Imaging lens, endoscope objective, and endoscope

Abstract

The present application relates to an imaging lens, an endoscope objective lens and an endoscope. The imaging lens comprises: a first lens with negative focal length, the image side surface is concave at the near optical axis; a second lens with positive focal length, the image side surface is convex at the near optical axis; a third lens with positive focal length, the object side surface and the image side surface are both convex at the near optical axis; a fourth lens with negative focal length, the object side surface is concave at the near optical axis, and the image side surface is convex at the near optical axis; and the imaging lens satisfies: 150 deg / mm <= FOV / SD11 <= 189 deg / mm. The above imaging lens can balance miniaturization design and good imaging quality.

Description

Technical Field

[0001] This invention relates to the field of endoscopy technology, and in particular to an imaging lens assembly, an endoscopy objective, and an endoscope. Background Technology

[0002] Endoscopes can be inserted into a patient's body for more precise diagnosis and treatment, leading to their increasingly widespread use in the medical field. However, because patient tissues are relatively fragile, endoscopes can easily cause damage during diagnosis or treatment, especially endoscopes used to observe digestive organs, bronchi, nasal cavities, pharynx, urinary organs, and the uterus, which have strict size requirements. Currently, however, some endoscopes are too large, posing a risk of injury to patients. Summary of the Invention

[0003] Therefore, it is necessary to provide an imaging lens assembly, an endoscope objective, and an endoscope to address the current problem of excessively large endoscope sizes.

[0004] An imaging lens assembly, wherein the number of lenses having optical power is four, and the imaging lens assembly comprises, along the optical axis from the object side to the image side, the following:

[0005] A first lens with negative optical power, wherein the image-side surface of the first lens is concave near the optical axis;

[0006] A second lens with positive optical power, wherein the image-side surface of the second lens is convex near the optical axis;

[0007] A third lens having positive optical power, wherein both the object-side and image-side surfaces of the third lens are convex near the optical axis; and,

[0008] A fourth lens with negative optical power, wherein the object side of the fourth lens is concave near the optical axis and the image side is convex near the optical axis;

[0009] The imaging lens group satisfies the following condition:

[0010] 150deg / mm≤FOV / SD11≤189deg / mm;

[0011] Wherein, FOV is the maximum field of view of the imaging lens group, and SD11 is the maximum effective half-aperture of the object side of the first lens.

[0012] In one embodiment, the imaging lens group satisfies the following condition:

[0013] 0.7≤SD11 / f≤1.1;

[0014] Where f is the effective focal length of the imaging lens group.

[0015] In one embodiment, the imaging lens group satisfies the following condition:

[0016] 1.6≤f*tan(HFOV) / ImgH≤2.2;

[0017] Where f is the effective focal length of the imaging lens group, HFOV is half of the maximum field of view of the imaging lens group, and ImgH is half of the image height corresponding to the maximum field of view of the imaging lens group.

[0018] In one embodiment, the imaging lens group satisfies the following condition:

[0019] 2.9 ≤ TTL / ImgH ≤ 3.8;

[0020] Wherein, TTL is the distance on the optical axis from the object side of the first lens to the imaging surface of the imaging lens group, and ImgH is half of the image height corresponding to the maximum field of view of the imaging lens group.

[0021] In one embodiment, the imaging lens group satisfies the following condition:

[0022] 1.4mm -1 ≤FNO / TTL≤2mm -1 ;

[0023] Wherein, FNO is the aperture number of the imaging lens group, and TTL is the distance on the optical axis from the object side of the first lens to the imaging surface of the imaging lens group.

[0024] In one embodiment, the maximum effective half-aperture of the object side of the first lens is greater than the maximum effective half-aperture of the image side of the fourth lens, and the maximum effective half-aperture of the object side of the second lens and the object side of the third lens is smaller than the maximum effective half-aperture of the image side of the fourth lens.

[0025] In one embodiment, the imaging lens group satisfies the following condition:

[0026] 1.4 ≤ SD11 / SD42 ≤ 1.8; and / or,

[0027] 2.3≤SD11 / SD21≤3.4;

[0028] Wherein, SD42 is the maximum effective half-aperture of the image side of the fourth lens; SD21 is the maximum effective half-aperture of the object side of the second lens.

[0029] In one embodiment, the imaging lens group satisfies the following condition:

[0030] 3.4≤TTL / f≤4;

[0031] Where TTL is the distance on the optical axis from the object side of the first lens to the imaging surface of the imaging lens group, and f is the effective focal length of the imaging lens group.

[0032] In one embodiment, the imaging lens group satisfies the following condition:

[0033] 0.9≤Bf / f≤1.4;

[0034] Wherein, Bf is the distance on the optical axis from the image side of the fourth lens to the imaging surface of the imaging lens group, and f is the effective focal length of the imaging lens group.

[0035] In one embodiment, the first lens is made of glass, while the second, third, and fourth lenses are all made of plastic.

[0036] In one embodiment, the first lens, the second lens, the third lens, and the fourth lens are all made of plastic.

[0037] An endoscope objective includes a photosensitive element and an imaging lens assembly as described in any of the above embodiments, wherein the photosensitive element is disposed on the image side of the imaging lens assembly.

[0038] An endoscope comprising an endoscope objective as described above.

