TW201741711A - Lens assembly - Google Patents

Abstract

A lens assembly includes a first lens, a second lens, a third lens, a fourth lens and a fifth lens, all of which are arranged in sequence from an object side to an image side along an optical axis. The first lens includes a convex surface facing the image side. The second lens includes a concave surface facing the object side. The third lens is a biconvex lens with positive refractive power. The fourth lens is with negative refractive power and includes a concave surface facing the object side. The fifth lens is with positive refractive power and includes a convex surface facing the image side. The first lens satisfies the following condition: -20 ≤ f1 / f ≤ 2 wherein f1 is an effective focal length of the first lens and f is an effective focal length of the lens assembly.

Description

Imaging lens (13)

The present invention relates to an imaging lens.

The continuous development of digital cameras and hands to high-definition and lightweight, so that the demand for miniaturization and high-resolution imaging lenses has increased. The conventional imaging lens is large in size and cannot meet the needs of today. It requires an imaging lens of another new architecture to meet both miniaturization and high resolution requirements.

In view of this, the main object of the present invention is to provide an imaging lens whose lens length is short, but still has good optical performance, and the lens resolution can also meet the requirements.

The imaging lens of the present invention sequentially includes a first lens, a second lens, a third lens, a fourth lens and a fifth lens from an object side to an image side along an optical axis. The first lens includes a convex surface facing the image side. The second lens includes a concave surface facing the object side. The third lens is a lenticular lens having a positive refractive power. The fourth lens has a negative refractive power and includes a concave surface facing the object side. The fifth lens has a positive refractive power and includes a convex surface toward the image side. The first lens satisfies the following conditions: -20 f ₁ /f 2; wherein f ₁ is the effective focal length of the first lens, and f is the effective focal length of the imaging lens.

The imaging lens satisfies the following conditions: 0.4 BFL/TTL 0.9; wherein, BFL is the distance from the image side of the fifth lens to an imaging surface on the optical axis, and TTL is the distance from the object side of the first lens to the imaging surface on the optical axis.

The third lens satisfies the following conditions: 2 (R ₃₁ -R ₃₂ )/(R ₃₁ +R ₃₂ ) 10; wherein R ₃₁ is a radius of curvature of an object side surface of the third lens, and R ₃₂ is a radius of curvature of an image side surface of the third lens.

The imaging lens of the present invention may further include a cymbal including an incident surface facing the image side of the fifth lens.

The filter may be further disposed between the fifth lens and the crucible.

The imaging lens of the present invention sequentially includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a filter from an object side to an image side along an optical axis. And a trip. The first lens includes a convex surface facing the image side. The second lens includes a concave surface facing the object side. The third lens is a lenticular lens having a positive refractive power. The fourth lens has a negative refractive power and includes a concave surface facing the object side. The fifth lens has a positive refractive power and includes a convex surface toward the image side. The 稜鏡 includes an incident surface facing the image side of the filter. The imaging lens satisfies the following conditions: 2 (R ₃₁ -R ₃₂ )/(R ₃₁ +R ₃₂ ) 10,0.4 BFL/TTL 0.9,-20 f ₁ /f 2; wherein R ₃₁ is the radius of curvature of the side surface of the third lens, R ₃₂ is the radius of curvature of the image side of the third lens, and BFL is the distance from the image side of the fifth lens to the image plane on the optical axis, TTL The distance from the side of the object of the first lens to the optical axis of the imaging surface, f ₁ is the effective focal length of the first lens, and f is the effective focal length of the imaging lens.

Wherein at least one of the first lens and the second lens has a negative refractive power.

The refractive power of the first lens is opposite to the refractive power of the second lens.

Wherein the first lens has a negative refractive power and the second lens has a negative refractive power.

The imaging lens of the present invention may further include an aperture disposed between the object side and the first lens.

