Patent Publication Number: US-10324273-B2

Title: Optical lens set

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority from Chinese patent application No. 201610755720.8, filed on Aug. 29, 2016, the contents of which are hereby incorporated by reference in their entirety for all purposes. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to an optical imaging lens set. Specifically speaking, the present invention is directed to an optical imaging lens set of five lens elements for use in mobile phones, in cameras, in tablet personal computers, or in personal digital assistants (PDA). 
     2. Description of the Prior Art 
     In recent years, the popularity of mobile phones and digital cameras makes the specifications of various portable electronic products improve quickly, and so does the key component—the optical imaging lens set. However, good and necessary optical properties for taking pictures or recording videos are not enough. There is still a need for telescopic function. 
     With the development of image sensors, the demands for the imaging quality are getting higher and higher. The conventional size of the telescopic optical imaging lens set is longer than 50 mm and Fno number is over 4. They fail to meet the demands for the specification of current portable electronic products. Accordingly, an optical imaging lens set of telescopic function which has improved imaging quality with reduced lens set size is still needed. 
     SUMMARY OF THE INVENTION 
     In light of the above, the present invention proposes an optical imaging lens set which has a reduced optical imaging lens system length and keeps sufficient optical performance. The optical imaging lens set of five lens elements of the present invention from an object side toward an image side in order along an optical axis has a first lens element, a second lens element, a third lens element, a fourth lens element and a fifth lens element. Each lens element has an object-side surface facing toward an object side as well as an image-side surface facing toward an image side. The optical imaging lens set exclusively has the first lens element, the second lens element, the third lens element, the fourth lens element and the fifth lens element with refractive power. 
     The first lens element has an image-side surface with a concave portion in a vicinity of its periphery. The second lens element is of a plastic material. The third lens element has an object-side surface with a concave portion in a vicinity of the optical-axis and an image-side surface with a concave portion in a vicinity of its periphery. The fourth lens element has an object-side surface with a concave portion in a vicinity of the optical-axis. The fifth lens element has an object-side surface with a concave portion in a vicinity of its periphery and an image-side surface with a convex portion in a vicinity of the optical-axis. 
     In the optical imaging lens set of five lens elements of the present invention, TTL is a distance from the first object-side surface to an image plane and the second lens element has a second lens element thickness T 2  to satisfy 10.50≤TTL/T 2 ≤22.80. 
     In the optical imaging lens set of five lens elements of the present invention, ALT is the total thickness of all five lens elements, an air gap G 12  between the first lens element and the second lens element along the optical axis and an air gap G 45  between the fourth lens element and the fifth lens element along the optical axis to satisfy 5.50≤ALT/(G 12 +G 45 ). 
     The optical imaging lens set of five lens elements of the present invention satisfies 6.50≤ALT/T 2 . 
     In the optical imaging lens set of five lens elements of the present invention, an air gap G 23  between the second lens element and the third lens element along the optical axis satisfies 4.20≤TTL/(G 12 +G 23 +G 45 ). 
     In the optical imaging lens set of five lens elements of the present invention, the fourth lens element has a fourth lens element thickness T 4  to satisfy ALT/T 4 ≤8.60. 
     The optical imaging lens set of five lens elements of the present invention satisfies 4.20≤TTL/(G 23 +G 45 )≤8.50. 
     In the optical imaging lens set of five lens elements of the present invention, EFL is the effective focal length of the optical imaging lens set to satisfy EFL/(G 12 +G 23 )≤12.70. 
     In the optical imaging lens set of five lens elements of the present invention, the fifth lens element has a fifth lens element thickness T 5  to satisfy TTL/(T 4 +T 5 )≤6.50. 
     The optical imaging lens set of five lens elements of the present invention satisfies EFL/(G 23 +G 45 )≤8.6. 
     In the optical imaging lens set of five lens elements of the present invention, the third lens element has a third lens element thickness T 3  to satisfy 4.20≤ALT/(T 2 +T 3 ). 
     In the optical imaging lens set of five lens elements of the present invention, the first lens element has a first lens element thickness T 1  to satisfy 2.80≤(T 1 +T 4 )/T 2 ≤4.50. 
     The optical imaging lens set of five lens elements of the present invention satisfies EFL/(G 12 +G 23 +G 45 )≤10.50. 
     In the optical imaging lens set of five lens elements of the present invention, an air gap G 34  between the third lens element and the fourth lens element along the optical axis satisfies 1.3≤ALT/G 34 . 
     The optical imaging lens set of five lens elements of the present invention satisfies 8.50≤EFL/T 5 ≤11.80. 
     The optical imaging lens set of five lens elements of the present invention satisfies 3.70≤EFL/G 34 ≤12.50. 
     The optical imaging lens set of five lens elements of the present invention satisfies 4.00≤TTL/(T 1 +T 2 ). 
     The optical imaging lens set of five lens elements of the present invention satisfies 3.20≤TTL/(G 12 +G 34 ). 
     The optical imaging lens set of five lens elements of the present invention satisfies 9.50≤EFL/(T 2 +T 4 ). 
     These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1-5  illustrates the methods for determining the surface shapes and for determining one region is a region in a vicinity of the optical axis or the region in a vicinity of its circular periphery of one lens element. 
         FIG. 6  illustrates a first example of the optical imaging lens set of the present invention. 
