CN117420662A

CN117420662A - Optical lens and camera module

Info

Publication number: CN117420662A
Application number: CN202311717786.4A
Authority: CN
Inventors: 占爽; 王志强; 孙大成; 郭晓凡; 纵莎; 刘国栋
Original assignee: Lianchuang Electronic Technology Co ltd
Current assignee: Lianchuang Electronic Technology Co ltd
Priority date: 2023-12-14
Filing date: 2023-12-14
Publication date: 2024-01-19
Anticipated expiration: 2043-12-14
Also published as: CN117420662B

Abstract

The invention discloses an optical lens and an image pickup module, wherein the optical lens sequentially comprises a first group, a second group and a third group from an object side to an imaging surface along an optical axis; the first group has negative focal power, and consists of a first substrate and a first lens, wherein the object side surface or the image side surface of the first substrate is connected with the first lens in a gluing way; the second group has positive focal power and sequentially comprises a second substrate and a second lens which are connected in a gluing way from the object side to the imaging surface along the optical axis; the third group has optical power and consists of a third lens and a third substrate which are connected in a gluing way in sequence from the object side to the imaging surface along the optical axis; and the object side surface or the image side surface of the first substrate or the second substrate is plated with a diaphragm. The optical lens provided by the invention reduces the size and caliber of the lens while meeting the requirement of a large field angle, effectively increases the depth of field of the lens, and can well meet the requirements of the detection range and the observation depth of an endoscope.

Description

Optical lens and camera module

Technical Field

The present invention relates to the field of optical imaging technology, and in particular, to an optical lens and an imaging module.

Background

In recent years, with the rapid development of the medical field, the requirements of society on medical equipment are increasing, and in particular, the requirements on the performance of cameras mounted on medical detection equipment are increasing, for example, in order to more flexibly and comprehensively enter a human body to collect images, medical equipment such as an endoscope and the like carrying an imaging lens is generally adopted to perform the examination of various intracavity diseases such as gastrointestinal tract, pancreas, biliary tract, respiratory tract and the like so as to determine the internal structure of the human body or observe pathological states.

Currently, in the market, endoscope lenses generally have problems of oversized size, small angle of view and insufficient depth of field, such as: the oversized endoscope can cause discomfort to a human body when the endoscope is used, the small angle of view can cause the scope of observation of the endoscope lens to be insufficient, and the small depth of field can influence the depth of observation of the endoscope lens.

Disclosure of Invention

Therefore, the invention aims to provide an optical lens and an imaging module, which at least have the characteristics of small size, small caliber, large field of view and large depth of field.

The embodiment of the invention realizes the aim through the following technical scheme.

In one aspect, the present invention provides an optical lens, which sequentially comprises a first group, a second group, and a third group from an object side to an imaging plane along an optical axis; the first group has negative focal power, and consists of a first substrate and a first lens, wherein the object side surface or the image side surface of the first substrate is connected with the first lens in a gluing way; the second group has positive focal power and sequentially comprises a second substrate and a second lens which are connected in a gluing way from the object side to the imaging surface along the optical axis; the third group has optical power and consists of a third lens and a third substrate which are connected in a gluing way in sequence from the object side to the imaging surface along the optical axis; a diaphragm is plated on the object side surface or the image side surface of the first substrate or the second substrate; wherein, the optical lens satisfies the conditional expression: 1.2mm/rad < TTL/theta <1.8mm/rad, H <1mm, TTL represents the distance from the object side surface of the first group to the imaging surface on the optical axis, theta represents the maximum half field angle of the optical lens, and H represents the image height corresponding to the maximum field angle of the optical lens.

In some embodiments, the second group further includes a fourth lens, and an image side surface of the fourth lens is glued to an object side surface of the second substrate.

In some embodiments, the means for glue bonding includes nano-imprinting means or etching means.

In some embodiments, the first lens has a negative optical power; the second lens has positive optical power; the image side surface of the second lens is a convex surface.

In some embodiments, the optical lens satisfies the following conditional expression: 0.09mm < F/f# <0.13mm, wherein F represents an effective focal length of the optical lens and f# represents an aperture value of the optical lens.

In some embodiments, -5<f _Q1 /f<-0.5, where f _Q1 Representing the effective focal length of the first group, f representing the effective focal length of the optical lens.

In some embodiments, the optical lens satisfies the following conditional expression: 0.2<f _Q2 /f<1.2, wherein f _Q2 Representing an effective focal length of the second group, f representing an effective focal length of the optical lens.

In some embodiments, the optical lens satisfies the following conditional expression: -7<f _Q1 /f _Q2 <-1, wherein f _Q1 Representing the effective focal length, f, of the first group _Q2 Representing the effective focal length of the second group.

In some embodiments, the optical lens satisfies the following conditional expression: -1<f _Q2 /f _Q3 <0.1, wherein f _Q2 Representing the effective focal length of the second group, f _Q3 Representing the effective focal length of the third group.

