Miniature wide-angle lens

Abstract

The miniature wide-angle lens comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens and a seventh lens which are sequentially distributed from an object space to an image space along an optical axis, the first lens is a convex-concave lens with negative focal power, a first curved surface, close to the object space, of the first lens is a convex surface, and a second curved surface, close to the image space, of the second lens is a concave surface. The second curved surface close to the image space is a concave surface; the second lens is a biconvex lens with positive focal power; the third lens is a biconcave lens with negative focal power; the fourth lens is a concave-convex lens with positive focal power; the fifth lens is a biconvex lens with positive focal power; the sixth lens is a concave-convex lens with positive focal power; and the seventh lens is a plate lens with positive focal power. According to the miniature wide-angle lens, the optical structure of seven glass lenses is adopted, and the overall size of the miniature wide-angle lens is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of lenses, and in particular to a miniature wide-angle lens. Background Art

[0002] With the rapid development of modern science and technology, security monitoring technology is being used more and more widely in various fields. From public places such as squares and warehouses, to living areas such as residential areas and schools, to key areas such as borders and important facilities, security monitoring plays an indispensable role. In security monitoring systems, lenses are key supporting products for cameras, and their quality and performance directly affect the clarity and efficiency of monitoring images. In the existing monitoring facilities on the market, the relevant types of lenses have a large barrel size due to the large number of glass lenses used, which cannot meet consumers' demand for small-volume monitoring equipment. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a miniature wide-angle lens to solve the problem that the existing wide-angle lens is relatively large in size.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: a miniature wide-angle lens, which includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens and a seventh lens distributed in sequence along the optical axis from the object side to the image side, wherein: The first lens is a convex-concave lens with negative optical power, wherein the first curved surface of the first lens close to the object side is a convex surface, and the second curved surface of the first lens close to the image side is a concave surface; The second lens is a biconvex lens with positive optical power; The third lens is a biconcave lens with negative optical power; The fourth lens is a meniscus lens with positive refractive power, wherein the first curved surface of the fourth lens close to the object side is a concave surface, and the second curved surface close to the image side is a convex surface; The fifth lens is a biconvex lens with positive optical power; The sixth lens is a meniscus lens with positive refractive power, wherein the first curved surface of the sixth lens close to the object side is a concave surface, and the second curved surface close to the image side is a convex surface; The seventh lens is a plano lens with positive refractive power.

[0005] Furthermore, in the micro wide-angle lens described in the present invention, the curvature radius of the first curved surface of the second lens is a positive value, and the curvature radius of the second curved surface of the second lens is a negative value, wherein the absolute values ​​of the curvature radii of the first curved surface and the second curved surface of the second lens are the same.

[0006] Furthermore, in the micro wide-angle lens described in the present invention, the curvature radius of the second curved surface of the fifth lens is a negative value, and the curvature radius of the first curved surface of the sixth lens is a negative value, wherein the curvature radius of the second curved surface of the fifth lens is the same as the curvature radius of the first curved surface of the sixth lens.

[0007] Furthermore, in the micro wide-angle lens of the present invention, the micro wide-angle lens needs to satisfy the following conditional formula: Tan(Semi-FOV)>TTL / (2×f) 17<(f23×f45) / (D2×D3)<22 8.5<(f45×f56) / (D4×D56)<9.0 Wherein, Tan(Semi-FOV) represents the tangent value of Semi-FOV, Semi-FOV is the maximum half field angle of the micro wide-angle lens, TTL is the total optical length of the micro wide-angle lens; f is the equivalent focal length of the micro wide-angle lens; Wherein, f23 is the equivalent focal length of the second lens and the third lens; f45 is the equivalent focal length of the fourth lens and the fifth lens; D2 is the center thickness of the second lens on the optical axis; D3 is the center thickness of the third lens on the optical axis; Wherein, f56 is the equivalent focal length of the fifth lens and the sixth lens; D4 is the center thickness of the fourth lens on the optical axis; and D56 is the total center thickness of the fifth and sixth lenses on the optical axis.

[0008] Furthermore, in the micro wide-angle lens of the present invention, the first lens and the second lens satisfy the following relationship: 0.9<|f1 / f |<1.0; 0.24<|L1 / f1 |<0.3, 0.2<|D1 / f1 |<0.3; 1.2<|f2 / f1|<1.3; 0.02 <L2 / f2<0.08;0.6<D2 / f2<0.8 Among them, f1 is the focal length of the first lens; f is the equivalent focal length of the micro wide-angle lens; L1 is the distance between the first lens and the second lens; D1 is the center thickness of the first lens on the optical axis; f2 is the focal length of the second lens; L2 is the distance between the second lens and the third lens; D2 is the center thickness of the second lens on the optical axis.

