Infrared optical system, infrared imaging module and sweeping robot

Abstract

The present application provides an infrared optical system, an infrared imaging module, and a floor cleaning robot. The above infrared optical system sequentially includes, along the optical axis from the object side to the image side: a first lens, a second lens, a third lens, and a fourth lens. The first lens has a negative optical power; the third lens has a positive optical power. The object side surface of the third lens is a convex surface, and the image side surface of the third lens is a convex surface. The infrared optical system satisfies the following relational expression: -0.1 < f / R11 < 0, where f represents the effective focal length of the infrared optical system, and R11 represents the curvature radius of the object side surface of the first lens. Since both the object side surface and the image side surface of the third lens are convex surfaces, and according to the relationship between the effective focal length and the curvature radius of the object side surface of the first lens, the (F-θ) distortion value of the infrared optical system can be reduced under the condition of a compact structure, and the relative illuminance value of the image on the imaging surface can be increased, thereby improving the image clarity of the infrared optical system.

Description

Technical Field

[0001] The present invention relates to the technical field of optical imaging, and particularly to an infrared optical system, an infrared imaging module, and a floor cleaning robot. Background Art

[0002] With the development of artificial intelligence technology, in people's daily life and work and learning places, more and more intelligent machines are assisting to complete tasks, improving the efficiency of completing various tasks. Among them, intelligent home appliances have also become the main direction of the development of artificial intelligence, enabling people to be freed from heavy housework. For example, for the cleaning of the floor in a residential house, a floor cleaning robot is usually used for cleaning, which has the characteristics of fast cleaning speed and large cleaning area, and is increasingly favored by household users.

[0003] However, the lenses of traditional floor cleaning robots have problems such as relatively low resolution, too small field of view, and small imaging size, resulting in large distortion during shooting, dark corners or reduced image clarity. In particular, the radial distortion of the collected images is relatively serious, making it impossible for the floor cleaning robot to accurately judge obstacles ahead through the collected images, so that the floor cleaning robot cannot accurately avoid obstacles, resulting in a low obstacle avoidance rate of the floor cleaning robot. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and provide an infrared optical system, an infrared imaging module, and a floor cleaning robot that improve image clarity.

[0005] The purpose of the present invention is achieved by the following technical solutions:

[0006] An infrared optical system sequentially includes, along the optical axis from the object side to the image side: a first lens, a second lens, a third lens, and a fourth lens. Among them, the first lens has a negative optical power; the third lens has a positive optical power, the object side surface of the third lens is a convex surface, and the image side surface of the third lens is a convex surface; the infrared optical system satisfies the following relational expression: -0.1 < f / R11 < 0; where f represents the effective focal length of the infrared optical system, and R11 represents the curvature radius of the object side surface of the first lens.

[0007] In one embodiment, the infrared optical system satisfies the following relational expression: |dist(F - θ)| < 10%; where dist(F - θ) represents the (F - θ) distortion value of the image formed by the infrared optical system on the imaging surface.

[0008] In one embodiment, the infrared optical system satisfies the following relationship: 0.2 < CTmax - CTmin < 0.5; where CTmax represents the thickness value of the lens with the maximum thickness on the optical axis, and CTmin represents the thickness value of the lens with the minimum thickness on the optical axis.

[0009] In one embodiment, the infrared optical system satisfies the following relationship: 1 < R22 / R41 < 6; where R22 represents the radius of curvature of the image-side surface of the second lens, and R41 represents the radius of curvature of the object-side surface of the fourth lens.

[0010] In one embodiment, the infrared optical system satisfies the following relationship: 0.15 < CT3 / TTL < 0.2; where CT3 represents the central thickness of the third lens on the optical axis, and TTL represents the distance on the optical axis from the object side surface of the first lens to the imaging surface of the infrared optical system.

[0011] In one embodiment, the infrared optical system satisfies the following relationship: 4.1 mm < TTL < 4.4 mm.

[0012] In one embodiment, the infrared optical system satisfies the following relationship: 0.3 < SAG12 × n2 < 0.5; where SAG12 represents the distance between the intersection point of the image-side surface of the first lens on the optical axis and the vertical projection point of the position of the maximum effective radius of the first lens on the optical axis, and n2 represents the refractive index of the second lens.

[0013] In one embodiment, the infrared optical system satisfies the following relationship: 1.6 < n2 < 1.7.

[0014] In one embodiment, the infrared optical system further includes an aperture, and the aperture is disposed on the object side of the second lens.

[0015] In one embodiment, the second lens has a positive optical power, and both the object-side surface and the image-side surface of the second lens are convex surfaces.

[0016] An infrared imaging module includes the infrared optical system according to any one of the above embodiments and a photosensitive element, and the photosensitive element is located on the image side of the infrared optical system.

[0017] A floor sweeping robot includes a moving body and the above infrared imaging module, and the infrared imaging module is disposed on the moving body.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] By selecting a smaller number of lenses and limiting the shapes of the object-side surface and the image-side surface of the third lens, that is, both the object-side surface and the image-side surface of the third lens are convex, and based on the relationship between the satisfied effective focal length and the radius of curvature of the object-side surface of the first lens, the field of view of the infrared optical system is increased. At the same time, while ensuring the compact structure of each lens, the (F-θ) distortion value of the infrared optical system is reduced, the relative illumination value of the image on the imaging surface is increased, and thus the image clarity of the infrared optical system is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 This is a schematic structural diagram of the infrared optical system of Example 1 of the present application;

[0022] Figures 2A to 2C They are respectively a spherical aberration curve diagram, an astigmatism curve diagram, an F-θ distortion curve diagram, and a magnification chromatic aberration curve diagram of the infrared optical system of Example 1;

[0023] Figure 3 This is a schematic structural diagram of the infrared optical system according to Example 2 of the present application;

[0024] Figures 4A to 4C They are respectively a spherical aberration curve diagram, an astigmatism curve diagram, an F-θ distortion curve diagram, and a magnification chromatic aberration curve diagram of the infrared optical system of Example 2;

[0025] Figure 5 This is a schematic structural diagram of the infrared optical system of Example 3 of the present application;

[0026] Figures 6A to 6C They are respectively a spherical aberration curve diagram, an astigmatism curve diagram, an F-θ distortion curve diagram, and a magnification chromatic aberration curve diagram of the infrared optical system of Example 3;

[0027] Figure 7 This is a schematic structural diagram of the infrared optical system according to Example 4 of the present application;

[0028] Figures 8A to 8C They are respectively a spherical aberration curve diagram, an astigmatism curve diagram, an F-θ distortion curve diagram, and a magnification chromatic aberration curve diagram of the infrared optical system of Example 4;

[0029] Figure 9 This is a schematic structural diagram of the infrared optical system of Example 5 of the present application;

[0030] Figures 10A to 10C They are respectively a spherical aberration curve diagram, an astigmatism curve diagram, an F-θ distortion curve diagram, and a magnification chromatic aberration curve diagram of the infrared optical system of Example 5;

[0031] Figure 11 This is a schematic structural diagram of the infrared optical system according to Example 6 of the present application;

[0032] 12A to 12C They are respectively a spherical aberration curve diagram, an astigmatism curve diagram, an F-θ distortion curve diagram and a magnification chromatic aberration curve diagram of the infrared optical system of Example 6. DETAILED DESCRIPTION

[0033] To facilitate understanding of the present invention, the present invention will be described more fully below with reference to the accompanying drawings. The accompanying drawings illustrate preferred embodiments of the present invention. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the present disclosure.

