Folded imaging system lens

Abstract

The present application provides a folded imaging system lens, comprising a first group of optical elements, wherein the first group of optical elements comprises a first lens and a first prism arranged in sequence, wherein the first prism is used to deflect incident light from a first optical axis to a second optical axis, and the first lens is arranged in front of the first prism, and the first lens has positive optical power; a second group of optical elements: the second group of optical elements is arranged behind the first prism, and the second group of optical elements comprises a fixed lens group and a movable lens group, and the movable lens group is movable relative to the fixed lens group; a third group of optical elements: the third group of optical elements comprises a second prism, and the second prism guides light toward an imaging surface. The field of view of the folded imaging system lens is FOV, which satisfies tanFOV<0.32, thereby providing a small-sized folded optical lens with a large field of view.

Description

Technical Field

[0001] The present application relates to a camera lens, and in particular to a folded imaging system lens. Background Art

[0002] The emergence of small mobile devices such as smartphones, tablets, and tethered devices has led to a demand for miniaturized, compact camera modules capable of capturing high-quality images at wide apertures. Folded imaging optics, a solution that folds the optical path, facilitates the miniaturization of telephoto cameras.

[0003] In the prior art, telephoto lenses are often designed as lenses of folded imaging optical systems, so that telephoto lenses can be integrated into small mobile devices. However, due to the limitation that the design of the lenses of conventional folded imaging systems only performs optical path deflection at the front prism of the lens group, the camera modules used in the prior art are mostly conventional small cameras, which generally only achieve lower resolution, lower image quality or lower aperture.

[0004] With the development of technology, the size of the photosensitive chips in the camera modules of small devices has also increased. The size of the photosensitive chips has increased from the original 1 / 2 inch to 1 inch. The large photosensitive chips require the optical system to have a larger optical aperture. In the existing technology, the folded imaging system lens still uses a smaller photosensitive chip to achieve higher resolution. Generally speaking, due to the size requirements of the folded imaging system lens and the smaller optical aperture, the folded imaging system lens in the existing technology often uses a smaller photosensitive chip. As the size of the photosensitive chip becomes larger and the pixel density becomes closer, the demand for compact optical imaging systems with better imaging performance has also increased.

[0005] In summary, the market is increasingly looking forward to smaller folded imaging system lenses equipped with image sensors with higher total pixels or larger pixel sizes. They also expect folded imaging system lenses to accommodate larger image sensors, or to have a larger field of view for a wider viewing range, or to maintain a sufficiently compact physical size. The challenge for optical system design is to provide a folded imaging system lens with a smaller form factor and an imaging lens system that can capture higher brightness or higher resolution images within the physical size constraints of the terminal design. Summary of the Invention

[0006] In response to the above problems, the present application provides a folded imaging system lens, which includes a first group of optical elements, the first group of optical elements including a first lens and a first prism arranged in sequence, the first prism being used to transform incident light from a first optical axis to a second optical axis, the first lens being arranged in front of the first prism, and the first lens having positive optical power; a second group of optical elements: the second group of optical elements is arranged behind the first prism, the second group of optical elements including a fixed lens group and a movable lens group, the movable lens group being movable relative to the fixed lens group; a third group of optical elements: the third group of optical elements including a second prism, the second prism guiding light toward an imaging surface, the field of view of the folded imaging system lens being FOV, satisfying tanFOV<0.32, thereby providing a folded optical lens with a small size and a large field of view.

[0007] The present application provides a folded imaging system lens, which includes a fixed lens group and a movable lens group. The fixed lens group includes a second lens, a third lens, and a fourth lens in sequence. The movable lens group includes a fifth lens and a sixth lens in sequence. The sixth lens has negative optical power. The optical effective diameter of the fifth lens is smaller than that of all the lenses in the fixed lens group. The optical effective diameter of the sixth lens is smaller than that of all the lenses in the fixed lens group. The object side surface and image side surface of the fifth lens are aspherical surfaces. The object side surface and image side surface of the sixth lens are also aspherical surfaces. This can maintain the movable lens group in a state of low sensitivity, that is, the movable lens group will not cause significant changes to other optical properties of the optical system when it moves for focusing. The present application uses this movable lens group to enhance the advantages of moving the inner focus lens group for focusing. At the same time, when focusing, it will not excessively affect the optical properties of the folded imaging system lens, such as MTF peak, field curvature, astigmatism, or image tilt.

[0008] Further objectives and advantages of the present application will be fully apparent through understanding of the following description and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The above and other purposes, features, and advantages of the present application will become more apparent through a more detailed description of the embodiments of the present application in conjunction with the accompanying drawings. The accompanying drawings are intended to provide a further understanding of the embodiments of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the present application and do not constitute a limitation of the present application. In the drawings, the same reference numerals generally represent the same components or steps.

[0010] Figure 1 The optical system structure diagram of one embodiment of the present application is shown.

[0011] Figure 2 A schematic diagram of the structural dimensions of an embodiment of the present application is shown.

[0012] Figure 3 The optical system structure diagram of one embodiment of the present application is shown.

[0013] Figure 4 Graphs showing distortion, astigmatism, and chromatic aberration of the folded imaging system lens of Example 1 when the object distance is infinite.

[0014] Figure 5 Graphs showing distortion, astigmatism, and chromatic aberration of the folded imaging system lens of Example 1 at an object distance of 15 cm are shown.

[0015] Figure 6 The optical system structure diagram of another embodiment of the present application is shown.

[0016] Figure 7 Graphs showing distortion, astigmatism, and chromatic aberration of the folded imaging system lens of Example 2 when the object distance is infinite.

[0017] Figure 8 Graphs showing distortion, astigmatism, and chromatic aberration of the folded imaging system lens of Example 2 at an object distance of 15 cm are shown.

