CN117130146A - Miniature capsule endoscope lens - Google Patents
Miniature capsule endoscope lens Download PDFInfo
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- CN117130146A CN117130146A CN202311396571.7A CN202311396571A CN117130146A CN 117130146 A CN117130146 A CN 117130146A CN 202311396571 A CN202311396571 A CN 202311396571A CN 117130146 A CN117130146 A CN 117130146A
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- 239000002775 capsule Substances 0.000 title claims abstract description 35
- 230000003287 optical effect Effects 0.000 claims abstract description 244
- 239000003094 microcapsule Substances 0.000 claims abstract description 9
- 238000003384 imaging method Methods 0.000 claims description 32
- 238000005286 illumination Methods 0.000 claims description 15
- 238000009792 diffusion process Methods 0.000 claims description 3
- 230000004075 alteration Effects 0.000 abstract description 5
- 230000000694 effects Effects 0.000 abstract description 5
- 239000011521 glass Substances 0.000 abstract description 3
- 230000003902 lesion Effects 0.000 abstract 1
- 238000004519 manufacturing process Methods 0.000 abstract 1
- 238000010586 diagram Methods 0.000 description 13
- 238000005452 bending Methods 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 3
- 238000001514 detection method Methods 0.000 description 3
- 230000007547 defect Effects 0.000 description 2
- 201000010099 disease Diseases 0.000 description 2
- 208000037265 diseases, disorders, signs and symptoms Diseases 0.000 description 2
- 230000005669 field effect Effects 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 238000012634 optical imaging Methods 0.000 description 2
- 210000000813 small intestine Anatomy 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000001934 delay Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 210000001035 gastrointestinal tract Anatomy 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 210000000214 mouth Anatomy 0.000 description 1
- 210000003928 nasal cavity Anatomy 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 230000001575 pathological effect Effects 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 241000894007 species Species 0.000 description 1
- 230000000007 visual effect Effects 0.000 description 1
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B23/00—Telescopes, e.g. binoculars; Periscopes; Instruments for viewing the inside of hollow bodies; Viewfinders; Optical aiming or sighting devices
- G02B23/24—Instruments or systems for viewing the inside of hollow bodies, e.g. fibrescopes
- G02B23/2407—Optical details
- G02B23/2423—Optical details of the distal end
- G02B23/243—Objectives for endoscopes
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B1/00—Instruments for performing medical examinations of the interior of cavities or tubes of the body by visual or photographical inspection, e.g. endoscopes; Illuminating arrangements therefor
- A61B1/00163—Optical arrangements
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
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Abstract
The application relates to a microcapsule endoscope lens, which comprises five glass spherical lenses, wherein the five glass spherical lenses have optical power, and the optical lens comprises a first lens with negative optical power, a second lens with negative optical power, a third lens with negative optical power, a fourth lens with positive optical power and a fifth lens with negative optical power in sequence from an object side to an image side along an optical axis. The optical lens not only reduces the manufacturing cost of the lens, but also realizes the effects of wide angle, low distortion, high relative illuminance and high pixel, can well correct on-axis and off-axis aberration, has excellent optical performance, and the volume of the whole capsule endoscope is kept in a range as small as possible, so that the whole capsule endoscope can freely move in a human body, and flexibly and accurately shooting and inputting the high image quality of the lesion position of a patient.
Description
Technical Field
The application discloses a microcapsule endoscope lens, and mainly relates to the technical field of optical imaging.
Background
A capsule endoscope, also called capsule endoscope (capsule endoscope), is a capsule-shaped endoscope, which is a medical instrument used for examining the intestinal tract of a human body; the endoscope can enter the human body through the oral cavity, the nasal cavity and other channels of the human body, and images of diseased parts in the human body are shot, so that doctors can observe and diagnose the disease parts; the endoscope needs to have higher pixels, enough large field angle and good depth of field effect to meet the requirement of comprehensively and accurately observing the affected part. However, the endoscope having the above-mentioned good performance in the related art tends to have a large volume, and is liable to cause discomfort to the patient when the endoscope enters the human body.
