Patent Publication Number: US-2022236528-A1

Title: Optical imaging system, image capturing apparatus, and electronic device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation application of International Application No. PCT/CN2019/111499, filed Oct. 16, 2019, the entire disclosure of which is incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     This application relates to the field of optical imaging technology, and more particularly to an optical imaging system, an image capturing apparatus, and an electronic device. 
     BACKGROUND 
     With the widespread availability of portable mobile electronic products such as mobile phones and wearable devices, users have increasing requirements for miniaturization and thinness of such mobile electronic products, same as a shooting apparatus and camera lenses loaded thereon. As a size of a chip continuously reduces and the number of pixels continuously increases, requirements for resolution of the camera lens are also gradually increased. Thus, an ultra-thin and miniaturized camera lens with good optical performance is needed. 
     The present application adopts a four-piece optical imaging system, which ensures miniaturization of the camera lens. Such a small number of lenses uses aspherical surfaces to obtain different shapes, which can provide a good optical performance. In particular, for a camera lens packed through a chip-scale-package (CSP) manufacturing process, since there is usually a protective glass packed in front of a photosensitive chip, a filter in the present application is placed in the middle, which leaves room for shortening a back focal length and facilitates ultra-thin design. In addition, for some optical imaging systems with large lens spacing, the filter can be placed in the middle to reduce an assembly step, thereby improving a yield stability. 
     SUMMARY 
     In view of above, a fourth-piece optical imaging system is provided, which can ensure miniaturization of the optical imaging system, reduce assembly steps (also called mismatch gaps) of various lenses of the optical imaging system, and improve a yield of the optical imaging system. 
     Also, it is necessary to provide an image capturing apparatus including the above-mentioned optical imaging system. 
     In addition, it is also necessary to provide an electronic device including the above-mentioned image capturing apparatus. 
     An optical imaging system, includes, in order from an object side to an image side, a first lens with a positive refractive power, a second lens with a refractive power, a third lens with a refractive power, and a fourth lens with a refractive power. The optical imaging system further includes a stop located in front of an imaging surface of the optical imaging system, and a first infrared filter located between the first lens and the fourth lens. As such, assembly steps among lenses of the optical imaging system can be reduced, and miniaturization can be realized. 
     In an implementation, an object-side surface and an image-side surface of each of the first lens, the second lens, the third lens, and the fourth lens are aspheric, and at least one of the object-side surface or the image-side surface of the fourth lens has at least one inflection point. The aspheric lenses are used to make it easy to obtain a shape other than a spherical shape and obtain more control variables, which is beneficial to reducing aberration and obtaining high-quality images with a relatively small number of lenses. As such, the number of the lenses can be reduced, and the miniaturization requirements of the optical imaging system can be satisfied. At least one of the object-side surface or the image-side surface of the fourth lens has at least one inflection point, with aid of the inflection point, it is possible to correct an aberration of an off-axis field of view, restrain an incident angle of light to the imaging surface, and match more accurately with a photosensitive element. 
     In an implementation, an object-side surface of the first lens is convex near an optical axis and a periphery. The object-side surface of the first lens is convex in the vicinity of the optical axis, which can improve the positive refractive power of the first lens that undertakes the main imaging function of the optical imaging system, and facilitates ultra-thinness. 
     In an implementation, an image-side surface of the second lens is concave near an optical axis and a periphery. The image-side surface of the second lens is concave, which facilitates a better spherical aberration correction. 
     In an implementation, an object-side surface of the third lens is concave near a periphery, and an image-side surface of the third lens is convex near a periphery. The third lens L 3  can effectively reduce field curvature and distortion of the system and improve the imaging quality. 
     In an implementation, an object-side surface of the fourth lens is convex near the optical axis, and an image-side surface of the fourth lens is concave near the optical axis and is convex near a periphery. The image-side surface of the fourth lens is concave near the optical axis, which is beneficial to adjusting the back focal length. For the image-side surface of the fourth lens, a radius of curvature changes from concave to convex, to better correct the aberration of the off-axis field of view, restrain the incident angle of light to the imaging surface, and match more accurately with the photosensitive element. 
     In an implementation, the optical imaging system further includes a protective glass or a second infrared filter, where the protective glass or the second infrared filter is located between the fourth lens and the imaging surface. The protective glass is used for dustproof to protect the photosensitive element on the imaging surface. The second infrared filter is placed between the fourth lens and the imaging surface, which can filter out light in the infrared band, reduce some ghost images caused by stray light, and can also protect the photosensitive element to a certain extent. 
     In an implementation, the optical imaging system further includes a third infrared filter located in front of the first lens. The third infrared filter can cut off infrared light and reduce the adverse effect of infrared light on imaging. The third infrared filter is located in front of the first lens to match a new lens stacking form with a different lens barrel structure. At present, there is an assembly mode in which the first lens is finally assembled, the object-side surface of the first lens protrudes outside the lens barrel, and an infrared filter is placed in front of the first lens to protect a front end of the lens group. 
     In an implementation, the first infrared filter includes at least one first infrared filter. 
     In an implementation, the optical imaging system satisfies the following expression: 
       FNO&gt;2.0;         where FNO represents an f-number of the optical imaging system.       
     If FNO&lt;2.0, the optical imaging system is most likely to be a high-end imaging product, which has higher requirements for imaging quality, and the optical imaging system generally has a compact multi-piece structure, which makes it difficult to place the infrared filter in the middle. However, the present application can still be applied to other products with FNO&lt;2.0, especially for products manufactured through a CSP process, placing the infrared filter in the middle is more beneficial to compressing a total length of the optical imaging system. 
     In an implementation, the optical imaging system satisfies the following expression: 
         BF/TTL&lt; 0.21;         where BF represents a minimum distance from an image-side surface of the fourth lens to the imaging surface of the optical imaging system in a direction parallel to an optical axis, and TTL represents a distance from an object-side surface of the first lens to the imaging surface on the optical axis.       
     Usually, a filter and a complementary metal-oxide semiconductor (CMOS) photosensitive chip are also sequentially provided at an image side of the last lens of the optical imaging system (for example, the fourth lens in the present application). Light is first filtered by the filter before incident on the photosensitive chip, so the filter has a certain protective effect on the photosensitive chip, and also filters part of the light, which reduces stray light and light spots, etc. and makes the image have bright and sharp colors and good color reproduction. Generally, a few-piece optical imaging system has low pixels, and the infrared filter can be located in the middle for some specifications with low imaging requirements. In addition, a protective glass is packaged in front of a photosensitive chip of the product manufactured through the CSP process, and the infrared filter can be placed in the middle to leave room for compressing the back focus, which facilitates the ultra-thinness and miniaturization of the optical imaging system. 
     In an implementation, the optical imaging system satisfies the following expression: 
       MAX( T 12: T 23: T 34)&gt;0.4;         where T12 represents a distance from an image-side surface of the first lens to an object-side surface of the second lens on an optical axis, T23 represents a distance from an image-side surface of the second lens to an object-side surface of the third lens on the optical axis, T34 represents a distance from an image-side surface of the third lens to an object-side surface of the fourth lens on the optical axis, and MAX(T12:T23:T34) represents a maximum among T12, 123, and T34.       
     When the above expression is satisfied, each of the lenses in the optical imaging system is spaced apart from one another at a large interval, the assembly step is large, a mass production assembly is unstable, and the yield is poor. If an infrared filter is placed between lenses arranged at large intervals, the assembly step can be reduced, the yield can be improved, and a space can be saved for a mechanical back focus of the lens, which is beneficial to compressing a height of a camera lens. 
     In an implementation, the optical imaging system satisfies the following expression: 
       0.5&lt; f 1/ f&lt; 1.3;         where f represents an effective focal length of the optical imaging system, and f1 represents an effective focal length of the first lens.       
     Since the first lens L 1  is responsible for most of a positive refractive power of the optical imaging system, a reasonable positive refractive power of the first lens L 1  is more beneficial to shortening the optical imaging system and can effectively correct field curvature of the optical imaging system. 
     In an implementation, the optical imaging system satisfies the following expression: 
         R 1/ f&gt; 0.4;         where R1 represents a radius of curvature of an object-side surface of the first lens, and f represents a total effective focal length of the optical imaging system.       
     The object-side surface of the first lens L 1  is convex in the vicinity of the optical axis, which can improve the positive refractive power of the first lens L 1  that undertakes the main imaging function of the optical imaging system  100 , and facilitates ultra-thinness. If R1/f is lower than a lower limit, the positive refractive power of the first lens L 1  is excessively large relative to the entire optical imaging system, which makes an aberration correction difficult. 
     In an implementation, the optical imaging system satisfies the following expression: 
       3&lt; D/CT 4&lt;15;         where D represents an optical clear aperture of an image-side surface of the fourth lens, and CT4 represents a distance from an object-side surface of the fourth lens to the image-side surface of the fourth lens on an optical axis.       
     When the lens has a small thickness and a large outer diameter, the molding is difficult to be uniform, and it is easy to produce joint lines. When the above expression is satisfied, the fourth lens can be easily injection-molded, so that the plastic injected via a unilateral gate can easily reach the opposite side, which lowers an eccentricity of the lens and improves the yield of the optical imaging system. 
     In an implementation, the optical imaging system satisfies the following expression: 
       0.12&lt;|( R 7− R 8)/( R 7+ R 8)|&lt;0.51;
         where R7 represents a radius of curvature of an object-side surface of the fourth lens, and R8 represents a radius of curvature of an image-side surface of the fourth lens.       

