A zoom lens with a constant large aperture

Abstract

The present invention relates to a zoom lens with a constant large aperture, comprising: a first lens group with positive focal power, a second lens group with negative focal power, an aperture, a third lens group with positive focal power, and a fourth lens group with positive focal power, which are arranged in sequence from the object side to the image side; the first lens group and the third lens group are fixed groups, the second lens group moves along the optical axis from the object side to the image side to perform a zoom from a wide-angle end to a telephoto end, and the fourth lens group moves along the optical axis to correct the image plane position during the zoom process; the first lens group and the second lens group satisfy: 2.0≤(d 12t ‑d 12w ) / fw≤4.0, where d 12t is the distance from the image side of the last lens of the first lens group to the object side of the first lens of the second lens group when the zoom lens is at the telephoto end; d 12w f is the distance from the image side of the last lens of the first lens group to the object side of the first lens of the second lens group when the zoom lens is at the wide-angle end; W This is the focal length at the wide-angle end.

Description

Technical Field

[0001] The invention relates to the field of optical imaging, and in particular to a zoom lens with a constant large aperture. Background Art

[0002] Zoom lenses are becoming increasingly popular in the security monitoring market because of their variable focal length, making them suitable for a variety of monitoring scenarios.

[0003] The existing constant aperture zoom lenses on the market still have some performance defects that limit their use scenarios. For example, the wide-angle angle is not large enough, the monitoring range is limited; the aperture is small and cannot meet the monitoring needs of low-light environments; the resolution is insufficient, the resolution is low, the zoom range is small, and the monitoring range is limited. Summary of the invention

[0004] The purpose of the present invention is to solve the above problems and provide a zoom lens with a constant large aperture to solve the problem of poor imaging performance of the zoom lens.

[0005] To achieve the above object, the present invention provides a zoom lens with a constant large aperture, comprising: a first lens group with positive focal power, a second lens group with negative focal power, an aperture stop, a third lens group with positive focal power, and a fourth lens group with positive focal power, which are arranged in sequence from the object side to the image side;

[0006] The first lens group and the third lens group are fixed groups, the second lens group moves along the optical axis from the object side to the image side to change the magnification from the wide-angle end to the telephoto end, and at the same time, the fourth lens group moves along the optical axis to correct the image plane position during the magnification change process;

[0007] The first lens group and the second lens group satisfy:

[0008] 2.0≤(d 12t -d 12w ) / fw≤4.0

[0009] Among them, d 12t represents the distance from the image side surface of the last lens element of the first lens group to the object side surface of the first lens element of the second lens group when the zoom lens is at the telephoto end; d 12w represents the distance from the image side surface of the last lens element of the first lens group to the object side surface of the first lens element of the second lens group when the zoom lens is at the wide-angle end; f W This is the focal length at the wide-angle end.

[0010] According to one aspect of the present invention, the first lens group includes: one lens with negative optical power and two lenses with positive optical power;

[0011] According to one aspect of the present invention, the second lens group includes: two or three lenses with negative optical power and one lens with positive optical power;

[0012] According to one aspect of the present invention, the third lens group includes: three or four lenses with negative optical power, and three or four lenses with positive optical power; wherein, from the object side to the image side, the optical power of the last lens in the third lens group is positive;

[0013] According to one aspect of the present invention, the fourth lens group includes: two lenses with negative optical power and two lenses with positive optical power; wherein, from the object side to the image side, the optical power of the last lens in the fourth lens group is negative.

[0014] According to one aspect of the present invention, the lenses in the third lens group include an aspherical lens.

[0015] According to one aspect of the present invention, the first lens group includes a doublet lens group;

[0016] The second lens group includes a doublet lens group;

[0017] The third lens group includes one or two doublet lens groups;

[0018] The fourth lens group includes one or two doublet lens groups.

[0019] According to one aspect of the present invention, the focal length f2 of the second lens group is equal to the focal length f2 at the wide-angle end of the zoom lens. W Satisfies the following relationship: 1.0≤|f2| / f w ≤3.0.

[0020] According to one aspect of the present invention, the focal length f3 of the third lens group is equal to the focal length f at the wide-angle end of the zoom lens. W Satisfies the following relationship: 1.5≤f3 / f w ≤5.

[0021] According to one aspect of the present invention, in the first lens group, at least one lens with positive focal power has a relative refractive index temperature coefficient dn / dt (Li) Satisfies the following relationship: -8*10 -6 ≤dn / dt (Li) ≤-3*10 -6 .

[0022] According to one aspect of the present invention, in the second lens group, at least one lens with negative focal power has a relative refractive index temperature coefficient dn / dt (Lj) Satisfies the following relationship: -8*10-6 ≤dn / dt (Lj) ≤-3*10 -6 .

