CN113900224A

CN113900224A - Optical system, image capturing module and electronic equipment

Info

Publication number: CN113900224A
Application number: CN202111123714.8A
Authority: CN
Inventors: 谭怡翔; 党绪文; 李明
Original assignee: Jiangxi Jingchao Optical Co Ltd
Current assignee: Jiangxi Jingchao Optical Co Ltd
Priority date: 2021-09-24
Filing date: 2021-09-24
Publication date: 2022-01-07
Anticipated expiration: 2041-09-24
Also published as: CN113900224B

Abstract

The invention relates to an optical system, an image capturing module and an electronic device. The optical system includes: a first lens element with positive refractive power having a convex object-side surface and a concave image-side surface; a second lens element with refractive power having a convex object-side surface at paraxial region and a concave image-side surface at paraxial region; a third lens element with refractive power; a fourth lens element with positive refractive power having a convex object-side surface and a concave image-side surface; a fifth lens element with negative refractive power having a convex object-side surface and a concave image-side surface; the optical system satisfies: 25deg is less than or equal to HFOV/FNO is less than or equal to 33 deg. The optical system has good imaging quality and large aperture characteristics.

Description

Optical system, image capturing module and electronic equipment

Technical Field

The present invention relates to the field of camera shooting, and in particular, to an optical system, an image capturing module and an electronic device.

Background

With the rapid development Of Time Of Flight (TOF) detection technology, TOF lenses are also applied more and more widely in electronic devices such as smart phones, tablet computers, electronic readers and the like, so that the imaging quality requirements Of the industry on the TOF lenses are higher and higher. The diaphragm number of the TOF lens has great influence on imaging quality, the imaging brightness of the TOF lens can be improved by the large diaphragm characteristic, and meanwhile, the TOF lens can also have good imaging quality in a low-light environment. However, it is difficult for the current TOF lens to meet the requirement of a large aperture.

Disclosure of Invention

Accordingly, it is necessary to provide an optical system, an image capturing module and an electronic device for the TOF lens that cannot meet the requirement of a large aperture.

An optical system includes, in order from an object side to an image side along an optical axis:

a first lens element with positive refractive power having a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region;

a second lens element with refractive power having a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region;

a third lens element with refractive power;

a fourth lens element with positive refractive power having a convex object-side surface and a concave image-side surface;

a fifth lens element with negative refractive power having a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region;

and the optical system satisfies the following conditional expression:

25deg≤HFOV/FNO≤33deg；

wherein the HFOV is a half of a maximum field angle of the optical system, and the FNO is an f-number of the optical system.

In the optical system, the first lens element has positive refractive power, and the object-side surface of the first lens element is convex at a position close to the optical axis, so that light rays can be converged, and the total length of the optical system can be shortened. The convex-concave surface type of the first lens is matched with the convex-concave surface type of the second lens, so that the light is prevented from being too converged, the trend of the light is more gentle, the sensitivity of the optical system is reduced, and the chromatic aberration of the optical system is eliminated. The fourth lens element with positive refractive power can correct the incident angle of the beam expanded by the second and third lens elements. The fifth lens element with negative refractive power has a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region, and is favorable for correcting off-axis aberration and on-axis aberration, thereby improving imaging quality of the optical system. The optical system has the refractive power and the surface shape characteristics, can realize miniaturized design and has high imaging quality.

When the condition formula is met, the half field angle and the diaphragm number of the optical system can be reasonably configured, so that the optical system can simultaneously have the characteristics of a large field angle and a large diaphragm, the requirement of large-range shooting can be met, and the requirement of large light flux of the TOF lens can also be met. Exceeding the upper limit of the above conditional expression, the field angle and aperture of the optical system are too large, which is not favorable for controlling the light, and is not favorable for improving the imaging quality. If the angle of view and the aperture of the optical system are too small below the lower limit of the above conditional expression, the visible range is narrowed, and it is difficult to satisfy the requirement for large-range shooting, and a dark angle phenomenon is likely to occur due to insufficient light flux.

In one embodiment, the optical system satisfies the following conditional expression:

1.1≤f/EPD≤1.4；

where f is the effective focal length of the optical system and EPD is the entrance pupil diameter of the optical system. The optical system can have the characteristic of large aperture when the condition formula is met, so that the optical system can obtain enough light entering amount, dark corners at the periphery of an imaging surface are avoided, and the shooting effect of the optical system in a low-light environment is improved; in addition, the increase of the aperture is also beneficial to reducing the size of the Airy spots, so that the optical system has a higher resolution limit, and the optical system can meet the design requirement of high pixels by matching the reasonable arrangement of the refractive power of each lens in the optical system.

0.4≤SD11/ImgH≤0.6；

wherein SD11 is half of the maximum effective aperture of the object-side surface of the first lens, and ImgH is half of the image height corresponding to the maximum angle of view of the optical system. When satisfying above-mentioned conditional expression, the ratio of the biggest effective half bore of object side face that can rational configuration first lens and optical system's half image height is favorable to reducing the segment difference between each lens among the optical system to be favorable to the whole gentle transition of optical system, in addition, still be favorable to promoting optical system's the light flux volume, thereby improve the relative illuminance of formation of image. Exceeding the upper limit of the above conditional expressions, the maximum effective aperture of the object-side surface of the first lens is too large, resulting in difficulty in controlling the incident light, and a longer structure is required to realize smooth transition of the light, which is not favorable for the miniaturization design of the optical system. Below the lower limit of the above conditional expression, the maximum effective aperture of the object-side surface of the first lens is too small, which causes a decrease in the amount of light passing, and makes it difficult for the relative illumination to reach the design value, thereby making it difficult to meet the requirement of the TOF lens for high imaging quality.

1.6≤TTL/ImgH≤1.9；

wherein, TTL is a distance on an optical axis from an object-side surface of the first lens element to an image plane of the optical system, that is, a total optical length of the optical system, and ImgH is a half of an image height corresponding to a maximum field angle of the optical system. When the conditional expressions are satisfied, the ratio of the total optical length to the half-image height of the optical system can be reasonably configured, so that the total length of the optical system can be shortened, and the optical system can be miniaturized. Exceeding the upper limit of the above conditional expression results in an excessively large total length of the optical system, which is disadvantageous for the miniaturization design of the optical system. Below the lower limit of the above conditional expression, the total length of the optical system is too short, which causes the surface of each lens to be too curved, and high-order aberration is easily generated, so that the sensitivity between the lenses is increased, which is not favorable for achieving the product design specification and improving the imaging performance.

