CN216956501U - Optical imaging system and electronic apparatus - Google Patents

Abstract

The application discloses an optical camera system and electronic equipment, wherein the optical camera system comprises a first lens group and a second lens group which are sequentially arranged along a light path, and the first lens group comprises a first lens and a reflective optical element which are arranged along a first optical axis and have positive refractive power; the second lens group comprises a second lens, a third lens and a fourth lens which are arranged along a second optical axis; the first optical axis is perpendicular to the second optical axis.

Description

Optical imaging system and electronic apparatus

Technical Field

The present disclosure relates to the field of optical elements, and in particular, to an optical imaging system and an electronic device including the same.

Background

At present, a long-focus camera is adopted in a mobile phone, but in order to adapt to the overall dimension of the mobile phone, the size of the long-focus camera has to be reduced, the long-focus camera usually adopts the edge cutting design of a lens or a lens barrel, or an imaging surface is reduced, which can lead to the great reduction of the photographing effect of the long-focus camera, and therefore, the imaging quality of a miniaturized and long-focus optical imaging system is still to be improved.

SUMMERY OF THE UTILITY MODEL

The application provides an optical camera system, which comprises a first lens group and a second lens group which are sequentially arranged along an optical path, and is characterized in that the first lens group comprises a first lens with positive refractive power and a reflective optical element which are arranged along a first optical axis; the second lens group comprises a second lens, a third lens and a fourth lens which are arranged along a second optical axis; the first optical axis is perpendicular to the second optical axis.

In one embodiment, the distance TL2 between the maximum effective radius edge of the first lens and the imaging plane of the optical imaging system in the direction along the second optical axis and the effective focal length f of the optical imaging system satisfy: TL2/f < 1.6.

In one embodiment, a distance TL2 between a maximum effective radius edge of the first lens and an imaging plane of the optical imaging system in a direction along the second optical axis satisfies: 20mm < TL2<30 mm.

In one embodiment, the effective focal length f of the optical imaging system satisfies: f >12 mm.

In one embodiment, a distance TL1 in a direction along the first optical axis from a front end of the first lens group to a maximum effective radius edge of a lens having a maximum effective radius in the second lens group and a distance TL2 in a direction along the second optical axis from the maximum effective radius edge of the first lens to an imaging surface of the optical imaging system satisfy: TL1/TL2< 0.6.

In one embodiment, the maximum field angle FOV of the optical imaging system satisfies: 15 ° < FOV <30 °.

In one embodiment, the effective focal length f of the optical imaging system and the entrance pupil diameter EPD of the optical imaging system satisfy: 2.5< f/EPD < 4.0.

In one embodiment, a maximum value Nmax of a refractive index of the second lens, a refractive index of the third lens, and a refractive index of the fourth lens satisfies: nmax > 1.5.

In one embodiment, the smallest abbe number Vmin among the abbe number of the second lens, the abbe number of the third lens and the abbe number of the fourth lens satisfies: vmin > 40.

In one embodiment, the refractive index N3 of the third lens and the refractive index N4 of the fourth lens satisfy: (N3+ N4)/2> 1.6.

In one embodiment, the abbe number V2 of the second lens and the abbe number V3 of the third lens satisfy: (V2+ V3)/2< 45.

In one embodiment, an air space TPL1 on the first optical axis from the image-side surface of the first lens to the incident surface of the reflective optical element and an air space TPL2 on the second optical axis from the exit surface of the reflective optical element to the object-side surface of the second lens satisfy: TPL 1X 10/TPL2< 1.0.

In one embodiment, the first lens group and the second lens group have at least one aspherical lens.

In one embodiment, the reflective optical element is a prism having an incident surface, a reflective surface, and an exit surface.

In one embodiment, the object distance TOL of the optical imaging system satisfies: 300mm < TOL.

In one embodiment, the object-side surface of the first lens element is convex and the image-side surface of the first lens element is convex.

In one embodiment, the second lens element has positive refractive power.

In one embodiment, the third lens element with negative refractive power has a concave object-side surface.

Another aspect of the present application provides an electronic apparatus that may include the optical imaging system according to the above-described embodiment and an imaging element for converting an optical image formed by the optical imaging system into an electrical signal.

This application adopts four lens and a reflection optical element to carry out the long-focus camera light path design of turning back, through the epaxial interval etc. of the central thickness of the refractive power of rational distribution each lens, face type, each lens and between each lens for above-mentioned optical camera system has at least one beneficial effect such as long focal length, big flux, miniaturization, high imaging quality.

