Optical imaging system

Abstract

An optical imaging system is provided, which includes a first lens, a second lens, a third lens, a fourth lens, and a fifth lens. The first lens has a positive refractive power and an image-side surface which is convex. The second lens has a positive refractive power, and the third lens has a negative refractive power. The fourth lens has a positive refractive power, and the fifth lens has a positive refractive power. The first lens to the fifth lens are sequentially arranged from an object side toward an imaging plane.

Description

[0001] This application is a divisional application of the invention patent application "Optical Imaging System" filed on April 15, 2016, with application number 202110022860.5. Technical Field

[0002] The following description relates to an optical imaging system for photographing objects in both the visible and near-infrared regions. Background Technology

[0003] Surveillance cameras are installed in vehicles to capture the vehicle's forward and rearward views. For example, a surveillance camera is installed in the vehicle's rearview mirror to capture moving vehicles, pedestrians, and other objects in front of the vehicle.

[0004] Surveillance cameras operate both day and night. However, due to low illumination at night, it is difficult to capture clear images of objects or people. Specifically, because surveillance cameras mounted on vehicles are ideally small, an optical imaging system capable of capturing objects in the visible and near-infrared regions is required, even at a small size. Summary of the Invention

[0005] This summary is provided to introduce, in a simplified form, the inventive concept further described in the detailed embodiments below. This summary is not intended to identify key or essential technical features of the claimed subject matter, nor is it intended to help determine the scope of the claimed subject matter.

[0006] According to an embodiment, an optical imaging system is provided, the optical imaging system comprising: a first lens having positive refractive power and a convex image-side surface; a second lens having positive refractive power; a third lens having negative refractive power; a fourth lens having positive refractive power; and a fifth lens having positive refractive power, wherein the first lens to the fifth lens are arranged sequentially from the object side toward the imaging surface.

[0007] The image surface of the second lens may be concave.

[0008] The object-side surface of the fourth lens may be concave.

[0009] The object-side surface and image-side surface of the fifth lens may be convex.

[0010] The optical imaging system also includes an aperture stop disposed between the second lens and the third lens.

[0011] One or more of the first to fifth lenses may have a spherical shape.

[0012] One or more of the first to fifth lenses may be made of glass.

[0013] The optical imaging system can satisfy -6.5<{(1 / f)*(Y / tanθ)-1}*100<-1.0, where f is the total focal length of the optical imaging system, Y is 1 / 2 of the diagonal length of the imaging plane, and θ is the half field of view angle of the optical imaging system.

[0014] The optical imaging system can satisfy TL / 2Y<2.0, where TL is the distance from the object-side surface of the first lens to the imaging plane, and 2Y is the diagonal length of the imaging plane.

[0015] The optical imaging system can satisfy -7.0<R1 / f<5.0, where f is the total focal length of the optical imaging system, and R1 is the radius of curvature of the object-side surface of the first lens.

[0016] The optical imaging system can satisfy -5.5<(R1+R2) / (R1-R2)<5.5, where R1 is the radius of curvature of the object-side surface of the first lens, and R2 is the radius of curvature of the image-side surface of the first lens.

[0017] The optical imaging system can satisfy 0.2<f / f1<0.6, where f is the total focal length of the optical imaging system, and f1 is the focal length of the first lens.

[0018] The optical imaging system can satisfy -2.5<f / f3<-1.5, where f is the total focal length of the optical imaging system, and f3 is the focal length of the third lens.

[0019] The optical imaging system can satisfy 5.0<(t1+t2) / t3<12.0, where t1 is the central thickness of the first lens on the optical axis, t2 is the central thickness of the second lens on the optical axis, and t3 is the central thickness of the third lens on the optical axis.

[0020] The optical imaging system can satisfy 0≤|n1-n2|≤0.20, where n1 is the refractive index of the first lens, and n2 is the refractive index of the second lens.

[0021] According to another embodiment, an optical imaging system is provided, the optical imaging system comprising: a first lens; a second lens; a third lens having a concave object-side surface and a concave image-side surface; a fourth lens; a fifth lens having a convex object-side surface and a convex image-side surface, wherein the first lens to the fifth lens are sequentially arranged from the object side toward the imaging plane.