[0009] Furthermore, in the micro wide-angle lens of the present invention, the third lens satisfies the following relationship: 1.8<|f3 / f |<1.9 0.02<|L2 / f3|<0.05, 0.09<|D3 / f3|<0.13 Among them, f3 is the focal length of the third lens; f is the equivalent focal length of the micro wide-angle lens; L2 is the distance between the second lens and the third lens; D3 is the center thickness of the third lens on the optical axis.

[0010] Furthermore, in the micro wide-angle lens of the present invention, the fourth lens and the fifth lens satisfy the following relationship: 1.6 <f4 / f<2.0,20<f5 / f<23 0.03 <L3 / f<0.6,0.3<D4 / f<0.5 Among them, f4 is the focal length of the fourth lens; f is the equivalent focal length of the micro wide-angle lens; f5 is the focal length of the fifth lens; L3 is the distance between the third lens and the fourth lens; D4 is the center thickness of the fourth lens on the optical axis.

[0011] Furthermore, in the micro wide-angle lens of the present invention, the first lens, the fourth lens and the fifth lens are glass lenses made of the same material.

[0012] Furthermore, in the micro wide-angle lens of the present invention, the second lens and the sixth lens are glass lenses with a refractive index greater than a first threshold; and the third lens is a glass lens with an Abbe number lower than a second threshold.

[0013] Furthermore, in the micro wide-angle lens of the present invention, the fifth lens and the sixth lens are cemented lenses.

[0014] The beneficial effect of the present invention is that: the present invention designs a miniature wide-angle lens for security monitoring, and the miniature wide-angle lens only needs to use seven glass lenses. Through the arrangement and combination of the seven glass lenses, the total optical length of the miniature wide-angle lens of the present invention can be maintained below 14 mm in actual application, thereby reducing the volume of the miniature wide-angle lens. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of each lens group of the miniature wide-angle lens of the present invention in the first embodiment; Figure 2 is a point diagram of the miniature wide-angle lens of the present invention in the first embodiment; Figure 3 is an astigmatism diagram of the miniature wide-angle lens in Example 1 of the present invention; Figure 4 is a distortion diagram of the miniature wide-angle lens in the first embodiment of the present invention; Figure 5A spherical aberration diagram of the miniature wide-angle lens of the present invention in the first embodiment; Figure 6 is a chromatic aberration diagram of the miniature wide-angle lens in the first embodiment of the present invention; Figure 7 Schematic diagram of each lens group of the miniature wide-angle lens of the present invention in the second embodiment; Figure 8 is a point diagram of the miniature wide-angle lens of the present invention in the second embodiment; Fig. 9 is an astigmatism diagram of the miniature wide-angle lens in the second embodiment of the present invention; Fig.10 This is a distortion diagram of the miniature wide-angle lens in the second embodiment of the present invention; Fig.11 This is a spherical aberration diagram of the miniature wide-angle lens in the second embodiment of the present invention; Fig.12 This is a chromatic aberration diagram of the miniature wide-angle lens in the second embodiment of the present invention.

[0016] Description of labels: 1. The first lens; 2. Second lens; 3. The third lens; 4. The fourth lens; 5. The fifth lens; 6. Sixth lens; 7. The seventh lens. DETAILED DESCRIPTION

[0017] In order to explain the technical content, achieved objectives and effects of the present invention in detail, the following is an explanation in conjunction with the implementation modes and the accompanying drawings.

[0018] In the existing surveillance equipment on the market, all types of related lenses are multi-piece structures. As the number of lenses used gradually increases, the size of the lens also increases, and the restrictions on the structural design of the optical module also become stricter, making it impossible to meet consumers' demand for small-volume surveillance equipment. For this reason, please refer to Figures 1 to 12 The present invention discloses a miniature wide-angle lens, which comprises a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, a fifth lens 5, a sixth lens 6 and a seventh lens 7, which are sequentially distributed along the optical axis from the object side to the image side, wherein: The first lens is a convex-concave lens with negative optical power, wherein the first curved surface of the first lens close to the object side is a convex surface, and the second curved surface of the first lens close to the image side is a concave surface; The second lens is a biconvex lens with positive optical power; wherein the first curved surface of the second lens close to the object side is a convex surface, and the second curved surface close to the image side is a convex surface; The third lens is a double concave lens with negative optical power; wherein the first curved surface of the third lens close to the object side is a concave surface, and the second curved surface close to the image side is a concave surface; The fourth lens is a meniscus lens with positive refractive power, wherein the first curved surface of the fourth lens close to the object side is a concave surface, and the second curved surface close to the image side is a convex surface; The fifth lens is a biconvex lens with positive optical power; wherein the first curved surface of the fifth lens close to the object side is a convex surface, and the second curved surface close to the image side is a convex surface; The sixth lens is a meniscus lens with positive refractive power, wherein the first curved surface of the sixth lens close to the object side is a concave surface, and the second curved surface close to the image side is a convex surface; The seventh lens is a plano lens with positive refractive power.