[0039] The imaging lens assembly described above allows for a reasonable configuration of the optical power and surface shape of each lens. Combined with the rational design of the FOV / SD11, it can effectively converge light, thereby shortening the overall length of the imaging lens assembly. Consequently, when the imaging lens assembly is applied to an endoscope, it helps to reduce the size of the endoscope and avoid damage to the patient caused by an excessively large endoscope. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the imaging lens assembly in the first embodiment;

[0041] Figure 2 The diagrams shown are the astigmatism curve, distortion curve, and magnification chromatic aberration curve of the imaging lens group in the first embodiment.

[0042] Figure 3 This is a schematic diagram of the imaging lens assembly in the second embodiment;

[0043] Figure 4 The astigmatism curve, distortion curve, and magnification chromatic aberration curve of the imaging lens group in the second embodiment are shown.

[0044] Figure 5 This is a schematic diagram of the imaging lens assembly in the third embodiment;

[0045] Figure 6The astigmatism curve, distortion curve, and magnification chromatic aberration curve of the imaging lens group in the third embodiment are shown.

[0046] Figure 7 This is a schematic diagram of the imaging lens assembly in the fourth embodiment;

[0047] Figure 8 The astigmatism curve, distortion curve, and magnification chromatic aberration curve of the imaging lens group in the fourth embodiment are shown below.

[0048] Figure 9 This is a schematic diagram of the imaging lens assembly in the fifth embodiment;

[0049] Figure 10 The diagrams shown in the fifth embodiment are the astigmatism curve, distortion curve, and magnification chromatic aberration curve of the imaging lens group.

[0050] Figure 11 This is a schematic diagram of the imaging lens assembly in the sixth embodiment;

[0051] Figure 12 The diagrams shown in the sixth embodiment are the astigmatism curve, distortion curve, and magnification chromatic aberration curve of the imaging lens group.

[0052] Figure 13 This is a schematic diagram of the imaging lens assembly in the seventh embodiment;

[0053] Figure 14 The diagrams shown in the seventh embodiment are astigmatism curves, distortion curves, and magnification chromatic aberration curves of the imaging lens group. Detailed Implementation

[0054] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0055] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0056] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0057] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0058] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0059] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0060] Please see Figure 1In some embodiments of this application, the imaging lens group 100 includes a first lens L1, a second lens L2, a third lens L3, and a fourth lens L4 sequentially along the optical axis from the object side to the image side. Specifically, the first lens L1 includes an object-side surface S1 and an image-side surface S2, the second lens L2 includes an object-side surface S3 and an image-side surface S4, the third lens L3 includes an object-side surface S5 and an image-side surface S6, and the fourth lens L4 includes an object-side surface S7 and an image-side surface S8. The first lens L1, the second lens L2, the third lens L3, and the fourth lens L4 are coaxially arranged, and the common axis of all lenses in the imaging lens group 100 is the optical axis of the imaging lens group 100. In some embodiments, the imaging lens group 100 may further include an imaging surface S9 located on the image side of the fourth lens L4, and light rays can be incident on the imaging surface S9 after being adjusted by the first lens L1, the second lens L2, the third lens L3, and the fourth lens L4.

[0061] Specifically, in some examples, the first lens L1 has negative optical power, and its image-side surface S2 is concave near the optical axis. The second lens L2 has positive optical power, and its image-side surface S4 is convex near the optical axis. The third lens L3 has positive optical power, and both its object-side surface S5 and image-side surface S6 are convex near the optical axis. The fourth lens L4 has negative optical power, and its object-side surface S7 is concave near the optical axis, while its image-side surface S8 is convex near the optical axis.

[0062] The negative optical power of the first lens L1, combined with the concave shape of its image-side surface S2 near the optical axis, facilitates the collection of large-angle light rays by the first lens L1, thereby enabling the imaging lens group 100 to achieve wide-angle characteristics and meet the needs of large-area imaging. The positive optical power of the second lens L2, combined with the convex shape of its image-side surface S4 near the optical axis, helps the second lens L2 correct aberrations caused by the introduction of large-angle light rays by the first lens L1, thus improving the imaging quality of the imaging lens group 100. The positive optical power of the third lens L3, combined with its biconvex shape near the optical axis, allows the third lens L3 to work effectively with the second lens L2 to converge light rays, thereby shortening the overall length of the imaging lens group 100 and achieving a miniaturized design. The rational configuration of the optical power and surface shape of the first lens L1, the second lens L2, and the third lens L3 also facilitates a smooth transition of light between these lenses, thereby reducing the aberration sensitivity of the imaging lens group 100. This, in turn, improves the imaging quality of the imaging lens group 100 while achieving wide-angle characteristics and miniaturization. The negative optical power of the fourth lens L4, combined with its concave-convex surface shape near the optical axis, helps the fourth lens L4 to effectively deflect and diverge light onto the imaging surface S9. This makes it easier to match the angle of incidence of light on the imaging surface S9 with the photosensitive element, and also helps to increase the size of the imaging surface S9 of the imaging lens group 100, thus improving the imaging quality of the imaging lens group 100. Simultaneously, it also helps to shorten the back focal length of the imaging lens group 100, thereby facilitating miniaturization. It should be noted that, in this application, the description of the surface shape of a lens near the optical axis can be understood as the surface shape of the portion of the lens corresponding to the area traversed by paraxial rays.

