Imaging lens

Abstract

An imaging lens comprises a first lens group, a second lens group and a third lens group. The first lens group has positive refractive power. The second lens group has negative refractive power and includes at least two lenses. The third lens group has positive refractive power and includes a lens 3-1, a lens 3-2, a lens 3-3, and a lens 3-4. The first lens group, the second lens group and the third lens group are sequentially arranged from the object side to the image side along the optical axis. The lens 3-1, the lens 3-2, the lens 3-3 and the lens 3-4 are sequentially arranged from the object side to the image side along the optical axis. The 3-1 lens is a biconvex lens with positive refractive power, and comprises a convex surface facing the object side and another convex surface facing the image side. The 3-3 lens comprises a concave surface facing the image side. The two lenses closest to the image side in the second lens group or the third lens group are meniscus lenses.

Description

Technical Field

[0001] The invention relates to an imaging lens. Background Art

[0002] Today's high-resolution imaging lenses often have a long total lens length and a large size, which can no longer meet the application requirements of today's unmanned aircraft. Therefore, another new imaging lens architecture is needed to meet the needs of miniaturization and high resolution at the same time. Summary of the invention

[0003] In view of this, the main purpose of the present invention is to provide an imaging lens with high resolution but still good optical performance.

[0004] The invention provides an imaging lens comprising a first lens group, a second lens group and a third lens group.

[0005] The first lens group has positive refractive power. The second lens group has negative refractive power and includes at least two lenses.

[0006] The third lens group has positive refractive power and includes a 3-1 lens, a 3-2 lens, a 3-3 lens, and a 3-4 lens. The first lens group, the second lens group, and the third lens group are arranged in sequence from the object side to the image side along the optical axis. The 3-1 lens, the 3-2 lens, the 3-3 lens, and the 3-4 lens are arranged in sequence from the object side to the image side along the optical axis. The 3-1 lens is a biconvex lens with positive refractive power and includes a convex surface facing the object side and another convex surface facing the image side. The 3-3 lens includes a concave surface facing the image side. The two lenses closest to the image side in the second lens group or the third lens group are meniscus lenses.

[0007] The refractive powers of adjacent lenses in the second lens group or the third lens group are opposite.

[0008] The present invention provides another imaging lens including a first lens group, a second lens group and a third lens group. The first lens group has positive refractive power. The second lens group has negative refractive power. The third lens group has positive refractive power. The first lens group, the second lens group and the third lens group are arranged in sequence from the object side to the image side along the optical axis. The lens closest to the object side in the third lens group is a double convex lens with positive refractive power, and includes a convex surface facing the object side and another convex surface facing the image side. The second lens group or the third lens group includes a plurality of lenses, and the refractive powers of adjacent lenses in the lenses are opposite.

[0009] The third lens group includes a 3-1 lens, a 3-2 lens, a 3-3 lens and a 3-4 lens arranged in sequence along the optical axis from the object side to the image side; the 3-3 lens includes a concave surface facing the image side; in the second lens group or the third lens group, the two lenses closest to the image side are meniscus lenses.

[0010] The second lens group includes a 2-1 lens, a 2-2 lens and a 2-3 lens; one of the 2-1 lens, the 2-2 lens and the 2-3 lens is a biconcave lens and the other two are meniscus lenses; the 2-1 lens and the 2-3 lens have the same refractive power, and the 2-1 lens and the 2-2 lens have opposite refractive powers; and the refractive power of the lens closest to the object side in the second lens group is opposite to the refractive power of the lens closest to the object side in the third lens group.

[0011] The object side surface shape of the lens closest to the object side in the second lens group is the same as its image side surface shape; the image side surface shapes of adjacent lenses in the first lens group or the second lens group are the same; and the second lens group and the third lens group include a total of five meniscus lenses.

[0012] The first lens group includes a 1-1 lens, a 1-2 lens and a 1-3 lens arranged in sequence along the optical axis from the object side to the image side; the second lens group includes a 2-1 lens, a 2-2 lens and a 2-3 lens arranged in sequence along the optical axis from the object side to the image side; the 1-2 lens includes a concave surface facing the image side; the 2-1 lens includes a concave surface facing the object side; the 2-2 lens is a meniscus lens with positive refractive power, and includes a convex surface facing the object side and a concave surface facing the image side; and the 2-3 lens is a meniscus lens with negative refractive power, and includes a convex surface facing the object side and a concave surface facing the image side.