     In an implementation, at least one of the second lens, the third lens, or the fourth lens has a negative refractive power. At least one of the second lens, the third lens, or the fourth lens has a negative refractive power, which can correct the spherical aberration caused by the positive refractive power of the first lens, and cooperates with other lenses to ensure a higher resolution of the optical imaging system. 
     By reasonable configuring radii of curvature of the object-side surface and the image-side surface of the fourth lens, the total optical length for imaging can be effectively shortened, which satisfies miniaturization requirements, and effectively improves the resolution of the optical imaging system. 
     An image capturing apparatus is further provided in the present application. The image capturing apparatus includes the above-mentioned optical imaging system and a photosensitive element located on the imaging surface of the optical imaging system. 
     An electronic device is further provided in the present application. The electronic device includes a body and the above-mentioned image capturing apparatus, where the image capturing apparatus is installed on the body. 
     Thus, the present application adopts a four-piece optical imaging system with the first infrared filter between the first lens and the fourth lens. As such, miniaturization of the optical imaging system is realized, the assembly step of the optical imaging system is reduced, and assembly stability of the optical imaging system is improved, which improves the yield of the optical imaging system and lows a cost. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Structures, features, and functions of the present application are more clearly described hereinafter with reference to the accompanying drawings and the implementations. 
         FIG. 1  is a schematic structural view of an optical imaging system according to an implementation of the present application. 
         FIG. 2  illustrates from left to right a spherical aberration curve, an astigmatic curve, and a distortion curve of the optical imaging system illustrated in  FIG. 1 . 
         FIG. 3  is a schematic structural view of an optical imaging system according to an implementation of the present application. 
         FIG. 4  illustrates from left to right a spherical aberration curve, an astigmatic curve, and a distortion curve of the optical imaging system illustrated in  FIG. 3 . 
         FIG. 5  is a schematic structural view of an optical imaging system according to an implementation of the present application. 
         FIG. 6  illustrates from left to right a spherical aberration curve, an astigmatic curve, and a distortion curve of the optical imaging system illustrated in  FIG. 5 . 
         FIG. 7  is a schematic structural view of an optical imaging system according to an implementation of the present application. 
         FIG. 8  illustrates from left to right a spherical aberration curve, an astigmatic curve, and a distortion curve of the optical imaging system illustrated in  FIG. 7 . 
         FIG. 9  is a schematic structural view of an optical imaging system according to an implementation of the present application. 
         FIG. 10  illustrates from left to right a spherical aberration curve, an astigmatic curve, and a distortion curve of the optical imaging system illustrated in  FIG. 9 . 
         FIG. 11  is a schematic structural view of an optical imaging system according to an implementation of the present application. 
         FIG. 12  illustrates from left to right a spherical aberration curve, an astigmatic curve, and a distortion curve of the optical imaging system illustrated in  FIG. 11 . 
         FIG. 13  is a schematic structural view of an image capturing apparatus according to an implementation of a second aspect of the present application. 
         FIG. 14  is a schematic structural view of an electronic device according to an implementation of a third aspect of the present application. 
     
    
    
