A fixed focus lens

Abstract

The embodiment of the present invention discloses a fixed-focus lens, which includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens and a ninth lens arranged in sequence from the object side to the image side along the optical axis; the first lens is a plastic aspheric lens with negative optical power, the second lens is a plastic aspheric lens, the third lens is a plastic aspheric lens with positive optical power, the fourth lens is a plastic aspheric lens, the fifth lens is a glass spherical lens with positive optical power, the sixth lens is a glass spherical lens with negative optical power, the seventh lens is a glass spherical lens with positive optical power, the eighth lens is a plastic aspheric lens, and the ninth lens is a plastic aspheric lens. The embodiment of the present invention adopts a mixed combination of 3 spherical glass lenses and 6 aspheric plastic lenses, which can simultaneously take into account the advantages of excellent imaging, compact structure, large light transmission, large target surface, infrared confocal, wide angle, etc.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of optical lenses, and in particular to a fixed-focus lens. Background Art

[0002] In the digital age, the work in the fields of security and public safety is in full swing, so the demand for monitoring facilities is also increasing. Compared with zoom lenses, fixed-focus lenses are simple to design and manufacture, and the images of moving objects taken are clear and stable, with delicate pictures, making them occupy an important position in the security monitoring industry.

[0003] The parameters of the mainstream fixed-focus large-aperture lenses on the market are close to F1.0, and are equipped with 1 / 2.7-inch chips. At night, fill light is required or filters of different thicknesses are switched to ensure the quality of lens imaging at night. There are still problems such as the target surface is not large enough, the clarity is not high enough, and the filters are not universal. Summary of the invention

[0004] The present invention provides a fixed-focus lens, which can achieve the characteristics of ultra-large light transmission, large target area and high definition, and meet the design requirements of infrared confocal.

[0005] An embodiment of the present invention provides a fixed-focus lens, comprising a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens and a ninth lens arranged in sequence from the object side to the image side along an optical axis;

[0006] The first lens is a plastic aspheric lens with negative optical power, the second lens is a plastic aspheric lens, the third lens is a plastic aspheric lens with positive optical power, the fourth lens is a plastic aspheric lens, the fifth lens is a glass spherical lens with positive optical power, the sixth lens is a glass spherical lens with negative optical power, the seventh lens is a glass spherical lens with positive optical power, the eighth lens is a plastic aspheric lens, and the ninth lens is a plastic aspheric lens.

[0007] Optionally, the second lens, the third lens and the fourth lens meet the following conditions:

[0008] -0.45≤Φ2 / Φ≤0.1;

[0009] 0.19≤Φ3 / Φ≤0.48;

[0010] -0.07≤Φ4 / Φ≤0.2;

[0011] Among them, Φ is the overall optical power of the fixed-focus lens, Φ2, Φ3, and Φ4 are the optical power of the second lens, the optical power of the third lens, and the optical power of the fourth lens, respectively.

[0012] Optionally, the second lens, the third lens and the fourth lens meet the following conditions:

[0013] 0.03≤Φ234 / Φ≤0.57;

[0014] Wherein, Φ is the optical focal length of the fixed-focus lens as a whole, and Φ234 is the optical focal length of the combined lens group consisting of the second lens, the third lens and the fourth lens.

[0015] Optionally, the fifth lens, the sixth lens and the seventh lens meet the following conditions:

[0016] 0.19≤Φ5 / Φ≤0.65;

[0017] -0.86≤Φ6 / Φ≤-0.18;

[0018] 0.3≤Φ7 / Φ≤0.69;

[0019] Among them, Φ is the overall optical power of the fixed-focus lens, and Φ5, Φ6, and Φ7 are the optical powers of the fifth lens, the sixth lens, and the seventh lens, respectively.

[0020] Optionally, the fifth lens and the sixth lens are glued to form a glued lens group, or the sixth lens and the seventh lens are glued to form a glued lens group, or the fifth lens, the sixth lens and the seventh lens are glued in sequence to form a glued lens group.

[0021] Optionally, the eighth lens and the ninth lens meet the following conditions:

[0022] -0.81≤Φ8 / Φ≤0.44;

[0023] -0.22≤Φ9 / Φ≤0.66;

[0024] Wherein, Φ is the overall optical power of the fixed-focus lens, and Φ8 and Φ9 are the optical powers of the eighth lens and the ninth lens respectively.

[0025] Optionally, the eighth lens and the ninth lens meet the following conditions:

[0026] -0.1≤Φ89 / Φ≤0.3;

[0027] Wherein, Φ is the optical focal length of the fixed-focus lens as a whole, and Φ89 is the optical focal length of the combined lens group consisting of the eighth lens and the ninth lens.

[0028] Optionally, the fifth lens and the seventh lens satisfy the following conditions:

[0029] 1.4 <Nd5<1.71;

[0030] 52.6 <Vd5<98;

[0031] 1.4 <Nd7<1.71;

[0032] 52.6 <Vd7<98;

[0033] Wherein, Nd5 and Vd5 are the refractive index and Abbe number of the fifth lens respectively, and Nd7 and Vd7 are the refractive index and Abbe number of the seventh lens respectively.

[0034] Optionally, the fixed-focus lens satisfies the following condition: 0.005≤(C23+C34) / D1≤0.1;

[0035] Wherein, C23 is the air gap between the second lens and the third lens; C34 is the air gap between the third lens and the fourth lens, and D1 is the effective diameter of the system light on the object side of the first lens.

[0036] Optionally, the fixed-focus lens satisfies the following condition: 1°≤CRA max ≤16°;

[0037] Among them, CRA max It is the maximum incident angle of the main light in the fixed-focus lens entering the electronic photosensitive element.

[0038] An embodiment of the present invention provides a fixed-focus lens, comprising a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens and a ninth lens arranged in sequence from the object side to the image side along the optical axis; the first lens is a plastic aspheric lens with negative optical power, the second lens is a plastic aspheric lens, the third lens is a plastic aspheric lens with positive optical power, the fourth lens is a plastic aspheric lens, the fifth lens is a glass spherical lens with positive optical power, the sixth lens is a glass spherical lens with negative optical power, the seventh lens is a glass spherical lens with positive optical power, the eighth lens is a plastic aspheric lens, and the ninth lens is a plastic aspheric lens. The embodiment of the present invention adopts a mixed combination of 3 spherical glass lenses and 6 aspherical plastic lenses. By reasonably allocating parameters such as the material, optical focal length, center thickness of each lens and on-axis spacing between each lens, the aberration of the lens in the wavelength range of 436 to 850 nm can be reasonably corrected and balanced, and the aperture F1.0 is achieved. The total optical length is not more than 30 mm, the imaging target surface is >φ9.2 mm, and a 1 / 1.8-inch chip can be matched to meet high-definition image quality requirements. It can also ensure the infrared confocal function at a low cost, and ultimately enable the above-mentioned fixed-focus lens system to achieve the advantages of excellent imaging, compact structure, large light transmission, large target surface, infrared confocal, wide angle, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 is a structural schematic diagram of a fixed-focus lens provided in Embodiment 1 of the present invention;