2≤|f2/f1|≤17；

wherein f2 is the effective focal length of the second lens, and f1 is the effective focal length of the first lens. When the conditional expressions are met, the ratio of the effective focal lengths of the first lens element and the second lens element can be reasonably configured, so that the refractive power of the second lens element is not too close to that of the first lens element, light rays converged by the first lens element can be smoothly transited to each lens element on the image side through the second lens element, and meanwhile, the balance of on-axis chromatic aberration and correction of off-axis coma of each lens element on the image side of the second lens element are facilitated. If the refractive power of the second lens element is too small, the burden of controlling light rays by each lens element on the image side is increased, and the surface shape of each lens element on the object side is too curved, which is not favorable for improving the imaging quality of the optical system. Being less than the lower limit of above-mentioned conditional expression, the refractive power of second lens and first lens is too close, leads to light too to gather together, and light is reasonable expansion not yet, also can increase each lens of image space and adjust the burden of light, is unfavorable for the promotion of formation of image quality.

0.1≤BF/TTL≤0.2；

wherein, BF is the shortest distance from the image side surface of the fifth lens element to the imaging surface of the optical system in the optical axis direction, and TTL is the distance from the object side surface of the first lens element to the imaging surface of the optical system in the optical axis direction. When the condition formula is met, the rear focal ratio of the optical system can be reasonably configured, the total length of the optical system is shortened to realize miniaturization design, meanwhile, reasonable control of the chief ray incident angle from the outermost view field to an imaging surface is facilitated, the decrease of relative illumination caused by the fact that the chief ray incident angle of the outermost view field is too large is avoided, and therefore the imaging quality of the optical system is improved.

0＜SAG42/SAG51≤3.4；

SAG42 is the rise of the image-side surface of the fourth lens at the maximum effective aperture, namely the distance from the intersection point of the image-side surface of the fourth lens and the optical axis to the maximum effective aperture of the image-side surface of the fourth lens in the optical axis direction, and SAG51 is the rise of the object-side surface of the fifth lens at the maximum effective aperture, namely the distance from the intersection point of the object-side surface of the fifth lens and the optical axis to the maximum effective aperture of the object-side surface of the fifth lens in the optical axis direction. When the conditional expressions are met, the ratio of the image side rise of the fourth lens to the object side rise of the fifth lens can be reasonably configured, so that the image side of the fourth lens is matched with the object side of the fifth lens in shape, the incident angle of light rays between the fourth lens and the fifth lens on the surface of the lens is favorably reduced, the off-axis chromatic aberration is favorably inhibited, and meanwhile, the luminous flux of the optical system is favorably improved.

1.3≤∑CT/∑AT≤2.6；

Σ CT is the sum of thicknesses of the first lens, the second lens, the third lens, the fourth lens, and the fifth lens on the optical axis, and Σ AT is the sum of air spaces on the optical axis of two adjacent lenses of the first lens, the second lens, the third lens, the fourth lens, and the fifth lens, that is, the sum of air spaces on the optical axis between the first lens and the second lens, between the second lens and the third lens, between the third lens and the fourth lens, and between the fourth lens and the fifth lens. When the condition formula is met, the central thickness of each lens in the optical system and the distance between every two adjacent lenses can be reasonably configured, so that the distribution of each lens is more uniform, the smooth transition of light rays in the optical system is facilitated, the high-order aberration is further facilitated to be eliminated, and the imaging quality of the optical system is improved.

0.8≤f1/f34≤1.2；

wherein f1 is an effective focal length of the first lens, and f34 is a combined focal length of the third lens and the fourth lens. When the conditional expressions are satisfied, the ratio of the effective focal length of the first lens element to the combined focal length of the third lens element and the fourth lens element can be reasonably configured, so that the refractive power of the first lens element is close to the combined refractive power of the third lens element and the fourth lens element, and a similar symmetrical structure is formed between the first lens element and the combination of the third lens element and the fourth lens element, thereby being beneficial to correcting the aberration of the optical system and improving the imaging quality of the optical system.

An image capturing module includes a photosensitive element and the optical system of any of the above embodiments, wherein the photosensitive element is disposed at an image side of the optical system. The image capturing module adopts the optical system, has good imaging quality and can have large aperture characteristics, so that the requirement of a TOF lens on large light transmission amount can be met.

An electronic device comprises a shell and the image capturing module, wherein the image capturing module is arranged on the shell. Adopt above-mentioned module of getting for instance among the electronic equipment, also can possess big light ring characteristic when possessing good formation of image quality to be favorable to the application of electronic equipment in the TOF detection field.

Drawings

FIG. 1 is a schematic structural diagram of an optical system according to a first embodiment of the present application;

FIG. 2 is a longitudinal spherical aberration diagram, an astigmatism diagram and a distortion diagram of an optical system in a first embodiment of the present application;

FIG. 3 is a schematic structural diagram of an optical system according to a second embodiment of the present application;

FIG. 4 is a longitudinal spherical aberration diagram, an astigmatism diagram and a distortion diagram of an optical system in a second embodiment of the present application;

FIG. 5 is a schematic structural diagram of an optical system according to a third embodiment of the present application;

FIG. 6 is a longitudinal spherical aberration diagram, an astigmatism diagram and a distortion diagram of an optical system in a third embodiment of the present application;

FIG. 7 is a schematic structural diagram of an optical system according to a fourth embodiment of the present application;

FIG. 8 is a longitudinal spherical aberration diagram, an astigmatism diagram and a distortion diagram of an optical system in a fourth embodiment of the present application;

FIG. 9 is a schematic structural diagram of an optical system according to a fifth embodiment of the present application;

FIG. 10 is a longitudinal spherical aberration diagram, an astigmatism diagram and a distortion diagram of an optical system in a fifth embodiment of the present application;

fig. 11 is a schematic view of an image capturing module according to an embodiment of the present application;

fig. 12 is a schematic diagram of an electronic device in an embodiment of the present application.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are not to be considered limiting of the invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and the like as used herein are for illustrative purposes only and do not denote a unique embodiment.

