Liquid focusing lens and camera shooting instrument with same

Abstract

The liquid focusing lens comprises a first lens group, a second lens group and a third lens group which are sequentially arranged from the object side to the image side, the second lens group comprises a liquid lens, the focal length of the liquid lens is changed by changing the curvature of the liquid surface, and finally the purpose of focusing is achieved. The liquid focusing lens disclosed by the invention has the advantages of being high in focusing speed, high in efficiency, high in precision, high in resolving power, capable of meeting the requirement for miniaturization use of equipment and the like while meeting the requirement for small size, the liquid lens can be replaced, liquid lenses produced by different manufacturers in the market can be used, and the liquid focusing lens is more universal; the liquid focusing lens is wide in applicable object distance range and can be used for different object distances, and the object distance range is 80 mm to infinity.

Description

Technical Field

[0001] The invention belongs to the technical field of optical lenses, and in particular relates to a liquid focusing lens and a camera having the same. Background Art

[0002] At present, most industrial equipment is equipped with traditional industrial focusing lenses. The characteristics of this type of lens are: the impact of changes in object distance can only be compensated by moving the lens group, so that the image quality remains clear and is not affected by changes in object distance. The methods of moving the lens group are roughly divided into manual focusing and electric focusing. Manual focusing is slow and inefficient. Although electric focusing is fast, the size of the entire lens will be larger, which is not conducive to miniaturization.

[0003] With the rapid development of science and technology, the development of liquid lenses has changed dramatically, and its related technologies have entered the mass production and civilian stage from the laboratory stage. Compared with traditional industrial focusing lenses, lenses with liquid lenses have the advantages of smaller size and faster focusing speed, which can further miniaturize industrial equipment equipped with optical lenses.

[0004] Based on this, the present invention discloses a liquid focusing lens and an imaging instrument having the same. Summary of the invention

[0005] In order to solve the technical problems existing in the prior art, the purpose of the present invention is to provide a liquid focusing lens and a camera having the same, which has the advantages of fast focusing speed, high resolution, and meeting the use requirements of miniaturization of equipment while meeting the requirements of small size.

[0006] In order to achieve the above purpose and the above technical effect, the technical solution adopted by the present invention is:

[0007] A liquid focusing lens comprises a first lens group, a second lens group and a third lens group which are arranged in sequence from the object side to the image side. The second lens group comprises a liquid lens. The focal length of the liquid lens is changed by changing the curvature of the liquid surface, thereby finally achieving the purpose of focusing.

[0008] Furthermore, the first lens group satisfies the relationship:

[0009] -6 <f1 / f<-2;

[0010] Wherein, f is the focal length of the liquid focusing lens, and f1 is the focal length of the first lens group.

[0011] Furthermore, the first lens group includes a first lens and a second lens arranged in sequence from the object side to the image side, and the first lens and the second lens meet the following conditions:

[0012] Nd(G1)≥1.7;

[0013] Nd(G2)≥1.7;

[0014] Wherein, Nd(G1) is the refractive index of the first lens, and Nd(G2) is the refractive index of the second lens.

[0015] Furthermore, the first lens is a meniscus positive lens with its convex surface facing the object plane, and the second lens is a plano-concave negative lens with its concave surface facing the image plane.

[0016] Furthermore, the first lens is a plano-convex positive lens with the convex surface facing the object plane, and the second lens is a biconcave negative lens.

[0017] Furthermore, the liquid lens satisfies the relationship:

[0018] -0.015<1 / fy<0.025;

[0019] Where fy is the focal length of the liquid lens.

[0020] Furthermore, the liquid lens satisfies the following conditions:

[0021] The length of the liquid lens from front to back (including the liquid lens itself) is ≥3.5mm.

[0022] Further, the third lens group comprises a third lens and a fourth lens arranged in sequence from the object side to the image side, the third lens is a biconvex positive refractive power lens, and the fourth lens is a biconcave negative refractive power lens;

[0023] The third lens and the fourth lens meet the following conditions:

[0024] Nd(G3)≥1.7;

[0025] Nd(G4)≥1.7;

[0026] Wherein, Nd(G3) is the refractive index of the third lens, and Nd(G4) is the refractive index of the fourth lens.

[0027] Further, the third lens group comprises a third lens, a fourth lens and a fifth lens arranged in sequence from the object side to the image side, the third lens is a biconvex positive refractive power lens, and the fourth lens is a biconcave negative refractive power lens;

[0028] The third lens, the fourth lens and the fifth lens meet the following conditions:

[0029] Nd(G3)≥1.7;

[0030] Nd(G4)≥1.7;

[0031] Nd(G5)≥1.8;

[0032] Wherein, Nd(G3) is the refractive index of the third lens, Nd(G4) is the refractive index of the fourth lens, and Nd(G5) is the refractive index of the fifth lens.

