Optical lens and DMS imaging module

Abstract

The embodiment of the invention discloses an optical lens and a DMS imaging module. The optical lens comprises a diaphragm, a first lens, a second lens and a third lens which are sequentially arranged from an object side to an image side along an optical axis; the first lens has positive focal power; the second lens has positive focal power; the third lens has negative focal power; the first to third lenses satisfy the following conditions: 0.13 < = phi 1 / phi < = 0.18; 0.11 < = phi 2 / phi < = 0.35; phi 3 / phi is greater than or equal to-0.32 and less than or equal to-0.05 According to the embodiment of the invention, a conventional lens material is adopted, a three-piece structure is designed, and the shape and the focal power of each lens element and the relative position of each lens element are optimized, so that the total length of the lens is smaller than 8mm, and the optical lens has the characteristics of large image surface, small size, high image quality and the like, can be applied to a DMS system, and has a wide application prospect. Driver monitoring is assisted, and driving safety is guaranteed.

Description

Technical Field

[0001] The present invention relates to the field of optical lens technology, and in particular to an optical lens and a DMS imaging module. Background Technology

[0002] As intelligent driving rapidly evolves towards Level 2+ and above, the primary responsibility for driving is gradually shifting from humans to systems, placing higher demands on the accuracy and robustness of driver status monitoring. The Driver Monitor System (DMS), as a crucial component in ensuring human-machine co-driving safety, must continuously and stably capture subtle features such as the driver's facial micro-expressions, gaze direction, and eyelid status in the complex and ever-changing cabin environment. Its imaging quality directly determines the accuracy of identifying dangerous states such as fatigue and distraction, as well as the timeliness of warnings.

[0003] Currently, traditional DMS optical modules face the dual challenges of excessive length and insufficient image quality due to strict limitations in vehicle space and layout. The industry urgently needs to develop a next-generation DMS optical solution that combines small overall length and high image quality. Summary of the Invention

[0004] This invention provides an optical lens and a DMS imaging module to achieve a large image area and high resolution within a limited space through a compact optical design, thereby providing a more reliable optical perception basis for driving safety in intelligent driving.

[0005] In a first aspect, embodiments of the present invention provide an optical lens, comprising an aperture stop, a first lens, a second lens, and a third lens arranged sequentially along the optical axis from the object side to the image side; the first lens has positive optical power; the second lens has positive optical power; the third lens has negative optical power; and the first lens to the third lens satisfy the following conditions:

[0006] 0.13≦φ1 / φ≦0.18;

[0007] 0.11≦φ2 / φ≦0.35;

[0008] -0.32≦φ3 / φ≦-0.05;

[0009] Wherein, φ is the optical power of the optical lens, and φ1, φ2, and φ3 are the optical powers of the first lens, the second lens, and the third lens, respectively.

[0010] Optionally, the first lens has positive optical power; the second lens has positive optical power; and the third lens has negative optical power.

[0011] Optionally, the first lens is a glass spherical lens; the second lens is a plastic aspherical lens; and the third lens is a plastic aspherical lens.

[0012] Optionally, the object-side surface of the first lens is convex and the image-side surface is concave; the object-side surface of the second lens is concave and the image-side surface is convex; and the object-side surface of the third lens is concave and the image-side surface is convex.

[0013] Optionally, the first lens to the third lens satisfy the following conditions:

[0014] 1.65≦ ≤2.05;

[0015] 1.57≦ ≤1.64;

[0016] 1.43≦ ≤1.72;

[0017] in, , , The refractive indices are, in order, those of the first lens to the third lens.

[0018] Optionally, the first lens to the third lens satisfy the following conditions:

[0019] 1.65≦ ≤2.05; 29.95≦ ≤52.33;

[0020] 1.57≦ ≤1.64; 52.45≦ ≤71.30;

[0021] 1.43≦ ≤1.72; 19.21≤ ≤58.93;

[0022] in, , , These are the dispersion coefficients of the first lens to the third lens, respectively.

[0023] Optionally, the optical lens satisfies the following condition:

[0024] 0.94 ≤ TTL / IC ≤ 1.28;

[0025] Wherein, IC is the image plane diameter of the optical lens, and TTL is the total optical length of the optical lens.