[0018] Figure 9 The optical system structure diagram of another embodiment of the present application is shown.

[0019] Figure 10 Graphs showing distortion, astigmatism, and chromatic aberration of the folded imaging system lens of Example 3 when the object distance is infinite.

[0020] Figure 11 Graphs showing distortion, astigmatism, and chromatic aberration of the folded imaging system lens of Example 3 at an object distance of 15 cm are shown.

[0021] Figure 12 The optical system structure diagram of another embodiment of the present application is shown.

[0022] Figure 13 Graphs showing distortion, astigmatism, and chromatic aberration of the folded imaging system lens of Example 4 when the object distance is infinite.

[0023] Figure 14 Graphs showing distortion, astigmatism, and chromatic aberration of the folded imaging system lens of Example 4 at an object distance of 15 cm are shown.

[0024] Figure 15 The optical system structure diagram of another embodiment of the present application is shown.

[0025] Figure 16 Graphs showing distortion, astigmatism, and chromatic aberration of the folded imaging system lens of Example 5 when the object distance is infinite.

[0026] Figure 17 Graphs showing distortion, astigmatism, and chromatic aberration of the folded imaging system lens of Example 5 at an object distance of 15 cm are shown. DETAILED DESCRIPTION

[0027] Below, the exemplary embodiments according to the present invention will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments of the present invention, and it should be understood that the present invention is not limited to the exemplary embodiments described herein.

[0028] In the description of the present invention, it should be noted that, for directional words, such as the terms "center", "horizontal", "longitudinal", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like, indicating directions and positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and cannot be understood as limiting the specific scope of protection of the present invention.

[0029] It should be noted that the terms "first", "second", etc. in the description and claims of this application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0030] The terms "comprises" and "having" and any variations thereof in the specification and claims of this application are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus that includes a series of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, product or apparatus.

[0031] In the description of the present invention, it should also be noted that, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct, contact, or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0032] Attachment Figure 1The present invention shows a folded imaging system lens 1, which includes a first group of optical elements 10, which includes a first lens 101 and a first prism 102 arranged in sequence. The first prism 102 is used to turn the incident light from the first optical axis O1 to the second optical axis O2. The first lens 101 is arranged in front of the first prism 102 and has positive optical power; the second group of optical elements 20 is arranged behind the first prism 102 and includes a solid A fixed lens group 201 and a movable lens group 202, wherein the movable lens group 202 is movable relative to the fixed lens group 201; a third group of optical elements 30: the third group of optical elements 30 includes a second prism 301, wherein the second prism 301 directs light toward the imaging surface. The field of view of the folded imaging system lens 1 is FOV, which satisfies the following relationship: tanFOV<0.32. In the present application, the folded imaging system lens 1 can divide the optical length into several different directions while meeting the total optical length, thereby reducing the length, width, and height of the folded imaging system lens 1 as a whole. Specifically, in the present application, the first prism 102 folds the incident light to another direction, and the second prism 301 folds the folded light again, thereby dividing the optical path required for the original single-direction light into at least two directions, thereby reducing the length, width, and height of the folded imaging system lens 1. In the present application, the first lens 101 with positive optical power is arranged in front of the first prism 102. The incident light can be converged after passing through the first lens 101, thereby reducing the size of the incident surface of the first prism 102, so as to reduce the size of the first prism 102. In the present application, the movable lens group 202 is movable relative to the fixed lens group 201. In the present application, the movable lens group 202 is moved for focusing. The use of this method of moving the lens group 202 for focusing can reduce the driving force required for the driving motor. The driving force of the motor is generally positively correlated with the size of the motor. The greater the driving force of the motor, the larger the overall size of the motor. Therefore, the use of the movable lens group 202 for focusing in the present application can reduce the size of the motor, thereby reducing the size of the camera module when the folded imaging system lens 1 is made into a camera module.Those skilled in the art should know that the FOV (Field of View) is an important parameter in an optical system. For example, under the premise of the same chip and similar TTL performance, the FOV designed in this application is larger than that of the prior art. Since a larger FOV means a larger shooting range of the lens, it is particularly rare for a telephoto system with a relatively small FOV. Secondly, the FOV is also closely related to the performance of the optical system, such as MTF (Modulation Transfer Function), relative illuminance, CRA (Confocal aperture ratio), distortion, etc., and further optimization is also required in the design.

[0033] As shown in the Figure 2 attachment, the length of the folding imaging system lens 1 in the second optical axis direction is SH, and the shoulder height of the fixed lens group 201 in the first optical axis direction is GH1, satisfying the condition: 1.44 < SH / GH1 < 1.5. Under the premise of meeting the overall optical height, it helps to shorten the shoulder height of the system.

[0034] As shown in the Figure 1 attachment, in this application, the fixed lens group 201 sequentially includes a second lens 2011, a third lens 2012, and a fourth lens 2013, and the moving lens group 202 sequentially includes a fifth lens 2021 and a sixth lens 2022. The optical apertures of the fifth lens 2021 and the sixth lens 2022 are smaller than those of the lenses in the fixed lens group 201. More specifically, the optical effective diameter of the fifth lens 2021 is smaller than that of all the lenses in the fixed lens group 201, and the optical effective diameter of the sixth lens 2022 is smaller than that of all the lenses in the fixed lens group 201. Therefore, in this application, using the fifth lens 2021 and the sixth lens 2022 as the moving lens group 202 for focusing can reduce the driving force required by the motor, and the optical apertures of the fifth lens 2021 and the sixth lens 2022 are small. The fifth lens 2021 and the sixth lens 2022 are the parts with the smallest apertures in the folding imaging system lens 1, which can greatly reduce the driving force required by the motor, thereby reducing the size of the motor and the size of the camera module.

