Optical lens, camera module, endoscope and endoscope system

Abstract

The invention 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 which are arranged from an object side to an image side; the first lens has negative focal power, the second lens has negative focal power, the third lens has positive focal power, and the fourth lens has positive focal power; the third lens can move along the optical axis of the optical lens, so that the optical lens performs focusing between a far focus position and a near focus position; the focal length f4 of the fourth lens of the optical lens and the focal length f2 of the second lens of the optical lens meet the relational expression:-0.5 lt; f4 / f2lt; and-0.1. The optical lens achieves the purposes of large field angle, high image quality and miniaturization within the field depth range of 2mm-100mm.

Description

Technical Field

[0001] The present 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 Art

[0002] An electronic endoscope is a device that can be inserted into the human body, allowing doctors to directly observe the changes in the tissue morphology and pathological changes of the human body cavity and internal organs, and use the electronic endoscope to make accurate diagnosis of diseases. Currently, electronic endoscopes are widely used in various fields of clinical medicine, especially in the diagnosis of uterine cavity diseases, playing an irreplaceable role.

[0003] Camera modules, such as endoscope objective lenses, are usually used in conjunction with endoscopes to transmit images detected by the endoscope to detectors for better observation. They are commonly used in modern medical minimally invasive surgery and gastrointestinal examination and treatment.

[0004] In order to make precise diagnosis of lesions, the endoscope is expected to have a higher resolution, which will help doctors better judge the lesions and improve the efficiency of diagnosis. At the same time, the endoscope is also expected to be smaller, that is, the aperture of the endoscope objective lens is controlled to be smaller, which has obvious advantages in the field of minimally invasive diagnosis without anesthesia. How to develop an optical lens with a large field of view, high image quality and miniaturization has become an important topic in the industry. Summary of the invention

[0005] Embodiments of the present application provide an optical lens, a camera module, an endoscope, and an endoscope system with a large field of view, high image quality, and miniaturization.

[0006] In a first aspect, an embodiment of the present 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 a negative optical focal length, the second lens has a negative optical focal length, the third lens has a positive optical focal length, and the fourth lens has a positive optical focal length; the third lens can move along the optical axis of the optical lens so that the optical lens can be focused 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。

[0007] The beneficial effect of the optical lens provided by the embodiment of the present application is that: by reasonably allocating the focal power of the optical lens, the focal power of the first lens and the second lens are both negative, and when the light passes through each lens group of the optical lens, the light first diverges twice and then converges twice, so that the light transition is relatively smooth, which not only reduces the aberration, improves the field of view and resolution, thereby improving the imaging quality, but also helps to reduce the aperture of the optical lens. In addition, when the optical lens satisfies the above relationship, not only the aberration of the optical lens is well corrected, but also it helps to reduce the total optical length of the optical lens, so that the optical lens can achieve the purpose of taking into account a large field of view, high image quality and miniaturization within the depth of field.

[0008] In some embodiments, the fifth lens and the sixth lens form a cemented lens.

[0009] Through the above arrangement, not only can the light passing through the optical lens be smoother, the tolerance sensitivity is reduced, thereby further improving the imaging quality, but also the assembly of the optical lens is facilitated.

[0010] In some embodiments, the cemented lens has positive optical power.

[0011] Through the above arrangement, the cemented lens can well balance the first lens and the second lens, so that the light transition is smoother, which not only further reduces the aberration, but also reduces the tolerance sensitivity, thereby further improving the imaging quality.

[0012] In some embodiments, the combined focal length fm of the cemented lens and the focal length f4 of the fourth lens satisfy the relationship: <f4 / fm<0.5。

[0013] By making reasonable selection, when the optical lens satisfies the above relationship, it is not only beneficial to correct the aberration of the optical lens and improve the imaging quality, but also shorten the overall length of the optical lens.

[0014] In some embodiments, the combined focal length fm of the cemented lens and the effective focal length f of the optical lens at the far focus satisfy the relationship: <fm / f<50。

[0015] By making reasonable selection, when the optical lens satisfies the above relationship, not only the imaging quality is further improved, but also the length of the optical lens is reduced.

[0016] 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。

[0017] By making reasonable selection, when the optical lens satisfies the above relationship, not only the imaging quality of the optical lens is further improved, but also the diameter of the optical lens is reduced.

[0018] In some embodiments, a curvature radius R1 of an object-side surface of the second lens close to the object side and a curvature radius R2 of an image-side surface close to the image side satisfy the relationship: -1<(R1-R2) / (R1+R2)<3.

[0019] By making reasonable selection, when the optical lens satisfies the above relationship, not only the size of the second lens in the direction perpendicular to the optical axis is 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 is not too thin, and it is easy to process.

[0020] In some embodiments, the focal length f3 of the third lens and the effective focal length f of the optical lens at the far focus satisfy the relationship: <f3 / f<8。

[0021] By making reasonable selection, when the optical lens satisfies the above relationship, the aberrations of the third lens and the remaining lenses cancel each other out, thereby 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.

[0022] In some embodiments, the optical lens further includes a stop, and the stop is located between the third lens and the fourth lens.

[0023] Through the above arrangement, the optical lens structure is further made symmetrical, and it is beneficial to take into account both imaging quality and aperture size.

[0024] In a second aspect, an embodiment of the present application further provides a camera module, comprising the optical lens and a photosensitive element as described in the first aspect above, wherein the photosensitive element is arranged on the image side of the optical lens.

[0025] The camera module in the embodiment of the present application has the same technical effect as that achieved by the optical lens in the first aspect, which will not be described in detail here.

[0026] In some embodiments, the optical lens further includes a filter.

[0027] In some embodiments, the filter is an infrared cutoff filter.

[0028] Through the above arrangement, the interference of infrared rays during the imaging process of the optical lens can be reduced, thereby further improving the imaging quality of the optical lens.

[0029] In some embodiments, the filter is provided with a laser cut-off film.

[0030] Through the above arrangement, the optical lens can be suitable for laser treatment.

[0031] In some embodiments, a protective sheet is provided on the photosensitive element.

[0032] Through the above arrangement, the photosensitive element can be well protected.

[0033] In a third aspect, an embodiment of the present application further provides an endoscope, comprising the camera module described in the second aspect above.

[0034] The technical effects achieved by the endoscope in the embodiment of the present application are the same as those achieved by the camera module in the second aspect, which will not be repeated here.

[0035] In a fourth aspect, an embodiment of the present application further provides an endoscope system, comprising a light source host, an image processing device, and the endoscope described in the third aspect above.

[0036] The camera module in the embodiment of the present application has the same technical effect as that achieved by the endoscope in the third aspect, which will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0038] Figure 1 The optical path diagram of the structure of the optical lens at the far focus position in the first embodiment of the present application;

[0039] Figure 2 A magnification spherical aberration diagram of the optical lens at far focus in Example 1 of the present application;

[0040] Figure 3 A spherical aberration diagram of the optical lens at far focus in Example 1 of the present application;

[0041] Figure 4 The astigmatism diagram of the optical lens at far focus in the first embodiment of the present application;

[0042] Figure 5 This is a distortion diagram of the optical lens at a far focus in Example 1 of the present application;

[0043] Figure 6 This is a structural light path diagram of the optical lens at near focus in Example 1 of the present application;

[0044] Figure 7A magnification spherical aberration diagram of the optical lens at near focus in Example 1 of the present application;

[0045] Figure 8 A spherical aberration diagram of the optical lens at near focus in Example 1 of the present application;

[0046] Fig. 9 The astigmatism diagram of the optical lens in the first embodiment of the present application at the near focus position;

[0047] Fig.10 This is a distortion diagram of the optical lens in Example 1 of the present application at a near focus position;

[0048] Fig.11 It is a schematic diagram of the structure of the optical lens in the second embodiment of the present application at a far focus position;

[0049] Fig.12 A magnification spherical aberration diagram of the optical lens at far focus in the second embodiment of the present application;

[0050] Fig.13 A spherical aberration diagram of the optical lens at far focus in the second embodiment of the present application;

[0051] Fig.14 The astigmatism diagram of the optical lens at far focus in the second embodiment of the present application;

[0052] Fig.15 This is a distortion diagram of the optical lens at far focus in the second embodiment of the present application;

