Folding imaging system lens

Abstract

The invention provides a folding imaging system lens, which comprises a first group of optical elements, the first group of optical elements comprises a first lens and a first prism which are arranged in sequence, the first prism is used for turning incident light from a first optical axis to a second optical axis, the first lens is arranged in front of the first prism, and the first lens has positive focal power; the second group of optical elements is arranged behind the first prism, the second group of optical elements comprises a fixed lens group and a movable lens group, and the movable lens group can move relative to the fixed lens group; the third group of optical elements comprises a second prism, the second prism enables the light to be guided to face the imaging surface, the field angle of view of the folded imaging system lens is FOV, and tanFOVlt is met; and 0.32, thereby providing a folding optical lens which is small in size and has a large field angle.

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 the need for miniaturized, compact camera modules that can capture high-quality images at a larger aperture. Folded imaging optical systems, as a solution to fold the optical path, can facilitate the miniaturization of telephoto cameras.

[0003] In the prior art, telephoto lenses are often designed as lenses of folded imaging optical systems so that they can be integrated into small mobile devices. However, due to the limitation that the design of 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 photosensitive chips in camera modules in small devices has also increased, from the original 1 / 2 inch to 1 inch. Large photosensitive chips require the optical system to have a larger optical aperture. In the prior art, folded imaging system lenses still use smaller photosensitive chips to achieve higher resolution. Generally speaking, due to the size requirements of folded imaging system lenses and the smaller optical aperture, folded imaging system lenses in the prior art often use smaller photosensitive chips. As the size of photosensitive chips becomes larger and the pixel density becomes tighter, the demand for compact optical imaging systems with better imaging performance has also increased.

[0005] In summary, the market is more looking forward to a small-sized folded imaging system lens that can be equipped with a higher total pixel count or larger pixel size image sensor, and also expects the folded imaging system lens to be able to adapt to a larger image sensor, or expects the folded imaging system lens to have a larger field of view to obtain a larger viewing range, or also hopes that the folded imaging system lens still maintains a sufficiently compact physical size. The challenge for optical system design work is to provide a folded imaging system lens with a smaller appearance, and an imaging lens system that can capture higher brightness or higher resolution images under the constraints of the physical size 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 includes a first lens and a first prism arranged in sequence, the first prism is used to turn incident light from a first optical axis to a second optical axis, 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, the second group of optical elements includes 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 includes 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 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 a negative optical focal length. 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 aspherical surfaces. The movable lens group can be kept 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 adopts the movable lens group to enhance the advantage of the inner focusing lens group moving for focusing. At the same time, when focusing, the optical properties of the folded imaging system lens, such as MTF peak, field curvature, astigmatism or screen tilt, will not be excessively affected.

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

[0009] By describing the embodiments of the present application in more detail in conjunction with the accompanying drawings, the above and other purposes, features and advantages of the present application will become more apparent. The accompanying drawings are used 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 accompanying drawings, the same reference numerals generally represent the same components or steps.

[0010] Figure 1 A structural diagram of an optical system according to an 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 A structural diagram of an optical system according to an embodiment of the present application is shown.

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

[0014] Figure 5 1 is a diagram of distortion, astigmatism and chromatic aberration of the folded imaging system lens of Example 1 when the object distance is 15 cm.

[0015] Figure 6 A structural diagram of an optical system according to another embodiment of the present application is shown.

[0016] Figure 7 1 and 2 are diagrams showing distortion, astigmatism and chromatic aberration of the folded imaging system lens of Example 2 when the object distance is infinite.

[0017] Figure 8 1 and 2 are diagrams of distortion, astigmatism and chromatic aberration of the folded imaging system lens of Example 2 when the object distance is 15 cm.

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

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

[0020] Fig.11 1 and 2 are diagrams of distortion, astigmatism and chromatic aberration of the folded imaging system lens of Example 3 when the object distance is 15 cm.

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

[0022] Fig.13 1 and 2 are diagrams showing distortion, astigmatism and chromatic aberration of the folded imaging system lens of Example 4 when the object distance is infinite.

[0023] Fig.14 1 and 2 are diagrams of distortion, astigmatism and chromatic aberration of the folded imaging system lens of Example 4 when the object distance is 15 cm.

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

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

[0026] Fig.17 1 and 2 are diagrams of distortion, astigmatism and chromatic aberration of the folded imaging system lens of Example 5 when the object distance is 15 cm. 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 here.

