Prime lens

Abstract

The prime lens comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, a ninth lens and a tenth lens which are sequentially arranged from an object plane to an image plane along an optical axis, the prime lens further comprises a first lens group with positive focal power, a second lens group with negative focal power and a third lens group with positive focal power; the first lens group comprises a first lens with positive focal power, a second lens with positive focal power, a third lens with negative focal power and a fourth lens with positive focal power; the second lens group comprises a fifth lens with negative focal power; and the third lens group comprises a sixth lens with negative focal power, a seventh lens with positive focal power, an eighth lens with negative focal power, a ninth lens with positive focal power and a tenth lens with negative focal power. By adopting the technical scheme, the imaging effect of the prime lens can be ensured by setting the focal power and the composition mode of the lens group and the focal power of each lens.

Description

Technical Field

[0001] The embodiment of the utility model relates to the technical field of optical devices, and in particular to a fixed-focus lens. Background Art

[0002] With the development of photography technology and the upgrading of camera technology, mirrorless cameras have been favored by more consumers due to their light weight, easy operation and high image quality.

[0003] Therefore, the research on micro-single lenses has become a hot topic. Utility Model Content

[0004] The utility model provides a fixed-focus lens, which realizes a micro single lens with good imaging effect by reasonably setting the composition mode of the lens and the focal length distribution mode of the lens.

[0005] The embodiment of the utility model provides a fixed-focus lens, comprising a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, a ninth lens and a tenth lens arranged in sequence from an object plane to an image plane along an optical axis;

[0006] The fixed-focus lens further includes a first lens group, a second lens group and a third lens group; the first lens group is a positive power lens group and includes the first lens, the second lens, the third lens and the fourth lens; the second lens group is a negative power lens group and includes the fifth lens; the third lens group is a positive power lens group and includes the sixth lens, the seventh lens, the eighth lens, the ninth lens and the tenth lens;

[0007] Among them, the first lens is a positive power lens, the second lens is a positive power lens, the third lens is a negative power lens, the fourth lens is a positive power lens, the fifth lens is a negative power lens, the sixth lens is a negative power lens, the seventh lens is a positive power lens, the eighth lens is a negative power lens, the ninth lens is a positive power lens, and the tenth lens is a negative power lens.

[0008] Optionally, the maximum semi-aperture of the first lens is SD1, the distance between the object side surface of the first lens and the image side surface of the fourth lens is T14, and the distance between the object side surface of the second lens and the image side surface of the fourth lens is T24;

[0009] Among them, 21≤SD1≤25.1; 0.7≤T24 / T14≤0.8.

[0010] Optionally, the focal power of the first lens is Φ1, and the focal power of the first lens group is Φ14;

[0011] Among them, 0.6≤Φ1 / Φ14≤0.8.

[0012] Optionally, the Abbe number of the second lens is Vd2;

[0013] Among them, Vd2≥80.

[0014] Optionally, the semi-aperture of the object-side surface of the fifth lens is SD5, and the radius of curvature of the object-side surface of the fifth lens is R5;

[0015] Among them, -0.13≤SD5 / R5≤-0.03.

[0016] Optionally, the focal power of the first lens group is Φ14, and the focal power of the third lens group is Φ610;

[0017] Among them, 0.75≤Φ610 / Φ14≤0.9.

[0018] Optionally, the second lens is glued to the third lens;

[0019] The sixth lens is glued to the seventh lens;

[0020] The eighth lens is cemented to the ninth lens.

[0021] Optionally, the image side surface radius of the seventh lens is R7, and the object side surface radius of the eighth lens is R8;

[0022] Among them, 1≤R7 / R8≤1.4.

[0023] Optionally, the air interval between the ninth lens and the tenth lens is G910, and the total optical length of the fixed-focus lens is TTL;

[0024] Among them, 0.1≤G910 / TTL≤0.15.

[0025] Optionally, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, the ninth lens and the tenth lens are all spherical lenses.

[0026] The fixed-focus lens provided by the embodiment of the utility model includes three lens groups by setting the fixed-focus lens. The first lens group is a positive optical focal length lens group, which can collect light with a large aperture of the lens, effectively control the length and aperture of the lens, and is conducive to a small and lightweight design; the second lens group is a negative optical focal length lens group and a focusing lens group, and the second lens group includes only one lens, so that the second lens group can be light in weight and more convenient to focus; when applied to automatic focusing, the focusing error can be reduced and the focusing sensitivity can be improved; the third lens group is a positive optical focal length lens group, which can achieve full-frame target surface imaging and smaller field curvature distortion. Further, by setting the first lens group to include a first lens with positive optical power, a second lens with positive optical power, a third lens with negative optical power and a fourth lens with positive optical power, the second lens group to include a fifth lens with negative optical power, the third lens group to include a sixth lens with negative optical power, a seventh lens with positive optical power, an eighth lens with negative optical power, a ninth lens with positive optical power and a tenth lens with negative optical power, and by reasonably setting the composition of the lenses in each lens group and the optical power of each lens to meet the optical power setting method of each lens group, the imaging effect of the fixed-focus lens is guaranteed.