[0053] Fig.16 It is a schematic diagram of the structure of the optical lens in the second embodiment of the present application at a near focus position;

[0054] Fig.17 A magnification spherical aberration diagram of the optical lens at near focus in Example 2 of the present application;

[0055] Fig.18 A spherical aberration diagram of the optical lens at near focus in the second embodiment of the present application;

[0056] Fig.19 The astigmatism diagram of the optical lens in the second embodiment of the present application at the near focus position;

[0057] Fig. 20 This is a distortion diagram of the optical lens in the second embodiment of the present application at a near focus position;

[0058] Fig.21 It is a schematic diagram of the structure of the optical lens in the third embodiment of the present application at a far focus position;

[0059] Fig. 22 A magnification spherical aberration diagram of the optical lens at far focus in Example 3 of the present application;

[0060] Fig.23 A spherical aberration diagram of the optical lens at far focus in the third embodiment of the present application;

[0061] Fig.24 The astigmatism diagram of the optical lens at far focus in the third embodiment of the present application;

[0062] Fig.25 This is a distortion diagram of the optical lens at far focus in the third embodiment of the present application;

[0063] Fig.26 This is a schematic diagram of the structure of the optical lens in the third embodiment of the present application at a near focus position;

[0064] Fig. 27 A magnification spherical aberration diagram of the optical lens at near focus in Example 3 of the present application;

[0065] Fig.28 This is a spherical aberration diagram of the optical lens at near focus in Example 3 of the present application;

[0066] Fig.29 This is an astigmatism diagram of the optical lens at near focus in Example 3 of the present application;

[0067] Fig.30 This is a distortion diagram of the optical lens at near focus in Example 3 of the present application;

[0068] Fig.31 It is a schematic diagram of the structure of the optical lens in the fourth embodiment of the present application at a far focus position;

[0069] Fig.32 A magnification spherical aberration diagram of the optical lens at far focus in the fourth embodiment of the present application;

[0070] Fig.33 A spherical aberration diagram of the optical lens at far focus in the fourth embodiment of the present application;

[0071] Fig.34 The astigmatism diagram of the optical lens at far focus in the fourth embodiment of the present application;

[0072] Fig.35 This is a distortion diagram of the optical lens at far focus in the fourth embodiment of the present application;

[0073] Fig.36 This is a schematic diagram of the structure of the optical lens in the fourth embodiment of the present application at a near focus position;

[0074] Fig.37 A magnification spherical aberration diagram of the optical lens in the fourth embodiment of the present application at a near focus position;

[0075] Fig.38 This is a spherical aberration diagram of the optical lens at near focus in the fourth embodiment of the present application;

[0076] Fig.39 This is an astigmatism diagram of the optical lens at near focus in the fourth embodiment of the present application;

[0077] Fig.40 This is a distortion diagram of the optical lens in the fourth embodiment of the present application at a near focus position;

[0078] Fig.41 It is a schematic diagram of the structure of the optical lens in the fifth embodiment of the present application at a far focus position;

[0079] Fig.42 A magnification spherical aberration diagram of the optical lens at far focus in Example 5 of the present application;

[0080] Fig.43 A spherical aberration diagram of the optical lens at far focus in Example 5 of the present application;

[0081] Fig.44 The astigmatism diagram of the optical lens in Example 5 of the present application at far focus;

[0082] Fig.45 This is a distortion diagram of the optical lens at far focus in Example 5 of the present application;

[0083] Fig.46 This is a schematic diagram of the structure of the optical lens in the fifth embodiment of the present application at a near focus position;

[0084] Fig.47 A magnification spherical aberration diagram of the optical lens in Example 5 of the present application at near focus;

[0085] Fig.48 This is a spherical aberration diagram of the optical lens at near focus in Example 5 of the present application;

[0086] Fig.49 This is an astigmatism diagram of the optical lens in Example 5 of the present application at a near focus position;

[0087] Fig.50 This is a distortion diagram of the optical lens in Example 5 of the present application at a near focus position;

[0088] Fig.51 It is a schematic diagram of the structure of the optical lens in the sixth embodiment of the present application at a far focus position;

[0089] Fig.52 A magnification spherical aberration diagram of the optical lens at far focus in Example 6 of the present application;

[0090] Fig.53 A spherical aberration diagram of the optical lens at far focus in Example 6 of the present application;

[0091] Fig.54 The astigmatism diagram of the optical lens at far focus in Example 6 of the present application;

[0092] Fig.55 This is a distortion diagram of the optical lens at far focus in Example 6 of the present application;

[0093] Fig.56 It is a schematic diagram of the structure of the optical lens in the sixth embodiment of the present application at a near focus position;

[0094] Fig.57 A magnification spherical aberration diagram of the optical lens in Example 6 of the present application at near focus;

[0095] Fig.58 This is a spherical aberration diagram of the optical lens at near focus in Example 6 of the present application;

[0096] Fig.59 This is an astigmatism diagram of the optical lens at near focus in Example 6 of the present application;

[0097] Fig.60 This is a distortion diagram of the optical lens at near focus in Example 6 of the present application;

[0098] Fig.61 Schematic diagram of the structure of the optical lens at the far focus position in the seventh embodiment of the present application;

[0099] Fig.62 A magnification spherical aberration diagram of the optical lens at far focus in Example 7 of the present application;

[0100] Fig.63 This is a spherical aberration diagram of the optical lens at far focus in Example 7 of the present application;

[0101] Fig.64 The astigmatism diagram of the optical lens at far focus in the seventh embodiment of the present application;

[0102] Fig.65 This is a distortion diagram of the optical lens at far focus in Example 7 of the present application;

[0103] Fig.66 Schematic diagram of the structure of the optical lens in the seventh embodiment of the present application at a near focus position;

[0104] Fig.67 A magnification spherical aberration diagram of the optical lens in Example 7 of the present application at near focus;

[0105] Fig.68 This is a spherical aberration diagram of the optical lens at near focus in Example 7 of the present application;

[0106] Fig.69 This is an astigmatism diagram of the optical lens in Example 7 of the present application at a near focus position;

[0107] Fig.70This is a distortion diagram of the optical lens in Example 7 of the present application at near focus.

[0108] Among them, the reference numerals in the figure are:

[0109] The first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the filter L7, the protective sheet L8, and the aperture STO. DETAILED DESCRIPTION

[0110] For ease of understanding, the English abbreviations and related technical terms involved in the embodiments of the present application are explained and described below.

[0111] Focal power is equal to the difference between the convergence of the image-side light beam and the convergence of the object-side light beam. It characterizes the ability of an optical lens to deflect light.

[0112] A lens or lens group with positive optical power has a positive focal length and has the effect of converging light.

[0113] A lens or lens group with negative optical power has a negative focal length and has the effect of diverging light.

[0114] Focal length F, also known as focal length, is a measure of the convergence or divergence of light in an optical lens. It refers to the vertical distance from the optical center of a lens or lens group to the focal plane when an infinitely distant scene forms a clear image on the focal plane through the lens or lens group. From a practical point of view, it can be understood as the distance from the center of the lens to the plane when the object is infinitely far away. For a fixed-focus lens, the position of its optical center is fixed; for a telephoto lens, the change of the optical center of the lens brings about a change in the focal length of the lens.

[0115] Back focal length FBL is the length from the rear end of the optical lens to the imaging plane.

[0116] The total optical length TTL (Total Track Length) refers to the distance from the center of the lens to the focus of light gathering, that is, in the module, the distance from the center of the lens to the imaging plane of the sensor surface.

[0117] The object side is bounded by the lens. The side where the object is located is called the object side, and the surface of the lens close to the object side is called the object side.

[0118] The image side is bounded by the lens. The side where the image of the object is located is called the image side, and the surface of the lens close to the image side is called the image side.

[0119] The aperture (aperture diaphragm) is a device used to control the amount of light that passes through the lens and enters the photosensitive surface inside the camera body. It is usually inside the lens.

[0120] Aperture number, also known as F number (FNO), is a relative value obtained by dividing the focal length of the lens by the diameter of the lens entrance pupil (the inverse of the relative aperture). The smaller the aperture value, the more light enters in the same unit time. The larger the aperture value, the smaller the depth of field, and the background content of the photo will be blurred, similar to the effect of a telephoto lens.

