Optical lens

Abstract

The application provides an optical lens, which is composed of a first group with negative optical power, a second group with positive optical power and a protection glass along an optical axis from an object side to an imaging surface; the first group is sequentially composed of a first lens and a first substrate which are glued together along the optical axis from the object side to the imaging surface; the first lens has negative optical power, the object side surface of the first lens is a concave surface, and the image side surface of the first lens is a plane; the object side surface and the image side surface of the first substrate are both planes; the second group is sequentially composed of a second substrate and a second lens which are glued together along the optical axis from the object side to the imaging surface; the object side surface and the image side surface of the second substrate are both planes; the second lens has positive optical power, the object side surface of the second lens is a plane, and the image side surface of the second lens is a convex surface. The optical lens provided by the application can meet the requirement of a large view angle, reduce the size and aperture of the lens, effectively increase the depth of field of the lens, and meet the requirement of the detection range and observation depth of an endoscope.

Description

Technical Field

[0001] This invention relates to the technical field of imaging lenses, and in particular to an optical lens. Background Technology

[0002] In recent years, with the rapid development of the medical field, society's requirements for medical equipment have also been increasing, especially the performance requirements for cameras mounted on medical testing equipment. For example, in order to more flexibly and comprehensively enter the human body to collect images, medical equipment such as endoscopes with camera lenses are generally used to examine various cavities such as the gastrointestinal tract, pancreas, biliary tract, and respiratory tract, so as to determine the internal structure of the human body or observe pathological conditions.

[0003] Currently, endoscope lenses on the market generally suffer from problems such as excessive size, small field of view, and insufficient depth of field. For example, excessive size can cause discomfort to the user when using the endoscope, a small field of view results in an insufficient observation range, and a small depth of field affects the observation depth of the endoscope lens. Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to provide an optical lens that can effectively meet the requirements of endoscopic detection range and observation depth.

[0005] The technical solution adopted in this invention is as follows: An optical lens, which consists of a first group with negative optical power, a second group with positive optical power, and a protective glass, arranged sequentially from the object side to the imaging plane along the optical axis; The first group consists of a first lens and a first substrate bonded together along the optical axis from the object side to the imaging surface; the first lens has negative optical power, its object side is concave, and its image side is planar; both the object side and the image side of the first substrate are planar; the object side of the first substrate is bonded and fixed to the image side of the first lens. The second group consists of a second substrate and a second lens bonded together along the optical axis from the object side to the imaging surface; the object side and image side of the second substrate are both planar; the second lens has positive optical power, its object side is planar, and its image side is convex; the object side of the second lens is bonded and fixed to the image side of the second substrate. Wherein, the total optical length TTL of the optical lens and the true image height IH corresponding to the maximum field of view of the optical lens satisfy: 1.5 <TTL / IH<2.2。

[0006] Further preferably, the true image height IH corresponding to the maximum field of view of the optical lens and the effective focal length f of the optical lens satisfy: 1.3 <IH / f<1.7。

[0007] Further preferably, the total optical length TTL of the optical lens and the aperture value Fno of the optical lens satisfy: 0.1mm<TTL / Fno<0.3mm.

[0008] Further preferably, the maximum field of view FOV of the optical lens and the aperture value Fno of the optical lens satisfy: 23°<FOV / Fno<26°.

[0009] Further preferably, the effective focal length f of the optical lens and the focal length f1 of the first lens satisfy: -6.1<f1 / f<-3.3; the radius of curvature R1 of the object-side surface of the first lens and the effective focal length f of the optical lens satisfy: -1.5<R1 / f<-0.2.

[0010] Further preferably, the effective focal length f of the optical lens and the focal length f2 of the second lens satisfy: 0.9<f2 / f<1; the radius of curvature R6 of the image-side surface of the second lens and the effective focal length f of the optical lens satisfy: -0.7<R6 / f<-0.3.

[0011] Further preferably, the center thickness CT1 of the first lens and the edge thickness ET1 of the first lens satisfy: 0.3<CT1 / ET1<0.7.

[0012] Further preferably, the clear semi-aperture CSD3 on the image-side surface of the first substrate and the clear semi-aperture CSD4 on the object-side surface of the second substrate satisfy: 1.3<CSD3 / CSD4<2.

