Optical imaging system

Abstract

The present application provides an optical imaging system. The optical imaging system comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens. The first lens has a negative refractive power, and the second lens has a negative refractive power. The third lens has a positive refractive power, and the fourth lens has a positive refractive power and its object side surface is concave. The fifth lens has a positive refractive power. The sixth lens has a negative refractive power. The first lens to the sixth lens are sequentially arranged from the object side to the imaging surface. One lens among the first lens to the sixth lens is bonded to its adjacent lens.

Description

[0001] This application is a divisional application of the invention patent application filed on October 20, 2016, with application number 201610916160.X and title "Optical Imaging System". Technical Field

[0002] The following description relates to an optical imaging system that is installed as a sensor in a surveillance camera. Background Technology

[0003] Small surveillance cameras are installed in vehicles to image or provide a visual representation of the vehicle's front and rear fields of view. For example, a small surveillance camera is mounted on the vehicle's rearview mirror to image, record, or visually present moving vehicles, pedestrians, and scenes in front of the vehicle.

[0004] Such small surveillance cameras do not simply image objects in front of and behind a vehicle, but rather function as sensors to identify objects present in front of and behind the vehicle. In this respect, the surveillance camera used as a sensor should be able to detect subtle movements. However, this sensor-based approach requires a high level of resolution. As a result, the surveillance camera may be prone to overheating due to its high resolution.

[0005] Therefore, as mentioned above, there is a need to develop an optical imaging system that maintains a constant and high level of resolution even at high temperatures, so that it can be installed as a sensor in a surveillance camera. Summary of the Invention

[0006] This summary is provided to introduce, in a simplified form, the selection of inventive concepts that will be further described in the detailed embodiments below. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to help determine the scope of the claimed subject matter.

[0007] One aspect of this disclosure provides an optical imaging system that has a constant and high level of resolution at high temperatures.

[0008] According to an embodiment, an optical imaging system is provided, the optical imaging system comprising: a first lens having negative refractive power; a second lens having negative refractive power; a third lens having positive refractive power; a fourth lens having positive refractive power, the object-side surface of which is concave; a fifth lens having positive refractive power; and a sixth lens having negative refractive power, wherein the first lens to the sixth lens are arranged sequentially from the object side toward the imaging plane, and one of the first lens to the sixth lens can be coupled to an adjacent lens.

[0009] The object surface of the first lens can be convex, and the image surface of the first lens can be concave.

[0010] The object surface of the second lens can be convex, and the image surface of the second lens can be concave.

[0011] The object-side surface of the third lens can be convex.

[0012] The image-side surface of the third lens can be convex.

[0013] The image-side surface of the third lens can be concave.

[0014] The image-side surface of the fourth lens can be convex.

[0015] The object surface of the fifth lens can be convex, and the image surface of the fifth lens can be convex.

[0016] The object surface of the sixth lens may be concave, and the image surface of the sixth lens may be concave.

[0017] The second lens and the third lens can be joined together.

[0018] The fifth lens and the sixth lens can be joined together.

[0019] The fourth lens may be made of glass.

[0020] The fourth lens may be aspherical.

[0021] The fifth lens among the first to sixth lenses may have the largest effective radius.

[0022] 10.0mm < |R13|, where R13 can be the radius of curvature of the image-side surface of the sixth lens.

[0023] The optical imaging system may further include an aperture stop disposed between the third lens and the fourth lens.

[0024] The optical imaging system may further include: a filter; and a protective glass disposed between the sixth lens and the imaging surface.

[0025] The radius of curvature of the image surface of the second lens can be substantially the same as the radius of curvature of the object surface of the third lens.

[0026] The radius of curvature of the image surface of the fifth lens can be substantially the same as the radius of curvature of the object surface of the sixth lens.