[0035] In this application, the first lens 101 has a positive optical power. The object side of the first lens 101 is convex, and the image side of the first lens 101 is flat, so as to start converging the incident light.

[0036] In this application, the second lens 2011 has a positive optical power. The object side of the second lens 2011 is concave, and the image side of the second lens 2011 is convex, which plays a role in correcting primary spherical aberration.

[0037] In the present application, the third lens 2012 has negative optical power, the object side surface of the third lens 2012 is convex, and the image side surface of the third lens 2012 is concave, which plays a role in correcting primary and higher-order spherical aberrations.

[0038] In the present application, the fourth lens 2013 has positive refractive power, the object-side surface of the fourth lens 2013 is convex, and the image-side surface of the fourth lens 2013 is convex, which plays a role in correcting astigmatism.

[0039] In the present application, the fifth lens 2021 has negative optical power, the object side surface of the fifth lens 2021 is concave, and the image side surface of the fifth lens 2021 is convex, which plays a role in correcting coma, primary astigmatism and distortion.

[0040] In the present application, the sixth lens 2022 has negative optical power, the object side surface of the sixth lens 2022 is concave, and the image side surface of the sixth lens 2022 is concave at the paraxial portion, which plays a role in correcting coma, primary astigmatism and distortion.

[0041] In the present application, a glue layer is provided between the first lens 101 and the first prism 102 for connection, and a split assembly scheme is adopted, which can reduce the manufacturing complexity of the first group of optical elements 10 composed of the first lens 101 and the first prism 102, thereby improving the production yield.

[0042] In the present application, the object-side surface of the first lens 101 is a spherical surface, and the image-side surface of the first lens 101 is a flat surface. Since spherical surface processing has less curvature change than aspherical surface processing and has higher curvature processing precision, the first lens 101 used in the present application has a higher processing yield. In the present application, the first prism 102 is an isosceles right triangle prism. Since isosceles right triangle prisms are easier to form, the second prism 301 has a higher forming yield. When the first lens 101 and the first prism 102 are assembled together, the assembly yield of the first optical element 10 can be guaranteed.

[0043] In the present application, the object-side surface of the second lens 2011 is an aspherical surface, and the image-side surface of the second lens 2011 is an aspherical surface, which can correct the primary spherical aberration.

[0044] In the present application, the object-side surface of the third lens 2012 is an aspherical surface, and the image-side surface of the third lens 2012 is an aspherical surface, which can correct primary and secondary spherical aberrations.

[0045] In the present application, the object-side surface of the fourth lens 2013 is an aspherical surface, and the image-side surface of the third lens 2012 is an aspherical surface, which can correct astigmatism.

[0046] Generally speaking, the shape of an aspheric surface is more flexible than that of a spherical surface, and the aspheric surface can better improve the aberration effect.

[0047] In the present application, the second prism 301 is also an isosceles right triangle prism. Since the isosceles right triangle prism is easier to form, the second prism 301 has a higher forming yield.

[0048] It is worth mentioning that although the solution of using the movable lens group 202 for internal focusing in this application can reduce the size, the inventor found that the folded imaging system lens 1 of this application uses the first prism 102 and the second prism 301 to fold the light path twice and finally guide it to the photosensitive chip. The light is highly sensitive to the position of the optical element, and the movable lens group 202 in this application is difficult to design. The inventors found that when the object side surface of the fifth lens 2021 in this application adopts an aspheric surface and the image side surface of the fifth lens 2021 also adopts an aspheric surface, the aberration can be reduced. When the object side surface of the sixth lens adopts an aspheric surface and the image side surface of the sixth lens 2022 also adopts an aspheric surface, when the fifth lens 2021 and the sixth lens 2022 both have negative optical power, the movable lens group 202 can be kept in a state of lower sensitivity, that is, the movable lens group 202 will not cause a significant change to other optical properties of the optical system when it moves for focusing. The use of the movable lens group 202 in this application can enhance the advantage of the internal focus lens group moving for focusing. At the same time, when focusing, it will not excessively affect the MTF peak, field curvature, astigmatism or screen tilt and other optical properties of the folded imaging system lens 1.

[0049] In this application, an aperture stop 2014 is disposed between the first prism 102 and the second lens 2011. This aperture stop 2014 is positioned proximate to the second lens 2011 to control the brightness of the folded imaging system lens 1. In this application, the second lens 2011 has an effective aperture similar to that of the third lens 2012 or the fourth lens 2013. The placement of the aperture stop 2014 on the second lens 2011 ensures a large aperture, thereby ensuring the imaging brightness of the folded imaging system lens 1. Those skilled in the art will appreciate that in other embodiments, the aperture stop 2014 can be positioned between the second lens 2011 and the third lens 2012. Since the effective apertures of the second lens 2011, the third lens 2012, and the fourth lens 2013 are similar in this application, this can also enable the folded imaging system lens 1 to maintain a large aperture.

[0050] Attachment Figure 2The figure shows a structural diagram of some important parameters of the folded imaging system lens 1 of the present application, wherein the length of the folded imaging system lens 1 in the second optical axis direction is SH, which represents the distance between the object side surface of the first lens 101 and the imaging surface in the first optical axis direction.

[0051] The shoulder height of the fixed lens group 201 in the first optical axis direction is GH1, which is determined by the largest aperture of the second lens 2011, the third lens 2012 or the fourth lens 2013 in the first optical axis direction.

[0052] The shoulder height of the movable lens group 202 in the first optical axis direction is GH2, which is determined by the maximum aperture of the fifth lens 2021 or the sixth lens 2022 in the first optical axis direction.

[0053] The optical path length of the first prism 102 in the second optical axis direction is DP1, which is the aperture of the first prism 102 on the exit plane.

[0054] The height of the folded imaging system lens 1 in the first optical axis direction is SL, which is the distance in the Z direction from the intersection corner of the incident surface and the reflection surface of the first prism 102 to the intersection corner of the reflection surface and the output surface of the second prism 301.