[0028] In the description of the present invention, it should be noted that directional words, such as the terms "center", "lateral", "longitudinal", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", etc., indicating directions and positional relationships are based on the directions or positional relationships shown in the accompanying drawings, which are only for the convenience of narrating the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, 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 the present application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0030] The terms "including" 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 comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products or apparatuses.

[0031] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, a contact connection, or an indirect connection through an intermediate medium, and it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0032] Attached Figure 1The folded imaging system lens 1 of the present application is shown in the figure. The folded imaging system lens 1 includes a first group of optical elements 10, the first group of optical elements 10 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 the first lens 101 has positive optical power; a second group of optical elements 20: the second group of optical elements 20 is arranged behind the first prism 102, and the second group of optical elements 20 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 the light toward the imaging surface, and 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 under the premise of satisfying 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 incident light is folded to another direction by the first prism 102, and the folded light is folded again by the second prism 301, so that the optical path required for the original single-direction light can be divided 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 focal length is arranged in front of the first prism 102, and 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 such a moving 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 moving 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 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 especially 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 accompanying drawings, 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 accompanying drawings, 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 effective optical diameter of the fifth lens 2021 is smaller than that of all the lenses in the fixed lens group 201, and the effective optical 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 reducing 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 optical power, the object side surface of the fourth lens 2013 is a convex surface, and the image side surface of the fourth lens 2013 is a convex surface, 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 a concave surface, and the image side surface of the sixth lens 2022 is a concave surface near the axis, 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 plane. Since the curved surface changes less in spherical surface processing than in aspherical surface processing, the curved surface processing precision is higher, so the processing yield rate of the first lens 101 used in the present application is higher, and the first prism 102 in the present application is an isosceles right triangle prism. Since the isosceles right triangle prism is easier to form, the second prism 301 has a higher forming yield rate. When the first lens 101 and the first prism 102 are assembled together, the assembly yield rate of the first group of optical elements 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 aspherical surface is more flexible than that of a spherical surface, and the aspherical 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 moving the movable lens group 202 for internal focusing in the present application can reduce the size, the inventor found that since the folded imaging system lens 1 of the present 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 the present application is difficult to design. The inventors have discovered that when the object side surface of the fifth lens 2021 in the present application is aspherical and the image side surface of the fifth lens 2021 is also aspherical, the aberration can be reduced. When the object side surface of the sixth lens is aspherical and the image side surface of the sixth lens 2022 is also aspherical, when the fifth lens 2021 and the sixth lens 2022 both have negative optical power, the mobile lens group 202 can be kept in a state of lower sensitivity, that is, the mobile lens group 202 will not cause significant changes to other optical properties of the optical system when it moves for focusing. The mobile lens group 202 used in the present application can enhance the advantage of the internal focusing 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 the present application, an aperture stop 2014 is provided between the first prism 102 and the second lens 2011, and the aperture stop 2014 is provided close to the second lens 2011 to control the brightness of the folded imaging system lens 1. In the present application, the second lens 2011 has an effective aperture similar to that of the third lens 2012 or the fourth lens 2013, and the aperture stop 2014 is provided on the second lens 2011 to ensure that the size of the aperture stop is large, thereby ensuring the imaging brightness of the folded imaging system lens 1. Those skilled in the art should know that in some other embodiments, the aperture stop 2014 can be provided 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 in the present application are similar, the folded imaging system lens 1 can also have a large aperture.

[0050] Attached Figure 2The structure diagram of some important parameters of the folded imaging system lens 1 of the present application is illustrated, wherein the length of the folded imaging system lens 1 in the second optical axis direction is SH, which represents the distance from the object side of the first lens 101 to 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 maximum 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, that 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 angle of the incident surface and the reflection surface of the first prism 102 to the intersection angle of the reflection surface and the emission 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] The 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 can be 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 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 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 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 < 2.5. Thus, on the premise of ensuring a relatively large image plane of the folding imaging system lens 1, a relatively large aperture can be ensured, or the light passing amount of the folding imaging system lens 1 can be increased to reduce the depth of field, or the imaging performance of the folding imaging system lens 1 can be improved.

[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] 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 can be emitted by the second prism 301 of the folding imaging system lens 1.

[0074] The length of the folding 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 can enter the second group of optical elements 20 to the greatest extent, while shortening the overall optical height of the folding imaging system lens 1.

[0076] The focal length of the first lens 101 is f1, and the effective focal length of the folding 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 converging effect better, so as to reduce the size of the incident surface of the first prism, thereby shortening the height of the folding imaging system lens 1.