The above described objects, features, and advantages of the invention will be apparent from the description and appended claims

1, 2, 3 ‧ ‧ imaging lens

L11, L21, L31‧‧‧ first lens

L12, L22, L32‧‧‧ second lens

L13, L23, L33‧‧‧ third lens

L14, L24, L34‧‧‧ fourth lens

L15, L25, L35‧‧‧ fifth lens

ST1, ST2, ST3‧‧ ‧ aperture

OF1, OF2, OF3‧‧‧ Filters

P1, P2, P3‧‧‧稜鏡

IMA1, IMA2, IMA3‧‧‧ imaging surface

OA1, OA2, OA3‧‧‧ optical axis

S11, S12, S13, S14, S15, S16, S17‧‧

S18, S19, S110, S111, S112, S113‧‧‧

S21, S22, S23, S24, S25, S26, S27‧‧

S28, S29, S210, S211, S212, S213‧‧‧

S31, S32, S33, S34, S35, S36, S37‧‧

S38, S39, S310, S311, S312, S313‧‧

S114, S214, S314‧‧‧ incident surface

S115, S215, S315‧‧‧ reflective surface

S116, S216, S316‧‧‧ exit surface

1 is a schematic view showing a lens configuration and an optical path of a first embodiment of an imaging lens according to the present invention.

Fig. 2A is a longitudinal spherical aberration diagram of the imaging lens of Fig. 1.

Fig. 2B is an astigmatic field curvature diagram of the imaging lens of Fig. 1.

Fig. 2C is a distortion diagram of the imaging lens of Fig. 1.

Fig. 3 is a schematic view showing a lens configuration and an optical path of a second embodiment of the imaging lens according to the present invention.

Fig. 4A is a longitudinal spherical aberration diagram of the imaging lens of Fig. 3.

Fig. 4B is an astigmatic field curvature diagram of the imaging lens of Fig. 3.

Fig. 4C is a distortion diagram of the imaging lens of Fig. 3.

Fig. 5 is a view showing a lens configuration and an optical path of a third embodiment of the imaging lens according to the present invention.

Fig. 6A is a longitudinal spherical aberration diagram of the imaging lens of Fig. 5.

Fig. 6B is an astigmatic field curvature diagram of the imaging lens of Fig. 5.

Fig. 6C is a distortion diagram of the imaging lens of Fig. 5.

Please refer to FIG. 1. FIG. 1 is a schematic view showing a lens configuration and an optical path of a first embodiment of an imaging lens according to the present invention. The imaging lens 1 includes an aperture ST1, a first lens L11, a second lens L12, a third lens L13, a fourth lens L14, and a first step from an object side to an image side along an optical axis OA1. Five lenses L15, one filter OF1 and one 稜鏡 P1. At the time of imaging, the light from the object side is finally imaged on an image plane IMA1. The first lens L11 is a lenticular lens having a positive refractive power made of a plastic material, the object side surface S12 being a convex surface, the image side surface S13 being a convex surface, and the object side surface S12 and the image side surface S13 being aspherical surfaces. The second lens L12 is a biconcave lens having a negative refractive power made of a plastic material, the object side surface S14 is a concave surface, the image side surface S15 is a concave surface, and the object side surface S14 and the image side surface S15 are both aspherical surfaces. The third lens L13 is a lenticular lens having a positive refractive power made of a plastic material, the object side surface S16 being a convex surface, the image side surface S17 being a convex surface, and the object side surface S16 and the image side surface S17 being aspherical surfaces. The fourth lens L14 is a biconcave lens having a negative refractive power made of a plastic material, the object side surface S18 being a concave surface, the image side surface S19 being a concave surface, and the object side surface S18 and the image side surface S19 being aspherical surfaces. The fifth lens L15 is a lenticular lens having a positive refractive power made of a plastic material, the object side surface S110 is a convex surface, the image side surface S111 is a convex surface, and the object side surface S110 and the image side surface S111 are aspherical surfaces. The filter side OF1 has a flat surface S112 and an image side surface S113. The entrance surface S114, the reflection surface S115 and the exit surface S116 of the 稜鏡P1 are all planes, and the light from the object side enters the 稜鏡P1 from the incident surface S114, and then changes the direction of the ray by the reflection surface S115, and exits the rib by the exit surface S116. The mirror P1 is finally imaged on the imaging surface IMA1, and the main function of the 稜鏡P1 is to change the traveling direction of the incident light to achieve the purpose of shortening the total length of the lens.

