TW202136844A - Optical lens and manufacturing method thereof - Google Patents

Abstract

An optical lens including a first lens group, an aperture and a second lens group sequence arranged from a magnified side to a minified side along an optical axis is provided. The first lens group has a negative refractive power and includes three lenses having refractive power. The first lens group includes a lens having positive refractive power and an aspheric lens. The second lens group has a positive refractive power and includes three lenses having refractive power. The second lens group includes a lens having a negative refractive power, the lens closest to the minified side is a combination lens, and includes an aspheric lens. The total number of lenses having refractive power is between 6 and 8.

Description

Lens and its manufacturing method

The present invention relates to a lens and a manufacturing method thereof, and more particularly to an imaging lens and a manufacturing method thereof.

The traditional wide-angle lens is not easy to shrink the size of the lens due to the lens shape and lens material, and it is also difficult to have both the wide viewing angle and the imaging quality under a large aperture. Therefore, how to meet the requirements of wide viewing angle, high imaging quality, resistance to environmental variation, miniaturization and small thermal drift at the same time is something that needs to be studied in this field.

The invention provides a lens and a manufacturing method thereof, which can effectively reduce the number of lenses, improve aberrations, effectively reduce costs, and have good optical effects.

The present invention provides a lens comprising a first lens group, an aperture, and a second lens group arranged in sequence along the optical axis from the magnification side to the reduction side. The first lens group has negative refractive power and includes three lenses with refractive power. The first lens group includes one lens with positive refractive power and one aspheric lens. The second lens group has a positive refractive power and includes three lenses with refractive power. The second lens group includes a lens with a negative refractive power, and the lens closest to the reduction side is a combined lens, and includes an aspheric lens. The total number of lenses with diopter included in the lens ranges from 6 to 8. The lens satisfies 9>LT/EFL>15 and LT/D1>12, where LT is the distance along the optical axis from the lens surface of the first lens group closest to the magnification side to the lens surface of the second lens group farthest from the first lens group , EFL is the effective focal length of the lens, and D1 is the thickness along the optical axis of the lens closest to the magnification side in the first lens group.

The present invention also provides a lens including a first lens, a second lens, a third lens, an aperture, a fourth lens, a fifth lens, and a sixth lens that are sequentially arranged along the optical axis from the magnification side to the reduction side. Among them, the fifth lens and the sixth lens are cemented lenses. The lens satisfies 9>LT/EFL>15, 4>D6/D5>10, 180>FOV>230 and 80>A2>50, where LT is the lens surface closest to the magnification side of the first lens group to the second lens group. The distance along the optical axis away from the lens surface of the first lens group, EFL is the effective focal length of the lens, D5 is the thickness of the fifth lens along the optical axis, D6 is the thickness of the sixth lens along the optical axis, and FOV is the lens's thickness The field angle, and A2 is the angle between the extension line of the concave edge of the second lens and the optical axis.

The present invention also provides a lens manufacturing method, including providing a lens barrel, and placing and fixing a first lens group, a second lens group, and an aperture in the lens barrel. Wherein, the first lens group has a negative refractive power and includes three lenses with refractive power. The first lens group includes one lens with positive refractive power and one aspheric lens. The second lens group has a positive refractive power and includes three lenses with refractive power. The second lens group includes a lens with a negative refractive power, and the lens closest to the reduction side is a combined lens, and includes an aspheric lens. The total number of lenses with diopter included in the lens ranges from 6 to 8. The lens satisfies 9>LT/EFL>15 and LT/D1>12, where LT is the distance along the optical axis from the lens surface of the first lens group closest to the magnification side to the lens surface of the second lens group farthest from the first lens group , EFL is the effective focal length of the lens, and D1 is the thickness along the optical axis of the lens closest to the magnification side in the first lens group.