The traditional capsule endoscope has the defects of small observation range, low imaging relative illumination and the like, poor image quality and the like, for example, the total length of a system of the capsule endoscope proposed by YenChih-Ta and the like is smaller than 4mm, the Modulation Transfer Function (MTF) can reach 12.5% when the system is 285lp/mm, the relative illumination of the system can reach 34.1% when the system is 144lp/mm, the relative illumination of the system reaches 60%, the field angle is 109.8 degrees, the system is relatively unfavorable to obtain more perfect image information by integrating the parameters, and the corresponding pathological information can be obtained by independent judgment by depending on the professional ability and working experience of doctors, so that the traditional endoscope lens has very large uncertainty in practical use, is difficult to achieve high-precision imaging effect by excessively depending on the subjective speculation of people, and seriously delays the treatment time of patients if the system cannot be correctly judged.
Disclosure of Invention
The application designs a capsule endoscope based on the premise of keeping indexes such as large view field, small volume and the like, and performs aberration optimization, thereby effectively solving the problems that the traditional endoscope structure is not beneficial to the system to obtain more perfect image information, has very large uncertainty in actual use, excessively depends on subjective speculation of people, is difficult to achieve high-precision imaging effect and the like.
Specifically, the technical scheme of the application is as follows:
a capsule endoscope optical lens having five lenses having optical power in total, the optical lens including a first lens having negative optical power, a second lens having negative optical power, a third lens having negative optical power, a fourth lens having positive optical power, and a fifth lens having negative optical power, which are disposed in order from an object side to an image side along an optical axis;
the first lens element has negative refractive power, wherein an object-side surface of the first lens element is convex at a paraxial region thereof, and an image-side surface of the first lens element is concave at a paraxial region thereof;
the second lens has negative focal power, the object side surface of the second lens is a convex surface at a paraxial region, and the image side surface of the second lens is a concave surface at the paraxial region;
the third lens element has negative refractive power, wherein an object-side surface of the third lens element is concave at a paraxial region thereof, and an image-side surface of the third lens element is convex at a paraxial region thereof;
the fourth lens element has positive refractive power, wherein an object-side surface of the fourth lens element is convex at a paraxial region thereof, and an image-side surface of the fourth lens element is convex at a paraxial region thereof;
the fifth lens element has negative refractive power, wherein an object-side surface of the fifth lens element is convex at a paraxial region thereof, and an image-side surface of the fifth lens element is concave at a paraxial region thereof;
a diaphragm is arranged between the third lens and the fourth lens;
the structures of the third lens, the fourth lens and the fifth lens form negative-positive structural symmetry;
the endoscope optical lens satisfies the relation:wherein FNUM is the relative aperture of the optical lens, f is the focal length of the optical lens, B is the back focal length of the optical lens, and alpha is the half-diameter of the diffusion at the 0 field of view;
the optical lens of the microcapsule endoscope meets the relation: 2< FNUM/TAN (HFOV) <2.5, wherein HFOV is half of the maximum field angle of the optical lens, TAN (HFOV) is the tangent of HFOV angle, FNUM is the relative aperture of the optical lens;
the optical lens of the microcapsule endoscope meets the relation: TTL/f is more than 4 and less than 5; wherein TTL is a distance from an object side surface of the first lens to an imaging surface of the optical lens on the optical axis, and f is a focal length of the optical lens.
Further, the optical lens satisfies the following conditional expression:the HFOV is the horizontal angle of view of the optical system, and TTL is the total optical length of the optical lens.
Further, the optical lens satisfies the following conditional expression:wherein f1 is the focal length of the first lens, f2 is the focal length of the second lens, f4 is the focal length of the fourth lens, and f5 is the focal length of the fifth lens.
Further, the optical lens satisfies the following conditional expression: fnum=2.83, FNUM being the relative aperture of the optical lens.
Further, the optical lens satisfies the following conditional expression:w is the half field angle of the optical lens.
Further, the optical lens satisfies the following conditional expression: ttl=6mm, TTL is the optical total length of the optical lens.
Further, the optical lens satisfies the following conditional expression:θ is the optical system distortion.
Further, the optical lens satisfies the following conditional expression: the relative illumination is more than 95% of the full field of view and is uniformly distributed.
Compared with the prior art, the application has the beneficial effects that: the capsule endoscope lens has five lenses with optical power, the optical lens comprises a first lens with negative optical power, a second lens with negative optical power, a third lens with negative optical power, a fourth lens with positive optical power and a fifth lens with negative optical power, which are arranged from an object side to an image side along an optical axis, the lens structure in the whole optical system can well balance various aberrations in the system, the optical power of the lens groups and the optical power of each lens group is reasonably distributed on distortion control, the special problem of optical distortion is solved, and the optical distortion of the system is less than 31% on the premise of high illumination and high image quality.