Drawings

Other features, objects and advantages of the present application will become more apparent upon reading of the following detailed description of non-limiting embodiments thereof, made with reference to the accompanying drawings in which:

fig. 1 shows a schematic configuration diagram of an optical imaging system according to embodiment 1 of the present application in a Y-Z plane;

fig. 2A to 2D show an on-axis chromatic aberration curve, an astigmatism curve, a distortion curve, and a chromatic aberration of magnification curve, respectively, of the optical imaging system of embodiment 1;

fig. 3 shows a schematic configuration diagram of an optical imaging system according to embodiment 2 of the present application on the Y-Z plane;

fig. 4A to 4D show an on-axis chromatic aberration curve, an astigmatism curve, a distortion curve, and a chromatic aberration of magnification curve, respectively, of the optical imaging system of embodiment 2;

fig. 5 is a schematic view showing a structure of an optical imaging system according to embodiment 3 of the present application in the Y-Z plane;

fig. 6A to 6D show an axial chromatic aberration curve, an astigmatism curve, a distortion curve, and a magnification chromatic aberration curve, respectively, of the optical imaging system of embodiment 3 at an object distance of infinity;

fig. 7A to 7D show an axial chromatic aberration curve, an astigmatism curve, a distortion curve, and a magnification chromatic aberration curve, respectively, of the optical imaging system of embodiment 3 at an object distance of 1000 mm;

fig. 8A to 8D show an axial chromatic aberration curve, an astigmatism curve, a distortion curve, and a magnification chromatic aberration curve, respectively, of the optical imaging system of embodiment 3 at an object distance of 400 mm; and

fig. 9 is a schematic structural diagram of an electronic device according to an embodiment of the present application.

Detailed Description

For a better understanding of the present application, various aspects of the present application will be described in more detail with reference to the accompanying drawings. It should be understood that the detailed description is merely illustrative of exemplary embodiments of the present application and does not limit the scope of the present application in any way. Like reference numerals refer to like elements throughout the specification. The expression "and/or" includes any and all combinations of one or more of the associated listed items.

It should be noted that in this specification, the expressions first, second, third, etc. are used only to distinguish one feature from another, and do not represent any limitation on the features. Thus, the first lens discussed below may also be referred to as the second lens or the third lens without departing from the teachings of the present application.

In the drawings, the thickness, size, and shape of the lens have been slightly exaggerated for convenience of explanation. In particular, the shapes of the spherical or aspherical surfaces shown in the drawings are shown by way of example. That is, the shape of the spherical surface or the aspherical surface is not limited to the shape of the spherical surface or the aspherical surface shown in the drawings. The figures are purely diagrammatic and not drawn to scale.

Herein, the paraxial region refers to a region near the optical axis. If the lens surface is convex and the convex position is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the concave position is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the object is called the object side surface of the lens, and the surface of each lens closest to the imaging surface is called the image side surface of the lens.

It will be further understood that the terms "comprises," "comprising," "has," "having," "includes" and/or "including," when used in this specification, specify the presence of stated features, elements, and/or components, but do not preclude the presence or addition of one or more other features, elements, components, and/or groups thereof. Moreover, when a statement such as "at least one of" appears after a list of listed features, the entirety of the listed features is modified rather than modifying individual elements in the list. Furthermore, when describing embodiments of the present application, the use of "may" mean "one or more embodiments of the present application. Also, the term "exemplary" is intended to refer to an example or illustration.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments with reference to the attached drawings.

The features, principles, and other aspects of the present application are described in detail below.

An optical imaging system according to an exemplary embodiment of the present application may include a first lens group and a second lens group sequentially disposed along an optical path, the first lens group may include a first lens and a reflective optical element disposed along a first optical axis (i.e., an optical axis Z), and the second lens group may include a second lens, a third lens, and a fourth lens along a second optical axis (i.e., an optical axis Y), the optical axis Z being perpendicular to the optical axis Y. Through the grouping design of the optical camera system, the miniaturization of the whole system is realized, the light inlet quantity is increased in a limited space, and meanwhile, the automatic focusing function can be realized through the grouping movement of the second group.

In an exemplary embodiment, the first lens element with positive refractive power has a convex object-side surface and a convex image-side surface, and the field curvature of the optical imaging system can be balanced and the ghost image between the first lens element and the reflective optical element can be improved by controlling the shape of the first lens element and the distribution of the refractive power.

In an exemplary embodiment, the second lens element may have positive refractive power, and the processing manufacturability of the lens element may be improved by controlling the positive refractive power of the second lens element, which is beneficial to achieving the single group focusing function of the second lens element.

In an exemplary embodiment, the third lens element with negative refractive power has a concave object-side surface, and a ghost image between the second lens element and the third lens element can be effectively improved by controlling the shape of the third lens element.

In an exemplary embodiment, the fourth lens element can have positive refractive power or negative refractive power. The surface type arrangement of the optical image pickup system is beneficial to ensuring that the distribution of the refractive power of the optical image pickup system is more reasonable under the condition that the size of the optical image pickup system is not too large, and is vital to improving the aberration correction capability of the optical image pickup system and reducing the sensitivity of the optical image pickup system.

Any two adjacent lenses of the first lens to the fourth lens are provided with air space.

In an exemplary embodiment, having at least one aspherical lens in the first lens group and the second lens group is advantageous for achieving high imaging quality, reducing spherical aberration in the paraxial region.

In an exemplary embodiment, the reflective optical element is a prism, and has an incident surface, a reflective surface, and an exit surface, which is beneficial to achieving the efficacy of turning the optical path of the optical imaging system.

In an exemplary embodiment, the optical imaging system may be a system having a macro feature, and the object distance TOL of the optical imaging system satisfies: TOL of 300mm is favorable for realizing the shooting function of wider object distance, and meanwhile, the alignment of the focal plane can be quickly realized through the grouping and moving function of the second lens group.