[0019] From the above description, it can be seen that the beneficial effect of the present invention is that: the present invention designs a miniature wide-angle lens for monitoring, the miniature wide-angle lens adopts an optical structure of seven glass lenses, and the total optical length of the lens can be maintained below 14mm in practical applications.

[0020] It should be noted that, in the lens of the present invention, the surface close to the object side (i.e., the object side) is called the first curved surface, and the surface close to the image side (i.e., the image side) is called the second curved surface. When designing the lens of the present invention, when determining the positive and negative values ​​of the radius of curvature of the lens curved surface, the direction of the lens toward the object side is taken as the quasi-direction. When the value of the radius of curvature of the first curved surface of the lens is a positive value, the first curved surface is convex relative to the direction toward the object side, and the first curved surface is concave relative to the direction toward the image side. When the value of the radius of curvature of the second curved surface is a positive value, the second curved surface is convex relative to the direction toward the object side, and concave relative to the direction toward the image side.

[0021] Furthermore, in the micro wide-angle lens described in the present invention, the curvature radius of the first curved surface of the second lens is a positive value, and the curvature radius of the second curved surface of the second lens is a negative value, wherein the absolute values ​​of the curvature radii of the first curved surface and the second curved surface of the second lens are the same.

[0022] In practical applications, the first curved surface and the second curved surface of the first lens 1 of the present invention have positive values ​​of the radius of curvature. The second lens 2 has a positive value of the radius of curvature of the first curved surface, and a negative value of the radius of curvature of the second curved surface, wherein the radius of curvature of the two curved surfaces have the same value. The third lens 3 has a negative value of the radius of curvature of the first curved surface, and a positive value of the radius of curvature of the second curved surface. The fourth lens 4 has a negative value of the radius of curvature of the first curved surface and a negative value. The fifth lens 5 has a positive value of the radius of curvature of the first curved surface, and a negative value of the radius of curvature of the second curved surface. The sixth lens 6 has a negative value of the radius of curvature of the first curved surface, and a positive value of the radius of curvature of the second curved surface. The radius of curvature of the second curved surface of the fifth lens 5 and the first curved surface of the sixth lens 6 have the same value.

[0023] Furthermore, in the micro wide-angle lens described in the present invention, the curvature radius of the second curved surface of the fifth lens is a negative value, and the curvature radius of the first curved surface of the sixth lens is a negative value, wherein the curvature radius of the second curved surface of the fifth lens is the same as the curvature radius of the first curved surface of the sixth lens.

[0024] Furthermore, in the micro wide-angle lens of the present invention, the micro wide-angle lens needs to satisfy the following conditional formula: Tan(Semi-FOV)>TTL / (2×f) 17<(f23×f45) / (D2×D3)<22 8.5<(f45×f56) / (D4×D56)<9.0 Wherein, Tan(Semi-FOV) represents the tangent value of Semi-FOV, Semi-FOV is the maximum half field angle of the micro wide-angle lens, TTL is the total optical length of the micro wide-angle lens; f is the equivalent focal length of the micro wide-angle lens; Wherein, f23 is the equivalent focal length of the second lens 2 and the third lens 3; f45 is the equivalent focal length of the fourth lens 4 and the fifth lens 5; D2 is the center thickness of the second lens 2 on the optical axis; D3 is the center thickness of the third lens 3 on the optical axis; Wherein, f56 is the equivalent focal length of the fifth lens 5 and the sixth lens 6; D4 is the center thickness of the fourth lens 4 on the optical axis; and D56 is the total center thickness of the fifth lens 5 and the sixth lens 6 on the optical axis.