[0023] According to one aspect of the present invention, in the third lens group, at least one lens with positive focal power has a refractive index Nd (Lk) and Abbe number Vd (Lk) Satisfy the following relationship: 60≤VD (Lk) ≤95,1.4≤ND (Lk) ≤1.6.

[0024] According to one aspect of the present invention, in the fourth lens group, at least one lens with positive focal power has a refractive index Nd (Lh) and Abbe number Vd (Lh) Satisfy the following relationship: 60≤VD (Lh) ≤95,1.4≤ND (Lh) ≤1.6.

[0025] According to one solution of the present invention, the zoom lens of the present invention can achieve high-quality imaging at different magnifications by reasonably matching four lens groups.

[0026] According to one solution of the present invention, the zoom lens of the present invention achieves high-quality imaging effect by reasonably distributing glasses with different refractive indices.

[0027] According to one embodiment of the present invention, the zoom lens of the present invention has excellent resolution and image quality close to the diffraction limit.

[0028] According to one solution of the present invention, the zoom lens of the present invention has a large and constant aperture, ensuring uniform illumination at different magnifications.

[0029] According to one solution of the present invention, the zoom lens of the present invention can achieve infrared confocality, ensuring high-quality imaging at both visible light wavelengths and infrared light wavelengths.

[0030] According to one solution of the present invention, the zoom lens of the present invention has small distortion, high imaging quality, uniform image quality, fine image quality, rich colors and high contrast.

[0031] According to one solution of the present invention, the zoom lens of the present invention has high overall transmittance and uniform picture brightness.

[0032] According to one solution of the present invention, the zoom lens of the present invention can solve the problem of temperature drift and can produce clear images without refocusing in a temperature range of -40°C to 80°C.

[0033] According to one embodiment of the present invention, the zoom lens of the present invention has good individual component and assembly tolerances and good manufacturability.

[0034] According to one solution of the present invention, the first lens group G1 is a fixed group, which mainly functions to correct the aberration and distortion of the system, while reducing the tolerance sensitivity and ensuring the uniformity of the picture. The second lens group G2 is set to move, which can ensure that the aperture value changes less while achieving the zoom from the wide-angle end to the telephoto end. The third lens group G3 is a fixed group, which shares the correction pressure of the first and second lens groups on the incident angle of the main light, ensuring good color reproduction. The fourth lens group G4 is used to move to focus at different magnifications, which can more effectively improve the imaging quality at different object distances and ensure the uniformity of the picture. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1-2 is a diagram schematically showing the lens structure at the wide-angle end and the telephoto end of the zoom lens in Embodiment 1 of the present invention when the object distance is infinite;

[0036] Figure 3-5 Schematically shows the position chromatic aberration, magnification chromatic aberration, and distortion diagram of the zoom lens at the wide-angle end when the object distance is infinite in Example 1 of the present invention;

[0037] Figure 6-8 Schematically shows the position chromatic aberration, magnification chromatic aberration, and distortion diagram of the zoom lens at the telephoto end when the object distance is infinite in Example 1 of the present invention;

[0038] Fig. 9 Schematically shows the performance diagram of the zoom lens at the wide-angle end when the object distance is infinite, the defocus curves of visible light and infrared, and the defocus curve diagram under high and low temperatures in Example 1 of the present invention;

[0039] Figure 10-11 is a diagram schematically showing the lens structure at the wide-angle end and the telephoto end of the zoom lens when the object distance is infinite in Embodiment 2 of the present invention;

[0040] Figure 12-14 Schematically shows the position chromatic aberration, magnification chromatic aberration, and distortion diagram of the zoom lens at the wide-angle end when the object distance is infinite in Example 2 of the present invention;

[0041] Figure 15-17 Schematically shows the position chromatic aberration, magnification chromatic aberration, and distortion diagram of the zoom lens at the telephoto end when the object distance is infinite in Example 2 of the present invention;

[0042] Fig.18 Schematically shows the performance diagram of the zoom lens at the wide-angle end when the object distance is infinite, the defocus curves of visible light and infrared, and the defocus curve diagram under high and low temperatures in Example 2 of the present invention;

[0043] Figure 19-21 is a diagram schematically showing the lens structure at the wide-angle end and the telephoto end of the zoom lens when the object distance is infinite in Embodiment 3 of the present invention;

[0044] Figure 22-23 Schematically shows the position chromatic aberration, magnification chromatic aberration, and distortion of the zoom lens at the wide-angle end when the object distance is infinite in Example 3 of the present invention;

[0045] Figure 24-26 Schematically shows the position chromatic aberration, magnification chromatic aberration, and distortion diagram of the zoom lens at the telephoto end when the object distance is infinite in Example 3 of the present invention;

[0046] Fig. 27 is a diagram schematically showing the performance of the zoom lens at the wide-angle end when the object distance is infinite, the defocus curves of visible light and infrared, and the defocus curves at high and low temperatures in Example 3 of the present invention;