[0026] Optionally, the optical lens satisfies the following condition:

[0027] TTL / EFFL ≤ 1.67;

[0028] Wherein, TTL is the total optical length of the optical lens, and EFFL is the total focal length of the optical lens.

[0029] Optionally, the optical lens satisfies the following condition:

[0030] 2.47≦EFFL / FNO≦2.69;

[0031] Wherein, EFFL is the total focal length of the optical lens, and FNO is the aperture number of the optical lens.

[0032] Optionally, the optical lens satisfies the following condition:

[0033] 1.95 ≤ FNO ≤ 2.05;

[0034] Wherein, FNO is the aperture number of the optical lens.

[0035] Secondly, embodiments of the present invention also provide a DMS imaging module, including the optical lens described in any embodiment of the first aspect.

[0036] The optical lens and DMS imaging module provided in this invention use conventional lens materials and are designed as a three-element structure. By optimizing the shape, optical power, and relative position of each lens element, the total length of the lens is less than 8mm. This results in an optical lens with features such as a large image plane, small size, and high image quality. It can be used in DMS systems to assist in driver monitoring and ensure driving safety. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the structure of an optical lens provided in Embodiment 1 of the present invention;

[0038] Figure 2 for Figure 1 This is a spherical aberration curve of the optical lens shown.

[0039] Figure 3 for Figure 1 This is the ray fan diagram of the optical lens shown.

[0040] Figure 4 This is a schematic diagram of the structure of an optical lens provided in Embodiment 2 of the present invention;

[0041] Figure 5 for Figure 4 This is a spherical aberration curve of the optical lens shown.

[0042] Figure 6 for Figure 4 This is the ray fan diagram of the optical lens shown.

[0043] Figure 7 This is a schematic diagram of the structure of an optical lens provided in Embodiment 3 of the present invention;

[0044] Figure 8 for Figure 7 This is a spherical aberration curve of the optical lens shown.

[0045] Figure 9 for Figure 7 This is the ray fan diagram of the optical lens shown. Detailed Implementation

[0046] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0047] The terminology used in the embodiments of this invention is for the purpose of describing specific embodiments only and is not intended to limit the invention. It should be noted that directional terms such as "upper," "lower," "left," and "right" described in the embodiments of this invention are used to describe the angles shown in the accompanying drawings and should not be construed as limiting the embodiments of this invention. Furthermore, in the context, it should be understood that when referring to an element being formed "on" or "below" another element, it can be formed not only directly on or below the other element, but also indirectly on or below it through intermediate elements. The terms "first," "second," etc., are used for descriptive purposes only and do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0048] The term "comprising" and its variations as used in this invention are open-ended, meaning "including but not limited to". The term "based on" means "at least partially based on". The term "one embodiment" means "at least one embodiment".

[0049] It should be noted that the concepts of "first" and "second" mentioned in this invention are only used to distinguish the corresponding contents and are not used to limit the order or interdependence.

[0050] It should be noted that the terms "a" and "a plurality of" used in this invention are illustrative rather than restrictive. Those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".

[0051] Figure 1 This is a schematic diagram of the structure of an optical lens provided in Embodiment 1 of the present invention, for reference. Figure 1This optical lens is mainly used in DMS systems and specifically includes an aperture stop STO, a first lens 10, a second lens 20, and a third lens 30 arranged sequentially from the object side to the image side along the optical axis. The first lens 10 has positive optical power; the second lens 20 has positive optical power; and the third lens 30 has negative optical power. The first lens 10 to the third lens 30 satisfy the following conditions: 0.13≦φ1 / φ≦0.18; 0.11≦φ2 / φ≦0.35; -0.32≦φ3 / φ≦-0.05; where φ is the optical power of the lens, and φ1, φ2, and φ3 are the optical powers of the first lens 10, the second lens 20, and the third lens 30, respectively.

[0052] First, for optical lenses, optical power equals the difference between the image-side beam convergence and the object-side beam convergence; it characterizes the optical system's ability to deflect light. The larger the absolute value of optical power, the stronger the bending ability of light; the smaller the absolute value, the weaker the bending ability. When optical power is positive, the refraction of light is converging; when optical power is negative, the refraction of light is diverging. Optical power can be used to characterize a single refractive surface of a lens (i.e., one surface of the lens), a single lens, or a system formed by multiple lenses (i.e., a lens group).