[0027] According to an embodiment, an optical imaging system is provided, the optical imaging system including three lenses with positive refractive power and three lenses with negative refractive power, wherein four of the six lenses can be joined to adjacent lenses to form two pairs of joined lenses, the joined lenses being formed by combining lenses having different refractive powers from each other.

[0028] Other features and aspects will become apparent from the following detailed description, drawings, and claims. Attached Figure Description

[0029] Figure 1 This is a diagram of an optical imaging system according to the first embodiment;

[0030] Figure 2 It means Figure 1 A table showing the characteristics of the lenses in the optical imaging system;

[0031] Figure 3 It means Figure 1 The table shows the aspherical characteristics of the optical imaging system.

[0032] Figure 4 This is a diagram of an optical imaging system according to the second embodiment;

[0033] Figure 5 It means Figure 4 A table showing the characteristics of the lenses in the optical imaging system;

[0034] Figure 6 It means Figure 4 The table shows the aspherical characteristics of the optical imaging system.

[0035] Figure 7 It is based on temperature. Figure 1 The graph shows the variation of the modulation transfer function (MTF) of the optical imaging system.

[0036] Figure 8 It is based on temperature. Figure 4 The graph showing the MTF variation of the optical imaging system; and

[0037] Figure 9 This is another graph representing the MTF variation of an optical imaging system based on temperature.

[0038] 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 convenience, the relative dimensions and depictions of these elements may be enlarged. Detailed Implementation

[0039] 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. The order of operations described herein is merely illustrative and is not limited to the order presented 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.

[0040] The features described herein may be implemented in various forms and are not to be construed as being limited to the examples described herein. Rather, the examples described herein are 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] It will be understood that although the terms "first," "second," "third," etc., may be used herein to describe various lenses, these lenses should not be limited by these terms. These terms are used only to distinguish one lens from another. These terms do not necessarily imply a particular order or arrangement of the lenses. Therefore, the first lens discussed below may be referred to as the second lens without departing from the teachings of the various embodiments.

[0042] Exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings.

[0043] Furthermore, the surface of each lens closest to the object is called the first surface or object-side surface, and the surface of each lens closest to the imaging plane is called the second surface or image-side surface. Additionally, all values ​​for the lens's radius of curvature, thickness / distance, OAL, Y (half the diagonal length of the imaging plane), focal length, and other lens parameters are expressed in millimeters (mm).

[0044] Those skilled in the art will appreciate that other units of measurement may be used. Furthermore, throughout this specification, all radii of curvature, thickness, OAL (optical distance from the first surface of the first lens to the image sensor), optical distance (SL) between the aperture and the image sensor, image height (IMGH), back focus length (BFL), the total focal length of the optical system, and the focal length of each lens are expressed in millimeters (mm). Moreover, the lens thickness, inter-lens spacing, OAL, and SL are all distances measured based on the optical axis of the lens.

[0045] Furthermore, in the embodiments, the shape of the lens is described and explained relative to the optical axis portion of the lens.

[0046] A convex surface of a lens means that the optical axis portion of the corresponding surface protrudes, while a concave surface means that the optical axis portion of the corresponding surface is recessed. Therefore, in a lens configuration where one surface is described as convex, the edge portion of said surface may be recessed. Similarly, in a lens configuration where one surface is described as concave, the edge portion of said surface may protrude. In other words, the paraxial region of the lens may be convex, while the rest 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 rest of the lens outside the paraxial region may be convex, concave, or flat.

[0047] Furthermore, in the embodiments, the thickness and radius of curvature of the lens are measured relative to the optical axis of the corresponding lens.

[0048] The optical system according to an embodiment includes six lenses. As an example, the optical system may include a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens. Without departing from the scope of the embodiments described herein, the lens module may include four to six lenses. According to the illustrated example, the embodiment describing the optical system includes six 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 six lenses, while obtaining the various results and effects described below. Furthermore, although each lens is described as having a specific refractive power, at least one of lenses with different refractive powers can be used to obtain the desired results.