[0047] Figure 28-29 is a diagram schematically showing the lens structure at the wide-angle end and the telephoto end of the zoom lens when the object distance is infinite in Embodiment 4 of the present invention;

[0048] Figure 30-32 Schematically shows the position chromatic aberration, magnification chromatic aberration, and distortion diagram of the zoom lens at the wide-angle end when the object distance is infinite in Example 4 of the present invention;

[0049] Figure 33-35 Schematically shows the position chromatic aberration, magnification chromatic aberration, and distortion diagram of the zoom lens at the telephoto end when the object distance is infinite in Example 4 of the present invention;

[0050] Fig.36 Schematically showing the performance diagram of the zoom lens at the wide-angle end when the object distance is infinite, the defocus curves of visible light and infrared, and the defocus curve diagram under high and low temperatures in Example 4 of the present invention;

[0051] Figure 37-38 is a diagram schematically showing the lens structure at the wide-angle end and the telephoto end of the zoom lens when the object distance is infinite in Embodiment 5 of the present invention;

[0052] Figure 39-41 Schematically shows the position chromatic aberration, magnification chromatic aberration, and distortion diagram of the zoom lens at the wide-angle end when the object distance is infinite in Example 5 of the present invention;

[0053] Figure 42-44 Schematically shows the position chromatic aberration, magnification chromatic aberration, and distortion diagram of the zoom lens at the telephoto end when the object distance is infinite in Example 5 of the present invention;

[0054] Fig.45 It schematically shows the performance diagram of the zoom lens at the wide-angle end when the object distance is infinite in Example 5 of the present invention, the defocus curves of visible light and infrared, and the defocus curve diagram under high and low temperatures. DETAILED DESCRIPTION

[0055] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0056] When describing the embodiments of the present invention, the orientation or positional relationship expressed by the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the orientation or positional relationship shown in the relevant drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the above terms should not be understood as limiting the present invention.

[0057] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. The embodiments cannot be described one by one here, but the embodiments of the present invention are not therefore limited to the following embodiments.

[0058] like Figure 1 As shown, according to an embodiment of the present invention, a zoom lens with a constant large aperture of the present invention comprises: a first lens group G1 with positive focal power, a second lens group G2 with negative focal power, an aperture STOP, a third lens group G3 with positive focal power, and a fourth lens group G4 with positive focal power, which are arranged in sequence from the object side to the image side along the optical axis. In this embodiment, the first lens group G1 and the third lens group G3 are fixed groups, the second lens group G2 moves along the optical axis from the object side to the image side to perform zooming from the wide-angle end to the telephoto end, and at the same time, the fourth lens group G4 moves along the optical axis to correct the image plane position during the zooming process.

[0059] In this embodiment, the first lens group G1 and the second lens group G2 satisfy:

[0060] 2.0≤(d 12t -d 12w ) / fw≤4.0

[0061] Among them, d 12t It represents the distance from the image side of the last lens of the first lens group G1 to the object side of the first lens of the second lens group G2 when the zoom lens is at the telephoto end; d 12w It indicates the distance from the image side of the last lens of the first lens group G1 to the object side of the first lens of the second lens group G2 when the zoom lens is at the wide-angle end; f W This is the focal length at the wide-angle end.

[0062] Through the above arrangement, the first lens group G1 and the second lens group G2 satisfy the above relationship, which effectively reduces the aberration between the first lens group G1 and the second lens group G2, and also effectively controls the volume of the entire zoom lens, thereby reducing the design and manufacturing costs of the entire zoom lens.

[0063] like Figure 1 As shown, according to an embodiment of the present invention, the first lens group G1 includes: one lens with negative optical power and two lenses with positive optical power. In this embodiment, the first lens group G1 includes a doublet lens group composed of the above-mentioned multiple lenses.

[0064] Through the above arrangement, the use of lenses with positive and negative optical powers is beneficial to correcting the spherical aberration, astigmatism and distortion inside the first lens group G1, thereby facilitating the realization of the large aperture effect of the zoom lens of the present invention. In addition, through the above arrangement, the tolerance sensitivity of the lens group is effectively reduced, which is beneficial to reducing the difficulty of production and assembly of the group.

[0065] like Figure 1 As shown, according to an embodiment of the present invention, the second lens group G2 includes: two or three lenses with negative optical power and one lens with positive optical power. In this embodiment, the second lens group G2 includes a doublet lens group composed of multiple lenses.

[0066] Through the above arrangement, the use of lenses with positive and negative optical power and a cemented lens group is beneficial to correcting the spherical aberration, astigmatism and distortion inside the second lens group G2. Correction of aberrations inside the second lens group G2 is beneficial to reducing the burden ratio of aberration correction on the first lens group, and can better reduce the tolerance sensitivity of the active group, which is beneficial to comprehensively improving the imaging quality of the entire zoom lens.

