Optical systems and endoscopes

Abstract

This application relates to an optical system and an endoscope. The optical system includes a front lens, a light path conversion element, a rear mirror assembly, and a sensor arranged sequentially from the object side to the image side. The light path conversion element is used to change the direction of light propagation, causing the light rays passing through the front lens to be deflected and incident on the rear mirror assembly. The optical system satisfies: 0.9 < |f F / f|<1.1, 1.2<f R / f < 1.7, 0.63 < |f F / f R |<0.88, where f F f is the focal length of the front lens. R f is the focal length of the rear mirror group, and f is the focal length of the optical system. This application, through the arrangement of the front lens, the optical path conversion element, and the rear mirror group, and by defining the relationship between the focal length of the front lens, the focal length of the rear mirror group, and the focal length of the optical system, enables the optical system to have a better field of view, better image quality, and better miniaturization design.

Description

Technical Field

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

[0002] In the field of endoscopy, traditional emphyseal endoscopes can only provide a frontal view along the insertion axis, while oblique endoscopes can achieve multi-angle observation by deflecting the optical axis. In the medical field, departments have specific requirements regarding the observation angles of endoscopes, making the development of oblique endoscopes crucial.

[0003] However, endoscopes in related technologies often fail to simultaneously achieve miniaturization, a wide field of view, and high imaging quality. Utility Model Content

[0004] Therefore, it is necessary to provide an optical system and endoscope to address the problem that endoscopes in related technologies cannot simultaneously achieve miniaturization, a wide field of view, and high imaging quality.

[0005] According to one aspect of this application, an optical system is provided, comprising: a front lens and a rear lens group sequentially arranged from the object side to the image side; the optical system satisfies:

[0006] 0.9 < |f F / f|<1.1;

[0007] 1.2 < f R / f < 1.7;

[0008] 0.63 < |f F / f R | < 0.88;

[0009] Wherein, the f F The focal length of the front lens is f. R f is the focal length of the rear mirror group, and f is the focal length of the optical system.

[0010] In one embodiment, the optical system also satisfies:

[0011] FOV ≥ 120°;

[0012] D1≤2.5;

[0013] Wherein, FOV is the field of view of the optical system, and D1 is the outer diameter of the front lens.

[0014] In one embodiment, the front lens has negative optical power, and the light-emitting surface of the front lens is concave.

[0015] In one embodiment, the rear lens group has positive optical power, and the rear lens group includes a first lens and a cemented lens group arranged sequentially from the object side to the image side, the first lens having positive optical power, and the cemented lens group having positive optical power; the cemented lens group includes a second lens and a third lens cemented together with each other;

[0016] The first lens has positive optical power, and the light-incident surface of the first lens is convex, and the light-exit surface is convex.

[0017] The second lens has positive optical power, and the light-incident surface and the light-exit surface of the first lens are both convex.

[0018] The third lens has negative optical power, and the light-incident surface of the third lens is concave, while the light-outceasing surface is convex.

[0019] In one embodiment, the optical system further satisfies:

[0020] vd1 > 50;

[0021] vd2 > vd1;

[0022] Wherein, vd1 is the Abbe coefficient of the second lens, and vd2 is the Abbe coefficient of the third lens.

[0023] In one embodiment, the optical system further includes a light path conversion element and an aperture. The light path conversion element is disposed between the front lens and the rear lens group, and the light path conversion element is used to change the direction of light propagation so that the light passing through the front lens is deflected and incident on the rear lens group.

[0024] The aperture is located on the object side or image side of the optical path conversion element.

[0025] In one embodiment, the optical system also satisfies:

[0026] n > 1.8;

[0027] Wherein, n is the refractive index of the optical path conversion element.

[0028] In one embodiment, the optical system also satisfies:

[0029] 6mm≤L≤9mm;

[0030] Where L is the total optical length of the optical system.

[0031] According to another aspect of this application, an endoscope is provided, including the optical system and endoscope tube of any of the above embodiments, wherein the optical system is disposed within the endoscope tube;

[0032] The lens barrel includes a first sleeve, which includes a first inner circumferential portion and a second inner circumferential portion. The front lens is installed in the first inner circumferential portion, and an optical path conversion element is installed in the second inner circumferential portion. The axial direction of the first inner circumferential portion intersects with the axial direction of the second inner circumferential portion.

