CN116009220A - Optical lens and camera module - Google Patents
Optical lens and camera module Download PDFInfo
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- CN116009220A CN116009220A CN202310294290.4A CN202310294290A CN116009220A CN 116009220 A CN116009220 A CN 116009220A CN 202310294290 A CN202310294290 A CN 202310294290A CN 116009220 A CN116009220 A CN 116009220A
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Abstract
The invention discloses an optical lens and an imaging module, which sequentially comprise from an object side to an imaging surface along an optical axis: a first group, a second group, and a third group; the first group has positive focal power and sequentially comprises a first substrate and a first lens which are connected in a gluing way from the object side to the imaging surface along the optical axis; the object side surface or the image side surface of the first substrate is plated with a diaphragm; the second group sequentially comprises a second lens, a second substrate and a third lens which are connected in a gluing way from the object side to the imaging surface along the optical axis; the third group has positive focal power and sequentially comprises a fourth lens and a third substrate which are connected in a gluing way from the object side to the imaging surface along the optical axis. 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, ensures that the lens can realize high-definition imaging within a working object distance of 3mm to infinity, and can well meet the requirements of the detection range, the observation depth and the definition of an endoscope.
Description
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, insufficient imaging definition 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 insufficient observation range of the endoscope lens, insufficient definition can influence the observation effect of the endoscope lens, and the small depth of field can influence the observation depth 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 volume, large field of view, large depth of field and high definition imaging.
The embodiment of the invention realizes the aim through the following technical scheme.
In one aspect, the present invention provides an optical lens comprising, in order from an object side to an imaging surface along an optical axis: a first group, a second group, and a third group; the first group has positive focal power and sequentially comprises a first substrate and a first lens which are connected in a gluing way from the object side to the imaging surface along the optical axis; an object side surface or an image side surface of the first substrate is plated with a diaphragm; the second group sequentially comprises a second lens, a second substrate and a third lens which are connected in a gluing way from the object side to the imaging surface along the optical axis; the third group has positive focal power and sequentially comprises a fourth lens and a third substrate which are connected in a gluing way from the object side to the imaging surface along the optical axis; wherein the working object distance of the optical lens is 3mm to infinity; the optical lens satisfies the following conditional expression: 0.6mm/rad < TTL/theta <1mm/rad, TTL represents the distance from the object side surface to the imaging surface of the first group on the optical axis, and theta represents the maximum half field angle of the optical lens.
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 optical power and the surface type of each lens group are reasonably arranged, so that the optical lens has smaller size and caliber, simultaneously has larger field angle, realizes wide-angle characteristic, meets the requirement of large-scale shooting, simultaneously effectively increases the depth of field of the lens, enables the lens to realize high-definition imaging in 3mm to infinite working object distance, and can well meet the requirements of the endoscope detection range, observation depth and definition.
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 a field curvature of an optical lens according to a first embodiment of the present invention.
Fig. 3 is an axial chromatic aberration diagram of an optical lens according to a first embodiment of the present invention.
Fig. 4 is a schematic structural diagram of an optical lens according to a second embodiment of the present invention.
Fig. 5 is a field curvature chart of an optical lens according to a second embodiment of the present invention.
Fig. 6 is an axial chromatic aberration diagram of an optical lens according to a second embodiment of the present invention.
Fig. 7 is a schematic structural diagram of an optical lens according to a third embodiment of the present invention.
Fig. 8 is a field curvature chart of an optical lens according to a third embodiment of the present invention.
Fig. 9 is an axial chromatic aberration diagram of an optical lens according to a third embodiment of the present invention.
Fig. 10 is a schematic structural diagram of an image capturing module according to a fourth 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 from an object side to an imaging surface along an optical axis: a first group, a second group, a third group.
The first group has positive focal power, and sequentially comprises a first substrate and a first lens which are connected in a gluing way from the object side to the imaging surface along the optical axis, wherein the first lens is glued on the image side surface of the first substrate. In some embodiments, the first group further includes a fifth lens, the fifth lens is glued on the object side surface of the first substrate, and lenses are respectively disposed on two surfaces of the first substrate, so that the lens has a larger field angle while high-quality imaging is ensured. The surfaces of the first lens and the fifth lens, which are glued with the first substrate, are plane surfaces.