[0013] Further preferably, the clear semi-aperture CSD1 on the object-side surface of the first lens and the clear semi-aperture CSD6 on the image-side surface of the second lens satisfy: 1.2<CSD1 / CSD6<2.3.

[0014] Further preferably, the effective focal length f of the optical lens satisfies: 0.28mm<f<0.36mm; the total optical length TTL of the optical lens satisfies: 0.7mm<TTL<1.1mm; the maximum field of view FOV of the optical lens satisfies: 100°<FOV<125°.

[0015] The optical lens provided by the present invention is configured with two groups, using only two sets of lenses and substrates, which not only facilitates the fixation of the optical imaging system, but also significantly reduces the total length of the optical imaging system, realizes the miniaturization of the lens, and is beneficial to mass production. At the same time, the size and aperture of the lens are reduced while satisfying a large field of view, and the depth of field of the lens is effectively increased, which can well meet the requirements of the endoscope for detection range and observation depth. The lens can achieve high-definition imaging within the working object distance from 3mm to infinity, which can well meet the requirements of the endoscope for detection range, observation depth and definition. Attached Figure Description

[0016] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a schematic diagram of the optical lens structure in Embodiment 1 of the present invention.

[0017] Figure 2 This is an MTF curve of the optical lens in Embodiment 1 of the present invention.

[0018] Figure 3 This is an axial aberration curve of the optical lens in Embodiment 1 of the present invention.

[0019] Figure 4 This is a field curvature curve diagram of the optical lens in Embodiment 1 of the present invention.

[0020] Figure 5 This is a schematic diagram of the optical lens structure in Embodiment 2 of the present invention.

[0021] Figure 6 This is the MTF curve of the optical lens in Embodiment 2 of the present invention.

[0022] Figure 7 This is an axial aberration curve of the optical lens in Embodiment 2 of the present invention.

[0023] Figure 8 This is a field curvature curve diagram of the optical lens in Embodiment 2 of the present invention.

[0024] Figure 9 This is a schematic diagram of the optical lens in Embodiment 3 of the present invention.

[0025] Figure 10 This is an MTF curve of the optical lens in Embodiment 3 of the present invention.

[0026] Figure 11 This is an axial aberration curve of the optical lens in Embodiment 3 of the present invention.

[0027] Figure 12 This is a field curvature curve diagram of the optical lens in Embodiment 3 of the present invention.

[0028] Figure 13 This is a schematic diagram of the optical lens structure in Embodiment 4 of the present invention.

[0029] Figure 14 This is the MTF curve of the optical lens in Embodiment 4 of the present invention.

[0030] Figure 15 This is an axial aberration curve of the optical lens in Embodiment 4 of the present invention.

[0031] Figure 16This is a field curvature curve diagram of the optical lens in Embodiment 4 of the present invention.

[0032] The following detailed description, in conjunction with the accompanying drawings, will further illustrate the present invention. Detailed Implementation

[0033] To better understand this application, various aspects of this application will be described in more detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely illustrative of embodiments of this application and are not intended to limit the scope of this application in any way. Throughout the specification, the same reference numerals refer to the same elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0034] It should be noted that in this specification, the terms "first," "second," "third," etc., are used only to distinguish one feature from another and do not imply any limitation on the features. Therefore, without departing from the teachings of the invention, the first lens discussed below may also be referred to as the second lens or the third lens.

[0035] In the accompanying drawings, the thickness, size, and shape of the lenses have been slightly exaggerated for ease of illustration. Specifically, the shapes of the spherical or aspherical surfaces shown in the drawings are illustrated by way of example. That is, the shapes of the spherical or aspherical surfaces are not limited to those shown in the drawings. The drawings are for illustrative purposes only and are not strictly to scale.

[0036] In this article, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the location of the convexity is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the location of the concaveness is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the subject is called the object-side surface of the lens, and the surface of each lens closest to the imaging plane is called the image-side surface of the lens.