In some embodiments, the optical lens satisfies the following conditional expression: 0.25< CT23/TTL <0.5,3< CT23/CT12<50, wherein CT12 represents an air separation distance of the first group and the second group on the optical axis, CT23 represents an air separation distance of the second group and the third group on the optical axis, and TTL represents a distance of an object side surface to an imaging surface of the first group on the optical axis.

In some implementations, the third group has negative optical power, and the object-side surface of the third lens is concave.

In some implementations, the third group has positive optical power, and the object-side surface of the third lens is convex.

On the other hand, the invention also provides an image pickup module, which comprises the optical lens and the imaging element, wherein the imaging element is used for converting an optical image formed by the optical lens into an electric signal.

Compared with the prior art, the optical lens provided by the invention adopts three groups of lens groups formed by bonding the substrate and the lens, and the focal power and the surface type collocation of each lens group are reasonably arranged, so that the lens size and the caliber are reduced to a certain extent while the large angle of view is met, the depth of field of the lens is effectively increased, and the requirements of the endoscope on the detection range and the observation depth can be well met.

Drawings

The foregoing and/or additional aspects and advantages of the present invention will be apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings.

Fig. 1 is a schematic structural diagram of an optical lens according to a first embodiment of the present invention;

FIG. 2 is a graph showing the MTF of an optical lens according to a first embodiment of the present invention;

FIG. 3 is a graph showing axial chromatic aberration of an optical lens according to a first embodiment of the present invention;

FIG. 4 is a schematic diagram of an optical lens according to a second embodiment of the present invention;

FIG. 5 is a graph showing the MTF of an optical lens according to a second embodiment of the present invention;

FIG. 6 is a graph showing axial chromatic aberration of an optical lens according to a second embodiment of the present invention;

FIG. 7 shows a third embodiment of the present invention is a schematic structural diagram of the optical lens;

FIG. 8 is a graph showing the MTF of an optical lens according to a third embodiment of the present invention;

FIG. 9 is a graph showing axial chromatic aberration of an optical lens according to a third embodiment of the present invention;

fig. 10 is a schematic structural diagram of an optical lens according to a fourth embodiment of the present invention;

FIG. 11 is a graph showing the MTF of an optical lens according to a fourth embodiment of the present invention;

FIG. 12 is a fourth embodiment of the present invention axial chromatic aberration curve graph of the optical lens;

fig. 13 is a schematic structural diagram of an optical lens according to a fifth embodiment of the present invention;

fig. 14 is an MTF graph of an optical lens according to a fifth embodiment of the present invention;

FIG. 15 is a graph showing axial chromatic aberration of an optical lens according to a fifth embodiment of the present invention;

fig. 16 is a schematic structural view of an optical lens according to a sixth embodiment of the present invention;

fig. 17 is an MTF graph of an optical lens according to a sixth embodiment of the present invention;

FIG. 18 is a graph showing axial chromatic aberration of an optical lens according to a sixth embodiment of the present invention;

fig. 19 is a schematic structural diagram of an image capturing module according to a seventh embodiment of the present invention.

Detailed Description

In order that the objects, features and advantages of the invention will be readily understood, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. Several embodiments of the invention are presented in the figures. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Like reference numerals refer to like elements throughout the specification.

Furthermore, the terms "first," "second," "third," and the like, are used primarily to distinguish between different devices, elements or components (the particular species and configurations may be the same or different), and are not used to indicate or imply relative importance and amounts of the indicated devices, elements or components.

In this context, near the optical axis means the area near the optical axis. If the lens surface is convex and the convex position 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 concave position is not defined, it means that the lens surface is concave at least in the paraxial region.

The invention provides an optical lens which sequentially comprises a first group, a second group and a third group from an object side to an imaging surface along an optical axis.

The first group has negative focal power, and consists of a first substrate and a first lens, wherein the object side surface or the image side surface of the first substrate is connected with the first lens in a gluing way; the surface of the first lens glued with the first substrate is a plane.

The second group has positive focal power and sequentially comprises a second substrate and a second lens which are connected in a gluing way from the object side to the imaging surface along the optical axis. The second lens is glued on the image side surface of the second substrate; the surface of the second lens glued with the second substrate is a plane. In some embodiments, the second group further includes a fourth lens, and an image side surface of the fourth lens is glued to an object side surface of the second substrate; lenses are respectively arranged on the two surfaces of the second substrate, so that high-quality imaging of the lens can be better ensured. The surfaces of the second lens and the fourth lens, which are glued with the second substrate, are plane surfaces.

The third group has negative focal power or positive focal power, and consists of a third lens and a third substrate which are connected in a gluing way sequentially from the object side to the imaging surface along the optical axis; the surface of the third lens glued with the third substrate is a plane.

In some embodiments, the third group hasThe object side surface of the third lens is a concave surface. Further, the optical lens satisfies the following conditional expression: f (f) _Q3 /f<-1, wherein f _Q3 Representing an effective focal length of the third group, f representing an effective focal length of the optical lens. The third group can better control the angle of light incident to the image plane and can better match the imaging chip.