[0040] Figure 2 yes Figure 1 Spherical aberration curve of the fixed focal length lens shown;

[0041] Figure 3 is a structural schematic diagram of a fixed-focus lens provided in Embodiment 2 of the present invention;

[0042] Figure 4 yes Figure 3 Spherical aberration curve of the fixed focal length lens shown;

[0043] Figure 5 is a structural schematic diagram of a fixed-focus lens provided in Embodiment 3 of the present invention;

[0044] Figure 6 yes Figure 5 Spherical aberration curve of the fixed focal length lens shown;

[0045] Figure 7 is a structural schematic diagram of a fixed-focus lens provided by Embodiment 4 of the present invention;

[0046] Figure 8 yes Figure 7 Spherical aberration curve of the fixed focal length lens shown;

[0047] Fig. 9 is a structural schematic diagram of a fixed-focus lens provided in Embodiment 5 of the present invention;

[0048] Fig.10 yes Fig. 9 Spherical aberration graph for the fixed focal length lens shown. DETAILED DESCRIPTION

[0049] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0050] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. It should be noted that the directional words such as "upper", "lower", "left", "right" and the like described in the embodiments of the present invention are described at the angles shown in the accompanying drawings and should not be understood as limitations on the embodiments of the present invention. In addition, in the context, it is also necessary to understand that when it is mentioned that an element is formed "on" or "under" another element, it can not only be directly formed "on" or "under" another element, but also indirectly formed "on" or "under" another element through an intermediate element. The terms "first", "second", etc. are only used for descriptive purposes and do not represent any order, quantity or importance, but are only used to distinguish different components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood in specific circumstances.

[0051] The term “including” and its variations used in the present invention are open inclusions, that is, “including but not limited to.” The term “based on” means “based at least in part on.” The term “one embodiment” means “at least one embodiment.”

[0052] It should be noted that the concepts such as "first" and "second" mentioned in the present invention are only used to distinguish the corresponding contents, and are not used to limit the order or interdependence.

[0053] It should be noted that the modifications of "one" and "plurality" mentioned in the present invention are illustrative rather than restrictive, and those skilled in the art should understand that, unless otherwise clearly indicated in the context, it should be understood as "one or more".

[0054] Figure 1 is a schematic diagram of the structure of a fixed-focus lens provided in Embodiment 1 of the present invention, with reference to Figure 1 The fixed-focus lens comprises a first lens 10, a second lens 20, a third lens 30, a fourth lens 40, a fifth lens 50, a sixth lens 60, a seventh lens 70, an eighth lens 80 and a ninth lens 90 which are arranged in sequence from the object side to the image side along the optical axis;

[0055] The first lens 10 is a plastic aspheric lens with negative power, the second lens 20 is a plastic aspheric lens, the third lens 30 is a plastic aspheric lens with positive power, the fourth lens 40 is a plastic aspheric lens, the fifth lens 50 is a glass spherical lens with positive power, the sixth lens 60 is a glass spherical lens with negative power, the seventh lens 70 is a glass spherical lens with positive power, the eighth lens 80 is a plastic aspheric lens, and the ninth lens 90 is a plastic aspheric lens.

[0056] First of all, for optical lenses, the focal length is equal to the difference between the convergence of the image-side beam and the convergence of the object-side beam, which characterizes the ability of the optical system to deflect light. The larger the absolute value of the focal length, the stronger the ability to bend light, and the smaller the absolute value of the focal length, the weaker the ability to bend light. When the focal length is a positive number, the refraction of light is convergent; when the focal length is a negative number, the refraction of light is divergent. The focal length can be used to characterize a refractive surface of a lens (i.e., a surface of a lens), can be used to characterize a lens, and can also be used to characterize a system formed by multiple lenses (i.e., a lens group).

[0057] In the fixed-focus lens provided in this embodiment, each lens can be fixed to a lens barrel ( Figure 1 (not shown) in the Figure 1 As shown, the first lens 10 and the sixth lens 60 are set as negative power lenses, and the third lens 30, the fifth lens 50 and the seventh lens 70 are set as positive power lenses. Through the coordination of the power of these lenses, the entire lens can achieve the characteristics of large aperture and large target surface, achieve ultra-large light transmission, and adapt to larger-sized imaging chips. In addition, the three lenses in the middle position of the fifth lens 50, the sixth lens 60 and the seventh lens 70 are glass spherical lenses, and the other lenses are plastic aspherical lenses. The above three glass spherical lenses can be used to reduce the focal length difference of the entire lens for visible light and infrared light, ensuring day and night confocality. At the same time, by coordinating with other plastic aspherical lenses, various aberrations of the entire lens can be corrected, so that the aberrations of the lens in the wavelength range of 436 to 850nm are reasonably corrected and balanced, and high-definition image quality requirements are achieved on the basis of the above ultra-large light transmission, large target surface, and day and night confocality. In addition, since the entire fixed-focus lens is formed by a glass-plastic hybrid method of 3G6P, i.e., three glass lenses and six plastic lenses, the cost can be reduced to a certain extent. At a relatively low cost, the above-mentioned ultra-large light transmission, large target surface, high definition, and day and night confocal lens design can be achieved to meet the video or image monitoring needs in the security and public safety fields. I would also like to add that since the first lens close to the object surface, i.e., the first lens 10, is set to be a negative optical focal length lens, it can ensure that the lens can pass a large angle of light, ensure the viewing angle of the lens, and take into account the characteristics of wide angle.

[0058] It should be added that we continue to refer to Figure 1 The fixed-focus lens may be provided with a filter 100 after the ninth lens 90 along the optical axis. The filter 100 may be used to filter out interfering light. For example, an ultraviolet filter may prevent interference from ultraviolet rays and ensure the color reproduction of the photo. It may also be used to control light, especially excessively bright light. For example, a polarizing filter may reduce reflections, and an impurity filter may eliminate blue or green impurities to make the picture clear.

[0059] In an optional embodiment, the second lens 20, the third lens 30 and the fourth lens 40 can be arranged to satisfy the following conditions: -0.45≤Φ2 / Φ≤0.1; 0.19≤Φ3 / Φ≤0.48; -0.07≤Φ4 / Φ≤0.2; wherein Φ is the overall optical focal length of the fixed-focus lens, and Φ2, Φ3 and Φ4 are the optical focal lengths of the second lens 20, the third lens 30 and the fourth lens 40, respectively.

[0060] Further optionally, the second lens 20, the third lens 30 and the fourth lens 40 can be set to meet the following condition: 0.03≤Φ234 / Φ≤0.57; wherein Φ is the optical focal length of the fixed-focus lens as a whole, and Φ234 is the optical focal length of the combined lens group consisting of the second lens 20, the third lens 30 and the fourth lens 40.

