CN111929811A

CN111929811A - Lens

Info

Publication number: CN111929811A
Application number: CN202010771779.2A
Authority: CN
Inventors: 张冬
Original assignee: Hubei Hekou Photoelectric Co ltd
Current assignee: Hubei Hekou Photoelectric Co ltd
Priority date: 2020-08-04
Filing date: 2020-08-04
Publication date: 2020-11-13

Abstract

The invention discloses a lens, comprising: the first lens group, the second lens group, the third lens group, the fourth lens group, the light splitting device, the filtering device and the identification device are sequentially arranged between the object side and the imaging side; the inlet of the light splitting device is connected with the outlet of the fourth lens group, the outlet of the light splitting device is connected with the inlet of the light filtering device, and the light splitting device is used for splitting the light beam at the outlet of the fourth lens group into a horizontal light beam and a vertical light beam and independently sending the horizontal light beam and the vertical light beam to the light filtering device; the filtering device is used for receiving the horizontal light beams and the vertical light beams, filtering the horizontal light beams and the vertical light beams, and independently sending the filtered horizontal light beams and the filtered vertical light beams to the recognition device; the identification device is used for receiving and identifying the horizontal light beams and the vertical light beams which are subjected to the filtering processing.

Description

Lens

Technical Field

The invention relates to the technical field of optical imaging, in particular to a lens.

Background

Along with the development of society, people's safety precaution consciousness is constantly improved, and security protection monitoring industry also obtains high-speed development, and the effect of control performance is also bigger and bigger. The zoom lens has practical design and use in the last century, and with the development of lens design technology, the application occasions of the zoom lens are gradually increased. Nowadays, zoom lenses have been widely used in the fields of civil products, security monitoring, and the like. For example, 3D identification lenses with high pixels, wide wavelength bands and large apertures are mostly used in the fields of vehicle-mounted, machine vision, public safety, monitoring and the like, in public safety identification, a dual-lens mode is mostly adopted, and visible light and infrared light are respectively identified through dual CMOS (Complementary Metal Oxide Semiconductor), but the dual-lens involves software splicing and complex algorithm processing, and has a complex structure and high cost, which is not beneficial to improving market competitiveness.

Disclosure of Invention

The present invention is directed to solving at least one of the problems of the prior art.

Therefore, the invention provides the lens which can be used for independently identifying visible light and infrared light, has a simple structure and is beneficial to reducing the cost.

A lens barrel according to an embodiment of the present invention includes: the optical lens comprises a first lens group, a second lens group, a third lens group, a fourth lens group, a light splitting device, a filtering device and a recognition device, wherein the first lens group, the second lens group, the third lens group, the fourth lens group, the light splitting device, the filtering device and the recognition device are sequentially arranged between an object side and an imaging side; the light splitting device is arranged between the fourth lens group and the filtering device, an inlet of the light splitting device is connected with an outlet of the fourth lens group, an outlet of the light splitting device is connected with an inlet of the filtering device, and the light splitting device is used for dividing a light beam at the outlet of the fourth lens group into a horizontal light beam and a vertical light beam and independently sending the horizontal light beam and the vertical light beam to the filtering device;

the light filtering device is arranged between the light splitting device and the identification device and is used for receiving the horizontal light beams and the vertical light beams, filtering the horizontal light beams and the vertical light beams and independently sending the filtered horizontal light beams and the filtered vertical light beams to the identification device;

the identification device is used for receiving and identifying the filtered horizontal light beams and the filtered vertical light beams.

The lens disclosed by the embodiment of the invention at least has the following beneficial effects: the aberration is reduced by the multiple groups of lens groups, and the imaging quality is improved; the light beams passing through the multiple groups of lens groups are divided into horizontal light beams and vertical light beams by the light splitting device, and the horizontal light beams and the vertical light beams are independently sent to the light filtering device for light filtering treatment; the filtering device independently sends the filtered horizontal light beams and the filtered vertical light beams to the recognition device for independent recognition imaging; by adopting the lens in the technical scheme, the visible light and the infrared light can be independently identified, and the lens has the functions of double lenses, is simple in structure and is beneficial to reducing the cost.