[0034] In this specification, the side of an optical element where an object is located is referred to as the object side of the optical element. Correspondingly, the side of the optical element where the image of the object is located is referred to as the image side of the optical element. The surface of each lens closest to the object is called the object side, and the surface of each lens closest to the imaging plane is called the image side. The distance from the object side to the image side is defined as the positive direction.

[0035] In the following description, if a lens surface is convex and the location of the convex surface is unspecified, it means that the lens surface is convex at least near the optical axis. If a lens surface is concave and the location of the concave surface is unspecified, it means that the lens surface is concave at least near the optical axis. Here, the near optical axis refers to the area near the optical axis.

[0036] The features, principles and other aspects of the present application will be described in detail below.

[0037] Please also refer to Figure 1 、 Figure 3 、 Figure 5 、 Figure 7 、 Figure 9 as well as Figure 11 , which is a schematic diagram of the structure of an infrared optical system according to an embodiment of the present invention. The infrared optical system includes four lenses with optical power: a first lens, a second lens, a third lens, and a fourth lens. The four lenses are arranged in order from the object side to the image side along the optical axis. The infrared optical system also includes an infrared filter for filtering out visible light while ensuring the transmission of infrared light. The dotted line represents the straight line along the optical axis.

[0038] The first lens has a negative optical power, and both the object side and the image side of the first lens are concave surfaces; the third lens has a positive optical power, and both the object side and the image side of the third lens are convex surfaces. By setting both the object side and the image side of the third lens as convex surfaces, the third lens has a positive optical power, which facilitates better propagation of light in the infrared optical system. At the same time, it is also convenient to ensure good imaging quality when the structure of the infrared optical system is compact, that is, the total length of the infrared optical system is relatively small.

[0039] In this embodiment, the infrared optical system satisfies the following relationship: -0.1 < f / R11 < 0; where f represents the effective focal length of the infrared optical system, and R11 represents the curvature radius of the object side of the first lens. f / R11 can be -0.098, -0.094, -0.089, -0.081, -0.080 or -0.005. By selecting a smaller number of lenses, the volume of the infrared optical system is reduced. And by defining the shapes of the object side and the image side of the third lens, that is, both the object side and the image side of the third lens are convex surfaces, and according to the relationship between the effective focal length and the curvature radius of the object side of the first lens, the field angle of the infrared optical system is increased, so that while ensuring the compact structure of each lens, the (F-θ) distortion value of the infrared optical system is reduced, the relative illuminance value of the image on the imaging surface is increased, and thus the image clarity of the infrared optical system is improved. Moreover, when reducing the (F-θ) distortion value of the infrared optical system, the field angle of the infrared optical system is increased to be greater than 130°, which is significantly better than the field angle of the traditional optical imaging system, where the field angle of the traditional optical imaging system is 80° - 120°.

[0040] When the above infrared optical system is used for imaging, the light emitted or reflected by the object to be photographed enters the infrared optical system from the object side direction and sequentially passes through the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the infrared filter, and finally converges the infrared light emitted or reflected by the object to be photographed onto the imaging surface, forming an infrared image with a large field angle and a small (F-θ) distortion value, that is, forming a relatively clear infrared image.

[0041] In one embodiment, the infrared optical system satisfies the following relationship: |dist(F-θ)| < 10%; where dist(F-θ) represents the (F-θ) distortion value of the image formed by the infrared optical system on the imaging surface. In this embodiment, by adjusting the ratio of f / R11, the value of dist(F-θ) is changed. For example, |dist(F-θ)| is set to be less than 10%, and |dist(F-θ)| can be 5.238%, 6.660%, 6.895%, 8.252%, 9.450% or 9.824%. In this way, the (F-θ) distortion value of the image formed by the infrared optical system on the imaging surface is further reduced, facilitating the distortion correction of the (F-θ) distortion value of the image formed by the infrared optical system on the imaging surface, thereby increasing the relative illuminance value of the final image on the imaging surface, that is, the brightness of the image is increased, and it has good imaging quality, and further improves the clarity of the image formed by the infrared optical system on the imaging surface.

[0042] In one embodiment, the infrared optical system satisfies the following relationship: 0.2 < CTmax - CTmin < 0.5; where CTmax represents the thickness value of the lens with the maximum thickness on the optical axis, and CTmin represents the thickness value of the lens with the minimum thickness on the optical axis. In this embodiment, CTmax - CTmin can be 0.206, 0.233, 0.279, 0.340, 0.389 or 0.481. The lens thicknesses of each lens are different. According to the shapes of the object side and the image side of each lens, the total length of the lenses in the infrared optical system is changed. In order to reduce the influence on the size of the field angle, by adjusting the total central thickness of each lens on the optical axis, it is convenient for light to propagate better therein, that is, to ensure that the light is close to the optical axis when propagating between the lenses, thereby reducing the (F-θ) distortion value of the image formed by the infrared optical system on the imaging surface, and further improving the clarity of the image formed by the infrared optical system on the imaging surface.

[0043] In one embodiment, the infrared optical system satisfies the following relationship: 1 < R22 / R41 < 6; where R22 represents the radius of curvature of the image-side surface of the second lens, and R41 represents the radius of curvature of the object-side surface of the fourth lens. In this embodiment, R22 / R41 can be 1.019, 1.718, 1.728, 1.786, 2.318, or 5.962. The radius of curvature of the image-side surface of the second lens and the radius of curvature of the object-side surface of the fourth lens are adjusted, that is, the ratio of the radius of curvature of the image-side surface of the second lens to the radius of curvature of the object-side surface of the fourth lens is within a certain range, so that the radius of curvature of the image-side surface of the second lens and the radius of curvature of the object-side surface of the fourth lens are controlled within the range of reducing the (F-θ) distortion value, so that the absolute value of the (F-θ) distortion value of the image formed by the infrared optical system is ensured to be less than 10%, which is convenient for distortion adjustment of the image formed by the infrared optical system, thereby increasing the illuminance value of the image formed by the infrared optical system, and further increasing the clarity of the image formed by the infrared optical system.