The application overcomes the defects of the prior art, the distortion is below 31 percent, the relative illumination is 95 percent, the Modulation Transfer Function (MTF) can reach 40 percent when the image capturing of the wide angle of the field angle of 100 degrees is realized, the total length of the lens is only 6mm when the MTF is 100lp/mm, the volume is small, the application can effectively help to solve the technical problems that the traditional endoscope has very large uncertainty in practical use, the high-precision imaging effect is difficult to achieve due to the subjective speculation of people, and the like, and the lens is integrally made of spherical glass material, so that the processing technology difficulty of the optical lens can be better reduced on the premise that the imaging standard is ensured to be reached.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic structural view of an optical lens disclosed in a first embodiment of the present application.
Fig. 2 is a diagram illustrating the analysis of the modulation transfer function according to the first embodiment of the present application.
Fig. 3 is a full field root mean square spot size as disclosed in the first embodiment of the application.
Fig. 4 is a distortion chart disclosed in the first embodiment of the present application.
Fig. 5 is an image side illumination diagram of the first embodiment of the present application.
Fig. 6 is a schematic structural diagram of an optical lens according to a second embodiment of the present application.
Fig. 7 is a diagram illustrating a modulation transfer function analysis according to a second embodiment of the present application.
Fig. 8 is a full field root mean square spot size as disclosed in a second embodiment of the application.
Fig. 9 is a distortion chart of the disclosure of the second embodiment of the present application.
Fig. 10 is an image side illumination diagram according to a second embodiment of the present application.
Fig. 11 is a schematic structural view of an optical lens disclosed in a third embodiment of the present application.
Fig. 12 is a modulation transfer function analysis chart disclosed in the third embodiment of the present application.
Fig. 13 is a full field root mean square spot size as disclosed in the third embodiment of the present application.
Fig. 14 is a distortion chart disclosed in the third embodiment of the present application.
Fig. 15 is an image side illumination diagram according to a third embodiment of the present application.
Detailed Description
The following description of the embodiments of the present application will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
In the present application, the terms "upper", "lower", "left", "right", "front", "rear", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal" and the like indicate an azimuth or a positional relationship based on that shown in the drawings. These terms are only used to better describe the present application and its embodiments and are not intended to limit the scope of the indicated devices, elements or components to the particular orientations or to configure and operate in the particular orientations.
Also, some of the terms described above may be used to indicate other meanings in addition to orientation or positional relationships, for example, the term "upper" may also be used to indicate some sort of attachment or connection in some cases. The specific meaning of these terms in the present application will be understood by those of ordinary skill in the art according to the specific circumstances.
Furthermore, the terms "first," "second," 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 the relative importance and number of devices, elements, or components indicated. Unless otherwise indicated, the meaning of "a plurality" is two or more.
The technical scheme of the application will be further described with reference to the examples and the accompanying drawings.
According to a first aspect of the present application, there is provided an optical lens having five lenses having optical power in total, a first lens having negative optical power, a second lens having negative optical power, a third lens having negative optical power, a fourth lens having positive optical power, and a fifth lens having negative optical power, which are disposed in order from an object side to an image side along an optical axis. During imaging, light rays sequentially enter the first lens, the second lens, the third lens, the fourth lens and the fifth lens from the object side of the first lens, and finally are imaged on an imaging surface of the optical lens.
Further; the object side surface of the first lens is convex at a paraxial region, and the image side surface of the first lens is concave at a paraxial region; the object side surface of the second lens is convex at a paraxial region, and the image side surface of the second lens is concave at a paraxial region; the object side surface of the third lens element is concave at a paraxial region, and the image side surface of the third lens element is convex at a paraxial region; the object side surface of the fourth lens element is convex at a paraxial region, and the image side surface of the fourth lens element is convex at a paraxial region; the fifth lens element has a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region.
The optical lens has five lenses with optical power, when incident light passes through the first lens with negative refractive power, the light rays with a larger range of view fields can be effectively coupled and collected into the whole optical system, and the lens is beneficial to increasing the angle of view of the optical lens and obtaining the capability of shooting a larger angle of view range by matching with the planar design that the object side surface and the image side surface of the first lens are respectively convex and concave at the paraxial region; the second lens element with negative refractive power has a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region, which is effective for controlling a chief ray angle of the optical lens element, reducing reflection of light rays on a surface of the lens element, and correcting aberration of the optical system; the third lens element with negative refractive power has a concave object-side surface at a paraxial region and a convex image-side surface at a paraxial region; the fourth lens element with positive refractive power has a convex object-side surface at a paraxial region and a convex image-side surface at a paraxial region; the fifth lens element with negative refractive power has a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region, so that the refractive power of the optical lens element is reasonably distributed, the movement of the refractive power of the optical lens element in the object-side direction is reduced, the total optical length of the optical lens element is reduced, and the miniaturization design requirement is met.
