Infrared optical system and vehicle lens

Abstract

The utility model discloses an infrared optical system and vehicle -mounted camera lens, wherein, infrared optical system includes: the first lens with negative focal length and glass spherical surface that is arranged in proper order from object side to image side along the optical axis, the second lens with positive or negative focal length and plastic aspheric surface, diaphragm, the third lens with positive focal length and glass spherical surface and the fourth lens with positive or negative focal length and plastic aspheric surface. Through adopting 2G2P's technical scheme, namely adopting the mode of glass plastic combination, and the focal length of reasonable distribution each lens, can well correct aberration, guarantee enough good image quality, and stable high low temperature resolving, wherein, the total length of optical system is less than 9.4mm, and the image surface diameter can reach 4.8mm, and FOV can reach 64 DEG, and further, the total length of the vehicle -mounted camera lens is short, and the volume is small, and the field of view is big, has good commercial value.

Description

Technical Field

[0001] This utility model relates to the field of optical lens technology, and in particular to an infrared optical system and a vehicle-mounted lens. Background Technology

[0002] Automotive intelligence is one of the important directions for future industry development. As the eyes of automotive intelligence, in-vehicle cameras provide drivers with content and services during driving, improving driving safety, comfort, and convenience. In-vehicle DMS lenses, as an important component of in-vehicle cameras, have been continuously progressing towards higher precision, higher adaptability, miniaturization, and intelligence. However, current in-vehicle cameras, while pursuing miniaturization, suffer from significant overall lens aberrations, hindering the achievement of high-quality imaging. Utility Model Content

[0003] This invention provides an infrared optical system and a vehicle-mounted lens with a total optical length of less than 9.4 mm and an image plane diameter of 4.8 mm. It features small aberrations, good adaptability, and miniaturization.

[0004] According to one aspect of the present invention, an infrared optical system is provided, comprising: a first lens having negative optical power and being a glass spherical surface, a second lens having positive or negative optical power and being a plastic aspherical surface, an aperture, a third lens having positive optical power and being a glass spherical surface, and a fourth lens having positive or negative optical power and being a plastic aspherical surface, arranged sequentially along the optical axis from the object side to the image side.

[0005] Optionally, the first lens is a meniscus lens with a convex object side and a concave image side; the second lens is a meniscus lens with a concave object side and a convex image side; the third lens has a convex object side and either a concave or convex image side; and the fourth lens has a concave object side and a convex image side.

[0006] Optionally, the optical power of each of the first to fourth lenses is... Optical power of the infrared optical system The following conditions must be met:

[0007] Where i is a natural number, and 1≤i≤4.

[0008] Optionally, the refractive index ni of each of the first to fourth lenses satisfies:

[0009] 1.49≤n1≤1.74;1.44≤n2≤1.64;1.73≤n3≤1.98;1.42≤n4≤1.62, where i is a natural number and 1≤i≤4.

[0010] Optionally, the Abbe number vi of each lens from the first lens to the fourth lens satisfies:

[0011] 54.40≤v1≤62.30;55.00≤v2≤57.00;40.20≤v3≤42.70;63.20≤v4≤65.20, where i is a natural number and 1≤i≤4.

[0012] Optionally, the back focal length BFL of the infrared optical system and the total optical length TTL of the infrared optical system satisfy the condition: BFL / TTL > 0.28.

[0013] Optionally, the field of view (FOV) of the infrared optical system is greater than 64°.

[0014] Optionally, the total optical length (TTL) of the infrared optical system is less than 9.4 mm.

[0015] Optionally, the aspherical formulas for calculating the aspherical coefficients of the second lens and the fourth lens are as follows:

[0016]

[0017] 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, which is numerically the reciprocal of the radius of curvature; k represents the fitted conic coefficients; and 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.

[0018] According to another aspect of the present invention, a vehicle-mounted lens is provided, including the infrared optical system described in any embodiment of the present invention.