According to some embodiments of the invention, the first lens group comprises a first lens and a second lens; wherein the first lens and the second lens are both negative power lenses, the first lens and the second lens are both crescent in shape, the convex surface side of the first lens faces the object side, and the concave surface side of the first lens faces the convex surface side of the second lens.

According to some embodiments of the invention, the first lens satisfies the following condition: -44 < f (100) < -25; 1.7 < D₁/R₂＜1.82；1.7＜Nd₁Less than 1.8; wherein f (100) is the focal length of the first lens, Nd₁Is the refractive index of the first lens, D₁Is the diameter of the concave side of the first lens, R₂Is the radius of curvature of the concave side of the first lens.

According to some embodiments of the invention, the second lens group comprises a third lens and a fourth lens; wherein the third lens and the fourth lens are cemented at their edges to form a negative power lens, the third lens is crescent-shaped, the fourth lens is a biconcave lens, the concave side of the third lens faces the concave side of the second lens, the convex side of the third lens faces the fourth lens, and the radius of curvature of the fourth lens facing the concave side of the third lens is the same as the radius of curvature of the convex side of the third lens.

According to some embodiments of the invention, the third lens group comprises a fifth lens and a sixth lens; wherein the fifth lens and the sixth lens are both double convex lenses and are both positive power lenses, and the fifth lens is disposed between the fourth lens and the sixth lens.

According to some embodiments of the invention, the fifth lens and the sixth lens satisfy the following condition: 1.1 < | f (500)/f (600) | < 2.2; wherein f (500) is the focal length of the fifth lens, and f (600) is the focal length of the sixth lens.

According to some embodiments of the invention, the fourth lens group comprises a seventh lens and an eighth lens; wherein edges of the seventh lens and the eighth lens are cemented to form a positive power lens, the seventh lens is a meniscus lens, the eighth lens is a double convex lens, a convex surface side of the seventh lens faces the sixth lens, a concave surface side of the seventh lens faces a convex surface side of the eighth lens, and a radius of curvature of the concave surface side of the seventh lens is the same as a radius of curvature of the convex surface side of the eighth lens.

According to some embodiments of the invention, the third lens, the sixth lens and the seventh lens satisfy the following condition: 2.6 < | R₃₁/R₆₁+R₇₁| is less than 4; wherein R is₃₁Radius of curvature, R, of the concave side of the third lens₆₁Radius of curvature, R, of the sixth lens element on the side facing the fifth lens element₇₁Is the radius of curvature of the convex side of the seventh lens.

According to some embodiments of the invention, the first lens and the seventh lens satisfy the following condition: r₁₂＞R₇₂(ii) a Wherein R is₁₂Is the radius of curvature, R, of the concave side of the first lens₇₂Is the radius of curvature of the concave side of the seventh lens.

According to some embodiments of the invention, the fourth lens group further comprises a ninth lens and a tenth lens; wherein edges of the ninth lens and the tenth lens are cemented to form a negative power lens, the ninth lens is a biconcave lens, the tenth lens is a biconvex lens, and a radius of curvature of the ninth lens toward a concave surface side of the tenth lens is the same as a radius of curvature of the tenth lens toward a convex surface side of the ninth lens.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

fig. 1 is a schematic structural diagram of a lens barrel according to an embodiment of the present invention;

FIG. 2 is a diagram of the path of a light beam through a lens according to one embodiment of the present invention;

fig. 3 is a schematic structural diagram of a lens barrel according to another embodiment of the present invention;

FIG. 4 is a diagram of the path of a light beam through a lens according to another embodiment of the present invention;

FIG. 5 is a graph of transfer function (MTF) of the lens at 400-700nm according to an embodiment of the present invention;

FIG. 6 is a graph of transfer function (MTF) of the lens at 800-1000nm according to the embodiment of the present invention.

Reference numerals:

a first lens group G1, a second lens group G2, a third lens group G3, a fourth lens group G4, a first lens 100, a second lens 200, a third lens 300, a fourth lens 400, a fifth lens 500, a sixth lens 600, a seventh lens 700, an eighth lens 800, a ninth lens 900, a tenth lens 110, an eleventh lens 120, a twelfth lens 130, a light splitting device 140, a light filtering device 150, a first optical filter 1501, a second optical filter 1502, a recognition device 160, a first chip 1601, a second chip 1602, a first protection window 1603, a second protection window 1604

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.