The diaphragm is plated on the object side surface of the first substrate, so that the size of an incident light beam is better controlled, and the diaphragm is arranged on the object side surface of the first substrate in a film plating mode. 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 0.15mm or other values, and the effective aperture value is specifically set according to the actual situation, and the embodiment is not limited specifically.
The second group has negative focal power or positive focal power, and comprises a second lens, a second substrate and a third 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 object side surface of the second substrate, and the third lens is glued on the image side surface of the second substrate; the surfaces of the second lens and the third lens, which are glued with the second substrate, are plane surfaces. The first substrate and the second substrate can be glass substrates or plastic substrates with certain thickness and width, and the widths (effective caliber) of the first substrate and the second substrate in the direction perpendicular to the optical axis are larger than the effective caliber of the lens, so that a stable forming environment can be provided for each lens, and meanwhile connection and assembly among different subsequent groups are facilitated.
The third group has positive focal power, and the third group sequentially comprises a fourth lens and a third substrate which are connected in a gluing way from the object side to the imaging surface along the optical axis, wherein the fourth lens is glued on the object side surface of the third substrate, and the gluing surface of the fourth lens and the third substrate is a plane. The third substrate provides a support carrier for the fourth lens on one hand, and also serves as protective glass on the other hand, so as to protect the imaging chip on the imaging surface.
Specifically, the thicknesses of the first substrate, the second substrate and the third substrate can be selected to be 0.1mm-0.4mm, if the thickness of the substrate is lower than 0.1mm, the substrate is too thin and is easy to break, the lens cannot be well supported, the assembly difficulty is high, and the production yield is low; if the thickness of the substrate is higher than 0.4mm, the excessive thickness is unfavorable for realizing the light and thin lens. The effective calibers of the first substrate, the second substrate and the third substrate are smaller than 1.5mm, 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 substrates in a gluing mode, specifically, the first lens, the second lens, the third lens, the fourth lens and the fifth 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 stamping or etching a lens structure on the first substrate, the second substrate and the third substrate (glass or plastic), and can ensure that the lens has the characteristic of large depth of field while realizing wide angle and miniaturization of the lens. Preferably, the first lens, the second lens, the third lens, the fourth lens and the fifth lens all adopt a photoresist imprinting mode, the glued surfaces of the lenses and the substrate are planes, the surfaces of the lenses far away from the substrate can be spherical surfaces or aspherical surfaces, and preferably, aspherical lenses are 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.
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 a conventional mode, the processing precision is not guaranteed, and the coaxiality of each component is also difficult to guarantee, 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 arrangement positions of the lenses, and meanwhile, when the lenses are assembled, only the first substrate, the second substrate and the third substrate are required to be installed and fixed according to a preset space, the respective installation errors among a plurality of lenses are not required to be considered, and the overall processing sensitivity is reduced.
The working object distance of the optical lens is 3mm to infinity, which indicates that the lens has a larger depth of field range and can realize larger observation depth.
In some embodiments, the image side of the first lens element is convex, the image side of the third lens element is concave at a paraxial region, and the object side of the fourth lens element is convex.
In some embodiments, the optical lens satisfies the following conditional expression: 0.6mm/rad < TTL/theta <1mm/rad, TTL represents the distance from the object side surface to the imaging surface of the first group on the optical axis, and theta represents the maximum half field angle of the optical lens. The optical lens has smaller total optical length and larger angle of view, and can better realize the balance of small size and large visual angle.
In some embodiments, the optical lens satisfies the following conditional expression: 0.06< F/f# <0.1, 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 3mm 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: 0.1<f Q1 /f<8, wherein 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 positive focal power, improves the convergence capacity of light rays, is favorable for increasing the angle of view of the lens, and realizes a larger observation range.
In some embodiments, the optical lens satisfies the following conditional expression: 8<f Q3 /f<20, 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 has proper positive focal power, and the angle of light incident on the image surface is controlled to match with the CRA (chief ray incidence angle) of the imaging chip, so that the chip performance is fully utilized, and the image quality is further improved.