[0121] Total track length (TTL) refers to the total length from the surface of the lens closest to the object side to the imaging surface. TTL is the main factor affecting the height of the camera.

[0122] The imaging plane is located on the image side of all lenses in the optical lens and is the plane on which the image is formed after light passes through each lens in the optical lens.

[0123] The optical axis is an axis that passes vertically through the center of the lens. The optical axis of the lens is the axis that passes through the center of each lens of the lens. When light parallel to the optical axis enters a convex lens, the ideal convex lens should have all the light converge at one point behind the lens. This point where all the light converges is the focus.

[0124] Focus is the point where parallel light rays converge after being refracted by a lens or lens group.

[0125] Aberration: An optical lens has the properties of an ideal optical system at the optical axis. The near-axis light emitted from a point on the object intersects the image plane at one point (also known as the optical axis image point). However, the light rays that actually pass through the lens with different apertures are difficult to intersect perfectly at one point, but have a certain deviation from the position of the near-axis image point. These differences are collectively called aberrations.

[0126] Spherical aberration, generally speaking, when light from a spherical lens enters the lens and reaches the focal plane, it is more likely to be severely refracted and bent at the edge than at the center. This phenomenon will lead to a decrease in sharpness and contrast, the generation of light spots, and the image quality will be reduced. The larger the aperture, the more serious the problem. Therefore, this situation can be improved by closing the aperture, but it cannot be completely eliminated. This aberration caused by a spherical lens is called spherical aberration.

[0127] Distortion, also known as distortion, is the degree of distortion of the image formed by an optical lens relative to the object itself. Distortion is due to the influence of aperture spherical aberration. The height of the intersection of the main light of different fields of view with the Gaussian image plane after passing through the optical lens is not equal to the ideal image height. The difference between the two is the distortion. Therefore, distortion only changes the imaging position of the off-axis object point on the ideal plane, causing the shape of the image to be distorted, but does not affect the clarity of the image.

[0128] Astigmatism, because the object point is not on the optical axis of the optical lens, the light beam it emits has an inclination angle with the optical axis. After the light beam is refracted by the lens, the convergence point of its meridional beamlet and sagittal beamlet is not at the same point. That is, the light beam cannot be focused on one point, and the image is not clear, so astigmatism occurs. Meridian beamlet and sagittal beamlet are the names of light beams in two vertical planes in a rotationally symmetric optical lens.

[0129] Meridian plane: The plane formed by the chief ray (chief light beam) of an object point outside the optical axis and the optical axis is called the meridian plane.

[0130] Sagittal plane: The plane that passes through the main ray (main light beam) of the object point outside the optical axis and is perpendicular to the meridian plane is called the sagittal plane.

[0131] Field curvature is used to indicate the difference between the clearest image point position of the non-central field of view light after passing through the optical lens group and the clearest image point position of the central field of view on the optical axis. When the lens has field curvature, the intersection point of the entire light beam does not coincide with the ideal image point. Although a clear image point can be obtained at each specific point, the entire image plane is a curved surface.

[0132] Chromatic aberration of magnification is a type of chromatic aberration caused by the difference in image size due to the different heights (i.e. magnification) of images of different colors of light.

[0133] Cemented lenses, also known as cemented lenses, refer to combined lenses composed of two or more lenses that are glued together. The tolerance sensitivity of cemented lenses is better than that of single lenses. When used in endoscope products, it is more conducive to the assembly of lens structures and can improve the imaging quality of endoscopes.

[0134] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0135] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0136] An electronic endoscope is a device that can be inserted into the human body, allowing doctors to directly observe the changes in the tissue morphology and pathological changes of the human body cavity and internal organs, and use the electronic endoscope to make accurate diagnosis of diseases. Currently, electronic endoscopes are widely used in various fields of clinical medicine, especially in the diagnosis of uterine cavity diseases, playing an irreplaceable role.

[0137] Camera modules, such as endoscope objective lenses, are usually used in conjunction with endoscopes to transmit images detected by the endoscope to detectors for better observation. They are commonly used in modern medical minimally invasive surgery and gastrointestinal examination and treatment.

[0138] In order to make precise diagnosis of lesions, it is expected that endoscopes have good imaging quality, which will help doctors better judge lesions and improve diagnostic efficiency. At the same time, it is also expected that endoscopes have a wider field of view to increase doctors' observation range and help shorten inspection time. How to develop an optical lens with a large field of view, high image quality and miniaturization has become an important issue in the industry.

[0139] In order to solve the above technical problems, an embodiment of the present application provides an optical lens and a camera module.

[0140] like Figure 1 As shown, the camera module includes an optical lens and a photosensitive element ( Figure 1 IMAGE in the image), the photosensitive element is located on the image side of the optical lens.

[0141] The working principle of the camera module is as follows: the light reflected by the photographed scene generates an optical image through the optical lens and is projected onto the photosensitive surface of the photosensitive element. The photosensitive element converts the optical image into an electrical signal, namely an analog image signal, and transmits it to the processor.

[0142] Among them, the photosensitive element (also called image sensor) is a semiconductor chip with hundreds of thousands to millions of photodiodes on its surface. When exposed to light, it will generate electric charge. The photosensitive element can be a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS). CCD is made of a highly sensitive semiconductor material that can convert light into electric charge. Charge coupled devices are composed of many photosensitive units, usually in units of millions of pixels. When the surface of the photosensitive element is exposed to light, each photosensitive unit will reflect the charge on the component, and the signals generated by all the photosensitive units are added together to form a complete picture.

[0143] Among them, the optical lens mainly uses the refraction principle of the lens to form an image, that is, the light of the scene passes through the optical lens to form a clear image on the focal plane, and the image of the scene is recorded by the photosensitive element located on the focal plane.

[0144] The camera module can be used in electronic devices with camera functions. For example, the camera module can be used as an endoscope with a camera function, and the optical lens can be used as an endoscope objective lens. Of course, the electronic device can be other electronic devices with a camera function in addition to an endoscope with a camera function, which is not specifically limited here.

[0145] like Figure 1 As shown, an embodiment of the present 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 a negative optical power, the second lens has a negative optical power, the third lens has a positive optical power, and the fourth lens has a positive optical power; the third lens can move along the optical axis of the optical lens so that the optical lens can be focused between a far focus and a near focus.

[0146] By reasonably distributing the focal length of the optical lens, the focal length of the first lens and the second lens are both negative. When the light passes through the lens groups of the optical lens, the light first diverges twice and then converges twice. In this way, the light transition is smoother, which not only reduces the aberration, increases the field of view and resolution, thereby improving the imaging quality, but also helps to reduce the aperture of the optical lens.

[0147] like Figure 1 As shown, in some embodiments, the optical lens also includes a filter L7.

[0148] Through the above method, the optical lens can have the function of cutting in and out of a certain filter in the optical path, that is, the function of the filter blocking light and not blocking light, thereby diversifying the functions of the optical lens, achieving specific optical requirements, reducing the number of parts, and simplifying the assembly process of the optical lens. For example, the cold light source optical path of a medical endoscope can change the bandwidth of a certain monochromatic light in the optical path without replacing the light-emitting component, thereby realizing the need to select the illumination working mode of light sources with different wavelengths.

[0149] The above filter is an infrared cut-off filter, which can reduce the interference of infrared rays in the imaging process of the optical lens, thereby further improving the imaging quality of the optical lens.

[0150] The above-mentioned infrared cut-off film is the abbreviation of infrared cut-off filter (also called infrared filter or heat-absorbing filter), which is a filter used to filter infrared bands. For example, when installed on equipment with incandescent lamps (such as slides, 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 rays from passing through the camera lens and causing image distortion.

[0151] In some embodiments, the filter is provided with a laser cut-off film (not shown in the figure).

[0152] By providing a laser cut-off film on the filter, the optical lens can be suitable for laser therapy.

[0153] The laser cutoff film may be a functional film such as a YAG laser cutoff film or a LD laser cutoff film. The laser cutoff film may be provided on one side of the filter or on both sides of the filter, and no specific limitation is made here.