[0063] Furthermore, in some embodiments, the imaging lens group 100 satisfies the condition: 150deg / mm ≤ FOV / SD11 ≤ 189deg / mm; where FOV is the maximum field of view of the imaging lens group 100, and SD11 is the maximum effective half-aperture of the object-side surface S1 of the first lens L1. Satisfying the above condition is beneficial for reducing the effective aperture of the imaging lens group 100, thereby achieving a miniaturized design. It also helps the imaging lens group 100 achieve wide-angle characteristics to meet the needs of large-area imaging, and further contributes to good image quality. Exceeding the upper limit of the above condition results in an excessively large field of view for the imaging lens group 100, making it prone to uncorrectable distortions and other aberrations at the edges of the field of view, which is detrimental to improving image quality. Below the lower limit of the above condition, it is not conducive to achieving wide-angle characteristics, nor is it conducive to reducing the effective aperture of the imaging lens group 100.

[0064] When the above-mentioned optical power and surface features are met and the above-mentioned conditions are satisfied, the imaging lens group 100 can achieve both miniaturization, wide-angle characteristics and high imaging quality.

[0065] In some embodiments, the imaging lens group 100 satisfies the condition: 0.7 ≤ SD11 / f ≤ 1.1; where f is the effective focal length of the imaging lens group 100. Satisfying the above condition is beneficial for reducing the effective aperture and overall length of the imaging lens group 100 to achieve miniaturization, and also beneficial for improving the imaging quality of the imaging lens group 100. Exceeding the upper limit of the above condition results in an excessively large effective aperture of the first lens L1, which is not conducive to the realization of miniaturization. At the same time, the effective focal length of the imaging lens group 100 is too short, resulting in limited light deflection space along the axis of the imaging lens group 100, which is not conducive to good light adjustment, and thus not conducive to improving the imaging quality. Below the lower limit of the above condition, the effective focal length of the imaging lens group 100 is too long, resulting in an excessively long overall length of the imaging lens group 100, which is also not conducive to the realization of miniaturization.

[0066] In some embodiments, the imaging lens group 100 satisfies the condition: 1.6 ≤ f * tan(HFOV) / ImgH ≤ 2.2; where f is the effective focal length of the imaging lens group 100, HFOV is half of the maximum field of view of the imaging lens group 100, and ImgH is half of the image height corresponding to the maximum field of view of the imaging lens group 100. Satisfying the above condition allows the imaging lens group 100 to achieve wide-angle characteristics while also possessing good image quality. Exceeding the upper limit of the above condition results in an excessively large field of view for the imaging lens group 100, which can easily lead to uncorrectable distortions and other aberrations at the edges of the field of view, hindering the improvement of image quality. Below the lower limit of the above condition, it is detrimental to the imaging lens group 100 achieving wide-angle characteristics.

[0067] In some embodiments, the imaging lens group 100 satisfies the condition: 2.9 ≤ TTL / ImgH ≤ 3.8; where TTL is the distance on the optical axis from the object surface S1 of the first lens L1 to the imaging surface S9 of the imaging lens group 100, i.e., the total optical length of the imaging lens group 100, and ImgH is half the image height corresponding to the maximum field of view of the imaging lens group 100. Satisfying the above condition is beneficial for reducing the effective aperture and total optical length of the imaging lens group 100, thereby facilitating miniaturization. Exceeding the upper limit of the above condition results in an excessively long total length of the imaging lens group 100, which is detrimental to miniaturization. Below the lower limit of the above condition, the size of the imaging surface S9 of the imaging lens group 100 is too large, which is also detrimental to reducing the effective aperture of the imaging lens group 100 and miniaturization.

[0068] In some embodiments, the imaging lens group 100 satisfies the condition: 1.4mm -1 ≤FNO / TTL≤2mm -1Where FNO is the aperture number of the imaging lens group 100, and TTL is the distance on the optical axis from the object side surface S1 of the first lens L1 to the imaging surface S9 of the imaging lens group 100. Satisfying the above conditional expression is beneficial for reducing the effective aperture and overall length of the imaging lens group 100, thus facilitating miniaturization. It also helps prevent the aperture of the imaging lens group 100 from being too small, thereby ensuring sufficient light intake and good image quality. Exceeding the upper limit of the above conditional expression results in an excessively large aperture number for the imaging lens group 100, leading to an excessively small aperture, which is detrimental to increasing the light intake and can easily result in low relative illumination, thus hindering image quality improvement. Below the lower limit of the above conditional expression, the effective aperture and overall length of the imaging lens group 100 are too large, which is detrimental to miniaturization.

