Endoscope optical system, endoscope objective lens, and endoscope

Abstract

The present application relates to an endoscope optical system, an endoscope objective lens and an endoscope. The endoscope optical system comprises, in order from the object side to the image side along the optical axis, a first lens group having negative refractive power, a diaphragm and a second lens group having positive refractive power, the first lens group comprises, in order from the object side to the image side along the optical axis, a first lens having negative refractive power and a second lens having positive refractive power, and the second lens group comprises, in order from the object side to the image side along the optical axis, a third lens having positive refractive power, a fourth lens having positive refractive power and a fifth lens having negative refractive power; the endoscope optical system satisfies: 1.7 <= LG1 / f <= 1.9. The above endoscope optical system can meet the needs of miniaturization design, thereby minimizing the damage of the endoscope to the patient.

Description

Technical Field

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

[0002] With the rapid development of medical equipment, endoscopes are increasingly widely used in the medical field, leading to higher and higher requirements for them. Overly large endoscopes can easily cause injury to patients during diagnosis, especially those used to observe the digestive organs, bronchi, nasal cavity, pharynx, urinary organs, and uterus, where size requirements are even more stringent. Therefore, the industry urgently needs to find endoscopes with miniaturized designs to minimize the risk of endoscopic injury to patients. Summary of the Invention

[0003] Therefore, it is necessary to provide an endoscope optical system, an endoscope objective, and an endoscope to meet the requirements of miniaturization design.

[0004] An endoscopic optical system, characterized in that,

[0005] Along the optical axis from the object side to the image side, it sequentially includes a first lens group with negative optical power, an aperture stop, and a second lens group with positive optical power. The first lens group along the optical axis from the object side to the image side includes a first lens with negative optical power and a second lens with positive optical power. The second lens group along the optical axis from the object side to the image side includes a third lens with positive optical power, a fourth lens with positive optical power, and a fifth lens with negative optical power.

[0006] Furthermore, the endoscopic optical system satisfies the following condition:

[0007] 1.7≤LG1 / f≤1.9;

[0008] Wherein, LG1 is the distance from the object side of the first lens to the aperture on the optical axis, and f is the effective focal length of the endoscope optical system.

[0009] In one embodiment, the endoscopic optical system satisfies the following condition:

[0010] 1.15≤|fG1 / fG2|≤1.5;

[0011] Wherein, fG1 is the effective focal length of the first lens group, and fG2 is the effective focal length of the second lens group.

[0012] In one embodiment, the endoscopic optical system satisfies the following condition:

[0013] 0.95≤f2 / f3≤1.3;

[0014] Where f2 is the effective focal length of the second lens and f3 is the effective focal length of the third lens.

[0015] In one embodiment, the endoscopic optical system satisfies the following condition:

[0016] 0.7≤|f1 / f|≤0.8;

[0017] Where f1 is the effective focal length of the first lens.

[0018] In one embodiment, the endoscopic optical system satisfies the following condition:

[0019] 1.4≤|R3 / R6|≤1.6;

[0020] Wherein, R3 is the radius of curvature of the object side of the second lens at the optical axis, and R6 is the radius of curvature of the image side of the third lens at the optical axis.

[0021] In one embodiment, the endoscopic optical system satisfies the following condition:

[0022] 2ω≥130°;

[0023] Wherein, 2ω is the maximum field of view of the endoscope optical system.

[0024] In one embodiment, the endoscopic optical system satisfies the following condition:

[0025] Vd2≤40;

[0026] Wherein, Vd2 is the Abbe number of the second lens at 587.6 nm (d line).

[0027] In one embodiment, the image-side surface of the second lens is a plane, and the object-side surface of the third lens is a plane.

[0028] In one embodiment, both the image-side surface of the second lens and the object-side surface of the third lens are coated with a filter film.

[0029] An endoscope objective includes a photosensitive element and an endoscope optical system as described in any of the above embodiments, wherein the photosensitive element is disposed on the image side of the endoscope optical system.

[0030] An endoscope comprising the aforementioned endoscope objective.

[0031] The aforementioned endoscopic optical system, with its first lens group having negative optical power and second lens group having positive optical power, forms a reverse telephoto structure. This structure helps to maximize the field of view of the endoscopic optical system and shorten its overall length. The first lens, with its negative optical power, helps to expand the field of view. The second lens, with its positive optical power, helps to correct aberrations generated by the first lens, thereby improving image quality. The third and fourth lenses, with their positive optical power, help to shorten the overall length of the endoscopic optical system and effectively share the positive optical power required by the system, reducing its sensitivity and further improving image quality. The fifth lens, with its negative optical power, helps to correct aberrations generated by the fourth lens and also helps to correct chromatic aberration, further enhancing image quality.

