Floating focusing lens and lens module

Abstract

The utility model discloses a floating focusing lens and a lens module. The system sequentially comprises a fixed lens group from an object side to an image side; a diaphragm; and the floating lens group has positive diopter and can move towards the direction close to the fixed lens group or away from the fixed lens group along the optical axis, and the range of the movement amount is 1.5-9.5 mm. According to the utility model, under different object distances of the lens, the floating lens group is moved in a floating focusing mode, so that high-definition images can be obtained at different object distances. The floating lens group enables the total length of the lens to remain unchanged during movement, the load is small, and the system performance is improved. The moving amount of the floating lens group ranges from 1.5 mm to 9.5 mm, and the object distance ranges from 0.1 m to infinity. Furthermore, after optimization of the inventor, in the interval, the object distance range can be guaranteed, and the length of the system can be controlled.

Description

Technical Field

[0001] The utility model relates to the technical field of floating focus lenses, in particular to a floating focus lens and a lens module. Background Art

[0002] The general design of the lens has the best aberration correction at the commonly used focusing distance, but aberration will occur at the shooting distance. The floating focus system can move a whole group of lenses according to the length of the lens extension, which can improve the image quality of close-up description. The floating focus system indicates that the performance of close-up focusing will be relatively better, so many lenses with macro functions use the floating focus system.

[0003] Existing floating focus lenses generally have the following problems:

[0004] 1. When industrial lenses work at different object distances, the commonly used focusing method is to move the entire lens closer to or away from the imaging surface. The disadvantages are heavy load, large differences in field curvature at different object distances, and uneven resolution.

[0005] 2. Industrial lenses have increasingly higher requirements on lens indicators, requiring the object deformation to be as small as possible. The distortion of conventional distortion-free lenses is between 1% and 3%.

[0006] 3. The target surface of industrial sensors is getting larger and larger, and the resolution of lenses is required to be higher and higher. Conventional lenses cannot meet the sensor requirements.

[0007] 4. Conventional industrial lenses have large chromatic aberration, low color reproduction, and are prone to purple fringing. Utility Model Content

[0008] In view of this, an object of the present invention is to provide a floating focus lens, which can solve at least one technical problem mentioned in the background technology.

[0009] According to one aspect of the utility model, a floating focus lens is provided, which comprises, from the object side to the image side, the following components:

[0010] Fixed mirror group;

[0011] Aperture;

[0012] The floating lens group has positive refractive power and can move along the optical axis toward a direction close to the fixed lens group or away from the fixed lens group, and the movement range is 1.5mm to 9.5mm.

[0013] In the above technical solution, in this embodiment, at different object distances of the lens, the floating lens group is moved in a floating focusing manner to achieve high-definition images at different object distances. The floating lens group keeps the total length of the lens unchanged during movement, with a small load and improved system performance. The movement range of the floating lens group is 1.5 - 9.5 mm, and the object distance range covers 0.1 m to infinity. Further, after optimization by the inventor, within this range, both the object distance range can be ensured and the length of the system can be controlled. Compared with the prior art, the advantages of this embodiment are a large target surface and extremely small distortion, with the distortion less than 0.2%; high resolution, high pixels, and uniform image quality in the central and peripheral fields of view; the chromatic aberration is within the diffraction limit, and the color restoration degree is high; 1.5 - 9.5 mm represents the movement amount of the lens from the near object distance to the far object distance, and the position of the aperture remains unchanged. Taking the aperture as a reference, when the object distance is 0.1 m, the distance between the aperture and the first lens of the floating group is 1.5 mm, and when the object distance is infinity, the distance between the aperture and the first lens of the floating group is 9.5 mm.

[0014] In some embodiments, the focal length range of the second lens in the direction from the object side to the image side of the fixed lens group is -12 mm to -18 mm.

[0015] In the above technical solution, in order to collect light and achieve a wide angle and a large target surface, the focal length of the second lens satisfies the relationship: -12 < f2 < -18.

[0016] In some embodiments, the focal length range of the first lens in the direction from the object side to the image side of the floating lens group is 25 mm to 35 mm.

[0017] In the above technical solution, the focal length of the first lens of the floating lens group satisfies the relationship: 25 < f5 < 35. The light is transmitted from the front group to the rear group, and the optical power is reasonably distributed to maintain high resolution during the floating process; if the optical power is too large, the light will be significantly refracted and the resolution will decrease; if the optical power is too small, the movement amount of the rear group will be too large, which is not conducive to stability.

[0018] In some embodiments, the fixed lens group sequentially includes, from the object side to the image side: a first lens, a second lens, a third lens, and a fourth lens;

[0019] Among them, the third lens and the fourth lens are mutually cemented into an achromatic cemented lens.

[0020] In the above technical solution, the third lens and the fourth lens are mutually cemented into an achromatic cemented lens, and high and low dispersion materials are combined to correct chromatic aberration.

