CN112433341A - Imaging system - Google Patents

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Publication number
CN112433341A
CN112433341A CN202011134383.3A CN202011134383A CN112433341A CN 112433341 A CN112433341 A CN 112433341A CN 202011134383 A CN202011134383 A CN 202011134383A CN 112433341 A CN112433341 A CN 112433341A
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lens group
lens
imaging system
lenses
group
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Inventor
胡可欣
刘保东
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Sunny Optics Zhongshan Co Ltd
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Sunny Optics Zhongshan Co Ltd
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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
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B13/00—Optical objectives specially designed for the purposes specified below
    • G02B13/18—Optical objectives specially designed for the purposes specified below with lenses having one or more non-spherical faces, e.g. for reducing geometrical aberration

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Abstract

The invention relates to an imaging system, which comprises a first lens group (G1), a second lens group (G2), a third lens group (G3) and a Stop (STO), wherein the first lens group (G1) is a fixed group, the third lens group (G3) is a movable focusing group, and the second lens group (G2) is a fixed group. Aiming at the requirements and technical defects of the video conference imaging system in the market at present, the invention provides an imaging system which has a large aperture (Fno is less than or equal to 2.0), low distortion, high pixel, uniform image quality and resolution of more than 3000 ten thousand pixels, and has the characteristic of stable image quality of pictures in abnormal states of high temperature, low temperature and the like.

Description

Imaging system
Technical Field
The invention relates to the technical field of optical imaging, in particular to an imaging system.
Background
Along with the continuous and rapid construction of the Chinese information communication network, the Chinese communication level is greatly improved, and reliable guarantee is provided for information exchange of various industries. Video conferencing is a multimedia communication method that utilizes television technology and equipment to hold a conference via a communication network. When a video conference is held, the conference representatives in two or more different places can hear the sound of the opposite party and see the image of the opposite party, and also can see the scene of the conference room of the opposite party and the real objects, pictures, forms, files and the like displayed in the conference, thereby shortening the distance between the conference representatives, enhancing the atmosphere of the conference, leading people to be as if the people are participating in the conference at the same place and obviously improving the working efficiency.
Therefore, imaging systems for video conferencing have very high requirements on pixels, picture uniformity, distortion, color rendition, etc. However, the video conference lens in the market at present has large distortion, low picture consistency and the like, and the video conference lens has the defects of insufficient definition of imaging, low dynamic range during imaging and the like.
With the frequent application of video conferences, the requirements on the video conference imaging system are higher and higher, and the video conference lens on the market at present cannot meet the market requirements more and more, and is severely limited in some fields with higher imaging quality requirements.
Disclosure of Invention
It is an object of the present invention to provide an imaging system that meets the requirements of a video conference.
In order to achieve the above object, the present invention provides an imaging system, which includes a first lens group, a second lens group, a third lens group and a stop, wherein the first lens group is a fixed group, the third lens group is a movable focusing group, and the second lens group is a fixed group.
According to an aspect of the present invention, the first lens group has five lenses, wherein the five lenses at least include two positive lenses and two negative lenses, the lenses closest to the object side and the image side are both negative lenses, and at least two lenses form a double cemented lens group.
According to an aspect of the invention, in the first lens group, a first lens from an object side to an image side is a concave-convex type, a second lens is a concave-convex type or a concave-convex type, and a third lens is a convex-convex type, a concave-convex type or a convex-flat type.
According to an aspect of the invention, the second lens group has three lenses, wherein the three lenses at least include a positive lens and a negative lens, the lens closest to the object side is the negative lens, and two lenses form a double cemented lens group;
the two lenses forming the double cemented lens group are a negative lens and a positive lens in sequence from the object space to the image space.
According to an aspect of the invention, the third lens group has two lenses, wherein the two lenses include a negative lens and a positive lens, and at least one of the lenses is an aspheric lens.
According to an aspect of the present invention, the powers of the first lens group, the second lens group, and the third lens group are all positive;
the stop is located between the first lens group and the second lens group;
when imaging from an infinite-distance object to a close-distance object, the third lens group moves along the optical axis to finish focusing.