[0013] Among them, the 1-1 lens is a meniscus lens with negative refractive power, and includes a convex surface facing the object side and a concave surface facing the image side; the 1-2 lens is a meniscus lens with positive refractive power, and further includes a convex surface facing the object side; the 1-3 lens is a meniscus lens with positive refractive power, and includes a convex surface facing the object side and a concave surface facing the image side; the 2-1 lens is a double concave lens with negative refractive power, and further includes another concave surface facing the image side; the 3-2 lens is a meniscus lens with negative refractive power, and includes a convex surface facing the object side and a concave surface facing the image side; the 3-3 lens is a meniscus lens with positive refractive power, and further includes a convex surface facing the object side; and the 3-4 lens is a meniscus lens with negative refractive power, and includes a concave surface facing the object side and a convex surface facing the image side.

[0014] It may further include an aperture disposed between the second lens group and the third lens group, and the second lens group can move along the optical axis to perform focusing.

[0015] The imaging lens of the present invention can meet at least one of the following conditions: -0.76 < fG2 / f < -0.6; 0.8 < fG3 / f < 1.8; 3.6 < β2 < 6; 1.6 < fG3 / fG1 < 2.2; 0.75 < TTL / fG3 < 1.05; 4.5 < TTL / BFL < 8; 0.7 < f / TTL < 0.9; 3.6 < f / BFL < 5.5; 0.4 < T11ST / TSTIMA < 0.7; 0.53 < fG1 / f < 0.82; where f is the effective focal length of the imaging lens, fG1 is the effective focal length of the first lens group, fG2 is the effective focal length of the second lens group, fG3 is the effective focal length of the third lens group, TTL is the distance on the optical axis from the object side surface of the lens closest to the object side to the imaging surface, BFL is the distance on the optical axis from the image side surface of the lens closest to the image side to the imaging surface, T11ST is the distance on the optical axis from the object side surface of the lens closest to the object side to the aperture, TSTIMA is the distance on the optical axis from the aperture to the imaging surface, and β2 is the lateral magnification of the second lens group when an object is located at infinity.

[0016] Implementing the imaging lens of the present invention has the following beneficial effects: its total lens length is shorter and the resolution is higher, but it still has good optical performance. Description of the Drawings

[0017] Figure 1 It is a lens configuration and optical path schematic diagram according to the fifth embodiment of the imaging lens of the present invention.

[0018] Figure 2 It is a field curvature diagram according to the fifth embodiment of the imaging lens of the present invention.

[0019] Figure 3 It is a distortion diagram according to the fifth embodiment of the imaging lens of the present invention.

[0020] Figure 4 It is a modulation transfer function diagram according to the fifth embodiment of the imaging lens of the present invention.

[0021] Figure 5 It is a Y-field modulation transfer function diagram according to the fifth embodiment of the imaging lens of the present invention.

[0022] Figure 6 It is a through focus modulation transfer function diagram according to the fifth embodiment of the imaging lens of the present invention.

[0023] Figure 7Schematic diagram of lens configuration and optical path of a sixth embodiment of an imaging lens according to the present invention.

[0024] Figure 8 4 is a field curvature diagram according to the sixth embodiment of the imaging lens of the present invention.

[0025] Fig. 9 2 is a distortion diagram of the sixth embodiment of the imaging lens according to the present invention.

[0026] Fig.10 is a modulation transfer function diagram according to a sixth embodiment of the imaging lens of the present invention.

[0027] Fig.11 FIG. 4 is a diagram of a Y field of view modulation transfer function according to a sixth embodiment of the imaging lens of the present invention.

[0028] Fig.12 is a diagram of a defocus modulation transfer function according to a sixth embodiment of the imaging lens of the present invention. DETAILED DESCRIPTION

[0029] The present invention provides an imaging lens, comprising: a first lens group, the first lens group having positive refractive power; a second lens group, the second lens group having negative refractive power; and a third lens group, the third lens group having positive refractive power; wherein the first lens group, the second lens group and the third lens group are arranged in sequence from the object side to the image side along the optical axis.

[0030] The imaging lens of the first embodiment of the present invention is according to the first paragraph of [Specific Implementation Method], wherein the first lens group includes a lens, the lens has positive refractive power, and can be a biconvex lens, a plano-convex lens, or a meniscus-shaped concave-convex or convex-concave lens; the second lens group includes two lenses, the lenses have positive or negative refractive power, but not all of them are positive refractive power, and the lenses can be biconvex lenses, biconcave lenses, plano-convex lenses, plano-concave lenses, or meniscus-shaped concave-convex or convex-concave lenses, but not all of them are biconvex lenses or plano-convex lenses; the third lens group includes a 3-1 lens, a 3-2 lens, a 3-3 lens, and a 3-4 lens. -4 lens; the 3-1 lens is the lens closest to the object side in the third lens group and is a biconvex lens with positive refractive power; the 3-2 lens, the 3-3 lens and the 3-4 lens can have positive or negative refractive power; the 3-2 lens and the 3-4 lens can be biconvex lenses, biconcave lenses, plano-convex lenses, plano-concave lenses or meniscus-shaped concave-convex or convex-concave lenses, and the 3-3 lens includes a concave surface facing the image side and the other surface can be a convex surface, a plane surface or a concave surface facing the object side; the two lenses closest to the image side in the second lens group and / or the third lens group are meniscus lenses, and this design helps to reduce field curvature. When imaging, the light from the object side is finally imaged on the imaging surface. The first embodiment of the present invention can achieve basic operation through the above design.