[0025] As mentioned above, the miniature wide-angle lens of the present invention needs to satisfy the above three conditional expressions, wherein the conditional expression Tan (Semi-FOV)>TTL / (2×f) is related to the allowable value of the total height design of the miniature wide-angle lens of the present invention. When the difference in the values ​​of Tan (Semi-FOV)>TTL / (2×f) is larger, the allowable value is lower. The above allowable value refers to the maximum deviation of certain parameters (such as total height) that can be accepted during design. Tan (Semi-FOV) means taking the Tan coefficient using the maximum half viewing angle, which can obtain the design parameters of the ideal optical height of this invention, and this parameter directly affects the setting of the lens thickness.

[0026] The (f23×f45) / (D2×D3) conditional expression is related to the upper limit of the total height design of the miniature wide-angle lens of the present invention, and the (f45×f56) / (D4×D56) conditional expression is related to the lower limit of the total height design of the miniature wide-angle lens of the present invention.

[0027] From the above description, it can be seen that the total height of the miniature wide-angle lens of the present invention is limited and constrained through the above three conditional expressions, so that the total optical length of the miniature wide-angle lens of the present invention can be maintained below 14 mm, meeting the needs of consumers for small-volume monitoring equipment.

[0028] Furthermore, in the micro wide-angle lens of the present invention, the first lens 1 and the second lens 2 satisfy the following relationship: 0.9<|f1 / f |<1.0; 0.24<|L1 / f1 |<0.3, 0.2<|D1 / f1 |<0.3; 1.2<|f2 / f1|<1.3; 0.02 <L2 / f2<0.08;0.6<D2 / f2<0.8 Among them, f1 is the focal length of the first lens 1; f is the equivalent focal length of the micro wide-angle lens; L1 is the distance between the first lens 1 and the second lens 2; D1 is the center thickness of the first lens 1 on the optical axis; f2 is the focal length of the second lens 2; L2 is the distance between the second lens 2 and the third lens 3; D2 is the center thickness of the second lens 2 on the optical axis.

[0029] From the above description, it can be seen that through the above relationship, the overall thickness of the first lens 1 and the second lens 2 can be better controlled, thereby ensuring that the total length of the final micro wide-angle lens is maintained below 14 mm, thereby reducing the volume of the micro wide-angle lens.

[0030] Furthermore, in the micro wide-angle lens of the present invention, the third lens 3 satisfies the following relationship: 1.8<|f3 / f |<1.9 0.02 < |L2 / f3| < 0.05, 0.09 < |D3 / f3| < 0.13 Wherein, f3 is the focal length of the third lens 3; f is the equivalent focal length of the micro wide - angle lens; L2 is the distance between the second lens 2 and the third lens 3; D3 is the central thickness of the third lens 3 on the optical axis.

[0031] As can be seen from the above description, to control the thickness of the third lens 3, the third lens 3 is correspondingly set so that the third lens 3 satisfies the following relational expressions: 0.02 < |L2 / f3| < 0.05, 0.09 < |D3 / f3| < 0.13, thereby effectively controlling the thickness of the third lens 3, and ensuring that the total length of the finally fabricated micro wide - angle lens is maintained below 14 mm, reducing the volume of the micro wide - angle lens.

[0032] Furthermore, in the micro wide - angle lens of the present invention, the fourth lens and the fifth lens 5 must satisfy the following relational expressions: 1.6 < f4 / f < 2.0, 20 < f5 / f < 23 0.03 < L3 / f < 0.6, 0.3 < D4 / f < 0.5 Wherein, f4 is the focal length of the fourth lens 4; f is the equivalent focal length of the micro wide - angle lens; f5 is the focal length of the fifth lens 5; L3 is the distance between the third lens 3 and the fourth lens 4; D4 is the central thickness of the fourth lens 4 on the optical axis.

[0033] As can be seen from the above description, in order to control the thickness of the fourth lens 4 and the fifth lens 5, the corresponding parameters of the fourth lens 4 and the fifth lens 5 satisfy the following relational expressions, that is, satisfy 0.03 < L3 / f < 0.6 and 0.3 < D4 / f < 0.5, thereby effectively controlling the thickness of the fourth lens 4 and the fifth lens 5, and ensuring that the total length of the finally fabricated micro wide - angle lens can be maintained below 14 mm, reducing the volume of the micro wide - angle lens.

[0034] Furthermore, in the micro wide - angle lens of the present invention, the first lens 1, the fourth lens 4, and the fifth lens 5 are glass lenses of the same material.