Based on the above, in the lens and manufacturing method of the present invention, multiple aspherical lenses are used to improve the resolution performance, and the negative diopter lens is used to achieve wide-angle light collection ability, which can effectively reduce the number of lenses, improve aberrations, and Effectively reduce costs and have good optical effects.

In order to make the above-mentioned features and advantages of the present invention more comprehensible, the following specific embodiments are described in detail in conjunction with the accompanying drawings.

FIG. 1 is a schematic diagram of a lens according to an embodiment of the invention. Please refer to Figure 1. This embodiment provides a lens 100, which is an imaging lens, and can be used in security surveillance, vehicle-mounted, or action photography, etc. The invention is not limited to this. Specifically, the lens 100 is, for example, a fisheye lens, which uses a plurality of aspherical lenses to improve resolution performance, and uses a negative diopter lens to achieve wide-angle light collection capability.

The lens 100 has an optical axis A, and includes a first lens group 130, an aperture 140, and a second lens group 150 arranged in sequence from a magnification side 110 to a reduction side 120, wherein the magnification side 110 is a light input lens 100 side, and the reduced side 120 is the side of the light output lens 100. In this embodiment, the lens 100 further includes an infrared filter 160 and a light-transmitting protective cover 170, and the light entering the lens 100 can be transmitted from the magnification side 110 to the reduction side 120 and be imaged to the imaging surface 180.

The first lens group 130 has a negative refractive power and includes at least one aspheric lens. The first lens group 130 includes a first lens L1, a second lens L2, and a third lens L3 arranged in sequence from the magnification side 110 to the reduction side 120.

The second lens group 150 has a positive refractive power and includes at least one aspheric lens. In this embodiment, the second lens group 150 includes a fourth lens L4, a fifth lens L5, and a sixth lens L6 that are sequentially arranged from the magnification side 110 to the reduction side 120. The refractive power of one of the fifth lens L5 and the sixth lens L6 is positive, and the other of them is negative. In this embodiment, the refractive power of the fifth lens element L5 is negative, and the refractive power of the sixth lens element L6 is positive. However, in an embodiment, the refractive power of the fifth lens element L5 may be positive, and the refractive power of the sixth lens element L6 may be negative, and the present invention is not limited thereto. In this embodiment, at least two lenses (that is, the fifth lens L5 and the sixth lens L6) closest to the reduction side 120 in the second lens group 150 are cemented lenses.

Specifically, in this embodiment, the total number of lenses of the lens 100 is 6, the number of aspheric lenses is 4, and the number of cemented lenses is 1, so the number of lenses can be effectively reduced and aberrations can be improved. In addition, in this embodiment, the refractive powers of the 6 lenses in the lens 100 are negative, negative, positive, positive, negative, and positive from the magnification side 110 to the reduction side 120, and the materials are glass, plastic, plastic, and glass, respectively. , Plastic, plastic. In other words, the material of the second lens L2, the third lens L3, the fifth lens L5, and the sixth lens L6 is plastic. Therefore, the cost can be effectively reduced, but the present invention is not limited to this.

The number of diopter lenses in the lens 100 of this embodiment is between 6 and 8, which has the best and better cost-effectiveness. In addition, the lens 100 of this embodiment meets 9>LT/EFL>15, where LT is the lens surface of the lens 100 closest to the magnification side 110 (that is, the surface S1 of the first lens L1) to the lens 100 closest to the reduction side 120 The distance along the optical axis A of the lens surface of the lens surface (that is, the surface S13 of the sixth lens L6), and EFL is the effective focal length of the lens 100. In this embodiment, the lens 100 conforms to LT/D1>12, where D1 is the thickness along the optical axis A of the lens closest to the magnification side 110 in the lens 100 (ie, the first lens L1). It is worth mentioning that the diopter of the image side surface (that is, the surface S6) of the third lens L3 is positive.

On the other hand, in this embodiment, the lens 100 conforms to 4>Z1/Z2>10, where Z1 is the greater thickness of the fifth lens L5 or the sixth lens L6 along the optical axis A, and Z2 is the fifth lens L5 Or the sixth lens L6 has a smaller thickness along the optical axis A.