[0031] The imaging lens of the second embodiment of the present invention is according to the first paragraph of [Specific Implementation Method], wherein the first lens group includes a lens, which has positive refractive power and can be a biconvex lens, a plano-convex lens, or a meniscus-shaped concave-convex or convex-concave lens; the second lens group includes two lenses, which have positive or negative refractive power, but not all of them are positive refractive power, and the lenses can be biconvex lenses, biconcave lenses, plano-convex lenses, plano-concave lenses, or meniscus-shaped concave-convex or convex-concave lenses, but not all of them are biconvex lenses or plano-convex lenses; and the third lens group includes two lenses, which have positive or negative refractive power, but not all of them are negative refractive power, and The lenses may be biconvex lenses, biconcave lenses, plano-convex lenses, plano-concave lenses, or meniscus-shaped concave-convex or convex-concave lenses, but not all of them may be biconcave lenses or plano-concave lenses; wherein the lens of the third lens group closest to the object side is a biconvex lens with positive refractive power, and the refractive powers of the adjacent lenses in the lenses of the second lens group and / or the third lens group are opposite, that is, the refractive powers of the lenses of the second lens group are one positive and one negative, or the refractive powers of the lenses of the third lens group are one positive and one negative, or the refractive powers of the lenses of the second lens group and the third lens group are negative-positive-negative-positive or positive-negative-positive-negative in sequence from the object side to the image side. When imaging, the light from the object side is finally imaged on the imaging surface. The second embodiment of the present invention can achieve basic operation through the above design.

[0032] The imaging lens of the third embodiment of the present invention is according to the first paragraph of [Specific Implementation Method], wherein the first lens group includes a 1-1 lens, a 1-2 lens and a 1-3 lens arranged in sequence from the object side to the image side along the optical axis; the 1-1 lens, the 1-2 lens and the 1-3 lens are meniscus lenses (concave-convex or convex-concave lenses) and have the same surface shape facing the object side, and the refractive power can be positive or negative, and the refractive power of the 1-2 lens and the 1-3 lens is the same, and the refractive power of the 1-1 lens and the 1-2 lens is opposite. The second lens group includes a 2-1 lens, a 2-2 lens and a 2-3 lens arranged in sequence from the object side to the image side along the optical axis. Among the 2-1 lens, the 2-2 lens and the 2-3 lens, one is a biconcave lens and the other two are meniscus lenses (concave-convex or convex-concave lenses). The two meniscus lenses have the same surface shape facing the object side, and the refractive power can be positive or negative. The refractive power of the 2-1 lens and the 2-3 lens is the same, and the refractive power of the 2-1 lens and the 2-2 lens is opposite. The third lens group includes 3-1 lens, 3-2 lens, 3-3 lens and 3-4 lens arranged in sequence from the object side to the image side along the optical axis. The 3-1 lens is a double convex lens with positive refractive power. The 3-2 lens, 3-3 lens and 3-4 lens are meniscus lenses (concave-convex or convex-concave lenses). The refractive power can be positive or negative. The refractive power of the 3-2 lens and the 3-4 lens is the same, and the refractive power of the 3-2 lens and the 3-3 lens is opposite. The second lens group and the third lens group have a total of five meniscus lenses. The image side surface shapes of the 1-1 lens, the 1-2 lens and the 1-3 lens are the same, or the image side surface shapes of the 2-1 lens, the 2-2 lens and the 2-3 lens are the same. When imaging, the light from the object side is finally imaged on the imaging plane. The third embodiment of the present invention can achieve basic operation through the above design.