[0021] In some embodiments, the fourth lens uses a glass material with a negative Dn / Dt.

[0022] In the above technical solution, the glass material of the fourth lens needs to satisfy the material with a negative relative refractive index temperature coefficient Dn / dt, which is used to correct temperature drift and achieve athermal design. Further, in this embodiment, the fourth lens is the preferred result. Compared with the material selection of other lenses, the overall performance improvement effect achieved by selecting this material for this lens is the best.

[0023] In some embodiments, the lens satisfies the following formula:

[0024] nd1>1.8

[0025] Wherein, nd1 is the refractive index of the first lens.

[0026] In the above technical solution, in order to achieve further miniaturization design, a high refractive index material is used, which can reduce the aperture on the one hand and improve the resolution on the other.

[0027] In some embodiments, the floating lens group includes, from the object side to the image side, a fifth lens, a sixth lens, a seventh lens, an eighth lens, a ninth lens, a tenth lens, and an eleventh lens;

[0028] The ninth lens and the tenth lens are cemented together to form an achromatic cemented lens.

[0029] In the above technical solution, the ninth lens and the tenth lens are glued together to form an achromatic glued lens, and high and low dispersion materials are combined to correct chromatic aberration.

[0030] In some embodiments, the ninth lens is made of a glass material with a negative Dn / Dt.

[0031] In the above technical solution, the glass material of the ninth lens needs to satisfy the material with a negative relative refractive index temperature coefficient Dn / dt, which is used to correct temperature drift and realize athermal design. Further, in this embodiment, the ninth lens is the preferred result. Compared with the material selection of other lenses (except the fourth lens), the overall performance improvement effect achieved by selecting this material for this lens is the best.

[0032] In some embodiments, the lens satisfies the following formula:

[0033] -30mm <f 11 <-50mm

[0034] In the formula, f 11 is the focal length of the eleventh lens.

[0035] In the above technical solution, in order to further improve the lens resolution, the focal length of the eleventh lens satisfies the relationship: -30 <f 11 <-50, improve resolution and optimize chromatic aberration by properly distributing optical focal length.

[0036] According to another aspect of the utility model, a lens module is provided, comprising the above-mentioned floating focus lens. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0038] Figure 1 This is a schematic diagram of the lens structure of one embodiment of the floating focus lens of the utility model;

[0039] Figure 2 This is a lens optical path diagram of one embodiment of the floating focus lens of the utility model;

[0040] Figure 3 It is a distortion curve diagram of one embodiment of the floating focus lens of the utility model;

[0041] Figure 4 This is an MTF curve diagram of one embodiment of the floating focus lens of the utility model;

[0042] Figure 5 It is a chromatic aberration curve diagram of one embodiment of the floating focus lens of the utility model;

[0043] Figure 6 This is a schematic diagram of the lens structure of the second embodiment of the floating focus lens of the utility model;

[0044] Figure 7 This is a lens optical path diagram of the second embodiment of the floating focus lens of the utility model;

[0045] Figure 8 This is a distortion curve diagram of the second embodiment of the floating focus lens of the utility model;

[0046] Fig. 9 This is an MTF curve diagram of the second embodiment of the floating focus lens of the utility model;

[0047] Fig.10 This is a chromatic aberration curve diagram of the second embodiment of the floating focus lens of the utility model;

[0048] Fig.11 This is a schematic diagram of the lens structure of the third embodiment of the floating focus lens of the utility model;

[0049] Fig.12 This is a lens optical path diagram of the third embodiment of the floating focus lens of the utility model;

[0050] Fig.13 This is a distortion curve diagram of the third embodiment of the floating focus lens of the utility model;

[0051] Fig.14 This is an MTF curve diagram of the third embodiment of the floating focus lens of the utility model;

[0052] Fig.15 This is a chromatic aberration curve diagram of the third embodiment of the floating focus lens of the utility model. DETAILED DESCRIPTION

[0053] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It is particularly noted that the following embodiments are only used to illustrate the present invention, but do not limit the scope of the present invention. Similarly, the following embodiments are only partial embodiments of the present invention rather than all embodiments. All other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0054] The utility model provides a floating focus lens, which can solve at least one technical problem mentioned in the background technology.

[0055] Embodiment 1

[0056] See also Figure 1 , Figure 2 , an optical imaging lens that can be used for wide working distance industrial inspection. There are 11 lenses in total, from the object side OBJ to the image side IMA, they are the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the aperture ST, the fifth lens L5, the sixth lens L6, the seventh lens L7, the eighth lens L8, the ninth lens L9, the tenth lens L10, and the eleventh lens L11.