[0067] like Figure 1 As shown, according to an embodiment of the present invention, the third lens group G3 includes: three or four lenses with negative focal power, and three or four lenses with positive focal power; wherein, from the object side to the image side, the focal power of the last lens in the third lens group G3 is positive; in this embodiment, the third lens group G3 includes one or two doublet lens groups formed by the above-mentioned multiple lenses. In this embodiment, the lenses in the third lens group G3 include one aspherical lens.

[0068] Through the above arrangement, by using cemented lenses and aspherical lenses in the third lens group, the optical system can smoothly collect incident light, effectively reduce the field curvature and astigmatism generated by incident light with a large field of view, and maintain the advantage of low distortion while achieving a large aperture.

[0069] like Figure 1As shown, according to an embodiment of the present invention, the fourth lens group G4 includes: two lenses with negative optical power and two lenses with positive optical power; wherein, from the object side to the image side, the optical power of the last lens in the fourth lens group G4 is negative. In this embodiment, the fourth lens group G4 includes one or two doublet lens groups formed by the above-mentioned multiple lenses.

[0070] Through the above-mentioned settings, the use of lenses with positive and negative optical focal lengths and cemented lens groups is used in combination, which is beneficial to ensuring sufficient back focus and a larger imaging frame. At the same time, it is also beneficial to achieve a smaller main light incident angle and realize high color restoration of the picture.

[0071] like Figure 1 As shown, according to one embodiment of the present invention, the focal length f2 of the second lens group G2 is equal to the focal length f at the wide-angle end of the zoom lens. W Satisfies the following relationship: 1.0≤|f2| / f w ≤3.0.

[0072] Through the above arrangement, the focal length of the second lens group and the focal length of the wide-angle end of the zoom lens satisfy the above relationship, which effectively improves the resolution of the telephoto end of the present invention, while achieving the requirements of large-magnification zoom and small volume, effectively reducing design and manufacturing costs.

[0073] like Figure 1 As shown, according to one embodiment of the present invention, the focal length f3 of the third lens group G3 is equal to the focal length f at the wide-angle end of the zoom lens. W Satisfies the following relationship: 1.5≤f3 / f w ≤5.

[0074] Through the above arrangement, the focal length of the third lens group and the focal length of the wide-angle end of the zoom lens satisfy the above relationship, which can effectively reduce the tolerance sensitivity of the third lens group and effectively improve the resolution of the entire zoom lens. In addition, through the above arrangement, the zoom lens of the present invention can also achieve the requirements of large magnification zoom and small volume, effectively reducing the design and manufacturing costs.

[0075] like Figure 1 As shown, according to one embodiment of the present invention, in the first lens group G1, at least one lens with positive focal power has a relative refractive index temperature coefficient dn / dt (Li) Satisfies the following relationship: -8*10 -6 ≤dn / dt (Li) ≤-3*10 -6 .

[0076] Through the above arrangement, the lenses in the first lens group are selectively made to satisfy the above relationship, which is beneficial to the temperature correction of the athermal system and can more effectively balance the image plane drift at the telephoto end of the zoom lens under high and low temperature conditions.

[0077] like Figure 1 As shown, according to one embodiment of the present invention, in the second lens group G2, at least one lens with negative focal power has a relative refractive index temperature coefficient dn / dt (Lj) Satisfies the following relationship: -8*10 -6 ≤dn / dt (Lj) ≤-3*10 -6 .

[0078] Through the above arrangement, the lenses in the first lens group are selectively made to satisfy the above relationship, which is beneficial to the temperature correction of the athermal system and can more effectively balance the image plane drift at the telephoto end of the zoom lens under high and low temperature conditions.

[0079] like Figure 1 As shown, according to one embodiment of the present invention, in the third lens group G3, at least one lens with positive focal power has a refractive index Nd (Lk) and Abbe number Vd (Lk) Satisfy the following relationship: 60≤VD (Lk) ≤95,1.4≤ND (Lk) ≤1.6.

[0080] like Figure 1 As shown, according to one embodiment of the present invention, in the fourth lens group G4, at least one lens with positive focal power has a refractive index Nd (Lh) and Abbe number Vd (Lh) Satisfy the following relationship: 60≤VD (Lh) ≤95,1.4≤ND (Lh) ≤1.6.

[0081] Through the above arrangement, the lenses in the third lens group G3 are selectively made to satisfy the above relationship, so that the chromatic aberration and distortion of the third lens group and the fourth lens group can be effectively corrected, which is beneficial to improving the imaging quality of the entire zoom system.