[0061] Further optionally, the second lens 20 may be configured as a meniscus lens, and the fourth lens 40 may be configured as a meniscus lens.

[0062] As described above, when the optical focal lengths of the second lens 20, the third lens 30 and the fourth lens 40 meet the above-mentioned optical focal length range, and are combined with the specific shapes of the second lens 20 and the fourth lens 40, not only can the light deviation angle be effectively reduced, but it is also beneficial to correct the system aberrations and to achieve a large target surface.

[0063] In an optional embodiment, the fifth lens 50, the sixth lens 60 and the seventh lens 70 may be arranged to satisfy the following conditions: 0.19≤Φ5 / Φ≤0.65; -0.86≤Φ6 / Φ≤-0.18; 0.3≤Φ7 / Φ≤0.69; wherein Φ is the optical focal length of the fixed-focus lens as a whole, and Φ5, Φ6 and Φ7 are the optical focal lengths of the fifth lens 50, the sixth lens 60 and the seventh lens 70 respectively.

[0064] Further optionally, the fifth lens 50 may be configured as a biconvex glass spherical lens with positive power, the sixth lens 60 may be configured as a glass spherical lens with negative power, and the seventh lens 70 may be configured as a biconvex glass spherical lens with positive power.

[0065] Further optionally, the fifth lens 50 and the sixth lens 60 are cemented to form a cemented lens group, or the sixth lens 60 and the seventh lens 70 are cemented to form a cemented lens group, or the fifth lens 50, the sixth lens 60 and the seventh lens 70 are cemented in sequence to form a cemented lens group.

[0066] As described above, when the fifth lens 50, the sixth lens 60 and the seventh lens 70 meet the above-mentioned optical focal length range, by coordinating the specific shapes and bonding methods of the fifth lens 50, the sixth lens 60 and the seventh lens 70, it can be ensured that the lens can still be used normally in high and low temperature environments.

[0067] In an optional embodiment, the eighth lens 80 and the ninth lens 90 can be set to satisfy the following conditions: -0.81 ≤ Φ8 / Φ ≤ 0.44; -0.22 ≤ Φ9 / Φ ≤ 0.66; where Φ is the overall optical power of the fixed-focus lens, and Φ8 and Φ9 are the optical powers of the eighth lens 80 and the ninth lens 90 respectively.

[0068] Further optionally, the eighth lens 80 and the ninth lens 90 satisfy the following conditions: -0.1 ≤ Φ89 / Φ ≤ 0.3; where Φ is the overall optical power of the fixed-focus lens, and Φ89 is the optical power of the combined lens group composed of the eighth lens 80 and the ninth lens 90.

[0069] As described above, when the optical powers of the eighth lens 80 and the ninth lens 90 satisfy the above ranges, it is beneficial to correct the system aberration, thereby promoting the improvement of image quality.

[0070] In an optional embodiment, the fifth lens 50 and the seventh lens 70 can be set to satisfy the following conditions: 1.4 < Nd5 < 1.71; 52.6 < Vd5 < 98; 1.4 < Nd7 < 1.71; 52.6 < Vd7 < 98; where Nd5 and Vd5 are the refractive index and Abbe number of the fifth lens 50 respectively, and Nd7 and Vd7 are the refractive index and Abbe number of the seventh lens 70 respectively. When the fifth lens 50 and the seventh lens 70 satisfy the above refractive index and Abbe number ranges, the chromatic aberration of the entire optical system can be guaranteed, thereby realizing infrared confocal and making the filter more versatile.

[0071] In an optional embodiment, the fixed-focus lens can be set to satisfy the following conditions: 0.005 ≤ (C23 + C34) / D1 ≤ 0.1; where C23 is the air gap between the second lens 20 and the third lens 30; C34 is the air gap between the third lens 30 and the fourth lens 40, and D1 is the effective diameter of the system light ray on the object side of the first lens 10. At this time, the structure of the optical lens is more compact and is beneficial to the correction of system aberration.

[0072] In an optional embodiment, the fixed-focus lens can be set to satisfy the following conditions: 1° ≤ CRA max ≤ 16°; where CRA max is the maximum incident angle of the principal ray in the fixed-focus lens incident on the electron photosensitive element. At this time, the fixed-focus lens can have a larger target surface and can have a higher matching with the imaging chip.

[0073] The fixed-focus lens provided in the embodiment of the present invention adopts a mixed combination of three spherical glass lenses and six aspherical plastic lenses. By reasonably allocating parameters such as the material, optical focal length, center thickness of each lens and on-axis spacing between each lens, the aberration of the lens in the wavelength range of 436 to 850 nm can be reasonably corrected and balanced, and the aperture F1.0 is achieved. The total optical length is not more than 30 mm, the imaging target surface is >φ9.2 mm, and a 1 / 1.8-inch chip can be matched to meet the high-definition image quality requirements. It can also ensure the infrared confocal function at a low cost, and ultimately the above-mentioned fixed-focus lens system can achieve the advantages of excellent imaging, compact structure, large light transmission, large target surface, infrared confocal, wide angle, etc.

[0074] Based on the same concept above, the present invention provides five different specific embodiments, and their optical power relationships and related physical optical parameter design ranges are shown in Table 1:

[0075] Table 1 Relationship between the focal powers of the lenses and the design values ​​of the relevant physical optical parameters in the five embodiments

[0076] Example 1 Example 2 Example 3 Example 4 Example 5 Lower limit Upper limit Φ2 / Φ -0.10 -0.37 -0.10 -0.13 0.02 -0.45 0.10 Φ3 / Φ 0.23 0.34 0.44 0.38 0.33 0.19 0.48 Φ4 / Φ -0.03 0.16 -0.02 0.09 0.08 -0.07 0.20 Φ5 / Φ 0.34 0.58 0.31 0.36 0.26 0.19 0.65 Φ6 / Φ -0.28 -0.39 -0.76 -0.72 -0.69 -0.86 -0.18 Φ7 / Φ 0.55 0.35 0.63 0.61 0.50 0.30 0.69 Φ8 / Φ -0.62 -0.32 0.10 0.24 0.26 -0.81 0.44 Φ9 / Φ 0.53 0.28 0.12 -0.09 -0.05 -0.22 0.66 Φ234 / Φ 0.11 0.19 0.37 0.41 0.49 0.03 0.57 Φ89 / Φ 0.03 -0.04 0.24 0.16 0.22 -0.10 0.30 (C23+C34) / D1 0.06 0.04 0.03 0.08 0.02 0.005 0.1 <![CDATA[CRA max ]]> 10.49 10.53 3.90 9.08 11.87 1 16 Nd5 1.55 1.53 1.42 1.55 1.66 1.4 1.71 Nd7 1.55 1.66 1.55 1.55 1.42 1.4 1.71 Vd5 60 81 97 76 63.8 52.6 98 Vd7 84 64.2 72.69 60 97 52.6 98

[0077] refer to Figure 1 In the first embodiment of the present invention, the second lens 20, the fourth lens 40 and the eighth lens 80 are all negative power lenses, and the ninth lens 90 is a positive power lens. In addition, the power, size ratio and angle parameters of each lens and the combined lens meet those shown in Table 1 above, which will not be repeated here.