[0154] like Figure 1 As shown, in some embodiments, a protective sheet L8 is also provided on the photosensitive element. In this way, it can not only protect the photosensitive element, but also play the role of supporting the photosensitive element, which is convenient for installation.

[0155] like Figure 1 and Figure 6 The optical lens of the first embodiment of the present invention is shown in the structure light path diagram at the far focus and near focus. The optical lens includes a lens arranged from the object side to the image side (such as Figure 1 The first lens L1, the second lens L2, the third lens L3, the aperture STO, the fourth lens L4, the fifth lens L5 and the sixth lens L6 are arranged from left to right as shown in the figure, and the fifth lens L5 and the sixth lens L6 form a cemented lens. Specifically, the optical power of each lens is shown in the following Table 1b.

[0156] The fourth lens L4 can move along the optical axis of the optical lens so that the optical lens can form an image between a far focus and a near focus.

[0157] As an optional embodiment of the present application, based on the first embodiment of the present application, the parameter values ​​of each lens of the optical lens can refer to Table 1a to Table 1d.

[0158] Table 1a

[0159] Surface number Surface type R-Value Thickness(mm) Refractive Index Abbe number OBJ Standard Infinity 15.0(4.00) S1 Standard Infinity 0.405 1.88 42.0 S2 Standard 1.25 0.935 S3 Standard -1.33 0.754 1.50 85.6 S4 Standard -3.16 0.207(0.384) S5 Standard 1.42 0.797 1.76 40.1 S6 Standard 2.05 0.537(0.360) STO Standard Infinity 0.266 S8 Standard 2.04 0.801 1.59 58.3 S9 Standard -1.88 0.395 S10 Standard -17.67 0.757 1.64 60.2 S11 Standard -0.94 0.575 1.85 23.8 S12 Standard -2.99 0.621 S13 Standard Infinity 0.650 1.52 64.2 S14 Standard Infinity 0.350 1.52 64.2 IMAGE Standard Infinity /

[0160] It should be noted that, in Table 1a, “Surface Number” is 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 with the corresponding surface number, that is, the radius of curvature of the object side or image side of the lens corresponding to each surface number at the optical axis, and the “infinity” of the lens in the “radius of curvature” parameter series means that the object side or image side of the lens is a plane; the value of each lens in the “Thickness / Spacing” parameter series is the thickness of the lens on the optical axis, or the distance from the image side of the lens to the object side of the next lens on the optical axis; the value of the aperture STO in the “Thickness” parameter series is the distance from the center of the aperture STO to the object side of the next lens on the optical axis.

[0161] "OBJ" refers to the object plane. The two values ​​inside and outside the brackets of "OBJ" in the "Thickness" parameter column refer to two different object distances of the optical lens. The value of "S4" in the "Thickness" parameter column represents the distance between the image side of the second lens L2 and the image side of the third lens L3. The value of "S6" in the "Thickness" parameter column represents the distance between the image side of the third lens L3 and the aperture STO.

[0162] Under different object distance focusing, the second lens L2 and the third lens L3, as well as the third lens L3 and the aperture STO are different. Figure 1 , Figure 6 As shown in Table 1a, for the optical lens in this embodiment, when the object distance is 15 mm, the distance between the image side surface of the second lens L2 and the image side surface of the third lens L3 is 0.207 mm, and the distance between the image side surface of the third lens L3 and the stop STO is 0.537 mm. When the object distance is 4 mm, the distance between the image side surface of the second lens L2 and the image side surface of the third lens L3 is 0.384 mm, and the distance between the image side surface of the third lens L3 and the stop STO is 0.360 mm.

[0163] In the embodiment of the present application, when the optical lens focuses and images in the depth of field range of 2mm-100mm, the total optical length L is 8.10mm; the image height is 0.8mm; and the field angle is 135°. The focal length f of the optical lens in this embodiment is 0.86mm at the far focus point; and the focal length f is 0.84mm at the near focus point.

[0164] It should be noted that the depth of field of the optical lens in this embodiment at the far focus is in the range of 5mm-100mm, and the depth of field at the near focus is in the range of 2mm-6mm. In addition, regarding the field of view angle, the field of view angle of the optical lens in this embodiment at the far focus is the same as that at the near focus. Of course, the field of view angle of the optical lens at the far focus and the near focus may also be different. Usually, the field of view angle at the near focus may be slightly smaller than the field of view angle at the far focus. When making a specific selection, it is determined in combination with other optical parameters of the optical lens, and is not specifically limited here.

[0165] The positive and negative conditions of the focal length of each lens in the optical lens of this embodiment are shown in Table 1b.

[0166] Table 1b

[0167] lens L1 L2 L3 L4 L5 L6 Optical power - - + + + -

[0168] It should be noted that the "+" and "-" in Table 1b represent the positive and negative conditions of the focal length of each lens in the optical lens in Example 1. Among them, "+" represents that the lens has a positive focal length, and "-" represents that the lens has a negative focal length.

[0169] The concave-convex condition of the object side or image side of each lens in the optical lens of Example 1 at the optical axis is shown in Table 1c.

[0170] Table 1c

[0171] lens L1 L2 L3 L4 L5 L6 Concave and convex situation ∞+ -- ++ +- -- --

[0172] It should be noted that the "∞+", "--", "++", and "+-" in Table 1d represent the concave-convex situation of the object side or image side of each lens at the optical axis. Among them, "∞+" represents that the object side of the lens is flat at the optical axis, and the image side is convex toward the object at the optical axis; "--" represents that both the object side and the image side of the lens are concave toward the object at the optical axis; "++" represents that both the object side and the image side of the lens are convex toward the object at the optical axis; "+-" represents that the object side of the lens is convex toward the object at the optical axis, and the image side is convex toward the object at the optical axis, that is, a double convex crescent structure. Of course, in addition to those shown in the table, the concave and convex conditions also include "-+", "+∞", "-∞", "∞-", etc., among which, "-+" represents that the object side of the lens is concave toward the object side at the optical axis, and the image side is convex toward the object side at the optical axis, that is, a double concave structure; "+∞" represents that the object side of the lens is convex toward the object side at the optical axis, and the image side is a plane at the optical axis; "-∞" represents that the object side of the lens is concave toward the object side at the optical axis, and the image side is a plane at the optical axis; "∞-" represents that the object side of the lens is a plane at the optical axis, and the image side is concave toward the object side at the optical axis.

[0173] Combination Figure 1 and Figure 6The structural schematic diagram and optical path diagram of the optical lens in the first embodiment shown in FIG. 1 , and the main parameters of the optical lens in the first embodiment given in Tables 1a to 1c are obtained through simulation. Figures 2 to 5 , Figures 6 to 10 The simulation diagram shown. Figures 2 to 5 The diagrams respectively show the magnification chromatic aberration diagram, spherical aberration diagram, astigmatism diagram and distortion diagram of the optical lens in the first embodiment at the far focus; Figures 7 to 10 The diagrams respectively show the magnification chromatic aberration diagram, spherical aberration diagram, astigmatism diagram and distortion diagram of the optical lens in the first embodiment at near focus.

[0174] in, Figure 2 and Figure 7 In the magnification chromatic aberration diagram shown, the horizontal axis is the vertical position of light of different wavelengths on the image plane of the photosensitive element, and the vertical axis is the field angle.

[0175] Figure 3 and Figure 8 The horizontal axis in the spherical aberration diagram shown is the axial position of light of different wavelengths on the image plane of the photosensitive element, in mm; the vertical axis is the normalized entrance pupil coordinate (note: no unit).

[0176] Figure 4 and Fig. 9 The horizontal axis in the astigmatism diagram shown is the vertical position of light of different wavelengths on the image plane of the photosensitive element, in mm; the vertical axis is the field angle.

[0177] Figure 5 and Fig.10 The horizontal axis in the distortion diagram shown is the distortion value, and the vertical axis is the field of view angle.

[0178] The above descriptions about the magnification chromatic aberration diagram, the spherical aberration diagram, the astigmatism diagram and the distortion diagram are the same as those in other embodiments and will not be repeated hereinbelow.