According to an aspect of the present invention, a fixed group focal length f of the first lens group and the second lens groupMAnd the focal length f of the imaging system satisfies the following relation:
0.5≤fM/f≤2.0。
according to an aspect of the invention, a focal length f of the third lens groupG3And the focal length f of the imaging system satisfies the following relation:
1.5≤|fG3/f|≤7.5。
according to one aspect of the invention, the full optical length TTL and the focal length f of the imaging system satisfy the following relation:
7.76≤TTL/f≤10.82。
according to an aspect of the present invention, in the double cemented lens group of the second lens group, a positive lens refractive index ND and an abbe number VD satisfy the following relations:
60≤VD≤96；
and
1.43≤ND≤1.85。
according to the present invention, there is provided an imaging system having a large aperture (Fno ≤ 2.0), low distortion, high pixel count, uniform image quality, and a resolution of 3000 pixels or more, and having a characteristic of stable image quality of a screen in abnormal states such as high temperature and low temperature.
According to an aspect of the present invention, an imaging system includes a first lens group, a second lens group, and a third lens group arranged in this order from an object side to an image side along an optical axis, and a stop located between the first lens group and the second lens group. The first lens group is a fixed group, and the third lens group is a movable focusing group. The focal powers of the three lens groups are positive, so that the whole imaging system has smaller distortion and smaller astigmatism by matching the focal powers. The lenses in each group are matched with proper refractive index and Abbe number, so that the imaging system has lower dispersion. Moreover, the first lens group and the second lens group jointly form a double-Gaussian-like structure, and the double-Gaussian-like structure is beneficial to reducing aberrations such as distortion, field curvature and astigmatism of the system.
According to an aspect of the present invention, the first lens group has five lenses, wherein the five lenses at least include two positive lenses and two negative lenses, at least two lenses form a double cemented lens group, and the lenses closest to the object side and the image side are negative lenses. And the first lens from the object space to the image space is of a convex-concave type, the second lens is of a biconcave type or a concave-convex type, and the third lens is of a biconvex type, a convex-concave type or a convex-flat type. The first lens group is located at the front end of the imaging system, and the negative lens can well converge light rays, so that the imaging system has a larger space-free imaging range. The double-cemented lens is matched with proper focal power, and has good effect on the distortion, the coma aberration and the lateral chromatic aberration of the correction system, thereby ensuring that the optical system has the consistency of image quality and image surface close to the diffraction limit.
According to an embodiment of the present invention, the second lens group has three lenses, wherein the three lenses at least include a positive lens and a negative lens, the two lenses form a double cemented lens group, and the lens closest to the object side is the negative lens. Moreover, the two lenses forming the double cemented lens set are a negative lens and a positive lens in sequence from the object side to the image side. The use of the double combined lens group in the second lens group, with proper focal power, can be matched with the first lens group to correct spherical aberration, astigmatism, coma and distortion in the focusing lens group. Meanwhile, the burden proportion of the first lens group to aberration correction is reduced, and the tolerance sensitivity of the movable group can be better reduced, so that the optical system is greatly ensured to have good image plane consistency, and the imaging quality of the optical system is comprehensively improved.
According to an aspect of the invention, the third lens group has two lenses, wherein the two lenses include a negative lens and a positive lens, and at least one of the lenses is an aspheric lens. Therefore, the focusing group is matched with the positive and negative lenses, so that the reduction of the image plane incidence angle is facilitated, and the function of reducing the imaging system aberration is also realized. The aspheric lens is used for correcting and balancing system aberration.
According to one scheme of the invention, the imaging system comprises a double-Gaussian structure, so that distortion can be well corrected, light rays can be well converged, dark corners can be eliminated, and spherical aberration can be reduced.
According to the scheme of the invention, the fixed lens group focal length f consisting of the first lens group and the second lens groupMAnd the focal length f of the imaging system satisfies the following relation: f is not less than 0.5MThe/f is less than or equal to 2.0. Meeting this requirement can enable the optical system to achieve and maintain less distortion while collecting incident light rays quickly, reducing curvature of field and astigmatism. Focal length f of the third lens groupG3And the focal length f of the imaging system satisfies the following relation: f is more than or equal to 1.5G3The/| is less than or equal to 7.5. The requirement is met, the high focusing efficiency can be ensured, and meanwhile, the corresponding focusing sensitivity can be ensured according to the requirement; meanwhile, the burden proportion of the first lens group and the second lens group of the optical system on aberration correction is balanced by reasonably matching the positive and negative focal powers and the focal powers of the first lens group and the second lens group. The total optical length TTL and the focal length f of the imaging system satisfy the following relational expression: TTL/f is more than or equal to 7.76 and less than or equal to 10.82. In the double-cemented lens group of the second lens group, the refractive index of the positive lens is ND and the Abbe number is VD, which satisfy the following relational expression: VD is more than or equal to 60 and less than or equal to 96; ND is more than or equal to 1.43 and less than or equal to 1.85. The condition of the focal power and the Abbe number is satisfied, the chromatic aberration of the imaging system can be effectively corrected, and the imaging quality of the imaging system is improved. Meanwhile, the positive lens greatly contributes to maintaining the stability of the image plane of the imaging system in an extremely warm state.