In some embodiments of the present disclosure, the optical system 100 includes, in order from an object side to an image side along an optical axis 110, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, and a fifth lens L5, referring to fig. 1. Specifically, the first lens element L1 includes an object-side surface S1 and an image-side surface S2, the second lens element L2 includes an object-side surface S3 and an image-side surface S4, the third lens element L3 includes an object-side surface S5 and an image-side surface S6, the fourth lens element L4 includes an object-side surface S7 and an image-side surface S8, and the fifth lens element L5 includes an object-side surface S9 and an image-side surface S10. The first lens L1, the second lens L2, the third lens L3, the fourth lens L4, and the fifth lens L5 are coaxially disposed, and an axis common to the lenses in the optical system 100 is an optical axis 110 of the optical system 100.

The first lens element L1 with positive refractive power has a convex object-side surface S1 near the optical axis 110 of the first lens element L1, which is favorable for converging light rays and thus shortening the total length of the optical system 100. The object-side surface S1 of the first lens element L1 is convex at the paraxial region 110, the image-side surface S2 is concave at the paraxial region 110, the object-side surface S3 of the second lens element L2 is convex at the paraxial region 110, and the image-side surface S4 is concave at the paraxial region 110. The convex-concave shape of the first lens L1 and the convex-concave shape of the second lens L2 are matched to prevent the light from being too converged, so that the trend of the light is more gradual, the sensitivity of the optical system 100 is reduced, and the chromatic aberration of the optical system 100 is also eliminated. The second lens element L2 and the third lens element L3 both have refractive power. The fourth lens element L4 with positive refractive power is favorable for correcting the incident angle of the light beam passing through the second lens element L2 and the third lens element L3. The object-side surface S7 of the fourth lens element L4 is convex at the paraxial region 110, and the image-side surface S8 is concave at the paraxial region 110. The fifth lens element L5 with negative refractive power has a convex object-side surface S9 at the paraxial region 110 and a concave image-side surface S10 at the paraxial region 110 of the fifth lens element L5, which is favorable for correcting off-axis aberration and on-axis aberration and improving the imaging quality of the optical system 100. With the above-described refractive power and surface shape characteristics, the optical system 100 can be designed to be compact and have high image quality.

In addition, in some embodiments, the optical system 100 is provided with a stop STO, which may be disposed on the object side of the first lens L1. In some embodiments, the optical system 100 further includes a filter L6 disposed on the image side of the fifth lens L5. The filter L6 may be an infrared band pass filter, and the filter L6 is used to transmit light in the infrared band and block light in other bands, so that the optical system 100 can be applied to the TOF detection field. Specifically, in some embodiments, the optical filter L6 is capable of transmitting light having a wavelength of 930nm to 950 nm. Of course, the filter L6 can also transmit infrared light with wavelengths in other ranges according to different requirements of the application environment. Furthermore, the optical system 100 further includes an image plane S13 located on the image side of the fifth lens L5, the image plane S13 is an imaging plane of the optical system 100, and incident light is adjusted by the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, and the fifth lens L5 and can be imaged on the image plane S13.

In some embodiments, the object-side surface and the image-side surface of each lens of optical system 100 are both aspheric. The adoption of the aspheric surface structure can improve the flexibility of lens design, effectively correct spherical aberration and improve imaging quality. In other embodiments, the object-side surface and the image-side surface of each lens of the optical system 100 may be spherical. It should be noted that the above embodiments are only examples of some embodiments of the present application, and in some embodiments, the surface of each lens in the optical system 100 may be an aspheric surface or any combination of spherical surfaces.

In some embodiments, each lens in the optical system 100 may be made of glass or plastic. The lens made of plastic material can reduce the weight of the optical system 100 and the production cost, and the light and thin design of the optical system 100 can be realized by matching with the small size of the optical system 100. The glass lens provides the optical system 100 with excellent optical performance and high temperature resistance. It should be noted that the material of each lens in the optical system 100 may be any combination of glass and plastic, and is not necessarily both glass and plastic.

It is to be noted that the first lens L1 does not mean that there is only one lens, and in some embodiments, there may be two or more lenses in the first lens L1, and the two or more lenses can form a cemented lens, and a surface of the cemented lens closest to the object side can be regarded as the object side surface S1, and a surface of the cemented lens closest to the image side can be regarded as the image side surface S2. Alternatively, although no cemented lens is formed between the lenses of the first lens L1, the distance between the lenses is relatively fixed, and in this case, the object-side surface of the lens closest to the object side is the object-side surface S1, and the image-side surface of the lens closest to the image side is the image-side surface S2. In addition, the number of lenses in the second lens L2, the third lens L3, the fourth lens L4, or the fifth lens L5 in some embodiments may also be greater than or equal to two, and a cemented lens may be formed between any two adjacent lenses, or may also be a non-cemented lens.

Further, in some embodiments, the optical system 100 satisfies the conditional expression: 25deg is less than or equal to HFOV/FNO is less than or equal to 33 deg; here, the HFOV is a half of the maximum field angle of the optical system 100, and the FNO is an f-number of the optical system 100. Specifically, the HFOV/FNO may be: 27.301, 27.638, 28.021, 28.555, 29.314, 29.847, 30.367, 30.449, 31.002 or 31.250, with the numerical unit deg. When the above conditional expressions are satisfied, the half field angle and the f-number of the optical system 100 can be reasonably arranged, so that the optical system 100 can have both a large field angle and a large aperture characteristic, and can satisfy both the requirement of large-range shooting and the requirement of large light flux of the TOF lens. Exceeding the upper limit of the above conditional expression, the field angle and aperture of the optical system 100 are too large, which is not favorable for controlling the light, and is not favorable for improving the imaging quality. If the angle of view and the aperture of the optical system 100 are too small below the lower limit of the above conditional expression, the visible range is narrowed, and it is difficult to satisfy the requirement for large-range shooting, and a dark angle phenomenon is likely to occur due to insufficient light flux.

In some embodiments, the optical system 100 satisfies the conditional expression: f/EPD is more than or equal to 1.1 and less than or equal to 1.4; where f is the effective focal length of the optical system 100 and EPD is the entrance pupil diameter of the optical system 100. Specifically, the f/EPD may be: 1.20, 1.22, 1.23, 1.25, 1.28, 1.29, 1.30, 1.31, 1.32 or 1.33. Satisfying the above conditional expressions, the optical system 100 can have a large aperture characteristic, which is beneficial to the optical system 100 to obtain sufficient light entering amount, avoid the occurrence of dark corners around the imaging surface, and simultaneously is beneficial to improving the shooting effect of the optical system 100 in a low light environment; in addition, the increase of the aperture is also beneficial to reducing the size of the Airy's patch, so that the optical system 100 has a higher resolution limit, and the optical system 100 can meet the design requirement of high pixel by matching the reasonable refractive power of each lens in the optical system 100.