     DETAILED DESCRIPTION 
     Technical solutions in implementations of the present application will be described clearly and completely hereinafter with reference to the accompanying drawings in the implementations of the present application. Apparently, the described implementations are merely some rather than all implementations of the present application. All other implementations obtained by those of ordinary skill in the art based on the implementations of the present application without creative efforts shall fall within the protection scope of the present application. 
     Referring to  FIG. 1 ,  FIG. 3 ,  FIG. 5 ,  FIG. 7 ,  FIG. 9 , and  FIG. 11 , an optical imaging system  100  provided in a first aspect of the present application is applied to a camera lens. The optical imaging system  100  includes, in order from an object side to an image side, a first lens L 1  with a positive refractive power, a second lens L 2  with a refractive power, a third lens L 3  with a refractive power, and a fourth lens L 4  with a refractive power. The optical imaging system  100  further includes a stop  10  and a first infrared filter  31 . The stop  10  is located in front of an imaging surface of the optical imaging system  100 . The first infrared filter  31  is located between the first lens L 1  and the fourth lens L 4 . 
     Optionally, the first lens L 1  is made of plastic and has an object-side surface S 1  and an image-side surface S 2 . The object-side surface S 1  and the image-side surface S 2  of the first lens L 1  are aspheric. The object-side surface S 1  of the first lens L 1  is convex near an optical axis and a periphery. The image-side surface S 2  of the first lens L 1  can be convex or concave near the optical axis and can be convex or concave near a periphery. The first lens L 1  is an aspheric lens, which can facilitate light converging and image formation. It is easy to form other shapes other than a spherical shape, obtain more control variables, and obtain a high-quality image with fewer lenses, which reduces the number of the lenses and satisfies miniaturization requirements. 
     Optionally, the second lens L 2  is made of plastic and has an object-side surface S 3  and an image-side surface S 4 . The object-side surface S 3  and the image-side surface S 4  of the second lens L 2  are aspheric. The object-side surface S 3  of the second lens L 2  can be convex or concave near the optical axis and can be convex or concave near a periphery. The image-side surface S 4  of the second lens L 2  is convex near the optical axis and a periphery. The second lens L 2  can have a positive refractive power or a negative refractive power. The second lens L 2  is an aspheric lens, it is easy to form other shapes other than the spherical shape and obtain more control over the variables, which is beneficial to reducing the aberration and obtaining the high-quality image with fewer lenses. As such, the number of the lenses can be reduced, and the miniaturization requirements of the optical imaging system can be satisfied. The image-side surface S 4  of the second lens L 2  is concave, which facilitates a spherical aberration correction. 
     Optionally, the third lens L 3  is made of plastic and has an object-side surface S 5  and an image-side surface S 6 . The object-side surface S 5  and the image-side surface S 6  of the third lens L 3  are aspheric. The object-side surface S 5  of the third lens L 3  can be convex or concave near the optical axis and can be concave near a periphery. The image-side surface S 6  of the third lens L 3  can be convex or concave near the optical axis and can be convex near a periphery. The third lens L 3  can have a positive refractive power or a negative refractive power. The third lens L 3  can effectively reduce field curvature and distortion of the optical imaging system and improve imaging quality. The third lens L 3  is an aspheric lens, it is easy to form other shapes other than the spherical shape and obtain more control over the variables, which is beneficial to reducing the aberration and obtaining the high-quality image with fewer lenses. As such, the number of the lenses can be reduced, and the miniaturization requirements of the optical imaging system can be satisfied. 
     Optionally, the fourth lens L 4  is made of plastic and has an object-side surface S 7  and an image-side surface S 8 . The object-side surface S 7  and the image-side surface S 8  of the fourth lens L 4  are aspheric. The object-side surface S 7  of the fourth lens L 4  is convex near the optical axis and can be convex or concave near a periphery. The image-side surface S 8  of the fourth lens L 4  is concave near the optical axis and is convex near a periphery. The fourth lens L 4  can have a positive refractive power or a negative refractive power. The image-side surface of the fourth lens is concave near the optical axis, which is beneficial to adjusting the back focal length. For the image-side surface of the fourth lens, a radius of curvature changes from concave to convex, to better correct the aberration of the off-axis field of view, restrain the incident angle of light to the imaging surface, and match more accurately with the photosensitive element. 
     Optionally, at least one of the second lens L 2 , the third lens L 3 , or the fourth lens L 4  has a negative refractive power. At least one of the second lens L 2 , the third lens L 3 , or the fourth lens L 4  has a negative refractive power, which can correct the spherical aberration caused by the positive refractive power of the first lens, and cooperates with other lenses to ensure a higher resolution of the optical imaging system. 
     Optionally, the stop  10  can be located at any position in the optical imaging system  100 . The stop  10  can be located on the object-side surface of the first lens L 1 , or between the second lens L 2  and the third lens L 3 , or between the third lens L 3  and the fourth lens L 4 , etc. 
     Optionally, the infrared filter  31  is made of glass and has an object-side surface S 9  and an image-side surface S 10 . The object-side surface S 9  and the image-side surface S 10  of the infrared filter  31  are spheric. The first infrared filter  31  may be located at any position between the first lens L 1  and the second lens L 4 . More specifically, as illustrated in  FIG. 9 , the first infrared filter  31  is located between the first lens and the second lens; or as illustrated in  FIGS. 1, 5, 7, and 11 , the first infrared filter  31  is located between the second lens and the third lens; or as illustrated in  FIG. 3 , the first infrared filter  31  is located between the third lens and the fourth lens. The first infrared filter  31  can include at least one first infrared filter  31 . More specifically, the first infrared filter  31  can include one first infrared filter  31  (as illustrated in  FIGS. 1, 3, 5, 7, and 9 ), or two first infrared filters  31  (as illustrated in  FIG. 11 ), or three first infrared filters  31 . The infrared filter is usually located in front of a photosensitive element to filter out light with a wavelength different from that of visible light and reduce or eliminate a ghost image, stray light, and other adverse factor to the image. In the present application, the infrared filter is located in the middle, instead the rear, of the optical imaging system to reduce the mechanical back focal length of the camera lens, which is beneficial to realizing the miniaturization design. The filter is located between two adjacent lenses with a large air gap therebetween, such that various elements are compactly assembled together, a bearing step is reduced, and an actual production yield is more stable. 
     The term “element” in the present application refers to a lens, a lens barrel, a light shielding sheet, a gasket of a camera, or a component of other lens products. 
     The term “ghost image” in the present application refers to a duplicate image formed in the vicinity of a focal plane of the optical imaging system caused by reflections from lens surfaces, which is dim and offset with an original image. 
     In the four-piece optical imaging system  100  of the present application, the first infrared filter  30  is located between the first lens L 1  and the fourth lens L 4 , the miniaturization of the optical imaging system  100  is achieved, the assembly step of the optical imaging system  100  is reduced, and assembly stability of the optical imaging system  100  can be improved. As such, the yield of the optical imaging system  100  is improved and the cost is lowered. 
     In some implementations, at least one of the object-side surface S 7  or the image-side surface S 8  has at least one inflection point. The inflection point refers to a point where a radius of curvature changes from being negative to positive or from being positive to negative. The inflection point can be used to correct the aberration of an off-axis field of view and restrain an incident angle of light to an imaging surface so as to match the photosensitive element more precisely. 
     In some implementations, the optical imaging system  100  of the present application further includes a protective glass  50  or a second infrared filter  33 , where the protective glass  50  or the second infrared filter  33  is located between the fourth lens L 4  and the imaging surface  60 . The protective glass  50  is used for dustproof to protect photosensitive elements on the imaging surface  60 . The protective glass  50  has an object-side surface  51  and an image-side surface  53 . The second infrared filter  33  has an object-side surface S 11  and an image-side surface S 12 , which can filter out light in the infrared band, reduce some ghost images caused by stray light, and can also protect the photosensitive element to a certain extent 
     In some implementations, the optical imaging system  100  of the present application further includes a third infrared filter  35  located in front of the first lens L 1 . The third infrared filter  35  has an object-side surface S 13  and an image-side surface S 14 . The third infrared filter can cut off infrared light and reduce the adverse effect of infrared light on imaging. The third infrared filter is located in front of the first lens to match a new lens stacking form with a different lens barrel structure. At present, there is an assembly mode in which the first lens is finally assembled, the object-side surface of the first lens protrudes outside the lens barrel, and an infrared filter is placed in front of the first lens to protect a front end of the lens group. 
     In some implementations, the optical imaging system  100  satisfies the following expression: 
       FNO&gt;2.0;         where FNO represents an f-number of the optical imaging system.       
     In other words, FNO may be any value greater than 2.0. For example, FNO may be 2.0, 2.5, 3.0, 4.0, etc. 
     If FNO&lt;2.0, the optical imaging system  100  is most likely to be a high-end imaging product, which has higher requirements for imaging quality, and the optical imaging system  100  generally has a compact multi-piece structure, which makes it difficult to place the infrared filter in the middle. However, the present application can still be applied to other products with FNO&lt;2.0, especially for products manufactured through a CSP process, placing the infrared filter in the middle is more beneficial to compressing a total length of the optical imaging system  100 . 
     In some implementations, the optical imaging system  100  satisfies the following expression: 
         BF/TTL&lt; 0.21;         where BF represents a minimum distance from an image-side surface of the fourth lens to the imaging surface of the optical imaging system in a direction parallel to an optical axis, and TTL represents a distance from an object-side surface of the first lens to the imaging surface on the optical axis.       
     In other words, BF/TTL may be any value ranging from 0 to 0.21. For example, BF/TTL may be 0.1, 0.15, 0.18, 0.2, etc. 
     Usually, a filter and a complementary metal-oxide semiconductor (CMOS) photosensitive chip are also sequentially provided at an image side of the last lens of the optical imaging system (for example, the fourth lens L 4  in the present application). Light is first filtered by the filter before incident on the photosensitive chip, so the filter has a certain protective effect on the photosensitive chip, and also filters part of the light, which reduces stray light and light spots, etc. and makes the image have bright and sharp colors and good color reproduction. Generally, a few-piece optical imaging system has low pixels, and the infrared filter can be located in the middle for some specifications with low imaging requirements. In addition, a protective glass is packaged in front of a photosensitive chip of the product manufactured through the CSP process, and placing the infrared filter in the middle can leave room for compressing the back focus, which facilitates the ultra-thinness and miniaturization of the optical imaging system. 
     In some implementations, the optical imaging system  100  satisfies the following expression: 
       MAX( T 12: T 23: T 34)&gt;0.4;         where T12 represents a distance from an image-side surface of the first lens to an object-side surface of the second lens on an optical axis, T23 represents a distance from an image-side surface of the second lens to an object-side surface of the third lens on the optical axis, T34 represents a distance from an image-side surface of the third lens to an object-side surface of the fourth lens on the optical axis, and MAX(T12:T23:T34) represents a maximum among T12, 123, and T34.       
     In other words, MAX(T12:T23:T34) may be any value greater than 0.4. For example, FNO may be 0.5, 0.8, 1.0, 1.5, 1.8, etc. 
     When the above expression is satisfied, each of the lenses in the optical imaging system  100  is spaced apart from one another at a large interval, the assembly step is large, a mass production assembly is easily unstable, and the yield is poor. If an infrared filter is placed between lenses arranged at large intervals, the assembly step can be reduced, the yield can be improved, and a space can be saved for a mechanical back focus, which is beneficial to compressing a height of a camera lens. 
     In some implementations, the optical imaging system  100  satisfies the following expression: 
       0.5&lt; f 1/ f&lt; 1.3;         where f represents an effective focal length of the optical imaging system, and f1 represents an effective focal length of the first lens.       
     In other words, f1/f may be any value ranging from 0.5 to 1.3. For example, FNO may be 0.6, 0.8, 1.0, 1.1, 1.2, etc. 
     Since the first lens L 1  is responsible for most of a positive refractive power of the optical imaging system, a reasonable positive refractive power of the first lens L 1  is more beneficial to shortening the optical imaging system  100  and can effectively correct field curvature of the optical imaging system. 
     In some implementations, the optical imaging system satisfies the following expression: 
         R 1/ f&gt; 0.4;         where R1 represents a radius of curvature of an object-side surface of the first lens, and f represents a total effective focal length of the optical imaging system.       
     In other words, R1/f may be any value greater than 0.4. For example, R1/f may be 0.5, 0.8, 1.0, 1.5, 1.8, etc. 
     The object-side surface of the first lens L 1  is convex in the vicinity of the optical axis, which can improve the positive refractive power of the first lens L 1  that undertakes the main imaging function of the optical imaging system  100 , and facilitates ultra-thinness. If R1/f is lower than a lower limit, the positive refractive power of the first lens L 1  is excessively large relative to the entire optical imaging system  100 , which makes an aberration correction difficult. 
     In some implementations, the optical imaging system  100  satisfies the following expression: 
       3&lt; D/CT 4&lt;15;         where D represents an optical clear aperture of an image-side surface of the fourth lens, and CT4 represents a distance from an object-side surface of the fourth lens to the image-side surface of the fourth lens on an optical axis.       
     In other words, D/CT4 may be any value ranging from 3 to 15. For example, D/CT4 may be 4, 5, 6, 7, 8, 10, 12, 15, etc. 
     When the lens has a small thickness and a large outer diameter, the molding is difficult to be uniform, and it is easy to produce joint lines. When the above expression is satisfied, the fourth lens L 4  can be easily injection-molded, so that the plastic injected via a unilateral gate can easily reach the opposite side, which lowers an eccentricity of the lens and improves the yield of the optical imaging system. 
     In some implementations, the optical imaging system  100  satisfies the following expression: 
       0.12&lt;|( R 7− R 8)/( R 7+ R 8)|&lt;0.51;
         where R7 represents a radius of curvature of an object-side surface of the fourth lens, and R8 represents a radius of curvature of an image-side surface of the fourth lens.       

     In other words, |(R7−R8)/(R7+R8)| may be any value ranging from 0.12 to 0.51. For example, |(R7−R8)/(R7+R8)| may be 0.15, 0.18, 0.2, 0.3, 0.4, 0.5, etc. 
     By reasonable configuring radii of curvature of the object-side surface and the image-side surface of the fourth lens L 4 , the total optical length for imaging can be effectively shortened, which satisfies miniaturization requirements, and effectively improves the resolution of the optical imaging system  100 . 
     The optical imaging system  100  of the present application will be further specifically described hereinafter with reference to several implementations. 
     Referring to  FIG. 1  and  FIG. 2 ,  FIG. 1  is a schematic structural view of an optical imaging system  100  according to an implementation of the present application.  FIG. 2  illustrates from left to right a spherical aberration curve, an astigmatic curve, and a distortion curve of the optical imaging system  100  illustrated in  FIG. 1 . As illustrated in  FIG. 1 , the optical imaging system  100  of this implementation includes, from an object side to an image side, a first lens L 1  with a positive refractive power, a second lens L 2  with a negative refractive power, a first infrared filter  31 , a third lens L 3  with a positive refractive power, a fourth lens L 4  with a negative refractive power, a protective glass  50 , and an imaging surface  60 . The optical imaging system  100  further includes a stop  10 . The stop  10  is located at an object side of the first lens L 1 . 
     The first lens L 1  is made of plastic. An object-side surface S 1  and an image-side surface S 2  of the first lens L 1  are aspheric. The object-side surface S 1  is convex near the optical axis and a periphery. The image-side surface S 2  is convex near the optical axis and a periphery. 
     The second lens L 2  is made of plastic. An object-side surface S 3  and an image-side surface S 4  of the second lens L 2  are aspheric. The object-side surface S 3  is convex near the optical axis and is concave near a periphery. The image-side surface S 4  is concave near the optical axis and a periphery. 
     The third lens L 3  is made of plastic. An object-side surface S 5  and an image-side surface S 6  of the third lens L 3  are aspheric. The object-side surface S 5  is concave near the optical axis and a periphery. The image-side surface S 6  is convex near the optical axis and a periphery. 
     The fourth lens L 4  is made of plastic. An object-side surface S 7  and an image-side surface S 8  of the fourth lens L 4  are aspheric. The object-side surface S 7  is convex near the optical axis and a periphery. The image-side surface S 8  is concave near the optical axis and is convex near a periphery. 
     In this implementation, FNO=2.09. BF=0.7, TTL=4.072, BF/TTL=0.172. MAX(T12:T23:T34)=0.509. f1=3.141, f=3.875, f1/f=0.811. R1=1.902, R1/f=0.491. D=4.526, CT4=0.459, D/CT4=9.861. R7=1.87, R8=0.705, |(R7−R8)/(R7+R8)|=0.452. 
     In this implementation, the optical imaging system  100  satisfies conditions in Table 1 and Table 2 below. 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Optical Imaging System 100 illustrated in FIG. 1 
               