In the description of the present invention, it is to be understood that, in relation to the orientation description, the terms "central, longitudinal, transverse, length, width, thickness, upper, lower, front, rear, left, right, vertical, horizontal, top, bottom, inner, outer, circumferential, radial, circumferential" and the like indicate an orientation or positional relationship based on that shown in the drawings, which is merely for convenience of description and simplicity of description, and does not indicate or imply that the device or element so referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore, should not be considered as limiting the present invention.

In the description of the present invention, the meaning of a plurality of means is one or more, the meaning of a plurality of means is two or more, and larger, smaller, larger, etc. are understood as excluding the number, and larger, smaller, inner, etc. are understood as including the number. If the first and second are described for the purpose of distinguishing technical features, they are not to be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated or implicitly indicating the precedence of the technical features indicated.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

A lens barrel according to an embodiment of the present invention is described below with reference to fig. 1 and 3.

As shown in fig. 1 and 3, a lens barrel according to an embodiment of the present invention includes a first lens group G1, a second lens group G2, a third lens group G3, a fourth lens G4, a light splitting device 140, a filtering device 150, and a recognition device 160, and the first lens group G1, the second lens group G2, the third lens group G3, the fourth lens G4, the light splitting device 140, the filtering device 150, and the recognition device 160 are sequentially disposed between an object side and an image side.

Specifically, the light splitting device 140 is disposed between the fourth lens group G4 and the filtering device 150, an inlet of the light splitting device 140 is connected to an outlet of the fourth lens group G4, an outlet of the light splitting device 140 is connected to an inlet of the filtering device 150, as shown in fig. 2 and 4, the light splitting device 140 is configured to split the light beam at the outlet of the fourth lens group G4 into a horizontal light beam and a vertical light beam, and independently send the horizontal light beam and the vertical light beam to the filtering device 150. The filtering device 150 is disposed between the light splitting device 140 and the identification device 160, and the filtering device 150 is configured to receive the horizontal light beam and the vertical light beam, filter the horizontal light beam and the vertical light beam, and independently transmit the filtered horizontal light beam and the filtered vertical light beam to the identification device 160. The recognition device 160 is used for receiving and recognizing the horizontal light beam and the vertical light beam which are processed by filtering, and imaging the light beams.

The aberration is reduced by the multiple groups of lens groups, and the imaging quality is improved; the light beams passing through the multiple groups of lens groups are divided into horizontal light beams and vertical light beams by the light splitting device 140, and the horizontal light beams and the vertical light beams are independently sent to the filtering device 150 for filtering; the filtering device 150 independently transmits the filtered horizontal light beam and the filtered vertical light beam to the recognition device 160 for independent recognition imaging; by adopting the lens in the technical scheme, the visible light and the infrared light can be independently identified, and the lens has the functions of double lenses, is simple in structure and is beneficial to reducing the cost.

In some embodiments of the present invention, the first lens group G1 includes a first lens 100 and a second lens 200, the first lens 100 and the second lens 200 are both negative power lenses, the first lens 100 and the second lens 200 are both crescent-shaped, the convex surface side of the first lens 100 faces the object side, and the concave surface side of the first lens 100 faces the convex surface side of the second lens 200.

Further, the first lens satisfies the following condition: -44 < f (100) < -25; D1/R2 is more than 1.7 and less than 1.82;

nd1 is more than 1.7 and less than 1.8; where f (100) is the focal length of the first lens 100, Nd1 is the refractive index of the first lens 100, D1 is the diameter of the concave side of the first lens (100), i.e., the diameter of the meniscus (lens right effective clear aperture) of the first lens (100), and R2 is the radius of curvature of the concave side of the first lens (100).

In some embodiments of the present invention, the second lens group G2 includes a third lens 300 and a fourth lens 400, the edges of the third lens 300 and the fourth lens 400 are cemented to form a negative power lens, the third lens 300 is crescent-shaped, the fourth lens 400 is a double concave lens, the concave side of the third lens 300 faces the concave side of the second lens 200, the convex side of the third lens 300 faces the fourth lens 400, and the radius of curvature of the fourth lens 400 toward the concave side of the third lens 300 is the same as the radius of curvature of the convex side of the third lens 300.