[0082] According to the present invention, the first lens group G1 is a fixed group, and its main function is to correct the aberration and distortion of the system, while reducing the tolerance sensitivity and ensuring the uniformity of the picture. The second lens group G2 is used to move, and the aperture value can be kept small while achieving the zoom from the wide-angle end to the telephoto end. The third lens group G3 is a fixed group, which shares the correction pressure of the first and second lens groups on the incident angle of the main light, ensuring good color reproduction. The fourth lens group G4 is used to move to focus at different magnifications, which can more effectively improve the imaging quality at different object distances and ensure the uniformity of the picture.

[0083] Five groups of specific implementations are given below according to the above configuration of the present invention to specifically illustrate the zoom lens according to the present invention.

[0084] In the following embodiments, the aspheric lens surface shape satisfies the following formula:

[0085] Z=cy 2 / {1+[1-(1+k)c 2 y 2 ]1 / 2}+a4y 4 +a6y 6 +a8y 8 +a 10 y 10 +a 12 y 12 +a 14 y 14

[0086] Among them, parameter c is the curvature corresponding to the radius of the aspheric lens, y is the radial coordinate of the aspheric lens, and its unit is the same as the unit of lens length, k is the conic quadratic curve coefficient of the aspheric lens, and a4, a6...a12 are the corresponding order coefficients of the aspheric surface.

[0087] The data of the five implementation methods are summarized as shown in Table 1 below:

[0088]

[0089] Table 1

[0090] The following embodiments are described in conjunction with the zoom lens structures shown in the accompanying drawings.

[0091] Implementation method 1:

[0092] In this embodiment, the parameters of the zoom lens are as follows:

[0093] TTL = 168.1 mm;

[0094] FNO = 1.10;

[0095] Wide-angle focal length fw =12.0mm;

[0096] Telephoto focal length f t =60.5mm;

[0097] In this embodiment, in the zoom lens, from the object side to the image side, the first lens group G1 is sequentially provided with a first lens L1, a second lens L2 and a third lens L3;

[0098] From the object side to the image side, the second lens group G2 is sequentially provided with a fourth lens L4, a fifth lens L5, a sixth lens L6 and a seventh lens L7;

[0099] From the object side to the image side, the third lens group G3 is provided with an eighth lens L8, a ninth lens L9, a tenth lens L10, an eleventh lens L11, a twelfth lens L12, a thirteenth lens L13 and a fourteenth lens L14 in sequence;

[0100] From the object side to the image side, the fourth lens group G4 includes a fifteenth lens L15, a sixteenth lens L16, a seventeenth lens L17 and an eighteenth lens L18 in sequence.

[0101] Because the zoom lens according to the present invention has a total of 18 lenses, including multiple cemented lens groups, plus the aperture surface STOP, a total of 30 surfaces. These 30 surfaces are arranged in sequence according to the structural order of the present invention. For the convenience of description, the 30 surfaces are numbered sur1 to sur30, where the aperture surface is replaced by Stop instead of sur13, the cemented surfaces in the cemented lens group are represented by one number, and the imaging surface is represented as Image.

[0102] Table 2 is a parameter table of implementation mode 1:

[0103]

[0104]

[0105] Table 2

[0106] In this embodiment, the aspheric surface data is shown in Table 3 below:

[0107]

[0108]

[0109] Table 3

[0110] In this embodiment, the relative refractive index temperature coefficient of the second lens L2 in the first lens group G1 is: dn / dt (L2) =-3.5*10 -6 ;

[0111] The relative refractive index temperature coefficient of the third lens L3 in the first lens group G1 is: dn / dt (L3) =-6.2*10 -6 ;

[0112] The relative refractive index temperature coefficient of the fourth lens L7 in the second lens group G2 is: dn / dt (L7) =-6.2*10 -6 .

[0113] In this embodiment, the refractive index and Abbe number of the fifth lens L12 in the third lens group G3 are: Nd L12 =1.59, Vd L12 =68.62;

[0114] The refractive index and Abbe number of the second lens L16 in the fourth lens group G4 are: Nd L16 =1.62, Vd L16 =63.40.

[0115] Combination Figures 3 to 9 By optimizing the above parameter values, the maximum aperture of the lens in this embodiment is 1.1, achieving a large aperture, coinfocality of visible light and infrared light, and the best maximum field of view at the wide-angle end and the telephoto end. In addition, the zoom lens of the present invention also has the advantage of temperature compensation. In a large temperature difference range, the lens does not need to be refocused to ensure the same resolution as at normal temperature.

[0116] Implementation method 2:

[0117] In this embodiment, the parameters of the zoom lens are as follows:

[0118] TTL = 169.3 mm;

[0119] FNO = 1.0;

[0120] Wide-angle focal length f w =15.0mm;

[0121] Telephoto focal length f t =57.6mm;

[0122] In this embodiment, in the zoom lens, from the object side to the image side, the number of lenses in the first lens group G1, the second lens group G2, the third lens group G3 and the fourth lens group G4 is consistent with that in the first embodiment, and will not be repeated here.

