

[0010] The first lens, the second lens, the third lens, and the fourth lens are all made of plastic. The large-aperture TOF lens satisfies the following conditions: BFL / TTL>0.35, S42 / BFL>0.36, where BFL is the axial distance from the center point of the image side of the fourth lens to the imaging plane, TTL is the axial distance from the object side of the first lens to the imaging plane, and S42 is the sag of the image side of the fourth lens.

[0011] In the above scheme, the first, second, third, and fourth lenses are all made of plastic and all adopt aspherical surface shape. Compared with glass, plastic is much cheaper and lighter, which enables the lens to achieve low cost and reduce the weight of the lens. At the same time, the image side of the fourth lens is concave and has a large sagittal, which increases the back focal length. This is beneficial for the back focal compensation of the base for high and low temperature defocus under different temperature environments, and can better correct temperature drift. When the environment has certain temperature changes, it can still have good image quality, ensuring that the large aperture TOF lens has good high and low temperature imaging quality.

[0012] Furthermore, the large-aperture TOF lens satisfies the following conditions: -7.5 < f1 / f < -5.5, 5.5 < f2 / f < 10.0, 0.9 < f3 / f < 1.5, -20.0 < f4 / f < -13, where f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, f4 is the focal length of the fourth lens, and f is the focal length of the large-aperture TOF lens.

[0013] In the above scheme, the optical power of each lens has a reasonable distribution ratio. The object side of the first lens L1 is convex, which can reduce the incident angle of peripheral light on the first lens L1, help reduce surface reflection, make the optical imaging system more suitable for wide-angle design, and help increase the field of view.

[0014] Furthermore, the large-aperture TOF lens satisfies the following conditions: 1.6≤Nd1≤1.7, 1.6≤Nd2≤1.7, 1.6≤Nd3≤1.7, 1.6≤Nd4≤1.7, where Nd1 is the refractive index of the first lens, Nd2 is the refractive index of the second lens, Nd3 is the refractive index of the third lens, and Nd4 is the refractive index of the fourth lens.

[0015] In the above scheme, the first lens, second lens, third lens and fourth lens are all made of plastic material with high refractive index, which is conducive to achieving reasonable distribution of optical power, can better correct aberrations such as spherical aberration and field curvature, thereby improving lens resolution, and also helps to shorten the overall length of the optical system and realize lens miniaturization.

[0016] Furthermore, the object-side surface of the first lens is inverted, and both the object-side surface and the image-side surface of the second lens are inverted.

[0017] In the above scheme, the object-side surface of the first lens is inverted, and both the object-side surface and the image-side surface of the second lens are inverted. This is beneficial for fully optimizing the shape of the plastic aspherical lens and effectively correcting light aberrations at different apertures, thereby reducing the size of the TOF lens and reducing the assembly sensitivity of the lens, thus improving the resolution performance of the TOF lens.

[0018] Furthermore, the large-aperture TOF lens satisfies the following condition: 0.4 < f / TTL < 0.6, where f is the focal length of the large-aperture TOF lens, and TTL is the on-axis distance from the object side of the first lens to the imaging plane.

[0019] In the above scheme, by making the optical imaging system satisfy the above condition, it is beneficial to maintain high imaging quality while effectively shortening the system length.

[0020] Furthermore, the large-aperture TOF lens satisfies the following condition: 0 < TTL < 4.4 mm, where TTL is the on-axis distance from the object side of the first lens to the imaging plane.

[0021] In the above solution, the total optical length of the large-aperture TOF lens is less than 4.4mm, which has the characteristics of short total optical length and small overall lens size, which is conducive to the thin design of the terminal.

[0022] Furthermore, the large-aperture TOF lens satisfies the following conditional expression: C31 < 0, C32 < 0, C41 > 0, C42 > 0, where C31 is the curvature of the center point of the object-side surface of the third lens, C32 is the curvature of the center point of the image-side surface of the third lens, C41 is the curvature of the center point of the object-side surface of the fourth lens, and C42 is the curvature of the center point of the image-side surface of the fourth lens.

[0023] In the above scheme, the third and fourth lenses that satisfy the above structural relationship are conducive to the reasonable matching of lens shapes, reducing the size of the TOF lens, and reducing the processing sensitivity and assembly sensitivity of the lens, thereby improving the imaging quality of the TOF lens.

[0024] Furthermore, the field of view of the large-aperture TOF lens is greater than 60 degrees.

[0025] In the above solution, the large-aperture TOF lens has a field of view of more than 60 degrees, enabling monitoring of a large field of view.