[0032] Satisfying the condition 1.7 ≤ LG1 / f ≤ 1.9 is beneficial for reducing the incident height of light on the object side of the first lens, thereby reducing the effective aperture of the first lens and facilitating the miniaturization design of the endoscopic optical system. Additionally, it also helps to shorten the axial dimension of the endoscopic optical system, which is also beneficial for miniaturization. Exceeding the upper limit of the above condition results in an excessively high incident height of light on the object side of the first lens, leading to an excessively large effective aperture of the first lens, which is detrimental to miniaturization. Simultaneously, the axial dimension of the first lens group becomes too large, which is also detrimental to miniaturization. Below the lower limit of the above condition, the axial space of the first lens group is insufficient, making it difficult to effectively deflect light, which is detrimental to improving image quality. When the above optical power characteristics are met and the above condition is satisfied, the endoscopic optical system can achieve a balance between miniaturization, wide-angle characteristics, and high image quality. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the endoscope optical system in the first embodiment;

[0034] Figure 2A This is a field curvature astigmatism curve of the endoscope optical system in the first embodiment;

[0035] Figure 2B This is a distortion curve diagram of the endoscope optical system in the first embodiment;

[0036] Figure 2C This is a magnification chromatic aberration curve of the endoscope optical system in the first embodiment;

[0037] Figure 3 This is a schematic diagram of the endoscope optical system in the second embodiment;

[0038] Figure 4A This is a field curvature astigmatism curve of the endoscope optical system in the second embodiment;

[0039] Figure 4B This is a distortion curve of the endoscope optical system in the second embodiment;

[0040] Figure 4C This is a magnification chromatic aberration curve of the endoscope optical system in the second embodiment;

[0041] Figure 5 This is a schematic diagram of the endoscope optical system in the third embodiment;

[0042] Figure 6A This is a field curvature astigmatism curve of the endoscope optical system in the third embodiment;

[0043] Figure 6B This is a distortion curve diagram of the endoscope optical system in the third embodiment;

[0044] Figure 6C This is a magnification chromatic aberration curve of the endoscope optical system in the third embodiment;

[0045] Figure 7 This is a schematic diagram of the endoscope optical system in the fourth embodiment;

[0046] Figure 8A This is a field curvature astigmatism curve of the endoscope optical system in the fourth embodiment;

[0047] Figure 8B This is a distortion curve diagram of the endoscope optical system in the fourth embodiment;

[0048] Figure 8C This is a magnification chromatic aberration curve of the endoscope optical system in the fourth embodiment;

[0049] Figure 9 This is a schematic diagram of the endoscope optical system in the fifth embodiment;

[0050] Figure 10A This is a field curvature astigmatism curve of the endoscope optical system in the fifth embodiment;

[0051] Figure 10B This is a distortion curve diagram of the endoscope optical system in the fifth embodiment;

[0052] Figure 10C This is a magnification chromatic aberration curve of the endoscope optical system in the fifth embodiment. Detailed Implementation

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] Please see Figure 1 In some embodiments of this application, the endoscopic optical system 100 includes, along the optical axis from the object side to the image side, a first lens group G1 with negative optical power and a second lens group G2 with positive optical power. The first lens group G1 with negative optical power and the second lens group G2 with positive optical power constitute a reverse telephoto structure, which helps to maximize the field of view of the endoscopic optical system 100 and shortens the overall length of the endoscopic optical system 100.

[0060] Specifically, the first lens group G1, along the optical axis from the object side to the image side, includes a first lens L1 with negative optical power and a second lens L2 with positive optical power. The second lens group G2, along the optical axis from the object side to the image side, includes a third lens L3 with positive optical power, a fourth lens L4 with positive optical power, and a fifth lens L5 with negative optical power. The first lens L1, with its negative optical power, helps to expand the field of view of the endoscope optical system 100. The second lens L2, with its positive optical power, helps to correct the aberrations generated by the first lens L1. The third lens, L3, and the fourth lens L4, with their positive optical power, help to shorten the overall length of the endoscope optical system 100 and effectively share the positive optical power required by the endoscope optical system 100, thus reducing the sensitivity of the endoscope optical system 100. The fifth lens L5, with its negative optical power, helps to correct the aberrations generated by the fourth lens L4 and also helps to correct the chromatic aberration of the endoscope optical system 100.