In some embodiments of the present invention, third lens group G3 includes fifth lens 500 and sixth lens 600; the fifth lens 500 and the sixth lens 600 are both double convex lenses and are both positive power lenses, and the fifth lens 500 is disposed between the fourth lens 400 and the sixth lens 600.

Further, the fifth lens 500 and the sixth lens 600 satisfy the following condition: 1.1 < | f (500)/f (600) | < 2.2; where f (500) is the focal length of the fifth lens 500, and f (600) is the focal length of the sixth lens 600.

Further, the Abbe number Abbe of the fifth lens 500 satisfies 30 < Abbe < 40.

In some embodiments of the present invention, fourth lens group G4 includes seventh lens 700 and eighth lens 800; the seventh lens 700 is a negative power lens, the eighth lens 800 is a positive power lens, the edges of the seventh lens 700 and the eighth lens 800 are cemented to form a positive power lens, the seventh lens 700 is a meniscus lens (left convex and right concave), the eighth lens 800 is a double convex lens, the convex surface side of the seventh lens 700 faces the sixth lens 600, the concave surface side of the seventh lens 700 faces the convex surface side of the eighth lens 800, and the radius of curvature of the concave surface side of the seventh lens 700 is the same as the radius of curvature of the convex surface side of the eighth lens 800.

Further, the third lens 300, the sixth lens 600, and the seventh lens 700 satisfy the following condition: 2.6 < | R₃₁/R₆₁+R₇₁| is less than 4; wherein R is₃₁Is a curvature radius of the concave side of the third lens 300, R₆₁Radius of curvature, R, of the sixth lens 600 toward the fifth lens 500 side₇₁Is the radius of curvature of the convex side of the seventh lens 700.

Further, the first lens 100 and the seventh lens 700 satisfy the following condition: r₁₂＞R₇₂(ii) a Wherein R is₁₂Is a curvature radius of the concave side of the first lens 100, R₇₂Is the radius of curvature of the concave side of the seventh lens 700.

Further, Abbe number Abbe of the seventh lens 700 satisfies 30 < Abbe < 40.

Further, a diaphragm is provided between the sixth lens 600 and the seventh lens 700, and the diaphragms are now the light fluxes and correct aberrations.

In some embodiments of the present invention, fourth lens group G4 further includes ninth lens 900 and tenth lens 110; the ninth lens 900 is a negative power lens, the tenth lens 110 is a positive power lens, the ninth lens 900 and the tenth lens 110 are cemented at their edges to form a negative power lens, the ninth lens 900 is a biconcave lens, the tenth lens 110 is a biconvex lens, and the radius of curvature of the ninth lens 900 toward the concave surface side of the tenth lens 110 is the same as the radius of curvature of the tenth lens 110 toward the convex surface side of the ninth lens 900.

Further, the refractive index Nd of the tenth lens 110₁₀Satisfy 1.5 < Nd₁₀Refractive index Nd of < 1.70, seventh lens 700₇₀Satisfy Nd₇₀＞1.8。

In some embodiments of the present invention, the fourth lens group G4 further includes an eleventh lens 120, the eleventh lens 120 is a double convex lens and is a positive power lens, and the first lens 100 and the eleventh lens 120 satisfy the following condition: 1.3 < | f (100)/f (120) | < 2.5; where f (100) is the focal length of the first lens 100, and f (120) is the focal length of the eleventh lens 120.

In some embodiments of the present invention, the fourth lens group G4 further includes a twelfth lens 130, and the twelfth lens 130 is a double convex lens and is a positive power lens.

In some embodiments of the present invention, the light splitting device 140 is a wavelength splitting device, which may be a cubic beam splitter mirror, and is bonded by two 45-degree right-angle prisms, and the bonding surface is a splitting surface. In other embodiments, the beam splitter 140 may be a flat plate beam splitter, but it is required to be placed at 45 degrees. The light splitting device 140 splits the light of two different wave bands of (400-760) nm and (800-1100) nm, and the optical axes of the light of the two wave bands are perpendicular to each other after the light splitting. In this embodiment, it is not limited which specific wavelength band is the horizontal light beam or the vertical light beam, but the filter device 150 and the identification device 160 corresponding to the corresponding wavelength band are required.