[0026] Furthermore, an aperture stop with an aperture value FNO≤1.5 is disposed between the first lens and the second lens.

[0027] In the above scheme, the aperture value FNO≤1.5, the lens allows a large amount of light in, and the image brightness is high.

[0028] This invention discloses a large-aperture TOF lens with advantages such as small size, light weight, high image quality, and good high and low temperature imaging quality for use in the infrared band. The first, second, third, and fourth lenses are all made of plastic and employ an aspherical surface. Compared to glass, plastic is much cheaper and lighter, enabling low-cost and weight reduction. Furthermore, the fourth lens has a concave image-side surface with a large sagittal, increasing the back focal length. This facilitates back focal compensation for high and low temperature defocusing under different temperature conditions, effectively correcting temperature drift. Even with significant temperature variations, the lens maintains good image quality, ensuring excellent high and low temperature imaging performance. Attached Figure Description

[0029] Figure 1 This is a cross-sectional view of the large-aperture TOF lens 1 in Example 1.

[0030] Figure 2 The MTF curve of the large aperture TOF lens 1 in Example 1 at room temperature of 20°C is shown.

[0031] Figure 3 The MTF curve of the large-aperture TOF lens 1 in Example 1 at a low temperature of -10℃ is shown.

[0032] Figure 4 The MTF curve of the large aperture TOF lens 1 in Example 1 at a high temperature of 60°C is shown.

[0033] Figure 5 This is a relative illumination curve of the large aperture TOF lens 1 in Example 1.

[0034] Figure 6 This is a schematic diagram of the sagittal height of the fourth lens side of the large-aperture TOF lens 1 in Example 1.

[0035] Figure 7 This is a cross-sectional view of the large-aperture TOF lens 2 in Example 2.

[0036] Figure 8 The MTF curve of the large aperture TOF lens 2 in Example 2 at room temperature of 20°C is shown.

[0037] Figure 9 The MTF curve of the large aperture TOF lens 2 in Example 2 at a low temperature of -10℃ is shown.

[0038] Figure 10The MTF curve of the large aperture TOF lens 2 in Example 2 at a high temperature of 60°C is shown.

[0039] Figure 11 This is a relative illumination curve of the large aperture TOF lens 2 in Example 2.

[0040] Figure 12 This is a schematic diagram of the sagittal height of the fourth lens side of the large-aperture TOF lens 2 in Example 2.

[0041] Figure 13 This is a cross-sectional view of the large-aperture TOF lens 3 in Example 3.

[0042] Figure 14 The MTF curve of the large aperture TOF lens 3 in Example 3 at room temperature (20°C) is shown.

[0043] Figure 15 The MTF curve of the large aperture TOF lens 3 in Example 3 at a low temperature of -10℃ is shown.

[0044] Figure 16 The MTF curve of the large aperture TOF lens 3 in Example 3 at a high temperature of 60°C is shown.

[0045] Figure 17 This is a relative illumination curve of the large-aperture TOF lens 3 in Example 3.

[0046] Figure 18 This is a schematic diagram of the sagittal height of the fourth lens side of the large-aperture TOF lens 3 in Example 3.

[0047] Figure 19 This is a cross-sectional view of the large-aperture TOF lens 4 in Example 4.

[0048] Figure 20 The MTF curve of the large-aperture TOF lens 4 in Example 4 at room temperature (20°C) is shown.

[0049] Figure 21 The MTF curve of the large aperture TOF lens 4 in Example 4 at a low temperature of -10℃ is shown.

[0050] Figure 22 The MTF curve of the large aperture TOF lens 4 in Example 4 at a high temperature of 60°C is shown.

[0051] Figure 23 This is a relative illumination curve of the large aperture TOF lens 4 in Example 4.

[0052] Figure 24 This is a schematic diagram of the sagittal height of the fourth lens side of the large-aperture TOF lens 4 in Example 4.

[0053] The following are the annotations for the reference numerals: 1-4, large aperture TOF lens; L1, first lens; L2, second lens; L3, third lens; L4, fourth lens; STO, aperture stop; BPF, bandpass filter; IMA, imaging plane. Detailed Implementation

[0054] The following will describe in further detail a large-aperture TOF lens of this utility model with reference to specific embodiments and accompanying drawings.