[0033] In one embodiment, the lens barrel further includes a second sleeve and a third sleeve;

[0034] The rear mirror assembly is installed inside the second sleeve, and a sensor is installed inside the third sleeve. The sensor is used to receive light passing through the optical system and generate a digital image. A portion of the first sleeve is fitted over the second sleeve, and a portion of the third sleeve is fitted over the second sleeve.

[0035] The aforementioned optical system, through the arrangement of the front lens and rear mirror group, and the limitation of the focal length of the front lens, rear mirror group, and the optical system itself, achieves a superior miniaturized design, a larger field of view, and better image quality. It can be understood that if |f F If |f| is higher than 1.1, the field of view of the optical system becomes smaller, failing to meet the observation requirements for a large field of view. If |f| F When |f| is below 0.9, the field of view of the optical system expands further, but at the same time, the outer diameter of the front lens increases, which is detrimental to the miniaturization of the optical system. Therefore, |f| F / f| satisfies 0.9 < |f F A range where f| < 1.1 is advantageous for enabling optical systems to have a better field of view and a more compact design. If f R If f is below 1.2, the image position of the light rays passing through the rear mirror group is relatively close to the rear mirror group, which is not conducive to the subsequent adjustment of the sensor's position relative to the rear mirror group. In other words, the adjustment interval between the rear mirror group and the sensor is insufficient, affecting assembly and debugging. If f R When f is higher than 1.7, the image position of the light rays passing through the rear mirror group is farther from the rear mirror group, requiring the sensor to be adjusted to a farther position to obtain a clear image, which is detrimental to the miniaturization design of the optical system. Therefore, f... R / f satisfies 1.2 < f R A range where f < 1.7 is beneficial for the assembly, debugging, and miniaturization design of optical systems. If |f F / f RIf the refractive power of the front lens is below 0.63, the refractive power of the front lens increases, the field of view of the optical system increases, and the height of the light rays passing through the front lens increases. This necessitates a larger outer diameter for the front lens to capture this field of view. Simultaneously, the increased field of view leads to darkening of the peripheral areas of the observed image. To achieve better brightness in the peripheral areas, stronger illumination light is required, resulting in a larger optical system size, increased light source power, and difficulties in heat dissipation. Adding heat dissipation components also hinders the miniaturization design of the endoscope. In other words, if |f F / f R If the value is below 0.63, it is detrimental to the miniaturization of the endoscope, both from the perspective of increasing the outer diameter of the optical system itself and from the perspective of adding an additional matching illumination module. If |f F / f R If the focal length is higher than 0.88, the refractive power of the front lens decreases, resulting in a smaller field of view for the optical system. Furthermore, when the light rays from the front lens and the rear lens group are deflected, the generated image is prone to unilateral blurring, which is detrimental to image quality. In summary, this application, by configuring the front lens and rear lens group and defining the relationship between the focal lengths of the front lens, the rear lens group, and the optical system, enables the optical system to achieve a better field of view, better image quality, and a more compact design. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the structure of the optical system in some embodiments of this application.

[0037] Figure 2 for Figure 1 The optical path conversion element of the optical system in the illustrated embodiment is shown as an unfolded and plotted lens cross-section diagram.

[0038] Figure 3 This is a schematic diagram of the optical system disposed inside the lens barrel in some embodiments of this application.

[0039] Figure 4 This is a schematic diagram of the lens barrel structure in some embodiments of this application.