Further, Abbe number Abbe of the third lens 300 is smaller than Abbe number Abbe of the spectroscopic device 140.

In some embodiments of the present invention, the filtering device 150 includes a first filter 1501 and a second filter 1502, the first filter 1501 is configured to receive the horizontal light beam, filter the horizontal light beam, and send the filtered horizontal light beam to the identifying device 160; the second filter 1502 is configured to receive the vertical beam, filter the vertical beam, and send the filtered vertical beam to the recognition device 160.

In some embodiments of the present invention, the identification device 160 includes a first chip 1601 and a second chip 1602, the first chip 1601 is configured to receive and identify the filtered horizontal beam, and the second chip 1602 is configured to receive and identify the filtered vertical beam, and perform a fusion process on the horizontal beam image and the vertical beam image through an image fusion algorithm. In this embodiment, the first chip 1601 and the second chip 1602 are both CMOS chips.

In some embodiments of the present invention, a first protection window 1603 for preventing dust is disposed on the first chip 1601, and a second protection window 1604 for preventing dust is disposed on the second chip 1602

In some embodiments of the invention, the optical back focus BF of the lens and the focal length of the lens satisfy BF/f > 4.

Further, the aperture coefficient of the lens is larger than or equal to 1.4.

Further, the angle of view of the lens is 120 °.

The optical transfer function is used for evaluating the imaging quality of the imaging system in a more accurate, visual and common mode, the higher and smoother curve of the optical transfer function shows that the imaging quality of the system is better, and various aberrations (such as spherical aberration, coma aberration, astigmatism, field curvature, axial chromatic aberration, vertical axis chromatic aberration and the like) are well corrected.

FIG. 5 is a graph showing the optical transfer function (MTF) of the lens in the wide-angle state in the visible light band (400-700 nm); the abscissa is resolution in 1p/mm and the ordinate is MTF value. As shown in fig. 5, the visible light curve smoothly falls and concentrates. At 250p/mm, the MTF value can still be ensured to be larger than 0.2. Therefore, the performance of the lens of the system can reach higher pixel resolution under visible light.

FIG. 6 is a graph showing the optical transfer function (MTF) of the lens in the wide-angle state of infrared light (800-; the abscissa is resolution in 1p/mm and the ordinate is MTF value. As shown in fig. 6, the infrared light curve smoothly falls and concentrates. At 250p/mm, the MTF value can still be ensured to be larger than 0.2, and the whole is equivalent to that in a visible light state.

Other constructions and operations of a lens according to an embodiment of the present invention are known to those of ordinary skill in the art and will not be described in detail herein.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an illustrative embodiment," "an example," "a specific example," or "some examples" or the like mean 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 invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. 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 embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the gist of the present invention.

Claims

1. A lens barrel comprising a first lens group (G1), a second lens group (G2), a third lens group (G3), a fourth lens group (G4), a light-splitting device (140), a filter device (150), and a recognition device (160), the first lens group (G1), the second lens group (G2), the third lens group (G3), the fourth lens group (G4), the light-splitting device (140), the filter device (150), and the recognition device (160) being disposed in this order between an object side and an image side; it is characterized in that the preparation method is characterized in that,

the light splitting device (140) is arranged between the fourth lens group (G4) and the filter device (150), an inlet of the light splitting device (140) is connected with an outlet of the fourth lens group (G4), an outlet of the light splitting device (140) is connected with an inlet of the filter device (150), and the light splitting device is used for splitting a light beam at an outlet of the fourth lens group (G4) into a horizontal light beam and a vertical light beam and independently sending the horizontal light beam and the vertical light beam to the filter device (150);

the filtering device (150) is arranged between the light splitting device (140) and the identification device (160) and is used for receiving the horizontal light beam and the vertical light beam, filtering the horizontal light beam and the vertical light beam and independently sending the filtered horizontal light beam and the filtered vertical light beam to the identification device (160);

the identification device (160) is used for receiving and identifying the horizontal light beams and the vertical light beams which are subjected to the filtering processing.

