An endoscope and an endoscope objective lens

Abstract

The present invention relates to the technical field of endoscopes, and particularly to an objective lens of an endoscope. In the optical system of the endoscope objective lens, a first lens, a second lens, a diaphragm, a third lens, and a fourth lens are arranged in sequence from the image side to the object side along the optical axis. The first lens and the fourth lens have negative optical powers, the second lens and the third lens have positive optical powers. The height h11 of the chief ray on the object side surface of the first lens and the height h42 of the chief ray on the image side surface of the fourth lens satisfy: 0.65 ≤ h11 / h42 ≤ 1.35, and / or the effective optical diameter D11 of the object side surface of the first lens and the effective optical diameter D42 of the image side surface of the fourth lens satisfy: 0.75 ≤ D11 / D42 ≤ 1.25. In this way, the first lens and the fourth lens can be approximately symmetric, and the paths of the light rays passing through the two approximately symmetric lenses are also approximately symmetric, which can cancel out a part of the aberrations with each other, thereby reducing the difficulty of aberration correction. At the same time, it can also reduce the tolerance sensitivity of the optical surface.

Description

Technical Field

[0001] The present invention relates to the technical field of endoscopes, and particularly to an objective lens of an endoscope. Background Art

[0002] Endoscope devices are characterized by small size and direct imaging, and are currently widely used in various industries. An endoscope can enter the patient's body in a non-invasive or minimally invasive manner, and accurate diagnosis or treatment can be performed by observing the endoscope image.

[0003] Since the natural orifices of various parts of the human body are relatively small, even in the case of invasive openings, the smaller the opening, the better. Therefore, there are strict size limit requirements for endoscopes, especially for endoscopes used to observe digestive tract organs, hepatobiliary organs, bronchi, ENT, urinary organs, uterus, etc.

[0004] The diameter size of the endoscope cannot be too large, and correspondingly, the size of the objective optical system at the front end of the endoscope cannot be too large. When observing narrow curved ribbon-shaped organs such as the bladder and ureter, the insertion part is usually bent by more than 90 degrees to observe the organ. In this case, when the length of the objective optical system is short, the length from the front end of the endoscope to the bending part can be shortened, and the endoscope can observe a wider range in the bag-shaped organ. The objective optical system of the endoscope not only needs to be small in size to enable the front end of the endoscope to be small in size, but also the objective optical system of the endoscope is a wide-angle objective optical system, and the field angle of the endoscope objective is generally greater than or equal to 120 degrees. Due to the large field angle, it is relatively difficult to correct the off-axis aberration of the light rays in the edge field of the endoscope objective, and the surface shape and position tolerance sensitivity of the optical elements in the objective are relatively large. Summary of the Invention

[0005] The purpose of the present invention is to provide an endoscope objective lens to improve the problem of difficult aberration correction of the current endoscope objective lens.

[0006] In addition, the purpose of the present invention is also to provide an endoscope using the above endoscope objective lens.

[0007] According to a first aspect, in one embodiment, an endoscope objective lens is provided, including an objective optical system, and the objective optical system includes:

[0008] A first lens, the first lens having a negative optical power, and a part of the image side of the first lens near the optical axis and away from the edge of the first lens being concave;

[0009] A second lens, the second lens having a positive optical power;

[0010] An aperture stop;

[0011] A third lens, the third lens having a positive optical power;

[0012] The fourth lens, the fourth lens having a negative optical power, a portion of the object side surface of the fourth lens near the optical axis and away from the edge of the fourth lens being concave;

[0013] The first lens, the second lens, the aperture stop, the third lens, and the fourth lens are arranged in sequence along the optical axis from the object side to the image side;

[0014] The chief ray height h11 on the object side surface of the first lens and the chief ray height h42 on the image side surface of the fourth lens satisfy: 0.65 ≤ h11 / h42 ≤ 1.35, and / or the effective optical diameter D11 of the object side surface of the first lens and the effective optical diameter D42 of the image side surface of the fourth lens satisfy: 0.75 ≤ D11 / D42 ≤ 1.25.

[0015] Further, in one embodiment, the chief ray height h11 on the object side surface of the first lens and the chief ray height h42 on the image side surface of the fourth lens satisfy: 0.8 ≤ h11 / h42 ≤ 1.2.

[0016] Further, in one embodiment, the effective optical diameter D11 of the object side surface of the first lens and the effective optical diameter D42 of the image side surface of the fourth lens satisfy: 0.85 ≤ D11 / D42 ≤ 1.15

[0017] Further, in one embodiment, the effective optical diameter D11 of the object side surface of the first lens and the imaging height imgH of the objective optical system satisfy: 0.8 ≤ D11 / imgH ≤ 1.42.

[0018] Even further, in one embodiment, the effective optical diameter D11 of the object side surface of the first lens and the imaging height imgH of the objective optical system satisfy: 1.00 ≤ D11 / imgH ≤ 1.40.

[0019] Further, in one embodiment, the chief ray heights at the edge fields of the two surfaces of the first lens are h11 and h12 respectively, the average value of h11 and h12 is H1, the focal length of the first lens is f1, the chief ray heights at the edge fields of the two surfaces of the fourth lens are h41 and h42 respectively, the average value of h41 and h42 is H4, the focal length of the fourth lens is f4, then the objective optical system satisfies: 1 ≤ (H1 / f1) / (H4 / f4) ≤ 2.