[0078] In this first embodiment, by adopting a structure of mixing 3 glass spherical lenses and 6 plastic aspherical lenses, and by reasonably allocating the optical focal length, surface shape, Abbe number, etc. of each lens, the following design values ​​can be achieved: the focal length f is 4.108mm, the F# is 1.01, and the corresponding angle of φ9.2mm is 138.34°.

[0079] like Figure 1 The parameter design values ​​of each lens in the fixed-focus lens of the first embodiment are shown in Table 2:

[0080] Table 2: Design values ​​of each lens of the fixed focus lens in Example 1

[0081]

[0082] The surface numbers in Table 2 are numbered according to the order of the surfaces of each lens. "OBJ" represents the object surface of the fixed-focus lens; "STO" represents the aperture of the fixed-focus lens; "IMA" represents the image surface of the fixed-focus lens; the radius of curvature represents the curvature of the lens surface, a positive value represents that the surface is bent toward the image side, and a negative value represents that the surface is bent toward the object side, where "Infinity" represents that the surface is a plane, the radius of curvature is infinite, and the distance is infinite; the thickness represents the central axial distance from the current surface to the next surface, the refractive index represents the ability of the material between the current surface and the next surface to deflect light, and a blank space represents that the current position is air, and the refractive index is 1; the Abbe number represents the dispersion characteristics of the material between the current surface and the next surface to light, and a blank space represents that the current position is air; dP x,y It represents the deviation characteristics of special dispersion compared with "normal glass"; the semi-aperture represents the effective diameter of the light of the lens; the k value represents the numerical value of the cone coefficient of the aspheric surface.

[0083] Where, the relative partial dispersion P for wavelengths x and y is x,y It is expressed as follows:

[0084] P x,y =(n x -n y )-(n F -n C )

[0085] P′ x,y =(n x -n y )-(n F′ -n C′ )

[0086] The data sheet gives the P by grade. s,t , P C,s , P d,C , P e,d , P g,F , P′ s,t , P′ C,s , P′ d,C , P′ e,d , P′ g,F .

[0087] According to the Abbe formula, for most so-called "normal glass" (H-K6 and F4 of Chengdu Guangming are selected as "normal glass"), the following linear relationship is established:

[0088] P x,y =m x,y *v d +b x,y

[0089] This linear relationship is based on Px,y is the vertical axis, v d It is represented by the horizontal axis, where m x,y is the slope, b x,y is the intercept.

[0090] As is known to all, the correction of the secondary spectrum, i.e. the achromatization of more than two wavelengths, requires at least one glass that does not conform to the above formula (i.e. its P x,y The deviation value deviates from Abbe's empirical formula), and its deviation value is expressed as dP x,y If it is expressed, then each P x,y -v d The point is shifted by dP relative to the "normal line" that conforms to the above formula x,y In this way, the dP of each grade of glass x,y The value can be calculated using the following formula:

[0091] P x,y =m x,y *v d +n x,y +dP x,y

[0092] Therefore, dP x,y It quantitatively represents the deviation characteristics of special dispersion compared with "normal glass".

[0093] dP g,F The calculation formula is as follows: dP g,F =P g,F -0.6457+0.001703*v d .

[0094] The aspheric cone coefficient can be defined by the following aspheric formula, but is not limited to the following representation method:

[0095]

[0096] Among them, z is the axial vector height of the aspheric surface in the Z direction; r is the height of the aspheric surface; c is the curvature of the fitted sphere, which is the inverse of the radius of curvature; k is the fitting cone coefficient; the 4th, 6th, 8th, 10th, 12th, and 14th order coefficients of the AF aspheric polynomial.

[0097] The even-order coefficients of each aspheric surface in the above-mentioned embodiment 1 are shown in Table 3:

[0098] Table 3 Aspheric surface parameters

[0099] Surface number A B C D E F S1 -3.03906E-04 3.11578E-06 1.62370E-08 -9.03993E-10 1.05039E-11 -3.84137E-14 S2 3.03971E-03 -2.03960E-05 1.45942E-05 -1.34165E-06 7.12225E-08 -8.77631E-10 S3 4.14322E-03 -3.23579E-04 2.22292E-05 -1.09703E-06 1.90135E-08 1.00250E-10 S4 1.22319E-03 -8.76082E-05 1.05685E-05 -3.52958E-07 -1.14428E-08 1.51984E-09 S5 -4.40948E-03 -4.90808E-05 2.76981E-07 1.19831E-07 1.11916E-08 -3.54163E-10 S6 -1.78445E-03 -8.07713E-05 1.86171E-06 4.63794E-08 1.55021E-09 6.59075E-11 S7 4.72955E-04 2.76735E-05 -1.21270E-06 -2.21678E-09 3.57418E-09 1.19012E-10 S8 5.03036E-04 2.16844E-05 1.01798E-06 -1.54606E-08 -1.94237E-09 7.64594E-11 S14 1.50065E-04 -1.70256E-05 3.66027E-07 9.45851E-09 -6.19860E-10 2.68541E-12 S15 7.11300E-04 -1.44620E-05 1.99726E-07 2.47508E-08 -6.41544E-10 -3.56491E-11 S16 3.77800E-04 2.14146E-06 1.14610E-06 -3.65746E-09 -7.46696E-10 2.71877E-11 S17 1.79304E-05 8.05501E-06 1.29101E-06 -2.60970E-08 -4.14222E-10 6.97380E-11

[0100] Among them, -3.03906E-04 means that the coefficient A of the surface number S1 is -3.03906*10 -4 , and so on.

[0101] Figure 2 yes Figure 1 The spherical aberration curve of the fixed focus lens shown is Figure 2 The vertical axis is a dimensionless quantity, which represents the normalized entrance pupil radius. The vertical vertex represents the maximum pupil radius. The horizontal axis represents the distance from the image sensor surface to the focus on each wavelength axis. In other words, it can be understood as the offset from the ideal focus, in millimeters (mm). The different linear curves in the figure represent different wavelengths of system imaging. Figure 2 It can be seen that the axial aberrations of different wavelengths are all controlled within the range of (-0.05mm, +0.05mm), indicating that the spherical aberration of the fixed-focus lens at each wavelength is well controlled and can meet the needs of wide-spectrum applications, which also reflects that the fixed-focus lens has day and night confocal function.