[0069] In some embodiments, the maximum effective half-aperture of the object-side surface S1 of the first lens L1 is greater than the maximum effective half-aperture of the image-side surface S8 of the fourth lens L4, and the maximum effective half-apertures of the object-side surface S3 of the second lens L2 and the object-side surface S5 of the third lens L3 are both smaller than the maximum effective half-aperture of the image-side surface S8 of the fourth lens L4. This configuration allows for a smaller effective aperture of the imaging lens group 100 while maintaining a sufficiently large maximum effective aperture of the object-side surface S1 of the first lens L1. This facilitates the effective collection of wide-angle light by the first lens L1, thus contributing to the realization of wide-angle characteristics. Furthermore, the light collected by the first lens L1 fills the aperture of the imaging lens group 100 through the second lens L2 and the third lens L3, thereby improving the relative illumination of the image and enhancing the image quality of the imaging lens group 100. Additionally, it facilitates the effective transmission of light to the imaging surface S9 by the fourth lens L4, which helps to enlarge the size of the imaging surface S9 and allows the incident angle of light on the imaging surface S9 to better match the photosensitive element, thereby improving the image quality of the imaging lens group 100.

[0070] In some embodiments, the imaging lens group 100 satisfies the condition: 1.4 ≤ SD11 / SD42 ≤ 1.8; where SD42 is the maximum effective half-aperture of the image-side surface S8 of the fourth lens L4. Satisfying the above condition is beneficial for the first lens L1 to effectively collect large-angle light rays, and also beneficial for the fourth lens L4 to effectively transmit light rays to the imaging surface S9, thereby facilitating the realization of wide-angle and large image-side characteristics.

[0071] In some embodiments, the imaging lens group 100 satisfies the condition: 2.3 ≤ SD11 / SD21 ≤ 3.4; where SD21 is the maximum effective half-aperture of the object side surface S3 of the second lens L2. Satisfying the above condition allows the first lens L1 and the second lens L2 to work together effectively, which is beneficial for the mutual correction of aberrations and for achieving wide-angle characteristics.

[0072] In some embodiments, the imaging lens group 100 satisfies the condition: 3.4 ≤ TTL / f ≤ 4; where TTL is the distance on the optical axis from the object surface S1 of the first lens L1 to the imaging surface S9 of the imaging lens group 100, i.e., the total optical length of the imaging lens group 100, and f is the effective focal length of the imaging lens group 100. Satisfying the above condition helps to shorten the total length of the imaging lens group 100, achieving a miniaturized design, and also allows the imaging lens group 100 sufficient space to reasonably deflect light, which is beneficial to improving image quality.

[0073] In some embodiments, the imaging lens group 100 satisfies the condition: 0.9 ≤ Bf / f ≤ 1.4; where Bf is the distance on the optical axis from the image-side surface S8 of the fourth lens L4 to the imaging surface S9 of the imaging lens group 100, i.e., the back focal length of the imaging lens group 100, and f is the effective focal length of the imaging lens group 100. Satisfying the above condition shortens the overall length of the imaging lens group 100 to achieve a miniaturized design, while also allowing the imaging lens group 100 to have a sufficiently large back focal space, which is beneficial for focusing the imaging lens group 100 and for better assembly of the imaging lens group 100 with the photosensitive element.

[0074] In some embodiments, the imaging lens group 100 satisfies the condition: 120°≤FOV≤140°. Satisfying this condition, the imaging lens group 100 possesses wide-angle characteristics. When applied in endoscopes, this facilitates the acquisition of images over a large area, thereby reducing the risk of missed diagnoses. Simultaneously, the field of view of the imaging lens group 100 is not excessively large, preventing overly severe distortions and aberrations at the edges of the field of view, thus contributing to improved image quality.

[0075] In some embodiments, the imaging lens group 100 satisfies the condition: 0.8mm ≤ ImgH ≤ 1mm; where ImgH is half the image height corresponding to the maximum field of view of the imaging lens group 100. Satisfying the above condition allows the imaging lens group 100 to possess a large image plane characteristic, thereby enabling it to match higher pixel photosensitive elements to obtain good image quality. It also helps reduce aberrations in the edge field of view, improves the relative illumination in the edge field of view, and further enhances the image quality of the imaging lens group 100.

[0076] It should be noted that in some embodiments, the imaging lens group 100 can be matched with a photosensitive element having a rectangular photosensitive surface, and the imaging surface S9 of the imaging lens group 100 coincides with the photosensitive surface of the photosensitive element. In this case, the effective pixel area on the imaging surface S9 has both horizontal and diagonal directions. Therefore, FOV can be understood as the maximum field of view of the imaging lens group 100 in the diagonal direction, and ImgH can be understood as half the size of the effective pixel area of ​​the imaging lens group 100 in the diagonal direction.

[0077] It is understood that in this application, the imaging surface S9 can be understood as a virtual surface formed by the convergence point of system light rays on the image side of the fourth lens L4. When the imaging lens group 100 is matched with the photosensitive element, the imaging surface S9 coincides with the photosensitive surface of the photosensitive element, so that the light rays adjusted by the system can form a clear image on the photosensitive surface.

[0078] In some embodiments, the imaging lens group 100 is provided with an aperture stop ST, which may be positioned between the second lens L2 and the third lens L3. The centrally positioned aperture stop ST allows the imaging lens group 100 to achieve miniaturization while also having sufficient light intake, thereby improving the imaging quality of the imaging lens group 100.

[0079] In some embodiments, the imaging lens assembly 100 may further include an infrared cut-off filter 110, which may be disposed between the first lens L1 and the second lens L2. The infrared cut-off filter 110 is used to filter out infrared light and prevent infrared light from reaching the imaging surface S9 and affecting the imaging quality of the imaging lens assembly 100. Of course, the infrared cut-off filter 110 may also be disposed between any other two lenses, or between the fourth lens L4 and the imaging surface S9, as long as there is sufficient space for the infrared cut-off filter 110 to be assembled.