[0040] Explanation of icon numbers:

[0041] 10. Optical system;

[0042] 1. Front lens; 2. Optical path conversion element; 3. Rear lens group; 31. First lens; 321. Second lens; 322. Third lens; 4. Sensor; 5. Aperture;

[0043] 61. First sleeve; 611. First inner circumference; 612. Second inner circumference; 62. Second sleeve; 621. Third inner circumference; 622. Fourth inner circumference; 63. Third sleeve; 7. Protective lens; 8. Spacer. Detailed Implementation

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] Endoscopes are primarily used in minimally invasive surgery to provide surgeons with clear, wide-angle images, reducing the risk of blind spots during procedures. Different departments have varying requirements for observation angles. For example, pyeloscopy in urology requires an angle of approximately 70° to fully observe the renal pelvis structure, while gastroscopy and colonoscopy often use an angle of 30°-45° to observe the area behind the mucosal folds. Laparoscopic surgery may require angles exceeding 90° to observe the interaction between the surgical instruments and tissues. In other words, most departments require endoscopes with oblique viewing capabilities to provide images from the corresponding perspectives.

[0051] The oblique-view objective lens optical system is a key optical component for endoscopes to achieve multi-angle observation. Endoscopes equipped with this optical system are mainly used in minimally invasive surgery to provide doctors with clear, wide-angle observation images and reduce the risk of blind spots in surgery.

[0052] In related technologies, oblique-viewing objective optical systems, such as those using simple lens combinations, suffer from problems such as a large overall system size, insufficient aberration correction capability, and significant degradation of image quality in the peripheral field of view, making it difficult to meet the miniaturization requirements of modern minimally invasive surgery. Furthermore, some related technologies employ specific lens combinations and strict condition constraints to shorten the size of the optical system. However, when the diameter of the optical system shrinks to a certain size, its optical performance deteriorates significantly. These technologies do not adequately consider aberration characteristics changes under ultra-narrow diameter conditions, and when the field of view exceeds a certain angle, the modulation transfer function (MTF) value of the optical system's edge region drops sharply, severely affecting the sharpness of image edges and diagnostic value. This degradation is particularly pronounced during large-field-of-view oblique observation, making it difficult for surgeons to clearly identify the fine structures at the edges of lesions. In some related technologies, lenses work together to ensure a sufficient field of view, but longer lens groups are needed to balance the optical power, which objectively increases the overall length of the optical system. Moreover, from the perspective of manufacturing tolerances, longer optical systems are more sensitive, making it more difficult to guarantee the mass production consistency of longer optical systems.

[0053] Based on this, this application provides an optical system and an endoscope, wherein the optical system has a better field of view, a smaller size, and better imaging quality.

[0054] See Figure 1 and Figure 2 As shown, Figure 1 This is a schematic diagram of the structure of the optical system 10 in some embodiments of this application. Figure 2 for Figure 1 The optical path conversion element 2 of the optical system 10 in the embodiment shown is unfolded and plotted as a lens cross-section.

[0055] This application provides an optical system 10, which includes a front lens 1 and a rear lens group 3 arranged sequentially from the object side to the image side.

[0056] And optical system 10 satisfies:

[0057] 0.9 < |f F / f|<1.1, where f F Let f be the focal length of the front lens 1, and f be the focal length of the optical system 10. For example, |f F / f| can be 0.95, 1, or 1.05.

[0058] It is understandable that if |f F If |f| is higher than 1.1, the field of view of optical system 10 becomes smaller, failing to meet the observation requirements for a large field of view. If |f| FIf |f| is less than 0.9, the field of view of the optical system 10 will further expand, but at the same time, the outer diameter of the front lens 1 will increase, which is not conducive to the miniaturization of the optical system 10. Therefore, |f| F / f| satisfies 0.9 < |f F The range of / f|<1.1 is beneficial for the optical system 10 to have a better field of view and a better miniaturized design.

[0059] Optical system 10 also satisfies 1.2 < f R / f<1.7, f R This is the focal length of the rear lens group 3. For example, f. R / f can be 1.3, 1.4, or 1.5.

[0060] If f R If the f value is less than 1.2, the imaging position of the light rays passing through the rear mirror group 3 will be relatively close to the rear mirror group 3, which is not conducive to the adjustment of the position of the sensor 4 relative to the rear mirror group 3. That is, the adjustment interval between the rear mirror group 3 and the sensor 4 is insufficient, which affects the assembly and debugging.

[0061] The sensor 4 is located on the light-emitting side of the rear mirror group 3, and is used to receive the light emitted from the rear mirror group 3 and generate an image for the doctor to view and examine.