               
                 EFL = 3.875, FNO = 2.09, FOV = 80.2, TTL = 4.072 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Surface 
                 Surface 
                 Surface 
                 Y 
                   
                   
                 Refractive 
                 Abbe 
                 Focal 
               
               
                 Number 
                 name 
                 type 
                 Radius 
                 Thickness 
                 Material 
                 index 
                 number 
                 length 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Object surface 
                   
                 Spheric 
                 Infinity 
                 400 
                   
                   
                   
                   
               
               
                 Stop 10 
                   
                 Spheric 
                 Infinity 
                 −0.093 
               
               
                 S1 
                 First Lens 
                 Aspheric 
                 1.902 
                 0.723 
                 Plastic 
                 1.544 
                 56.114 
                 3.141 
               
               
                 S2 
                   
                 Aspheric 
                 −15.055  
                 0.191 
               
               
                 S3 
                 Second Lens 
                 Aspheric 
                 3.545 
                 0.259 
                 Plastic 
                 1.661 
                 20.370 
                 −8.975 
               
               
                 S4 
                   
                 Aspheric 
                 2.161 
                 0.157 
               
               
                 S9 
                 First Infrared 
                 Spheric 
                 Infinity 
                 0.210 
                 Glass 
                 1.517 
                 64.167 
               
               
                 S10 
                 Filter 
                 Spheric 
                 Infinity 
                 0.142 
               
               
                 S5 
                 Third Lens 
                 Aspheric 
                 −3.508  
                 0.720 
                 Plastic 
                 1.544 
                 56.114 
                 2.278 
               
               
                 S6 
                   
                 Aspheric 
                 −0.985  
                 0.100 
               
               
                 S7 
                 Fourth Lens 
                 Aspheric 
                 1.870 
                 0.459 
                 Plastic 
                 1.544 
                 56.114 
                 −2.408 
               
               
                 S8 
                   
                 Aspheric 
                 0.705 
                 0.453 
               
               
                 S51 
                 Protective 
                 Spheric 
                 Infinity 
                 0.400 
                 Glass 
                 1.517 
                 64.167 
               
               
                 S53 
                 Glass 
                 Spheric 
                 Infinity 
                 0.258 
               
               
                 Imaging Surface 
                   
                 Spheric 
                 Infinity 
                 400 
               
               
                   
               
               
                 Note: 
               
               
                 a reference wavelength is d-line 555.0 nm 
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 2 
               
             
            
               
                   
               
               
                 Aspheric Coefficients of the Optical Imaging System 100 Illustrated in FIG. 1 
               
               
                 Aspheric Coefficients 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Surface 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 Number 
                 S1 
                 S2 
                 S3 
                 S4 
                 S5 
                 S6 
                 S7 
                 S8 
               
               
                   
               
               
                 K 
                  7.8062E−01 
                 −9.9000E+01 
                 −7.0815E+00 
                  1.9399E+00 
                 1.0634E+01 
                 −4.4082E+00 
                 −1.5657E+01 
                 −3.6421E+00 
               
               
                 A4 
                 −6.7783E−02 
                 −2.8649E−01 
                 −3.9106E−01 
                 −2.0655E−01 
                 1.5361E−01 
                 −2.7436E−01 
                 −2.5745E−01 
                 −2.0361E−01 
               
               
                 A6 
                  2.9714E−02 
                 −2.8555E−03 
                  2.0562E−01 
                 −1.9270E−01 
                 −4.4723E−01  
                  5.9691E−01 
                  2.0872E−01 
                  1.9936E−01 
               
               
                 A8 
                 −2.6177E−01 
                  1.8075E+00 
                 −1.3912E+00 
                  1.5264E+00 
                 1.6442E+00 
                 −1.2585E+00 
                 −1.6819E−01 
                 −1.4986E−01 
               
               
                 A10 
                 −4.9597E+00 
                 −1.4326E+01 
                  1.0549E+01 
                 −5.4394E+00 
                 −5.0134E+00  
                  2.1079E+00 
                  1.3915E−01 
                  8.0659E−02 
               
               
                 A12 
                  5.1636E+01 
                  5.9842E+01 
                 −3.8954E+01 
                  1.5159E+01 
                 1.1044E+01 
                 −2.5297E+00 
                 −7.9866E−02 
                 −2.9783E−02 
               
               
                 A14 
                 −2.2538E+02 
                 −1.4445E+02 
                  8.8647E+01 
                 −2.8340E+01 
                 −1.5752E+01  
                  2.1192E+00 
                  2.8813E−02 
                  7.2651E−03 
               
               
                 A16 
                  5.1550E+02 
                  2.0051E+02 
                 −1.2306E+02 
                  3.2219E+01 
                 1.3901E+01 
                 −1.1102E+00 
                 −6.3430E−03 
                 −1.1120E−03 
               
               
                 A18 
                 −6.0650E+02 
                 −1.4733E+02 
                  9.4699E+01 
                 −2.0123E+01 
                 −6.9282E+00  
                  3.1042E−01 
                  7.8481E−04 
                  9.6575E−05 
               
               
                 A20 
                  2.8989E+02 
                  4.3802E+01 
                 −3.0841E+01 
                  5.3103E+00 
                 1.4874E+00 
                 −3.4026E−02 
                 −4.2042E−05 
                 −3.6403E−06 
               
               
                   
               
            
           
         
       
     
     Table 2 illustrates aspherical data of the optical imaging system  100  illustrated in  FIG. 1 , where k represents a conic coefficient of each surface. A4 to A20 represent the fourth to twentieth order aspherical coefficients of each surface. 
     As illustrated in  FIG. 2 , an aberration of the optical imaging system  100  of the present application is still be controlled within a reasonable range on the premise of satisfying ultra-thinness and miniaturization, which ensures the imaging quality. 
     Referring to  FIG. 3  and  FIG. 4 ,  FIG. 3  is a schematic structural view of an optical imaging system  100  according to an implementation of the present application.  FIG. 4  illustrates from left to right a spherical aberration curve, an astigmatic curve, and a distortion curve of the optical imaging system  100  illustrated in  FIG. 3 . As illustrated in  FIG. 3 , the optical imaging system  100  of this implementation includes, from an object side to an image side, a first lens L 1  with a positive refractive power, a second lens L 2  with a negative refractive power, a third lens L 3  with a positive refractive power, a first infrared filter  31 , a fourth lens L 4  with a negative refractive power, a protective glass  50 , and an imaging surface  60 . The optical imaging system  100  further includes a stop  10 . The stop  10  is located at an object side of the first lens L 1 . 
     The first lens L 1  is made of plastic. An object-side surface S 1  and an image-side surface S 2  of the first lens L 1  are aspheric. The object-side surface S 1  is convex near the optical axis and a periphery. The image-side surface S 2  is concave near the optical axis and is convex near a periphery. 
     The second lens L 2  is made of plastic. An object-side surface S 3  and an image-side surface S 4  of the second lens L 2  are aspheric. The object-side surface S 3  is convex near the optical axis and a periphery. The image-side surface S 4  is concave near the optical axis and a periphery. 
     The third lens L 3  is made of plastic. An object-side surface S 5  and an image-side surface S 6  of the third lens L 3  are aspheric. The object-side surface S 5  is concave near the optical axis and a periphery. The image-side surface S 6  is convex near the optical axis and a periphery. 
     The fourth lens L 4  is made of plastic. An object-side surface S 7  and an image-side surface S 8  of the fourth lens L 4  are aspheric. The object-side surface S 7  is convex near the optical axis and is concave near a periphery. The image-side surface S 8  is concave near the optical axis and is convex near a periphery. 
     In this implementation, FNO=2.09. BF=0.7, TTL=3.687, BF/TTL=0.190. MAX(T12:T23:T34)=0.451. f1=3.394, f=2.73, f1/f=1.243. R1=1.696, R1/f=0.621. D=4.296, CT4=0.298, D/CT4=14.416. R7=1.404, R8=0.7, |(R7−R8)/(R7+R8)|=0.335. 
     In this implementation, the optical imaging system  100  satisfies conditions in Table 3 and Table 4 below. 
     