[0020] Further, in one embodiment, the combined focal length of the second lens and the third lens as a group of lenses is F23, the focal length of the objective optical system is f, then the objective optical system satisfies: 0.7 ≤ F23 / f ≤ 1.2.

[0021] Further, in one embodiment, the object side surface of the second lens is convex; the image side surface of the third lens is convex.

[0022] Further, in one embodiment, the number of lenses with optical power in the objective optical system is four.

[0023] According to a second aspect, in one embodiment, an endoscope is provided, including the endoscope objective lens described in any one of the embodiments of the first aspect.

[0024] For the endoscope objective lens according to the above embodiment, in the optical system of the endoscope objective lens, the first lens, the second lens, the diaphragm, the third lens, and the fourth lens are arranged in sequence along the optical axis from the object side to the image side. The first lens and the fourth lens have negative optical power. The part of the image side surface of the first lens close to the optical axis and far from the edge of the first lens is concave. The part of the object side surface of the fourth lens close to the optical axis and far from the edge of the fourth lens is concave. The second lens and the third lens have positive optical power. The height h11 of the chief ray on the object side surface of the first lens and the height h42 of the chief ray on the image side surface of the fourth lens satisfy: 0.65 ≤ h11 / h42 ≤ 1.35, and / or the effective optical diameter D11 of the object side surface of the first lens and the effective optical diameter D42 of the image side surface of the fourth lens satisfy: 0.75 ≤ D11 / D42 ≤ 1.25, so that the diaphragm in the objective optical system is located between the second lens and the third lens, and the positive and negative relationships of the optical power of the lenses at the symmetric positions on both sides of the diaphragm are symmetric. In addition, the shapes of the object side surface of the first lens and the image side surface of the fourth lens are approximately symmetric. The positions of the light rays passing through the optical surfaces of the lenses in two approximately symmetric lenses, especially in the first lens and the fourth lens, are approximately symmetric. The above approximately symmetric features can make the entire optical system have a certain symmetry, and a part of the aberrations can be offset by the fact that the signs of the partial aberrations generated by the imaging light rays passing through the approximately symmetric surfaces in the optical system are opposite, thereby reducing the difficulty of aberration correction and improving the imaging quality. Description of the Drawings

[0025] Figure 1 It is a schematic structural diagram of the objective optical system in the first embodiment;

[0026] Figure 2 For use Figure 1 The imaging diffraction MTF curve graph when using the objective optical system therein;

[0027] Figure 3 It is a schematic structural diagram of the objective optical system in the second embodiment;

[0028] Figure 4 For use Figure 3 The imaging diffraction MTF curve graph when using the objective optical system therein;

[0029] Figure 5 It is a schematic structural diagram of the objective optical system in the third embodiment;

[0030] Figure 6 For use Figure 5 It is the imaging diffraction MTF curve graph when using the objective optical system in

[0031] Figure 7 It is a schematic structural diagram of the objective optical system in the fourth embodiment;

[0032] Figure 8 For use Figure 7 It is the imaging diffraction MTF curve graph when using the objective optical system in

[0033] Figure 9 It is a schematic structural diagram of the objective optical system in the fifth embodiment;

[0034] Figure 10 For use Figure 9 It is the imaging diffraction MTF curve graph when using the objective optical system in

[0035] Figure 11 It is a schematic structural diagram of the objective optical system in the sixth embodiment;

[0036] Figure 12 For use Figure 11 It is the imaging diffraction MTF curve graph when using the objective optical system in

[0037] Figure 13 It is a schematic structural diagram of the objective optical system in the seventh embodiment;

[0038] Figure 14 For use Figure 13 It is the imaging diffraction MTF curve graph when using the objective optical system in

[0039] Figure 15 It is a schematic structural diagram of the objective optical system in the eighth embodiment;

[0040] Figure 16 For use Figure 15 It is the imaging diffraction MTF curve graph when using the objective optical system in

[0041] Figure 17 It is a schematic structural diagram of the objective optical system in the ninth embodiment;

[0042] Figure 18 For use Figure 17 It is the imaging diffraction MTF curve graph when using the objective optical system in

[0043] List of feature names corresponding to the reference numerals in the drawings: 1. First lens; 11. Object side; 12. Image side; 2. Second lens; 21. Object side; 22. Image side; 3. Third lens; 31. Object side; 32. Image side; 4. Fourth lens; 41. Object side; 42. Image side; 5. Diaphragm; 6. Filter; 61. Object side; 62. Image side; 7. Image sensor glass; 71. Object side; 72. Image side. Detailed implementation manners

[0044] The present invention will be further described in detail below in conjunction with the accompanying drawings through specific implementation manners. Similar elements in different implementation manners adopt related similar element numbers. In the following implementation manners, many detailed descriptions are provided to enable a better understanding of the present application. However, those skilled in the art can easily recognize that some of the features can be omitted in different situations, or can be replaced by other elements, materials, or methods. In some cases, some operations related to the present application are not shown or described in the specification to avoid overwhelming the core part of the present application with excessive descriptions. For those skilled in the art, it is not necessary to describe these related operations in detail, and they can fully understand the related operations based on the descriptions in the specification and the general technical knowledge in the art.