[0062] If f R If f is higher than 1.7, the image position of the light rays passing through the rear mirror group 3 will be farther from the rear mirror group 3, causing the sensor 4 to need to be adjusted to a farther position to obtain a clear image, which is not conducive to the miniaturization design of the optical system 10. Therefore, satisfying 1.2 < f R The range of f < 1.7 is beneficial for the assembly, debugging, and miniaturization design of the optical system 10.

[0063] Optical system 10 also satisfies 0.63 < |f F / f R | < 0.88, for example |f F / f R | It can be 0.65, 0.7 or 0.8.

[0064] By satisfying the above range, the focal length of the front lens 1 and the focal length of the rear lens group 3 are relatively balanced, which is conducive to achieving good aberration correction and improving resolution. Thus, while enabling the optical system 10 to have a better field of view, the optical system 10 also has better imaging quality.

[0065] It's understandable, if |f F / f RIf the refractive power of the front lens 1 is higher than 0.88, the refractive power of the front lens 1 will decrease, resulting in a smaller field of view of the optical system 10. Furthermore, if the light rays from the front lens 1 and the rear lens group 3 are deflected, the generated image is prone to unilateral blurring, which is detrimental to the image quality.

[0066] If |f F / f R If the refractive power of the front lens 1 is less than 0.63, the refractive power of the front lens 1 increases, the field of view of the optical system 10 increases, and the height of the light rays passing through the front lens 1 increases. This necessitates a larger outer diameter for the front lens 1 to capture this field of view. Simultaneously, the increased field of view leads to darkening of the peripheral areas of the observed image. To achieve better brightness in the peripheral areas, stronger illumination light is required, which increases the size of the optical system 10, increases the power of the light source, and makes heat dissipation difficult. Adding heat dissipation components is also detrimental to the miniaturization design of the endoscope. In other words, if |f F / f R If the value is below 0.63, it is not conducive to the miniaturization of the endoscope, whether from the perspective of increasing the outer diameter of the optical system 10 itself or from the perspective of adding an additional matching illumination module.

[0067] Therefore, by setting the front lens 1 and the rear lens group 3, and defining the relationship between the focal length of the front lens 1, the focal length of the rear lens group 3 and the focal length of the optical system 10, this application enables the optical system 10 to have a better field of view, better imaging quality and a better miniaturized design.

[0068] In this embodiment, further, 0.95 < |f F / f|<1.05, 1.3<f R / f < 1.6, which helps to further improve the field of view and miniaturization of the optical system 10, while also providing better imaging quality, thus improving image quality and the accuracy of doctors' judgment during the detection process.

[0069] In this embodiment, the optical system 10 further includes a light path conversion element 2, which is disposed between the front lens 1 and the rear mirror group 3. The light path conversion element 2 is used to change the direction of light propagation, causing the light rays passing through the front lens 1 to be deflected and incident on the rear mirror group 3. The propagation direction of the light rays propagating in the front lens 1 intersects with the propagation direction of the light rays propagating in the rear mirror group 3. Ambient light passes through the front lens 1 and the light path conversion element 2 in sequence and then enters the rear mirror group 3, thereby forming an image for observation. That is, the front lens 1 can be set at an angle to obtain light rays at an angle, and the light rays are propagated and incident on the rear mirror group 3 through the light path conversion element 2.

[0070] In this embodiment, a flat glass plate can be provided on the object side of the front lens 1 for protection, or the flat glass plate can be omitted. If the flat glass plate is omitted, the material of the front lens 1 can be set to high-hardness glass. The specific settings can be set according to actual needs, and no further restrictions are imposed here.

[0071] In this embodiment, as Figure 1 The light path conversion element 2 can include two reflective surfaces. The light emitted from the front lens 1 passes through the two reflective surfaces in sequence and is reflected to the rear mirror group 3, thereby achieving the deflection of the light propagation direction. The light path conversion element 2 can be a prism or a mirror, without much restriction.

[0072] In some embodiments, the optical system 10 further satisfies: FOV ≥ 120°, D1 ≤ 2.5. For example, FOV can be 125°, 130°, or 140°.