[0123] In this embodiment, the zoom lens of the present invention has a total of 18 lenses, including a plurality of cemented lens groups, and a stop surface STOP, a total of 31 surfaces. The 31 surfaces are arranged in sequence according to the structural sequence of the present invention. For the convenience of description, the 31 surfaces are numbered sur1 to sur31, wherein the stop surface is replaced by Stop instead of sur13, the cemented surfaces in the cemented lens group are represented by one number, and the imaging surface is represented by Image.

[0124] Table 4 is a parameter table of implementation mode 2:

[0125]

[0126]

[0127] Table 4

[0128] In this embodiment, the aspheric surface data is shown in Table 5 below:

[0129]

[0130] Table 5

[0131] In this embodiment, the relative refractive index temperature coefficient of the third lens L3 in the first lens group G1 is: dn / dt (L3) =-5.7*10 -6 ;

[0132] The relative refractive index temperature coefficient of the first lens L4 in the second lens group G2 is: dn / dt (L4) =-6.2*10 -6 .

[0133] In this embodiment, the refractive index and Abbe number of the fifth lens L12 in the third lens group G3 are: Nd L12 =1.59, Vd L12 =68.6;

[0134] The refractive index and Abbe number of the second lens L16 in the fourth lens group G4 are: NdL16=1.69, VdL16=54.6.

[0135] Combination Figures 12 to 18 By optimizing the above parameter values, the maximum aperture of the lens in this embodiment is 1.0, achieving a large aperture, coinfocality of visible light and infrared light, and the best maximum field of view at the wide-angle end and the telephoto end. In addition, the zoom lens of the present invention also has the advantage of temperature compensation. Within a large temperature difference range, the lens does not need to be refocused to ensure the same resolution as at normal temperature.

[0136] Implementation method three:

[0137] In this embodiment, the parameters of the zoom lens are as follows:

[0138] TTL = 181.34 mm;

[0139] FNO = 1.0;

[0140] Wide-angle focal length fw = 19.5;

[0141] Telephoto focal length ft = 60.5;

[0142] In this embodiment, in the zoom lens, from the object side to the image side, the number of lenses in the first lens group G1, the second lens group G2, the third lens group G3 and the fourth lens group G4 are the same, which will not be described in detail here.

[0143] In this embodiment, the zoom lens of the present invention has a total of 18 lenses, including a plurality of cemented lens groups, and a stop surface STOP, a total of 32 surfaces. These 32 surfaces are arranged in sequence according to the structural sequence of the present invention. For the convenience of description, the 31 surfaces are numbered sur1 to sur31, wherein the stop surface is replaced by Stop instead of sur13, the cemented surfaces in the cemented lens group are represented by one number, and the imaging surface is represented by Image.

[0144] Table 6 is a parameter table of implementation method 3:

[0145]

[0146]

[0147]

[0148] Table 6

[0149] In this embodiment, the aspheric surface data is shown in Table 7 below:

[0150]

[0151] Table 7

[0152] In this embodiment, the relative refractive index temperature coefficient of the second lens L2 in the first lens group G1 is: dn / dt (L2) =-7.4*10 -6 ;

[0153] The relative refractive index temperature coefficient of the first lens L4 in the second lens group G2 is: dn / dt (L4) =-6.2*10 -6 .

[0154] In this embodiment, the refractive index and Abbe number of the fifth lens L12 in the third lens group G3 are: Nd L12 =1.55, Vd L12 =75.50;

[0155] The refractive index and Abbe index of the first lens L15 in the fourth lens group G4 are: Nd L15 =1.59, Vd L15 =68.6.

[0156] Combination Figure 21 to Figure 27 By optimizing the above parameter values, the maximum aperture of the lens in this embodiment is 1.0, achieving a large aperture, coinfocality of visible light and infrared light, and the best maximum field of view at the wide-angle end and the telephoto end. In addition, the zoom lens of the present invention also has the advantage of temperature compensation. Within a large temperature difference range, the lens does not need to be refocused to ensure the same resolution as at normal temperature.

[0157] Implementation method 4:

[0158] In this embodiment, the parameters of the zoom lens are as follows:

[0159] TTL = 174.9 mm;

[0160] FNO = 1.1;

[0161] Wide-angle focal length fw = 12.5;

[0162] Telephoto focal length ft = 58.6;

[0163] In this embodiment, in the zoom lens, from the object side to the image side, the first lens group G1 is sequentially provided with a first lens L1, a second lens L2 and a third lens L3;

[0164] From the object side to the image side, the second lens group G2 is sequentially provided with a fourth lens L4, a fifth lens L5 and a sixth lens L6;

[0165] From the object side to the image side, the third lens group G3 is sequentially provided with a seventh lens L7, an eighth lens L8, a ninth lens L9, a tenth lens L10, an eleventh lens L11, a twelfth lens L12 and a thirteenth lens L13;

[0166] From the object side to the image side, the fourth lens group G4 includes a fourteenth lens L14, a fifteenth lens L15, a sixteenth lens L16 and a seventeenth lens L17 in sequence.