[0033] Furthermore, the liquid focusing lens satisfies the relationship:

[0034] -1 <f4 / f<3;

[0035] Wherein, f is the focal length of the liquid focusing lens, and f4 is the combined focal length of the third lens, the fourth lens and the fifth lens.

[0036] Furthermore, the third lens and the fourth lens are not glued together. In this case, the third lens and the fourth lens meet the following conditions:

[0037] -20 <f2 / f<5;

[0038] Wherein, f is the focal length of the liquid focusing lens, and f2 is the combined focal length of the third lens and the fourth lens.

[0039] Furthermore, the third lens and the fourth lens are glued together to form a first glued lens group, and the first glued lens group satisfies the relationship:

[0040] -20 <f3 / f<5;

[0041] Wherein, f is the focal length of the liquid focusing lens, and f3 is the focal length of the first cemented lens group.

[0042] Furthermore, the fifth lens is a biconvex positive refractive power lens.

[0043] Furthermore, the fifth lens is a plano-convex positive refractive power lens with the convex surface facing the image plane.

[0044] Furthermore, a stop is provided between the second lens group and the third lens.

[0045] Furthermore, the focal length of the liquid focusing lens is f=16 mm, the aperture value FNO=5.6, the half image height is ≤4.8 mm, and the total length is within 30 mm.

[0046] The present invention also discloses an imaging instrument comprising the liquid focusing lens as described above, wherein the imaging instrument is any one of a camera, a video camera, a microscope, a telescope and an endoscope.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] 1) Compared with the previous focusing lens, the liquid focusing lens disclosed in the present invention has a smaller volume and is suitable for use in miniaturized equipment;

[0049] 2) Compared with the previous focusing lens, the liquid focusing lens disclosed in the present invention has higher precision and is easier to operate;

[0050] 3) The liquid focusing lens disclosed in the present invention has strong versatility, and the liquid lens can be replaced, and liquid lenses produced by different manufacturers on the market can be used;

[0051] 4) Compared with the previous focusing lens, the liquid focusing lens disclosed in the present invention has faster focusing speed and higher efficiency;

[0052] 5) The liquid focusing lens disclosed in the present invention is applicable to different interface types;

[0053] 6) The liquid focusing lens disclosed in the present invention is applicable to a wide range of object distances and can be used for different object distances, and the object distance range satisfies: 80mm~∞. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 Schematic diagram of the structure of the liquid focusing lens according to Embodiment 1 of the present invention;

[0055] Figure 2 Schematic diagram of MTF of Example 1 of the present invention;

[0056] Figure 3 Schematic diagram of the structure of the liquid focusing lens according to Embodiment 2 of the present invention;

[0057] Figure 4 This is a schematic diagram of MTF of Example 2 of the present invention. DETAILED DESCRIPTION

[0058] The present invention is described in detail below so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0059] A brief summary of one or more aspects is given below to provide a basic understanding of these aspects. This summary is not an exhaustive overview of all conceived aspects, and is neither intended to identify the key or critical elements of all aspects nor to define the scope of any or all aspects. Its only purpose is to give some concepts of one or more aspects in a simplified form as a prelude to a more detailed description that will be given later.

[0060] like Figure 1-4 As shown, a liquid focusing lens comprises a first lens group, a second lens group and a third lens group arranged in sequence from the object side to the image side, wherein the first lens group comprises a first lens G1 and a second lens G2, and the second lens group comprises a liquid lens L1. The focal length of the liquid lens L1 is changed by changing the curvature of the liquid surface, thereby finally achieving the purpose of focusing.

[0061] In the present invention, the focal length of the liquid lens L1 can be changed by changing the refractive index or shape of the liquid lens L1, or by changing the performance of the liquid lens L1 itself by changing the operating voltage to achieve a change in focal length.

[0062] In the present invention, the first lens group satisfies the relationship:

[0063] -6 <f1 / f<-2;

[0064] Wherein, f is the focal length of the liquid focusing lens, and f1 is the focal length of the first lens group.

[0065] In the present invention, a stop STO is disposed between the second lens group and the third lens G3.

[0066] In the present invention, the first lens G1 and the second lens G2 satisfy the following conditions:

[0067] n(G1)≥1.7;

[0068] n(G2)≥1.7;

[0069] Wherein, n(G1) is the refractive index of the first lens G1, and n(G2) is the refractive index of the second lens G2.