In some embodiments, the optical system 100 satisfies the conditional expression: SD11/ImgH is more than or equal to 0.4 and less than or equal to 0.6; SD11 is half the maximum effective aperture of the object-side surface S1 of the first lens L1, and ImgH is half the image height corresponding to the maximum angle of view of the optical system 100. Specifically, SD11/ImgH may be: 0.448, 0.452, 0.457, 0.461, 0.475, 0.493, 0.502, 0.511, 0.532, or 0.544. When the above conditional expressions are satisfied, the ratio of the maximum effective half aperture of the object-side surface S1 of the first lens L1 to the half image height of the optical system 100 can be reasonably configured, which is beneficial to reducing the step difference between the lenses in the optical system 100, thereby being beneficial to the smooth transition of the whole optical system 100, and in addition, being beneficial to improving the light flux of the optical system 100, thereby improving the relative illumination of the image. Exceeding the upper limit of the above conditional expression, the maximum effective aperture of the object-side surface S1 of the first lens L1 is too large, which makes it difficult to control the incident light, and requires a longer structure to achieve smooth transition of the light, thus being disadvantageous to the miniaturization design of the optical system 100. Below the lower limit of the above conditional expression, the maximum effective aperture of the object-side surface S1 of the first lens L1 is too small, which reduces the amount of light passing through, makes it difficult for the relative illuminance to reach the designed value, and makes it difficult to satisfy the requirement of the TOF lens for high imaging quality.

It should be noted that in some embodiments, the optical system 100 may match a photosensitive element having a rectangular photosensitive surface, and the imaging surface of the optical system 100 coincides with the photosensitive surface of the photosensitive element. At this time, the effective pixel region on the imaging plane of the optical system 100 has a horizontal direction and a diagonal direction, the maximum field angle of the optical system can be understood as the maximum field angle of the optical system 100 in the diagonal direction, and ImgH can be understood as a half of the length of the effective pixel region on the imaging plane of the optical system 100 in the diagonal direction.

In some embodiments, the optical system 100 satisfies the conditional expression: TTL/ImgH is more than or equal to 1.6 and less than or equal to 1.9; wherein, TTL is a distance on an optical axis from an object-side surface of the first lens element to an image plane of the optical system, and ImgH is half of an image height corresponding to a maximum field angle of the optical system. Specifically, TTL/ImgH may be: 1.650, 1.667, 1.693, 1.705, 1.738, 1.766, 1.798, 1.824, 1.833 or 1.848. When the above conditional expressions are satisfied, the ratio of the total optical length to the half-image height of the optical system 100 can be configured reasonably, which is beneficial to shortening the total optical length of the optical system 100, so that the optical system 100 can realize a miniaturized design. Exceeding the upper limit of the above conditional expression results in an excessively large total length of the optical system 100, which is disadvantageous for the compact design of the optical system 100. Below the lower limit of the conditional expression, the total length of the optical system 100 is too short, which causes the surface shape of each lens to be too curved, and high-order aberration is easily generated, so that the sensitivity between lenses is increased, which is not favorable for achieving the product design specification and improving the imaging performance.

In some embodiments, the optical system 100 satisfies the conditional expression: | f2/f1| is more than or equal to 2 and less than or equal to 17; where f2 is the effective focal length of the second lens L2, and f1 is the effective focal length of the first lens L1. Specifically, | f2/f1| may be: 2.349, 2.687, 2.993, 3.552, 4.025, 4.347, 4.637, 6.368, 10.251, or 16.812. When the above conditional expressions are satisfied, the ratio of the effective focal lengths of the first lens element L1 and the second lens element L2 can be reasonably configured, so that the refractive power of the second lens element L2 is not too close to the refractive power of the first lens element L1, and therefore, the light rays converged by the first lens element L1 can smoothly transit to each lens element on the image side through the second lens element L2, and simultaneously, the chromatic aberration on the balance axis of each lens element on the image side of the second lens element L2 is also facilitated, and the off-axis coma is corrected. If the refractive power of the second lens element L2 is too small, the burden of controlling light beams by each lens element on the image side increases, and the surface shape of each lens element on the object side is too curved, which is not favorable for improving the imaging quality of the optical system 100. When the refractive power of the second lens element L2 and the refractive power of the first lens element L1 are too close to each other, the light rays are too converged, and the light rays are not expanded reasonably, which increases the burden of adjusting the light rays by each lens element on the image side, and is not favorable for improving the image quality.

In some embodiments, the optical system 100 satisfies the conditional expression: BF/TTL is more than or equal to 0.1 and less than or equal to 0.2; wherein, BF is the shortest distance from the image-side surface S10 of the fifth lens element L5 to the image plane of the optical system 100 along the optical axis 110, and TTL is the distance from the object-side surface S1 of the first lens element L1 to the image plane of the optical system 100 along the optical axis 110. Specifically, the BF/TTL may be: 0.137, 0.141, 0.148, 0.152, 0.154, 0.158, 0.162, 0.164, 0.169, or 0.176. When the above conditional expressions are satisfied, the rear focal ratio of the optical system 100 can be reasonably configured, the total length of the optical system 100 is shortened to realize the miniaturization design, and meanwhile, reasonable control of the chief ray incident angle from the outermost viewing field to the imaging surface is facilitated, and the decrease of the relative illumination caused by the overlarge chief ray incident angle from the outermost viewing field is avoided, so that the imaging quality of the optical system 100 is favorably improved.

In some embodiments, the optical system 100 satisfies the conditional expression: SAG42/SAG51 is more than 0 and less than or equal to 3.4; SAG42 is the rise of the image side surface S8 of the fourth lens L4 at the maximum effective aperture, and SAG51 is the rise of the object side surface S9 of the fifth lens L5 at the maximum effective aperture. Specifically, SAG42/SAG51 may be: 0.066, 0.154, 0.663, 1.251, 1.751, 2.354, 2.631, 2.894, 3.001, or 3.375. When the conditional expressions are satisfied, the ratio of the rise of the image-side surface S8 of the fourth lens L4 to the rise of the object-side surface S9 of the fifth lens L5 can be reasonably configured, so that the shape of the image-side surface S8 of the fourth lens L4 is matched with that of the object-side surface S9 of the fifth lens L5, and therefore the incident angle of light rays between the fourth lens L4 and the fifth lens L5 on the lens surface is favorably reduced, the off-axis chromatic aberration is favorably inhibited, and the luminous flux of the optical system 100 is favorably improved.