[0055] The optical effective diameter of the object-side surface of the first lens 101 is D1, which is determined by the incident aperture size of the first lens 101.

[0056] The center thickness of the first lens 101 is CT1, which is determined by the distance between the object-side surface of the first lens 101 and the image-side surface of the first lens 101 in the direction of the first optical axis.

[0057] The total optical length of the fixed lens group 201 is GL1, which is determined by the lengths of the second lens 2011, the third lens 2012 to the fourth lens 2013 in the second optical axis direction.

[0058] The total optical length of the movable lens group 202 is GL2, which is determined by the lengths of the fifth lens 2021 and the sixth lens 2022 in the second optical axis direction.

[0059] The incident optical path length of the second prism 301 in the second optical axis direction is DP2, that is, the aperture of the second prism 301 on the incident plane.

[0060] The distance between the first prism 102 and the second lens in the second optical axis direction is AP12.

[0061] A distance between the fourth lens 2013 and the fifth lens 2021 in the second optical axis direction is AP23.

[0062] The distance between the sixth lens 2022 and the second prism 301 in the second optical axis direction is AP34.

[0063] As shown in the accompanying drawings, the folding imaging system lens 1 in this application satisfies the following conditions:

[0064] The entrance pupil diameter of the folding imaging system lens 1 is EPD, and the height of the folding imaging system lens 1 in the first optical axis direction is SL. The following relationship is satisfied:

[0065] 3.6 < SL / EPD < 4.02. Thus, on the premise of ensuring the height SL of the folding imaging system lens 1 in the first optical axis direction, the entrance pupil diameter EPD of the folding imaging system lens 1 is increased as much as possible, which is beneficial to increasing the aperture under the premise of size constraints to achieve a better imaging effect.

[0066] The optical effective diameter of the object side surface of the first lens 101 is D1, and the central thickness of the first lens 101 is CT1. The following relationship is satisfied:

[0067] 9.09 < D1 / CT1 < 10.23. Thus, on the premise of ensuring a relatively high processability of the first lens 101, the structural compactness of the folding imaging system lens 1 is improved, which is beneficial to shortening the height of the folding imaging system lens 1.

[0068] The total optical length of the fixed lens group 201 is GL1, and the total optical length of the moving lens group 202 is GL2. The following relationship is satisfied:

[0069] 2.45 < GL1 / GL2 < 3.19. Thus, on the premise of ensuring a relatively high processability of the fixed lens group 201 and the moving lens group 202, the total optical lengths of the fixed lens group 201 and the moving lens group 202 are reduced, and at the same time, the clearance margin between the fixed lens group 201 and the moving lens group 202 can also be increased.

[0070] The semi-image height of the folding imaging system lens 1 is ImgH, and the F-number of the folding imaging system lens 1 is Fno. The following relationship is satisfied:

[0071] 2.28 < ImgH / Fno < .......

[0072] The refractive index of the second prism 301 is Nd2, and the incident optical path length of the second prism 301 in the second optical axis direction is DP2. The following relationship is satisfied:

[0073] It seems there is an incomplete value in the relationship in line . It should be "2.28 < ImgH / Fno < 2.5" to be consistent with the previous context. The translation has been adjusted accordingly.0.19 < Nd2 / DP2 < 0.45, so as to ensure that under the premise of the relatively small size of the second prism 301, all the light rays can be emitted by the second prism 301 of the folded imaging system lens 1.

[0074] The length of the folded imaging system lens 1 in the second optical axis direction is SH, and the outgoing optical path length of the first prism 102 in the second optical axis direction is DP1, satisfying the following relational expression:

[0075] 0.41 < DP1 / SH < 0.44, ensuring that the light rays can enter the second group of optical elements 20 to the greatest extent, while shortening the overall optical height of the folded imaging system lens 1.

[0076] The focal length of the first lens 101 is f1, and the effective focal length of the folded imaging system lens 1 is EFL, satisfying the following relational expression:

[0077] f1 / EFL > 5.6. When this conditional expression is satisfied, it can be ensured that the first lens 101 has sufficient refractive power, making the light beam converging effect better, so as to reduce the size of the incident surface of the first prism, thereby shortening the height of the folded imaging system lens 1.

[0078] The length of the folded imaging system lens 1 in the second optical axis direction is SH, and the shoulder height of the fixed lens group 201 in the first optical axis direction is GH1, satisfying the following relational expression:

[0079] 1.44 < SH / GH1 < 1.5. When this conditional expression is satisfied, it can reduce the shoulder height of the folded imaging system lens 1 on the premise of meeting the overall optical height of the folded imaging system lens 1.

[0080] The object distance of the folded imaging system lens 1 is OBJ, which satisfies the following relational expression:

[0081] 15 cm < OBJ < INF. When this conditional expression is satisfied, it can ensure that the effective focusing distance of the folded imaging system lens 1 is from 15 cm to infinity. This shows that the effective focusing distance of the folded imaging system lens 1 of the present application starts from 15 cm. In the prior art, the folded imaging system lens 1 generally only meets the requirement of focusing on shooting distant scenes. Generally, the object distance requirement in the prior art is more than 50 cm, but this will affect the shooting use of the telephoto lens sometimes. For example, the telephoto lens sometimes shoots slightly closer scenes, but it is difficult to achieve clear shooting of nearby scenes with an object distance of more than 50 cm for clear focusing.

[0082] The distance between the first prism and the second lens in the second optical axis direction is AP12, the distance between the fourth lens 2013 and the fifth lens 2021 in the second optical axis direction is AP23, and the distance between the sixth lens 2022 and the second prism 301 in the second optical axis direction is AP34, which satisfy the following relational expressions:

[0083] 0.655 < AP12 / AP23 < 2.24. On the premise that the total optical length of the lens 1 of the folded imaging system can meet the design requirements, it helps to meet the clearance requirements between the moving lens group 202, the first prism and the fixed lens group 201, and avoid spatial collisions between the lens groups.