[0049] In the optical system according to an embodiment, the first to sixth lenses are formed of a material including glass, plastic, or other similar types of polycarbonate material. In another embodiment, at least one of the first to sixth lenses is formed of a material different from the material forming the other lenses.

[0050] In this disclosure, the first lens refers to the lens closest to the object (or target), while the sixth lens refers to the lens closest to the imaging plane (or image sensor). Furthermore, the lens thickness, the inter-lens spacing, and the OAL are all distances measured based on the optical axis of the lens.

[0051] The optical imaging system comprises six lenses. The construction of each lens will be described below.

[0052] The first lens has refractive power (such as positive or negative refractive power). For example, the first lens has negative refractive power.

[0053] One surface of the first lens is concave. For example, the image-side surface of the first lens is concave.

[0054] The first lens may have a spherical surface. For example, both surfaces of the first lens are spherical. The first lens may be formed of a material with high light transmittance and excellent machinability. For example, the first lens may be formed of glass. However, the material of the first lens is not limited to this. For example, the first lens may also be formed of plastic.

[0055] The first lens has a predetermined refractive index. For example, the refractive index of the first lens is 1.60 or less. The first lens may have a relatively high Abbe number. For example, the Abbe number of the first lens may be 60 or greater.

[0056] The second lens has refractive power (such as positive or negative refractive power). For example, the second lens has negative refractive power.

[0057] One surface of the second lens is concave. For example, the image-side surface of the second lens is concave.

[0058] The second lens may have a spherical surface. For example, both surfaces of the second lens are spherical. The second lens may be formed of a material with high light transmittance and excellent machinability. For example, the second lens may be formed of glass. However, the material of the second lens is not limited to this. For example, the second lens may also be formed of plastic.

[0059] The second lens may have a higher refractive index than the first lens. For example, the refractive index of the second lens may be 1.80 or greater. The second lens may also have a lower Abbe number than the first lens. For example, the Abbe number of the second lens may be 25 or less.

[0060] The third lens may have refractive power (such as positive or negative refractive power). For example, the third lens may have positive refractive power.

[0061] One surface of the third lens can be convex. For example, the object-side surface of the third lens is convex.

[0062] The third lens may have a spherical surface. For example, both surfaces of the third lens are spherical. The third lens may be formed of a material with high light transmittance and excellent machinability. For example, the third lens may be formed of glass. However, the material of the third lens is not limited to this. For example, the third lens may be formed of plastic.

[0063] The third lens may have a higher refractive index than the first lens. For example, the refractive index of the third lens may be 1.90 or greater. The third lens may also have a higher Abbe number than the second lens. For example, the Abbe number of the third lens may be 30 or greater.

[0064] The fourth lens may have refractive power (such as positive or negative refractive power). For example, the fourth lens has positive refractive power.

[0065] One surface of the fourth lens can be concave. For example, the object-side surface of the fourth lens is concave.

[0066] The fourth lens may have aspherical surfaces. For example, two surfaces of the fourth lens may be aspherical. The fourth lens may be formed from a material with high light transmittance and excellent machinability. For example, the fourth lens may be formed from glass. However, the material of the fourth lens is not limited to this. For example, the fourth lens may be formed from plastic.

[0067] The fourth lens may have a lower refractive index than the third lens. For example, the refractive index of the fourth lens may be less than 1.80. The fourth lens may also have a lower Abbe number than the first lens. For example, the Abbe number of the fourth lens may be 55 or less.

[0068] The fifth lens may have refractive power (such as positive or negative refractive power). For example, the fifth lens has positive refractive power.

[0069] At least one surface of the fifth lens may be convex. For example, both surfaces of the fifth lens may be convex.

[0070] The fifth lens may have a spherical surface. For example, both surfaces of the fifth lens are spherical. The fifth lens may be formed of a material with high light transmittance and excellent machinability. For example, the fifth lens may be formed of glass. However, the material of the fifth lens is not limited to this. For example, the fifth lens may be formed of plastic.