[0019] According to the embodiments of this utility model, an infrared optical system and a vehicle-mounted lens are proposed. The infrared optical system includes: a first lens with negative optical power and a glass spherical surface, arranged sequentially along the optical axis from the object side to the image side; a second lens with positive or negative optical power and a plastic aspherical surface; an aperture; a third lens with positive optical power and a glass spherical surface; and a fourth lens with positive or negative optical power and a plastic aspherical surface. By adopting a 2G2P technical solution, that is, using a glass-plastic combination and reasonably distributing the optical power of each lens, aberrations can be well corrected, ensuring sufficiently good image quality and stable high and low temperature resolution. The total length of this optical system is less than 9.4 mm, the image plane diameter can reach 4.8 mm, and the field of view can reach 64°. Therefore, this vehicle-mounted lens has a short total length, small size, and large field of view, and has good commercial value.

[0020] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this utility model, nor is it intended to limit the scope of this utility model. Other features of this utility model will become readily apparent from the following description. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the infrared optical system proposed in Embodiment 1 of this utility model;

[0023] Figure 2 This is the optical sector diagram of the infrared optical system proposed in Embodiment 1 of this utility model;

[0024] Figure 3 This is the axial chromatic aberration diagram of the infrared optical system proposed in Embodiment 1 of this utility model;

[0025] Figure 4 This is a schematic diagram of the infrared optical system proposed in Embodiment 2 of this utility model;

[0026] Figure 5 This is the fan-shaped diagram of the infrared optical system proposed in Embodiment 2 of this utility model;

[0027] Figure 6 This is the axial chromatic aberration diagram of the infrared optical system proposed in Embodiment 2 of this utility model;

[0028] Figure 7 This is a schematic diagram of the infrared optical system proposed in Embodiment 3 of this utility model;

[0029] Figure 8 This is the optical sector diagram of the infrared optical system proposed in Embodiment 3 of this utility model;

[0030] Figure 9 This is the axial chromatic aberration diagram of the infrared optical system proposed in Embodiment 3 of this utility model. Detailed Implementation

[0031] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0032] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this utility model are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this utility model described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion.

[0033] An infrared optical system according to one aspect of this utility model includes: a first lens having negative optical power and being a glass spherical surface, a second lens having positive or negative optical power and being a plastic aspherical surface, an aperture, a third lens having positive optical power and being a glass spherical surface, and a fourth lens having positive or negative optical power and being a plastic aspherical surface, arranged sequentially along the optical axis from the object side to the image side.

[0034] This infrared optical system employs a 2G2P structure, combining glass spherical lenses and plastic aspherical lenses. The lens design is achieved through a rational allocation of optical power and material selection. The use of plastic aspherical lenses reduces the lens's design cost. Furthermore, the combination of glass spherical and plastic aspherical lenses optimizes the lens's optical performance.

[0035] In one embodiment, the infrared optical system includes a first lens, a second lens, an aperture stop, a third lens, and a fourth lens arranged sequentially along the optical axis from the object side to the image side, with optical powers of negative, positive, positive, and positive, respectively.

[0036] In another embodiment, the infrared optical system includes a first lens, a second lens, an aperture stop, a third lens, and a fourth lens arranged sequentially along the optical axis from the object side to the image side, with optical powers of negative, negative, positive, and positive, respectively.

[0037] In yet another embodiment, the infrared optical system includes a first lens, a second lens, an aperture stop, a third lens, and a fourth lens arranged sequentially along the optical axis from the object side to the image side, with optical powers of negative, negative, positive, and negative, respectively.

[0038] In another embodiment, the infrared optical system includes a first lens, a second lens, an aperture stop, a third lens, and a fourth lens arranged sequentially along the optical axis from the object side to the image side, with optical powers of negative, positive, positive, and negative, respectively.

[0039] In the above embodiments, the infrared optical system further includes a filter, a flat glass plate, and an image plane arranged sequentially along the optical axis from the object side to the image side. The filter is positioned close to the fourth lens, and the image plane is positioned away from the fourth lens. The filter filters out other stray light and transmits infrared light, enabling the infrared optical system to perform imaging based on infrared light.

