Endoscope light path amplifying structure, lens and endoscope

Abstract

The utility model discloses an endoscope light path amplifying structure, a lens and an endoscope, and belongs to the technical field of endoscopes, the lens comprises the light path structure, the endoscope comprises the lens, the light path structure comprises a first fixed lens group, a movable lens group and a second fixed lens group which are arranged in sequence, and the first fixed lens group, the movable lens group and the second fixed lens group are arranged in parallel. The first fixed lens group comprises a first lens and a second lens arranged on the image space side of the first lens, the movable lens group comprises a third lens, and the second fixed lens group comprises a fourth lens and a fifth lens arranged on the image space side of the fourth lens; the first lens is a plano-concave lens, the second lens is a meniscus lens, the third lens is a triplet lens, the fourth lens is a positive lens, the fifth lens is a negative lens, and the imaging quality of the optical path system can be effectively guaranteed by setting the lenses on the optical path structure into specific structures.

Description

Technical Field

[0001] The utility model relates to the technical field of endoscopes, in particular to an optical path structure of a magnifying endoscope, a lens and an endoscope. Background Art

[0002] An endoscope usually includes a tubular body with a lens provided at one end of the body. It is specifically used to enter the body through a natural channel or incision to observe the internal features of the human body.

[0003] Endoscopes are used more and more widely in the field of medical detection. The resolution of ordinary endoscopes can no longer meet the requirements of some clinical applications, which brings inconvenience to the detection and diagnosis of diseases. In order to improve the optical resolution of observation, magnifying endoscopes came into being. At present, the optical magnification methods of magnifying endoscopes are divided into two-speed magnification, multi-speed magnification, continuous magnification, etc. Among them, endoscopes with two-speed magnification have the characteristics of easy operation, fewer lenses, low requirements for the optical system, low cost and can meet the general detection and diagnosis needs.

[0004] The optical path structure of the endoscope has an important influence on the performance of the endoscope. For example, off-axis aberration is a series of aberrations derived from off-axis points due to the presence of spherical aberration and image curvature on the refractive sphere of the lens. When the optical system images an off-axis point, it does not have ideal imaging conditions, which will produce off-axis aberrations. Specifically, when a wide beam is imaged, coma, astigmatism and image curvature will be generated; when a narrow beam is imaged, coma is zero, but astigmatism and image curvature still exist. Therefore, in the optical design, measures need to be taken to correct and reduce these aberrations to improve the imaging quality of the system. To address this problem, the patent document with application number CN202222129602.X provides a new type of endoscope, which solves aberrations, chromatic aberrations, etc. through a specific lens structure to achieve the purpose of improving imaging quality.

[0005] Endoscopes are medical instruments widely used in the medical field. Further optimization of endoscopes will undoubtedly promote the development of the medical industry. Utility Model Content

[0006] In order to further optimize the endoscope, the present invention provides a magnifying endoscope optical path structure, lens and endoscope. This solution can effectively ensure the imaging quality of the optical path system by setting each lens in the optical path structure to a specific structure.

[0007] In response to the above problems, the present invention provides a magnifying endoscope optical path structure, lens, and endoscope that solve the problems through the following technical points: a magnifying endoscope optical path structure, from the object side to the image side, includes a first fixed lens group, a movable lens group, and a second fixed lens group arranged in sequence, the first fixed lens group includes a first lens and a second lens arranged on the image side of the first lens, the movable lens group includes a third lens, and the second fixed lens group includes a fourth lens and a fifth lens arranged on the image side of the fourth lens;

[0008] The first lens is a plano-concave lens, the second lens is a meniscus lens, the third lens is a triplet lens, the fourth lens is a positive lens, and the fifth lens is a negative lens.

[0009] In the above scheme, the first fixed mirror group serves as the front fixed group of the optical path structure, and the second fixed mirror group serves as the rear fixed group of the optical path structure. The lenses on the front and rear fixed groups are fixed on the optical path structure. The movable mirror group is a mirror group whose position in the optical path / optical axis can be adjusted during the use of the endoscope according to the specific magnification requirements of the endoscope.