[0071] The fifth lens may have a refractive index substantially similar to that of the fourth lens. For example, the refractive index of the fifth lens may be less than 1.80. The fifth lens may also have an Abbe number lower than that of the first lens. For example, the Abbe number of the fifth lens may be less than 60.

[0072] The sixth lens may have refractive power (such as positive or negative refractive power). For example, the sixth lens may have negative refractive power.

[0073] At least one surface of the sixth lens may be concave. For example, both surfaces of the sixth lens may be concave. In an alternative embodiment, the image-side surface of the sixth lens may be flat or substantially flat.

[0074] The sixth lens may have a spherical surface. For example, both surfaces of the sixth lens are spherical. The sixth lens may be formed of a material with high light transmittance and excellent machinability. For example, the sixth lens may be formed of glass. However, the material of the sixth lens is not limited to this. For example, the sixth lens may be formed of plastic.

[0075] The sixth lens may have a higher refractive index than the first through fifth lenses. For example, the refractive index of the sixth lens may be 1.90 or greater. The sixth lens may have a lower Abbe number than the second lens. For example, the Abbe number of the sixth lens may be 23 or less.

[0076] At least one of the first through sixth lenses may be aspherical. For example, the fourth lens is aspherical. The aspherical surface of the fourth lens can be represented by the following Equation 1:

[0077] [Equation 1]

[0078]

[0079] In the example, c is the reciprocal of the radius of curvature of the lens, k is the conic section constant, r is the distance from a point on the aspherical surface of the lens to the optical axis, A to H are aspherical constants, and Z (or SAG) is the distance between a point on the aspherical surface of the lens at a distance r from the optical axis and a tangent plane that is tangent to the vertex of the aspherical surface of the lens.

[0080] Optical imaging systems may include image sensors. Image sensors can be configured to achieve high levels of resolution. For example, the unit size of the pixels constituting an image sensor may be 1.12 μm or smaller. The surface of the image sensor forms the imaging surface on which the image is formed.

[0081] An optical imaging system may include an aperture stop. The aperture stop may be positioned between lenses. For example, the aperture stop may be positioned between a third lens and a fourth lens. In another example, the aperture stop may be positioned in front of the object-side surface of the first lens. The aperture stop adjusts the amount of light incident on the image sensor. The aperture stop is configured to divide the refractive power of the optical imaging system in two. For example, the total refractive power of the lens placed in front of the aperture stop (i.e., adjacent to the object side) may be negative, while the total refractive power of the lens placed behind the aperture stop (i.e., adjacent to the imaging plane) may be positive. This configuration can, for example, increase the field of view of the optical imaging system and reduce the overall length of the optical imaging system.

[0082] Optical imaging systems may include filters. Filters may be positioned between a sixth lens and an image sensor and may filter out components that reduce resolution. For example, a filter may filter out light of infrared wavelengths.

[0083] The optical imaging system may also include a cover glass. The cover glass can be positioned between the sixth lens and the image sensor, and can reduce resolution degradation caused by foreign objects. For example, the cover glass can be formed directly on the surface of the image sensor.

[0084] An optical imaging system satisfies the following conditional expression:

[0085] [Conditional Expression] 90° <FOV

[0086] [Conditional expression] 10mm < |R13|

[0087] In the example, FOV is the maximum field of view of the optical imaging system (in degrees), and R13 is the radius of curvature of the image-side surface of the sixth lens.

[0088] Next, an optical imaging system according to an embodiment will be described. First, reference will be made to... Figure 1 An optical imaging system according to a first embodiment is described.

[0089] 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, a fifth lens 150, and a sixth lens 160.