2. A lens barrel according to claim 1, wherein said first lens group (G1) includes a first lens (100) and a second lens (200); wherein the content of the first and second substances,

the first lens (100) and the second lens (200) are both negative-power lenses, the first lens (100) and the second lens (200) are both crescent-shaped, the convex surface side of the first lens (100) faces the object side, and the concave surface side of the first lens (100) faces the convex surface side of the second lens (200).

3. A lens barrel according to claim 2, wherein the first lens (100) satisfies the following condition:

-44＜f(100)＜-25；

1.7＜D₁/R₂＜1.82；

1.7＜Nd₁＜1.8；

wherein f (100) is the focal length of the first lens (100), Nd₁Is the refractive index of the first lens (100), D₁Is the diameter of the concave side of the first lens (100), R₂Is the radius of curvature of the concave side of the first lens (100).

4. A lens barrel according to claim 3, wherein said second lens group (G2) includes a third lens (300) and a fourth lens (400); wherein the content of the first and second substances,

the third lens (300) and the fourth lens (400) are cemented at their edges to form a negative power lens, the third lens (300) is crescent-shaped, the fourth lens (400) is a biconcave lens, the concave side of the third lens (300) faces the concave side of the second lens (200), the convex side of the third lens (300) faces the fourth lens (400), and the radius of curvature of the fourth lens (400) facing the concave side of the third lens (300) is the same as the radius of curvature of the convex side of the third lens (300).

5. A lens barrel according to claim 4, wherein said third lens group (G3) includes a fifth lens (500) and a sixth lens (600); wherein the content of the first and second substances,

the fifth lens (500) and the sixth lens (600) are both double convex lenses and are both positive power lenses, and the fifth lens (500) is disposed between the fourth lens (400) and the sixth lens (600).

6. A lens barrel according to claim 5, wherein the fifth lens (500) and the sixth lens (600) satisfy the following condition:

1.1＜∣f(500)/f(600)∣＜2.2；

wherein f (500) is the focal length of the fifth lens (500), and f (600) is the focal length of the sixth lens (600).

7. A lens barrel according to claim 6, wherein said fourth lens group (G4) includes a seventh lens (700) and an eighth lens (800); wherein the content of the first and second substances,

edges of the seventh lens (700) and the eighth lens (800) are cemented to form a positive power lens, the seventh lens (700) is a meniscus lens, the eighth lens (800) is a double convex lens, a convex surface side of the seventh lens (700) faces the sixth lens (600), a concave surface side of the seventh lens (700) faces a convex surface side of the eighth lens (800), and a radius of curvature of the concave surface side of the seventh lens (700) is the same as that of the convex surface side of the eighth lens (800).

8. A lens barrel according to claim 7, wherein the third lens (300), the sixth lens (600) and the seventh lens (700) satisfy the following condition:

2.6＜∣R₃₁/R₆₁+R₇₁∣＜4；

wherein R is₃₁Is the radius of curvature, R, of the concave side of the third lens (300)₆₁A radius of curvature, R, of the sixth lens (600) on the side facing the fifth lens (500)₇₁Is the radius of curvature of the convex surface side of the seventh lens (700).

9. A lens barrel according to claim 8, wherein the first lens (100) and the seventh lens (700) satisfy the following condition:

R₁₂＞R₇₂；

wherein R is₁₂Is the radius of curvature, R, of the concave side of the first lens (100)₇₂Is the radius of curvature of the concave side of the seventh lens (700).

10. A lens barrel according to claim 9, wherein said fourth lens group (G4) further includes a ninth lens (900) and a tenth lens (110); wherein the content of the first and second substances,

edges of the ninth lens (900) and the tenth lens (110) are cemented to form a negative power lens, the ninth lens (900) is a biconcave lens, the tenth lens (110) is a biconvex lens, and a radius of curvature of the ninth lens (900) toward a concave side of the tenth lens (110) is the same as a radius of curvature of the tenth lens (110) toward a convex side of the ninth lens (900).