In some embodiments, the optical system 100 satisfies the conditional expression: sigma CT/sigma AT is more than or equal to 1.3 and less than or equal to 2.6; Σ CT is the sum of thicknesses of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, and the fifth lens L5 on the optical axis 110, and Σ AT is the sum of air spaces between two adjacent lenses of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, and the fifth lens L5 on the optical axis. Specifically, Σ CT/Σ AT may be: 1.327, 1.551, 1.674, 1.733, 1.829, 1.936, 2.015, 2.238, 2.471, or 2.511. When the above conditional expressions are satisfied, the central thicknesses of the lenses in the optical system 100 and the distances between the adjacent lenses can be reasonably configured, which is beneficial to making the distribution of the lenses more uniform, thereby being beneficial to smooth transition of light rays in the optical system 100, further being beneficial to eliminating high-order aberration, and improving the imaging quality of the optical system 100.

In some embodiments, the optical system 100 satisfies the conditional expression: f1/f34 is more than or equal to 0.8 and less than or equal to 1.2; wherein f1 is the effective focal length of the first lens L1, and f34 is the combined focal length of the third lens L3 and the fourth lens L4. Specifically, f1/f34 may be: 0.862, 0.887, 0.904, 0.925, 0.938, 0.952, 0.987, 1.022, 1.067 or 1.197. When the above conditional expressions are satisfied, the ratio of the effective focal length of the first lens element L1 to the combined focal length of the third lens element L3 and the fourth lens element L4 can be reasonably configured, so that the refractive power of the first lens element L1 is close to the combined refractive power of the third lens element L3 and the fourth lens element L4, and thus a similar symmetric structure is formed between the combination of the first lens element L1 and the third lens element L3 and the fourth lens element L4, which is favorable for correcting the aberration of the optical system 100 and improving the imaging quality of the optical system 100.

The reference wavelengths of the effective focal length and the combined focal length are 940 nm.

Based on the above description of the embodiments, more specific embodiments and drawings are set forth below for detailed description.

First embodiment

Referring to fig. 1 and fig. 2, fig. 1 is a schematic structural diagram of the optical system 100 in the first embodiment, and the optical system 100 includes, in order from an object side to an image side, a stop STO, a first lens element L1 with positive refractive power, a second lens element L2 with positive refractive power, a third lens element L3 with negative refractive power, a fourth lens element L4 with positive refractive power, and a fifth lens element L5 with negative refractive power. Fig. 2 is a graph of longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the first embodiment sequentially from left to right, where the reference wavelength is 940nm, and the other embodiments are the same.

The object-side surface S1 of the first lens element L1 is convex at a paraxial region 110 and convex at a peripheral region;

the image-side surface S2 of the first lens element L1 is concave at the paraxial region 110 and convex at the periphery;

the object-side surface S3 of the second lens element L2 is convex at a paraxial region 110 and concave at a peripheral region;

the image-side surface S4 of the second lens element L2 is concave at a paraxial region 110 and convex at a peripheral region;

the object-side surface S5 of the third lens element L3 is concave at a paraxial region 110 and concave at a peripheral region;

the image-side surface S6 of the third lens element L3 is convex at a paraxial region 110 and convex at a peripheral region;

the object-side surface S7 of the fourth lens element L4 is convex at a paraxial region 110 and concave at a peripheral region;

the image-side surface S8 of the fourth lens element L4 is concave at a paraxial region 110 and convex at a peripheral region;

the object-side surface S9 of the fifth lens element L5 is convex at a paraxial region 110 and concave at a peripheral region;

the image-side surface S10 of the fifth lens element L5 is concave at a paraxial region 110 and convex at a peripheral region.

The object-side and image-side surfaces of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, and the fifth lens L5 are aspheric.

It should be noted that, in the present application, when a surface of the lens is described as being convex at a position near the optical axis 110 (the central region of the surface), it is understood that the region of the surface of the lens near the optical axis 110 is convex. When a surface of a lens is described as concave at the circumference, it is understood that the surface is concave near the region of maximum effective radius. For example, when the surface is convex at a paraxial region 110 and also convex at a peripheral region, the shape of the surface from the center (the intersection of the surface with the optical axis 110) to the edge direction may be purely convex; or a convex shape at the center is firstly transited to a concave shape, and then becomes a convex shape near the maximum effective radius. Here, only examples are made to illustrate the relationship at the optical axis 110 and the circumference, and various shape structures (concave-convex relationship) of the surface are not fully embodied, but other cases can be derived from the above examples.

The first lens L1, the second lens L2, the third lens L3, the fourth lens L4 and the fifth lens L5 are all made of plastic.

Further, the optical system 100 satisfies the conditional expression: HFOV/FNO 29.851 deg; here, the HFOV is a half of the maximum field angle of the optical system 100, and the FNO is an f-number of the optical system 100. When the above conditional expressions are satisfied, the half field angle and the f-number of the optical system 100 can be reasonably arranged, so that the optical system 100 can have both a large field angle and a large aperture characteristic, and can satisfy both the requirement of large-range shooting and the requirement of large light flux of the TOF lens.

The optical system 100 satisfies the conditional expression: f/EPD is 1.33; where f is the effective focal length of the optical system 100 and EPD is the entrance pupil diameter of the optical system 100. Satisfying the above conditional expressions, the optical system 100 can have a large aperture characteristic, which is beneficial to the optical system 100 to obtain sufficient light entering amount, avoid the occurrence of dark corners around the imaging surface, and simultaneously is beneficial to improving the shooting effect of the optical system 100 in a low light environment; in addition, the increase of the aperture is also beneficial to reducing the size of the Airy's patch, so that the optical system 100 has a higher resolution limit, and the optical system 100 can meet the design requirement of high pixel by matching the reasonable refractive power of each lens in the optical system 100.