[0035] Furthermore, in the micro wide - angle lens of the present invention, the second lens 2 and the sixth lens 6 are glass lenses with a refractive index greater than the first threshold; the third lens 3 is a glass lens with an Abbe number lower than the second threshold.

[0036] In practical applications, the second lens 2 and the sixth lens 6 are made of glass lenses with high refractive materials (such as materials with a refractive index greater than or equal to 1.60), and the third lens 3 is a glass lens with a low Abbe number (such as an Abbe number less than 30). It should be noted that the first threshold and the second threshold can be selected according to actual conditions and are not limited here.

[0037] In practical applications, by arranging a combination of high and low refractive lenses, the first lens, the fourth lens, and the fifth lens are made of glass lenses of the same material; the second and sixth lenses are made of glass lenses of high refractive material, and the first lens, the second lens, the third lens, and the first four lenses of the third lens have negative and positive focal lengths, so that the present invention can achieve the purpose of high relative brightness and high definition, that is, improve the relative brightness and resolution of the miniature wide-angle lens.

[0038] Furthermore, in the micro wide-angle lens of the present invention, the fifth lens 5 and the sixth lens 6 are cemented lenses.

[0039] Please refer to Figures 1 to 6 , Embodiment 1 of the present invention is: This embodiment provides a miniature wide-angle lens, which is applied in the field of security monitoring, such as Figure 1 As shown, the miniature wide-angle lens adopts an optical structure of seven glass lenses. Specifically, the miniature wide-angle lens includes a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, a fifth lens 5, a sixth lens 6 and a seventh lens 7 which are sequentially distributed along the optical axis from the object side to the image side. The total length of the miniature wide-angle lens in this embodiment is maintained below 14 mm. Moreover, the miniature wide-angle lens in this embodiment can achieve the purpose of high relative brightness and high resolution by arranging a combination of high and low refractive lenses.

[0040] For the convenience of description, the inventor describes the specific parameter settings of the miniature wide-angle lens in Example 1 (such as the thickness and size of the glass lens) in sequence.

[0041] Table 1 lists various parameters of the corresponding curved surfaces of the glass lens in the miniature wide-angle lens in the first embodiment.

[0042] Table 1.

[0043] Note: OBJ stands for object plane; STOP stands for aperture; IMA stands for image plane; EFFL stands for effective focal length; F / NO stands for F-Number, also known as relative aperture.

[0044] It should be noted that the thickness / gap corresponding to the thirteenth surface in Table 1 is the distance length of the optical back focus in the micro wide-angle lens of the present invention.

[0045] Accordingly, Table 2 shows the main optical parameters of the micro wide-angle lens in the first embodiment.

[0046] Table 2.

[0047] Table 3 shows the corresponding values ​​of the corresponding conditional formula of the micro wide-angle lens in the first embodiment.

[0048] Table 3.

[0049] Table 4 shows the corresponding values ​​of the corresponding relational equation of the micro wide-angle lens in the first embodiment.

[0050] Table 4.

[0051] Tables 1 to 4 above show the lens shape and various properties of the miniature wide-angle lens in the first embodiment. The corresponding values ​​of the corresponding conditional expressions in Table 3 above can first determine the length range and effect of TTL. Based on the corresponding values ​​in Table 3 above, the lens thickness (such as D1, D2) and the lens spacing distance (such as L1, L2) can be controlled by the various relationship expressions in the above table to achieve a miniaturization effect. Therefore, based on the corresponding values ​​in Tables 1 to 4 above, it can be seen that the first embodiment can realize a miniaturized optical wide-angle lens.

[0052] Accordingly, in order to further verify the optical performance of the micro wide-angle lens, such as the depth of field range and effect, edge resolution, etc., the RMS (Root Mean Square Radius) value, astigmatism value, spherical aberration value and chromatic aberration value of the micro wide-angle lens in the first embodiment are also provided, as follows.

[0053] Table 5 shows the RMS values ​​of the micro wide-angle lens in the first embodiment.

[0054] Table 5.

[0055] Table 6 shows the astigmatism values ​​of the miniature wide-angle lens in the first embodiment.

[0056] Table 6.

[0057] Table 7 shows the spherical aberration values ​​of the micro wide-angle lens of the first embodiment.

[0058] Table 7.

[0059] Table 8 shows the chromatic aberration values ​​of the miniature wide-angle lens of the first embodiment.

[0060] Table 8.