[0044] In one embodiment, the infrared optical system satisfies the following relationship: 0.15 < CT3 / TTL < 0.2; where CT3 represents the central thickness of the third lens on the optical axis, and TTL represents the distance on the optical axis from the object-side surface of the first lens to the imaging surface of the infrared optical system, that is, the total optical length of the infrared optical system. In this embodiment, CT3 / TTL can be 0.148, 0.153, 0.155, 0.159, 0.172, or 0.198. The lens thickness of the third lens is CT3. Since both the object-side surface and the image-side surface of the third lens are convex surfaces, the third lens has a positive optical power, so that the light is better focused after passing through the third lens, and then the light is focused near the optical axis, reducing the amplitude of the light deviating from the optical axis, thereby reducing the distortion of the image formed by the infrared optical system on the imaging surface, and further reducing the (F-θ) distortion value of the infrared optical system, which is convenient for distortion adjustment of the image formed by the infrared optical system, thereby increasing the illuminance value of the image formed by the infrared optical system, and further increasing the clarity of the image formed by the infrared optical system. In other embodiments, after the specifications of the third lens are determined, that is, after the lens thickness of the third lens is fixed, the change in the value of TTL is controlled within a certain range. For example, 4.1 mm < TTL < 4.4 mm, ensuring that while reducing the (F-θ) distortion value of the infrared optical system, the total thickness of the four lenses is reduced, thereby reducing the overall volume of the infrared optical system.

[0045] In one embodiment, the infrared optical system satisfies the following relationship: 0.3 < SAG12 × n2 < 0.5; where SAG12 represents the distance between the intersection point of the image side of the first lens on the optical axis and the perpendicular projection point of the maximum effective radius position of the first lens on the optical axis, and n2 represents the refractive index of the second lens. In this embodiment, SAG12 × n2 can be 0.369, 0.418, 0.425, 0.445, 0.452 or 0.485. SAG12 represents the distance between the intersection point of the image side of the first lens on the optical axis and the perpendicular projection point of the maximum effective radius position of the first lens on the optical axis, that is, the sag amount of the image side of the first lens, so that after the light passes through the first lens, the focus of the light reaching the image side of the first lens is close to the optical axis, facilitating the light to converge on the image side of the first lens after passing through the first lens. Thus, under the action of the high refractive index of the second lens, the light further converges towards the optical axis, further reducing the (F-θ) distortion value of the image formed by the infrared optical system, thereby increasing the illuminance value of the image formed by the infrared optical system, and further improving the clarity of the image formed by the infrared optical system. In other embodiments, after the specifications of the first lens are determined, that is, both the object side and the image side of the first lens are concave surfaces, by adjusting the refractive index of the second lens, it is convenient to improve the convergence of light on the optical axis, thereby reducing the distortion of the image formed by the infrared optical system. In the case of a large field angle, the (F-θ) distortion value of the image formed by the infrared optical system is further reduced, and then the relative illuminance value of the image formed by the infrared optical system is increased, the tilt of the image formed by the infrared optical system is improved, and the imaging quality of the infrared optical system is improved.

[0046] In one embodiment, the infrared optical system further includes an aperture stop, and the aperture stop is disposed on the object side of the second lens. In this embodiment, the aperture stop has the function of suppressing the excessive increase of the main ray incident angle, that is, improving the incident angle of the light near the optical axis, facilitating the third lens to improve the deviation of the light from the optical axis, so that the deviation amount of the focus of the light after passing through the third lens from the optical axis is reduced, thereby reducing the distortion of the image formed by the infrared optical system on the imaging surface and effectively improving the image quality of the image formed by the infrared optical system on the imaging surface. The aperture stop can also be disposed between the first lens and the object side of the infrared optical system, that is, the aperture stop is disposed on the object side of the first lens. The aperture stop can be an aperture diaphragm or a field stop to further improve the imaging quality of the infrared optical system.

[0047] In one embodiment, the second lens has positive focal power, and both the object-side and image-side surfaces of the second lens are convex. In this embodiment, the second lens and the third lens are both convex lenses, and both the object-side and image-side surfaces are aspherical. This facilitates further adjustment of the focus offset of light after passing through the second and third lenses, thereby further reducing the (F-θ) distortion of the image formed by the infrared optical system, thereby increasing the relative illumination value of the image formed by the infrared optical system, improving the inclination of the image formed by the infrared optical system, and improving the imaging quality of the infrared optical system.

[0048] The infrared optical system according to the above-described embodiment of the present application can utilize multiple lenses, such as the four lenses described above. By optimizing the aperture, curvature, and shape of the third lens, and rationally allocating the focal length, refractive power, surface shape, thickness, and on-axis spacing of each lens, an optical imaging system is provided that maintains a wide field of view while minimizing F-θ distortion, thereby better meeting the application requirements of ultra-wide-angle electronic devices. It will be understood that while the embodiments are described using four lenses as an example, the optical imaging system is not limited to including four lenses and may include other numbers of lenses if desired.

[0049] Specific embodiments of the infrared optical system applicable to the above-mentioned embodiments will be further described below with reference to the accompanying drawings.

[0050] Example 1

[0051] The following reference Figures 1 to 2D The infrared optical system of Example 1 of the present application is described.

[0052] Figure 1 FIG. 1 shows a schematic structural diagram of the infrared optical system of Example 1. Figure 1 As shown, the infrared optical system includes, in order from the object side to the image side along the optical axis, a first lens L1 , a second lens L2 , a third lens L3 , a fourth lens L4 , an infrared filter L5 , and an imaging surface S11 .

[0053] The first lens L1 has negative refractive power. Both its object-side surface S1 and image-side surface S2 are aspherical. Furthermore, the object-side surface S1 of the first lens L1 is convex along the optical axis and convex along the circumference. The image-side surface S2 of the first lens L1 is concave along the optical axis and convex along the circumference.

[0054] The second lens L2 has positive refractive power. Its object-side surface S3 and image-side surface S4 are both aspherical. Moreover, the object-side surface S3 of the second lens L2 is convex along the optical axis and concave along the circumference. The image-side surface S4 of the second lens L2 is convex along the optical axis and convex along the circumference.

[0055] The third lens L3 has positive refractive power. Its object-side surface S5 and image-side surface S6 are both aspherical. Moreover, the object-side surface S5 of the third lens L3 is convex along the optical axis and convex along the circumference. The image-side surface S6 of the third lens L3 is convex and convex along the circumference.

[0056] The fourth lens L4 has negative refractive power. Both its object-side surface S7 and image-side surface S8 are aspherical. Furthermore, the object-side surface S7 of the fourth lens L4 is convex along the optical axis and concave along the circumference. The image-side surface S8 of the fourth lens L4 is concave and convex along the circumference.

[0057] A stop STO is provided between the first lens L1 and the second lens L2 to further improve the imaging quality of the infrared optical system.

[0058] The infrared optical system also includes an infrared filter L5 having an object-side surface S9 and an image-side surface S10. The image side of the fourth lens L4 is provided with an infrared filter L5 to filter the infrared light, that is, the infrared filter L5 is used to filter out visible light and ensure that the infrared light is transmitted.