[0078] 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 following relational expression:

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

[0080] The object distance of the folding 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 folding imaging system lens 1 is from 15 cm to infinity, which shows that the effective focusing distance of the folding imaging system lens 1 of this application starts from 15 cm. In the prior art, the folding 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 the 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 folding imaging system can meet the design requirements, it helps to meet the gap requirements between the moving lens group 202, the first prism and the fixed lens group 201, and avoid spatial collision between 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 folding imaging system can meet the design requirements, it helps to meet the gap 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 folding imaging system can meet the design requirements, it helps to meet the gap 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 collision between 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 2 / R) / (1+sqrt(1-(1+k)×(Y / R) 2 ))+∑(A i )×(Y i )

[0092] Where X: the relative distance between the point on the aspheric surface that is Y away from the optical axis and the tangent plane that is tangent to 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] Attached Figure 3 The first embodiment 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, the maximum viewing angle of the folded imaging system lens 1 is FOV, and 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 15 cm. 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 a convex surface, the image side surface of the first lens 101 is a plane, and the first lens 101 plays a role of focusing incident light; a first prism 102 with total 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 a concave surface, the image side surface of the second lens 2011 is a convex surface, and the second lens 2011 plays a role of correcting primary spherical aberration; a third lens 2012 with negative optical power, the object side surface of the third lens 2012 is a convex surface, the image side surface of the third lens 2012 is a concave surface, and the The third lens 2012 serves to correct primary and secondary 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 near axis, 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 this embodiment 1:

[0119]

[0120] <Example 2>

[0121] Attached Figure 6 Embodiment 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, the maximum viewing angle of the folded imaging system lens 1 is FOV, and the basic optical system parameters in Embodiment 2 are as follows: EFL=16.57mm; 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 a convex surface, the image side surface of the first lens 101 is a plane, and the first lens 101 plays a role of focusing incident light; a first prism 102 with total 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 a concave surface, the image side surface of the second lens 2011 is a convex surface, and the second lens 2011 plays a role of correcting primary spherical aberration; a third lens 2012 with negative optical power, the object side surface of the third lens 2012 is a convex surface, the image side surface of the third lens 2012 is a concave surface, and the The third lens 2012 serves to correct primary and secondary 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 near axis, and the sixth lens 2022 serving to correct coma, primary astigmatism and distortion.

[0123] The specific values ​​of the various conditional expressions in this embodiment 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] Attached Fig. 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, the maximum viewing angle of the folded imaging system lens 1 is FOV, and the basic optical system parameters in Example 3 are as follows: EFL=16.57mm; 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 a convex surface, the image side surface of the first lens 101 is a plane, and the first lens 101 plays a role of focusing incident light; a first prism 102 with total 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 a concave surface, the image side surface of the second lens 2011 is a convex surface, and the second lens 2011 plays a role of correcting primary spherical aberration; a third lens 2012 with negative optical power, the object side surface of the third lens 2012 is a convex surface, the image side surface of the third lens 2012 is a concave surface, and the The third lens 2012 serves to correct primary and secondary 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 near axis, and the sixth lens 2022 serving to correct coma, primary astigmatism and distortion.

[0145] The specific values ​​of the various conditional expressions in this embodiment 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] Attached Fig.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, the maximum viewing angle of the folded imaging system lens 1 is FOV, and the basic optical system parameters in Example 4 are as follows: EFL=16.57mm; 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 a convex surface, the image side surface of the first lens 101 is a plane, and the first lens 101 plays a role of focusing incident light; a first prism 102 with total 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 a concave surface, the image side surface of the second lens 2011 is a convex surface, and the second lens 2011 plays a role of correcting primary spherical aberration; a third lens 2012 with negative optical power, the object side surface of the third lens 2012 is a convex surface, the image side surface of the third lens 2012 is a concave surface, and the The third lens 2012 serves to correct primary and secondary 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 near axis, and the sixth lens 2022 serving to correct coma, primary astigmatism and distortion.

[0168] The specific values ​​of the various conditional expressions in this embodiment 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 parameters of Example 4:

[0183]

[0184]

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

[0186]

[0187] <Example 5>

[0188] Attached Fig.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, the maximum viewing angle of the folded imaging system lens 1 is FOV, and the basic optical system parameters in Example 5 are as follows: EFL=16.57mm; 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 a convex surface, the image side surface of the first lens 101 is a plane, and the first lens 101 plays a role of focusing incident light; a first prism 102 with total 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 a concave surface, the image side surface of the second lens 2011 is a convex surface, and the second lens 2011 plays a role of correcting primary spherical aberration; a third lens 2012 with negative optical power, the object side surface of the third lens 2012 is a convex surface, the image side surface of the third lens 2012 is a concave surface, and the The third lens 2012 serves to correct primary and secondary 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 near axis, and the sixth lens 2022 serving to correct coma, primary astigmatism and distortion.