In other embodiments, the third group has positive optical power, and the object-side surface of the third lens is convex. Further, the optical lens satisfies the following conditional expression: f (f) _Q3 /f>10, wherein f _Q3 Representing an effective focal length of the third group, f representing an effective focal length of the optical lens. The tolerance sensitivity of the third group can be reasonably controlled to improve the processability of the lens when the conditions are met.

The first substrate, the second substrate and the third substrate can be glass substrates or plastic substrates with certain thickness and width, and the widths (effective caliber) of the first substrate, the second substrate and the third substrate in the direction perpendicular to the optical axis are larger than the effective caliber of the glued lens, so that a stable forming environment can be provided for each lens, and meanwhile, the connection and the assembly between different subsequent groups are facilitated. The third substrate is simultaneously multiplexed into the protective glass or the optical filter, which is favorable for further reducing the thickness of the lens and realizing the small volume of the lens.

More specifically, the thicknesses of the first substrate, the second substrate and the third substrate can be selected to be 0.02mm-0.3mm, and the maximum effective caliber of the first substrate, the second substrate and the third substrate is smaller than 1.1mm, but the effective calibers of the first substrate, the second substrate and the third substrate are larger than the effective calibers of the lenses, so that the first substrate, the second substrate and the third substrate have better supporting and stabilizing effects for the lenses.

The lenses are connected with the substrate in a gluing mode, specifically, the first lens, the second lens, the third lens and the fourth lens can be fixed on the first substrate, the second substrate and the third substrate in a nano imprinting or etching mode, so that the processing precision and the stability of the lenses can be ensured, and the miniaturization of the optical lens is realized.

The optical lens adopts a processing mode of embossing or etching a lens structure on the first, second and third glass or plastic substrates, and can realize wide angle and miniaturization of the lens and ensure that the lens has the characteristic of large depth of field. Preferably, the first lens, the second lens, the third lens and the fourth lens all adopt a photoresist imprinting mode, the glued surface of the lens and the substrate is a plane, the surface of the lens far away from the substrate can be a spherical surface or an aspherical surface, and an aspherical lens is preferably adopted, so that the manufacturing cost can be effectively reduced, the weight is reduced, more excellent imaging effect can be provided, and the optical performance is more excellent.

The diaphragm is plated on the object side surface or the image side surface of the first substrate or the second substrate, and the diaphragm limits the aperture of the size of the incident light beam, so that the size and the position of the diaphragm have decisive effects on the definition, the imaging range and the brightness of the imaging of the lens. In order to better control the intensity of the incident light, a diaphragm is arranged on the object side surface or the image side surface of the first substrate or the second substrate in a film plating mode, and the gluing effect of the lens and the first substrate or the second substrate is not affected because the diaphragm film layer is very thin. In order to better play a role in converging the incident light, the effective aperture value of the diaphragm is set to be smaller, for example, may be 0.1mm or 0.12mm,0.15mm or other values, and the setting is specifically performed according to the actual situation, and the embodiment is not limited specifically.

Because the optical lens provided by the invention has smaller overall size, the processing difficulty of a single lens and the lens assembly are larger according to the conventional mode, and the processing precision cannot be ensured, the widths of the first substrate, the second substrate and the third substrate are larger by arranging the lenses on the first substrate, the second substrate and the third substrate in a gluing way, so that a stable supporting effect can be provided for the positions of the lenses, and meanwhile, the first substrate, the second substrate and the third substrate only need to be fixed according to the preset space during the lens assembly, the respective installation errors among a plurality of lenses do not need to be considered, the overall processing sensitivity is reduced, and the processability is improved.

In some embodiments, the image side of the second lens element is convex, the object side of the third lens element is concave or convex, and the object side of the fourth lens element is concave.

In some embodiments, the optical lens satisfies the following conditional expression: 1.2mm/rad < TTL/theta <1.8mm/rad, H <1mm, TTL represents the distance from the object side surface of the first group to the imaging surface on the optical axis, theta represents the maximum half field angle of the optical lens, and H represents the image height corresponding to the maximum field angle of the optical lens. The optical lens has smaller total optical length and larger angle of view, and has larger imaging surface, so that the balance of small size, large visual angle and high pixels of the lens can be better realized.

In some embodiments, the optical lens satisfies the following conditional expression: 0.09mm < F/f# <0.13mm, wherein F represents an effective focal length of the optical lens and f# represents an aperture value of the optical lens. The optical lens has a sufficiently large depth of field range, can realize clear imaging on an image plane when the object distance is 5mm to infinity, and is beneficial to enlarging the observation depth and detection range of the lens in the use process.

In some embodiments, the optical lens satisfies the following conditional expression: -5<f _Q1 /f<-0.5, where f _Q1 Representing the effective focal length of the first group, f representing the effective focal length of the optical lens. The first group has reasonable negative focal power, is favorable for collecting incident light in a large field of view, is favorable for increasing the field angle of the lens, and realizes a larger observation range.