[0022] According to another embodiment, an optical imaging system is provided, the optical imaging system comprising: a first lens; a second lens having a convex object-side surface; a third lens having a concave object-side surface and a concave image-side surface; a fourth lens; and a fifth lens having a convex object-side surface, wherein the second lens and the third lens have a refractive index greater than that of the first lens, and the fourth lens and the fifth lens have a refractive index less than that of the third lens.

[0023] The first lens may have positive refractive power, the second lens may have positive refractive power, the third lens may have negative refractive power, the fourth lens may have positive refractive power, and the fifth lens may have positive refractive power.

[0024] The Abbe number of the third lens may be lower than that of the first lens.

[0025] The Abbe number of the fourth lens and the Abbe number of the fifth lens are greater than the Abbe number of the third lens.

[0026] Other features and aspects will become apparent from the following detailed description, drawings, and claims. Attached Figure Description

[0027] These and / or other aspects will become clearer and more readily apparent from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0028] Figure 1 This is a diagram of an optical imaging system according to the first embodiment;

[0029] Figure 2 It represents Figure 1 The graph shows the aberration curves of the optical imaging system.

[0030] Figure 3 It represents Figure 1 The table shows the characteristics of the lenses in the optical imaging system;

[0031] Figure 4 This is a diagram of an optical imaging system according to the second embodiment;

[0032] Figure 5 It represents Figure 4 The graph shows the aberration curves of the optical imaging system.

[0033] Figure 6 It represents Figure 4 The table shows the characteristics of the lenses in the optical imaging system;

[0034] Figure 7 This is a diagram of an optical imaging system according to a third embodiment;

[0035] Figure 8 It represents Figure 7 The graph shows the aberration curves of the optical imaging system.

[0036] Figure 9 It represents Figure 7 The table shows the characteristics of the lenses in the optical imaging system.

[0037] In all the accompanying drawings and detailed embodiments, unless otherwise described, the same reference numerals will be understood to indicate the same elements, features, and structures. For clarity, illustration, and brevity, the relative dimensions and depictions of these elements may be enlarged. Detailed Implementation

[0038] The following detailed embodiments are provided to help the reader gain a full understanding of the methods, apparatus, and / or systems described herein. However, various modifications, alterations, and equivalents of the methods, apparatus, and / or systems described herein will be apparent to those skilled in the art. For example, the sequence of operations described herein is merely an example and is not limited to the sequence set forth herein; rather, variations that will be apparent to those skilled in the art can be made, except for operations that must occur in a specific order. Furthermore, for clarity and brevity, descriptions of functions and structures well-known to those skilled in the art may be omitted.

[0039] Throughout the accompanying drawings and detailed embodiments, the same reference numerals denote the same elements. The drawings may not be to scale; for clarity, illustration, and convenience, relative dimensions, scales, and depictions in the drawings may be enlarged.

[0040] The features described herein may be implemented in various forms and shall not be construed as being limited to the examples described herein. Rather, the examples described herein have been provided so that this disclosure will be thorough and complete, and will convey the full scope of this disclosure to those skilled in the art.

[0041] Throughout this specification, it will be understood that when an element (such as a layer, region, or wafer (substrate)) is referred to as being "on" another element, "connected" to another element, or "bonded" to another element, it may be directly "on" another element, "connected" to another element, or "bonded" to another element, or there may be other elements in between. Conversely, when an element is referred to as being "directly on" another element, "directly connected" to another element, or "directly bonded" to another element, there are no elements or layers in between. The same reference numerals always indicate the same element. As used herein, the term "and / or" includes any and all combinations of one or more of the related items listed.

[0042] It will be understood that although terms such as "first," "second," and "third" may be used herein to describe various lenses, these lenses should not be limited by these terms. These terms are merely used to distinguish one lens from another. These terms do not necessarily imply a specific order or arrangement of the lenses. Therefore, without departing from the teachings of the various embodiments, the first lens discussed below may be described as a second lens.

[0043] Spatial relation terms such as “above,” “upper,” “below,” and “lower” may be used herein to readily describe the relationship of one element to other elements, as shown in the accompanying drawings. It will be understood that spatial relation terms are intended to encompass different orientations of the device in use or operation, in addition to those depicted in the drawings. For example, if the device in the drawings is flipped, an element described as “above” or “on” other elements will subsequently be positioned “below” or “below” other elements or features. Thus, the term “above” may include both “above” and “below” orientations depending on the specific orientation of the drawings. The device may be otherwise positioned (rotated 90 degrees or in other orientations), and the spatial relation descriptors used herein may be interpreted accordingly.