[0010] This solution provides a specific optical path structure lens group layout. Specifically, for the first fixed lens group, a method including a front plano-concave lens and a rear meniscus lens is adopted, which can enable the front fixed group to better correct and reduce off-axis aberrations, such as astigmatism and field curvature; for the movable lens group, the third lens, which is a triplet lens, can effectively reduce the chromatic aberration (spherical axial chromatic aberration) generated by the optical path system. At the same time, for the installation of the movable lens group on the optical path structure, since the third lens is an integrated structure including three lenses, such a movable lens group structure has the characteristics of easy assembly on the optical path structure and low difficulty in position adjustment; for the second fixed lens group, a method including a positive lens for the front lens and a negative lens for the rear lens is adopted, which can enable the rear fixed group to have the characteristics of reducing spherical aberration, coma and chromatic aberration. In summary, this solution provides a technical solution that can effectively ensure the imaging quality of the optical path system.

[0011] As a further technical solution for the optical path structure of the magnifying endoscope:

[0012] The focal length f1 of the first lens satisfies: 1.3mm≥f1≥0.95mm, and the focal length f2 of the second lens satisfies: 8mm≥f2≥6mm;

[0013] f1 and f2 satisfy the following relationship: 0.8≤|f1*f2 / (f1+f2)|≤1.2.

[0014] The above scheme provides a specific implementation method for the first fixed lens group. With this setting, while satisfying the requirements of correcting and reducing off-axis aberrations, it also has the characteristics of being beneficial to the rationality of the focal length distribution of the front fixed group, making the off-axis field of view aberrations smaller, and being beneficial to the design of reducing the length of the optical path system.

[0015] Furthermore, to better correct the chromatic aberration of the front fixed group within an optimal range to achieve excellent orientation quality, the first lens and the second lens are set to satisfy the following relationship in the optical path system:

[0016] 0.8*|h1 2 / (V1*f1)|≤|h2 2 / (V2*f2)|≤1.2*|h1 2 / (V1*f1)|, wherein h1 and h2 are the marginal ray heights of the first lens and the second lens respectively, and V1 and V2 are the Abbe numbers of the first lens and the second lens respectively.

[0017] In the third lens, the lens in the middle is a positive lens, and the lenses on both sides are negative lenses. The focal length f3 of the third lens satisfies: 3.2 mm ≥ f3 ≥ 2.5 mm, the refractive index of the lens in the middle is greater than 1.8, and the Abbe number is less than 48, and the refractive index of the lenses on both sides is less than 1.7, and the Abbe number is greater than 50.

[0018] The above setting of the third lens can greatly control the chromatic aberration produced by the system.

[0019] The parameters of the third lens satisfy: 0.8≤1 / |f31*V31+f32*V32+f33*V33|≤1.5;

[0020] Wherein, f31 is the focal length of the object-side lens of the third lens, V31 is the Abbe number of the object-side lens of the third lens, f32 is the focal length of the intermediate lens of the third lens, V32 is the Abbe number of the intermediate lens of the third lens, f33 is the focal length of the image-side lens of the third lens, and V32 is the Abbe number of the image-side lens of the third lens.

[0021] The above further configuration of the third lens element can improve the correction capability of the movable lens group for both axial and vertical chromatic aberrations, so that both axial and vertical chromatic aberrations are within an excellent range.

[0022] The focal length f4 of the fourth lens satisfies: 3.5 mm ≥ f4 ≥ 2.6 mm, and the focal length f5 of the fifth lens satisfies: 2.2 mm ≥ f5 ≥ 1.2 mm;

[0023] The Abbe number V4 of the fourth lens satisfies: V4>60, and the parameters of the second fixed lens group satisfy: 1 / |(f4+f5)*(V4+V5)*0.5|≤1.2;

[0024] The V5 is the Abbe number of the fifth lens.

[0025] The above setting of the second fixed lens group can ensure that the spherical aberration, coma and chromatic aberration of the second fixed lens group are within an excellent numerical range.

[0026] It also includes a filter arranged on the optical path of the optical path structure;

[0027] The filter is provided with a filter film or a spectrum transmission film, and the filter film is used for filtering the near infrared spectrum.

[0028] In the above scheme, the filter film is used to filter the near-infrared spectrum to avoid the impact of the near-infrared spectrum on imaging quality, and the spectral transparent film is used to optimize the effect under special spectral imaging, such as the use of excitation light imaging on endoscopes.

[0029] Preferably, for the first fixed lens group, movable lens group and second fixed lens group provided above, in order to facilitate the installation of the filter and ensure the effect of the filter, the preferred arrangement is to arrange the filter between the first lens and the second lens.

