Zoom lens

Abstract

The invention discloses a zoom lens, which belongs to the technical field of optics and consists of an image surface positioned on an image side, and a front fixed group A with positive focal power, a zoom group B with negative focal power, a middle fixed group C with positive focal power and a compensation group D with positive focal power which are sequentially arranged from an object side to the image side, the lens is composed of a negative meniscus lens A1, a positive meniscus lens A2, a biconvex lens A3, a positive meniscus lens A4, a negative meniscus lens B1, a biconcave lens B2, a biconvex lens B3, a biconcave lens B4, a diaphragm, a biconvex lens C1, a negative meniscus lens C2, a positive meniscus lens C3, a biconvex lens C4, a negative meniscus lens C5, a biconvex lens D1, a positive meniscus lens D2, a biconvex lens D3 and a biconcave lens D4 which are sequentially arranged from the object side to the image side. And the imaging quality is high, and good image quality can be obtained.

Description

Technical Field

[0001] The invention belongs to the field of optical technology, and in particular relates to a zoom lens. Background Art

[0002] At present, with the gradual popularization of security monitoring, it is more and more widely used, user awareness is gradually deepening, and the requirements for image quality are getting higher and higher. Simply increasing the pixels on the original 1 / 3" series image sensor to improve the image resolution can no longer meet the user's experience needs. The existing solution is to increase the photosensitive area of ​​the image sensor, that is, to use a 1 / 2" series image sensor. Because the increase in the image sensor area causes a sharp increase in the lens diameter, length, and cost, the increase in the lens volume leads to a series of problems such as the increase in the camera's pan / tilt and casing. Therefore, a lens with a moderate diameter and length is needed to prevent the size of the camera from being excessively increased while also ensuring the zoom effect. Summary of the invention

[0003] In order to overcome the above-mentioned deficiencies, the inventors of the present invention have continuously reformed and innovated through long-term exploration and attempts, multiple experiments and efforts, and proposed a zoom lens, which has the advantages of high lens resolution, high imaging quality, and good image quality, as well as the characteristics of large magnification, large field of view, large relative aperture, and large target surface.

[0004] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is to provide a zoom lens. It is composed of an image plane located on the image side and the following four lens groups: The front fixed group A has positive optical power and is composed of four lenses having refractive powers, which are arranged in order from the object side to the image side: a negative meniscus lens A1, a positive meniscus lens A2, a biconvex lens A3, and a positive meniscus lens A4; The zoom group B has negative optical power and is disposed between the front fixed group A and the image side. It is composed of four lenses with refractive power, namely, a negative meniscus lens B1, a biconcave lens B2, a biconvex lens B3, and a biconcave lens B4, which are arranged in sequence from the object side to the image side. The intermediate fixed group C has positive optical power and is disposed between the zoom group B and the image side. It is composed of five lenses with refractive power, namely, a biconvex lens C1, a negative meniscus lens C2, a positive meniscus lens C3, a biconvex lens C4, and a negative meniscus lens C5, which are arranged in order from the object side to the image side. A stop is provided before the biconvex lens C1. The compensation group D has positive optical power and is disposed between the intermediate fixed group C and the image side. It is composed of four lenses with refractive power, namely, a biconvex lens D1, a positive meniscus lens D2, a biconvex lens D3, and a biconcave lens D4, which are arranged in order from the object side to the image side. The front fixed group A, the zoom group B, the middle fixed group C, and the compensation group D are arranged in sequence from the object side to the image side.

[0005] According to the zoom lens described in the present invention, a further preferred technical solution is: the negative meniscus lens A1 and the positive meniscus lens A2 are tightly bonded to form a first bonding group; the biconvex lens B3 and the biconcave mirror B4 are tightly bonded to form a second bonding group; the biconvex lens C1 and the negative meniscus lens C2 are tightly bonded to form a third bonding group; the biconvex lens D3 and the biconcave mirror D4 are tightly bonded to form a fourth bonding group.