       
         
           
               
             
               
                 TABLE 3 
               
             
            
               
                   
               
               
                 Optical Imaging System 100 Illustrated in FIG. 3 
               
               
                 EFL = 2.73, FNO = 2.09, FOV = 81.6, TTL = 3.687 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Surface 
                 Surface 
                 Surface 
                 Y 
                   
                   
                 Refractive 
                 Abbe 
                 Focal 
               
               
                 Number 
                 name 
                 type 
                 Radius 
                 Thickness 
                 Material 
                 index 
                 number 
                 length 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Object surface 
                   
                 Spheric 
                 Infinity 
                 Infinity 
                   
                   
                   
                   
               
               
                 Stop 10 
                   
                 Spheric 
                 Infinity 
                 −0.103 
               
               
                 S1 
                 First Lens 
                 Aspheric 
                 1.696 
                 0.673 
                 Plastic 
                 1.544 
                 56.114 
                 3.394 
               
               
                 S2 
                   
                 Aspheric 
                 17.226  
                 0.174 
               
               
                 S3 
                 Second Lens 
                 Aspheric 
                 2.541 
                 0.260 
                 Plastic 
                 1.661 
                 20.370 
                 −13.345 
               
               
                 S4 
                   
                 Aspheric 
                 1.895 
                 0.318 
               
               
                 S5 
                 Third Lens 
                 Aspheric 
                 −3.764  
                 0.502 
                 Plastic 
                 1.544 
                 56.114 
                 2.805 
               
               
                 S6 
                   
                 Aspheric 
                 −1.140  
                 0.120 
               
               
                 S9 
                 First Infrared 
                 Spheric 
                 Infinity 
                 0.210 
                 Glass 
                 1.517 
                 64.167 
               
               
                 S10 
                 Filter 
                 Spheric 
                 Infinity 
                 0.120 
               
               
                 S7 
                 Fourth Lens 
                 Aspheric 
                 1.404 
                 0.298 
                 Plastic 
                 1.544 
                 56.114 
                 −3.009 
               
               
                 S8 
                   
                 Aspheric 
                 0.700 
                 0.404 
               
               
                 S51 
                 Protective 
                 Spheric 
                 Infinity 
                 0.400 
                 Glass 
                 1.517 
                 64.167 
               
               
                 S53 
                 Glass 
                 Spheric 
                 Infinity 
                 0.208 
               
               
                 Imaging Surface 
                   
                 Spheric 
                 Infinity 
                 0.000 
               
               
                   
               
               
                 Note: 
               
               
                 a reference wavelength is d-line 555.0 nm 
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 4 
               
             
            
               
                   
               
               
                 Aspheric Coefficients of the Optical Imaging System 100 illustrated in FIG. 3 
               
               
                 Aspheric Coefficients 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Surface 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 Number 
                 S1 
                 S2 
                 S3 
                 S4 
                 S5 
                 S6 
                 S7 
                 S8 
               
               
                   
               
               
                 K 
                  7.7077E−01 
                 −9.8416E+01 
                 −4.2755E+00 
                  1.9875E+00 
                  1.0186E+01 
                 −7.3324E+00 
                 −1.8771E+01 
                 −4.3398E+00 
               
               
                 A4 
                 −7.6455E−02 
                 −2.6112E−01 
                 −3.2914E−01 
                 −2.2306E−01 
                 −1.6670E−02 
                 −4.7769E−01 
                 −2.4323E−01 
                 −2.0552E−01 
               
               
                 A6 
                  3.0145E−01 
                 −3.1826E−01 
                 −3.4642E−01 
                  1.9737E−01 
                  1.4407E+00 
                  1.7617E+00 
                  1.2415E−01 
                  1.7655E−01 
               
               
                 A8 
                 −4.7004E+00 
                  4.1486E+00 
                  2.8487E+00 
                 −2.1762E+00 
                 −7.6878E+00 
                 −5.0706E+00 
                 −8.6360E−03 
                 −1.1561E−01 
               
               
                 A10 
                  3.3652E+01 
                 −2.4774E+01 
                 −1.4053E+01 
                  1.1304E+01 
                  2.4578E+01 
                  1.1353E+01 
                 −1.6597E−02 
                  5.1397E−02 
               
               
                 A12 
                 −1.4313E+02 
                  8.9866E+01 
                  5.3270E+01 
                 −3.1988E+01 
                 −5.0454E+01 
                 −1.7556E+01 
                  5.3132E−03 
                 −1.3678E−02 
               
               
                 A14 
                  3.6478E+02 
                 −1.9804E+02 
                 −1.1932E+02 
                  5.9688E+01 
                  6.6096E+01 
                  1.7755E+01 
                  1.7787E−03 
                  1.6198E−03 
               
               
                 A16 
                 −5.4342E+02 
                  2.5477E+02 
                  1.5022E+02 
                 −7.2306E+01 
                 −5.2516E+01 
                 −1.1020E+01 
                 −1.4301E−03 
                  7.6500E−05 
               
               
                 A18 
                  4.2948E+02 
                 −1.7408E+02 
                 −9.8973E+01 
                  5.0353E+01 
                  2.2666E+01 
                  3.7613E+00 
                  3.1748E−04 
                 −3.8350E−05 
               
               
                 A20 
                 −1.3575E+02 
                  4.8133E+01 
                  2.6550E+01 
                 −1.5038E+01 
                 −3.9981E+00 
                 −5.3674E−01 
                 −2.4562E−05 
                  2.6445E−06 
               
               
                   
               
            
           
         
       
     
     Table 4 illustrates aspherical data of the optical imaging system  100  illustrated in  FIG. 3 , where k represents a conic coefficient of each surface. A4 to A20 represent the fourth to twentieth order aspherical coefficients of each surface. 
     As illustrated in  FIG. 4 , an aberration of the optical imaging system  100  of the present application is still be controlled within a reasonable range on the premise of satisfying ultra-thinness and miniaturization, which ensures the imaging quality. 
     Referring to  FIG. 5  and  FIG. 6 ,  FIG. 5  is a schematic structural view of an optical imaging system  100  according to an implementation of the present application.  FIG. 6  illustrates from left to right a spherical aberration curve, an astigmatic curve, and a distortion curve of the optical imaging system  100  illustrated in  FIG. 5 . As illustrated in  FIG. 5 , the optical imaging system  100  of this implementation includes, from an object side to an image side, a first lens L 1  with a positive refractive power, a second lens L 2  with a negative refractive power, a stop  10 , a first infrared filter  31 , a third lens L 3  with a negative refractive power, a fourth lens L 4  with a positive refractive power, a protective glass  50 , and an imaging surface  60 . 
     The first lens L 1  is made of plastic. An object-side surface S 1  and an image-side surface S 2  of the first lens L 1  are aspheric. The object-side surface S 1  is convex near the optical axis and a periphery. The image-side surface S 2  is convex near the optical axis and a periphery. 
     The second lens L 2  is made of plastic. An object-side surface S 3  and an image-side surface S 4  of the second lens L 2  are aspheric. The object-side surface S 3  is concave near the optical axis and a periphery. The image-side surface S 4  is concave near the optical axis and a periphery. 
     The third lens L 3  is made of plastic. An object-side surface S 5  and an image-side surface S 6  of the third lens L 3  are aspheric. The object-side surface S 5  is convex near the optical axis and is concave near a periphery. The image-side surface S 6  is concave near the optical axis and is convex near a periphery. 
     The fourth lens L 4  is made of plastic. An object-side surface S 7  and an image-side surface S 8  of the fourth lens L 4  are aspheric. The object-side surface S 7  is convex near the optical axis and a periphery. The image-side surface S 8  is concave near the optical axis and is convex near a periphery. 
     In this implementation, FNO=2.50. BF=0.939, TTL=5.662, BF/TTL=0.166. MAX(T12:T23:T34)=1.906. f1=2.162, f=4.177, f1/f=0.518. R1=1.669, R1/f=0.400. D=3.298, CT4=0.952, D/CT4=3.464. R7=3.364, R8=4.345, |(R7−R8)/(R7−FR8)|=0.127. 
     In this implementation, the optical imaging system  100  satisfies conditions in Table 5 and Table 6 below. 
     
       
         
           
               
             
               
                 TABLE 5 
               
             
            
               
                   
               
               
                 Optical Imaging System 100 Illustrated in FIG. 5 
               
               
                 EFL = 4.177, FNO = 2.50, FOV = 36.0, TTL = 5.662 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Surface 
                 Surface 
                 Surface 
                 Y 
                   
                   
                 Refractive 
                 Abbe 
                 Focal 
               
               
                 Number 
                 name 
                 type 
                 Radius 
                 Thickness 
                 Material 
                 index 
                 number 
                 length 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Object surface 
                   
                 Spheric 
                 Infinity 
                 30.00 
                   
                   
                   
                   
               
               
                 S1 
                 First Lens 
                 Aspheric 
                 1.669 
                 0.979 
                 Plastic 
                 1.544 
                 56.114 
                 2.162 
               
               
                 S2 
                   
                 Aspheric 
                 −3.193  
                 0.104 
               
               
                 S3 
                 Second Lens 
                 Aspheric 
                 −3.062  
                 0.392 
                 Plastic 
                 1.640 
                 23.530 
                 −3.347 
               
               
                 S4 
                   
                 Aspheric 
                 7.668 
                 0.191 
               
               
                 Stop 10 
                   
                 Spheric 
                 Infinity 
                 0.309 
               
               
                 S9 
                 First Infrared 
                 Spheric 
                 Infinity 
                 0.300 
                 Glass 
                 1.517 
                 64.167 
               
               
                 S10 
                 Filter 
                 Spheric 
                 Infinity 
                 1.106 
               
               
                 S5 
                 Third Lens 
                 Aspheric 
                 9.019 
                 0.229 
                 Plastic 
                 1.544 
                 56.114 
                 −4.641 
               
               
                 S6 
                   
                 Aspheric 
                 1.960 
                 0.100 
               
               
                 S7 
                 Fourth Lens 
                 Aspheric 
                 3.364 
                 0.952 
                 Plastic 
                 1.640 
                 23.530 
                 16.756 
               
               
                 S8 
                   
                 Aspheric 
                 4.345 
                 0.463 
               
               
                 S51 
                 Protective 
                 Spheric 
                 Infinity 
                 0.400 
                 Glass 
                 1.517 
                 64.167 
               
               
                 S53 
                 glass 
                 Spheric 
                 Infinity 
                 0.138 
               
               
                 Imaging Surface 
                   
                 Spheric 
                 Infinity 
                 0.000 
               
               
                   
               
               
                 Note: 
               
               
                 a reference wavelength is d-line 555.0 nm 
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 6 
               
             
            
               
                   
               
               
                 Aspheric Coefficients of Optical Imaging System 100 Illustrated in FIG. 5 
               
               
                 Aspheric Coefficients 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Surface 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 Number 
                 S1 
                 S2 
                 S3 
                 S4 
                 S5 
                 S6 
                 S7 
                 S8 
               
               
                   
               
               
                 K 
                 −3.3574E−01  
                 −1.0068E+01  
                 −3.8205E+01  
                 2.0768E+00 
                  6.2067E+01 
                 −1.1995E+01 
                 −4.7152E+01  
                 −6.4932E+00 
               