The lens structure in the whole optical system can well balance various aberrations in the system, reasonably distributes the lens groups and the focal power forming each lens group in distortion control, solves the special problem of optical distortion, and achieves the premise of high illumination and high image quality, wherein the optical distortion of the system is less than 30%.
In addition, the microcapsule endoscope lens satisfies the relation: TTL/f is more than 4 and less than 5; wherein TTL is the distance from the object side surface of the first lens to the imaging surface of the optical lens on the optical axis (i.e. the total optical length of the optical lens), f is the focal length of the optical lens, and when the optical lens satisfies the above relation, the relation between the total optical length and the focal length of the optical system is defined.
When the optical lens satisfies 4 < TTL/f < 5, the optical lens has a larger depth of field effect while the miniaturized design is realized by limiting the relation between the total optical length and the focal length of the optical lens. When the optical lens satisfies the above relation, the focal length of the optical lens can be smaller, so that a larger depth of field can be obtained, thereby improving the shooting capability of the optical lens, and on the other hand, when the optical lens satisfies the above relation, the optical total length of the optical lens can be better ensured to be smaller, thereby reducing the volume of the endoscope and meeting the purpose of flexible movement of the endoscope in a narrow space in a human body.
As an alternative implementation manner, in an embodiment of the present application, the optical lens satisfies the following relationship:the horizontal view angle of the micro-capsule endoscope lens is HFOV, the total optical length of the capsule endoscope lens is TTL, when the optical lens meets the relation, the total length of the optical system can be effectively ensured to be kept in a reasonable range, and more space for installing and receiving detectors is reserved for reducing the total optical length of the lens, so that the whole optical imaging capability is more accurate.
The optical lens meeting the relation can also avoid the condition that the diameter of the first lens is too large due to the overlarge angle of view, thereby ensuring that the diameter of the whole optical lens is kept in a smaller reasonable range, and also further reducing the whole diameter of the capsule endoscope; through reasonable configuration of the relation between the total optical length and the horizontal view angle of the optical lens, the design of a large view field can be met while the miniaturization requirement of the optical lens is met, so that the optical performance is improved, and the service performance of an endoscope is improved.
As an alternative implementation manner, in an embodiment of the present application, the optical lens satisfies the following relationship:the method comprises the steps of carrying out a first treatment on the surface of the Wherein f1 is the focal length of the first lens, f2 is the focal length of the second lens, f4 is the focal length of the fourth lens, and f5 is the focal length of the fifth lens; when the optical lens meets the relation, the bending force of the first lens, the second lens, the fourth lens and the fifth lens can be reasonably matched, and on the premise of meeting the bending force setting requirement of each lens, the overlarge bending force difference among all elements of the whole optical system is avoided, so that the optical lens with higher imaging symmetry is formed, and the imaging performance of the whole optical lens is improved.
As an alternative implementation manner, in an embodiment of the present application, the optical lens satisfies the following relationship: fnum=2.83.
For a fixed focus lens, the depth of field is:wherein: f is the focal length of the lens; f is the F-number under paraxial operation; delta is the allowable circle of confusion diameter; l is the focusing distance.
From the above equation, it is known that a large value is required for the F-number of the optical system in order to obtain a large depth of field, but the light flux entering the optical system is relatively reduced when the F-number is increased, and the resolution is lowered. The F number of the optical system designed by the application is set to be 2.83 in consideration of the working depth of field and imaging quality of the endoscope optical system.
As an alternative implementation manner, in an embodiment of the present application, the optical lens satisfies the following relationship: 2 w=100°; the diameter of the human small intestine is usually 20-30mm, the designed optical system is required to be capable of well imaging the target at the front 10mm, and then the field angle 2w of the lens is as follows:where x is the object distance and y is the horizontal field width at x.