[0073] Wherein, FOV is the field of view of optical system 10, and D1 is the outer diameter of front lens 1. It can be understood that the field of view of optical system 10 is mainly determined by the refractive index of front lens 1. A larger refractive index of front lens 1 can increase the field of view of optical system 10, while the outer diameter of the negative lens also needs to be larger to receive more light. The field of view and outer diameter of front lens 1 of the optical system 10 in this application satisfy the above-mentioned range, which is beneficial for maintaining a balance between the field of view and the outer diameter of front lens 1, allowing it to have a large field of view while also having a small radial dimension.

[0074] In some embodiments, see Figure 1 and Figure 2 As shown, the front lens 1 has negative optical power, and the light-emitting surface of the front lens 1 is concave, which is conducive to forming a strong divergence structure and can form a wider incident beam angle in the object side, thereby helping to obtain a larger field of view.

[0075] See Figure 1 and Figure 2 As shown, in some embodiments, the rear lens group 3 has a positive optical power, which, together with the negative optical power of the front lens 1, is used to modulate the light propagation path so as to modulate the light to form an image.

[0076] Furthermore, the rear mirror group 3 includes a first lens 31 and a cemented lens group arranged sequentially from the object side to the image side. The first lens 31 has positive optical power, and the cemented lens group also has positive optical power. The positive optical power of the first lens 31 and the positive optical power of the cemented lens group work together to gradually reduce the height of the light rays, which is beneficial for reducing the aperture of the optical system 10, i.e., for reducing the radial dimension of the optical system 10, and for miniaturization design.

[0077] The cemented lens assembly includes a second lens 321 and a third lens 322 cemented together. This facilitates the acquisition of images at the strabismus angle, enabling strabismus of the endoscope, while also promoting the miniaturization of the optical system 10.

[0078] In this embodiment, the first lens 31 has positive optical power, and both its incident and exit surfaces are convex. The biconvex structure of the first lens 31 provides a relatively symmetrical positive optical power distribution, which helps to reduce the spherical aberration sensitivity of the optical system 10, improve resolution, and enhance imaging quality.

[0079] In this embodiment, the second lens 321 has positive optical power, and the light-incident surface and the light-exit surface of the first lens 31 are both convex. The second lens 321 and the first lens 31 share the optical power, which can reduce the refractive power of a single lens, thereby facilitating a smooth transition of light, reducing light distortion, and improving the quality of light imaging.

[0080] In this embodiment, the third lens 322 has negative optical power, and its incident surface is concave while its exit surface is convex. The combination of the concave and convex surfaces of the third lens 322 with negative optical power allows it to work in conjunction with the second lens 321 to form an achromatic doublet lens. This is beneficial for eliminating chromatic aberration, reducing image color fringing, thereby improving image quality and increasing the diagnostic accuracy of the endoscope.

[0081] In some embodiments, the optical system 10 further satisfies: vd1 > 50, vd2 > vd1, where vd1 is the Abbe coefficient of the second lens 321 and vd2 is the Abbe coefficient of the third lens 322. For example, vd1 can be 55, 60, or 65.

[0082] Thus, the second lens 321 uses a low-dispersion material, such as a low-dispersion glass material, while the third lens 322 uses a high-dispersion material, such as a high-dispersion glass material. The third lens 322 can also use a glass material with anomalous dispersion properties, so that the second lens 321 and the third lens 322 work together to achieve a good aberration correction effect.

[0083] In this embodiment, the second lens 321 can also be made of an ultra-low dispersion material so that the Abbe coefficient of the second lens 321 satisfies: vd > 80, so as to further improve the aberration correction effect.

[0084] like Figure 1In some embodiments, the optical system 10 further includes an aperture 5, which is disposed on the object side or image side of the optical path conversion element 2. Thus, by placing the aperture 5 near the optical path conversion element 2, or in other words, configuring the optical path conversion element 2 near the aperture 5, i.e., on the object side or image side of the aperture 5, the incident height of light in the optical path conversion element 2 can be reduced, thereby reducing the radial dimension of the optical path conversion element 2. Furthermore, the aperture 5 effectively restricts the light beam, which is beneficial for reducing aberrations and improving image brightness and color uniformity. It also helps to shorten the distance from the aperture 5 to the image plane, further facilitating miniaturization design.