[0059] Table 1 shows the surface type, curvature radius, thickness, refractive index, and conic coefficient of each lens of the infrared optical system of Example 1, wherein the distance from the object side surface of the first lens L1 to the imaging surface S11 of the optical imaging system on the optical axis, the curvature radius, and the thickness are all in millimeters (mm). Table 1

[0060]

[0061]

[0062] As can be seen from Table 1, in this embodiment, the first lens L1 to the fourth lens L4 are all plastic aspheric lenses, and the surface shape x of each aspheric surface is defined by the following formula:

[0063]

[0064] Where x is the distance from the vertex of the aspheric surface at a height h along the optical axis; c is the paraxial curvature of the aspheric surface, c = 1 / R (i.e., paraxial curvature c is the reciprocal of the radius of curvature R in Table 1); k is the conic coefficient; Ai is the i-th order coefficient of the aspheric surface. Table 2 below lists the higher-order coefficients A4, A6, A8, A10, A12, A14, and A16 that can be used for the aspheric surfaces S1 to S8 of the lens in Example 1.

[0065] Table 2

[0066]

[0067] Combining the data in Table 1 and Table 2, it can be seen that the infrared optical system in Example 1 satisfies:

[0068] f / R11=-0.080, where f represents the effective focal length of the infrared optical system, and R11 represents the curvature radius of the object-side surface S1 of the first lens L1;

[0069] |dist(F-θ)|=6.895%, where dist(F-θ) represents the (F-θ) distortion value of the image formed by the infrared optical system on the imaging surface S11;

[0070] CTmax-CTmin=0.206mm, where CTmax represents the thickness of the lens with the maximum thickness on the optical axis, and CTmin represents the thickness of the lens with the minimum thickness on the optical axis;

[0071] R22 / R41=-1.05, where R22 represents the curvature radius of the image-side surface S4 of the second lens L2, and R41 represents the curvature radius of the object-side surface S7 of the fourth lens L4;

[0072] CT3 / TTL=0.152, where CT3 represents the center thickness of the third lens element L3 on the optical axis, and TTL represents the distance from the object-side surface S1 of the first lens element L1 to the imaging surface S11 of the infrared optical system on the optical axis;

[0073] SAG12×n2=0.485, where SAG12 represents the distance between the intersection of the image-side surface S2 of the first lens L1 on the optical axis and the perpendicular projection point of the maximum effective radius of the first lens L1 on the optical axis, and n2 represents the refractive index of the second lens L2.

[0074] Figure 2A The spherical aberration curves of the infrared optical system of Example 1 are shown, which respectively represent the deviation of the focal point of light with wavelengths of 810 nm, 820 nm, and 830 nm after passing through the infrared optical system; Figure 2B 1. An astigmatism curve of the infrared optical system of Example 1 is shown, which indicates meridional field curvature and sagittal field curvature; Figure 2C The F-θ distortion curve of the infrared optical system of Example 1 is shown, which represents the F-θ distortion rate at different image heights; Figure 2D The chromatic aberration of magnification of the infrared optical system of Example 1 is shown, which respectively represents the magnification of light with wavelengths of 810nm, 820nm and 830nm by the infrared optical system. Figures 2A to 2DIt can be seen that the (F-θ) distortion value of the infrared optical system is effectively corrected, that is, the (F-θ) distortion value of the infrared optical system is reduced, and the relative illumination value of the image on the imaging surface S11 is increased, thereby improving the image clarity of the infrared optical system. The infrared optical system given in Example 1 can achieve good imaging quality. At the same time, the field of view of the infrared optical system is increased to more than 120°, that is, the field of view is 134.3°, thereby realizing ultra-wide-angle image acquisition.

[0075] Example 2

[0076] The following reference Figures 3 to 4D Describe the infrared optical system of Example 2 of the present application.

[0077] Figure 3 FIG. 2 shows a schematic structural diagram of the infrared optical system of Example 2. Figure 3 As shown, the infrared optical system includes, in order from the object side to the image side along the optical axis, a first lens L1 , a second lens L2 , a third lens L3 , a fourth lens L4 , an infrared filter L5 , and an imaging surface S11 .

[0078] The first lens L1 has negative refractive power. Both its object-side surface S1 and image-side surface S2 are aspherical. Furthermore, the object-side surface S1 of the first lens L1 is convex along the optical axis and convex along the circumference. The image-side surface S2 of the first lens L1 is concave along the optical axis and convex along the circumference.

[0079] The second lens L2 has positive refractive power. Its object-side surface S3 and image-side surface S4 are both aspherical. Moreover, the object-side surface S3 of the second lens L2 is convex along the optical axis and concave along the circumference. The image-side surface S4 of the second lens L2 is convex along the optical axis and convex along the circumference.

[0080] The third lens L3 has positive refractive power. Its object-side surface S5 and image-side surface S6 are both aspherical. Furthermore, the object-side surface S5 of the third lens L3 is convex along the optical axis and concave along the circumference. The image-side surface S6 of the third lens L3 is convex and convex along the circumference.

[0081] The fourth lens L4 has negative refractive power. Its object-side surface S7 and image-side surface S8 are both aspherical. Furthermore, the object-side surface S7 of the fourth lens L4 is convex along the optical axis and concave along the circumference. The image-side surface S8 of the fourth lens L4 is concave and concave along the circumference.

[0082] An aperture STO is provided between the first lens L1 and the second lens L2 to further improve the imaging quality of the infrared optical system.

[0083] The infrared optical system also includes an infrared filter L5 having an object-side surface S9 and an image-side surface S10. The image side of the fourth lens L4 is provided with an infrared filter L5 to filter the infrared light, that is, the infrared filter L5 is used to filter out visible light and ensure that the infrared light is transmitted.

[0084] Table 3 shows the surface type, curvature radius, thickness, refractive index, and conic coefficient of each lens of the infrared optical system of Example 2. The distance from the object-side surface of the first lens L1 to the imaging surface S11 of the optical imaging system on the optical axis, the curvature radius, and the thickness are all in millimeters (mm).

[0085] Table 3

[0086]

[0087] As shown in Table 3, in this embodiment, the first lens L1 to the fourth lens L4 are all plastic aspheric lenses, and the surface shape x of each aspheric surface is defined by the following formula:

[0088]

[0089] Where x is the distance from the vertex of the aspheric surface at a height h along the optical axis; c is the paraxial curvature of the aspheric surface, c = 1 / R (i.e., paraxial curvature c is the reciprocal of the radius of curvature R in Table 3); k is the conic coefficient; Ai is the i-th order coefficient of the aspheric surface. Table 4 below lists the higher-order coefficients A4, A6, A8, A10, A12, A14, and A16 that can be used for the aspheric surfaces S1 to S8 of the lens in Example 2.

[0090] Table 4

[0091]

[0092] Combining the data in Table 3 and Table 4, it can be seen that the infrared optical system in Example 2 meets the following requirements:

[0093] f / R11=-0.005, where f represents the effective focal length of the infrared optical system, and R11 represents the curvature radius of the object-side surface S1 of the first lens L1;

[0094] |dist(F-θ)|=9.450%, where dist(F-θ) represents the (F-θ) distortion value of the image formed by the infrared optical system on the imaging surface S11;

[0095] CTmax-CTmin=0.233mm, where CTmax represents the thickness of the lens with the maximum thickness on the optical axis, and CTmin represents the thickness of the lens with the minimum thickness on the optical axis;

[0096] R22 / R41=-1.03, where R22 represents the curvature radius of the image-side surface S4 of the second lens L2, and R41 represents the curvature radius of the object-side surface S7 of the fourth lens L4;

[0097] CT3 / TTL=0.162, where CT3 represents the center thickness of the third lens element L3 on the optical axis, and TTL represents the distance from the object-side surface S1 of the first lens element L1 to the imaging surface S11 of the infrared optical system on the optical axis;

[0098] SAG12×n2=0.452, where SAG12 represents the distance between the intersection of the image-side surface S2 of the first lens L1 on the optical axis and the perpendicular projection point of the maximum effective radius of the first lens L1 on the optical axis, and n2 represents the refractive index of the second lens L2.