Drawings
Fig. 1 schematically shows a block diagram of an imaging system according to a first embodiment of the invention;
FIG. 2 schematically shows an MTF plot in focus for an optimal working object distance for an imaging system according to a first embodiment of the present invention;
FIG. 3 schematically shows an optical distortion diagram of an imaging system according to a first embodiment of the present invention;
FIG. 4 schematically shows a block diagram of an imaging system according to a second embodiment of the invention;
FIG. 5 schematically shows an MTF plot in focus for an optimal working object distance for an imaging system according to a second embodiment of the present invention;
FIG. 6 schematically shows an optical distortion diagram of an imaging system according to a second embodiment of the present invention;
fig. 7 is a view schematically showing the construction of an image forming system according to a third embodiment of the present invention;
FIG. 8 schematically shows an MTF plot in focus for an optimal working object distance for an imaging system according to a third embodiment of the present invention;
FIG. 9 schematically shows an optical distortion diagram of an imaging system according to a third embodiment of the present invention;
fig. 10 is a view schematically showing the construction of an image forming system according to a fourth embodiment of the present invention;
FIG. 11 schematically shows an MTF plot in focus for an optimal working object distance for an imaging system according to a fourth embodiment of the present invention;
fig. 12 schematically shows an optical distortion diagram of an imaging system according to a fourth embodiment of the present invention;
fig. 13 is a view schematically showing the construction of an image forming system according to a fifth embodiment of the present invention;
FIG. 14 schematically shows an MTF plot in focus for an optimal working object distance for an imaging system according to a fifth embodiment of the present invention;
fig. 15 schematically shows an optical distortion diagram of an imaging system according to a fifth embodiment of the present invention.
Detailed Description
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments will be briefly described below. It is obvious that the drawings in the following description are only some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive effort.
In describing embodiments of the present invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are used in an orientation or positional relationship that is based on the orientation or positional relationship shown in the associated drawings, which is for convenience and simplicity of description only, and does not indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and thus, the above-described terms should not be construed as limiting the present invention.
The present invention is described in detail below with reference to the drawings and the specific embodiments, which are not repeated herein, but the embodiments of the present invention are not limited to the following embodiments.
Referring to fig. 1, the imaging system of the present invention includes a first lens group G1, a second lens group G2, and a third lens group G3 arranged in this order from an object side to an image side along an optical axis, and a stop STO disposed between the first lens group G1 and the second lens group G2. The first lens group G1 is a fixed group, and the third lens group G3 is a movable focusing group. According to the concept of the present invention, the second lens group G2 is also a fixed group, so that the first lens group G1 and the second lens group G2 together form a double-gauss-like structure, which is beneficial to reducing aberrations such as distortion, curvature of field, astigmatism and the like of the system. In the invention, the focal powers of the three lens groups are all positive, so that the whole imaging system has smaller distortion and smaller astigmatism by matching the focal powers. The lenses in each group are matched with proper refractive index and Abbe number, so that the imaging system has lower dispersion.
In the present invention, the first lens group G1 has five lenses, at least including two positive lenses and two negative lenses, at least two lenses form a double cemented lens group, and the lens closest to the object side and the lens closest to the image side are negative lenses. And the first lens from the object space to the image space is of a convex-concave type, the second lens is of a biconcave type or a concave-convex type, and the third lens is of a biconvex type, a convex-concave type or a convex-flat type. The first lens group G1 is located at the front end of the imaging system, wherein the negative lens can well converge light, so that the imaging system has a large imaging range without space. The double-cemented lens is matched with proper focal power, and has good effect on the distortion, the coma aberration and the lateral chromatic aberration of the correction system, thereby ensuring that the optical system has the consistency of image quality and image surface close to the diffraction limit.