[0070] In some embodiments, the first lens group includes: the first lens G1 is a meniscus positive lens, with a convex surface facing the object plane; the second lens G2 is a plano-concave negative lens, with a concave surface facing the image plane.

[0071] In some embodiments, the first lens group includes: the first lens G1 is a plano-convex positive lens with a convex surface facing the object plane; and the second lens G2 is a biconcave negative lens.

[0072] In the present invention, the liquid lens L1 satisfies the following conditions:

[0073] The length of the liquid lens from front to back (including the liquid lens itself) is ≥3.5mm, and can be replaced with liquid lenses from different manufacturers as needed.

[0074] The liquid lens L1 satisfies the relationship:

[0075] -0.015<1 / fy<0.025;

[0076] Among them, fy is the focal length of the liquid lens L1. The liquid lens L1 changes its own performance by changing the working voltage to achieve the change of focal length and finally achieve the purpose of focusing.

[0077] In some embodiments, the third lens group includes a third lens G3 and a fourth lens G4 arranged in sequence from the object side to the image side, the third lens G3 is a biconvex positive refractive power lens, the fourth lens G4 is a biconcave negative refractive power lens, and the third lens G3 and the fourth lens G4 meet the following conditions:

[0078] Nd(G3)≥1.7;

[0079] Nd(G4)≥1.7;

[0080] Wherein, Nd(G3) is the refractive index of the third lens G3, and Nd(G4) is the refractive index of the fourth lens G4.

[0081] In some embodiments, the third lens group includes a third lens G3, a fourth lens G4, and a fifth lens G5 arranged in sequence from the object side to the image side, the third lens G3 is a biconvex positive refractive power lens, and the fourth lens G4 is a biconcave negative refractive power lens, satisfying the following conditions:

[0082] Nd(G3)≥1.7;

[0083] Nd(G4)≥1.7;

[0084] Nd(G5)≥1.8;

[0085] Wherein, Nd(G3) is the refractive index of the third lens G3, Nd(G4) is the refractive index of the fourth lens G4, and Nd(G5) is the refractive index of the fifth lens G5.

[0086] In some embodiments, the third lens G3 and the fourth lens G4 may not be glued together. In this case, the third lens G3 and the fourth lens G4 meet the following conditions:

[0087] -20 <f2 / f<5;

[0088] Wherein, f is the focal length of the liquid focusing lens, and f2 is the combined focal length of the third lens G3 and the fourth lens G4.

[0089] In some embodiments, the third lens G3 and the fourth lens G4 may be cemented together to form a first cemented lens group D1, and the first cemented lens group D1 satisfies the relationship:

[0090] -20 <f3 / f<5;

[0091] Wherein, f3 is the focal length of the first cemented lens group D1.

[0092] In some embodiments, the liquid focusing lens satisfies the relationship:

[0093] -1 <f4 / f<3;

[0094] Wherein, f4 is the combined focal length of the third lens G3, the fourth lens G4 and the fifth lens G5.

[0095] In some embodiments, the fifth lens G5 is a biconvex positive refractive power lens.

[0096] In some embodiments, the fifth lens G5 is a plano-convex positive refractive power lens with a convex surface facing the image plane.

[0097] The liquid focusing lens disclosed in the invention has a focal length f=16mm, an aperture value FNO=5.6, a half image height ≤4.8mm, a total length within 30mm, a short total length, and a small volume of the entire lens.

[0098] The present invention also discloses an imaging instrument comprising the liquid focusing lens as described above. The imaging instrument is any one of a camera, a video camera, a microscope, a telescope and an endoscope.

[0099] Example 1

[0100] like Figure 1-2 As shown, a liquid focusing lens comprises a first lens group, a second lens group and a third lens group which are arranged in sequence from the object side to the image side, wherein the first lens group comprises a first lens G1 and a second lens G2 which are arranged in sequence from the object side to the image side, the second lens group comprises a liquid lens L1, the third lens group comprises a third lens G3, a fourth lens G4 and a fifth lens G5 which are arranged in sequence from the object side to the image side, an aperture STO is arranged between the second lens group and the third lens G3, and all lenses are glass spherical surfaces.

[0101] The first lens G1 is a meniscus positive lens with its convex surface facing the object plane; the second lens G2 is a plano-concave negative lens with its concave surface facing the image plane; the third lens G3 is a bi-convex positive refractive power lens; the fourth lens G4 is a bi-concave negative refractive power lens; the fifth lens G5 is a plano-convex positive refractive power lens with its convex surface facing the image plane.

