Optical adapter and endoscope

Abstract

The utility model relates to an optical adapter and an endoscope. The optical adapter sequentially comprises a first cemented lens group with positive focal power from an object side to an image side along an optical axis, the first cemented lens group comprises a first lens and a second lens which are cemented and are sequentially arranged from the object side to the image side along the optical axis, and the object side surface of the first lens is a convex surface; the second cemented lens group has positive focal power, the second cemented lens group comprises a third lens and a fourth lens which are cemented and are sequentially arranged from the object side to the image side along the optical axis, and the image side surface of the fourth lens is a convex surface; and the fifth lens has negative focal power, and the image side surface of the fifth lens is a convex surface. The optical adapter is favorable for correcting various aberrations such as chromatic aberration and distortion, improving the relative illumination of imaging and improving the imaging resolution, thereby being favorable for improving the imaging quality of the optical adapter.

Description

Technical Field

[0001] This application relates to the field of endoscope technology, and in particular to an optical adapter and an endoscope. Background Technology

[0002] An endoscope is a medical device that can be inserted into the human body for observation, diagnosis, or treatment. An endoscope typically includes an endoscope image processing unit, a light source, an optical adapter, and an endoscope mirror. The endoscope mirror is inserted into the body to acquire images. The optical adapter connects the endoscope mirror and the image sensor of the endoscope image processing unit, enabling the adjustment and transmission of light to transfer the images acquired by the endoscope mirror to the image sensor. However, current optical adapters generally suffer from poor image quality. Utility Model Content

[0003] Therefore, it is necessary to provide an optical adapter and endoscope to address the problem of poor imaging quality of current optical adapters.

[0004] An optical adapter, comprising, along the optical axis from the object side to the image side, the following components in sequence:

[0005] A first cemented lens assembly with positive optical power, the first cemented lens assembly includes a first lens and a second lens cemented together and arranged sequentially from the object side to the image side along the optical axis, the object side of the first lens being convex;

[0006] A second cemented lens assembly with positive optical power, the second cemented lens assembly including a third lens and a fourth lens cemented together and arranged sequentially from the object side to the image side along the optical axis, the image side of the fourth lens being convex;

[0007] A fifth lens with negative optical power, wherein the image-side surface of the fifth lens is convex.

[0008] The optical adapter described above features a well-designed lens with appropriate power and surface shape. Combined with the design of the cemented lens assembly, this design helps to correct various aberrations such as chromatic aberration and distortion, improves relative illumination, and enhances image resolution. This, in turn, improves the image quality of the optical adapter. When used in endoscopes, this design enhances the accuracy of diagnosis and treatment. It also helps to reduce the size of the optical adapter, making it easier for users to operate and hold the endoscope for extended periods.

[0009] In one embodiment, the first lens has negative optical power, the second lens has positive optical power, the third lens has negative optical power, and the fourth lens has positive optical power.

[0010] In one embodiment, the image-side surface of the first lens is concave, the object-side surface of the second lens is convex and the image-side surface is concave, the object-side surface of the third lens is concave and the image-side surface is convex, the object-side surface of the fourth lens is concave, and the object-side surface of the fifth lens is concave.

[0011] In one embodiment, the optical adapter further includes a light-transmitting protective element disposed on the object side of the first cemented lens assembly, and the optical adapter satisfies the following condition:

[0012] 0.2≤CT2 / (T12+T23)≤0.5;

[0013] Wherein, CT2 is the thickness of the first cemented lens assembly on the optical axis, T12 is the distance on the optical axis from the image side of the light-transmitting protective element to the object side of the first cemented lens assembly, and T23 is the distance on the optical axis from the image side of the first cemented lens assembly to the object side of the second cemented lens assembly.

[0014] In one embodiment, the optical adapter satisfies the following condition:

[0015] 0.1 ≤ f2 / (f2+f3) ≤ 0.3;

[0016] Where f2 is the focal length of the first cemented lens group and f3 is the focal length of the second cemented lens group.

[0017] In one embodiment, the optical adapter satisfies the following condition:

[0018] 0.2≤CT4 / T34≤0.4;

[0019] Wherein, CT4 is the thickness of the fifth lens on the optical axis, and T34 is the distance on the optical axis from the image side of the second cemented lens group to the object side of the fifth lens.

[0020] In one embodiment, the optical adapter satisfies the following condition:

[0021] 3°≤Semi-FOV≤8°;

[0022] Wherein, Semi-FOV is half of the maximum field of view of the optical adapter.

[0023] In one embodiment, the optical adapter satisfies the following condition:

[0024] 25mm≤f≤30mm;

[0025] Where f is the focal length of the optical adapter.

[0026] In one embodiment, the optical adapter further includes an aperture stop disposed on the object side of the first cemented lens assembly.