[0167] In this embodiment, the zoom lens of the present invention has a total of 17 lenses, including a plurality of cemented lens groups, and a stop surface STOP, a total of 28 surfaces. The 28 surfaces are arranged in sequence according to the structural sequence of the present invention. For the convenience of description, the 28 surfaces are numbered sur1 to sur28, wherein the stop surface is replaced by Stop instead of sur11, the cemented surfaces in the cemented lens group are represented by one number, and the imaging surface is represented by Image.

[0168] Table 8 is a parameter table of implementation mode 4:

[0169]

[0170]

[0171] Table 8

[0172] In this embodiment, the aspheric surface data is shown in Table 9 below:

[0173]

[0174] Table 9

[0175] In this embodiment, the relative refractive index temperature coefficient of the second lens L2 in the first lens group G1 is: dn / dt (L2) =-3.7*10 -6 ;

[0176] The relative refractive index temperature coefficient of the third lens L3 in the first lens group G1 is: dn / dt (L3) =-6.3*10 -6 ;

[0177] The relative refractive index temperature coefficient of the third lens L6 in the second lens group G2 is: dn / dt (L6) =-6.2*10 -6 .

[0178] In this embodiment, the refractive index and Abbe number of the fourth lens L10 in the third lens group G3 are: Nd L10 =1.55, Vd L10 =75.50;

[0179] The refractive index and Abbe index of the second lens L15 in the fourth lens group G4 are: Nd L15 =1.50, Vd L15 =81.6.

[0180] Combination Figure 30 to Figure 36By optimizing the above parameter values, the maximum aperture of the lens in this embodiment is 1.1, achieving a large aperture, coinfocality of visible light and infrared light, and the best maximum field of view at the wide-angle end and the telephoto end. In addition, the zoom lens of the present invention also has the advantage of temperature compensation. In a large temperature difference range, the lens does not need to be refocused to ensure the same resolution as at normal temperature.

[0181] Implementation method five:

[0182] In this embodiment, the parameters of the zoom lens are as follows:

[0183] TTL = 174.5 mm;

[0184] FNO = 1.0;

[0185] Wide-angle focal length fw = 11;

[0186] Telephoto focal length ft = 60.5;

[0187] In this embodiment, in the zoom lens, from the object side to the image side, the number of lenses in the first lens group G1, the second lens group G2, the third lens group G3 and the fourth lens group G4 is consistent with that in the first embodiment, and will not be repeated here.

[0188] In this embodiment, the zoom lens of the present invention has a total of 18 lenses, including a plurality of cemented lens groups, and a stop surface STOP, a total of 32 surfaces. These 31 surfaces are arranged in sequence according to the structural sequence of the present invention. For the convenience of description, the 32 surfaces are numbered sur1 to sur32, wherein the stop surface is replaced by Stop instead of sur13, the cemented surfaces in the cemented lens group are represented by one number, and the imaging surface is represented by Image.

[0189] Table 10 is a parameter table of implementation mode 5:

[0190]

[0191]

[0192]

[0193] Table 10

[0194] In this embodiment, the aspheric surface data is shown in Table 11 below:

[0195]

[0196] Table 11

[0197] In this embodiment, the relative refractive index temperature coefficient of the first lens L1 in the first lens group G1 is: dn / dt(L1) =-6.2*10 -6 ;

[0198] The relative refractive index temperature coefficient of the fourth lens L7 in the second lens group G2 is: dn / dt (L7) =-5.6*10 -6 .

[0199] In this embodiment, the refractive index and Abbe number of the fifth lens L12 in the third lens group G3 are: Nd L12 =1.59, Vd L12 =68.6;

[0200] The refractive index and Abbe number of the first lens L15 in the fourth lens group G4 are: Nd L15 =1.46, Vd L15 =90.2.

[0201] Combination Figure 39 to Figure 45 By optimizing the above parameter values, the maximum aperture of the lens in this embodiment is 1.0, achieving a large aperture, coinfocality of visible light and infrared light, and the best maximum field of view at the wide-angle end and the telephoto end. In addition, the zoom lens of the present invention also has the advantage of temperature compensation. Within a large temperature difference range, the lens does not need to be refocused to ensure the same resolution as at normal temperature.

[0202] From the above description, it can be seen that the zoom lens of the present invention achieves a maximum aperture of ≤1.2, and can achieve co-focusing of visible light and infrared light. In addition, the lens design takes temperature compensation into consideration, and within a large temperature range, the lens does not need to be refocused to ensure the same resolution as at normal temperature.