In the present invention, the second lens group G2 has three lenses, at least including a positive lens and a negative lens, two lenses form a double cemented lens group, and the lens closest to the object side is the negative lens. Moreover, the two lenses forming the double cemented lens set are a negative lens and a positive lens in sequence from the object side to the image side. The use of the double-lens combination in the second lens group G2, in combination with a suitable focal power, can be used in combination with the first lens group G1 to correct spherical aberration, astigmatism, coma and distortion in the focusing lens group. Meanwhile, the burden proportion of the first lens group G1 on aberration correction is reduced, and the tolerance sensitivity of the movable group can be better reduced, so that the optical system is greatly ensured to have good image plane consistency, and the imaging quality of the optical system is comprehensively improved.
In the present invention, the third lens group G3 has two lenses, including a negative lens and a positive lens, and at least one of the lenses is an aspheric lens. Therefore, the focusing group is matched with the positive and negative lenses, so that the reduction of the image plane incidence angle is facilitated, and the function of reducing the imaging system aberration is also realized. The aspheric lens is used for correcting and balancing system aberration.
Therefore, the imaging system comprises the double-Gaussian structure, so that distortion can be well corrected, light rays can be converged, dark angles can be eliminated, and spherical aberration can be reduced.
In the present invention, the fixed focal length f of the lens group composed of the first lens group G1 and the second lens group G2MAnd the focal length f of the imaging system satisfies the following relation: f is not less than 0.5MThe/f is less than or equal to 2.0. Meeting this requirement can enable the optical system to achieve and maintain less distortion while collecting incident light rays quickly, reducing curvature of field and astigmatism. Focal length f of third lens group G3G3And the focal length f of the imaging system satisfies the following relation: f is more than or equal to 1.5G3The/| is less than or equal to 7.5. The requirement is met, the high focusing efficiency can be ensured, and meanwhile, the corresponding focusing sensitivity can be ensured according to the requirement; meanwhile, the burden proportion of the first lens group G1 and the second lens group G2 of the optical system on aberration correction is balanced by reasonably matching the positive and negative focal power and the focal power of the first lens group and the second lens group. The total optical length TTL and the focal length f of the imaging system satisfy the following relational expression: TTL/f is more than or equal to 7.76 and less than or equal to 10.82. In the double-cemented lens group of the second lens group G2, the positive lens refractive index ND and the abbe number VD satisfy the following relations: VD is more than or equal to 60 and less than or equal to 96; ND is more than or equal to 1.43 and less than or equal to 1.85. The condition of the focal power and the Abbe number is satisfied, the chromatic aberration of the imaging system can be effectively corrected, and the imaging quality of the imaging system is improved. Meanwhile, the positive lens greatly contributes to maintaining the stability of the image plane of the imaging system in an extremely warm state.
Five groups of embodiments are given below to specifically explain the imaging system of the present invention according to the above-described arrangement of the present invention. In the following embodiments, the surfaces of the respective lenses are denoted by sur1, sur2, … and surN, in which the cemented surface of the cemented lens group is one surface and the stop is STO. The parameter settings of the respective embodiments satisfy the following table 1:
Figure BDA0002736189720000081
TABLE 1
The surface types of all the aspherical lenses satisfy the aspherical equation:
Z＝CY2/{1+[1-(1+K)C2Y2]1/2}+A4Y4+A6Y6+A8Y8+A10Y10+A12Y12+A14Y14
wherein, the parameter C is the curvature corresponding to the radius of the aspheric lens, Y is the radial coordinate of the aspheric lens, the unit is the same as the lens length unit, K is the conic coefficient of the aspheric lens, A4，A6…A12Respectively, corresponding order coefficients of the aspheric surface.
Referring to fig. 1, in the following embodiments, the first lens group G1 includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, and a fifth lens L5, which are arranged in order along an optical axis. The fourth lens element L4 and the fifth lens element L5 form a double lens assembly. The second lens group G2 includes a sixth lens L6, a seventh lens L7, and an eighth lens L8, which are arranged in order along the optical axis. The sixth lens element L6 and the seventh lens element L7 form a double lens assembly. The third lens group G3 includes a ninth lens L9 and a tenth lens L10 arranged in order along the optical axis.