[0102] Figure 3 is a schematic diagram of the structure of a fixed-focus lens provided in Embodiment 2 of the present invention, with reference to Figure 3 In the second embodiment of the present invention, the second lens 20 and the eighth lens 80 are negative power lenses, and the fourth lens 40 and the ninth lens 90 are positive power lenses. In addition, the power, size ratio and angle parameters of each lens and the combined lens meet those shown in Table 1 above, which will not be repeated here.

[0103] In this second embodiment, by adopting a structure of mixing 3 glass spherical lenses and 6 plastic aspherical lenses, and by reasonably allocating the optical focal length, surface shape, Abbe number, etc. of each lens, the following design values ​​can be achieved: the focal length f is 4.598mm, the F# is 1.08, and the corresponding angle of φ9.2mm is 145.9°.

[0104] like Figure 3 The parameter design values ​​of each lens in the fixed-focus lens of the second embodiment are shown in Table 4:

[0105] Table 4: Design values ​​of each lens in the fixed focus lens of Example 2

[0106]

[0107]

[0108] The surface numbers in Table 4 are numbered according to the order of the surfaces of each lens. "OBJ" represents the object surface of the fixed-focus lens; "STO" represents the aperture of the fixed-focus lens; "IMA" represents the image surface of the fixed-focus lens; the radius of curvature represents the curvature of the lens surface, a positive value represents that the surface is bent toward the image side, and a negative value represents that the surface is bent toward the object side, where "Infinity" represents that the surface is a plane, the radius of curvature is infinite, and the distance is infinite; the thickness represents the central axial distance from the current surface to the next surface, the refractive index represents the ability of the material between the current surface and the next surface to deflect light, and a blank space represents that the current position is air, and the refractive index is 1; the Abbe number represents the dispersion characteristics of the material between the current surface and the next surface to light, and a blank space represents that the current position is air; dP x,y It represents the deviation characteristics of special dispersion compared with "normal glass"; the semi-aperture represents the effective diameter of the light of the lens; the k value represents the numerical value of the cone coefficient of the aspheric surface.

[0109] Where, the relative partial dispersion P for wavelengths x and y is x,y It is expressed as follows:

[0110] P x,y =(n x -n y )-(n F -n C )

[0111] P′ x,y =(n x -n y )-(n F′ -n C′ )

[0112] The data sheet gives the P by grade. s,t , P C,s , P d,C , P e,d , P g,F , P′ s,t , P′ C,s , P′ d,C , P′ e,d , P′ g,F .

[0113] According to the Abbe formula, for most so-called "normal glass" (H-K6 and F4 of Chengdu Guangming are selected as "normal glass"), the following linear relationship is established:

[0114] P x,y =m x,y *v d +b x,y

[0115] This linear relationship is based on Px,y is the vertical axis, v d It is represented by the horizontal axis, where m x,y is the slope, b x,y is the intercept.

[0116] As is known to all, the correction of the secondary spectrum, i.e. the achromatization of more than two wavelengths, requires at least one glass that does not conform to the above formula (i.e. its P x,y The deviation value deviates from Abbe's empirical formula), and its deviation value is expressed as dP x,y If it is expressed, then each P x,y -v d The point is shifted by dP relative to the "normal line" that conforms to the above formula x,y In this way, the dP of each grade of glass x,y The value can be calculated using the following formula:

[0117] P x,y =m x,y *v d +b x,y +dP x,y

[0118] Therefore, dP x,y It quantitatively represents the deviation characteristics of special dispersion compared with "normal glass".

[0119] dP g,F The calculation formula is as follows: dP g,F =P g,F -0.6457+0.001703*v d .

[0120] The aspheric cone coefficient can be defined by the following aspheric formula, but is not limited to the following representation method:

[0121]

[0122] Among them, z is the axial vector height of the aspheric surface in the Z direction; r is the height of the aspheric surface; c is the curvature of the fitted sphere, which is the inverse of the radius of curvature; k is the fitting cone coefficient; the 4th, 6th, 8th, 10th, 12th, and 14th order coefficients of the AF aspheric polynomial.

[0123] The even-order coefficients of each aspheric surface in the above-mentioned embodiment 2 are shown in Table 5:

[0124] Table 5 Aspheric surface parameters

[0125]

[0126]

[0127] Among them, -1.14043E-04 means that the coefficient A of the surface number S1 is -1.14043*10 -4 , and so on.

[0128] Figure 4 yes Figure 3 The spherical aberration curve of the fixed focus lens shown is Figure 4 The vertical axis is a dimensionless quantity, which represents the normalized entrance pupil radius. The vertical vertex represents the maximum pupil radius. The horizontal axis represents the distance from the image sensor surface to the focus on each wavelength axis. In other words, it can be understood as the offset from the ideal focus, in millimeters (mm). The different linear curves in the figure represent different wavelengths of system imaging. Figure 4 It can be seen that the axial aberrations of different wavelengths are all controlled within the range of (-0.05mm, +0.05mm), indicating that the spherical aberration of the fixed-focus lens at each wavelength is well controlled and can meet the needs of wide-spectrum applications, which also reflects that the fixed-focus lens has day and night confocal function.

[0129] Figure 5 is a schematic diagram of the structure of a fixed-focus lens provided in Embodiment 3 of the present invention, with reference to Figure 5 In the third embodiment of the present invention, the second lens 20 and the fourth lens 40 are negative power lenses, and the eighth lens 80 and the ninth lens 90 are positive power lenses. In addition, the power, size ratio and angle parameters of each lens and the combined lens meet those shown in Table 1 above, which will not be described here.

[0130] In this third embodiment, by adopting a mixed structure of 3 glass spherical lenses and 6 plastic aspherical lenses, and by reasonably allocating the optical focal length, surface shape, Abbe number, etc. of each lens, the following design values ​​can be achieved: the focal length f is 4.363mm, the F# is 1.08, and the corresponding angle of φ9.2mm is 139.85°.

[0131] like Figure 5 The parameter design values ​​of each lens in the fixed-focus lens of the third embodiment are shown in Table 6:

[0132] Table 6: Design values ​​of each lens in the fixed focus lens of Example 3

[0133]

[0134]

[0135] The surface numbers in Table 6 are numbered according to the order of the surfaces of each lens. "OBJ" represents the object surface of the fixed-focus lens; "STO" represents the aperture of the fixed-focus lens; "IMA" represents the image surface of the fixed-focus lens; the radius of curvature represents the curvature of the lens surface, a positive value represents that the surface is bent toward the image side, and a negative value represents that the surface is bent toward the object side, where "Infinity" represents that the surface is a plane, the radius of curvature is infinite, and the distance is infinite; the thickness represents the central axial distance from the current surface to the next surface, the refractive index represents the ability of the material between the current surface and the next surface to deflect light, and a blank represents that the current position is air, and the refractive index is 1; the Abbe number represents the dispersion characteristics of the material between the current surface and the next surface to light, and a blank represents that the current position is air; dP x,y It represents the deviation characteristics of special dispersion compared with "normal glass"; the semi-aperture represents the effective diameter of the light of the lens; the k value represents the numerical value of the cone coefficient of the aspheric surface.