[0203] The above is only one embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A zoom lens with a constant large aperture, characterized in that: include: The lens group includes a first lens group (G1) with positive power, a second lens group (G2) with negative power, an aperture, a third lens group (G3) with positive power, and a fourth lens group (G4) with positive power, which are arranged in sequence from the object side to the image side, totaling four lens groups; The first lens group (G1) and the third lens group (G3) are fixed groups, the second lens group (G2) moves along the optical axis from the object side to the image side to change the magnification from the wide-angle end to the telephoto end, and at the same time, the fourth lens group (G4) moves along the optical axis to correct the image plane position during the magnification change process; The second lens group (G2) comprises: two or three lenses with negative optical power and one lens with positive optical power, a total of three lenses or four lenses; When the second lens group (G2) includes three lenses, the focal powers of the lenses from the object side to the image side are negative focal power, positive focal power, and negative focal power, respectively; When the second lens group (G2) includes four lenses, the optical power of the lenses from the object side to the image side is negative optical power, negative optical power, positive optical power, and negative optical power in sequence; The fourth lens group (G4) includes: two lenses with negative focal power and two lenses with positive focal power, a total of four lenses; wherein, from the object side to the image side, the focal power of each lens is negative focal power, positive focal power, positive focal power, negative focal power, or The optical power of each lens is positive optical power, negative optical power, positive optical power, negative optical power in sequence; The first lens group (G1) and the second lens group (G2) satisfy: 2.0≤(d 12t -d 12w ) / fw≤4.0 Among them, d 12t represents the distance from the image side surface of the last lens of the first lens group (G1) to the object side surface of the first lens of the second lens group (G2) when the zoom lens is at the telephoto end; d 12w represents the distance from the image side surface of the last lens element of the first lens group (G1) to the object side surface of the first lens element of the second lens group (G2) when the zoom lens is at the wide-angle end; f W This is the focal length at the wide-angle end.

2. The zoom lens according to claim 1, wherein: The first lens group (G1) comprises: one lens with negative focal power, two lenses with positive focal power, a total of three lenses, and the focal powers of the lenses from the object side to the image side are: negative focal power, positive focal power, positive focal power; or The optical power of each lens is: positive optical power, negative optical power, positive optical power.

3. The zoom lens according to claim 1, wherein: The third lens group (G3) comprises: three or four lenses with negative focal power, three or four lenses with positive focal power, a total of seven lenses; wherein, from the object side to the image side, the focal power of the last lens in the third lens group (G3) is positive, and from the object side to the image side, the focal powers of the lenses are: positive focal power, negative focal power, positive focal power, negative focal power, positive focal power, negative focal power, positive focal power, positive focal power, positive focal power; or Negative power, negative power, positive power, negative power, positive power, negative power, positive power; or Negative power, positive power, negative power, positive power, negative power, negative power, positive power.

4. The zoom lens according to claim 3, wherein: The lenses in the third lens group (G3) include an aspherical lens.

5. The zoom lens according to any one of claims 2 to 4, characterized in that: The first lens group (G1) comprises a doublet lens group; The second lens group (G2) comprises a doublet lens group; The third lens group (G3) comprises one or two doublet lens groups; The fourth lens group (G4) comprises one or two doublet lens groups.

6. The zoom lens according to any one of claims 1 to 4, characterized in that: The focal length f2 of the second lens group (G2) is equal to the focal length f2 at the wide-angle end of the zoom lens. W Satisfies the following relationship: 1.0≤|f2| / f w ≤3.

0.

7. The zoom lens according to any one of claims 1 to 4, characterized in that: The focal length f3 of the third lens group (G3) is equal to the focal length f3 at the wide-angle end of the zoom lens. W Satisfies the following relationship: 1.5≤f3 / f w ≤5.

8. The zoom lens according to any one of claims 2 to 4, characterized in that: In the first lens group (G1), at least one lens with positive focal power has a relative refractive index temperature coefficient dn / dt (Li) Satisfies the following relationship: -8*10 -6 ≤dn / dt (Li) ≤-3*10 -6 .

9. The zoom lens according to any one of claims 2 to 4, characterized in that: In the second lens group (G2), at least one lens with negative focal power has a relative refractive index temperature coefficient dn / dt (Lj) Satisfies the following relationship: -8*10 -6 ≤dn / dt (Lj) ≤-3*10 -6 .

10. The zoom lens according to any one of claims 2 to 4, characterized in that: In the third lens group (G3), at least one lens with positive focal power has a refractive index Nd (Lk) and Abbe number Vd (Lk) Satisfy the following relationship: 60≤VD (Lk) ≤95,1.4≤ND (Lk) ≤1.

6.

11. The zoom lens according to any one of claims 2 to 4, characterized in that: In the fourth lens group (G4), at least one lens with positive focal power has a refractive index Nd (Lh) and Abbe number Vd (Lh) Satisfy the following relationship: 60≤VD (Lh) ≤95,1.4≤ND (Lh) ≤1.6.

Images