Patent Publication Number: US-9851538-B2

Title: Optical imaging lens

Description:
RELATED APPLICATIONS 
     This application claims priority from China Patent Application No. 201610252412.3, filed on Apr. 21, 2016 and China Patent Application No. 201610352292.4, filed on May 25, 2016, the contents of which are hereby incorporated by reference in their entirety for all purposes. 
     TECHNICAL FIELD 
     The present disclosure relates to an optical imaging lens, and particularly, to an optical imaging lens having six lens elements. 
     BACKGROUND 
     Technology improves every day, continuously expanding consumer demand for increasingly compact electronic devices. This applies in the context of telephoto lens characteristics, in that key components for optical imaging lenses incorporated into consumer electronic products should keep pace with technological improvements in order to meet the expectations of consumers expectations. Some important characteristics of an optical imaging lens include image quality and size. Improvements in image sensor technology play an important role in raising consumer expectations related to image quality. However, reducing the size of the imaging lens while achieving good optical characteristics presents challenging problems. For example, in a typical optical imaging lens system having six lens elements, the distance from the object side surface of the first lens element to the image plane along the optical axis is too large to accommodate the slim profile of today&#39;s cell phones or digital cameras. 
     Decreasing the dimensions of an optical lens while maintaining good optical performance may not only be achieved by scaling down the lens. Rather, these benefits may be realized by improving other aspects of the design process, such as by varying the material used for the lens, or adjusting the assembly yield. 
     In this manner, there is a continuing need for improving the design characteristics of small sized optical lenses. Achieving these advancements may require overcoming unique challenges, even when compared to design improvements for traditional optical lenses. However, refining aspects of the optical lens manufacturing process that result in a lens that meets consumer demand and provides upgrades to imaging quality are always desirable objectives for industries, governments, and academia. 
     SUMMARY 
     The present disclosure provides for an optical imaging lens. By controlling the convex or concave shape of the surfaces of each lens element and the parameters in at least two equations, the length of the optical imaging lens may be shortened while maintaining good optical characteristics and system functionality. 
     In some embodiments, an optical imaging lens may comprise sequentially from an object side to an image side along an optical axis, an aperture stop, a first, second, third, fourth, fifth and sixth lens elements, and a filtering unit. Each of the first, second, third, fourth, fifth and sixth lens elements have varying refracting power in some embodiments. Additionally, some embodiments further comprise an object-side surface facing toward the object side, an image-side surface facing toward the image side, and a central thickness defined along the optical axis. 
     In the specification, parameters used herein may include: 
     
       
         
           
               
               
             
               
                   
               
               
                 Param- 
                   
               
               
                 eter 
                 Definition 
               
               
                   
               
             
            
               
                 T1 
                 The central thickness of the first lens element along the optical 
               
               
                   
                 axis 
               
               
                 G12 
                 The distance between the image-side surface of the first lens 
               
               
                   
                 element and the object-side surface of the second lens element 
               
               
                   
                 along the optical axis/The air gap between the first lens 
               
               
                   
                 element and the second lens element along the optical axis 
               
               
                 T2 
                 The central thickness of the second lens element along the 
               
               
                   
                 optical axis 
               
               
                 G23 
                 The air gap between the second lens element and the third lens 
               
               
                   
                 element along the optical axis 
               
               
                 T3 
                 The central thickness of the third lens element along the optical 
               
               
                   
                 axis 
               
               
                 G34 
                 The air gap between the third lens element and the fourth lens 
               
               
                   
                 element along the optical axis 
               
               
                 T4 
                 The central thickness of the fourth lens element along the 
               
               
                   
                 optical axis 
               
               
                 G45 
                 The air gap between the fourth lens element and the fifth lens 
               
               
                   
                 element along the optical axis 
               
               
                 T5 
                 The central thickness of the fifth lens element along the optical 
               
               
                   
                 axis 
               
               
                 G56 
                 The air gap between the fifth lens element and the sixth lens 
               
               
                   
                 element along the optical axis 
               
               
                 T6 
                 The central thickness of the sixth lens element along the optical 
               
               
                   
                 axis 
               
               
                 G6F 
                 The distance between the image-side surface of the sixth lens 
               
               
                   
                 element and the object-side surface of the filtering unit along 
               
               
                   
                 the optical axis 
               
               
                 TF 
                 The central thickness of the filtering unit along the optical 
               
               
                   
                 axis 
               
               
                 GFP 
                 The distance between the image-side surface of the filtering 
               
               
                   
                 unit and an image plane along the optical axis 
               
               
                 f1 
                 The focusing length of the first lens element 
               
               
                 f2 
                 The focusing length of the second lens element 
               
               
                 f3 
                 The focusing length of the third lens element 
               
               
                 f4 
                 The focusing length of the fourth lens element 
               
               
                 f5 
                 The focusing length of the fifth lens element 
               
               
                 f6 
                 The focusing length of the sixth lens element 
               
               
                 n1 
                 The refracting index of the first lens element 
               
               
                 n2 
                 The refracting index of the second lens element 
               
               
                 n3 
                 The refracting index of the third lens element 
               
               
                 n4 
                 The refracting index of the fourth lens element 
               
               
                 n5 
                 The refracting index of the fifth lens element 
               
               
                 n6 
                 The refracting index of the sixth lens element 
               
               
                 v1 
                 The Abbe number of the first lens element 
               
               
                 v2 
                 The Abbe number of the second lens element 
               
               
                 v3 
                 The Abbe number of the third lens element 
               
               
                 v4 
                 The Abbe number of the fourth lens element 
               
               
                 v5 
                 The Abbe number of the fifth lens element 
               
               
                 v6 
                 The Abbe number of the sixth lens element 
               
               
                 HFOV 
                 Half Field of View of the optical imaging lens 
               
               
                 Fno 
                 F-number of the optical imaging lens 
               
               
                 EFL 
                 The effective focal length of the optical imaging lens 
               
               
                 TTL 
                 The distance between the object-side surface of the first lens 
               
               
                   
                 element and an image plane along the optical axis/The length 
               
               
                   
                 of the optical image lens 
               
               
                 ALT 
                 The sum of the central thicknesses of all lens elements 
               
               
                 Gaa 
                 The sum of all air gaps between all lens elements along the 
               
               
                   
                 optical axis 
               
               
                 BFL 
                 The back focal length of the optical imaging lens/The distance 
               
               
                   
                 from the image-side surface of the last lens element to the 
               
               
                   
                 image plane along the optical axis 
               
               
                 TL 
                 The distance from the object-side surface of the first lens 
               
               
                   
                 element to the image-side surface of the lens element adjacent 
               
               
                   
                 to the image plane along the optical axis 
               
               
                 Gmax 
                 The maximum value of the air gaps between two adjacent lens 
               
               
                   
                 elements of the first lens element to the sixth lens element 
               
               
                   
               
            
           
         
       
     
     According to some embodiments of the optical imaging lens of the present disclosure, the image-side surface of the first lens element may comprise a concave portion in a vicinity of a periphery of the first lens element; the image-side surface of the second lens element may comprise a concave portion in a vicinity of a periphery of the second lens element; the material of the third lens element may be plastic; the material of the fourth lens element may be plastic; the material of the fifth lens element may be plastic; the material of the sixth lens element may be plastic; and the optical imaging lens may comprise no other lenses having refracting power beyond the six lens elements. 
     In another exemplary embodiment, other equation(s), such as those relating to the ratio among parameters could be taken into consideration. For example, EFL and TTL could be controlled to satisfy the equation as follows:
 
1≦EFL/TTL  Equation (1); and
 
TTL could be controlled to satisfy the equation as follows:
 
TTL≦18 mm  Equation (2).
 
     Alternatively, other parameters could be taken into consideration. For example: T4 and T6 could be controlled to satisfy the equation as follows:
 
 T 4/ T 6≦1.8  Equation (3);
 
BFL and T3 could be controlled to satisfy the equation as follows:
 
BFL/ T 3≦2.8  Equation (4);
 
BFL and T6 could be controlled to satisfy the equation as follows:
 
BFL/ T 6≦2.8  Equation (5);
 
TTL and T3 could be controlled to satisfy the equation as follows:
 
TTL/ T 3≦17.9  Equation (6);
 
G34 and T4 could be controlled to satisfy the equation as follows:
 
 T 4/ G 34≦1.4  Equation (7);
 
T5 and G34 could be controlled to satisfy the equation as follows:
 
 T 5/ G 34≦1.8  Equation (8);
 
ALT and T6 could be controlled to satisfy the equation as follows:
 
ALT/ T 6≦9.3  Equation (9);
 
TTL and T6 could be controlled to satisfy the equation as follows:
 
TTL/ T 6≦17.9  Equation (10);
 
Gaa and T3 could be controlled to satisfy the equation as follows:
 
Gaa/ T 3≦5.8  Equation (11);
 
T1 and T3 could be controlled to satisfy the equation as follows:
 
 T 1/ T 3≦2.4  Equation (12);
 
Gaa and T6 could be controlled to satisfy the equation as follows:
 
Gaa/ T 6≦5.8  Equation (13);
 
T1 and T6 could be controlled to satisfy the equation as follows:
 
 T 1/ T 6≦2.4  Equation (14);
 
BFL and G34 could be controlled to satisfy the equation as follows:
 
BFL/ G 34≦2.2  Equation (15);
 
ALT and G34 could be controlled to satisfy the equation as follows:
 
ALT/ G 34≦7.3  Equation (16);
 
TTL and G34 could be controlled to satisfy the equation as follows:
 
TTL/ G 34≦13.9  Equation (17);
 
Gaa and G34 could be controlled to satisfy the equation as follows:
 
Gaa/ G 34≦4.5  Equation (18);
 
ALT and T3 could be controlled to satisfy the equation as follows:
 
ALT/ T 3≦5.7  Equation (19);
 
ALT and T1 could be controlled to satisfy the equation as follows:
 
ALT/ T 1≦3.7  Equation (20); or
 
TTL and T1 could be controlled to satisfy the equation as follows:
 
TTL/ T 1≦7.3  Equation (21).
 