[0040] It is understandable that optical power is equal to the difference between the convergence of the image-side beam and the convergence of the object-side beam; it characterizes the ability of an optical system to deflect light. The larger the absolute value of the optical power, the stronger the bending ability of light; the smaller the absolute value, the weaker the bending ability. When the optical power is positive, the refraction of light is converging; when the 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). In the infrared optical system provided in this embodiment, each lens can be fixed inside a lens barrel (not shown in the figure).

[0041] The first lens has a negative optical power, allowing more light to enter the optical system and ensuring a wider field of view. The second lens has either a negative or positive optical power. When the second lens has a negative optical power, it diverges the light entering the first lens, resulting in a larger beam divergence angle, which further increases the lens's field of view. When the second lens has a positive optical power, it contracts the light entering the first lens, ensuring smooth propagation without excessive deflection, thus improving image quality and facilitating miniaturized lens design, reducing the lens's aperture and overall length. The third lens has a positive optical power, contracting the light passing through the aperture stop, ensuring smooth propagation without excessive deflection, further improving image quality and facilitating miniaturized lens design. The fourth lens has either a negative or positive optical power. When the fourth lens has a negative optical power, it diverges the light entering the fourth lens, resulting in a larger beam divergence angle, allowing the light to reach the image sensor on the image side, thus expanding the imaging range. When the fourth lens has a positive optical power, it can compress the light entering the fourth lens, so that the light can be transmitted smoothly backward during propagation without excessive deflection. This is beneficial to improving image quality and reducing the aperture and overall length of the lens.

[0042] Furthermore, the first lens is a glass spherical mirror, the second lens is a plastic aspherical mirror, the third lens is a glass spherical mirror, and the fourth lens is a plastic aspherical mirror. Since the refractive index of glass is generally higher than that of plastic, this alternating arrangement allows the dispersion characteristics of glass and plastic to counteract wavelength separation during light refraction, reducing residual chromatic aberration. For example, the glass spherical mirror corrects the primary chromatic aberration, while the plastic aspherical mirror corrects edge dispersion. This minimizes the chromatic aberration of the entire infrared optical system. Moreover, this alternating arrangement allows the glass spherical mirror to achieve basic light refraction, while the plastic aspherical mirror conforms to the edge light trajectory, reducing distortion throughout the infrared optical system. Furthermore, this alternating arrangement contributes to the lightweight design of the overall infrared optical system, reducing its overall design cost.

[0043] This embodiment of the invention employs four lenses. By rationally matching the optical power and materials of each lens, the optical system achieves excellent imaging performance, enabling it to effectively correct aberrations, ensure sufficiently good image quality, and provide stable high and low temperature resolution. Furthermore, the field of view is greater than 64°, and the total optical length meets the TTL ≤ 9.4mm requirement. This results in a small size, low cost, and a large field of view, thus meeting current requirements for the field of view, size, and cost of automotive lenses.

[0044] Optionally, the first lens is a meniscus lens with a convex object side and a concave image side; the second lens is a meniscus lens with a concave object side and a convex image side; the third lens has a convex object side and either a concave or convex image side; and the fourth lens has a concave object side and a convex image side.

[0045] In this embodiment, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the location of the convexity is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the location of the concaveness is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens near the object side is called the object-side surface of the lens, and the surface of each lens near the image side is called the image-side surface of the lens. The surface shape in the paraxial region can be determined according to the judgment method commonly known in the art, using the R value (R refers to the radius of curvature of the paraxial region, usually referring to the R value in the lens database of optical software) to determine concavity and convexity. When the R value is positive, the lens surface is convex towards the object side; when the R value is negative, the lens surface is convex towards the image side.

[0046] In this embodiment, the first lens has an object-side convex towards the object side and an image-side convex towards the object side; the second lens has an object-side convex towards the image side and an image-side convex towards the image side; the third lens has an object-side convex towards the object side and an image-side convex towards either the image or object side; and the fourth lens has an object-side convex towards the image side and an image-side convex towards the image side. This design allows light to enter the optical system more effectively, ensuring smooth propagation without excessive deflection, thus preventing the introduction of greater aberrations. Simultaneously, it helps to reduce the lens aperture and overall length.