[0099] Figure 4A The spherical aberration curves of the infrared optical system of Example 2 are shown, which respectively represent the deviation of the focal point of light with wavelengths of 810 nm, 820 nm, and 830 nm after passing through the infrared optical system; Figure 4B 1. An astigmatism curve of the infrared optical system of Example 2 is shown, which indicates meridional field curvature and sagittal field curvature; Figure 4C The F-θ distortion curve of the infrared optical system of Example 2 is shown, which represents the F-θ distortion rate at different image heights; Figure 4D The chromatic aberration of magnification of the infrared optical system of Example 2 is shown, which respectively represents the magnification of light with wavelengths of 810nm, 820nm and 830nm by the infrared optical system. Figures 4A to 4D It can be seen that the (F-θ) distortion value of the infrared optical system is effectively corrected, that is, the (F-θ) distortion value of the infrared optical system is reduced, and the relative illumination value of the image on the imaging surface S11 is increased, thereby improving the image clarity of the infrared optical system. The infrared optical system given in Example 2 can achieve good imaging quality. At the same time, the field of view of the infrared optical system is increased to more than 120°, that is, the field of view angle is 132°, thereby realizing ultra-wide-angle image acquisition.

[0100] Example 3

[0101] The following reference Figures 5 to 6D The infrared optical system of Example 3 of the present application is described.

[0102] Figure 5 FIG. 3 shows a schematic structural diagram of the infrared optical system of Example 3. Figure 5 As shown, the infrared optical system includes, in order from the object side to the image side along the optical axis, a first lens L1 , a second lens L2 , a third lens L3 , a fourth lens L4 , an infrared filter L5 , and an imaging surface S11 .

[0103] The first lens L1 has negative refractive power. Both its object-side surface S1 and image-side surface S2 are aspherical. Furthermore, the object-side surface S1 of the first lens L1 is convex along the optical axis and convex along the circumference. The image-side surface S2 of the first lens L1 is concave along the optical axis and convex along the circumference.

[0104] The second lens L2 has positive refractive power. Its object-side surface S3 and image-side surface S4 are both aspherical. Moreover, the object-side surface S3 of the second lens L2 is convex along the optical axis and concave along the circumference. The image-side surface S4 of the second lens L2 is convex along the optical axis and convex along the circumference.

[0105] The third lens L3 has positive refractive power. Its object-side surface S5 and image-side surface S6 are both aspherical. Furthermore, the object-side surface S5 of the third lens L3 is convex along the optical axis and concave along the circumference. The image-side surface S6 of the third lens L3 is convex and convex along the circumference.

[0106] The fourth lens L4 has negative refractive power. Its object-side surface S7 and image-side surface S8 are both aspherical. Furthermore, the object-side surface S7 of the fourth lens L4 is convex along the optical axis and concave along the circumference. The image-side surface S8 of the fourth lens L4 is concave and concave along the circumference.

[0107] An aperture STO is provided between the first lens L1 and the second lens L2 to further improve the imaging quality of the infrared optical system.

[0108] The infrared optical system also includes an infrared filter L5 having an object-side surface S9 and an image-side surface S10. The image side of the fourth lens L4 is provided with an infrared filter L5 to filter the infrared light, that is, the infrared filter L5 is used to filter out visible light and ensure that the infrared light is transmitted.

[0109] Table 5 shows the surface type, curvature radius, thickness, refractive index, and conic coefficient of each lens of the infrared optical system of Example 3. The distance from the object side surface of the first lens L1 to the imaging surface S11 of the optical imaging system on the optical axis, the curvature radius, and the thickness are all in millimeters (mm). Table 5

[0110]

[0111] As shown in Table 5, in this embodiment, the first lens L1 to the fourth lens L4 are all plastic aspheric lenses, and the surface shape x of each aspheric surface is defined by the following formula:

[0112]

[0113] Where x is the distance from the vertex of the aspheric surface at a height h along the optical axis; c is the paraxial curvature of the aspheric surface, c = 1 / R (i.e., paraxial curvature c is the reciprocal of the radius of curvature R in Table 5); k is the conic coefficient; Ai is the i-th order coefficient of the aspheric surface. Table 6 below lists the higher-order coefficients A4, A6, A8, A10, A12, A14, and A16 that can be used for the aspheric surfaces S1 to S8 of the lens in Example 3.

[0114] Table 6

[0115]

[0116]

[0117] Combining the data in Table 5 and Table 6, it can be seen that the infrared optical system in Example 3 meets the following requirements:

[0118] f / R11=-0.098, where f represents the effective focal length of the infrared optical system, and R11 represents the curvature radius of the object-side surface S1 of the first lens L1;

[0119] |dist(F-θ)|=5.238%, where dist(F-θ) represents the (F-θ) distortion value of the image formed by the infrared optical system on the imaging surface S11;

[0120] CTmax-CTmin=0.340mm, where CTmax represents the thickness of the lens with the maximum thickness on the optical axis, and CTmin represents the thickness of the lens with the minimum thickness on the optical axis;

[0121] R22 / R41=-1.03, where R22 represents the curvature radius of the image-side surface S4 of the second lens L2, and R41 represents the curvature radius of the object-side surface S7 of the fourth lens L4;

[0122] CT3 / TTL=0.181, where CT3 represents the center thickness of the third lens element L3 on the optical axis, and TTL represents the distance from the object-side surface S1 of the first lens element L1 to the imaging surface S11 of the infrared optical system on the optical axis;

[0123] SAG12×n2=0.425, where SAG12 represents the distance between the intersection of the image-side surface S2 of the first lens L1 on the optical axis and the perpendicular projection point of the maximum effective radius of the first lens L1 on the optical axis, and n2 represents the refractive index of the second lens L2.

[0124] Figure 6AThe spherical aberration curves of the infrared optical system of Example 3 are shown, which respectively represent the deviation of the focal point of light with wavelengths of 810 nm, 820 nm, and 830 nm after passing through the infrared optical system; Figure 6B 1. An astigmatism curve of the infrared optical system of Example 3 is shown, which indicates meridional field curvature and sagittal field curvature; Figure 6C The F-θ distortion curve of the infrared optical system of Example 3 is shown, which represents the F-θ distortion rate at different image heights; Figure 6D The chromatic aberration of magnification of the infrared optical system of Example 3 is shown, which respectively represents the magnification of light with wavelengths of 810nm, 820nm and 830nm by the infrared optical system. 6A to 6D It can be seen that the (F-θ) distortion value of the infrared optical system is effectively corrected, that is, the (F-θ) distortion value of the infrared optical system is reduced, and the relative illumination value of the image on the imaging surface S11 is increased, thereby improving the image clarity of the infrared optical system. The infrared optical system given in Example 3 can achieve good imaging quality. At the same time, the field of view of the infrared optical system is increased to more than 120°, that is, the field of view angle is 131.9°, thereby realizing ultra-wide-angle image acquisition.