The half ImgH of the diagonal length of the effective pixel area on the imaging surface of the optical imaging system satisfies: ImgH >3.08 mm. In an exemplary embodiment, ImgH may be, for example, in the range of 3.08mm to 3.11 mm.

In an exemplary embodiment, the optical imaging system according to the present application further includes a stop disposed between the first lens and the reflective optical element.

In an exemplary embodiment, an optical imaging system according to the present application may satisfy: TL2/f <1.6, where TL2 is the distance from the maximum effective radius edge of the first lens to the imaging plane of the optical imaging system in the direction along the second optical axis, and TL2 is the projection distance of the optical imaging system in the direction of the optical axis Y, as shown in fig. 1. The lens meets TL2/f <1.6, is beneficial to controlling the structural size among the whole lenses of the optical camera system and improving the assembly stability of the lens.

In an exemplary embodiment, an optical imaging system according to the present application may satisfy: 20mm < TL2<30mm, where TL2 is the distance of the maximum effective radius edge of the first lens to the imaging plane of the optical imaging system in the direction along the second optical axis. More specifically, TL2 further satisfies: 21.41mm < TL2<24.87 mm. Satisfy 20mm < TL2<30mm, be favorable to turning back the design through the prism, reduce the length of optical imaging system in optical axis Y direction, can satisfy the miniaturized design demand of complete machine.

In an exemplary embodiment, an optical imaging system according to the present application may satisfy: 5mm < TL1<10mm, where TL1 is the distance in the direction along the first optical axis from the front end of the first lens group to the maximum effective radius edge of the lens in the second lens group having the largest effective radius. As shown in fig. 1, TL1 is the projection distance of the optical imaging system in the optical axis Z direction. f is the effective focal length of the optical imaging system. More specifically, TL1 further satisfies: 6.6mm < TL1<7.6 mm. Satisfy 5mm < TL1<10mm, be favorable to effectively reducing telephoto lens's whole length through the prism design of turning back, guarantee can also keep less size when the focus increases.

In an exemplary embodiment, an optical imaging system according to the present application may satisfy: f >12mm, where f is the effective focal length of the optical imaging system. More specifically, f further may satisfy: f >15 mm. Preferably, 12mm < f <20 mm. And f is larger than 12mm, so that the optical camera system has a longer effective focal length and the telephoto effect is realized.

In an exemplary embodiment, an optical imaging system according to the present application may satisfy: TL1/TL2<0.6, where TL1 is a distance in a direction along the first optical axis from a front end of the first lens group to a maximum effective radius edge of a lens having a maximum effective radius in the second lens group, and TL2 is a distance in a direction along the second optical axis from the maximum effective radius edge of the first lens to an image plane of the optical imaging system. More specifically, TL1 and TL2 further satisfy: TL1/TL2< 0.4. The optical imaging system satisfies TL1/TL2<0.6, which is beneficial to the miniaturization of the whole size of the optical imaging system.

In an exemplary embodiment, an optical imaging system according to the present application may satisfy: 15 ° < FOV <30 °, where FOV is the maximum field angle of the optical imaging system. More specifically, the FOV may further satisfy: 20 ° < FOV <23 °. Satisfying 15 < FOV <30, beneficial to the telephoto capability of the telephoto lens.

In an exemplary embodiment, an optical imaging system according to the present application may satisfy: 2.5< f/EPD <4.0, where f is the effective focal length of the optical imaging system and EPD is the entrance pupil diameter of the optical imaging system. More specifically, f and EPD may further satisfy: 2.7< f/EPD < 3.4. Satisfy 2.5< f/EPD <4.0, be favorable to optical imaging system to realize the long focus function, increase optical imaging system's the light inlet quantity, promote optical imaging system's the function of shooing.

In an exemplary embodiment, an optical imaging system according to the present application may satisfy: nmax >1.5, where Nmax is the maximum of the refractive index of the second lens, the refractive index of the third lens, and the refractive index of the fourth lens. The Nmax is more than 1.5, which is beneficial to realizing large focal length of the optical camera system and controlling the whole size of the first lens.

In an exemplary embodiment, an optical imaging system according to the present application may satisfy: vmin >40, where Vmin is the smallest Abbe number among the Abbe number of the second lens, the Abbe number of the third lens, and the Abbe number of the fourth lens. The Vmin >40 is satisfied, the large focal length of the optical camera system is favorably realized, and the vertical axis chromatic aberration of the optical camera system is reduced.

In an exemplary embodiment, an optical imaging system according to the present application may satisfy: (N3+ N4)/2>1.6, where N3 is the refractive index of the third lens and N4 is the refractive index of the fourth lens. More specifically, N3 and N4 further satisfy: (N3+ N4)/2> 1.61. The optical imaging system meets the requirement that (N3+ N4)/2 is more than 1.6, and is beneficial to the optical imaging system to improve the brightness and enlarge the aperture under the condition of realizing large focal length.