[0045] In addition, the features, operations, or characteristics described in the specification can be combined in any appropriate manner to form various implementation manners. At the same time, the steps or actions in the method description can also be reordered or adjusted in an obvious manner by those skilled in the art. Therefore, the various sequences in the specification and the drawings are only for clearly describing a certain embodiment and do not mean that they are the necessary sequences, unless it is stated that a certain sequence must be followed.

[0046] The serial numbers assigned to the components herein, such as "first", "second", etc., are only used to distinguish the described objects and do not have any sequential or technical meanings. The "connection" and "coupling" mentioned in the present application, unless otherwise specified, both include direct and indirect connections (couplings).

[0047] The field of view angle of the endoscope objective lens is generally greater than or equal to 120 degrees. Therefore, the objective lens optical system of the endoscope is a wide-angle objective lens optical system. Due to the large field of view angle, it is relatively difficult to correct the off-axis aberrations caused by the marginal rays of the endoscope objective lens. In view of this problem, the present application provides an endoscope objective lens optical system with an approximately symmetric structure. Through the approximate symmetry of the optical surfaces and the positions of the light rays on the optical surfaces, a part of the aberrations can be offset from each other. Therefore, this structure is beneficial to aberration correction, especially for the correction effects of coma, distortion, and lateral chromatic aberration are particularly obvious. The structure of the endoscope objective lens will be introduced in detail below.

[0048] In some embodiments, please refer to Figures 1 to 16 An endoscope objective lens includes an objective lens optical system, which includes a first lens 1, a second lens 2, a diaphragm, a third lens 3, and a fourth lens 4. The first lens 1, the second lens 2, the diaphragm, the third lens 3, and the fourth lens 4 are arranged in sequence from the object side to the image side along the optical axis of the objective lens optical system.

[0049] In some embodiments, considering the need for low cost, the number of lenses with optical power in the objective lens optical system is four, and the diaphragm is located at the middle position of the four lenses to make the objective lens structure approximately symmetric.

[0050] In some embodiments, for a wide-angle objective lens, in order to increase the angle of the marginal optical chief ray, the first lens 1 has a negative optical power. Specifically, the image side 12 of the first lens 1 is a concave surface in the part close to the optical axis of the lens optical system and far from the edge of the first lens 1.

[0051] The first lens 1 can adopt any feasible lens shape. For example, in one embodiment, the first lens 1 adopts a meniscus lens. In another embodiment, the first lens 1 is a plano-concave lens, with its object side 11 being a plane and its image side 12 being a concave surface.

[0052] In some embodiments, based on a similar symmetric structure, the fourth lens 4 of the objective lens optical system is approximately symmetric with the first lens 1, and the fourth lens 4 also has a negative optical power. The object side 41 of the fourth lens 4 is a concave surface in the part close to the optical axis of the lens optical system and far from the edge of the fourth lens 4.

[0053] Specifically, in some embodiments, the fourth lens 4 adopts a meniscus lens, and its object side 41 is a concave surface.

[0054] In some embodiments, both the first lens 1 and the fourth lens 4 have negative optical powers, and both the second lens 2 and the third lens 3 have positive optical powers. This enables the entire objective lens optical system to have a positive optical power for imaging. In one embodiment, the image side 32 of the third lens 3 is a convex surface.

[0055] In some embodiments, the objective lens optical system satisfies at least one of the following two conditions:

[0056] Condition 1: The chief ray height h11 on the object side 11 of the first lens 1 and the chief ray height h42 on the image side 42 of the fourth lens 4 satisfy: 0.65 ≤ h11 / h42 ≤ 1.35.

[0057] Condition 2: The effective optical diameter D11 of the object side 11 of the first lens 1 and the effective optical diameter D42 of the image side 42 of the fourth lens 4 satisfy: 0.75 ≤ D11 / D42 ≤ 1.25.

[0058] The objective lens optical system satisfies Condition 1 and / or Condition 2, such that the heights of the light rays passing through the first lens 1 and the fourth lens 4 are also approximately symmetric, which is beneficial for the correction of aberrations and at the same time beneficial for reducing the tolerance sensitivity of the optical surfaces. The height of the chief ray of the marginal field of view on the object side surface 11 of the first lens 1 is close to the height on the image side surface 42 of the fourth lens 4, which can make the heights of the light rays passing through approximately symmetric. The effective optical diameter of the object side surface 11 of the first lens 1 is close to the effective optical diameter of the image side surface 42 of the fourth lens 4, which may also make the heights of the light rays passing through approximately symmetric.

[0059] That is to say, in the objective lens optical system of the present application, in addition to the structures of the first lens 1 and the fourth lens 4 being approximately symmetric, the heights of the light rays passing through the first lens 1 and the fourth lens 4 with an approximately symmetric relationship are also approximately symmetric.

[0060] It should be noted that the object side of the objective lens optical system in the present application can be understood as the side of the objective lens optical system facing the object to be photographed, such as the side facing the lesion area, and the image side of the objective lens optical system can be understood as the side where the imaging surface of the objective lens optical system is located. Similarly, the image side surface of the lens is the side of the lens facing the imaging surface of the objective lens optical system, and the object side surface is the side of the lens facing the object to be photographed.

[0061] In some embodiments, the parameters are further optimized, and the chief ray height h11 on the object side surface 11 of the first lens 1 and the chief ray height h42 on the image side surface 42 of the fourth lens 4 satisfy: 0.8 ≤ h11 / h42 ≤ 1.2. In some other embodiments, h11 / h42 can satisfy 0.65 ≤ h11 / h42 ≤ 0.85, and of course it can also satisfy 1.2 ≤ h11 / h42 ≤ 1.35.