In addition, the lens 100 of this embodiment conforms to 180 degrees>FOV>230 degrees, where FOV is the maximum angle of view of the lens 100. In a preferred embodiment, the lens 100 conforms to FOV>210 degrees. In this embodiment, the thickness of the lens closest to the magnification side 110 (ie, the first lens L1) along the optical axis A is greater than 1 millimeter. The lens 100 of this embodiment conforms to 0.7>R1/LT>2, where R1 is the effective radius r1 of the lens closest to the magnification side 110 (ie, the first lens L1) in the lens 100. The lens 100 of this embodiment satisfies 0.2>RL/LT>0.38, where RL is the effective radius r6 of the lens closest to the reduction side 120 (that is, the sixth lens L6) in the lens 100. The lens 100 of this embodiment conforms to D6/D5>2, where T6 is the thickness of the sixth lens L6 along the optical axis A, and D5 is the thickness of the fifth lens L5 along the optical axis A. The lens 100 of this embodiment satisfies 50>A2>80, where A2 is the angle B (or aperture angle) between the concave edge tangent of the second lens L2 and the direction perpendicular to the optical axis A, as shown in FIG. 1.

Therefore, in this embodiment, the lens 100 is a fixed-focus imaging lens, and the aperture of the lens 100 can reach F/2.0, the total length can be within 12.5 mm, and the half angle of view can reach 105 degrees or more. More specifically, the lens 100 of this embodiment is a fisheye lens, which can effectively reduce the number of lenses, improve aberrations, effectively reduce costs, and have good optical effects.

In this embodiment, the actual design of the aforementioned components can be seen in Table 1 below.

Table I EFL (mm) =0.9011; F/#=2; FOV (˚)=218; TTL (mm)=12.33; IMH (mm)=4.01; RL (mm)=3.283; LT (mm)=10.736; RL/ LT= 0.306; EFL/LT= 0.0839; element surface Radius of curvature (mm) Spacing (mm) Refractive index (Nd) Abbe number (Vd) The first lens L1 S1 10.465 1.000 1.804 46.5 S2 2.931 1.778 Second lens L2 S3* 6.101 0.666 1.536 56.0 S4* 0.844 1.268 The third lens L3 S5* 2.478 1.309 1.640 23.5 S6* 12.703 0.200 Aperture 140 S7 Unlimited 0.100 Fourth lens L4 S8 -113.600 1.151 1.804 46.5 S9 -2.332 0.183 Fifth lens L5 S10* 4.881 0.528 1.640 23.5 S11* 0.802 0.008 Sixth lens L6 S12* 0.802 2.540 1.536 56.0 S13* -1.913 0.100 Infrared filter 160 S14 Unlimited 0.300 1.517 64.2 S15 Unlimited 0.749 Protective cover 170 S16 Unlimited 0.400 1.517 64.2 S17 Unlimited 0.045 Imaging surface 180 S18 Unlimited 0.000

Please refer to Figure 1 and Table 1 at the same time. Specifically, in the lens 100 of this embodiment, the first lens L1 has a surface S1 and a surface S2 sequentially from the magnification side 110 to the reduction side 120, and the first lens L2 has a surface S1 and a surface S2 from the magnification side 110 to the reduction side 120 in sequence. The surface S3 and the surface S4, and the surface S3 and the surface S4 are aspherical surfaces, which are represented by the symbol * as aspherical surfaces, and so on, and the surface corresponding to each element will not be repeated. In addition, TTL is the total length of the lens, that is, the distance from the lens surface closest to the magnification side 110 in the lens 100 (that is, the surface S1 of the first lens L1) to the imaging surface 180 in the lens 100 along the optical axis A, and IMH is the image plane diameter.