[0125] Example 4

[0126] The following reference Figures 7 to 8D The infrared optical system of Example 4 of the present application is described.

[0127] Figure 7 FIG. 4 shows a schematic structural diagram of the infrared optical system of Example 4. Figure 7 As shown, the infrared optical system includes, in order from the object side to the image side along the optical axis, a first lens L1 , a second lens L2 , a third lens L3 , a fourth lens L4 , an infrared filter L5 , and an imaging surface S11 .

[0128] The first lens L1 has negative refractive power. Both its object-side surface S1 and image-side surface S2 are aspherical. Furthermore, the object-side surface S1 of the first lens L1 is convex along the optical axis and convex along the circumference. The image-side surface S2 of the first lens L1 is concave along the optical axis and convex along the circumference.

[0129] The second lens L2 has positive refractive power. Its object-side surface S3 and image-side surface S4 are both aspherical. Furthermore, the object-side surface S3 of the second lens L2 is concave along the optical axis and concave along the circumference. The image-side surface S4 of the second lens L2 is convex along the optical axis and convex along the circumference.

[0130] The third lens L3 has positive refractive power. Its object-side surface S5 and image-side surface S6 are both aspherical. Moreover, the object-side surface S5 of the third lens L3 is convex along the optical axis and convex along the circumference. The image-side surface S6 of the third lens L3 is convex and convex along the circumference.

[0131] The fourth lens L4 has negative refractive power. Its object-side surface S7 and image-side surface S8 are both aspherical. Furthermore, the object-side surface S7 of the fourth lens L4 is convex along the optical axis and concave along the circumference. The image-side surface S8 of the fourth lens L4 is concave and concave along the circumference.

[0132] An aperture STO is provided between the first lens L1 and the second lens L2 to further improve the imaging quality of the infrared optical system.

[0133] The infrared optical system also includes an infrared filter L5 having an object-side surface S9 and an image-side surface S10. The image side of the fourth lens L4 is provided with an infrared filter L5 to filter the infrared light, that is, the infrared filter L5 is used to filter out visible light and ensure that the infrared light is transmitted.

[0134] Table 7 shows the surface type, curvature radius, thickness, refractive index, and conic coefficient of each lens of the infrared optical system of Example 4. The distance from the object-side surface of the first lens L1 to the imaging surface S11 of the optical imaging system on the optical axis, the curvature radius, and the thickness are all in millimeters (mm).

[0135] Table 7

[0136]

[0137] As shown in Table 7, in this embodiment, the first lens L1 to the fourth lens L4 are all plastic aspheric lenses, and the surface shape x of each aspheric surface is defined by the following formula:

[0138]

[0139] Where x is the distance from the vertex of the aspheric surface at a height h along the optical axis; c is the paraxial curvature of the aspheric surface, c = 1 / R (i.e., paraxial curvature c is the reciprocal of the radius of curvature R in Table 7); k is the conic coefficient; Ai is the i-th order coefficient of the aspheric surface. Table 8 below lists the higher-order coefficients A4, A6, A8, A10, A12, A14, and A16 that can be used for the aspheric surfaces S1 to S8 of the lens in Example 4.

[0140] Table 8

[0141]

[0142] Combining the data in Table 7 and Table 8, it can be seen that the infrared optical system in Example 4 meets the following requirements:

[0143] f / R11=-0.081, where f represents the effective focal length of the infrared optical system, and R11 represents the curvature radius of the object-side surface S1 of the first lens L1;

[0144] |dist(F-θ)|=9.824%, where dist(F-θ) represents the (F-θ) distortion value of the image formed by the infrared optical system on the imaging surface S11;

[0145] CTmax-CTmin=0.279mm, where CTmax represents the thickness of the lens with the maximum thickness on the optical axis, and CTmin represents the thickness of the lens with the minimum thickness on the optical axis;

[0146] R22 / R41=-1.15, where R22 represents the curvature radius of the image-side surface S4 of the second lens L2, and R41 represents the curvature radius of the object-side surface S7 of the fourth lens L4;

[0147] CT3 / TTL=0.154, where CT3 represents the center thickness of the third lens element L3 on the optical axis, and TTL represents the distance from the object-side surface S1 of the first lens element L1 to the imaging surface S11 of the infrared optical system on the optical axis;

[0148] SAG12×n2=0.418, where SAG12 represents the distance between the intersection of the image-side surface S2 of the first lens L1 on the optical axis and the perpendicular projection point of the maximum effective radius of the first lens L1 on the optical axis, and n2 represents the refractive index of the second lens L2.

[0149] Figure 8A The spherical aberration curves of the infrared optical system of Example 4 are shown, which respectively represent the deviation of the focal point of light with wavelengths of 810 nm, 820 nm, and 830 nm after passing through the infrared optical system; Figure 8B 1. An astigmatism curve of the infrared optical system of Example 4 is shown, which indicates meridional field curvature and sagittal field curvature; Figure 8C The F-θ distortion curve of the infrared optical system of Example 4 is shown, which represents the F-θ distortion rate at different image heights; Figure 8D The chromatic aberration of magnification of the infrared optical system of Example 4 is shown, which respectively represents the magnification of light with wavelengths of 810nm, 820nm and 830nm by the infrared optical system. Figures 8A to 8D It can be seen that the (F-θ) distortion value of the infrared optical system is effectively corrected, that is, the (F-θ) distortion value of the infrared optical system is reduced, and the relative illumination value of the image on the imaging surface S11 is increased, thereby improving the image clarity of the infrared optical system. The infrared optical system given in Example 4 can achieve good imaging quality. At the same time, the field of view of the infrared optical system is increased to more than 120°, that is, the field of view angle is 139.2°, thereby realizing ultra-wide-angle image acquisition.

[0150] Example 5

[0151] The following reference Figures 9 to 10D Describe the infrared optical system of Example 5 of the present application.

[0152] Figure 9 FIG. 5 shows a schematic structural diagram of the infrared optical system of Example 5. Figure 9 As shown, the infrared optical system includes, in order from the object side to the image side along the optical axis, a first lens L1 , a second lens L2 , a third lens L3 , a fourth lens L4 , an infrared filter L5 , and an imaging surface S11 .

[0153] The first lens L1 has negative refractive power. Both its object-side surface S1 and image-side surface S2 are aspherical. Furthermore, the object-side surface S1 of the first lens L1 is convex along the optical axis and convex along the circumference. The image-side surface S2 of the first lens L1 is concave along the optical axis and convex along the circumference.