[0006] According to a zoom lens described in the present invention, a further preferred technical solution is: the concave surface of the negative meniscus lens A1, the concave surface of the positive meniscus lens A2, the large surface of the biconvex lens A3, and the concave surface of the positive meniscus lens A4 of the front fixed group A are facing the image side; the concave surface of the negative meniscus lens B1, the small surface of the biconcave mirror B2, the small surface of the biconvex lens B3, and the large surface of the biconcave mirror B4 of the zoom group B are facing the image side; the small surface of the biconvex lens C1, the convex surface of the negative meniscus lens C2, the concave surface of the positive meniscus lens C3, the large surface of the biconvex lens C4, and the concave surface of the negative meniscus lens C5 of the intermediate fixed group C are facing the image side; the large surface of the biconvex lens D1, the concave surface of the positive meniscus lens D2, the large surface of the biconvex lens D3, and the small surface of the biconcave mirror D4 of the compensation group D are facing the image side. In the present invention, the large surface and the small surface refer to that the radii of the two surfaces in the biconvex and biconcave lenses are generally different, so a large surface and a small surface will appear.

[0007] According to a zoom lens described in the present invention, a further preferred technical solution is: when the lens changes from short focal length to long focal length: the moving direction of the zoom group B is from the front fixed group A to the middle fixed group C, and the interval between the front fixed group A and the zoom group B is 0.45mm-44mm, so that the moving range of the zoom group B from the short focal length end to the long focal length end of the lens is 43.55mm; the moving direction of the compensation group D is from the image plane to the middle fixed group C, and the interval between the middle fixed group C and the compensation group D is 6mm-24.5mm, so that the moving range of the compensation group D from the short focal length end to the long focal length end of the lens is 18.5mm.

[0008] According to the zoom lens of the present invention, a further preferred technical solution is: the combined focal length of the front fixed group A meets the condition: the combined focal length of the front fixed group A meets the condition: 63 mm <f A <73 mm; zoom group B combined focal length meets the condition: -13.5 mm <f B <9.5 mm; the focal length of the middle fixed group C meets the conditions: 36.5 mm <f C <46.5 mm; Compensation group D combined focal length meets the conditions: 32.5 mm <f D <38.5 mm.

[0009] According to the zoom lens of the present invention, a further preferred technical solution is that the lenses of the front fixed group A, the variable power group B, the intermediate fixed group C and the compensation group D are all made of spherical optical glass lenses.

[0010] Compared with the prior art, the technical solution of the present invention has the following advantages / benefits: 1. The zoom lens of the present invention has the advantages of high lens resolution, high imaging quality, and good image quality.

[0011] 2. The zoom lens of the present invention has the characteristics of large magnification, large field of view, large relative aperture, and large target surface.

[0012] 3. The zoom lens of the present invention is equipped with a relatively lightweight zoom and compensation group, which facilitates high-speed zoom and focusing in an integrated structure.

[0013] 4. The zoom lens of the present invention adopts a full-spherical optical glass lens, which is conducive to mass production of products, has high quality consistency, and has the characteristics of high cost performance.

[0014] 5. The zoom lens of the present invention has the characteristics of uniform illumination on the target surface and good night vision effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 It is a schematic diagram of the optical system of the present invention; Figure 2 This is a light layout diagram of the present invention when the focal length is short; Figure 3 This is a light layout diagram of the present invention when the focus is medium; Figure 4 This is a light layout diagram of the present invention at a long focus; Figure 5 This is the MTF diagram of the present invention at short focus; Figure 6 This is the transmission MTF diagram of the present invention at mid-focus; Figure 7 This is the MTF diagram of the invention at telephoto; Figure 8 This is a field curvature / distortion diagram of the present invention at short focal length; Fig. 9 This is a field curvature / distortion diagram of the present invention at mid-focus; Fig.10 This is a field curvature / distortion diagram of the present invention at telephoto; Fig.11 This is the spot diagram of the present invention at short focus; Fig.12 This is a point diagram of the present invention at mid-focus; Fig.13 It is a point diagram of the present invention at a long focal length. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention are clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention. Therefore, the detailed description of the embodiments of the present invention provided below is not intended to limit the scope of the claimed invention, but merely represents the selected embodiments of the present invention.

[0018] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and thus, once an item is defined in one drawing, it may not be further defined or explained in the subsequent drawings.