[0136] Where, the relative partial dispersion P for wavelengths x and y is x,y It is expressed as follows:

[0137] P x,y =(n x -n y )-(n F -n C )

[0138] P′ x,y =(n x -n y )-(n F′ -n C′ )

[0139] The data sheet gives the P by grade. s,t , P C,s , P d,c , P e,d , P g,F , P′ s,t , P′ C,s , P′ d,C , P′ e,d , P′ g,F .

[0140] According to the Abbe formula, for most so-called "normal glass" (H-K6 and F4 of Chengdu Guangming are selected as "normal glass"), the following linear relationship is established:

[0141] P x,y =m x,y *v d +n x,y

[0142] This linear relationship is based on Px,y is the vertical axis, v d It is represented by the horizontal axis, where m x,y is the slope, b x,y is the intercept.

[0143] As is known to all, the correction of the secondary spectrum, i.e. the achromatization of more than two wavelengths, requires at least one glass that does not conform to the above formula (i.e. its P x,y The deviation value deviates from Abbe's empirical formula), and its deviation value is expressed as dP x,y If it is expressed, then each P x,y -v d The point is shifted by dP relative to the "normal line" that conforms to the above formula x,y In this way, the dP of each grade of glass x,y The value can be calculated using the following formula:

[0144] P x,y =m x,y *v d +b x,y +dP x,y

[0145] Therefore, dP x,y It quantitatively represents the deviation characteristics of special dispersion compared with "normal glass".

[0146] dP g,F The calculation formula is as follows: dP g,F =P g,F -0.6457+0.001703*v d .

[0147] The aspheric cone coefficient can be defined by the following aspheric formula, but is not limited to the following representation method:

[0148]

[0149] Among them, z is the axial vector height of the aspheric surface in the Z direction; r is the height of the aspheric surface; c is the curvature of the fitted sphere, which is the inverse of the radius of curvature; k is the fitting cone coefficient; the 4th, 6th, 8th, 10th, 12th, and 14th order coefficients of the AF aspheric polynomial.

[0150] The even-order coefficients of each aspheric surface in the above-mentioned embodiment 3 are shown in Table 7:

[0151] Table 7 Aspheric surface parameters

[0152] Surface number A B C D E F S1 3.74027E-06 2.61037E-06 -6.13888E-08 -3.19991E-11 4.27036E-11 -4.76645E-13 S2 2.71374E-03 -2.64189E-05 1.52915E-06 -2.08126E-08 9.34450E-09 -1.26490E-09 S3 2.17338E-03 -2.76181E-04 1.25618E-05 2.89258E-08 -2.92137E-09 2.45826E-10 S4 1.41522E-03 -4.71746E-05 3.75079E-06 8.87117E-08 -4.23384E-09 3.97104E-10 S5 -1.42575E-03 1.32550E-06 -2.18232E-07 3.63209E-08 5.64245E-10 -4.39131E-11 S6 -1.66177E-03 1.69741E-05 -9.00853E-07 1.42009E-08 1.72504E-10 -3.52032E-12 S7 6.48130E-04 1.23084E-05 -2.14176E-06 2.23818E-08 8.69006E-10 9.49276E-12 S8 7.85138E-04 8.70709E-06 -1.61324E-06 6.78309E-09 1.07542E-09 -9.44417E-12 S14 -2.07937E-04 -5.03686E-05 8.22800E-07 -1.74945E-08 -8.90248E-10 1.30720E-11 S15 -4.04931E-04 -4.29474E-06 -1.02597E-07 1.22413E-08 -3.74742E-10 4.73052E-12 S16 -1.64394E-03 -2.88840E-05 1.08785E-06 1.21345E-08 -1.05337E-09 1.78990E-11 S17 -2.18777E-03 -3.76616E-06 1.14651E-06 -3.02742E-08 8.91755E-11 6.72727E-12

[0153] Among them, 3.74027E-06 means that the coefficient A of the surface number S1 is 3.74027*10 -6 , and so on.

[0154] Figure 6 yes Figure 5 The spherical aberration curve of the fixed focus lens shown is Figure 6 The vertical axis is a dimensionless quantity, which represents the normalized entrance pupil radius. The vertical vertex represents the maximum pupil radius. The horizontal axis represents the distance from the image sensor surface to the focus on each wavelength axis. In other words, it can be understood as the offset from the ideal focus, in millimeters (mm). The different linear curves in the figure represent different wavelengths of system imaging. Figure 6 It can be seen that the axial aberrations of different wavelengths are all controlled within the range of (-0.05mm, +0.05mm), indicating that the spherical aberration of the fixed-focus lens at each wavelength is well controlled and can meet the needs of wide-spectrum applications, which also reflects that the fixed-focus lens has day and night confocal function.

[0155] Figure 7 is a structural schematic diagram of a fixed-focus lens provided in Embodiment 4 of the present invention, with reference to Figure 7 In the fourth embodiment of the present invention, the second lens 20 and the ninth lens 90 are negative power lenses, and the fourth lens 40 and the eighth lens 80 are positive power lenses. In addition, the power, size ratio and angle parameters of each lens and the combined lens meet those shown in Table 1 above, which will not be repeated here.

[0156] In this fourth embodiment, by adopting a mixed structure of 3 glass spherical lenses and 6 plastic aspherical lenses, and by reasonably allocating the optical focal length, surface shape, Abbe number, etc. of each lens, the following design values ​​can be achieved: the focal length f is 4.593mm, the F# is 1.08, and the corresponding angle of φ9.2mm is 140.59°.

[0157] like Figure 7 The parameter design values ​​of each lens in the fixed-focus lens of the fourth embodiment are shown in Table 8:

[0158] Table 8: Design values ​​of each lens in the fixed focus lens in Example 4

[0159]

[0160] The surface numbers in Table 8 are numbered according to the order of the surfaces of each lens. "OBJ" represents the object surface of the fixed-focus lens; "STO" represents the aperture of the fixed-focus lens; "IMA" represents the image surface of the fixed-focus lens; the radius of curvature represents the curvature of the lens surface, a positive value represents that the surface is bent toward the image side, and a negative value represents that the surface is bent toward the object side, where "Infinity" represents that the surface is a plane, the radius of curvature is infinite, and the distance is infinite; the thickness represents the central axial distance from the current surface to the next surface, the refractive index represents the ability of the material between the current surface and the next surface to deflect light, and a blank represents that the current position is air, and the refractive index is 1; the Abbe number represents the dispersion characteristics of the material between the current surface and the next surface to light, and a blank represents that the current position is air; dP x,y It represents the deviation characteristics of special dispersion compared with "normal glass"; the semi-aperture represents the effective diameter of the light of the lens; the k value represents the numerical value of the cone coefficient of the aspheric surface.

