Optical lens, camera module, endoscope and endoscope system

Abstract

The application provides an optical lens, a camera module, an endoscope and an endoscope system. The optical lens comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens arranged from an object side to an image side; the first lens has a negative focal power, the second lens has a negative focal power, the third lens has a positive focal power, and the fourth lens has a positive focal power; the third lens can move along the optical axis of the optical lens to focus the optical lens between a far focus and a near focus; the focal length f4 of the fourth lens of the optical lens and the focal length f2 of the second lens satisfy the relationship: -0.5 < f4 / f2 < -0.1. The optical lens achieves the purposes of large field of view, high image quality and miniaturization in the range of 2mm-100mm depth of field.

Description

[0001] This application is a divisional application of the invention patent application filed on August 2, 2024, with application number 202411061145.2 and invention title "Optical Lens, Camera Module, Endoscope and Endoscope System". Technical Field

[0002] This application relates to the field of optical imaging technology, and in particular to an optical lens, a camera module, an endoscope, and an endoscope system. Background Technology

[0003] An electronic endoscope is an instrument that can be inserted into the human body, allowing doctors to directly observe the tissue morphology and lesions of the body cavities and internal organs, and to make accurate diagnoses of diseases. Currently, electronic endoscopes are widely used in various fields of clinical medicine, and play an irreplaceable role, especially in the diagnosis of intrauterine diseases.

[0004] Camera modules, such as endoscope objectives, are typically used in conjunction with endoscopes to transmit images detected by the endoscope to a detector for better observation. They are commonly used in modern minimally invasive surgery, as well as in gastrointestinal examinations and treatments.

[0005] For precise diagnosis of lesions, endoscopes are desired to have high resolution, which helps doctors better identify lesions and improve diagnostic efficiency. At the same time, endoscopes are also desired to be small in size, meaning that the diameter of the endoscope objective lens should be small, which has a significant advantage in the field of minimally invasive diagnosis without anesthesia. Developing an optical lens with a wide field of view, high image quality, and miniaturization has become an important research topic in the industry. Summary of the Invention

[0006] Embodiments of this application provide an optical lens, camera module, endoscope, and endoscope system with a wide field of view, high image quality, and miniaturization.

[0007] In a first aspect, embodiments of this application provide an optical lens. The optical lens includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens arranged from the object side to the image side; the first lens has negative optical power, the second lens has negative optical power, the third lens has positive optical power, and the fourth lens has positive optical power; the third lens is movable along the optical axis of the optical lens to allow the optical lens to focus between a telephoto and a near-focal point; the focal length f4 of the fourth lens and the focal length f2 of the second lens satisfy the relationship: -0.5. <f4 / f2<-0.1。

[0008] The beneficial effects of the optical lens provided in this application embodiment are as follows: By rationally allocating the optical power of the optical lens, with both the first and second lenses having negative optical power, when light passes through the various lens groups of the optical lens, the light first diverges twice and then converges twice. This makes the light transition smoother, which not only reduces aberrations and improves the field of view and resolution, thereby improving image quality, but also helps to reduce the aperture of the optical lens. In addition, when the optical lens satisfies the above relationship, not only are the aberrations of the optical lens well corrected, but it also helps to reduce the overall optical length of the optical lens, thereby enabling the optical lens to achieve the goals of a large field of view, high image quality, and miniaturization within the depth of field.

[0009] In some embodiments, the fifth lens and the sixth lens form a cemented lens.

[0010] The above settings not only make the light pass through the optical lens more smoothly and reduce tolerance sensitivity, thereby further improving the image quality, but also facilitate the assembly of the optical lens.

[0011] In some embodiments, the laminated lens has positive power.

[0012] The above settings enable the cemented lens to effectively balance the first and second lenses, resulting in a smoother light transition. This not only further reduces aberrations but also lowers tolerance sensitivity, thereby further improving image quality.

[0013] In some embodiments, the combined focal length fm of the cemented lens and the focal length f4 of the fourth lens satisfy the following relationship: 0 <f4 / fm<0.5。

[0014] By making appropriate choices, when the optical lens satisfies the above relationship, it is not only beneficial to correct the aberrations of the optical lens and improve the image quality, but also to shorten the overall length of the optical lens.

[0015] In some embodiments, the combined focal length fm of the cemented lens and the effective focal length f of the optical lens at the telephoto position satisfy the following relationship: 2 <fm / f<50。

[0016] By making appropriate choices, when the optical lens satisfies the above relationship, not only is the image quality further improved, but the length of the optical lens is also reduced.

[0017] In some embodiments, the focal length f1 of the first lens and the focal length f2 of the second lens of the optical lens satisfy the relationship: 0.1 <f2 / f1<0.4。

[0018] By making appropriate choices, when the optical lens satisfies the above relationship, not only is the imaging quality of the optical lens further improved, but it is also beneficial to reduce the diameter of the optical lens.

[0019] In some embodiments, the radius of curvature R1 of the object side of the second lens near the object side and the radius of curvature R2 of the image side near the image side satisfy the relationship: -1<(R1-R2) / (R1+R2)<3.

[0020] By making reasonable selections so that the optical lens satisfies the above relationship, not only can the size of the second lens in the direction perpendicular to the optical axis be effectively controlled, thereby shortening the size of the optical lens in the direction perpendicular to the optical axis, but also the thickness of the second lens will not be too thin, making it easy to process.

[0021] In some embodiments, the focal length f3 of the third lens and the effective focal length f of the optical lens at the telephoto position satisfy the following relationship: 2 <f3 / f<8。

[0022] By making appropriate choices, when the optical lens satisfies the above relationship, the aberrations of the third lens and the other lenses cancel each other out, thus improving the image quality. At the same time, it is also beneficial to shorten the length of the optical lens, thereby realizing the miniaturization design of the optical lens.

[0023] In some embodiments, the optical lens further includes an aperture stop located between the third lens and the fourth lens.

[0024] The above settings further make the optical lens structure symmetrical, and are also conducive to balancing image quality and aperture size.

[0025] Secondly, embodiments of this application also provide a camera module, including the optical lens and photosensitive element described in the first aspect above, wherein the photosensitive element is disposed on the image side of the optical lens.

[0026] The camera module in this embodiment achieves the same technical effect as the optical lens in the first aspect, and will not be described again here.

[0027] In some embodiments, the optical lens further includes a filter.

[0028] In some embodiments, the filter is an infrared cutoff filter.

[0029] By implementing the above settings, infrared interference during the imaging process of the optical lens can be reduced, thereby further improving the imaging quality of the optical lens.

[0030] In some embodiments, the filter is provided with a laser cutoff film.

[0031] The above settings make the optical lens suitable for laser therapy.

[0032] In some embodiments, the photosensitive element is provided with a protective sheet.

[0033] The above settings can effectively protect the photosensitive element.

[0034] Thirdly, embodiments of this application also provide an endoscope, including the camera module described in the second aspect above.

[0035] The endoscope in this embodiment achieves the same technical effect as the camera module in the second aspect, and will not be described again here.

[0036] Fourthly, embodiments of this application also provide an endoscope system, including a light source host, an image processing device, and the endoscope described in the third aspect above.