In an exemplary embodiment, an optical imaging system according to the present application may satisfy: (V2+ V3)/2<45, where V2 is the Abbe number of the second lens and V3 is the Abbe number of the third lens. More specifically, V2 and V3 further satisfy: (V2+ V3)/2< 40. The optical lens meets the requirement that (V2+ V3)/2 is less than 45, so that the refractive power distribution is favorably improved, the field curvature of the optical imaging system is further optimized and improved, the shape of the lens is favorably optimized, and ghost images between two surfaces of the third lens are reduced.

In an exemplary embodiment, an optical imaging system according to the present application may satisfy: TPL1 × 10/TPL2<1.0, where TPL1 is an air interval on the first optical axis from the image-side surface of the first lens to the incident surface of the reflective optical element, and TPL2 is an air interval on the second optical axis from the exit surface of the reflective optical element to the object-side surface of the second lens. More specifically, TPL1 and TPL2 further satisfied TPL1 × 10/TPL2< 0.5. The lens meets the requirement that TPL1 multiplied by 10/TPL2 is less than 1.0, which is not only beneficial to ensuring stable transmission of light rays entering the optical camera system after refraction through the lens, but also beneficial to the arrangement of the structure of the second lens group, reduces the sensitivity of the front second lens group, reduces the whole size of the lens and leaves more space for the whole machine.

In an exemplary embodiment, the effective focal length f of the optical imaging system may be, for example, in the range of 15.67mm to 17.00mm, the effective focal length f1 of the first lens may be, for example, in the range of 20.31mm to 28.02mm, the effective focal length f2 of the second lens may be, for example, in the range of 6.46mm to 7.07mm, the effective focal length f3 of the third lens may be, for example, in the range of-32.81 mm to-4.21 mm, and the effective focal length f4 of the fourth lens may be, for example, in the range of-11.09 mm to 10.09 mm.

In an exemplary embodiment, the optical imaging system according to the present application further includes an optical filter for correcting color deviation and/or a protective glass for protecting a photosensitive element located on an imaging surface. The application provides an optical camera system with a foldback light path design and an automatic focusing function. The optical imaging system according to the above-described embodiment of the present application may employ a plurality of lenses, for example, the above four lenses. By reasonably distributing the refractive power, the surface shape, the center thickness of each lens, the on-axis distance between each lens and the like of each lens, the low-order aberration of the optical imaging system can be effectively balanced and controlled, meanwhile, the tolerance sensitivity can be reduced, and the miniaturization of the optical imaging system can be kept.

In the embodiment of the present application, at least one of the mirror surfaces of each of the first to fourth lenses is an aspherical mirror surface. The aspheric lens is characterized in that: the curvature varies continuously from the center of the lens to the periphery of the lens. Unlike a spherical lens having a constant curvature from the center of the lens to the periphery of the lens, an aspherical lens has better curvature radius characteristics, and has advantages of improving distortion aberration and improving astigmatic aberration. After the aspheric lens is adopted, the aberration generated in imaging can be eliminated as much as possible, and the imaging quality is further improved. Optionally, the object-side surface and the image-side surface of each of the first lens to the fourth lens are aspheric mirror surfaces.

However, it will be appreciated by those skilled in the art that the number of lenses making up the optical imaging system can be varied to achieve the various results and advantages described in this specification without departing from the claimed subject matter. For example, although four lenses are exemplified in the embodiment, the optical imaging system is not limited to including four lenses. The optical camera system may also include other numbers of lenses, if desired.

Specific examples of the optical imaging system applicable to the above-described embodiments are further described below with reference to the drawings.

Example 1

An optical imaging system according to embodiment 1 of the present application is described below with reference to fig. 1 to 2D. Fig. 1 shows a schematic configuration diagram of an optical imaging system according to embodiment 1 of the present application on the Y-Z plane.

As shown in fig. 1, the optical imaging system, in order from an object side to an image side, comprises: a first lens E1, a stop STO and a reflective optical element P arranged along the optical axis Z, a second lens E2, a third lens E3 and a fourth lens E4 arranged along the optical axis Y, a filter E5 and an image forming surface S11.

The first lens element E1 with positive refractive power has a convex object-side surface S1 and a convex image-side surface S2. The reflective optical element P is a prism, and has an incident surface P1, a reflective surface P2, and an exit surface P3. The second lens element E2 with positive refractive power has a concave object-side surface S3 and a convex image-side surface S4. The third lens element E3 with negative refractive power has a concave object-side surface S5 and a convex image-side surface S6. The fourth lens element E4 with negative refractive power has a concave object-side surface S7 and a concave image-side surface S8. Filter E5 has an object side S9 and an image side S10. Light from an object sequentially passes through the first lens E1, the stop STO and the reflective optical element P along the optical axis Z direction, is reflected to the optical axis Y direction through the reflective optical element P, sequentially passes through the second lens E2, the third lens E3, the fourth lens E4 and the filter E5 along the optical axis Y direction, and finally is imaged on the imaging surface S11.