[0057] The first lens L1, the second lens L2, the third lens L3, and the fourth lens L4 are fixed lens groups. When the object distance changes, the fixed lens group remains stationary. In this embodiment, the focal length of the fixed group is 60.8 mm. The fifth lens L5, the sixth lens L6, the seventh lens L7, the eighth lens L8, the ninth lens L9, the tenth lens L10, and the eleventh lens L11 are floating lens groups. When the object distance changes, the floating lens group moves forward and backward. When the object distance becomes smaller, the floating lens group moves toward the object side; when the object distance becomes larger, the floating lens group moves toward the image side.

[0058] The first lens L1 has positive refractive power, the object side surface 1 is convex, and the image side surface 2 is concave. The second lens L2 has negative refractive power, the object side surface 3 is concave, and the image side surface 4 is concave. The object side surface 5 of the third lens L3 is convex, and the image side surface 6 is concave. The fourth lens L4 has positive refractive power, the object side surface 6 is convex, and the image side surface 7 is convex. The fifth lens L5 has positive refractive power, the object side surface 9, and the image side surface 10. The sixth lens L6 has positive refractive power, the object side surface 11 is convex, and the image side surface 12 is concave. The seventh lens L7 has negative refractive power, the object side surface 13, and the image side surface 14. The eighth lens L8 has positive refractive power, the object side surface 14, and the image side surface 15. The ninth lens L9 has positive refractive power, the object side surface 16, and the image side surface 17. The tenth lens L10 has negative refractive power, the object side surface 17, and the image side surface 18. The eleventh lens L11 has negative refractive power, an object-side surface 19 is concave, and an image-side surface 20 is convex.

[0059] Table 1 Lens related parameters of Example 1

[0060] Face number Type radius thickness Refractive Index Abbe number focal length 1 First lens Glass 32.80 2.65 1.83 37.20 120.90 2 47.00 9.60 3 Second lens Glass -19.80 3.20 1.56 42.80 -13.86 4 13.72 2.70 5 The third lens Glass 22.11 4.15 1.61 44.10 -835.40 6 The fourth lens Glass 19.67 4.04 1.61 63.40 15.80 7 -17.78 1.24 8 Aperture Infinity 5.23 9 Fifth lens Glass 13.16 4.41 1.49 81.50 28.60 10 160.30 0.14 11 The sixth lens Glass 15.23 2.93 1.75 52.30 55.60 12 21.97 0.67 13 Seventh lens Glass -466.24 0.96 1.62 36.30 -31.80 14 The eighth lens Glass 20.55 1.31 1.83 42.70 26.40 15 10.31 1.31 16 The ninth lens Glass 233.76 3.00 1.59 68.50 13.13 17 Tenth lens Glass -8.00 3.90 1.83 42.70 -54.98 18 -11.85 0.55 19 Eleventh lens Glass -9.00 1.13 1.61 53.90 -47.70 20 -14.50 4.84 21 Protective glass Glass Infinity 0.50 1.51 64.20 22 IMA Infinity 7.90

[0061] Figure 3 It is the distortion curve of the optical system. From the figure, it can be seen that the distortion of the optical system at full image height is less than 0.2%, which meets the characteristics of large target surface and extremely small distortion, and the object image is not deformed. Figure 4 This is the MTF curve of the optical system. The center and edge MTF are uniform, 200lp / mm is greater than 0.3 contrast, high resolution, high pixels, and the ability to resolve details. Figure 5 This is a chromatic aberration curve. The chromatic aberration value is less than 2um. The chromatic aberration is within the diffraction limit, and the color reproduction is high.

[0062] Embodiment 2

[0063] See also Figure 6 , Figure 7 The difference between this embodiment and the previous embodiment lies in the different lens parameters. Please refer to Table 2 for details.

[0064] Table 2 Lens related parameters of Example 2

[0065] Face number Type radius thickness Refractive Index Abbe number focal length 1 First lens Glass 35.49 2.10 1.83 37.20 83.30 2 70.92 8.05 3 Second lens Glass -19.80 1.85 1.56 42.80 -14.40 4 14.27 2.04 5 The third lens Glass 20.80 4.90 1.61 44.10 1440.70 6 The fourth lens Glass 19.43 4.80 1.61 63.40 16.00 7 -18.22 1.20 8 Aperture Infinity 4.90 9 Fifth lens Glass 18.49 3.30 1.46 90.30 32.90 10 -131.37 0.10 11 The sixth lens Glass 23.21 2.20 1.75 52.30 104.00 12 31.62 1.03 13 Seventh lens Glass -38.28 1.86 1.62 36.30 -10.60 14 The eighth lens Glass 8.05 3.05 1.91 35.20 19.30 15 12.23 0.86 16 The ninth lens Glass 66.99 2.93 1.59 68.50 15.70 17 Tenth lens Glass -10.60 4.23 1.83 42.70 -376.00 18 -12.96 1.98 19 Eleventh lens Glass -8.90 1.44 1.61 53.90 -37.50 20 -15.38 1.79 21 Protective glass Glass Infinity 0.50 1.51 64.20 22 IMA Infinity 8.29