         FIG. 7A  illustrates the longitudinal spherical aberration on the image plane of the first example. 
         FIG. 7B  illustrates the astigmatic aberration on the sagittal direction of the first example. 
         FIG. 7C  illustrates the astigmatic aberration on the tangential direction of the first example. 
         FIG. 7D  illustrates the distortion aberration of the first example. 
         FIG. 8  illustrates a second example of the optical imaging lens set of five lens elements of the present invention. 
         FIG. 9A  illustrates the longitudinal spherical aberration on the image plane of the second example. 
         FIG. 9B  illustrates the astigmatic aberration on the sagittal direction of the second example. 
         FIG. 9C  illustrates the astigmatic aberration on the tangential direction of the second example. 
         FIG. 9D  illustrates the distortion aberration of the second example. 
         FIG. 10  illustrates a third example of the optical imaging lens set of five lens elements of the present invention. 
         FIG. 11A  illustrates the longitudinal spherical aberration on the image plane of the third example. 
         FIG. 11B  illustrates the astigmatic aberration on the sagittal direction of the third example. 
         FIG. 11C  illustrates the astigmatic aberration on the tangential direction of the third example. 
         FIG. 11D  illustrates the distortion aberration of the third example. 
         FIG. 12  illustrates a fourth example of the optical imaging lens set of five lens elements of the present invention. 
         FIG. 13A  illustrates the longitudinal spherical aberration on the image plane of the fourth example. 
         FIG. 13B  illustrates the astigmatic aberration on the sagittal direction of the fourth example. 
         FIG. 13C  illustrates the astigmatic aberration on the tangential direction of the fourth example. 
         FIG. 13D  illustrates the distortion aberration of the fourth example. 
         FIG. 14  illustrates a fifth example of the optical imaging lens set of five lens elements of the present invention. 
         FIG. 15A  illustrates the longitudinal spherical aberration on the image plane of the fifth example. 
         FIG. 15B  illustrates the astigmatic aberration on the sagittal direction of the fifth example. 
         FIG. 15C  illustrates the astigmatic aberration on the tangential direction of the fifth example. 
         FIG. 15D  illustrates the distortion aberration of the fifth example. 
         FIG. 16  illustrates a sixth example of the optical imaging lens set of five lens elements of the present invention. 
         FIG. 17A  illustrates the longitudinal spherical aberration on the image plane of the sixth example. 
         FIG. 17B  illustrates the astigmatic aberration on the sagittal direction of the sixth example. 
         FIG. 17C  illustrates the astigmatic aberration on the tangential direction of the sixth example. 
         FIG. 17D  illustrates the distortion aberration of the sixth example. 
         FIG. 18  illustrates a seventh example of the optical imaging lens set of five lens elements of the present invention. 
         FIG. 19A  illustrates the longitudinal spherical aberration on the image plane of the seventh example. 
         FIG. 19B  illustrates the astigmatic aberration on the sagittal direction of the seventh example. 
         FIG. 19C  illustrates the astigmatic aberration on the tangential direction of the seventh example. 
         FIG. 19D  illustrates the distortion aberration of the seventh example. 
         FIG. 20  illustrates an eighth example of the optical imaging lens set of five lens elements of the present invention. 
         FIG. 21A  illustrates the longitudinal spherical aberration on the image plane of the eighth example. 
         FIG. 21B  illustrates the astigmatic aberration on the sagittal direction of the eighth example. 
         FIG. 21C  illustrates the astigmatic aberration on the tangential direction of the eighth example. 
         FIG. 21D  illustrates the distortion aberration of the eighth example. 
         FIG. 22  illustrates a ninth example of the optical imaging lens set of five lens elements of the present invention. 
         FIG. 23A  illustrates the longitudinal spherical aberration on the image plane of the ninth example. 
         FIG. 23B  illustrates the astigmatic aberration on the sagittal direction of the ninth example. 
         FIG. 23C  illustrates the astigmatic aberration on the tangential direction of the ninth example. 
         FIG. 23D  illustrates the distortion aberration of the ninth example. 
         FIG. 24  shows the optical data of the first example of the optical imaging lens set. 
         FIG. 25  shows the aspheric surface data of the first example. 
         FIG. 26  shows the optical data of the second example of the optical imaging lens set. 
         FIG. 27  shows the aspheric surface data of the second example. 
         FIG. 28  shows the optical data of the third example of the optical imaging lens set. 
         FIG. 29  shows the aspheric surface data of the third example. 
         FIG. 30  shows the optical data of the fourth example of the optical imaging lens set. 
         FIG. 31  shows the aspheric surface data of the fourth example. 
         FIG. 32  shows the optical data of the fifth example of the optical imaging lens set. 
         FIG. 33  shows the aspheric surface data of the fifth example. 
         FIG. 34  shows the optical data of the sixth example of the optical imaging lens set. 
         FIG. 35  shows the aspheric surface data of the sixth example. 
         FIG. 36  shows the optical data of the seventh example of the optical imaging lens set. 
         FIG. 37  shows the aspheric surface data of the seventh example. 
         FIG. 38  shows the optical data of the eighth example of the optical imaging lens set. 
         FIG. 39  shows the aspheric surface data of the eighth example. 
         FIG. 40  shows the optical data of the ninth example of the optical imaging lens set. 
         FIG. 41  shows the aspheric surface data of the ninth example. 
         FIG. 42  shows some important ratios in the examples. 
     