[0030] In a preferred embodiment, the movable mirror group realizes switching between the magnifying end and the conventional end of the endoscope by moving, specifically: when the movable mirror group is close to the first fixed mirror group, it is in the magnifying end mode, and the magnifying end field of view angle is greater than 75°; when the movable mirror group is close to the second fixed mirror group, it is in the conventional end mode, and the conventional end field of view angle is greater than 140°. Technicians in this field can adjust the endoscope to two levels of magnification according to observation needs. Under such application, the endoscope optical path system has the characteristics of simple system structure, small size, low requirements for the optical system, and low cost of use.

[0031] Regarding the resolution curve of the optical path system formed by the above two-step magnification adjustment (including other forms of discontinuous multi-step magnification adjustment), for example, the peak resolution is present at the magnified end, and the peak resolution at the magnified end is several times the peak resolution at the conventional end. Due to the discontinuity of the steps, a resolution depression will occur at a certain distance (object distance) range (the curve of the resolution changing with the object distance on the resolution curve is not smooth, and a concave resolution curve segment appears). As a result, the visual clarity at this distance is lower than expected, affecting the effect of medical examination. To address this problem, an aperture diaphragm is also provided on the optical path structure, and the aperture diaphragm can adjust the aperture size of the optical path.

[0032] The aperture stop is any one of the following structures:

[0033] The aperture stop includes a glass substrate and a plurality of coatings provided on the glass substrate. The coatings are electrochromic materials and are in a ring structure. When the coatings are multiple layers, the coatings are arranged in the form of concentric circles along the radial direction of the glass substrate.

[0034] The aperture diaphragm is flippably arranged on the optical path structure, and the aperture diaphragm can be flipped to have different postures on the optical path;

[0035] The aperture stop is movably arranged on the optical path structure, and the aperture stop can be moved to have different positions on the optical path.

[0036] The basic principle of the above scheme is: using the aperture diaphragm to adjust the aperture size of the light path, thereby adjusting the depth of field of the optical system. When in use, for the resolution concave interval, by changing the object distance and the depth of field under the magnification gear, the purpose of improving observation clarity is achieved. Specifically, for the technical solution using electrochromic material as the coating, when the coating is energized, the coating becomes black and the light transmittance decreases. The light-transmitting part on the aperture diaphragm is the circle inside the coating, resulting in a smaller system aperture and a larger depth of field. In this case, the peak resolution of the magnification end decreases, but the resolution of the concave interval on the resolution curve will be improved. In this state, if the peak resolution of the magnification end needs to be restored, the coating is powered off, and the light-transmitting part on the aperture diaphragm includes the circle inside the coating and the coverage area of ​​the coating, so that the aperture can be increased, so that the peak resolution of the magnification end is improved. In a specific implementation, the glass substrate can be made of high-transmittance glass. When the coating is multi-layered, the coating forms multiple rings on the glass substrate. The rings are generally referred to as ring glass. By controlling the power state of each ring glass, the current can be used to excite the chemical substances or conductive films in the ring glass, resulting in a decrease in the transmittance of the ring glass. Since each ring glass is insulated from each other, the transmittance of each ring glass can be individually controlled. This solution can form multiple aperture sizes, and while adjusting the depth of field of the magnifying endoscope, it can also achieve fine-tuning of the depth of field to well match the peak resolution in each state. Preferably, due to the volume of the endoscope system and considering the optical physics diffraction limit, the difference between the inner and outer diameters of each ring structure is greater than 0.1mm, and the number of ring structures is ≥8 or ≥3. The outer contour of the concentric rings is a circle, which is the preferred embodiment for general optical paths. When the outer contour is adjusted to an equilateral polygon, it should also be considered an equivalent technical solution. For the polygonal outer contour, to ensure imaging quality, the number of sides of the polygon is preferably ≥5.

[0037] The above optical path structure design using the coating has little impact on the size of the optical path structure, and is easy to use and has low installation cost.