[0037] The camera module in this embodiment achieves the same technical effect as the endoscope in the third aspect, and will not be described again here. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a structural optical path diagram of the optical lens at the telephoto end in Embodiment 1 of this application; Figure 2 This is a magnification chromatic aberration diagram of the optical lens at the telephoto end in Embodiment 1 of this application; Figure 3 This is a spherical aberration diagram of the optical lens at the telephoto end in Embodiment 1 of this application; Figure 4 This is an astigmatism image of the optical lens at the telephoto end in Embodiment 1 of this application; Figure 5 This is a distortion diagram of the optical lens at the telephoto end in Embodiment 1 of this application; Figure 6 This is a structural optical path diagram of the optical lens at near-focal distance in Embodiment 1 of this application; Figure 7 This is a magnification chromatic aberration diagram of the optical lens at near-focal distance in Embodiment 1 of this application; Figure 8 This is a spherical aberration diagram of the optical lens at near-focal distance in Embodiment 1 of this application; Figure 9 This is an astigmatism image of the optical lens at near-focus in Embodiment 1 of this application; Figure 10 This is a distortion diagram of the optical lens at near-focus in Embodiment 1 of this application; Figure 11 This is a schematic diagram of the optical lens at the telephoto end in Embodiment 2 of this application; Figure 12 This is a magnification chromatic aberration diagram of the optical lens at the telephoto end in Embodiment 2 of this application; Figure 13 This is a spherical aberration diagram of the optical lens at the telephoto end in Embodiment 2 of this application; Figure 14 This is an astigmatism image of the optical lens at the telephoto end in Embodiment 2 of this application; Figure 15 This is a distortion diagram of the optical lens at the telephoto end in Embodiment 2 of this application; Figure 16 This is a schematic diagram of the optical lens at near-focal distance in Embodiment 2 of this application; Figure 17 This is a magnification chromatic aberration diagram of the optical lens at near-focal distance in Embodiment 2 of this application; Figure 18 This is a spherical aberration diagram of the optical lens at near-focal distance in Embodiment 2 of this application; Figure 19 This is an astigmatism image of the optical lens at near-focal distance in Embodiment 2 of this application; Figure 20 This is a distortion diagram of the optical lens at near-focus in Embodiment 2 of this application; Figure 21 This is a schematic diagram of the optical lens at the telephoto end in Embodiment 3 of this application; Figure 22 This is a magnification chromatic aberration diagram of the optical lens at the telephoto end in Embodiment 3 of this application; Figure 23 This is a spherical aberration diagram of the optical lens at the telephoto end in Embodiment 3 of this application; Figure 24 This is an astigmatism image of the optical lens at the telephoto end in Embodiment 3 of this application; Figure 25 This is a distortion diagram of the optical lens at the telephoto end in Embodiment 3 of this application; Figure 26 This is a schematic diagram of the optical lens at near-focal distance in Embodiment 3 of this application; Figure 27 This is a magnification chromatic aberration diagram of the optical lens at near-focal distance in Embodiment 3 of this application; Figure 28 This is a spherical aberration diagram of the optical lens at near-focal distance in Embodiment 3 of this application; Figure 29 This is an astigmatism image of the optical lens at near-focal distance in Embodiment 3 of this application; Figure 30 This is a distortion diagram of the optical lens at near-focus in Embodiment 3 of this application; Figure 31 This is a schematic diagram of the optical lens at the telephoto end in Embodiment 4 of this application; Figure 32 This is a magnification chromatic aberration diagram of the optical lens at the telephoto end in Embodiment 4 of this application; Figure 33 This is a spherical aberration diagram of the optical lens at the telephoto end in Embodiment 4 of this application; Figure 34 This is an astigmatism image of the optical lens at the telephoto end in Embodiment 4 of this application; Figure 35 This is a distortion diagram of the optical lens at the telephoto end in Embodiment 4 of this application; Figure 36 This is a schematic diagram of the optical lens at near-focal distance in Embodiment 4 of this application; Figure 37 This is a magnification chromatic aberration diagram of the optical lens at near-focal distance in Embodiment 4 of this application; Figure 38 This is a spherical aberration diagram of the optical lens at near-focal distance in Embodiment 4 of this application; Figure 39 This is an astigmatism image of the optical lens at near-focus in Embodiment 4 of this application; Figure 40 This is a distortion diagram of the optical lens at near-focus in Embodiment 4 of this application; Figure 41 This is a schematic diagram of the optical lens at the telephoto end in Embodiment 5 of this application; Figure 42 This is a magnification chromatic aberration diagram of the optical lens at the telephoto end in Embodiment 5 of this application; Figure 43 This is a spherical aberration diagram of the optical lens at the telephoto end in Embodiment 5 of this application; Figure 44 This is an astigmatism image of the optical lens at the telephoto end in Embodiment 5 of this application; Figure 45 This is a distortion diagram of the optical lens at the telephoto end in Embodiment 5 of this application; Figure 46 This is a schematic diagram of the optical lens at near-focal point in Embodiment 5 of this application; Figure 47 This is a magnification chromatic aberration diagram of the optical lens at near-focal distance in Embodiment 5 of this application; Figure 48This is a spherical aberration diagram of the optical lens at near-focal distance in Embodiment 5 of this application; Figure 49 This is an astigmatism image of the optical lens at near-focal distance in Embodiment 5 of this application; Figure 50 This is a distortion diagram of the optical lens at near-focus in Embodiment 5 of this application; Figure 51 This is a schematic diagram of the optical lens at the telephoto end in Embodiment Six of this application; Figure 52 This is a magnification chromatic aberration diagram of the optical lens at the telephoto end in Embodiment Six of this application; Figure 53 This is a spherical aberration diagram of the optical lens at the telephoto end in Embodiment Six of this application; Figure 54 This is an astigmatism image of the optical lens at the telephoto end in Embodiment Six of this application; Figure 55 This is a distortion diagram of the optical lens at the telephoto end in Embodiment Six of this application; Figure 56 This is a schematic diagram of the optical lens at near-focal distance in Embodiment Six of this application; Figure 57 This is a magnification chromatic aberration diagram of the optical lens at near-focal distance in Embodiment Six of this application; Figure 58 This is a spherical aberration diagram of the optical lens at near-focal distance in Embodiment Six of this application; Figure 59 This is an astigmatism image of the optical lens at near-focal distance in Embodiment Six of this application; Figure 60 This is a distortion diagram of the optical lens at near-focal distance in Embodiment Six of this application; Figure 61 This is a schematic diagram of the optical lens at the telephoto end in Embodiment 7 of this application; Figure 62 This is a magnification chromatic aberration diagram of the optical lens at the telephoto end in Embodiment 7 of this application; Figure 63 This is a spherical aberration diagram of the optical lens at the telephoto end in Embodiment 7 of this application; Figure 64 This is an astigmatism image of the optical lens at the telephoto end in Embodiment 7 of this application; Figure 65 This is a distortion diagram of the optical lens at the telephoto end in Embodiment 7 of this application; Figure 66 This is a schematic diagram of the optical lens at near-focal distance in Embodiment 7 of this application; Figure 67 This is a magnification chromatic aberration diagram of the optical lens at near-focal distance in Embodiment 7 of this application; Figure 68 This is a spherical aberration diagram of the optical lens at near-focal distance in Embodiment 7 of this application; Figure 69 This is an astigmatism image of the optical lens at near-focal distance in Embodiment 7 of this application; Figure 70 This is a distortion diagram of the optical lens in Embodiment 7 of this application at near-focal distance.