As an alternative implementation manner, in an embodiment of the present application, the optical lens satisfies the following relationship: ttl=6 mm; wherein TTL is the total optical length of the optical lens, and the capsule endoscope consists of the optical lens, a light emitting diode, a solid imaging sensor (COMS), a control circuit, a magnetic control switch, a battery and a transmitting device; an object enters an optical system through a transparent spherical cover at the front end of the capsule to be imaged on a CMOS image sensor, and then is subjected to photoelectric signal conversion by a COMS and is transmitted to an external image receiving instrument through a transmitting device; the capsule endoscope has a limited internal space through the small intestine and should be easy to swallow, and thus the size of the various elements inside the capsule endoscope including the illumination system should be minimized as much as possible, and thus the total track length of the capsule endoscope lens is controlled to 6mm to allow other components to have more storage space.
As an alternative embodiment, the optical lens satisfies the relationWherein FNUM is the relative aperture of the optical lens, f is the focal length of the optical lens, B is the back focal length of the optical lens, and alpha is the half-diameter of the diffusion at the 0 field of view; when the optical lens satisfies the relation->When the range is reached, the larger depth of field can be obtained on the basis of smaller relative aperture, and the size of the diffuse spots in final imaging of the lens is reduced, so that the detection depth of the capsule endoscope in a human body is improved, and meanwhile, the imaging quality of the lens can be controlled in a good range by controlling the size of the diffuse spots.
As an alternative embodiment, the optical lens satisfies the relation 2< FNUM/TAN (HFOV) <2.5, wherein HFOV is half of the maximum field angle of the optical lens, TAN (HFOV) is the tangent of HFOV angle, FNUM is the relative aperture of the optical lens; when the lens meets the range, the lens can be limited to obtain a larger field angle on the basis of meeting a smaller relative aperture, so that the detection range of the capsule endoscope in a human body is improved, the light transmission capacity of the lens can be better increased, and the detection quality and the illumination of the capsule endoscope lens are improved.
As an alternative implementation manner, in an embodiment of the present application, the optical lens satisfies the following relationship:the method comprises the steps of carrying out a first treatment on the surface of the And θ is distortion of the optical system, and imaging quality is directly controlled by limiting imaging distortion of the optical system, so that the working performance of the endoscope is better kept in a high-precision range, and the objective actual picture given by the endoscope is more accurate, thereby effectively avoiding misdiagnosis caused by subjective factors.
As an alternative implementation manner, in an embodiment of the present application, the optical lens satisfies the following relationship: and H is more than or equal to 100 percent and is more than or equal to 95 percent, wherein H represents relative illuminance, in an imaging system, if the relative illuminance is smaller, the illuminance of an image plane is very uneven, and the problems of underexposure or center overexposure of certain positions are easy to occur, so that the imaging quality of an optical instrument is influenced, and the relative illuminance of the optical system is limited to be within the range.
The F-number of the capsule endoscope of the present application is set to 2.83 so that more light can enter the whole optical system lens, the relative illuminance of more than 0.95 is to avoid darkening or deviating the image, the view angle of the lens of the capsule endoscope is improved so that more visual information can be obtained to diagnose the disease of the patient, in this case, the FOV is set to 100 °, the working distance is 10mm, the first element of the wide angle lens needs a larger diameter to receive light from a large field of view, but the lens radius is limited to 2mm, otherwise the diameter of the capsule endoscope is increased to enlarge the whole capsule lens, so that the volume of the whole capsule lens is increased to be unfavorable for use, and the requirement is also that the rest space of other parts inside the capsule is the same.
Specific examples of the optical lens applicable to the above-described embodiments are further described below with reference to the accompanying drawings.
First embodiment
As shown in fig. 1, a schematic structural diagram of an optical lens 100 according to an embodiment of the present application is shown, where the optical lens 100 includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, and a fifth lens L5 sequentially disposed from an object side to an image side along an optical axis. During imaging, light enters the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, and the fifth lens L5 in order from the object side of the first lens L1, and finally is imaged on the imaging surface of the optical lens 100. The first lens L1 has negative power, the second lens L2 has negative power, the third lens L3 has negative power, the fourth lens L4 has positive power, and the fifth lens L5 has negative power.
Further, the object-side surface S1 of the first lens element L1 is convex at the paraxial region O, and the image-side surface S2 of the first lens element L1 is concave at the paraxial region O; the object side surface S3 of the second lens element L2 is convex at a paraxial region O, and the image side surface S4 of the second lens element L2 is concave at the paraxial region O; the object side surface S5 of the third lens element L3 is concave at a paraxial region O, and the image side surface S6 of the third lens element L3 is convex at the paraxial region O; the object side surface S7 of the fourth lens element L4 is convex at a paraxial region O, and the image side surface S8 of the fourth lens element L4 is convex at the paraxial region O; the object-side surface S9 of the fifth lens element L5 is convex at the paraxial region O, and the image-side surface S10 of the fifth lens element L5 is concave at the paraxial region O.