[0179] from Figure 2 and Figure 7 As can be seen from the figure, as the field of view increases, the vertical chromatic aberration of the optical lens gradually increases, but the vertical axis chromatic aberration can be controlled within the deviation allowed by the diffraction limit, making the chromatic aberration smaller and improving the imaging quality. Figure 3 and Figure 8 It can be seen that the axial value range of different wavelengths is controlled within the range of ±0.05mm, and the chromatic aberration is good in the entire entrance pupil range. Therefore, the axial point chromatic aberration of this optical lens is good. Figure 4 and Fig. 9 It can be seen that the astigmatism value of the optical lens is controlled between -0.01 and 0.05. As the field of view increases, the astigmatism of the system gradually increases, but the astigmatism value can be controlled within the range of ±0.05mm, and the image quality of the optical lens is good. Figure 5 and Fig.10 It can be seen that as the field of view increases, the distortion of the optical lens gradually increases, but the distortion value can be controlled within 80%, reducing the impact of image distortion on image quality. This shows that the imaging quality of the optical lens is good.

[0180] Fig.11 and Fig.16 The structure of the optical lens of the second embodiment at the far focus and near focus is shown. The structure of the optical lens of the second embodiment is mainly different from that of the optical lens of the first embodiment in terms of the parameters of each lens, the relationship they satisfy, the focal power, and the concave-convex condition at the optical axis.

[0181] As an optional embodiment of the present application, based on the second embodiment of the present application, the parameter values ​​of each lens of the optical lens can refer to Table 2a to Table 2c.

[0182] Table 2a

[0183] Surface number Surface type R-Value Thickness(mm) Refractive Index Abbe number OBJ Standard Infinity 15.0(4.00) S1 Standard Infinity 0.450 1.87 41.8 S2 Standard 1.14 0.747 S3 Standard -1.25 0.750 1.49 83.5 S4 Standard -2.83 0.200(0.376) S5 Standard 1.50 0.800 1.77 42.1 S6 Standard 2.27 0.536(0.360) STO Standard Infinity 0.200 S8 Standard 2.19 0.800 1.58 68.3 S9 Standard -2.19 0.398 S10 Standard 18.74 0.765 1.64 65.2 S11 Standard -0.95 0.450 1.83 23.8 S12 Standard -2.62 0.813 S13 Standard Infinity 0.650 1.52 64.2 S14 Standard Infinity 0.350 1.52 64.2 IMAGE Standard Infinity /

[0184] In the embodiment of the present application, when the optical lens is focused and imaged at 2mm-100mm, the total optical length L is 7.91mm; the image height is 0.8mm; and the field of view angle is 135°. The focal length f of the optical lens in this embodiment is 0.85mm at the far focus; and the focal length f is 0.83mm at the near focus.

[0185] The positive and negative conditions of the focal length of each lens in the optical lens of this embodiment are shown in Table 2b.

[0186] Table 2b

[0187] lens L1 L2 L3 L4 L5 L6 Optical power - - + + + -

[0188] The concave-convex condition of each lens in the optical lens of this embodiment at the optical axis is shown in Table 2c.

[0189] Table 2c

[0190] lens L1 L2 L3 L4 L5 L6 Concave and convex situation ∞+ -- ++ +- +- --

[0191] Combination Fig.11 and Fig.16 The structural diagram of the optical lens in the second embodiment shown in FIG. 1 and the main parameters of the optical lens in the second embodiment given in Tables 2a to 2c are obtained through simulation. Figures 12 to 20 The simulation diagram shown. Fig.12 and Fig.17 As can be seen from the figure, as the field of view increases, the vertical chromatic aberration of the optical lens gradually increases, but the vertical axis chromatic aberration can be controlled within the deviation allowed by the diffraction limit, making the chromatic aberration smaller and improving the imaging quality. Fig.13 and Fig.18It can be seen that the axial value range of different wavelengths is controlled within the range of ±0.04mm, and the chromatic aberration is good in the entire entrance pupil range. Therefore, the axial point chromatic aberration of this optical lens is good. Fig.14 and Fig.19 It can be seen that the astigmatism value of the optical lens is controlled between -0.02 and 0.05. As the field of view increases, the astigmatism of the system gradually increases, but the astigmatism value can be controlled within the range of ±0.05mm, and the image quality of the optical lens is good. Fig.15 and Fig. 20 It can be seen that as the field of view increases, the distortion of the optical lens gradually increases, but the distortion value can be controlled within 70%, reducing the impact of image distortion on image quality. This shows that the imaging quality of the optical lens is good.

[0192] Fig.21 and Fig.26 The structure of the optical lens of the third embodiment at the far focus and near focus is shown. The structure of the optical lens of the third embodiment is mainly different from that of the optical lens of the first embodiment in terms of the parameters of each lens, the relationship they satisfy, the focal power, and the concave-convex condition at the optical axis.

[0193] As an optional embodiment of the present application, on the basis of Embodiment 3 of the present application, the parameter values ​​of each lens of the optical lens can refer to Table 3a to Table 3c.

[0194] Table 3a

[0195] Surface number Surface type R-Value Thickness(mm) Refractive Index Abbe number OBJ Standard Infinity 15.0(4.00) S1 Standard Infinity 0.450 1.86 42.0 S2 Standard 1.04 1.014 S3 Standard -15.31 0.449 1.52 73.0 S4 Standard 5.00 0.381(0.527) S5 Standard 1.09 0.560 1.75 45.1 S6 Standard 1.43 0.510(0.365) STO Standard Infinity 0.395 S8 Standard 1.86 0.685 1.59 68.3 S9 Standard -1.90 0.396 S10 Standard -178.1 0.769 1.64 60.2 S11 Standard -0.90 0.450 1.85 28.8 S12 Standard -3.33 0.658 S13 Standard Infinity 0.650 1.52 64.2 S14 Standard Infinity 0.350 1.52 64.2 IMAGE Standard Infinity /

[0196] In the embodiment of the present application, when the optical lens is focused and imaged at 2mm-100mm, the total optical length L is 7.72mm; the image height is 0.8mm; and the field of view angle is 135°. The focal length f of the optical lens in this embodiment is 0.85mm at the far focus; and the focal length f is 0.83mm at the near focus.

[0197] The positive and negative conditions of the focal length of each lens in the optical lens of this embodiment are shown in Table 3b.

[0198] Table 3b

[0199] lens L1 L2 L3 L4 L5 L6 Optical power - - + + + -

[0200] The concave-convex condition of each lens in the optical lens of this embodiment at the optical axis is shown in Table 3c.

[0201] Table 3c

[0202] lens L1 L2 L3 L4 L5 L6 Concave and convex situation ∞+ -+ ++ +- -- --

[0203] Combination Fig.21 and Fig.26The structural diagram of the optical lens in the fourth embodiment shown in FIG. 1 and the main parameters of the optical lens in the third embodiment given in Tables 3a to 3c are obtained through simulation. Figures 22 to 30 The simulation diagram shown. Fig. 22 and Fig. 27 As can be seen from the figure, as the field of view increases, the vertical chromatic aberration of the optical lens gradually increases, but the vertical axis chromatic aberration can be controlled within the deviation allowed by the diffraction limit, making the chromatic aberration smaller and improving the imaging quality. Fig.23 and Fig.28 It can be seen that the axial value range of different wavelengths is controlled within the range of ±0.06mm, and the chromatic aberration is good in the entire entrance pupil range. Therefore, the axial point chromatic aberration of this optical lens is good. Fig.24 and Fig.29 It can be seen that the astigmatism value of the optical lens is controlled between -0.01 and 0.06. As the field of view increases, the astigmatism of the system gradually increases, but the astigmatism value can be controlled within the range of ±0.06mm, and the image quality of the optical lens is good. Fig.25 and Fig.30 It can be seen that as the field of view increases, the distortion of the optical lens gradually increases, but the distortion value can be controlled within 70%, reducing the impact of image distortion on image quality. This shows that the imaging quality of the optical lens is good.

[0204] Fig.31 and Fig.36 The structure of the optical lens of the fourth embodiment at the far focus and near focus is shown. The main differences between the structure of the optical lens of the fourth embodiment and the optical lens of the first embodiment are the parameters of each lens, the relationship they satisfy, the focal power, and the concave-convex situation at the optical axis.