[0040] The following are the labeling elements in the figure: First lens L1; Second lens L2; ​​Third lens L3; Fourth lens L4; Fifth lens L5; Sixth lens L6; Filter L7; Protective film L8; Aperture stop STO. Detailed Implementation

[0041] For ease of understanding, the English abbreviations and related technical terms used in the embodiments of this application will be explained and described below.

[0042] Focal power is equal to the difference between the convergence of the image-side beam and the convergence of the object-side beam; it characterizes the ability of an optical lens to deflect light.

[0043] A lens or lens group with positive optical power, having a positive focal length, and having the effect of converging light.

[0044] A lens or lens group with negative optical power has a negative focal length and has the effect of diverging light.

[0045] Focal length (F), also known as focal length, is a measure of how well light converges or diverges in optical lenses. It refers to the perpendicular distance from the optical center of a lens or lens group to the focal plane when a distant object is projected into a sharp image. From a practical perspective, it can be understood as the distance from the lens center to the focal plane when the object is at infinity. For prime lenses, the position of their optical center remains constant; for telephoto lenses, changes in the lens's optical center result in changes in the focal length.

[0046] Back focal length FBL is the length from the rearmost point of the optical lens to the image plane.

[0047] Total Track Length (TTL) refers to the distance from the center of the lens to the focal point where light converges; in other words, within a module, it is the distance from the center of the lens to the imaging plane of the sensor surface.

[0048] The object side is defined by the lens; the side where the object is located is called the object side, and the surface of the lens closest to the object side is called the object side surface.

[0049] The image side is the side on which the image of the object is located, with the lens as the boundary. The surface of the lens closest to the image side is called the image side surface.

[0050] An aperture diaphragm is a device used to control the amount of light passing through the lens and entering the sensor inside the camera body; it is usually located inside the lens.

[0051] Aperture number, also known as F-number (FNO), is a relative value derived from the lens's focal length and entrance pupil diameter (the reciprocal of the relative aperture). A smaller aperture number allows more light to enter the lens in the same unit of time. A larger aperture number results in a shallower depth of field, blurring the background and creating an effect similar to a telephoto lens.

[0052] Total track length (TTL) refers to the total length from the surface of the lens closest to the object to the imaging plane. TTL is a major factor in determining the height of the camera.

[0053] The imaging plane is located on the image side of all lenses in an optical lens, and is the surface on which the image is formed after light passes through each lens in the optical lens.

[0054] The optical axis is a perpendicular axis passing through the center of a lens. The lens optical axis is the axis passing through the centers of all the lenses in the lens. When light rays parallel to the optical axis enter a convex lens, an ideal convex lens should have all the light rays converging at a single point behind the lens; this point where all the light rays converge is called the focal point.

[0055] The focal point is the point where parallel light rays converge after being refracted by a lens or lens group.

[0056] Aberrations: Optical lenses have the properties of an ideal optical system at the optical axis, where near-axis rays emitted from a point on an object intersect the image plane at a point (i.e., the optical axis image point). However, in reality, rays passing through different apertures of the lens rarely intersect perfectly at a single point, but rather deviate from the position of the near-axis image point. These differences are collectively referred to as aberrations.

[0057] Spherical aberration occurs when light rays entering a spherical lens are more easily refracted and bent at the edges of the lens compared to the center. This results in reduced sharpness and contrast, as well as the formation of bokeh, thus degrading image quality. The larger the aperture, the more severe the aberration. Stopping down the aperture can improve the situation, but it cannot completely eliminate it. This aberration caused by spherical lenses is called spherical aberration.

[0058] Distortion, also known as image distortion, refers to the degree of distortion in the image formed by an optical lens relative to the object itself. Distortion occurs due to the spherical aberration of the aperture. The height of the intersection point between the principal ray and the Gaussian image plane after passing through the lens in different fields of view is not equal to the ideal image height; this difference is the distortion. Therefore, distortion only changes the imaging position of the off-axis object point on the ideal plane, causing a distortion in the image shape, but it does not affect the image's sharpness.

[0059] Astigmatism occurs because the object point is not on the optical axis of the lens, causing the emitted beam of light to be tilted at an angle to the optical axis. After refraction by the lens, the convergence points of the meridional and sagittal beams are not at the same point. In other words, the beam cannot be focused at a single point, resulting in an unclear image and thus astigmatism. The meridional and sagittal beams are the names of the beams within two perpendicular planes of a rotationally symmetric optical lens.

[0060] The meridional plane is the plane formed by the principal ray (principal beam) of an object point outside the optical axis and the optical axis.

[0061] The sagittal surface is the plane that passes through the principal ray (principal beam) of an object point outside the optical axis and is perpendicular to the meridional plane.

[0062] Field curvature refers to the difference in optical axis between the position of the sharpest image point after rays from the off-center field of view pass through an optical lens assembly and the position of the sharpest image point in the center field of view. When a lens has field curvature, the intersection of the entire beam does not coincide with the ideal image point. Although a sharp image point can be obtained at each specific point, the entire image plane is a curved surface.

[0063] Magnification chromatic aberration is a color difference caused by the difference in image size due to the different imaging heights (i.e., magnification) of different colored lights.

[0064] Cemented lenses, also known as bonded lenses, are composite lenses composed of two or more lenses bonded together. Cemented lenses have better tolerance sensitivity than single lenses, which is more beneficial for lens assembly when used in endoscope products, thus improving the imaging quality of the endoscope.

[0065] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0066] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0067] An electronic endoscope is an instrument that can be inserted into the human body, allowing doctors to directly observe the tissue morphology and lesions of the body cavities and internal organs, and to make accurate diagnoses of diseases. Currently, electronic endoscopes are widely used in various fields of clinical medicine, and play an irreplaceable role, especially in the diagnosis of intrauterine diseases.

[0068] Camera modules, such as endoscope objectives, are typically used in conjunction with endoscopes to transmit images detected by the endoscope to a detector for better observation. They are commonly used in modern minimally invasive surgery, as well as in gastrointestinal examinations and treatments.

[0069] For accurate diagnosis of lesions, endoscopes are expected to have excellent image quality, which helps doctors better identify lesions and improve diagnostic efficiency. At the same time, endoscopes are also expected to have a wide field of view, increasing the doctor's observation range and shortening examination time. Developing an optical lens with a wide field of view, high image quality, and miniaturization has become an important research topic in the industry.

[0070] To address the aforementioned technical problems, this application provides an optical lens and a camera module.

[0071] like Figure 1 As shown, the camera module includes an optical lens and a photosensitive element (…). Figure 1 (IMAGE in the image), the image sensor is located on the image side of the optical lens.

[0072] The working principle of a camera module is as follows: the light reflected from the subject passes through the optical lens to generate an optical image, which is then projected onto the photosensitive surface of the photosensitive element. The photosensitive element converts the optical image into an electrical signal, i.e., an analog image signal, and transmits it to the processor.