In this example, the effective focal length f of the optical imaging system is 16.99mm, the effective focal length f1 of the first lens of the optical imaging system is 26.15mm, the effective focal length f2 of the second lens is 6.67mm, the effective focal length f3 of the third lens is-32.41 mm, the effective focal length f4 of the fourth lens is-10.70 mm, the distance TL1 in the direction along the optical axis Z from the front end of the first lens group to the maximum effective radius edge of the lens having the largest effective radius in the second lens group is 6.70mm, the distance TL2 in the direction along the optical axis Y from the maximum effective radius edge of the first lens to the imaging plane of the optical imaging system is 23.80mm, the half gh of the diagonal length of the effective pixel region on the imaging plane S11 of the optical imaging system is 3.09mm, the maximum field angle imfov of the optical imaging system is 21.16 °, and the ratio f/f of the effective focal length f to the entrance pupil of the optical imaging system is 3.30.30.

Table 1 shows a basic parameter table of the optical imaging system of embodiment 1, in which the unit of the radius of curvature and the thickness are both millimeters (mm).

TABLE 1

In embodiment 1, the object-side surface and the image-side surface of any one of the first lens E1 through the fourth lens E4 are aspheric surfaces, and the surface shape x of each aspheric lens can be defined by, but is not limited to, the following aspheric surface formula:

wherein x is the rise of the distance from the aspheric surface vertex to the aspheric surface vertex when the aspheric surface is at the position with the height of h along the optical axis direction; c is the paraxial curvature of the aspheric surface, c being 1/R (i.e., paraxial curvature c is the inverse of radius of curvature R in table 1 above); k is a conic coefficient; ai is the correction coefficient of the i-th order of the aspherical surface. Table 2 below shows the high-order coefficient A of each of the aspherical mirror surfaces S1 to S8 used in example 1₄、A₆、A₈、A₁₀、A₁₂、A₁₄、A₁₆And A₁₈。

Flour mark

A4

A6

A8

A10

A12

A14

A16

A18

S1

-3.0724E-02

-7.1794E-04

-1.4449E-04

3.1164E-05

-1.8974E-05

9.3676E-06

-1.8261E-06

0.0000E+00

S2

-4.9476E-02

-1.7851E-03

-3.0242E-04

2.8138E-05

-3.1854E-05

5.4188E-06

-1.0672E-05

0.0000E+00

S3

1.3451E-01

-9.8020E-03

-3.0996E-03

-3.3213E-04

2.9665E-04

1.4287E-04

3.6226E-05

0.0000E+00

S4

-2.0799E-01

-2.7160E-02

-3.5024E-02

-2.0687E-03

-5.9281E-03

-2.3998E-03

-8.7555E-04

0.0000E+00

S5

-2.9750E-01

-2.7574E-04

-6.2293E-03

-1.8326E-04

-1.7132E-04

-3.4807E-05

-1.1258E-05

0.0000E+00

S6

-2.6900E-01

9.0251E-03

-4.4581E-03

-4.6394E-04

-1.9667E-04

2.0619E-05

1.7291E-05

0.0000E+00

S7

8.6326E-01

-1.0321E-01

8.8528E-03

-3.3935E-03

7.6335E-04

-1.0516E-05

1.1777E-04

5.4872E-06

S8

1.2621E+00

-1.5852E-01

1.9722E-02

-5.1533E-03

1.7830E-03

3.9807E-05

2.2993E-04

0.0000E+00

TABLE 2

Fig. 2A shows an on-axis chromatic aberration curve of the optical imaging system of embodiment 1, which represents the deviation of the convergent focal points of light rays of different wavelengths after passing through the lens. Fig. 2B shows an astigmatism curve representing meridional field curvature and sagittal field curvature of the optical imaging system of embodiment 1. Fig. 2C shows a distortion curve of the optical imaging system of embodiment 1, which represents distortion magnitude values corresponding to different image heights. Fig. 2D shows a chromatic aberration of magnification curve of the optical imaging system of embodiment 1, which represents a deviation of different image heights on the imaging plane after the light rays pass through the lens. As can be seen from fig. 2A to 2D, the optical imaging system according to embodiment 1 can achieve good imaging quality.

Example 2

An optical imaging system according to embodiment 2 of the present application is described below with reference to fig. 3 to 4D. In this embodiment and the following embodiments, descriptions of parts similar to those of embodiment 1 will be omitted for the sake of brevity. Fig. 3 shows a schematic configuration diagram of an optical imaging system according to embodiment 2 of the present application on the Y-Z plane.

As shown in fig. 3, the optical imaging system, in order from an object side to an image side, comprises: a first lens E1, a stop STO and a reflective optical element P arranged along the optical axis Z, a second lens E2, a third lens E3 and a fourth lens E4 arranged along the optical axis Y, a filter E5 and an image forming surface S11.

The first lens element E1 with positive refractive power has a convex object-side surface S1 and a convex image-side surface S2. The reflective optical element P is a prism, and has an incident surface P1, a reflective surface P2, and an exit surface P3. The second lens element E2 with positive refractive power has a convex object-side surface S3 and a concave image-side surface S4. The third lens element E3 with negative refractive power has a concave object-side surface S5 and a concave image-side surface S6. The fourth lens element E4 with positive refractive power has a convex object-side surface S7 and a concave image-side surface S8. Filter E5 has an object side S9 and an image side S10. Light from an object sequentially passes through the first lens E1, the stop STO and the reflective optical element P along the optical axis Z direction, is reflected to the optical axis Y direction through the reflective optical element P, sequentially passes through the second lens E2, the third lens E3, the fourth lens E4 and the filter E5 along the optical axis Y direction, and finally is imaged on the imaging surface S11.