[0038] The above aperture diaphragm posture adjustment by flipping and aperture diaphragm position adjustment by movement are respectively as follows: for the flipping, the aperture diaphragm can be considered to be flippable as a baffle for the light path. For example, it is set to also include a system diaphragm, and the aperture of the aperture diaphragm is smaller than the aperture of the current system diaphragm. When the magnification gear is at the magnification end, the aperture diaphragm is flipped to act on the current light path, resulting in a smaller aperture at the magnification end and an increased depth of field. When the magnification gear is at the normal end, the aperture diaphragm is flipped to act on the current light path, resulting in a smaller aperture at the magnification end and an increased depth of field. After the depth of field is increased, although the peak resolution decreases, the resolution of the concave portion on the resolution curve is reduced. The curve segment will be improved. When the peak resolution needs to be restored, the aperture diaphragm can be flipped to eliminate its influence on the optical path. As for the movement, that is, by changing the position of the aperture diaphragm, the shading effect of the aperture diaphragms at different positions on the light can be used to change the area of ​​the actual light path. For example, when the magnifying endoscope switches gears, a cam is used to move the movable lens group. Under the above optical path structure design, in order to improve the imaging quality and simplify the system structure, the aperture diaphragm is fixed to the front end of the movable lens group. At this time, the movable lens group moves a certain distance d along the optical axis, and the diaphragm moves d at the same time. At this time, the total length of the system remains unchanged, but the virtual image of the diaphragm changes, thereby changing the depth of field and improving the resolution of the recessed area.

[0039] At the same time, the present solution also relates to a lens including the optical path structure as described in any one of the above items. It is easy to understand that the lens adopts the optical path structure, and the optical path structure is a component part of the lens.

[0040] At the same time, the present solution also relates to an endoscope including the lens. It is easy to understand that the endoscope adopts the lens, and the lens is a component part of the endoscope.

[0041] The utility model has the following beneficial effects:

[0042] This solution provides a specific optical path structure lens group layout. Specifically, for the first fixed lens group, a method including a front plano-concave lens and a rear meniscus lens is adopted, which can enable the front fixed group to better correct and reduce off-axis aberrations, such as astigmatism and field curvature; for the movable lens group, the third lens, which is a triplet lens, can effectively reduce the chromatic aberration (spherical axial chromatic aberration) generated by the optical path system. At the same time, for the installation of the movable lens group on the optical path structure, since the third lens is an integrated structure including three lenses, such a movable lens group structure has the characteristics of easy assembly on the optical path structure and low difficulty in position adjustment; for the second fixed lens group, a method including a positive lens for the front lens and a negative lens for the rear lens is adopted, which can enable the rear fixed group to have the characteristics of reducing spherical aberration, coma and chromatic aberration. In summary, this solution provides a technical solution that can effectively ensure the imaging quality of the optical path system. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a structural schematic diagram of a specific embodiment of the optical path structure of the magnifying endoscope described in this solution;

[0044] Figure 2 for Figure 1 Surface numbered schematic diagram of the structure shown;

[0045] Figure 3 Schematic diagram of field curvature and astigmatism in the normal end state in Example 9;

[0046] Figure 4 This is a schematic diagram showing distortion in a normal end state in Example 9;

[0047] Figure 5 Schematic diagram of field curvature and astigmatism in the magnified end state in Example 9;

[0048] Figure 6 This is a schematic diagram showing distortion in the amplified end state in Example 9;

[0049] Figure 7 Schematic diagram of a resolution curve when the resolution curve is adjusted without using an aperture stop in Example 6;

[0050] Figure 8 Schematic diagram of a resolution curve when adjusting the resolution curve using an aperture stop in Example 6. Reference numerals in the figure are: 1, first lens; 2, filter; 3, second lens; 4, aperture stop; 5, third lens; 6, fourth lens; 7, fifth lens. DETAILED DESCRIPTION

[0051] The present invention will be further described in detail below with reference to the following embodiments, but the present invention is not limited to the following embodiments:

[0052] Example 1:

[0053] like Figures 1 to 8 As shown, a magnifying endoscope optical path structure, from the object side to the image side, includes a first fixed lens group, a movable lens group, and a second fixed lens group arranged in sequence, wherein the first fixed lens group includes a first lens 1 and a second lens 3 arranged on the image side of the first lens 1, the movable lens group includes a third lens 5, and the second fixed lens group includes a fourth lens 6 and a fifth lens 7 arranged on the image side of the fourth lens 6;

[0054] The first lens 1 is a plano-concave lens, the second lens 3 is a meniscus lens, the third lens 5 is a triplet lens, the fourth lens 6 is a positive lens, and the fifth lens 7 is a negative lens.

[0055] In the above scheme, the first fixed mirror group serves as the front fixed group of the optical path structure, and the second fixed mirror group serves as the rear fixed group of the optical path structure. The lenses on the front and rear fixed groups are all fixed on the optical path structure. The movable mirror group is a mirror group whose position in the optical path can be adjusted during the use of the endoscope according to the specific magnification requirements of the endoscope.