[0073] A photosensitive element (also known as an image sensor) is a semiconductor chip containing hundreds of thousands to millions of photodiodes on its surface. When illuminated by light, these photodiodes generate electrical charges. Photosensitive elements can be charge-coupled devices (CCDs) or complementary metal-oxide-semiconductor (CMOS) devices. CCDs are made of a highly sensitive semiconductor material that converts light into electrical charges. A charge-coupled device consists of many photosensitive units, typically measured in megapixels. When light illuminates the surface of the photosensitive element, each photosensitive unit reflects a charge onto the component. The signals generated by all the photosensitive units are added together to form a complete image.

[0074] Among them, optical lenses mainly use the refraction principle of lenses to form images, that is, light from the scene passes through the optical lens and forms a clear image on the focal plane, and the image of the scene is recorded by the photosensitive element located on the focal plane.

[0075] The aforementioned camera module can be used in electronic devices with camera and photo-taking capabilities. For example, the camera module can serve as an endoscope with a shooting function, and the optical lens can serve as the objective lens of the endoscope. Of course, the aforementioned electronic device can be any other electronic device with a shooting function besides an endoscope; no specific limitation is made here.

[0076] like Figure 1 As shown in the figure, an embodiment of this application provides an optical lens. The optical lens includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens arranged from the object side to the image side; the first lens has negative optical power, the second lens has negative optical power, the third lens has positive optical power, and the fourth lens has positive optical power; the third lens is movable along the optical axis of the optical lens to enable the optical lens to focus between the telephoto and near-focal points.

[0077] By rationally allocating the optical power of the optical lens, with both the first and second lenses having negative optical power, when light passes through the various lens groups of the optical lens, the light first diverges twice and then converges twice. This makes the light transition smoother, which not only reduces aberrations, increases the field of view and resolution, thereby improving image quality, but also helps to reduce the aperture of the optical lens.

[0078] like Figure 1 As shown, in some embodiments, the optical lens also includes a filter L7.

[0079] In this way, optical lenses can function as both the entry and exit light paths of a certain filter in the optical path, that is, they can block light or not, thus diversifying the functions of optical lenses, fulfilling specific optical requirements, reducing the number of parts, and simplifying the assembly process. For example, in the cold light source optical path of a medical endoscope, without changing the light-emitting component, the bandwidth of a certain monochromatic light in the optical path can be changed to achieve the selection of different wavelength light source illumination modes.

[0080] The aforementioned filter is an infrared cutoff filter. This reduces infrared interference during the imaging process of the optical lens, thereby further improving the image quality of the optical lens.

[0081] The aforementioned infrared cut-off sheet is short for infrared cut-off filter (also called infrared filter or heat-absorbing filter), a type of filter used to filter infrared wavelengths. For example, when installed on incandescent light equipment (such as slide projectors), it can prevent unnecessary heat from burning the lens; when installed on cameras with solid-state electronic devices (CCD image sensors or CMOS image sensors), it can prevent infrared light from passing through the camera lens and causing image distortion.

[0082] In some embodiments, the filter is provided with a laser cutoff membrane (not shown in the figure).

[0083] By setting a laser cutoff film on the filter, the optical lens can be made suitable for laser therapy.

[0084] The aforementioned laser cutoff film can be a functional film such as a YAG laser cutoff film or an LD laser cutoff film. The laser cutoff film can be set on one side of the filter or on both sides of the filter; no specific limitation is made here.

[0085] like Figure 1 As shown, in some embodiments, a protective sheet L8 is also provided on the photosensitive element. This not only protects the photosensitive element but also serves to support it, facilitating installation.

[0086] like Figure 1 and Figure 6 The diagram illustrates the optical path of the optical lens in Embodiment 1 of this application at the telephoto and near-focal points. The optical lens comprises elements arranged from the object side to the image side (e.g., ...). Figure 1 The lenses shown (arranged from left to right) are: first lens L1, second lens L2, third lens L3, aperture stop STO, fourth lens L4, fifth lens L5, and sixth lens L6. Fifth lens L5 and sixth lens L6 form a cemented lens. Specifically, the optical power of each lens is shown in Table 1b below.

[0087] The fourth lens L4 can move along the optical axis of the optical lens so that the optical lens can image between the telephoto and near-focal points.

[0088] As an optional embodiment of this application, based on Embodiment 1 of this application, the parameter values ​​of each lens of the optical lens can be referred to Tables 1a to 1c.

[0089]

[0090] It should be noted that in Table 1a, "Surface Number" refers to the number of each surface arranged from the object side to the image side. "Standard" in the surface type represents a standard spherical surface. The radius R value is the lens corresponding to the surface number, which is the radius of curvature of the object side or image side of the lens corresponding to each surface number at the optical axis. "Infinite" in the "Radius of Curvature" parameter series means that the object side or image side of the lens is a plane. The value in the "Thickness / Spacing" parameter series for each lens is the thickness of the lens on the optical axis, or the distance on the optical axis from the image side of the lens to the object side of the next lens. The value in the "Thickness" parameter series for the stop STO is the distance on the optical axis from the center of the stop STO to the object side of the next lens.

[0091] “OBJ” refers to the object plane. The two values ​​inside and outside the parentheses in the “Thickness” parameter series for “OBJ” refer to two different object distances of the optical lens. The value of “S4” in the “Thickness” parameter series represents the distance between the image-side surface of the second lens L2 and the image-side surface of the third lens L3. The value of “S6” in the “Thickness” parameter series represents the distance between the image-side surface of the third lens L3 and the aperture stop STO.

[0092] The focusing distances at different object distances differ between the second lens L2 and the third lens L3, as well as between the third lens L3 and the aperture stop STO. For example, when combined with... Figure 1 , Figure 6 As shown in Table 1a, in this embodiment, when the object distance is 15mm, the distance between the image-side surface of the second lens L2 and the image-side surface of the third lens L3 is 0.207mm, and the distance between the image-side surface of the third lens L3 and the aperture stop STO is 0.537mm. When the object distance is 4mm, the distance between the image-side surface of the second lens L2 and the image-side surface of the third lens L3 is 0.384mm, and the distance between the image-side surface of the third lens L3 and the aperture stop STO is 0.360mm.

[0093] In this embodiment, when the optical lens focuses and images within a depth-of-field range of 2mm-100mm, its total optical length L is 8.10mm; image height is 0.8mm; and field of view is 135°. In this embodiment, the focal length f of the optical lens at the telephoto end is 0.86mm; and the focal length f at the near-focal end is 0.84mm.

[0094] It should be noted that the depth of field range of the optical lens in this embodiment is 5mm-100mm at the telephoto end and 2mm-6mm at the near-focal end. Furthermore, regarding the field of view, the optical lens in this embodiment has the same field of view at both the telephoto and near-focal ends. Of course, the field of view of the optical lens at the telephoto and near-focal ends can also be different. Generally, the field of view at the near-focal end can be slightly smaller than the field of view at the telephoto end. The specific selection is determined in conjunction with other optical parameters of the optical lens, and no specific limitation is made here.

[0095] The positive and negative values ​​of the optical power of each lens in the optical lens in this embodiment are shown in Table 1b.