[0055] like Figures 1 to 24 As shown, in a preferred embodiment, a large-aperture TOF lens of the present invention comprises, from the object side to the image side along the optical axis: a first lens L1 with negative optical power, the object side of the first lens L1 being convex and the image side being concave; a second lens L2 with positive optical power, the object side of the second lens L2 being convex and the image side being concave; a third lens L3 with positive optical power, the object side of the third lens L3 being concave and the image side being convex; and a fourth lens L4 with negative optical power. The object-side surface of lens 4 is convex, and the image-side surface is concave. The first lens L1, the second lens L2, the third lens L3, and the fourth lens L4 are all made of plastic. The large-aperture TOF lens satisfies the following conditions: BFL / TTL>0.35, S42 / BFL>0.36, where BFL is the on-axis distance from the center point of the image-side surface of the fourth lens L4 to the imaging plane, TTL is the on-axis distance from the object-side surface of the first lens L1 to the imaging plane, and S42 is the sag of the image-side surface of the fourth lens L4. The first lens L1, the second lens L2, the third lens L3, and the fourth lens L4 are all made of plastic and all use aspherical surfaces. Compared with glass, plastic is much cheaper and lighter, which enables the lens to achieve low cost and reduce weight. At the same time, the image side of the fourth lens L4 is concave and has a large sagittal, which increases the back focal length. This is beneficial for the back focal length compensation of the base for high and low temperature defocusing under different temperature conditions, and can better correct temperature drift. It has good image quality in conditions from -10℃ to 60℃, ensuring that this large aperture TOF lens has excellent high and low temperature imaging quality.

[0056] In the above embodiment, all four lenses are aspherical lenses. Aspherical surfaces have a greater degree of freedom in shape and are significantly better at correcting light refraction and aberrations than spherical surfaces. This is beneficial for improving the resolution of the TOF lens and reducing its size, and is more conducive to the miniaturization of the lens.

[0057] like Figures 1 to 24As shown, in some embodiments, the large-aperture TOF lens satisfies the following conditions: -7.5 < f1 / f < -5.5, 5.5 < f2 / f < 10.0, 0.9 < f3 / f < 1.5, -20.0 < f4 / f < -13, where f1 is the focal length of the first lens L1, f2 is the focal length of the second lens L2, f3 is the focal length of the third lens L3, f4 is the focal length of the fourth lens L4, and f is the focal length of the large-aperture TOF lens. The optical power of each lens has a reasonable distribution ratio. The object-side surface of the first lens L1 is convex, which can reduce the incident angle of peripheral light rays at the first lens L1, helping to reduce surface reflection and making the optical imaging system more suitable for wide-angle designs, thus increasing the field of view.

[0058] like Figures 1 to 24 As shown, in some embodiments, the large-aperture TOF lens satisfies the following conditions: 1.6≤Nd1≤1.7, 1.6≤Nd2≤1.7, 1.6≤Nd3≤1.7, 1.6≤Nd4≤1.7, where Nd1 is the refractive index of the first lens L1, Nd2 is the refractive index of the second lens L2, Nd3 is the refractive index of the third lens L3, and Nd4 is the refractive index of the fourth lens L4. The first lens L1, second lens L2, third lens L3, and fourth lens L4 are all made of plastic materials with high refractive indices, which is beneficial for achieving a reasonable distribution of optical power, better correcting spherical aberration, field curvature, and other aberrations, thereby improving lens resolution. Furthermore, it helps to shorten the overall length of the optical system, achieving lens miniaturization.

[0059] like Figures 1 to 24 As shown, in some embodiments, the object-side surface of the first lens L1 is inverted, and both the object-side surface and the image-side surface of the second lens L2 are inverted. The inversion of the object-side surface of the first lens L1 and the inversion of both the object-side surface and the image-side surface of the second lens L2 facilitates the optimization of the shape of the plastic aspherical lens and effectively corrects light aberrations at different apertures, thereby reducing the size of the TOF lens and decreasing the assembly sensitivity of the lens, ultimately improving the resolving performance of the TOF lens.

[0060] like Figures 1 to 24 As shown, in some embodiments, the large-aperture TOF lens satisfies the following condition: 0.4 < f / TTL < 0.6, where f is the focal length of the large-aperture TOF lens, and TTL is the on-axis distance from the object-side surface of the first lens L1 to the imaging plane. By making the optical imaging system satisfy the above condition, it is beneficial to maintain high imaging quality while effectively shortening the system length.

[0061] like Figures 1 to 24As shown, in some embodiments, the large-aperture TOF lens satisfies the following condition: 0 < TTL < 4.4 mm, where TTL is the axial distance from the object-side surface of the first lens L1 to the imaging plane. This large-aperture TOF lens has a total optical length of less than 4.4 mm, featuring a short total optical length and small overall lens size, which is beneficial for the thinner design of the terminal.