[0027] An endoscope including an optical adapter as described in any of the above embodiments. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of the optical adapter in some embodiments.

[0029] Figure 2 This is a transfer function graph of the optical adapter in some embodiments.

[0030] Figure 3 This is a defocus curve diagram of the optical adapter in some embodiments.

[0031] Figure 4 This is a dot plot of the optical adapter in some embodiments.

[0032] Figure 5 The diagram shows the field curvature and distortion curves of the optical adapter in some embodiments.

[0033] Figure label:

[0034] 10. Optical adapter; E1. Light transmission protection element; S3. Aperture stop; E2. First cemented lens group; E21. First lens; E22. Second lens; E3. Second cemented lens group; E31. Third lens; E32. Fourth lens; E4. Fifth lens; S12. Imaging plane. Detailed Implementation

[0035] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are 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 this application. However, this application can be implemented 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 this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0036] In the description of this application, it should be understood that if terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application 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, and therefore should not be construed as a limitation of this application.

[0037] Furthermore, where the terms "first" and "second" appear, these terms are 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 with "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, where the term "multiple" appears, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0038] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," 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 expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0039] In this application, unless otherwise expressly specified and limited, the use of descriptions such as "above" or "below" the second feature indicates that the first and second features are in direct contact or indirect contact via an intermediate medium. Furthermore, "above," "on top of," and "over" 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. Similarly, "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.

[0040] It should be noted that if 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. If 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. If so, the terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application are for illustrative purposes only and do not represent the only possible implementation.

[0041] Please see Figure 1 , Figure 1 This is a schematic diagram of the optical adapter 10 in the first embodiment. The optical adapter 10 provided in this application can be used in medical devices, such as endoscopes. In some embodiments, the endoscope may further include an endoscope mirror and an image sensor. The optical adapter 10 is disposed in the endoscope mirror and the image sensor. The endoscope mirror can at least partially extend into the human body to collect images of the lesion area. The light collected by the endoscope mirror can be adjusted and transmitted by the optical adapter 10 and then transmitted to the image sensor. The optical adapter 10 plays a connecting and adapting role between the endoscope mirror and the image sensor to improve the imaging quality of the endoscope.

[0042] Furthermore, in some embodiments, the optical adapter 10 contains five lenses with optical power. The optical adapter 10 includes, sequentially from the object side to the image side, a first cemented lens group E2, a second cemented lens group E3, and a fifth lens E4 along the optical axis. The first cemented lens group E2 includes a first lens E21 and a second lens E22 cemented together and sequentially arranged from the object side to the image side along the optical axis. The second cemented lens group E3 includes a third lens E31 and a fourth lens E32 cemented together and sequentially arranged from the object side to the image side along the optical axis. The optical adapter 10 has an imaging surface S12. When the optical adapter 10 is installed in an endoscope, the imaging surface S12 can at least partially overlap with the photosensitive surface of the image sensor. Light from the object side can be directed onto the imaging surface S12 after being adjusted sequentially by the lenses in the optical adapter 10. The first cemented lens group E2 has positive optical power, that is, the combined optical power of the first lens E21 and the second lens E22 is positive. The object side of the first cemented lens group E2 is convex, that is, the object side of the first lens E21 is convex. The second cemented lens group E3 has positive optical power, that is, the combined optical power of the third lens E31 and the fourth lens E32 is positive. The image side of the second cemented lens group E3 is convex, that is, the image side of the fourth lens E32 is convex. The fifth lens E4 has negative optical power, and the image side of the fifth lens E4 is convex.

[0043] The aforementioned optical adapter 10 features a rationally designed lens power and surface shape. Combined with the cemented lens assembly design, this facilitates the correction of various aberrations such as chromatic aberration and distortion, improves relative illumination, and enhances image resolution. This, in turn, improves the image quality of the optical adapter 10, enhancing the accuracy of diagnosis and treatment when used in endoscopes. Furthermore, it allows for a reduction in the size of the optical adapter 10, making it easier for users to operate and hold the endoscope for extended periods. Additionally, it increases the depth of field of the optical adapter 10, improving its imaging capabilities and adapting to the acquisition needs of endoscopes.

[0044] Specifically, the optical power and convex object-side design of the first cemented lens group E2 effectively converge incident light rays, thereby capturing more light, improving light energy collection efficiency, and enhancing image brightness. It also helps correct aberrations such as spherical aberration, improving image quality. Furthermore, it helps compress the axial dimensions of the optical adapter 10. The cemented arrangement of the first lens E21 and the second lens E22 also helps balance chromatic aberration, improving image quality. The optical power and surface shape of the second cemented lens group E3 complement the first cemented lens group E2, effectively controlling the light propagation path and effectively correcting and balancing aberrations such as field curvature and astigmatism, thus improving the image quality of the optical adapter 10. The optical power and surface shape of the fifth lens E4 work together to effectively diverge light rays onto the imaging surface S12, improving the matching degree between the incident angle of light on the imaging surface S12 and the image sensor, thereby improving relative illumination and resolution.