[0205] As an optional embodiment of the present application, on the basis of Embodiment 4 of the present application, the parameter values ​​of each lens of the optical lens can refer to Table 4a to Table 4c.

[0206] Table 4a

[0207] Surface number Surface type R-Value Thickness(mm) Refractive Index Abbe number OBJ Standard Infinity 15.0(4.00) S1 Standard Infinity 0.450 1.88 40.1 S2 Standard 1.16 0.900 S3 Standard -1.85 0.750 1.51 86.6 S4 Standard -5.16 0.200(0.353) S5 Standard 1.13 0.651 1.80 49.5 S6 Standard 1.68 0.636(0.483) STO Standard Infinity 0.526 S8 Standard 5.26 0.800 1.59 68.4 S9 Standard -1.41 0.400 S10 Standard 4.15 0.450 1.85 23.8 S11 Standard 1.18 0.800 1.59 68.4 S12 Standard -10.8 0.500 S13 Standard Infinity 0.650 1.52 64.2 S14 Standard Infinity 0.350 1.52 64.2 IMAGE Standard Infinity /

[0208] In the embodiment of the present application, when the optical lens is focused and imaged at 2mm-100mm, the total optical length L is 8.06mm; the image height is 0.81mm; and the field of view is 135°. The focal length f of the optical lens in this embodiment is 0.84mm at the far focus; and the focal length f is 0.82mm at the near focus.

[0209] The positive and negative conditions of the focal length of each lens in the optical lens of this embodiment are shown in Table 4b.

[0210] Table 4b

[0211] lens L1 L2 L3 L4 L5 L6 Optical power - - + + - +

[0212] The concave-convex condition of each lens in the optical lens of this embodiment at the optical axis is shown in Table 4c.

[0213] Table 4c

[0214] lens L1 L2 L3 L4 L5 L6 Concave and convex situation ∞+ -- ++ +- ++ +-

[0215] Combination Fig.31 and Fig.36 The structural diagram of the optical lens in the fourth embodiment shown in FIG. 4 and the main parameters of the optical lens in the fourth embodiment given in Tables 4a to 4c are obtained through simulation. Figures 32 to 40 The simulation diagram shown. Fig.32 and Fig.37 As can be seen from the figure, as the field of view increases, the vertical chromatic aberration of the optical lens gradually increases, but the vertical axis chromatic aberration can be controlled within the deviation allowed by the diffraction limit, making the chromatic aberration smaller and improving the imaging quality. Fig.33 and Fig.38 It can be seen that the axial value range of different wavelengths is controlled within the range of ±0.05mm, and the chromatic aberration is good in the entire entrance pupil range. Therefore, the axial point chromatic aberration of this optical lens is good. Fig.34 and Fig.39 It can be seen that the astigmatism value of the optical lens is controlled between 0.01 and 0.06. As the field of view increases, the astigmatism of the system gradually increases, but the astigmatism value can be controlled within the range of ±0.06mm, and the image quality of the optical lens is good. Fig.35 and Fig.40 It can be seen that as the field of view increases, the distortion of the optical lens gradually increases, but the distortion value can be controlled within 70%, reducing the impact of image distortion on image quality. This shows that the imaging quality of the optical lens is good.

[0216] Fig.41 and Fig.46 The structure of the optical lens of the fifth embodiment at the far focus and near focus is shown. The structure of the optical lens of the fifth embodiment is different from that of the optical lens of the first embodiment mainly in the parameters of each lens, the relationship satisfied, the focal power, and the concave-convex condition at the optical axis.

[0217] As an optional embodiment of the present application, based on the fifth embodiment of the present application, the parameter values ​​of each lens of the optical lens can refer to Table 5a to Table 5c.

[0218] Table 5a

[0219] Surface number Surface type R-Value Thickness(mm) Refractive Index Abbe number OBJ Standard Infinity 15.0(4.00) S1 Standard Infinity 0.400 1.83 42.0 S2 Standard 1.14 0.891 S3 Standard -1.52 0.791 1.48 72.4 S4 Standard .2.77 0.195(0.445) S5 Standard 1.37 0.590 1.74 27.3 S6 Standard 1.85 1.125(0.875) STO Standard Infinity 0.371 S8 Standard 7.35 0.900 1.45 90.3 S9 Standard -1.19 0.441 S10 Standard 6.59 0.683 1.55 68.1 S11 Standard -1.20 0.701 1.75 35.5 S12 Standard -5.36 1.021 S13 Standard Infinity 0.650 1.52 64.2 S14 Standard Infinity 0.350 1.52 64.2 IMAGE Standard Infinity /

[0220] In the embodiment of the present application, when the optical lens is focused and imaged at 2mm-100mm, the total optical length L is 9.11mm; the image height is 0.81mm; and the field of view is 160°. The focal length f of the optical lens in this embodiment is 0.82mm at the far focus; and the focal length f is 0.80mm at the near focus.

[0221] The positive and negative conditions of the focal length of each lens in the optical lens of this embodiment are shown in Table 5b.

[0222] Table 5b

[0223] lens L1 L2 L3 L4 L5 L6 Optical power - - + + + -

[0224] The concave-convex condition of each lens in the optical lens of this embodiment at the optical axis is shown in Table 5c.

[0225] Table 5c

[0226] lens L1 L2 L3 L4 L5 L6 Concave and convex situation ∞+ -- ++ +- +- --

[0227] Combination Fig.41 and Fig.46 The structural diagram of the optical lens in the fifth embodiment shown in FIG. 5 and the main parameters of the optical lens in the fifth embodiment given in Tables 5a to 5c are obtained through simulation. Figures 42 to 50 The simulation diagram shown. Fig.42 and Fig.47 As can be seen from the figure, as the field of view increases, the vertical chromatic aberration of the optical lens gradually increases, but the vertical axis chromatic aberration can be controlled within the deviation allowed by the diffraction limit, making the chromatic aberration smaller and improving the imaging quality. Fig.43 and Fig.48 It can be seen that the axial value range of different wavelengths is controlled within the range of ±0.06mm, and the chromatic aberration is good in the entire entrance pupil range. Therefore, the axial point chromatic aberration of this optical lens is good. Fig.44 and Fig.49 It can be seen that the astigmatism value of the optical lens is controlled between -0.01 and 0.06. As the field of view increases, the astigmatism of the system gradually increases, but the astigmatism value can be controlled within the range of ±0.06mm, and the image quality of the optical lens is good. Fig.45 and Fig.50 It can be seen that as the field of view increases, the distortion of the optical lens gradually increases, but the distortion value can be controlled within 80%, reducing the impact of image distortion on image quality. This shows that the imaging quality of the optical lens is good.

[0228] Fig.51 and Fig.56The structure of the optical lens of Example 6 at far focus and near focus is shown. The structure of the optical lens of Example 6 is mainly different from that of the optical lens of Example 1 in terms of the parameters of each lens, the relationship they satisfy, the focal power, and the concave-convex condition at the optical axis.

[0229] As an optional embodiment of the present application, on the basis of Embodiment 6 of the present application, the parameter values ​​of each lens of the optical lens can refer to Table 6a to Table 6c.

[0230] Table 6a

[0231] Surface number Surface type R-Value Thickness(mm) Refractive Index Abbe number OBJ Standard Infinity 15.0(4.00) S1 Standard Infinity 0.400 1.83 42.0 S2 Standard 1.12 0.944 S3 Standard -1.35 0.801 1.47 70.4 S4 Standard -2.24 0.760(0.972) S5 Standard 1.48 0.800 1.76 52.7 S6 Standard 1.80 1.181(0.969) STO Standard Infinity 0.281 S8 Standard 1.48 0.533 1.62 60.4 S9 Standard -17.17 0.400 S10 Standard 20.31 0.450 1.85 35.3 S11 Standard 0.96 0.715 1.58 71.0 S12 Standard -1.60 1.079 S13 Standard Infinity 0.650 1.52 64.2 S14 Standard Infinity 0.350 1.52 64.2 IMAGE Standard Infinity /

[0232] In the embodiment of the present application, when the optical lens is focused and imaged at 2mm-100mm, the total optical length L is 9.34mm; the image height is 0.81mm; and the field of view is 160°. The focal length f of the optical lens in this embodiment is 0.79mm at the far focus; and the focal length f is 0.77mm at the near focus.