In this example, the effective focal length f of the optical imaging system is 15.68mm, the effective focal length f1 of the first lens of the optical imaging system is 20.32mm, the effective focal length f2 of the second lens is 7.06mm, the effective focal length f3 of the third lens is-4.22 mm, the effective focal length f4 of the fourth lens is 10.08mm, the distance TL1 from the front end of the first lens group to the maximum effective radius edge of the lens having the largest effective radius in the second lens group in the direction along the optical axis Z is 7.50mm, the distance TL2 from the maximum effective radius edge of the first lens to the imaging plane of the optical imaging system in the direction along the optical axis Y is 21.42mm, the half gh of the diagonal length of the effective pixel region on the imaging plane S11 of the optical imaging system is 3.10mm, the maximum field angle imfov of the optical imaging system is 22.19 °, and the ratio f/80 of the effective focal length f to the entrance pupil of the optical imaging system is 2.80.

Table 3 shows a basic parameter table of the optical imaging system of embodiment 2, in which the unit of the radius of curvature and the thickness are both millimeters (mm). Table 4 shows high-order term coefficients that can be used for each aspherical mirror surface in example 2, wherein each aspherical mirror surface type can be defined by formula (1) given in example 1 above.

TABLE 3

Flour mark

A4

A6

A8

A10

A12

A14

A16

A18

S1

-7.2777E-02

-6.7312E-03

-1.0491E-03

-1.2463E-04

-3.4383E-05

3.6408E-06

-3.4819E-06

0.0000E+00

S2

-6.5724E-02

-5.9178E-03

-8.8952E-04

-9.8339E-05

-2.3308E-05

1.9402E-06

-1.8837E-06

0.0000E+00

S3

2.1694E-01

2.7859E-02

-3.7530E-03

-2.4671E-04

-3.2787E-05

-1.1596E-04

1.3491E-05

0.0000E+00

S4

1.0195E-01

2.3996E-02

-1.1159E-02

-1.4744E-03

-2.8896E-04

-3.2124E-04

6.2666E-04

0.0000E+00

S5

-2.2475E-01

3.5171E-02

3.1549E-03

-7.9310E-03

1.0906E-03

-1.0734E-03

7.6694E-04

0.0000E+00

S6

1.1624E-01

2.8124E-02

1.3492E-02

-3.8385E-03

6.7566E-04

-4.4200E-04

-3.3935E-05

0.0000E+00

S7

5.6471E-01

-2.1207E-02

5.2636E-03

-3.0174E-04

2.0042E-04

1.0648E-04

-3.0307E-05

-1.1650E-06

S8

4.5690E-01

-3.6257E-02

1.8537E-03

-3.2488E-04

-9.3140E-05

1.5545E-04

-2.5580E-05

0.0000E+00

TABLE 4

Fig. 4A shows an on-axis chromatic aberration curve of the optical imaging system of embodiment 2, which represents the deviation of the convergent focal points of light rays of different wavelengths after passing through the lens. Fig. 4B shows astigmatism curves representing meridional field curvature and sagittal field curvature of the optical imaging system of embodiment 2. Fig. 4C shows a distortion curve of the optical imaging system of embodiment 2, which represents distortion magnitude values corresponding to different image heights. Fig. 4D shows a chromatic aberration of magnification curve of the optical imaging system of embodiment 2, which represents a deviation of different image heights on the imaging plane after the light ray passes through the lens. As can be seen from fig. 4A to 4D, the optical imaging system according to embodiment 2 can achieve good imaging quality.

Example 3

An optical imaging system according to embodiment 3 of the present application is described below with reference to fig. 5 to 6D. Fig. 5 shows a schematic configuration diagram of an optical imaging system according to embodiment 3 of the present application on the Y-Z plane.

As shown in fig. 5, the optical imaging system, in order from an object side to an image side, comprises: a first lens E1, a stop STO and a reflective optical element P arranged along the optical axis Z, a second lens E2, a third lens E3 and a fourth lens E4 arranged along the optical axis Y, a filter E5 and an image forming surface S11.

The first lens element E1 with positive refractive power has a convex object-side surface S1 and a convex image-side surface S2. The reflective optical element P is a prism, and has an incident surface P1, a reflective surface P2, and an exit surface P3. The second lens element E2 with positive refractive power has a convex object-side surface S3 and a convex image-side surface S4. The third lens element E3 with negative refractive power has a concave object-side surface S5 and a convex image-side surface S6. The fourth lens element E4 with positive refractive power has a convex object-side surface S7 and a concave image-side surface S8. Filter E5 has an object side S9 and an image side S10. Light from an object sequentially passes through the first lens E1, the stop STO and the reflective optical element P along the optical axis Z direction, is reflected to the optical axis Y direction through the reflective optical element P, sequentially passes through the second lens E2, the third lens E3, the fourth lens E4 and the filter E5 along the optical axis Y direction, and finally is imaged on the imaging surface S11.