[0062] In some embodiments, the parameters are further optimized, and the effective optical diameter D11 of the object side surface 11 of the first lens 1 and the effective optical diameter D42 of the image side surface 42 of the fourth lens 4 satisfy: 0.85 ≤ D11 / D42 ≤ 1.15. In some other embodiments, D11 / D42 can satisfy: 0.75 ≤ D11 / D42 ≤ 0.85, and of course it can also satisfy: 1.15 ≤ D11 / D42 ≤ 1.25.

[0063] Furthermore, the end portion of the endoscopic lens includes components such as an endoscope objective lens, an imaging module, an illumination element, an instrument channel, a water and gas channel, and a structural support element. Generally, the size of the end portion of the endoscopic lens and the size of the instrument channel are preferably determined by clinical needs. The imaging module includes an image sensor, and the size of the image sensor is determined by the clinical requirements for image clarity and the number of pixels, as well as the remaining space at the head end. The larger the size of the image sensor, the better the image quality usually is. Therefore, when designing an endoscope, the best practice is that the size of the entire imaging module can be determined by the upper limit of the size of the selected image sensor and its attached circuit board, that is, the diameter square of the endoscope objective lens should be less than or equal to the size of the image sensor and its attached circuit board. Given the image sensor packaging process and the objective lens structural component process, this means that there is a certain corresponding relationship between the diameter of the endoscope objective lens optical system and the effective photosensitive surface (i.e., the image plane size) of the image sensor.

[0064] The ratio of the effective optical diameter D11 of the object side 11 of the first lens 1 to the imaging height imgH of the optical system is D11 / imgH. When D11 / imgH is too small, the effective optical diameter of the first lens 1 is too small, and the imaging light beam is too concentrated on the first lens 1. Since the endoscope is used in the human body, the optical surface of the objective lens (i.e., the object side 11 of the first lens 1) is easily contaminated by foreign objects, and the objective lens contaminants will affect the image quality. When the imaging light beam is too concentrated on the first lens 1, more imaging light beams are affected by the contaminant particles, and the influence of the contaminants on the image quality is large. At the same time, considering the limiting conditions of h11 / h42 and / or D11 / D42, when D11 / imgH is too small, the maximum effective optical diameter of the fourth lens 4 is also too small. At this time, the light is too concentrated on the image side 42 of the fourth lens 4, increasing the tolerance sensitivity and requiring too high machining accuracy and assembly accuracy for the surface shape of the fourth lens 4. When D11 / imgH is too large, the effective optical diameter of the lens is too large, and the final diameter of the objective lens will be larger than the packaging size of the image sensor, resulting in a larger module size and being unfavorable for minimizing the size in the diameter direction of the objective lens. In one embodiment, the relationship between the effective optical diameter D11 of the object side 11 of the first lens 1 in the objective lens optical system and the imaging height imgH (i.e., the image height) of the optical system satisfies the following condition: 0.8 ≤ D11 / imgH ≤ 1.42. When D11 / imgH is within this range, the objective lens optical system is less affected by contaminants and has less tolerance sensitivity. Further, in one embodiment, 1.00 ≤ D11 / imgH ≤ 1.40. In some other embodiments, according to the usage requirements, without considering the above factors, D11 / imgH can also be less than 0.8 or greater than 1.42.

[0065] Further, in some embodiments, in order to further optimize the objective lens size and image quality, the chief ray heights at the edges of the two surfaces of the first lens 1 are h11 and h12 respectively, the average value of h11 and h12 is H1, the focal length of the first lens 1 is f1, the chief ray heights at the edges of the two surfaces of the fourth lens 4 are h41 and h42 respectively, the average value of h41 and h42 is H4, and the focal length of the fourth lens 4 is f4. Then, the objective lens optical system satisfies: 1 ≤ (H1 / f1) / (H4 / f4) ≤ 2. H1 / f1 and H4 / f4 characterize to a certain extent the refractive ability of the lens to light. When the difference between the two is small, the symmetry of the light rays in the objective lens is better, which is conducive to the realization of the wide-angle performance, shortening the length of the objective lens, having a relatively high relative illumination in the marginal field of view, and being relatively easy to correct distortion. In some other embodiments, (H1 / f1) / (H4 / f4) can also be less than 1 or greater than 2.

[0066] Further, the second lens 2 and the third lens 3 are positive focal length lenses. The main function of the second lens 2 and the third lens 3 is to converge light rays. When the focal power of the second lens 2 and the third lens 3 is strong, it is conducive to the convergence of light rays, thereby shortening the length of the objective lens and increasing the wide-angle performance. Therefore, in some embodiments, the combined focal length of the second lens 2 and the third lens 3 as a group of lenses is F23, and the focal length of the objective lens is f. The objective lens optical system satisfies the following condition: 0.7 ≤ F23 / f ≤ 1.2. This can make the length of the objective lens smaller. If F23 / f is too large, it is easy to cause the length of the objective lens to be too long. If F23 / f is too small, it is not conducive to the correction of aberrations and results in poor imaging quality. In some other embodiments, when conditions permit, F23 / f can also be less than 0.7, and of course, it can also be greater than 1.2.

