Patent Publication Number: US-2022236535-A1

Title: Optical system, image capturing module, and electronic device

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a national stage, filed under 35 U.S.C. § 371, of International Application No. PCT/CN2020/083697, filed on Apr. 8, 2020, and entitled “OPTICAL SYSTEM, IMAGE CAPTURING MODULE, AND ELECTRONIC DEVICE”, the content of which is incorporated herein in entirety by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to the field of photographing, and more particularly, to an optical system, an image capturing module, and an electronic device. 
     BACKGROUND 
     With the continuous development of electronic devices such as smart phones and tablet computers, photographing functions have become indispensable functions in the electronic devices. The volume of the electronic devices tends to become more and more miniaturized, which also puts forward higher requirements for the size of the optical system in the electronic devices. However, the head of the current camera lens is usually large, and it is difficult to meet the requirements of the miniaturization design of the electronic devices. 
     SUMMARY 
     According to various embodiments of the present disclosure, an optical imaging system, an image capturing module, and an electronic device are provided. 
     An optical system, sequentially arranged from an object side to an image side, includes: 
     a first lens having a positive refractive power; 
     a second lens having a refractive power; 
     a third lens having a negative refractive power, an object side surface and an image side surface of the third lens being both concave at their circumferences; 
     a fourth lens having a negative refractive power; 
     a fifth lens having a positive refractive power, at least one of an object side surface and an image side surface of the fifth lens having an inflection point; and 
     a sixth lens having a negative refractive power; 
     the optical system satisfies the following relational expressions: 
     
       
         
           
             
               0.60 
               &lt; 
               
                 CT 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 1 
                 ⁢ 
                 
                   / 
                 
                 ⁢ 
                 SD 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 11 
               
               &lt; 
               1.01 
             
             ; 
           
         
       
       
         
           
             
               5.5 
               &lt; 
               
                 TTL 
                 ⁢ 
                 
                   / 
                 
                 ⁢ 
                 CT 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 1 
               
               &lt; 
               9.0 
             
             ; 
           
         
       