[0161] Where, the relative partial dispersion P for wavelengths x and y is x,y It is expressed as follows:

[0162] P x,y =(n x -n y )-(n F -n C )

[0163] P′ x,y =(n x -n y )-(n F′ -n C′ )

[0164] The data sheet gives the P by grade. s,t , P C,s , P d,C , P e,d , P g,F , P′ s,t , P′ c,s , P′ d,C , P′ e,d , P′ g,F .

[0165] According to the Abbe formula, for most so-called "normal glass" (H-K6 and F4 of Chengdu Guangming are selected as "normal glass"), the following linear relationship is established:

[0166] P x,y =m x,y *v d +b x,y

[0167] This linear relationship is based on Px,y is the vertical axis, v d It is represented by the horizontal axis, where m x,y is the slope, b x,y is the intercept.

[0168] As is known to all, the correction of the secondary spectrum, i.e. the achromatization of more than two wavelengths, requires at least one glass that does not conform to the above formula (i.e. its P x,y The deviation value deviates from Abbe's empirical formula), and its deviation value is expressed as dP x,y If it is expressed, then each P x,y -v d The point is shifted by dP relative to the "normal line" that conforms to the above formula x,y In this way, the dP of each grade of glass x,y The value can be calculated using the following formula:

[0169] P x,y =m x,y *v d +n x,y +dP x,y

[0170] Therefore, dP x,y It quantitatively represents the deviation characteristics of special dispersion compared with "normal glass".

[0171] dP g,F The calculation formula is as follows: dP g,F =P g,F -0.6457+0.001703*v d .

[0172] The aspheric cone coefficient can be defined by the following aspheric formula, but is not limited to the following representation method:

[0173]

[0174] Among them, z is the axial vector height of the aspheric surface in the Z direction; r is the height of the aspheric surface; c is the curvature of the fitted sphere, which is the inverse of the radius of curvature; k is the fitting cone coefficient; the 4th, 6th, 8th, 10th, 12th, and 14th order coefficients of the AF aspheric polynomial.

[0175] The even-order coefficients of each aspheric surface in the fourth embodiment are shown in Table 9:

[0176] Table 9 Aspheric surface parameters

[0177] Surface number A B C D E F S1 -6.89230E-04 1.58536E-05 -1.40427E-07 -1.22786E-09 4.44490E-11 -3.00005E-13 S2 3.13081E-03 -9.56553E-05 6.47745E-06 -5.30844E-07 3.19516E-08 -9.64763E-10 S3 2.41580E-03 -1.65897E-04 1.22842E-05 -8.02261E-07 3.51640E-08 -6.13512E-10 S4 1.69707E-03 -2.93422E-05 2.09677E-06 -1.77867E-08 4.23072E-10 5.95225E-11 S5 -1.15760E-03 6.37308E-06 -3.90718E-07 8.06881E-09 4.36761E-10 -1.13896E-11 S6 -1.64891E-03 3.89668E-05 -7.78849E-07 1.65552E-08 1.91876E-10 -4.87687E-12 S7 4.48400E-04 2.71329E-05 -1.67593E-06 2.36827E-08 5.69388E-10 -1.15370E-11 S8 7.71841E-04 7.75472E-06 -1.76145E-06 7.08882E-09 1.07234E-09 -1.67569E-11 S13 -9.00897E-04 -4.04147E-05 1.19149E-06 -6.13320E-08 2.03286E-09 -1.25786E-11 S14 1.09341E-03 -6.85149E-05 1.53248E-06 3.04951E-08 -2.24482E-09 3.45296E-11 S15 -1.63169E-03 -2.23100E-05 2.02301E-06 3.72650E-09 -3.90274E-09 7.64148E-11 S16 -2.71359E-03 4.93107E-05 1.15687E-07 -6.85632E-08 1.59820E-09 -9.93716E-12

[0178] Among them, -6.89230E-04 means that the coefficient A of the surface number S1 is -6.89230*10 -4 , and so on.

[0179] Figure 8 yes Figure 7 The spherical aberration curve of the fixed focus lens shown is Figure 8 The vertical axis is a dimensionless quantity, which represents the normalized entrance pupil radius. The vertical vertex represents the maximum pupil radius. The horizontal axis represents the distance from the image sensor surface to the focus on each wavelength axis. In other words, it can be understood as the offset from the ideal focus, in millimeters (mm). The different linear curves in the figure represent different wavelengths of system imaging. Figure 8 It can be seen that the axial aberrations of different wavelengths are all controlled within the range of (-0.05mm, +0.05mm), indicating that the spherical aberration of the fixed-focus lens at each wavelength is well controlled and can meet the needs of wide-spectrum applications, which also reflects that the fixed-focus lens has day and night confocal function.

[0180] Fig. 9 is a structural schematic diagram of a fixed-focus lens provided in Embodiment 5 of the present invention, with reference to Fig. 9 In the fifth embodiment of the present invention, the second lens 20, the fourth lens 40 and the eighth lens 80 are positive power lenses, and the ninth lens 90 is a negative power lens. In addition, the power, size ratio and angle parameters of each lens and the combined lens meet those shown in Table 1 above, which will not be described here.

[0181] In this fifth embodiment, by adopting a structure of mixing 3 glass spherical lenses and 6 plastic aspherical lenses, and by reasonably allocating the optical focal length, surface shape, Abbe number, etc. of each lens, the following design values ​​can be achieved: the focal length f is 4.162mm, the F# is 1.078, and the corresponding angle of φ9.2mm is 139.85°.

[0182] like Fig. 9 The parameter design values ​​of each lens in the fixed-focus lens of the fifth embodiment are shown in Table 10:

[0183] Table 10: Design values ​​of each lens in the fixed focus lens of Example 5

[0184]

[0185]

[0186] The surface numbers in Table 10 are numbered according to the order of the surfaces of each lens. "OBJ" represents the object surface of the fixed-focus lens; "STO" represents the aperture of the fixed-focus lens; "IMA" represents the image surface of the fixed-focus lens; the radius of curvature represents the curvature of the lens surface, a positive value represents that the surface is bent toward the image side, and a negative value represents that the surface is bent toward the object side, where "Infinity" represents that the surface is a plane, the radius of curvature is infinite, and the distance is infinite; the thickness represents the central axial distance from the current surface to the next surface, the refractive index represents the ability of the material between the current surface and the next surface to deflect light, and a blank represents that the current position is air, and the refractive index is 1; the Abbe number represents the dispersion characteristics of the material between the current surface and the next surface to light, and a blank represents that the current position is air; dP x,y It represents the deviation characteristics of special dispersion compared with "normal glass"; the semi-aperture represents the effective diameter of the light of the lens; the k value represents the numerical value of the cone coefficient of the aspheric surface.