[0067] Further, in some embodiments, the object side 21 of the second lens 2 is a convex surface; the image side 32 of the third lens 3 is a convex surface. This is more conducive to the symmetry of the objective lens optical system. In some embodiments, the second lens 2 and the third lens 3 can be double convex lenses, that is, both the object side and the image side of the lens are convex surfaces. In some other embodiments, one of the object side 21 of the second lens 2 and the image side 32 of the third lens 3 is a concave surface or both are concave surfaces. In some other embodiments, one of the object side 21 of the second lens 2 and the image side 32 of the third lens 3 is a convex surface.

[0068] Considering that if the thickness of the first lens 1 is too thick, it will increase the length of the objective lens and reduce the effectiveness of the approximate symmetry of the objective lens structure. In some embodiments, the objective lens optical system satisfies the following condition: D11 / T1 ≥ 3.2, where D11 is the effective optical diameter of the object side 11 of the first lens 1, and T1 is the central thickness of the first lens 1.

[0069] According to the description of the above embodiments, the above embodiments will be described in more detail below in combination with more specific embodiments.

[0070] For the first embodiment, please refer to Figure 1 and Figure 2 . The left side is the object side, the right side is the image side, and IM is the image plane. From the object side to the image plane, there are successively the first lens 1, the second lens 2, the aperture stop 5, the third lens 3, the fourth lens 4, the filter 6, and the image sensor glass 7.

[0071] The filter 6 has an object side surface 61 and an image side surface 62, and the image sensor glass 7 has an object side surface 71 and an image side surface 72. In some embodiments, the filter 6 and the image sensor glass 7 are not necessary, and whether to use the filter 6 and the image sensor glass 7 in the objective optical system can be selected according to needs. Please refer to Figure 1 . The first lens 1 has a negative optical power, its object side surface 11, i.e., the left side surface, is a plane, and its image side surface 12, i.e., the right side surface, is a concave surface. The second lens 2 has a positive optical power, the object side surface 21 of the second lens 2 is a W-shaped surface, and the image side surface 22 is a convex surface. The third lens 3 has a positive optical power, and the third lens 3 is a biconvex lens, that is, both the object side surface 31 and the image side surface 32 of the third lens 3 are convex surfaces. The fourth lens 4 has a negative optical power, the object side surface 41 of the fourth lens 4 is a concave surface, and the image side surface 42 is a W-shaped surface. The imaging quality of this embodiment is good, and the MTF data can be referred to Figure 2 . Table 1 lists the data such as the curvature radius, thickness, refractive index, Abbe number, effective optical diameter, focal length f of the objective lens, field of view angle FOV, F / number, and total length TTL of each element in the first embodiment. Table 2 lists the aspherical data of each element.

[0072] Table 1 Structural data of the objective optical system in the first embodiment

[0073]

[0074] Table 2 Aspherical data of the aspherical surfaces in the first embodiment

[0075]

[0076] For the second embodiment, please refer to Figure 3 and Figure 4 . The left side is the object side, the right side is the image side, and IM is the image plane. From the object side to the image plane, there are successively the first lens 1, the second lens 2, the aperture stop 5, the third lens 3, the fourth lens 4, the filter 6, and the image sensor glass 7.

[0077] Table 3 Structural data of the objective optical system in the second embodiment

[0078]

[0079] In some embodiments, the filter 6 and the image sensor glass 7 are not necessary, and it can be selected whether to use the filter 6 and the image sensor glass 7 for the objective optical system according to needs. Please refer to Figure 3 , the first lens 1 has a negative focal power, its object side surface 11, i.e., the left side surface, is a plane, and its image side surface 12, i.e., the right side surface, is a concave surface; the second lens 2 has a positive focal power, the object side surface 21 of the second lens 2 is a W-shaped surface, and the image side surface 22 is a convex surface; the third lens 3 has a positive focal power, the object side surface 31 of the third lens 3 is a concave surface, and the image side surface 32 is a convex surface; the fourth lens 4 has a negative focal power, the object side surface 41 of the fourth lens 4 is a concave surface, and the image side surface 42 is a W-shaped surface. The imaging quality of this embodiment is good. For the MTF data, please refer to Figure 4 . Table 3 lists the data such as the curvature radius, thickness, refractive index, Abbe number, effective optical diameter, focal length f of the objective lens, field of view angle FOV, F / number, and total length TTL of each component in the first embodiment. Table 4 lists the aspheric data of each component.

[0080] Aspheric data of the aspheric surfaces in the second embodiment in Table 4

[0081]

[0082] For the third embodiment, please refer to Figure 5 and Figure 6 , the left side is the object side, the right side is the image side, and IM is the image plane. From the object side to the image plane, there are successively the first lens 1, the second lens 2, the aperture stop 5, the third lens 3, the fourth lens 4, the filter 6, and the image sensor glass 7. In some embodiments, the filter 6 and the image sensor glass 7 are not necessary, and it can be selected whether to use the filter 6 and the image sensor glass 7 for the objective optical system according to needs. Please refer to Figure 5 , the first lens 1 has a negative focal power, its object side surface 11, i.e., the left side surface, is a plane, and its image side surface 12, i.e., the right side surface, is a concave surface; the second lens 2 has a positive focal power, the object side surface 21 of the second lens 2 is a concave surface, and the image side surface 22 is a convex surface; the third lens 3 has a positive focal power, the third lens 3 is a biconvex lens, that is, both the object side surface 31 and the image side surface 32 of the third lens 3 are convex surfaces; the fourth lens 4 has a negative focal power, the object side surface 41 of the fourth lens 4 is a concave surface, and the image side surface 42 is a W-shaped surface.