[0080] In some embodiments, the imaging lens assembly 100 further includes a protective glass 120, which may be disposed between the fourth lens L4 and the imaging surface S9. The protective glass 120 is used to protect the photosensitive element disposed at the imaging surface S9.

[0081] In some embodiments, the object-side and image-side surfaces of each lens in the imaging lens group 100 are aspherical, and the surface shapes of the object-side and image-side surfaces of each lens may differ near the optical axis and around the circumference. The use of aspherical structures can improve the flexibility of lens design, effectively correct spherical aberration, and improve image quality.

[0082] In some embodiments, each lens in the imaging lens assembly 100 may be made of plastic. Using plastic lenses can reduce the weight of the imaging lens assembly 100 and lower production costs, and, combined with the small size of the imaging lens assembly 100, achieve a lightweight and thin design.

[0083] In other embodiments, the first lens L1 can be made of glass, while the second lens L2, third lens L3, and fourth lens L4 can be made of plastic. Using glass provides the first lens L1 with good wear resistance and biocompatibility, ensuring that the foremost lens of the imaging lens assembly 100 is less prone to damage from impacts when used in an endoscope, eliminating the need for a protective glass front end and minimizing the risk of negative health effects on the user. Using plastic for the latter three lenses facilitates miniaturization of the imaging lens assembly 100, while also reducing its weight and cost. Of course, the above material combinations are merely examples of imaging lens assembly 100 in some embodiments; all lenses in the imaging lens assembly 100 can also be made of glass, or any combination of glass and plastic.

[0084] The reference wavelength for the above effective focal lengths is 587.6nm.

[0085] Based on the descriptions of the above embodiments, more specific embodiments and accompanying drawings are provided below for detailed explanation.

[0086] First Embodiment

[0087] Please see again. Figure 1 , Figure 1 This is a schematic diagram of the imaging lens assembly 100 in the first embodiment. The imaging lens assembly 100 includes, from the object side to the image side, a first lens L1 with negative optical power, an infrared cutoff filter 110, a second lens L2 with positive optical power, an aperture ST, a third lens L3 with positive optical power, a fourth lens L4 with negative optical power, and a protective glass 120.

[0088] The object-side surface and image-side surface of the first lens L1, the second lens L2, the third lens L3, and the fourth lens L4 are all aspherical, and the same applies to other embodiments.

[0089] The object side of the first lens L1 is flat near the optical axis, and the image side is concave near the optical axis.

[0090] The object side of the second lens L2 is convex near the optical axis, and the image side is convex near the optical axis.

[0091] The object side of the third lens L3 is convex near the optical axis, and the image side is convex near the optical axis.

[0092] The object side of the fourth lens L4 is concave near the optical axis, and the image side is convex near the optical axis.

[0093] Table 1 below shows the detailed parameters of each lens in the imaging lens group 100 in the first embodiment, including radius of curvature, thickness, refractive index, Abbe number, effective focal length, effective focal length f, maximum field of view (FOV), and aperture number (FNO). The elements in Table 1, from the first lens L1 to the imaging surface S9, are arranged sequentially from top to bottom. The first row of the first lens L1 represents the object-side surface S1, the second row represents the image-side surface S2, and so on. The first value in the "thickness" parameter column of the first lens L1 is the thickness of the first lens L1 along the optical axis 110, and the second value is the distance from the image-side surface S2 of the first lens L1 to the rear surface (the object-side surface of the second lens L2) along the optical axis 110. The meanings of the other values ​​in the thickness parameter column can be deduced from this. The reference wavelength for the refractive index, Abbe number, and effective focal length of each lens is 587.6 nm.

[0094] It should be noted that in this embodiment and the following embodiments, the imaging lens group 100 may also omit the infrared cut-off filter 110 and the protective glass 120, but the distance between the first lens L1 and the second lens L2, as well as the distance between the fourth lens L4 and the imaging surface S9, remain unchanged.

[0095] Table 1

[0096]

[0097]

[0098] The aspherical coefficients of the object-side or image-side surfaces of each lens in the imaging lens group 100 are given in Table 2. The surface numbers S1-S8 represent the object-side or image-side surfaces S1-S8, respectively. The numbers K-A8 from top to bottom represent the type of aspherical coefficient, where K represents the conic coefficient, A4 represents the fourth-order aspherical coefficient, A6 represents the sixth-order aspherical coefficient, and A8 represents the eighth-order aspherical coefficient. Furthermore, the formula for the aspherical coefficient is as follows:

[0099]

[0100] Where Z is the distance from the corresponding point on the aspherical surface to the plane tangent to the vertex of the surface, r is the distance from the corresponding point on the aspherical surface to the optical axis 110, c is the curvature of the vertex of the aspherical surface, K is the conic coefficient, and Ai is the coefficient corresponding to the i-th higher-order term in the aspherical surface shape formula.