The optical system 100 satisfies the conditional expression: SD11/ImgH ═ 0.448; SD11 is half the maximum effective aperture of the object-side surface S1 of the first lens L1, and ImgH is half the image height corresponding to the maximum angle of view of the optical system 100. When the above conditional expressions are satisfied, the ratio of the maximum effective half aperture of the object-side surface S1 of the first lens L1 to the half image height of the optical system 100 can be reasonably configured, which is beneficial to reducing the step difference between the lenses in the optical system 100, thereby being beneficial to the smooth transition of the whole optical system 100, and in addition, being beneficial to improving the light flux of the optical system 100, thereby improving the relative illumination of the image.

The optical system 100 satisfies the conditional expression: TTL/ImgH is 1.700; wherein, TTL is a distance on an optical axis from an object-side surface of the first lens element to an image plane of the optical system, and ImgH is half of an image height corresponding to a maximum field angle of the optical system. When the above conditional expressions are satisfied, the ratio of the total optical length to the half-image height of the optical system 100 can be configured reasonably, which is beneficial to shortening the total optical length of the optical system 100, so that the optical system 100 can realize a miniaturized design.

The optical system 100 satisfies the conditional expression: 6.802 | f2/f1 |; where f2 is the effective focal length of the second lens L2, and f1 is the effective focal length of the first lens L1. When the above conditional expressions are satisfied, the ratio of the effective focal lengths of the first lens element L1 and the second lens element L2 can be reasonably configured, so that the refractive power of the second lens element L2 is not too close to the refractive power of the first lens element L1, and therefore, the light rays converged by the first lens element L1 can smoothly transit to each lens element on the image side through the second lens element L2, and simultaneously, the chromatic aberration on the balance axis of each lens element on the image side of the second lens element L2 is also facilitated, and the off-axis coma is corrected.

The optical system 100 satisfies the conditional expression: BF/TTL is 0.176; wherein, BF is the shortest distance from the image-side surface S10 of the fifth lens element L5 to the image plane of the optical system 100 along the optical axis 110, and TTL is the distance from the object-side surface S1 of the first lens element L1 to the image plane of the optical system 100 along the optical axis 110. When the above conditional expressions are satisfied, the rear focal ratio of the optical system 100 can be reasonably configured, the total length of the optical system 100 is shortened to realize the miniaturization design, and meanwhile, reasonable control of the chief ray incident angle from the outermost viewing field to the imaging surface is facilitated, and the decrease of the relative illumination caused by the overlarge chief ray incident angle from the outermost viewing field is avoided, so that the imaging quality of the optical system 100 is favorably improved.

The optical system 100 satisfies the conditional expression: SAG42/SAG51 ═ 1.060; SAG42 is the rise of the image side surface S8 of the fourth lens L4 at the maximum effective aperture, and SAG51 is the rise of the object side surface S9 of the fifth lens L5 at the maximum effective aperture. When the conditional expressions are satisfied, the ratio of the rise of the image-side surface S8 of the fourth lens L4 to the rise of the object-side surface S9 of the fifth lens L5 can be reasonably configured, so that the shape of the image-side surface S8 of the fourth lens L4 is matched with that of the object-side surface S9 of the fifth lens L5, and therefore the incident angle of light rays between the fourth lens L4 and the fifth lens L5 on the lens surface is favorably reduced, the off-axis chromatic aberration is favorably inhibited, and the luminous flux of the optical system 100 is favorably improved.

The optical system 100 satisfies the conditional expression: Σ CT/Σ AT 2.511; Σ CT is the sum of thicknesses of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, and the fifth lens L5 on the optical axis 110, and Σ AT is the sum of air spaces between two adjacent lenses of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, and the fifth lens L5 on the optical axis. When the above conditional expressions are satisfied, the central thicknesses of the lenses in the optical system 100 and the distances between the adjacent lenses can be reasonably configured, which is beneficial to making the distribution of the lenses more uniform, thereby being beneficial to smooth transition of light rays in the optical system 100, further being beneficial to eliminating high-order aberration, and improving the imaging quality of the optical system 100.

The optical system 100 satisfies the conditional expression: f1/f34 is 0.906; wherein f1 is the effective focal length of the first lens L1, and f34 is the combined focal length of the third lens L3 and the fourth lens L4. When the above conditional expressions are satisfied, the ratio of the effective focal length of the first lens element L1 to the combined focal length of the third lens element L3 and the fourth lens element L4 can be reasonably configured, so that the refractive power of the first lens element L1 is close to the combined refractive power of the third lens element L3 and the fourth lens element L4, and thus a similar symmetric structure is formed between the combination of the first lens element L1 and the third lens element L3 and the fourth lens element L4, which is favorable for correcting the aberration of the optical system 100 and improving the imaging quality of the optical system 100.

In addition, the parameters of the optical system 100 are given in table 1. Among them, the image plane S13 in table 1 may be understood as an imaging plane of the optical system 100. The elements from the object plane (not shown) to the image plane S13 are sequentially arranged in the order of the elements from top to bottom in table 1. The Y radius in table 1 is the radius of curvature of the object-side or image-side surface at the optical axis 110 for the corresponding surface number. Surface numbers S1 and S2 denote an object-side surface S1 and an image-side surface S2 of the first lens L1, respectively, that is, in the same lens, a surface with a smaller surface number is an object-side surface, and a surface with a larger surface number is an image-side surface. The first numerical value in the "thickness" parameter column of the first lens element L1 is the thickness of the lens element along the optical axis 110, and the second numerical value is the distance between the image-side surface and the rear surface of the lens element along the image-side direction along the optical axis 110.

Note that, in this embodiment and the following embodiments, the optical system 100 may not be provided with the filter L6, but the distance from the image-side surface S10 of the fifth lens L5 to the image surface S13 is kept constant at this time.

In the first embodiment, the effective focal length f of the optical system 100 is 2.33mm, the total optical length TTL is 3.33mm, the maximum field angle FOV is 75deg, and the f-number FNO is 1.33. The optical system 100 has excellent image quality, can be designed in a compact size, and has a large aperture characteristic.

The reference wavelength of the focal length of each lens is 940nm, the reference wavelength of the refractive index and the abbe number of each lens is 587.56nm, and the same is true for other embodiments.