[0027] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present utility model, nor are they intended to limit the scope of the present utility model. Other features of the present utility model will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 This is a schematic structural diagram of a fixed-focus lens corresponding to an infinite object distance provided by the first embodiment of the utility model;

[0030] Figure 2 This is a schematic diagram of the MTF of a fixed-focus lens corresponding to an infinite object distance provided in the first embodiment of the present utility model;

[0031] Figure 3 This is a schematic diagram of field curvature distortion of a fixed-focus lens corresponding to an infinite object distance provided by the first embodiment of the utility model;

[0032] Figure 4 It is a schematic diagram of a vertical axis chromatic aberration curve of a fixed-focus lens corresponding to an infinite object distance provided in the first embodiment of the utility model;

[0033] Figure 5 This is a schematic structural diagram of a fixed-focus lens corresponding to an infinite object distance provided by Embodiment 2 of the present utility model;

[0034] Figure 6 This is a schematic diagram of the MTF of a fixed-focus lens corresponding to an infinite object distance provided in the second embodiment of the present utility model;

[0035] Figure 7 This is a schematic diagram of field curvature distortion of a fixed-focus lens corresponding to an infinite object distance provided by Embodiment 2 of the present utility model;

[0036] Figure 8 This is a schematic diagram of a vertical axis chromatic aberration curve of a fixed-focus lens corresponding to an infinite object distance provided in the second embodiment of the present utility model;

[0037] Fig. 9 This is a schematic structural diagram of a fixed-focus lens corresponding to an infinite object distance provided by Embodiment 3 of the present utility model;

[0038] Fig.10 This is a schematic diagram of the MTF of a fixed-focus lens corresponding to an infinite object distance provided in the third embodiment of the present utility model;

[0039] Fig.11 This is a schematic diagram of field curvature distortion of a fixed-focus lens corresponding to an infinite object distance provided by Embodiment 3 of the present utility model;

[0040] Fig.12 It is a schematic diagram of a vertical axis chromatic aberration curve of a fixed-focus lens corresponding to an infinite object distance provided by Embodiment 3 of the present utility model. DETAILED DESCRIPTION

[0041] In order to enable those skilled in the art to better understand the solution of the utility model, the technical solution in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiment of the utility model. Obviously, the described embodiment is only a part of the embodiment of the utility model, not all of the embodiments. Based on the embodiment of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the utility model.

[0042] Embodiment 1

[0043] Figure 1 : is a schematic diagram of the structure of a fixed-focus lens corresponding to an infinite object distance provided by the first embodiment of the utility model, such as Figure 1As shown, the fixed-focus lens provided in Embodiment 1 of the present invention comprises a first lens 101, a second lens 102, a third lens 103, a fourth lens 104, a fifth lens 105, a sixth lens 106, a seventh lens 107, an eighth lens 108, a ninth lens 109 and a tenth lens 110 which are arranged in sequence along the optical axis from the object plane to the image plane; the fixed-focus lens also comprises a first lens group S1, a second lens group S2 and a third lens group S3; the first lens group S1 is a positive focal power lens group and comprises the first lens 101, the second lens 102, the third lens 103 and the fourth lens 104; the second lens group S2 is a negative focal power lens group and comprises the fifth lens 105, the sixth lens 106, the seventh lens 107, the eighth lens 108, the ninth lens 109 and the tenth lens 110; The third lens group S3 is a positive power lens group and includes a sixth lens 106, a seventh lens 107, an eighth lens 108, a ninth lens 109 and a tenth lens 110; wherein the first lens 101 is a positive power lens, the second lens 102 is a positive power lens, the third lens 103 is a negative power lens, the fourth lens 104 is a positive power lens, the fifth lens 105 is a negative power lens, the sixth lens 106 is a negative power lens, the seventh lens 107 is a positive power lens, the eighth lens 108 is a negative power lens, the ninth lens 109 is a positive power lens, and the tenth lens 110 is a negative power lens.

[0044] Specifically, the fixed-focus lens provided in the embodiment of the utility model includes a first lens group S1, a second lens group S2 and a third lens group S3, the first lens group S1 further includes a first lens 110, a second lens 120, a third lens 130 and a fourth lens 140, the second lens group S2 further includes a fifth lens 105, and the third lens group S3 further includes a sixth lens 106, a seventh lens 107, an eighth lens 108, a ninth lens 109 and a tenth lens 110.

[0045] Furthermore, the focal length is equal to the difference between the convergence of the image-side light beam and the convergence of the object-side light beam, and it characterizes the ability of the optical system to deflect light. The larger the absolute value of the focal length, the stronger the ability to bend light, and the smaller the absolute value of the focal length, the weaker the ability to bend light. When the focal length is a positive number, the refraction of light is convergent; when the focal length is a negative number, the refraction of light is divergent. The focal length can be used to characterize a certain refractive surface of a lens (i.e., a surface of a lens), can be used to characterize a certain lens, and can also be used to characterize a system formed by multiple lenses (i.e., a lens group).