[0096]

[0097] It should be noted that the "+" and "-" in Table 1b represent the positive and negative optical power of each lens in the optical lens of Example 1. "+" indicates that the lens has positive optical power; "-" indicates that the lens has negative optical power.

[0098] The concavity or convexity of the object side or image side of each lens in the optical lens of Embodiment 1 at the optical axis is shown in Table 1c.

[0099]

[0100] It should be noted that in Table 1d, “∞+”, “--”, “++”, and “+-” represent the concavity or convexity of the object-side or image-side of each lens at the optical axis. “∞+” indicates that the object-side of the lens is flat at the optical axis, while the image-side is convex towards the object. “--” indicates that both the object-side and image-side of the lens are concave towards the object. “++” indicates that both the object-side and image-side of the lens are convex towards the object. “+-” indicates that both the object-side and image-side of the lens are convex towards the object, i.e., a double-convex crescent structure. Of course, in addition to those shown in the table, concavity and convexity also include "-+", "+∞", "-∞", "∞-", etc. Among them, "-+" represents that the object side of the lens is concave towards the object side at the optical axis, and the image side is convex towards the object side at the optical axis, which is a double concave structure; "+∞" represents that the object side of the lens is convex towards the object side at the optical axis, and the image side is flat at the optical axis; "-∞" represents that the object side of the lens is concave towards the object side at the optical axis, and the image side is flat at the optical axis; "∞-" represents that the object side of the lens is flat at the optical axis, and the image side is concave towards the object side at the optical axis.

[0101] Combination Figure 1 and Figure 6 The schematic diagram and optical path diagram of the optical lens in Embodiment 1, as well as the main parameters of the optical lens in Embodiment 1 given in Tables 1a to 1c, were obtained through simulation. Figures 2 to 5 , Figures 6 to 10 The simulation diagram is shown below. Among them, Figures 2 to 5 The diagrams shown are the magnification chromatic aberration diagram, spherical aberration diagram, astigmatism diagram, and distortion diagram of the optical lens at the telephoto point in Embodiment 1. Figures 7 to 10 The diagrams shown are the magnification chromatic aberration diagram, spherical aberration diagram, astigmatism diagram, and distortion diagram of the optical lens at near-focal distance in Embodiment 1.

[0102] in, Figure 2 and Figure 7 The horizontal axis of the magnification chromatic aberration diagram shown represents the vertical position of light of different wavelengths on the image plane of the photosensitive element, and the vertical axis represents the field of view.

[0103] Figure 3 and Figure 8 The horizontal axis of the spherical aberration diagram shown represents the axial position of light of different wavelengths on the image plane of the photosensitive element, in mm; the vertical axis represents the normalized entrance pupil coordinates (note: no unit).

[0104] Figure 4 and Figure 9 The horizontal axis of the astigmatism diagram shown represents the vertical position of light of different wavelengths on the image plane of the photosensitive element, in mm; the vertical axis represents the field of view.

[0105] Figure 5 and Figure 10The horizontal axis of the distortion graph shown is the distortion value, and the vertical axis is the field of view angle.

[0106] The above descriptions of the magnification chromatic aberration diagram, spherical aberration diagram, astigmatism diagram, and distortion diagram are the same as those in other embodiments, and will not be repeated below.

[0107] from Figure 2 and Figure 7 As can be seen, with the increase of the field of view, the vertical chromatic aberration of the optical lens gradually increases, but the transverse chromatic aberration can be controlled within the allowable offset of the diffraction limit, resulting in smaller chromatic aberration and improved image quality. From Figure 3 and Figure 8 As can be seen, the axial values ​​for different wavelengths are controlled within ±0.05mm, and the chromatic aberration is good throughout the entire entrance pupil range. Therefore, the on-axis chromatic aberration of this optical lens is good. From Figure 4 and Figure 9 As can be seen, the astigmatism value of the optical lens is controlled between -0.01 and 0.05. With the increase of the field of view, the astigmatism of the system gradually increases, but the astigmatism value can be controlled within ±0.05mm, indicating good image quality of the optical lens. Figure 5 and Figure 10 As can be seen, the distortion of the optical lens gradually increases with the increase of the field of view, but the distortion value can be controlled within 80%, reducing the impact of image distortion on image quality. This indicates that the optical lens has good imaging quality.

[0108] Figure 11 and Figure 16 The diagram shows the structure of the optical lens in Embodiment 2 at the telephoto and near-focal points. The main differences between the optical lens in Embodiment 2 and the optical lens in Embodiment 1 lie in the parameters of each lens, the relationships they satisfy, the optical power, and the concavity / convexity at the optical axis.

[0109] As an optional embodiment of this application, based on Embodiment 2 of this application, the parameter values ​​of each lens of the optical lens can be referred to Tables 2a to 2c.

[0110]

[0111] In this embodiment, the optical lens has a total optical length L of 7.91 mm, an image height of 0.8 mm, and a field of view of 135° when focusing between 2 mm and 100 mm. The optical lens in this embodiment has a focal length f of 0.85 mm at the telephoto end and a focal length f of 0.83 mm at the near-focal end.

[0112] The positive and negative values ​​of the optical power of each lens in the optical lens in this embodiment are shown in Table 2b.

[0113]

[0114] The concavity and convexity of each lens at the optical axis in this embodiment are shown in Table 2c.

[0115]

[0116] Combination Figure 11 and Figure 16 The schematic diagram of the optical lens in Embodiment 2 shown, and the main parameters of the optical lens in Embodiment 2 given in Tables 2a to 2c, were obtained through simulation. Figures 12 to 20 The simulation diagram shown is from... Figure 12 and Figure 17 As can be seen, with the increase of the field of view, the vertical chromatic aberration of the optical lens gradually increases, but the transverse chromatic aberration can be controlled within the allowable offset of the diffraction limit, resulting in smaller chromatic aberration and improved image quality. From Figure 13 and Figure 18 As can be seen, the axial values ​​for different wavelengths are controlled within ±0.04mm, and the chromatic aberration is good throughout the entire entrance pupil range. Therefore, the on-axis chromatic aberration of this optical lens is good. From Figure 14 and Figure 19 As can be seen, the astigmatism value of the optical lens is controlled between -0.02 and 0.05. With the increase of the field of view, the astigmatism of the system gradually increases, but the astigmatism value can be controlled within ±0.05mm, indicating good image quality of the optical lens. Figure 15 and Figure 20 As can be seen, the distortion of the optical lens gradually increases with the increase of the field of view, but the distortion value can be controlled within 70%, reducing the impact of image distortion on image quality. This indicates that the optical lens has good imaging quality.

[0117] Figure 21 and Figure 26 The diagram shows the structure of the optical lens of Embodiment 3 at the telephoto and near-focal points. The main differences between the optical lens of Embodiment 3 and the optical lens of Embodiment 1 lie in the parameters of each lens, the relationships they satisfy, the optical power, and the concavity / convexity at the optical axis.

[0118] As an optional embodiment of this application, based on Embodiment 3 of this application, the parameter values ​​of each lens of the optical lens can be referred to Tables 3a to 3c.

[0119]

[0120] In this embodiment, the optical lens has a total optical length L of 7.72mm, an image height of 0.8mm, and a field of view of 135° when focusing between 2mm and 100mm. The optical lens in this embodiment has a focal length f of 0.85mm at the telephoto end and a focal length f of 0.83mm at the near-focal end.