[0090] In this embodiment, the first lens 110 has negative refractive power, its object-side surface is convex, and its image-side surface is concave. The second lens 120 has negative refractive power, its object-side surface is convex, and its image-side surface is concave. The third lens 130 has positive refractive power, its object-side surface is convex, and its image-side surface is convex. 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, its object-side surface is convex, and its image-side surface is convex. The sixth lens 160 has negative refractive power, its object-side surface is concave, and its image-side surface is concave.

[0091] In one example, all lenses from the first to the sixth lens are made of glass. The fourth lens from the first to the sixth lens is aspherical, while the other lenses from the first to the sixth lens are spherical.

[0092] The second lens 120 may be joined, bonded, adhered, directly connected, or operatively connected to the third lens 130. For example, the image-side surface S4 of the second lens 120 may be partially, substantially, or selectively entirely joined, bonded, adhered, directly connected, or operatively connected to the object-side surface S5 of the third lens 130. For this purpose, the radius of curvature of the image-side surface of the second lens is the same, equivalent, or substantially the same as the radius of curvature of the object-side surface of the third lens. In one configuration, the joining, bonding, adhesion, direct connection, or operative connection is typically performed by using an adhesive, heating, or pressurizing to firmly connect two or more lenses to each other.

[0093] The fifth lens 150 may be joined, bonded, adhered, directly connected, or operatively connected to the sixth lens 160. For example, the image-side surface S11 of the fifth lens 150 may be partially, substantially, or selectively wholly joined, bonded, adhered, directly connected, or operatively connected to the object-side surface S12 of the sixth lens 160. For this purpose, the radius of curvature of the image-side surface of the fifth lens 150 and the radius of curvature of the object-side surface of the sixth lens 160 may be the same, equivalent, or substantially the same.

[0094] The optical imaging system constructed as described above exhibits Figure 2 The characteristics of the lens are shown in the table below. Figure 3 This is a table showing the aspherical (ASP) characteristics of the fourth lens.

[0095] The optical imaging system 100 includes an aperture stop ST. In one example, the aperture stop ST is disposed between a third lens 130 and a fourth lens 140. For example, the aperture stop ST is disposed between the image-side surface of the third lens 130 and the object-side surface of the fourth lens 140.

[0096] The optical imaging system 100 includes a filter 170 and a protective glass 180. The filter 170 and the protective glass 180 are disposed between the sixth lens 160 and the image sensor 190. The filter 170 filters out infrared light, and the protective glass 180 protects the image sensor 190.

[0097] The optical imaging system 100 includes an image sensor 190. The image sensor 190 forms an imaging surface on which an image of light refracted by a lens is formed.

[0098] Reference Figure 4 An optical imaging system according to a second embodiment is described.

[0099] 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, a fifth lens 250, and a sixth lens 260.

[0100] In this embodiment, the first lens 210 may have negative refractive power, with its object-side surface being convex and its image-side surface being concave. The second lens 220 has negative refractive power, with its object-side surface being convex and its image-side surface being concave. The third lens 230 has positive refractive power, with its object-side surface being convex and its image-side surface being concave. The fourth lens 240 has positive refractive power, with its object-side surface being concave and its image-side surface being convex. The fifth lens 250 has positive refractive power, with its object-side surface being convex and its image-side surface being convex. The sixth lens 260 has negative refractive power, with its object-side surface being concave and its image-side surface being concave.

[0101] In one example, all lenses from the first to the sixth lens are made of glass. The fourth lens from the first to the sixth lens is aspherical, while the other lenses from the first to the sixth lens are spherical.

[0102] The second lens 220 may be joined, bonded, adhered, directly connected, or operatively connected to the third lens 230. For example, the image-side surface S4 of the second lens 220 may be partially, substantially, or selectively entirely joined, bonded, adhered, directly connected, or operatively connected to the object-side surface S5 of the third lens 230. For this purpose, the radius of curvature of the image-side surface of the second lens is the same, equivalent, or substantially the same as the radius of curvature of the object-side surface of the third lens.