In addition, in order to maintain good optical performance of the imaging lens of the present invention, the imaging lens 1 of the first embodiment is required to satisfy the following three conditions:

Wherein R1 ₃₁ is the radius of curvature of the object side surface S16 of the third lens L13, R1 ₃₂ is the radius of curvature of the image side surface S17 of the third lens L13, and BFL1 is the image side surface S111 of the fifth lens L15 to the imaging plane IMA1 on the optical axis OA1. The distance TTL1 is the distance from the object side S12 of the first lens L11 to the imaging plane IMA1 on the optical axis OA1, f1 ₁ is the effective focal length of the first lens L11, and f1 is the effective focal length of the imaging lens 1.

With the design of the above lens, aperture ST1 and 稜鏡P1, the imaging lens 1 can effectively shorten the total length of the lens, effective correction aberration, and lens resolution.

Table 1 is a table of related parameters of the lenses of the imaging lens 1 in Fig. 1. Table 1 shows that the effective focal length of the imaging lens 1 of the first embodiment is equal to 4.4132 mm, the aperture value is equal to 2.2, and the total length of the lens is equal to 8.842 mm.

The aspherical surface depression z of each lens in Table 1 is obtained by the following formula: z = ch ² /{1 + [1 - (k + 1) c ² h ² ] ^1/2 } + Ah ⁴ + Bh ⁶ + Ch ⁸ +Dh ¹⁰ +Eh ¹²

Where: c: curvature; h: the vertical distance from any point on the lens surface to the optical axis; k: conic coefficient; A~E: aspheric coefficient.

Table 2 is a table of related parameters of the aspherical surface of each lens in Table 1, where k is a conical coefficient (Conic Constant) and A~E is an aspherical coefficient.

In the imaging lens 1 of the first embodiment, the curvature radius R1 ₃₁ of the object side S16 of the third lens L13 is 2.435 mm, and the curvature radius R1 ₃₂ of the image side surface S17 of the third lens L13 is -1.729 mm, and the fifth lens L15 The distance BFL1=4.503 mm from the side surface S111 to the imaging surface IMA1 on the optical axis OA1, the distance TTL1=8.842 mm of the object side surface S12 of the first lens L11 to the optical axis OA1 of the first lens L11, and the effective focal length of the first lens L11 F1 ₁ =4.31710mm, the effective focal length of imaging lens 1 is f1=4.4132mm, which can be obtained from the above data (R1 ₃₁ -R1 ₃₂ )/(R1 ₃₁ +R1 ₃₂ )=5.898, BFL1/TTL1=0.509, f1 ₁ /f1 =0.978, can meet the requirements of the above conditions (1) to (3).

In addition, the optical performance of the imaging lens 1 of the first embodiment can also be achieved, which can be seen from the 2A to 2C drawings. Fig. 2A is a longitudinal Spherical Aberration diagram of the imaging lens 1 of the first embodiment. Fig. 2B is an astigmatic field curve diagram of the imaging lens 1 of the first embodiment. Fig. 2C is a distortion diagram of the imaging lens 1 of the first embodiment.

As can be seen from FIG. 2A, the imaging lens 1 of the first embodiment produces a longitudinal spherical aberration value of -0.025 mm to 0.030 mm for light having a wavelength of 760.0000 nm, 820.0000 nm, and 86.0000 nm. As can be seen from FIG. 2B, the imaging lens 1 of the first embodiment has an astigmatic field curvature of -0.050 mm to 0.050 mm in the direction of the tangential direction and the sagittal direction for the light having a wavelength of 820.0000 nm. between. As can be seen from FIG. 2C, the imaging lens 1 of the first embodiment has a distortion of between 0% and 1.1% for light having a wavelength of 820.0000 nm. It is apparent that the longitudinal spherical aberration, the astigmatic field curvature, and the distortion of the imaging lens 1 of the first embodiment can be It is effectively corrected to obtain better optical performance.