In some embodiments, the optical lens satisfies the following conditional expression: 0.2<f _Q2 /f<1.2, wherein f _Q2 Representing an effective focal length of the second group, f representing an effective focal length of the optical lens. The conditions are met, so that the second group has larger positive focal power, light is converged, the correction difficulty of aberration and distortion is reduced, and the overall imaging quality is improved.

In some embodimentsWherein, the optical lens satisfies the following conditional expression: -7<f _Q1 /f _Q2 <-1, wherein f _Q1 Representing the effective focal length, f, of the first group _Q2 Representing the effective focal length of the second group. The lens has the advantages that the positive and negative focal power collocations of the first group and the second group are reasonably set, so that the lens performance and imaging quality are improved, the total length of the lens is controlled, the tolerance sensitivity of the lens is reduced, and the lens is processed.

In some embodiments, the optical lens satisfies the following conditional expression: -1<f _Q2 /f _Q3 <0.1, wherein f _Q2 Representing the effective focal length of the second group, f _Q3 Representing the effective focal length of the third group. The imaging chip has the advantages that the angle of incidence of light on the image surface can be better controlled by reasonably setting the focal power collocation of the second group and the third group, so that the CRA of the imaging chip is matched, the chip performance is fully utilized, and the image quality is improved.

In some embodiments, the optical lens satisfies the following conditional expression: 0.25< CT23/TTL <0.5,3< CT23/CT12<50, wherein CT12 represents an air separation distance of the first group and the second group on the optical axis, CT23 represents an air separation distance of the second group and the third group on the optical axis, and TTL represents a distance of an object side surface to an imaging surface of the first group on the optical axis. The above conditions are met, a larger interval distance can be formed between the second group and the third group, so that the convergence of light rays is realized conveniently, the correction difficulty of aberration is reduced, the overall imaging quality is improved, meanwhile, the larger interval distance is beneficial to lens molding and assembly, and the product yield is ensured.

In some embodiments, the optical lens satisfies the following conditional expression: 0.95< D/H <1.1, wherein D represents the maximum effective caliber of the first substrate, the second substrate and the third substrate, and H represents the image height corresponding to the maximum field angle of the optical lens. Because each lens is glued on the first substrate, the second substrate and the third substrate, and the effective caliber of each lens is smaller than the caliber of each substrate, the conditions are met, the lens is ensured to have smaller external caliber and reduced volume, the field angle of the lens is increased, the imaging range of the lens is enlarged, and a larger observation range is realized. In some embodiments, the mechanical calibers of the first substrate, the second substrate and the third substrate are equal, which is beneficial to processing and assembling the components of each group (including the substrate and the lens) into the lens, and improves the assembly yield.

In some embodiments, the optical lens satisfies the following conditional expression: 0.18mm<CT _Q1 <0.6mm，0.05mm<CT _Q2 <0.4mm，0.3mm<CT _Q3 <0.5mm, wherein CT _Q1 Representing the central thickness of the first group on the optical axis, CT _Q2 Representing the center thickness of the second group on the optical axis, CT _Q3 Representing the center thickness of the third group on the optical axis. The lens meets the conditions, is beneficial to realizing miniaturization of the lens, is beneficial to molding and assembling of the lens, and ensures the yield of products.

In some embodiments, the optical lens satisfies the following conditional expression: 1.0< TTL/D <1.8, wherein TTL represents the distance from the object side surface to the imaging surface of the first group on the optical axis, and D represents the maximum effective caliber of the first substrate, the second substrate and the third substrate. The above conditions are satisfied, the volume of the whole optical lens can be controlled in a smaller range, and miniaturization of the lens can be well realized.

In some embodiments, the maximum field angle of the optical lens is 112 ° < FOV <140 °, and the total optical length of the optical lens is 1.2mm < ttl <1.8 mm.

The optical lens provided by the invention adopts three groups of lens groups glued by the substrate and the lens, and by reasonably setting the focal power and the surface type collocation of each lens group, the lens has a large field angle (FOV can reach 120 degrees) and smaller total length (TTL <1.8 mm), meanwhile, the depth of field of the lens is effectively increased, the lens can realize high-definition imaging in 5mm to infinite working object distance, and the requirements of the endoscope detection range, observation depth and definition can be well met.

In the embodiments of the present invention, when the lens surface type in the optical lens is an aspherical surface, the aspherical surface type of each lens satisfies the following equation:

where z is the distance sagittal height from the aspherical surface vertex when the aspherical surface is at a position of height h in the optical axis direction, c is the paraxial curvature of the surface, k is the quadric coefficient, A _2i The aspherical surface profile coefficient of the 2 i-th order.

The invention is further illustrated in the following examples. In various embodiments, the thickness, radius of curvature, and material selection portion of each lens in the optical lens may vary, and for specific differences, reference may be made to the parameter tables of the various embodiments. The following examples are merely preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the following examples, and any other changes, substitutions, combinations or simplifications that do not depart from the gist of the present invention are intended to be equivalent substitutes within the scope of the present invention.