[0084] The distance between the first prism and the second lens in the second optical axis direction is AP12, the distance between the fourth lens 2013 and the fifth lens 2021 in the second optical axis direction is AP23, and the distance between the sixth lens 2022 and the second prism 301 in the second optical axis direction is AP34, which satisfy the following relational expressions:

[0085] 0.286 < AP12 / AP34 < 0.876. On the premise that the total optical length of the lens 1 of the folded imaging system can meet the design requirements, it helps to meet the clearance requirements between the moving lens group 202, the first prism and the fixed lens group 201, as well as the focusing stroke requirements of the moving lens group 202, and increase the space utilization efficiency of the moving lens group 202.

[0086] The distance between the first prism and the second lens in the second optical axis direction is AP12, the distance between the fourth lens 2013 and the fifth lens 2021 in the second optical axis direction is AP23, and the distance between the sixth lens 2022 and the second prism 301 in the second optical axis direction is AP34, which satisfy the following relational expressions:

[0087] 0.191 < AP12 / (AP23 + AP34) < 0.629. On the premise that the total optical length of the lens 1 of the folded imaging system can meet the design requirements, it helps to meet the clearance requirements between the moving lens group 202, the first prism and the fixed lens group 201, utilize the effective space of the moving lens group 202, and avoid spatial collisions between the lens groups.

[0088] The conditional numerical values of the embodiments of the present application are shown in the following table:

[0089]

[0090] In the embodiments of the present application that conform to the above embodiments, the aspheric curve equations of each lens are expressed as follows:

[0091] X(Y) = (Y , , ,

[0089] ,

[0091] , 2 , ,

[0090] / R) / (1+sqrt(1-(1+k)×(Y / R) 2 ))+∑(A i )×(Y i )

[0092] Where X is the distance from the point on the aspheric surface, which is Y away from the optical axis, to the tangent plane that intersects the optical axis of the aspheric surface.

[0093] Y: The vertical distance between the point on the aspheric curve and the optical axis;

[0094] R: radius of curvature;

[0095] k: cone coefficient;

[0096] Ai: i-th order aspheric coefficient;

[0097] <Example 1>

[0098] Attachment Figure 3 The diagram illustrates a first embodiment of the folded imaging system lens 1 of the present application. In this embodiment, the focal length of the folded imaging system lens 1 is EFL, the aperture value (f-number) of the folded imaging system lens 1 is Fno, and the maximum viewing angle of the folded imaging system lens 1 is FOV. The basic optical system parameters in this embodiment 1 are as follows: EFL = 15.38 mm; Fno = 2.1; and FOV = 17.98 degrees.

[0099] It is worth mentioning that Figure 3 The upper middle part shows the structural state diagram of the folded imaging system lens 1 when it is focused at infinity. Figure 3 The lower middle part shows the structural state diagram of the folded imaging system lens 1 when focusing at 15cm. The rest of the embodiments in this application also adopt this method.

[0100] The folded imaging system lens 1 includes, from the object side to the image side, a first lens 101 with positive optical power, the object side surface of the first lens 101 is convex, the image side surface of the first lens 101 is flat, and the first lens 101 plays the role of focusing the incident light; a first prism 102 with total internal reflection capability, in this embodiment, the first prism 102 is implemented as a prism; a second lens 2011 with positive optical power, the object side surface of the second lens 2011 is concave, the image side surface of the second lens 2011 is convex, and the second lens 2011 plays the role of correcting primary spherical aberration; a third lens 2012 with negative optical power, the object side surface of the third lens 2012 is convex, the image side surface of the third lens 2012 is concave, and the The third lens 2012 serves to correct primary and higher spherical aberrations; the fourth lens 2013 having positive power, the object side surface of the fourth lens 2013 being convex, the image side surface of the fourth lens 2013 being convex, and the fourth lens 2013 serving to correct astigmatism; the fifth lens 2021 having negative power, the object side surface of the fifth lens 2021 being concave, the image side surface of the fifth lens 2021 being convex, and the fifth lens 2021 serving to correct coma, primary astigmatism and distortion; the sixth lens 2022 having negative power, the object side surface of the sixth lens 2022 being concave, the image side surface of the sixth lens 2022 being concave at the paraxial portion, and the sixth lens 2022 serving to correct coma, primary astigmatism and distortion.

[0101] The specific values ​​of the various conditional expressions in Example 1 are as follows:

[0102] SL / EPD=3.646

[0103] TanFOV=0.324

[0104] D1 / CT1=9.136

[0105] GL1 / GL2=3.116

[0106] ImgH / Fno=2.438

[0107] Nd2 / DP2=0.185

[0108] OBJ=15cm~INF

[0109] DP1 / SH=0.42

[0110] f1 / EFL=6.405

[0111] SH / GH1=1.439

[0112] AP12 / AP23=0.705

[0113] AP12 / AP34=0.373

[0114] AP12 / (AP23+AP34)=0.191

[0115] Table 1 below shows the parameters of Example 1:

[0116]

[0117]

[0118] Table 2 below shows the aspheric coefficients of Example 1:

[0119]

[0120] <Example 2>

[0121] Attachment Figure 6 Example 2 of the folded imaging system lens 1 of the present application is illustrated. In this embodiment, the focal length of the folded imaging system lens 1 is EFL, the aperture value (f-number) of the folded imaging system lens 1 is Fno, and the maximum viewing angle of the folded imaging system lens 1 is FOV. The basic optical system parameters in Example 2 are as follows: EFL = 16.57 mm; Fno = 2.25; and FOV = 17.05 degrees.