[0062] like Figures 1 to 24 As shown, in some embodiments, the large-aperture TOF lens satisfies the following conditions: C31 < 0, C32 < 0, C41 > 0, C42 > 0, where C31 is the curvature of the center point of the object-side surface of the third lens L3, C32 is the curvature of the center point of the image-side surface of the third lens L3, C41 is the curvature of the center point of the object-side surface of the fourth lens L4, and C42 is the curvature of the center point of the image-side surface of the fourth lens L4. The third lens L3 and the fourth lens L4 satisfying the above structural relationships facilitate a reasonable combination of lens shapes, reduce the size of the TOF lens, and decrease the processing and assembly sensitivity of the lenses, thereby improving the imaging quality of the TOF lens.

[0063] like Figures 1 to 24 As shown, in some embodiments, the field of view of a large-aperture TOF lens is greater than 60 degrees. A field of view greater than 60 degrees enables monitoring over a wider range of fields.

[0064] like Figures 1 to 24 As shown, in some embodiments, an aperture stop with an aperture value FNO ≤ 1.5 is disposed between the first lens L1 and the second lens L2. An aperture value FNO ≤ 1.5 allows for a large amount of light to enter the lens, resulting in high image brightness.

[0065] In various embodiments of this utility model, when the lens adopts an aspherical surface shape, the aspherical surface shapes of the optical lens satisfy the following relationship:

[0066]

[0067] In the formula, Z is the distance between the surface and the surface vertex in the optical axis direction, parameter c is the curvature corresponding to the lens radius, y is the radial coordinate, k is the conic quadratic curve coefficient, and a4, a6, a8, a10, a12, a14, and a16 are the surface coefficients corresponding to the fourth, sixth, eighth, tenth, twelfth, fourteenth, and sixteenth order radial coordinates, respectively.

[0068] Below, examples of large-aperture TOF lenses are provided, along with detailed explanations in conjunction with accompanying drawings.

[0069] Example 1

[0070] Figure 1This is a cross-sectional view of the large-aperture TOF lens 1 in this embodiment. The large-aperture TOF lens 1 includes, from the object side to the image side along the optical axis, a first lens L1, an aperture stop STO, a second lens L2, a third lens L3, a fourth lens L4, a bandpass filter BPF, and an imaging plane IMA.

[0071] The first lens L1 has a negative optical power, a convex object-side surface with inflected edges, and a concave image-side surface. The second lens L2 has a positive optical power, a convex object-side surface with inflected edges, and a concave image-side surface with inflected edges. The third lens L3 has a positive optical power, a concave object-side surface, and a convex image-side surface. The fourth lens L4 has a negative optical power, a convex object-side surface, and a concave image-side surface. All four lenses—L1, L2, L3, and L4—are made of plastic aspherical lenses.

[0072] In this embodiment, the field of view (FOV) of the large aperture TOF lens 1 is 60.2°, and the field of view (FNO) is 1.5.

[0073] The relevant parameters of each lens in the large-aperture TOF lens 1 in this embodiment are shown in Table 1-1.

[0074] Table 1-1

[0075]

[0076]

[0077] The aspherical surface parameters of the large-aperture TOF lens 1 in this embodiment are shown in Table 1-2.

[0078] Table 1-2

[0079]

[0080] like Figure 2 This is the MTF curve of the large-aperture TOF lens 1 in this embodiment at a room temperature of 20°C. Figure 3 This is the MTF curve at a low temperature of -10℃. Figure 4 This is the MTF curve at a high temperature of 60℃. Figure 5 This is a relative illumination curve of the large-aperture TOF lens 1 in this embodiment. Figure 6 This is a schematic diagram of the sagittal height of the fourth lens side of the large-aperture TOF lens 1 in this embodiment.

[0081] according to Figures 2-4The MTF curves of the large-aperture TOF lens 1 shown are displayed under normal temperature of 20℃, low temperature of -10℃, and high temperature of 60℃. It can be seen that the large-aperture TOF lens 1 of this embodiment has good imaging quality under conditions ranging from -10℃ to 60℃, and performs well in harsh environments of low and high temperatures, which can meet the shooting requirements of special environments.

[0082] according to Figure 5 The relative illumination curve of the large aperture TOF lens 1 shown indicates that the relative illumination of the lens is greater than 80%, the image brightness is uniform, and there are no dark corners at the edges.