[0056] This solution provides a specific optical path structure lens group layout. Specifically, for the first fixed lens group, a method including a front plano-concave lens and a rear meniscus lens is adopted, which can enable the front fixed group to better correct and reduce off-axis aberrations, such as astigmatism and field curvature; for the movable lens group, the third lens 5, which is a triplet lens, can effectively reduce the chromatic aberration (spherical axial chromatic aberration) generated by the optical path system. At the same time, for the installation of the movable lens group on the optical path structure, since the third lens 5 is an integrated structure including three lenses, such a movable lens group structure has the characteristics of easy assembly on the optical path structure and low difficulty in position adjustment; for the second fixed lens group, a method including a positive lens for the front lens and a negative lens for the rear lens is adopted, which can enable the rear fixed group to have the characteristics of reducing spherical aberration, coma and chromatic aberration. In summary, this solution provides a technical solution that can effectively ensure the imaging quality of the optical path system.

[0057] Example 2:

[0058] This embodiment is further refined based on the embodiment 1:

[0059] The focal length f1 of the first lens 1 satisfies: 1.3 mm ≥ f1 ≥ 0.95 mm, and the focal length f2 of the second lens 3 satisfies: 8 mm ≥ f2 ≥ 6 mm;

[0060] f1 and f2 satisfy the following relationship: 0.8≤|f1*f2 / (f1+f2)|≤1.2.

[0061] The above scheme provides a specific implementation method for the first fixed lens group. With this setting, while satisfying the requirements of correcting and reducing off-axis aberrations, it also has the characteristics of being beneficial to the rationality of the focal length distribution of the front fixed group, making the off-axis field of view aberrations smaller, and being beneficial to the design of reducing the length of the optical path system.

[0062] Furthermore, in order to better correct the chromatic aberration of the front fixed group to a preferred range to obtain excellent orientation quality, the first lens 1 and the second lens 3 are arranged in the optical path system to satisfy the following relationship:

[0063] 0.8*|h1 2 / (V1*f1)|≤|h2 2 / (V2*f2)|≤1.2*|h1 2 / (V1*f1)|, wherein h1 and h2 are the marginal ray heights of the first lens 1 and the second lens 3, respectively, and V1 and V2 are the Abbe numbers of the first lens 1 and the second lens 3, respectively.

[0064] Example 3:

[0065] This embodiment is further refined based on the embodiment 1:

[0066] In the third lens 5, the lens in the middle is a positive lens, and the lenses on both sides are negative lenses. The focal length f3 of the third lens 5 satisfies: 3.2mm≥f3≥2.5mm, the refractive index of the lens in the middle is greater than 1.8, and the Abbe number is less than 48, and the refractive index of the lenses on both sides is less than 1.7, and the Abbe number is greater than 50.

[0067] The above setting of the third lens 5 can greatly control the chromatic aberration generated by the system.

[0068] The parameters of the third lens 5 satisfy: 0.8≤1 / |f31*V31+f32*V32+f33*V33|≤1.5;

[0069] Among them, f31 is the focal length of the object side lens of the third lens 5, V31 is the Abbe number of the object side lens of the third lens 5, f32 is the focal length of the intermediate lens of the third lens 5, V32 is the Abbe number of the intermediate lens of the third lens 5, f33 is the focal length of the image side lens of the third lens 5, and V32 is the Abbe number of the image side lens of the third lens 5.

[0070] The above further setting of the third lens 5 can make the movable lens group have better axial and vertical chromatic aberration correction capabilities, so that the axial and vertical chromatic aberrations are both within the excellent range.

[0071] Example 4:

[0072] This embodiment is further refined based on the embodiment 1:

[0073] The focal length f4 of the fourth lens 6 satisfies: 3.5 mm ≥ f4 ≥ 2.6 mm, and the focal length f5 of the fifth lens 7 satisfies: 2.2 mm ≥ f5 ≥ 1.2 mm;

[0074] The Abbe number V4 of the fourth lens 6 satisfies: V4>60, and the parameters of the second fixed lens group satisfy: 1 / |(f4+f5)*(V4+V5)*0.5|≤1.2;

[0075] V5 is the Abbe number of the fifth lens element 7 .

[0076] The above setting of the second fixed lens group can ensure that the spherical aberration, coma and chromatic aberration of the second fixed lens group are within an excellent numerical range.