TABLE 1

Further, aspheric coefficients of the image-side surface or the object-side surface of each lens of the optical system 100 are given by table 2. Wherein, the surface numbers from S1 to S10 represent the image side or the object side S1 to S10, respectively. And K-a20 from top to bottom respectively indicate the types of aspheric coefficients, where K indicates a conic coefficient, a4 indicates a quartic aspheric coefficient, a6 indicates a sextic aspheric coefficient, A8 indicates an octal aspheric coefficient, and so on. In addition, the aspherical surface coefficient formula is as follows:

wherein Z is the distance from the corresponding point on the aspheric surface to the plane tangent to the surface vertex, r is the distance from the corresponding point on the aspheric surface to the optical axis 110, c is the curvature of the aspheric surface vertex, K is the conic coefficient, and Ai is the coefficient corresponding to the i-th high-order term in the aspheric surface type formula.

TABLE 2

Fig. 2 includes a Longitudinal Spherical Aberration diagram (Longitudinal Spherical Aberration) of the optical system 100, in which the Longitudinal Spherical Aberration curve represents the deviation of the converging focus of the light rays with different wavelengths after passing through the lens, the ordinate represents the Normalized Pupil coordinate (Normalized Pupil coordiator) from the Pupil center to the Pupil edge, and the abscissa represents the focus deviation, i.e., the distance (in mm) from the image plane to the intersection of the light rays and the optical axis 110. It can be known from the longitudinal spherical aberration diagram that the convergent focus deviation degrees of the light rays with different wavelengths in the first embodiment tend to be consistent, and the diffuse speckles or color halos in the imaging picture are effectively inhibited. Fig. 2 also includes an astigmatism graph (ASTIGMATIC FIELD CURVES) of the optical system 100 in which the abscissa represents focus offset and the ordinate represents image height in mm, and the S-curve in the astigmatism graph represents sagittal curvature at 940nm and the T-curve represents meridional curvature at 940 nm. As can be seen from the figure, the curvature of field of the optical system 100 is small, the curvature of field and astigmatism of each field are well corrected, and the center and the edge of the field have clear images. Fig. 2 further includes a DISTORTION plot (distorrion) of the optical system 100, where the DISTORTION plot represents DISTORTION magnitude values corresponding to different angles of view, where the abscissa represents DISTORTION value in mm and the ordinate represents image height in mm. As can be seen from the figure, the image distortion caused by the main beam is small, and the imaging quality of the system is excellent.

Second embodiment

Referring to fig. 3 and 4, fig. 3 is a schematic structural diagram of the optical system 100 in the second embodiment, in which the optical system 100 includes, in order from an object side to an image side, a stop STO, a first lens element L1 with positive refractive power, a second lens element L2 with positive refractive power, a third lens element L3 with negative refractive power, a fourth lens element L4 with positive refractive power, and a fifth lens element L5 with negative refractive power. Fig. 4 is a graph of longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the second embodiment, which is shown from left to right.

the image-side surface S2 of the first lens element L1 is concave at the paraxial region 110 and concave at the periphery;

In addition, the parameters of the optical system 100 are given in table 3, and the definitions of the parameters can be obtained from the first embodiment, which is not described herein.

TABLE 3

Further, the aspheric coefficients of the image-side surface or the object-side surface of each lens of the optical system 100 are shown in table 4, and the definitions of the parameters can be obtained from the first embodiment, which is not repeated herein.

TABLE 4

According to the provided parameter information, the following data can be deduced:

HFOV/FNO(deg)	28.195	BF/TTL	0.162
				f/EPD	1.33	SAG42/SAG51	0.066
SD11/ImgH	0.491	∑CT/∑AT	1.647
				TTL/ImgH	1.848	f1/f34	0.966
\|f2/f1\|	4.819

in addition, as can be seen from the aberration diagram in fig. 4, the longitudinal spherical aberration, astigmatism and distortion of the optical system 100 are well controlled, so that the optical system 100 of this embodiment has good imaging quality.

Third embodiment

Referring to fig. 5 and 6, fig. 5 is a schematic structural diagram of the optical system 100 in the third embodiment, in which the optical system 100 includes, in order from an object side to an image side, a stop STO, a first lens element L1 with positive refractive power, a second lens element L2 with positive refractive power, a third lens element L3 with negative refractive power, a fourth lens element L4 with positive refractive power, and a fifth lens element L5 with negative refractive power. Fig. 6 is a graph of longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the third embodiment, from left to right.

the object-side surface S5 of the third lens element L3 is convex at a paraxial region 110 and concave at a peripheral region;

the image-side surface S6 of the third lens element L3 is concave at a paraxial region 110 and convex at a peripheral region;

In addition, the parameters of the optical system 100 are given in table 5, and the definitions of the parameters can be obtained from the first embodiment, which is not described herein again.

TABLE 5

Further, the aspheric coefficients of the image-side surface or the object-side surface of each lens of the optical system 100 are shown in table 6, and the definitions of the parameters can be obtained from the first embodiment, which is not repeated herein.

TABLE 6

And, according to the above provided parameter information, the following data can be derived:

HFOV/FNO(deg)	27.301	BF/TTL	0.164
				f/EPD	1.32	SAG42/SAG51	1.192
SD11/ImgH	0.500	∑CT/∑AT	1.385
				TTL/ImgH	1.650	f1/f34	0.929
\|f2/f1\|	2.349

in addition, as can be seen from the aberration diagram in fig. 6, the longitudinal spherical aberration, astigmatism and distortion of the optical system 100 are well controlled, so that the optical system 100 of this embodiment has good imaging quality.

Fourth embodiment

Referring to fig. 7 and 8, fig. 7 is a schematic structural diagram of the optical system 100 in the fourth embodiment, in which the optical system 100 includes, in order from an object side to an image side, a stop STO, a first lens element L1 with positive refractive power, a second lens element L2 with positive refractive power, a third lens element L3 with negative refractive power, a fourth lens element L4 with positive refractive power, and a fifth lens element L5 with negative refractive power. Fig. 8 is a graph of longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the fourth embodiment, which is shown from left to right.

In addition, the parameters of the optical system 100 are given in table 7, and the definitions of the parameters can be obtained from the first embodiment, which is not described herein.

TABLE 7

Further, the aspheric coefficients of the image-side surface or the object-side surface of each lens of the optical system 100 are shown in table 8, and the definitions of the parameters can be obtained from the first embodiment, which is not repeated herein.