     
     where CT1 is a thickness of the first lens on an optical axis, SD11 is half of a maximum effective aperture of an object side surface of the first lens, and TTL is a distance from the object side surface of the first lens to an imaging plane of the optical system on the optical axis. 
     An image capturing module includes a photosensitive element and the optical system described above, and the photosensitive element is arranged on the image side of the optical system. 
     An electronic device includes a housing and the image capturing module described above, and the image capturing module is mounted on the housing. 
     The details of one or more embodiments of the present disclosure are set forth in the accompanying drawings and the description below. Other features, objects and advantages of the present disclosure will become apparent from the description, the accompanying drawings, and the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       To better describe and illustrate the embodiments and/or examples of the disclosure disclosed herein, reference may be made to one or more accompanying drawings. The additional details or examples used to describe the accompanying drawings are not to be construed as limiting the scope of any one of the disclosed disclosure, the presently described embodiments and/or examples, and the presently understood preferred mode of the disclosure. 
         FIG. 1  is a schematic view of an optical system in a first embodiment of the present disclosure. 
         FIG. 2  is graphs of spherical aberration, astigmatism, and distortion of the optical system in the first embodiment of the present disclosure. 
         FIG. 3  is a schematic view of an optical system in a second embodiment of the present disclosure. 
         FIG. 4  is graphs of spherical aberration, astigmatism, and distortion of the optical system in the second embodiment of the present disclosure. 
         FIG. 5  is a schematic view of an optical system in a third embodiment of the present disclosure. 
         FIG. 6  is graphs of spherical aberration, astigmatism, and distortion of the optical system in the third embodiment of the present disclosure. 
         FIG. 7  is a schematic view of an optical system in a fourth embodiment of the present disclosure. 
         FIG. 8  is graphs of spherical aberration, astigmatism, and distortion of the optical system in the fourth embodiment of the present disclosure. 
         FIG. 9  is a schematic view of an optical system in a fifth embodiment of the present disclosure. 
         FIG. 10  is graphs of spherical aberration, astigmatism, and distortion of the optical system in the fifth embodiment of the present disclosure. 
         FIG. 11  is a schematic view of an optical system in a sixth embodiment of the present disclosure. 
         FIG. 12  is graphs of spherical aberration, astigmatism, and distortion of the optical system in the sixth embodiment of the present disclosure. 
         FIG. 13  is a schematic view of an image capturing module in an embodiment of the present disclosure. 
         FIG. 14  is a schematic view of an electronic device in an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     In order to facilitate the understanding of the present disclosure, the present disclosure will be described more fully hereinafter with reference to the related accompanying drawings. Preferable embodiments of the present disclosure are presented in the accompanying drawings. However, the present disclosure may be embodied in many different forms and is not limited to the embodiments described herein. Rather, the purpose of providing these embodiments is to make the content of the present disclosure more thorough and comprehensive. 
     It should be noted that when an element is referred to as being “fixed to” another element, it can be directly fixed to another element or indirectly connected to another element with a mediating element. When an element is considered to be “connected to” another element, it can be directly connected to another element or indirectly connected to another element with a mediating element. The terms “in”, “outer”, “left”, “right”, and the like used herein are for illustrative purposes only and are not intended to be the only embodiments. 
     Referring to  FIG. 1 , in some embodiments of the present disclosure, an optical system  100  includes, sequentially arranged from an object side to an image side, a first lens L 1 , a second lens L 2 , a third lens L 3 , a fourth lens L 4 , a fifth lens L 5 , and a sixth lens L 6 . Specifically, the first lens L 1  includes an object side surface S 1  and an image side surface S 2 , the second lens L 2  includes an object side surface S 3  and an image side surface S 4 , the third lens L 3  includes an object side surface S 5  and an image side surface S 6 , the fourth lens L 4  includes an object side surface S 7  and an image side surface S 8 , the fifth lens L 5  includes an object side surface S 9  and an image side surface S 10 , and the sixth lens L 6  includes an object side surface S 11  and an image side surface S 12 . 
     The first lens L 1  has a positive refractive power, and the second lens L 2  has a refractive power. The third lens L 3  has a negative refractive power, and the object side surface S 5  and the image side surface S 6  of the third lens L 3  are both concave at their circumferences. The fourth lens L 4  has a negative refractive power. The fifth lens L 5  has a positive refractive power, and at least one of the object side surface S 9  and the image side surface S 10  of the fifth lens L 5  has an inflection point to correct the aberration of the off-axis field of view and improve the imaging quality of the optical system  100 . The lenses of the optical system  100  are arranged coaxially, and central axes of the lenses are on the same straight line, this straight line is an optical axis of the optical system  100 . 
     In addition, in some embodiments, the optical system  100  is provided with an optical stop STO, and the optical stop STO may be arranged on an object side of the first lens L 1 . In some embodiments, the optical system  100  further includes an infrared filter L 7  arranged on an image side of the sixth lens L 6 , and the infrared filter L 7  includes an object side surface S 13  and an image side surface S 14 . Further, the optical system  100  further includes an image plane S 15  located on the image side of the sixth lens L 6 . Incident light can be imaged on the image plane S 15  after being adjusted by the first lens L 1 , the second lens L 2 , the third lens L 3 , the fourth lens L 4 , the fifth lens L 5 , and the sixth lens L 6 . It is worth noting that the infrared filter L 7  may be an infrared cut-off filter, which is configured to filter out interference light and prevent the interference light from reaching the image plane S 15  of the optical system  100  and affecting normal imaging. 
     In some embodiments, the object side surfaces and the image side surfaces of the lenses of the optical system  100  are all aspherical surfaces. The use of the aspherical structure can improve the flexibility of the lens design, effectively correct spherical aberration, and improve imaging quality. In some other embodiments, the object side surface S 9  and the image side surface S 10  of the fifth lens L 5  are both aspherical surfaces, while the object side surfaces and the image side surfaces of the remaining lenses of the optical system  100  may be all spherical surfaces. It should be noted that the aforementioned embodiments are merely examples of some embodiments of the present disclosure. In some embodiments, the surfaces of the remaining lenses in the optical system  100  may be any combination of aspherical surfaces or spherical surfaces. 
     In some embodiments, the lenses in the optical system  100  may be all made of glass or plastic. The use of plastic lenses can reduce the weight of the optical system  100  and reduce the production cost, which, in addition with the smaller size of the optical system, can achieve a light and miniaturization design of the optical system. The use of glass lenses enables the optical system  100  to have excellent optical performance and higher temperature resistance. It should be noted that the lenses in the optical system  100  can also be made of materials of any combination of glass and plastic, and not necessarily be all made of glass or plastic. 
     It should be noted that the first lens L 1  does not mean that there is only one lens. In some embodiments, there may also be two or more lenses in the first lens L 1 , and the two or more lenses can form a cemented lens. A surface of the cemented lens closest to the object side can be regarded as the object side surface S 1 , and a surface of the cemented lens closest to the image side can be regarded as the image side surface S 2 . Alternatively, the lenses of the first lens L 1  do not form a cemented lens, but the distances between the lenses are relatively fixed. In this case, an object side surface of the lens closest to the object side is the object side surface S 1 , and an image side surface of the lens closest to the image side is the image side surface S 2 . In addition, in some embodiments, the number of lenses in the second lens L 2 , the third lens L 3 , the fourth lens L 4 , the fifth lens L 5 , or the sixth lens L 6  can also be greater than or equal to two, and any adjacent lenses can form a cemented lens or can be a non-cemented lens. 
     Further, in some embodiments, the optical system  100  satisfies a relational expression: 0.60&lt;CT1/SD11&lt;1.01; where CT1 is a thickness of the first lens L 1  on the optical axis, that is, a center thickness of the first lens L 1 , and SD11 is half of a maximum effective aperture of the object side surface S 1  of the first lens L 1 . Specifically, CT1/SD11 may be 0.64, 0.69, 0.73, 0.75, 0.82, 0.86, 0.89, 0.91, 0.93, or 0.98. When the above relational expression is satisfied, the first lens L 1  can be reasonably configured, so that the head of the camera lens is smaller, thereby satisfying the requirements of the miniaturization design of the electronic device. 
     In some embodiments, the optical system  100  satisfies a relational expression: 5.5&lt;TTL/CT1&lt;9.0; where CT1 is the thickness of the first lens L 1  on the optical axis, and TTL is a distance from the object side surface S 1  of the first lens L 1  to the image plane S 15  on the optical axis. Specifically, TTL/CT1 may be 5.81, 5.92, 6.31, 6.58, 6.85, 6.92, 7.12, 7.34, 7.58, or 7.69. When the above relational expression is satisfied, the first lens L 1  and a total system length of the optical system  100  can be reasonably configured, the total system length of the optical system  100  can be made smaller while ensuring that the head of the camera lens is small, which further satisfies the requirements of the miniaturization design of the electronic devices. In addition, it can also be ensured that the first lens L 1  has a sufficient thickness, so that the yield rate of the first lens L 1  during processing and molding is higher, and thus the yield rate of the assembly of the optical system  100  is further improved. 
     In some embodiments, the optical system  100  satisfies a relational expression: 2.2≤FNO≤2.6; where FNO is an f-number of the optical system  100 . Specifically, the FNO may be 2.30, 2.32, 2.36, 2.39, 2.41, 2.47, 2.48, 2.51, 2.53, or 2.55. When the above relational expression is satisfied, while ensuring that the optical system  100  has a sufficient amount of light flux, it is also beneficial to make the head of the camera lens smaller. 
     In some embodiments, the optical system  100  satisfies a relational expression: 1&lt;f3/f4&lt;10; where f3 is an effective focal length of the third lens L 3 , and f4 is an effective focal length of the fourth lens L 4 . Specifically, f3/f4 maybe 1.336, 1.735, 2.208, 2.896, 3.528, 3.619, 4.626, 5.462, 7.264, or 9.218. When the above relational expression is satisfied, the third lens L 3  and the fourth lens L 4  can be reasonably configured, so as to effectively expand the field of view of the optical system  100 , thereby reducing the total system length of the optical system  100 , and satisfying the requirements of the miniaturization design. 
     In some embodiments, the optical system  100  satisfies a relational expression: 2.0&lt;f4/f1+f5/f6&lt;4.0; where f1 is an effective focal length of the first lens L 1 , f4 is the effective focal length of the fourth lens L 4 , f5 is an effective focal length of the fifth lens L 5 , and f6 is an effective focal length of the sixth lens L 6 . Specifically, f4/f1+f5/f6 may be 3.11, 3.16, 3.19, 3.22, 3.27, 3.41, 3.45, 3.49, 3.53, or 3.58. When the above relational expression is satisfied, the refractive powers of the first lens L 1 , the fourth lens L 4 , the fifth lens L 5 , and the sixth lens L 6  can be reasonably configured, so as to ensure that the positive and negative spherical aberrations of the optical system  100  can be balanced with each other, thereby improving the imaging quality of the optical system  100 . 
     In some embodiments, the optical system  100  satisfies a relational expression: 1.0&lt;f/f12&lt;1.5; where f is a total effective focal length of the optical system  100 , and f12 is a combined focal length of the first lens L 1  and the second lens L 2 . Specifically, f/f12 may be 1.05, 1.06, 1.07, 1.09, 1.10, 1.12, 1.15, 1.16, 1.17, or 1.18. When the above relational expression is satisfied, the effective focal length of the optical system  100  and the combined focal length of the first lens L 1  and the second lens L 2  can be reasonably configured, so as to effectively shorten the total system length of the optical system  100  and avoid the excessive increase of high-order spherical aberration of the optical system  100 , thereby improving the imaging quality of the optical system  100 . 
     In some embodiments, the optical system  100  satisfies a relational expression: TT/ImgH&lt;1.1; where TT is a distance from the object side surface S 1  of the first lens L 1  to the image side surface S 12  of the sixth lens L 6  on the optical axis, and ImgH is half of a diagonal length of an effective pixel area of the optical system  100  on an imaging plane. Specifically, TT/ImgH may be 1.05, 1.06, 1.07, or 1.08. When the above relational expression is satisfied, the imaging quality of the optical system  100  on the image plane S 15  can be improved, and the total system length of the optical system  100  can be effectively shortened, which further satisfies the requirements of the miniaturization design of the lens. 
     In some embodiments, the optical system  100  satisfies a relational expression: −1.5&lt;R9/R10&lt;0; where R9 is a radius of curvature of the object side surface S 9  of the fifth lens L 5  at the optical axis, and R10 is a radius of curvature of the image side surface S 10  of the fifth lens L 5  at the optical axis. Specifically, R9/R10 may be −1.19, −1.15, −1.11, −1.09, −0.98, −0.92, −0.88, −0.82, −0.75, or −0.72. When the above relational expression is satisfied, the relation between the object side surface S 9  and the image side surface S 10  of the fifth lens L 5  can be reasonably restricted, so that the deflection angle of the optical system  100  can be reasonably distributed, and the astigmatism of the off-axis field of view of the optical system  100  can be improved, thereby improving the imaging quality of the optical system  100 . 
     In some embodiments, the optical system  100  satisfies a relational expression: 1&lt;|f6|/R12&lt;2; where f6 is the effective focal length of the sixth lens L 6 , and R12 is a radius of curvature of the image side surface S 12  of the sixth lens L 6  at the optical axis. Specifically, |f6|/R12 may be 1.82, 1.84, 1.85, 1.88, 1.89, 1.90, 1.92, 1.96, 1.97, or 1.98. When the above relational expression is satisfied, the effective focal length of the sixth lens L 6  and the image side surface S 12  can be reasonably configured, so as to reduce the incident angle of light rays reaching the image plane S 15  of the optical system  100 , so that the optical system  100  can be more easily matched with a photosensitive element. 
     In some embodiments, the optical system  100  satisfies a relational expression: 1.0&lt;CT5/|SAG51|&lt;5.0; where CT5 is a thickness of the fifth lens L 5  on the optical axis, and SAG51 is a sagittal height of the object side surface S 9  of the fifth lens L 5 , that is, a distance in a direction parallel to the optical axis from an intersection of the object side surface S 9  of the fifth lens L 5  on the optical axis to a maximum effective radius position of the object side surface S 9  of the fifth lens L 5 . Specifically, CT5/|SAG51| may be 1.91, 2.13, 2.52, 2.68, 3.22, 3.34, 3.87, 3.92, 4.13, or 4.26. When the above relational expression is satisfied, the fifth lens L 5  can be reasonably configured, so that the surface shape of the fifth lens L 5  can be more reasonable, so as to reduce the defect rate of the fifth lens L 5  during the processing and molding. In addition, the aberrations generated in the optical system  100  can be corrected, thereby further improving the imaging quality of the optical system  100 . 
     According to the aforementioned descriptions of the various embodiments, more specific embodiments and accompanying drawings are provided below for detailed description. 
     First Embodiment 
     Referring to  FIGS. 1 and 2 ,  FIG. 1  is a schematic view of an optical system  100  in the first embodiment. The optical system  100  includes, sequentially arranged from an object side to an image side, an optical stop STO, a first lens L 1  having a positive refractive power, a second lens L 2  having a negative refractive power, a third lens L 3  having a negative refractive power, a fourth lens L 4  having a negative refractive power, a fifth lens L 5  having a positive refractive power, and a sixth lens L 6  having a negative refractive power.  FIG. 2  is, sequentially from left to right, graphs of spherical aberration, astigmatism, and distortion of the optical system  100  in the first embodiment, where the graphs of astigmatism and distortion are both graphs at 555 nm, which are the same in other embodiments. 
     An object side surface S 1  of the first lens L 1  is convex at its paraxial position and convex at its circumference. 
     An image side surface S 2  of the first lens L 1  is planar at its paraxial position and planar at its circumference. 
     An object side surface S 3  of the second lens L 2  is planar at its paraxial position and planar at its circumference. 
     An image side surface S 4  of the second lens L 2  is concave at its paraxial position and convex at its circumference. 
     An object side surface S 5  of the third lens L 3  is concave at its paraxial position and concave at its circumference. 
     An image side surface S 6  of the third lens L 3  is convex at its paraxial position and concave at its circumference. 
     An object side surface S 7  of the fourth lens L 4  is concave at its paraxial position and concave at its circumference. 
     An image side surface S 8  of the fourth lens L 4  is concave at its paraxial position and convex at its circumference. 
     An object side surface S 9  of the fifth lens L 5  is convex at its paraxial position and concave at its circumference. 
     An image side surface S 10  of the fifth lens L 5  is convex at its paraxial position and convex at its circumference. 
     An object side surface S 11  of the sixth lens L 6  is convex at its paraxial position and convex at its circumference. 
     An image side surface S 12  of the sixth lens L 6  is concave at its paraxial position and concave at its circumference. 
     The image side surface S 2  of the first lens L 1  and the object side surface S 3  of the second lens L 2  are planar, while the object side surface S 1  of the first lens L 1 , the image side surface S 4  of the second lens L 2 , and the object side surfaces and the image side surfaces of the third lens L 3 , the fourth lens L 4 , the fifth lens L 5 , and the sixth lens L 6  are all aspherical. 
     It should be noted that, in the present disclosure, when describing that a surface of a lens is convex at its paraxial position (a central area of this side surface), it can be understood as that an area of this surface of the lens near the optical axis is convex. When describing that a surface of a lens is concave at its circumference, it can be understood as that an area of this surface near the maximum effective radius is concave. For example, when this surface is convex at the optical axis and is also convex at its circumference, a shape of this surface in a direction from the center (the optical axis) to the edge may be completely convex, or the surface may be firstly transited from a convex shape at the center to a concave shape, and then become a convex surface at a position close to its maximum effective radius. These are only examples to illustrate the relation between the positions of the optical axis and the circumference. The various shapes and structures (concave-convex relationship) of the surface are not fully described, but other situations can be derived from the above examples. 
     The first lens L 1 , the second lens L 2 , the third lens L 3 , the fourth lens L 4 , the fifth lens L 5 , and the sixth lens L 6  are all made of plastic. 
     Further, the optical system  100  satisfies a relational expression: CT1/SD11=1.001; where CT1 is a thickness of the first lens L 1  on the optical axis, that is, a center thickness of the first lens L 1 , and SD11 is half of a maximum effective aperture of the object side surface S 1  of the first lens L 1 . When the above relational expression is satisfied, the first lens L 1  can be reasonably configured, so that the head of the camera lens is smaller, thereby satisfying the requirements of the miniaturization design of the electronic device. 
     The optical system  100  satisfies a relational expression: TTL/CT1=5.80; where CT1 is the thickness of the first lens L 1  on the optical axis, and TTL is a distance from the object side surface S 1  of the first lens L 1  to the image plane S 15 . When the above relational expression is satisfied, the first lens L 1  and a total system length of the optical system  100  can be reasonably configured, the total system length of the optical system  100  can be made smaller while ensuring that the head of the camera lens is small, which further satisfies the requirements of the miniaturization design of the electronic devices. In addition, it can also be ensured that the first lens L 1  has a sufficient thickness, so that the yield rate of the first lens L 1  during processing and molding is higher, and thus the yield rate of the assembly of the optical system  100  is further improved. 
     The optical system  100  satisfies a relational expression: FNO=2.54; where FNO is an f-number of the optical system  100 . When the above relational expression is satisfied, while ensuring that the optical system  100  has a sufficient amount of light flux, it is also beneficial to make the head of the camera lens smaller. 
     The optical system  100  satisfies a relational expression: f3/f4=9.218; where f3 is an effective focal length of the third lens L 3 , and f4 is an effective focal length of the fourth lens L 4 . When the above relational expression is satisfied, the third lens L 3  and the fourth lens L 4  can be reasonably configured, so as to effectively expand the field of view of the optical system  100 , thereby reducing the total system length of the optical system  100 , and satisfying the requirements of the miniaturization design. 
     The optical system  100  satisfies a relational expression: f4/f1+f5/f6=3.58; where f1 is an effective focal length of the first lens L 1 , f4 is the effective focal length of the fourth lens L 4 , f5 is an effective focal length of the fifth lens L 5 , and f6 is an effective focal length of the sixth lens L 6 . When the above relational expression is satisfied, the refractive powers of the first lens L 1 , the fourth lens L 4 , the fifth lens L 5 , and the sixth lens L 6  can be reasonably configured, so as to ensure that the positive and negative spherical aberrations of the optical system  100  can be balanced with each other, thereby improving the imaging quality of the optical system  100 . 
     The optical system  100  satisfies a relational expression: f/f12=1.05; where f is a total effective focal length of the optical system  100 , and f12 is a combined focal length of the first lens L 1  and the second lens L 2 . When the above relational expression is satisfied, the effective focal length of the optical system  100  and the combined focal length of the first lens L 1  and the second lens L 2  can be reasonably configured, so as to effectively shorten the total system length of the optical system  100  and avoid the excessive increase of high-order spherical aberration of the optical system  100 , thereby improving the imaging quality of the optical system  100 . 
     The optical system  100  satisfies a relational expression: TT/ImgH=1.05; where TT is a distance from the object side surface S 1  of the first lens L 1  to the image side surface S 12  of the sixth lens L 6  on the optical axis, and ImgH is half of a diagonal length of an effective pixel area of the optical system  100  on the imaging plane. When the above relational expression is satisfied, the imaging quality of the optical system  100  on the image plane S 15  can be improved, and the total system length of the optical system  100  can be effectively shortened, which further satisfies the requirements of the miniaturization design of the lens. 
     The optical system  100  satisfies a relational expression: R9/R10=−1.19; where R9 is a radius of curvature of the object side surface S 9  of the fifth lens L 5  at the optical axis, and R10 is a radius of curvature of the image side surface S 10  of the fifth lens L 5  at the optical axis. When the above relational expression is satisfied, the relation between the object side surface S 9  and the image side surface S 10  of the fifth lens L 5  can be reasonably restricted, so that the deflection angle of the optical system  100  can be reasonably distributed, and the astigmatism of the off-axis field of view of the optical system  100  can be improved, thereby improving the imaging quality of the optical system  100 . 
     The optical system  100  satisfies a relational expression: |f6|/R12=1.83; where f6 is the effective focal length of the sixth lens L 6 , and R12 is a radius of curvature of the image side surface S 12  of the sixth lens L 6  at the optical axis. When the above relational expression is satisfied, the effective focal length of the sixth lens L 6  and the image side surface S 12  can be reasonably configured, so as to reduce the incident angle of light rays reaching the image plane S 15  of the optical system  100 , so that the optical system  100  can be more easily matched with a photosensitive element. 
     The optical system  100  satisfies a relational expression: CT5/|SAG51|=3.70; where CT5 is a thickness of the fifth lens L 5  on the optical axis, and SAG51 is a sagittal height of the object side surface S 9  of the fifth lens L 5 . When the above relational expression is satisfied, the fifth lens L 5  can be reasonably configured, so that the surface shape of the fifth lens L 5  can be more reasonable, so as to reduce the defect rate of the fifth lens L 5  during the processing and molding. In addition, the aberrations generated in the optical system  100  can be corrected, thereby further improving the imaging quality of the optical system  100 . 
     In addition, various parameters of the optical system  100  are given in Table 1. The image plane S 15  in Table 1 can be understood as an imaging plane of the optical system  100 . The elements from an object plane (not shown in the figures) to the image plane S 15  are sequentially arranged in the order of the elements from top to bottom in Table 1. The Y radius in Table 1 is a radius of curvature of an object side surface or an image side surface with a corresponding surface number on the optical axis. The surface numbers  1  and  2  are the object side surface S 1  and the image side surface S 2  of the first lens L 1 , 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 value in the “thickness” parameter column of the first lens L 1  is a thickness of the lens on the optical axis, and the second value therein is a distance on the optical axis from the image side surface of the lens to an object side surface of a rear lens in a direction towards the image side. 
     It should be noted that in this embodiment and the following various embodiments, the optical system  100  may not be provided with the infrared filter L 7 , but in this case, a distance from the image side surface S 11  of the sixth lens L 6  to the image plane S 15  remains unchanged. 
     In the first embodiment, the total effective focal length of the optical system  100  is indicated by f, and f=3.68 mm. The f-number thereof is indicated by FNO, and FNO=2.54. The half of the maximum field of view is indicated by HFOV, and HFOV=41.06°. The distance from the object side surface S 1  of the first lens L 1  to the image plane S 15  on the optical axis is indicated by TTL, and TTL=4.4 mm. 
     In addition, the focal length, refractive index, and Abbe number of each of the lenses are values at a wavelength of 555 nm, and the same applies to other embodiments. 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 First Embodiment 
               