The first embodiment:
as shown in fig. 1, in the present embodiment, the second lens L2 is of a biconcave type, and the third lens L3 is of a biconvex type. The parameters of the imaging system in this embodiment are as follows:
the total length TTL of the system is 33 mm; the system focal length f is 4.3 m; the system imaging object distance range is 0.3 m-inf. Other parameters are shown in table 2 below:
Figure BDA0002736189720000091
TABLE 2
The following table 3 shows aspheric coefficients of the aspheric lenses in the present embodiment, where K is a conic constant of the surface, and a4、A6、A8、A10Aspheric coefficients of fourth, sixth, eighth and tenth orders, respectively:
Figure BDA0002736189720000092
Figure BDA0002736189720000101
TABLE 3
With reference to fig. 2 and 3, the imaging system of the present embodiment has an obvious effect on correcting aberration of the imaging system by using the aspheric lens, and can better improve image quality and make it easier to reach a diffraction limit.
The second embodiment:
as shown in fig. 4, in the present embodiment, the second lens L2 is of a concave-convex type, and the third lens L3 is of a biconvex type. The parameters of the imaging system in this embodiment are as follows:
the total length TTL of the system is 36.4 mm; the focal length f of the system is 3.85 mm; the system imaging object distance range is 0.3 m-inf. Other parameters are shown in table 4 below:
Figure BDA0002736189720000102
TABLE 4
The following table 5 shows aspheric coefficients of the aspheric lenses in the present embodiment, where K is a conic constant of the surface, and a4、A6、A8、A10Aspheric coefficients of fourth, sixth, eighth and tenth orders, respectively:
noodle numbering K A4 A6 A8 A10
sur16 -9.21 -4.35E-04 3.65E-05 5.56E-06 0
sur17 12.75 -1.95E-03 -4.52E-05 2.39E-06 0
sur18 6.52 -2.11E-04 -3.02E-06 6.14E-07 0
sur19 -9.16 1.15E-03 -2.68E-06 1.76E-07 0
TABLE 5
With reference to fig. 5 and 6, the imaging system of the present embodiment employs an aspheric lens, which has a significant effect on correcting aberration of the imaging system, and can better improve image quality and make it easier to reach a diffraction limit.
Third embodiment:
as shown in fig. 7, in the present embodiment, the second lens L2 is of a biconcave type, and the third lens L3 is of a convex-concave type. The parameters of the imaging system in this embodiment are as follows:
the total length TTL of the system is 37 mm; the focal length f of the system is 3.9 mm; the system imaging object distance range is 0.3 m-inf; other parameters are shown in table 6 below:
Figure BDA0002736189720000111
Figure BDA0002736189720000121
TABLE 6
The following table 7 shows aspheric coefficients of the aspheric lenses in the present embodiment, where K is a conic constant of the surface, and a4、A6、A8、A10Aspheric coefficients of fourth, sixth, eighth and tenth orders, respectively:
noodle numbering K A4 A6 A8 A10
sur16 -7.51 -2.55E-04 5.25E-06 7.56E-07 0
sur17 7.42 -5.35E-04 -3.12E-06 5.39E-07 0
sur18 6.52 -1.61E-04 -5.12E-06 6.14E-07 0
sur19 -19.26 4.32E-03 -3.38E-06 8.76E-06 0
TABLE 7
With reference to fig. 8 and 9, the imaging system of the present embodiment employs an aspheric lens, which has a significant effect on correcting aberration of the imaging system, and can better improve image quality, so that the imaging system can more easily reach a diffraction limit.
Fourth embodiment:
as shown in fig. 10, in the present embodiment, the second lens L2 is of a biconcave type, and the third lens L3 is of a convex-flat type. The parameters of the imaging system in this embodiment are as follows:
the total length TTL of the system is 36 mm; the focal length f of the system is 3.9 mm; the system imaging object distance range is 0.3 m-inf; other parameters are shown in table 8 below:
Figure BDA0002736189720000131
TABLE 8
The following table 9 shows aspheric coefficients of the aspheric lenses in the present embodiment, where K is a conic constant of the surface, and a4、A6、A8、A10Aspheric coefficients of fourth, sixth, eighth and tenth orders, respectively:
noodle numbering K A4 A6 A8 A10
sur16 -16.28 -3.45E-04 4.35E-06 6.46E-07 0
sur17 6.82 -6.25E-04 -2.32E-06 3.19E-07 0
sur18 5.43 -2.71E-04 -4.82E-06 5.24E-07 0
sur19 -9.16 3.71E-03 -6.88E-06 7.36E-06 0
TABLE 9
With reference to fig. 11 and 12, the imaging system of this embodiment employs an aspheric lens, which has a significant effect on correcting aberration of the imaging system, and can better improve image quality, so that the imaging system can more easily reach a diffraction limit.