[0233] The positive and negative conditions of the focal length of each lens in the optical lens of this embodiment are shown in Table 4b.

[0234] Table 6b

[0235] lens L1 L2 L3 L4 L5 L6 Optical power - - + + - +

[0236] The concave-convex condition of each lens in the optical lens of this embodiment at the optical axis is shown in Table 6c.

[0237] Table 6c

[0238] lens L1 L2 L3 L4 L5 L6 Concave and convex situation ∞+ -- ++ +- ++ +-

[0239] Combination Fig.51 and Fig.56 The structural diagram of the optical lens in the sixth embodiment shown in FIG. 6 and the main parameters of the optical lens in the sixth embodiment given in Tables 6a to 6c are obtained through simulation. Figures 52 to 60 The simulation diagram shown. Fig.52 and Fig.57 As can be seen from the figure, as the field of view increases, the vertical chromatic aberration of the optical lens gradually increases, but the vertical axis chromatic aberration can be controlled within the deviation allowed by the diffraction limit, making the chromatic aberration smaller and improving the imaging quality. Fig.53 and Fig.58 It can be seen that the axial value range of different wavelengths is controlled within the range of ±0.06mm, and the chromatic aberration is good in the entire entrance pupil range. Therefore, the axial point chromatic aberration of this optical lens is good. Fig.54 and Fig.59It can be seen that the astigmatism value of the optical lens is controlled between -0.01 and 0.06. As the field of view increases, the astigmatism of the system gradually increases, but the astigmatism value can be controlled within the range of ±0.06mm, and the image quality of the optical lens is good. Fig.55 and Fig.60 It can be seen that as the field of view increases, the distortion of the optical lens gradually increases, but the distortion value can be controlled within 80%, reducing the impact of image distortion on image quality. This shows that the imaging quality of the optical lens is good.

[0240] Fig.61 and Fig.66 The structure of the optical lens of the seventh embodiment at the far focus and near focus is shown. The structure of the optical lens of the seventh embodiment is different from that of the optical lens of the first embodiment mainly in the parameters of each lens, the relationship satisfied, the focal power, and the concave-convex condition at the optical axis.

[0241] As an optional embodiment of the present application, based on Embodiment 7 of the present application, the parameter values ​​of each lens of the optical lens can refer to Table 7a to Table 7c.

[0242] Table 7a

[0243] Surface number Surface type R-Value Thickness(mm) Refractive Index Abbe number OBJ Standard Infinity 15.0(4.00) S1 Standard Infinitv 0.450 1.86 40.1 S2 Standard 1.13 0.830 S3 Standard -1.33 0.631 1.45 70.4 S4 Standard -2.62 0.188(0.439) S5 Standard 1.62 0.803 1.74 25.7 S6 Standard 2.00 0.770(0.519) STO Standard Infinitv 0.221 S8 Standard 2.95 0.685 1.48 90.3 S9 Standard -1.10 0.442 S10 Standard 15.18 0.745 1.55 78.3 S11 Standard -1.15 0.449 1.78 29.5 S12 Standard -4.32 0.830 S13 Standard Infinitv 0.650 1.52 64.2 S14 Standard Infinity 0.350 1.52 64.2 IMAGE Standard Infinity /

[0244] In the embodiment of the present application, when the optical lens is focused and imaged at 2mm-100mm, the total optical length L is 8.04mm; the image height is 0.81mm. The optical lens in this embodiment has a focal length f of 0.83mm at far focus and a field of view of 156°; and a focal length f of 0.81mm at near focus and a field of view of 148°.

[0245] The positive and negative conditions of the focal length of each lens in the optical lens of this embodiment are shown in Table 7b.

[0246] Table 7b

[0247] lens L1 L2 L3 L4 L5 L6 Optical power - - + + + -

[0248] The concave-convex condition of each lens in the optical lens of this embodiment at the optical axis is shown in Table 7c.

[0249] Table 7c

[0250] lens L1 L2 L3 L4 L5 L6 Concave and convex situation ∞+ -- ++ +- +- --

[0251] Combination Fig.61 and Fig.66 The structural diagram of the optical lens in the seventh embodiment shown in FIG. 1 and the main parameters of the optical lens in the seventh embodiment given in Tables 7a to 7c are obtained through simulation. Figures 62 to 70 The simulation diagram shown. Fig.62 and Fig.67 As can be seen from the figure, as the field of view increases, the vertical chromatic aberration of the optical lens gradually increases, but the vertical axis chromatic aberration can be controlled within the deviation allowed by the diffraction limit, making the chromatic aberration smaller and improving the imaging quality. Fig.63 and Fig.68 It can be seen that the axial value range of different wavelengths is controlled within the range of ±0.06mm, and the chromatic aberration is good in the entire entrance pupil range. Therefore, the axial point chromatic aberration of this optical lens is good. Fig.64 and Fig.69 It can be seen that the astigmatism value of the optical lens is controlled between -0.02 and 0.06. As the field of view increases, the astigmatism of the system gradually increases, but the astigmatism value can be controlled within the range of ±0.06mm, and the image quality of the optical lens is good. Fig.65 and Fig.70 It can be seen that as the field of view increases, the distortion of the optical lens gradually increases, but the distortion value can be controlled within 80%, reducing the impact of image distortion on image quality. This shows that the imaging quality of the optical lens is good.

[0252] Table 10 shows the optical parameters of the optical lenses in ten embodiments of the present application including the above seven embodiments.

[0253] Table 10

[0254] Optical parameters Embodiment 1 Embodiment 2 Embodiment 3 Embodiment 4 Embodiment 5 f4 / f2 -0.32 -0.37 -0.22 -0.32 -0.27 f4 / fm 0.08 0.29 0.05 0.07 0.23 fm / f 25.92 7.77 43.05 35.03 12.36 f2 / f1 0.25 0.24 0.24 0.21 0.15 (R1-R2) / (R1+R2) -0.40 -0.39 1.97 -0.47 -0.29 f3 / f 4.62 4.66 4.17 3.73 6.30 Optical parameters Embodiment 6 Embodiment 7 Embodiment 8 Embodiment 9 Embodiment 10 f4 / f2 -0.22 -0.28 -0.14 -0.49 -0.24 f4 / fm 0.21 0.13 0.06 0.06 0.50 fm / f 12.83 17.62 27.43 36.36 6.17 f2 / f1 0.12 0.19 0.11 0.35 0.11 (R1-R2) / (R1+R2) -0.25 -0.33 -0.21 -0.84 -0.27 f3 / f 6.13 5.98 3.44 3.90 7.24

[0255] Note: The following are the explanations of the relationship between the optical lenses in each embodiment:

[0256] f is the focal length of the optical lens, which is equal to the EFL value of the optical lens.

[0257] f1 is the focal length of the first lens L1 in the optical lens;

[0258] f2 is the focal length of the second lens L2 in the optical lens;

[0259] f3 is the focal length of the third lens L3 in the optical lens;

[0260] f4 is the focal length of the fourth lens L4 in the optical lens;

[0261] fm is the focal length of the cemented lens composed of the fifth lens L5 and the sixth lens L6 in the optical lens, that is, equal to the combined focal length of the fifth lens L5 and the sixth lens L6;

[0262] R1 is the curvature of the object side of the second lens in the optical lens;

[0263] R2 is the curvature of the image side surface of the second lens in the optical lens.

[0264] It should be noted that the optical parameters of the optical lenses in the above-mentioned embodiments 1 to 7 correspond to the above-mentioned seven embodiments. Since the structures of the optical lenses in the eighth, ninth and tenth embodiments are the same as those in the above-mentioned seven embodiments, but the parameters are slightly different, the optical parameters of the relational expressions corresponding to the optical lenses in the eighth, ninth and tenth embodiments are listed in Table 10.

[0265] It can be seen from the optical parameters of the ten embodiments given in Table 10 above that the optical lens of the present application satisfies the relationship: -0.5 <f4 / f2<-0.1。

[0266] If the ratio f4 / f2 is too small, the length of the optical lens will be too long, which is not conducive to use on products with limited installation space; if the ratio f4 / f2 is too large, the imaging quality of the optical lens within the depth of field will be poor, and it will be difficult to correct spherical aberration, coma, and chromatic aberration, making it impossible to obtain high-resolution images.