    
    
     DETAILED DESCRIPTION 
     Before the detailed description of the present invention, the first thing to be noticed is that in the present invention, similar (not necessarily identical) elements are labeled as the same numeral references. In the entire present specification, “a certain lens element has negative/positive refractive power” refers to the part in a vicinity of the optical axis of the lens element has negative/positive refractive power calculated by Gaussian optical theory. An object-side/image-side surface refers to the region which allows imaging light passing through, in the drawing, imaging light includes Lc (chief ray) and Lm (marginal ray). As shown in  FIG. 1 , the optical axis is “I” and the lens element is symmetrical with respect to the optical axis I. The region A that near the optical axis and for light to pass through is the region in a vicinity of the optical axis, and the region C that the marginal ray passing through is the region in a vicinity of a certain lens element&#39;s circular periphery. In addition, the lens element may include an extension part E for the lens element to be installed in an optical imaging lens set (that is the region outside the region C perpendicular to the optical axis). Ideally speaking, no light would pass through the extension part, and the actual structure and shape of the extension part is not limited to this and may have other variations. For the reason of simplicity, the extension part is not illustrated in the following examples. More, precisely, the method for determining the surface shapes or the region in a vicinity of the optical axis, the region in a vicinity of its circular periphery and other regions is described in the following paragraphs:
     1.  FIG. 1  is a radial cross-sectional view of a lens element. Before determining boundaries of those aforesaid portions, two referential points should be defined first, middle point and conversion point. The middle point of a surface of a lens element is a point of intersection of that surface and the optical axis. The conversion 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 conversion points appear on one single surface, then these conversion points are sequentially named along the radial direction of the surface with numbers starting from the first conversion point. For instance, the first conversion point (closest one to the optical axis), the second conversion point, and the N th  conversion point (farthest one to the optical axis within the scope of the clear aperture of the surface). The portion of a surface of the lens element between the middle point and the first conversion point is defined as the portion in a vicinity of the optical axis. The portion located radially outside of the N th  conversion point (but still within the scope of the clear aperture) is defined as the portion in a vicinity of a periphery of the lens element. In some embodiments, there are other portions existing between the portion in a vicinity of the optical axis and the portion in a vicinity of a periphery of the lens element; the numbers of portions depend on the numbers of the conversion 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.   2. Referring to  FIG. 2 , determining the shape of a portion is convex or concave depends on whether a collimated ray passing through that portion converges or diverges. That is, while applying a collimated ray to a portion to be determined in terms of shape, the collimated ray passing through that portion will be bended and the ray itself or its extension line will eventually meet the optical axis. The shape of that portion 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 portion, i.e. the focal point of this ray is at the image side (see point R in  FIG. 2 ), the portion will be determined as having a convex shape. On the contrary, if the ray diverges after passing through a portion, 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 portion will be determined as having a concave shape. Therefore, referring to  FIG. 2 , the portion between the middle point and the first conversion point has a convex shape, the portion located radially outside of the first conversion point has a concave shape, and the first conversion point is the point where the portion having a convex shape changes to the portion having a concave shape, namely the border of two adjacent portions. Alternatively, there is another common way for a person with ordinary skill in the art to tell whether a portion in a vicinity of the optical axis has 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 is commonly 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.   3. For none conversion point cases, the portion in a vicinity of the optical axis is defined as the portion between 0˜50% of the effective radius (radius of the clear aperture) of the surface, whereas the portion in a vicinity of a periphery of the lens element is defined as the portion 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 conversion point, namely a first conversion point, appears within the clear aperture of the image-side surface of the lens element. Portion I is a portion in a vicinity of the optical axis, and portion II is a portion in a vicinity of a periphery of the lens element. The portion in a vicinity of the optical axis is 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 portion in a vicinity of a periphery of the lens element is different from that of the radially inner adjacent portion, i.e. the shape of the portion in a vicinity of a periphery of the lens element is different from the shape of the portion in a vicinity of the optical axis; the portion in a vicinity of a periphery of the lens element has a convex shape. 
     Referring to the second example depicted in  FIG. 4 , a first conversion point and a second conversion point exist on the object-side surface (within the clear aperture) of a lens element. In which portion I is the portion in a vicinity of the optical axis, and portion III is the portion in a vicinity of a periphery of the lens element. The portion in a vicinity of the optical axis has a convex shape because the R value at the object-side surface of the lens element is positive. The portion in a vicinity of a periphery of the lens element (portion III) has a convex shape. What is more, there is another portion having a concave shape existing between the first and second conversion point (portion II). 
     Referring to a third example depicted in  FIG. 5 , no conversion point exists on the object-side surface of the lens element. In this case, the portion between 0˜50% of the effective radius (radius of the clear aperture) is determined as the portion in a vicinity of the optical axis, and the portion between 50˜100% of the effective radius is determined as the portion in a vicinity of a periphery of the lens element. The portion in a vicinity of the optical axis of the object-side surface of the lens element is determined as having a convex shape due to its positive R value, and the portion in a vicinity of a periphery of the lens element is determined as having a convex shape as well. 
     As shown in  FIG. 6 , the optical imaging lens set  1  of five lens elements of the present invention, sequentially located from an object side  2  (where an object is located) to an image side  3  along an optical axis  4 , has an aperture stop (ape. stop)  80 , a first lens element  10 , a second lens element  20 , a third lens element  30 , a fourth lens element  40 , a fifth lens element  50 , a filter  70  and an image plane  71 . Generally speaking, the first lens element  10 , the second lens element  20 , the third lens element  30 , the fourth lens element  40  and the fifth lens element  50  may be made of a transparent plastic material but the present invention is not limited to this, and each lens element has an appropriate refractive power. There are exclusively five lens elements, which means the first lens element  10 , the second lens element  20 , the third lens element  30 , the fourth lens element  40  and the fifth lens element  50  with refractive power in the optical imaging lens set  1  of the present invention. The optical axis  4  is the optical axis of the entire optical imaging lens set  1 , and the optical axis of each of the lens elements coincides with the optical axis of the optical imaging lens set  1 . 
     Furthermore, the optical imaging lens set  1  includes an aperture stop (ape. stop)  80  disposed in an appropriate position. In  FIG. 6 , the aperture stop  80  is disposed between the object side  2  and the first lens element  10 . When light emitted or reflected by an object (not shown) which is located at the object side  2  enters the optical imaging lens set  1  of the present invention, it forms a clear and sharp image on the image plane  71  at the image side  3  after passing through the aperture stop  80 , the first lens element  10 , the second lens element  20 , the third lens element  30 , the fourth lens element  40 , the fifth lens element  50  and the filter  70 . In one embodiments of the present invention, the optional filter  70  may be a filter of various suitable functions. For example, the filter  70  may be an infrared cut filter (IR cut filter), placed between the image-side surface  52  of the fifth lens element  50  and the image plane  71 . 