In some embodiments of the present invention, in some embodiments,the optical lens satisfies the following conditional expression: 0.01<f Q1 /f Q3 <1, wherein f Q1 Representing the effective focal length, f, of the first group Q3 Representing the effective focal length of the third group. The optical power collocation of the first group and the third group is reasonably set to effectively collect light rays with large angles, enlarge the field angle of an optical system and realize the wide-angle characteristic; meanwhile, the light entering the imaging surface can be effectively converged, the correction difficulty of aberration is reduced, and the overall imaging quality is improved.
In some embodiments, the optical lens satisfies the following conditional expression: 1<D/H <1.3, wherein D represents the maximum effective aperture of the first, second and third substrates, and H represents the total image height of the optical lens. The lenses are respectively glued on the substrates, and the effective caliber of each lens is smaller than that of the substrate, so that the conditions are met, the lens is ensured to have smaller external caliber, the field angle of the lens is increased, the imaging range of the lens is enlarged, and the larger observation range is realized. In some embodiments, the effective 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 a lens, and improves the assembly yield.
In some embodiments, the optical lens satisfies the following conditional expression: 0.1mm<CT Q1 <0.6mm，0.1mm<CT Q2 <0.3mm，0.1mm<CT Q3 <0.3mm, 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, ensures that the thickness of each group is not too large while ensuring the good performance of the lens, is beneficial to realizing the miniaturization of the lens, is beneficial to the molding and the assembly of the lens, and ensures the product yield.
In some embodiments, the optical lens satisfies the following conditional expression: 0.6< TTL/D <1, 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 lens meets the conditions, can ensure that the lens has smaller optical total length and smaller caliber, and is beneficial to realizing the miniaturization of the overall size of the lens.
In some embodiments, the optical lens satisfies the following conditional expression: 0.006 mm/° H/FOV <0.008 mm/°, where H represents the total image height of the optical lens and FOV represents the maximum field angle of the optical lens. The above conditions are satisfied, and the edge resolution of the optical lens can be improved by controlling the distortion, so that the imaging quality of the lens is improved.
In some embodiments, the optical lens satisfies the following conditional expression: 1.5< TTL/f <2.5, wherein TTL represents the distance from the object side surface to the imaging surface of the first group on the optical axis, and f represents the effective focal length of the optical lens. The method meets the conditions, is beneficial to shortening the total length of the system, realizes the miniaturized design of the lens, and is beneficial to improving the imaging quality of the optical lens.
In some embodiments, the maximum field angle FOV of the optical lens is greater than or equal to 125 degrees, and the total optical length TTL of the optical lens is less than or equal to 1mm.
The optical lens provided by the invention adopts three groups of lens groups formed by bonding the substrate and the lens, and by reasonably setting the focal power and the surface type collocation of each lens group, the optical lens has a smaller total length (TTL is less than or equal to 1 mm) and a larger field angle (FOV is more than or equal to 125 degrees), so that the wide-angle characteristic is realized, the requirement of large-scale shooting is met, the depth of field of the lens is effectively increased, the high-definition imaging of the lens can be realized within the working object distance from 3mm to infinity, and the requirements of the detection range, the observation depth and the definition of an endoscope 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 positive 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 surface along the optical axis, a stop ST, a first substrate L11, and a first lens L12. The thickness of the first substrate L11 in the optical axis direction was 0.1mm, and both the object side surface and the image side surface of the first substrate L11 were planar. The diaphragm ST is plated on the object side surface of the first substrate L11 in a film plating mode, and the effective caliber of the diaphragm is 0.1mm. The object side surface of the first lens element L12 is planar, and the image side surface of the first lens element L12 is convex, and the object side surface of the first lens element L12 is bonded to the image side surface of the first substrate L11 by nanoimprinting.