First embodiment

Referring to fig. 1, a schematic structural diagram of an optical lens 100 according to a first embodiment of the present invention is shown, where the optical lens 100 includes, in order from an object side to an imaging plane along an optical axis: a first group Q1 having negative power, a second group Q2 having positive power, and a third group Q3 having negative power.

The first group Q1 includes, in order from the object side to the imaging plane along the optical axis, a first lens L1 and a first substrate G1. The thickness of the first substrate G1 in the optical axis direction is 0.175mm, and the object side surface S2 and the image side surface S3 of the first substrate G1 are both planar. The diaphragm ST is plated on the image side surface S3 of the first substrate G1 in a film plating mode, and the effective caliber of the diaphragm ST is 0.12mm. The first lens L1 has negative optical power, the object-side surface S1 of the first lens L1 is concave, the image-side surface is planar, and the image-side surface of the first lens L1 is bonded on the object-side surface S2 of the first substrate G1 by nano imprinting.

The second group Q2 includes a second substrate G2 and a second lens L2 in order from the object side to the imaging surface along the optical axis. The thickness of the second substrate G2 in the optical axis direction is 0.026mm, and the object side surface S6 and the image side surface S7 of the second substrate G2 are both planar. The second lens L2 has positive optical power, the object-side surface of the second lens L2 is a plane, the image-side surface S8 is a convex surface, and the object-side surface of the second lens L2 is glued on the image-side surface S7 of the second substrate G2 by nano imprinting.

The third group Q3 includes a third lens L3 and a third substrate G3 in order from the object side to the imaging surface along the optical axis. The thickness of the third substrate G3 in the optical axis direction is 0.3mm, and the object side surface S10 and the image side surface S11 of the third substrate G3 are both flat surfaces. The third lens element L3 has negative refractive power, wherein an object-side surface S9 of the third lens element L3 is concave, and an image-side surface is planar, and the image-side surface of the third lens element L3 is bonded to the object-side surface S10 of the third substrate G3 by nanoimprinting.

The first substrate G1, the second substrate G2 and the third substrate G3 are made of glass materials, so that imprinting of the lens and assembly of the lens can be better realized.

The object-side surface S1 of the first lens element L1, the image-side surface S8 of the second lens element L2, and the object-side surface S9 of the third lens element L3 are aspheric. The first lens L1, the second lens L2 and the third lens L3 are made of plastic materials which are convenient to produce, so that the nanoimprint lens is convenient to form on one hand, and the volume and the weight of the lens can be reduced on the other hand.

The relevant parameters of each lens in the optical lens 100 provided in this embodiment are shown in table 1.

TABLE 1

The surface profile coefficients of the aspherical surfaces of the optical lens 100 in this embodiment are shown in table 2.

TABLE 2

In the present embodiment, graphs of MTF and axial chromatic aberration of the optical lens 100 are shown in fig. 2 and 3, respectively.

In fig. 2, the MTF curve represents the degree of modulation of lens imaging at a frequency of 75lp/mm at different fields of view, the horizontal axis represents the angle of view (in degrees), and the vertical axis represents the MTF value. As can be seen from the figure, the MTF values of the optical lens 100 in the present embodiment are all above 0.6 in the full field of view, and the MTF curves are approximately horizontal in the process from the center to the edge field of view, which indicates that the optical lens 100 has better imaging quality and better detail resolution under the full field of view.

The axial chromatic aberration curves of fig. 3 represent aberrations at different wavelengths on the optical axis at the imaging plane, with the horizontal axis representing the offset (in millimeters) and the vertical axis representing the normalized pupil radius. As can be seen from fig. 3, the offset amount of the axial chromatic aberration is controlled within ±0.08 mm, which indicates that the optical lens 100 can effectively correct the aberration of the fringe field of view.

Second embodiment

Referring to fig. 4 for a schematic structural diagram of an optical lens 200 according to the present embodiment, the optical lens 200 in the present embodiment is substantially the same as the optical lens 100 in the first embodiment, and is different in the setting position of the diaphragm ST, and the curvature radius, the aspheric coefficient, the thickness of the substrate, and the like of each lens surface are different. Specifically, the stop ST in the optical lens 200 in the present embodiment is disposed on the image side surface S7 of the second substrate G2. The relevant parameters of each lens in the optical lens 200 provided in this embodiment are shown in table 3.

TABLE 3 Table 3

The surface profile coefficients of the aspherical surfaces of the optical lens 200 in this embodiment are shown in table 4.

TABLE 4 Table 4

In the present embodiment, graphs of MTF and axial chromatic aberration of the optical lens 200 are shown in fig. 5 and 6, respectively.

As can be seen from fig. 5, the MTF values of the optical lens 200 in the present embodiment are all above 0.55 in the full field of view, and the MTF curves are approximately horizontal in the process from the center to the edge field of view at the frequency of 75lp/mm, which indicates that the optical lens 200 has better imaging quality and better detail resolution in the full field of view.

As can be seen from fig. 6, the offset amount of the axial chromatic aberration is controlled within ±0.06 millimeters, indicating that the optical lens 200 can effectively correct the aberration of the fringe field of view.