In addition, the interval in Table 1 is the distance between the next surface of the surface from the enlarged side 110 to the reduced side 120. In other words, the thickness of the first lens L1 is 10.465 mm, the thickness of the second lens L2 is 6.101 mm, and the distance between the adjacent surfaces of the first lens L1 and the second lens L2 is 2.931 mm, and so on, Therefore, I will not repeat them again.

In addition, the radius of curvature in Table 1 is the radius of curvature of the surface, and its positive and negative values represent the direction of curvature. For example, the radius of curvature of the surface S1 of the first lens L1 is positive, and the radius of curvature of the surface S2 of the first lens L1 Is positive. Therefore, the first lens L1 is a convex-concave lens. For another example, the radius of curvature of the surface S12 of the sixth lens L6 is positive, and the radius of curvature of the surface S13 of the sixth lens L6 is negative. Therefore, the first lens L1 is a biconvex lens, and so on, so it will not be repeated.

(1)Table 2 below lists the quadric coefficient value K and the aspheric coefficient AH of each aspheric surface. The aspheric polynomial can be expressed by the following formula (1):

(1)

Where x is the offset in the direction of the optical axis A (sag), c'is the reciprocal of the radius of the Osculating Sphere, that is, the reciprocal of the radius of curvature close to the optical axis, K is the quadric coefficient, y It is the height of the aspheric surface, that is, the height from the center of the lens to the edge of the lens. A-H respectively represent the aspheric coefficients of the aspheric polynomials.

Table II S3 S4 S5 S6 K -1.924 -0.988 -4.477 -6.852 A 0 0 0 0 B 9.14E-04 4.92E-02 6.20E-02 7.08E-02 C -7.76E-03 4.06E-02 4.89E-03 -6.29E-03 D 2.47E-03 -4.61E-02 -4.27E-03 -1.63E-01 E -3.72E-04 2.00E-02 5.05E-03 5.67E-01 F 2.84E-05 1.77E-03 -1.72E-03 -1.01E-02 G -8.25E-07 1.71E-03 5.58E-04 -1.26E+00 H -1.14E-08 -1.43E-03 -3.01E-04 8.52E-01 S10 S11 S12 S13 K 1.14 -1.693 -1.693 -6.985 A 0 0 0 0 B -3.74E-02 2.48E-02 2.48E-02 -4.59E-02 C 2.49E-02 3.62E-02 3.62E-02 3.02E-02 D -8.76E-03 -1.23E-02 -1.23E-02 -1.16E-02 E -7.24E-06 -3.13E-05 -3.13E-05 2.08E-03 F 8.48E-06 1.17E-05 1.17E-05 3.62E-05 G 1.35E-04 5.21E-05 5.21E-05 -5.48E-05 H 1.50E-04 1.06E-04 1.06E-04 4.16E-06

FIG. 3 is a schematic diagram of a lens according to another embodiment of the invention. Please refer to Figure 3. The lens 100A depicted in this embodiment is similar to the lens 100 shown in FIG. 1. The main difference between the two is that in this embodiment, the surface S11 of the fifth lens L5 is a spherical surface.

In this embodiment, the actual design of the aforementioned components can be seen in Table 3 below. The interpretation of Table 3 is the same as that of Table 1, so I won’t repeat it.

Table Three EFL (mm) =0.896; F/#=2; FOV (˚)=218; TTL (mm)=12.34; IMH (mm)=4.01; RL (mm)=3.3; LT (mm)=10.762; RL/ LT= 0.307; EFL/LT= 0.0833; element surface Radius of curvature (mm) Spacing (mm) Refractive index (Nd) Abbe number (Vd) The first lens L1 S1 10.481 1 1.804 46.5 S2 3.013 1.792 Second lens L2 S3* 5.007 0.761 1.536 56.0 S4* 0.76 1.356 The third lens L3 S5* 2.35 1.145 1.640 23.5 S6* 18.131 0.2 Aperture 140 S7 Unlimited 0.1 Fourth lens L4 S8 20.332 1.216 1.804 46.5 S9 -3 0.202 Fifth lens L5 S10* 4.349 0.481 1.640 23.5 S11 0.854 0.008 Sixth lens L6 S12* 0.854 2.511 1.536 56.0 S13* -1.903 0.1 Infrared filter 160 S14 Unlimited 0.3 1.517 64.2 S15 Unlimited 0.733 Protective cover 170 S16 Unlimited 0.4 1.517 64.2 S17 Unlimited 0.045 Imaging surface 180 S18 Unlimited 0