[0019] Example: like Figure 1-Figure 7 , a zoom lens, has the advantages of high lens resolution, large zoom, large field of view, large relative aperture, and large target surface. It consists of an image plane located on the image side and the following four lens groups: The front fixed group A has positive optical power and is composed of four lenses with refractive power, namely, negative meniscus lens A1, positive meniscus lens A2, biconvex lens A3, and positive meniscus lens A4, which are arranged in order from the object side to the image side. The front fixed group is used for pre-focusing of light. The front fixed group is a four-piece structure. The high refractive index and high dispersion are glued with the low refractive index and low dispersion to better correct the chromatic aberration of the long focal length system. The four-piece structure greatly reduces the difficulty of lens processing at the short focal length while ensuring the same aberration contribution; The zoom group B has negative optical power and is arranged between the front fixed group A and the image side. It is composed of four lenses with refractive power, which are arranged in sequence from the object side to the image side, namely, a negative meniscus lens B1, a biconcave lens B2, a biconvex lens B3, and a biconcave lens B4. The zoom group is used to change the focal length of the system by moving the zoom group. A four-piece structure is adopted to obtain a better correction effect of long-short focal aberrations. The middle fixed group C has positive optical power and is arranged between the zoom group B and the image side. It is composed of five lenses with refractive power, which are arranged in order from the object side to the image side: biconvex lens C1, negative meniscus lens C2, positive meniscus lens C3, biconvex lens C4, and negative meniscus lens C5. An aperture is set before the biconvex lens C1. The middle fixed group adopts the main aperture plus auxiliary aperture mode, which effectively solves the influence of off-axis stray light in the long focal length and improves image quality. The compensation group D has positive optical power and is disposed between the intermediate fixed group C and the image side. It is composed of four lenses with refractive power, which are arranged in sequence from the object side to the image side, namely, a biconvex lens D1, a positive meniscus lens D2, a biconvex lens D3, and a biconcave lens D4. The function of the compensation group is to compensate for the image plane deviation caused by the movement of the zoom group. The front fixed group A, the zoom group B, the middle fixed group C, and the compensation group D are arranged in order from the object side to the image side. The image plane is where the image receptor is placed. In this embodiment, the negative meniscus lens A1 and the positive meniscus lens A2 are tightly bonded together to form a first bonding group; the biconvex lens B3 and the biconcave mirror B4 are tightly bonded together to form a second bonding group; the biconvex lens C1 and the negative meniscus lens C2 are tightly bonded together to form a third bonding group; the biconvex lens D3 and the biconcave mirror D4 are tightly bonded together to form a fourth bonding group.

[0020] In this embodiment, the concave surface of the negative meniscus lens A1, the concave surface of the positive meniscus lens A2, the large surface of the biconvex lens A3, and the concave surface of the positive meniscus lens A4 of the front fixed group A are facing the image side; the concave surface of the negative meniscus lens B1, the small surface of the biconcave mirror B2, the small surface of the biconvex lens B3, and the large surface of the biconcave mirror B4 of the zoom group B are facing the image side; the small surface of the biconvex lens C1, the convex surface of the negative meniscus lens C2, the concave surface of the positive meniscus lens C3, the large surface of the biconvex lens C4, and the concave surface of the negative meniscus lens C5 of the intermediate fixed group C are facing the image side; the large surface of the biconvex lens D1, the concave surface of the positive meniscus lens D2, the large surface of the biconvex lens D3, and the small surface of the biconcave mirror D4 of the compensation group D are facing the image side.

[0021] Figure 2-Figure 4 As shown is a light layout diagram, in this embodiment, when the lens changes from short focus to long focus: the moving direction of the zoom group B is from the front fixed group A to the middle fixed group C, and the interval between the front fixed group A and the zoom group B is 0.45~44mm, so that the moving range of the zoom group B from the short focus end to the long focus end of the lens is 43.55mm; the moving direction of the compensation group D is from the image plane to the middle fixed group C, and the interval between the middle fixed group C and the compensation group D is 6-24.5mm, so that the moving range of the compensation group D from the short focus end to the long focus end of the lens is 18.5mm.