[0047] Optionally, the optical power of each of the first to fourth lenses... Optical power of infrared optical systems The following conditions must be met:

[0048] Where i is a natural number, and 1≤i≤4. This is beneficial for achieving a large field of view, small size, and short overall length in infrared optical systems. Specifically, the first lens uses high-refractive-index glass, and when the optical power is set within the aforementioned range, it allows more light to enter the optical system, ensuring a larger field of view. The second lens uses relatively low-refractive-index plastic, and when the optical power is set within the aforementioned range, it corrects chromatic aberration and improves image quality. The third lens uses relatively high-refractive-index glass, and when the optical power is set within the aforementioned range, it effectively reduces light rays, corrects system aberrations, improves image quality, and enables miniaturization. The fourth lens uses relatively low-refractive-index plastic, and when the optical power is set within the aforementioned range, it effectively corrects chromatic aberration, improves image quality, and optimizes the principal ray angle and distortion performance.

[0049] Optionally, the refractive index ni of each of the first to fourth lenses satisfies:

[0050] 1.49≤n1≤1.74; 1.44≤n2≤1.64; 1.73≤n3≤1.98; 1.42≤n4≤1.62, where i is a natural number and 1≤i≤4. This effectively corrects system aberrations and improves imaging quality.

[0051] Optionally, the Abbe number vi of each of the first to fourth lenses satisfies:

[0052] 54.40≤v1≤62.30;55.00≤v2≤57.00;40.20≤v3≤42.70;63.20≤v4≤65.20, where i is a natural number and 1≤i≤4. This effectively corrects system chromatic aberration and improves image quality.

[0053] Optionally, the back focal length (BFL) of the infrared optical system and the total optical length (TTL) of the infrared optical system satisfy the condition: BFL / TTL > 0.28. This ensures that the entire optical system has a compact structure, high integration, and a short total length, while also ensuring sufficient installation space for the imaging chip and filters.

[0054] Optionally, the field of view (FOV) of the infrared optical system is greater than 64°.

[0055] Optionally, the total optical length (TTL) of the infrared optical system is less than 9.4 mm.

[0056] Optionally, the aspherical formulas for calculating the aspherical coefficients of the second lens and the fourth lens are as follows:

[0057]

[0058] 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, which is numerically the reciprocal of the radius of curvature; k represents the fitted conic coefficients; and 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.

[0059] According to another aspect of the present invention, a vehicle-mounted lens is also provided, including an infrared optical system according to any embodiment of the present invention.

[0060] The infrared optical system proposed in this utility model will be described below using specific embodiments one to three.

[0061] The parameter list for the three embodiments in Table 1 is as follows:

[0062]

[0063]

[0064] The formula for aspherical surfaces is shown below:

[0065]

[0066] 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, which is numerically the reciprocal of the radius of curvature; k represents the fitted conic coefficients; and 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.

[0067] Example 1

[0068] Figure 1This is a schematic diagram of the infrared optical system proposed in Embodiment 1 of this utility model. Figure 1 As shown, the infrared optical system includes a first lens L1 with negative optical power and a glass spherical surface, a second lens L2 with negative optical power and a plastic aspherical surface, an aperture STO, a third lens L3 with positive optical power and a glass spherical surface, and a fourth lens L4 with negative optical power and a plastic aspherical surface, arranged sequentially along the optical axis from the object side to the image side, a flat glass PL, an image plane IMA, and a filter (not shown).

[0069] The infrared optical system in this embodiment has a focal length f of 3.310mm, a field of view of 74.4°, an aperture of F2.2, and a total axial length of 9.38554mm.

[0070] Table 2. Design values ​​for each lens in the infrared optical system of Example 1.

[0071]

[0072]

[0073] In Table 2, the surface numbers S1-S12 are assigned according to the surface sequence of each lens. "STO" represents the aperture stop; the radius of curvature represents the curvature of the lens surface, with a positive value indicating that the surface is curved (concave) towards the image plane and a negative value indicating that the surface is curved (concave) 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 thickness of the 13th surface 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.