[0045] In some embodiments, the first lens E21 has negative optical power, the second lens E22 has positive optical power, the third lens E31 has negative optical power, and the fourth lens E32 has positive optical power. The image-side surface of the first lens E21 is concave, the object-side surface of the second lens E22 is convex and the image-side surface is concave, the object-side surface of the third lens E31 is concave and the image-side surface is convex, the object-side surface of the fourth lens E32 is concave, and the object-side surface of the fifth lens E4 is concave. The combination of the optical power and surface shape of the first lens E21 and the second lens E22 allows for reasonable control of the propagation path of the light rays collected by the object-side surface of the first lens E21, which is beneficial for correcting aberrations such as spherical aberration and coma. Simultaneously, it reduces the burden on the refracted light rays of each image-side lens, which helps to reduce the aberration sensitivity and tolerance sensitivity of each lens, thereby improving the forming yield and assembly yield of each lens. The optical power and surface shape of the third lens E31 and the fourth lens E32 are well-matched with the first cemented lens group E2, which can reasonably control the optical power distribution in the optical adapter 10, suppress the generation of various aberrations, and improve the imaging quality of the optical adapter 10. The object side of the fifth lens E4 is concave, which, together with the other optical power and surface shape designs, helps to make the direction of edge rays more reasonable, suppresses aberrations in the edge field of view, and improves the imaging quality of the edge field of view. At the same time, it also helps to suppress aberrations such as field curvature and distortion, thus improving the imaging quality of the optical adapter 10.

[0046] In some embodiments, the optical adapter 10 further includes an aperture stop S3, which is disposed on the object side of the first cemented lens group E2. The front-positioned design of the aperture stop S3, combined with the optical power and surface design of each lens in the optical adapter 10, helps to improve the structural compactness of the optical adapter 10, thereby further reducing the axial dimensions of the optical adapter 10 and facilitating long-term operation and handling of the endoscope by the user. In some embodiments, the optical adapter 10 further includes a light-transmitting protection element E1, which is disposed on the object side of the first cemented lens group E2. The light-transmitting protection element E1 includes, but is not limited to, flat glass, used to protect each lens in the optical adapter 10. In some embodiments, the material of each lens in the optical adapter 10 includes, but is not limited to, any suitable glass or plastic. Using common and readily available materials helps to reduce processing difficulty and manufacturing costs.

[0047] In some embodiments, the optical adapter 10 satisfies the following conditions: 3° ≤ Semi-FOV ≤ 8°; 25mm ≤ f ≤ 30mm; where Semi-FOV is half of the maximum field of view of the optical adapter 10, and f is the focal length of the optical adapter 10. When the above conditions are met, the optical power and surface design of each lens can balance the field of view and imaging quality of the optical adapter 10, achieving good imaging quality while meeting the imaging requirements of the endoscope, thereby improving the accuracy of diagnosis and treatment.

[0048] In the first embodiment, the optical adapter 10 satisfies the condition: 0.2 ≤ CT2 / (T12+T23) ≤ 0.5; where CT2 is the thickness of the first cemented lens group E2 on the optical axis, i.e., the distance on the optical axis from the object side of the first lens E21 to the image side of the second lens E22; T12 is the distance on the optical axis from the image side of the light-transmitting protective element E1 to the object side of the first cemented lens group E2 (i.e., the object side of the first lens E21); and T23 is the distance on the optical axis from the image side of the first cemented lens group E2 (i.e., the image side of the second lens E22) to the object side of the second cemented lens group E3 (i.e., the object side of the third lens E31). For example, CT2 / (T12+T23) can be 0.2, 0.3, 0.4, or 0.5. When the above conditions are met, the optical adapter 10's structural compactness is improved, reducing its axial dimensions. This also allows for sufficient space to be reserved for light propagation on the object side of the first cemented lens group E2, optimizing light path and thus helping to suppress various aberrations such as spherical aberration, astigmatism, and field curvature. Simultaneously, it increases the focusing range of the optical adapter 10, thereby increasing its depth of field.

[0049] In the first embodiment, the optical adapter 10 satisfies the condition: 0.1 ≤ f2 / (f2+f3) ≤ 0.3; where f2 is the focal length of the first cemented lens group E2, i.e., the combined focal length of the first lens E21 and the second lens E22, and f3 is the focal length of the second cemented lens group E3, i.e., the combined focal length of the third lens E31 and the fourth lens E32. For example, f2 / (f2+f3) can be 0.1 or 0.2. When the above condition is satisfied, the optical power distribution of the first cemented lens group E2 and the second cemented lens group E3 can be reasonably configured, which is beneficial to suppressing the generation of various aberrations such as distortion, improving the imaging quality of the optical adapter 10, and also helps to compress the axial dimension of the optical adapter 10.