[0101] Table 2

[0102]

[0103] Please see Figure 2 , Figure 2From left to right, the images show the astigmatism curve, distortion curve, and magnification chromatic aberration curve of the imaging lens group 100 in the first embodiment. Figure 2 As can be seen from the astigmatism curves, the sagittal and meridional field curvatures of the imaging lens group 100 are both small, and the field curvature and astigmatism of each field of view are well corrected. The center and edges of the field of view both have clear imaging, and the imaging lens group 100 possesses a large depth of field effect. Figure 2 The distortion curves show that the imaging lens group exhibits relatively small distortion across the entire 100° field of view, with minimal image deformation caused by the main beam, indicating excellent system imaging quality. Figure 2 As can be seen from the magnification chromatic aberration curve, the maximum difference between different wavelengths is less than 2µm, indicating that the magnification chromatic aberration of the imaging lens group 100 is well corrected and has good imaging quality.

[0104] Second Embodiment

[0105] Please see Figure 3 , Figure 3 The image lens group 100 in the second embodiment is shown in the schematic diagram. The image lens group 100 includes, from the object side to the image side, a first lens L1 with negative optical power, an infrared cut-off filter 110, a second lens L2 with positive optical power, an aperture ST, a third lens L3 with positive optical power, a fourth lens L4 with negative optical power, and a protective glass 120.

[0106] The object side of the first lens L1 is concave near the optical axis, and the image side is also concave near the optical axis.

[0107] The object side of the second lens L2 is convex near the optical axis, and the image side is convex near the optical axis.

[0108] The object side of the third lens L3 is convex near the optical axis, and the image side is convex near the optical axis.

[0109] The object side of the fourth lens L4 is concave near the optical axis, and the image side is convex near the optical axis.

[0110] In addition, the parameters of the imaging lens group 100 are given in Table 3, and the definitions of each parameter can be derived from the first embodiment, so they will not be repeated here.

[0111] Table 3

[0112]

[0113]

[0114] The aspherical coefficients of the image side or object side of each lens in the imaging lens group 100 are given in Table 4, and the definitions of each parameter can be derived from the first embodiment.

[0115] Table 4

[0116]

[0117] Please see Figure 4 , Figure 4 From left to right, the images show the astigmatism curve, distortion curve, and magnification chromatic aberration curve of the imaging lens group 100 in the second embodiment. Figure 4 It can be seen that the field curvature astigmatism, distortion and magnification chromatic aberration of the imaging lens group 100 are well corrected, and the imaging lens group 100 has good imaging quality.

[0118] Third Embodiment

[0119] Please see Figure 5 , Figure 5 This is a schematic diagram of the imaging lens group 100 in the third embodiment. The imaging lens group 100 includes, from the object side to the image side, a first lens L1 with negative optical power, an infrared cut-off filter 110, a second lens L2 with positive optical power, an aperture ST, a third lens L3 with positive optical power, a fourth lens L4 with negative optical power, and a protective glass 120.

[0120] The object side of the first lens L1 is flat near the optical axis, and the image side is concave near the optical axis.

[0121] The object side of the second lens L2 is convex near the optical axis, and the image side is convex near the optical axis.

[0122] The object side of the third lens L3 is convex near the optical axis, and the image side is convex near the optical axis.

[0123] The object side of the fourth lens L4 is concave near the optical axis, and the image side is convex near the optical axis.

[0124] In addition, the parameters of the imaging lens group 100 are given in Table 5, and the definitions of each parameter can be derived from the first embodiment, and will not be repeated here.

[0125] Table 5

[0126]

[0127]

[0128] The aspherical coefficients of the image side or object side of each lens in the imaging lens group 100 are given in Table 6, and the definitions of each parameter can be derived from the first embodiment.

[0129] Table 6

[0130]

[0131] Please see Figure 6 , Figure 6 From left to right, the images show the astigmatism curve, distortion curve, and magnification chromatic aberration curve of the imaging lens group 100 in the third embodiment. Figure 6 It can be seen that the field curvature astigmatism, distortion and magnification chromatic aberration of the imaging lens group 100 are well corrected, and the imaging lens group 100 has good imaging quality.

[0132] Fourth embodiment

[0133] Please see Figure 7 , Figure 7 This is a schematic diagram of the imaging lens group 100 in the fourth embodiment. The imaging lens group 100 includes, from the object side to the image side, a first lens L1 with negative optical power, an infrared cut-off filter 110, a second lens L2 with positive optical power, an aperture ST, a third lens L3 with positive optical power, a fourth lens L4 with negative optical power, and a protective glass 120.

[0134] The object side of the first lens L1 is concave near the optical axis, and the image side is also concave near the optical axis.

[0135] The object side of the second lens L2 is convex near the optical axis, and the image side is convex near the optical axis.

[0136] The object side of the third lens L3 is convex near the optical axis, and the image side is convex near the optical axis.

[0137] The object side of the fourth lens L4 is concave near the optical axis, and the image side is convex near the optical axis.

[0138] In addition, the parameters of the imaging lens group 100 are given in Table 7, and the definitions of each parameter can be derived from the first embodiment, and will not be repeated here.

[0139] Table 7

[0140]

[0141]

[0142] The aspherical coefficients of the image side or object side of each lens in the imaging lens group 100 are given in Table 8, and the definitions of each parameter can be derived from the first embodiment.