[0046] In the embodiment of the utility model, the first lens group S1 is set as a positive focal lens group. The first lens group S1 with positive focal length can collect light for the large aperture light of the fixed focus lens, effectively control the length and caliber of the fixed focus lens, and is conducive to a small and lightweight design. Further, the first lens group S1 includes a first lens 101 with positive focal length, a second lens 102 with positive focal length, a third lens 103 with negative focal length, and a fourth lens 104 with positive focal length. The focal length combination of the four lenses can ensure the realization of the first lens group S1 with positive focal length. In addition, the first lens 101 and the second lens 102 are both set as positive focal length lenses. The first lens 101 and the second lens 102 can play a role in converging light to ensure that as much light incident on the lens is collected as possible, which is conducive to improving the illumination of the lens. The third lens 103 is set as a negative focal length lens. The third lens 103 can effectively deflect the light incident thereon, thereby effectively increasing the field of view of the fixed focus lens. In addition, the third lens 103 is set as a negative power lens, which can also reduce the angle at which the edge light enters the aperture and balance part of the vertical axis aberration. The fourth lens 104 is set as a positive power lens, so that the fourth lens 104 can timely correct the large aberration generated by the third lens 103, which can ensure the aberration balance and high and low temperature performance stability of the lens while eliminating the high-order aberration of the lens as much as possible, and at the same time can control the target surface (size) and improve the image quality of the lens to meet the use requirements in more situations.

[0047] On this basis, the second lens group S2 is set as a negative power lens group, and the second lens group S2 is used as a focus lens group, which can be moved along the optical axis direction to achieve different aperture shooting and depth of field adjustment, while ensuring uniform and stable image quality within a longer shooting range. Further, the second lens group S2 includes a fifth lens 105 with negative power, and only includes this lens, so as to ensure that the focus lens group is light in weight and more convenient to focus. When applied to automatic focus, it can reduce focus error and improve focus sensitivity.

[0048] On this basis, the third lens group S3 is set as a positive power lens group, which can achieve full-frame target surface imaging and small field curvature distortion. Further, the third lens group S3 includes a sixth lens 106 with negative power, a seventh lens 107 with positive power, an eighth lens 108 with negative power, a ninth lens 109 with positive power, and a tenth lens 110 with negative power. The power combination of the five lenses can ensure the realization of the third lens group S3 with positive power.

[0049] In summary, the fixed-focus lens provided in the embodiment of the utility model can collect light from the large aperture of the lens by setting the first lens group as a positive focal length lens group, effectively control the length and diameter of the lens, and is conducive to a small and lightweight design. The second lens group is set as a negative focal length lens group and a focusing lens group, and the second lens group includes only one lens, so that the second lens group can be light in weight and more convenient when focusing; when applied to automatic focusing, it can reduce focusing errors and improve focusing sensitivity. Setting the third lens group as a positive focal length lens group can achieve full-frame target imaging and smaller field curvature distortion.

[0050] Continue to refer Figure 1 As shown, the fixed-focus lens provided by the embodiment of the utility model may also include an aperture 111 and a filter 112; the aperture 111 is arranged in the optical path between the fifth lens 105 and the sixth lens 106; the filter 112 is arranged in the optical path between the tenth lens 110 and the image plane. By setting the aperture 111, the propagation direction of the light beam can be adjusted, which is beneficial to improving the imaging quality. And the aperture 111 in the fixed-focus lens can be located in the optical path between the fifth lens 105 and the sixth lens 106, and the aperture 111 is located in the middle of the fixed-focus lens to ensure that the front and rear apertures of the fixed-focus lens are minimized. Further, the filter 112 is arranged in the optical path between the tenth lens 110 and the image plane, and the filter 112 can filter out stray spectra to ensure imaging quality. Further, the fixed-focus lens may also include flat glass to protect the lens and the image sensor.

[0051] As a feasible implementation, the maximum semi-aperture of the first lens 101 is SD1, the distance between the object side surface of the first lens 101 and the image side surface of the fourth lens 104 is T14, and the distance between the object side surface of the second lens 102 and the image side surface of the fourth lens 104 is T24; wherein, 21≤SD1≤25.1; 0.7≤T24 / T14≤0.8. By adopting the above parameter definition, by making the structure of the first lens group S1 compact, a smaller volume of the fixed focus lens can be achieved, and the aperture and the total length can be reduced at the same time.

[0052] As a feasible implementation, the focal power of the first lens 101 is Φ1, and the focal power of the first lens group S1 is Φ14; wherein 0.6≤Φ1 / Φ14≤0.8. The above parameter definition facilitates the object field light to enter the fixed focus lens through the first lens 101, and the second lens 102, the third lens 103 and the fourth lens 104 can jointly correct the spherical aberration.

[0053] As a feasible implementation, the Abbe number of the second lens 102 is Vd2; wherein Vd2≥80.

[0054] Specifically, the Abbe number is an index used to indicate the dispersion ability of a transparent medium. The more severe the dispersion of the medium, the smaller the Abbe number; conversely, the less the dispersion of the medium, the larger the Abbe number. That is, the second lens 102 is set to be a lens with a high Abbe number and low dispersion, ensuring that the second lens 102 has a good correction effect on axial chromatic aberration and can reduce the purple fringing phenomenon.

[0055] As a feasible implementation manner, the semi-aperture of the object-side surface of the fifth lens 105 is SD5, and the radius of curvature of the object-side surface of the fifth lens 105 is R5; wherein, -0.13≤SD5 / R5≤-0.03.