[0061] It is understood that the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, and the fifth lens L5 are coaxially arranged, and the common axis of all lenses in the endoscope optical system 100 is the optical axis of the endoscope optical system 100. The endoscope optical system 100 also includes an image plane IMA located on the image side of the fifth lens L5. The image plane IMA is the imaging surface of the endoscope optical system 100. After the incident light is adjusted by the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, and the fifth lens L5, it can be imaged onto the image plane IMA.

[0062] In some embodiments, the endoscope optical system 100 is provided with an aperture stop S, which can be positioned between the first lens group G1 and the second lens group G2, that is, between the second lens L2 and the third lens L3. The centrally positioned aperture stop S, combined with the anti-measuring structure formed by the first lens group G1 with negative optical power and the second lens group G2 with positive optical power, is beneficial for achieving a wide-angle and miniaturized endoscope optical system 100.

[0063] In some embodiments, the image-side surface of the second lens L2 and the object-side surface of the third lens L3 are both planar, which is beneficial for the shaping and assembly of the second lens L2 and the third lens L3. It is also beneficial for the installation of the aperture S between the second lens L2 and the third lens L3. In addition, the planar setting can provide stable support for the aperture S, making it less likely to shift after installation, which is beneficial for improving the stability of the endoscope imaging system 100.

[0064] In some embodiments, at least one of the image-side surface of the second lens L2 and the object-side surface of the third lens L3 is coated with a filter film (not shown). The filter film is used to filter out interfering light and prevent interfering light from reaching the image plane IMA and affecting normal imaging. For example, the filter film can be an infrared cut-off filter film, used to block light in the near-infrared region that may be sensed by the photosensitive element. Using a filter film instead of a light filter helps to shorten the overall length of the endoscope optical system 100, thereby helping to meet the requirements of miniaturization design. At the same time, the fact that both the image-side surface of the second lens L2 and the object-side surface of the third lens L3 are planar reduces the difficulty of coating and the risk of filter film detachment. In addition, with the filter film located on the image-side surface of the second lens L2 and the object-side surface of the third lens L3, compared to the case where the filter film is located between the fifth lens L5 and the image plane IMA, the incident angle of light on the filter film is smaller, which helps to improve the filtering effect of the filter film and thus helps to improve the image quality.

[0065] In some embodiments, the endoscope optical system 100 further includes a protective glass CG disposed between the fifth lens L5 and the image plane IMA, and the protective glass CG is used to protect the photosensitive element disposed at the image plane IMA.

[0066] In some embodiments, the object-side and image-side surfaces of each lens in the endoscope optical system 100 are aspherical, meaning 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 improves the flexibility of lens design and effectively corrects spherical aberration, thus improving image quality. In other embodiments, the object-side and image-side surfaces of each lens in the endoscope optical system 100 may also be spherical, meaning the surface shapes of the object-side and image-side surfaces of each lens are the same near the optical axis and around the circumference. It should be noted that the above embodiments are merely examples of some embodiments of this application; in some embodiments, the surface of each lens in the endoscope optical system 100 can be any combination of aspherical or spherical surfaces.

[0067] In some embodiments, the lenses in the endoscope optical system 100 can be made of either glass or plastic. Using plastic lenses reduces the weight of the endoscope optical system 100 and lowers production costs, while also allowing for a slimmer design due to the smaller size of the endoscope optical system 100. Using glass lenses provides the endoscope optical system 100 with excellent optical performance and high temperature resistance. It should be noted that the lenses in the endoscope optical system 100 can also be made of any combination of glass and plastic, and do not necessarily have to be made entirely of glass or entirely of plastic.

[0068] Furthermore, in some embodiments, the endoscope optical system 100 satisfies the condition: 1.7 ≤ LG1 / f ≤ 1.9; where LG1 is the distance on the optical axis from the object side of the first lens L1 to the aperture S, and f is the effective focal length of the endoscope optical system 100. Specifically, LG1 / f can be: 1.744, 1.752, 1.763, 1.778, 1.785, 1.791, 1.802, 1.814, 1.823, or 1.849. Satisfying the above condition helps to reduce the incident height of light on the object side of the first lens L1, thereby helping to reduce the effective aperture of the first lens L1, which in turn helps to miniaturize the endoscope optical system 100; in addition, it also helps to shorten the axial dimension of the endoscope optical system 100, which also helps to miniaturize the endoscope optical system 100. If the upper limit of the above conditional expression is exceeded, the incident height of light on the object side of the first lens L1 is too large, resulting in an excessively large effective aperture of the first lens L1, which is detrimental to miniaturization design. Simultaneously, the on-axis dimensions of the first lens group G1 are too large, also hindering miniaturization. If the lower limit of the above conditional expression is exceeded, the on-axis space of the first lens group G1 is insufficient, making it difficult to effectively deflect light rays, which is detrimental to improving image quality.