Please refer to FIG. 3, which is a schematic diagram of a lens configuration and an optical path of a second embodiment of an imaging lens according to the present invention. The imaging lens 2 includes an aperture ST2, a first lens L21, a second lens L22, a third lens L23, a fourth lens L24, and a first step from an object side to an image side along an optical axis OA2. Five lenses L25, one filter OF2 and one P2. At the time of imaging, the light from the object side is finally imaged on an image plane IMA2. The first lens L21 is a meniscus lens having a negative refractive power made of a plastic material, and the object side surface S22 is a concave surface, the image side surface S23 is a convex surface, and the object side surface S22 and the image side surface S23 are both aspherical surfaces. The second lens L22 is a biconcave lens having a negative refractive power made of a plastic material, the object side surface S24 is a concave surface, the image side surface S25 is a concave surface, and the object side surface S24 and the image side surface S25 are both aspherical surfaces. The third lens L23 is a lenticular lens having a positive refractive power made of a plastic material, the object side surface S26 being a convex surface, the image side surface S27 being a convex surface, and the object side surface S26 and the image side surface S27 being aspherical surfaces. The fourth lens L24 is a biconcave lens having a negative refractive power made of a plastic material, the object side surface S28 being a concave surface, the image side surface S29 being a concave surface, and the object side surface S28 and the image side surface S29 being aspherical surfaces. The fifth lens L25 is a lenticular lens having a positive refractive power made of a plastic material, the object side surface S210 is a convex surface, the image side surface S211 is a convex surface, and the object side surface S210 and the image side surface S211 are both aspherical surfaces. The filter side OF2 has a flat surface S212 and an image side surface S213. The entrance surface S214, the reflection surface S215 and the exit surface S216 of the 稜鏡P2 are all planes, and the light from the object side enters the 稜鏡P2 from the incident surface S214, and then reflects the direction of the ray by the reflection surface S215, and exits the rib by the exit surface S216. The mirror P2 is finally imaged on the imaging surface IMA2, and the main function of the 稜鏡P2 is to change the traveling direction of the incident light to achieve the purpose of shortening the total length of the lens.

In addition, in order to maintain good optical performance of the imaging lens of the present invention, the imaging lens 1 of the second embodiment is required to satisfy the following three conditions:

Wherein R2 ₃₁ is the radius of curvature of the object side surface S26 of the third lens L23, R2 ₃₂ is the radius of curvature of the image side surface S27 of the third lens L23, and BFL2 is the image side surface S211 of the fifth lens L25 to the imaging plane IMA2 on the optical axis OA2. The distance TTL2 is the distance from the object side S22 of the first lens L21 to the imaging plane IMA2 on the optical axis OA2, f2 ₁ is the effective focal length of the first lens L21, and f2 is the effective focal length of the imaging lens 2.

With the design of the above lens, aperture ST2 and 稜鏡P2, the imaging lens 2 can effectively shorten the total length of the lens, effective correction aberration, and lens resolution.

Table 3 is a table of related parameters of the lenses of the imaging lens 2 in Fig. 3. Table 3 shows that the effective focal length of the imaging lens 2 of the second embodiment is equal to 4.5294 mm, the aperture value is equal to 2.3, and the total length of the lens is equal to 8.283 mm.

The aspherical surface depression z of each lens in Table 3 is obtained by the following formula: z = ch ² /{1 + [1 - (k + 1) c ² h ² ] ^1/2 } + Ah ⁴ + Bh ⁶ + Ch ⁸ +Dh ¹⁰ +Eh ¹²

Where: c: curvature; h: the vertical distance from any point on the lens surface to the optical axis; k: conic coefficient; A~E: aspheric coefficient.