               
                 f = 3.68 mm, FNO = 2.54, HFOV = 41.06°, TTL = 4.4 mm 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Surface 
                 Surface 
                 Surface 
                 Y radius 
                 Thickness 
                   
                 Refractive 
                 Abbe 
                 Focal length 
               
               
                 number 
                 name 
                 shape 
                 (mm) 
                 (mm) 
                 Material 
                 index 
                 number 
                 (mm) 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                   
                 Object plane 
                 Spherical 
                 Infinite 
                 394 
                   
                   
                   
                   
               
               
                   
                 Optical stop 
                 Spherical 
                 Infinite 
                 −0.129 
               
               
                 1 
                 First lens 
                 Aspherical 
                 1.613 
                 0.759 
                 Plastic 
                 1.546 
                 56.14 
                 2.95 
               
               
                 2 
                   
                 Aspherical 
                 Infinite 
                 0.050 
               
               
                 3 
                 Second lens 
                 Aspherical 
                 Infinite 
                 0.250 
                 Plastic 
                 1.546 
                 56.14 
                 −14.50 
               
               
                 4 
                   
                 Aspherical 
                 7.915 
                 0.093 
               
               
                 5 
                 Third lens 
                 Aspherical 
                 −20.750 
                 0.280 
                 Plastic 
                 1.666 
                 20.37 
                 −64.25 
               
               
                 6 
                   
                 Aspherical 
                 −40.475 
                 0.238 
               
               
                 7 
                 Fourth lens 
                 Aspherical 
                 −79.355 
                 0.290 
                 Plastic 
                 1.645 
                 23.54 
                 −6.97 
               
               
                 8 
                   
                 Aspherical 
                 4.767 
                 0.192 
               
               
                 9 
                 Fifth lens 
                 Aspherical 
                 3.200 
                 0.666 
                 Plastic 
                 1.546 
                 56.14 
                 2.79 
               
               
                 10 
                   
                 Aspherical 
                 −2.685 
                 0.328 
               
               
                 11 
                 Sixth lens 
                 Aspherical 
                 563.270 
                 0.326 
                 Plastic 
                 1.546 
                 56.14 
                 −2.29 
               
               
                 12 
                   
                 Aspherical 
                 1.249 
                 0.310 
               
               
                 13 
                 Infrared filter 
                 Spherical 
                 Infinite 
                 0.210 
                 Glass 
                 1.518 
                 64.17 
               
               
                 14 
                   
                 Spherical 
                 Infinite 
                 0.408 
               
               
                 15 
                 Image plane 
                 Spherical 
                 Infinite 
                 0.000 
               
               
                   
               
            
           
         
       
     
     Further, the aspheric coefficients of the image side surfaces or the object side surfaces of the lenses of the optical system  100  are given in Table 2. The surface numbers from 1-10 represent the image side surfaces or the object side surfaces S 1 -S 10 , respectively. The K to A20 from top to bottom represent the types of the aspheric coefficients, respectively, where K represents a conic coefficient, A4 represents a fourth-order aspheric coefficient, A6 represents a sixth-order aspheric coefficient, and A8 is an eighth-order aspheric coefficient, and so on. In addition, the aspheric coefficient equation is as follows: 
     
       
         
           
             Z 
             = 
             
               
                 
                   cr 
                   2 
                 
                 
                   1 
                   + 
                   
                     
                       1 
                       - 
                       
                         
                           ( 
                           
                             k 
                             + 
                             1 
                           
                           ) 
                         
                         ⁢ 
                         
                           c 
                           2 
                         
                         ⁢ 
                         
                           r 
                           2 
                         
                       
                     
                   
                 
               
               + 
               
                 
                   ∑ 
                   i 
                 
                 ⁢ 
                 
                   Ai 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   
                     r 
                     i 
                   
                 
               
             
           
         
       
     
     where, Z is a distance from a corresponding point on the aspherical surface to a plane tangent to a vertex of the surface, r is a distance from a corresponding point on the aspherical surface to the optical axis, c is a curvature of the vertex of the aspherical surface, k is a conic coefficient, and Ai is a coefficient corresponding to a high-order term of the i th  term in the equation of the aspherical surface shape. 
     
       
         
           
               
             
               
                 TABLE 2 
               
               
                   
               
               
                 First Embodiment 
               
               
                 Aspheric coefficient 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Surface 
                   
                   
                   
                   
                   
                   
               
               
                 number 
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
               
                 K 
                 −4.6198E+00 
                 1.0000E+00 
                 1.0000E+00 
                 −5.0000E+01 
                  3.0000E+01 
                 −5.0000E+01  
               
               
                 A4 
                  1.1936E−01 
                 3.6869E−02 
                 3.2258E−02 
                 −1.1334E−01 
                 −4.2808E−02 
                 1.0970E−01 
               
               
                 A6 
                 −3.0613E−03 
                 −5.1250E−01  
                 −1.9135E−01  
                 −1.4635E−01 
                 −4.1251E−01 
                 −2.6859E−01  
               
               
                 A8 
                 −5.0869E−01 
                 4.5843E+00 
                 8.1092E−02 
                 −2.1782E+00 
                 −3.6638E−01 
                 6.1508E−01 
               
               
                 A10 
                  2.2954E+00 
                 −2.4375E+01  
                 8.2420E+00 
                  1.5945E+01 
                  7.6378E+00 
                 −4.5595E−01  
               
               
                 A12 
                 −5.3919E+00 
                 7.5584E+01 
                 −6.1183E+01  
                 −5.7803E+01 
                 −2.9619E+01 
                 1.7876E−01 
               
               
                 A14 
                  6.5558E+00 
                 −1.4024E+02  
                 1.9924E+02 
                  1.1705E+02 
                  6.1589E+01 
                 −4.2137E−02  
               
               
                 A16 
                 −3.2594E+00 
                 1.5505E+02 
                 −3.3615E+02  
                 −1.2117E+02 
                 −6.4964E+01 
                 0.0000E+00 
               
               
                 A18 
                  0.0000E+00 
                 −9.4868E+01  
                 2.8764E+02 
                  4.9545E+01 
                  2.6770E+01 
                 0.0000E+00 
               
               
                 A20 
                  0.0000E+00 
                 2.4857E+01 
                 −9.8988E+01  
                  0.0000E+00 
                  0.0000E+00 
                 0.0000E+00 
               
               
                   
               
               
                 Surface 
                   
               
               
                 number 
                 7 
                 8 
                 9 
                 10 
                 11 
                 12 
               
               
                   
               
               
                 K 
                  5.0000E+01 
                 −1.9990E+01 
                 −1.1302E+01 
                 −3.7576E+01 
                 −1.5017E+01 
                 −7.9842E+00 
               
               
                 A4 
                 −1.2951E−01 
                 −2.4089E−01 
                 −6.4338E−03 
                  1.1234E−02 
                 −3.9618E−01 
                 −2.2194E−01 
               
               
                 A6 
                  4.8684E−01 
                  2.6803E−01 
                 −2.3170E−01 
                 −4.2480E−02 
                  2.1950E−01 
                  1.7054E−01 
               
               
                 A8 
                 −2.2834E+00 
                 −2.7059E−01 
                  5.2030E−01 
                  4.7069E−02 
                 −3.3018E−02 
                 −9.9184E−02 
               
               
                 A10 
                  7.8221E+00 
                  2.4577E−01 
                 −7.4016E−01 
                 −9.0827E−03 
                 −7.2916E−03 
                  4.2828E−02 
               
               
                 A12 
                 −1.7576E+01 
                 −7.8124E−02 
                  6.7761E−01 
                 −1.5733E−02 
                  2.5762E−03 
                 −1.3315E−02 
               
               
                 A14 
                  2.5309E+01 
                 −1.2314E−01 
                 −3.9778E−01 
                  1.1829E−02 
                  8.0434E−05 
                  2.7878E−03 
               
               
                 A16 
                 −2.2717E+01 
                  1.4792E−01 
                  1.4105E−01 
                 −3.5652E−03 
                 −1.2311E−04 
                 −3.6474E−04 
               
               
                 A18 
                  1.1575E+01 
                 −6.2327E−02 
                 −2.6970E−02 
                  5.0866E−04 
                  1.8116E−05 
                  2.6738E−05 
               
               
                 A20 
                 −2.5654E+00 
                  9.5591E−03 
                  2.1132E−03 
                 −2.8226E−05 
                 −8.7338E−07 
                 −8.3712E−07 
               
               
                   
               
            
           
         
       
     
     Second Embodiment 
     Referring to  FIGS. 3 and 4 ,  FIG. 3  is a schematic view of an optical system  100  in the second embodiment. The optical system  100  includes, sequentially arranged from an object side to an image side, an optical stop STO, a first lens L 1  having a positive refractive power, a second lens L 2  having a negative refractive power, a third lens L 3  having a negative refractive power, a fourth lens L 4  having a negative refractive power, a fifth lens L 5  having a positive refractive power, and a sixth lens L 6  having a negative refractive power.  FIG. 4  is, sequentially from left to right, graphs of spherical aberration, astigmatism, and distortion of the optical system  100  in the second embodiment. 
     An object side surface S 1  of the first lens L 1  is convex at its paraxial position and convex at its circumference. 
     An image side surface S 2  of the first lens L 1  is planar at its paraxial position and planar at its circumference. 
     An object side surface S 3  of the second lens L 2  is planar at its paraxial position and planar at its circumference. 
     An image side surface S 4  of the second lens L 2  is concave at its paraxial position and convex at its circumference. 
     An object side surface S 5  of the third lens L 3  is concave at its paraxial position and concave at its circumference. 
     An image side surface S 6  of the third lens L 3  is convex at its paraxial position and concave at its circumference. 
     An object side surface S 7  of the fourth lens L 4  is concave at its paraxial position and concave at its circumference. 
     An image side surface S 8  of the fourth lens L 4  is concave at its paraxial position and convex at its circumference. 
     An object side surface S 9  of the fifth lens L 5  is convex at its paraxial position and concave at its circumference. 
     An image side surface S 10  of the fifth lens L 5  is convex at its paraxial position and convex at its circumference. 
     An object side surface S 11  of the sixth lens L 6  is convex at its paraxial position and convex at its circumference. 
     An image side surface S 12  of the sixth lens L 6  is concave at its paraxial position and concave at its circumference. 
     The image side surface S 2  of the first lens L 1  and the object side surface S 3  of the second lens L 2  are planar, while the object side surface S 1  of the first lens L 1 , the image side surface S 4  of the second lens L 2 , and the object side surfaces and the image side surfaces of the third lens L 3 , the fourth lens L 4 , the fifth lens L 5 , and the sixth lens L 6  are all aspherical. 
     The first lens L 1 , the second lens L 2 , the third lens L 3 , the fourth lens L 4 , the fifth lens L 5 , and the sixth lens L 6  are all made of plastic. 
     In addition, various parameters of the optical system  100  are given in Table 3, in which definitions of the various parameters can be obtained from the first embodiment, which will not be repeated here. 
     