[0085] In some embodiments, the optical system 10 further satisfies: n > 1.8, where n is the refractive index of the optical path conversion element 2. For example, the refractive index n of the optical path conversion element 2 can be 1.85, 1.87, 1.9, etc.

[0086] If the above conditions are met, the optical path conversion element 2 has a high refractive index. For example, if the optical path conversion element 2 can use a glass material with a high refractive index, the air equivalent length of the optical path conversion element 2 can be shortened by the high refractive index of the optical path conversion element 2. This can suppress the height of the light rays incident on the optical path conversion element 2 by the front lens 1 while ensuring that the optical system 10 has a large field of view, which is beneficial to reducing the volume of the optical system 10.

[0087] It should be noted that the materials of the front lens 1, the optical path conversion element 2, and the rear mirror group 3 in this application are not limited to glass. Other materials, such as resin or silicone, can also be used. The specific application can be set according to the specific requirements, and no further restrictions are imposed here.

[0088] In some embodiments, the optical system 10 further satisfies: 6mm ≤ L ≤ 9mm, where L is the total optical length of the optical system 10. For example, L can be 6.5mm, 7mm, or 8mm, etc.

[0089] Thus, the overall size of the optical system 10 of this application meets the above-mentioned range, thereby enabling the optical system 10 of this application to have better imaging quality and better field of view while also maintaining a better size range, which is beneficial to maintaining the miniaturization of the optical system 10.

[0090] This application also provides an endoscope, including the optical system 10 and the endoscope tube in any of the above embodiments, wherein the optical system 10 is disposed inside the endoscope tube, and the endoscope tube provides an installation position and housing protection for the optical system 10.

[0091] See Figure 3 and Figure 4 As shown, Figure 3 This is a schematic diagram of the optical system 10 disposed inside the lens barrel in some embodiments of this application. Figure 4 This is a schematic diagram of the lens barrel structure in some embodiments of this application.

[0092] The lens barrel includes a first sleeve 61, which includes a first inner circumferential portion 611 and a second inner circumferential portion 612. A front lens 1 is installed in the first inner circumferential portion 611, and a light path conversion element 2 is installed in the second inner circumferential portion 612. The axial direction of the first inner circumferential portion 611 intersects with the axial direction of the second inner circumferential portion 612. Thus, the front lens 1 installed in the first inner circumferential portion 611 is tilted relative to the light path conversion element 2 installed in the second inner circumferential portion 612. In this way, the front lens 1 can receive ambient light incident at an oblique angle, and then change the propagation direction of the light through the light path conversion element 2, so that the light passing through the front lens 1 is deflected and enters the rear lens group 3.

[0093] In this embodiment, the oblique viewing angle, that is, the tilt angle of the front lens 1 relative to the optical path conversion element 2, can be achieved by setting the tilt angle of the first inner peripheral portion 611 and the second inner peripheral portion 612, or in other words, by setting a preset angle between the axial direction of the first inner peripheral portion 611 and the axial direction of the second inner peripheral portion 612, and the preset angle is the viewing angle of the optical system 10.

[0094] Thus, after the front lens 1 is installed in the first inner circumference 611 and the optical path conversion element 2 is installed in the second inner circumference 612, the front lens 1 is tilted relative to the optical path conversion element 2 at the preset angle, and the front lens 1 can receive the external ambient light that is tilted at the preset angle.

[0095] For example, a preset angle can be set to 70° to accommodate pyeloscopy in urology, or one of the preset angles between 30° and 45° to accommodate gastroscopy and colonoscopy, or even a large preset angle of 90° or higher to accommodate laparoscopic surgery. Specific angle settings can be configured according to actual needs, and no further restrictions are imposed here.