Table 4 is a table of related parameters of the aspherical surface of each lens in Table 3, where k is a conical coefficient (Conic Constant) and A~E is an aspherical coefficient.

In the imaging lens 2 of the second embodiment, the curvature radius R2 ₃₁ of the object side surface S26 of the third lens L23 is 2.801 mm, and the curvature radius R2 ₃₂ of the image side surface S27 of the third lens L23 is -1.719 mm, and the fifth lens L25 is The distance BFL2=5.711 mm from the side surface S211 to the imaging plane IMA2 on the optical axis OA2, the distance TTL2=8.283 mm of the object side surface S22 of the first lens L21 to the imaging plane IMA2 on the optical axis OA2, and the effective focal length of the first lens L21 F2 ₁ = -30.69820mm, the effective focal length of imaging lens 2 is f2=4.5294mm, which can be obtained from the above data (R2 ₃₁ -R2 ₃₂ )/(R2 ₃₁ +R2 ₃₂ )=4.177, BFL2/TTL2=0.689, f2 ₁ / F2=-6.778 can meet the requirements of the above conditions (4) to (6).

In addition, the optical performance of the imaging lens 2 of the second embodiment can also be achieved, which can be seen from Figs. 4A to 4C. Fig. 4A is a longitudinal Spherical Aberration diagram of the imaging lens 2 of the second embodiment. Fig. 4B is an astigmatic field curve diagram of the imaging lens 2 of the second embodiment. Fig. 4C is a distortion diagram of the imaging lens 2 of the second embodiment.

As can be seen from FIG. 4A, the longitudinal lens difference produced by the imaging lens 2 of the second embodiment for light having a wavelength of 760.0000 nm, 820.0000 nm, and 86.0000 nm is between -0.025 mm and 0.025 mm. As can be seen from FIG. 4B, the imaging lens 2 of the second embodiment has an astigmatic field curvature of -0.15 mm to 0.07 mm in the direction of the tangential direction and the sagittal direction for the light having a wavelength of 820.0000 nm. between. As can be seen from Fig. 4C, the imaging lens 2 of the second embodiment produces a distortion of -2.3% to 0% for light having a wavelength of 820.0000 nm. It is obvious that the longitudinal spherical aberration, the astigmatic field curvature, and the distortion of the imaging lens 2 of the second embodiment can be Effective correction to achieve better optical performance.

Please refer to FIG. 5, which is a schematic diagram of a lens configuration and an optical path of a third embodiment of an imaging lens according to the present invention. The imaging lens 3 sequentially includes an aperture ST3, a first lens L31, a second lens L32, a third lens L33, a fourth lens L34, and a first image from an object side to an image side along an optical axis OA3. Five lenses L35, one filter OF3 and one P3. At the time of imaging, the light from the object side is finally imaged on an image plane IMA3. The first lens L31 has a negative refractive power and is made of a plastic material. The object side surface S32 is a concave surface, the image side surface S33 is a convex surface, and the object side surface S32 and the image side surface S33 are aspherical surfaces. The second lens L32 is a meniscus lens having a positive refractive power made of a plastic material, and the object side surface S34 is a concave surface, the image side surface S35 is a convex surface, and the object side surface S34 and the image side surface S35 are both aspherical surfaces. The third lens L33 is a lenticular lens having a positive refractive power made of a plastic material, the object side surface S36 being a convex surface, the image side surface S37 being a convex surface, and the object side surface S36 and the image side surface S37 being aspherical surfaces. The fourth lens L34 is a meniscus lens having a negative refractive power made of a plastic material, the object side surface S38 being a concave surface, the image side surface S39 being a convex surface, and the object side surface S38 and the image side surface S39 being aspherical surfaces. The fifth lens L35 is a meniscus lens having a positive refractive power made of a plastic material, and the object side surface S310 is a concave surface, the image side surface S311 is a convex surface, and the object side surface S310 and the image side surface S311 are both aspherical surfaces. The filter OF3 has a flat surface S312 and an image side surface S313. The entrance surface S314, the reflection surface S315 and the exit surface S316 of the 稜鏡P3 are all planes, and the light from the object side enters the 稜鏡P3 from the incident surface S314, and then reflects the direction of the ray by the reflection surface S315, and exits the rib by the exit surface S316. The mirror P3 is finally imaged on the imaging surface IMA3, and the main function of the 稜鏡P3 is to change the traveling direction of the incident light to achieve the purpose of shortening the total length of the lens.