               
                 A4 
                 3.4030E−03 
                 8.5193E−02 
                 2.0727E−02 
                 1.0040E−01 
                 −2.1857E−01 
                 −1.3312E−02 
                 7.3789E−02 
                 −7.1017E−02 
               
               
                 A6 
                 2.0058E−03 
                 −1.5152E−01  
                 8.5402E−03 
                 −7.9423E−02  
                 −3.2520E−02 
                 −2.4598E−01 
                 −2.1503E−01  
                  3.2168E−02 
               
               
                 A8 
                 −5.3582E−03  
                 2.0691E−01 
                 −4.4765E−02  
                 1.2632E−01 
                  8.2791E−02 
                  4.3494E−01 
                 3.1398E−01 
                 −1.7759E−02 
               
               
                 A10 
                 6.5573E−03 
                 −2.0656E−01  
                 1.1957E−01 
                 1.0014E−03 
                 −3.8794E−02 
                 −4.0352E−01 
                 −2.5794E−01  
                  1.1087E−02 
               
               
                 A12 
                 −7.6672E−03  
                 1.2847E−01 
                 −1.5329E−01  
                 −2.0074E−01  
                 −9.2747E−02 
                  2.0950E−01 
                 1.2023E−01 
                 −4.6776E−03 
               
               
                 A14 
                 4.3886E−03 
                 −4.5449E−02  
                 9.8880E−02 
                 2.4545E−01 
                  1.1035E−01 
                 −5.8202E−02 
                 −3.0074E−02  
                  1.0123E−03 
               
               
                 A16 
                 −1.4848E−03  
                 6.8168E−03 
                 −2.4752E−02  
                 −8.7554E−02  
                 −3.7833E−02 
                  6.7694E−03 
                 3.1298E−03 
                 −8.8393E−05 
               
               
                 A18 
                 0.0000E+00 
                 0.0000E+00 
                 0.0000E+00 
                 0.0000E+00 
                  0.0000E+00 
                  0.0000E+00 
                 0.0000E+00 
                  0.0000E+00 
               
               
                 A20 
                 0.0000E+00 
                 0.0000E+00 
                 0.0000E+00 
                 0.0000E+00 
                  0.0000E+00 
                  0.0000E+00 
                 0.0000E+00 
                  0.0000E+00 
               
               
                   
               
            
           
         
       
     
     Table 6 illustrates aspherical data of the optical imaging system  100  illustrated in  FIG. 5 , where k represents a conic coefficient of each surface. A4 to A20 represent the fourth to twentieth order aspherical coefficients of each surface. 
     As illustrated in  FIG. 6 , an aberration of the optical imaging system  100  of the present application is still be controlled within a reasonable range on the premise of satisfying ultra-thinness and miniaturization, which ensures the imaging quality. 
     Referring to  FIG. 7  and  FIG. 8 ,  FIG. 7  is a schematic structural view of an optical imaging system  100  according to an implementation of the present application.  FIG. 8  illustrates from left to right a spherical aberration curve, an astigmatic curve, and a distortion curve of the optical imaging system  100  illustrated in  FIG. 7 . As illustrated in  FIG. 7 , the optical imaging system  100  of this implementation includes, from an object side to an image side, a third infrared filter  35 , a first lens L 1  with a positive refractive power, a second lens L 2  with a negative refractive power, a stop  10 , a first infrared filter  31 , a third lens L 3  with a negative refractive power, a fourth lens L 4  with a negative refractive power, a protective glass  50 , and an imaging surface  60 . 
     The first lens L 1  is made of plastic. An object-side surface S 1  and an image-side surface S 2  of the first lens L 1  are aspheric. The object-side surface S 1  is convex near the optical axis and a periphery. The image-side surface S 2  is convex near the optical axis and a periphery. 
     The second lens L 2  is made of plastic. An object-side surface S 3  and an image-side surface S 4  of the second lens L 2  are aspheric. The object-side surface S 3  is concave near the optical axis and a periphery. The image-side surface S 4  is concave near the optical axis and a periphery. 
     The third lens L 3  is made of plastic. An object-side surface S 5  and an image-side surface S 6  of the third lens L 3  are aspheric. The object-side surface S 5  is convex near the optical axis and is concave near a periphery. The image-side surface S 6  is concave near the optical axis and is convex near a periphery. 
     The fourth lens L 4  is made of plastic. An object-side surface S 7  and an image-side surface S 8  of the fourth lens L 4  are aspheric. The object-side surface S 7  is convex near the optical axis and is concave near a periphery. The image-side surface S 8  is concave near the optical axis and is convex near a periphery. 
     In this implementation, FNO=2.50. BF=0.842, TTL=5.2, BF/TTL=0.162. MAX(T12:T23:T34)=1.693. f1=2.147, f=3.746, f1/f=0.573. R1=1.515, R1/f=0.404. D=3.602, CT4=0.4, D/CT4=9.005. R7=2.421, R8=2.084, |(R7−R8)/(R7+R8)|=0.075. 
     In this implementation, the optical imaging system  100  satisfies conditions in Table 7 and Table 8 below. 
     
       
         
           
               
             
               
                 TABLE 7 
               
             
            
               
                   
               
               
                 Optical Imaging System 100 Illustrated in FIG. 7 
               
               
                 EFL = 3.746, FNO = 2.5, FOV = 42.2, TTL = 5.2 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Surface 
                 Surface 
                 Surface 
                 Y 
                   
                   
                 Refractive 
                 Abbe 
                 Focal 
               
               
                 Number 
                 name 
                 type 
                 Radius 
                 Thickness 
                 Material 
                 index 
                 number 
                 length 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Object surface 
                   
                 Spheric 
                 Infinity 
                 30.00 
                   
                   
                   
                   
               
               
                 S13 
                 Third Infrared 
                 Spheric 
                 Infinity 
                 0.210 
                 Glass 
                 1.517 
                 64.167 
               
               
                 S14 
                 Filter 
                 Spheric 
                 Infinity 
                 0.100 
               
               
                 S1 
                 First Lens 
                 Aspheric 
                 1.515 
                 0.917 
                 Plastic 
                 1.544 
                 56.114 
                 2.147 
               
               
                 S2 
                   
                 Aspheric 
                 −4.073  
                 0.103 
               
               
                 S3 
                 Second Lens 
                 Aspheric 
                 −4.013  
                 0.373 
                 Plastic 
                 1.640 
                 23.530 
                 −3.572 
               
               
                 S4 
                   
                 Aspheric 
                 5.597 
                 0.100 
               
               
                 Stop 10 
                   
                   
                 Infinity 
                 0.248 
               
               
                 S9 
                 First Infrared 
                 Spheric 
                 Infinity 
                 0.300 
                 Glass 
                 1.517 
                 64.167 
               
               
                 S10 
                 Filter 
                 Spheric 
                 Infinity 
                 1.045 
               
               
                 S5 
                 Third Lens 
                 Aspheric 
                 8.450 
                 0.272 
                 Plastic 
                 1.544 
                 56.114 
                 −7.865 
               
               
                 S6 
                   
                 Aspheric 
                 2.814 
                 0.108 
               
               
                 S7 
                 Fourth Lens 
                 Aspheric 
                 2.421 
                 0.400 
                 Plastic 
                 1.640 
                 23.530 
                 −43.309 
               
               
                 S8 
                   
                 Aspheric 
                 2.084 
                 0.428 
               
               
                 S51 
                 Protective 
                 Spheric 
                 Infinity 
                 0.400 
                 Glass 
                 1.517 
                 64.167 
               
               
                 S53 
                 Glass 
                 Spheric 
                 Infinity 
                 0.195 
               
               
                 Imaging Surface 
                   
                 Spheric 
                 Infinity 
                 0.000 
               
               
                   
               
               
                 Note: 
               
               
                 a reference wavelength is d-line 555.0 nm 
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 8 
               
             
            
               
                   
               
               
                 Aspheric Coefficients of Optical Imaging System 100 Illustrated in FIG. 7 
               
               
                 Aspheric Coefficients 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Surface 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 Number 
                 S1 
                 S2 
                 S3 
                 S4 
                 S5 
                 S6 
                 S7 
                 S8 
               
               
                   
               
               
                 K 
                 −3.1367E−01  
                 −9.6413E+00  
                 −4.0812E+01  
                 2.6528E+00 
                 −9.9786E+00 
                 −7.5272E+00 
                 −2.5829E+01  
                 −8.4087E+00 
               
               
                 A4 
                 4.3206E−03 
                 6.7600E−02 
                 4.1368E−02 
                 8.1461E−02 
                 −1.4414E−01 
                 −8.4473E−02 
                 4.4998E−02 
                 −9.2574E−02 
               
               
                 A6 
                 4.6347E−03 
                 −1.2988E−01  
                 −9.4890E−02  
                 2.1317E−04 
                 −3.4033E−01 
                  3.8614E−02 
                 −1.0978E−01  
                  4.7941E−02 
               
               
                 A8 
                 −1.3969E−02  
                 2.1865E−01 
                 2.1564E−01 
                 −2.5093E−01  
                  1.1614E+00 
                 −2.1547E−01 
                 1.2569E−01 
                 −1.6701E−02 
               
               
                 A10 
                 2.3378E−02 
                 −2.6773E−01  
                 −2.3553E−01  
                 1.6479E+00 
                 −2.8060E+00 
                  3.1662E−01 
                 −7.1656E−02  
                  7.5024E−03 
               
               
                 A12 
                 −2.3008E−02  
                 2.0451E−01 
                 1.0411E−01 
                 −4.1283E+00  
                  3.7649E+00 
                 −2.1926E−01 
                 2.1252E−02 
                 −3.2835E−03 
               