[0037] It should also be understood that the terms "comprising," "including," "having," "containing," and / or "comprising," when used in this specification, indicate the presence of the stated features, elements, and / or components, but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof. Furthermore, when expressions such as "at least one of..." appear after a list of listed features, they modify the entire list of features, not individual elements in the list. Additionally, when describing embodiments of this application, the word "may" is used to mean "one or more embodiments of this application." And the term "exemplary" is intended to refer to an example or illustration.

[0038] Unless otherwise specifically defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It should also be understood that terms (such as those defined in commonly used dictionaries) should be interpreted as having a meaning consistent with their meaning in the context of the relevant art, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0039] It should be noted that the embodiments of the present application and the features in the embodiments may be combined with each other under the condition of no conflict. The present application will be described in detail below with reference to the accompanying drawings in conjunction with the embodiments.

[0040] In the optical lens provided by the embodiment of the present invention, along the optical axis from the object side to the imaging surface, there are sequentially a first group with negative refractive power, a second group with positive refractive power, and a protective glass. Wherein, along the optical axis from the object side to the imaging surface, the first group is sequentially a cemented first lens and a first substrate; the first lens has negative refractive power, its object side surface is a concave surface, and its image side surface is a flat surface; both the object side surface and the image side surface of the first substrate are flat surfaces; the object side surface of the first substrate is cemented and fixed to the image side surface of the first lens. Along the optical axis from the object side to the imaging surface, the second group is sequentially a cemented second substrate and a second lens; both the object side surface and the image side surface of the second substrate are flat surfaces; the second lens has positive refractive power, its object side surface is a flat surface, and its image side surface is a convex surface; the object side surface of the second lens is cemented and fixed to the image side surface of the second substrate. Specifically, the first lens and the second lens may be respectively fixed on the first substrate and the second substrate by means of nanoimprinting, so that the processing precision and stability can be ensured, and further the miniaturization of the optical lens can be realized. The protective glass functions to protect the optical lens and prevent the photosensitive chip from being damaged and affecting the imaging effect of the lens.

[0041] In some implementations, the optical lens may further include a diaphragm, and the diaphragm may be coated on the image side surface of the second substrate by a coating method. It can be understood that the diaphragm is used to limit the amount of incoming light, so as to change the brightness of the imaging.

[0042] In some implementations, the total optical length TTL of the optical lens and the real image height IH corresponding to the maximum field angle of the optical lens satisfy: 1.5<TTL / IH<2.2. Satisfying the above conditional expression, the total optical length of the optical lens and the real image height corresponding to the maximum field angle are reasonably configured, which can effectively shorten the total optical length of the optical lens while ensuring that the optical lens has high pixels, so that the optical lens meets the miniaturization requirement and has high imaging quality.

[0043] In some embodiments, the real image height IH corresponding to the maximum field angle of the optical lens and the effective focal length f of the optical lens satisfy: 1.3<IH / f<1.7. Meeting the above conditional expression, the ratio of the effective focal length to the image height of the optical lens is controlled. Shortening the effective focal length can expand the field angle, enable the optical lens to capture a wider object-side space, increase the width of the light beam entering the optical lens, improve the brightness of the optical lens at the image plane and avoid vignetting; at the same time, the optical lens is provided with a large image plane characteristic, which matches a large-image-plane chip to improve the resolution and ensure the imaging quality of the optical lens.

[0044] In some embodiments, the total optical length TTL of the optical lens and the aperture value Fno of the optical lens satisfy: 0.1mm<TTL / Fno<0.3mm. Meeting the above conditional expression, by controlling the relationship between the total length of the optical lens and the aperture value, it is ensured that the optical lens can meet certain design requirements for aperture and miniaturization, so that the optical lens can obtain sufficient light throughput even in a dim environment, and meet the needs of high-quality and high-definition shooting.

[0045] In some embodiments, the maximum field angle FOV of the optical lens and the aperture value Fno of the optical lens satisfy: 23°<FOV / Fno<26°. Meeting the above conditional expression can ensure that the optical lens has a certain large field angle, reduce the influence of off-axis aberrations on the system, and at the same time ensure the improvement of the brightness of the imaging plane, thereby improving the imaging quality.

[0046] In some embodiments, the effective focal length f of the optical lens and the focal length f1 of the first lens satisfy: -6.1<f1 / f<-3.3. Meeting the above conditional expression, the first lens is provided with negative refractive power, which can diverge the light passing therethrough, expand the field angle of the optical lens, and simplify the balance between the overall aberration correction and the imaging quality of the optical lens.