Table 4 below lists the quadric coefficient value K of each aspheric surface and the coefficients A-H of each order aspheric surface.

Table Four S3 S4 S5 S6 K -3.09E+00 -9.40E-01 -3.40E+00 -4.98E+02 A 0 0 0 0 B 4.38E-04 5.81E-02 6.41E-02 5.39E-02 C -7.81E-03 3.95E-02 5.90E-03 3.56E-02 D 2.47E-03 -4.25E-02 3.00E-03 -1.57E-01 E -3.71E-04 2.11E-02 6.12E-03 4.58E-01 F 2.86E-05 1.57E-03 -2.15E-03 -1.20E-01 G -7.69E-07 2.96E-03 2.27E-03 -9.99E-01 H -1.99E-08 1.41E-03 -1.02E-03 9.58E-01 S10 S12 S13 K 1.52E+00 -1.53E+00 -6.88E+00 A 0 0 0 B -3.65E-02 3.34E-02 -4.64E-02 C 2.14E-02 3.49E-02 2.98E-02 D -1.23E-02 -1.63E-02 -1.18E-02 E -4.96E-04 -3.63E-03 2.00E-03 F 4.97E-04 -1.53E-03 2.71E-05 G 2.50E-04 1.78E-05 -4.75E-05 H 2.64E-04 6.50E-04 1.13E-05

FIG. 5 is a schematic diagram of a lens according to another embodiment of the invention. Please refer to Figure 5. The lens 100B depicted in this embodiment is similar to the lens 100 shown in FIG. 1. The main difference between the two is that in this embodiment, the surface S11 of the fifth lens L5 is a spherical surface.

In this embodiment, the actual design of the aforementioned components can be seen in Table 5 below. The interpretation of Table 5 is the same as that of Table 1, so I won’t repeat it.

Table 5 EFL (mm) =0.9; F/#=2; FOV (˚)=218; TTL (mm)=12.3; IMH (mm)=4.01; RL (mm)=3.435; LT (mm)=11.007; RL/ LT= 0.312; EFL/LT= 0.0818; element surface Radius of curvature (mm) Spacing (mm) Refractive index (Nd) Abbe number (Vd) The first lens L1 S1 12.319 1 1.804 46.5 S2 3.105 1.543 Second lens L2 S3* 4.378 0.484 1.536 56.0 S4* 0.872 1.651 The third lens L3 S5* 3.171 1.301 1.640 23.5 S6* -41 0.358 Aperture 140 S7 Unlimited 0.09 Fourth lens L4 S8 26.147 1.278 1.804 39.6 S9 -2.96 0.181 Fifth lens L5 S10* 3.357 0.364 1.640 23.5 S11 0.678 0 Sixth lens L6 S12* 0.678 2.757 1.536 56.0 S13* -2.164 0.11 Infrared filter 160 S14 Unlimited 0.33 1.517 64.2 S15 Unlimited 0.364 Protective cover 170 S16 Unlimited 0.44 1.517 64.2 S17 Unlimited 0.05 Imaging surface 180 S18 Unlimited 0

Table 6 below lists the quadric coefficient value K of each aspheric surface and the aspheric coefficients A-H of each order.