Specifically, taking an example of the focal length f=1.42 mm of the optical lens 100, the f-number fnum=2.83 of the optical lens 100, the maximum field half angle hfov=50° of the optical lens 100, the distance ttl=6.04 mm between the object side surface S1 of the first lens L1 and the image side surface S10 of the fifth lens L5 of the optical lens 100 on the optical axis O, the parameters of the optical lens 100 are given in the following tables 1-1 and 1-2.
TABLE 1-1
TABLE 1-2
In the above table, f is the focal length of the optical system, and f1 to f5 are the focal lengths of the respective lenses in order.
The detailed optical data of this example are shown in tables 1-3 below
Tables 1 to 3
Referring to fig. 2, fig. 2 shows a modulation function analysis chart of the optical lens 100 according to the first embodiment, wherein fig. 2 shows a modulation function analysis chart of the optical lens 100 under 100 line pairs in the first embodiment. In fig. 2, the abscissa along the X-axis direction represents the line pair value in mm, and the ordinate along the Y-axis direction represents the modulation transfer function value; as can be seen from fig. 2, the modulation transfer functions of the optical lens 100 in the first embodiment are all above 40% under 100 line pairs, which indicates that the imaging quality of the optical lens 100 in the present embodiment is better.
Referring to fig. 3, fig. 3 is a diagram showing the root mean square spot size of the full field of view of the optical lens 100 according to the first embodiment; wherein, the abscissa along the X-axis direction represents the relative field of view, and the ordinate along the Y-axis direction represents the root mean square size; as can be seen from fig. 3, the root mean square size of the optical lens 100 is within 0.005 under the full field.
Referring to fig. 4, fig. 4 is a graph showing distortion of the optical lens 100 in the wavelength of visible light according to the first embodiment, wherein the abscissa along the X-axis represents distortion, and the ordinate along the Y-axis represents normalized angle of view, and as can be seen from fig. 4, distortion of the optical lens 100 is well corrected in the wavelength of visible light.
Referring to fig. 5, fig. 5 is a schematic diagram of the relative illuminance of the optical lens in the first embodiment, wherein the abscissa along the X-axis represents the relative field of view, and the ordinate along the Y-axis represents the illuminance, and as can be seen from fig. 5, the relative illuminance of the optical lens 100 is above 95% at all relative fields of view.
Therefore, the capsule endoscope lens provided by the first embodiment of the application can meet the requirements of large field angle, low distortion and high illumination of the system.
Second embodiment
As shown in fig. 6, a schematic structural diagram of an optical lens 200 according to a second embodiment of the present application is shown, where the optical lens 200 includes a first lens L6, a second lens L7, a third lens L8, a fourth lens L9, and a fifth lens L10 sequentially disposed from an object side to an image side along an optical axis. During imaging, light enters the first lens L6, the second lens L7, the third lens L8, the fourth lens L9, and the fifth lens L10 in order from the object side of the first lens L6, and finally is imaged on the imaging surface of the optical lens 200. Wherein the first lens L6 has negative power, the second lens L7 has negative power, the third lens L8 has negative power, the fourth lens L9 has positive power, and the fifth lens L10 has negative power.
Further, the object-side surface S11 of the first lens element L6 is convex at the paraxial region O, and the image-side surface S12 of the first lens element L6 is concave at the paraxial region O; the object side surface S13 of the second lens element L7 is convex at a paraxial region O, and the image side surface S14 of the second lens element L7 is concave at the paraxial region O; the object side surface S15 of the third lens element L8 is concave at a paraxial region O, and the image side surface S16 of the third lens element L8 is convex at the paraxial region O; the object-side surface S17 of the fourth lens element L9 is convex at a paraxial region O, and the image-side surface S18 of the fourth lens element L9 is convex at the paraxial region O; the object-side surface S19 of the fifth lens element L10 is convex at a paraxial region O, and the image-side surface S20 of the fifth lens element L10 is concave at the paraxial region O.