[0103] The fifth lens 250 may be joined, bonded, adhered, directly connected, or operatively connected to the sixth lens 260. For example, the image-side surface S11 of the fifth lens 250 may be partially, substantially, or selectively entirely joined, bonded, adhered, directly connected, or operatively connected to the object-side surface S12 of the sixth lens 260. For this purpose, the radius of curvature of the image-side surface of the fifth lens 250 and the radius of curvature of the object-side surface of the sixth lens 260 may be the same, equivalent, or substantially the same.

[0104] The optical imaging system constructed as described above exhibits Figure 5 The characteristics of the lens are shown in the table. Figure 6 This is a table showing the aspherical characteristics of the fourth lens.

[0105] The optical imaging system 200 includes an aperture stop ST. The aperture stop ST is disposed between the third lens 230 and the fourth lens 240. For example, the aperture stop ST is disposed between the image surface of the third lens 230 and the object surface of the fourth lens 240.

[0106] The optical imaging system 200 includes a filter 270 and a protective glass 280. The filter 270 and the protective glass 280 are disposed between the sixth lens 260 and the image sensor 290. The filter 270 filters out infrared light, and the protective glass 280 protects the image sensor 290.

[0107] The optical imaging system 200 includes an image sensor 290. The image sensor 290 forms an imaging surface on which an image of light refracted by a lens is formed.

[0108] As an illustrative and non-limiting example, Table 1 shows the optical characteristics of the optical imaging systems according to the first and second embodiments. The total focal length (f) of the optical imaging system is determined to be substantially in the range of 3.3 mm to 4.1 mm. In the optical imaging system, the focal length (f1) of the first lens is determined to be substantially in the range of -7.3 mm to -4.3 mm. In the optical imaging system, the focal length (f2) of the second lens is determined to be substantially in the range of -6.2 mm to -3.2 mm. In the optical imaging system, the focal length (f3) of the third lens is determined to be substantially in the range of 1.8 mm to 4.2 mm. In the optical imaging system, the focal length (f4) of the fourth lens is determined to be substantially in the range of 5.3 mm to 10.1 mm. In the optical imaging system, the focal length (f5) of the fifth lens is determined to be substantially in the range of 3.1 mm to 5.9 mm. In the optical imaging system, the focal length (f6) of the sixth lens is determined to be substantially in the range of -6.5 mm to -3.4 mm. In optical imaging systems, the OAL is generally defined as being in the range of 13.0 mm to 17.5 mm.

[0109] [Table 1]

[0110]

[0111]

[0112] Furthermore, because multiple spherical lenses are used in the optical imaging system constructed as described above, the cost required to manufacture the optical imaging system is reduced. The optical imaging system according to the embodiment is configured to significantly reduce changes in focal length due to temperature by significantly reducing the refractive power of the lenses.

[0113] The optical imaging system according to the embodiment maintains a constant level of resolution at high temperatures. Figure 7 and Figure 8 It is a graph showing the variation of the optical imaging system according to the first and second embodiments with respect to temperature or the modulation transfer function (MTF) as a function of temperature.

[0114] In the optical imaging system according to the first embodiment, the MTF value is in the range of 0.72 to 0.75 within a temperature range of 10°C to 60°C. Similarly, in the optical imaging system according to the second embodiment, the MTF value is in the range of 0.71 to 0.75 within a temperature range of 10°C to 60°C. Therefore, the optical imaging system according to the embodiment has a constant level of resolution within a temperature range of 10°C to 60°C. Thus, the optical imaging system according to the embodiment can achieve a high level of resolution even in environments with a wide temperature range (such as the interior of a vehicle).

[0115] On the other hand, such as Figure 9As shown, in other optical imaging systems, the MTF value ranges from 0.7 to 0.8 within the temperature range of 10°C to 60°C. Therefore, in such other optical imaging systems, the resolution varies significantly within the temperature range of 10°C to 60°C.