[0047] In some embodiments, the curvature radius R1 of the object-side surface of the first lens and the effective focal length f of the optical lens satisfy: -1.5<R1 / f<-0.2. Meeting the above conditional expression can constrain the surface profile of the object-side surface of the first lens, which is beneficial to reducing the bending degree of light at the image-side surface of the first lens, helping the incident light to converge, reducing the astigmatism of the optical lens, so as to balance the astigmatism problem caused by the large field angle of the optical lens, so that the astigmatism will not be too large while the optical lens has a large field of view, thereby ensuring that the optical lens has excellent imaging quality; at the same time, the curvature radius value of the object-side surface of the first lens is relatively large, making the object-side surface relatively gentle and preventing the object-side surface of the first lens from being scratched.

[0048] In some embodiments, the effective focal length f of the optical lens and the focal length f2 of the second lens satisfy: 0.9 < f2 / f < 1. By satisfying the above conditional expression, the optical power of the second lens can be effectively adjusted, so as to reasonably deflect the light rays from the marginal field of view of the first lens, prevent excessive deflection of the light rays, thereby correcting the marginal aberration of the optical lens and improving the imaging resolution.

[0049] In some embodiments, the radius of curvature R6 of the image side of the second lens and the effective focal length f of the optical lens satisfy: -0.7 < R6 / f < -0.3. Satisfying the above conditional expression makes the image side of the second lens a convex surface, which can reasonably limit the width of the light beam exiting from the second lens, contribute to the miniaturization of the optical lens, and the second lens can effectively reduce the occurrence of spherical aberration and astigmatism to improve the imaging quality of the optical lens.

[0050] In some embodiments, the center thickness CT1 of the first lens and the edge thickness ET1 of the first lens satisfy: 0.3 < CT1 / ET1 < 0.7. By satisfying the above conditional expression, by reasonably controlling the ratio of the edge thickness of the first lens to the thickness of the first lens on the optical axis, the thickness ratio of the first lens can be reasonably controlled, so as to optimize the surface shape of the first lens, which is beneficial to the effective convergence of large-angle incident light rays, and makes the light rays passing through the first lens have a small deflection angle, thereby reducing the generation of stray light and further ensuring good imaging performance.

[0051] In some embodiments, the clear half aperture CSD3 of the image side of the first substrate and the clear half aperture CSD4 of the object side of the second substrate satisfy: 1.3 < CSD3 / CSD4 < 2. By satisfying the above conditional expression, by limiting the clear aperture of the image side of the first group and the clear aperture of the object side of the second group, on the one hand, the smaller incident aperture of the second group is used to converge the imaging beam, physically block stray light, suppress ghost images and glare, improve image contrast, and reduce the radial size of the lens to realize a small, thin and light module; on the other hand, the incident height of the light rays is precisely constrained, and the distribution of lens optical power is matched to balance and correct spherical aberration, coma, chromatic aberration and distortion, so as to ensure high-resolution imaging in the full field of view.

[0052] In some embodiments, the clear half aperture CSD1 of the object side of the first lens and the clear half aperture CSD6 of the image side of the second lens satisfy: 1.2 < CSD1 / CSD6 < 2.3. By satisfying the above conditional expression, by controlling the ratio of the clear half aperture at the object side end of the first lens to the clear aperture at the image side end of the second lens, the optical lens can have a small aperture size, while ensuring that the optical lens can collect large-angle light rays, realize large field-of-view imaging of the optical lens, increase the imaging area of the optical lens, and improve the imaging quality.

[0053] In some embodiments, the maximum field of view FOV of the optical lens and the entrance pupil diameter of the optical lens satisfy: 1400° / mm<FOV / EPD<2100° / mm. Meeting the above conditional expression enables the optical lens to have a large field of view range and a small entrance pupil diameter, and also shows that the optical lens has a long depth of field range, that is, the optical lens can achieve large-angle clear imaging while still having clear recognition capability for near objects, ensuring high imaging quality.