[0154] The second lens L2 has positive refractive power. Its object-side surface S3 and image-side surface S4 are both aspherical. Moreover, the object-side surface S3 of the second lens L2 is convex along the optical axis and concave along the circumference. The image-side surface S4 of the second lens L2 is convex along the optical axis and convex along the circumference.

[0155] The third lens L3 has positive refractive power. Its object-side surface S5 and image-side surface S6 are both aspherical. Furthermore, the object-side surface S5 of the third lens L3 is convex along the optical axis and concave along the circumference. The image-side surface S6 of the third lens L3 is convex and convex along the circumference.

[0156] The fourth lens L4 has negative refractive power. Both its object-side surface S7 and image-side surface S8 are aspherical. Furthermore, the object-side surface S7 of the fourth lens L4 is convex along the optical axis and concave along the circumference. The image-side surface S8 of the fourth lens L4 is concave and convex along the circumference.

[0157] An aperture STO is provided between the first lens L1 and the second lens L2 to further improve the imaging quality of the infrared optical system.

[0158] The infrared optical system also includes an infrared filter L5 having an object-side surface S9 and an image-side surface S10. The image side of the fourth lens L4 is provided with an infrared filter L5 to filter the infrared light, that is, the infrared filter L5 is used to filter out visible light and ensure that the infrared light is transmitted.

[0159] Table 9 shows the surface type, curvature radius, thickness, refractive index, and conic coefficient of each lens of the infrared optical system of Example 5. The units of the distance from the object-side surface of the first lens L1 to the imaging surface S11 of the optical imaging system on the optical axis, the curvature radius, and the thickness are all in millimeters (mm).

[0160] Table 9

[0161]

[0162] As shown in Table 9, in this embodiment, the first lens L1 to the fourth lens L4 are all plastic aspheric lenses, and the surface shape x of each aspheric surface is defined by the following formula:

[0163]

[0164] Where x is the distance from the vertex of the aspheric surface at a height h along the optical axis; c is the paraxial curvature of the aspheric surface, c = 1 / R (i.e., paraxial curvature c is the reciprocal of the radius of curvature R in Table 9); k is the conic coefficient; and Ai is the i-th order coefficient of the aspheric surface. Table 10 below lists the higher-order coefficients A4, A6, A8, A10, A12, A14, and A16 that can be used for the aspheric surfaces S1 to S8 of the lens in Example 5.

[0165] Table 10

[0166]

[0167] Combining the data in Table 9 and Table 10, it can be seen that the infrared optical system in Example 5 meets the following requirements:

[0168] f / R11=-0.094, where f represents the effective focal length of the infrared optical system, and R11 represents the curvature radius of the object-side surface S1 of the first lens L1;

[0169] |dist(F-θ)|=6.660%, where dist(F-θ) represents the (F-θ) distortion value of the image formed by the infrared optical system on the imaging surface S11;

[0170] CTmax-CTmin=0.389mm, where CTmax represents the thickness of the lens with the maximum thickness on the optical axis, and CTmin represents the thickness of the lens with the minimum thickness on the optical axis;

[0171] R22 / R41=-0.91, where R22 represents the curvature radius of the image-side surface S4 of the second lens L2, and R41 represents the curvature radius of the object-side surface S7 of the fourth lens L4;

[0172] CT3 / TTL=0.190, where CT3 represents the center thickness of the third lens element L3 on the optical axis, and TTL represents the distance from the object-side surface S1 of the first lens element L1 to the imaging surface S11 of the infrared optical system on the optical axis;

[0173] SAG12×n2=0.445, where SAG12 represents the distance between the intersection of the image-side surface S2 of the first lens L1 on the optical axis and the perpendicular projection point of the maximum effective radius of the first lens L1 on the optical axis, and n2 represents the refractive index of the second lens L2.

[0174] Figure 10A The spherical aberration curves of the infrared optical system of Example 5 are shown, which respectively represent the deviation of the focal point of light with wavelengths of 810 nm, 820 nm, and 830 nm after passing through the infrared optical system; Figure 10B 10. An astigmatism curve of the infrared optical system of Example 5 is shown, which indicates meridional field curvature and sagittal field curvature; Figure 10C FIG4 shows an F-θ distortion curve of the infrared optical system of Example 5, which represents the F-θ distortion rate at different image heights; Figure 10D The chromatic aberration of magnification of the infrared optical system of Example 5 is shown, which respectively represents the magnification of light with wavelengths of 810nm, 820nm and 830nm by the infrared optical system. 10A to 10D It can be seen that the (F-θ) distortion value of the infrared optical system is effectively corrected, that is, the (F-θ) distortion value of the infrared optical system is reduced, and the relative illumination value of the image on the imaging surface S11 is increased, thereby improving the image clarity of the infrared optical system. The infrared optical system given in Example 5 can achieve good imaging quality. At the same time, the field of view of the infrared optical system is increased to more than 120°, that is, the field of view angle is 134.3°, thereby realizing ultra-wide-angle image acquisition.

[0175] Example 6

[0176] The following reference Figures 11 to 12D Describe the infrared optical system of Example 6 of the present application.

[0177] Figure 11 FIG. 5 shows a schematic structural diagram of the infrared optical system of Example 6. Figure 11 As shown, the infrared optical system includes, in order from the object side to the image side along the optical axis, a first lens L1 , a second lens L2 , a third lens L3 , a fourth lens L4 , an infrared filter L5 , and an imaging surface S11 .

[0178] The first lens L1 has negative refractive power. Both its object-side surface S1 and image-side surface S2 are aspherical. Furthermore, the object-side surface S1 of the first lens L1 is convex along the optical axis and convex along the circumference. The image-side surface S2 of the first lens L1 is concave along the optical axis and convex along the circumference.

[0179] The second lens L2 has positive refractive power. Its object-side surface S3 and image-side surface S4 are both aspherical. Moreover, the object-side surface S3 of the second lens L2 is convex along the optical axis and concave along the circumference. The image-side surface S4 of the second lens L2 is convex along the optical axis and convex along the circumference.

[0180] The third lens L3 has positive refractive power. Its object-side surface S5 and image-side surface S6 are both aspherical. Furthermore, the object-side surface S5 of the third lens L3 is convex along the optical axis and concave along the circumference. The image-side surface S6 of the third lens L3 is convex and convex along the circumference.

[0181] The fourth lens L4 has negative refractive power. Its object-side surface S7 and image-side surface S8 are both aspherical. Furthermore, the object-side surface S7 of the fourth lens L4 is convex along the optical axis and concave along the circumference. The image-side surface S8 of the fourth lens L4 is concave and concave along the circumference.

[0182] A stop STO is provided between the first lens L1 and the second lens L2 to further improve the imaging quality of the infrared optical system.

[0183] The infrared optical system also includes an infrared filter L5 having an object-side surface S9 and an image-side surface S10. The image side of the fourth lens L4 is provided with an infrared filter L5 to filter the infrared light, that is, the infrared filter L5 is used to filter out visible light and ensure that the infrared light is transmitted.