Specifically, taking an example of the focal length f=1.31 mm of the optical lens 200, the f-number fnum=1.31 of the optical lens 200, the maximum field half angle hfov=50° of the optical lens 200, the distance ttl=6.00 mm from the object side surface S11 of the first lens L6 to the image side surface S20 of the fifth lens L10 of the optical lens 100 on the optical axis O, other parameters of the optical lens 200 are given in the following tables 2-1 and 2-2.
TABLE 2-1
TABLE 2-2
In the above table, f is the focal length of the optical system, and f1 to f5 are the focal lengths of the respective lenses in order.
The detailed optical data of this example are shown in tables 2-3 below
Tables 2 to 3
Referring to fig. 7, 8, 9 and 10, fig. 7 shows a modulation function analysis chart of the optical lens 200 of the second embodiment, 100 lines to time, a multi-field diffraction transfer function reaches 41%, fig. 8 shows a full-field root mean square size chart of the optical lens 200 of the second embodiment, the root mean square size chart is smaller than 0.0044, fig. 9 shows a distortion chart of the optical lens 200 of the second embodiment in a visible light band, a distortion range is smaller than 30.39%, and fig. 10 shows a relative illuminance diagram of the optical lens 200 of the second embodiment.
By comparing the above illustrated data information, it can be seen that the total length of the optical lens 200 is smaller than that of the system of the optical lens 100 on the premise of meeting the imaging index, and the range of distortion and root mean square size is better than that of the optical lens, so that the volume of the capsule endoscope can be better reduced, the capsule endoscope can conveniently obtain more flexible and wide working space when working in a human body, and also can save more space for other structures of the capsule endoscope, and obtain better imaging quality.
For the wavelengths and related parameters corresponding to the curves in fig. 7, 8, 9 and 10, reference may be made to the descriptions in fig. 2, 3, 4 and 5 in the first embodiment, and the descriptions are omitted here.
Third embodiment
As shown in fig. 11, a schematic structural diagram of an optical lens 300 according to a second embodiment of the present application is shown, where the optical lens 300 includes a first lens L11, a second lens L12, a third lens L13, a fourth lens L14, and a fifth lens L15, which are sequentially disposed from an object side to an image side along an optical axis. In imaging, light enters the first lens L11, the second lens L12, the third lens L13, the fourth lens L14, and the fifth lens L15 in order from the object side of the first lens L11, and finally is imaged on the imaging surface 301 of the optical lens 300. Wherein the first lens L11 has negative power, the second lens L12 has negative power, the third lens L13 has negative power, the fourth lens L14 has positive power, and the fifth lens L15 has negative power.
Further, the object-side surface S21 of the first lens element L11 is convex at the paraxial region O, and the image-side surface S22 of the first lens element L11 is concave at the paraxial region O; the object side surface S23 of the second lens element L12 is convex at a paraxial region O, and the image side surface S24 of the second lens element L12 is concave at the paraxial region O; the object side surface S25 of the third lens element L13 is concave at a paraxial region O, and the image side surface S26 of the third lens element L13 is convex at the paraxial region O; the object-side surface S27 of the fourth lens element L14 is convex at a paraxial region O, and the image-side surface S28 of the fourth lens element L14 is convex at the paraxial region O; the object-side surface S29 of the fifth lens element L15 is convex at a paraxial region O, and the image-side surface S30 of the fifth lens element L15 is concave at the paraxial region O.
Specifically, taking the focal length f=1.359 mm of the optical lens 300, the f-number fnum=2.74 of the optical lens 300, the maximum field half angle hfov=50° of the optical lens 300, the distance ttl=6.08 mm from the object side surface S21 of the first lens L11 to the image side surface S30 of the fifth lens L15 of the optical lens 300 on the optical axis O as an example, other parameters of the optical lens 300 are given in the following tables 3-1 and 3-2.
TABLE 3-1
TABLE 3-2
In the above table, f is the focal length of the optical system, and f1 to f6 are the focal lengths of the respective lenses in order.
The detailed optical data of this example are shown in tables 3-3 below
TABLE 3-3
Referring to fig. 12, 13, 14 and 15, fig. 12 shows a modulation function analysis chart of the optical lens 300 of the third embodiment, 100 lines to time, a multi-field diffraction transfer function reaches 42%, fig. 13 shows a full-field root mean square size chart of the optical lens 300 of the third embodiment, the root mean square size is smaller than 0.0043, fig. 14 shows a distortion chart of the optical lens 300 of the third embodiment in a visible light band, a distortion range is smaller than 29.25%, and fig. 15 shows a relative illuminance diagram of the optical lens 200 of the third embodiment.