       
         
           
               
             
               
                 TABLE 3 
               
             
            
               
                   
               
               
                 Second embodiment 
               
               
                 f = 3.67 mm, FNO = 2.55, HFOV = 41.13°, TTL = 4.4 mm 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Surface 
                 Surface 
                 Surface 
                 Y radius 
                 Thickness 
                   
                 Refractive 
                 Abbe 
                 Focal length 
               
               
                 number 
                 name 
                 shape 
                 (mm) 
                 (mm) 
                 Material 
                 index 
                 number 
                 (mm) 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                   
                 Object plane 
                 Spherical 
                 Infinite 
                 394 
                   
                   
                   
                   
               
               
                   
                 Optical stop 
                 Spherical 
                 Infinite 
                 −0.130 
               
               
                 1 
                 First lens 
                 Aspherical 
                 1.616 
                 0.730 
                 Plastic 
                 1.546 
                 56.14 
                 2.96 
               
               
                 2 
                   
                 Aspherical 
                 Infinite 
                 0.050 
               
               
                 3 
                 Second lens 
                 Aspherical 
                 Infinite 
                 0.258 
                 Plastic 
                 1.546 
                 56.14 
                 −15.78 
               
               
                 4 
                   
                 Aspherical 
                 8.616 
                 0.097 
               
               
                 5 
                 Third lens 
                 Aspherical 
                 −19.615 
                 0.277 
                 Plastic 
                 1.666 
                 20.37 
                 −45.80 
               
               
                 6 
                   
                 Aspherical 
                 −55.183 
                 0.235 
               
               
                 7 
                 Fourth lens 
                 Aspherical 
                 −70.507 
                 0.298 
                 Plastic 
                 1.645 
                 23.54 
                 −7.01 
               
               
                 8 
                   
                 Aspherical 
                 4.829 
                 0.200 
               
               
                 9 
                 Fifth lens 
                 Aspherical 
                 3.134 
                 0.669 
                 Plastic 
                 1.546 
                 56.14 
                 2.78 
               
               
                 10 
                   
                 Aspherical 
                 −2.727 
                 0.330 
               
               
                 11 
                 Sixth lens 
                 Aspherical 
                 −386.669 
                 0.329 
                 Plastic 
                 1.546 
                 56.14 
                 −2.31 
               
               
                 12 
                   
                 Aspherical 
                 1.267 
                 0.309 
               
               
                 13 
                 Infrared filter 
                 Spherical 
                 Infinite 
                 0.210 
                 Glass 
                 1.518 
                 64.17 
               
               
                 14 
                   
                 Spherical 
                 Infinite 
                 0.408 
               
               
                 15 
                 Image plane 
                 Spherical 
                 Infinite 
                 0.000 
               
               
                   
               
            
           
         
       
     
     Further, the aspheric coefficients of the image side surfaces or the object side surfaces of the lenses of the optical system  100  are given in Table 4, in which definitions of the various parameters can be obtained from the first embodiment, which will not be repeated here. 
     
       
         
           
               
             
               
                 TABLE 4 
               
               
                   
               
               
                 Second embodiment 
               
               
                 Aspheric coefficient 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Surface 
                   
                   
                   
                   
                   
                   
               
               
                 number 
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
               
                 K 
                 −4.6557E+00 
                 1.0000E+00 
                 1.0000E+00 
                 −5.0000E+01 
                  3.0000E+01 
                 −4.9699E+01  
               
               
                 A4 
                  1.2012E−01 
                 3.8097E−02 
                 3.9654E−02 
                 −1.1368E−01 
                 −4.3566E−02 
                 1.1775E−01 
               
               
                 A6 
                 −2.6116E−02 
                 −5.6242E−01  
                 −2.8926E−01  
                 −1.6104E−01 
                 −3.8656E−01 
                 −3.1703E−01  
               
               
                 A8 
                 −3.2888E−01 
                 4.8517E+00 
                 6.9985E−01 
                 −2.2456E+00 
                 −7.8303E−01 
                 7.5239E−01 
               
               
                 A10 
                  1.5175E+00 
                 −2.4286E+01  
                 6.6102E+00 
                  1.7124E+01 
                  1.0082E+01 
                 −6.7550E−01  
               
               
                 A12 
                 −3.6040E+00 
                 7.0582E+01 
                 −5.9958E+01  
                 −6.2229E+01 
                 −3.6572E+01 
                 3.6620E−01 
               
               
                 A14 
                  4.4609E+00 
                 −1.2292E+02  
                 2.0067E+02 
                  1.2415E+02 
                  7.1858E+01 
                 −1.0665E−01  
               
               
                 A16 
                 −2.2763E+00 
                 1.2797E+02 
                 −3.3772E+02  
                 −1.2619E+02 
                 −7.2476E+01 
                 0.0000E+00 
               
               
                 A18 
                  0.0000E+00 
                 −7.4022E+01  
                 2.8608E+02 
                  5.0733E+01 
                  2.8899E+01 
                 0.0000E+00 
               
               
                 A20 
                  0.0000E+00 
                 1.8398E+01 
                 −9.7289E+01  
                  0.0000E+00 
                  0.0000E+00 
                 0.0000E+00 
               
               
                   
               
               
                 Surface 
                   
               
               
                 number 
                 7 
                 8 
                 9 
                 10 
                 11 
                 12 
               
               
                   
               
               
                 K 
                 4.4680E+01 
                 −2.3977E+01 
                 −1.1446E+01 
                 −3.6906E+01  
                 5.0000E+01 
                 −7.8769E+00 
               
               
                 A4 
                 −1.2432E−01  
                 −2.3698E−01 
                 −7.0824E−03 
                 1.2871E−02 
                 −3.9234E−01  
                 −2.2200E−01 
               
               
                 A6 
                 4.4185E−01 
                  2.4676E−01 
                 −2.2265E−01 
                 −4.3614E−02  
                 2.2629E−01 
                  1.7336E−01 
               
               
                 A8 
                 −2.1163E+00  
                 −2.0733E−01 
                  4.9204E−01 
                 4.0326E−02 
                 −4.9531E−02  
                 −1.0215E−01 
               
               
                 A10 
                 7.4087E+00 
                  1.2121E−01 
                 −6.8969E−01 
                 3.3138E−03 
                 5.6263E−03 
                  4.4453E−02 
               
               
                 A12 
                 −1.6945E+01  
                  7.1279E−02 
                  6.2461E−01 
                 −2.5388E−02  
                 −2.7552E−03  
                 −1.3886E−02 
               
               
                 A14 
                 2.4792E+01 
                 −2.3127E−01 
                 −3.6449E−01 
                 1.5974E−02 
                 1.3729E−03 
                  2.9207E−03 
               
               
                 A16 
                 −2.2593E+01  
                  1.9471E−01 
                  1.2892E−01 
                 −4.5889E−03  
                 −3.0871E−04  
                 −3.8438E−04 
               
               
                 A18 
                 1.1682E+01 
                 −7.3586E−02 
                 −2.4642E−02 
                 6.4549E−04 
                 3.2790E−05 
                  2.8371E−05 
               
               
                   
               
            
           
         
       
     
     In addition, according to the parameter information provided above, the following relations can be derived: 
     
       
         
           
             
               
                 CT 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 1 
                 ⁢ 
                 
                   / 
                 
                 ⁢ 
                 SD 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 11 
               
               = 
               0.967 
             
             ; 
             
               
                 TTL 
                 ⁢ 
                 
                   / 
                 
                 ⁢ 
                 CT 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 1 
               
               = 
               6.03 
             
             ; 
             
               FNO 
               = 
               2.55 
             
             ; 
             
               
                 f 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 3 
                 ⁢ 
                 
                   / 
                 
                 ⁢ 
                 f 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 4 
               
               = 
               6.534 
             
             ; 
           
         
       
       
         
           
             
               
                 
                   f 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   4 
                   ⁢ 
                   
                     / 
                   
                   ⁢ 
                   f 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   1 
                 
                 + 
                 
                   f 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   5 
                   ⁢ 
                   
                     / 
                   
                   ⁢ 
                   f 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   6 
                 
               
               = 
               3.57 
             
             ; 
             
               
                 f 
                 ⁢ 
                 
                   / 
                 
                 ⁢ 
                 f 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 12 
               
               = 
               1.06 
             
             ; 
             
               
                 TT 
                 ⁢ 
                 
                   / 
                 
                 ⁢ 
                 ImgH 
               
               = 
               1.05 
             
             ; 
             
               
                 R 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 9 
                 ⁢ 
                 
                   / 
                 
                 ⁢ 
                 R 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 10 
               
               = 
               
                 - 
                 1.15 
               
             
             ; 
           
         
       
       
         
           
             
               
                 
                    
                   
                     f 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     6 
                   
                    
                 
                 ⁢ 
                 
                   / 
                 
                 ⁢ 
                 R 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 12 
               
               = 
               1.82 
             
             ; 
             
               
                 CT 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 5 
                 ⁢ 
                 
                   / 
                 
                 ⁢ 
                 
                    
                   
                     SAG 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     51 
                   
                    
                 
               
               = 
               
                 3.78 
                 . 
               
             
           
         
       
     
     Third Embodiment 
     Referring to  FIGS. 5 and 6 ,  FIG. 5  is a schematic view of an optical system  100  in the third embodiment. The optical system  100  includes, sequentially arranged from an object side to an image side, an optical stop STO, a first lens L 1  having a positive refractive power, a second lens L 2  having a negative refractive power, a third lens L 3  having a negative refractive power, a fourth lens L 4  having a negative refractive power, a fifth lens L 5  having a positive refractive power, and a sixth lens L 6  having a negative refractive power.  FIG. 6  is, sequentially from left to right, graphs of spherical aberration, astigmatism, and distortion of the optical system  100  in the third embodiment. 
     An object side surface S 1  of the first lens L 1  is convex at its paraxial position and convex at its circumference. 
     An image side surface S 2  of the first lens L 1  is concave at its paraxial position and concave at its circumference. 
     An object side surface S 3  of the second lens L 2  is convex at its paraxial position and convex at its circumference. 
     An image side surface S 4  of the second lens L 2  is concave at its paraxial position and convex at its circumference. 
     An object side surface S 5  of the third lens L 3  is concave at its paraxial position and concave at its circumference. 
     An image side surface S 6  of the third lens L 3  is convex at its paraxial position and concave at its circumference. 
     An object side surface S 7  of the fourth lens L 4  is concave at its paraxial position and concave at its circumference. 
     An image side surface S 8  of the fourth lens L 4  is concave at its paraxial position and convex at its circumference. 
     An object side surface S 9  of the fifth lens L 5  is convex at its paraxial position and concave at its circumference. 
     An image side surface S 10  of the fifth lens L 5  is convex at its paraxial position and convex at its circumference. 
     An object side surface S 11  of the sixth lens L 6  is convex at its paraxial position and convex at its circumference. 
     An image side surface S 12  of the sixth lens L 6  is concave at its paraxial position and concave at its circumference. 
     The object side surfaces and the image side surfaces of the first lens L 1 , the second lens L 2 , the third lens L 3 , the fourth lens L 4 , the fifth lens L 5 , and the sixth lens L 6  are all aspherical. 
     The first lens L 1 , the second lens L 2 , the third lens L 3 , the fourth lens L 4 , the fifth lens L 5 , and the sixth lens L 6  are all made of plastic. 
     In addition, various parameters of the optical system  100  are given in Table 5, in which definitions of the various parameters can be obtained from the first embodiment, which will not be repeated here. 
     