[0121] The positive and negative values ​​of the optical power of each lens in the optical lens in this embodiment are shown in Table 3b.

[0122]

[0123] The concavity and convexity of each lens at the optical axis in this embodiment are shown in Table 3c.

[0124]

[0125] Combination Figure 21 and Figure 26 The schematic diagram of the optical lens in Embodiment 4 and the main parameters of the optical lens in Embodiment 3 given in Tables 3a to 3c were obtained through simulation. Figures 22 to 30 The simulation diagram shown is from... Figure 22 and Figure 27 As can be seen, with the increase of the field of view, the vertical chromatic aberration of the optical lens gradually increases, but the transverse chromatic aberration can be controlled within the allowable offset of the diffraction limit, resulting in smaller chromatic aberration and improved image quality. From Figure 23 and Figure 28 As can be seen, the axial values ​​for different wavelengths are controlled within ±0.06mm, and the chromatic aberration is good throughout the entire entrance pupil range. Therefore, the on-axis chromatic aberration of this optical lens is good. From Figure 24 and Figure 29 As can be seen, the astigmatism value of the optical lens is controlled between -0.01 and 0.06. With the increase of the field of view, the astigmatism of the system gradually increases, but the astigmatism value can be controlled within ±0.06mm, indicating good image quality of the optical lens. Figure 25 and Figure 30 As can be seen, the distortion of the optical lens gradually increases with the increase of the field of view, but the distortion value can be controlled within 70%, reducing the impact of image distortion on image quality. This indicates that the optical lens has good imaging quality.

[0126] Figure 31 and Figure 36 The diagram shows the structure of the optical lens in Embodiment 4 at the telephoto and near-focal points. The main differences between the optical lens in Embodiment 4 and the optical lens in Embodiment 1 lie in the parameters of each lens, the relationships they satisfy, the optical power, and the concavity / convexity at the optical axis.

[0127] As an optional embodiment of this application, based on Embodiment 4 of this application, the parameter values ​​of each lens of the optical lens can be referred to Tables 4a to 4c.

[0128]

[0129] In this embodiment, the optical lens has a total optical length L of 8.06 mm, an image height of 0.81 mm, and a field of view of 135° when focusing between 2 mm and 100 mm. The optical lens in this embodiment has a focal length f of 0.84 mm at the telephoto end and a focal length f of 0.82 mm at the near-focal end.

[0130] The positive and negative values ​​of the optical power of each lens in the optical lens in this embodiment are shown in Table 4b.

[0131]

[0132] The concavity and convexity of each lens at the optical axis in this embodiment are shown in Table 4c.

[0133]

[0134] Combination Figure 31 and Figure 36 The schematic diagram of the optical lens in Embodiment 4 shown, and the main parameters of the optical lens in Embodiment 4 given in Tables 4a to 4c, were obtained through simulation. Figures 32 to 40 The simulation diagram shown is from... Figure 32 and Figure 37 As can be seen, with the increase of the field of view, the vertical chromatic aberration of the optical lens gradually increases, but the transverse chromatic aberration can be controlled within the allowable offset of the diffraction limit, resulting in smaller chromatic aberration and improved image quality. From Figure 33 and Figure 38 As can be seen, the axial values ​​for different wavelengths are controlled within ±0.05mm, and the chromatic aberration is good throughout the entire entrance pupil range. Therefore, the on-axis chromatic aberration of this optical lens is good. From Figure 34 and Figure 39 As can be seen, the astigmatism value of the optical lens is controlled between 0.01 and 0.06. With the increase of the field of view, the astigmatism of the system gradually increases, but the astigmatism value can be controlled within ±0.06mm, indicating good image quality of the optical lens. Figure 35 and Figure 40 As can be seen, the distortion of the optical lens gradually increases with the increase of the field of view, but the distortion value can be controlled within 70%, reducing the impact of image distortion on image quality. This indicates that the optical lens has good imaging quality.

[0135] Figure 41 and Figure 46 The diagram shows the structure of the optical lens of Embodiment 5 at the telephoto and near-focal points. The main differences between the optical lens of Embodiment 5 and the optical lens of Embodiment 1 lie in the parameters of each lens, the relationships they satisfy, the optical power, and the concavity / convexity at the optical axis.

[0136] As an optional embodiment of this application, based on Embodiment 5 of this application, the parameter values ​​of each lens of the optical lens can be referred to Tables 5a to 5c.

[0137]

[0138] In this embodiment, the optical lens has a total optical length L of 9.11 mm, an image height of 0.81 mm, and a field of view of 160° when focusing between 2 mm and 100 mm. The optical lens in this embodiment has a focal length f of 0.82 mm at the telephoto end and a focal length f of 0.80 mm at the near-focal end.

[0139] The positive and negative values ​​of the optical power of each lens in the optical lens in this embodiment are shown in Table 5b.

[0140]

[0141] The concavity and convexity of each lens at the optical axis in this embodiment are shown in Table 5c.

[0142]

[0143] Combination Figure 41 and Figure 46 The schematic diagram of the optical lens in Embodiment 5 shown, and the main parameters of the optical lens in Embodiment 5 given in Tables 5a to 5c, were obtained through simulation. Figures 42 to 50 The simulation diagram shown is from... Figure 42 and Figure 47 As can be seen, with the increase of the field of view, the vertical chromatic aberration of the optical lens gradually increases, but the transverse chromatic aberration can be controlled within the allowable offset of the diffraction limit, resulting in smaller chromatic aberration and improved image quality. From Figure 43 and Figure 48 As can be seen, the axial values ​​for different wavelengths are controlled within ±0.06mm, and the chromatic aberration is good throughout the entire entrance pupil range. Therefore, the on-axis chromatic aberration of this optical lens is good. From Figure 44 and Figure 49 As can be seen, the astigmatism value of the optical lens is controlled between -0.01 and 0.06. With the increase of the field of view, the astigmatism of the system gradually increases, but the astigmatism value can be controlled within ±0.06mm, indicating good image quality of the optical lens. Figure 45 and Figure 50 As can be seen, the distortion of the optical lens gradually increases with the increase of the field of view, but the distortion value can be controlled within 80%, reducing the impact of image distortion on image quality. This indicates that the optical lens has good imaging quality.

[0144] Figure 51 and Figure 56The diagram shows the structure of the optical lens of Embodiment Six at the telephoto and near-focal points. The main differences between the optical lens of Embodiment Six and the optical lens of Embodiment One are the parameters of each lens, the relationships they satisfy, the optical power, and the concavity / convexity at the optical axis.

[0145] As an optional embodiment of this application, based on Embodiment Six of this application, the parameter values ​​of each lens of the optical lens can be referred to Tables 6a to 6c.

[0146]

[0147] In this embodiment, the optical lens has a total optical length L of 9.34 mm, an image height of 0.81 mm, and a field of view of 160° when focusing between 2 mm and 100 mm. The optical lens in this embodiment has a focal length f of 0.79 mm at the telephoto end and a focal length f of 0.77 mm at the near-focal end.

[0148] The positive and negative values ​​of the optical power of each lens in the optical lens in this embodiment are shown in Table 4b.