     Each lens element in the optical imaging lens set  1  of the present invention has an object-side surface facing toward the object side  2  as well as an image-side surface facing toward the image side  3 . For example, the first lens element  10  has a first object-side surface  11  and a first image-side surface  12 ; the second lens element  20  has a second object-side surface  21  and a second image-side surface  22 ; the third lens element  30  has a third object-side surface  31  and a third image-side surface  32 ; the fourth lens element  40  has a fourth object-side surface  41  and a fourth image-side surface  42 ; the fifth lens element  50  has a fifth object-side surface  51  and a fifth image-side surface  52 . In addition, each object-side surface and image-side surface in the optical imaging lens set  1  of the present invention has a part (or portion) in a vicinity of its circular periphery (circular periphery part) away from the optical axis  4  as well as a part in a vicinity of the optical axis (optical axis part) close to the optical axis  4 . 
     Each lens element in the optical imaging lens set  1  of the present invention further has a central thickness T on the optical axis  4 . For example, the first lens element  10  has a first lens element thickness T 1 , the second lens element  20  has a second lens element thickness T 2 , the third lens element  30  has a third lens element thickness T 3 , the fourth lens element  40  has a fourth lens element thickness T 4 , the fifth lens element  50  has a fifth lens element thickness T 5 . Therefore, the total thickness of all the lens elements in the optical imaging lens set  1  along the optical axis  4  is ALT=T 1 +T 2 +T 3 +T 4 +T 5 . 
     In addition, between two adjacent lens elements in the optical imaging lens set  1  of the present invention there is an air gap along the optical axis  4 . For example, an air gap G 12  is disposed between the first lens element  10  and the second lens element  20 , an air gap G 23  is disposed between the second lens element  20  and the third lens element  30 , an air gap G 34  is disposed between the third lens element  30  and the fourth lens element  40 , as well as an air gap G 45  is disposed between the fourth lens element  40  and the fifth lens element  50 . Therefore, the sum of total five air gaps between adjacent lens elements from the first lens element  10  to the fifth lens element  50  along the optical axis  4  is AAG=G 12 +G 23 +G 34 +G 45 . 
     In addition, the distance between the first object-side surface  11  of the first lens element  10  and the image plane  71 , namely the total length of the optical imaging lens set  1 , along the optical axis  4  is TTL. EFL represents the effective focal length of the optical imaging lens set  1 . 
     Furthermore, the focal length of the first lens element  10  is f1; the focal length of the second lens element  20  is f2; the focal length of the third lens element  30  is f3; the focal length of the fourth lens element  40  is f4; the focal length of the fifth lens element  50  is f5; the refractive index of the first lens element  10  is n 1 ; the refractive index of the second lens element  20  is n 2 ; the refractive index of the third lens element  30  is n 3 ; the refractive index of the fourth lens element  40  is n 4 ; the refractive index of the fifth lens element  50  is n 5 ; the Abbe number of the first lens element  10  is υ1; the Abbe number of the second lens element  20  is υ2; the Abbe number of the third lens element  30  is υ3; and the Abbe number of the fourth lens element  40  is υ4; the Abbe number of the fifth lens element  50  is υ5. 
     FIRST EXAMPLE 
     Please refer to  FIG. 6  which illustrates the first example of the optical imaging lens set  1  of the present invention. Please refer to  FIG. 7A  for the longitudinal spherical aberration on the image plane  71  of the first example; please refer to  FIG. 7B  for the astigmatic field aberration on the sagittal direction; please refer to  FIG. 7C  for the astigmatic field aberration on the tangential direction, and please refer to  FIG. 7D  for the distortion aberration. The Y axis of the spherical aberration in each example is “field of view” for 1.0. The Y axis of the astigmatic field and the distortion in each example stands for “image height”, which is 2.62 mm. 
     The optical imaging lens set  1  of the first example has five lens elements  10  to  50  with refractive power. The optical imaging lens set  1  also has a filter  70 , an aperture stop  80 , and an image plane  71 . The aperture stop  80  is provided between the object side  2  and the first lens element  10 . The filter  70  may be used for preventing specific wavelength light (such as the infrared light) reaching the image plane to adversely affect the imaging quality. 
     The first lens element  10  has positive refractive power. The first object-side surface  11  facing toward the object side  2  has a convex part  13  in the vicinity of the optical axis and a convex part  14  in a vicinity of its circular periphery. The first image-side surface  12  facing toward the image side  3  has a concave part  16  in the vicinity of the optical axis and a concave part  17  in a vicinity of its circular periphery. Besides, both the first object-side surface  11  and the first image-side  12  of the first lens element  10  are aspherical surfaces. 
     The second lens element  20  is of a plastic material and has negative refractive power. The second object-side surface  21  facing toward the object side  2  has a convex part  23  in the vicinity of the optical axis and a convex part  24  in a vicinity of its circular periphery. The second image-side surface  22  facing toward the image side  3  has a concave part  26  in the vicinity of the optical axis and a concave part  27  in a vicinity of its circular periphery. Both the second object-side surface  21  and the second image-side  22  of the second lens element  20  are aspherical surfaces. 
     The third lens element  30  has positive refractive power. The third object-side surface  31  facing toward the object side  2  has a concave part  33  in the vicinity of the optical axis and a convex part  34  in a vicinity of its circular periphery. The third image-side surface  32  facing toward the image side  3  has a convex part  36  in the vicinity of the optical axis and a concave part  37  in a vicinity of its circular periphery. Both the third object-side surface  31  and the third image-side  32  of the third lens element  30  are aspherical surfaces. 
     The fourth lens element  40  has negative refractive power. The fourth object-side surface  41  facing toward the object side  2  has a concave part  43  in the vicinity of the optical axis and a concave part  44  in a vicinity of its circular periphery. The fourth image-side surface  42  facing toward the image side  3  has a concave part  46  in the vicinity of the optical axis and a convex part  47  in a vicinity of its circular periphery. Both the fourth object-side surface  41  and the fourth image-side  42  of the fourth lens element  40  are aspherical surfaces. 
     The fifth lens element  50  has positive refractive power. The fifth object-side surface  51  facing toward the object side  2  has a concave part  53  in the vicinity of the optical axis and a concave part  54  in a vicinity of its circular periphery. The fifth image-side surface  52  facing toward the image side  3  has a convex part  56  in the vicinity of the optical axis and a convex part  57  in a vicinity of its circular periphery. Both the fifth object-side surface  51  and the fifth image-side  52  of the fifth lens element  50  are aspherical surfaces. 
     In the first lens element  10 , the second lens element  20 , the third lens element  30 , the fourth lens element  40  and the fifth lens element  50  of the optical imaging lens element  1  of the present invention, there are 10 surfaces, such as the object-side surfaces  11 / 21 / 31 / 41 / 51  and the image-side surfaces  12 / 22 / 32 / 42 / 52 . If a surface is aspherical, these aspheric coefficients are defined according to the following formula: 
               Z   ⁡     (   Y   )       =           Y   2     R     /     (     1   +       1   -       (     1   +   K     )     ⁢       Y   2       R   2               )       +       ∑     i   =   1     n     ⁢       a   i     ×     Y   i                 
In which:
     R represents the curvature radius of the lens element surface;   Z represents the depth of an 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 a vertical distance from a point on the aspherical surface to the optical axis;   K is a conic constant;   a i  is the aspheric coefficient of the i th  order.   