[0083] Example 2

[0084] Figure 7 This is the lens cross-section of the large aperture TOF lens 2 in this embodiment. Compared with Embodiment 1, the main difference in this embodiment is that the optical parameters such as the radius of curvature and lens thickness of each lens surface are different.

[0085] In this embodiment, the field of view (FOV) of the large aperture TOF lens 2 is 62.2°, and the field of view (FNO) is 1.49.

[0086] The relevant parameters of each lens in the large-aperture TOF lens 2 in this embodiment are shown in Table 2-1.

[0087] Table 2-1

[0088]

[0089] The aspherical surface parameters of the large-aperture TOF lens 2 in this embodiment are shown in Table 2-2.

[0090] Table 2-2

[0091]

[0092] In this embodiment, the MTF curves of the large-aperture TOF lens 2 at room temperature (20°C), low temperature (-10°C), and high temperature (60°C) are respectively as follows: Figure 8 , Figure 9 , Figure 10 As shown. Figure 11 This is a relative illumination curve of the large-aperture TOF lens 2 in this embodiment. Figure 12 This is a schematic diagram of the sagittal height of the fourth lens side of the large-aperture TOF lens 2 in this embodiment.

[0093] from Figure 8 , Figure 9 and Figure 10 As can be seen, the large-aperture TOF lens 2 in this embodiment has good image quality under conditions ranging from -10℃ to 60℃, and has effectively corrected the temperature drift problem, thus meeting the shooting requirements in special environments.

[0094] from Figure 11 As can be seen, with a relative illumination greater than 80%, the large aperture TOF lens 2 can ensure uniform brightness in its imaging and eliminate dark corners at the edges.

[0095] Example 3

[0096] Figure 13 This is the lens cross-section of the large aperture TOF lens 3 in this embodiment. Compared with Embodiment 1, the main difference in this embodiment is that the optical parameters such as the radius of curvature and lens thickness of each lens surface are different.

[0097] In this embodiment, the field of view (FOV) of the large-aperture TOF lens 3 is 62.2°, and the field of view (FNO) is 1.46.

[0098] The relevant parameters of each lens in the large-aperture TOF lens 3 in this embodiment are shown in Table 3-1.

[0099]

[0100] The aspherical surface parameters of the large-aperture TOF lens 3 in this embodiment are shown in Table 3-2.

[0101]

[0102]

[0103] In this embodiment, the MTF curves of the large-aperture TOF lens 3 at room temperature (20°C), low temperature (-10°C), and high temperature (60°C) are respectively as follows: Figure 14 , Figure 15 , Figure 16 As shown. Figure 17 This is a relative illumination curve of the large aperture TOF lens 3 in this embodiment. Figure 18 This is a schematic diagram of the sagittal height of the fourth lens side of the large-aperture TOF lens 3 in this embodiment.

[0104] from Figure 14 , Figure 15 and Figure 16 As can be seen, the large-aperture TOF lens 3 in this embodiment has good image quality under conditions ranging from -10℃ to 60℃, and has effectively corrected the temperature drift problem, thus meeting the shooting requirements in special environments.

[0105] from Figure 17 As can be seen, with a relative illumination greater than 80%, the large aperture TOF lens 3 can ensure uniform brightness in its imaging and eliminate dark corners at the edges.

[0106] Example 4

[0107] Figure 19This is the lens cross-section of the large-aperture TOF lens 4 in this embodiment. Compared with Embodiment 1, the main difference in this embodiment is that the optical parameters such as the radius of curvature and lens thickness of each lens surface are different.

[0108] In this embodiment, the large aperture TOF lens 4 has a field of view (FOV) of 62.2° and an aperture (FNO) of 1.48.

[0109] The relevant parameters of each lens in the large-aperture TOF lens 4 in this embodiment are shown in Table 4-1.

[0110]

[0111]

[0112] The aspherical surface parameters of the large-aperture TOF lens 4 in this embodiment are shown in Table 4-2.

[0113] Table 4-2

[0114]

[0115] In this embodiment, the MTF curves of the large-aperture TOF lens 4 at room temperature (20°C), low temperature (-10°C), and high temperature (60°C) are as follows: Figure 20 , Figure 21 , Figure 22 As shown. Figure 23 This is a relative illumination curve of the large-aperture TOF lens 4 in this embodiment. Figure 24 This is a schematic diagram of the sagittal height of the fourth lens side of the large-aperture TOF lens 4 in this embodiment.