Table 6 S3 S4 S5 S6 K -1.07E+01 -8.96E-01 -4.39E+00 0 A 0 0 0 0 B 8.85E-03 2.26E-02 3.78E-02 3.55E-02 C -5.05E-03 2.51E-02 4.87E-03 2.06E-02 D 1.28E-03 -1.10E-02 1.92E-03 -5.22E-02 E -1.60E-04 3.66E-03 4.79E-04 1.54E-01 F 9.84E-06 4.51E-04 -6.80E-04 -2.24E-01 G -2.69E-07 1.29E-03 5.21E-04 1.26E-01 H 0 0 0 0 S10 S12 S13 K 4.30E-02 -1.25E+00 -6.38E+00 A 0 0 0 B -3.40E-02 2.50E-02 1.75E-03 C 9.06E-03 5.51E-02 1.13E-03 D 1.52E-03 -5.04E-05 -2.17E-03 E 3.43E-03 2.86E-03 3.70E-04 F -1.16E-03 2.04E-04 -3.77E-06 G -4.71E-03 -5.22E-03 -3.92E-05 H 0 0 0

2A and FIG. 2B, FIG. 4A and FIG. 4B, and FIG. 6A and FIG. 6B are respectively astigmatic field curve diagrams and distortion diagrams of the embodiment lenses 100, 100A, and 100B. Figures 2A, 4A, and 6A are the astigmatic field curvature diagrams of the lenses 100, 100A, and 100B. The horizontal axis is the focus displacement (mm), the vertical axis is the image height, and T is the curve in the meridian direction. , S represents the curve in the sagittal direction, and different line styles represent the measurement conditions at different wavelengths. 2B, 4B, and 6B are distortion diagrams of the lenses 100, 100A, and 100B. The horizontal axis is the distortion percentage (%), the vertical axis is the image height, and different line styles represent the measurement conditions at different wavelengths. It can be verified that the astigmatic field curvature and distortion displayed by the lenses 100, 100A, and 100B of this embodiment are within the standard range between wavelengths of 450 nm and 650 nm, so they have good optical imaging quality, such as Figures 2A and 2B, Figure 4A and Figure 4B, Figure 6A and Figure 6B are shown.

In summary, in the lens and its manufacturing method of the present invention, multiple aspherical lenses are used to improve resolution performance, and a negative diopter lens is used to achieve wide-angle light collection capability, which can effectively reduce the number of lenses and improve the image. Poor, effectively reduce costs, and have good optical effects.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention. Anyone with ordinary knowledge in the relevant technical field can make some changes and modifications without departing from the spirit and scope of the present invention. The protection scope of the present invention shall be subject to those defined by the attached patent application scope.

100, 100A, 100B: lens 110: Magnified side 120: Reduced side 130: The first lens group 140: Aperture 150: second lens group 160: Infrared filter 170: Translucent protective cover 180: imaging surface A: Optical axis B: included angle L1~L6: lens r1, r6: effective radius S1~S18: surface

FIG. 1 is a schematic diagram of a lens according to an embodiment of the invention. 2A and 2B are respectively an astigmatic field curve diagram and a distortion diagram of the lens of the embodiment in FIG. 1. FIG. 3 is a schematic diagram of a lens according to another embodiment of the invention. 4A and 4B are respectively an astigmatic field curve diagram and a distortion diagram of the lens of the embodiment in FIG. 3. FIG. 5 is a schematic diagram of a lens according to another embodiment of the invention. 6A and 6B are respectively an astigmatic field curve diagram and a distortion diagram of the lens of the embodiment in FIG. 5.