[0061] It should be noted that the above RMS value mainly expresses the degree of focusing of light. The smaller the RMS value, the smaller the focused point, and the better the depth of field range and effect. The astigmatism value mainly expresses that when the red and blue wavelengths are closer to the main wavelength (green), the image and color reproduction will be higher, and it is less likely to produce blurred images of the subject. In addition, because wide-angle lenses usually have poor edge resolution (excessive distortion), the spherical aberration coefficient must be controlled to avoid excessive blurring of the edge image. The chromatic aberration value is to control the convergence of the three wavelengths of red, green and blue to reduce the occurrence of purple and green edges.

[0062] Based on the contents disclosed in Tables 5 to 8 above, it is not difficult to see that the micro wide-angle camera prepared in the first embodiment has good optical performance. In practical applications, the edge effect of a general wide-angle lens is not good. If the spherical aberration and astigmatism are not controlled, it is difficult to have a good edge effect. According to the above spherical aberration value and pixel value of the micro wide-angle lens in the first embodiment above, it can be seen that the edge effect of the micro wide-angle lens is better; in addition, the wide-angle lens usually has a larger CRA. If it is used with a sensor with a small CRA, purple and green edges are prone to appear. At this time, chromatic aberration can be used to control and avoid this phenomenon. Referring to Table 8, it can be seen that the chromatic aberration value is not much different from the ideal range, and the purple and green edges of the wide-angle lens can be well controlled.

[0063] Please refer to Figures 7 to 12 , Embodiment 2 of the present invention is: This embodiment provides a miniature wide-angle lens, which is applied in the field of security monitoring, such as Figure 7 As shown, the miniature wide-angle lens adopts an optical structure of seven glass lenses. Specifically, the miniature wide-angle lens includes a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, a fifth lens 5, a sixth lens 6 and a seventh lens 7 which are sequentially distributed along the optical axis from the object side to the image side. The total length of the miniature wide-angle lens in this embodiment is maintained below 14 mm. Moreover, the miniature wide-angle lens in this embodiment can achieve the purpose of high relative brightness and high resolution by arranging a combination of high and low refractive lenses.

[0064] For the convenience of description, the inventor describes the specific parameter settings of the miniature wide-angle lens in the second embodiment (such as the thickness and size of the glass lens) in sequence.

[0065] Table 9 lists various parameters of the corresponding curved surfaces of the glass lens in the micro wide-angle lens in the second embodiment.

[0066] Table 9.

[0067] Note: OBJ stands for object plane; STOP stands for aperture; IMA stands for image plane; EFFL stands for effective focal length; F / NO stands for F-Number, also known as relative aperture.

[0068] It should be noted that the thickness / gap of the thirteenth surface described in the above Table 9 is the distance length of the optical back focus of the micro wide-angle lens of the present invention.

[0069] Table 10 shows the main optical parameters of the micro wide-angle lens in the second embodiment.

[0070] Table 10.

[0071] Table 11 shows the corresponding values ​​of the corresponding conditional formula of the micro wide-angle lens in the second embodiment.

[0072] Table 11.

[0073] Table 12 shows the corresponding values ​​of the corresponding relationship of the micro wide-angle lens in the second embodiment.

[0074] Table 12.

[0075] Tables 9 to 12 above show the lens shape and various properties of the miniature wide-angle lens in the second embodiment. The corresponding values ​​of the corresponding conditional expressions in Table 11 above can first determine the length range and effect of TTL. Based on the corresponding values ​​in Table 11 above, the lens thickness (such as D1, D2) and the lens spacing distance (such as L1, L2) can be controlled by the various relationship expressions in the above table to achieve a miniaturization effect. Therefore, based on the corresponding values ​​of Tables 9 to 12 above, it can be seen that the second embodiment can realize a miniaturized optical wide-angle lens.

[0076] In addition, based on the data in Table 3 in the first embodiment and Table 11 in the second embodiment regarding the conditional expression Tan(Semi-FOV)>TTL / (2×f), the design tolerance of the first embodiment is better than that of the second embodiment.

[0077] Accordingly, in order to further verify the optical performance of the micro wide-angle lens, such as the depth of field range and effect, edge resolution, etc., and to compare the performance of the first and second embodiments in the above parameters, the present invention also provides the RMS value, astigmatism value, spherical aberration value and chromatic aberration value of the micro wide-angle lens in the second embodiment, as follows.

[0078] Table 13 shows the RMS values ​​of the micro wide-angle lens in the second embodiment.

[0079] Table 13.

[0080] Table 14 shows the astigmatism values ​​of the micro wide-angle lens in the second embodiment.

[0081] Table 14.