[0116] from Figure 20 , Figure 21 and Figure 22 As can be seen, the large-aperture TOF lens 4 in this embodiment has good image quality under conditions ranging from -10℃ to 60℃, and has effectively corrected the temperature drift problem, thus meeting the shooting requirements in special environments.

[0117] from Figure 23 As can be seen, with a relative illumination greater than 80%, the large-aperture TOF lens 4 can ensure uniform brightness in its imaging and eliminate dark corners at the edges.

[0118] This invention discloses the working principle and process of a large-aperture TOF lens. Through specific surface shape settings and reasonable allocation of optical power, the TOF lens structure is relatively compact, effectively shortening the overall length of the lens. The small lens size facilitates the lightweight design of the terminal, while the large aperture provides high image quality and a wide monitoring angle. Simultaneously, the image-side surface of the fourth lens is concave and has a large sagittal, significantly increasing the back focal length. This enhances the back focal compensation of the base for defocusing under high and low temperature conditions, effectively correcting temperature drift and meeting the shooting requirements in special environments.

[0119] In the description of this utility model, it should be understood that terms such as "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0120] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0121] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0122] Although the description of this utility model has been given in conjunction with the specific embodiments described above, it is obvious to those skilled in the art that many substitutions, modifications, and variations can be made based on the above description. Therefore, all such substitutions, modifications, and variations are included within the spirit and scope of the appended claims.

Claims

1. A large-aperture TOF lens, characterized in that, From the object side to the image side along the optical axis, the following are included sequentially: A first lens with negative optical power, wherein the object side of the first lens is convex and the image side is concave; A second lens with positive optical power, wherein the object side of the second lens is convex and the image side is concave; A third lens with positive optical power, wherein the object side of the third lens is concave and the image side is convex; A fourth lens with negative optical power, wherein the object side of the fourth lens is convex and the image side is concave; The first lens, the second lens, the third lens, and the fourth lens are all made of plastic. The large-aperture TOF lens satisfies the following condition: BFL / TTL > 0.35, S 42 / BFL>0.36, where BFL is the axial distance from the center point of the image side of the fourth lens to the imaging surface, TTL is the axial distance from the object side of the first lens to the imaging surface, and S42 is the sagitta of the image side of the fourth lens.

2. The large-aperture TOF lens according to claim 1, characterized in that, The large-aperture TOF lens satisfies the following condition: -7.5 < f1 / f < -5.5, 5.5 < f² / f < 10.0 0.9 < f3 / f < 1.5 -20.0 < f4 / f < -13, Wherein, f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, f4 is the focal length of the fourth lens, and f is the focal length of the large aperture TOF lens.

3. The large-aperture TOF lens according to claim 1, characterized in that, The large-aperture TOF lens satisfies the following condition: 1.6≤Nd1≤1.7, 1.6≤Nd2≤1.7, 1.6≤Nd3≤1.7, 1.6≤Nd4≤1.7, Wherein, Nd1 is the refractive index of the first lens, Nd2 is the refractive index of the second lens, Nd3 is the refractive index of the third lens, and Nd4 is the refractive index of the fourth lens.

4. The large-aperture TOF lens according to claim 1, characterized in that, The object-side surface of the first lens is inverted, and both the object-side surface and the image-side surface of the second lens are inverted.

5. The large-aperture TOF lens according to claim 1, characterized in that, The large-aperture TOF lens satisfies the following condition: 0.4 < f / TTL < 0.6 Where f is the focal length of the large-aperture TOF lens, and TTL is the on-axis distance from the object side of the first lens to the imaging plane.

6. The large-aperture TOF lens according to claim 1, characterized in that... The large-aperture TOF lens satisfies the following condition: 0 < TTL < 4.4 mm, where TTL is the on-axis distance from the object side of the first lens to the imaging surface.

7. The large-aperture TOF lens according to claim 1, characterized in that, The large-aperture TOF lens satisfies the following condition: C31 < 0, C32 < 0, C41 > 0, C42 > 0 Wherein, C31 is the curvature of the center point of the object-side surface of the third lens, C32 is the curvature of the center point of the image-side surface of the third lens, C41 is the curvature of the center point of the object-side surface of the fourth lens, and C42 is the curvature of the center point of the image-side surface of the fourth lens.

8. The large-aperture TOF lens according to claim 1, characterized in that, The large-aperture TOF lens has a field of view greater than 60 degrees.

9. The large-aperture TOF lens according to claim 1, characterized in that, An aperture stop with an aperture value FNO≤1.5 is disposed between the first lens and the second lens.

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