     The aforesaid parameters and equations are not limited to particular embodiments, and could be selectively incorporated in other embodiments described herein. In some embodiments, more details about the convex or concave surface structure could be incorporated for one specific lens element or broadly for plural lens elements to enhance the control for the system performance and/or resolution. It is further noted that the details listed herein could be incorporated into other example embodiments if no inconsistency occurs. 
     By controlling the convex or concave shape of the surfaces, exemplary embodiments of the optical imaging lens systems herein achieve good optical characteristics, provide an enlarged aperture, reduce the field of view, increase assembly yield, and effectively shorten the length of the optical imaging lens. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments will be more readily understood from the following detailed description when read in conjunction with the appended drawing, in which: 
         FIG. 1  depicts a cross-sectional view of one single lens element according to the present disclosure; 
         FIG. 2  depicts a schematic view of the relation between the surface shape and the optical focus of the lens element; 
         FIG. 3  depicts a schematic view of a first example of the surface shape and the efficient radius of the lens element; 
         FIG. 4  depicts a schematic view of a second example of the surface shape and the efficient radius of the lens element; 
         FIG. 5  depicts a schematic view of a third example of the surface shape and the efficient radius of the lens element; 
         FIG. 6  depicts a cross-sectional view of a first embodiment of an optical imaging lens having six lens elements according to the present disclosure; 
         FIG. 7  depicts a chart of longitudinal spherical aberration and other kinds of optical aberrations of a first embodiment of the optical imaging lens according to the present disclosure; 
         FIG. 8  depicts a table of optical data for each lens element of the optical imaging lens of a first embodiment of the present disclosure; 
         FIG. 9  depicts a table of aspherical data of a first embodiment of the optical imaging lens according to the present disclosure; 
         FIG. 10  depicts a cross-sectional view of a second embodiment of an optical imaging lens having six lens elements according to the present disclosure; 
         FIG. 11  depicts a chart of longitudinal spherical aberration and other kinds of optical aberrations of a second embodiment of the optical imaging lens according the present disclosure; 
         FIG. 12  depicts a table of optical data for each lens element of the optical imaging lens of a second embodiment of the present disclosure; 
         FIG. 13  depicts a table of aspherical data of a second embodiment of the optical imaging lens according to the present disclosure; 
         FIG. 14  depicts a cross-sectional view of a third embodiment of an optical imaging lens having six lens elements according to the present disclosure; 
         FIG. 15  depicts a chart of longitudinal spherical aberration and other kinds of optical aberrations of a third embodiment of the optical imaging lens according the present disclosure; 
         FIG. 16  depicts a table of optical data for each lens element of the optical imaging lens of a third embodiment of the present disclosure; 
         FIG. 17  depicts a table of aspherical data of a third embodiment of the optical imaging lens according to the present disclosure; 
         FIG. 18  depicts a cross-sectional view of a fourth embodiment of an optical imaging lens having six lens elements according to the present disclosure; 
         FIG. 19  depicts a chart of longitudinal spherical aberration and other kinds of optical aberrations of a fourth embodiment of the optical imaging lens according the present disclosure; 
         FIG. 20  depicts a table of optical data for each lens element of the optical imaging lens of a fourth embodiment of the present disclosure; 
         FIG. 21  depicts a table of aspherical data of a fourth embodiment of the optical imaging lens according to the present disclosure; 
         FIG. 22  depicts a cross-sectional view of a fifth embodiment of an optical imaging lens having six lens elements according to the present disclosure; 
         FIG. 23  depicts a chart of longitudinal spherical aberration and other kinds of optical aberrations of a fifth embodiment of the optical imaging lens according the present disclosure; 
         FIG. 24  depicts a table of optical data for each lens element of the optical imaging lens of a fifth embodiment of the present disclosure; 
         FIG. 25  depicts a table of aspherical data of a fifth embodiment of the optical imaging lens according to the present disclosure; 
         FIG. 26  depicts a cross-sectional view of a sixth embodiment of an optical imaging lens having six lens elements according to the present disclosure; 
         FIG. 27  depicts a chart of longitudinal spherical aberration and other kinds of optical aberrations of a sixth embodiment of the optical imaging lens according to the present disclosure; 
         FIG. 28  depicts a table of optical data for each lens element of a sixth embodiment of an optical imaging lens according to the present disclosure; 
         FIG. 29  depicts a table of aspherical data of a sixth embodiment of the optical imaging lens according to the present disclosure; 
         FIG. 30  depicts a cross-sectional view of a seventh embodiment of an optical imaging lens having six lens elements according to the present disclosure; 
         FIG. 31  depicts a chart of longitudinal spherical aberration and other kinds of optical aberrations of a seventh embodiment of the optical imaging lens according to the present disclosure; 
         FIG. 32  depicts a table of optical data for each lens element of the optical imaging lens of a seventh embodiment of the present disclosure; 
         FIG. 33  depicts a table of aspherical data of a seventh embodiment of the optical imaging lens according to the present disclosure; 
         FIG. 34  depicts a cross-sectional view of an eighth embodiment of an optical imaging lens having six lens elements according to the present disclosure; 
         FIG. 35  depicts a chart of longitudinal spherical aberration and other kinds of optical aberrations of an eighth embodiment of the optical imaging lens according to the present disclosure; 
         FIG. 36  depicts a table of optical data for each lens element of the optical imaging lens of an eighth embodiment of the present disclosure; 
         FIG. 37  depicts a table of aspherical data of an eighth embodiment of the optical imaging lens according to the present disclosure; 
         FIG. 38  depicts a cross-sectional view of a ninth embodiment of an optical imaging lens having six lens elements according to the present disclosure; 
         FIG. 39  depicts a chart of longitudinal spherical aberration and other kinds of optical aberrations of a ninth embodiment of the optical imaging lens according to the present disclosure; 
         FIG. 40  depicts a table of optical data for each lens element of the optical imaging lens of a ninth embodiment of the present disclosure; 
         FIG. 41  depicts a table of aspherical data of a ninth embodiment of the optical imaging lens according to the present disclosure; 
         FIG. 42  depicts a cross-sectional view of a tenth embodiment of an optical imaging lens having six lens elements according to the present disclosure; 
         FIG. 43  depicts a chart of longitudinal spherical aberration and other kinds of optical aberrations of a tenth embodiment of the optical imaging lens according to the present disclosure; 
         FIG. 44  depicts a table of optical data for each lens element of the optical imaging lens of a tenth embodiment of the present disclosure; 
         FIG. 45  depicts a table of aspherical data of a tenth embodiment of the optical imaging lens according to the present disclosure; 
         FIG. 46  depicts a cross-sectional view of an eleventh embodiment of an optical imaging lens having six lens elements according to the present disclosure; 
         FIG. 47  depicts a chart of longitudinal spherical aberration and other kinds of optical aberrations of an eleventh embodiment of the optical imaging lens according to the present disclosure; 
         FIG. 48  depicts a table of optical data for each lens element of the optical imaging lens of an eleventh embodiment of the present disclosure; 
         FIG. 49  depicts a table of aspherical data of an eleventh embodiment of the optical imaging lens according to the present disclosure; 
         FIG. 50  is a table for the values of BFL, Gaa, ALT, EFL/TTL, T4/T6, BFL/T3, BFL/T6, TTL/T3, T4/G34, T5/G34, ALT/T6, TTL/T6, Gaa/T3, T1/T3, Gaa/T6, T1/T6, BFL/G34, ALT/G34, TTL/G34, Gaa/G34, ALT/T3, ALT/T1 and TTL/T1 of the first to eleventh example embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     For a more complete understanding of the present disclosure and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, in which like reference numbers indicate like features. Persons having ordinary skill in the art will understand other varieties for implementing example embodiments, including those described herein. The drawings are not limited to specific scale and similar reference numbers are used for representing similar elements. As used in the disclosures and the appended claims, the terms “example embodiment,” “exemplary embodiment,” and “present embodiment” do not necessarily refer to a single embodiment, although it may, and various example embodiments may be readily combined and interchanged, without departing from the scope or spirit of the present disclosure. Furthermore, the terminology as used herein is for the purpose of describing example embodiments only and is not intended to be a limitation of the disclosure. In this respect, as used herein, the term “in” may include “in” and “on”, and the terms “a”, “an” and “the” may include singular and plural references. Furthermore, as used herein, the term “by” may also mean “from”, depending on the context. Furthermore, as used herein, the term “if” may also mean “when” or “upon”, depending on the context. Furthermore, as used herein, the words “and/or” may refer to and encompass any and all possible combinations of one or more of the associated listed items. 
     In the present specification, the description “a lens element having positive refracting power (or negative refractive power)” means that the paraxial refractive power of the lens element in Gaussian optics is positive (or negative). The description “An object-side (or image-side) surface of a lens element” may include a specific region of that surface of the lens element where imaging rays are capable of passing through that region, namely the clear aperture of the surface. The aforementioned imaging rays can be classified into two types, chief ray Lc and marginal ray Lm. Taking a lens element depicted in  FIG. 1  as an example, the lens element may be rotationally symmetric, where the optical axis I is the axis of symmetry. The region A of the lens element is defined as “a part in a vicinity of the optical axis”, and the region C of the lens element is defined as “a part in a vicinity of a periphery of the lens element”. Besides, the lens element may also have an extending part E extended radially and outwardly from the region C, namely the part outside of the clear aperture of the lens element. The extending part E may be used for physically assembling the lens element into an optical imaging lens system. Under normal circumstances, the imaging rays would not pass through the extending part E because those imaging rays only pass through the clear aperture. The structures and shapes of the aforementioned extending part E are only examples for technical explanation, the structures and shapes of lens elements should not be limited to these examples. Note that the extending parts of the lens element surfaces depicted in the following embodiments are partially omitted. 
     The following criteria are provided for determining the shapes and the parts of lens element surfaces set forth in the present specification. These criteria mainly determine the boundaries of parts under various circumstances including the part in a vicinity of the optical axis, the part in a vicinity of a periphery of a lens element surface, and other types of lens element surfaces such as those having multiple parts. 
       FIG. 1  depicts a radial cross-sectional view of a lens element. Before determining boundaries of those aforesaid parts, two referential points should be defined first, the central point and the transition point. The central point of a surface of a lens element is a point of intersection of that surface and the optical axis. The transition point is a point on a surface of a lens element, where the tangent line of that point is perpendicular to the optical axis. Additionally, if multiple transition points appear on one single surface, then these transition points are sequentially named along the radial direction of the surface with numbers starting from the first transition point. For instance, the first transition point (closest one to the optical axis), the second transition point, and the Nth transition point (farthest one to the optical axis within the scope of the clear aperture of the surface). The part of a surface of the lens element between the central point and the first transition point is defined as the part in a vicinity of the optical axis. The part located radially outside of the Nth transition point (but still within the scope of the clear aperture) is defined as the part in a vicinity of a periphery of the lens element. In some embodiments, there are other parts existing between the part in a vicinity of the optical axis and the part in a vicinity of a periphery of the lens element; the numbers of parts depend on the numbers of the transition point(s). In addition, the radius of the clear aperture (or a so-called effective radius) of a surface is defined as the radial distance from the optical axis I to a point of intersection of the marginal ray Lm and the surface of the lens element. 
     Referring to  FIG. 2 , determining the shape of a part is convex or concave depends on whether a collimated ray passing through that part converges or diverges. That is, while applying a collimated ray to a part to be determined in terms of shape, the collimated ray passing through that part will be bended and the ray itself or its extension line will eventually meet the optical axis. The shape of that part can be determined by whether the ray or its extension line meets (intersects) the optical axis (focal point) at the object-side or image-side. For instance, if the ray itself intersects the optical axis at the image side of the lens element after passing through a part, i.e. the focal point of this ray is at the image side (see point R in  FIG. 2 ), the part will be determined as having a convex shape. On the contrary, if the ray diverges after passing through a part, the extension line of the ray intersects the optical axis at the object side of the lens element, i.e. the focal point of the ray is at the object side (see point M in  FIG. 2 ), that part will be determined as having a concave shape. Therefore, referring to  FIG. 2 , the part between the central point and the first transition point may have a convex shape, the part located radially outside of the first transition point may have a concave shape, and the first transition point is the point where the part having a convex shape changes to the part having a concave shape, namely the border of two adjacent parts. Alternatively, there is another method to determine whether a part in a vicinity of the optical axis may have a convex or concave shape by referring to the sign of an “R” value, which is the (paraxial) radius of curvature of a lens surface. The R value may be used in conventional optical design software such as Zemax and CodeV. The R value usually appears in the lens data sheet in the software. For an object-side surface, positive R means that the object-side surface is convex, and negative R means that the object-side surface is concave. Conversely, for an image-side surface, positive R means that the image-side surface is concave, and negative R means that the image-side surface is convex. The result found by using this method should be consistent as by using the other way mentioned above, which determines surface shapes by referring to whether the focal point of a collimated ray is at the object side or the image side. 
     For none transition point cases, the part in a vicinity of the optical axis may be defined as the part between 0-50% of the effective radius (radius of the clear aperture) of the surface, whereas the part in a vicinity of a periphery of the lens element may be defined as the part between 50-100% of effective radius (radius of the clear aperture) of the surface. 
     Referring to the first example depicted in  FIG. 3 , only one transition point, namely a first transition point, appears within the clear aperture of the image-side surface of the lens element. Part I may be a part in a vicinity of the optical axis, and part II may be a part in a vicinity of a periphery of the lens element. The part in a vicinity of the optical axis may be determined as having a concave surface due to the R value at the image-side surface of the lens element is positive. The shape of the part in a vicinity of a periphery of the lens element may be different from that of the radially inner adjacent part, i.e. the shape of the part in a vicinity of a periphery of the lens element may be different from the shape of the part in a vicinity of the optical axis; the part in a vicinity of a periphery of the lens element may have a convex shape. 
     Referring to the second example depicted in  FIG. 4 , a first transition point and a second transition point may exist on the object-side surface (within the clear aperture) of a lens element. In which part I may be the part in a vicinity of the optical axis, and part III may be the part in a vicinity of a periphery of the lens element. The part in a vicinity of the optical axis may have a convex shape because the R value at the object-side surface of the lens element may be positive. The part in a vicinity of a periphery of the lens element (part III) may have a convex shape. What is more, there may be another part having a concave shape existing between the first and second transition point (part II). 
     Referring to a third example depicted in  FIG. 5 , no transition point may exist on the object-side surface of the lens element. In this case, the part between 0-50% of the effective radius (radius of the clear aperture) may be determined as the part in a vicinity of the optical axis, and the part between 50-100% of the effective radius may be determined as the part in a vicinity of a periphery of the lens element. The part in a vicinity of the optical axis of the object-side surface of the lens element may be determined as having a convex shape due to its positive R value, and the part in a vicinity of a periphery of the lens element may be determined as having a convex shape as well. 
     In the present disclosure, various examples of optical imaging lenses are provided, including examples in which the optical imaging lens is a prime lens. Example embodiments of optical imaging lenses may comprise, sequentially from an object side to an image side along an optical axis, a first, second, third, fourth, fifth and sixth lens elements and a filter unit, in which each of said lens elements has an object-side surface facing toward the object side and an image-side surface facing toward the image side. The optical imaging lens of the present disclosure achieves good optical characteristics and provides a shortened length due to the design characteristics of each lens element. 
     The optical imaging lens may include variations of any of the above mentioned characteristics, and the system may vary one or more lens elements. In addition, the system may include variations of additional optical features as well as variations of the optical lens length of the optical imaging lens. For example, the first lens element may have positive refracting power, which is favorable to gather light; the object-side surface of the second lens element may comprise a convex portion in a vicinity of a periphery of the second lens element and the object-side surface of the third lens element may comprise a convex portion in a vicinity of a periphery of the third lens element, which is favorable to gather edge image light; the object-side surface of the sixth lens element may comprise a concave portion in a vicinity of a periphery of the sixth lens element and the image-side surface may comprise a convex portion in a vicinity of a periphery of the sixth lens element. The above mentioned designs may effectively eliminate aberrations, reduce the length of the optical lens, and enhance imaging quality and telephoto characteristics, to provide a more clear image of a local portion of the object. 
     In addition, controlling the parameters of each lens element as described herein may beneficially provide a designer with the flexibility to design an optical imaging lens with good optical performance, shortened length, enhanced telephoto characteristics, and technological feasibility. 
     For example, lengthening EFL may reduce the field of view for telephoto characteristics. However, the optical imaging lens used in many cell phones today involves miniaturized dimensions that may affect the lengthening range of the EFL. In view of the above, satisfying any one of the following equations may result in decreasing the thickness of the system. Furthermore, the field of view may be reduced and at least one of the following telephoto characteristics may be satisfied:
 