[0122] The folded imaging system lens 1 includes, from the object side to the image side, a first lens 101 with positive optical power, the object side surface of the first lens 101 is convex, the image side surface of the first lens 101 is flat, and the first lens 101 plays the role of focusing the incident light; a first prism 102 with total internal reflection capability, in this embodiment, the first prism 102 is implemented as a prism; a second lens 2011 with positive optical power, the object side surface of the second lens 2011 is concave, the image side surface of the second lens 2011 is convex, and the second lens 2011 plays the role of correcting primary spherical aberration; a third lens 2012 with negative optical power, the object side surface of the third lens 2012 is convex, the image side surface of the third lens 2012 is concave, and the The third lens 2012 serves to correct primary and higher spherical aberrations; the fourth lens 2013 having positive power, the object side surface of the fourth lens 2013 being convex, the image side surface of the fourth lens 2013 being convex, and the fourth lens 2013 serving to correct astigmatism; the fifth lens 2021 having negative power, the object side surface of the fifth lens 2021 being concave, the image side surface of the fifth lens 2021 being convex, and the fifth lens 2021 serving to correct coma, primary astigmatism and distortion; the sixth lens 2022 having negative power, the object side surface of the sixth lens 2022 being concave, the image side surface of the sixth lens 2022 being concave at the paraxial portion, and the sixth lens 2022 serving to correct coma, primary astigmatism and distortion.

[0123] The specific values ​​of the various conditional expressions in Example 2 are as follows:

[0124] SL / EPD=3.603

[0125] TanFOV=0.306

[0126] D1 / CT1=9.09

[0127] GL1 / GL2=2.453

[0128] ImgH / Fno=2.276

[0129] Nd2 / DP2=0.185

[0130] OBJ=20cm~INF

[0131] DP1 / SH=0.412

[0132] f1 / EFL=5.6

[0133] SH / GH1=1.501

[0134] AP12 / AP23=0.655

[0135] AP12 / AP34=0.286

[0136] AP12 / (AP23+AP34)=0.199

[0137] Table 3 below shows the parameters of Example 2:

[0138]

[0139]

[0140] Table 4 below shows the aspheric coefficients of Example 2:

[0141]

[0142] <Example 3>

[0143] Attachment Figure 9 Example 3 of the folded imaging system lens 1 of the present application is illustrated. In this embodiment, the focal length of the folded imaging system lens 1 is EFL, the aperture value (f-number) of the folded imaging system lens 1 is Fno, and the maximum viewing angle of the folded imaging system lens 1 is FOV. The basic optical system parameters in Example 3 are as follows: EFL = 16.57 mm; Fno = 2.05; and FOV = 16.87 degrees.

[0144] The folded imaging system lens 1 includes, from the object side to the image side, a first lens 101 with positive optical power, the object side surface of the first lens 101 is convex, the image side surface of the first lens 101 is flat, and the first lens 101 plays the role of focusing the incident light; a first prism 102 with total internal reflection capability, in this embodiment, the first prism 102 is implemented as a prism; a second lens 2011 with positive optical power, the object side surface of the second lens 2011 is concave, the image side surface of the second lens 2011 is convex, and the second lens 2011 plays the role of correcting primary spherical aberration; a third lens 2012 with negative optical power, the object side surface of the third lens 2012 is convex, the image side surface of the third lens 2012 is concave, and the The third lens 2012 serves to correct primary and higher spherical aberrations; the fourth lens 2013 having positive power, the object side surface of the fourth lens 2013 being convex, the image side surface of the fourth lens 2013 being convex, and the fourth lens 2013 serving to correct astigmatism; the fifth lens 2021 having negative power, the object side surface of the fifth lens 2021 being concave, the image side surface of the fifth lens 2021 being convex, and the fifth lens 2021 serving to correct coma, primary astigmatism and distortion; the sixth lens 2022 having negative power, the object side surface of the sixth lens 2022 being concave, the image side surface of the sixth lens 2022 being concave at the paraxial portion, and the sixth lens 2022 serving to correct coma, primary astigmatism and distortion.

[0145] The specific values ​​of the various conditional expressions in Example 3 are as follows:

[0146] SL / EPD=3.669

[0147] TanFOV=0.303

[0148] D1 / CT1=9.15

[0149] GL1 / GL2=3.16

[0150] ImgH / Fno=2.498

[0151] Nd2 / DP2=0.45

[0152] OBJ=15cm~INF

[0153] DP1 / SH=0.412

[0154] f1 / EFL=7.981

[0155] SH / GH1=1.439

[0156] AP12 / AP23=1.538

[0157] AP12 / AP34=0.481

[0158] AP12 / (AP23+AP34)=0.366

[0159] Table 5 below shows the parameters of Example 3:

[0160]

[0161]

[0162] Table 6 below shows the aspheric coefficients of Example 3:

[0163]

[0164]

[0165] <Example 4>

[0166] Attachment Figure 12 Example 4 of the folded imaging system lens 1 of the present application is illustrated. In this embodiment, the focal length of the folded imaging system lens 1 is EFL, the aperture value (f-number) of the folded imaging system lens 1 is Fno, and the maximum viewing angle of the folded imaging system lens 1 is FOV. The basic optical system parameters in Example 4 are as follows: EFL = 16.57 mm; Fno = 2.05; and FOV = 16.87 degrees.