[0096] It should be noted that, as Figure 1 , Figure 3 and Figure 4 The axial direction of the first inner peripheral portion 611 is parallel to the axis C1 of the first inner peripheral portion 611, and the axial direction of the second inner peripheral portion 612 is parallel to the axis C2 of the second inner peripheral portion 612.

[0097] like Figure 3 In some embodiments, the lens barrel also includes a separator 8, which is disposed between the front lens 1 and the optical path conversion element 2 to maintain a preset interval between the front lens 1 and the optical path conversion element 2. The installation of the separator 8 is beneficial to improving the installation stability of the front lens 1 and the optical path conversion element 2, improving their installation accuracy, and reducing the risk of their position shifting due to environmental fluctuations.

[0098] In this embodiment, the isolator 8 is ring-shaped, so that the center of the ring does not obstruct the passage of light, and the isolator 8 can also serve to isolate the front lens 1 and the optical path conversion element 2.

[0099] In some embodiments, such as Figure 3 and Figure 4 As shown, the lens barrel also includes a second sleeve 62 and a third sleeve 63. The rear mirror assembly 3 is installed inside the second sleeve 62, and a sensor 4 is installed inside the third sleeve 63. The sensor 4 is used to receive light passing through the optical system and generate a digital image. Parts of the first sleeve 61 and the third sleeve 63 are sequentially fitted onto the outside of the second sleeve 62 along the optical axis of the rear mirror assembly 3.

[0100] During assembly, the third sleeve 63 can move along the optical axis of the rear mirror group 3. By adjusting the third sleeve 63 relative to the second sleeve 62, the distance between the sensor 4 inside the third sleeve 63 and the rear mirror group 3 inside the second sleeve 62 can be adjusted. This facilitates the alignment of the sensor 4 with the imaging position of the light rays passing through the rear mirror group 3, enabling the sensor 4 to acquire a clear image. Once the sensor 4 has achieved a clear image, the relative position between the third sleeve 63 and the second sleeve 62 will be fixed to ensure that the sensor 4 continues to acquire clear images in subsequent use of the optical system 10.

[0101] In this embodiment, sensor 4 can be an image sensor to convert the received optical image formed by optical system 10 into an electrical signal and finally form a digital image for doctors to observe and examine.

[0102] In this embodiment, the second sleeve 62 includes a third inner circumferential portion 621 and a fourth inner circumferential portion 622 arranged sequentially along the optical axis. The third inner circumferential portion 621 is used to accommodate the first lens 31, and the fourth inner circumferential portion 622 is used to accommodate the cemented lens assembly. The inner diameter of the third inner circumferential portion 621 is smaller than the inner diameter of the fourth inner circumferential portion 622. Thus, the end of the third inner circumferential portion 621 near the fourth inner circumferential portion 622 forms a stepped structure with the fourth inner circumferential portion 622. This stepped structure can limit the cemented lens assembly in the fourth inner circumferential portion 622, or in other words, the cemented lens assembly in the fourth inner circumferential portion 622 abuts against the end of the third inner circumferential portion 621 near the fourth inner circumferential portion 622. This helps to improve the installation stability of the cemented lens assembly.

[0103] The third inner circumference 621 has a protruding structure at one end away from the fourth inner circumference 622. The protruding structure protrudes in the direction of the optical axis and abuts against the first lens 31 inside the third inner circumference 621 to improve the installation stability of the first lens 31.

[0104] In some embodiments, the endoscope includes a protective lens 7 disposed within the third sleeve 63 and at one end of the sensor 4 near the rear end of the mirror assembly 3, in order to protect the photosensitive surface of the sensor 4.