[0053] Secondly, the optical lens provided in this embodiment is mainly used in DMS systems, and this optical lens can set all lenses in one lens barrel ( Figure 1 (not shown in the image) such as Figure 1 As shown, in this embodiment of the invention, an optical lens is designed by using three lenses to form an optical lens, and by coordinating the optical power of these three lenses, a simple, miniaturized, and stable optical lens design is achieved. Specifically, the three glass spheres are allocated with positive and negative optical power, and the ratio of optical power of each lens to the optical lens is limited to meet certain conditions. This allows light to propagate smoothly, preventing excessive refraction on any one surface, resulting in good image quality, reduced aberrations, lower sensitivity, and a compact structure, achieving a large field of view and miniaturization.

[0054] In one specific embodiment, optionally, the first lens 10 is a glass spherical lens; the second lens 20 is a plastic aspherical lens; and the third lens 30 is a plastic aspherical lens.

[0055] In this embodiment of the invention, the first lens 10, located at the front of the lens, is set as a glass spherical lens. This utilizes the characteristics of glass material to achieve a higher Abbe number, which is beneficial for eliminating chromatic aberration. On the other hand, it can reduce the sensitivity of imaging to temperature, reduce the degree of lens deformation at different temperatures, and ensure clear imaging even in high and low temperature environments. The second lens 20 and the third lens 30 are set as plastic aspherical lenses. This can take advantage of the lower manufacturing difficulty of plastic lenses during the fabrication of these aspherical lenses, which helps to reduce manufacturing costs and achieve mass production. They have the advantages of being inexpensive, easy to process, and lightweight. Furthermore, the aspherical surface shape can be used to better correct aberrations, reduce distortion, increase illumination, and reduce the number of lenses in the optical system.

[0056] In one specific embodiment, optionally, the object-side surface of the first lens 10 is convex and the image-side surface is concave; the object-side surface of the second lens 20 is concave and the image-side surface is convex; and the object-side surface of the third lens 30 is concave and the image-side surface is convex.

[0057] In this embodiment, the specific shapes of the front and rear surfaces of each lens are limited to convex or concave to control various aberrations by utilizing the specific morphology of each lens surface. For example, by setting the object-side surface of the first lens 10 to convex and the image-side surface of the third lens 30 to concave, i.e., adopting a front-convex and rear-concave structure, the convex front surface can be used to quickly focus light, reducing the size of the rear lens group, while avoiding the decrease in edge resolution due to beam divergence. The concave rear surface can be used to quickly converge the beam, shortening the physical length and reducing the overall optical length and volume. As another example, by setting the second lens 20 in the middle position to have a concave front surface and a convex rear surface, the convex surface can be used to counteract the edge distortion and chromatic aberration caused by the concave surface magnifying the image, thereby achieving a balance of aberrations.

[0058] In one specific embodiment, optionally, the first lens 10 to the third lens 30 satisfy the following condition: 1.65 ≤ ≤2.05; 1.57≦ ≤1.64; 1.43≦ ≤1.72; where, , , The refractive indices of the first lens 10 to the third lens 30 are respectively.

[0059] In one specific embodiment, optionally, the first lens 10 to the third lens 30 satisfy the following condition: 1.65 ≤ ≤2.05; 29.95≦ ≤52.33; 1.57≤ ≤1.64; 52.45≦ ≤71.30; 1.43 ≤ ≤1.72; 19.21≤ ≤58.93; among which, , , The dispersion coefficients are, in order, those of the first lens 10 to the third lens 30.

[0060] Under the above conditions, by properly allocating optical power and combining it with an appropriate refractive index and Abbe number, system aberrations can be effectively corrected and the resolving power of the lens can be improved.

[0061] In one specific embodiment, the optical lens may optionally satisfy the following condition: 0.94≦TTL / IC≦1.28; where IC is the image plane diameter of the optical lens and TTL is the total optical length of the optical lens.

[0062] In this embodiment, by setting the optical lens to meet the above conditions, the ratio between the structural size of the optical system and the imaging range can be reasonably controlled, which helps to ensure sufficient image plane coverage while achieving a compact design, improve the system integration applicability and maintain good image plane illumination uniformity.

[0063] In one specific embodiment, optionally, the optical lens satisfies the following condition: TTL / EFFL≦1.67; where TTL is the total optical length of the optical lens, and EFFL is the total focal length of the optical lens.