[0077] Example 5:

[0078] This embodiment is further refined based on the embodiment 1:

[0079] It also includes a filter 2 arranged on the optical path of the optical path structure;

[0080] The filter 2 is provided with a filter film or a spectrum transmission film, and the filter film is used to filter the near-infrared spectrum.

[0081] In the above scheme, the filter film is used to filter the near-infrared spectrum to avoid the impact of the near-infrared spectrum on imaging quality, and the spectral transparent film is used to optimize the effect under special spectral imaging, such as the use of excitation light imaging on endoscopes.

[0082] Preferably, for the first fixed lens group, movable lens group and second fixed lens group provided above, in order to facilitate the installation of the filter 2 and ensure the effect of the filter 2, the preferred arrangement is to arrange the filter 2 between the first lens 1 and the second lens 3.

[0083] In a preferred embodiment, the movable mirror group realizes switching between the magnifying end and the conventional end of the endoscope by moving, specifically: when the movable mirror group is close to the first fixed mirror group, it is in the magnifying end mode, and the magnifying end field of view angle is greater than 75°; when the movable mirror group is close to the second fixed mirror group, it is in the conventional end mode, and the conventional end field of view angle is greater than 140°. Technicians in this field can adjust the endoscope to two levels of magnification according to observation needs. Under such application, the endoscope optical path system has the characteristics of simple system structure, small size, low requirements for the optical system, and low cost of use.

[0084] Example 6:

[0085] This embodiment is further refined based on the embodiment 1:

[0086] Regarding the resolution curve of the optical path system formed by the above two-step magnification adjustment (including other forms of discontinuous multi-step magnification adjustment), for example, the peak resolution is present at the magnified end, and the peak resolution at the magnified end is several times that of the peak resolution at the conventional end. Due to the discontinuity of the steps, a resolution depression will occur at a certain distance (object distance) range (the curve of the resolution changing with the object distance on the resolution curve is not smooth, and a concave resolution curve segment appears). As a result, the visual clarity at this distance is lower than expected, affecting the effect of medical examination. To address this problem, an aperture stop 4 is also provided on the optical path structure, and the aperture stop 4 can adjust the aperture size of the optical path.

[0087] The aperture stop 4 is any one of the following structures:

[0088] The aperture stop 4 includes a glass substrate and a plurality of coating layers provided on the glass substrate. The coating layers are electrochromic materials and are in a ring structure. When the coating layers are multiple layers, the coating layers are arranged in the form of concentric circles along the radial direction of the glass substrate.

[0089] The aperture stop 4 can be flipped and arranged on the optical path structure, and the aperture stop 4 can be flipped to have different postures on the optical path;

[0090] The aperture stop 4 is movably arranged on the optical path structure, and the aperture stop 4 can be moved to have different positions on the optical path.

[0091] The basic principle of the above scheme is: the aperture size of the light path is adjusted by using the aperture stop 4, thereby adjusting the depth of field of the optical system. When in use, for the resolution depression interval, the object distance and the depth of field under the magnification gear are changed to achieve the purpose of improving observation clarity. Specifically, for the technical scheme using electrochromic material as the coating, when the coating is energized, the coating becomes black and the light transmittance decreases. The light-transmitting part on the aperture stop 4 is the circle inside the coating, resulting in a smaller system aperture and a larger depth of field. In this case, the peak resolution of the amplification end decreases, but the resolution of the depression interval on the resolution curve will be improved. In this state, if the peak resolution of the amplification end needs to be restored, the coating is powered off, and the light-transmitting part on the aperture stop 4 includes the circle inside the coating and the coverage area of ​​the coating, so that the aperture can be increased, so that the peak resolution of the amplification end is improved. In a specific implementation, the glass substrate can be made of high-transmittance glass. When the coating is multi-layered, the coating forms multiple rings on the glass substrate. The rings are generally referred to as ring glass. By controlling the power state of each ring glass, the current can be used to excite the chemical substances or conductive films in the ring glass, resulting in a decrease in the transmittance of the ring glass. Since each ring glass is insulated from each other, the transmittance of each ring glass can be individually controlled. This solution can form multiple aperture sizes, and while adjusting the depth of field of the magnifying endoscope, it can also achieve fine-tuning of the depth of field to well match the peak resolution in each state. Preferably, due to the volume of the endoscope system and considering the optical physics diffraction limit, the difference between the inner and outer diameters of each ring structure is greater than 0.1mm, and the number of ring structures is ≥8 or ≥3. The outer contour of the concentric rings is a circle, which is the preferred embodiment for general optical paths. When the outer contour is adjusted to an equilateral polygon, it should also be considered an equivalent technical solution. For the polygonal outer contour, to ensure imaging quality, the number of sides of the polygon is preferably ≥5.