[0082] Table 15 shows the spherical aberration values ​​of the micro wide-angle lens in the second embodiment.

[0083] Table 15.

[0084] Table 16 shows the chromatic aberration values ​​of the micro wide-angle lens in the second embodiment.

[0085] Table 16.

[0086] Based on the contents disclosed in Tables 13 to 16 above, and by comparing the corresponding parameters in the above Example 1, it can be seen that: (1) From the RMS values ​​in Table 5 of Example 1 and Table 13 of Example 2, it can be seen that even though the aperture of the micro wide-angle lens in Example 1 is larger than that in Example 2, the RMS value of the maximum half-viewing angle 5 of the micro wide-angle lens in Example 1 is still better than that of Example 2. The RMS values ​​of the half-viewing angles 1 to 4 of the micro wide-angle lens in Example 1 are not much different from those in Example 2, that is, the beam convergence and focusing of Example 1 are better than those of Example 2. For relevant information, please refer to Figure 2 and Figure 8 . (2) From the astigmatism values ​​in Table 6 of Example 1 and Table 14 of Example 2, it can be seen that the main wavelength of the present invention is 588nm, the difference between the wavelength 1 and wavelength 3 of Example 1 in the S direction and the wavelength 2 is -7.6um and -7.6um respectively, and the difference between the wavelength 1 and wavelength 3 of Example 1 in the T direction and the wavelength 2 is 8.7um and 0.4um respectively; the difference between the wavelength 1 and wavelength 3 of Example 2 in the S direction and the wavelength 2 is 7.0um and 7.0um respectively, and the difference between the wavelength 1 and wavelength 3 of Example 2 in the T direction and the wavelength 2 is 12um and 1.0um respectively. From the data, it can be seen that the difference in the S direction offset number between the two is not much, but the performance of Example 1 in the T direction is better. For relevant information, please refer to Figure 3 and Fig. 9 ,in Figure 3 as well as Fig. 9The three groups of curves in the figure are the corresponding curves of the three wavelengths of blue, green and red. Because there are two directions of sub-five and arc loss, there are a total of 6 curves. (3) According to the spherical aberration values ​​in Table 7 of Example 1 and Table 15 of Example 2, the maximum difference in the spherical aberration values ​​of wavelengths 1, 2 and 3 of the micro wide-angle lens in Example 1 is 27um, and the maximum difference in the spherical aberration values ​​of wavelengths 1, 2 and 3 of Example 2 is 24um. From the data, it can be seen that Example 2 performs better than Example 1, but the difference is not large. For relevant information, please refer to Figure 5 and Fig.11 . (4) According to the chromatic aberration values ​​in Table 8 of Example 1 and Table 16 of Example 2, the main wavelength of the present invention is 588nm. The difference between the wavelength 1 and wavelength 3 of the micro wide-angle lens in Example 1 and the ideal value is -0.27um and -0.49um respectively. The difference between the wavelength 1 and wavelength 3 of Example 2 and the wavelength 2 in the T direction is 1.50um and -0.33um respectively. From the data, it can be seen that the deviations of the wavelength 1 and wavelength 3 of the micro wide-angle lens in Example 1 are both within 1um, but the deviation of the wavelength 1 of Example 2 is greater than 1um. For relevant information, please refer to Figure 6 and Fig.12 . Embodiments 1 and 2 are basically similar in design, and their optical performance is similar. Embodiment 2 even has a better TTL performance than Embodiment 1. However, in terms of dispersion, the value of wavelength 1 (blue light) of Embodiment 2 is close to twice the size of the ideal SPOT, which greatly increases the risk of purple fringing. The purple fringing phenomenon is difficult to resolve in the image by back-end software (DSP), so Embodiment 1 is preferred. In summary, the TTL and field of view design of Embodiment 2 are better than that of Embodiment 1, but its basic optical performance evaluation is still better than that of Embodiment 1, so Embodiment 1 is preferred in the present invention.

[0087] In summary, the miniature wide-angle lens provided by the present invention: The present invention proposes a miniature wide-angle lens for security monitoring, which adopts an optical structure of seven glass lenses, and the total length of the miniature wide-angle lens is maintained below 14 mm, and through the combination of high and low refractive lenses, the purpose of high relative brightness and high-definition resolution is achieved.