[0054] In some embodiments, the center thickness CT5 of the second lens and the edge thickness ET5 of the second lens satisfy: 1.1<CT5 / ET5<1.3. Meeting the above conditional expression, by controlling the center thickness and edge thickness of the second lens within a certain range, can also effectively balance the aberration generated by the optical lens, and is also beneficial to the field curvature adjustment in engineering production, thereby helping to improve the imaging quality of the optical lens.

[0055] In some embodiments, the clear semi-aperture CSD1 on the object side of the first lens and the clear semi-aperture CSD2 on the image side of the first lens satisfy: 1.05<CSD1 / CSD2<1.15. Meeting the above conditional expression ensures that the first lens has a large aperture, guarantees that light in a relatively large range enters the optical lens, ensures that the lens has a large field of view, and improves the imaging performance of the lens.

[0056] In some embodiments, the clear semi-aperture CSD1 on the object side of the first lens and the sagittal height SAG1 of the clear semi-aperture on the object side of the first lens satisfy: -12<CSD1 / SAG1<-5. Meeting the above conditional expression, by adjusting the surface shape of the edge region on the object side of the first lens, is beneficial to collecting light rays of the edge field of view, and can correct off-axis aberrations of the edge field of view of the optical lens at the same time, so as to improve the imaging quality of the optical lens.

[0057] In some embodiments, the clear semi-aperture CSD6 on the image side of the second lens and the sagittal height SAG6 of the clear semi-aperture on the image side of the second lens satisfy: -4.7<CSD6 / SAG6<-3.4. Meeting the above conditional expression, by reasonably limiting the shape of the image side of the second lens, can improve the field curvature of the lens, reduce the difficulty of lens aberration optimization, thereby improving the imaging quality of the lens.

[0058] In some embodiments, the optical lens satisfies the following conditional expressions: 0.28mm<f<0.36mm; 100°<FOV<125°; 0.05mm<EPD<0.08mm; 0.7mm<TTL<1.1mm; 4<Fno<5.5; 26°<CRA<30°; 0.45mm<IH<0.5mm. In the above conditional expressions, f denotes the effective focal length of the optical lens; FOV denotes the maximum field of view of the optical lens, EPD denotes the entrance pupil diameter of the optical lens, TTL denotes the total optical length of the optical lens; Fno denotes the aperture value of the optical lens, CRA denotes the chief ray incident angle at the maximum image height of the optical lens, and IH denotes the real image height corresponding to the maximum field of view of the optical lens, that is, the full image height of the optical lens. By satisfying the above conditional expressions, the optical lens has at least one or more of the advantages of short focal length, large field of view, small entrance pupil diameter, short total length, relatively small aperture, small image plane, low distortion, and low sensitivity.

[0059] In some implementations, the substrate in the optical lens provided by the present invention is made of glass, so that the substrate can better realize the imprinting and assembly of the first lens and the second lens.

[0060] In some implementations, the lens material in the optical lens provided by the present invention may be glass or plastic. When the lens is made of plastic, the production cost can be effectively reduced, and the volume and weight of the lens can be reduced while facilitating the forming of the nano-imprinted lens. In addition, when the lens is made of glass, the geometric chromatic aberration of the optical system can be effectively corrected through the low dispersion characteristic of glass itself. Preferably, the first lens and the second lens of the lens of the present invention are made of plastic.

[0061] More specifically, the first lens and the second lens of the present invention adopt aspherical lenses.

[0062] In various embodiments of the present invention, when the lenses are aspherical lenses, each aspherical surface shape of the optical lens satisfies the following equation: ; Wherein, z is the distance between the curved surface and the vertex of the curved surface in the optical axis direction, h is the distance from the optical axis to the curved surface, c is the curvature of the vertex of the curved surface, K is the conic coefficient, and A, B, C, D, E, F, G, H are respectively the second-order, fourth-order, sixth-order, eighth-order, tenth-order, twelfth-order, fourteenth-order, and sixteenth-order surface coefficients.

[0063] The present invention will be further described below with reference to several embodiments. In each embodiment, the thickness, radius of curvature, and material selection of each lens in the optical lens are different; for specific differences, please refer to the parameter tables of each embodiment. The following embodiments are merely preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the following embodiments. Any changes, substitutions, combinations, or simplifications made without departing from the innovative points of the present invention should be considered as equivalent substitutions and are included within the protection scope of the present invention.