1≦EFL/TTL  Equation (1).
 
     Furthermore, in some embodiments, the value of EFL/TTL may be further restricted between 1.00 and 1.50. 
     Properly decreasing the thicknesses of the lens elements as well as the air gaps between the lens elements serves to shorten the length of the optical imaging lens and allow for the system to focus more easily, which raises image quality. In this manner, the thicknesses of the lens elements and the air gaps between the lens elements may be adjusted to satisfy any one of equations described below, to result in arrangements that overcome the difficulties of providing improved imaging quality while overcoming the previously described difficulties related to assembling the optical lens system:
 
 T 4/ T 6≦1.8  Equation (3);
 
BFL/ T 3≦2.8  Equation (4);
 
BFL/ T 6≦2.8  Equation (5);
 
 T 4/ G 34≦1.4  Equation (7);
 
 T 5/ G 34≦1.8  Equation (8);
 
ALT/ T 6≦9.3  Equation (9);
 
Gaa/ T 3≦5.8  Equation (11);
 
 T 1/ T 3≦2.4  Equation (12);
 
Gaa/ T 6≦5.8  Equation (13);
 
 T 1/ T 6≦2.4  Equation (14);
 
BFL/ G 34≦2.2  Equation (15);
 
ALT/ G 34≦7.3  Equation (16);
 
Gaa/ G 34≦4.5  Equation (18);
 
ALT/ T 3≦5.7  Equation (19); and
 
ALT/ T 1≦3.7  Equation (20).
 
     When the design of the optical imaging lens could satisfy any one of Equations (3), (4), (5), (7), (8), (9), (11), (12), (13), (14), (15), (16), (18), (19) and (20), and the denominators of theses equations are fixed, the numerators could be reduced to reduce the volume of the optical imaging lens. 
     In some embodiments, the value of T4/T6 may be further restricted between 0.3 and 1.8. In some embodiments, the value of BFL/T3 may be further restricted between 0.70 and 2.8. In some embodiments, the value of BFL/T6 may be further restricted between 1.00 and 2.8. In some embodiments, the value of T4/G34 may be further restricted between 0.10 and 1.4. In some embodiments, the value of T5/G34 may be further restricted between 0.20 and 1.8. In some embodiments, the value of ALT/T6 may be further restricted between 3.4 and 9.3. In some embodiments, the value of Gaa/T3 may be further restricted between 1.7 and 5.8. In some embodiments, the value of T1/T3 may be further restricted between 1.00 and 2.40. In some embodiments, the value of Gaa/T6 may be further restricted between 1.00 and 5.80. In some embodiments, the value of T1/T6 may be further restricted between 0.60 and 2.40. In some embodiments, the value of BFL/G34 may be further restricted between 0.60 and 2.20. In some embodiments, the value of ALT/G34 may be further restricted between 3.20 and 7.30. In some embodiments, the value of Gaa/G34 may be further restricted between 2.20 and 4.50. In some embodiments, the value of ALT/T3 may be further restricted between 3.50 and 5.70. In some embodiments, the value of ALT/T1 may be further restricted between 2.20 and 3.70. 
     In addition, the parameters set forth in the present disclosure could be varied to satisfy any one of equations below, such that the optical imaging lens could be in proper arrangement and have good image quality:
 
TTL/ T 3≦17.9  Equation (6);
 
TTL/ T 6≦17.9  Equation (10);
 
TTL/ G 34≦13.9  Equation (17); and
 
TTL/ T 1≦7.3  Equation (21).
 