TABLE 8

HFOV/FNO(deg)	28.682	BF/TTL	0.145
				f/EPD	1.28	SAG42/SAG51	3.375
SD11/ImgH	0.514	∑CT/∑AT	1.619
				TTL/ImgH	1.798	f1/f34	0.862
\|f2/f1\|	4.190

in addition, as can be seen from the aberration diagram in fig. 8, the longitudinal spherical aberration, astigmatism, and distortion of the optical system 100 are well controlled, so that the optical system 100 of this embodiment has good imaging quality.

Fifth embodiment

Referring to fig. 9 and 10, fig. 9 is a schematic structural diagram of the optical system 100 in the fifth embodiment, in which the optical system 100 includes, in order from an object side to an image side, a stop STO, a first lens element L1 with positive refractive power, a second lens element L2 with negative refractive power, a third lens element L3 with positive refractive power, a fourth lens element L4 with positive refractive power, and a fifth lens element L5 with negative refractive power. Fig. 10 is a graph showing the longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the fifth embodiment from left to right.

In addition, the parameters of the optical system 100 are given in table 9, and the definitions of the parameters can be obtained from the first embodiment, which is not described herein.

TABLE 9

Further, the aspheric coefficients of the image-side surface or the object-side surface of each lens of the optical system 100 are shown in table 10, and the definitions of the parameters can be obtained from the first embodiment, which is not repeated herein.

Watch 10

HFOV/FNO(deg)	31.250	BF/TTL	0.137
				f/EPD	1.19	SAG42/SAG51	0.799
SD11/ImgH	0.544	∑CT/∑AT	1.327
				TTL/ImgH	1.824	f1/f34	1.197
\|f2/f1\|	16.812

in addition, as can be seen from the aberration diagram in fig. 10, the longitudinal spherical aberration, astigmatism, and distortion of the optical system 100 are well controlled, so that the optical system 100 of this embodiment has good imaging quality.

Referring to fig. 11, in some embodiments, the optical system 100 may be assembled with the photosensitive element 210 to form the image capturing module 200. At this time, the light-sensing surface of the light-sensing element 210 may be regarded as the image surface S13 of the optical system 100. The image capturing module 200 may further include a filter L6, wherein the filter L6 is disposed between the image side surface S10 and the image surface S13 of the fifth lens element L5. In some embodiments, the optical filter L6 is capable of transmitting 930nm to 950nm wavelength infrared light. Specifically, the photosensitive element 210 may be a Charge Coupled Device (CCD) or a Complementary Metal-Oxide Semiconductor (CMOS) Device. The image capturing module 200 with the optical system 100 has good imaging quality and large aperture characteristics, so as to satisfy the requirement of a TOF lens for large light flux.

Referring to fig. 11 and 12, in some embodiments, the image capturing module 200 may be applied to an electronic device 300, the electronic device includes a housing 310, and the image capturing module 200 is disposed in the housing 310. Specifically, the electronic apparatus 300 may be, but is not limited to, a wearable device such as a mobile phone, a video phone, a smart phone, an electronic book reader, a vehicle-mounted image capturing apparatus such as a car recorder, or a smart watch. When the electronic device 300 is a smartphone, the housing 310 may be a middle frame of the electronic device 300. The image capturing module 200 is adopted in the electronic device 300, so that the electronic device has good imaging quality and a large aperture characteristic, and is favorable for the application of the electronic device in the TOF detection field.

Further, in some embodiments, where the electronic device 300 is used in the field of TOF detection, the electronic device 300 may be a time-of-flight (TOF) based infrared detection device or an apparatus configured with infrared detection functionality. The electronic device 300 further includes a projection module 320, the projection module 320 is configured to emit infrared light to the object to be measured, and the infrared light emitted by the projection module 320 is reflected by the object to be measured and then received by the image capturing module 200, so as to obtain three-dimensional depth information of the object to be measured, and implement a three-dimensional detection function.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. An optical system comprising, in order from an object side to an image side along an optical axis:

a third lens element with refractive power;

and the optical system satisfies the following conditional expression:

25deg≤HFOV/FNO≤33deg；

2. The optical system according to claim 1, wherein the following conditional expression is satisfied:

1.1≤f/EPD≤1.4；

where f is the effective focal length of the optical system and EPD is the entrance pupil diameter of the optical system.

3. The optical system according to claim 1, wherein the following conditional expression is satisfied:

0.4≤SD11/ImgH≤0.6；

wherein SD11 is half of the maximum effective aperture of the object-side surface of the first lens, and ImgH is half of the image height corresponding to the maximum angle of view of the optical system.

4. The optical system according to claim 1, wherein the following conditional expression is satisfied:

1.6≤TTL/ImgH≤1.9；

wherein, TTL is a distance on an optical axis from an object-side surface of the first lens element to an image plane of the optical system, and ImgH is half of an image height corresponding to a maximum field angle of the optical system;

and/or the optical system satisfies the following conditional expression:

0.8≤f1/f34≤1.2；

wherein f1 is an effective focal length of the first lens, and f34 is a combined focal length of the third lens and the fourth lens.

5. The optical system according to claim 1, wherein the following conditional expression is satisfied:

2≤|f2/f1|≤17；

wherein f2 is the effective focal length of the second lens, and f1 is the effective focal length of the first lens.

6. The optical system according to claim 1, wherein the following conditional expression is satisfied:

0.1≤BF/TTL≤0.2；

wherein, BF is the shortest distance from the image side surface of the fifth lens element to the imaging surface of the optical system in the optical axis direction, and TTL is the distance from the object side surface of the first lens element to the imaging surface of the optical system in the optical axis direction.

7. The optical system according to claim 1, wherein the following conditional expression is satisfied:

0＜SAG42/SAG51≤3.4；

and SAG42 is the rise of the image side surface of the fourth lens at the maximum effective aperture, and SAG51 is the rise of the object side surface of the fifth lens at the maximum effective aperture.

8. The optical system according to claim 1, wherein the following conditional expression is satisfied:

1.3≤∑CT/∑AT≤2.6；

Σ CT is the sum of thicknesses of the first lens, the second lens, the third lens, the fourth lens, and the fifth lens on the optical axis, and Σ AT is the sum of air spaces of adjacent two lenses of the first lens, the second lens, the third lens, the fourth lens, and the fifth lens on the optical axis.

9. An image capturing module, comprising a photosensitive element and the optical system of any one of claims 1 to 8, wherein the photosensitive element is disposed on an image side of the optical system.

10. An electronic device, comprising a housing and the image capturing module of claim 9, wherein the image capturing module is disposed on the housing.