               
                 A14 
                 1.0749E−02 
                 −8.6974E−02  
                 3.6881E−02 
                 5.1572E+00 
                 −2.6500E+00 
                  7.2176E−02 
                 −2.8838E−03  
                  8.6346E−04 
               
               
                 A16 
                 −2.6147E−03  
                 1.5322E−02 
                 −3.8684E−02  
                 −2.6182E+00  
                  7.4857E−01 
                 −8.9013E−03 
                 9.2291E−05 
                 −1.0424E−04 
               
               
                 A18 
                 0.0000E+00 
                 0.0000E+00 
                 0.0000E+00 
                 0.0000E+00 
                  0.0000E+00 
                  0.0000E+00 
                 0.0000E+00 
                  0.0000E+00 
               
               
                 A20 
                 0.0000E+00 
                 0.0000E+00 
                 0.0000E+00 
                 0.0000E+00 
                  0.0000E+00 
                  0.0000E+00 
                 0.0000E+00 
                  0.0000E+00 
               
               
                   
               
            
           
         
       
     
     Table 8 illustrates aspherical data of the optical imaging system  100  illustrated in  FIG. 7 , where k represents a conic coefficient of each surface. A4 to A20 represent the fourth to twentieth order aspherical coefficients of each surface. 
     As illustrated in  FIG. 8 , an aberration of the optical imaging system  100  of the present application is still be controlled within a reasonable range on the premise of satisfying ultra-thinness and miniaturization, which ensures the imaging quality. 
     Referring to  FIG. 9  and  FIG. 10 ,  FIG. 9  is a schematic structural view of an optical imaging system  100  according to an implementation of the present application.  FIG. 10  illustrates from left to right a spherical aberration curve, an astigmatic curve, and a distortion curve of the optical imaging system  100  illustrated in  FIG. 9 . As illustrated in  FIG. 9 , the optical imaging system  100  of this implementation includes, from an object side to an image side, a stop  10 , a first lens L 1  with a positive refractive power, a first infrared filter  31 , a second lens L 2  with a negative refractive power, a third lens L 3  with a positive refractive power, a fourth lens L 4  with a negative refractive power, a second infrared filter  33 , and an imaging surface  60 . 
     The first lens L 1  is made of plastic. An object-side surface S 1  and an image-side surface S 2  of the first lens L 1  are aspheric. The object-side surface S 1  is convex near the optical axis and a periphery. The image-side surface S 2  is convex near the optical axis and a periphery. 
     The second lens L 2  is made of plastic. An object-side surface S 3  and an image-side surface S 4  of the second lens L 2  are aspheric. The object-side surface S 3  is convex near the optical axis and is concave near a periphery. The image-side surface S 4  is concave near the optical axis and a periphery. 
     The third lens L 3  is made of plastic. An object-side surface S 5  and an image-side surface S 6  of the third lens L 3  are aspheric. The object-side surface S 5  is concave near the optical axis and a periphery. The image-side surface S 6  is convex near the optical axis and a periphery. 
     The fourth lens L 4  is made of plastic. An object-side surface S 7  and an image-side surface S 8  of the fourth lens L 4  are aspheric. The object-side surface S 7  is convex near the optical axis and is concave near a periphery. The image-side surface S 8  is concave near the optical axis and is convex near a periphery. 
     In this implementation, FNO=2.40. BF=0.8, TTL=3.946, BF/TTL=0.203. MAX(T12:T23:T34)=0.41. f1=3.153, f=2.941, f1/f=1.072. R1=1.911, R1/f=0.650. D=3.976, CT4=0.431, D/CT4=9.225. R7=2.116, R8=0.695, |(R7−R8)/(R7+R8)|=0.506. 
     In this implementation, the optical imaging system  100  satisfies conditions in Table 9 and Table 10 below. 
     
       
         
           
               
             
               
                 TABLE 9 
               
             
            
               
                   
               
               
                 Optical Imaging System 100 Illustrated in FIG. 9 
               
               
                 EFL = 2.941, FNO = 2.4, FOV = 29.0, TTL = 3.946 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Surface 
                 Surface 
                 Surface 
                 Y 
                   
                   
                 Refractive 
                 Abbe 
                 Focal 
               
               
                 Number 
                 name 
                 type 
                 Radius 
                 Thickness 
                 Material 
                 index 
                 number 
                 length 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Object surface 
                   
                 Spheric 
                 Infinity 
                 400 
                   
                   
                   
                   
               
               
                 Stop 10 
                   
                 Spheric 
                 Infinity 
                 −0.055 
               
               
                 S1 
                 First Lens 
                 Aspheric 
                 1.911 
                 0.564 
                 Plastic 
                 1.544 
                 56.114 
                 3.153 
               
               
                 S2 
                   
                 Aspheric 
                 −15.546  
                 0.100 
               
               
                 S9 
                 First Infrared 
                 Aspheric 
                 Infinity 
                 0.210 
                 Glass 
                 1.517 
                 64.167 
               
               
                 S10 
                 Filter 
                 Aspheric 
                 Infinity 
                 0.100 
               
               
                 S3 
                 Second Lens 
                 Aspheric 
                 3.182 
                 0.224 
                 Plastic 
                 1.661 
                 20.368 
                 −11.134 
               
               
                 S4 
                   
                 Aspheric 
                 2.164 
                 0.321 
               
               
                 S5 
                 Third Lens 
                 Aspheric 
                 −3.298  
                 0.792 
                 Plastic 
                 1.544 
                 56.114 
                 2.178 
               
               
                 S6 
                   
                 Aspheric 
                 −0.948  
                 0.103 
               
               
                 S7 
                 Fourth Lens 
                 Asnheric 
                 2.116 
                 0.431 
                 Plastic 
                 1.544 
                 56.114 
                 −2.123 
               
               
                 S8 
                   
                 Aspheric 
                 0.695 
                 0.542 
               
               
                 S11 
                 Second Infrared 
                 Spheric 
                 Infinity 
                 0.210 
                 Glass 
                 1.517 
                 64.167 
               
               
                 S12 
                 Filter 
                 Spheric 
                 Infinity 
                 0.350 
               
               
                 Imaging Surface 
                   
                 Spheric 
                 Infinity 
                 0.000 
               
               
                   
               
               
                 Note: 
               
               
                 a reference wavelength is d-line 555.0 nm 
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 10 
               
             
            
               
                   
               
               
                 Aspheric Coefficients of the Optical Imaging System 100 Illustrated in FIG. 9 Aspheric Coefficients 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Surface 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 Number 
                 S1 
                 S2 
                 S3 
                 S4 
                 S5 
                 S6 
                 S7 
                 S8 
               
               
                   
               
               
                 K 
                 −1.5841E−01 
                 −9.9000E+01 
                 −6.7831E+00 
                  1.8672E+00 
                 1.0913E+01 
                 −4.3939E+00 
                 −2.9890E+01 
                 −3.9274E+00 
               
               
                 A4 
                 −9.3232E−02 
                 −2.6630E−01 
                 −3.4450E−01 
                 −1.8531E−01 
                 2.2854E−01 
                 −2.6350E−01 
                 −2.7429E−01 
                 −2.6156E−01 
               
               
                 A6 
                  3.0564E−01 
                  1.2107E−01 
                 −3.0861E−01 
                 −6.6682E−01 
                 −6.1152E−01  
                  5.0762E−01 
                 −2.4746E−02 
                  2.7439E−01 
               
               
                 A8 
                 −7.2703E+00 
                 −1.2899E+00 
                  1.8670E+00 
                  3.7250E+00 
                 2.1100E+00 
                 −8.0693E−01 
                  4.8805E−01 
                 −2.2367E−01 
               
               
                 A10 
                  7.0786E+01 
                  6.4077E+00 
                 −7.7276E+00 
                 −1.4109E+01 
                 −6.0302E+00  
                  6.3744E−01 
                 −8.4150E−01 
                  1.2931E−01 
               
               
                 A12 
                 −4.0820E+02 
                 −2.0373E+01 
                  2.6022E+01 
                  3.8084E+01 
                 1.2283E+01 
                  6.2126E−01 
                  7.9648E−01 
                 −5.1867E−02 
               
               
                 A14 
                  1.4155E+03 
                  4.2615E+01 
                 −4.8906E+01 
                 −6.4945E+01 
                 −1.7636E+01  
                 −2.1700E+00 
                 −4.4375E−01 
                  1.4075E−02 
               
               
                 A16 
                 −2.9044E+03 
                 −5.6968E+01 
                  5.1745E+01 
                  6.7402E+01 
                 1.7464E+01 
                  2.3496E+00 
                  1.4478E−01 
                 −2.4682E−03 
               
               
                 A18 
                  3.2441E+03 
                  4.3850E+01 
                 −2.9954E+01 
                 −3.9036E+01 
                 −1.0317E+01  
                 −1.1770E+00 
                 −2.5733E−02 
                  2.5380E−04 
               
               
                 A20 
                 −1.5193E+03 
                 −1.4828E+01 
                  7.4782E+00 
                  9.6035E+00 
                 2.6226E+00 
                  2.2710E−01 
                  1.9327E−03 
                 −1.1724E−05 
               
               
                   
               
            
           
         
       
     