[0056] Specifically, the object side surface of the lens can be understood as the surface of the lens close to the object plane. Since the fifth lens 105 is used as a focusing lens, the above parameter limitation can ensure that when the light at the same pupil corresponds to lens surfaces of different apertures during the movement and focusing of the fifth lens 105, the change amplitude of the emitted light is small, thereby ensuring the focusing effect.

[0057] As a feasible implementation, the focal power of the first lens group S1 is Φ14, and the focal power of the third lens group S3 is Φ610; wherein 0.75≤Φ610 / Φ14≤0.9. Since the first lens group S1 is located in the optical path before the aperture 111, and the third lens group S3 is located in the optical path after the aperture 111, the distortion can be balanced by limiting the focal power of each lens group before and after the aperture 111. The distortion here can be understood as the distortion of the optical system, that is, the sum of the distortions produced by all lenses.

[0058] As a feasible implementation manner, the second lens 102 is glued to the third lens 103 ; the sixth lens 106 is glued to the seventh lens 107 ; the eighth lens 108 is glued to the ninth lens 109 .

[0059] Specifically, the second lens 102 and the third lens 103 are bonded together, which can be understood as the side surface of the second lens 102 close to the image side is bonded together with the side surface of the third lens 103 close to the object plane, that is, the image side surface of the second lens 102 is bonded together with the object side surface of the third lens 103. The sixth lens 106 and the seventh lens 107 are bonded together, which can be understood as the side surface of the sixth lens 106 close to the image side is bonded together with the side surface of the seventh lens 107 close to the object plane, that is, the image side surface of the sixth lens 106 is bonded together with the object side surface of the seventh lens 107. The eighth lens 108 and the ninth lens 109 are bonded together, which can be understood as the side surface of the eighth lens 108 close to the image side is bonded together with the side surface of the ninth lens 109 close to the object plane, that is, the image side surface of the eighth lens 108 is bonded together with the object side surface of the ninth lens 109. By arranging the second lens 102 and the third lens 103 to be glued together, the air gap between the second lens 102 and the third lens 103 can be reduced; the sixth lens 106 and the seventh lens 107 are glued together to reduce the air gap between the sixth lens 106 and the seventh lens 107; the eighth lens 108 and the ninth lens 109 are glued together to reduce the air gap between the eighth lens 108 and the ninth lens 109, which helps to reduce the total optical length of the lens, and can also reduce the tolerance sensitivity problems such as tilt / eccentricity generated by the lens unit during the assembly process, simplify the assembly procedure during the lens manufacturing process, and improve equipment efficiency. At the same time, the second lens 102 and the third lens 103 are glued together, the sixth lens 106 and the seventh lens 107 are glued together, and the eighth lens 108 and the ninth lens 109 are glued together, which can also reduce the light loss caused by reflection between lenses, improve illumination, and reduce the risk of ghosting; and the glued lens can be used to minimize or eliminate chromatic aberration. The use of glued lenses in fixed-focus lenses can improve image quality and reduce the reflection loss of light energy, thereby improving image quality and improving the clarity of lens imaging. Further, the second lens 102 and the third lens 103 can be supported by a gasket, or can be glued by glue, the sixth lens 106 and the seventh lens 107 can be supported by a gasket, or can be glued by glue, and the eighth lens 108 and the ninth lens 109 can be supported by a gasket, or can be glued by glue. The utility model does not limit the specific gluing method.

[0060] As a feasible implementation, the image side curvature radius of the seventh lens 107 is R7, and the object side curvature radius of the eighth lens 108 is R8; wherein 1≤R7 / R8≤1.4. The larger the off-axis field angle, the longer the optical path will be for the same horizontal distance, and 1≤R7 / R8 is satisfied, so that the optical paths of each field tend to remain consistent. By ensuring that R7 / R8≤1.4, light can enter the lens at a gentler angle to avoid increasing spherical aberration and reducing the resolution of the central field of view.

[0061] As a feasible implementation, the air gap between the ninth lens 109 and the tenth lens 110 is G910, and the total optical length of the fixed focus lens is TTL; wherein 0.1≤G910 / TTL≤0.15. The above parameter limitation combined with the setting of the tenth lens 110 as a negative optical power lens can further correct the Petzvan field curvature.

[0062] As a feasible implementation, the first lens 101 , the second lens 102 , the third lens 103 , the fourth lens 104 , the fifth lens 105 , the sixth lens 106 , the seventh lens 107 , the eighth lens 108 , the ninth lens 109 and the tenth lens 110 are all glass spherical lenses.

[0063] Specifically, the characteristic of the spherical lens is that it has a constant curvature from the center of the lens to the periphery of the lens, which ensures that the lens is set in a simple manner. Furthermore, since the thermal expansion coefficient of glass lenses is small and the stability is good, the spherical lens can be set as a glass spherical lens. The thermal properties of glass spherical lenses are more stable. When assuming more optical power, it can ensure that the lens has good resolution in a wider temperature range (-40℃~80℃). In addition, compared with plastic aspherical lenses, the range of glass materials available is wider, and the refractive index and Abbe number are relatively free to choose. To a certain extent, the high-level aberrations and chromatic aberrations of the lens can be controlled to meet the use requirements under complex conditions.

[0064] As a feasible implementation method, specific parameters of the fixed-focus lens are described below.