[0069] When the above-mentioned optical power characteristics are met and the above-mentioned conditions are satisfied, the endoscope optical system 100 can achieve miniaturization, wide-angle characteristics and high imaging quality.

[0070] In some embodiments, the endoscope optical system 100 satisfies the condition: 1.15 ≤ |fG1 / fG2| ≤ 1.5; where fG1 is the effective focal length of the first lens group G1 and fG2 is the effective focal length of the second lens group G2. Specifically, |fG1 / fG2| can be: 1.160, 1.184, 1.203, 1.234, 1.277, 1.321, 1.355, 1.389, 1.394, or 1.406. Satisfying the above condition not only expands the field of view but also helps to shorten the overall length of the endoscope optical system 100, thus achieving both wide-angle characteristics and miniaturization. Below the lower limit of the above condition, the optical focal length of the second lens group G2 is too weak, making it difficult to effectively converge light, resulting in an excessively long overall length of the endoscope optical system 100, which is detrimental to miniaturization. If the upper limit of the above condition is exceeded, the optical focal length of the first lens group G1 will be too weak, which is not conducive to expanding the field of view. At the same time, it will cause the incident height of light on the first lens L1 to increase, which is not conducive to the realization of miniaturization design.

[0071] In some embodiments, the endoscopic optical system 100 satisfies the condition: 0.95 ≤ f2 / f3 ≤ 1.3; where f2 is the effective focal length of the second lens L2 and f3 is the effective focal length of the third lens L3. Specifically, f2 / f3 can be: 1.018, 1.047, 1.089, 1.125, 1.137, 1.184, 1.201, 1.255, 1.258, or 1.261. Satisfying the above condition allows for a reasonable configuration of the optical power distribution of the second lens L2 and the third lens L3 on both sides of the aperture stop S, which is beneficial for effectively correcting aberrations such as spherical aberration and coma, thereby improving the imaging quality of the endoscopic optical system 100. Beyond the range of the above condition, the optical power distribution of the lenses on both sides of the aperture stop S is unbalanced, making it difficult to effectively correct aberrations such as spherical aberration and coma.

[0072] In some embodiments, the endoscope optical system 100 satisfies the condition: 0.7 ≤ |f1 / f| ≤ 0.8; where f1 is the effective focal length of the first lens L1. Specifically, |f1 / f| can be: 0.733, 0.735, 0.736, 0.737, 0.739, 0.740, 0.741, 0.743, 0.745, or 0.746. Satisfying the above condition is beneficial for shortening the overall length of the endoscope optical system 100 and reducing the effective aperture of the first lens L1, thereby facilitating the miniaturization design of the endoscope optical system 100 and also benefiting the processing and assembly of the first lens L1. Below the lower limit of the above condition, the optical focal length of the first lens L1 is too large, resulting in an excessively curved surface of the first lens L1, which is detrimental to the forming and assembly of the first lens L1. If the upper limit of the above condition is exceeded, the optical focal length of the first lens L1 is too small, which leads to an increase in the total length of the endoscope optical system 100. At the same time, it leads to an increase in the incident height of light on the object side of the first lens L1, which leads to an increase in the effective aperture of the object side of the first lens L1, which is not conducive to the miniaturization design of the endoscope optical system 100.

[0073] In some embodiments, the endoscopic optical system 100 satisfies the condition: 1.4 ≤ |R3 / R6| ≤ 1.6; where R3 is the radius of curvature of the object-side surface of the second lens L2 at the optical axis, and R6 is the radius of curvature of the image-side surface of the third lens L3 at the optical axis. Specifically, |R3 / R6| can be: 1.468, 1.471, 1.475, 1.483, 1.486, 1.490, 1.498, 1.502, 1.505, or 1.508. Satisfying the above condition helps to reduce the incident angle of the off-axis beam on the second lens L2 and the third lens L3, thereby helping to correct coma and improve the imaging quality of the endoscopic optical system 100. It also helps to prevent the surface shapes of the second lens L2 and the third lens L3 from being excessively curved, thus facilitating the processing and assembly of the second lens L2 and the third lens L3.