[0044] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the inventive concept. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. It will also be understood that the terms “comprising” and / or “consisting of” as used in this specification enumerate the stated features, integers, steps, operations, components, elements, and / or groups thereof, but do not exclude the presence or addition of one or more other features, integers, steps, operations, components, elements, and / or groups thereof.

[0045] In the following description, various embodiments will be illustrated with reference to schematic diagrams showing examples. In the drawings, for example, deformations of the illustrated shapes may be estimated due to manufacturing techniques and / or tolerances. Therefore, the embodiments should not be construed as being limited to a specific shape in the area shown herein, including, for example, changes in shape due to manufacturing processes. The following embodiments may also be constituted by one or a combination thereof.

[0046] Furthermore, according to the embodiment, the first lens is the lens closest to the object or subject used to capture the image. The fifth lens is the lens closest to the imaging surface or image sensor. Additionally, the radius of curvature, TL, Y (half the length of the imaging surface diagonal), and focal length of the lens are all expressed in millimeters (mm). Furthermore, the thickness of the lens, the spacing between the lenses, and TL are distances measured relative to the optical axis of the lens.

[0047] Those skilled in the art will appreciate that other units of measurement may be used. Furthermore, in this specification, the total radius of curvature of the lens, thickness, OAL (optical distance from the first surface of the first lens to the image sensor), distance on the optical axis between the aperture and the image sensor (SL), image height (IMGH), back focus length (BFL), total focal length of the optical system, and focal length of each lens are expressed in millimeters (mm). Moreover, the lens thickness, inter-lens spacing, OAL, and SL are all measured based on the optical axis of the lens.

[0048] Furthermore, regarding the shape of a lens, these shapes are described in relation to the optical axis of the lens. A convex surface of a lens means that the optical axis portion of the corresponding surface is convex, and a concave surface means that the optical axis portion of the corresponding surface is concave. Therefore, in a lens construction where one surface is described as convex, the edge portion of the lens may be concave. Similarly, in a lens construction where one surface is described as concave, the edge portion of the lens may be convex. In other words, the paraxial region of the lens may be convex, while the remaining portion of the lens outside the paraxial region may be convex, concave, or flat. Furthermore, the paraxial region of the lens may be concave, while the remaining portion of the lens outside the paraxial region may be convex, concave, or flat.

[0049] An optical imaging system has an optical system comprising multiple lenses. For example, the optical system of an optical imaging system includes five lenses having refractive powers. Without departing from the scope of the embodiments described herein, a lens module may include four to five lenses. According to the example shown, the embodiment of the optical system described includes five lenses having refractive powers. However, those skilled in the art will appreciate that the number of lenses in the optical system can be varied, for example, between two and five lenses, to obtain the various results and effects described below. Furthermore, although each lens is described as having a specific refractive power, at least one lens with different refractive powers can be used to obtain the desired results.

[0050] Furthermore, optical imaging systems are not limited to including only lenses with refractive power. For example, an optical imaging system may include an aperture to control the amount of light. Additionally, an optical imaging system may include an image sensor (i.e., an imaging device) that converts an image of an object incident upon it through the optical system into an electrical signal. Furthermore, an optical imaging system may include a spacing maintenance member that adjusts the distance between the lenses.

[0051] The first through fifth lenses can be formed of a material having a refractive index different from that of air. For example, the first through fifth lenses can be formed of plastic, glass, or polyurethane.

[0052] An optical imaging system may include five lenses, an image sensor, and an aperture. These components will then be described.

[0053] The first lens has refractive power. For example, the first lens has positive refractive power.

[0054] One surface of the first lens is convex. For example, the image-side surface of the first lens is convex.

[0055] The first lens has a spherical surface. For example, both surfaces of the first lens are spherical. The first lens is formed of a material with high light transmittance and good processability. For example, the first lens is formed of glass. However, the material of the first lens is not limited to glass. For example, the first lens is formed of plastic or polyurethane material.

[0056] The first lens has a predetermined refractive index. For example, the refractive index of the first lens is 1.70 or greater.

[0057] The second lens has refractive power. For example, the second lens has positive refractive power.