[0065] Table 1 Optical design values ​​of the fixed focus lens in Example 1

[0066] Scope of protection Example 1 Lower limit Upper limit SD1 23.07 21 25.1 T24 / T14 0.7757 0.7 0.8 Φ1 / Φ14 0.6294 0.6 0.8 Vd2 90 80 100 SD5 / R5 -0.094 -0.13 -0.03 Φ610 / Φ14 0.7964 0.75 0.9 R7 / R8 1.260 1 1.4 G910 / TTL 0.1334 0.1 0.15

[0067] Table 2 Design values ​​of optical physical parameters of a fixed-focus lens

[0068]

[0069] The surface numbers in Table 2 are numbered according to the order of the surfaces of each lens. "2" represents the object surface of the first lens, "3" represents the image surface of the first lens, and so on. "STP" represents the aperture of the lens; the radius of curvature represents the curvature of the lens surface, a positive value represents that the surface is bent toward the image side, and a negative value represents that the surface is bent toward the object side; "infinity" represents that the surface is a plane and the radius of curvature is infinite; the thickness represents the central axial distance from the current surface to the next surface, the refractive index represents the ability of the material between the current surface and the next surface to deflect light, and the space represents that the current position is air with a refractive index of 1; the Abbe number represents the dispersion characteristics of the material between the current surface and the next surface to light. The semi-aperture represents half of the aperture size of the current surface.

[0070] Furthermore, Figure 2 This is a schematic diagram of the MTF of a fixed-focus lens corresponding to an infinite object distance provided in Example 1 of the utility model. The MTF diagram is one of the most commonly used and authoritative evaluation methods in modern optical design. The horizontal axis is the spatial frequency of the line pairs in the object space being imaged on the image plane through the optical system, and the unit is cycle / mm, and the vertical axis is the modulus of the optical transfer function. Curves of different colors represent the changing trends of the optical transfer functions of the images in the meridian (T as shown in the figure) and sagittal (S as shown in the figure) directions corresponding to different fields of view (0.00mm, 6.48mm, 10.8mm, 15.20mm, 19.44mm and 21.60mm as shown in the figure) with the increase of spatial frequency. The most ideal curve is a straight line that coincides with the diffraction limit of the system, indicating that the geometric aberrations of the light at all positions are smaller than the wave phase difference caused by the physical limitations of the system itself, and can be ignored. By Figure 2 It can be seen that the optical transfer function of the system is relatively high at 30lp / mm in each field of view, and the trend changes are soft and smooth, which shows that the optical system can achieve the imaging requirements of high resolution and uniform image quality.

[0071] Figure 3 : is a schematic diagram of field curvature distortion of a fixed-focus lens corresponding to an infinite object distance provided by the first embodiment of the present invention. In the left coordinate system of the figure, the horizontal coordinate represents the magnitude of the field curvature, and the unit is mm; the vertical coordinate represents the normalized image height, and there is no unit; T represents the meridian, and S represents the sagittal; Figure 3 It can be seen that the field curvature of the lens provided in this embodiment is effectively controlled, that is, when imaging, the difference between the image quality at the center and the image quality at the periphery is small. In the coordinate system on the right, the horizontal coordinate represents the magnitude of the distortion, in units of %; the vertical coordinate represents the normalized image height, in units of %. Figure 3 It can be seen that the maximum distortion of the lens provided in this embodiment is controlled within 2%, the distortion is well corrected, and the imaging distortion is small.

[0072] Figure 4 This is a schematic diagram of the vertical chromatic aberration curve of a fixed-focus lens corresponding to an infinite object distance provided in Example 1 of the utility model. The horizontal axis is the vertical axis distance of other wavelengths of light on the image plane from the main wavelength of light, and the vertical axis is the field of view. The curve describes the vertical chromatic aberration of light of different fields of view and different wavelengths (blue represents 486.1nm, green represents 587.6nm, and red represents 656.3nm) on the image plane. The most ideal curve is that all wavelengths of light are within the radius of the Airy disk, indicating that the vertical chromatic aberration of light in all fields of view is smaller than the wave phase difference caused by the physical limitations of the system itself. Figure 4 It can be seen that the vertical axis chromatic aberration of the lens provided in this embodiment is effectively controlled, that is, when imaging, it is unlikely to cause streaking, purple fringing, etc. in places with large contrast.

[0073] In summary, the fixed-focus lens provided in the first embodiment of the present invention adopts an all-glass 10G structure, and realizes a small-volume internal focusing fixed-focus lens design with a focal length of 85mm, an imaging target surface of 43.2mm, and an F number of 1.8 by matching lens materials and reasonably allocating the optical power of each component. When the aperture is fully open, the MTF value of all fields of view reaches more than 0.4 at a spatial frequency of 30lp / mm, and achieves |distortion|≤1%, and corrects vertical axis chromatic aberration.