[0149]

[0150] The concavity and convexity of each lens at the optical axis in this embodiment are shown in Table 6c.

[0151]

[0152] Combination Figure 51 and Figure 56 The schematic diagram of the optical lens in Embodiment Six shown, and the main parameters of the optical lens in Embodiment Six given in Tables 6a to 6c, were obtained through simulation. Figures 52 to 60 The simulation diagram shown is from... Figure 52 and Figure 57 As can be seen, with the increase of the field of view, the vertical chromatic aberration of the optical lens gradually increases, but the transverse chromatic aberration can be controlled within the allowable offset of the diffraction limit, resulting in smaller chromatic aberration and improved image quality. From Figure 53 and Figure 58 As can be seen, the axial values ​​for different wavelengths are controlled within ±0.06mm, and the chromatic aberration is good throughout the entire entrance pupil range. Therefore, the on-axis chromatic aberration of this optical lens is good. From Figure 54 and Figure 59 As can be seen, the astigmatism value of the optical lens is controlled between -0.01 and 0.06. With the increase of the field of view, the astigmatism of the system gradually increases, but the astigmatism value can be controlled within ±0.06mm, indicating good image quality of the optical lens. Figure 55 and Figure 60As can be seen, the distortion of the optical lens gradually increases with the increase of the field of view, but the distortion value can be controlled within 80%, reducing the impact of image distortion on image quality. This indicates that the optical lens has good imaging quality.

[0153] Figure 61 and Figure 66 The diagram shows the structure of the optical lens of Embodiment 7 at the telephoto and near-focal points. The main differences between the optical lens of Embodiment 7 and the optical lens of Embodiment 1 lie in the parameters of each lens, the relationships they satisfy, the optical power, and the concavity / convexity at the optical axis.

[0154] As an optional embodiment of this application, based on Embodiment 7 of this application, the parameter values ​​of each lens of the optical lens can be referred to Tables 7a to 7c.

[0155]

[0156] In this embodiment, the total optical length L of the optical lens is 8.04mm when focusing and imaging between 2mm and 100mm; the image height is 0.81mm. In this embodiment, the focal length f of the optical lens at the telephoto end is 0.83mm, and the field of view is 156°; the focal length f at the near-focal end is 0.81mm, and the field of view is 148°.

[0157] The positive and negative values ​​of the optical power of each lens in the optical lens in this embodiment are shown in Table 7b.

[0158]

[0159] The concavity and convexity of each lens at the optical axis in this embodiment are shown in Table 7c.

[0160]

[0161] Combination Figure 61 and Figure 66 The schematic diagram of the optical lens in Embodiment 7 shown, and the main parameters of the optical lens in Embodiment 7 given in Tables 7a to 7c, were obtained through simulation. Figures 62 to 70 The simulation diagram shown is from... Figure 62 and Figure 67 As can be seen, with the increase of the field of view, the vertical chromatic aberration of the optical lens gradually increases, but the transverse chromatic aberration can be controlled within the allowable offset of the diffraction limit, resulting in smaller chromatic aberration and improved image quality. From Figure 63 and Figure 68 As can be seen, the axial values ​​for different wavelengths are controlled within ±0.06mm, and the chromatic aberration is good throughout the entire entrance pupil range. Therefore, the on-axis chromatic aberration of this optical lens is good. From Figure 64 and Figure 69As can be seen, the astigmatism value of the optical lens is controlled between -0.02 and 0.06. With the increase of the field of view, the astigmatism of the system gradually increases, but the astigmatism value can be controlled within ±0.06mm, indicating good image quality of the optical lens. Figure 65 and Figure 70 As can be seen, the distortion of the optical lens gradually increases with the increase of the field of view, but the distortion value can be controlled within 80%, reducing the impact of image distortion on image quality. This indicates that the optical lens has good imaging quality.

[0162] Table 10 provides the optical parameters of the optical lenses in ten embodiments of this application, including the seven embodiments described above.

[0163]

[0164] Note: The following annotations explain the relationships between the optical lenses in the various embodiments: f is the focal length of the optical lens, which is equal to the EFL value of the optical lens.

[0165] f1 is the focal length of the first lens L1 in the optical lens; f2 is the focal length of the second lens L2 in the optical lens; f3 is the focal length of the third lens L3 in the optical lens; f4 is the focal length of the fourth lens L4 in the optical lens; fm is the focal length of the cemented lens composed of the fifth lens L5 and the sixth lens L6 in the optical lens, which is equal to the combined focal length of the fifth lens L5 and the sixth lens L6. R1 is the curvature of the object side surface of the second lens in the optical lens; R2 is the curvature of the image-side surface of the second lens in the optical lens.

[0166] It should be noted that the optical parameters of the optical lenses in Embodiments 1 to 7 correspond to those in the seven embodiments. Since the structures of the optical lenses in Embodiments 8, 9, and 10 are the same as those in the seven embodiments, only the parameters are slightly different, Table 10 lists the optical parameters of the corresponding formulas for the optical lenses in Embodiments 8, 9, and 10.

[0167] As can be seen from the optical parameters of the ten embodiments given in Table 10 above, the optical lens of this application satisfies the relationship: -0.5 <f4 / f2<-0.1。

[0168] If the ratio f4 / f2 is too small, the optical lens will be too long, which is not conducive to its use on products with limited installation space; if the ratio f4 / f2 is too large, the optical lens will have poor image quality in the depth of field range, and it will be difficult to correct spherical aberration, coma and chromatic aberration, and high-resolution images cannot be obtained.

[0169] By appropriately selecting the above parameters, when the ratio f4 / f2 satisfies the above relationship, the proper ratio of the focal length of the fourth lens L4 and the second lens L2 is beneficial for aberration correction and improving image quality within the depth of field. Furthermore, the shorter overall optical length of the optical lens helps reduce the overall length of the lens. When the optical lens is used as an endoscope objective and mounted on the rigid part of the endoscope, it helps reduce the length of the rigid part of the endoscope.

[0170] As can be seen from the optical parameters of the ten embodiments given in Table 10 above, the optical lens of this application satisfies the following relationship: 0 <f4 / fm<0.5。

[0171] If the ratio f4 / fm is too small, the aberrations produced by the fourth lens L4 cannot be completely corrected, which has a significant impact on the overall imaging quality of the optical lens; if the ratio f4 / fm is too large, not only will the total length of the optical lens be too long, but the aberrations produced by the last two lenses will also not be completely corrected.

[0172] By reasonably selecting the above parameters, when the ratio f4 / fm satisfies the above relationship, it is not only beneficial to correct the aberrations of the optical lens and improve the imaging quality, but also to shorten the total length of the optical lens.

[0173] As can be seen from the optical parameters of the ten embodiments given in Table 10 above, the optical lens of this application satisfies the following relationship: 2 <fm / f<50。

[0174] By appropriately selecting the above parameters, when the ratio fm / f satisfies the aforementioned relationship, better light can be collected onto the imaging surface after passing through the optical lens, improving the overall brightness of the image. It also facilitates the correction of axial and transverse chromatic aberration, balances aberrations generated by other lenses, improves image quality, and shortens the overall length of the optical lens. Furthermore, when the fifth lens L5 and the sixth lens L6 are cemented together to form a cemented lens, not only is tolerance sensitivity reduced, further improving image quality, but the length of the optical lens is further reduced, and assembly of the optical lens is also more convenient.