     The optical data of the first example of the optical imaging lens set  1  are shown in  FIG. 24  while the aspheric surface data are shown in  FIG. 25 . In the present examples of the optical imaging lens set, the f-number of the entire optical lens element system is Fno, EFL is the effective focal length, HFOV stands for the half field of view which is half of the field of view of the entire optical lens element system, and the unit for the curvature radius, the thickness and the focal length is in millimeters (mm). TTL is 6.0187 mm. Fno is 2.6614. The image height is 2.62 mm. HFOV is 21.6855 degrees. 
     SECOND EXAMPLE 
     Please refer to  FIG. 8  which illustrates the second example of the optical imaging lens set  1  of the present invention. It is noted that from the second example to the following examples, in order to simplify the figures, only the components different from what the first example has, and the basic lens elements will be labeled in figures. Other components that are the same as what the first example has, such as the object-side surface, the image-side surface, the part in a vicinity of the optical axis and the part in a vicinity of its circular periphery will be omitted in the following examples. Please refer to  FIG. 9A  for the longitudinal spherical aberration on the image plane  71  of the second example, please refer to  FIG. 9B  for the astigmatic aberration on the sagittal direction, please refer to  FIG. 9C  for the astigmatic aberration on the tangential direction, and please refer to  FIG. 9D  for the distortion aberration. The components in the second example are similar to those in the first example, but the optical data such as the curvature radius, the refractive power, the lens thickness, the lens focal length, the aspheric surface or the back focal length in this example are different from the optical data in the first example, and in this example, the fifth object-side surface  51  has a convex part  53 ′ in the vicinity of the optical axis. 
     The optical data of the second example of the optical imaging lens set are shown in  FIG. 26  while the aspheric surface data are shown in  FIG. 27 . TTL is 6.1984 mm. Fno is 2.6014. The image height is 2.62 mm. HFOV is 21.5504 degrees. In particular, 1) the HFOV of the second example is smaller than that of the first example of the present invention. 
     THIRD EXAMPLE 
     Please refer to  FIG. 10  which illustrates the third example of the optical imaging lens set  1  of the present invention. Please refer to  FIG. 11A  for the longitudinal spherical aberration on the image plane  71  of the third example; please refer to  FIG. 11B  for the astigmatic aberration on the sagittal direction; please refer to  FIG. 11C  for the astigmatic aberration on the tangential direction, and please refer to  FIG. 11D  for the distortion aberration. The components in the third example are similar to those in the first example, but the optical data such as the curvature radius, the refractive power, the lens thickness, the lens focal length, the aspheric surface or the back focal length in this example are different from the optical data in the first example, and in this example, the fifth object-side surface  51  has a convex part  53 ′ in the vicinity of the optical axis. 
     The optical data of the third example of the optical imaging lens set are shown in  FIG. 28  while the aspheric surface data are shown in  FIG. 29 . TTL is 6.1287 mm. Fno is 2.6744. The image height is 2.62 mm. HFOV is 21.4292 degrees. In particular, 1) the HFOV of the third example is smaller than that of the first example of the present invention. 
     FOURTH EXAMPLE 
     Please refer to  FIG. 12  which illustrates the fourth example of the optical imaging lens set  1  of the present invention. Please refer to  FIG. 13A  for the longitudinal spherical aberration on the image plane  71  of the fourth example; please refer to  FIG. 13B  for the astigmatic aberration on the sagittal direction; please refer to  FIG. 13C  for the astigmatic aberration on the tangential direction, and please refer to  FIG. 13D  for the distortion aberration. The components in the fourth example are similar to those in the first example, but the optical data such as the curvature radius, the refractive power, the lens thickness, the lens focal length, the aspheric surface or the back focal length in this example are different from the optical data in the first example, and in this example, the fifth object-side surface  51  has a convex part  53 ′ in the vicinity of the optical axis. 
     The optical data of the fourth example of the optical imaging lens set are shown in  FIG. 30  while the aspheric surface data are shown in  FIG. 31 . TTL is 6.2344 mm. Fno is 2.6751. The image height is 2.62 mm. HFOV is 21.5813 degrees. In particular, 1) the HFOV of the fourth example is smaller than that of the first example of the present invention. 
     FIFTH EXAMPLE 
     Please refer to  FIG. 14  which illustrates the fifth example of the optical imaging lens set  1  of the present invention. Please refer to  FIG. 15A  for the longitudinal spherical aberration on the image plane  71  of the fifth example; please refer to  FIG. 15B  for the astigmatic aberration on the sagittal direction; please refer to  FIG. 15C  for the astigmatic aberration on the tangential direction, and please refer to  FIG. 15D  for the distortion aberration. The components in the fifth example are similar to those in the first example, but the optical data such as the curvature radius, the refractive power, the lens thickness, the lens focal length, the aspheric surface or the back focal length in this example are different from the optical data in the first example, and in this example, the fifth object-side surface  51  has a convex part  53 ′ in the vicinity of the optical axis. 
     The optical data of the fifth example of the optical imaging lens set are shown in  FIG. 32  while the aspheric surface data are shown in  FIG. 33 . TTL is 6.2285 mm. Fno is 2.6750. The image height is 2.62 mm. HFOV is 21.5801 degrees. In particular, 1) the Fno of the fifth example is larger than that of the first example of the present invention, 2) the HFOV of the fifth example is smaller than that of the first example. 
     SIXTH EXAMPLE 