[0022] In this embodiment, the combined focal length of the front fixed group A meets the condition: 63 mm <f A<73 mm; zoom group B combined focal length meets the condition: -13.5 mm <f B <9.5 mm; the focal length of the middle fixed group C meets the conditions: 36.5 mm <f C <46.5 mm; Compensation group D combined focal length meets the conditions: 32.5 mm <f D <38.5 mm.

[0023] The physical parameters of each lens in this embodiment meet the data requirements shown in Table 1 below: Table 1 As shown in the above table, surfaces 1, 2, and 3 correspond to the first cemented group, surfaces 4 and 5 correspond to biconvex lenses A3, surfaces 6 and 7 correspond to positive meniscus lenses A4, surfaces 8 and 9 correspond to negative meniscus lenses B1, surfaces 10 and 11 correspond to biconcave lenses B2, surfaces 12, 13, and 14 correspond to the second cemented group, surface 15 (STO in the table, the abbreviation of aperture) corresponds to the aperture, surfaces 16, 17, and 18 correspond to the third cemented group, surfaces 19 and 20 correspond to positive meniscus lenses C3, surfaces 21 and 22 correspond to biconvex lenses C4, surfaces 23 and 24 correspond to negative meniscus lenses C5, surfaces 25 and 26 correspond to biconvex lenses D1, surfaces 27 and 28 correspond to positive meniscus lenses D2, surfaces 29, 30, and 31 correspond to the fourth cemented group, surface 32 is an air spacer (no actual parameter explanation, if the material in the table is empty, it is an air surface), and surface Ima corresponds to the image plane. In the table, STO is the abbreviation of aperture, and IMA is the image plane. Figure 5-Figure 7 The transmission MTF diagrams of the present invention at short focal length, medium focal length and long focal length are given. The diffraction MTF calculation is based on the fast Fourier transform FFT of pupil data. The MTF result is obtained by spatial frequency modulation of the sine wave. Figure 5 The center MTF of the present invention is greater than 0.75 and the edge MTF is greater than 0.3 at short focal length. Figure 6 The center MTF of the present invention is greater than 0.6 when the focus is medium, and the edge MTF is greater than 0.3. Figure 7 At long focal length, the center MTF of the present invention is greater than 0.45, and the edge MTF is greater than 0.25. Figure 8 , Fig. 9 , Fig.10 The field curvature and distortion curves of the zoom lens designed by the present invention at short focus, medium focus and long focus are given, and the ordinate in the figure represents the normalized field of view coordinate; it can be seen that the field curvature of the present invention at short focus is less than 0.05mm, and the distortion is less than 8.5%; the field curvature of the present invention at medium focus is less than 0.2mm, and the distortion is less than 0.3%; the field curvature of the present invention at long focus is less than 0.3mm, and the distortion is less than 0.35%. Fig.11 , Fig.12 , Fig.13The spot diagrams of the zoom lens designed by the present invention at short focal length, medium focal length and long focal length are given. In the spot diagram at short focal length, coordinate 20 represents the square Fig.10 The total of the grids is 20 microns, and a single grid represents 2 microns. In the short focus of the present invention, the center RMS radius is 1.25 microns, the GEO radius is 2 microns, the edge RMS radius is 1.22 microns, and the GEO radius is 2.3 microns. In the point diagram at medium focus, the coordinate 100 represents the grid. Fig.10 The total of the grids is 100 microns, and a single grid represents 10 microns. In the present invention, the center RMS radius is 1.43 microns, the GEO radius is 2.4 microns, the edge RMS radius is 9 microns, and the GEO radius is 26 microns when the focus is medium. In the point diagram at telephoto, the coordinate 100 represents the grid. Fig.10 The total of the grids is 100 microns, and a single grid represents 10 microns; when the present invention is telephoto, the center RMS radius is 3.2 microns, the GEO radius is 4 microns, the edge RMS radius is 5.9 microns, and the GEO radius is 20 microns. It can be seen that the lens of the present invention has the characteristics of high resolution and high imaging quality, and good image quality can be obtained. The lenses of the front fixed group A, the variable magnification group B, the middle fixed group C, and the compensation group D of the present invention all use full-spherical optical glass lenses, which is conducive to the mass production of products, with high quality consistency and high product cost performance.