[0092] The above optical path structure design using the coating has little impact on the size of the optical path structure, and is easy to use and has low installation cost.

[0093] The above-mentioned adjustment of the posture of the aperture diaphragm 4 by flipping and the adjustment of the position of the aperture diaphragm 4 by movement are respectively as follows: for the flipping, it can be considered that the aperture diaphragm 4 can be flipped to serve as a baffle of the light path. For example, it is set to also include a system diaphragm, and the aperture of the aperture diaphragm 4 is smaller than the aperture of the current system diaphragm. When the magnification gear is at the magnification end, the aperture diaphragm 4 is flipped to act on the current light path, resulting in a smaller aperture at the magnification end and an increased depth of field. When the magnification gear is at the normal end, the aperture diaphragm 4 is flipped to act on the current light path, resulting in a smaller aperture at the magnification end and an increased depth of field. After the depth of field is increased, although the peak resolution decreases, the resolution curve is improved. The resolution curve segment of the depression will be improved. When the peak resolution needs to be restored, the aperture diaphragm 4 can be flipped to eliminate its influence on the optical path. As for the movement, that is, by changing the position of the aperture diaphragm 4 and utilizing the light shielding effect of the aperture diaphragm 4 at different positions, the area of ​​the actual light path is changed. For example, when the magnifying endoscope switches gears, a cam is used to move the movable lens group. Under the above optical path structure design, in order to facilitate imaging quality, the aperture diaphragm 4 is fixed to the front end of the movable lens group. At this time, the movable lens group moves a certain distance d along the optical axis, and the diaphragm moves d at the same time. At this time, the total length of the system remains unchanged, but the virtual image of the diaphragm changes, thereby changing the depth of field and improving the resolution of the depression.

[0094] In a specific embodiment, when the aperture stop 4 is not used to adjust the resolution curve, the resolution curve of this embodiment is as follows: Figure 7 As shown, Figure 7 The horizontal axis represents the object distance in mm, and the vertical axis represents the object-space resolution in line pairs per millimeter (lp / mm). The curve with a higher peak on the left is the resolution curve at the magnified end, and the curve with a lower peak on the right is the resolution curve at the conventional end. It can be clearly seen that there is a resolution depression between the conventional end and the magnified end. This depression causes the doctor to observe reduced clarity within the depression range when performing endoscopic examinations.

[0095] When the coating is used for depth of field processing, the resolution curve obtained is as follows Figure 8 As shown, combined Figure 8 It can be concluded that by intervening in the depth of field, a smooth resolution curve can be obtained, which effectively solves the problem of periodic clarity reduction during the observation process caused by resolution depression.

[0096] Example 7:

[0097] Based on Example 1, this embodiment provides a lens including the optical path structure described above. It is easy to understand that the lens adopts the optical path structure, and the optical path structure is a component part of the lens.

[0098] Example 8:

[0099] This embodiment provides an endoscope including the lens on the basis of the embodiment 1. It is easy to understand that the endoscope adopts the lens, and the lens is a component part of the endoscope.

[0100] Example 9:

[0101] This embodiment provides a specific implementation of an optical path structure. The system parameters of the optical path structure are shown in the following table:

[0102] SURFACE Radius Thickness 1 Infinity 0.32 2 1 0.526026813 3 Infinity 0.3 4 Infinity 0.33271894 5 -2.945497509 1.105170274 6 -2.505588986 1.287034861 7 Infinity 0.012 8 1.129969413 0.5 9 -1.397559279 0.235236372 10 0.955481862 0.514982843 11 -1.643426405 0.524043788 12 1.400374981 0.6 13 16.90646828 0.340154734 14 -1.657889892 1.512446916 15 21.5542497 0.305146471 16 Infinity 0.4 17 Infinity 0.045

[0103] The surface serial number of the optical path structure is as follows Figure 2 As shown in the figure, the embodiment is applied to a two-stage magnification endoscope having a magnifying end and a conventional end. The field curvature, astigmatism and distortion of the conventional end are as follows: Figure 3 and Figure 4 As shown, the field curvature, astigmatism and distortion at the amplified end are as follows Figure 5 and Figure 6 The optical path structure provided by this embodiment has the characteristics of good chromatic aberration and excellent imaging quality, as well as a wide field of view and high resolution.