[0143] Table 8

[0144]

[0145] Please see Figure 8 , Figure 8 From left to right, the images show the astigmatism curve, distortion curve, and magnification chromatic aberration curve of the imaging lens group 100 in the fourth embodiment. Figure 8It can be seen that the field curvature astigmatism, distortion and magnification chromatic aberration of the imaging lens group 100 are well corrected, and the imaging lens group 100 has good imaging quality.

[0146] Fifth Embodiment

[0147] Please see Figure 9 , Figure 9 The image lens group 100 in the fifth embodiment is shown in the schematic diagram. The image lens group 100 includes, from the object side to the image side, a first lens L1 with negative optical power, an infrared cut-off filter 110, a second lens L2 with positive optical power, an aperture ST, a third lens L3 with positive optical power, a fourth lens L4 with negative optical power, and a protective glass 120.

[0148] The object side of the first lens L1 is flat near the optical axis, and the image side is concave near the optical axis.

[0149] The object side of the second lens L2 is convex near the optical axis, and the image side is convex near the optical axis.

[0150] The object side of the third lens L3 is convex near the optical axis, and the image side is convex near the optical axis.

[0151] The object side of the fourth lens L4 is concave near the optical axis, and the image side is convex near the optical axis.

[0152] In addition, the parameters of the imaging lens group 100 are given in Table 9, and the definitions of each parameter can be derived from the first embodiment, and will not be repeated here.

[0153] Table 9

[0154]

[0155]

[0156] The aspherical coefficients of the image side or object side of each lens in the imaging lens group 100 are given in Table 10, and the definitions of each parameter can be derived from the first embodiment.

[0157] Table 10

[0158]

[0159] Please see Figure 10 , Figure 10 From left to right, the images show the astigmatism curve, distortion curve, and magnification chromatic aberration curve of the imaging lens group 100 in the fifth embodiment. Figure 10 It can be seen that the field curvature astigmatism, distortion and magnification chromatic aberration of the imaging lens group 100 are well corrected, and the imaging lens group 100 has good imaging quality.

[0160] Sixth Embodiment

[0161] Please see Figure 11 , Figure 11 This is a schematic diagram of the imaging lens group 100 in the sixth embodiment. The imaging lens group 100 includes, from the object side to the image side, a first lens L1 with negative optical power, an infrared cut-off filter 110, a second lens L2 with positive optical power, an aperture ST, a third lens L3 with positive optical power, a fourth lens L4 with negative optical power, and a protective glass 120.

[0162] The object side of the first lens L1 is concave near the optical axis, and the image side is also concave near the optical axis.

[0163] The object side of the second lens L2 is convex near the optical axis, and the image side is convex near the optical axis.

[0164] The object side of the third lens L3 is convex near the optical axis, and the image side is convex near the optical axis.

[0165] The object side of the fourth lens L4 is concave near the optical axis, and the image side is convex near the optical axis.

[0166] In addition, the parameters of the imaging lens group 100 are given in Table 11, and the definitions of each parameter can be derived from the first embodiment, and will not be repeated here.

[0167] Table 11

[0168]

[0169] The aspherical coefficients of the image side or object side of each lens in the imaging lens group 100 are given in Table 12, and the definitions of each parameter can be derived from the first embodiment.

[0170] Table 12

[0171]

[0172] Please see Figure 12 , Figure 12 From left to right, the images show the astigmatism curve, distortion curve, and magnification chromatic aberration curve of the imaging lens group 100 in the sixth embodiment. Figure 12 It can be seen that the field curvature astigmatism, distortion and magnification chromatic aberration of the imaging lens group 100 are well corrected, and the imaging lens group 100 has good imaging quality.

[0173] Seventh Embodiment

[0174] Please see Figure 13 , Figure 13The image lens group 100 in the seventh embodiment is shown in the following schematic diagram. The image lens group 100 includes, from the object side to the image side, a first lens L1 with negative optical power, an infrared cut-off filter 110, a second lens L2 with positive optical power, an aperture ST, a third lens L3 with positive optical power, a fourth lens L4 with negative optical power, and a protective glass 120.

[0175] The object side of the first lens L1 is concave near the optical axis, and the image side is also concave near the optical axis.

[0176] The object side of the second lens L2 is concave near the optical axis, and the image side is convex near the optical axis.

[0177] The object side of the third lens L3 is convex near the optical axis, and the image side is convex near the optical axis.

[0178] The object side of the fourth lens L4 is concave near the optical axis, and the image side is convex near the optical axis.

[0179] In addition, the parameters of the imaging lens group 100 are given in Table 13, and the definitions of each parameter can be derived from the first embodiment, and will not be repeated here.

[0180] Table 13

[0181]

[0182] The aspherical coefficients of the image side or object side of each lens in the imaging lens group 100 are given in Table 14, and the definitions of each parameter can be derived from the first embodiment.

[0183] Table 14

[0184]

[0185] Please see Figure 14 , Figure 14 From left to right, the images show the astigmatism curve, distortion curve, and magnification chromatic aberration curve of the imaging lens group 100 in the seventh embodiment. Figure 14 It can be seen that the field curvature astigmatism, distortion and magnification chromatic aberration of the imaging lens group 100 are well corrected, and the imaging lens group 100 has good imaging quality.