[0167] The folded imaging system lens 1 includes, from the object side to the image side, a first lens 101 with positive optical power, the object side surface of the first lens 101 is convex, the image side surface of the first lens 101 is flat, and the first lens 101 plays the role of focusing the incident light; a first prism 102 with total internal reflection capability, in this embodiment, the first prism 102 is implemented as a prism; a second lens 2011 with positive optical power, the object side surface of the second lens 2011 is concave, the image side surface of the second lens 2011 is convex, and the second lens 2011 plays the role of correcting primary spherical aberration; a third lens 2012 with negative optical power, the object side surface of the third lens 2012 is convex, the image side surface of the third lens 2012 is concave, and the The third lens 2012 serves to correct primary and higher spherical aberrations; the fourth lens 2013 having positive power, the object side surface of the fourth lens 2013 being convex, the image side surface of the fourth lens 2013 being convex, and the fourth lens 2013 serving to correct astigmatism; the fifth lens 2021 having negative power, the object side surface of the fifth lens 2021 being concave, the image side surface of the fifth lens 2021 being convex, and the fifth lens 2021 serving to correct coma, primary astigmatism and distortion; the sixth lens 2022 having negative power, the object side surface of the sixth lens 2022 being concave, the image side surface of the sixth lens 2022 being concave at the paraxial portion, and the sixth lens 2022 serving to correct coma, primary astigmatism and distortion.

[0168] The specific values ​​of the various conditional expressions in Example 4 are as follows:

[0169] SL / EPD=3.767

[0170] TanFOV=0.303

[0171] D1 / CT1=9.83

[0172] GL1 / GL2=3.19

[0173] ImgH / Fno=2.498

[0174] Nd2 / DP2=0.454

[0175] OBJ=15cm~INF

[0176] DP1 / SH=0.441

[0177] f1 / EFL=8.887

[0178] SH / GH1=1.482

[0179] AP12 / AP23=1.538

[0180] AP12 / AP34=0.481

[0181] AP12 / (AP23+AP34)=0.366

[0182] Table 7 below shows the various parameters of Example 4:

[0183]

[0184]

[0185] Table 8 below shows the aspheric coefficients of Example 4:

[0186]

[0187] <Example 5>

[0188] Attachment Figure 15 Example 5 of the folded imaging system lens 1 of the present application is illustrated. In this embodiment, the focal length of the folded imaging system lens 1 is EFL, the aperture value (f-number) of the folded imaging system lens 1 is Fno, and the maximum viewing angle of the folded imaging system lens 1 is FOV. The basic optical system parameters in Example 5 are as follows: EFL = 16.57 mm; Fno = 2.29; and FOV = 16.81 degrees.

[0189] The folded imaging system lens 1 includes, from the object side to the image side, a first lens 101 with positive optical power, the object side surface of the first lens 101 is convex, the image side surface of the first lens 101 is flat, and the first lens 101 plays the role of focusing the incident light; a first prism 102 with total internal reflection capability, in this embodiment, the first prism 102 is implemented as a prism; a second lens 2011 with positive optical power, the object side surface of the second lens 2011 is concave, the image side surface of the second lens 2011 is convex, and the second lens 2011 plays the role of correcting primary spherical aberration; a third lens 2012 with negative optical power, the object side surface of the third lens 2012 is convex, the image side surface of the third lens 2012 is concave, and the The third lens 2012 serves to correct primary and higher spherical aberrations; the fourth lens 2013 having positive power, the object side surface of the fourth lens 2013 being convex, the image side surface of the fourth lens 2013 being convex, and the fourth lens 2013 serving to correct astigmatism; the fifth lens 2021 having negative power, the object side surface of the fifth lens 2021 being concave, the image side surface of the fifth lens 2021 being convex, and the fifth lens 2021 serving to correct coma, primary astigmatism and distortion; the sixth lens 2022 having negative power, the object side surface of the sixth lens 2022 being concave, the image side surface of the sixth lens 2022 being concave at the paraxial portion, and the sixth lens 2022 serving to correct coma, primary astigmatism and distortion.

[0190] The specific values ​​of the various conditional expressions in Example 5 are as follows:

[0191] SL / EPD=4.015

[0192] TanFOV=0.3

[0193] D1 / CT1=10.23

[0194] GL1 / GL2=2.847

[0195] ImgH / Fno=2.498

[0196] Nd2 / DP2=0.4

[0197] OBJ=15cm~INF

[0198] DP1 / SH=0.412

[0199] f1 / EFL=8.761

[0200] SH / GH1=1.437

[0201] AP12 / AP23=2.24

[0202] AP12 / AP34=0.876

[0203] AP12 / (AP23+AP34)=0.629

[0204] Table 9 below shows the various parameters of Example 5:

[0205]

[0206] Table 10 below shows the aspheric coefficients of Example 5:

[0207]

[0208] The present application also discloses optical performance diagrams corresponding to the optical design, including optical performance diagrams of distortion, optical performance diagrams of astigmatism, and optical performance diagrams of axial chromatic aberration.

[0209] In this application, distortion refers to the degree of distortion of the image formed by an optical system relative to the object itself. In the optical performance diagram of distortion, the horizontal axis represents the magnitude of the distortion, and the vertical axis represents the image height.

[0210] In this application, astigmatism refers to the situation where the light source's point of illumination is not on the optical axis of the optical system, resulting in the light beam being tilted at an angle to the optical axis. After the light beam is refracted by a lens, the convergence points of its meridional and sagittal beamlets are not aligned. This means that the light beam cannot be focused to a single point, resulting in an unclear image. In the optical performance diagram of astigmatism, the horizontal axis represents the magnitude of the astigmatism, while the vertical axis also represents the image height.

[0211] In this application, axial chromatic aberration refers to the difference in the position of the image formed on the axis by light of different wavelengths. In the optical performance diagram of axial chromatic aberration, the horizontal axis is the position of the light of different wavelengths off the axis, and the vertical axis is the normalized image height.

[0212] This application provides the following optical performance diagrams of each embodiment. Overall, the five embodiments of this application have high optical performance and can obtain high-quality optical information.