[0064] In this embodiment, by setting the optical lens to meet the above conditions, the relationship between the total optical length and the focal length of the optical lens is limited. While satisfying the field of view range of the optical lens, the total optical length of the optical lens can be controlled, thereby achieving the miniaturization design of the optical lens.

[0065] In one specific embodiment, optionally, the optical lens satisfies the following condition: 2.47≦EFFL / FNO≦2.69; where EFFL is the total focal length of the optical lens, and FNO is the aperture number of the optical lens.

[0066] By setting the optical lens to meet the above conditions, the optical system can achieve high imaging brightness and improve performance in low-light environments, while effectively suppressing spherical aberration and astigmatism caused by large aperture, ensuring that the optical system has excellent contrast and resolution throughout the entire field of view.

[0067] In one specific embodiment, the optical lens may optionally satisfy the following condition: 1.95 ≤ FNO ≤ 2.05; where FNO is the aperture number of the optical lens.

[0068] Among them, the aperture number can be used to measure the amount of light entering the lens. A smaller aperture number will bring in more light. By setting the FNO to meet the above conditions, it indicates that the optical lens can have a suitable amount of light entering the lens, which is conducive to clear imaging.

[0069] The optical lens provided in this embodiment of the invention uses conventional lens materials and is designed as a 3-element structure. By optimizing the shape, optical power, and relative position of each lens element, the total length of the lens is less than 8mm. This results in an optical lens with features such as a large image area, small size, and high image quality. It can be used in DMS systems to assist in driver monitoring and ensure driving safety.

[0070] Based on the same concept described above, this invention provides three different specific embodiments, the optical power relationship and related physical optical parameter design ranges of which are shown in Table 1:

[0071] Table 1. Optical power relationship of each lens and design values ​​of related physical and optical parameters in the three embodiments.

[0072]

[0073] In Embodiment 1 of the present invention, reference is made to Figure 1 Knowing the structure, shape, and location of each component in the system is crucial. In this first embodiment, the aperture stop STO is located on the object side of the first lens 10. Furthermore, a planar glass 40 is provided along the object plane to the image plane; the planar glass 40 is located on the image-side surface of the third lens 30, and it protects the photosensitive chip in the imaging sensor. The optical performance parameters of this lens are as follows: focal length EFFL of 5.13mm, field of view of 64.8°, and aperture of F2.02. Figure 1 The parameter design values ​​of each lens in the optical lens of Embodiment 1 are shown in Table 2:

[0074] Table 2. Design parameters of each lens in the optical lens of Example 1

[0075]

[0076] The surface numbers in Table 2 are assigned according to the surface sequence of each lens. "STO" represents the aperture stop of the lens; the radius of curvature represents the curvature of the lens surface, with a positive value indicating that the surface bends towards the image plane and a negative value indicating that the surface bends towards the object plane. "PL" indicates that the surface is flat and the radius of curvature is infinite; the thickness represents the central axial distance between the current surface and the next surface. Since the different number of digits of each parameter value can cause focusing errors, the S11 thickness has a certain range and can be adjusted as needed to achieve a clear focus; the refractive index represents the ability of the material between the current surface and the next surface to deflect light. A blank space indicates that the current position is air and the refractive index is 1.

[0077] The aspherical lenses in Table 2 satisfy the following formula:

[0078] ;

[0079] Where z represents the axial sagitta in the Z-direction of the aspherical surface; r represents the distance from a point on the aspherical surface to the optical axis; c represents the curvature of the fitted sphere, numerically the reciprocal of the radius of curvature; k represents the fitted conic coefficients; A, B, C, D, E, F, and G represent the 4th, 6th, 8th, 10th, 12th, 14th, and 16th order coefficients of the aspherical polynomial, respectively. The coefficient values ​​for each aspherical surface in the above embodiment are shown in Table 3.

[0080] Table 3 Aspherical parameters of each lens in the optical lens of Example 1

[0081]

[0082] Where -9.56E-02 indicates that the coefficient k of surface number S1 is -9.56 × 10⁻⁶. -2 And so on.