[0074] Furthermore, when the image-side surface of the second lens L2 and the object-side surface of the third lens L3 are both planes, and simultaneously satisfy 1.4≤|R3 / R6|≤1.6 and 0.95≤f2 / f3≤1.3, the surface shape and optical power distribution of the lenses on both sides of the aperture stop S can be reasonably configured, which is beneficial to effectively correct aberrations such as spherical aberration and coma, thereby improving the imaging quality of the endoscope optical system 100.

[0075] In some embodiments, the endoscopic optical system 100 satisfies the condition: 2ω ≥ 130°; where 2ω is the maximum field of view of the endoscopic optical system 100. Specifically, 2ω can be 138.3, 138.4, 138.5, 138.6, 138.8, 140.4, 140.9, 141.2, 141.5, or 141.8, with the unit being degrees. By satisfying the above condition, the endoscopic optical system 100 possesses a wide-angle characteristic, enabling observation of a large field of view during pathological examinations within the body, thereby reducing the risk of missed diagnoses.

[0076] It should be noted that, in some embodiments, the endoscope optical system 100 can be matched with a photosensitive element having a rectangular photosensitive surface, and the image plane IMA of the endoscope optical system 100 coincides with the photosensitive surface of the photosensitive element. In this case, the effective pixel area on the image plane IMA has both a horizontal direction and a diagonal direction, so 2ω can be understood as the maximum field of view of the endoscope optical system 100 in the diagonal direction.

[0077] In addition, in this application, the image plane IMA can be understood as a virtual plane formed by the convergence point of system light rays on the image side of the fifth lens L5. When the endoscope optical system 100 is matched with the photosensitive element, the image plane IMA 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 endoscopic optical system 100 satisfies the condition: Vd2 ≤ 40; where Vd2 is the Abbe number of the second lens L2 at 587.6 nm (d line). Specifically, Vd2 can be: 25.5, 25.6, 25.7, 25.8, 26.2, 27.5, 28.7, 29.1, 30.2, or 31.3. Satisfying the above condition, the second lens L2 can effectively correct axial chromatic aberration and transverse chromatic aberration, thereby improving the imaging quality of the endoscopic optical system 100.

[0079] The reference wavelength for the above effective focal length values ​​is 587.6 nm (d line).

[0080] Based on the descriptions of the above embodiments, more specific embodiments and accompanying drawings are provided below for detailed explanation.

[0081] First Embodiment

[0082] Please see again. Figure 1 , Figure 1This is a schematic diagram of the endoscope optical system 100 in the first embodiment. The endoscope optical system 100 includes, from the object side to the image side, a first lens L1 with negative optical power, a second lens L2 with positive optical power, an aperture S, a third lens L3 with positive optical power, a fourth lens L4 with positive optical power, a fifth lens L5 with negative optical power, and a protective glass CG.

[0083] The object-side surface and image-side surface of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, and the fifth lens L5 are all spherical, and the same applies to other embodiments.

[0084] The object-side surface of the first lens L1 is flat, and the image-side surface is concave.

[0085] The object-side surface of the second lens L2 is convex, while the image-side surface is flat.

[0086] The object-side surface of the third lens L3 is a plane, and the image-side surface is a convex surface.

[0087] The object-side surface of the fourth lens L4 is convex, and the image-side surface is also convex.

[0088] The object-side surface of the fifth lens L5 is concave, while the image-side surface is flat.

[0089] Table 1 below shows detailed parameters of each lens in the endoscope optical system 100 in the first embodiment, including radius of curvature, thickness, refractive index, Abbe number, effective focal length f, maximum field of view 2ω, and effective aperture value FNO. The reference wavelength for the refractive index and Abbe number of each lens is 587.6 nm, and this is also true in other embodiments. The image plane IMA in Table 1 can be understood as the imaging plane of the endoscope optical system 100. The elements from the object plane (not shown) to the image plane IMA are arranged sequentially from top to bottom according to the elements in Table 1. The first row of the first lens L1 represents the object-side surface of the first lens L1, the second row represents the image-side surface of the first lens L1, and so on. The first value in the "thickness" parameter column of the first lens L1 is the thickness of the first lens L1 on the optical axis 110, and the second value is the distance from the image-side surface of the first lens L1 to the rear surface in the image-side direction (the object-side surface of the second lens L2) on the optical axis 110. The meanings of the other values ​​in the thickness parameter column can be deduced from this.

[0090] It should be noted that in this embodiment and the following embodiments, the endoscope optical system 100 may also be without protective glass CG, but in this case, the distance from the image side of the fifth lens L5 to the image plane IMA remains unchanged.