       
         
           
               
             
               
                 TABLE 5 
               
             
            
               
                   
               
               
                 Third Embodiment 
               
               
                 f = 3.66 mm, FNO = 2.41, HFOV = 41.21°, TTL = 4.445 mm 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Surface 
                 Surface 
                 Surface 
                 Y radius 
                 Thickness 
                   
                 Refractive 
                 Abbe 
                 Focal length 
               
               
                 number 
                 name 
                 shape 
                 (mm) 
                 (mm) 
                 Material 
                 index 
                 number 
                 (mm) 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                   
                 Object plane 
                 Spherical 
                 Infinite 
                 400 
                   
                   
                   
                   
               
               
                   
                 Optical stop 
                 Spherical 
                 Infinite 
                 −0.153 
               
               
                 1 
                 First lens 
                 Aspherical 
                 1.592 
                 0.673 
                 Plastic 
                 1.546 
                 56.14 
                 3.36 
               
               
                 2 
                   
                 Aspherical 
                 10.272 
                 0.052 
               
               
                 3 
                 Second lens 
                 Aspherical 
                 10.888 
                 0.294 
                 Plastic 
                 1.546 
                 56.14 
                 −177.22 
               
               
                 4 
                   
                 Aspherical 
                 9.693 
                 0.105 
               
               
                 5 
                 Third lens 
                 Aspherical 
                 −11.954 
                 0.262 
                 Plastic 
                 1.666 
                 20.37 
                 −26.01 
               
               
                 6 
                   
                 Aspherical 
                 −38.826 
                 0.235 
               
               
                 7 
                 Fourth lens 
                 Aspherical 
                 −71.823 
                 0.335 
                 Plastic 
                 1.645 
                 23.54 
                 −7.05 
               
               
                 8 
                   
                 Aspherical 
                 4.854 
                 0.212 
               
               
                 9 
                 Fifth lens 
                 Aspherical 
                 2.924 
                 0.714 
                 Plastic 
                 1.546 
                 56.14 
                 2.80 
               
               
                 10 
                   
                 Aspherical 
                 −2.922 
                 0.322 
               
               
                 11 
                 Sixth lens 
                 Aspherical 
                 112.513 
                 0.332 
                 Plastic 
                 1.546 
                 56.14 
                 −2.43 
               
               
                 12 
                   
                 Aspherical 
                 1.307 
                 0.301 
               
               
                 13 
                 Infrared 
                 Spherical 
                 Infinite 
                 0.210 
                 Glass 
                 1.518 
                 64.17 
               
               
                 14 
                 filter 
                 Spherical 
                 Infinite 
                 0.399 
               
               
                 15 
                 Image plane 
                 Spherical 
                 Infinite 
                 0.000 
               
               
                   
               
            
           
         
       
     
     Further, the aspheric coefficients of the image side surfaces or the object side surfaces of the lenses of the optical system  100  are given in Table 6, in which definitions of the various parameters can be obtained from the first embodiment, which will not be repeated here. 
     
       
         
           
               
             
               
                 TABLE 6 
               
               
                   
               
               
                 Third Embodiment 
               
               
                 Aspheric coefficient 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Surface 
                   
                   
                   
                   
                   
                   
               
               
                 number 
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
               
                 K 
                 −4.4978E+00 
                 −3.4503E+01 
                 −1.7992E+01 
                 −5.0000E+01 
                  2.4038E+01 
                 3.0000E+01 
               
               
                 A4 
                  1.2371E−01 
                  3.9205E−02 
                  3.7243E−02 
                 −1.0998E−01 
                 −3.2525E−02 
                 1.1624E−01 
               
               
                 A6 
                 −3.2929E−02 
                 −5.0760E−01 
                 −3.4734E−01 
                 −1.6074E−01 
                 −4.4954E−01 
                 −3.1284E−01  
               
               
                 A8 
                 −1.6451E−01 
                  3.2833E+00 
                  6.6264E−01 
                 −2.0223E+00 
                 −1.7538E−01 
                 7.1762E−01 
               
               
                 A10 
                  6.4984E−01 
                 −1.2062E+01 
                  6.7989E+00 
                  1.4063E+01 
                  5.6424E+00 
                 −6.1903E−01  
               
               
                 A12 
                 −1.3752E+00 
                  2.6615E+01 
                 −4.7885E+01 
                 −4.5003E+01 
                 −1.9002E+01 
                 3.0820E−01 
               
               
                 A14 
                  1.5923E+00 
                 −3.7705E+01 
                  1.3409E+02 
                  7.9591E+01 
                  3.4661E+01 
                 −8.0246E−02  
               
               
                 A16 
                 −7.8640E−01 
                  3.5321E+01 
                 −1.9561E+02 
                 −7.2771E+01 
                 −3.2986E+01 
                 0.0000E+00 
               
               
                 A18 
                  0.0000E+00 
                 −2.0334E+01 
                  1.4749E+02 
                  2.6641E+01 
                  1.2447E+01 
                 0.0000E+00 
               
               
                 A20 
                  0.0000E+00 
                  5.3735E+00 
                 −4.5559E+01 
                  0.0000E+00 
                  0.0000E+00 
                 0.0000E+00 
               
               
                   
               
               
                 Surface 
                   
               
               
                 number 
                 7 
                 8 
                 9 
                 10 
                 11 
                 12 
               
               
                   
               
               
                 K 
                  5.0000E+01 
                 −3.2271E+01 
                 −1.0343E+01 
                 −3.7734E+01 
                 −4.0000E+01 
                 −7.2234E+00 
               
               
                 A4 
                 −1.1661E−01 
                 −2.1245E−01 
                 −8.1680E−03 
                  2.1417E−02 
                 −3.5847E−01 
                 −2.0972E−01 
               
               
                 A6 
                  3.5650E−01 
                  1.3812E−01 
                 −2.1740E−01 
                 −6.1260E−02 
                  1.8475E−01 
                  1.5782E−01 
               
               
                 A8 
                 −1.7225E+00 
                  1.4935E−01 
                  4.9639E−01 
                  6.1822E−02 
                 −2.1902E−02 
                 −8.9237E−02 
               
               
                 A10 
                  6.6102E+00 
                 −5.9366E−01 
                 −6.9442E−01 
                 −1.6543E−02 
                 −8.2219E−03 
                  3.7445E−02 
               
               
                 A12 
                 −1.6691E+01 
                  9.1414E−01 
                  6.1770E−01 
                 −1.1820E−02 
                  2.5530E−03 
                 −1.1354E−02 
               
               
                 A14 
                  2.6529E+01 
                 −8.3435E−01 
                 −3.5274E−01 
                  1.0028E−02 
                 −3.5306E−05 
                  2.3301E−03 
               
               
                 A16 
                 −2.5781E+01 
                  4.5479E−01 
                  1.2244E−01 
                 −3.0550E−03 
                 −7.4560E−05 
                 −3.0019E−04 
               
               
                 A18 
                  1.3990E+01 
                 −1.3556E−01 
                 −2.3083E−02 
                  4.3515E−04 
                  1.1111E−05 
                  2.1739E−05 
               
               
                 A20 
                 −3.2543E+00 
                  1.6935E−02 
                  1.7951E−03 
                 −2.4154E−05 
                 −5.1714E−07 
                 −6.7383E−07 
               
               
                   
               
            
           
         
       
     
     In addition, according to the parameter information provided above, the following relations can be derived: 
     
       
         
           
             
               
                 CT 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 1 
                 ⁢ 
                 
                   / 
                 
                 ⁢ 
                 SD 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 11 
               
               = 
               0.85 
             
             ; 
             
               
                 TTL 
                 ⁢ 
                 
                   / 
                 
                 ⁢ 
                 CT 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 1 
               
               = 
               6.60 
             
             ; 
             
               FNO 
               = 
               2.41 
             
             ; 
             
               
                 f 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 3 
                 ⁢ 
                 
                   / 
                 
                 ⁢ 
                 f 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 4 
               
               = 
               3.689 
             
             ; 
           
         
       
       
         
           
             
               
                 
                   f 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   4 
                   ⁢ 
                   
                     / 
                   
                   ⁢ 
                   f 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   1 
                 
                 + 
                 
                   f 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   5 
                   ⁢ 
                   
                     / 
                   
                   ⁢ 
                   f 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   6 
                 
               
               = 
               3.25 
             
             ; 
             
               
                 f 
                 ⁢ 
                 
                   / 
                 
                 ⁢ 
                 f 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 12 
               
               = 
               1.08 
             
             ; 
             
               
                 TT 
                 ⁢ 
                 
                   / 
                 
                 ⁢ 
                 ImgH 
               
               = 
               1.07 
             
             ; 
             
               
                 R 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 9 
                 ⁢ 
                 
                   / 
                 
                 ⁢ 
                 R 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 10 
               
               = 
               
                 - 
                 1.00 
               
             
             ; 
           
         
       
       
         
           
             
               
                 
                    
                   
                     f 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     6 
                   
                    
                 
                 ⁢ 
                 
                   / 
                 
                 ⁢ 
                 R 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 12 
               
               = 
               1.86 
             
             ; 
             
               
                 CT 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 5 
                 ⁢ 
                 
                   / 
                 
                 ⁢ 
                 
                    
                   
                     SAG 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     51 
                   
                    
                 
               
               = 
               
                 4.3 
                 . 
               
             
           
         
       
     
     Fourth Embodiment 
     Referring to  FIGS. 7 and 8 ,  FIG. 7  is a schematic view of an optical system  100  in the fourth embodiment. The optical system  100  includes, sequentially arranged from an object side to an image side, an optical stop STO, a first lens L 1  having a positive refractive power, a second lens L 2  having a positive refractive power, a third lens L 3  having a negative refractive power, a fourth lens L 4  having a negative refractive power, a fifth lens L 5  having a positive refractive power, and a sixth lens L 6  having a negative refractive power.  FIG. 8  is, sequentially from left to right, graphs of spherical aberration, astigmatism, and distortion of the optical system  100  in the fourth embodiment. 
     An object side surface S 1  of the first lens L 1  is convex at its paraxial position and convex at its circumference. 
     An image side surface S 2  of the first lens L 1  is concave at its paraxial position and concave at its circumference. 
     An object side surface S 3  of the second lens L 2  is convex at its paraxial position and convex at its circumference. 
     An image side surface S 4  of the second lens L 2  is concave at its paraxial position and convex at its circumference. 
     An object side surface S 5  of the third lens L 3  is concave at its paraxial position and concave at its circumference. 
     An image side surface S 6  of the third lens L 3  is convex at its paraxial position and concave at its circumference. 
     An object side surface S 7  of the fourth lens L 4  is concave at its paraxial position and concave at its circumference. 
     An image side surface S 8  of the fourth lens L 4  is concave at its paraxial position and convex at its circumference. 
     An object side surface S 9  of the fifth lens L 5  is convex at its paraxial position and concave at its circumference. 
     An image side surface S 10  of the fifth lens L 5  is convex at its paraxial position and convex at its circumference. 
     An object side surface S 11  of the sixth lens L 6  is convex at its paraxial position and convex at its circumference. 
     An image side surface S 12  of the sixth lens L 6  is concave at its paraxial position and concave at its circumference. 
     The object side surfaces and the image side surfaces of the first lens L 1 , the second lens L 2 , the third lens L 3 , the fourth lens L 4 , the fifth lens L 5 , and the sixth lens L 6  are all aspherical. 
     The first lens L 1 , the second lens L 2 , the third lens L 3 , the fourth lens L 4 , the fifth lens L 5 , and the sixth lens L 6  are all made of plastic. 
     In addition, various parameters of the optical system  100  are given in Table 7, in which definitions of the various parameters can be obtained from the first embodiment, which will not be repeated here. 
     