[0074] Table 3. Design values ​​of aspheric coefficients for the second and fourth lenses in Example 1.

[0075]

[0076] Figure 2 This is the fan plot of the infrared optical system proposed in Embodiment 1 of this utility model. The fan plot is one of the most commonly used evaluation methods in modern optical design. The horizontal axis represents the beam aperture, and the vertical axis represents the transverse aberration. The ideal curve is a straight line coinciding with the horizontal axis, indicating that all light rays are focused at the same point on the image plane. The interval corresponding to the vertical axis of the curve is the maximum dispersion range of the beam on the ideal image plane, with a maximum scaling factor of ±30μm. The fan plot can reflect not only the monochromatic aberration of different wavelengths (where blue represents 920nm, green represents 940nm, and red represents 960nm) but also the magnitude of the transverse chromatic aberration. Figure 2It can be seen that the system closely approximates the horizontal axis at each wavelength in each field of view, indicating that the transverse aberration of each wavelength is well corrected. At the same time, there is no obvious dispersion of each wavelength, indicating that the chromatic aberration of the system is also well corrected, thus ensuring that the optical system can achieve the high-resolution imaging requirements.

[0077] Figure 3 This is the axial chromatic aberration diagram of the infrared optical system proposed in Embodiment 1 of this utility model. For example... Figure 3 As shown, the vertical direction represents the normalized aperture, 0 indicates it is on the optical axis, and the vertical vertex represents the maximum pupil radius (0.7523 mm); the horizontal direction represents the offset relative to the ideal focus, in millimeters (mm). The different linear curves in the figure represent different wavelengths of system imaging (blue represents 920 nm, green represents 940 nm, and red represents 960 nm), derived from... Figure 3 It can be seen that the axial aberrations of different wavelengths are all controlled within the range of (-0.02mm, +0.02mm), indicating that the spherical aberration of the infrared optical system at each wavelength is well controlled and can meet the application requirements.

[0078] Example 2

[0079] Figure 4 This is a schematic diagram of the infrared optical system proposed in Embodiment 2 of this utility model. Figure 4 As shown, the infrared optical system includes a first lens L1 with negative optical power and a glass spherical surface, a second lens L2 with positive optical power and a plastic aspherical surface, an aperture STO, a third lens L3 with positive optical power and a glass spherical surface, and a fourth lens L4 with negative optical power and a plastic aspherical surface, arranged sequentially along the optical axis from the object side to the image side, a flat glass PL, an image plane IMA, and a filter (not shown).

[0080] The infrared optical system proposed in Example 2 has a focal length f of 3.37 mm, a field of view of 74.4°, an aperture of F2.2, and a total axial length of 7.69775 mm.

[0081] Table 4 shows the design values ​​of each lens in the infrared optical system of Example 2.

[0082]

[0083]

[0084] In Table 4, the surface numbers S1-S12 are assigned according to the surface sequence of each lens. "STO" represents the aperture stop; the radius of curvature represents the curvature of the lens surface, with a positive value indicating that the surface is curved (concave) towards the image plane and a negative value indicating that the surface is curved (concave) 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 thickness of the 13th surface 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.

[0085] Table 5. Design values ​​of aspheric coefficients for the second and fourth lenses in Example 2.

[0086]

[0087] Figure 5 This is the fan plot of the infrared optical system proposed in Embodiment 2 of this utility model. The fan plot is one of the most commonly used evaluation methods in modern optical design. The horizontal axis represents the beam aperture, and the vertical axis represents the transverse aberration. The ideal curve is a straight line coinciding with the horizontal axis, indicating that all light rays are focused at the same point on the image plane. The interval corresponding to the vertical axis of the curve is the maximum dispersion range of the beam on the ideal image plane, with a maximum scaling factor of ±30μm. The fan plot can reflect not only the monochromatic aberration of different wavelengths (where blue represents 920nm, green represents 940nm, and red represents 960nm) but also the magnitude of the transverse chromatic aberration. Figure 5 It can be seen that the system closely approximates the horizontal axis at each wavelength in each field of view, indicating that the transverse aberration of each wavelength is well corrected. At the same time, there is no obvious dispersion of each wavelength, indicating that the chromatic aberration of the system is also well corrected, thus ensuring that the optical system can achieve the high-resolution imaging requirements.