     In some embodiments, the value of TTL/T3 may be further restricted between 6.6 and 17.9. In some embodiments, the value of TTL/T6 may be further restricted between 5.4 and 17.9. In some embodiments, the value of TTL/G34 may be further restricted between 6.5 and 13.9. In some embodiments, the value of TTL/T1 may be further restricted between 5.3 and 7.3. 
     Moreover, designing the optical imaging lens to additionally satisfy the equation HFOV≦25°, advantageously improves imaging in applications where uniform light of the image has an impact upon imaging quality. Furthermore, satisfying the HFOV criteria reduces difficulties related to designing and processing the optical image lens. 
     It should be appreciated that numerous variations are possible when considering improvements to the design of an optical system. When the optical imaging lens of the present disclosure satisfies at least one of the equations described above, the length of the optical lens may be reduced, the aperture stop may be enlarged (F-number may be reduced), the field angle may be reduced, the imaging quality may be enhanced, or the assembly yield may be upgraded. Such characteristics may advantageously mitigate various drawbacks in other optical system designs. 
     When implementing example embodiments, more details about the convex or concave surface could be incorporated for one specific lens element or broadly for plural lens elements to enhance the control for the system performance and/or resolution. It is noted that the details listed here could be incorporated in example embodiments if no inconsistency occurs. 
     Several exemplary embodiments and associated optical data will now be provided to illustrate non-limiting examples of optical imaging lens systems having good optical characteristics and a shortened length. Reference is now made to  FIGS. 6-9 .  FIG. 6  illustrates an example cross-sectional view of an optical imaging lens  1  having six lens elements according to a first example embodiment.  FIG. 7  shows example charts of longitudinal spherical aberration and other kinds of optical aberrations of the optical imaging lens  1  according to the first example embodiment.  FIG. 8  illustrates an example table of optical data of each lens element of the optical imaging lens  1  according to the first example embodiment.  FIG. 9  depicts an example table of aspherical data of the optical imaging lens  1  according to the first example embodiment. 
     As shown in  FIG. 6 , the optical imaging lens  1  of the present embodiment may comprise, in order from an object side A 1  to an image side A 2  along an optical axis, an aperture stop  100 , a first lens element  110 , a second lens element  120 , a third lens element  130 , a fourth lens element  140 , a fifth lens element  150  and a sixth lens element  160 . A filtering unit  170  and an image plane  180  of an image sensor (not shown) are positioned at the image side A 2  of the optical imaging lens  1 . Each of the first, second, third, fourth, fifth and sixth lens elements  110 ,  120 ,  130 ,  140 ,  150 ,  160  and the filtering unit  170  may comprise an object-side surface  111 / 121 / 131 / 141 / 151 / 161 / 171  facing toward the object side A 1  and an image-side surface  112 / 122 / 132 / 142 / 152 / 162 / 172  facing toward the image side A 2 . The example embodiment of the filtering unit  170  illustrated is an IR cut filter (infrared cut filter) positioned between the sixth lens element  160  and an image plane  180 . The filtering unit  170  selectively absorbs light passing optical imaging lens  1  that has a specific wavelength. For example, if IR light is absorbed, IR light which is not seen by human eyes is prohibited from producing an image on the image plane  180 . 
     Exemplary embodiments of each lens element of the optical imaging lens  1  will now be described with reference to the drawings. The lens elements of the optical imaging lens  1  are constructed using plastic material, in some embodiments. 
     An example embodiment of the first lens element  110  may have positive refracting power. The object-side surface  111  may comprise a convex portion  1111  in a vicinity of an optical axis and a convex portion  1112  in a vicinity of a periphery of the first lens element  110 . The image-side surface  112  may comprise a concave portion  1121  in a vicinity of the optical axis and a concave portion  1122  in a vicinity of a periphery of the first lens element  110 . The object-side surface  111  and the image-side surface  112  may be aspherical surfaces. 
     An example embodiment of the second lens element  120  may have negative refracting power. The object-side surface  121  may comprise a concave portion  1211  in a vicinity of the optical axis and a convex portion  1212  in a vicinity of a periphery of the second lens element  120 . The image-side surface  122  may comprise a concave portion  1221  in a vicinity of the optical axis and a concave portion  1222  in a vicinity of a periphery of the second lens element  120 . The object-side surface  121  and the image-side surface  122  may be aspherical surfaces. 
     An example embodiment of the third lens element  130  may have positive refracting power. The object-side surface  131  may comprise a convex portion  1311  in a vicinity of the optical axis and a convex portion  1312  in a vicinity of a periphery of the third lens element  130 . The image-side surface  132  may comprise a concave portion  1321  in a vicinity of the optical axis and a concave portion  1322  in a vicinity of a periphery of the third lens element  130 . The object-side surface  131  and the image-side surface  132  may be aspherical surfaces. 
     An example embodiment of the fourth lens element  140  may have positive refracting power. The object-side surface  141  may comprise a convex portion  1411  in a vicinity of the optical axis and a concave portion  1412  in a vicinity of a periphery of the fourth lens element  140 . The image-side surface  142  may comprise a concave portion  1421  in a vicinity of the optical axis and a convex portion  1422  in a vicinity of a periphery of the fourth lens element  140 . The object-side surface  141  and the image-side surface  142  may be aspherical surfaces. 
     An example embodiment of the fifth lens element  150  may have negative refracting power. The object-side surface  151  may comprise a concave portion  1511  in a vicinity of the optical axis and a concave portion  1512  in a vicinity of a periphery of the fifth lens element  150 . The image-side surface  152  may comprise a concave portion  1521  in a vicinity of the optical axis and a convex portion  1522  in a vicinity of a periphery of the fifth lens element  150 . The object-side surface  151  and the image-side surface  152  may be aspherical surfaces. 
     An example embodiment of the sixth lens element  160  may have negative refracting power. The object-side surface  161  may comprise a concave portion  1611  in a vicinity of the optical axis and a concave portion  1612  in a vicinity of a periphery of the sixth lens element  160 . The image-side surface  162  may comprise a concave portion  1621  in a vicinity of the optical axis and a convex portion  1622  in a vicinity of a periphery of the sixth lens element  160 . The object-side surface  161  and the image-side surface  162  may be aspherical surfaces. 
     In example embodiments, air gaps exist between the lens elements  110 ,  120 ,  130 ,  140 ,  150 , the filtering unit  170  and the image plane  180  of the image sensor. For example,  FIG. 6  illustrates the air gap d 1  existing between the first lens element  110  and the second lens element  120 , the air gap d 2  existing between the second lens element  120  and the third lens element  130 , the air gap d 3  existing between the third lens element  130  and the fourth lens element  140 , the air gap d 4  existing between the fourth lens element  140  and the fifth lens element  150 , the air gap d 5  existing between the fifth lens element  150  and the sixth lens element  160 , the air gap d 6  existing between the sixth lens element  160  and the filtering unit  170 , and the air gap d 7  existing between the filtering unit  170  and the image plane  180  of the image sensor. However, in other embodiments, any of the aforesaid air gaps may or may not exist. For example, the profiles of opposite surfaces of any two adjacent lens elements may correspond to each other, and in such situation, the air gap may not exist. The air gap d 1  is denoted by G12, the air gap d 2  is denoted by G23, the air gap d 3  is denoted by G34, the air gap d 4  is denoted by G45, the air gap d 5  is denoted by G56, the air gap d 6  is denoted by G6F, the air gap d 7  is denoted by GFP, and the sum of d 1 , d 2 , d 3 , d 4  and d 5  is denoted by Gaa. 
       FIG. 8  depicts the optical characteristics of each lens elements in the optical imaging lens  1  of the present embodiment. The aspherical surfaces including the object-side surface  111  of the first lens element  110 , the image-side surface  112  of the first lens element  110 , the object-side surface  121  and the image-side surface  122  of the second lens element  120 , the object-side surface  131  and the image-side surface  132  of the third lens element  130 , the object-side surface  141  and the image-side surface  142  of the fourth lens element  140 , the object-side surface  151  and the image-side surface  152  of the fifth lens element  150 , the object-side surface  161  and the image-side surface  162  of the sixth lens element  160  are all defined by the following aspherical formula (1): 
     
       
         
           
             
               
                 
                   
                     Z 
                     ⁡ 
                     
                       ( 
                       Y 
                       ) 
                     
                   
                   = 
                   
                     
                       
                         
                           Y 
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                         R 
                       
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                         ( 
                         
                           1 
                           + 
                           
                             
                               1 
                               - 
                               
                                 
                                   ( 
                                   
                                     1 
                                     + 
                                     K 
                                   
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                                 ⁢ 
                                 
                                   
                                     Y 
                                     2 
                                   
                                   
                                     R 
                                     2 
                                   
                                 
                               
                             
                           
                         
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                     + 
                     
                       
                         ∑ 
                         
                           i 
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                           1 
                         
                         n 
                       
                       ⁢ 
                       
                         
                           a 
                           
                             2 
                             ⁢ 
                             i 
                           
                         
                         × 
                         
                           Y 
                           
                             2 
                             ⁢ 
                             
                                 
                             
                             ⁢ 
                             i 
                           
                         
                       
                     
                   
                 
               
               
                 
                   formula 
                   ⁢ 
                   
                       
                   
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     wherein, 
     R represents the radius of curvature of the surface of the lens element; 
     Z represents the depth of the aspherical surface (the perpendicular distance between the point of the aspherical surface at a distance Y from the optical axis and the tangent plane of the vertex on the optical axis of the aspherical surface); 
     Y represents the perpendicular distance between the point of the aspherical surface and the optical axis; 
     K represents a conic constant;
         a 2i  represents an aspherical coefficient of 2i th  level.       