     Please refer to  FIG. 16  which illustrates the sixth example of the optical imaging lens set  1  of the present invention. Please refer to  FIG. 17A  for the longitudinal spherical aberration on the image plane  71  of the sixth example; please refer to  FIG. 17B  for the astigmatic aberration on the sagittal direction; please refer to  FIG. 17C  for the astigmatic aberration on the tangential direction, and please refer to  FIG. 17D  for the distortion aberration. The components in the sixth example are similar to those in the first example, but the optical data such as the curvature radius, the refractive power, the lens thickness, the lens focal length, the aspheric surface or the back focal length in this example are different from the optical data in the first example, and in this example, the fifth object-side surface  51  has a convex part  53 ′ in the vicinity of the optical axis. 
     The optical data of the sixth example of the optical imaging lens set are shown in  FIG. 34  while the aspheric surface data are shown in  FIG. 35 . TTL is 6.1503 mm. Fno is 2.6030. The image height is 2.62 mm. HFOV is 21.7730 degrees. In particular, 1) the aperture stop of the sixth example is larger than that of the first example of the present invention. 
     SEVENTH EXAMPLE 
     Please refer to  FIG. 18  which illustrates the seventh example of the optical imaging lens set  1  of the present invention. Please refer to  FIG. 19A  for the longitudinal spherical aberration on the image plane  71  of the seventh example; please refer to  FIG. 19B  for the astigmatic aberration on the sagittal direction; please refer to  FIG. 19C  for the astigmatic aberration on the tangential direction, and please refer to  FIG. 19D  for the distortion aberration. The components in the seventh example are similar to those in the first example, but the optical data such as the curvature radius, the refractive power, the lens thickness, the lens focal length, the aspheric surface or the back focal length in this example are different from the optical data in the first example, and in this example, the fourth object-side surface  41  has a convex part  44 ′ in a vicinity of its circular periphery and the fourth image-side surface  42  has a convex part  46 ′ in the vicinity of the optical axis. 
     The optical data of the seventh example of the optical imaging lens set are shown in  FIG. 36  while the aspheric surface data are shown in  FIG. 37 . TTL is 6.3808 mm. Fno is 2.6051. The image height is 2.62 mm. HFOV is 22.0796 degrees. In particular, 1) the aperture stop of the sixth example is larger than that of the first example of the present invention. 
     EIGHTH EXAMPLE 
     Please refer to  FIG. 20  which illustrates the eighth example of the optical imaging lens set  1  of the present invention. Please refer to  FIG. 21A  for the longitudinal spherical aberration on the image plane  71  of the eighth example; please refer to  FIG. 21B  for the astigmatic aberration on the sagittal direction; please refer to  FIG. 21C  for the astigmatic aberration on the tangential direction, and please refer to  FIG. 21D  for the distortion aberration. The components in the eighth example are similar to those in the first example, but the optical data such as the curvature radius, the refractive power, the lens thickness, the lens focal length, the aspheric surface or the back focal length in this example are different from the optical data in the first example, and in this example, the fourth image-side surface  42  has a convex part  46 ′ in the vicinity of the optical axis. 
     The optical data of the eighth example of the optical imaging lens set are shown in  FIG. 38  while the aspheric surface data are shown in  FIG. 39 . TTL is 5.9812 mm. Fno is 2.5925. The image height is 2.62 mm. HFOV is 21.8230 degrees. In particular, 1) the TTL of the eighth example is shorter than that of the first example of the present invention, 2) the aperture stop of the eighth example is larger than that of the first example of the present invention. 
     NINTH EXAMPLE 
     Please refer to  FIG. 22  which illustrates the ninth example of the optical imaging lens set  1  of the present invention. Please refer to  FIG. 23A  for the longitudinal spherical aberration on the image plane  71  of the ninth example; please refer to  FIG. 23B  for the astigmatic aberration on the sagittal direction; please refer to  FIG. 23C  for the astigmatic aberration on the tangential direction, and please refer to  FIG. 23D  for the distortion aberration. The components in the ninth example are similar to those in the first example, but the optical data such as the curvature radius, the refractive power, the lens thickness, the lens focal length, the aspheric surface or the back focal length in this example are different from the optical data in the first example, and in this example, the fifth lens element  50  has negative refractive power and the fourth image-side surface  42  has a convex part  46 ′ in the vicinity of the optical axis. 
     The optical data of the ninth example of the optical imaging lens set are shown in  FIG. 40  while the aspheric surface data are shown in  FIG. 41 . TTL is 5.7772 mm. Fno is 2.5818. The image height is 2.62 mm. HFOV is 22.3974 degrees. In particular, 1) the TTL of the ninth example is shorter than that of the first example of the present invention, 2) the aperture stop of the ninth example is larger than that of the first example of the present invention. 
     Some important ratios in each example are shown in  FIG. 42 . The distance between the fifth image-side surface  52  of the fifth lens element  50  to the image plane  71  along the optical axis  4  is BFL; the air gap between the fifth lens element  50  and the filter  70  along the optical axis  4  is GSF; the thickness of the filter  70  along the optical axis  4  is TF; the distance between the filter  70  to the image plane  71  along the optical axis  4  is GFP. Therefore, BFL=G 5 F+TF+GFP. 
     In the light of the above examples, the inventors observe at least the following features:
     1. The present invention proposes finely designed vicinity of the optical axis of a lens element or finely designed vicinity of its periphery. The first lens element has an image-side surface with a concave portion in a vicinity of its periphery to recover light of larger angle.   2. The third lens element has an object-side surface with a concave portion in a vicinity of the optical-axis and an image-side surface with a concave portion in a vicinity of its periphery to concentrate light effectively.   3. The fourth lens element has an object-side surface with a concave portion in a vicinity of the optical-axis to synergistically correct the aberration.   4. The fifth lens element has an object-side surface with a concave portion in a vicinity of its periphery and an image-side surface with a convex portion in a vicinity of the optical-axis to synergistically decrease the length of the optical imaging lens set and to ensure good imaging quality.   