In this example, the effective focal length f1 of the first lens of the optical imaging system is 28.01mm, the effective focal length f2 of the second lens is 6.47mm, the effective focal length f3 of the third lens is-32.80 mm, the effective focal length f4 of the fourth lens is-11.08 mm, the distance TL1 from the front end of the first lens group to the maximum effective radius edge of the lens having the largest effective radius in the second lens group in the direction along the optical axis Z is 7.58mm, the half ImgH of the diagonal length of the effective pixel region on the imaging plane S11 of the optical imaging system is 3.09mm, and the ratio f/EPD of the effective focal length f of the optical imaging system to the entrance pupil diameter EPD of the optical imaging system is 3.30.

In this example, the second lens group of the optical imaging system moves relative to the image plane under different object moments to perform a macro zoom function, so the data corresponding to TPL2 and BFL in table 6 under different object moments TOL are different, when the object moment TOL is infinity, TPL2 is 5.1893mm, and BFL is 2.8318 mm; when the moment TOL is 1000mm, the TPL2 is 4.7893mm, and the BFL is 3.2318 mm; when the moment TOL is 400mm, TPL2 is 4.1893mm, and BFL is 3.8318 mm. TPL2 is an air space on the optical axis Y from the exit surface of the reflective optical element to the object-side surface of the second lens, and BFL is the back focus of the optical imaging system.

Table 5 shows a basic parameter table of the optical imaging system of embodiment 3, in which the unit of the radius of curvature and the thickness are both millimeters (mm). Table 6 shows high-order term coefficients that can be used for each aspherical mirror surface in example 3, wherein each aspherical mirror surface type can be defined by formula (1) given in example 1 above.

TABLE 5

Flour mark

A4

A6

A8

A10

A12

A14

A16

A18

S1

-3.0796E-02

-6.7681E-04

-1.0961E-04

2.5671E-05

-1.4111E-05

6.5705E-06

-1.2135E-06

0.0000E+00

S2

-6.0671E-02

-1.7203E-03

-1.9843E-04

5.3309E-05

-7.4550E-06

1.3781E-05

-3.7370E-06

0.0000E+00

S3

1.6362E-01

-1.0713E-02

-2.9000E-03

-3.8620E-04

2.0263E-04

1.0641E-04

5.6413E-05

0.0000E+00

S4

-2.5891E-01

-4.6457E-02

-4.8156E-02

-9.0781E-03

-8.8860E-03

-6.1923E-03

-1.5478E-03

0.0000E+00

S5

-2.9759E-01

-6.3236E-04

-5.3339E-03

-1.1177E-03

9.0883E-07

-5.5922E-05

-9.4032E-06

0.0000E+00

S6

-2.8626E-01

1.0252E-02

-4.8380E-03

-5.0105E-04

-2.2687E-04

-4.7571E-05

-5.4236E-06

0.0000E+00

S7

1.0409E+00

-1.2938E-01

1.3347E-02

-3.5544E-03

7.5358E-04

-4.6187E-05

1.1009E-04

1.5088E-07

S8

1.2356E+00

-1.8597E-01

2.3247E-02

-5.1661E-03

1.9667E-03

2.0644E-04

2.8442E-04

0.0000E+00

TABLE 6

Table 7 shows the corresponding parameter changes for example 3 at object moments TOL of infinity, 1000mm and 400mm, respectively.

In this example, when the object moment TOL is infinity, the effective focal length f of the optical imaging system is 16.29mm, the maximum field angle FOV of the optical imaging system is 21.24 °, and the ratio TL2/f, which is the distance TL2 from the maximum effective radius edge of the first lens to the imaging plane in the direction of the optical axis Y, to the effective focal length f of the optical imaging system is 1.53. The air gap TPL2 on the optical axis Y from the exit surface of the reflective optical element to the object-side surface of the second lens is 5.1893 mm.

In this example, when the object moment TOL is 1000mm, the effective focal length f of the optical imaging system is 16.20mm, the maximum field angle FOV of the optical imaging system is 21.03 °, and the ratio TL2/f of the distance TL2 from the maximum effective radius edge of the first lens to the imaging plane in the optical axis Y direction to the effective focal length f of the optical imaging system is 1.53. The air gap TPL2 on the optical axis Y from the exit surface of the reflective optical element to the object-side surface of the second lens is 4.7893 mm.

In this example, when the object moment TOL is 400mm, the effective focal length f of the optical imaging system is 16.06mm, the maximum field angle FOV of the optical imaging system is 20.73 °, and the ratio TL2/f of the distance TL2 from the maximum effective radius edge of the first lens to the imaging plane in the optical axis Y direction to the effective focal length f of the optical imaging system is 1.55. The air gap TPL2 on the optical axis Y from the exit surface of the reflective optical element to the object-side surface of the second lens is 4.1893 mm.

TABLE 7

Fig. 6A shows an on-axis chromatic aberration curve of the optical imaging system of embodiment 3, which represents the deviation of the convergent focal points of light rays of different wavelengths after passing through the lens. Fig. 6B shows astigmatism curves representing meridional field curvature and sagittal field curvature of the optical imaging system of embodiment 3. Fig. 6C shows a distortion curve of the optical imaging system of embodiment 3, which represents distortion magnitude values corresponding to different image heights. Fig. 6D shows a chromatic aberration of magnification curve of the optical imaging system of embodiment 3, which represents a deviation of different image heights on the imaging plane after the light ray passes through the lens. As can be seen from fig. 6A to 6D, the optical imaging system according to embodiment 3 can achieve good imaging quality.