Third embodiment

Referring to fig. 7, the structure of the optical lens 300 in the present embodiment is substantially the same as that of the first embodiment, and the difference is mainly that the positions of the first lens L1 and the stop ST are different, and the curvature radius, the aspheric coefficient, the thickness of the substrate, and the like of the lens surfaces are different. Specifically, the optical lens 300 includes, in order from the object side to the imaging plane along the optical axis: a first group Q1 having negative power, a second group Q2 having positive power, and a third group Q3 having negative power.

The first group Q1 includes, in order from the object side to the imaging plane along the optical axis, a first substrate G1 and a first lens L1. The thickness of the first substrate G1 in the optical axis direction is 0.3mm, and the object side surface S2 and the image side surface S3 of the first substrate G1 are both planar. The first lens L1 has negative optical power, the object-side surface of the first lens L1 is a plane, the image-side surface S4 is a concave surface, and the object-side surface of the first lens L1 is glued on the image-side surface S3 of the first substrate G1 by nano imprinting.

The second group Q2 includes a second substrate G2 and a second lens L2 in order from the object side to the imaging surface along the optical axis. The thickness of the second substrate G2 in the optical axis direction is 0.025mm, and the object side surface S6 and the image side surface S7 of the second substrate G2 are both planar. The second lens L2 has positive optical power, the object-side surface of the second lens L2 is a plane, the image-side surface S8 is a convex surface, and the object-side surface of the second lens L2 is glued on the image-side surface S7 of the second substrate G2 by nano imprinting. The diaphragm ST is plated on the object side surface S6 of the second substrate G2 by a plating method.

The image side surface S4 of the first lens element L1, the image side surface S8 of the second lens element L2, and the object side surface S9 of the third lens element L3 are aspheric. The first lens L1, the second lens L2 and the third lens L3 are made of plastic materials which are convenient to produce, so that the nanoimprint lens is convenient to form on one hand, and the volume and the weight of the lens can be reduced on the other hand.

The relevant parameters of each lens in the optical lens 300 provided in this embodiment are shown in table 5.

TABLE 5

The surface profile coefficients of the aspherical surfaces of the optical lens 300 in this embodiment are shown in table 6.

TABLE 6

In the present embodiment, graphs of MTF and axial chromatic aberration of the optical lens 300 are shown in fig. 8 and 9, respectively.

As can be seen from fig. 8, the MTF values of the optical lens 300 in the present embodiment are all above 0.5 in the full field of view, and the MTF curves are approximately horizontal in the process from the center to the edge field of view at the frequency of 75lp/mm, which indicates that the optical lens 300 has better imaging quality and better detail resolution in the full field of view.

As can be seen from fig. 9, the offset amount of the axial chromatic aberration is controlled within ±0.1mm, indicating that the optical lens 300 can effectively correct the aberration of the fringe field of view.

Fourth embodiment

Referring to fig. 10 for a schematic structural diagram of an optical lens 400 provided in the present embodiment, the optical lens 400 in the present embodiment is substantially the same as the optical lens 300 in the third embodiment, and is different in that the third group Q3 has positive optical power, the diaphragm ST is disposed on the image side surface S7 of the second substrate G2, and the curvature radius, the aspheric coefficient, the thickness of the substrate, and the like of each lens surface are different.

Specifically, the optical lens 400 includes, in order from an object side to an imaging surface along an optical axis: a first group Q1 having negative power, a second group Q2 having positive power, and a third group Q3 having positive power.

The first group Q1 includes, in order from the object side to the imaging plane along the optical axis, a first substrate G1 and a first lens L1. The thickness of the first substrate G1 in the optical axis direction is 0.201mm, and the object side surface S2 and the image side surface S3 of the first substrate G1 are both planar. The first lens L1 has negative optical power, the object-side surface of the first lens L1 is a plane, the image-side surface S4 is a concave surface, and the object-side surface of the first lens L1 is glued on the image-side surface S3 of the first substrate G1 by nano imprinting.

The second group Q2 includes a second substrate G2 and a second lens L2 in order from the object side to the imaging surface along the optical axis. The thickness of the second substrate G2 in the optical axis direction is 0.025mm, and the object side surface S6 and the image side surface S7 of the second substrate G2 are both planar. The second lens L2 has positive optical power, the object-side surface of the second lens L2 is a plane, the image-side surface S8 is a convex surface, and the object-side surface of the second lens L2 is glued on the image-side surface S7 of the second substrate G2 by nano imprinting. The diaphragm ST is coated on the image side surface S7 of the second substrate G2 by a coating method.

The third group Q3 includes a third lens L3 and a third substrate G3 in order from the object side to the imaging surface along the optical axis. The thickness of the third substrate G3 in the optical axis direction is 0.3mm, and the object side surface S10 and the image side surface S11 of the third substrate G3 are both flat surfaces. The third lens element L3 has positive refractive power, wherein an object-side surface S9 of the third lens element L3 is convex, and an image-side surface S10 of the third substrate G3 is bonded to the image-side surface of the third lens element L3 by nanoimprinting.