In addition, in order to maintain good optical performance of the imaging lens of the present invention, the imaging lens 3 of the third embodiment is required to satisfy the following three conditions:

Wherein R3 ₃₁ is the radius of curvature of the object side surface S36 of the third lens L33, R3 ₃₂ is the radius of curvature of the image side surface S37 of the third lens L33, and BFL3 is the image side surface S311 of the fifth lens L35 to the imaging plane IMA3 on the optical axis OA3. The distance TTL3 is the distance from the object side S32 of the first lens L31 to the imaging plane IMA3 on the optical axis OA3, f3 ₁ is the effective focal length of the first lens L31, and f3 is the effective focal length of the imaging lens 3.

With the design of the above lens, aperture ST3 and 稜鏡P3, the imaging lens 3 can effectively shorten the total length of the lens, effective correction aberration, and lens resolution.

Table 5 is a table of related parameters of the lenses of the imaging lens 3 in Fig. 5. Table 5 shows that the effective focal length of the imaging lens 3 of the third embodiment is equal to 4.5294 mm, the aperture value is equal to 2.4, and the total length of the lens is equal to 8.017 mm.

The aspherical surface depression z of each lens in Table 5 is obtained by the following formula: z = ch ² /{1 + [1 - (k + 1) c ² h ² ] ^1/2 } + Ah ⁴ + Bh ⁶ + Ch ⁸ +Dh ¹⁰ +Eh ¹²

Where: c: curvature; h: the vertical distance from any point on the lens surface to the optical axis; k: conic coefficient; A~E: aspheric coefficient.

Table 6 is the relevant parameter table of the aspherical surface of each lens in Table 5, where k is the conic coefficient (Conic Constant) and A~E is the aspherical coefficient.

In the imaging lens 3 of the third embodiment, the curvature radius R3 ₃₁ of the object side S36 of the third lens L33 is 4.622 mm, and the curvature radius R3 ₃₂ of the image side surface S37 of the third lens L33 is -2.220 mm, and the fifth lens L35 The distance BFL3=5.938 mm from the side surface S311 to the imaging plane IMA3 on the optical axis OA3, the distance TTL3=8.017 mm of the object side surface S32 of the first lens L31 to the optical axis OA3 of the first lens L31, and the effective focal length of the first lens L31 F3 ₁ = -63.87000mm, the effective focal length of the imaging lens 3 is f3 = 4.5294mm, which can be obtained from the above data (R3 _{31 -} R3 ₃₂ ) / (R3 ₃₁ + R3 ₃₂ ) = 2.820, BFL3 / TTL3 = 0.741, f3 ₁ / F3=-14.101, can meet the requirements of the above conditions (7) to (9).

Further, the optical performance of the imaging lens 3 of the third embodiment can also be achieved, which can be seen from Figs. 6A to 6C. Fig. 6A is a longitudinal Spherical Aberration diagram of the imaging lens 3 of the third embodiment. Fig. 6B is an astigmatism field curve diagram of the imaging lens 3 of the third embodiment. Fig. 6C is a distortion diagram of the imaging lens 3 of the third embodiment.