[0083] Figure 2 for Figure 1 This is a spherical aberration curve diagram of the optical lens shown. The vertical direction represents the normalized 0-field pupil plane, where 0 represents the pupil center, and the vertical vertex represents the pupil vertex. The horizontal direction represents the spherical aberration at different wavelengths, in millimeters (mm). Different linear curves in the diagram represent different wavelengths of the system's imaging. Figure 2 It can be seen that the spherical aberration of different wavelengths is controlled within the range of (-0.02mm, +0.02mm), indicating that the spherical aberration of the glass-plastic hybrid optical lens is well controlled at each wavelength, which can meet the requirements of wide spectrum applications, and also reflects that the glass-plastic hybrid optical lens has day and night confocal function.

[0084] Figure 3 for Figure 1This is the ray fan plot of the optical lens shown. Firstly, the ray fan plot is one of the commonly used evaluation methods by optical designers. In a single plot, the horizontal axis represents the normalized beam aperture, and the vertical axis represents the transverse aberration. Ideally, each curve should completely coincide with the horizontal axis, at which point all rays in that field of view focus at the same point on the image plane. The vertical axis in a single image can also represent the maximum dispersion range of the beam on the ideal image plane. The ray fan plot can reflect not only monochromatic aberration at different wavelengths but also the magnitude of transverse chromatic aberration. Figure 3 It can be seen that this optical lens closely approximates the horizontal axis at all wavelengths across all fields of view, indicating that its transverse aberrations at each wavelength are well corrected. Furthermore, the curves for each color do not show significant dispersion, indicating that this optical lens also provides good correction for chromatic aberration, meeting the requirements for its use.

[0085] Figure 4 This is a schematic diagram of an optical lens structure provided in Embodiment 2 of the present invention. In Embodiment 2 of the present invention, reference is made to... Figure 4 Knowing the structure, shape, and location of each component in the system is crucial. In this second embodiment, the aperture stop STO is located on the object side of the first lens 10. Furthermore, a planar glass 40 is provided along the object plane to the image plane; the planar glass 40 is located on the image-side surface of the third lens 30, and it protects the photosensitive chip in the imaging sensor. The optical performance parameters of this lens are as follows: focal length EFFL is 5.08mm, field of view is 64.8°, and aperture is F2.01. Figure 4 The parameter design values ​​of each lens in the optical lens of Embodiment 2 are shown in Table 4:

[0086] Table 4. Design parameters of each lens in the optical lens of Example 2

[0087]

[0088] The surface numbers in Table 4 are assigned according to the surface sequence of each lens. "STO" represents the aperture stop of the lens; the radius of curvature represents the curvature of the lens surface, with a positive value indicating that the surface bends towards the image plane and a negative value indicating that the surface bends towards the object plane. "PL" indicates that the surface is flat and the radius of curvature is infinite; the thickness represents the central axial distance between the current surface and the next surface. Since the different number of digits of each parameter value can cause focusing errors, the S11 thickness has a certain range and can be adjusted as needed to achieve a clear focus; the refractive index represents the ability of the material between the current surface and the next surface to deflect light. A blank space indicates that the current position is air and the refractive index is 1.

[0089] The aspherical lenses in Table 4 satisfy the following formula:

[0090] ;

[0091] Where z represents the axial sagitta in the Z-direction of the aspherical surface; r represents the distance from a point on the aspherical surface to the optical axis; c represents the curvature of the fitted sphere, numerically the reciprocal of the radius of curvature; k represents the fitted conic coefficients; A, B, C, D, E, F, and G represent the 4th, 6th, 8th, 10th, 12th, 14th, and 16th order coefficients of the aspherical polynomial, respectively. The coefficient values ​​for each aspherical surface in the above embodiment two are shown in Table 5.

[0092] Table 5 Aspherical parameters of each lens in the optical lens of Example 2

[0093]

[0094] Where 6.26E-03 indicates that the coefficient A of surface number S1 is 6.26 × 10⁻⁶. -3 And so on.

[0095] Figure 5 for Figure 4 This is a spherical aberration curve diagram of the optical lens shown. The vertical direction represents the normalized 0-field pupil plane, where 0 represents the pupil center, and the vertical vertex represents the pupil vertex. The horizontal direction represents the spherical aberration at different wavelengths, in millimeters (mm). Different linear curves in the diagram represent different wavelengths of the system's imaging. Figure 5 It can be seen that the spherical aberration of different wavelengths is controlled within the range of (-0.03mm, +0.03mm), indicating that the spherical aberration of the glass-plastic hybrid optical lens is well controlled at each wavelength, which can meet the requirements of wide spectrum applications, and also reflects that the glass-plastic hybrid optical lens has day and night confocal function.