     Table 10 illustrates aspherical data of the optical imaging system  100  illustrated in  FIG. 9 , where k represents a conic coefficient of each surface. A4 to A20 represent the fourth to twentieth order aspherical coefficients of each surface. 
     As illustrated in  FIG. 10 , an aberration of the optical imaging system  100  of the present application is still be controlled within a reasonable range on the premise of satisfying ultra-thinness and miniaturization, which ensures the imaging quality. 
     Referring to  FIG. 11  and  FIG. 12 ,  FIG. 11  is a schematic structural view of an optical imaging system  100  according to an implementation of the present application.  FIG. 12  illustrates from left to right a spherical aberration curve, an astigmatic curve, and a distortion curve of the optical imaging system  100  illustrated in  FIG. 11 . As illustrated in  FIG. 11 , the optical imaging system  100  of this implementation includes, from an object side to an image side, a first lens L 1  with a positive refractive power, a second lens L 2  with a negative refractive power, a first infrared filter  31 , a third lens L 3  with a positive refractive power, a first infrared filter  31 , a fourth lens L 4  with a negative refractive power, a second infrared filter  33 , and an imaging surface  60 . The optical imaging system  100  further includes a stop  10 . The stop  10  is located at an object side of the first lens L 1 . 
     The first lens L 1  is made of plastic. An object-side surface S 1  and an image-side surface S 2  of the first lens L 1  are aspheric. The object-side surface S 1  is convex near the optical axis and a periphery. The image-side surface S 2  is concave near the optical axis and a periphery. 
     The second lens L 2  is made of plastic. An object-side surface S 3  and an image-side surface S 4  of the second lens L 2  are aspheric. The object-side surface S 3  is convex near the optical axis and is concave near a periphery. The image-side surface S 4  is concave near the optical axis and a periphery. 
     The third lens L 3  is made of plastic. An object-side surface S 5  and an image-side surface S 6  of the third lens L 3  are aspheric. The object-side surface S 5  is concave near the optical axis and a periphery. The image-side surface S 6  is convex near the optical axis and a periphery. 
     The fourth lens L 4  is made of plastic. An object-side surface S 7  and an image-side surface S 8  of the fourth lens L 4  are aspheric. The object-side surface S 7  is convex near the optical axis and a periphery. The image-side surface S 8  is concave near the optical axis and is convex near a periphery. 
     In this implementation, FNO=2.20. BF=0.8, TTL=4.669, BF/TTL=0.171. MAX(T12:T23:T34)=0.986. f1=3.814, f=3.945, f1/f=0.967. R1=1.422, R1/f=0.360. D=5.306, CT4=0.424, D/CT4=12.514. R7=1.376, R8=0.994, |(R7−R8)/(R7+R8)|=0.161. 
     In this implementation, the optical imaging system  100  satisfies conditions in Table 11 and Table 12 below. 
     
       
         
           
               
             
               
                 TABLE 11 
               
             
            
               
                   
               
               
                 Optical Imaging System 100 Illustrated in FIG. 11 
               
               
                 EFL = 3.945, FNO = 2.2, FOV = 72.2, TTL = 4.669 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Surface 
                 Surface 
                 Surface 
                 Y 
                   
                   
                 Refractive 
                 Abbe 
                 Focal 
               
               
                 Number 
                 name 
                 type 
                 Radius 
                 Thickness 
                 Material 
                 index 
                 number 
                 length 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Object surface 
                   
                 Spheric 
                 Infinity 
                 Infinity 
                   
                   
                   
                   
               
               
                 Stop 10 
                   
                 Spheric 
                 Infinity 
                 −0.309 
               
               
                 S1 
                 First Lens 
                 Aspheric 
                 1.422 
                 0.498 
                 Plastic 
                 1.544 
                 56.114 
                 3.814 
               
               
                 S2 
                   
                 Aspheric 
                 3.932 
                 0.120 
               
               
                 S3 
                 Second Lens 
                 Aspheric 
                 2.773 
                 0.274 
                 Plastic 
                 1.640 
                 23.530 
                 −9.103 
               
               
                 S4 
                   
                 Aspheric 
                 1.810 
                 0.349 
               
               
                 S9 
                 First Infrared 
                 Spheric 
                 Infinity 
                 0.110 
                 Glass 
                 1.517 
                 64.167 
               
               
                 S10 
                 Filter 
                 Spheric 
                 Infinity 
                 0.317 
               
               
                 S5 
                 Third Lens 
                 Aspheric 
                 −3.617  
                 0.439 
                 Plastic 
                 1.544 
                 56.114 
                 7.865 
               
               
                 S6 
                   
                 Aspheric 
                 −2.047  
                 0.218 
               
               
                 S9 
                 First Infrared 
                 Spheric 
                 Infinity 
                 0.300 
                 Glass 
                 1.517 
                 64.167 
               
               
                 S10 
                 Filter 
                 Spheric 
                 Infinity 
                 0.468 
               
               
                 S7 
                 Fourth Lens 
                 Aspheric 
                 1.376 
                 0.424 
                 Plastic 
                 1.544 
                 56.114 
                 −10.779 
               
               
                 S8 
                   
                 Aspheric 
                 0.994 
                 0.353 
               
               
                 S11 
                 Second Infrared 
                 Spheric 
                 Infinity 
                 0.210 
                 Glass 
                 1.517 
                 64.167 
               
               
                 S12 
                 Filter 
                 Spheric 
                 Infinity 
                 0.588 
               
               
                 Imaging Surface 
                   
                 Spheric 
                 Infinity 
                 0.000 
               
               
                   
               
               
                 Note: 
               
               
                 a reference wavelength is d-line 555.0 nm 
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 12 
               
             
            
               
                   
               
               
                 Aspheric Coefficients of the Optical Imaging System 100 Illustrated in FIG. 11 
               
               
                 Aspheric Coefficients 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Surface 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 Number 
                 S1 
                 S2 
                 S3 
                 S4 
                 S5 
                 S6 
                 S7 
                 S8 
               
               
                   
               
               
                 K 
                 −5.8037E+00  
                 3.9470E+00 
                 −2.5076E+01 
                 −4.0629E+00  
                 4.9934E+00 
                 −1.9618E+00 
                 −4.0734E+00 
                 −1.9253E+00 
               
               
                 A4 
                 2.6155E−01 
                 −1.7152E−01  
                 −1.3466E−01 
                 −2.9771E−02  
                 −1.1979E−01  
                 −1.8410E−01 
                 −1.7154E−01 
                 −2.4288E−01 
               
               
                 A6 
                 −2.5116E−01  
                 2.1462E−01 
                 −3.8630E−02 
                 4.7641E−02 
                 8.2320E−02 
                  2.2935E−01 
                  1.2833E−02 
                  1.4368E−01 
               
               
                 A8 
                 5.1725E−01 
                 −2.6730E−01  
                  6.2183E−01 
                 5.6757E−01 
                 −1.5022E−01  
                 −6.0233E−01 
                  4.2816E−02 
                 −6.2944E−02 
               
               
                 A10 
                 −8.8733E−01  
                 5.8961E−01 
                 −1.3664E+00 
                 −1.5606E+00  
                 3.2004E−01 
                  1.2670E+00 
                 −2.6214E−02 
                  2.0051E−02 
               
               
                 A12 
                 1.1078E+00 
                 −1.1425E+00  
                  1.4451E+00 
                 2.3772E+00 
                 −6.1686E−01  
                 −1.7264E+00 
                  8.0768E−03 
                 −4.4146E−03 
               
               
                 A14 
                 −7.6132E−01  
                 1.2711E+00 
                 −7.1331E−01 
                 −2.0306E+00  
                 9.6883E−01 
                  1.4211E+00 
                 −1.5025E−03 
                  6.3457E−04 
               
               
                 A16 
                 2.2780E−01 
                 −6.1001E−01  
                  0.0000E+00 
                 7.6353E−01 
                 −7.4626E−01  
                 −6.1580E−01 
                  1.7014E−04 
                 −5.4890E−05 
               
               
                 A18 
                 0.0000E+00 
                 0.0000E+00 
                  0.0000E+00 
                 0.0000E+00 
                 2.0835E−01 
                  1.0630E−01 
                 −1.0815E−05 
                  2.4791E−06 
               
               
                 A20 
                 0.0000E+00 
                 0.0000E+00 
                  0.0000E+00 
                 0.0000E+00 
                 0.0000E+00 
                  0.0000E+00 
                  2.9577E−07 
                 −4.1498E−08 
               
               
                   
               
            
           
         
       
     
     Table 12 illustrates aspherical data of the optical imaging system  100  illustrated in  FIG. 11 , where k represents a conic coefficient of each surface. A4 to A20 represent the fourth to twentieth order aspherical coefficients of each surface. 
     As illustrated in  FIG. 12 , an aberration of the optical imaging system  100  of the present application is still be controlled within a reasonable range on the premise of satisfying ultra-thinness and miniaturization, which ensures the imaging quality. 
     Referring to  FIG. 13 , in a second aspect of the present application, an image capturing apparatus  200  is provided. The image capturing apparatus  200  includes the optical imaging system  100  as described in the first aspect and a photosensitive element  210  located on an imaging surface  60  of the optical imaging system  100 . 
     The photosensitive element  210  of the present application may be a charge coupled device (CCD) or a complementary metal-oxide semiconductor (CMOS sensor). 
     As for other features of the image capturing apparatus  200 , reference can be made to the first aspect of the present application, which is not repeated herein. 
     As can be seen in  FIG. 14 , in a third aspect of the present application, an electronic device  300  is provided. The electronic device  300  includes a body  310  and the image capturing apparatus  200  as described in the second aspect. The image capturing apparatus  200  is installed on the body  310 . 
     The electronic device  300  in the present application can include but is not limited to personal computers, laptops, tablet personal computers, a mobile phone, cameras, intelligent bands, intelligent watches, and intelligent glasses, etc. 
     While present application has been described specifically and in detail above with reference to several implementations, the scope of the present application is not limited thereto. As will occur to those skilled in the art, present application is susceptible to various modifications and substitution within the technical range of the present application. Any modifications or substitutions that can be made by those skilled in the art shall all be encompassed within the protection of the present application. Therefore, the scope of the present application should be determined by the scope of the claims.