By comparing the above illustrated data information, it can be seen that the optical lens 300 is slightly increased in system length relative to the optical lens 100, so as to obtain better imaging quality, and the range of distortion and root mean square size is better than that of the optical lens 100, so that the capsule endoscope can obtain better imaging quality in the human body, and the doctor is helped to reduce the probability of subjective judgment error caused by poor image effect.
The wavelengths and the related parameters corresponding to the curves in fig. 12, 13, 14 and 15 can be referred to in the first embodiment for the descriptions in fig. 2, 3, 4 and 5, and are not repeated here.
Therefore, the capsule endoscope lens provided by the application can meet the requirements of large field angle, low distortion and high illumination of a system.
The optical lens disclosed in the embodiments of the present application is described in detail, and specific examples are applied to illustrate the principles and embodiments of the present application, and the description of the above examples is only for helping to understand the optical lens and the core ideas of the present application; meanwhile, as those skilled in the art will vary in the specific embodiments and application scope according to the idea of the present application, the present disclosure should not be construed as limiting the present application in summary.
Claims (8)
1. An optical lens of a capsule endoscope, which is characterized in that: the optical lens of the microcapsule endoscope comprises a first lens with negative focal power, a second lens with negative focal power, a third lens with negative focal power, a fourth lens with positive focal power and a fifth lens with negative focal power, which are sequentially arranged from an object side to an image side along an optical axis;
the first lens element has negative refractive power, wherein an object-side surface of the first lens element is convex at a paraxial region thereof, and an image-side surface of the first lens element is concave at a paraxial region thereof;
the second lens has negative focal power, the object side surface of the second lens is a convex surface at a paraxial region, and the image side surface of the second lens is a concave surface at the paraxial region;
the third lens element has negative refractive power, wherein an object-side surface of the third lens element is concave at a paraxial region thereof, and an image-side surface of the third lens element is convex at a paraxial region thereof;
the fourth lens element has positive refractive power, wherein an object-side surface of the fourth lens element is convex at a paraxial region thereof, and an image-side surface of the fourth lens element is convex at a paraxial region thereof;
the fifth lens element has negative refractive power, wherein an object-side surface of the fifth lens element is convex at a paraxial region thereof, and an image-side surface of the fifth lens element is concave at a paraxial region thereof;
a diaphragm is arranged between the third lens and the fourth lens;
the structures of the third lens, the fourth lens and the fifth lens form negative-positive structural symmetry;
the endoscope optical lens satisfies the relation:wherein FNUM is the relative aperture of the optical lens, f is the focal length of the optical lens, B is the back focal length of the optical lens, and alpha is the half-diameter of the diffusion at the 0 field of view;
the optical lens of the microcapsule endoscope meets the relation: 2< FNUM/TAN (HFOV) <2.5, wherein HFOV is half of the maximum field angle of the optical lens, TAN (HFOV) is the tangent of HFOV angle, FNUM is the relative aperture of the optical lens;
the optical lens of the microcapsule endoscope meets the relation: TTL/f is more than 4 and less than 5; wherein TTL is a distance from an object side surface of the first lens to an imaging surface of the optical lens on the optical axis, and f is a focal length of the optical lens.
2. The optical lens of claim 1, wherein: the optical lens satisfies the following conditional expression:the HFOV is the horizontal angle of view of the optical system, and TTL is the total optical length of the optical lens.
3. The optical lens of claim 1, wherein: the optical lens satisfies the following conditional expression:wherein f1 is the focal length of the first lens, f2 is the focal length of the second lens, f4 is the focal length of the fourth lens, and f5 is the focal length of the fifth lens.
4. The optical lens of claim 1, wherein: the optical lens satisfies the following conditional expression: fnum=2.83, FNUM being the relative aperture of the optical lens.
5. The optical lens of claim 1, wherein: the optical lens satisfies the following conditional expression:w is the half field angle of the optical lens.
6. The optical lens of claim 1, wherein: the optical lens satisfies the following conditional expression: ttl=6mm, TTL is the optical total length of the optical lens.
7. The optical lens of claim 1, wherein: the optical lens satisfies the following conditional expression:θ is the optical system distortion.
8. The optical lens of claim 1, wherein: the optical lens satisfies the following conditional expression: the relative illumination is more than 95% of the full field of view and is uniformly distributed.
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