[0074] Embodiment 2

[0075] Figure 5 : is a structural schematic diagram of a fixed-focus lens corresponding to an infinite object distance provided by the second embodiment of the present utility model, such as Figure 5 As shown, the fixed-focus lens provided in Embodiment 2 of the present invention comprises a first lens 101, a second lens 102, a third lens 103, a fourth lens 104, a fifth lens 105, a sixth lens 106, a seventh lens 107, an eighth lens 108, a ninth lens 109 and a tenth lens 110 which are arranged in sequence along the optical axis from the object plane to the image plane; the fixed-focus lens also comprises a first lens group S1, a second lens group S2 and a third lens group S3; the first lens group S1 is a positive focal power lens group and comprises the first lens 101, the second lens 102, the third lens 103 and the fourth lens 104; the second lens group S2 is a negative focal power lens group and comprises the fifth lens 105, the sixth lens 106, the seventh lens 107, the eighth lens 108, the ninth lens 109 and the tenth lens 110; The third lens group S3 is a positive power lens group and includes a sixth lens 106, a seventh lens 107, an eighth lens 108, a ninth lens 109 and a tenth lens 110; wherein the first lens 101 is a positive power lens, the second lens 102 is a positive power lens, the third lens 103 is a negative power lens, the fourth lens 104 is a positive power lens, the fifth lens 105 is a negative power lens, the sixth lens 106 is a negative power lens, the seventh lens 107 is a positive power lens, the eighth lens 108 is a negative power lens, the ninth lens 109 is a positive power lens, and the tenth lens 110 is a negative power lens.

[0076] The configuration of the above-mentioned lens is the same as that in the first embodiment, and will not be described in detail here.

[0077] As another feasible implementation, specific parameters in the fixed-focus lens are described below.

[0078] Table 3 Optical design values ​​of the fixed focus lens in Example 2

[0079] Scope of protection Example 2 Lower limit Upper limit SD1 24.10 21 25.1 T24 / T14 0.7488 0.7 0.8 Φ1 / Φ14 0.7723 0.6 0.8 Vd2 95.1 80 100 SD5 / R5 -0.129 -0.13 -0.03 Φ610 / Φ14 0.8260 0.75 0.9 R7 / R8 1.326 1 1.4 G910 / TTL 0.1402 0.1 0.15

[0080] Table 4 Design values ​​of optical physical parameters of a fixed-focus lens

[0081]

[0082] The surface numbers in Table 4 are numbered according to the order of the surfaces of each lens, "2" represents the object surface of the first lens, "3" represents the image surface of the first lens, and so on. "STP" represents the aperture of the lens; the radius of curvature represents the curvature of the lens surface, a positive value represents that the surface is bent toward the image side, and a negative value represents that the surface is bent toward the object side; "infinity" represents that the surface is a plane and the radius of curvature is infinite; the thickness represents the central axial distance from the current surface to the next surface, the refractive index represents the ability of the material between the current surface and the next surface to deflect light, and the space represents that the current position is air with a refractive index of 1; the Abbe number represents the dispersion characteristics of the material between the current surface and the next surface to light. The semi-aperture represents half of the aperture size of the current surface.

[0083] Furthermore, Figure 6 This is a schematic diagram of the MTF of a fixed-focus lens corresponding to an infinite object distance provided in Example 2 of the utility model. The MTF diagram is one of the most commonly used and authoritative evaluation methods in modern optical design. The horizontal axis is the spatial frequency of the line pairs in the object space being imaged on the image plane through the optical system, and the unit is cycle / mm, and the vertical axis is the modulus of the optical transfer function. Curves of different colors represent the changing trends of the optical transfer functions of the images in the meridian (T as shown in the figure) and sagittal (S as shown in the figure) directions corresponding to different fields of view (0.00mm, 6.48mm, 10.8mm, 15.20mm, 19.44mm and 21.60mm as shown in the figure) with the increase of spatial frequency. The most ideal curve is a straight line that coincides with the diffraction limit of the system, indicating that the geometric aberrations of the light at all positions are smaller than the wave phase difference caused by the physical limitations of the system itself, and can be ignored. By Figure 6 It can be seen that the optical transfer function of the system is relatively high at 30lp / mm in each field of view, and the trend changes are soft and smooth, which shows that the optical system can achieve the imaging requirements of high resolution and uniform image quality.

[0084] Figure 7 : is a schematic diagram of field curvature distortion of a fixed-focus lens corresponding to an infinite object distance provided by the second embodiment of the present invention. In the left coordinate system of the figure, the horizontal coordinate represents the magnitude of the field curvature, and the unit is mm; the vertical coordinate represents the normalized image height, and there is no unit; T represents the meridian, and S represents the sagittal; Figure 7 It can be seen that the field curvature of the lens provided in this embodiment is effectively controlled, that is, when imaging, the difference between the image quality at the center and the image quality at the periphery is small. In the coordinate system on the right, the horizontal coordinate represents the magnitude of the distortion, in units of %; the vertical coordinate represents the normalized image height, in units of %. Figure 7 It can be seen that the maximum distortion of the lens provided in this embodiment is controlled within 2%, the distortion is well corrected, and the imaging distortion is small.

[0085] Figure 8 This is a schematic diagram of the vertical chromatic aberration curve of a fixed-focus lens corresponding to an infinite object distance provided in Example 2 of the utility model. The horizontal axis is the vertical distance of other wavelengths of light on the image plane from the main wavelength of light, and the vertical axis is the field of view. The curve describes the vertical chromatic aberration of light of different fields of view and different wavelengths (blue represents 486.1nm, green represents 587.6nm, and red represents 656.3nm) on the image plane. The most ideal curve is that all wavelengths of light are within the radius of the Airy disk, indicating that the vertical chromatic aberration of light in all fields of view is smaller than the wave phase difference caused by the physical limitations of the system itself. Figure 8 It can be seen that the vertical axis chromatic aberration of the lens provided in this embodiment is effectively controlled, that is, when imaging, it is unlikely to cause streaking, purple fringing, etc. in places with large contrast.