[0267] By reasonably selecting the above parameters, when the ratio f4 / f2 satisfies the above relationship, the appropriate ratio of the focal length of the fourth lens L4 to the focal length of the second lens L2 is conducive to the correction of aberrations and the improvement of the imaging quality within the depth of field, and the optical lens has a shorter total optical length, which is conducive to reducing the length of the entire optical lens. When the optical lens is used as an endoscope objective lens installed in the hard part of the endoscope, it is conducive to reducing the length of the hard part of the endoscope.

[0268] It can be seen from the optical parameters of the ten embodiments given in Table 10 above that the optical lens of the present application satisfies the relationship: <f4 / fm<0.5。

[0269] If the ratio f4 / fm is too small, the aberration produced by the fourth lens L4 cannot be completely corrected, which has a great impact on the imaging quality of the entire optical lens; if the ratio f4 / fm is too large, not only the total length of the optical lens is longer, but also the aberration produced by the last two lenses cannot be completely corrected.

[0270] By reasonably selecting the above parameters, when the ratio f4 / fm satisfies the above relationship, it is not only beneficial to correct the aberration of the optical lens and improve the imaging quality, but also shortens the overall length of the optical lens.

[0271] It can be seen from the optical parameters of the ten embodiments given in Table 10 above that the optical lens of the present application satisfies the relationship: <fm / f<50。

[0272] By reasonably selecting the above parameters, when the ratio fm / f satisfies the above relationship, better light can be collected to the imaging surface after passing through the optical lens, improving the brightness of the overall image, and is conducive to the correction of axial chromatic aberration and vertical chromatic aberration, balancing the aberrations produced by other lenses, improving the imaging quality, and shortening the total length of the optical lens. In addition, when the fifth lens L5 and the sixth lens L6 are glued together to form a glued lens, not only the tolerance sensitivity is reduced, the imaging quality can be further improved, but also the length of the optical lens is further reduced, and it is more convenient to assemble the optical lens.

[0273] It can be seen from the optical parameters of the ten embodiments given in Table 10 above that the optical lens of the present application satisfies the relationship: 0.1 <f2 / f1<0.4。

[0274] If the ratio f2 / f1 is too small, the first lens L1 of the optical lens will have a large aberration, which will increase the difficulty of designing the entire optical lens and make the tolerance sensitivity poorer; if the ratio f2 / f1 is too large, the aperture of the first lens L1 of the optical lens will be large, making it difficult to achieve a thin diameter. Thin diameter means that the aperture of the optical lens should be as small as possible. Especially when the optical lens is used as an endoscope objective, it is an important indicator of the optical lens design.

[0275] By reasonably selecting the above parameters, when the ratio f2 / f1 satisfies the above relationship, the difference in negative power between the first lens L1 and the second lens L2 is small, and the deflection angle of light passing through is small, which not only makes it possible to correct the aberration and spherical aberration of the optical lens well, thereby further improving the imaging quality of the optical lens, but also facilitates the reduction of the diameter of the optical lens.

[0276] It can be seen from the optical parameters of the ten embodiments given in Table 10 above that the optical lens of the present application satisfies the relationship: <f3 / f<8。

[0277] If the ratio f3 / f is too small, the spherical aberration of the first lens L1 and the second lens L2 cannot be corrected well, resulting in poor image quality; if the ratio f3 / f is too large, the image quality of the optical lens will be improved, but the length of the optical lens will be too long, which is not conducive to miniaturization design.

[0278] By reasonably allocating the focal length of each lens of the optical lens, when the ratio f3 / f satisfies the above relationship, the aberrations of the third lens L3 and the remaining lenses cancel each other out, thereby improving the imaging quality; at the same time, it is also beneficial to shorten the length of the optical lens, thereby realizing a miniaturized design of the optical lens.

[0279] It can be seen from the optical parameters of the ten embodiments given in Table 10 above that the curvature radius R1 of the object side surface and the curvature radius R2 of the image side surface of the second lens group of the optical lens of the present application satisfy the relationship: -1<(R1-R2) / (R1+R2)<3.

[0280] If the ratio (R1-R2) / (R1+R2)< is too small, the astigmatism and coma of the optical lens are over-corrected; if the ratio (R1-R2) / (R1+R2)< is too large, the processability of the second lens L2 is reduced, and the correction effect of the aberration is reduced, and it cannot be balanced with the aberrations generated by the first lens L1 and the third lens L3 in the optical lens, which has a great impact on the optical imaging quality.

[0281] 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 at the edge of the second lens L2 can be effectively controlled, that is, the light passing through the second lens L2 at the circumference will not be too greatly deflected toward the optical axis or the edge, so that the light passing through the second lens L2 at the circumference is relatively smooth, so that the beam diameter is effectively controlled, and the size of the second lens L2 in the direction perpendicular to the optical axis is effectively controlled, 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 is not too thin, and it is easy to process.

[0282] In summary, when the optical lens in the present application focuses within the depth of field range of 2mm-100mm, the total optical length of the optical lens is controlled at 7.72mm-9.11mm, indicating that the size of the optical lens is relatively small. The image height is greater than 0.8mm, indicating that the resolution of the optical lens is relatively high; the field of view angle can reach 135°~160°; at the same time, it can be seen from the simulation diagrams of various embodiments that the optical lens in the present application can achieve the purpose of taking into account a large field of view angle, high image quality and miniaturization within the depth of field range of 2mm-100mm. When the optical lens is used as an endoscope objective lens, the endoscope containing the optical lens of the present application can be used for colonoscopy and gastroscopy.

[0283] The embodiment of the present application also provides an endoscope, comprising the camera module in any of the above embodiments. The beneficial effects achieved by the endoscope are the same as those of the camera module in the above embodiments, which will not be described in detail here.

[0284] An embodiment of the present application also provides an endoscope system, including a light source host, an image processing device and an endoscope.

[0285] The image processing device is connected to the light source host in communication, and the light source host is connected to the endoscope in a detachable manner. For example, the light source host and the endoscope are pluggable.

[0286] When the light source host and the image processing device are a two-in-one integrated device, there is no concept of corresponding connection.

[0287] The endoscope system also includes a display that is communicatively connected to the image processing device, wherein the display can be provided as an independent device or integrated into the image processing device, which is not specifically limited here.

[0288] The beneficial effects achieved by the endoscope system are the same as those of the endoscope in the above-mentioned embodiment, and will not be described in detail here.

[0289] The above are only specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. An optical lens, characterized in that: comprising 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 so that the optical lens can be focused 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。 2. The optical lens according to claim 1, characterized in that: The fifth lens and the sixth lens form a cemented lens.

3. The optical lens according to claim 2, characterized in that: The cemented lens has positive power.

4. The optical lens according to claim 3, characterized in that: The combined focal length fm of the cemented lens and the focal length f4 of the fourth lens satisfy the relationship: <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 far focus satisfy the relationship: <fm / f<50。 5. The optical lens according to any one of claims 1 to 4, characterized in that: 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。 6. The optical lens according to any one of claims 1 to 4, characterized in that: A curvature radius R1 of the object-side surface of the second lens and a curvature radius R2 of the image-side surface of the second lens satisfy the relationship: -1<(R1-R2) / (R1+R2)<3.

7. The optical lens according to any one of claims 1 to 4, characterized in that: The focal length f3 of the third lens and the effective focal length f of the optical lens at the far focus satisfy the relationship: <f3 / f<8。 8. The optical lens according to any one of claims 1 to 4, characterized in that: The optical lens further includes a stop, and the stop is located between the third lens and the fourth lens.

9. A camera module, characterized in that: include: The optical lens according to any one of claims 1 to 8; as well as The photosensitive element is arranged on the image side of the optical lens.

10. The camera module according to claim 9, characterized in that: A filter is also provided between the photosensitive element and the optical lens.

11. An endoscope, characterized in that: include: A camera module as described in any one of claims 9-10.

12. An endoscope system, characterized in that: include: A light source host, an image processing device, and an endoscope as claimed in claim 11.

Images