The relevant parameters of each lens in the optical lens 400 provided in this embodiment are shown in table 7.

TABLE 7

The surface profile coefficients of the aspherical surfaces of the optical lens 400 in this embodiment are shown in table 8.

TABLE 8

In the present embodiment, graphs of MTF and axial chromatic aberration of the optical lens 400 are shown in fig. 11 and 12, respectively.

As can be seen from fig. 11, the MTF values of the optical lens 400 in the present embodiment are all above 0.6 in the full field of view, and the MTF curves are approximately horizontal in the process from the center to the edge field of view at the frequency of 75lp/mm, which indicates that the optical lens 400 has better imaging quality and better detail resolution in the full field of view.

As can be seen from fig. 12, the offset amount of the axial chromatic aberration is controlled within ±0.06 millimeters, indicating that the optical lens 400 can effectively correct the aberration of the fringe field of view.

Fifth embodiment

Referring to fig. 13, a schematic structural diagram of an optical lens 500 according to a fifth embodiment of the present invention is shown, where the optical lens 500 includes, in order from an object side to an imaging plane along an optical axis: a first group Q1 having negative power, a second group Q2 having positive power, and a third group Q3 having negative power.

The first group Q1 includes, in order from the object side to the imaging plane along the optical axis, a first substrate G1 and a first lens L1. The thickness of the first substrate G1 in the optical axis direction was 0.247mm, and the object side surface S2 and the image side surface S3 of the first substrate G1 were both planar. The first lens L1 has negative optical power, the object-side surface of the first lens L1 is a plane, the image-side surface S4 is a concave surface, and the object-side surface of the first lens L1 is glued on the image-side surface S3 of the first substrate G1 by nano imprinting.

The second group Q2 includes, in order from the object side to the imaging surface along the optical axis, a fourth lens L4, a second substrate G2, and a second lens L2. The thickness of the second substrate G2 in the optical axis direction is 0.027mm, and the object side surface S6 and the image side surface S7 of the second substrate G2 are both planar. The second lens L2 has positive focal power, the object side surface of the second lens L2 is a plane, and the image side surface S8 is a convex surface; the fourth lens L4 has negative focal power, the object side surface of the fourth lens is a concave surface S5, and the image side surface of the fourth lens is flat; the image side surface of the fourth lens element and the object side surface of the second lens element L2 are respectively bonded to the object side surface S6 and the image side surface S7 of the second substrate G2 by nanoimprinting. The diaphragm ST is plated on the object side surface S6 of the second substrate G2 by a plating method.

The third group Q3 includes a third lens L3 and a third substrate G3 in order from the object side to the imaging surface along the optical axis. The thickness of the third substrate G3 in the optical axis direction is 0.3mm, and the object side surface S10 and the image side surface S11 of the third substrate G3 are both flat surfaces. The third lens element L3 has negative refractive power, wherein an object-side surface of the third lens element L3 is concave, and an image-side surface of the third lens element L3 is planar, and the image-side surface of the third lens element L3 is bonded to the object-side surface S10 of the third substrate G3 by nanoimprinting.

The image side surface S4 of the first lens element L1, the image side surface S8 of the second lens element L2, the object side surface S9 of the third lens element L3 and the object side surface S5 of the fourth lens element L4 are aspheric. The first lens L1, the second lens L2, the third lens L3 and the fourth lens L4 are made of plastic materials which are convenient to produce, so that the nanoimprint lens is convenient to form on one hand, and the volume and the weight of the lens can be reduced on the other hand.

The relevant parameters of each lens in the optical lens 500 provided in this embodiment are shown in table 9.

TABLE 9

The surface profile coefficients of the aspherical surfaces of the optical lens 500 in this embodiment are shown in table 10.

Table 10

In the present embodiment, graphs of MTF and axial chromatic aberration of the optical lens 500 are shown in fig. 14 and 15, respectively.

As can be seen from fig. 14, the MTF values of the optical lens 500 in the present embodiment are all above 0.55 in the full field of view, and the MTF curves are approximately horizontal in the process from the center to the edge field of view at the frequency of 75lp/mm, which indicates that the optical lens 500 has better imaging quality and better detail resolution in the full field of view.

As can be seen from fig. 15, the offset amount of the axial chromatic aberration is controlled within ±0.05 mm, indicating that the optical lens 500 can effectively correct the aberration of the fringe field of view.

Sixth embodiment

Referring to fig. 16, the optical lens 600 of the present embodiment is substantially the same as the optical lens 500 of the fifth embodiment in terms of the configuration of the optical lens 600, and is different in terms of the setting position of the diaphragm ST and the difference in the radius of curvature, aspheric coefficients, thickness of the substrate, etc. of the lens surfaces. Specifically, the stop ST in the optical lens 600 in the present embodiment is disposed on the image side surface S7 of the second substrate G2. The relevant parameters of each lens in the optical lens 600 provided in this embodiment are shown in table 11.