[0116] As described above, according to the embodiments, a high level of resolution is achieved even in high-temperature environments.

[0117] While this disclosure includes specific examples, it will be apparent to those skilled in the art that various changes in form and detail may be made to these examples without departing from the spirit and scope of the claims and their equivalents. The examples described herein are to be understood as descriptive in nature only 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 a different manner and / or replaced or supplemented by other components or their equivalents. Therefore, the scope of this disclosure is not defined by the specific embodiments but by the claims and their equivalents, and all variations 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: 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 positive refractive power, and its object-side surface is concave. The fifth lens has positive refractive power; The sixth lens has negative refractive power, and the image surface of the sixth lens is concave. The first to the sixth lenses are arranged sequentially from the object side toward the imaging plane, and the optical imaging system has a total of six lenses with refractive power. One of the first through sixth lenses is joined to an adjacent lens. The total focal length of the optical imaging system is in the range of 3.3 mm to 4.1 mm, the focal length of the second lens is in the range of -6.2 mm to -3.2 mm, and the distance on the optical axis from the object surface of the first lens to the imaging surface is in the range of 13.0 mm to 17.5 mm.

2. The optical imaging system according to claim 1, wherein, The focal length of the first lens is in the range of -7.3mm to -4.3mm.

3. The optical imaging system according to claim 1, wherein, The maximum field of view (FOV) of the optical imaging system is greater than or equal to 90°.

4. The optical imaging system according to claim 1, wherein, The focal length of the third lens is in the range of 1.8mm to 4.2mm.

5. The optical imaging system according to claim 1, wherein, The focal length of the fourth lens is in the range of 5.3 mm to 10.1 mm.

6. The optical imaging system according to claim 1, wherein, The focal length of the fifth lens is in the range of 3.1 mm to 5.9 mm.

7. The optical imaging system according to claim 1, wherein, The focal length of the sixth lens is in the range of -6.5mm to -3.4mm.

8. The optical imaging system according to claim 1, wherein, The object surface of the first lens is convex, and the image surface of the first lens is concave.

9. The optical imaging system according to claim 1, wherein, The object surface of the second lens is convex, and the image surface of the second lens is concave.

10. The optical imaging system according to claim 1, wherein, The object-side surface of the third lens is convex, and the image-side surface of the third lens is either convex or concave.

11. The optical imaging system according to claim 1, wherein, The image-side surface of the fourth lens is convex, the fourth lens is formed of glass, and the fourth lens has an aspherical shape.

12. The optical imaging system according to claim 1, wherein, The object surface of the fifth lens is convex, and the image surface of the fifth lens is also convex.

13. The optical imaging system according to claim 1, wherein, The object-side surface of the sixth lens is concave.

14. The optical imaging system according to claim 1, wherein, The second lens is joined to the third lens, and the fifth lens is joined to the sixth lens.

15. The optical imaging system according to claim 1, wherein, The fifth lens among the first to sixth lenses has the largest effective radius.

16. The optical imaging system according to claim 1, wherein, 10.0mm < |R13|, where R13 is the radius of curvature of the image-side surface of the sixth lens.

17. The optical imaging system according to claim 1, further comprising: An aperture stop is disposed between the third lens and the fourth lens; Filters; as well as A protective glass is disposed between the sixth lens and the imaging surface.

18. The optical imaging system according to claim 1, wherein, The radius of curvature of the image surface of the second lens is substantially the same as the radius of curvature of the object surface of the third lens, and the radius of curvature of the image surface of the fifth lens is substantially the same as the radius of curvature of the object surface of the sixth lens.