[0102] A cover glass IR+CG is provided on the image side of the fifth lens G5.

[0103] The first lens group satisfies the relationship:

[0104] f1 / f=-3.7;

[0105] Wherein, f is the focal length of the liquid focusing lens, and f1 is the focal length of the first lens group.

[0106] The third lens G3 and the fourth lens G4 are cemented together to form a first cemented lens group D1. The first cemented lens group D1 satisfies the relationship:

[0107] f3 / f=-5.22;

[0108] Wherein, f3 is the focal length of the first cemented lens group D1.

[0109] The liquid lens L1 satisfies the relationship:

[0110] 1 / fy=-0.0006 (at object distance 400mm);

[0111] Among them, fy is the focal length of the liquid lens L1. The liquid lens L1 changes its own performance by changing the working voltage to achieve the change of focal length and finally achieve the purpose of focusing.

[0112] The liquid focusing lens of this embodiment satisfies the relationship:

[0113] f4 / f=0.66;

[0114] Wherein, f4 is the focal length of the combination of the third lens G3, the fourth lens G4 and the fifth lens G5.

[0115] The parameters of the liquid focusing lens of this embodiment are shown in Table 1.

[0116] Table 1

[0117] Focal length f 16mm Aperture value FNO 5.6 Half Image Height 4.8mm Total length 30mm wavelength Visible light

[0118] The shape, material, refractive index and Abbe number parameters of each lens in this embodiment are shown in Table 2.

[0119] Table 2

[0120]

[0121] In Table 2, when the radius of curvature is Infinity, it means that the surface is a plane.

[0122] Figure 2 : This is a schematic diagram of the MTF of this embodiment, in which the OTF coefficient corresponding to the spatial frequency of the central field of view 145LP / mm is above 0.22, and the lens achieves high resolution characteristics.

[0123] Example 2

[0124] like Figure 3-4 As shown, a liquid focusing lens comprises a first lens group, a second lens group and a third lens group which are arranged in sequence from the object side to the image side, wherein the first lens group comprises a first lens G1 and a second lens G2 which are arranged in sequence from the object side to the image side, the second lens group comprises a liquid lens L1, the third lens group comprises a third lens G3, a fourth lens G4 and a fifth lens G5 which are arranged in sequence from the object side to the image side, an aperture STO is arranged between the second lens group and the third lens G3, and all lenses are glass spherical surfaces.

[0125] The first lens G1 is a plano-convex positive lens with its convex surface facing the object plane; the second lens G2 is a biconcave negative lens; the third lens G3 is a biconvex positive refractive power lens; the fourth lens G4 is a biconcave negative refractive power lens; and the fifth lens G5 is a biconvex positive refractive power lens.

[0126] A cover glass IR+CG is provided on the image side of the fifth lens G5.

[0127] The first lens group satisfies the relationship:

[0128] f1 / f=-4.4;

[0129] Wherein, f is the focal length of the liquid focusing lens, and f1 is the focal length of the first lens group.

[0130] The third lens G3 and the fourth lens G4 are not glued together and satisfy the relationship:

[0131] f2 / f=2.8;

[0132] Wherein, f2 is the combined focal length of the third lens G3 and the fourth lens G4.

[0133] The liquid lens L1 satisfies the relationship:

[0134] 1 / fy=-0.0033 (at object distance 400mm);

[0135] Among them, fy is the focal length of the liquid lens L1. The liquid lens L1 changes its own performance by changing the working voltage to achieve the change of focal length and finally achieve the purpose of focusing.

[0136] The liquid focusing lens of this embodiment satisfies the relationship:

[0137] f4 / f=0.68;

[0138] Wherein, f4 is the focal length of the combination of the third lens G3, the fourth lens G4 and the fifth lens G5.

[0139] The parameters of the liquid focusing lens of this embodiment are shown in Table 3.

[0140] Table 3

[0141] Focal length f 16mm Aperture value FNO 5.6 Half Image Height 4.8mm Total length 30mm wavelength Visible light

[0142] The shape, material, refractive index and Abbe number parameters of each lens in this embodiment are shown in Table 4.

[0143] Table 4

[0144]

[0145]

[0146] In Table 4, when the radius of curvature is Infinity, it indicates that the surface is a plane.

[0147] Figure 4 : This is a schematic diagram of the MTF of this embodiment, in which the OTF coefficient corresponding to the spatial frequency of the central field of view 145LP / mm is above 0.22, and the lens achieves high resolution characteristics.

[0148] The rest is the same as in Example 1.