[0088] Figure 6 This is the axial chromatic aberration diagram of the infrared optical system proposed in Embodiment 2 of this utility model. For example... Figure 6 As shown, the vertical direction represents the normalized aperture, 0 indicates it is on the optical axis, and the vertical vertex represents the maximum pupil radius (0.7437 mm); the horizontal direction represents the offset relative to the ideal focus, in millimeters (mm). The different linear curves in the figure represent different wavelengths of system imaging (blue represents 920 nm, green represents 940 nm, and red represents 960 nm), derived from... Figure 6 It can be seen that the axial aberrations of different wavelengths are all controlled within the range of (-0.02mm, +0.02mm), indicating that the spherical aberration of the infrared optical system at each wavelength is well controlled and can meet the application requirements.

[0089] Example 3

[0090] Figure 7 This is a schematic diagram of the infrared optical system proposed in Embodiment 3 of this utility model. Figure 7 As shown, the infrared optical system includes a first lens L1 with negative optical power and a glass spherical surface, a second lens L2 with positive optical power and a plastic aspherical surface, an aperture STO, a third lens L3 with positive optical power and a glass spherical surface, and a fourth lens L4 with positive optical power and a plastic aspherical surface, arranged sequentially along the optical axis from the object side to the image side, a flat glass PL, an image plane IMA, and a filter (not shown).

[0091] The infrared optical system proposed in Example 3 has a focal length f of 3.3 mm, a field of view of 74.4°, an aperture of F2.2, and a total axial length of 7.77196 mm.

[0092] Table 6 shows the design values ​​of each lens in the infrared optical system of Example 3.

[0093]

[0094]

[0095] In Table 6, the surface numbers S1-S12 are assigned according to the surface sequence of each lens. "STO" represents the aperture stop; the radius of curvature represents the curvature of the lens surface, with a positive value indicating that the surface is curved (concave) towards the image plane and a negative value indicating that the surface is curved (concave) 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 thickness of the 13th surface 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.

[0096] Table 7. Design values ​​of aspheric coefficients for the second and fourth lenses in Example 3.

[0097] Face number k A B C D E F G S3 2.26E-01 1.21E-02 5.94E-03 -6.72E-03 4.78E-03 3.68E-03 -4.53E-03 1.2E-03 S4 -4.86E-01 3.17E-03 -2.74E-03 7.04E-03 -1.31E-02 1.44E-02 -7.53E-03 1.5E-03 S8 2.80E+00 2.74E-02 3.13E-02 -2.75E-02 1.37E-02 8.23E-03 -1.26E-02 3.8E-03 S9 2.29E+00 5.76E-02 2.77E-02 -9.51E-03 2.68E-03 1.02E-02 -8.55E-03 2.1E-03

[0098] Figure 8This is the fan plot of the infrared optical system proposed in Embodiment 3 of this utility model. The fan plot is one of the most commonly used evaluation methods in modern optical design. The horizontal axis represents the beam aperture, and the vertical axis represents the transverse aberration. The ideal curve is a straight line coinciding with the horizontal axis, indicating that all light rays are focused at the same point on the image plane. The interval corresponding to the vertical axis of the curve is the maximum dispersion range of the beam on the ideal image plane, where the maximum scaling factor is ±22μm. The fan plot can reflect not only the monochromatic aberration of different wavelengths (where blue represents 920nm, green represents 940nm, and red represents 960nm) but also the magnitude of the transverse chromatic aberration. Figure 8 It can be seen that the system closely approximates the horizontal axis at each wavelength in each field of view, indicating that the transverse aberration of each wavelength is well corrected. At the same time, there is no obvious dispersion of each wavelength, indicating that the chromatic aberration of the system is also well corrected, thus ensuring that the optical system can achieve the high-resolution imaging requirements.