[0050] In the first embodiment, the optical adapter 10 satisfies the condition: 0.2 ≤ CT4 / T34 ≤ 0.4; where CT4 is the thickness of the fifth lens E4 on the optical axis, and T34 is the distance on the optical axis from the image-side surface of the second cemented lens group E3 (i.e., the image-side surface of the fourth lens E32) to the object-side surface of the fifth lens E4. For example, CT5 / T45 can be 0.2, 0.3, or 0.4. Satisfying the above condition is beneficial to improving the structural compactness of the optical adapter 10, thereby reducing the axial dimensions of the optical adapter 10. It also helps to take into account the tolerance sensitivity of the optical adapter 10, improve the assembly yield of the optical adapter 10, reduce the assembly difficulty, and further facilitate the reasonable control of the light path between the second cemented lens group E3 and the fifth lens E4, balancing various aberrations such as chromatic aberration, astigmatism, and field curvature, thereby improving the imaging quality of the optical adapter 10.

[0051] Please see Figures 2-5 As shown, Figure 2 Here are some MTF (Mean Transfer Function) curves for the optical adapter 10 in certain embodiments. Figure 3 Here are defocus curves for the optical adapter 10 in some embodiments. Figure 4 This is a dot plot of the optical adapter 10 in some embodiments. Figure 5 Here are field curvature and distortion curves for the optical adapter 10 in some embodiments. Figures 2-5 As can be seen, in some embodiments, when the resolution of the optical adapter 10 meets 250 lp / mm, the MTF value across the entire field of view is greater than 0.2 and close to the diffraction limit. In the dot plot, the diffuse spots are all close to the Airy disk, and the spot diameter is mostly contained within the Airy disk, essentially at the diffraction limit. The distortion across the entire field of view is less than 1%. Therefore, the optical adapter 10 has good imaging quality, balancing clear imaging and small size requirements, and meets the needs of 4K optical mounts.

[0052] 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.

[0053] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. An optical adapter, characterized by, Along the optical axis from the object side to the image side, the following are included in sequence: A first cemented lens assembly with positive optical power, the first cemented lens assembly includes a first lens and a second lens cemented together and arranged sequentially from the object side to the image side along the optical axis, the object side of the first lens being convex; A second cemented lens assembly with positive optical power, the second cemented lens assembly including a third lens and a fourth lens cemented together and arranged sequentially from the object side to the image side along the optical axis, the image side of the fourth lens being convex; A fifth lens with negative optical power, wherein the image-side surface of the fifth lens is convex.

2. The optical adapter of claim 1, wherein, The first lens has negative optical power, the second lens has positive optical power, the third lens has negative optical power, and the fourth lens has positive optical power.

3. The optical adapter of claim 2, wherein, The first lens has a concave image side, the second lens has a convex object side and a concave image side, the third lens has a concave object side and a convex image side, the fourth lens has a concave object side, and the fifth lens has a concave object side.

4. The optical adapter of any of claims 1-3, wherein, The optical adapter further includes a light-transmitting protective element disposed on the object side of the first cemented lens assembly, and the optical adapter satisfies the following condition: 0.2≤CT2 / (T12+T23)≤0.5; Wherein, CT2 is the thickness of the first cemented lens assembly on the optical axis, T12 is the distance on the optical axis from the image side of the light-transmitting protective element to the object side of the first cemented lens assembly, and T23 is the distance on the optical axis from the image side of the first cemented lens assembly to the object side of the second cemented lens assembly.

5. The optical adapter according to any one of claims 1-3, characterized in that, The optical adapter satisfies the following condition: 0.1 ≤ f2 / (f2+f3) ≤ 0.3; Where f2 is the focal length of the first cemented lens group and f3 is the focal length of the second cemented lens group.

6. The optical adapter of any one of claims 1-3, wherein, The optical adapter satisfies the following condition: 0.2≤CT4 / T34≤0.4; Wherein, CT4 is the thickness of the fifth lens on the optical axis, and T34 is the distance on the optical axis from the image side of the second cemented lens group to the object side of the fifth lens.

7. The optical adapter of any of claims 1-3, wherein, The optical adapter satisfies the following condition: 3°≤Semi-FOV≤8°; Wherein, Semi-FOV is half of the maximum field of view of the optical adapter.

8. The optical adapter of any of claims 1-3, wherein, The optical adapter satisfies the following condition: 25mm≤f≤30mm; Where f is the focal length of the optical adapter.

9. The optical adapter of any of claims 1-3, wherein, The optical adapter also includes an aperture stop, which is located on the object side of the first cemented lens assembly.

10. An endoscope characterized by comprising: Includes the optical adapter as described in any one of claims 1-9.

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