     The values of each aspherical parameter are shown in  FIG. 9 . 
       FIG. 7  part a shows the longitudinal spherical aberration, wherein the horizontal axis of  FIG. 7  part a defines the focus, and the vertical axis of  FIG. 7  part a defines the field of view.  FIG. 7  part b shows the astigmatism aberration in the sagittal direction, wherein the horizontal axis of  FIG. 7  part b defines the focus, and the vertical axis of  FIG. 7  part b defines the image height.  FIG. 7  part c shows the astigmatism aberration in the tangential direction, wherein the horizontal axis of  FIG. 7  part c defines the focus, and the vertical axis of  FIG. 7  part c defines the image height.  FIG. 7  part d shows the variation of the distortion aberration, wherein the horizontal axis of  FIG. 7  part d defines the percentage, and the vertical axis of  FIG. 7  part d defines the image height. The three curves with different wavelengths (470 nm, 555 nm, 650 nm) represent that off-axis light with respect to these wavelengths may be focused around an image point. From the vertical deviation of each curve shown in  FIG. 7  part a, the offset of the off-axis light relative to the image point may be within about ±0.05 mm. Therefore, the first embodiment may improve the longitudinal spherical aberration with respect to different wavelengths. Referring to  FIG. 7  part b, the focus variation with respect to the three different wavelengths (470 nm, 555 nm, 650 nm) in the whole field may fall within about ±0.16 mm. Referring to  FIG. 7  part c, the focus variation with respect to the three different wavelengths (470 nm, 555 nm, 650 nm) in the whole field may fall within about ±0.20 mm. Referring to  FIG. 7  part d, the horizontal axis of  FIG. 7  part d, the variation of the distortion aberration may be within about ±0.25%. 
     Please refer to  FIG. 50  for the values of BFL, Gaa, ALT, EFL/TTL, T4/T6, BFL/T3, BFL/T6, TTL/T3, T4/G34, T5/G34, ALT/T6, TTL/T6, Gaa/T3, T1/T3, Gaa/T6, T1/T6, BFL/G34, ALT/G34, TTL/G34, Gaa/G34, ALT/T3, ALT/T1 and TTL/T1 of the present embodiment. 
     The distance from the object-side surface  111  of the first lens element  110  to the image plane  180  along the optical axis may be about 5.357 mm. In accordance with these values, the present embodiment may provide an optical imaging lens having a shortened length, and may be capable of accommodating a slim product profile that also renders improved optical performance. 
     Reference is now made to  FIGS. 10-13 .  FIG. 10  illustrates an example cross-sectional view of an optical imaging lens  2  having six lens elements according to a second example embodiment.  FIG. 11  shows example charts of longitudinal spherical aberration and other kinds of optical aberrations of the optical imaging lens  2  according to the second example embodiment.  FIG. 12  shows an example table of optical data of each lens element of the optical imaging lens  2  according to the second example embodiment.  FIG. 13  shows an example table of aspherical data of the optical imaging lens  2  according to the second example embodiment. The reference numbers labeled in the present embodiment are similar to those in the first embodiment for the similar elements, but here the reference numbers are initialed with 2, for example, reference number  231  for labeling the object-side surface of the third lens element  230 , reference number  232  for labeling the image-side surface of the third lens element  230 , etc. 
     As shown in  FIG. 10 , the optical imaging lens  2  of the present embodiment, in an order from an object side A 1  to an image side A 2  along an optical axis, may comprise an aperture stop  200 , a first lens element  210 , a second lens element  220 , a third lens element  230 , a fourth lens element  240 , a fifth lens element  250  and a sixth lens element  260 . 
     The arrangement of the convex or concave surface structures, including the object-side surfaces  211 ,  231 ,  241 ,  251 , and  261  and the image-side surfaces  212  and  222  are generally similar with the optical imaging lens  1 . The differences between the optical imaging lens  1  and the optical imaging lens  2  may include the concave/convex shapes of at least one of the following: the object-side surface  221  and the image-side surfaces  232 ,  242 ,  252 ,  262 . Additional differences may include the refracting power, a radius of curvature, a thickness, an aspherical data, and an effective focal length of each lens element. More specifically, the object-side surface  221  may comprise a convex portion  2211  in a vicinity of the optical axis, the image-side surface  232  may comprise a convex portion  2322  in a vicinity of a periphery of the third lens element  230 , the image-side surface  242  may comprise a concave portion  2422  in a vicinity of a periphery of the fourth lens element  240 , the image-side surface  252  may comprise a convex portion  2521  in a vicinity of the optical axis, the image-side surface  262  may comprise a convex portion  2621  in a vicinity of the optical axis, the fourth lens element  240  may have negative refracting power, and the fifth lens element  250  may have positive refracting power. 
     Here, for clearly showing the drawings of the present embodiment, only the surface shapes which are different from that in the first embodiment are labeled. Please refer to  FIG. 12  for the optical characteristics of each lens element in the optical imaging lens  2  of the present embodiment. 
     From the vertical deviation of each curve shown in  FIG. 11  part a, the offset of the off-axis light relative to the image point may be within about ±0.01 mm. Referring to  FIG. 11  part b, the focus variation with respect to the three different wavelengths (470 nm, 555 nm, 650 nm) in the whole field may fall within about ±0.20 μm. Referring to  FIG. 11  part c, the focus variation with respect to the three different wavelengths (470 nm, 555 nm, 650 nm) in the whole field may fall within about ±0.20 μm. Referring to  FIG. 11  part d, the variation of the distortion aberration of the optical imaging lens  2  may be within about ±0.7%. 
     Please refer to  FIG. 50  for the values of BFL, Gaa, ALT, EFL/TTL, T4/T6, BFL/T3, BFL/T6, TTL/T3, T4/G34, T5/G34, ALT/T6, TTL/T6, Gaa/T3, T1/T3, Gaa/T6, T1/T6, BFL/G34, ALT/G34, TTL/G34, Gaa/G34, ALT/T3, ALT/T1 and TTL/T1 of the present embodiment. 
     In comparison with the first embodiment, the second embodiment may include decreased values related to at least one of the following: longitudinal spherical aberration, astigmatism aberration in the sagittal and tangential directions, and HFOV. Further, the second embodiment may be manufactured more easily and the yield rate may be higher when compared to the first embodiment. 
     Reference is now made to  FIGS. 14-17 .  FIG. 14  illustrates an example cross-sectional view of an optical imaging lens  3  having six lens elements according to a third example embodiment.  FIG. 15  shows example charts of longitudinal spherical aberration and other kinds of optical aberrations of the optical imaging lens  3  according to the third example embodiment.  FIG. 16  shows an example table of optical data of each lens element of the optical imaging lens  3  according to the third example embodiment.  FIG. 17  shows an example table of aspherical data of the optical imaging lens  3  according to the third example embodiment. The reference numbers labeled in the present embodiment are similar to those in the first embodiment for the similar elements, but here the reference numbers are initialed with 3, for example, reference number  331  for labeling the object-side surface of the third lens element  330 , reference number  332  for labeling the image-side surface of the third lens element  330 , etc. 
     As shown in  FIG. 14 , the optical imaging lens  3  of the present embodiment, in an order from an object side A 1  to an image side A 2  along an optical axis, may comprise an aperture stop  300 , a first lens element  310 , a second lens element  320 , a third lens element  330 , a fourth lens element  340 , a fifth lens element  350  and a sixth lens element  360 . 
     The arrangement of the convex or concave surface structures, including the object-side surfaces  311  and  331  and the image-side surfaces  312 ,  322 , and  352  are generally similar with the optical imaging lens  1 . The differences between the optical imaging lens  1  and the optical imaging lens  3  may include the concave/convex shapes of at least one of the following: the object-side surfaces  321 ,  341 ,  351 , and  361 , and the image-side surface  332 ,  342 , and  362 . Additional differences may include the refracting power, a radius of curvature, a thickness, an aspherical data, and an effective focal length of each lens element. More specifically, the object-side surface  321  may comprise a convex portion  3211  in a vicinity of the optical axis, the image-side surface  332  may comprise a convex portion  3322  in a vicinity of a periphery of the third lens element  330 , the object-side surface  341  may comprise a concave portion  3411  in a vicinity of the optical axis, the image-side surface  342  may comprise a convex portion  3421  in a vicinity of the optical axis and a concave portion  3422  in a vicinity of a periphery of the fourth lens element  340 , the object-side surface  351  may comprise a convex portion  3511  in a vicinity of the optical axis, the object-side surface  361  may comprise a convex portion  3611  in a vicinity of the optical axis, the image-side surface  362  may comprises a convex portion  3621  in a vicinity of the optical axis, the fourth lens element  340  may have negative refracting power, and the sixth lens element  360  may comprise positive refracting power. 
     Here, for clearly showing the drawings of the present embodiment, only the surface shapes which are different from that in the first embodiment are labeled. Please refer to  FIG. 16  for the optical characteristics of each lens element in the optical imaging lens  3  of the present embodiment. 
     From the vertical deviation of each curve shown in  FIG. 15  part a, the offset of the off-axis light relative to the image point may be within about ±0.03 mm. Referring to  FIG. 15  part b, the focus variation with respect to the three different wavelengths (470 nm, 555 nm, 650 nm) in the whole field may fall within about ±0.04 mm. Referring to  FIG. 15  part c, the focus variation with respect to the three different wavelengths (470 nm, 555 nm, 650 nm) in the whole field may fall within about ±0.08 mm. Refer to  FIG. 15  part d, the variation of the distortion aberration of the optical imaging lens  3  may be within about ±1.2%. 
     Please refer to  FIG. 50  for the values of BFL, Gaa, ALT, EFL/TTL, T4/T6, BFL/T3, BFL/T6, TTL/T3, T4/G34, T5/G34, ALT/T6, TTL/T6, Gaa/T3, T1/T3, Gaa/T6, T1/T6, BFL/G34, ALT/G34, TTL/G34, Gaa/G34, ALT/T3, ALT/T1 and TTL/T1 of the present embodiment. 
     In comparison with the first embodiment, the third embodiment may include decreased values related to at least one of the following: longitudinal spherical aberration, astigmatism aberration in the sagittal and tangential directions, and HFOV. Also, the third embodiment may further feature improved image quality in comparison with the first embodiment. Moreover, the third embodiment may be manufactured more easily and its yield rate may be higher when compared to the first embodiment. 
     Reference is now made to  FIGS. 18-21 .  FIG. 18  illustrates an example cross-sectional view of an optical imaging lens  4  having six lens elements according to a fourth example embodiment.  FIG. 19  shows example charts of longitudinal spherical aberration and other kinds of optical aberrations of the optical imaging lens  4  according to the fourth embodiment.  FIG. 20  shows an example table of optical data of each lens element of the optical imaging lens  4  according to the fourth example embodiment.  FIG. 21  shows an example table of aspherical data of the optical imaging lens  4  according to the fourth example embodiment. The reference numbers labeled in the present embodiment are similar to those in the first embodiment for the similar elements, but here the reference numbers are initialed with 4, for example, reference number  431  for labeling the object-side surface of the third lens element  430 , reference number  432  for labeling the image-side surface of the third lens element  430 , etc. 