[0091] Table 1

[0092]

[0093] In addition, the values ​​of each conditional expression of the endoscope optical system 100 in the first embodiment are detailed in Table 6. The effects of each conditional expression can be referred to the above description. The values ​​of each conditional expression in the second, third, fourth and fifth embodiments can also be obtained from Table 6, and will not be repeated hereafter.

[0094] Please see Figure 2A , Figure 2B and Figure 2C . Figure 2A This is a field curvature astigmatism curve of the endoscope optical system 100 in the first embodiment, generated by... Figure 2A It can be seen that the sagittal field curvature and meridional field curvature of the endoscope optical system 100 are both small, and the field curvature and astigmatism of each field of view are well corrected. The center and edge of the field of view have clear imaging, which is conducive to the endoscope optical system 100 obtaining a large depth of field effect.

[0095] Figure 2B This is a distortion curve diagram of the endoscope optical system 100 in the first embodiment, from... Figure 2B It can be seen that the distortion of the maximum field of view of the endoscope optical system 100 is less than 65%, the distortion within the effective observation field of view is less than 55%, the image distortion caused by the main beam is small, and the imaging quality of the system is excellent. Among them, the reference wavelength for the field curvature astigmatism curve and the distortion curve is 587.6nm, and the same applies to other embodiments.

[0096] Figure 2C This is a magnification chromatic aberration curve of the endoscope optical system 100 in the first embodiment, derived from... Figure 2C It can be seen that the maximum difference between the wavelengths of 656.3nm and 486.1nm is less than 2µm, indicating that the magnification chromatic aberration of the 100-magnification endoscope optical system is well corrected and has good imaging quality.

[0097] Second Embodiment

[0098] Please see Figure 3 , Figure 3 This is a schematic diagram of the endoscope optical system 100 in the second embodiment. The endoscope optical system 100 includes, from the object side to the image side, a first lens L1 with negative optical power, a second lens L2 with positive optical power, an aperture S, a third lens L3 with positive optical power, a fourth lens L4 with positive optical power, a fifth lens L5 with negative optical power, and a protective glass CG.

[0099] The object-side surface of the first lens L1 is flat, and the image-side surface is concave.

[0100] The object-side surface of the second lens L2 is convex, while the image-side surface is flat.

[0101] The object-side surface of the third lens L3 is a plane, and the image-side surface is a convex surface.

[0102] The object-side surface of the fourth lens L4 is convex, and the image-side surface is also convex.

[0103] The object-side surface of the fifth lens L5 is concave, while the image-side surface is flat.

[0104] In addition, the parameters of the endoscope optical system 100 are given in Table 2, and the definitions of each parameter can be derived from the first embodiment, and will not be repeated here.

[0105] Table 2

[0106]

[0107]

[0108] Please see Figure 4A , Figure 4B and Figure 4C . Figure 4A This is a field curvature astigmatism curve of the endoscope optical system 100 in the second embodiment, generated by... Figure 4A It can be seen that the sagittal field curvature and meridional field curvature of the endoscope optical system 100 are both small, and the field curvature and astigmatism of each field of view are well corrected. The center and edge of the field of view have clear imaging, which is conducive to the endoscope optical system 100 obtaining a large depth of field effect.

[0109] Figure 4B This is a distortion curve diagram of the endoscope optical system 100 in the second embodiment, from... Figure 4B It can be seen that the endoscope optical system 100 has small distortion, the image distortion caused by the main beam is small, and the imaging quality of the system is excellent.

[0110] Figure 4C This is a magnification chromatic aberration curve of the endoscope optical system 100 in the second embodiment, derived from... Figure 4C It can be seen that the magnification chromatic aberration of the endoscopic optical system 100 has been well corrected, resulting in good imaging quality.

[0111] Third Embodiment

[0112] Please see Figure 5 , Figure 5 This is a schematic diagram of the endoscope optical system 100 in the third embodiment. The endoscope optical system 100 includes, from the object side to the image side, a first lens L1 with negative optical power, a second lens L2 with positive optical power, an aperture S, a third lens L3 with positive optical power, a fourth lens L4 with positive optical power, a fifth lens L5 with negative optical power, and a protective glass CG.

[0113] The object-side surface of the first lens L1 is flat, and the image-side surface is concave.

[0114] The object-side surface of the second lens L2 is convex, while the image-side surface is flat.

[0115] The object-side surface of the third lens L3 is a plane, and the image-side surface is a convex surface.