The second group Q2 includes, in order from the object side to the imaging surface along the optical axis, a second lens L21, a second substrate L22, and a third lens L23. The thickness of the second substrate L22 in the optical axis direction was 0.1mm, and both the object side surface and the image side surface of the second substrate L22 were planar. The object-side surface of the second lens element L21 is convex at a paraxial region, the image-side surface of the third lens element L23 is planar, the image-side surface of the third lens element L23 is concave at a paraxial region, and the image-side surface of the second lens element L21 and the object-side surface of the third lens element L23 are respectively bonded to the object-side surface and the image-side surface of the second substrate L22 by nanoimprinting.
The third group Q3 includes, in order from the object side to the imaging surface along the optical axis, a fourth lens L31, a third substrate L32. The thickness of the third substrate L32 in the optical axis direction was 0.1mm, and both the object side surface and the image side surface of the third substrate L32 were planar. The object side surface of the fourth lens element L31 is convex, and the image side surface of the fourth lens element L31 is planar, and the image side surface of the fourth lens element L31 is bonded to the object side surface of the third substrate L32 by nanoimprinting. The third substrate L32 provides a support carrier for the fourth lens L31 on one hand, and is used as a protective glass on the other hand, so that stray light can be effectively filtered, color deviation can be corrected, an imaging chip on an imaging surface can be protected, the thickness of the lens can be maximally reduced, and the miniaturization of the lens can be realized.
The first substrate L11, the second substrate L22 and the third substrate L32 are made of glass materials, so that imprinting of the lens and assembly and fixation of the lens can be better realized.
The image side surface of the first lens element L12, the object side surface of the second lens element L21, the image side surface of the third lens element L23 and the object side surface of the fourth lens element L31 are aspheric. The first lens L12, the second lens L21, the third lens L23 and the fourth lens L31 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. In fig. 1, S1 denotes an object side surface of the first substrate L11, S2 denotes a bonding surface of the first substrate L11 and the first lens L12, S3 denotes an image side surface of the first lens L12, S4 denotes an object side surface of the second lens L21, S5 denotes a bonding surface of the second lens L21 and the second substrate L22, S6 denotes a bonding surface of the second substrate L22 and the third lens L23, S7 denotes an image side surface of the third lens L23, S8 denotes an object side surface of the fourth lens L31, S9 denotes a bonding surface of the fourth lens L31 and the third substrate L32, and S10 denotes an image side surface of the third substrate L32.
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 curvature of field and axial chromatic aberration of the optical lens 100 are shown in fig. 2 and 3, respectively.
The field curvature curve of fig. 2 represents the extent of curvature of the meridional image plane and the sagittal image plane. In FIG. 2, the horizontal axis represents the offset (unit: mm), and the vertical axis represents the normalized field angle. As can be seen from fig. 2, the curvature of field of the meridional image plane (T direction) and the sagittal image plane (S direction) are controlled within ±0.05mm, indicating that the curvature of field of the optical lens 100 is well corrected.
The axial chromatic aberration curves of fig. 3 represent aberrations at different wavelengths on the optical axis at the imaging plane. In FIG. 3, the horizontal axis represents the spherical difference (unit: mm), and the vertical axis represents the normalized pupil radius. As can be seen from fig. 3, the offset amount of the axial chromatic aberration is controlled within ±0.02mm, indicating 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 provided in the present embodiment, the optical lens 200 in the present embodiment includes, in order from an object side to an imaging plane along an optical axis: a first group Q1 having positive power, a second group Q2 having negative power, and a third group Q3 having positive power.
The first group Q1 includes, in order from the object side to the imaging surface along the optical axis, a fifth lens L13, a stop ST, a first substrate L11, and a first lens L12. The thickness of the first substrate L11 in the optical axis direction was 0.1mm. The diaphragm ST is plated on the object side surface of the first substrate L11 in a film plating mode, the thickness of the film is thinner, and the gluing effect of the fifth lens L13 on the first substrate is not affected; the effective aperture of the diaphragm is 0.1mm. The object side surface of the fifth lens element L13 is concave, and the image side surface of the fifth lens element L13 is planar; the object side surface of the first lens element L12 is planar, the image side surface of the fifth lens element L13 is convex, and the image side surface of the fifth lens element L13 and the object side surface of the first lens element L12 are respectively bonded to the object side surface and the image side surface of the first substrate L11 by nano-imprinting, or in other embodiments, the object side surface and the image side surface of the first substrate are disposed on the surface of the first substrate by etching.