[0086] In summary, the fixed-focus lens provided in the second embodiment of the present invention adopts an all-glass 10G structure, and realizes a small-volume internal focusing fixed-focus lens design with a focal length of 85mm, an imaging target surface of 43.2mm, and an F number of 1.8 by matching lens materials and reasonably allocating the optical power of each component. When the aperture is fully open, the MTF value of all fields of view reaches more than 0.4 at a spatial frequency of 30lp / mm, and achieves |distortion|≤1%, and corrects vertical axis chromatic aberration.

[0087] Embodiment 3

[0088] Fig. 9 : is a schematic diagram of the structure of a fixed-focus lens corresponding to an infinite object distance provided by the third embodiment of the present utility model, such as Fig. 9As shown, the fixed-focus lens provided in Embodiment 2 of the present invention comprises a first lens 101, a second lens 102, a third lens 103, a fourth lens 104, a fifth lens 105, a sixth lens 106, a seventh lens 107, an eighth lens 108, a ninth lens 109 and a tenth lens 110 which are arranged in sequence along the optical axis from the object plane to the image plane; the fixed-focus lens also comprises a first lens group S1, a second lens group S2 and a third lens group S3; the first lens group S1 is a positive focal power lens group and comprises the first lens 101, the second lens 102, the third lens 103 and the fourth lens 104; the second lens group S2 is a negative focal power lens group and comprises the fifth lens 105, the sixth lens 106, the seventh lens 107, the eighth lens 108, the ninth lens 109 and the tenth lens 110; lens 105; the third lens group S3 is a positive power lens group and includes a sixth lens 106, a seventh lens 107, an eighth lens 108, a ninth lens 109 and a tenth lens 110; wherein the first lens 101 is a positive power lens, the second lens 102 is a positive power lens, the third lens 103 is a negative power lens, the fourth lens 104 is a positive power lens, the fifth lens 105 is a negative power lens, the sixth lens 106 is a negative power lens, the seventh lens 107 is a positive power lens, the eighth lens 108 is a negative power lens, the ninth lens 109 is a positive power lens, and the tenth lens 110 is a negative power lens. The arrangement of the above lenses is the same as that of the first embodiment, and will not be repeated here.

[0089] As another feasible implementation, specific parameters in the fixed-focus lens are described below.

[0090] Table 5 Optical design values ​​of the fixed focus lens in Example 3

[0091] Scope of protection Example 3 Lower limit Upper limit SD1 25.07 21 25.1 T24 / T14 0.7336 0.7 0.8 Φ1 / Φ14 0.7966 0.6 0.8 Vd2 81.6 80 100 SD5 / R5 -0.05 -0.13 -0.03 Φ610 / Φ14 0.8187 0.75 0.9 R7 / R8 1.393 1 1.4 G910 / TTL 0.1203 0.1 0.15

[0092] Table 6 Design values ​​of optical physical parameters of a fixed-focus lens

[0093]

[0094] The surface numbers in Table 6 are numbered according to the order of the surfaces of each lens, "2" represents the object surface of the first lens, "3" represents the image surface of the first lens, and so on. "STP" represents the aperture of the lens; the radius of curvature represents the curvature of the lens surface, a positive value represents that the surface is bent toward the image side, and a negative value represents that the surface is bent toward the object side; "infinity" represents that the surface is a plane and the radius of curvature is infinite; the thickness represents the central axial distance from the current surface to the next surface, the refractive index represents the ability of the material between the current surface and the next surface to deflect light, and the space represents that the current position is air with a refractive index of 1; the Abbe number represents the dispersion characteristics of the material between the current surface and the next surface to light. The semi-aperture represents half of the aperture size of the current surface.

[0095] Furthermore, Fig.10 This is a schematic diagram of the MTF of a fixed-focus lens corresponding to an infinite object distance provided in Example 3 of the utility model. The MTF diagram is one of the most commonly used and authoritative evaluation methods in modern optical design. The horizontal axis is the spatial frequency of the line pairs in the object space being imaged on the image plane through the optical system, and the unit is cycle / mm, and the vertical axis is the modulus of the optical transfer function. Curves of different colors represent the changing trends of the optical transfer functions of the images in the meridian (T as shown in the figure) and sagittal (S as shown in the figure) directions corresponding to different fields of view (0.00mm, 6.48mm, 10.8mm, 15.20mm, 19.44mm and 21.60mm as shown in the figure) with the increase of spatial frequency. The most ideal curve is a straight line that coincides with the diffraction limit of the system, indicating that the geometric aberrations of the light at all positions are smaller than the wave phase difference caused by the physical limitations of the system itself, and can be ignored. By Fig.10 It can be seen that the optical transfer function of the system is relatively high at 30lp / mm in each field of view, and the trend changes are soft and smooth, which shows that the optical system can achieve the imaging requirements of high resolution and uniform image quality.