[0024] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and 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 operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0025] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0026] The above are only preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be regarded as limiting the present invention, and the protection scope of the present invention should be based on the scope defined by the claims. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the spirit and scope of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A zoom lens, characterized in that: It consists of an image plane located on the image side and the following four lens groups: The front fixed group A has positive optical power and is composed of four lenses having refractive powers, which are arranged in order from the object side to the image side: a negative meniscus lens A1, a positive meniscus lens A2, a biconvex lens A3, and a positive meniscus lens A4; The zoom group B has negative optical power and is disposed between the front fixed group A and the image side. It is composed of four lenses with refractive power, namely, a negative meniscus lens B1, a biconcave lens B2, a biconvex lens B3, and a biconcave lens B4, which are arranged in sequence from the object side to the image side. The intermediate fixed group C has positive optical power and is disposed between the zoom group B and the image side. It is composed of five lenses with refractive power, namely, a biconvex lens C1, a negative meniscus lens C2, a positive meniscus lens C3, a biconvex lens C4, and a negative meniscus lens C5, which are arranged in order from the object side to the image side. A stop is provided before the biconvex lens C1. The compensation group D has positive optical power and is disposed between the intermediate fixed group C and the image side. It is composed of four lenses with refractive power, namely, a biconvex lens D1, a positive meniscus lens D2, a biconvex lens D3, and a biconcave lens D4, which are arranged in order from the object side to the image side. The front fixed group A, the zoom group B, the middle fixed group C, and the compensation group D are arranged in sequence from the object side to the image side.

2. The zoom lens according to claim 1, characterized in that: The negative meniscus lens A1 and the positive meniscus lens A2 are tightly bonded together to form a first bonding group; the biconvex lens B3 and the biconcave mirror B4 are tightly bonded together to form a second bonding group; the biconvex lens C1 and the negative meniscus lens C2 are tightly bonded together to form a third bonding group; the biconvex lens D3 and the biconcave mirror D4 are tightly bonded together to form a fourth bonding group.

3. The zoom lens according to claim 1, characterized in that: The concave surface of the negative meniscus lens A1, the concave surface of the positive meniscus lens A2, the large surface of the biconvex lens A3, and the concave surface of the positive meniscus lens A4 of the front fixed group A are facing the image side; the concave surface of the negative meniscus lens B1, the small surface of the biconcave lens B2, the small surface of the biconvex lens B3, and the large surface of the biconcave lens B4 of the zoom group B are facing the image side; the small surface of the biconvex lens C1, the convex surface of the negative meniscus lens C2, the concave surface of the positive meniscus lens C3, the large surface of the biconvex lens C4, and the concave surface of the negative meniscus lens C5 of the intermediate fixed group C are facing the image side; The large surface of the biconvex lens D1 of the compensation group D, the concave surface of the positive meniscus lens D2, the large surface of the biconvex lens D3, and the small surface of the biconcave mirror D4 face the image side.

4. The zoom lens according to claim 1, characterized in that: When the lens changes from short focal length to long focal length: the movement direction of the zoom group B is from the front fixed group A to the middle fixed group C, and the interval between the front fixed group A and the zoom group B is 0.45mm-44mm, so that the movement range of the zoom group B from the short focal length end to the long focal length end of the lens is 43.55mm; the movement direction of the compensation group D is from the image plane to the middle fixed group C, and the interval between the middle fixed group C and the compensation group D is 6mm-24.5mm, so that the movement range of the compensation group D from the short focal length end to the long focal length end of the lens is 18.5mm.

5. The zoom lens according to claim 1, characterized in that: The combined focal length of the front fixed group A meets the condition: 63 mm < f A <73 mm; the focal length of zoom group B meets the condition: -13.5 mm < f B <9.5 mm; the focal length of the intermediate fixed group C meets the condition: 36.5 mm < f C <46.5 mm; the focal length of compensation group D meets the condition: 32.5 mm < f D <38.5 mm.

6. The zoom lens according to claim 1, characterized in that: The lenses of the front fixed group A, the variable magnification group B, the intermediate fixed group C, and the compensation group D are all made of spherical optical glass lenses.

Images