       
         
           
               
             
               
                 TABLE 7 
               
             
            
               
                   
               
               
                 Fourth Embodiment 
               
               
                 f = 3.67 mm, FNO = 2.41, HFOV = 40.15°, TTL = 4.45 mm 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Surface 
                 Surface 
                 Surface 
                 Y radius 
                 Thickness 
                   
                 Refractive 
                 Abbe 
                 Focal length 
               
               
                 number 
                 name 
                 shape 
                 (mm) 
                 (mm) 
                 Material 
                 index 
                 number 
                 (mm) 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                   
                 Object plane 
                 Spherical 
                 Infinite 
                 400 
                   
                   
                   
                   
               
               
                   
                 Optical stop 
                 Spherical 
                 Infinite 
                 −0.154 
               
               
                 1 
                   
                 Aspherical 
                 1.589 
                 0.651 
                 Plastic 
                 1.546 
                 56.14 
                 3.52 
               
               
                 2 
                 First lens 
                 Aspherical 
                 7.825 
                 0.054 
               
               
                 3 
                   
                 Aspherical 
                 7.978 
                 0.312 
                 Plastic 
                 1.546 
                 56.14 
                 76.58 
               
               
                 4 
                 Second lens 
                 Aspherical 
                 9.723 
                 0.106 
               
               
                 5 
                   
                 Aspherical 
                 −13.031 
                 0.253 
                 Plastic 
                 1.666 
                 20.37 
                 −22.82 
               
               
                 6 
                 Third lens 
                 Aspherical 
                 −91.639 
                 0.234 
               
               
                 7 
                   
                 Aspherical 
                 −61.080 
                 0.349 
                 Plastic 
                 1.645 
                 23.54 
                 −7.25 
               
               
                 8 
                 Fourth lens 
                 Aspherical 
                 5.064 
                 0.216 
               
               
                 9 
                   
                 Aspherical 
                 2.933 
                 0.716 
                 Plastic 
                 1.546 
                 56.14 
                 2.81 
               
               
                 10 
                 Fifth lens 
                 Aspherical 
                 −2.934 
                 0.315 
               
               
                 11 
                   
                 Aspherical 
                 71.850 
                 0.332 
                 Plastic 
                 1.546 
                 56.14 
                 −2.43 
               
               
                 12 
                 Sixth lens 
                 Aspherical 
                 1.299 
                 0.303 
               
               
                 13 
                 Infrared 
                 Spherical 
                 Infinite 
                 0.210 
                 Glass 
                 1.518 
                 64.17 
               
               
                 14 
                 filter 
                 Spherical 
                 Infinite 
                 0.401 
               
               
                 15 
                 Image plane 
                 Spherical 
                 Infinite 
                 0.000 
               
               
                   
               
            
           
         
       
     
     Further, the aspheric coefficients of the image side surfaces or the object side surfaces of the lenses of the optical system  100  are given in Table 8, in which definitions of the various parameters can be obtained from the first embodiment, which will not be repeated here. 
     
       
         
           
               
             
               
                 TABLE 8 
               
               
                   
               
               
                 Fourth Embodiment 
               
               
                 Aspheric coefficient 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Surface 
                   
                   
                   
                   
                   
                   
               
               
                 number 
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
               
                 K 
                 −4.4829E+00 
                 −3.1772E+01 
                 −2.3952E+01 
                 −5.0000E+01 
                 2.1901E+01 
                 4.0000E+01 
               
               
                 A4 
                  1.2345E−01 
                  3.4012E−02 
                  2.8057E−02 
                 −1.1154E−01 
                 −2.9557E−02  
                 1.1583E−01 
               
               
                 A6 
                 −2.1596E−02 
                 −4.3858E−01 
                 −2.8258E−01 
                 −1.6932E−01 
                 −4.7900E−01  
                 −3.1357E−01  
               
               
                 A8 
                 −2.4045E−01 
                  2.8150E+00 
                  5.3736E−01 
                 −1.6231E+00 
                 2.1115E−01 
                 7.3509E−01 
               
               
                 A10 
                  9.2635E−01 
                 −1.0613E+01 
                  5.2328E+00 
                  1.1207E+01 
                 3.4655E+00 
                 −6.8920E−01  
               
               
                 A12 
                 −1.9213E+00 
                  2.5585E+01 
                 −3.6255E+01 
                 −3.4915E+01 
                 −1.2406E+01  
                 4.0086E−01 
               
               
                 A14 
                  2.1358E+00 
                 −4.2612E+01 
                  9.9826E+01 
                  6.0314E+01 
                 2.3237E+01 
                 −1.1957E−01  
               
               
                 A16 
                 −9.9782E−01 
                  4.8400E+01 
                 −1.4430E+02 
                 −5.3953E+01 
                 −2.2480E+01  
                 0.0000E+00 
               
               
                 A18 
                  0.0000E+00 
                 −3.2715E+01 
                  1.0906E+02 
                  1.9331E+01 
                 8.5121E+00 
                 0.0000E+00 
               
               
                 A20 
                  0.0000E+00 
                  9.5845E+00 
                 −3.4161E+01 
                  0.0000E+00 
                 0.0000E+00 
                 0.0000E+00 
               
               
                   
               
               
                 Surface 
                   
               
               
                 number 
                 7 
                 8 
                 9 
                 10 
                 11 
                 12 
               
               
                   
               
               
                 K 
                  5.0000E+01 
                 −3.6362E+01 
                 −1.0568E+01 
                 −3.7709E+01 
                 −4.0000E+01 
                 −6.8352E+00 
               
               
                 A4 
                 −1.1353E−01 
                 −2.0852E−01 
                 −1.0588E−02 
                  2.0025E−02 
                 −3.5143E−01 
                 −2.1653E−01 
               
               
                 A6 
                  3.1758E−01 
                  1.3322E−01 
                 −2.0968E−01 
                 −6.1092E−02 
                  1.8348E−01 
                  1.7098E−01 
               
               
                 A8 
                 −1.4278E+00 
                  1.4459E−01 
                  4.8012E−01 
                  6.6493E−02 
                 −3.0647E−02 
                 −1.0105E−01 
               
               
                 A1O 
                  5.3254E+00 
                 −5.6250E−01 
                 −6.6756E−01 
                 −2.3742E−02 
                  9.7688E−04 
                  4.3355E−02 
               
               
                 A12 
                 −1.3324E+01 
                  8.4904E−01 
                  5.8798E−01 
                 −6.7859E−03 
                 −1.8451E−03 
                 −1.3143E−02 
               
               
                 A14 
                  2.1089E+01 
                 −7.6073E−01 
                 −3.3269E−01 
                  8.1011E−03 
                  1.1502E−03 
                  2.6665E−03 
               
               
                 A16 
                 −2.0474E+01 
                  4.0844E−01 
                  1.1458E−01 
                 −2.6385E−03 
                 −2.6050E−04 
                 −3.3869E−04 
               
               
                 A18 
                  1.1123E+01 
                 −1.2024E−01 
                 −2.1437E−02 
                  3.8754E−04 
                  2.7000E−05 
                  2.4202E−05 
               
               
                 A20 
                 −2.5955E+00 
                  1.4854E−02 
                  1.6531E−03 
                 −2.1919E−05 
                 −1.0909E−06 
                 −7.4134E−07 
               
               
                   
               
            
           
         
       
     
     In addition, according to the parameter information provided above, the following relations can be derived: 
     
       
         
           
             
               
                 CT 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 1 
                 ⁢ 
                 
                   / 
                 
                 ⁢ 
                 SD 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 11 
               
               = 
               0.82 
             
             ; 
             
               
                 TTL 
                 ⁢ 
                 
                   / 
                 
                 ⁢ 
                 CT 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 1 
               
               = 
               6.84 
             
             ; 
             
               FNO 
               = 
               2.41 
             
             ; 
             
               
                 f 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 3 
                 ⁢ 
                 
                   / 
                 
                 ⁢ 
                 f 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 4 
               
               = 
               3.148 
             
             ; 
           
         
       
       
         
           
             
               
                 
                   f 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   4 
                   ⁢ 
                   
                     / 
                   
                   ⁢ 
                   f 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   1 
                 
                 + 
                 
                   f 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   5 
                   ⁢ 
                   
                     / 
                   
                   ⁢ 
                   f 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   6 
                 
               
               = 
               3.21 
             
             ; 
             
               
                 f 
                 ⁢ 
                 
                   / 
                 
                 ⁢ 
                 f 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 12 
               
               = 
               1.10 
             
             ; 
             
               
                 TT 
                 ⁢ 
                 
                   / 
                 
                 ⁢ 
                 ImgH 
               
               = 
               1.07 
             
             ; 
             
               
                 R 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 9 
                 ⁢ 
                 
                   / 
                 
                 ⁢ 
                 R 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 10 
               
               = 
               
                 - 
                 1.00 
               
             
             ; 
           
         
       
       
         
           
             
               
                 
                    
                   
                     f 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     6 
                   
                    
                 
                 ⁢ 
                 
                   / 
                 
                 ⁢ 
                 R 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 12 
               
               = 
               1.87 
             
             ; 
             
               
                 CT 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 5 
                 ⁢ 
                 
                   / 
                 
                 ⁢ 
                 
                    
                   
                     SAG 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     51 
                   
                    
                 
               
               = 
               
                 4.26 
                 . 
               
             
           
         
       
     
     Fifth Embodiment 
     Referring to  FIGS. 9 and 10 ,  FIG. 9  is a schematic view of an optical system  100  in the fifth embodiment. The optical system  100  includes, sequentially arranged from an object side to an image side, an optical stop STO, a first lens L 1  having a positive refractive power, a second lens L 2  having a positive refractive power, a third lens L 3  having a negative refractive power, a fourth lens L 4  having a negative refractive power, a fifth lens L 5  having a positive refractive power, and a sixth lens L 6  having a negative refractive power.  FIG. 10  is, sequentially from left to right, graphs of spherical aberration, astigmatism, and distortion of the optical system  100  in the fifth embodiment. 
     An object side surface S 1  of the first lens L 1  is convex at its paraxial position and convex at its circumference. 
     An image side surface S 2  of the first lens L 1  is concave at its paraxial position and concave at its circumference. 
     An object side surface S 3  of the second lens L 2  is convex at its paraxial position and convex at its circumference. 
     An image side surface S 4  of the second lens L 2  is concave at its paraxial position and convex at its circumference. 
     An object side surface S 5  of the third lens L 3  is concave at its paraxial position and concave at its circumference. 
     An image side surface S 6  of the third lens L 3  is concave at its paraxial position and concave at its circumference. 
     An object side surface S 7  of the fourth lens L 4  is concave at its paraxial position and concave at its circumference. 
     An image side surface S 8  of the fourth lens L 4  is concave at its paraxial position and convex at its circumference. 
     An object side surface S 9  of the fifth lens L 5  is convex at its paraxial position and concave at its circumference. 
     An image side surface S 10  of the fifth lens L 5  is convex at its paraxial position and convex at its circumference. 
     An object side surface S 11  of the sixth lens L 6  is convex at its paraxial position and convex at its circumference. 
     An image side surface S 12  of the sixth lens L 6  is concave at its paraxial position and concave at its circumference. 
     The object side surfaces and the image side surfaces of the first lens L 1 , the second lens L 2 , the third lens L 3 , the fourth lens L 4 , the fifth lens L 5 , and the sixth lens L 6  are all aspherical. 
     The first lens L 1 , the second lens L 2 , the third lens L 3 , the fourth lens L 4 , the fifth lens L 5 , and the sixth lens L 6  are all made of plastic. 
     In addition, various parameters of the optical system  100  are given in Table 9, in which definitions of the various parameters can be obtained from the first embodiment, which will not be repeated here. 
     