[0096] Fig.11 : This is a schematic diagram of field curvature distortion of a fixed-focus lens corresponding to an infinite object distance provided by the third embodiment of the present invention. In the left coordinate system of the figure, the horizontal coordinate represents the magnitude of the field curvature, and the unit is mm; the vertical coordinate represents the normalized image height, and there is no unit; T represents the meridian, and S represents the sagittal; Fig.11 It can be seen that the field curvature of the lens provided in this embodiment is effectively controlled, that is, when imaging, the difference between the image quality at the center and the image quality at the periphery is small. In the coordinate system on the right, the horizontal coordinate represents the magnitude of the distortion, in units of %; the vertical coordinate represents the normalized image height, in units of %. Fig.11 It can be seen that the maximum distortion of the lens provided in this embodiment is controlled within 2%, the distortion is well corrected, and the imaging distortion is small.

[0097] Fig.12 This is a schematic diagram of the vertical chromatic aberration curve of a fixed-focus lens corresponding to an infinite object distance provided in Example 3 of the utility model. The horizontal axis is the vertical distance of other wavelengths of light on the image plane from the main wavelength of light, and the vertical axis is the field of view. The curve describes the vertical chromatic aberration of light of different fields of view and different wavelengths (blue represents 486.1nm, green represents 587.6nm, and red represents 656.3nm) on the image plane. The most ideal curve is that all wavelengths of light are within the radius of the Airy disk, indicating that the vertical chromatic aberration of light in all fields of view is smaller than the wave phase difference caused by the physical limitations of the system itself. Fig.12 It can be seen that the vertical axis chromatic aberration of the lens provided in this embodiment is effectively controlled, that is, when imaging, it is unlikely to cause streaking, purple fringing, etc. in places with large contrast.

[0098] In summary, the fixed-focus lens provided in the second embodiment of the present invention adopts an all-glass 10G structure, and realizes a small-volume internal focusing fixed-focus lens design with a focal length of 85mm, an imaging target surface of 43.2mm, and an F number of 1.8 by matching lens materials and reasonably allocating the optical power of each component. When the aperture is fully open, the MTF value of all fields of view reaches more than 0.4 at a spatial frequency of 30lp / mm, and achieves |distortion|≤1%, and corrects vertical axis chromatic aberration.

[0099] The above specific implementations do not constitute a limitation on the protection scope of the present utility model. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present utility model shall be included in the protection scope of the present utility model.

Claims

1. A fixed-focus lens, characterized in that: comprising a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, a ninth lens and a tenth lens arranged in sequence from the object plane to the image plane along the optical axis; The fixed-focus lens further includes a first lens group, a second lens group and a third lens group; the first lens group is a positive power lens group and includes the first lens, the second lens, the third lens and the fourth lens; the second lens group is a negative power lens group and includes the fifth lens; the third lens group is a positive power lens group and includes the sixth lens, the seventh lens, the eighth lens, the ninth lens and the tenth lens; Among them, the first lens is a positive power lens, the second lens is a positive power lens, the third lens is a negative power lens, the fourth lens is a positive power lens, the fifth lens is a negative power lens, the sixth lens is a negative power lens, the seventh lens is a positive power lens, the eighth lens is a negative power lens, the ninth lens is a positive power lens, and the tenth lens is a negative power lens.

2. The fixed-focus lens according to claim 1, characterized in that: The maximum semi-aperture of the first lens is SD1, the distance between the object side surface of the first lens and the image side surface of the fourth lens is T14, and the distance between the object side surface of the second lens and the image side surface of the fourth lens is T24; Among them, 21≤SD1≤25.1; 0.7≤T24 / T14≤0.

8.

3. The fixed-focus lens according to claim 1, characterized in that: The focal power of the first lens is Φ1, and the focal power of the first lens group is Φ14; Among them, 0.6≤Φ1 / Φ14≤0.

8.

4. The fixed-focus lens according to claim 1, wherein: The Abbe number of the second lens is Vd2; Among them, Vd2≥80.

5. The fixed-focus lens according to claim 1, wherein: The semi-aperture of the object side surface of the fifth lens is SD5, and the curvature radius of the object side surface of the fifth lens is R5; Among them, -0.13≤SD5 / R5≤-0.

03.

6. The fixed-focus lens according to claim 1, wherein: The focal power of the first lens group is Φ14, and the focal power of the third lens group is Φ610; Among them, 0.75≤Φ610 / Φ14≤0.

9.

7. The fixed-focus lens according to claim 1, wherein: The second lens is glued to the third lens; The sixth lens is glued to the seventh lens; The eighth lens is cemented to the ninth lens.

8. The fixed-focus lens according to claim 7, characterized in that: The image side surface of the seventh lens has a curvature radius of R7, and the object side surface of the eighth lens has a curvature radius of R8; Among them, 1≤R7 / R8≤1.

4.

9. The fixed-focus lens according to claim 1, wherein: The air interval between the ninth lens and the tenth lens is G910, and the total optical length of the fixed focus lens is TTL; Among them, 0.1≤G910 / TTL≤0.

15.

10. The fixed-focus lens according to claim 1, wherein: The first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, the ninth lens and the tenth lens are all spherical lenses.

Images