[0083] Table 5 Structural data of the objective optical system in the third embodiment

[0084]

[0085] Table 6 Aspheric data of the aspheric surfaces in the third embodiment

[0086]

[0087] The imaging quality of this embodiment is good. For its MTF data, please refer to Figure 6 . Table 5 lists data such as the radius of curvature, thickness, refractive index, Abbe number, effective optical diameter, focal length f of the objective lens, field of view FOV, F-number, and total length TTL of each component in the first embodiment. Table 6 lists the aspheric data of each component.

[0088] For the fourth embodiment, please refer to Figure 7 and Figure 8 . The left side is the object side, the right side is the image side, and IM is the image plane.

[0089] From the object side to the image plane, there are the first lens 1, the second lens 2, the aperture 5, the third lens 3, the fourth lens 4, the filter 6, and the image sensor glass 7 in sequence.

[0090] In some embodiments, the filter 6 and the image sensor glass 7 are not necessary. Whether to use the filter 6 and the image sensor glass 7 in the objective lens optical system can be selected according to needs.

[0091] Please refer to Figure 7 . The first lens 1 has a negative optical power. Its object side surface 11, i.e., the left side surface, is a plane, and its image side surface 12, i.e., the right side surface, is a concave surface; the second lens 2 has a positive optical power. The object side surface 21 of the second lens 2 is a W-shaped surface, and the image side surface 22 is a convex surface; the third lens 3 has a positive optical power. The third lens 3 is a biconvex lens, that is, both the object side surface 31 and the image side surface 32 of the third lens 3 are convex surfaces; the fourth lens 4 has a negative optical power. The object side surface 41 of the fourth lens 4 is a concave surface, and the image side surface 42 is a W-shaped surface.

[0092] The imaging quality of this embodiment is good. For its MTF data, please refer to Figure 8 .

[0093] Table 7 lists data such as the radius of curvature, thickness, refractive index, Abbe number, effective optical diameter, focal length f of the objective lens, field of view FOV, F-number, and total length TTL of each component in the first embodiment.

[0094] Table 8 lists the aspheric data of each component.

[0095] Structural data of the objective lens optical system in the fourth embodiment of Table 7

[0096]

[0097] Aspheric data of the aspheric surfaces in the fourth embodiment of Table 8

[0098]

[0099] For the fifth embodiment, please refer to Figure 9 and Figure 10, the left side is the object side, the right side is the image side, and IM is the image plane. From the object side to the image plane, there are the first lens 1, the second lens 2, the aperture stop 5, the third lens 3, the fourth lens 4, the filter 6, and the image sensor glass 7 in sequence.

[0100] In some embodiments, the filter 6 and the image sensor glass 7 are not necessary, and whether to use the filter 6 and the image sensor glass 7 in the objective optical system can be selected according to needs.

[0101] Please refer to Figure 9 , the first lens 1 has a negative focal power, its object side surface 11, i.e., the left side surface, is a plane, and its image side surface 12, i.e., the right side surface, is a concave surface; the second lens 2 has a positive focal power, the object side surface 21 of the second lens 2 is a W-shaped surface, and the image side surface 22 is a convex surface; the third lens 3 has a positive focal power, the object side surface 31 of the third lens 3 is a concave surface, and the image side surface 32 is a convex surface; the fourth lens 4 has a negative focal power, the object side surface 41 of the fourth lens 4 is a concave surface, and the image side surface 42 is a W-shaped surface.

[0102] The imaging quality of this embodiment is good. For its MTF data, please refer to Figure 10 .

[0103] Table 9 lists the data such as the curvature radius, thickness, refractive index, Abbe number, effective optical diameter, focal length f of the objective lens, field of view angle FOV, F-number, and total length TTL of each element in the first embodiment. Table 10 lists the aspheric data of each element.

[0104] Structural data of the objective optical system in the fifth embodiment in Table 9

[0105]

[0106] Aspheric data of the aspheric surfaces in the fifth embodiment in Table 10

[0107]

[0108] For the sixth embodiment, please refer to Figure 11 and Figure 12 , the left side is the object side, the right side is the image side, and IM is the image plane. From the object side to the image plane, there are the first lens 1, the second lens 2, the aperture stop 5, the third lens 3, the fourth lens 4, the filter 6, and the image sensor glass 7 in sequence.

[0109] Structural data of the objective optical system in the sixth embodiment in Table 11

[0110]

[0111] Aspheric data of the aspheric surfaces in the sixth embodiment in Table 12

[0112]

[0113] In some embodiments, the filter 6 and the image sensor glass 7 are not necessary, and it can be selected whether to use the filter 6 and the image sensor glass 7 in the objective optical system according to needs. Please refer to Figure 11 , the first lens 1 has a negative focal power, its object side 11, i.e., the left side, is a plane, and its image side 12, i.e., the right side, is a concave surface; the second lens 2 has a positive focal power, and the second lens 2 is a biconvex lens, that is, both the object side 21 and the image side 22 of the second lens 2 are convex surfaces; the third lens 3 has a positive focal power, and the third lens 3 is a biconvex lens, that is, both the object side 31 and the image side 32 of the third lens 3 are convex surfaces; the fourth lens 4 has a negative focal power, the object side 41 of the fourth lens 4 is a concave surface, and the image side is a W-shaped surface. The imaging quality of this embodiment is good. For its MTF data, please refer to Figure 12 . Table 11 lists the data such as the curvature radius, thickness, refractive index, Abbe number, effective optical diameter, focal length f of the objective lens, field of view angle FOV, F-number, and total length TTL of each component in the first embodiment. Table 12 lists the aspheric data of each component.