In summary, examples 1 to 3 satisfy the relationships shown in table 8, respectively, when the moment TOL is infinity.

Conditions/examples	1	2	3
				TL2/f	1.40	1.37	1.53
TL1/TL2	0.28	0.35	0.30
				(N3+N4)/2	1.62	1.66	1.62
(V2+V3)/2	37.55	39.30	37.55
				TPL1×10/TPL2	0.39	0.44	0.39

TABLE 8

The application also provides an electronic device which can be a mobile electronic device such as a digital camera, a mobile phone and the like. The electronic apparatus is equipped with the above-described optical imaging system and an imaging element for converting an optical image formed by the optical imaging system into an electric signal, and its electronic photosensitive element may be a photosensitive coupling element (CCD) or a complementary metal oxide semiconductor element (CMOS). Fig. 9 shows a schematic structural diagram of an electronic device according to an embodiment of the present application, where the electronic device is a mobile phone and an optical imaging system is configured on the mobile phone.

The above description is only a preferred embodiment of the application and is illustrative of the principles of the technology employed. It will be appreciated by a person skilled in the art that the scope of the invention as referred to in the present application is not limited to the embodiments with a specific combination of the above-mentioned features, but also covers other embodiments with any combination of the above-mentioned features or their equivalents without departing from the inventive concept. For example, the above features may be replaced with (but not limited to) features having similar functions disclosed in the present application.

Claims (19)

1. The optical image pickup system comprises a first lens group and a second lens group which are sequentially arranged along an optical path, and is characterized in that the first lens group comprises a first lens with positive refractive power and a reflective optical element which are arranged along a first optical axis; the second lens group comprises a second lens, a third lens and a fourth lens which are arranged along a second optical axis; the first optical axis is perpendicular to the second optical axis.

2. The optical imaging system according to claim 1, wherein a distance TL2 between a maximum effective radius edge of the first lens and an imaging plane of the optical imaging system in a direction along the second optical axis satisfies an effective focal length f of the optical imaging system: TL2/f < 1.6.

3. The optical imaging system according to claim 1, wherein a distance TL2 between a maximum effective radius edge of the first lens and an imaging plane of the optical imaging system in a direction along the second optical axis satisfies: 20mm < TL2<30 mm.

4. The optical imaging system according to claim 1, wherein an effective focal length f of the optical imaging system satisfies: f >12 mm.

5. The optical image pickup system according to claim 1, wherein a distance TL1 in a direction along the first optical axis from a front end of the first lens group to a maximum effective radius edge of a lens having a maximum effective radius among the second lens groups and a distance TL2 in a direction along the second optical axis from the maximum effective radius edge of the first lens to an image plane of the optical image pickup system satisfy: TL1/TL2< 0.6.

6. The optical imaging system according to claim 1, wherein a maximum field angle FOV of the optical imaging system satisfies: 15 ° < FOV <30 °.

7. The optical imaging system of claim 1, wherein the effective focal length f of the optical imaging system and the entrance pupil diameter EPD of the optical imaging system satisfy: 2.5< f/EPD < 4.0.

8. The optical imaging system according to claim 1, wherein a maximum value Nmax of a refractive index of the second lens, a refractive index of the third lens, and a refractive index of the fourth lens satisfies: nmax > 1.5.

9. The optical imaging system according to claim 1, wherein a minimum abbe number Vmin among the second lens abbe number, the third lens abbe number, and the fourth lens abbe number satisfies: vmin > 40.

10. The optical imaging system according to claim 1, wherein a refractive index N3 of the third lens and a refractive index N4 of the fourth lens satisfy: (N3+ N4)/2> 1.6.

11. The optical imaging system according to claim 1, wherein the abbe number V2 of the second lens and the abbe number V3 of the third lens satisfy: (V2+ V3)/2< 45.

12. The optical imaging system according to claim 1, wherein an air interval TPL1 on the first optical axis from the image-side surface of the first lens to the incident surface of the reflective optical element and an air interval TPL2 on the second optical axis from the exit surface of the reflective optical element to the object-side surface of the second lens satisfy: TPL 1X 10/TPL2< 1.0.

13. The optical imaging system according to claim 1, wherein at least one aspherical lens is provided in the first lens group and the second lens group.

14. The optical imaging system according to claim 1, wherein the reflective optical element is a prism having an incident surface, a reflecting surface, and an exit surface.

15. The optical imaging system according to claim 1, wherein the object distance TOL of the optical imaging system satisfies: 300mm < TOL.

16. The optical imaging system of claim 1, wherein the first lens element has a convex object-side surface and a convex image-side surface.

17. The optical imaging system of claim 1, wherein the second lens element has positive refractive power.

18. The optical imaging system of claim 1, wherein the third lens element with negative refractive power has a concave object-side surface.

19. An electronic apparatus, characterized by comprising the optical imaging system according to any one of claims 1 to 18 and an imaging element for converting an optical image formed by the optical imaging system into an electrical signal.

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