[0088] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention's specification and drawings, or directly or indirectly applied in related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A miniature wide-angle lens, characterized in that: The invention comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens and a seventh lens which are sequentially distributed along the optical axis from the object side to the image side, wherein: The first lens is a convex-concave lens with negative optical power, wherein the first curved surface of the first lens close to the object side is a convex surface, and the second curved surface of the first lens close to the image side is a concave surface; The second lens is a biconvex lens with positive optical power; The third lens is a biconcave lens with negative optical power; The fourth lens is a meniscus lens with positive refractive power, wherein the first curved surface of the fourth lens close to the object side is a concave surface, and the second curved surface close to the image side is a convex surface; The fifth lens is a biconvex lens with positive optical power; The sixth lens is a meniscus lens with positive refractive power, wherein the first curved surface of the sixth lens close to the object side is a concave surface, and the second curved surface close to the image side is a convex surface; The seventh lens is a plano lens with positive refractive power.

2. The miniature wide-angle lens according to claim 1, characterized in that: The curvature radius of the first curved surface of the second lens is a positive value, and the curvature radius of the second curved surface of the second lens is a negative value, wherein the absolute values ​​of the curvature radii of the first curved surface and the second curved surface of the second lens are the same.

3. The miniature wide-angle lens according to claim 1, characterized in that: The curvature radius of the second curved surface of the fifth lens is a negative value, and the curvature radius of the first curved surface of the sixth lens is a negative value, wherein the curvature radius of the second curved surface of the fifth lens and the first curved surface of the sixth lens are the same.

4. The miniature wide-angle lens according to claim 1, characterized in that: The micro wide-angle lens must meet the following conditions: Tan(Semi-FOV)> TTL / (2×f) 17<(f23×f45) / (D2×D3) <22 8.5 <(f45×f56) / (D4×D56) < 9.0 Wherein, Tan(Semi-FOV) represents the tangent value of Semi-FOV, Semi-FOV is the maximum half field angle of the micro wide-angle lens, TTL is the total optical length of the micro wide-angle lens; f is the equivalent focal length of the micro wide-angle lens; Wherein, f23 is the equivalent focal length of the second lens and the third lens; f45 is the equivalent focal length of the fourth lens and the fifth lens; D2 is the center thickness of the second lens on the optical axis; D3 is the center thickness of the third lens on the optical axis; Wherein, f56 is the equivalent focal length of the fifth lens and the sixth lens; D4 is the center thickness of the fourth lens on the optical axis; and D56 is the total center thickness of the fifth lens and the sixth lens on the optical axis.

5. The miniature wide-angle lens according to claim 1, characterized in that: The first lens and the second lens satisfy the following relationship: 0.9<|f1 / f |<1.0; 0.24<|L1 / f1 |<0.3, 0.2<|D1 / f1 |<0.3; 1.2<|f2 / f1 |<1.3; 0.02< L2 / f2 <0.08; 0.6 < D2 / f2 <0.8 Among them, f1 is the focal length of the first lens; f is the equivalent focal length of the micro wide-angle lens; L1 is the distance between the first lens and the second lens; D1 is the center thickness of the first lens on the optical axis; f2 is the focal length of the second lens; L2 is the distance between the second lens and the third lens; D2 is the center thickness of the second lens on the optical axis.

6. The miniature wide-angle lens according to claim 1, characterized in that: The third lens satisfies the following relationship: 1.8<|f3 / f |<1.9 0.02<|L2 / f3|<0.05, 0.09<|D3 / f3|<0.13 Among them, f3 is the focal length of the third lens; f is the equivalent focal length of the micro wide-angle lens; L2 is the distance between the second lens and the third lens; D3 is the center thickness of the third lens on the optical axis.

7. The miniature wide-angle lens according to claim 1, characterized in that: The fourth lens and the fifth lens satisfy the following relationship: 1.6< f4 / f <2.0, 20< f5 / f <23 0.03< L3 / f <0.6, 0.3< D4 / f <0.5 Among them, f4 is the focal length of the fourth lens; f is the equivalent focal length of the micro wide-angle lens; f5 is the focal length of the fifth lens; L3 is the distance between the third lens and the fourth lens; D4 is the center thickness of the fourth lens on the optical axis.

8. The miniature wide-angle lens according to claim 1, characterized in that: The first lens, the fourth lens and the fifth lens are glass lenses made of the same material.

9. The miniature wide-angle lens according to claim 1, characterized in that: The second lens and the sixth lens are glass lenses with a refractive index greater than a first threshold; the third lens is a glass lens with an Abbe number lower than a second threshold.

10. The miniature wide-angle lens according to claim 1, characterized in that: The fifth lens and the sixth lens are cemented lenses.

Images