As can be seen from Fig. 6A, the longitudinal spherical aberration value of the imaging lens 3 of the third embodiment for light having wavelengths of 760.0000 nm, 820.0000 nm, and 860.0000 nm is between -0.025 mm and 0.025 mm. As can be seen from FIG. 6B, the imaging lens 3 of the third embodiment has an astigmatic field curvature of -0.15 mm to 0.10 mm in the direction of the tangential direction and the sagittal direction for the light having a wavelength of 820.0000 nm. between. As can be seen from Fig. 6C, the distortion of the imaging lens 3 of the third embodiment for light having a wavelength of 820.0000 nm is between -2.3% and 0%. It is obvious that the longitudinal spherical aberration, the astigmatic field curvature, and the distortion of the imaging lens 3 of the third embodiment can be Effective correction to achieve better optical performance.

1‧‧‧ imaging lens

L11‧‧‧ first lens

L12‧‧‧ second lens

L13‧‧‧ third lens

L14‧‧‧4th lens

L15‧‧‧ fifth lens

ST1‧‧‧ aperture

OF1‧‧‧Filter

P1‧‧‧稜鏡

OA1‧‧‧ optical axis

IMA1‧‧‧ imaging surface

S11, S12, S13, S14, S15‧‧

S16, S17, S18, S19, S110‧‧‧

S111, S112, S113‧‧‧

S114‧‧‧Incoming surface

S115‧‧‧reflecting surface

S116‧‧‧ outgoing surface

Claims (10)

An imaging lens includes, along an optical axis, from an object side to an image side, a first lens, the first lens includes a convex surface, the convex surface faces the image side, and a second lens, the second lens a concave surface facing the object side; a third lens having a positive refractive power; the fourth lens having a negative refractive power and including a concave surface facing the object side And a fifth lens having a positive refractive power and including a convex surface facing the image side; wherein the first lens satisfies the following condition: -20 f ₁ /f 2 wherein f _{1 is} the effective focal length of the first lens, and f is the effective focal length of the imaging lens. The imaging lens of claim 1, wherein the imaging lens satisfies the following condition: 0.4 BFL/TTL 0.9, wherein the BFL is the distance from the image side of the fifth lens to an imaging surface on the optical axis, and TTL is the distance from the object side of the first lens to the imaging surface on the optical axis. The imaging lens of claim 1, wherein the third lens satisfies the following conditions: 2 (R ₃₁ -R ₃₂ )/(R ₃₁ +R ₃₂ ) 10 wherein R _{31 is a} radius of curvature of an object side surface of the third lens, and R _{32 is a} radius of curvature of an image side surface of the third lens. The imaging lens of claim 1, further comprising a cymbal including an incident surface facing the image side of the fifth lens. The imaging lens of claim 4, further comprising a filter disposed between the fifth lens and the crucible. An imaging lens includes, along an optical axis, from an object side to an image side, a first lens, the first lens includes a convex surface, the convex surface faces the image side, and a second lens, the second lens a concave surface facing the object side; a third lens having a positive refractive power; the fourth lens having a negative refractive power and including a concave surface facing the object side a fifth lens having a positive refractive power and including a convex surface facing the image side; a filter; and a crucible including an incident surface facing the image side of the optical filter Where the imaging lens satisfies the following conditions: 2 (R ₃₁ -R ₃₂ )/(R ₃₁ +R ₃₂ ) 100.4 BFL/TTL 0.9-20 f ₁ /f 2, wherein R _{31 is a} radius of curvature of an object side surface of the third lens, R _{32 is a} radius of curvature of an image side surface of the third lens, and BFL is an image side surface of the fifth lens to an imaging surface on the optical axis The distance, TTL is the distance from the side of the object of the first lens to the optical axis of the imaging surface, f _{1 is} the effective focal length of the first lens, and f is the effective focal length of the imaging lens. The imaging lens of claim 1 or 6, wherein at least one of the first lens and the second lens has a negative refractive power. The imaging lens of claim 7, wherein the refractive power of the first lens is opposite to the refractive power of the second lens. The imaging lens of claim 7, wherein the first lens has a negative refractive power and the second lens has a negative refractive power. The imaging lens of claim 1 or 6, further comprising an aperture disposed between the object side and the first lens.