[0033] The imaging lens of the fourth embodiment of the present invention is according to the first paragraph of [Specific Implementation Method], wherein lens 1-1 is a meniscus lens with negative refractive power, whose object side surface is convex, and whose image side surface is concave. Lens 1-2 is a meniscus lens with positive refractive power, whose object side surface is convex, and whose image side surface is concave. Lens 1-3 is a meniscus lens with positive refractive power, whose object side surface is convex, and whose image side surface is concave. Lens 2-1 is a biconcave lens with negative refractive power, whose object side surface and image side surface are concave. Lens 2-2 is a meniscus lens with positive refractive power, whose object side surface is convex, and whose image side surface is concave. Lens 2-3 is a meniscus lens with negative refractive power, whose object side surface is convex, and whose image side surface is concave. Lens 3-1 is a biconvex lens with positive refractive power, whose object side surface is convex, and whose image side surface is convex. Lens 3-2 is a meniscus lens with negative refractive power, whose object side surface is convex, and whose image side surface is concave. The 3-3 lens is a meniscus lens with positive refractive power, and its object side is convex, and its image side is concave. The 3-4 lens is a meniscus lens with negative refractive power, and its object side is concave, and its image side is convex. When imaging, the light from the object side is finally imaged on the imaging surface. The fourth embodiment of the present invention can achieve basic operation through the above design.

[0034] In addition, in another embodiment of the above-described imaging lens, chromatic aberration can be effectively reduced and resolution can be improved by further satisfying the condition 85 < VdG1P < 90, where VdG1P is the average Abbe number of the positive refractive power lenses in the first lens group. Meeting this condition can achieve basic operation. In yet another embodiment, the resolution can be effectively improved by further satisfying the condition -0.76 < fG2 / f < -0.6, where fG2 is the effective focal length of the second lens group and f is the effective focal length of the imaging lens. Meeting this condition can achieve basic operation. In yet another embodiment, the sensitivity can be effectively reduced by further satisfying the condition 0.8 < fG3 / f < 1.8, where fG3 is the effective focal length of the third lens group and f is the effective focal length of the imaging lens. Meeting this condition can achieve basic operation. In yet another embodiment, the focusing ability can be effectively improved by further satisfying the condition 1.6 < fG3 / fG1 < 2.2, where fG3 is the effective focal length of the third lens group and fG1 is the effective focal length of the first lens group. Meeting this condition can achieve basic operation. In yet another embodiment, the total lens length can be effectively shortened by further satisfying the condition 0.75 < TTL / fG3 < 1.05, where fG3 is the effective focal length of the third lens group and TTL is the distance on the optical axis from the object surface of the lens closest to the object side of the imaging lens to the imaging surface. Meeting this condition can achieve basic operation. In yet another embodiment, the back focal length can be effectively increased and the production yield of the imaging lens can be improved by further satisfying the condition 4.5 < TTL / BFL < 8, where TTL is the distance on the optical axis from the object surface of the lens closest to the object side of the imaging lens to the imaging surface and BFL is the distance on the optical axis from the image surface of the lens closest to the image side of the imaging lens to the imaging surface. Meeting this condition can achieve basic operation. In yet another embodiment, the total lens length can be effectively shortened by further satisfying the condition 0.7 < f / TTL < 0.9, where TTL is the distance on the optical axis from the object surface of the lens closest to the object side of the imaging lens to the imaging surface and f is the effective focal length of the imaging lens. Meeting this condition can achieve basic operation. In yet another embodiment, the back focal length can be effectively increased and the production yield of the imaging lens can be improved by further satisfying the condition 3.6 < f / BFL < 5.5, where BFL is the distance on the optical axis from the image surface of the lens closest to the image side of the imaging lens to the imaging surface and f is the effective focal length of the imaging lens. Meeting this condition can achieve basic operation. In yet another embodiment, the production yield of the imaging lens can be effectively improved by further satisfying the condition 0.4 < T11ST / TSTIMA < 0.7, where T11ST is the distance on the optical axis from the object surface of the lens closest to the object side of the imaging lens to the aperture and TSTIMA is the distance on the optical axis from the aperture in the imaging lens to the imaging surface. Meeting this condition can achieve basic operation.In yet another embodiment, the resolution can be effectively improved by satisfying the condition 0.53 < fG1 / f < 0.82, where fG1 is the effective focal length of the first lens group and f is the effective focal length of the imaging lens. Meeting this condition enables basic operation.

[0035] Please refer to Table 1, Table 2, Table 4, and Table 5 below. Table 1 and Table 4 are respectively the relevant parameter tables of each lens of the fifth to sixth embodiments of the imaging lens according to the present invention, and Table 2 and Table 5 are respectively the relevant parameter tables of the aspherical surfaces of the aspherical lenses in Table 1 and Table 4.