[0149] Parts or structures not specifically described in the present invention may adopt existing technologies or existing products and will not be described in detail here.

[0150] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A liquid focusing lens, characterized in that: The invention comprises a first lens group, a second lens group and a third lens group which are arranged in sequence from the object side to the image side. The second lens group comprises a liquid lens. The focal length of the liquid lens is changed by changing the curvature of the liquid surface, thereby finally achieving the purpose of focusing.

2. The liquid focusing lens according to claim 1, characterized in that: The first lens group satisfies the relationship: -6 <f1 / f<-2; Wherein, f is the focal length of the liquid focusing lens, and f1 is the focal length of the first lens group.

3. The liquid focusing lens according to claim 1 or 2, characterized in that: The first lens group includes a first lens and a second lens arranged in sequence from the object side to the image side, and the first lens and the second lens meet the following conditions: Nd(G1)≥1.7; Nd(G2)≥1.7; Wherein, Nd(G1) is the refractive index of the first lens, and Nd(G2) is the refractive index of the second lens.

4. The liquid focusing lens according to claim 3, characterized in that: The first lens is a meniscus positive lens with a convex surface facing the object plane, and the second lens is a plano-concave negative lens with a concave surface facing the image plane.

5. The liquid focusing lens according to claim 3, characterized in that: The first lens is a plano-convex positive lens with the convex surface facing the object plane, and the second lens is a biconcave negative lens.

6. The liquid focusing lens according to claim 1, characterized in that: The liquid lens satisfies the relationship: -0.015<1 / fy<0.025; Where fy is the focal length of the liquid lens.

7. The liquid focusing lens according to claim 1, characterized in that: The liquid lens meets the following conditions: The length of the liquid lens from front to back, including the liquid lens itself, is ≥3.5 mm.

8. The liquid focusing lens according to claim 1, characterized in that: The third lens group comprises a third lens and a fourth lens arranged in sequence from the object side to the image side, the third lens is a biconvex positive refractive power lens, and the fourth lens is a biconcave negative refractive power lens; The third lens and the fourth lens meet the following conditions: Nd(G3)≥1.7; Nd(G4)≥1.7; Wherein, Nd(G3) is the refractive index of the third lens, and Nd(G4) is the refractive index of the fourth lens.

9. The liquid focusing lens according to claim 1, characterized in that: The third lens group comprises a third lens, a fourth lens and a fifth lens arranged in sequence from the object side to the image side, the third lens is a biconvex positive refractive power lens, and the fourth lens is a biconcave negative refractive power lens; The third lens, the fourth lens and the fifth lens meet the following conditions: Nd(G3)≥1.7; Nd(G4)≥1.7; Nd(G5)≥1.8; Wherein, Nd(G3) is the refractive index of the third lens, Nd(G4) is the refractive index of the fourth lens, and Nd(G5) is the refractive index of the fifth lens.

10. The liquid focusing lens according to claim 9, characterized in that: The liquid focusing lens satisfies the relationship: -1 <f4 / f<3; Wherein, f is the focal length of the liquid focusing lens, and f4 is the combined focal length of the third lens, the fourth lens and the fifth lens.

11. The liquid focusing lens according to claim 8 or 9, characterized in that: The third lens and the fourth lens are not glued together. At this time, the third lens and the fourth lens meet the following conditions: -20 <f2 / f<5; Wherein, f is the focal length of the liquid focusing lens, and f2 is the combined focal length of the third lens and the fourth lens.

12. The liquid focusing lens according to claim 8 or 9, characterized in that: The third lens and the fourth lens are glued together to form a first glued lens group, and the first glued lens group satisfies the relationship: -20 <f3 / f<5; Wherein, f is the focal length of the liquid focusing lens, and f3 is the focal length of the first cemented lens group.

13. The liquid focusing lens according to claim 9, characterized in that: The fifth lens is a biconvex positive refractive power lens.

14. The liquid focusing lens according to claim 9, characterized in that: The fifth lens is a plano-convex positive refractive power lens, with the convex surface facing the image plane.

15. The liquid focusing lens according to claim 1, characterized in that: An aperture is arranged between the second lens group and the third lens.

16. The liquid focusing lens according to claim 1, characterized in that: The focal length of the liquid focusing lens is f=16 mm, the aperture value FNO=5.6, the half image height is ≤4.8 mm, and the total length is within 30 mm.

17. An imaging device comprising the liquid focusing lens according to any one of claims 1 to 16, characterized in that: The imaging instrument is any one of a camera, a video camera, a microscope, a telescope, and an endoscope.

Images