       
         
           
               
             
               
                 TABLE 9 
               
             
            
               
                   
               
               
                 Fifth Embodiment 
               
               
                 f = 3.72 mm, FNO = 2.35, HFOV = 40.7°, TTL = 4.476 mm 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Surface 
                 Surface 
                 Surface 
                 Y radius 
                 Thickness 
                   
                 Refractive 
                 Abbe 
                 Focal length 
               
               
                 number 
                 name 
                 shape 
                 (mm) 
                 (mm) 
                 Material 
                 index 
                 number 
                 (mm) 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                   
                 Object plane 
                 Spherical 
                 Infinite 
                 400 
                   
                   
                   
                   
               
               
                   
                 Optical stop 
                 Spherical 
                 Infinite 
                 −0.186 
               
               
                 1 
                   
                 Aspherical 
                 1.595 
                 0.582 
                 Plastic 
                 1.546 
                 56.14 
                 4.16 
               
               
                 2 
                 First lens 
                 Aspherical 
                 4.661 
                 0.082 
               
               
                 3 
                   
                 Aspherical 
                 4.380 
                 0.359 
                 Plastic 
                 1.546 
                 56.14 
                 12.48 
               
               
                 4 
                 Second lens 
                 Aspherical 
                 11.905 
                 0.104 
               
               
                 5 
                   
                 Aspherical 
                 −11.376 
                 0.250 
                 Plastic 
                 1.666 
                 20.37 
                 −13.62 
               
               
                 6 
                 Third lens 
                 Aspherical 
                 45.334 
                 0.267 
               
               
                 7 
                   
                 Aspherical 
                 −36.340 
                 0.469 
                 Plastic 
                 1.645 
                 23.54 
                 −7.98 
               
               
                 8 
                 Fourth lens 
                 Aspherical 
                 6.019 
                 0.213 
               
               
                 9 
                   
                 Aspherical 
                 2.792 
                 0.563 
                 Plastic 
                 1.546 
                 56.14 
                 2.84 
               
               
                 10 
                 Fifth lens 
                 Aspherical 
                 −3.239 
                 0.335 
               
               
                 11 
                   
                 Aspherical 
                 42.968 
                 0.332 
                 Plastic 
                 1.546 
                 56.14 
                 −2.41 
               
               
                 12 
                 Sixth lens 
                 Aspherical 
                 1.273 
                 0.306 
               
               
                 13 
                 Infrared 
                 Spherical 
                 Infinite 
                 0.210 
                 Glass 
                 1.518 
                 64.17 
               
               
                 14 
                 filter 
                 Spherical 
                 Infinite 
                 0.405 
               
               
                 15 
                 Image plane 
                 Spherical 
                 Infinite 
                 0.000 
               
               
                   
               
            
           
         
       
     
     Further, the aspheric coefficients of the image side surfaces or the object side surfaces of the lenses of the optical system  100  are given in Table 10, in which definitions of the various parameters can be obtained from the first embodiment, which will not be repeated here. 
     
       
         
           
               
             
               
                 TABLE 10 
               
               
                   
               
               
                 Fifth Embodiment 
               
               
                 Aspheric coefficient 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Surface 
                   
                   
                   
                   
                   
                   
               
               
                 number 
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
               
                 K 
                 −4.5063E+00 
                 −2.7815E+01 
                 −2.9778E+01 
                 −5.0000E+01 
                 −5.0000E+01 
                 −5.0000E+01  
               
               
                 A4 
                  1.2343E−01 
                  1.7025E−02 
                  1.5768E−02 
                     −J.0198E−01 
                 −2.9724E−02 
                 7.8166E−02 
               
               
                 A6 
                 −3.5574E−02 
                 −1.5097E−01 
                 −1.1558E−01 
                 −3.5503E−01 
                 −4.5040E−01 
                 −1.3055E−01  
               
               
                 A8 
                 −1.4887E−01 
                  8.6413E−01 
                  2.9603E−01 
                  5.0015E−01 
                  1.0993E+00 
                 3.0334E−01 
               
               
                 A10 
                  5.5035E−01 
                 −4.0326E+00 
                 −6.5899E−01 
                 −4.9904E−01 
                 −2.5839E+00 
                 −1.7700E−01  
               
               
                 A12 
                 −9.6839E−01 
                  1.2887E+01 
                  4.7754E−01 
                 −5.3923E−01 
                  5.5318E+00 
                 8.3462E−02 
               
               
                 A14 
                  8.4884E−01 
                 −2.5792E+01 
                  1.9889E+00 
                  4.3659E+00 
                 −5.7332E+00 
                 −3.5624E−02  
               
               
                 A16 
                 −2.9575E−01 
                  2.9776E+01 
                 −6.9951E+00 
                 −6.5371E+00 
                  2.0932E+00 
                 0.0000E+00 
               
               
                 A18 
                  0.0000E+00 
                 −1.7176E+01 
                  9.3333E+00 
                  3.1102E+00 
                  3.8153E−03 
                 0.0000E+00 
               
               
                 A20 
                  0.0000E+00 
                  3.7324E+00 
                 −4.2858E+00 
                  0.0000E+00 
                  0.0000E+00 
                 0.0000E+00 
               
               
                   
               
               
                 Surface 
                   
               
               
                 number 
                 7 
                 8 
                 9 
                 10 
                 11 
                 12 
               
               
                   
               
               
                 K 
                  5.0000E+01 
                 −4.0000E+01 
                 −1.0471E+01 
                 −4.0000E+01 
                 −4.0000E+01 
                 −6.6000E+00 
               
               
                 A4 
                 −1.1855E−01 
                 −2.3157E−01 
                 −2.6293E−02 
                  5.9267E−02 
                 −3.5643E−01 
                 −2.2035E−01 
               
               
                 A6 
                  3.1379E−01 
                  2.7801E−01 
                 −1.1601E−01 
                 −1.4506E−01 
                  1.8077E−01 
                  1.7447E−01 
               
               
                 A8 
                 −1.1106E+00 
                 −3.3070E−01 
                  2.6617E−01 
                  1.8389E−01 
                 −2.1699E−02 
                 −1.0091E−01 
               
               
                 A10 
                  3.1337E+00 
                  3.3921E−01 
                 −3.5516E−01 
                 −1.2213E−01 
                 −4.7093E−03 
                  4.1607E−02 
               
               
                 A12 
                 −6.4922E+00 
                 −2.6336E−01 
                  2.9292E−01 
                  4.2033E−02 
                 −2.6320E−04 
                 −1.1985E−02 
               
               
                 A14 
                  9.0173E+00 
                  1.4073E−01 
                 −1.5578E−01 
                 −6.3361E−03 
                  9.6616E−04 
                  2.3053E−03 
               
               
                 A16 
                 −7.9609E+00 
                 −4.8976E−02 
                  5.0456E−02 
                 −1.6693E−04 
                 −2.6272E−04 
                 −2.7954E−04 
               
               
                 A18 
                  4.0233E+00 
                  1.0470E−02 
                 −8.7868E−03 
                  1.6715E−04 
                  2.9382E−05 
                  1.9344E−05 
               
               
                 A20 
                 −8.8841E−01 
                 −1.1096E−03 
                  6.1879E−04 
                 −1.4419E−05 
                 −1.2429E−06 
                 −5.8448E−07 
               
               
                   
               
            
           
         
       
     
     In addition, according to the parameter information provided above, the following relations can be derived: 
     
       
         
           
             
               
                 CT 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 1 
                 ⁢ 
                 
                   / 
                 
                 ⁢ 
                 SD 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 11 
               
               = 
               0.712 
             
             ; 
             
               
                 TTL 
                 ⁢ 
                 
                   / 
                 
                 ⁢ 
                 CT 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 1 
               
               = 
               7.69 
             
             ; 
             
               FNO 
               = 
               2.35 
             
             ; 
             
               
                 f 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 3 
                 ⁢ 
                 
                   / 
                 
                 ⁢ 
                 f 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 4 
               
               = 
               1.707 
             
             ; 
           
         
       
       
         
           
             
               
                 
                   f 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   4 
                   ⁢ 
                   
                     / 
                   
                   ⁢ 
                   f 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   1 
                 
                 + 
                 
                   f 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   5 
                   ⁢ 
                   
                     / 
                   
                   ⁢ 
                   f 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   6 
                 
               
               = 
               3.10 
             
             ; 
             
               
                 f 
                 ⁢ 
                 
                   / 
                 
                 ⁢ 
                 f 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 12 
               
               = 
               1.16 
             
             ; 
             
               
                 TT 
                 ⁢ 
                 
                   / 
                 
                 ⁢ 
                 ImgH 
               
               = 
               1.08 
             
             ; 
             
               
                 R 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 9 
                 ⁢ 
                 
                   / 
                 
                 ⁢ 
                 R 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 10 
               
               = 
               
                 - 
                 0.86 
               
             
             ; 
           
         
       
       
         
           
             
               
                 
                    
                   
                     f 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     6 
                   
                    
                 
                 ⁢ 
                 
                   / 
                 
                 ⁢ 
                 R 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 12 
               
               = 
               1.89 
             
             ; 
             
               
                 CT 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 5 
                 ⁢ 
                 
                   / 
                 
                 ⁢ 
                 
                    
                   
                     SAG 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     51 
                   
                    
                 
               
               = 
               2.61 
             
           
         
       
     
     Sixth Embodiment 
     Referring to  FIGS. 11 and 12 ,  FIG. 11  is a schematic view of an optical system  100  in the sixth embodiment. The optical system  100  includes, sequentially arranged from an object side to an image side, an optical stop STO, a first lens L 1  having a positive refractive power, a second lens L 2  having a positive refractive power, a third lens L 3  having a negative refractive power, a fourth lens L 4  having a negative refractive power, a fifth lens L 5  having a positive refractive power, and a sixth lens L 6  having a negative refractive power.  FIG. 12  is, sequentially from left to right, graphs of spherical aberration, astigmatism, and distortion of the optical system  100  in the sixth embodiment. 
     An object side surface S 1  of the first lens L 1  is convex at its paraxial position and convex at its circumference. 
     An image side surface S 2  of the first lens L 1  is concave at its paraxial position and concave at its circumference. 
     An object side surface S 3  of the second lens L 2  is convex at its paraxial position and convex at its circumference. 
     An image side surface S 4  of the second lens L 2  is concave at its paraxial position and convex at its circumference. 
     An object side surface S 5  of the third lens L 3  is concave at its paraxial position and concave at its circumference. 
     An image side surface S 6  of the third lens L 3  is concave at its paraxial position and concave at its circumference. 
     An object side surface S 7  of the fourth lens L 4  is concave at its paraxial position and concave at its circumference. 
     An image side surface S 8  of the fourth lens L 4  is concave at its paraxial position and convex at its circumference. 
     An object side surface S 9  of the fifth lens L 5  is convex at its paraxial position and concave at its circumference. 
     An image side surface S 10  of the fifth lens L 5  is convex at its paraxial position and convex at its circumference. 
     An object side surface S 11  of the sixth lens L 6  is convex at its paraxial position and convex at its circumference. 
     An image side surface S 12  of the sixth lens L 6  is concave at its paraxial position and concave at its circumference. 
     The object side surfaces and the image side surfaces of the first lens L 1 , the second lens L 2 , the third lens L 3 , the fourth lens L 4 , the fifth lens L 5 , and the sixth lens L 6  are all aspherical. 
     The first lens L 1 , the second lens L 2 , the third lens L 3 , the fourth lens L 4 , the fifth lens L 5 , and the sixth lens L 6  are all made of plastic. 
     In addition, various parameters of the optical system  100  are given in Table 11, in which definitions of the various parameters can be obtained from the first embodiment, which will not be repeated here. 
     
       
         
           
               
             
               
                 TABLE 11 
               
             
            
               
                   
               
               
                 Sixth Embodiment 
               
               
                 f = 3.77 mm, FNO = 2.3, HFOV = 40.4°, TTL = 4.5 mm 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Surface 
                 Surface 
                 Surface 
                 Y radius 
                 Thickness 
                   
                 Refractive 
                 Abbe 
                 Focal length 
               
               
                 number 
                 name 
                 shape 
                 (mm) 
                 (mm) 
                 Material 
                 index 
                 number 
                 (mm) 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                   
                 Object plane 
                 Spherical 
                 Infinite 
                 400 
                   
                   
                   
                   
               
               
                   
                 Optical stop 
                 Spherical 
                 Infinite 
                 −0.201 
               
               
                 1 
                   
                 Aspherical 
                 1.592 
                 0.536 
                 Plastic 
                 1.546 
                 56.14 
                 4.48 
               
               
                 2 
                 First lens 
                 Aspherical 
                 4.018 
                 0.090 
               
               
                 3 
                   
                 Aspherical 
                 3.981 
                 0.410 
                 Plastic 
                 1.546 
                 56.14 
                 9.90 
               
               
                 4 
                 Second lens 
                 Aspherical 
                 14.560 
                 0.098 
               
               
                 5 
                   
                 Aspherical 
                 −13.756 
                 0.251 
                 Plastic 
                 1.666 
                 20.37 
                 −11.84 
               
               
                 6 
                 Third lens 
                 Aspherical 
                 18.630 
                 0.308 
               
               
                 7 
                   
                 Aspherical 
                 −67.607 
                 0.480 
                 Plastic 
                 1.640 
                 23.80 
                 −8.86 
               
               
                 8 
                 Fourth lens 
                 Aspherical 
                 6.207 
                 0.217 
               
               
                 9 
                   
                 Aspherical 
                 2.709 
                 0.500 
                 Plastic 
                 1.535 
                 55.71 
                 3.00 
               
               
                 10 
                 Fifth lens 
                 Aspherical 
                 −3.757 
                 0.330 
               
               
                 11 
                   
                 Aspherical 
                 18.560 
                 0.350 
                 Plastic 
                 1.546 
                 56.14 
                 −2.52 
               
               
                 12 
                 Sixth lens 
                 Aspherical 
                 1.273 
                 0.311 
               
               
                 13 
                 Infrared 
                 Spherical 
                 Infinite 
                 0.210 
                 Glass 
                 1.518 
                 64.17 
               
               
                 14 
                 filter 
                 Spherical 
                 Infinite 
                 0.409 
               
               
                 15 
                 Image plane 
                 Spherical 
                 Infinite 
                 0.000 
               
               
                   
               
            
           
         
       
     
     Further, the aspheric coefficients of the image side surfaces or the object side surfaces of the lenses of the optical system  100  are given in Table 12, in which definitions of the various parameters can be obtained from the first embodiment, which will not be repeated here. 
     