[0114] For the seventh embodiment, please refer to Figure 13 and Figure 14 , the left side is the object side, the right side is the image side, and IM is the image plane. From the object side to the image plane, there are successively the first lens 1, the second lens 2, the aperture stop 5, the third lens 3, the fourth lens 4, the filter 6, and the image sensor glass 7.

[0115] Structural data of the objective optical system in the seventh embodiment in Table 13

[0116]

[0117] In some embodiments, the filter 6 and the image sensor glass 7 are not necessary, and it can be selected whether to use the filter 6 and the image sensor glass 7 in the objective optical system according to needs. Please refer to Figure 13 , the first lens 1 has a negative focal power, its object side 11, i.e., the left side, is a plane, and its image side 12, i.e., the right side, is a concave surface; the second lens 2 has a positive focal power, and the second lens 2 is a biconvex lens, that is, both the object side 21 and the image side 22 of the second lens 2 are convex surfaces; the third lens 3 has a positive focal power, and the third lens 3 is a biconvex lens, that is, both the object side 31 and the image side 32 of the third lens 3 are convex surfaces; the fourth lens 4 has a negative focal power, the object side 41 of the fourth lens 4 is a concave surface, and the image side 42 is a W-shaped surface. The imaging quality of this embodiment is good. For its MTF data, please refer to Figure 14 . Table 13 lists the data such as the curvature radius, thickness, refractive index, Abbe number, effective optical diameter, focal length f of the objective lens, field of view angle FOV, F-number, and total length TTL of each component in the first embodiment. Table 14 lists the aspheric data of each component.

[0118] Aspherical data of the aspherical surface in the seventh embodiment, Table 14

[0119]

[0120] For the eighth embodiment, please refer to Figure 15 and Figure 16 , with the object side on the left and the image side on the right, and IM being the image plane. From the object side to the image plane, there are successively the first lens 1, the second lens 2, the aperture stop 5, the third lens 3, the fourth lens 4, the filter 6, and the image sensor glass 7.

[0121] Structural data of the objective optical system in the eighth embodiment, Table 15

[0122]

[0123] In some embodiments, the filter 6 and the image sensor glass 7 are not necessary, and it can be selected whether to use the filter 6 and the image sensor glass 7 in the objective optical system according to needs.

[0124] Please refer to Figure 15 , the first lens 1 has a negative optical power, its object side surface 11, i.e., the left side surface, is a plane, and its image side surface 12, i.e., the right side surface, is a concave surface; the second lens 2 has a positive optical power, and the second lens 2 is a biconvex lens, that is, both the object side surface 21 and the image side surface 22 of the second lens 2 are convex surfaces; the third lens 3 has a positive optical power, and the third lens 3 is a biconvex lens, that is, both the object side surface 31 and the image side surface 32 of the third lens 3 are convex surfaces; the fourth lens 4 has a negative optical power, the object side surface 41 of the fourth lens 4 is a concave surface, and the image side surface 42 is a W-shaped surface. The imaging quality of this embodiment is good, and the MTF data can be referred to Figure 16 . Table 15 lists data such as the curvature radius, thickness, refractive index, Abbe number, effective optical diameter, focal length f of the objective lens, field of view angle FOV, F-number, and total length TTL of each element in the first embodiment. Table 16 lists the aspherical data of each element.

[0125] Aspherical data of the aspherical surface in the eighth embodiment, Table 16

[0126]

[0127] For the ninth embodiment, please refer to Figure 17 and Figure 18 , with the object side on the left and the image side on the right, and IM being the image plane. From the object side to the image plane, there are successively the first lens 1, the second lens 2, the aperture stop 5, the third lens 3, the fourth lens 4, the filter 6, and the image sensor glass 7. In some embodiments, the filter 6 and the image sensor glass 7 are not necessary, and it can be selected whether to use the filter 6 and the image sensor glass 7 in the objective optical system according to needs.

[0128] Structural data of the objective lens optical system in the ninth embodiment, Table 17

[0129]

[0130] Aspherical data of the aspherical surface in the ninth embodiment, Table 18

[0131]

[0132] Please refer to Figure 17 , the first lens 1 has a negative optical power, its object side 11, i.e., the left side, is convex, and its image side 12, i.e., the right side, is concave; the second lens 2 has a positive optical power, and the second lens 2 is a biconvex lens, i.e., both the object side 21 and the image side 22 of the second lens 2 are convex; the third lens 3 has a positive optical power, and the third lens 3 is a biconvex lens, i.e., both the object side 31 and the image side 32 of the third lens 3 are convex; the fourth lens 4 has a negative optical power, the object side 41 of the fourth lens 4 is concave, and the image side 42 is convex. The imaging quality of this embodiment is good, and its MTF data please refer to Figure 18 . Table 17 lists data such as the curvature radius, thickness, refractive index, Abbe number, effective optical diameter, focal length f of the objective lens, field of view angle FOV, F / number, and total length TTL of each element in the first embodiment. Table 18 lists the aspherical data of each element.