     In addition, the inventors discover that there are some better ratio ranges for different data according to the above various important ratios. Better ratio ranges help the designers to design a better optical performance and practically possible optical imaging lens set. For example:
     1. Any one of the following conditions shows a smaller numerator when the denominator is fixed to exhibit the decrease of the total size:
 
TTL/ T   2 ≤22.80;
 
ALT/ T   4 ≤8.60;
 
TTL/( G   23   +G   45 )≤8.50;
 
EFL/( G   12   +G   23 )≤12.70;
 
TTL/( T   4   +T   5 )≤6.50;
 
EFL/( G   23   +G   4 )≤8.6;
 
( T   1   +T   4 )/ T   2 ≤4.50;
 
EFL/( G   12   +G   23   +G   45 )≤10.50;
 
EFL/ T   5 ≤11.80;
 
EFL/ G   34 ≤12.50.
   

     When the following conditions are further met, better imaging quality is possible:
 
10.50≤TTL/ T   2 ≤22.80;
 
4.20≤TTL/( G   23   +G   45 )≤8.50;
 
2.80≤( T   1   +T   4 )/ T   2 ≤4.50;
 
8.50≤EFL/ T   5 ≤11.80;
 
3.70≤EFL/ G   34 ≤12.50.
 
     When one of the following conditions is met, it shows better arrangements to provide better imaging quality when good yield is maintained:
 
5.50≤ALT/( G   12   +G   45 );
 
6.50≤ALT/ T   2 ;
 
4.20≤TTL/( G   12   +G   23   +G   45 );
 
4.20≤ALT/( T   2   +T   3 );
 
1.3≤ALT/ G   34 ;
 
4.00≤TTL/( T   1   +T   2 );
 
3.20≤TTL/( G   12   +G   34 );
 
9.50≤EFL/( T   2   +T   4 ).
 