[0036] Figs. 1 and 7 are respectively the lens configurations and optical path diagrams of the fifth and sixth embodiments of the imaging lens according to the present invention. Among them, lenses 3L1-1 and 4L1-1 are meniscus lenses with negative refractive power, their object sides S31 and S41 are convex surfaces, and their image sides S32 and S42 are concave surfaces. The object sides S31 and S41 and the image sides S32 and S42 are all spherical surfaces. Lenses 3L1-2 and 4L1-2 are meniscus lenses with positive refractive power, their object sides S33 and S43 are convex surfaces, and their image sides S34 and S44 are concave surfaces. The object sides S33 and S43 and the image sides S34 and S44 are all spherical surfaces. Lenses 3L1-3 and 4L1-3 are meniscus lenses with positive refractive power, their object sides S35 and S45 are convex surfaces, and their image sides S36 and S46 are concave surfaces. The object sides S35 and S45 and the image sides S36 and S46 are all aspherical surfaces.

[0037] Lenses 3L2-1 and 4L2-1 are biconcave lenses with negative refractive power, their object sides S37 and S47 are concave surfaces, and their image sides S38 and S48 are concave surfaces. The object sides S37 and S47 and the image sides S38 and S48 are all spherical surfaces. Lenses 3L2-2 and 4L2-2 are meniscus lenses with positive refractive power, their object sides S39 and S49 are convex surfaces, and their image sides S310 and S410 are concave surfaces. The object sides S39 and S49 and the image sides S310 and S410 are all spherical surfaces. Lenses 3L2-3 and 4L2-3 are meniscus lenses with negative refractive power, their object sides S311 and S411 are convex surfaces, and their image sides S312 and S412 are concave surfaces. The object sides S311 and S411 and the image sides S312 and S412 are all spherical surfaces.

[0038] 3-1 lenses 3L3-1 and 4L3-1 are double convex lenses with positive refractive power, whose object side surfaces S314 and S414 are convex, and whose image side surfaces S315 and S415 are convex, and whose object side surfaces S314 and S414 and image side surfaces S315 and S415 are all spherical surfaces. 3-2 lenses 3L3-2 and 4L3-2 are meniscus lenses with negative refractive power, whose object side surfaces S316 and S416 are convex, and whose image side surfaces S317 and S417 are concave, and whose object side surfaces S316 and S416 and image side surfaces S317 and S417 are all spherical surfaces. 3-3 lenses 3L3-3 and 4L3-3 are meniscus lenses with positive refractive power, whose object side surfaces S318 and S418 are convex, and image side surfaces S319 and S419 are concave, and both object side surfaces S318 and S418 and image side surfaces S319 and S419 are spherical surfaces. 3-4 lenses 3L3-4 and 4L3-4 are meniscus lenses with negative refractive power, whose object side surfaces S320 and S420 are concave, and image side surfaces S321 and S421 are convex, and both object side surfaces S320 and S420 and image side surfaces S321 and S421 are spherical surfaces.

[0039] In addition, the imaging lenses 3 and 4 can optimize the performance of the imaging lenses by satisfying at least one or all of the following conditions (1) to (11). The optimized performance is as described in the sixth paragraph of [Detailed Description], and thus will not be described in detail here:

[0040] 85 < VdG1P < 90; (1)

[0041] -0.76 < fG2 / f < -0.6; (2)

[0042] 0.8 < fG3 / f < 1.8; (3)

[0043] 3.6 < β2 < 6; (4)

[0044] 1.6 < fG3 / fG1 < 2.2; (5)

[0045] 0.75 < TTL / fG3 < 1.05; (6)

[0046] 4.5 < TTL / BFL < 8; (7)

[0047] 0.7 < f / TTL < 0.9; (8)

[0048] 3.6 < f / BFL < 5.5; (9)

[0049] 0.4 < T11ST / TSTIMA < 0.7; (10)

[0050] 0.53 < fG1 / f < 0.82; (11)

[0051] Wherein, VdG1P is the average Abbe coefficient of the lenses with positive refractive power in the first lens group LG31 and LG41 in the fifth to sixth embodiments, f is the effective focal length of the imaging lenses 3 and 4 in the fifth to sixth embodiments, fG1 is the effective focal length of the first lens group LG31 and LG41 in the fifth to sixth embodiments, fG2 is the effective focal length of the second lens group LG32 and LG42 in the fifth to sixth embodiments, fG3 is the effective focal length of the third lens group LG33 and LG43 in the fifth to sixth embodiments, and TTL is the distance from the object side surface S31 and S41 of the lens 3L1-1 and 4L1-1 closest to the object side to the imaging surface IMA3 and IMA4 on the optical axes OA3 and OA4 in the fifth to sixth embodiments. 4, BFL is the distance between the image side surface S321, S421 of the lens 3L3-4, 4L3-4 closest to the image side and the imaging surface IMA3, IMA4 on the optical axis OA3, OA4 in the fifth to sixth embodiments, T11ST is the distance between the object side surface S31, S41 of the lens 3L1-1, 4L1-1 closest to the object side and the aperture ST3, ST4 on the optical axis OA3, OA4 in the fifth to sixth embodiments, TSTIMA is the distance between the aperture ST3, ST4 and the imaging surface IMA3, IMA4 on the optical axis OA3, OA4 in the fifth to sixth embodiments, β2 is the lateral magnification of the second lens group LG32, LG42 when the object is at infinity in the fifth to sixth embodiments. This allows the imaging lenses 3, 4 to effectively shorten the total length of the lens, effectively improve the resolution, and effectively correct aberrations.