[0104] The above content is a further detailed description of the present invention in conjunction with specific preferred embodiments, and the specific embodiments of the present invention are not limited to these descriptions. For those skilled in the art of the present invention, other embodiments that do not depart from the technical solution of the present invention should be included in the scope of protection of the present invention.

Claims

1. A magnifying endoscope optical path structure, from the object side to the image side, comprising a first fixed lens group, a movable lens group, and a second fixed lens group arranged in sequence, characterized in that: The first fixed lens group includes a first lens (1) and a second lens (3) arranged on the image side of the first lens (1), the movable lens group includes a third lens (5), and the second fixed lens group includes a fourth lens (6) and a fifth lens (7) arranged on the image side of the fourth lens (6); The first lens (1) is a plano-concave lens, the second lens (3) is a meniscus lens, the third lens (5) is a triplet lens, the fourth lens (6) is a positive lens, and the fifth lens (7) is a negative lens.

2. The optical path structure of a magnifying endoscope according to claim 1, characterized in that: The focal length f1 of the first lens (1) satisfies: 1.3 mm ≥ f1 ≥ 0.95 mm, and the focal length f2 of the second lens (3) satisfies: 8 mm ≥ f2 ≥ 6 mm; f1 and f2 satisfy the following relationship: 0.8≤|f1*f2 / (f1+f2)|≤1.

2.

3. The optical path structure of a magnifying endoscope according to claim 1, characterized in that: In the third lens (5), the lens in the middle is a positive lens, and the lenses on both sides are negative lenses. The focal length f3 of the third lens (5) satisfies: 3.2mm≥f3≥2.5mm, the refractive index of the lens in the middle is greater than 1.8, and the Abbe number is less than 48, and the refractive index of the lenses on both sides is less than 1.7, and the Abbe number is greater than 50.

4. The optical path structure of a magnifying endoscope according to claim 3, characterized in that: The parameters of the third lens (5) satisfy: 0.8≤1 / |f31*V31+f32*V32+f33*V33|≤1.5; Wherein, f31 is the focal length of the object side lens of the third lens (5), V31 is the Abbe number of the object side lens of the third lens (5), f32 is the focal length of the intermediate lens of the third lens (5), V32 is the Abbe number of the intermediate lens of the third lens (5), f33 is the focal length of the image side lens of the third lens (5), and V32 is the Abbe number of the image side lens of the third lens (5).

5. The optical path structure of a magnifying endoscope according to claim 1, characterized in that: The focal length f4 of the fourth lens (6) satisfies: 3.5 mm ≥ f4 ≥ 2.6 mm, and the focal length f5 of the fifth lens (7) satisfies: 2.2 mm ≥ f5 ≥ 1.2 mm.

6. The optical path structure of a magnifying endoscope according to claim 5, characterized in that: The Abbe number V4 of the fourth lens (6) satisfies: V4>60, and the parameters of the second fixed lens group satisfy: 1 / |(f4+f5)*(V4+V5)*0.5|≤1.2; The V5 is the Abbe number of the fifth lens (7).

7. The optical path structure of a magnifying endoscope according to any one of claims 1 to 6, characterized in that: It also includes a filter (2) arranged on the optical path of the optical path structure; The filter (2) is provided with a filter film or a spectrum transmission film, and the filter film is used for filtering the near-infrared spectrum.

8. The optical path structure of a magnifying endoscope according to claim 1, characterized in that: It also includes an aperture stop (4) arranged on the optical path structure, and the aperture stop (4) can adjust the aperture size of the optical path; The aperture stop (4) is any one of the following structures: The aperture stop (4) includes a glass substrate and a plurality of coating layers arranged on the glass substrate, wherein the coating layers are electrochromic materials and are in a circular ring structure. When the coating layers are multiple layers, the coating layers are arranged in the form of concentric circles along the radial direction of the glass substrate. The aperture diaphragm (4) is flippably arranged on the optical path structure, and the aperture diaphragm (4) can be flipped to have different postures on the optical path; The aperture stop (4) is movably arranged on the optical path structure, and the aperture stop (4) can be moved to have different positions on the optical path.

9. A lens, characterized in that: The optical path structure comprises any one of claims 1 to 8.

10. An endoscope, characterized in that: Including the lens described in claim 9.

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