[0184] Table 11 shows the surface type, curvature radius, thickness, refractive index, and conic coefficient of each lens of the infrared optical system of Example 6. The units of the distance from the object-side surface of the first lens L1 to the imaging surface S11 of the optical imaging system on the optical axis, the curvature radius, and the thickness are all in millimeters (mm).

[0185] Table 11

[0186]

[0187] As can be seen from Table 11, in this embodiment, the first lens L1 to the fourth lens L4 are all plastic aspheric lenses, and the surface shape x of each aspheric surface is defined by the following formula:

[0188]

[0189] Where x is the distance from the vertex of the aspheric surface at a height h along the optical axis; c is the paraxial curvature of the aspheric surface, c = 1 / R (i.e., paraxial curvature c is the reciprocal of the radius of curvature R in Table 11); k is the conic coefficient; Ai is the i-th order coefficient of the aspheric surface. Table 12 below lists the higher-order coefficients A4, A6, A8, A10, A12, A14, and A16 that can be used for the aspheric surfaces S1 to S8 of the lens in Example 6.

[0190] Table 12

[0191]

[0192]

[0193] Combining the data in Table 11 and Table 12, it can be seen that the infrared optical system in Example 6 meets the following requirements:

[0194] f / R11=-0.089, where f represents the effective focal length of the infrared optical system, and R11 represents the curvature radius of the object-side surface S1 of the first lens L1;

[0195] |dist(F-θ)|=8.252%, where dist(F-θ) represents the (F-θ) distortion value of the image formed by the infrared optical system on the imaging surface S11;

[0196] CTmax-CTmin=0.481mm, where CTmax represents the maximum thickness of the lens on the optical axis, and CTmin represents the minimum thickness of the lens on the optical axis;

[0197] R22 / R41=-0.89, where R22 represents the curvature radius of the image-side surface S4 of the second lens L2, and R41 represents the curvature radius of the object-side surface S7 of the fourth lens L4;

[0198] CT3 / TTL=0.175, where CT3 represents the center thickness of the third lens element L3 on the optical axis, and TTL represents the distance from the object-side surface S1 of the first lens element L1 to the imaging surface S11 of the infrared optical system on the optical axis;

[0199] SAG12×n2=0.369, where SAG12 represents the distance between the intersection of the image-side surface S2 of the first lens L1 on the optical axis and the perpendicular projection point of the maximum effective radius of the first lens L1 on the optical axis, and n2 represents the refractive index of the second lens L2.

[0200] Figure 12A The spherical aberration curves of the infrared optical system of Example 6 are shown, which respectively represent the deviation of the focal point of light with wavelengths of 810 nm, 820 nm, and 830 nm after passing through the infrared optical system; Figure 12B 10. An astigmatism curve of the infrared optical system of Example 6 is shown, which indicates meridional field curvature and sagittal field curvature; Figure 12C FIG4 shows an F-θ distortion curve of the infrared optical system of Example 6, which represents the F-θ distortion rate at different image heights; Figure 12DThe magnification chromatic aberration of the infrared optical system of Example 6 is shown, which respectively represents the magnification of the light with wavelengths of 810nm, 820nm and 830nm by the infrared optical system. 12A to 12D It can be seen that the (F-θ) distortion value of the infrared optical system is effectively corrected, that is, the (F-θ) distortion value of the infrared optical system is reduced, and the relative illumination value of the image on the imaging surface S11 is increased, thereby improving the image clarity of the infrared optical system. The infrared optical system given in Example 6 can achieve good imaging quality. At the same time, the field of view of the infrared optical system is increased to more than 120°, that is, the field of view angle is 134.1°, thereby realizing ultra-wide-angle image acquisition.

[0201] The present application also provides an infrared imaging module, comprising the infrared optical system described in any of the above embodiments and a photosensitive element, wherein the photosensitive element is located on the image side of the infrared optical system. Specifically, the photosensitive surface of the photosensitive element is the imaging surface S11 of the infrared optical system, and the photosensitive element can be a complementary metal oxide semiconductor (CMOS) image sensor or a charge-coupled device (CCD) image sensor. By selecting a relatively small number of lenses and by limiting the shapes of the object side and image side of the third lens L3, that is, the object side and image side of the third lens L3 are both convex, and then according to the relationship between the effective focal length and the curvature radius of the object side of the first lens L1, the field of view of the infrared optical system is increased, thereby reducing the (F-θ) distortion value of the infrared optical system while ensuring the compact structure of each lens, improving the relative illumination value of the image formed on the photosensitive element, and thus improving the image clarity of the infrared optical system.

[0202] The present application also provides a sweeping robot comprising a mobile body and the aforementioned infrared imaging module, wherein the infrared imaging module is disposed on the mobile body. The infrared imaging module facilitates the collection of infrared light generated by external obstacles, thereby reducing the F-θ distortion of the formed infrared image. Thus, at a larger field of view, the captured image is a clean image, reducing dark corners or reduced image clarity caused by image distortion.

[0203] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. An infrared optical system, characterized in that: The optical lens comprises, in order from the object side to the image side along the optical axis: a first lens having negative optical power; Second lens; a third lens having positive optical power, wherein the object-side surface of the third lens is convex, and the image-side surface of the third lens is convex; and The fourth lens; The infrared optical system satisfies the following relationship: -0.1 <f / R11<0;|dist(F-θ)|<10%;0.2<CTmax-CTmin<0.5;0.3<SAG12×n2<0.5;1.6<n2<1.7; Among them, f represents the effective focal length of the infrared optical system, R11 represents the curvature radius of the object side surface of the first lens, dist(F-θ) represents the (F-θ) distortion value of the image formed by the infrared optical system on the imaging plane, CTmax represents the thickness value of the maximum thickness lens on the optical axis, CTmin represents the thickness value of the minimum thickness lens on the optical axis, SAG12 represents the distance between the intersection of the image side surface of the first lens on the optical axis and the vertical projection point of the maximum effective radius position of the first lens on the optical axis, and n2 represents the refractive index of the second lens.

2. The infrared optical system according to claim 1, characterized in that The infrared optical system satisfies the following relationship: 0.15 <CT3 / TTL<0.2; Wherein, CT3 represents the center thickness of the third lens on the optical axis, and TTL represents the distance from the object-side surface of the first lens to the imaging surface of the infrared optical system on the optical axis.

3. The infrared optical system according to claim 2, characterized in that The infrared optical system satisfies the following relationship: 4.1mm <TTL<4.4mm。 4. The infrared optical system according to claim 1, characterized in that The infrared optical system further includes an aperture, which is arranged on the object side of the second lens.

5. The infrared optical system according to claim 1, wherein: The second lens has positive refractive power, and both the object-side surface and the image-side surface of the second lens are convex surfaces.

6. An infrared imaging module, characterized in that: The infrared optical system comprises the infrared optical system according to any one of claims 1 to 5 and a photosensitive element, wherein the photosensitive element is located on the image side of the infrared optical system.

7. A sweeping robot, characterized in that: It comprises a mobile body and the infrared imaging module as claimed in claim 6, wherein the infrared imaging module is arranged on the mobile body.

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