[0052] The fifth embodiment of the imaging lens of the present invention will now be described in detail. Figure 1The imaging lens 3 includes a first lens group LG31, a second lens group LG32, an aperture ST3, a third lens group LG33, a filter OF3 and a protective glass CG3 arranged in sequence from the object side to the image side along the optical axis OA3. The first lens group LG31 has positive refractive power, and the first lens group LG31 includes a 1-1 lens 3L1-1, a 1-2 lens 3L1-2 and a 1-3 lens 3L1-3 arranged in sequence from the object side to the image side along the optical axis OA3. The second lens group LG32 has negative refractive power, and the second lens group LG32 includes a 2-1 lens 3L2-1, a 2-2 lens 3L2-2 and a 2-3 lens 3L2-3 arranged in sequence from the object side to the image side along the optical axis OA3. The third lens group LG33 has positive refractive power, and the third lens group LG33 includes a 3-1 lens 3L3-1, a 3-2 lens 3L3-2, a 3-3 lens 3L3-3 and a 3-4 lens 3L3-4 arranged in sequence from the object side to the image side along the optical axis OA3. During imaging, the light from the object side is finally imaged on the imaging surface IMA3. According to the seventh to tenth paragraphs of [Specific Implementation], the object side S322 and the image side S323 of the filter OF3 are both planes; the object side S324 and the image side S325 of the protective glass CG3 are both planes; by using the above-mentioned lenses and a design that satisfies at least one of the conditions (1) to (11), the imaging lens 3 can effectively shorten the total length of the lens, effectively improve the resolution, and effectively correct the aberration.

[0053] Table 1 Figure 1 Table of relevant parameters of each lens of imaging lens 3.

[0054] Table 1

[0055]

[0056]

[0057] The aspheric surface concavity z of the aspheric lens in Table 1 is obtained by the following formula:

[0058] z=ch 2 / {1+[1-(k+1)c 2 h 2 ] 1 / 2}+Ah 4 +Bh 6 +Ch 8 +Dh 10 +Eh 12 +Fh 14

[0059] Where: c: curvature; h: vertical distance from any point on the lens surface to the optical axis; k: cone coefficient; A~F: aspheric coefficient.

[0060] Table 2 is a table of relevant parameters of the aspheric surface of the aspheric lens in Table 1.

[0061]

[0062] Table 3 shows the relevant parameter values ​​of the imaging lens 3 of the fifth embodiment and the calculated values ​​corresponding to conditions (1) to (11). It can be seen from Table 3 that the imaging lens 3 of the fifth embodiment can meet the requirements of conditions (1) to (11).

[0063] Table 3

[0064]

[0065] In addition, the optical performance of the imaging lens 3 of the fifth embodiment can also meet the requirements. Figure 2 It can be seen that the field curvature of the imaging lens 3 of the fifth embodiment is between -0.09 mm and 0.06 mm. Figure 3 It can be seen that the distortion of the imaging lens 3 of the fifth embodiment is between 0% and 2.5%. Figure 4 It can be seen that the modulation transfer function value of the imaging lens 3 of the fifth embodiment is between 0.62 and 1.0. Figure 5 It can be seen that the Y field modulation transfer function value of the imaging lens 3 of the fifth embodiment is between 0.62 and 0.95. Figure 6 It can be seen that, for the imaging lens 3 of the fifth embodiment, when the focus offset is between -0.2 mm and 0.2 mm, the modulation transfer function value is between 0.02 and 0.95. It is obvious that the field curvature and distortion of the imaging lens 3 of the fifth embodiment can be effectively corrected, and the lens resolution can also meet the requirements, thereby obtaining better optical performance.