[0096] Figure 6 for Figure 4 This is the ray fan plot of the optical lens shown. Firstly, the ray fan plot is one of the commonly used evaluation methods by optical designers. In a single plot, the horizontal axis represents the normalized beam aperture, and the vertical axis represents the transverse aberration. Ideally, each curve should completely coincide with the horizontal axis, at which point all rays in that field of view focus at the same point on the image plane. The vertical axis in a single image can also represent the maximum dispersion range of the beam on the ideal image plane. The ray fan plot can reflect not only monochromatic aberration at different wavelengths but also the magnitude of transverse chromatic aberration. Figure 6 It can be seen that this optical lens closely approximates the horizontal axis at all wavelengths across all fields of view, indicating that its transverse aberrations at each wavelength are well corrected. Furthermore, the curves for each color do not show significant dispersion, indicating that this optical lens also provides good correction for chromatic aberration, meeting the requirements for its use.

[0097] Figure 7 This is a schematic diagram of an optical lens structure provided in Embodiment 3 of the present invention. In Embodiment 3 of the present invention, reference is made to... Figure 7 Knowing the structure, shape, and location of each component in the system is crucial. In this third embodiment, the aperture stop STO is located on the object side of the first lens 10. Furthermore, a planar glass 40 is provided along the object plane to the image plane; the planar glass 40 is located on the image-side surface of the third lens 30, and it protects the photosensitive chip in the imaging sensor. The optical performance parameters of this lens are as follows: focal length EFFL of 5.08mm, field of view of 64.8°, and aperture of F2.01. Figure 7 The parameter design values ​​of each lens in the optical lens of Embodiment 3 are shown in Table 6:

[0098] Table 6. Design values ​​of parameters for each lens in the optical lens of Example 3.

[0099]

[0100] The surface numbers in Table 6 are assigned according to the surface sequence of each lens. "STO" represents the aperture stop of the lens; the radius of curvature represents the curvature of the lens surface, with a positive value indicating that the surface bends towards the image plane and a negative value indicating that the surface bends towards the object plane. "PL" indicates that the surface is flat and the radius of curvature is infinite; the thickness represents the central axial distance between the current surface and the next surface. Since the different number of digits of each parameter value can cause focusing errors, the S11 thickness has a certain range and can be adjusted as needed to achieve a clear focus; the refractive index represents the ability of the material between the current surface and the next surface to deflect light. A blank space indicates that the current position is air and the refractive index is 1.

[0101] The aspherical lenses in Table 6 satisfy the following formula:

[0102] ;

[0103] Where z represents the axial sagitta in the Z-direction of the aspherical surface; r represents the distance from a point on the aspherical surface to the optical axis; c represents the curvature of the fitted sphere, numerically the reciprocal of the radius of curvature; k represents the fitted conic coefficients; A, B, C, D, E, F, and G represent the 4th, 6th, 8th, 10th, 12th, 14th, and 16th order coefficients of the aspherical polynomial, respectively. The coefficient values ​​for each aspherical surface in the above embodiment three are shown in Table 7.

[0104] Table 7 Aspherical parameters of each lens in the optical lens of Example 3

[0105]

[0106] Where -4.66E-03 indicates that the coefficient A of surface number S1 is -4.66 × 10⁻⁶. -3 And so on.

[0107] Figure 8 for Figure 7 This is a spherical aberration curve diagram of the optical lens shown. The vertical direction represents the normalized 0-field pupil plane, where 0 represents the pupil center, and the vertical vertex represents the pupil vertex. The horizontal direction represents the spherical aberration at different wavelengths, in millimeters (mm). Different linear curves in the diagram represent different wavelengths of the system's imaging. Figure 8 It can be seen that the spherical aberration of different wavelengths is controlled within the range of (-0.03mm, +0.03mm), indicating that the spherical aberration of the glass-plastic hybrid optical lens is well controlled at each wavelength, which can meet the requirements of wide spectrum applications, and also reflects that the glass-plastic hybrid optical lens has day and night confocal function.