     As shown in  FIG. 18 , the optical imaging lens  4  of the present embodiment, in an order from an object side A 1  to an image side A 2  along an optical axis, may comprise an aperture stop  400 , a first lens element  410 , a second lens element  420 , a third lens element  430 , a fourth lens element  440 , a fifth lens element  450  and a sixth lens element  460 . 
     The arrangement of the convex or concave surface structures, including the object-side surfaces  411 ,  431 ,  441 , and  461  and the image-side surfaces  412 ,  422 ,  442 ,  452 , and  462  are generally similar to the optical imaging lens  1 . The differences between the optical imaging lens  1  and the optical imaging lens  4  may include the concave/convex shapes of at least one of the following: the object-side surfaces  421  and  441 , and the image-side surfaces  432 ,  442 ,  452 , and  462 . Additional differences may include the refracting power, a radius of curvature, a thickness, an aspherical data, and an effective focal length of each lens element. More specifically, the object-side surface  421  may comprise a convex portion  4211  in a vicinity of the optical axis, the image-side surface  432  may comprise a convex portion  4322  in a vicinity of a periphery of the third lens element  430 , the object-side surface  441  may comprise a concave portion  4411  in a vicinity of the optical axis, the image-side surface  442  may comprise a concave portion  4422  in a vicinity of a periphery of the fourth lens element  440 , the image-side surface  452  may comprise a convex portion  4521  in a vicinity of the optical axis, the image-side surface  462  may comprise a convex portion  4621  in a vicinity of the optical axis, the fourth lens element  440  may have negative refracting power, and the fifth lens element  450  may have positive refracting power. 
     Here, for clearly showing the drawings of the present embodiment, only the surface shapes which are different from that in the first embodiment are labeled. Please refer to  FIG. 20  for the optical characteristics of each lens elements in the optical imaging lens  4  of the present embodiment. 
     From the vertical deviation of each curve shown in  FIG. 19  part a, the offset of the off-axis light relative to the image point may be within about ±0.02 mm. Referring to  FIG. 19  part b, the focus variation with respect to the three different wavelengths (470 nm, 555 nm, 650 nm) in the whole field may fall within about ±0.03 mm. Referring to  FIG. 19  part c, the focus variation with respect to the three different wavelengths (470 nm, 555 nm, 650 nm) in the whole field may fall within about ±0.06 mm. Referring to  FIG. 19  part d, the variation of the distortion aberration of the optical imaging lens  4  may be within about ±1.4%. 
     Please refer to  FIG. 50  for the values of BFL, Gaa, ALT, EFL/TTL, T4/T6, BFL/T3, BFL/T6, TTL/T3, T4/G34, T5/G34, ALT/T6, TTL/T6, Gaa/T3, T1/T3, Gaa/T6, T1/T6, BFL/G34, ALT/G34, TTL/G34, Gaa/G34, ALT/T3, ALT/T1 and TTL/T1 of the present embodiment. 
     Additionally, the distance from the object-side surface  411  of the first lens element  410  to the image plane  480  along the optical axis may be about 5.908 mm, EFL may be about 6.141 mm, the image height may be about 2.619 mm, HFOV may be about 22.896 degrees, and Fno may be about 2.29. 
     In comparison to the first embodiment, the fourth embodiment may include decreased values related to at least one of the following: longitudinal spherical aberration, astigmatism aberration in the sagittal and tangential directions, and HFOV. Also, the fourth embodiment may further feature improved image quality in comparison with the first embodiment. Moreover, the fourth embodiment may be manufactured more easily and its yield rate may be higher when compared to the first embodiment. 
     Reference is now made to  FIGS. 22-25 .  FIG. 22  illustrates an example cross-sectional view of an optical imaging lens  5  having six lens elements according to a fifth example embodiment.  FIG. 23  shows example charts of longitudinal spherical aberration and other kinds of optical aberrations of the optical imaging lens  5  according to the fifth embodiment.  FIG. 24  shows an example table of optical data of each lens element of the optical imaging lens  5  according to the fifth example embodiment.  FIG. 25  shows an example table of aspherical data of the optical imaging lens  5  according to the fifth example embodiment. The reference numbers labeled in the present embodiment are similar to those in the first embodiment for the similar elements, but here the reference numbers are initialed with 5, for example, reference number  531  for labeling the object-side surface of the third lens element  530 , reference number  532  for labeling the image-side surface of the third lens element  530 , etc. 
     As shown in  FIG. 22 , the optical imaging lens  5  of the present embodiment, in an order from an object side A 1  to an image side A 2  along an optical axis, may comprise an aperture stop  500 , a first lens element  510 , a second lens element  520 , a third lens element  530 , a fourth lens element  540 , a fifth lens element  550  and a sixth lens element  560 . 
     The arrangement of the convex or concave surface structures, including the object-side surfaces  511 ,  531 ,  551 , and  561  and the image-side surfaces  512  and  522  are generally similar to the optical imaging lens  1 . The differences between the optical imaging lens  1  and the optical imaging lens  5  may include the concave/convex shapes of at least one of the following: the object-side surfaces  521  and  541 , and the image-side surfaces  532 ,  542 ,  552  and  562 . Additional differences may include the refracting power, a radius of curvature, a thickness, an aspherical data, and an effective focal length of each lens element. More specifically, the object-side surface  521  may comprise a convex portion  5211  in a vicinity of the optical axis, the image image-side surface  532  may comprise a convex portion  5322  in a vicinity of a periphery of the third lens element  530 , the object-side surface  541  may comprise a concave portion  5411  in a vicinity of the optical axis, the image-side surface  542  may comprises a concave portion  5422  in a vicinity of a periphery of the fourth lens element  540 , the image-side surface  552  may comprise a convex portion  5521  in a vicinity of the optical axis, the image-side surface  562  may comprise a convex portion  5621  in a vicinity of the optical axis, the fourth lens element  540  may have negative refracting power, and the fifth lens element  550  may have positive refracting power. 
     Here, for clearly showing the drawings of the present embodiment, only the surface shapes which are different from that in the first embodiment are labeled.  FIG. 24  depicts the optical characteristics of each lens elements in the optical imaging lens  5  of the present embodiment. 
     From the vertical deviation of each curve shown in  FIG. 23  part a, the offset of the off-axis light relative to the image point may be within about ±0.016 mm. Referring to  FIG. 23  part b, the focus variation with respect to the three different wavelengths (470 nm, 555 nm, 650 nm) in the whole field may fall within about ±0.06 mm. Referring to  FIG. 23  part c, the focus variation with respect to the three different wavelengths (470 nm, 555 nm, 650 nm) in the whole field may fall within about ±0.1 mm. Referring to  FIG. 23  part d, the variation of the distortion aberration of the optical imaging lens  5  may be within about ±1.0%. 
     Please refer to  FIG. 50  for the values of BFL, Gaa, ALT, EFL/TTL, T4/T6, BFL/T3, BFL/T6, TTL/T3, T4/G34, T5/G34, ALT/T6, TTL/T6, Gaa/T3, T1/T3, Gaa/T6, T1/T6, BFL/G34, ALT/G34, TTL/G34, Gaa/G34, ALT/T3, ALT/T1 and TTL/T1 of the present embodiment. 
     In comparison to the first embodiment, the fifth embodiment may include decreased values related to at least one of the following: longitudinal spherical aberration, astigmatism aberration in the sagittal and tangential directions, and HFOV. Also, the fifth embodiment may further feature improved image quality in comparison with the first embodiment. Moreover, the fifth embodiment may be manufactured more easily and its yield rate may be higher when compared to the first embodiment. 
     Reference is now made to  FIGS. 26-29 .  FIG. 26  illustrates an example cross-sectional view of an optical imaging lens  6  having six lens elements according to a sixth example embodiment.  FIG. 27  shows example charts of longitudinal spherical aberration and other kinds of optical aberrations of the optical imaging lens  6  according to the sixth embodiment.  FIG. 28  shows an example table of optical data of each lens element of the optical imaging lens  6  according to the sixth example embodiment.  FIG. 29  shows an example table of aspherical data of the optical imaging lens  6  according to the sixth example embodiment. The reference numbers labeled in the present embodiment are similar to those in the first embodiment for the similar elements, but here the reference numbers are initialed with 6, for example, reference number  631  for labeling the object-side surface of the third lens element  630 , reference number  632  for labeling the image-side surface of the third lens element  630 , etc. 
     As shown in  FIG. 26 , the optical imaging lens  6  of the present embodiment, in an order from an object side A 1  to an image side A 2  along an optical axis, may comprise an aperture stop  600 , a first lens element  610 , a second lens element  620 , a third lens element  630 , a fourth lens element  640 , a fifth lens element  650  and a sixth lens element  660 . 
     The arrangement of the convex or concave surface structures, including the object-side surfaces  611 ,  631 ,  641 ,  651 , and  661  and image-side surfaces  612 ,  622 ,  632 ,  652 , and  662  are generally similar with the optical imaging lens  1 . The differences between the optical imaging lens  1  and the optical imaging lens  6  may include the concave/convex shapes of at least one of the following: the object-side surface  621 , and the image-side surface  642 . Additional differences may include the refracting power, a radius of curvature, a thickness, an aspherical data, and an effective focal length of each lens element. More specifically, the object-side surface  621  may comprise a convex portion  6211  in a vicinity of the optical axis, the image-side surface  642  may comprise a convex portion  6422  in a vicinity of a periphery of the fourth lens element  640 , the fourth lens element  640  may have negative refracting power, and the fifth lens element  650  may have positive refracting power. 
     Here, for clearly showing the drawings of the present embodiment, only the surface shapes which are different from that in the first embodiment are labeled. Please refer to  FIG. 28  for the optical characteristics of each lens elements in the optical imaging lens  6  of the present embodiment. 
     From the vertical deviation of each curve shown in  FIG. 27  part a, the offset of the off-axis light relative to the image point may be within about ±0.02 mm. Referring to  FIG. 27  part b, the focus variation with respect to the three different wavelengths (470 nm, 555 nm, 650 nm) in the whole field may fall within about ±0.04 mm. Referring to  FIG. 27  part c, the focus variation with respect to the three different wavelengths (470 nm, 555 nm, 650 nm) in the whole field may fall within about ±0.14 mm. Referring to  FIG. 27  part d, the variation of the distortion aberration of the optical imaging lens  6  may be within about ±1.4%. 
     Please refer to  FIG. 50  for the values of BFL, Gaa, ALT, EFL/TTL, T4/T6, BFL/T3, BFL/T6, TTL/T3, T4/G34, T5/G34, ALT/T6, TTL/T6, Gaa/T3, T1/T3, Gaa/T6, T1/T6, BFL/G34, ALT/G34, TTL/G34, Gaa/G34, ALT/T3, ALT/T1 and TTL/T1 of the present embodiment. 