The second group Q2 includes, in order from the object side to the imaging surface along the optical axis, a second lens L21, a second substrate L22, and a third lens L23. The thickness of the second substrate L22 in the optical axis direction was 0.1mm, and both the object side surface and the image side surface of the second substrate L22 were planar. The object-side surface of the second lens element L21 is convex at a paraxial region, the image-side surface of the third lens element L23 is planar at a paraxial region, and the image-side surface of the third lens element L23 is concave at a paraxial region, and the image-side surface of the second lens element L21 and the object-side surface of the third lens element L23 are respectively bonded to the object-side surface and the image-side surface of the second substrate L22 by nanoimprint, or in other embodiments, by etching.
The third group Q3 includes, in order from the object side to the imaging surface along the optical axis, a fourth lens L31, a third substrate L32. The thickness of the third substrate L32 in the optical axis direction was 0.1mm, and both the object side surface and the image side surface of the third substrate L32 were planar. The object side surface of the fourth lens element L31 is convex, and the image side surface of the fourth lens element L31 is planar, and the image side surface of the fourth lens element L31 is bonded to the object side surface of the third substrate L32 by nanoimprinting. The third substrate L32 provides a support carrier for the fourth lens L31 on one hand, and is used as a protective glass on the other hand, so that stray light can be effectively filtered, color deviation can be corrected, an imaging chip on an imaging surface can be protected, the thickness of the lens can be maximally reduced, and the miniaturization of the lens can be realized.
The first substrate L11, the second substrate L22 and the third substrate L32 are made of glass materials, so that imprinting of the lens and assembly and fixation of the lens can be better realized.
The image side surface of the first lens element L12, the object side surface of the second lens element L21, the image side surface of the third lens element L23, the object side surface of the fourth lens element L31 and the object side surface of the fifth lens element L13 are aspheric. The first lens L12, the second lens L21, the third lens L23, the fourth lens L31 and the fifth lens L13 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 200 provided in this embodiment are shown in table 3. In fig. 4, S0 denotes an image side surface of the fifth lens L13, S1 denotes a bonding surface of the fifth lens L13 and the first substrate L11, S2 denotes a bonding surface of the first substrate L11 and the first lens L12, S3 denotes an image side surface of the first lens L12, S4 denotes an object side surface of the second lens L21, S5 denotes a bonding surface of the second lens L21 and the second substrate L22, S6 denotes a bonding surface of the second substrate L22 and the third lens L23, S7 denotes an image side surface of the third lens L23, S8 denotes an object side surface of the fourth lens L31, S9 denotes a bonding surface of the fourth lens L31 and the third substrate L32, and S10 denotes an image side surface of the third substrate L32.
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 curvature of field and axial chromatic aberration of the optical lens 200 are shown in fig. 5 and 6, respectively.
The field curvature curve of fig. 5 represents the extent of curvature of the meridional image plane and the sagittal image plane. As can be seen from fig. 5, the curvature of field of the meridional image plane (T direction) and the sagittal image plane (S direction) are controlled within ±0.04mm, which indicates that the curvature of field of the optical lens 200 is well corrected.
The axial chromatic aberration curves of fig. 6 represent aberrations at different wavelengths on the optical axis at the imaging plane. As can be seen from fig. 6, the offset amount of the axial chromatic aberration is controlled within ±0.01mm, indicating that the optical lens 200 can effectively correct the aberration of the fringe field of view.
Third embodiment
Referring to fig. 7 for a schematic structural diagram of an optical lens 300 provided in the present embodiment, the optical lens 300 in the present embodiment has substantially the same structure as the optical lens in the second embodiment, and specifically, the optical lens 300 includes, in order from an object side to an imaging plane along an optical axis: a first group Q1 having positive power, a second group Q2 having negative power, and a third group Q3 having positive power.