[0058] One surface of the second lens is concave. For example, the image-side surface of the second lens is concave.

[0059] The second lens has a spherical surface. For example, both surfaces of the second lens are spherical. The second lens is formed of a material with high light transmittance and good processability. For example, the second lens is formed of glass. However, the material of the second lens is not limited to glass. For example, the second lens can also be formed of plastic or polyurethane material.

[0060] The second lens has a higher refractive index than the first lens. For example, the refractive index of the second lens is 1.90 or greater.

[0061] The third lens has refractive power. For example, the third lens has negative refractive power.

[0062] At least one surface of the third lens is concave. For example, both surfaces of the third lens are concave. In one example, the object-side surface of the third lens is concave in the paraxial region and gradually flattens out at its edges. In another example, the image-side surface of the third lens is concave in the paraxial region.

[0063] The third lens has a spherical surface. For example, both surfaces of the third lens are spherical. The third lens is formed of a material with high light transmittance and good machinability. For example, the third lens is formed of glass. However, the material of the third lens is not limited to glass. For example, the third lens is formed of plastic or polyurethane material.

[0064] The third lens has a higher refractive index than the first lens. For example, the refractive index of the third lens is 1.90 or greater. The third lens has a lower Abbe number than the first lens. For example, the Abbe number of the third lens is 25 or lower.

[0065] The fourth lens has refractive power. For example, the fourth lens has positive refractive power.

[0066] One surface of the fourth lens is concave. For example, the object-side surface of the fourth lens is concave.

[0067] The fourth lens has a spherical surface. For example, both surfaces of the fourth lens are spherical. The fourth lens is formed of a material with high light transmittance and good machinability. For example, the fourth lens is formed of glass. However, the material of the fourth lens is not limited to glass. For example, the fourth lens may be formed of plastic or polyurethane material.

[0068] The fourth lens has a lower refractive index than the third lens. For example, the refractive index of the fourth lens is 1.90 or less. The fourth lens has a higher Abbe number than the third lens. For example, the Abbe number of the fourth lens is 40 or greater.

[0069] The fifth lens has refractive power. For example, the fifth lens has positive refractive power.

[0070] At least one surface of the fifth lens is convex. For example, both surfaces of the fifth lens are convex.

[0071] The fifth lens has a spherical surface. For example, both surfaces of the fifth lens are spherical. The fifth lens is formed of a material with high light transmittance and good machinability. For example, the fifth lens is formed of glass. However, the material of the fifth lens is not limited to glass. For example, the fifth lens can be formed of plastic or polyurethane material.

[0072] The fifth lens has a lower refractive index than the third lens. For example, the refractive index of the fifth lens is less than 1.90. The fifth lens has a higher Abbe number than the third lens. For example, the Abbe number of the fifth lens is 40 or greater.

[0073] Those skilled in the art will appreciate that each of the first through fifth lenses can be configured with a refractive power opposite to that described above. For example, in an alternative configuration, the first lens has negative refractive power, the second lens has negative refractive power, the third lens has positive refractive power, the fourth lens has negative refractive power, and the fifth lens has negative refractive power.

[0074] Image sensors are constructed to achieve high resolution. For example, the unit size of pixels in an image sensor can be 1.12 μm or smaller. The imaging surface on which the image is formed is formed on the surface of the image sensor.

[0075] An aperture stop is positioned between lenses. For example, the aperture stop is positioned between the second lens and the third lens. The aperture stop, as described above, adjusts the amount of light incident on the image sensor.

[0076] The optical imaging system satisfies the following conditional expressions 1 to 9:

[0077] [Conditional expression 1] -6.5 < {(1 / f)*(Y / tanθ)-1}*100 < -1.0

[0078] [Conditional expression 2] TL / 2Y < 2.0

[0079] [Conditional Expression 3]-7.0 <R1 / f<5.0

[0080] [Conditional Expression 4] -5.5 < (R1 + R2) / (R1 - R2) < 5.5

[0081] [Conditional expression 5] 0.2 <f / f1<0.6

[0082] [Conditional Expression 6]-2.5 <f / f3<-1.5

[0083] [Conditional Expression 7] 1.5 <f / EPD<2.1

[0084] [Conditional Expression 8] 5.0 < (t1 + t2) / t3 < 12.0

[0085] [Conditional expression 9] 0 ≤ |n1 - n2| ≤ 0.20

[0086] In the example, f is the total focal length of the optical imaging system, 2Y is the diagonal length of the imaging plane, Y is 1 / 2 of 2Y, θ is the half field of view of the optical imaging system, TL is the distance from the object surface of the first lens to the imaging plane, R1 is the radius of curvature of the object surface of the first lens, R2 is the radius of curvature of the image surface of the first lens, f1 is the focal length of the first lens, f3 is the focal length of the third lens, EPD is the entrance pupil diameter (EPD), t1 is the center thickness of the first lens on the optical axis, t2 is the center thickness of the second lens on the optical axis, t3 is the center thickness of the third lens on the optical axis, n1 is the refractive index of the first lens, and n2 is the refractive index of the second lens.

[0087] Optical imaging systems that satisfy conditional expressions 1 to 9 can be miniaturized and achieve high resolution.

[0088] In addition, an optical imaging system according to several embodiments will be described.

[0089] First, refer to Figure 1 An optical imaging system according to a first embodiment is described.

[0090] The optical imaging system 100 according to the first embodiment includes a plurality of lenses having refractive power. For example, the optical imaging system 100 includes a first lens 110, a second lens 120, a third lens 130, a fourth lens 140, and a fifth lens 150.

[0091] In this embodiment, the first lens 110 has positive refractive power, its object-side surface is concave, and its image-side surface is convex. The second lens 120 has positive refractive power, its object-side surface is convex, and its image-side surface is concave. The third lens 130 has negative refractive power, and both of its surfaces are concave. The fourth lens 140 has positive refractive power, its object-side surface is concave, and its image-side surface is convex. The fifth lens 150 has positive refractive power, and both of its surfaces are convex. An aperture stop ST is disposed between the second and third lenses.

[0092] The optical system 100 includes components that form an imaging surface. For example, the optical imaging system includes an image sensor 160.

[0093] The optical imaging system constructed as described above can exhibit Figure 2 The aberration characteristics are shown in the figure. Figure 3 This is a table representing the characteristics of the lens of the optical imaging system according to the first embodiment.

[0094] Reference Figure 4 An optical imaging system according to a second embodiment is described.

[0095] The optical imaging system 200 according to the second embodiment includes a plurality of lenses having refractive power. For example, the optical imaging system 200 includes a first lens 210, a second lens 220, a third lens 230, a fourth lens 240, and a fifth lens 250.

[0096] In this embodiment, the first lens 210 has positive refractive power, with a concave object-side surface and a convex image-side surface. The second lens 220 has positive refractive power, with a convex object-side surface and a concave image-side surface. The third lens 230 has negative refractive power, with both of its surfaces being concave. The fourth lens 240 has positive refractive power, with a concave object-side surface and a convex image-side surface. The fifth lens 250 has positive refractive power, with both of its surfaces being convex. An aperture stop ST is positioned between the second and third lenses.

[0097] Optical system 200 includes components that form an imaging surface. For example, an optical imaging system includes an image sensor 260.

[0098] The optical imaging system constructed as described above can exhibit Figure 5 The aberration characteristics are shown in the figure. Figure 6This is a table representing the characteristics of the lens of the optical imaging system according to the second embodiment.

[0099] Reference Figure 7 An optical imaging system according to a third embodiment is described.

[0100] The optical imaging system 300 according to the third embodiment includes a plurality of lenses having refractive power. For example, the optical imaging system 300 includes a first lens 310, a second lens 320, a third lens 330, a fourth lens 340, and a fifth lens 350.

[0101] In this embodiment, the first lens 310 has positive refractive power, and both of its surfaces are convex. The second lens 320 has positive refractive power, with its object-side surface being convex and its image-side surface being concave. The third lens 330 has negative refractive power, and both of its surfaces are concave. The fourth lens 340 has positive refractive power, with its object-side surface being concave and its image-side surface being convex. The fifth lens 350 has positive refractive power, and both of its surfaces are convex. An aperture stop ST is disposed between the second and third lenses.

[0102] The optical system 300 includes components that form an imaging surface. For example, the optical imaging system includes an image sensor 360.

[0103] The optical imaging system constructed as described above can exhibit Figure 8 The aberration characteristics are shown in the figure. Figure 9 This is a table representing the characteristics of the lens of the optical imaging system according to the third embodiment.