     In comparison with the first embodiment, the sixth embodiment may include decreased values related to at least one of the following: the longitudinal spherical aberration, the astigmatism aberration in the sagittal and tangential directions, and HFOV of the sixth embodiment. Also, the sixth embodiment may further feature improved image quality in comparison with the first embodiment. Moreover, the sixth embodiment may be manufactured more easily and its yield rate may be higher when compared to the first embodiment. 
     Reference is now made to  FIGS. 30-33 .  FIG. 30  illustrates an example cross-sectional view of an optical imaging lens  7  having six lens elements according to a seventh example embodiment.  FIG. 31  shows example charts of longitudinal spherical aberration and other kinds of optical aberrations of the optical imaging lens  7  according to the seventh embodiment.  FIG. 32  shows an example table of optical data of each lens element of the optical imaging lens  7  according to the seventh example embodiment.  FIG. 33  shows an example table of aspherical data of the optical imaging lens  7  according to the seventh example embodiment. The reference numbers labeled in the present embodiment are similar to those in the first embodiment for the similar elements, but here the reference numbers are initialed with 7, for example, reference number  731  for labeling the object-side surface of the third lens element  730 , reference number  732  for labeling the image-side surface of the third lens element  730 , etc. 
     As shown in  FIG. 30 , the optical imaging lens  7  of the present embodiment, in an order from an object side A 1  to an image side A 2  along an optical axis, may comprise an aperture stop  700 , a first lens element  710 , a second lens element  720 , a third lens element  730 , a fourth lens element  740 , a fifth lens element  750  and a sixth lens element  760 . 
     The arrangement of the convex or concave surface structures, including the object-side surfaces  711 ,  731 ,  751 , and  761  and image-side surfaces  712 ,  722 , and  762  are generally similar with the optical imaging lens  1 . The differences between the optical imaging lens  1  and the optical imaging lens  7  may include the concave/convex shapes of at least one of the following: the object-side surfaces  721  and  741 , and the image-side surfaces  732 ,  742 , and  752 . Additional differences may include refracting power, radius of curvature, thickness, aspherical data, and effective focal length of each lens element. More specifically, the object-side surface  721  may comprise a convex portion  7211  in a vicinity of the optical axis, the image-side surface  732  may comprise a convex portion  7322  in a vicinity of a periphery of the third lens element  730 , the object-side surface  741  may comprise a concave portion  7411  in a vicinity of the optical axis, the image-side surface  742  may comprise a concave portion  7422  in a vicinity of a periphery of the fourth lens element  740 , the image-side surface  752  may comprise a concave portion  7521  in a vicinity of the optical axis, the fourth lens element  740  may have negative refracting power, and the fifth lens element  750  may have positive refracting power. 
     Here, for clearly showing the drawings of the present embodiment, only the surface shapes which are different from that in the first embodiment are labeled. Please refer to  FIG. 32  for the optical characteristics of each lens elements in the optical imaging lens  7  of the present embodiment. 
     From the vertical deviation of each curve shown in  FIG. 31  part a, the offset of the off-axis light relative to the image point may be within ±0.014 mm. Referring to  FIG. 31  part b, the focus variation with respect to the three different wavelengths (470 nm, 555 nm, 650 nm) in the whole field falls within ±0.035 mm. Referring to  FIG. 31  part c, the focus variation with respect to the three different wavelengths (470 nm, 555 nm, 650 nm) in the whole field falls within ±0.05 mm. Referring to  FIG. 31  part d, the variation of the distortion aberration of the optical imaging lens  7  may be within ±1.4%. 
     Please refer to  FIG. 50  for the values of BFL, Gaa, ALT, EFL/TTL, T4/T6, BFL/T3, BFL/T6, TTL/T3, T4/G34, T5/G34, ALT/T6, TTL/T6, Gaa/T3, T1/T3, Gaa/T6, T1/T6, BFL/G34, ALT/G34, TTL/G34, Gaa/G34, ALT/T3, ALT/T1 and TTL/T1 of the present embodiment. 
     In comparison to the first embodiment, the seventh embodiment may include improved values related to at least one of the following: longitudinal spherical aberration, astigmatism aberration in the sagittal and tangential directions, and HFOV. Moreover, the fourth embodiment may be manufactured more easily and its yield rate may be higher when compared to the first embodiment. 
     Reference is now made to  FIGS. 34-37 .  FIG. 34  illustrates an example cross-sectional view of an optical imaging lens  8  having six lens elements according to an eighth example embodiment.  FIG. 35  shows example charts of longitudinal spherical aberration and other kinds of optical aberrations of the optical imaging lens  8  according to the eighth embodiment.  FIG. 36  shows an example table of optical data of each lens element of the optical imaging lens  8  according to the eighth example embodiment.  FIG. 37  shows an example table of aspherical data of the optical imaging lens  8  according to the eighth example embodiment. The reference numbers labeled in the present embodiment are similar to those in the first embodiment for the similar elements, but here the reference numbers are initialed with 8, for example, reference number  831  for labeling the object-side surface of the third lens element  830 , reference number  832  for labeling the image-side surface of the third lens element  830 , etc. 
     As shown in  FIG. 34 , the optical imaging lens  8  of the present embodiment, in an order from an object side A 1  to an image side A 2  along an optical axis, may comprise an aperture stop  800 , a first lens element  810 , a second lens element  820 , a third lens element  830 , a fourth lens element  840 , a fifth lens element  850  and a sixth lens element  860 . 
     The arrangement of the convex or concave surface structures, including the object-side surfaces  811 ,  831 ,  841 ,  851 , and  861 , and the image-side surfaces  812 ,  822 ,  842 , and  862  are generally similar with the optical imaging lens  1 . The differences between the optical imaging lens  1  and the optical imaging lens  8  may include the concave/convex shapes of at least one of the following: the object-side surface  821 , and the image-side surfaces  832  and  852 . Additional differences may include the refracting power, a radius of curvature, a thickness, an aspherical data, and an effective focal length of each lens element. More specifically, the object-side surface  821  may comprise a concave portion  8211  in a vicinity of the optical axis, the image-side surface  832  may comprise a convex portion  8322  in a vicinity of a periphery of the third lens element  830 , the image-side surface  852  may comprise a convex portion  8521  in a vicinity of the optical axis, the fourth lens element  840  may have negative refracting power, and the fifth lens element  850  may have positive refracting power. 
     Here, for clearly showing the drawings of the present embodiment, only the surface shapes which are different from that in the first embodiment are labeled. Please refer to  FIG. 36  for the optical characteristics of each lens elements in the optical imaging lens  8  of the present embodiment. 
     From the vertical deviation of each curve shown in  FIG. 35  part a, the offset of the off-axis light relative to the image point may be within ±0.025 mm. Referring to  FIG. 35  part b, the focus variation with respect to the three different wavelengths (470 nm, 555 nm, 650 nm) in the whole field falls within ±0.025 mm. Referring to  FIG. 35  part c, the focus variation with respect to the three different wavelengths (470 nm, 555 nm, 650 nm) in the whole field falls within ±0.05 mm. Referring to  FIG. 35  part d, the variation of the distortion aberration of the optical imaging lens  8  may be within ±2.5%. 
     Please refer to  FIG. 50  for the values of BFL, Gaa, ALT, EFL/TTL, T4/T6, BFL/T3, BFL/T6, TTL/T3, T4/G34, T5/G34, ALT/T6, TTL/T6, Gaa/T3, T1/T3, Gaa/T6, T1/T6, BFL/G34, ALT/G34, TTL/G34, Gaa/G34, ALT/T3, ALT/T1 and TTL/T1 of the present embodiment. 
     In comparison to the first embodiment, the eighth embodiment may include decreased values related to at least one of the following: longitudinal spherical aberration, astigmatism aberration in the sagittal and tangential directions, and HFOV. Also, the eighth embodiment may further feature improved image quality in comparison with the first embodiment. Moreover, the eighth embodiment may be manufactured more easily and its yield rate may be higher when compared to the first embodiment. 
     Reference is now made to  FIGS. 38-41 .  FIG. 38  illustrates an example cross-sectional view of an optical imaging lens  9  having six lens elements according to a ninth example embodiment.  FIG. 39  shows example charts of longitudinal spherical aberration and other kinds of optical aberrations of the optical imaging lens  9  according to the ninth embodiment.  FIG. 40  shows an example table of optical data of each lens element of the optical imaging lens  9  according to the ninth example embodiment.  FIG. 41  shows an example table of aspherical data of the optical imaging lens  9  according to the ninth example embodiment. The reference numbers labeled in the present embodiment are similar to those in the first embodiment for the similar elements, but here the reference numbers are initialed with 9, for example, reference number  931  for labeling the object-side surface of the third lens element  930 , reference number  932  for labeling the image-side surface of the third lens element  930 , etc. 
     As shown in  FIG. 38 , the optical imaging lens  9  of the present embodiment, in an order from an object side A 1  to an image side A 2  along an optical axis, may comprise an aperture stop  900 , a first lens element  910 , a second lens element  920 , a third lens element  930 , a fourth lens element  940 , a fifth lens element  950  and a sixth lens element  960 . 
     The arrangement of the convex or concave surface structures, including the object-side surfaces  911 ,  931 , and  961 , and the image-side surfaces  912 ,  922 , and  952  are generally similar with the optical imaging lens  1 . The differences between the optical imaging lens  1  and the optical imaging lens  9  may include the concave/convex shapes of at least one of the following: the object-side surfaces  921 ,  941 , and  951 , and the image-side surfaces  932 ,  942 , and  962 . Additional differences may include the refracting power, a radius of curvature, a thickness, an aspherical data, and an effective focal length of each lens element. More specifically, the object-side surface  921  may comprise a convex portion  9211  in a vicinity of the optical axis, the image-side surface  932  may comprise a convex portion  9322  in a vicinity of a periphery of the third lens element  930 , the object-side surface  941  may comprise a concave portion  9411  in a vicinity of the optical axis, the image-side surface  942  may comprise a convex portion  9421  in a vicinity of the optical axis and a concave portion  9422  in a vicinity of a periphery of the fourth lens element  940 , the object-side surface  951  may comprise a convex portion  9511  in a vicinity of the optical axis, the image-side surface  962  may comprise a convex portion  9621  in a vicinity of the optical axis, the fourth lens element  940  may have negative refracting power, and the sixth lens element  960  may have positive refracting power. 
     Here, for clearly showing the drawings of the present embodiment, only the surface shapes which are different from that in the first embodiment are labeled. Please refer to  FIG. 40  for the optical characteristics of each lens elements in the optical imaging lens  9  of the present embodiment. 