The first group Q1 includes, in order from the object side to the imaging surface along the optical axis, a fifth lens L13, a stop ST, a first substrate L11, and a first lens L12. The thickness of the first substrate L11 in the optical axis direction was 0.11mm. The diaphragm ST is plated on the object side surface of the first substrate L11 in a film plating mode, the thickness of the film is thinner, and the gluing effect of the fifth lens L13 on the first substrate is not affected; the effective aperture of the diaphragm is 0.1mm. The object side surface of the fifth lens element L13 is concave, and the image side surface of the fifth lens element L13 is planar; the object side surface of the first lens element L12 is planar, the image side surface of the fifth lens element L13 is convex, the image side surface of the fifth lens element L13 and the object side surface of the first lens element L12 are respectively bonded to the object side surface and the image side surface of the first substrate L11 by nano imprinting, and in other embodiments, the lenses can be disposed on the surface of the first substrate by etching.
The second group Q2 includes, in order from the object side to the imaging surface along the optical axis, a second lens L21, a second substrate L22, and a third lens L23. The thickness of the second substrate L22 in the optical axis direction was 0.1mm, and both the object side surface and the image side surface of the second substrate L22 were planar. The object-side surface of the second lens element L21 is concave, the image-side surface of the third lens element L23 is planar, the image-side surface of the third lens element L23 is concave at a paraxial region, the image-side surface of the second lens element L21 and the object-side surface of the third lens element L23 are respectively bonded to the object-side surface and the image-side surface of the second substrate L22 by nanoimprint, and in other embodiments, the lenses can be disposed on the surface of the second substrate by etching.
The third group Q3 includes, in order from the object side to the imaging surface along the optical axis, a fourth lens L31, a third substrate L32. The thickness of the third substrate L32 in the optical axis direction was 0.1mm, and both the object side surface and the image side surface of the third substrate L32 were planar. The object side surface of the fourth lens element L31 is convex, and the image side surface of the fourth lens element L31 is planar, and the image side surface of the fourth lens element L31 is bonded to the object side surface of the third substrate L32 by nanoimprinting. The third substrate L32 provides a support carrier for the fourth lens L31 on one hand, and is used as a protective glass on the other hand, so that stray light can be effectively filtered, color deviation can be corrected, an imaging chip on an imaging surface can be protected, the thickness of the lens can be maximally reduced, and the miniaturization of the lens can be realized.
The first substrate L11, the second substrate L22 and the third substrate L32 are made of glass materials, so that imprinting of the lens and assembly and fixation of the lens can be better realized.
The image side surface of the first lens element L12, the object side surface of the second lens element L21, the image side surface of the third lens element L23, the object side surface of the fourth lens element L31 and the object side surface of the fifth lens element L13 are aspheric. The first lens L12, the second lens L21, the third lens L23, the fourth lens L31 and the fifth lens L13 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. In fig. 7, S0 denotes an image side surface of the fifth lens L13, S1 denotes a bonding surface of the fifth lens L13 and the first substrate L11, S2 denotes a bonding surface of the first substrate L11 and the first lens L12, S3 denotes an image side surface of the first lens L12, S4 denotes an object side surface of the second lens L21, S5 denotes a bonding surface of the second lens L21 and the second substrate L22, S6 denotes a bonding surface of the second substrate L22 and the third lens L23, S7 denotes an image side surface of the third lens L23, S8 denotes an object side surface of the fourth lens L31, S9 denotes a bonding surface of the fourth lens L31 and the third substrate L32, and S10 denotes an image side surface of the third substrate L32.
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, the field curvature and axial chromatic aberration curves of the optical lens 300 are shown in fig. 8 and 9, respectively.
The field curvature curve of fig. 8 indicates the extent of curvature of the meridional image plane and the sagittal image plane. As can be seen from fig. 8, the curvature of field of the meridional image plane (T direction) and the sagittal image plane (S direction) are controlled within ±0.05mm, which indicates that the curvature of field of the optical lens 300 is well corrected.
The axial chromatic aberration curves of fig. 9 represent aberrations at different wavelengths on the optical axis at the imaging plane. As can be seen from fig. 9, the offset amount of the axial chromatic aberration is controlled within ±0.02mm, indicating that the optical lens 300 can effectively correct the aberration of the fringe field of view.