19. An optical imaging system, comprising: 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 positive refractive power; The fifth lens has positive refractive power; The sixth lens has negative refractive power. The optical imaging system has a total of six lenses with refractive power. Four of the six lenses are joined to adjacent lenses to form two pairs of joined lenses. The joined lenses are constructed by combining lenses with different refractive powers. The total focal length of the optical imaging system is in the range of 3.3 mm to 4.1 mm, the focal length of the second lens is in the range of -6.2 mm to -3.2 mm, and the distance on the optical axis from the object surface of the first lens to the imaging surface is in the range of 13.0 mm to 17.5 mm. The image-side surface of the sixth lens is concave.

20. An optical imaging system, comprising: 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 positive refractive power, and its object-side surface is concave. The fifth lens has positive refractive power; The sixth lens has negative refractive power. The first to the sixth lenses are arranged sequentially from the object side toward the imaging plane, and the optical imaging system has a total of six lenses with refractive power. One of the first through sixth lenses is joined to an adjacent lens. The optical imaging system has a total focal length ranging from 3.3mm to 4.1mm, with the first lens having a focal length ranging from -7.3mm to -4.3mm, the second lens from -6.2mm to -3.2mm, the third lens from 1.8mm to 4.2mm, the fourth lens from 5.3mm to 10.1mm, the fifth lens from 3.1mm to 5.9mm, and the sixth lens from -6.5mm to -3.4mm. The image-side surface of the sixth lens is concave.

21. The optical imaging system according to claim 20, wherein, The distance on the optical axis from the object surface of the first lens to the imaging surface ranges from 13.0 mm to 17.5 mm.

22. The optical imaging system according to claim 20, wherein, The object surface of the first lens is convex, and the image surface of the first lens is concave.

23. The optical imaging system according to claim 20, wherein, The object surface of the second lens is convex, and the image surface of the second lens is concave.

24. The optical imaging system according to claim 20, wherein, The object-side surface of the third lens is convex, and the image-side surface of the third lens is either convex or concave.

25. The optical imaging system according to claim 20, wherein, The image-side surface of the fourth lens is convex, the fourth lens is formed of glass, and the fourth lens has an aspherical shape.

26. The optical imaging system according to claim 20, wherein, The object surface of the fifth lens is convex, and the image surface of the fifth lens is also convex.

27. The optical imaging system according to claim 20, wherein, The object-side surface of the sixth lens is concave.

28. The optical imaging system according to claim 20, wherein, The second lens is joined to the third lens, and the fifth lens is joined to the sixth lens.

29. The optical imaging system according to claim 20, wherein, The fifth lens among the first to sixth lenses has the largest effective radius.

30. The optical imaging system according to claim 20, wherein, 10.0mm < |R13|, where R13 is the radius of curvature of the image-side surface of the sixth lens.

31. The optical imaging system according to claim 20, further comprising: An aperture stop is disposed between the third lens and the fourth lens; Filters; as well as A protective glass is disposed between the sixth lens and the imaging surface.

32. The optical imaging system according to claim 20, wherein, The radius of curvature of the image surface of the second lens is substantially the same as the radius of curvature of the object surface of the third lens, and the radius of curvature of the image surface of the fifth lens is substantially the same as the radius of curvature of the object surface of the sixth lens.

33. An optical imaging system, comprising: 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 positive refractive power; The fifth lens has positive refractive power; The sixth lens has negative refractive power. Specifically, four of the lenses from the first to the sixth lens are joined to adjacent lenses to form two pairs of joined lenses. The joined lenses are constructed by combining lenses with different refractive powers. The optical imaging system has a total focal length ranging from 3.3mm to 4.1mm, with the first lens having a focal length ranging from -7.3mm to -4.3mm, the second lens from -6.2mm to -3.2mm, the third lens from 1.8mm to 4.2mm, the fourth lens from 5.3mm to 10.1mm, the fifth lens from 3.1mm to 5.9mm, and the sixth lens from -6.5mm to -3.4mm. The first lens to the sixth lens are arranged sequentially from the object side toward the imaging surface. The optical imaging system has a total of six lenses with refractive power, and the image-side surface of the sixth lens is concave.

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