     From the vertical deviation of each curve shown in  FIG. 39  part a, the offset of the off-axis light relative to the image point may be within ±0.04 mm. Referring to  FIG. 39  part b, the focus variation with respect to the three different wavelengths (470 nm, 555 nm, 650 nm) in the whole field falls within ±0.04 mm. Referring to  FIG. 39  part c, the focus variation with respect to the three different wavelengths (470 nm, 555 nm, 650 nm) in the whole field falls within ±0.07 mm. Referring to  FIG. 39  part d, the variation of the distortion aberration of the optical imaging lens  9  may be within ±2.5%. 
     Please refer to  FIG. 50  for the values of BFL, Gaa, ALT, EFL/TTL, T4/T6, BFL/T3, BFL/T6, TTL/T3, T4/G34, T5/G34, ALT/T6, TTL/T6, Gaa/T3, T1/T3, Gaa/T6, T1/T6, BFL/G34, ALT/G34, TTL/G34, Gaa/G34, ALT/T3, ALT/T1 and TTL/T1 of the present embodiment. 
     In comparison with the first embodiment, the ninth embodiment may include decreased values related to at least one of the following: longitudinal spherical aberration, astigmatism aberration in the sagittal and tangential directions, and HFOV. Moreover, the ninth embodiment may be manufactured more easily and its yield rate may be higher when compared to the first embodiment. 
     Reference is now made to  FIGS. 42-45 .  FIG. 42  illustrates an example cross-sectional view of an optical imaging lens  10  having six lens elements according to a tenth example embodiment.  FIG. 43  shows example charts of longitudinal spherical aberration and other kinds of optical aberrations of the optical imaging lens  10  according to the tenth embodiment.  FIG. 44  shows an example table of optical data of each lens element of the optical imaging lens  10  according to the tenth example embodiment.  FIG. 45  shows an example table of aspherical data of the optical imaging lens  10  according to the tenth example embodiment. The reference numbers labeled in the present embodiment are similar to those in the first embodiment for the similar elements, but here the reference numbers are initialed with 10, for example, reference number  1031  for labeling the object-side surface of the third lens element  930 , reference number  1032  for labeling the image-side surface of the third lens element  1030 , etc. 
     As shown in  FIG. 42 , the optical imaging lens  10  of the present embodiment, in an order from an object side A 1  to an image side A 2  along an optical axis, may comprise an aperture stop  1000 , a first lens element  1010 , a second lens element  1020 , a third lens element  1030 , a fourth lens element  1040 , a fifth lens element  1050  and a sixth lens element  1060 . 
     The arrangement of the convex or concave surface structures, including the object-side surfaces  1011 ,  1031 ,  1041 ,  1051 , and  1061 , and the image-side surfaces  1012 ,  1022 ,  1032 ,  1042 , and  1062  are generally similar with the optical imaging lens  1 . The differences between the optical imaging lens  1  and the optical imaging lens  10  may include the concave/convex shapes of at least one of the following: the object-side surface  1021 , and the image-side surface  1052 . Additional differences may include the refracting power, a radius of curvature, a thickness, an aspherical data, and an effective focal length of each lens element. More specifically, the object-side surface  1021  may comprise a convex portion  10211  in a vicinity of the optical axis, the image-side surface  1052  may comprise a convex portion  10521  in a vicinity of the optical axis, the fourth lens element  1040  may have negative refracting power, and the fifth lens element  1050  may have positive refracting power. 
     Here, for clearly showing the drawings of the present embodiment, only the surface shapes which are different from that in the first embodiment are labeled. Please refer to  FIG. 44  for the optical characteristics of each lens elements in the optical imaging lens  10  of the present embodiment. 
     From the vertical deviation of each curve shown in  FIG. 43  part a, the offset of the off-axis light relative to the image point may be within ±0.025 mm. Referring to  FIG. 43  part b, the focus variation with respect to the three different wavelengths (470 nm, 555 nm, 650 nm) in the whole field falls within ±0.025 mm. Referring to  FIG. 43  part c, the focus variation with respect to the three different wavelengths (470 nm, 555 nm, 650 nm) in the whole field falls within ±0.025 mm. Referring to  FIG. 43  part d, the variation of the distortion aberration of the optical imaging lens  9  may be within ±0.8%. 
     Please refer to  FIG. 50  for the values of BFL, Gaa, ALT, EFL/TTL, T4/T6, BFL/T3, BFL/T6, TTL/T3, T4/G34, T5/G34, ALT/T6, TTL/T6, Gaa/T3, T1/T3, Gaa/T6, T1/T6, BFL/G34, ALT/G34, TTL/G34, Gaa/G34, ALT/T3, ALT/T1 and TTL/T1 of the present embodiment. 
     In comparison with the first embodiment, the tenth embodiment may include decreased values related to at least one of the following: longitudinal spherical aberration, astigmatism aberration in the tangential direction, and HFOV. Moreover, the tenth embodiment may be manufactured more easily and its yield rate may be higher when compared to the first embodiment. 
     Reference is now made to  FIGS. 46-49 .  FIG. 46  illustrates an example cross-sectional view of an optical imaging lens  11  having six lens elements of the optical imaging lens according to a eleventh example embodiment.  FIG. 47  shows example charts of longitudinal spherical aberration and other kinds of optical aberrations of the optical imaging lens  11  according to the eleventh example embodiment.  FIG. 48  shows an example table of optical data of each lens element of the optical imaging lens  11  according to the eleventh example embodiment.  FIG. 49  shows an example table of aspherical data of the optical imaging lens  11  according to the eleventh example embodiment. The reference numbers labeled in the present embodiment are similar to those in the first embodiment for the similar elements, but here the reference numbers are initialed with 11, for example, reference number  1131  for labeling the object-side surface of the third lens element  1130 , reference number  1132  for labeling the image-side surface of the third lens element  1130 , etc. 
     As shown in  FIG. 46 , the optical imaging lens  11  of the present embodiment, in an order from an object side A 1  to an image side A 2  along an optical axis, may comprise an aperture stop  1100 , a first lens element  1110 , a second lens element  1120 , a third lens element  1130 , a fourth lens element  1140 , a fifth lens element  1150  and a sixth lens element  1160 . 
     The arrangement of the convex or concave surface structures, including the object-side surfaces  1111 ′,  1131 ,  1151 , and  1161  and image-side surfaces  1112 ′,  1122 ′,  1132 , and  1152  are generally the same as the optical imaging lens  1 . The differences between the optical imaging lens  1  and the optical imaging lens  11  may include the concave/convex shapes of at least one of the following: the object-side surfaces  1121 ′ and  1141 , and the image-side surfaces  1142 ,  1162 . Additional differences may include the refracting power, a radius of curvature, a refracting power, a thickness, an aspherical data, and an effective focal length of each lens element. More specifically, the object-side surface  1121 ′ may comprise a convex portion  11211  in a vicinity of the optical axis, the object-side surface  1141  may comprise a concave portion  11411  in a vicinity of the optical axis, the image-side surface  1142  may comprise a convex portion  11421  in a vicinity of the optical axis, the image-side surface  1162  may comprise a convex portion  11621  in a vicinity of the optical axis, and the fifth lens element  1150  may have positive refracting power. 
     Here, for clearly showing the drawings of the present embodiment, only the surface shapes which are different from that in the tenth embodiment are labeled. Please refer to FIG.  48  for the optical characteristics of each lens elements in the optical imaging lens  11  of the present embodiment. 
     From the vertical deviation of each curve shown in  FIG. 47  part a, the offset of the off-axis light relative to the image point may be within about ±0.12 mm. Referring to  FIG. 47  part b, the focus variation with respect to the three different wavelengths (470 nm, 555 nm, 650 nm) in the whole field may fall within about ±0.2 mm. Referring to  FIG. 47  part c, the focus variation with respect to the three different wavelengths (470 nm, 555 nm, 650 nm) in the whole field may fall within about ±0.25 mm. Referring to  FIG. 47  part d, the variation of the distortion aberration of the optical imaging lens  11  may be within about ±2.5%. 
     Please refer to  FIG. 50  for the values of BFL, Gaa, ALT, EFL/TTL, T4/T6, BFL/T3, BFL/T6, TTL/T3, T4/G34, T5/G34, ALT/T6, TTL/T6, Gaa/T3, T1/T3, Gaa/T6, T1/T6, BFL/G34, ALT/G34, TTL/G34, Gaa/G34, ALT/T3, ALT/T1 and TTL/T1 of the present embodiment. 
     In comparison with the first embodiment, the HFOV of the eleventh embodiment may be smaller. Further, the eleventh embodiment may be manufactured more easily and the yield rate may be higher in comparison with the first embodiment. 
     Please refer to FIG.  FIG. 50  which shows the values of BFL, Gaa, ALT, EFL/TTL, T4/T6, BFL/T3, BFL/T6, TTL/T3, T4/G34, T5/G34, ALT/T6, TTL/T6, Gaa/T3, T1/T3, Gaa/T6, T1/T6, BFL/G34, ALT/G34, TTL/G34, Gaa/G34, ALT/T3, ALT/T1 and TTL/T1 of the first to eleventh embodiments, and it is clear that the optical imaging lenses of the first to eleventh embodiments may satisfy the Equations (1)-(21). 
     According to above disclosure, the longitudinal spherical aberration, the astigmatism aberration and the variation of the distortion aberration of each embodiment meet the use requirements of various electronic products which implement an optical imaging lens. Moreover, the off-axis light with respect to 470 nm, 555 nm and 650 nm wavelengths may be focused around an image point, and the offset of the off-axis light for each curve relative to the image point may be controlled to effectively inhibit the longitudinal spherical aberration, the astigmatism aberration and the variation of the distortion aberration. Further, as shown by the imaging quality data provided for each embodiment, the distance between the 470 nm, 555 nm and 650 nm wavelengths may indicate that focusing ability and inhibiting ability for dispersion is provided for different wavelengths. 
     According to above illustration, the optical imaging lens of the present disclosure may provide an effectively shortened optical imaging lens length while maintaining good optical characteristics, by controlling the structure of the lens elements as well as at least one of the inequalities described herein. 
     While various embodiments in accordance with the disclosed principles been described above, it should be understood that they are presented by way of example only, and are not limiting. Thus, the breadth and scope of exemplary embodiment(s) should not be limited by any of the above-described embodiments, but should be defined only in accordance with the claims and their equivalents issuing from this disclosure. Furthermore, the above advantages and features are provided in described embodiments, but shall not limit the application of such issued claims to processes and structures accomplishing any or all of the above advantages. 
     Additionally, the section headings herein are provided for consistency with the suggestions under 37 C.F.R. 1.77 or otherwise to provide organizational cues. These headings shall not limit or characterize the invention(s) set out in any claims that may issue from this disclosure. Specifically, a description of a technology in the “Background” is not to be construed as an admission that technology is prior art to any invention(s) in this disclosure. Furthermore, any reference in this disclosure to “invention” in the singular should not be used to argue that there is only a single point of novelty in this disclosure. Multiple inventions may be set forth according to the limitations of the multiple claims issuing from this disclosure, and such claims accordingly define the invention(s), and their equivalents, that are protected thereby. In all instances, the scope of such claims shall be considered on their own merits in light of this disclosure, but should not be constrained by the headings herein.