Referring to table 7, the correlation values of the optical lens provided in the above three embodiments and each of the above conditional expressions are shown.
TABLE 7
In summary, the optical lens provided by the invention adopts three groups of lens groups formed by the substrate and the lens, is convenient for lens processing and forming and is more convenient to assemble, and meanwhile, the optical lens has smaller total length (TTL is less than or equal to 1 mm) and larger angle of view (FOV is more than or equal to 125 degrees) by reasonably setting the focal power and the surface type collocation of each lens group, so that the wide-angle characteristic is realized, the requirement of large-range shooting is met, the depth of field of the lens is effectively increased, the high-definition imaging of the lens can be realized within the working object distance from 3mm to infinity, and the requirements of the endoscope detection range, the observation depth and the definition can be well met.
Fourth embodiment
Referring to fig. 10, a fourth embodiment of the present invention provides an image capturing module 400, where the image capturing module 400 may include an imaging element 410 and the optical lens 100/200/300 (e.g., the optical lens 200) of any of the above embodiments. The imaging element 410 may be a CMOS (Complementary Metal Oxide Semiconductor ) image sensor or a CCD (Charge Coupled Device, charge coupled device) image sensor.
The imaging module 400 may be any of a medical endoscope, an industrial endoscope, a capsule lens, and a camera equipped with the optical lens 200.
The image capturing module 400 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 capturing module 400 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 on the 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 (12)
1. An optical lens comprising, in order from an object side to an imaging surface along an optical axis: a first group, a second group, and a third group;
the first group has positive focal power and sequentially comprises a first substrate and a first lens which are connected in a gluing way from the object side to the imaging surface along the optical axis; an object side surface or an image side surface of the first substrate is plated with a diaphragm;
the second group sequentially comprises a second lens, a second substrate and a third lens which are connected in a gluing way from the object side to the imaging surface along the optical axis;
the third group has positive focal power and sequentially comprises a fourth lens and a third substrate which are connected in a gluing way from the object side to the imaging surface along the optical axis;
wherein the working object distance of the optical lens is 3mm to infinity;
the optical lens satisfies the following conditional expression: 0.6mm/rad < TTL/theta <1mm/rad, TTL represents the distance from the object side surface to the imaging surface of the first group on the optical axis, and theta represents the maximum half field angle of the optical lens.
2. The optical lens of claim 1, wherein a fifth lens is adhesively attached to the object-side face of the first group.
3. The optical lens of claim 1, wherein the glue joint comprises a nanoimprint or an etching.
4. The optical lens of claim 1, wherein the image-side surface of the first lens element is convex, the image-side surface of the third lens element is concave at a paraxial region, and the object-side surface of the fourth lens element is convex.
5. The optical lens according to claim 1, wherein the optical lens satisfies a conditional expression: 0.06< F/f# <0.1, wherein F represents an effective focal length of the optical lens and f# represents an aperture value of the optical lens.
6. The optical lens of claim 1, wherein the lens is a lensThe optical lens satisfies the conditional expression: 0.1<f Q1 /f<8, wherein f Q1 Representing the effective focal length of the first group, f representing the effective focal length of the optical lens.
7. The optical lens according to claim 1, wherein the optical lens satisfies a conditional expression: 8<f Q3 /f<20, wherein f Q3 Representing an effective focal length of the third group, f representing an effective focal length of the optical lens.
8. The optical lens according to claim 1, wherein the optical lens satisfies a conditional expression: 0.01<f Q1 /f Q3 <1, wherein f Q1 Representing the effective focal length, f, of the first group 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: 1.8< H/f <2.5, wherein H represents the total image height of the optical lens and f represents the effective focal length of the optical lens.
10. The optical lens according to claim 1, wherein the optical lens satisfies a conditional expression: 0.1mm<CT Q1 <0.6mm，0.1mm<CT Q2 <0.3mm，0.1mm<CT Q3 <0.3mm, 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.
11. The optical lens according to claim 1, wherein the optical lens satisfies a conditional expression: 0.6< TTL/D <1, wherein D represents the maximum effective caliber in the first, second and third substrates.
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.
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