100: lens

110: Magnified side

120: Reduced side

130: The first lens group

140: Aperture

150: second lens group

160: Infrared filter

170: Translucent protective cover

180: imaging surface

A: Optical axis

B: included angle

L1~L6: lens

r1, r6: effective radius

S1~S18: surface

Claims (10)

A lens that contains: A first lens group, an aperture, and a second lens group arranged in sequence along an optical axis from one magnification side to a reduction side; in, The first lens group has a negative refractive power, the first lens group includes three lenses with refractive power, the first lens group includes a lens with a positive refractive power, and the first lens group includes an aspheric lens; The second lens group has positive refractive power, the second lens group includes three lenses with refractive power, the second lens group includes a lens with negative refractive power, and the lens of the second lens group closest to the reduction side is a combination Lens, the second lens group includes an aspheric lens; The total number of lenses with diopter included in the lens is between 6 and 8; and The lens meets the following conditions: (1) 9>LT/EFL>15, where LT is the distance along the optical axis from the lens surface of the first lens group closest to the magnification side to the lens surface of the second lens group farthest from the first lens group , And EFL is the effective focal length of the lens; and (2) LT/D1>12, where D1 is the thickness along the optical axis of the lens closest to the magnification side in the first lens group. The lens of claim 1, wherein the first lens group includes a first lens, a second lens, and a third lens that are sequentially arranged along the optical axis from the magnification side to the reduction side, the second lens The lens group includes a fourth lens, a fifth lens, and a sixth lens that are sequentially arranged along the optical axis from the magnification side to the reduction side. A lens that contains: A first lens, a second lens, a third lens, an aperture, a fourth lens, a fifth lens, and a sixth lens arranged in order along an optical axis from one magnification side to a reduction side; in, The fifth lens and the sixth lens are a cemented lens; and The lens meets the following conditions: (1) 9>LT/EFL>15, where LT is the distance along the optical axis from the lens surface of the first lens group closest to the magnification side to the lens surface of the second lens group farthest from the first lens group , And EFL is the effective focal length of the lens; (2) 4>D6/D5>10, where D5 is the thickness of the fifth lens along the optical axis, and D6 is the thickness of the sixth lens along the optical axis; (3) 180>FOV>230, where FOV is the angle of view of the lens; and (4) 80>A2>50, where A2 is the angle between the extension line of the concave edge of the second lens and the optical axis. The lens according to claim 1 or 3, wherein the lens meets FOV>210, where FOV is the angle of view of the lens. The lens according to claim 1 or 3, wherein the thickness of the lens closest to the magnification side along the optical axis is greater than 1 mm. The lens according to claim 2 or 3, wherein the refractive power of the first lens to the fourth lens is negative, negative, positive, and positive in order. The lens according to claim 2 or 3, wherein the refractive power of one of the fifth lens and the sixth lens is positive, and the other is negative. The lens according to claim 2 or 3, wherein the material of the first lens and the fourth lens is glass, and the material of the second lens, the third lens, the fifth lens, and the sixth lens is plastic. The lens according to claim 2 or 3, wherein the lens conforms to 4>Z1/Z2>10, where Z1 is the greater thickness of the fifth lens or the sixth lens along the optical axis, and Z2 is the first lens. The fifth lens or the sixth lens has a smaller thickness along the optical axis. A lens manufacturing method, including: Provide a lens barrel; and Put a first lens group, a second lens group and an aperture into and fixed in the lens barrel, Wherein, the first lens group has a negative refractive power, the first lens group includes three lenses with refractive power, the first lens group includes a lens with a positive refractive power, the first lens group includes an aspheric lens, and the first lens group includes a lens with a positive refractive power. The two lens groups have positive refractive power, the second lens group includes three lenses with refractive power, the second lens group includes a lens with negative refractive power, and the lens of the second lens group closest to the reduction side is a combined lens, The second lens group includes an aspheric lens, and the total number of lenses with refractive power in the lens is between 6 and 8, The lens meets the following conditions: (1) 9>LT/EFL>15, where LT is the distance along the optical axis from the lens surface of the first lens group closest to the magnification side to the lens surface of the second lens group farthest from the first lens group , And EFL is the effective focal length of the lens; and (2) LT/D1>12, where D1 is the thickness along the optical axis of the lens closest to the magnification side in the first lens group.

Images