     When any one of the following conditions is further met, it additionally keeps a suitable size:
 
5.50≤ALT/( G   12   +G   45 )≤22.90;
 
6.50≤ALT/ T   2 ≤9.50;
 
4.20≤TTL/( G   12   +G   23   +G   45 )≤8.0;
 
4.20≤ALT/( T   2   +T   3 )≤4.60;
 
1.3≤ALT/ G   34 ≤1.90 ;
 
4.00≤TTL/( T   1   +T   2 )≤5.80;
 
3.20≤TTL/( G   12   +G   34 )≤4.30;
 
9.50≤EFL/( T   2   +T   4 )≤11.50.
 
     When any one of the following conditions is further met, it helps reduce the total length of the optical imaging lens set without overly compromising the telescopic function.
 
TTL/ T   2 ≤22.8;
 
ALT/ T   4 ≤8.60;
 
TTL/( G   23   +G   45 )≤8.50;
 
TTL/( T   4   +T   5 )≤6.50;
 
( T   1   +T   4 )/T 2 ≤4.50.
 
     It is preferably:
 
10.50≤TTL/ T   2 ≤22.8;
 
5.60≤ALT/ T   4 ≤8.60;
 
4.20≤TTL/( G   23   +G   45 )≤8.50;
 
5.30≤TTL/( T   4   +T   5 )≤6.50;
 
2.80≤( T   1   +T 4) /T 2 ≤4.50;
 
to overly increase the total length of the optical imaging lens set when the telescopic function is overly enhanced.
 
     With respect to:
 
EFL/( G   12   +G   23 )≤12.70;
 
EFL/( G   23   +G   45 )≤8.60;
 
EFL/( G   12   +G   23   +G   45 )≤10.50;
 
EFL/ T   5 ≤11.80;
 
EFL/ G   34 ≤12.50;
 
by limiting the relationship amongst EFL, the length thickness and the air gaps, it helps enhance the telescopic function without compromising the imaging quality. It is preferably:
 
5.80≤EFL/( G   12   +G   23 )≤12.70;
 
4.60≤EFL/( G   23   +G   45 )≤8.60;
 
4.50≤EFL/( G   12   +G   23   +G   45 )≤10.50;
 
8.5≤EFL/ T   5 ≤11.80;
 
3.70≤EFL/ G   34 ≤12.50,
 
in order to keep each thickness of the lens element and each air gap in preferred ranges. A good ratio helps to control the lens thickness or the air gaps to maintain a suitable range and keeps a lens element from being too thick to facilitate the reduction of the overall size or too thin to assemble the optical imaging lens set.
 
     With respect to:
 
5.5≤ALT/( G   12   +G   45 );
 
6.5≤ALT/ T   2 ;
 
4.2≤TTL/( G   12   +G   23   +G   45 );
 
4.2≤ALT/( T   2   +T   3 );
 
1.3≤ALT/ G   34 ;
 
4.0≤TTL/( T   1   +T   2 );
 
3.20≤TTL/( G   12   +G   34 );
 
9.50≤EFL/( T   2   +T   4 );
 
it is preferably:
 
5.5≤ALT/( G   12   +G   45 )≤22.90;
 
6.5≤ALT/ T   2 ≤9.50;
 
4.2≤TTL/( G   12   +G   23   +G   45 )≤8.0;
 
4.2≤ALT/( T   2   +T   3 )≤4.60;
 
1.3≤ALT/ G   34 ≤1.90;
 
4.0≤TTL/( T   1   +T   2 )≤5.80;
 
3.20≤TTL/( G   12   +G   34 )≤4.30;
 
9.50≤EFL/( T   2   +T   4 )≤11.50
 
in order to keep each thickness of the lens element and each air gap in preferred ranges, good ratio helps to control the lens thickness or the air gaps to maintain a suitable range and keeps a lens element from being too thick to facilitate the reduction of the overall size or too thin to assemble the optical imaging lens set.
 
     The above limitations may be properly combined at the discretion of persons who practice the present invention and they are not limited as shown above. In the light of the unpredictability of the optical imaging lens set, the present invention suggests the above principles to appropriately reduce the length of the lens element set, to have better F number, to have better imaging quality or to have better assembling yield to overcome the shortcomings of prior art. 
     The above-mentioned one or more conditions may be properly combined in the embodiments. In addition to the above ratios, the curvatures of each lens element or multiple lens elements may be fine-tuned to result in more fine structures to enhance the performance or the resolution. For example, the first object-side surface  11  of the first lens element  10  may additionally have a convex part in the vicinity of the optical axis. The above limitations may be properly combined in the embodiments without causing inconsistency. 
     In each one of the above examples, the longitudinal spherical aberration, the astigmatic aberration and the distortion aberration meet requirements in use. By observing three representative wavelengths of red, green and blue, it is suggested that all curves of every wavelength are close to one another, which reveals off-axis light of different heights of every wavelength all concentrates on the image plane, and deviations of every curve also reveal that off-axis light of different heights are well controlled so the examples do improve the spherical aberration, the astigmatic aberration and the distortion aberration. In addition, by observing the imaging quality data the distances amongst the three representing different wavelengths are pretty close to one another, which means the present invention is able to concentrate light of the three representing different wavelengths so that the aberration is greatly improved. Given the above, the present invention provides outstanding imaging quality by the above designs of each lens element as well as the excellent synergies gained from the combinations of lens elements. 
     Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.