[0064] Example 1

[0065] Please see Figure 1 The diagram shows a schematic of the structure of the optical lens 100 provided in Embodiment 1 of the present invention. The optical lens 100 includes, along the optical axis from the object side to the imaging surface, a first group Q1 with negative optical power, a second group Q2 with positive optical power, and a protective glass G3.

[0066] The first group includes a first lens L1 and a first substrate G1 sequentially along the optical axis from the object side to the imaging surface. The first lens L1 has negative optical power, its object side S1 is concave, and its image side is planar; the object side and image side S3 of the first substrate G1 are both planar. The first lens L1 is bonded to the first substrate G1, and the image side of the first lens L1 and the object side of the first substrate G1 are bonded surfaces S2; the object side of the first substrate G1 is bonded to the image side of the first lens L1 by nanoimprinting.

[0067] The second group, along the optical axis from the object side to the imaging surface, includes a second substrate G2 and a second lens L2. The object side S4 and the image side of the second substrate G2 are both planar; the second lens L2 has positive optical power, its object side is planar, and its image side S6 is convex. The second substrate G2 is bonded to the second lens L2, and the image side of the second substrate G2 and the object side of the second lens L2 are bonded surfaces S5; the object side of the second lens L2 is bonded to the image side of the second substrate G2 by nanoimprinting.

[0068] The object side (S7) and image side (S8) of the protective glass G3 are both flat. The image side of the protective glass G3 is also the imaging surface.

[0069] The aperture ST is deposited on the image side of the second substrate G2 by a coating process, and the effective aperture of the aperture ST is 0.033mm.

[0070] The object-side surface S1 of the first lens L1 and the image-side surface S6 of the second lens L2 are aspherical. The first lens L1 and the second lens L2 are made of plastic, which facilitates the molding of nano-imprinted lenses and reduces the size and weight of the lenses.

[0071] The first substrate G1, the second substrate G2, and the protective glass G3 are made of glass.

[0072] The relevant parameters of each lens in the optical lens 100 in Example 1 are shown in Table 1-1.

[0073] Table 1-1

[0074] The surface profile parameters of the aspherical lens of the optical lens 100 in Example 1 are shown in Table 1-2.

[0075] Table 1-2

[0076] In this embodiment, the MTF curve, axial aberration curve, and field curvature curve of the optical lens 100 are respectively as follows: Figure 2 , Figure 3 , Figure 4 As shown.

[0077] Figure 2 This is a graph showing the MTF (Modulation Transfer Function) value of the optical lens as a function of the field of view at a spatial frequency of 70 lp / mm. The graph shows that from the center to a 60° field of view, the MTF value is controlled above 0.6, and the MTF curve changes smoothly and evenly from the center to the edge of the field of view, indicating good aberration control, slow degradation of off-axis performance, and clear imaging across the entire field of view. It should be noted that the horizontal axis represents the X-field of view (unit: degrees), indicating the angular range from the center (optical axis) during imaging, with 0° being the exact center and 60° being the edge. The vertical axis represents the MTF value (unitless), with a maximum value not exceeding 1 (perfect transfer). Higher values ​​indicate clearer imaging and higher contrast.

[0078] Figure 3 The diagram shows the axial aberration curves for Example 1, which represent the aberrations of each wavelength along the optical axis at the imaging plane. The horizontal axis represents the axial aberration value (unit: mm), and the vertical axis represents the normalized pupil radius. As can be seen from the diagram, the axial aberration offset is controlled within -0.01 mm to 0.05 mm, indicating that the optical lens can effectively correct axial aberrations.

[0079] Figure 4 The field curvature curve of Example 1 is shown, which represents the field curvature of light rays in the meridional and sagittal image planes. The horizontal axis represents the offset (unit: mm), and the vertical axis represents the field of view (unit: °). As can be seen from the figure, the field curvature of the meridional and sagittal image planes is controlled within 0~0.06 mm, indicating that the optical lens can effectively correct the field curvature.