[0066] Figure 8 It is the distortion curve of the optical system. From the figure, it can be seen that the distortion of the optical system at full image height is less than 0.2%, which meets the characteristics of large target surface and extremely small distortion, and the object image is not deformed. Fig. 9 This is the MTF curve of the optical system. The center and edge MTF are uniform, 200lp / mm is greater than 0.3 contrast, high resolution, high pixels, and the ability to resolve details. Fig.10 This is a chromatic aberration curve. The chromatic aberration value is less than 2um. The chromatic aberration is within the diffraction limit, and the color reproduction is high.

[0067] Embodiment 3

[0068] See also Fig.11 , Fig.12 The difference between this embodiment and the above two embodiments is that the lens parameters are different, please refer to Table 3 for details.

[0069] Table 3 Parameters of the three lenses in the embodiment

[0070] Face number Type radius thickness Refractive Index Abbe number Diopter 1 First lens Glass 27.80 2.20 1.91 35.25 83.60 2 42.30 3.35 3 Second lens Glass -24.05 4.38 1.56 42.80 -16.00 4 15.54 1.49 5 The third lens Glass 19.57 5.18 1.61 44.16 109.00 6 The fourth lens Glass 24.84 4.70 1.61 63.40 19.70 7 -22.04 1.20 8 Aperture Infinity 5.13 9 Fifth lens Glass 17.62 2.42 1.49 81.59 30.25 10 -96.50 0.09 11 The sixth lens Glass 18.30 2.00 1.75 52.33 62.00 12 28.66 0.86 13 Seventh lens Glass -70.66 0.60 1.62 36.34 -11.00 14 The eighth lens Glass 7.54 2.90 1.91 35.25 20.97 15 10.14 1.11 16 The ninth lens Glass 935.25 2.55 1.59 68.52 14.70 17 Tenth lens Glass -8.77 5.20 1.91 35.25 -87.40 18 -12.63 2.45 19 Eleventh lens Glass -9.09 1.70 1.61 53.92 -42.30 20 -15.00 1.63 21 Protective glass Glass Infinity 0.50 1.51 64.21 22 IMA Infinity 8.15

[0071] Fig.13 It is the distortion curve of the optical system. From the figure, it can be seen that the distortion of the optical system at full image height is less than 0.2%, which meets the characteristics of large target surface and extremely small distortion, and the object image is not deformed. Fig.14 This is the MTF curve of the optical system. The center and edge MTF are uniform, 200lp / mm is greater than 0.3 contrast, high resolution, high pixels, and the ability to resolve details. Fig.15 This is a chromatic aberration curve. The chromatic aberration value is less than 2um. The chromatic aberration is within the diffraction limit, and the color reproduction is high.

[0072] The above descriptions are only some embodiments of the present invention, and do not limit the protection scope of the present invention. Any equivalent device or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A floating focus lens, characterized in that: From the object side to the image side, they include: Fixed mirror group; Aperture; The floating lens group has positive refractive power and can move along the optical axis toward a direction close to the fixed lens group or away from the fixed lens group, and the movement range is 1.5mm to 9.5mm.

2. A floating focus lens as claimed in claim 1, characterized in that: The focal length range of the second lens of the fixed lens group from the object side to the image side is -12mm to -18mm.

3. The floating focus lens according to claim 1, characterized in that: The focal length range of the first lens of the floating lens group from the object side to the image side is 25mm to 35mm.

4. A floating focus lens as claimed in claim 1 or 2, characterized in that: The fixed lens group includes, from the object side to the image side, a first lens, a second lens, a third lens, and a fourth lens; The third lens and the fourth lens are glued together to form an achromatic glued lens.

5. The floating focus lens according to claim 4, characterized in that: The fourth lens is made of glass material with a negative Dn / Dt value.

6. The floating focus lens according to claim 4, characterized in that: The lens satisfies the following formula: nd1>1.8 Wherein, nd1 is the refractive index of the first lens.

7. A floating focus lens as claimed in claim 1 or 3, characterized in that: The floating lens group includes, from the object side to the image side, a fifth lens, a sixth lens, a seventh lens, an eighth lens, a ninth lens, a tenth lens, and an eleventh lens; The ninth lens and the tenth lens are cemented together to form an achromatic cemented lens.

8. The floating focus lens according to claim 7, characterized in that: The ninth lens is made of glass material with a negative Dn / Dt value.

9. The floating focus lens according to claim 7, characterized in that: The lens satisfies the following formula: -30mm<f 11 <-50mm In the formula, f 11 is the focal length of the eleventh lens.

10. A lens module, characterized in that: A floating focus lens comprising any one of claims 1-9.

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