[0187] Where, the relative partial dispersion P for wavelengths x and y is x,y It is expressed as follows:

[0188] P x,y =(n x -n y )-(n F -n C )

[0189] P′ x,y =(n x -n y )-(n F′ -n C′ )

[0190] The data sheet gives the P by grade. s,t , P C,s , P d,C , P e,d , P g,F , P′ s,t , P′ C,s , P′ d,C , P′ e,d , P′ g,F .

[0191] According to the Abbe formula, for most so-called "normal glass" (H-K6 and F4 of Chengdu Guangming are selected as "normal glass"), the following linear relationship is established:

[0192] P x,y =m x,y *v d +b x,y

[0193] This linear relationship is based on Px,y is the vertical axis, v d It is represented by the horizontal axis, where m x,y is the slope, b x,y is the intercept.

[0194] As is known to all, the correction of the secondary spectrum, i.e. the achromatization of more than two wavelengths, requires at least one glass that does not conform to the above formula (i.e. its P x,y The deviation value deviates from Abbe's empirical formula), and its deviation value is expressed as dP x,y If it is expressed, then each P x,y -v d The point is shifted by dP relative to the "normal line" that conforms to the above formula x,y In this way, the dP of each grade of glass x,y The value can be calculated using the following formula:

[0195] P x,y =m x,y *v d +b x,y +dP x,y

[0196] Therefore, dP x,y It quantitatively represents the deviation characteristics of special dispersion compared with "normal glass".

[0197] dP g,F The calculation formula is as follows: dP g,F =P g,F -0.6457+0.001703*v d .

[0198] The aspheric cone coefficient can be defined by the following aspheric formula, but is not limited to the following representation method:

[0199]

[0200] Among them, z is the axial vector height of the aspheric surface in the Z direction; r is the height of the aspheric surface; c is the curvature of the fitted sphere, which is the inverse of the radius of curvature; k is the fitting cone coefficient; the 4th, 6th, 8th, 10th, 12th, and 14th order coefficients of the AF aspheric polynomial.

[0201] The even-order coefficients of each aspheric surface in the fifth embodiment are shown in Table 11:

[0202] Table 11 Aspheric surface parameters

[0203]

[0204]

[0205] Among them, -4.37824E-04 means that the coefficient A of the surface number S1 is -4.37824*10 -4 , and so on.

[0206] Fig.10 yes Fig. 9 The spherical aberration curve of the fixed focus lens shown is Fig.10 The vertical axis is a dimensionless quantity, which represents the normalized entrance pupil radius. The vertical vertex represents the maximum pupil radius. The horizontal axis represents the distance from the image sensor surface to the focus on each wavelength axis. In other words, it can be understood as the offset from the ideal focus, in millimeters (mm). The different linear curves in the figure represent different wavelengths of system imaging. Fig.10 It can be seen that the axial aberrations of different wavelengths are all controlled within the range of (-0.05mm, +0.05mm), indicating that the spherical aberration of the fixed-focus lens at each wavelength is well controlled and can meet the needs of wide-spectrum applications, which also reflects that the fixed-focus lens has day and night confocal function.

[0207] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, combinations and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A fixed-focus lens, characterized in that: It consists of a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens and a ninth lens which are arranged in sequence from the object side to the image side along the optical axis; The first lens is a plastic aspheric lens with negative power, the second lens is a plastic aspheric lens, the third lens is a plastic aspheric lens with positive power, the fourth lens is a plastic aspheric lens, the fifth lens is a glass spherical lens with positive power, the sixth lens is a glass spherical lens with negative power, the seventh lens is a glass spherical lens with positive power, the eighth lens is a plastic aspheric lens, and the ninth lens is a plastic aspheric lens, and each lens is fixed in a lens barrel; The second lens and the fourth lens are concave-convex lenses, and the fifth lens and the seventh lens are biconvex lenses; The fifth lens and the seventh lens meet the following conditions: 1.4 <Nd5<1.71; 52.6 <Vd5<98; 1.4 <Nd7<1.71; 52.6 <Vd7<98; Wherein, Nd5 and Vd5 are the refractive index and Abbe number of the fifth lens respectively, and Nd7 and Vd7 are the refractive index and Abbe number of the seventh lens respectively; The second lens, the third lens and the fourth lens meet the following conditions: -0.45≤Φ2 / Φ≤0.1; 0.19≤Φ3 / Φ≤0.48; -0.07≤Φ4 / Φ≤0.2; Wherein, Φ is the overall focal length of the fixed-focus lens, Φ2, Φ3, and Φ4 are respectively the focal lengths of the second lens, the third lens, and the fourth lens; The fifth lens, the sixth lens and the seventh lens meet the following conditions: 0.19≤Φ5 / Φ≤0.65; -0.86≤Φ6 / Φ≤-0.18; 0.3≤Φ7 / Φ≤0.69; Among them, Φ is the overall optical power of the fixed-focus lens, and Φ5, Φ6, and Φ7 are the optical powers of the fifth lens, the sixth lens, and the seventh lens, respectively, so that the fixed-focus lens has both infrared confocal and wide angle.

2. The fixed-focus lens according to claim 1, characterized in that: The second lens, the third lens and the fourth lens meet the following conditions: 0.03≤Φ234 / Φ≤0.57; Wherein, Φ is the optical focal length of the fixed-focus lens as a whole, and Φ234 is the optical focal length of the combined lens group consisting of the second lens, the third lens and the fourth lens.

3. The fixed-focus lens according to claim 1, characterized in that: The fifth lens is cemented with the sixth lens to form a cemented lens group, or the sixth lens is cemented with the seventh lens to form a cemented lens group, or the fifth lens, the sixth lens and the seventh lens are cemented in sequence to form a cemented lens group.

4. The fixed-focus lens according to claim 1, characterized in that: The eighth lens and the ninth lens meet the following conditions: -0.81≤Φ8 / Φ≤0.44; -0.22≤Φ9 / Φ≤0.66; Wherein, Φ is the overall optical power of the fixed-focus lens, and Φ8 and Φ9 are the optical powers of the eighth lens and the ninth lens respectively.

5. The fixed-focus lens according to claim 1, wherein: The eighth lens and the ninth lens meet the following conditions: -0.1≤Φ89 / Φ≤0.3; Wherein, Φ is the optical focal length of the fixed-focus lens as a whole, and Φ89 is the optical focal length of the combined lens group consisting of the eighth lens and the ninth lens.

6. The fixed-focus lens according to claim 1, wherein: The fixed-focus lens satisfies the following condition: 0.005≤(C23+C34) / D1≤0.1; Wherein, C23 is the air gap between the second lens and the third lens; C34 is the air gap between the third lens and the fourth lens, and D1 is the effective diameter of the system light on the object side of the first lens.

7. The fixed-focus lens according to claim 1, wherein: The fixed focus lens meets the following conditions: 1°≤CRA max ≤16°; Among them, CRA max It is the maximum incident angle of the main light in the fixed-focus lens entering the electronic photosensitive element.

Images