[0080] Example 2

[0081] Please see Figure 5 The figure shown is a schematic diagram of the structure of the optical lens 200 provided in Embodiment 2 of the present invention. The main difference between this embodiment and Embodiment 1 is that the effective aperture of the stop ST is 0.037mm; the optical parameters such as the radius of curvature and lens thickness of each lens surface are different.

[0082] The relevant parameters of each lens in the optical lens 200 in Example 2 are shown in Table 2-1.

[0083] Table 2-1

[0084] The surface profile parameters of the aspherical lens of the optical lens 200 in Example 2 are shown in Table 2-2.

[0085] Table 2-2

[0086] In this embodiment, the MTF curve, axial aberration curve, and field curvature curve of the optical lens 200 are respectively as follows: Figure 6 , Figure 7 , Figure 8 As shown.

[0087] from Figure 6 As can be seen, from the center to the 60° field of view, the MTF value is controlled above 0.6, and the MTF curve changes smoothly and evenly from the center to the edge of the field of view, indicating that the aberration control is good, the off-axis performance deteriorates slowly, and the optical lens produces clear images across the entire field of view.

[0088] from Figure 7 As can be seen, the axial aberration offset is controlled within -0.01mm to 0.05mm, indicating that the optical lens can effectively correct axial aberration.

[0089] from Figure 8 As can be seen, the field curvature of the meridional and sagittal image planes is controlled within 0~0.06mm, indicating that the optical lens can effectively correct the field curvature.

[0090] Example 3

[0091] Please see Figure 9 The figure shown is a schematic diagram of the structure of the optical lens 300 provided in Embodiment 3 of the present invention. The main difference between this embodiment and Embodiment 1 is that the effective aperture of the stop ST is 0.039mm; the optical parameters such as the radius of curvature and lens thickness of each lens surface are different.

[0092] The relevant parameters of each lens in the optical lens 300 in Example 3 are shown in Table 3-1.

[0093] Table 3-1

[0094] The surface profile parameters of the aspherical lens of the optical lens 300 in Example 3 are shown in Table 3-2.

[0095] Table 3-2

[0096] In this embodiment, the MTF curve, axial aberration curve, and field curvature curve of the optical lens 300 are respectively as follows: Figure 10 , Figure 11 , Figure 12 As shown.

[0097] from Figure 10 As can be seen, from the center to the 60° field of view, the MTF value is controlled above 0.6, and the MTF curve changes smoothly and evenly from the center to the edge of the field of view, indicating that the aberration control is good, the off-axis performance deteriorates slowly, and the optical lens produces clear images across the entire field of view.

[0098] from Figure 11 As can be seen, the axial aberration offset is controlled within -0.01mm to 0.05mm, indicating that the optical lens can effectively correct axial aberration.

[0099] from Figure 12 As can be seen, the field curvature of the meridional and sagittal image planes is controlled within 0~0.06mm, indicating that the optical lens can effectively correct the field curvature.

[0100] Example 4

[0101] Please see Figure 13 The figure shown is a schematic diagram of the structure of the optical lens 400 provided in Embodiment 4 of the present invention. The main difference between this embodiment and Embodiment 1 is that the effective aperture of the stop ST is 0.043mm; the optical parameters such as the radius of curvature and lens thickness of each lens surface are different.

[0102] The relevant parameters of each lens in the optical lens 400 in Example 4 are shown in Table 4-1.

[0103] Table 4-1

[0104] The surface profile parameters of the aspherical lens of the optical lens 400 in Example 4 are shown in Table 4-2.

[0105] Table 4-2

[0106] In this embodiment, the MTF curve, axial aberration curve, and field curvature curve of the optical lens 400 are respectively as follows: Figure 14 , Figure 15 , Figure 16 As shown.

[0107] from Figure 14 As can be seen, from the center to the 60° field of view, the MTF value is controlled above 0.6, and the MTF curve changes smoothly and evenly from the center to the edge of the field of view, indicating that the aberration control is good, the off-axis performance deteriorates slowly, and the optical lens produces clear images across the entire field of view.

[0108] from Figure 15 As can be seen, the axial aberration offset is controlled within -0.02mm to 0.08mm, indicating that the optical lens can effectively correct axial aberration.