[0116] The object-side surface of the fourth lens L4 is convex, and the image-side surface is also convex.

[0117] The object side of the fifth lens L5 is concave, and the image side is convex.

[0118] In addition, the parameters of the endoscope optical system 100 are given in Table 3, and the definitions of each parameter can be derived from the first embodiment, and will not be repeated here.

[0119] Table 3

[0120]

[0121] Please see Figure 6A , Figure 6B and Figure 6C . Figure 6A This is a field curvature astigmatism curve of the endoscope optical system 100 in the third embodiment, generated by... Figure 6A It can be seen that the sagittal field curvature and meridional field curvature of the endoscope optical system 100 are both small, and the field curvature and astigmatism of each field of view are well corrected. The center and edge of the field of view have clear imaging, which is conducive to the endoscope optical system 100 obtaining a large depth of field effect.

[0122] Figure 6B This is a distortion curve diagram of the endoscope optical system 100 in the third embodiment, from... Figure 6B It can be seen that the endoscope optical system 100 has small distortion, the image distortion caused by the main beam is small, and the imaging quality of the system is excellent.

[0123] Figure 6C This is a magnification chromatic aberration curve of the endoscope optical system 100 in the third embodiment, derived from... Figure 6C It can be seen that the magnification chromatic aberration of the endoscopic optical system 100 has been well corrected, resulting in good imaging quality.

[0124] Fourth embodiment

[0125] Please see Figure 7 , Figure 7 This is a schematic diagram of the endoscope optical system 100 in the fourth embodiment. The endoscope optical system 100 includes, from the object side to the image side, a first lens L1 with negative optical power, a second lens L2 with positive optical power, an aperture S, a third lens L3 with positive optical power, a fourth lens L4 with positive optical power, a fifth lens L5 with negative optical power, and a protective glass CG.

[0126] The object-side surface of the first lens L1 is flat, and the image-side surface is concave.

[0127] The object-side surface of the second lens L2 is convex, while the image-side surface is flat.

[0128] The object-side surface of the third lens L3 is a plane, and the image-side surface is a convex surface.

[0129] The object-side surface of the fourth lens L4 is convex, and the image-side surface is also convex.

[0130] The object side of the fifth lens L5 is concave, and the image side is convex.

[0131] In addition, the parameters of the endoscope optical system 100 are given in Table 4, and the definitions of each parameter can be derived from the first embodiment, and will not be repeated here.

[0132] Table 4

[0133]

[0134]

[0135] Please see Figure 8A , Figure 8B and Figure 8C . Figure 8A This is a field curvature astigmatism curve of the endoscope optical system 100 in the fourth embodiment, generated by... Figure 8A It can be seen that the sagittal field curvature and meridional field curvature of the endoscope optical system 100 are both small, and the field curvature and astigmatism of each field of view are well corrected. The center and edge of the field of view have clear imaging, which is conducive to the endoscope optical system 100 obtaining a large depth of field effect.

[0136] Figure 8B This is a distortion curve diagram of the endoscope optical system 100 in the fourth embodiment, from... Figure 8B It can be seen that the endoscope optical system 100 has small distortion, the image distortion caused by the main beam is small, and the imaging quality of the system is excellent.

[0137] Figure 8C This is a magnification chromatic aberration curve of the endoscope optical system 100 in the fourth embodiment, derived from... Figure 8C It can be seen that the magnification chromatic aberration of the endoscopic optical system 100 has been well corrected, resulting in good imaging quality.

[0138] Fifth Embodiment

[0139] Please see Figure 9 , Figure 9This is a schematic diagram of the endoscope optical system 100 in the fifth embodiment. The endoscope optical system 100 includes, from the object side to the image side, a first lens L1 with negative optical power, a second lens L2 with positive optical power, an aperture S, a third lens L3 with positive optical power, a fourth lens L4 with positive optical power, a fifth lens L5 with negative optical power, and a protective glass CG.

[0140] The object-side surface of the first lens L1 is flat, and the image-side surface is concave.

[0141] The object-side surface of the second lens L2 is convex, while the image-side surface is flat.

[0142] The object-side surface of the third lens L3 is a plane, and the image-side surface is a convex surface.

[0143] The object-side surface of the fourth lens L4 is convex, and the image-side surface is also convex.

[0144] The object side of the fifth lens L5 is concave, and the image side is convex.

[0145] In addition, the parameters of the endoscope optical system 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.