[0105] The optical system 10 and endoscope of this application, through the arrangement of the front lens 1, the optical path conversion element 2, and the rear mirror group 3, and by limiting the relationship between the focal length of the front lens 1, the focal length of the rear mirror group 3, and the focal length of the optical system 10, reduce the axial and radial dimensions of the optical system 10, thereby improving the miniaturization capability of the optical system 10, and simultaneously improving the field of view and imaging effect of the optical system 10. Furthermore, by limiting the field of view, the outer diameter of the front lens 1, and the total optical length of the optical system 10, a balance is maintained between the field of view and the outer diameter of the front lens 1, and the total optical length is limited, allowing the optical system 10 to have a large field of view while also having a small radial dimension. The cemented arrangement of the mirror group further reduces the radial dimension of the optical system 10, facilitating miniaturization design. Finally, the optical power of the first lens 31, the second lens 321, and the third lens 322, as well as the concave and convex surface design of the incident and exit surfaces, improves the imaging quality of the optical system 10. Furthermore, this application sets the Abbe coefficients of the second lens 321 and the third lens 322, enabling the optical system 10 to have a good aberration correction effect. The optical path conversion element 2 is also provided with a high refractive index, thereby suppressing the light rays in the front lens 1 to a lower level, which is beneficial for reducing the size of the optical system 10. This application also improves the installation stability of the optical system 10 by providing the first sleeve 61, the second sleeve 62, and the third sleeve 63, and allows the third sleeve 63 to move relative to the second sleeve 62 along the optical axis of the rear lens group 3, facilitating adjustment so that the sensor 4 can acquire a clear image.

[0106] 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.

[0107] 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 system, characterized in that, The optical system includes a front lens and a rear lens group arranged sequentially from the object side to the image side; the optical system satisfies: 0.9<|f F / f|<1.1; 1.2<f R / f<1.7; 0.63<|f F / f R |<0.88; Wherein, the f F The focal length of the front lens is f. R f is the focal length of the rear mirror group, and f is the focal length of the optical system.

2. The optical system according to claim 1, characterized in that, The optical system also satisfies: FOV ≥ 120°; D1≤2.5； Wherein, FOV is the field of view of the optical system, and D1 is the outer diameter of the front lens.

3. The optical system according to claim 1, characterized in that, The front lens has negative optical power, and the light-emitting surface of the front lens is concave.

4. The optical system according to claim 1, characterized in that, The rear mirror group has positive optical power, and the rear mirror group includes a first lens and a cemented lens group arranged sequentially from the object side to the image side. The first lens has positive optical power, and the cemented lens group has positive optical power. The cemented lens group includes a second lens and a third lens cemented together with each other. The first lens has positive optical power, and the light-incident surface of the first lens is convex, and the light-exit surface is convex. The second lens has positive optical power, and the light-incident surface and the light-exit surface of the first lens are both convex. The third lens has negative optical power, and the light-incident surface of the third lens is concave, while the light-outceasing surface is convex.

5. The optical system according to claim 4, characterized in that, The optical system also satisfies: vd1 > 50; vd2 > vd1; Wherein, vd1 is the Abbe coefficient of the second lens, and vd2 is the Abbe coefficient of the third lens.

6. The optical system according to claim 1, characterized in that, The optical system further includes a light path conversion element and an aperture. The light path conversion element is disposed between the front lens and the rear lens group, and the light path conversion element is used to change the direction of light propagation, so that the light passing through the front lens is deflected and incident on the rear lens group. The aperture is located on the object side or image side of the optical path conversion element.

7. The optical system according to claim 6, characterized in that, The optical system also satisfies: n＞1.8； Wherein, n is the refractive index of the optical path conversion element.

8. The optical system according to claim 1, characterized in that, The optical system also satisfies: 6mm≤L≤9mm; Wherein, L is the total optical length of the optical system.

9. An endoscope, characterized in that, Includes the optical system and lens barrel according to any one of claims 1-8, wherein the optical system is disposed within the lens barrel; The lens barrel includes a first sleeve, which includes a first inner circumferential portion and a second inner circumferential portion. The front lens is installed in the first inner circumferential portion, and an optical path conversion element is installed in the second inner circumferential portion. The axial direction of the first inner circumferential portion intersects with the axial direction of the second inner circumferential portion.

10. The endoscope according to claim 9, characterized in that, The lens barrel also includes a second sleeve and a third sleeve; The rear mirror assembly is installed inside the second sleeve, and a sensor is installed inside the third sleeve. The sensor is used to receive light passing through the optical system and generate a digital image. Along the optical axis of the rear mirror assembly, portions of the first sleeve and the third sleeve are sequentially fitted over the second sleeve.

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