[0190] The specific values ​​of the various conditional expressions in this embodiment 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 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, and provides 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 the optical system on an object 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 means that the light source is not on the optical axis of the optical system, and the light beam emitted by the light source has an inclination angle with the optical axis. After the light beam is refracted by the lens, the convergence point of its meridional beamlet and sagittal beamlet is not at the same point. That is, the light beam cannot be focused on one point, and the image is not clear. In the optical performance diagram of astigmatism, the horizontal axis represents the magnitude of astigmatism, and the vertical axis is also the image height.

[0211] In this application, axial chromatic aberration refers to the difference in the position of the image of an object point on the axis when light of different wavelengths is imaged. In the optical performance diagram of axial chromatic aberration, the horizontal axis is the position of light of different wavelengths deviating from the axis, and the vertical axis is the normalized image height.

[0212] The present application provides the following optical performance diagrams of the various embodiments. Overall, the five embodiments of the present application have relatively high optical performance and can obtain relatively high-quality optical information.

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

[0214] Figure 5 1 is a diagram of distortion, astigmatism and chromatic aberration of the folded imaging system lens of Example 1 when the object distance is 15 cm.

[0215] Figure 7 1 and 2 are diagrams showing distortion, astigmatism and chromatic aberration of the folded imaging system lens of Example 2 when the object distance is infinite.

[0216] Figure 81 and 2 are diagrams of distortion, astigmatism and chromatic aberration of the folded imaging system lens of Example 2 when the object distance is 15 cm.

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

[0218] Fig.11 1 and 2 are diagrams of distortion, astigmatism and chromatic aberration of the folded imaging system lens of Example 3 when the object distance is 15 cm.

[0219] Fig.13 1 and 2 are diagrams showing distortion, astigmatism and chromatic aberration of the folded imaging system lens of Example 4 when the object distance is infinite.

[0220] Fig.14 1 and 2 are diagrams of distortion, astigmatism and chromatic aberration of the folded imaging system lens of Example 4 when the object distance is 15 cm.

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

[0222] Fig.17 1 and 2 are diagrams of distortion, astigmatism and chromatic aberration of the folded imaging system lens of Example 5 when the object distance is 15 cm.

[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 above embodiments. The above embodiments and descriptions only describe the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention. These changes and improvements fall within the scope of the present invention to be protected. The scope of protection claimed by the present invention is defined by the attached claims and their equivalents.

Claims

1. A folded imaging system lens, comprising: A first group of optical elements: The first group of optical elements includes a first lens and a first prism arranged in sequence, the first prism is used to turn the incident light from the first optical axis to the second optical axis, 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 includes a fixed lens group and a movable lens group, and the movable lens group is movable relative to the fixed lens group; The third group of optical elements: The third group of optical elements includes a second prism, wherein the second prism guides light toward the imaging surface, and the field of view of the folded imaging system lens is FOV, which satisfies the following relationship: tanFOV<0.

32.

2. The folded imaging system lens according to claim 1, characterized in that: 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 a negative optical power, 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, and the object side surface and the image side surface of the sixth lens are aspherical surfaces.

3. The folded imaging system lens according to claim 2, characterized in that: 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。 4. The folded imaging system lens according to claim 3, characterized in that: The optical effective diameter of the object side of the first lens is D1, and the central thickness of the first lens is CT1, which satisfies the following relationship: 9.09 <D1 / CT1<10.23。 5. The folded imaging system lens according to claim 4, characterized in that: The total optical length of the fixed lens group is GL1, and the total optical length of the movable lens group is GL2, which satisfies the following relationship: 2.45 <GL1 / GL2<3.19。 6. The folded imaging system lens according to claim 5, 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。 7. The folded imaging system lens according to claim 6, 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。 8. The folded imaging system lens according to claim 7, characterized in that: 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。 9. The folded imaging system lens according to claim 8, characterized in that: 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: f1 / EFL>5.

6.

10. The folded imaging system lens according to claim 9, characterized in that: 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。 11. The folded imaging system lens according to claim 10, characterized in that: 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, satisfying the following relationship: 0.655 <AP12 / AP23<2.24。 12. The folded imaging system lens according to claim 10, characterized in that: 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。 13. The folded imaging system lens according to claim 10, characterized in that: 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。 14. The folded imaging system lens according to claim 10, characterized in that: The second lens has positive refractive power, and the third lens has negative refractive power.

Images