[0146] Table 5

[0147]

[0148] Please see Figure 10A , Figure 10B and Figure 10C . Figure 10A This is a field curvature astigmatism curve of the endoscope optical system 100 in the fifth embodiment, derived from... Figure 10A It can be seen that the sagittal field curvature and meridional field curvature of the endoscope optical system 100 are both small, and the field curvature and astigmatism of each field of view are well corrected. The center and edge of the field of view have clear imaging, which is conducive to the endoscope optical system 100 obtaining a large depth of field effect.

[0149] Figure 10B This is a distortion curve diagram of the endoscope optical system 100 in the fifth embodiment, from... Figure 10B It can be seen that the endoscope optical system 100 has small distortion, the image distortion caused by the main beam is small, and the imaging quality of the system is excellent.

[0150] Figure 10C This is a magnification chromatic aberration curve of the endoscope optical system 100 in the fifth embodiment, derived from... Figure 10C It can be seen that the magnification chromatic aberration of the endoscopic optical system 100 has been well corrected, resulting in good imaging quality.

[0151] Table 6

[0152] LG1 / f 1.832 1.849 1.744 1.814 1.761 |fG1 / fG2| 1.406 1.352 1.286 1.265 1.160 f2 / f3 1.018 1.021 1.135 1.163 1.261 |f1 / f| 0.743 0.743 0.744 0.746 0.733 |R3 / R6| 1.476 1.487 1.468 1.510 1.424 Vd2 31.3 31.3 25.5 25.5 25.5

[0153] This application also provides an endoscope objective (not shown), including a photosensitive element and the endoscope optical system 100 described in any of the above embodiments. The photosensitive surface of the photosensitive element coincides with the image plane IMA of the endoscope optical system 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 endoscope optical system 100 in the endoscope objective achieves a balance between miniaturization, wide-angle characteristics, and high image quality, thereby facilitating the application of the endoscope objective in endoscopes.

[0154] 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 be the tube of 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 using 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 be used in the medical field to minimize damage to patients, acquire images of lesion areas over a wide area to avoid missed diagnoses, and form high-resolution images of lesions, improving diagnostic accuracy.

[0155] 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.

[0156] 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 endoscope optical system, characterized in that, Along the optical axis from the object side to the image side, it sequentially includes a first lens group with negative optical power, an aperture stop, and a second lens group with positive optical power. The first lens group, along the optical axis from the object side to the image side, sequentially includes a first lens with negative optical power and a second lens with positive optical power. The second lens group, along the optical axis from the object side to the image side, sequentially includes a third lens with positive optical power, a fourth lens with positive optical power, and a fifth lens with negative optical power. The image side of the first lens is concave. Furthermore, the endoscopic optical system satisfies the following condition: 1.7≤LG1 / f≤1.9; 1.15≤|fG1 / fG2|≤1.5; Wherein, LG1 is the distance from the object side of the first lens to the aperture on the optical axis, f is the effective focal length of the endoscope optical system, fG1 is the effective focal length of the first lens group, and fG2 is the effective focal length of the second lens group.

2. The endoscopic optical system according to claim 1, characterized in that, The image-side surface of the second lens is a plane, and the object-side surface of the third lens is a plane.

3. The endoscopic optical system according to claim 2, characterized in that, Both the image-side surface of the second lens and the object-side surface of the third lens are coated with a filter film.

4. The endoscopic optical system according to claim 1, characterized in that, The following conditions must be met: Vd2≤40; Where Vd2 is the Abbe number of the second lens.

5. The endoscopic optical system according to claim 1, characterized in that, The following conditions must be met: 0.95≤f2 / f3≤1.3; Where f2 is the effective focal length of the second lens and f3 is the effective focal length of the third lens.

6. The endoscopic optical system according to claim 1, characterized in that, The following conditions must be met: 0.7≤|f1 / f|≤0.8; Where f1 is the effective focal length of the first lens.

7. The endoscopic optical system according to claim 1, characterized in that, The following conditions must be met: 1.4≤|R3 / R6|≤1.6; Wherein, R3 is the radius of curvature of the object side of the second lens at the optical axis, and R6 is the radius of curvature of the image side of the third lens at the optical axis.

8. The endoscopic optical system according to claim 1, characterized in that, The following conditions must be met: 2ω≥130°; Wherein, 2ω is the maximum field of view of the endoscope optical system.

9. An endoscope objective, characterized in that, It includes a photosensitive element and an endoscope optical system as described in any one of claims 1-8, wherein the photosensitive element is disposed on the image side of the endoscope optical system.

10. An endoscope, characterized in that, Includes the endoscope objective as described in claim 9.

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