TABLE 11

The surface profile coefficients of the aspherical surfaces of the optical lens 600 in this embodiment are shown in table 12.

Table 12

In the present embodiment, graphs of MTF and axial chromatic aberration of the optical lens 600 are shown in fig. 17 and 18, respectively.

As can be seen from fig. 17, the MTF values of the optical lens 600 in the present embodiment are all above 0.55 in the full field of view, and the MTF curves are approximately horizontal in the process from the center to the edge field of view at the frequency of 75lp/mm, which indicates that the optical lens 600 has better imaging quality and better detail resolution in the full field of view.

As can be seen from fig. 18, the shift amount of the axial chromatic aberration is controlled within ±0.07 millimeters, indicating that the optical lens 600 can effectively correct the aberration of the fringe field of view.

Referring to table 13, the correlation values of the optical lenses provided in the above six embodiments and each of the above conditional expressions are shown.

TABLE 13

Seventh embodiment

Referring to fig. 19, a seventh embodiment of the present invention provides an image capturing module 700, where the image capturing module 700 may include an imaging element 710 and an optical lens (e.g., the optical lens 100) according to any of the above embodiments. The imaging element 710 may be a CMOS (Complementary Metal Oxide Semiconductor ) image sensor, or a CCD (Charge Coupled Device, charge coupled device) image sensor.

The imaging module 700 may be any of a medical endoscope, an industrial endoscope, a capsule lens, and a camera equipped with the optical lens 100.

The image pickup module 700 provided in this embodiment includes the optical lens in any of the above embodiments, and because of the characteristics of small size, small caliber and large field of view of the optical lens, the image pickup module 700 with the optical lens also has the advantages of small size, small caliber and large field of view, and can well meet the requirements of the endoscope detection range and the observation depth.

In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The foregoing examples illustrate only a few embodiments of the invention and are described in detail herein without thereby limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.

Claims

1. An optical lens is characterized by comprising a first group, a second group and a third group in sequence from an object side to an imaging surface along an optical axis;

the first group has negative focal power, and consists of a first substrate and a first lens, wherein the object side surface or the image side surface of the first substrate is connected with the first lens in a gluing way;

the second group has positive focal power and sequentially comprises a second substrate and a second lens which are connected in a gluing way from the object side to the imaging surface along the optical axis;

the third group has optical power and consists of a third lens and a third substrate which are connected in a gluing way in sequence from the object side to the imaging surface along the optical axis;

a diaphragm is plated on the object side surface or the image side surface of the first substrate or the second substrate;

wherein, the optical lens satisfies the conditional expression: 1.2mm/rad < TTL/theta <1.8mm/rad, H <1mm, TTL represents the distance from the object side surface of the first group to the imaging surface on the optical axis, theta represents the maximum half field angle of the optical lens, and H represents the image height corresponding to the maximum field angle of the optical lens.

2. The optical lens of claim 1, wherein the second group further comprises a fourth lens element, and wherein an image side of the fourth lens element is bonded to an object side of the second substrate.

3. The optical lens of claim 1, wherein the first lens has a negative optical power; the second lens has positive optical power; the image side surface of the second lens is a convex surface.

4. The optical lens according to claim 1, wherein the optical lens satisfies a conditional expression: 0.09mm < F/f# <0.13mm, wherein F represents an effective focal length of the optical lens and f# represents an aperture value of the optical lens.

5. The optical lens according to claim 1, wherein the optical lens satisfies a conditional expression: -5<f _Q1 /f<-0.5, where f _Q1 Representing the effective focal length of the first group, f representing the effective focal length of the optical lens.

6. The optical lens according to claim 1, wherein the optical lens satisfies a conditional expression: 0.2<f _Q2 /f<1.2, wherein f _Q2 Representing an effective focal length of the second group, f representing an effective focal length of the optical lens.

7. The optical lens according to claim 1, wherein the optical lens satisfies a conditional expression: -7<f _Q1 /f _Q2 <-1, wherein f _Q1 Representing the effective focal length, f, of the first group _Q2 Representing the effective focal length of the second group.

8. The optical lens according to claim 1, wherein the optical lens satisfies a conditional expression: -1<f _Q2 /f _Q3 <0.1, wherein f _Q2 Representing the effective focal length of the second group, f _Q3 Representing the effective focal length of the third group.

9. The optical lens according to claim 1, wherein the optical lens satisfies a conditional expression: 0.25< CT23/TTL <0.5,3< CT23/CT12<50, wherein CT12 represents an air separation distance of the first group and the second group on the optical axis, CT23 represents an air separation distance of the second group and the third group on the optical axis, and TTL represents a distance of an object side surface to an imaging surface of the first group on the optical axis.

10. The optical lens of claim 1, wherein the third group has negative optical power and the object-side surface of the third lens is concave.

11. The optical lens of claim 1, wherein the third group has positive optical power and an object-side surface of the third lens is convex.

12. An imaging module comprising the optical lens of any one of claims 1-11 and an imaging element for converting an optical image formed by the optical lens into an electrical signal.