[0175] As can be seen from the optical parameters of the ten embodiments given in Table 10 above, the optical lens of this application satisfies the relationship: 0.1 <f2 / f1<0.4。

[0176] If the ratio f2 / f1 is too small, the first lens L1 of the optical lens will have significant aberrations, increasing the design difficulty of the entire optical lens and making it less tolerant. If the ratio f2 / f1 is too large, the aperture of the first lens L1 will be too large, making it difficult to achieve a smaller aperture. A smaller aperture refers to making the aperture of the optical lens as small as possible. This is especially important when the optical lens is used as an endoscope objective, and is a crucial design parameter.

[0177] By reasonably selecting the above parameters, when the ratio f2 / f1 satisfies the above relationship, the difference in negative optical power between the first lens L1 and the second lens L2 is small, and the deflection angle of light rays is small. This not only allows the aberrations and spherical aberrations of the optical lens to be well corrected, thereby further improving the imaging quality of the optical lens, but also facilitates the reduction of the diameter of the optical lens.

[0178] As can be seen from the optical parameters of the ten embodiments given in Table 10 above, the optical lens of this application satisfies the following relationship: 2 <f3 / f<8。

[0179] If the ratio f3 / f is too small, the spherical aberration of the first lens L1 and the second lens L2 will not be properly corrected, resulting in poor image quality. If the ratio f3 / f is too large, it will improve the image quality of the optical lens, but at the same time, it will make the optical lens too long, which is not conducive to miniaturization design.

[0180] By rationally allocating the optical power of each lens in the optical lens, when the ratio f3 / f satisfies the above relationship, the aberrations of the third lens L3 and the other lenses cancel each other out, thus improving the imaging quality; at the same time, it is also beneficial to shorten the length of the optical lens, thereby realizing the miniaturization design of the optical lens.

[0181] As can be seen from the optical parameters of the ten embodiments given in Table 10 above, the radius of curvature R1 of the object side and the radius of curvature R2 of the image side of the second lens group of the optical lens of this application satisfy the relationship: -1<(R1-R2) / (R1+R2)<3.

[0182] If the ratio (R1-R2) / (R1+R2) is too small, the astigmatism and coma correction of the optical lens will be overdone; if the ratio (R1-R2) / (R1+R2) is too large, the manufacturability of the second lens L2 will be reduced, and the aberration correction effect will decrease. It will also be unable to balance the aberrations generated by the first lens L1 and the third lens L3 in the optical lens, which will have a significant impact on the optical imaging quality.

[0183] By reasonably selecting the above parameters, when the ratio (R1-R2) / (R1+R2) satisfies the above relationship, on the one hand, the deflection angle of the light rays at the edge of the second lens L2 can be effectively controlled, that is, the light rays at the circumference of the second lens L2 will not deflect too much towards the optical axis or the edge, so that the light rays at the circumference of the second lens L2 are relatively flat, and the beam diameter can be effectively controlled, thus effectively controlling the size of the second lens L2 in the direction perpendicular to the optical axis, thereby shortening the size of the optical lens in the direction perpendicular to the optical axis; on the other hand, the thickness of the second lens L2 will not be too thin, making it easier to process.

[0184] In summary, when the optical lens of this application focuses within a depth-of-field range of 2mm-100mm, the total optical length of the optical lens is controlled between 7.72mm and 9.11mm, indicating a relatively small size. The image height is greater than 0.8mm, indicating high resolution; the field of view can reach 135°~160°; and simulation diagrams from various embodiments show that the optical lens of this application achieves a balance between a large field of view, high image quality, and miniaturization within a depth-of-field range of 2mm-100mm. When used as an endoscope objective, an endoscope incorporating the optical lens of this application can be used for colonoscopy and gastroscopy.

[0185] This application also provides an endoscope, including the camera module from any of the above embodiments. The beneficial effects achieved by this endoscope are the same as those of the camera module in the above embodiments, and will not be repeated here.

[0186] This application also provides an endoscope system, including a light source host, an image processing device, and an endoscope.

[0187] The aforementioned image processing device is communicatively connected to the light source host, and the light source host is detachably connected to the endoscope. For example, the light source host and the endoscope can be plugged in and disconnected.

[0188] When the light source host and the image processing device are integrated into one device, there is no concept of a corresponding connection.

[0189] The endoscope system also includes a display that communicates with the image processing equipment. The display can be set up as a standalone device or integrated into the image processing equipment; no specific limitation is made here.

[0190] The beneficial effects achieved by this endoscope system are the same as those of the endoscope in the above embodiments, and will not be repeated here.

[0191] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An optical lens characterized in that, It consists of a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens arranged from the object side to the image side; The first lens has negative optical power, and the fourth lens has positive optical power; the object-side surface of the first lens is flat along the optical axis, and the image-side surface is convex to the object side along the optical axis; the object-side surface of the second lens is convex to the image side along the optical axis; the object-side surface of the third lens is convex to the object side along the optical axis, and the image-side surface is convex to the object side along the optical axis; the object-side surface of the fourth lens is convex to the object side along the optical axis, and the image-side surface is convex to the image side along the optical axis; the image-side surface of the sixth lens is convex to the image side along the optical axis. The third lens can move along the optical axis of the optical lens to enable the optical lens to focus between the telephoto and near-photo areas, so that the optical lens can image within a depth of field range of 2mm-100mm. The fifth lens and the sixth lens form a cemented lens, and the cemented lens has positive optical power; The focal length f1 of the first lens and the focal length f2 of the second lens of the optical lens satisfy the following relationship: 0.1 <f2 / f1<0.4; The focal length f4 of the fourth lens of the optical lens and the focal length f2 of the second lens satisfy the relationship: -0.5 <f4 / f2<-0.1; The focal length f3 of the third lens and the effective focal length f of the optical lens at the telephoto position satisfy the following relationship: 2 <f3 / f<8。 2. The optical lens according to claim 1, characterized in that: The combined focal length fm of the cemented lens and the focal length f4 of the fourth lens satisfy the following relationship: 0 <f4 / fm<0.5; And / or, the combined focal length fm of the cemented lens and the effective focal length f of the optical lens at the telephoto position satisfy the following relationship: 2 <fm / f<50。 3. The optical lens according to any one of claims 1-2, characterized in that, The radius of curvature R1 of the object side of the second lens and the radius of curvature R2 of the image side of the second lens satisfy the following relationship: -1 < (R1-R2) / (R1+R2) < 3.

4. The optical lens according to any one of claims 1-2, wherein, The optical lens also includes an aperture stop, which is located between the third lens and the fourth lens.

5. A camera module, comprising: include: The optical lens according to any one of claims 1-4; as well as A photosensitive element is disposed on the image side of the optical lens.

6. The camera module of claim 5, wherein, A filter is also provided between the photosensitive element and the optical lens.

7. An endoscope, characterized in that, include: The camera module as described in claim 5 or 6.

8. An endoscope system, characterized in that, include: The light source host, the image processing device, and the endoscope as described in claim 7.

Images