[0104] Table 1 shows the optical characteristics of the optical imaging systems according to the first to third embodiments. The total focal length (f) of the optical imaging system is determined to be in the range of 5.9 mm to 6.4 mm. In the optical imaging system, the focal length (f1) of the first lens is determined to be in the range of 12.0 mm to 26.0 mm. In the optical imaging system, the focal length (f2) of the second lens is determined to be in the range of 11.0 mm to 31.0 mm. In the optical imaging system, the focal length (f3) of the third lens is determined to be in the range of -3.3 mm to -2.0 mm. In the optical imaging system, the focal length (f4) of the fourth lens is determined to be in the range of 5.0 mm to 6.0 mm. In the optical imaging system, the focal length (f5) of the fifth lens is determined to be in the range of 6.0 mm to 10.0 mm. In the optical imaging system, the TL is determined to be in the range of 9.0 mm to 12.0 mm. The F-number of the optical imaging system is 1.9 or less. In the optical imaging system, the EPD was determined to be in the range of 3.2 mm to 3.4 mm. The full field of view (2θ) of the optical imaging system was determined to be in the range of 52° to 57°.

[0105] [Table 1]

[0106] f 6.10000 6.10000 6.20000 f1 16.5581 24.1354 13.1064 f2 15.3627 12.9068 29.2263 f3 -3.10482 -3.09389 -3.13969 f4 5.14407 5.12337 5.16263 f5 8.66335 7.80889 7.36402 TL 11.4500 11.0150 10.1050 F number 1.88000 1.85000 1.87000 EPD 3.24400 3.29700 3.31500 2θ 53.9000 55.5000 54.0200 Y 3.00000 3.10000 3.10000

[0107] Table 2 shows the values ​​of the conditional expressions for the optical imaging systems according to the first to third embodiments. As shown in Table 2, the optical imaging systems according to the first to third embodiments satisfy the entire range of values ​​for the above conditional expressions.

[0108] [Table 2]

[0109] ((1 / f)*(Y / tanθ)-1)*100 -3.26958 -3.40769 -1.91180 TL / 2Y 1.90833 1.77661 1.62984 R1 / f -5.29262 -3.33410 2.56855 (R1+R2) / (R1-R2) 1.95542 2.88019 -0.23175 f / f1 0.36840 0.25274 0.47305 f / f3 -1.96469 -1.97163 -1.97472 f / EPD 1.88039 1.85017 1.87029 (t1+t2) / t3 6.71429 9.60000 7.69600 |n1-n2| 0.01900 0.16700 0.16700

[0110] Because the optical imaging system constructed as described above has an F-number of 1.9 or less, it enables clear imaging of objects in the visible and near-infrared regions, as well as in low-light environments. Furthermore, because a spherical lens is used in the optical imaging system according to the embodiment, the cost required to manufacture the optical imaging system is reduced. Moreover, the optical imaging system according to the embodiment ensures a predetermined resolution in temperature environments ranging from -40°C to 80°C. Therefore, the optical system according to the embodiment achieves high resolution even in environments with large temperature variations, such as inside a vehicle.

[0111] As described above, the optical system according to the embodiment can clearly photograph objects even in low-light environments.

[0112] While this disclosure includes specific examples, those skilled in the art will appreciate that various changes in form and detail may be made in these embodiments without departing from the spirit and scope of the claims and their equivalents. The examples described herein are to be understood merely for descriptive purposes and not for limiting purposes. The description of features or aspects in each example is to be understood as applicable to similar features or aspects in other examples. Suitable results may be obtained if the described techniques are performed in a different order, and / or if components in the described system, architecture, apparatus, or circuit are combined in different forms and / or replaced or added by other components or their equivalents. Therefore, the scope of this disclosure is not limited by specific embodiments but by the claims and their equivalents, and all modifications within the scope of the claims and their equivalents are to be understood as included in this disclosure.