       
         
           
               
             
               
                 TABLE 12 
               
               
                   
               
               
                 Sixth Embodiment 
               
               
                 Aspheric coefficient 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Surface 
                   
                   
                   
                   
                   
                   
               
               
                 number 
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
               
                 K 
                 −4.4726E+00  
                 −2.4162E+01 
                 −3.3216E+01 
                 −5.0000E+01 
                 −5.0000E+01 
                 −5.0000E+01  
               
               
                 A4 
                 1.2661E−01 
                  9.4027E−03 
                  5.8523E−03 
                 −1.2024E−01 
                 −4.8794E−02 
                 5.1690E−02 
               
               
                 A6 
                 −7.4934E−02  
                 −8.3875E−03 
                  5.6976E−02 
                 −2.1807E−01 
                 −2.2636E−01 
                 −8.8972E−03  
               
               
                 A8 
                 8.6067E−02 
                 −3.2284E−01 
                 −1.1052E+00 
                  1.7108E−02 
                  3.9936E−01 
                 9.3582E−02 
               
               
                 A10 
                 −1.8805E−01  
                  2.1611E+00 
                  5.7261E+00 
                  9.3191E−01 
                 −7.0685E−01 
                 −5.1410E−02  
               
               
                 A12 
                 3.4540E−01 
                 −7.9428E+00 
                 −1.7757E+01 
                 −3.6823E+00 
                  1.1541E+00 
                 7.1390E−02 
               
               
                 A14 
                 −3.7349E−01  
                  1.8393E+01 
                  3.4405E+01 
                  8.3660E+00 
                  3.7784E−01 
                 −4.1583E−02  
               
               
                 A16 
                 1.6987E−01 
                 −2.6033E+01 
                 −4.0595E+01 
                 −9.0180E+00 
                 −2.2093E+00 
                 0.0000E+00 
               
               
                 A18 
                 0.0000E+00 
                  2.0714E+01 
                  2.7186E+01 
                  3.6235E+00 
                  1.2001E+00 
                 0.0000E+00 
               
               
                 A20 
                 0.0000E+00 
                 −6.8634E+00 
                 −7.8454E+00 
                  0.0000E+00 
                  0.0000E+00 
                 0.0000E+00 
               
               
                   
               
               
                 Surface 
                   
               
               
                 number 
                 7 
                 8 
                 9 
                 10 
                 11 
                 12 
               
               
                   
               
               
                 K 
                  5.0000E+01 
                 −4.0000E+01 
                 −1.0890E+01 
                 −4.0000E+01 
                 −4.0000E+01 
                 −6.2349E+00 
               
               
                 A4 
                 −1.4047E−01 
                 −2.4745E−01 
                 −2.5410E−02 
                  8.9961E−02 
                 −3.5416E−01 
                 −2.1720E−01 
               
               
                 A6 
                  3.1960E−01 
                  2.8686E−01 
                 −1.2123E−01 
                 −2.3028E−01 
                  1.5534E−01 
                  1.6727E−01 
               
               
                 A8 
                 −1.0713E+00 
                 −3.2850E−01 
                  2.9350E−01 
                  3.3376E−01 
                  1.6774E−02 
                 −9.3517E−02 
               
               
                 A10 
                  2.9599E+00 
                  2.9330E−01 
                 −4.0252E−01 
                 −2.7518E−01 
                 −3.0863E−02 
                  3.7000E−02 
               
               
                 A12 
                 −6.0215E+00 
                 −1.6961E−01 
                  3.3431E−01 
                  1.3450E−01 
                  9.5608E−03 
                 −1.0122E−02 
               
               
                 A14 
                  8.2085E+00 
                  4.7643E−02 
                 −1.7849E−01 
                 −4.0166E−02 
                 −1.2251E−03 
                  1.8270E−03 
               
               
                 A16 
                 −7.1168E+00 
                  2.2121E−03 
                  5.8899E−02 
                  7.2234E−03 
                  2.7664E−05 
                 −2.0558E−04 
               
               
                 A18 
                  3.5386E+00 
                 −4.5285E−03 
                 −1.0723E−02 
                 −7.2244E−04 
                  8.1923E−06 
                  1.3101E−05 
               
               
                 A20 
                 −7.7088E−01 
                  7.1432E−04 
                  8.1619E−04 
                  3.1108E−05 
                 −5.8557E−07 
                 −3.6432E−07 
               
               
                   
               
            
           
         
       
     
     In addition, according to the parameter information provided above, the following relations can be derived: 
     
       
         
           
             
               
                 CT 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 1 
                 ⁢ 
                 
                   / 
                 
                 ⁢ 
                 SD 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 11 
               
               = 
               0.636 
             
             ; 
             
               
                 TTL 
                 ⁢ 
                 
                   / 
                 
                 ⁢ 
                 CT 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 1 
               
               = 
               8.4 
             
             ; 
             
               FNO 
               = 
               2.30 
             
             ; 
             
               
                 f 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 3 
                 ⁢ 
                 
                   / 
                 
                 ⁢ 
                 f 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 4 
               
               = 
               1.336 
             
             ; 
           
         
       
       
         
           
             
               
                 
                   f 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   4 
                   ⁢ 
                   
                     / 
                   
                   ⁢ 
                   f 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   1 
                 
                 + 
                 
                   f 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   5 
                   ⁢ 
                   
                     / 
                   
                   ⁢ 
                   f 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   6 
                 
               
               = 
               3.17 
             
             ; 
             
               
                 f 
                 ⁢ 
                 
                   / 
                 
                 ⁢ 
                 f 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 12 
               
               = 
               1.18 
             
             ; 
             
               
                 TT 
                 ⁢ 
                 
                   / 
                 
                 ⁢ 
                 ImgH 
               
               = 
               1.08 
             
             ; 
             
               
                 R 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 9 
                 ⁢ 
                 
                   / 
                 
                 ⁢ 
                 R 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 10 
               
               = 
               
                 - 
                 0.72 
               
             
             ; 
           
         
       
       
         
           
             
               
                 
                    
                   
                     f 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     6 
                   
                    
                 
                 ⁢ 
                 
                   / 
                 
                 ⁢ 
                 R 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 12 
               
               = 
               1.98 
             
             ; 
             
               
                 CT 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 5 
                 ⁢ 
                 
                   / 
                 
                 ⁢ 
                 
                    
                   
                     SAG 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     51 
                   
                    
                 
               
               = 
               1.91 
             
           
         
       
     
     Referring to  FIG. 13 , in some embodiments, the optical system  100  can be assembled with a photosensitive element  210  to form an image capturing module  200 . In this case, a photosensitive surface of the photosensitive element  210  can be regarded as the image plane S 15  of the optical system  100 . The image capturing module  200  may further be provided with an infrared filter L 7 , and the infrared filter L 7  is arranged between the image side surface S 12  of the sixth lens L 6  and the image plane S 15 . Specifically, the photosensitive element  210  may be a Charge Coupled Device (CCD) or a Complementary Metal-Oxide Semiconductor Sensor (CMOS Sensor). The optical system  100  is used in the image capturing module  200  to enable the head of the camera lens being smaller, which can meet the requirements of miniaturization design of electronic devices. 
     Referring to  FIG. 14 , 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 mounted on the housing  310 . Specifically, the electronic device  300  may be, but is not limited to, a mobile phone, a video phone, a smart phone, an electronic book reader, a vehicle-mounted camera device such as a car recorder, or a wearable device such as a smart watch. The image capturing module  200  is used in the electronic device  300 , so that the head of the lens in the electronic device  300  is relatively small, which can meet the requirements of the miniaturization design of the electronic device  300 . Further, it can be understood that, in some embodiments, when the electronic device  300  is a smart phone, the lens of the electronic device  300  can be mounted in the housing  310  in an under-screen package manner. In this case, an opening needs to be defined in the screen of the electronic device  300  to expose the lens, so that light rays from the outside of the electronic device  300  can enter the inside of the electronic device  300  through the optical system  100  and form an image on the photosensitive surface of the photosensitive element  210 . The above image capturing module  200  is used in the electronic device  300 , so that the head of the lens is relatively small, and the lens can be exposed when the opening in the screen of the electronic device  300  is smaller, thereby increasing the screen-to-body ratio of the electronic device  300 , and further meeting the requirements of the miniaturization design of the electronic device  300 . 
     In the description of the present disclosure, it should be understood that the terms “center”, “longitudinal”, “transverse”, “length”, “width”, “thickness”, “upper”, “lower”, “front”, “rear”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc. indicate that the orientation or positional relationship is based on the orientation or positional relationship shown in the drawings, which is only for the purpose of facilitating the description of the present disclosure and simplifying the description, rather than indicating or implying that the device or elements must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as limitation of the present disclosure. 
     In addition, the terms “first” and “second” are used for purposes of description only, and cannot be understood to indicate or imply relative importance or implicitly indicate the number of technical features indicated. Therefore, the features defined “first” and “second” may explicitly or implicitly include at least one of the features. In the description of the present disclosure, the term “plurality” means at least two, such as two, three, etc., unless specifically defined otherwise. 
     In the present disclosure, unless otherwise clearly specified and limited, the term such as “mounted”, “interconnected”, “connected”, “fixed” should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection, or integrated; may be a mechanical connection or an electrical connection; may be a direct connection, or may be an indirect connection through an intermediate, may be a communication between two components or an interaction between two components, unless otherwise specified. Those ordinary skilled in the art can understand the specific meanings of the above terms in the present disclosure according to specific situations. 
     In the present disclosure, unless otherwise clearly specified and defined, the expression that a first feature is “above” or “below” a second feature may indicate that the first and second features are in direct contact, or the first and second features are in indirectly contact through an intermediate. The first feature is “at the top of”, “above”, and “over” the second feature may indicate that the first feature is directly or obliquely above the second feature, or only indicate that a level height of the first feature is higher than that of the second feature. The expression that a first feature is “beneath”, “below”, and “under” the second feature may indicate that the first feature is directly or obliquely below the second feature, or only indicates that the horizontal height of the first feature is lower than that of the second feature. 
     In the description of the present specification, descriptions with reference to the terms such as “an embodiment”, “some embodiments”, “examples”, “specific examples”, or “some examples” mean the specific features, structures, materials or characteristics described in conjunction with these embodiments or examples are included in at least one embodiment or example of the present disclosure. In the present specification, the schematic representations for the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine the different embodiments or examples and the features of the different embodiments or examples described in this specification without contradicting each other. 
     The technical features of the above embodiments can be combined arbitrarily. For concise description, not all possible combinations of the technical features in the above embodiments are described, but all of which should be considered to be within the scope described in this specification, as long as there is no contradiction between them. 
     The above-mentioned embodiments are merely illustrative of several embodiments of the present disclosure, which are described specifically and in detail, and cannot be understood to limit the scope of the present disclosure. It should be noted that, for those ordinary skilled in the art, several variations and improvements may be made without departing from the concept of the present disclosure, and these are all within the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure shall be subject to the appended claims.