[0213] Figure 4 Graphs showing distortion, astigmatism, and chromatic aberration of the folded imaging system lens of Example 1 when the object distance is infinite.

[0214] Figure 5 Graphs showing distortion, astigmatism, and chromatic aberration of the folded imaging system lens of Example 1 at an object distance of 15 cm are shown.

[0215] Figure 7 Graphs showing distortion, astigmatism, and chromatic aberration of the folded imaging system lens of Example 2 when the object distance is infinite.

[0216] Figure 8Graphs showing distortion, astigmatism, and chromatic aberration of the folded imaging system lens of Example 2 at an object distance of 15 cm are shown.

[0217] Figure 10 Graphs showing distortion, astigmatism, and chromatic aberration of the folded imaging system lens of Example 3 when the object distance is infinite.

[0218] Figure 11 Graphs showing distortion, astigmatism, and chromatic aberration of the folded imaging system lens of Example 3 at an object distance of 15 cm are shown.

[0219] Figure 13 Graphs showing distortion, astigmatism, and chromatic aberration of the folded imaging system lens of Example 4 when the object distance is infinite.

[0220] Figure 14 Graphs showing distortion, astigmatism, and chromatic aberration of the folded imaging system lens of Example 4 at an object distance of 15 cm are shown.

[0221] Figure 16 Graphs showing distortion, astigmatism, and chromatic aberration of the folded imaging system lens of Example 5 when the object distance is infinite.

[0222] Figure 17 Graphs showing distortion, astigmatism, and chromatic aberration of the folded imaging system lens of Example 5 at an object distance of 15 cm are shown.

[0223] The above describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the foregoing embodiments. The foregoing embodiments and description merely illustrate the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A folded imaging system lens, comprising: A first set of optical elements: The first set of optical elements includes, in sequence, a first lens and a first prism, wherein the first prism is used to deflect incident light from a first optical axis to a second optical axis, and the first lens is disposed in front of the first prism, and the first lens has positive optical power; A second group of optical elements: the second group of optical elements is disposed behind the first prism, and the second group of optical elements includes a fixed lens group and a movable lens group, wherein the movable lens group is movable relative to the fixed lens group; The fixed lens group is composed of a second lens, a third lens, and a fourth lens in sequence, and the movable lens group is composed of a fifth lens and a sixth lens in sequence; wherein the second lens has positive optical power, the third lens has negative optical power, and the sixth lens has negative optical power; The third group of optical elements: The third group of optical elements is composed of a second prism, which guides light toward the imaging surface. The field of view angle of the folded imaging system lens is FOV, which satisfies the following relationship: 0.3 <tanFOV<0.32; The entrance pupil diameter of the folded imaging system lens is EPD, and the height of the folded imaging system lens in the first optical axis direction is SL, which satisfies the following relationship: 3.6 <SL / EPD<4.02。 2. The folded imaging system lens according to claim 1, wherein: The optical effective diameter of the fifth lens is smaller than that of all lenses in the fixed lens group. The optical effective diameter of the sixth lens is smaller than that of all lenses in the fixed lens group. The object-side surface and the image-side surface of the fifth lens are aspherical surfaces. The object-side surface and the image-side surface of the sixth lens are also aspherical surfaces.

3. The folded imaging system lens according to claim 2, wherein: The optical effective diameter of the object side of the first lens is D1, and the center thickness of the first lens is CT1, which satisfies the following relationship: 9.09 <D1 / CT1<10.23 。 4. The folded imaging system lens according to claim 3, wherein: The total optical length of the fixed lens group is GL1, and the total optical length of the movable lens group is GL2, which satisfy the following relationship: 2.45 <GL1 / GL2<3.19 。 5. The folded imaging system lens according to claim 4, characterized in that: The half-image height of the folded imaging system lens is ImgH, and the aperture value of the folded imaging system lens is Fno, which satisfies the following relationship: 2.28 <ImgH / Fno<2.5 。 6. The folded imaging system lens according to claim 5, characterized in that: The refractive index of the second prism is Nd2, and the incident optical path length of the second prism in the second optical axis direction is DP2, which satisfies the following relationship: 0.19 <Nd2 / DP2<0.45 。 7. The folded imaging system lens according to claim 6, wherein: The length of the folded imaging system lens in the second optical axis direction is SH, and the length of the output optical path of the first prism in the second optical axis direction is DP1, which satisfies the following relationship: 0.41 <DP1 / SH<0.44 。 8. The folded imaging system lens according to claim 7, wherein: The focal length of the first lens is f1, and the effective focal length of the folded imaging system lens is EFL, which satisfies the following relationship: 5.6 <f1 / EFL<8.89 。 9. The folded imaging system lens according to claim 8, wherein: The length of the folded imaging system lens in the direction of the second optical axis is SH, and the shoulder height of the fixed lens group in the direction of the first optical axis is GH1, which satisfies the following relationship: 1.44 <SH / GH1<1.5 。 10. The folded imaging system lens according to claim 9, wherein: The distance between the first prism and the second lens in the second optical axis direction is AP12, and the distance between the fourth lens and the fifth lens in the second optical axis direction is AP23, which satisfies the following relationship: 0.655 <AP12 / AP23<2.24 。 11. The folded imaging system lens according to claim 9, wherein: The distance between the first prism and the second lens in the second optical axis direction is AP12, and the distance between the sixth lens and the second prism in the second optical axis direction is AP34, satisfying the following relationship: 0.286 <AP12 / AP34<0.876 。 12. The folded imaging system lens according to claim 9, wherein: The distance between the first prism and the second lens in the second optical axis direction is AP12, the distance between the fourth lens and the fifth lens in the second optical axis direction is AP23, and the distance between the sixth lens and the second prism in the second optical axis direction is AP34, satisfying the following relationship: 0.191 <AP12 / (AP23+AP34)<0.629。

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