[0066] The sixth embodiment of the imaging lens of the present invention will now be described in detail. Figure 7The imaging lens 4 includes a first lens group LG41, a second lens group LG42, an aperture ST4, a third lens group LG43, a filter OF4 and a protective glass CG4 arranged in sequence from the object side to the image side along the optical axis OA4. The first lens group LG41 has positive refractive power, and the first lens group LG41 includes a 1-1 lens 4L1-1, a 1-2 lens 4L1-2 and a 1-3 lens 4L1-3 arranged in sequence from the object side to the image side along the optical axis OA4. The second lens group LG42 has negative refractive power, and the second lens group LG42 includes a 2-1 lens 4L2-1, a 2-2 lens 4L2-2 and a 2-3 lens 4L2-3 arranged in sequence from the object side to the image side along the optical axis OA4. The third lens group LG43 has positive refractive power, and the third lens group LG43 includes a 3-1 lens 4L3-1, a 3-2 lens 4L3-2, a 3-3 lens 4L3-3 and a 3-4 lens 4L3-4 arranged in sequence from the object side to the image side along the optical axis OA4. During imaging, the light from the object side is finally imaged on the imaging surface IMA4. According to the seventh to tenth paragraphs of [Specific Implementation], the object side surface S422 and the image side surface S423 of the filter OF4 are both planes; the object side surface S424 and the image side surface S425 of the protective glass CG4 are both planes; by using the above-mentioned lenses and a design that satisfies at least one of the conditions (1) to (11), the imaging lens 4 can effectively shorten the total length of the lens, effectively improve the resolution, and effectively correct the aberration.

[0067] Table 4 is Figure 7 Table of relevant parameters of each lens of the imaging lens 4.

[0068] Table 4

[0069]

[0070] The definition of the aspheric surface concavity z of each lens in Table 4 is the same as the definition of the aspheric surface concavity z of each lens in Table 1 of the fifth embodiment, and will not be repeated here. Table 5 is a table of related parameters of the aspheric surface of the aspheric lens in Table 4.

[0071]

[0072] Table 6 shows the relevant parameter values ​​of the imaging lens 4 of the sixth embodiment and the calculated values ​​corresponding to conditions (1) to (11). It can be seen from Table 6 that the imaging lens 4 of the sixth embodiment can meet the requirements of conditions (1) to (11).

[0073] Table 6

[0074]

[0075] In addition, the optical performance of the imaging lens 4 of the sixth embodiment can also meet the requirements. Figure 8 It can be seen that the field curvature of the imaging lens 4 of the sixth embodiment is between -0.21 mm and 0.06 mm. Fig. 9 It can be seen that the distortion of the imaging lens 4 of the sixth embodiment is between 0% and 2.5%. Fig.10 It can be seen that the modulation transfer function value of the imaging lens 4 of the sixth embodiment is between 0.66 and 1.0. Fig.11 It can be seen that the Y field modulation transfer function value of the imaging lens 4 of the sixth embodiment is between 0.67 and 0.95. Fig.12 It can be seen that, for the imaging lens 4 of the sixth embodiment, when the focus offset is between -0.2 mm and 0.2 mm, the modulation transfer function value is between 0.00 and 0.95. It is obvious that the field curvature and distortion of the imaging lens 4 of the sixth embodiment can be effectively corrected, and the lens resolution can also meet the requirements, thereby obtaining better optical performance.

[0076] In the above embodiments 1 to 6, the positive refractive power of the first lens group and the aspherical lenses of lenses 1-3 are helpful for the resolution. In the above embodiments 1 to 6, the design of the image side surfaces of the lenses in the first lens group and / or the second lens group being concave helps to shorten the total length of the lens. In any of the above embodiments 1 to 6, in another other embodiment, the second lens group is a focusing lens group that can be moved on the optical axis for focusing. This design is used with the refractive power of adjacent lenses in the second lens group and / or the third lens group being opposite, or with the lens closest to the object side of the second lens group and the third lens group being positive refractive, which helps to match the focus sensitivity with the moving range.

[0077] Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Those skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. An imaging lens, characterized in that: include: A first lens group having positive refractive power; a second lens group having negative refractive power and including at least two lenses; as well as a third lens group having positive refractive power and including a 3-1 lens, a 3-2 lens, a 3-3 lens, and a 3-4 lens; The first lens group, the second lens group and the third lens group are arranged in sequence from the object side to the image side along the optical axis; wherein the 3-1 lens, the 3-2 lens, the 3-3 lens, and the 3-4 lens are arranged in sequence from the object side to the image side along the optical axis; The 3-1 lens is a biconvex lens with positive refractive power, and includes a convex surface facing the object side and another convex surface facing the image side; The 3-3 lens includes a concave surface facing the image side; In the second lens group or the third lens group, two lenses closest to the image side are meniscus lenses.