[0109] from Figure 16 As can be seen, the field curvature of the meridional and sagittal image planes is controlled within 0~0.06mm, indicating that the optical lens can effectively correct the field curvature.

[0110] Please refer to Table 5 for the optical characteristics corresponding to each of the above embodiments, including the effective focal length f, total optical length TTL, aperture value Fno, true image height IH corresponding to the maximum field of view, maximum field of view FOV, principal ray incident angle CRA at the maximum image height of the optical lens, and the value corresponding to each conditional expression in each embodiment.

[0111] Table 5

[0112] In summary, the optical lens provided by this invention, by setting two groups and using only two sets of lenses and a substrate, not only facilitates the fixation of the optical imaging system but also significantly reduces the overall length of the optical imaging system, achieving lens miniaturization and facilitating mass production. Simultaneously, while maintaining a large field of view, the lens size and aperture are reduced, effectively increasing the depth of field and well meeting the requirements of endoscopic detection range and observation depth. The lens can achieve high-definition imaging within a working object distance from 3mm to infinity, effectively meeting the requirements of endoscopic detection range, observation depth, and clarity.

[0113] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0114] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. An optical lens, characterized in that, Along the optical axis from the object side to the imaging plane, it is composed of a first group with negative optical power, a second group with positive optical power, and a protective glass in sequence; Along the optical axis from the object side to the imaging plane, the first group is sequentially a cemented first lens and a first substrate; the first lens has negative optical power, its object side surface is a concave surface, and its image side surface is a plane; both the object side surface and the image side surface of the first substrate are planes; the object side surface of the first substrate is cemented and fixed to the image side surface of the first lens; Along the optical axis from the object side to the imaging plane, the second group is sequentially a cemented second substrate and a second lens; both the object side surface and the image side surface of the second substrate are planes; the second lens has positive optical power, its object side surface is a plane, and its image side surface is a convex surface; the object side surface of the second lens is cemented and fixed to the image side surface of the second substrate; Wherein, the total optical length TTL of the optical lens and the real image height IH corresponding to the maximum field of view of the optical lens satisfy: 1.5<TTL / IH<2.2; The effective focal length f of the optical lens satisfies: 0.28mm<f<0.36mm; the total optical length TTL of the optical lens satisfies: 0.7mm<TTL<1.1mm; the maximum field of view FOV of the optical lens satisfies: 100°<FOV<125°.

2. The optical lens according to claim 1, characterized in that, The real image height IH corresponding to the maximum field of view of the optical lens and the effective focal length f of the optical lens satisfy: 1.3<IH / f<1.

7.

3. The optical lens according to claim 1, characterized in that, The total optical length TTL of the optical lens and the f-number Fno of the optical lens satisfy: 0.1mm<TTL / Fno<0.3mm.

4. The optical lens according to claim 1, characterized in that, The maximum field of view FOV of the optical lens and the f-number Fno of the optical lens satisfy: 23°<FOV / Fno<26°.

5. The optical lens according to claim 1, characterized in that, The effective focal length f of the optical lens and the focal length f1 of the first lens satisfy: -6.1<f1 / f<-3.3; the radius of curvature R1 of the object side surface of the first lens and the effective focal length f of the optical lens satisfy: -1.5<R1 / f<-0.

2.

6. The optical lens according to claim 1, characterized in that, The effective focal length f of the optical lens and the focal length f2 of the second lens satisfy: 0.9<f2 / f<1; the radius of curvature R6 of the image side surface of the second lens and the effective focal length f of the optical lens satisfy: -0.7<R6 / f<-0.

3.

7. The optical lens according to claim 1, characterized in that, The center thickness CT1 of the first lens and the edge thickness ET1 of the first lens satisfy: 0.3<CT1 / ET1<0.

7.

8. The optical lens according to claim 1, characterized in that, The clear half aperture CSD3 of the image side surface of the first substrate and the clear half aperture CSD4 of the object side surface of the second substrate satisfy: 1.3<CSD3 / CSD4<2.

9. The optical lens according to claim 1, characterized in that, The clear half aperture CSD1 of the object side surface of the first lens and the clear half aperture CSD6 of the image side surface of the second lens satisfy: 1.2<CSD1 / CSD6<2.3.

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