[0133] The endoscope objective lens optical systems described in Embodiments 1 to 9 satisfy the data in Table 19 below. In some other embodiments, in addition to the data provided in Table 19, and when the requirements are met, the endoscope objective lens optical system can also adopt other arbitrary feasible parameters. For example, in some other embodiments, according to the usage needs, D11 / imgH can also be less than or equal to 1, and in some other embodiments, D11 / imgH can also be greater than or equal to 1.34. In some other embodiments, (H1 / f1) / (H4 / f4) can also be greater than 2. In some other embodiments, when the requirements are met, other parameters of the endoscope objective lens optical system, such as f, FOV, imgH, TTL, etc., can also be adjusted according to needs.

[0134] Data of the endoscope objective lens optical system, Table 19

[0135] Implementation 1 Implementation 2 Implementation 3 Implementation 4 Implementation 5 Implementation 6 Implementation 7 Implementation 8 Implementation 9 f 0.750 0.758 0.826 0.754 0.753 0.719 0.709 0.7930 0.747 TTL 2.898 2.782 2.693 2.697 2.782 2.918 2.822 2.8150 2.813 FOV 140 140 140 140 140 140 150 125 140 h11 / h42 0.96 0.97 1.00 0.83 1.01 0.94 1.02 0.88 0.99 D11 / D42 1.04 1.04 1.08 0.91 1.06 1.05 1.11 0.96 1.04 D11 / imgH 1.25 1.23 1.18 1.12 1.26 1.33 1.34 1.16 1.29 (H1 / f1) / (H4 / f4) 1.03 1.09 0.73 0.66 2.00 1.21 1.13 0.93 1.18 F23 / f 0.79 0.79 0.54 0.72 0.80 1.20 0.83 0.77 0.83 D11 / T1 4.35 4.18 4.35 4.15 3.94 4.88 4.42 3.94 4.43

[0136] In some embodiments of the endoscope, the endoscope includes the endoscope objective lens as described in any one of the above embodiments.

[0137] The above uses specific examples to elaborate on the present invention, which is only used to help understand the present invention and is not intended to limit the present invention. For those skilled in the technical field to which the present invention belongs, based on the idea of the present invention, several simple deductions, deformations, or substitutions can also be made.

Claims

1. An endoscope objective lens, characterized in that, comprising an objective optical system, the objective optical system comprising: a first lens having a negative focal power, and a portion of the image side of the first lens near the optical axis and away from the edge of the first lens being concave; a second lens having a positive focal power; a diaphragm; a third lens having a positive focal power; a fourth lens having a negative focal power, and a portion of the object side of the fourth lens near the optical axis and away from the edge of the fourth lens being concave; the first lens, the second lens, the diaphragm, the third lens, and the fourth lens are arranged in sequence along the optical axis from the object side to the image side; the chief ray height h11 on the object side of the first lens and the chief ray height h42 on the image side of the fourth lens satisfy: 0.65 ≤ h11 / h42 ≤ 1.35, and / or the effective optical diameter D11 of the object side of the first lens and the effective optical diameter D42 of the image side of the fourth lens satisfy: 0.75 ≤ D11 / D42 ≤ 1.25; the effective optical diameter D11 of the object side of the first lens and the imaging height imgH of the objective optical system satisfy: 0.8 ≤ D11 / imgH ≤ 1.42; the chief ray heights at the edges of the two surfaces of the first lens are h11 and h12 respectively, the average value of h11 and h12 is H1, the focal length of the first lens is f1, the chief ray heights at the edges of the two surfaces of the fourth lens are h41 and h42 respectively, the average value of h41 and h42 is H4, the focal length of the fourth lens is f4, then the objective optical system satisfies: 1 ≤ (H1 / f1) / (H4 / f4) ≤ 2.

2. The endoscope objective lens according to claim 1, wherein, the chief ray height h11 on the object side of the first lens and the chief ray height h42 on the image side of the fourth lens satisfy: 0.8 ≤ h11 / h42 ≤ 1.

2.

3. The endoscope objective lens according to claim 1, wherein the effective optical diameter D11 of the object side of the first lens and the effective optical diameter D42 of the image side of the fourth lens satisfy: 0.85 ≤ D11 / D42 ≤ 1.

15.

4. The endoscope objective lens according to claim 1, wherein, the effective optical diameter D11 of the object side of the first lens and the imaging height imgH of the objective optical system satisfy: 1.00 ≤ D11 / imgH ≤ 1.

40.

5. The endoscope objective lens according to any one of claims 1 to 3, characterized in that, the combined focal length of the second lens and the third lens as a group of lenses is F23, the focal length of the objective optical system is f, then the objective optical system satisfies: 0.7 ≤ F23 / f ≤ 1.

2.

6. The endoscope objective lens according to any one of claims 1-3, characterized in that, the object side of the second lens is convex; the image side of the third lens is convex.

7. The endoscope objective lens according to any one of claims 1 to 3, characterized in that, the number of lenses having focal power in the objective optical system is four.

8. An endoscope comprising the endoscope objective according to any one of claims 1-7.

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