[0108] Figure 9 for Figure 7 This is the ray fan plot of the optical lens shown. Firstly, the ray fan plot is one of the commonly used evaluation methods by optical designers. In a single plot, the horizontal axis represents the normalized beam aperture, and the vertical axis represents the transverse aberration. Ideally, each curve should completely coincide with the horizontal axis, at which point all rays in that field of view focus at the same point on the image plane. The vertical axis in a single image can also represent the maximum dispersion range of the beam on the ideal image plane. The ray fan plot can reflect not only monochromatic aberration at different wavelengths but also the magnitude of transverse chromatic aberration. Figure 9 It can be seen that this optical lens closely approximates the horizontal axis at all wavelengths across all fields of view, indicating that its transverse aberrations at each wavelength are well corrected. Furthermore, the curves for each color do not show significant dispersion, indicating that this optical lens also provides good correction for chromatic aberration, meeting the requirements for its use.

[0109] Based on the same concept, this invention also provides a DMS imaging module. The DMS imaging module of this invention includes the optical lens provided in any of the above embodiments, and can be applied in various in-vehicle scenarios to continuously and stably capture subtle features such as the driver's facial micro-expressions, gaze direction, and eyelid state in complex and changing cabin environments. This allows for accurate identification and early warning of dangerous states such as fatigue and distraction, ensuring human-machine collaborative driving safety. It should be noted that since the DMS imaging module in this embodiment uses the optical lens described in the above embodiments, the DMS imaging module provided in this embodiment also has the same or similar beneficial effects as the aforementioned optical lens, which will not be elaborated further here.

[0110] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, combinations, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. An optical lens, characterized in that, The system comprises an aperture stop, a first lens, a second lens, and a third lens arranged sequentially from the object side to the image side along the optical axis; the first lens has positive optical power; the second lens has positive optical power; and the third lens has negative optical power; the first lens to the third lens satisfy the following conditions: 0.13≦φ1 / φ≦0.18; 0.11≦φ2 / φ≦0.35; -0.32≦φ3 / φ≦-0.05; Wherein, φ is the optical power of the optical lens, and φ1, φ2, and φ3 are the optical powers of the first lens, the second lens, and the third lens, respectively.

2. The optical lens according to claim 1, characterized in that, The first lens is a glass spherical lens; the second lens is a plastic aspherical lens; and the third lens is a plastic aspherical lens.

3. The optical lens according to claim 1, characterized in that, The first lens has a convex object-side surface and a concave image-side surface; the second lens has a concave object-side surface and a convex image-side surface; the third lens has a concave object-side surface and a convex image-side surface.

4. The optical lens according to claim 1, characterized in that, The first lens to the third lens satisfy the following conditions: 1.65≦ ≦2.05； 1.57≦ ≦1.64； 1.43≦ ≦1.72； in, , , The refractive indices are, in order, those of the first lens to the third lens.

5. The optical lens according to claim 1, characterized in that, The first lens to the third lens satisfy the following conditions: 1.65≦ ≦2.05；29.95≦ ≦52.33； 1.57≦ ≦1.64；52.45≦ ≦71.30； 1.43≦ ≦1.72；19.21≦ ≦58.93； in, , , These are the dispersion coefficients of the first lens to the third lens, respectively.

6. The optical lens according to claim 1, characterized in that, The optical lens satisfies the following conditions: 0.94 ≤ TTL / IC ≤ 1.28; Wherein, IC is the image plane diameter of the optical lens, and TTL is the total optical length of the optical lens.

7. The optical lens according to claim 1, characterized in that, The optical lens satisfies the following conditions: TTL / EFFL ≤ 1.67; Wherein, TTL is the total optical length of the optical lens, and EFFL is the total focal length of the optical lens.

8. The optical lens according to claim 1, characterized in that, The optical lens satisfies the following conditions: 2.47≦EFFL / FNO≦2.69; Wherein, EFFL is the total focal length of the optical lens, and FNO is the aperture number of the optical lens.

9. The optical lens according to claim 1, characterized in that, The optical lens satisfies the following conditions: 1.95 ≤ FNO ≤ 2.05; Wherein, FNO is the aperture number of the optical lens.

10. A DMS imaging module, characterized in that, Includes the optical lens as described in any one of claims 1-9.

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