Claims

1. An optical imaging system, comprising: a first lens having positive refractive power; a second lens having positive refractive power; a third lens having negative refractive power; a fourth lens having positive refractive power; a fifth lens having positive refractive power, wherein the first lens to the fifth lens are sequentially arranged from an object side toward an imaging surface, wherein the optical imaging system comprises a total of five lenses with refractive power, wherein the optical imaging system satisfies 5.9mm < f < 6.4mm, where f is a focal length of the optical imaging system, wherein 11.0mm < f2 < 31.0mm, f2 is a focal length of the second lens, and wherein the optical imaging system satisfies -5.5 < (R1+R2) / (R1-R2) < 5.5, where R1 is a curvature radius of an object-side surface of the first lens, and R2 is a curvature radius of an image-side surface of the first lens.

2. The optical imaging system according to claim 1, wherein, The optical imaging system satisfies -7.0 < R1 / f < 5.0, where R1 is the curvature radius of the object-side surface of the first lens.

3. The optical imaging system according to claim 1, wherein, The optical imaging system satisfies 0.2 < f / f1 < 0.6, where f1 is a focal length of the first lens.

4. The optical imaging system according to claim 1, wherein, The optical imaging system satisfies -2.5 < f / f3 < -1.5, where f3 is a focal length of the third lens.

5. The optical imaging system according to claim 1, wherein, The optical imaging system satisfies 5.0 < (t1+t2) / t3 < 12.0, where t1 is a central thickness of the first lens on an optical axis, t2 is a central thickness of the second lens on the optical axis, and t3 is a central thickness of the third lens on the optical axis.

6. The optical imaging system according to claim 1, wherein, The optical imaging system satisfies 0 ≤ |n1-n2| ≤ 0.20, where n1 is a refractive index of the first lens, and n2 is a refractive index of the second lens.

7. An optical imaging system, comprising: a first lens having positive refractive power; a second lens having positive refractive power; a third lens having a concave object-side surface and a concave image-side surface; a fourth lens having positive refractive power; a fifth lens having positive refractive power, wherein the first lens to the fifth lens are sequentially arranged from the object side toward the imaging surface, wherein the optical imaging system comprises a total of five lenses with refractive power, wherein the optical imaging system satisfies 5.9mm < f < 6.4mm, f is the focal length of the optical imaging system, and wherein 5.0mm < f4 < 6.0mm, f4 is a focal length of the fourth lens, wherein the optical imaging system satisfies -5.5 < (R1+R2) / (R1-R2) < 5.5, where R1 is the curvature radius of the object-side surface of the first lens, and R2 is the curvature radius of the image-side surface of the first lens.

8. The optical imaging system according to claim 7, wherein, The first lens has a convex image-side surface.

9. The optical imaging system according to claim 7, wherein, The second lens has a convex object-side surface.

10. The optical imaging system according to claim 7, wherein, The fourth lens has a concave object-side surface.

11. The optical imaging system according to claim 7, wherein, The fourth lens has a convex image-side surface.

12. The optical imaging system according to claim 7, wherein, The fifth lens has a convex object-side surface.

13. The optical imaging system according to claim 7, wherein, The fifth lens has a convex image-side surface.

14. An optical imaging system, comprising: a first lens, having positive refractive power; a second lens, having positive refractive power; a third lens, having negative refractive power; a fourth lens, having positive refractive power; a fifth lens, having positive refractive power, wherein the first lens to the fifth lens are arranged in order from the object side toward the image plane, wherein the optical imaging system includes a total of five lenses with refractive power, wherein the optical imaging system satisfies 5.9mm < f < 6.4mm, where f is the focal length of the optical imaging system, wherein 11.0mm < f2 < 31.0mm, f2 is the focal length of the second lens, and the optical imaging system satisfies TL / 2Y < 2.0, where TL is the distance from the object-side surface of the first lens to the image plane, and 2Y is the diagonal length of the image plane.

15. An optical imaging system, comprising: a first lens, having positive refractive power; a second lens, having positive refractive power; a third lens, having negative refractive power; a fourth lens, having positive refractive power; a fifth lens, having positive refractive power, wherein the first lens to the fifth lens are arranged in order from the object side toward the image plane, wherein the optical imaging system includes a total of five lenses with refractive power, wherein the optical imaging system satisfies 5.9mm < f < 6.4mm, where f is the focal length of the optical imaging system, wherein 11.0mm < f2 < 31.0mm, f2 is the focal length of the second lens, and the optical imaging system satisfies -6.5 < {(1 / f)*(Y / tanθ)-1}*100 < -1.0, where Y is 1 / 2 of the diagonal length of the image plane, and θ is the half field of view of the optical imaging system.

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