[0099] Figure 9 This is the axial chromatic aberration diagram of the infrared optical system proposed in Embodiment 3 of this utility model. For example... Figure 9 As shown, the vertical direction represents the normalized aperture, 0 indicates it is on the optical axis, and the vertical vertex represents the maximum pupil radius (0.7508 mm); the horizontal direction represents the offset relative to the ideal focus, in millimeters (mm). The different linear curves in the figure represent different wavelengths of system imaging (blue represents 920 nm, green represents 940 nm, and red represents 960 nm), derived from... Figure 9 It can be seen that the axial aberrations of different wavelengths are all controlled within the range of (-0.01mm, +0.02mm), indicating that the spherical aberration of the infrared optical system is well controlled at each wavelength and can meet the application requirements.

[0100] In summary, the infrared optical system and vehicle-mounted lens proposed according to the embodiments of this utility model include: a first lens with negative optical power and a glass spherical surface, arranged sequentially along the optical axis from the object side to the image side; a second lens with positive or negative optical power and a plastic aspherical surface; an aperture; a third lens with positive optical power and a glass spherical surface; and a fourth lens with positive or negative optical power and a plastic aspherical surface. By adopting a 2G2P technical solution, i.e., using a glass-plastic combination, and by rationally allocating the optical power of each lens, aberrations can be well corrected, ensuring sufficiently good image quality and stable high and low temperature resolution. The total length of this optical system is less than 9.4 mm, the image plane diameter can reach 4.8 mm, and the field of view can reach 64°. Furthermore, this vehicle-mounted lens has a short total length, small size, and a large field of view, possessing good commercial value.

[0101] The specific embodiments described above do not constitute a limitation on the scope of protection of this utility model. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the scope of protection of this utility model.

Claims

1. An infrared optical system, characterized in that, include: Along the optical axis from the object side to the image side, a first lens with negative optical power and a glass spherical surface, a second lens with positive or negative optical power and a plastic aspherical surface, an aperture, a third lens with positive optical power and a glass spherical surface, and a fourth lens with positive or negative optical power and a plastic aspherical surface are arranged sequentially.

2. The infrared optical system according to claim 1, characterized in that, The first lens is a meniscus lens with a convex object side and a concave image side; the second lens is a meniscus lens with a concave object side and a convex image side; the third lens has a convex object side and either a concave or convex image side; the fourth lens has a concave object side and a convex image side.

3. The infrared optical system according to claim 1, characterized in that, Optical power of each lens from the first lens to the fourth lens Optical power of the infrared optical system The following conditions must be met: Where i is a natural number, and 1≤i≤4.

4. The infrared optical system according to claim 1, characterized in that, The refractive index ni of each lens from the first lens to the fourth lens satisfies: 1.49≤n1≤1.74;1.44≤n2≤1.64;1.73≤n3≤1.98;1.42≤n4≤1.62, where i is a natural number and 1≤i≤4.

5. The infrared optical system according to claim 1, characterized in that, The Abbe number vi of each lens from the first lens to the fourth lens satisfies: 54.40≤v1≤62.30;55.00≤v2≤57.00;40.20≤v3≤42.70;63.20≤v4≤65.20, where i is a natural number and 1≤i≤4.

6. The infrared optical system according to claim 1, characterized in that, The back focal length BFL of the infrared optical system and the total optical length TTL of the infrared optical system satisfy the following condition: BFL / TTL > 0.

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7. The infrared optical system according to claim 1, characterized in that, The field of view (FOV) of the infrared optical system is greater than 64°.

8. The infrared optical system according to claim 1, characterized in that, The total optical length (TTL) of the infrared optical system is less than 9.4 mm.

9. The infrared optical system according to claim 1, characterized in that, The formulas for the aspherical surfaces in the second and fourth lenses are as follows: 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, which is numerically the reciprocal of the radius of curvature; k represents the fitted conic coefficients; and 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.

10. A vehicle-mounted lens, characterized in that, Including the infrared optical system as described in any one of claims 1-9.

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