2. The imaging lens according to claim 1, wherein: The refractive powers of adjacent lenses in the second lens group or the third lens group are opposite.

3. An imaging lens, characterized in that: include: A first lens group having positive refractive power; a second lens group having negative refractive power; as well as a third lens group, the third lens group having positive refractive power; The first lens group, the second lens group and the third lens group are arranged in sequence from the object side to the image side along the optical axis; The lens closest to the object side in the third lens group is a biconvex lens with positive refractive power, and includes a convex surface facing the object side and another convex surface facing the image side; The second lens group or the third lens group includes a plurality of lenses, and the refractive powers of adjacent lenses in the lenses are opposite.

4. The imaging lens according to claim 3, wherein: The third lens group includes a 3-1 lens, a 3-2 lens, a 3-3 lens, and a 3-4 lens arranged in sequence from the object side to the image side along the optical axis; The 3-3 lens includes a concave surface facing the image side; and In the second lens group or the third lens group, two lenses closest to the image side are meniscus lenses.

5. The imaging lens according to any one of claims 1 to 4, wherein: The second lens group includes a 2-1 lens, a 2-2 lens, and a 2-3 lens; One of the 2-1 lens, the 2-2 lens and the 2-3 lens is a biconcave lens and the other two are meniscus lenses; The 2-1 lens and the 2-3 lens have the same refractive power, and the 2-1 lens and the 2-2 lens have opposite refractive powers; and The refractive power of the lens closest to the object side in the second lens group is opposite to the refractive power of the lens closest to the object side in the third lens group.

6. The imaging lens according to any one of claims 1 to 4, wherein: The object side surface shape of the lens closest to the object side in the second lens group is the same as its image side surface shape; The image side surfaces of adjacent lenses in the first lens group or the second lens group are the same; and The second lens group and the third lens group include five meniscus lenses in total.

7. The imaging lens according to claim 2 or 4, wherein: The first lens group includes a 1-1 lens, a 1-2 lens, and a 1-3 lens arranged in sequence from the object side to the image side along the optical axis; The second lens group includes a 2-1 lens, a 2-2 lens, and a 2-3 lens arranged in sequence from the object side to the image side along the optical axis; The 1-2 lens includes a concave surface facing the image side; The 2-1 lens includes a concave surface facing the object side; The 2-2 lens is a meniscus lens having positive refractive power and comprising a convex surface facing the object side and a concave surface facing the image side; and The 2-3 lens is a meniscus lens with negative refractive power and includes a convex surface facing the object side and a concave surface facing the image side.

8. The imaging lens according to claim 7, wherein: The 1-1 lens is a meniscus lens with negative refractive power and includes a convex surface facing the object side and a concave surface facing the image side; The 1-2 lens is a meniscus lens with positive refractive power, and further includes a convex surface facing the object side; The 1-3 lens is a meniscus lens with positive refractive power, and includes a convex surface facing the object side and a concave surface facing the image side; The 2-1 lens is a biconcave lens having negative refractive power, and further comprises another concave surface facing the image side; The 3-2 lens is a meniscus lens with negative refractive power and includes a convex surface facing the object side and a concave surface facing the image side; The 3-3 lens is a meniscus lens having positive refractive power and further comprising a convex surface facing the object side; and The 3-4 lens is a meniscus lens with negative refractive power and includes a concave surface facing the object side and a convex surface facing the image side.

9. The imaging lens according to claim 7, wherein: The invention further comprises an aperture disposed between the second lens group and the third lens group, and the second lens group can move along the optical axis to perform focusing.

10. The imaging lens according to any one of claims 1 to 4, characterized in that: The imaging lens meets at least one of the following conditions: -0.76 <fG2 / f<-0.6; 0.8 <fG3 / f<1.8; 3.6<β2<6； 1.6 <fG3 / fG1<2.2; 0.75 <TTL / fG3<1.05; 4.5 <TTL / BFL<8; 0.7 <f / TTL<0.9; 3.6 <f / BFL<5.5; 0.4 <T11ST / TSTIMA<0.7; 0.53 <fG1 / f<0.82; Wherein f is the effective focal length of the imaging lens, fG1 is the effective focal length of the first lens group, fG2 is the effective focal length of the second lens group, fG3 is the effective focal length of the third lens group, TTL is the distance between the object side of the lens closest to the object side and the imaging plane on the optical axis, BFL is the distance between the image side of the lens closest to the image side and the imaging plane on the optical axis, T11ST is the distance between the object side of the lens closest to the object side and the aperture on the optical axis, TSTIMA is the distance between the aperture and the imaging plane on the optical axis, and β2 is the lateral magnification of the second lens group when an object is located at infinity.

Images