[0186] In addition, the imaging lens group 100 in the first to seventh embodiments satisfies the data in Table 15 below, and the effects that can be obtained by satisfying the following data can be referred to the above description.

[0187] Table 15

[0188]

[0189]

[0190] This application also provides an endoscope objective (not shown), including a photosensitive element and an imaging lens assembly 100 as described in any of the above embodiments. The photosensitive surface of the photosensitive element coincides with the imaging surface S9 of the imaging lens assembly 100. Specifically, the photosensitive element can be a charge-coupled device (CCD) or a complementary metal-oxide-semiconductor sensor (CMOS sensor). Using the above-described imaging lens assembly 100 in the endoscope objective achieves a balance between miniaturization, wide-angle characteristics, and high imaging quality, thereby facilitating the application of the endoscope objective in endoscopes.

[0191] This application also provides an endoscope (not shown), including a housing and an endoscope objective as described in any of the above embodiments. The endoscope objective is disposed within the housing, which can serve as a fixing structure for the endoscope objective. Endoscopes can be applied in the medical field, such as for medical diagnosis of patients. Specifically, endoscopes include, but are not limited to, endoscopes used to observe digestive organs, bronchi, nasal cavity, pharynx, urinary organs, and uterus. By employing the aforementioned endoscope objective in an endoscope, the endoscope objective can achieve a combination of miniaturization, wide-angle characteristics, and high imaging quality. This allows the endoscope to minimize damage to patients when applied in the medical field, acquire images of lesion areas over a wide area to avoid missed diagnoses, and form high-resolution images of lesions, improving diagnostic accuracy.

[0192] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0193] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. An imaging lens assembly comprising four lenses, characterized in that, The imaging lens group comprises four lenses with optical power, and the imaging lens group includes, from the object side to the image side, the following along the optical axis: A first lens with negative optical power, wherein the image-side surface of the first lens is concave near the optical axis; A second lens with positive optical power, wherein the image-side surface of the second lens is convex near the optical axis; Aperture; A third lens having positive optical power, wherein both the object-side and image-side surfaces of the third lens are convex near the optical axis; and, A fourth lens with negative optical power, wherein the object side of the fourth lens is concave near the optical axis and the image side is convex near the optical axis; The imaging lens group satisfies the following condition: 150deg / mm≤FOV / SD11≤189deg / mm; 0.7≤SD11 / f≤1.1; Wherein, FOV is the maximum field of view of the imaging lens group, SD11 is the maximum effective half-aperture of the object side of the first lens, and f is the effective focal length of the imaging lens group.

2. The imaging lens assembly according to claim 1, characterized in that, The imaging lens group satisfies the following condition: 1.6≤f*tan(HFOV) / ImgH≤2.2; Where f is the effective focal length of the imaging lens group, HFOV is half of the maximum field of view of the imaging lens group, and ImgH is half of the image height corresponding to the maximum field of view of the imaging lens group.

3. The imaging lens assembly according to claim 1, characterized in that, The imaging lens group satisfies the following condition: 2.9 ≤ TTL / ImgH ≤ 3.8; Wherein, TTL is the distance on the optical axis from the object side of the first lens to the imaging surface of the imaging lens group, and ImgH is half of the image height corresponding to the maximum field of view of the imaging lens group.

4. The imaging lens assembly according to claim 1, characterized in that, The imaging lens group satisfies the following condition: 1.4mm -1 ≤FNO / TTL≤2mm -1 ; Wherein, FNO is the aperture number of the imaging lens group, and TTL is the distance on the optical axis from the object side of the first lens to the imaging surface of the imaging lens group.

5. The imaging lens assembly according to claim 1, characterized in that, The maximum effective half-aperture of the object side of the first lens is greater than the maximum effective half-aperture of the image side of the fourth lens, and the maximum effective half-aperture of the object side of the second lens and the object side of the third lens is smaller than the maximum effective half-aperture of the image side of the fourth lens.

6. The imaging lens assembly according to claim 5, characterized in that, The imaging lens group satisfies the following condition: 1.4 ≤ SD11 / SD42 ≤ 1.8; and / or, 2.3≤SD11 / SD21≤3.4; Wherein, SD42 is the maximum effective half-aperture of the image side of the fourth lens, and SD21 is the maximum effective half-aperture of the object side of the second lens.

7. The imaging lens assembly according to claim 1, characterized in that, The imaging lens group satisfies the following condition: 3.4≤TTL / f≤4; Wherein, TTL is the distance on the optical axis from the object side of the first lens to the imaging surface of the imaging lens group.

8. The imaging lens assembly according to claim 1, characterized in that, The imaging lens group satisfies the following condition: 0.9≤Bf / f≤1.4; Wherein, Bf is the distance on the optical axis from the image side of the fourth lens to the imaging surface of the imaging lens group.

9. The imaging lens assembly according to claim 1, characterized in that, The first lens is made of glass, while the second, third, and fourth lenses are all made of plastic; or, The first lens, the second lens, the third lens, and the fourth lens are all made of plastic.

10. An endoscope objective, characterized in that, It includes a photosensitive element and an imaging lens assembly as described in any one of claims 1-9, wherein the photosensitive element is disposed on the image side of the imaging lens assembly.

11. An endoscope, characterized in that, Includes the endoscope objective as described in claim 10.

Images