Fifth embodiment:
as shown in fig. 13, in the present embodiment, the second lens L2 is of a biconcave type, and the third lens L3 is of a biconvex type. The parameters of the imaging system in this embodiment are as follows:
the total length TTL of the system is 39.5 mm; the focal length f of the system is 3.65 mm; the system imaging object distance range is 0.3 m-inf; other parameters are shown in table 10 below:
Figure BDA0002736189720000141
watch 10
The following table 11 shows aspheric coefficients of the aspheric lenses in the present embodiment, where K is a conic constant of the surface, and a4、A6、A8、A10Aspheric coefficients of fourth, sixth, eighth and tenth orders, respectively:
noodle numbering K A4 A6 A8 A10
sur16 -3.28 -3.35E-04 4.55E-06 1.36E-07 0
sur17 6.82 -6.15E-04 -2.72E-06 1.29E-07 0
sur18 5.43 -2.21E-04 -4.32E-06 1.34E-07 0
sur19 -9.16 3.61E-04 -6.58E-06 1.16E-07 0
TABLE 11
With reference to fig. 14 and fig. 15, the imaging system of this embodiment employs an aspheric lens, which has a significant effect on correcting aberration of the imaging system, and can better improve image quality, so that the imaging system can more easily reach a diffraction limit.
The above description is only one embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. An imaging system comprising a first lens group (G1), a second lens group (G2), a third lens group (G3) and a Stop (STO), the first lens group (G1) being a fixed group, the third lens group (G3) being a movable focusing group, characterized in that the second lens group (G2) is a fixed group.
2. The imaging system of claim 1, wherein the first lens group (G1) has five lenses, at least two positive lenses and two negative lenses, and the lenses closest to the object and the image are both negative lenses, at least two lenses forming a double cemented lens group.
3. The imaging system of claim 2, wherein in the first lens group (G1), a first lens from an object side to an image side is concave-convex, a second lens is concave-convex or concave-convex, and a third lens is convex-convex, concave-convex or convex-flat.
4. The imaging system of claim 1, wherein the second lens group (G2) has three lenses, at least one positive lens and one negative lens, the lens closest to the object is the negative lens, and two lenses form a double cemented lens group;
the two lenses forming the double cemented lens group are a negative lens and a positive lens in sequence from the object space to the image space.
5. The imaging system of claim 1, wherein the third lens group (G3) has two lenses, including a negative lens and a positive lens, and at least one of the lenses is an aspheric lens.
6. The imaging system of claim 1, wherein the optical powers of the first lens group (G1), the second lens group (G2), and the third lens group (G3) are all positive;
the Stop (STO) is located between the first lens group (G1) and the second lens group (G2);
when imaging from an infinite-distance object to a close-distance object, the third lens group (G3) moves along the optical axis to complete focusing.
7. The imaging system of any of claims 1-6, wherein the first lens group (G1) and the second lens group (G2) constitute a fixed group focal length fMAnd the focal length f of the imaging system is satisfied withThe following relation:
0.5≤fM/f≤2.0。
8. the imaging system according to any of claims 1-6, characterized in that the focal length f of the third lens group (G3)G3And the focal length f of the imaging system satisfies the following relation:
1.5≤|fG3/f|≤7.5。
9. the imaging system of any of claims 1-6, wherein the full optical length, TTL, and the focal length, f, of the imaging system satisfy the following relationship:
7.76≤TTL/f≤10.82。
10. an imaging system according to claim 4, wherein said double cemented lens group of the second lens group (G2) has a positive lens refractive index ND and an Abbe number VD satisfying the following relation:
60≤VD≤96；
and
1.43≤ND≤1.85。
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114732353A (en) * 2022-06-13 2022-07-12 南京览视医疗科技有限公司 High-resolution fundus optical imaging system

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114732353A (en) * 2022-06-13 2022-07-12 南京览视医疗科技有限公司 High-resolution fundus optical imaging system

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