Wide working distance wide-angle line-scan lens

Abstract

The application discloses a wide working distance wide-angle line scanning lens, which comprises a first lens, a second lens, a third lens, a fourth lens, a diaphragm, a fifth lens, a sixth lens, a seventh lens, an eighth lens and a ninth lens arranged in sequence along an optical axis from an object side to an image side, wherein the first lens has negative refractive power, the second lens has positive refractive power, the third lens has negative refractive power, the fourth lens has positive refractive power, the fifth lens has positive refractive power, the sixth lens has negative refractive power, the seventh lens has positive refractive power, the eighth lens has positive refractive power, and the ninth lens has negative refractive power. The line scanning lens reduces focal length, expands the field of view, and realizes large field of view, large target surface and low distortion. The line scanning lens realizes wide working distance and high resolution, and has wide working distance and high pixels. In addition, the line scanning lens is designed without thermalization, and can still clearly image in high and low temperature environments.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical lenses, in particular to a wide working distance wide-angle line scanning lens. BACKGROUND

[0002] Machine vision demand is increasing day by day, especially in many industries such as electronic manufacturing, appearance detection, bill detection and size measurement, as an important component in machine vision, the scanning machine vision lens has higher and higher requirements on its optical distortion, working distance, field of view size, etc.

[0003] The existing line scanning lens cannot simultaneously consider large target surface and low distortion, often in order to make the target surface larger, the distortion is also large, and the object cannot be clearly restored; and the working distance of the existing line scanning lens is narrow, which limits the use scene, and the imaging quality is different under different object distances; in addition, the existing line scanning lens is not designed without thermalization, and the use temperature range is limited, and it cannot be used in high and low temperature environments. At present, there is no line scanning lens on the market that can simultaneously consider large target surface, large field of view, low distortion and high quality.

[0004] In view of this, the present application inventors have invented a wide working distance wide-angle line scanning lens. SUMMARY

[0005] The purpose of the present application is to provide a wide working distance wide-angle line scanning lens that simultaneously considers large target surface, large field of view, low distortion and high quality.

[0006] In order to achieve the above-mentioned purpose, the present application adopts the following technical scheme: a wide working distance wide-angle line scanning lens, comprising a first lens, a second lens, a third lens, a fourth lens, a diaphragm, a fifth lens, a sixth lens, a seventh lens, an eighth lens and a ninth lens arranged in order from the object side to the image side along an optical axis, wherein the first lens to the ninth lens each comprises an object side surface facing the object side and allowing imaging light to pass through, and an image side surface facing the image side and allowing imaging light to pass through.

[0007] The first lens has a negative refractive power, and the object side surface of the first lens is a convex surface and the image side surface is a concave surface;

[0008] The second lens has a positive refractive power, and the object side surface of the second lens is a convex surface;

[0009] The third lens has a negative refractive power, and the image side surface of the third lens is a concave surface;

[0010] The fourth lens has a positive refractive power, and the image side surface of the fourth lens is a convex surface;

[0011] The fifth lens has a positive refractive power, and the object side surface of the fifth lens is a concave surface and the image side surface is a convex surface;

[0012] The sixth lens has negative refractive power, and the object side surface of the sixth lens is concave and the image side surface is convex.

[0013] The seventh lens has positive refractive power, and the image side surface of the seventh lens is convex.

[0014] The eighth lens has positive refractive power, and the image side surface of the eighth lens is convex.

[0015] The ninth lens has negative refractive power, and the object side surface of the ninth lens is concave and the image side surface is concave.

[0016] The lens satisfies BFL / TTL≥0.28, wherein BFL is the optical back focal length of the lens, and TTL is the total optical length of the lens.

[0017] Further, the lens satisfies 1<|FG1 / f|<1.5, 2.5<|FG2 / f|<4, wherein FG1 is the combined focal length of the first lens to the fourth lens, FG2 is the combined focal length of the fifth lens to the ninth lens, and f is the focal length of the lens.

[0018] Further, the lens satisfies 0.5<|BFL / f|<1.12, wherein f is the focal length of the lens.

[0019] Further, the lens satisfies 0.6<|y / f|<1.2, wherein y is the image height of the lens, and f is the focal length of the lens.

[0020] Further, the lens satisfies 0.44<|f2 / f|<1, 0.3<|f7 / f|<0.65, 0.45<|f9 / f|<0.86, wherein f2, f7, f9 are the focal lengths of the second lens, the seventh lens, and the ninth lens, respectively.

[0021] Further, the lens satisfies 0.8<nd2 / nd8<1.3, wherein nd2, nd8 are the refractive indices of the second lens and the eighth lens, respectively.

[0022] Further, the lens satisfies 1.85<nd2, 1.8<nd8<2.06, wherein nd2, nd8 are the refractive indices of the second lens and the eighth lens, respectively.

[0023] Further, the image side surface of the third lens and the object side surface of the fourth lens are mutually cemented, the image side surface of the fifth lens and the object side surface of the sixth lens are mutually cemented, and satisfy |vd4-vd3|>30, |vd5-vd6|>30, wherein vd3, vd4, vd5, vd6 are the dispersion coefficients of the third lens, the fourth lens, the fifth lens, and the sixth lens, respectively.

[0024] Further, the lens satisfies: dn4 / Dt<0, dn5 / Dt<0, wherein dn4 / Dt and dn5 / Dt are temperature coefficients of the refractive index of the fourth lens and the fifth lens, respectively.

[0025] Compared with the prior art, the present application has the following advantages:

[0026] The line scanning lens of the present application reduces the focal length, expands the field of view, realizes large field of view and large target surface, controls optical distortion, realizes large target surface and low distortion, and at the same time, realizes wide working distance and high resolution, wide working distance and high pixels, and wider field of view than similar line scanning lenses at the same object distance. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 Fig. 1 is a structural diagram of the line scanning lens of the present application;

[0028] Figure 2 Fig. 1 is a structural diagram of the line scanning lens of the present application;

[0029] Figure 3 Fig. 1 is a structural diagram of the line scanning lens of the present application;

[0030] Figure 4 Fig. 1 is a structural diagram of the line scanning lens of the present application;

[0031] Figure 5 Fig. 1 is a structural diagram of the line scanning lens of the present application;

[0032] Figure 6 Fig. 1 is a structural diagram of the line scanning lens of the present application;

[0033] Figure 7 Fig. 1 is a structural diagram of the line scanning lens of the present application.

[0034] BRIEF DESCRIPTION OF DRAWINGS

[0035] 1, first lens; 2, second lens; 3, third lens; 4, fourth lens; 5, fifth lens; 6, sixth lens; 7, seventh lens; 8, eighth lens; 9, ninth lens; 10, diaphragm; 11, protective sheet. DETAILED DESCRIPTION

[0036] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not intended to limit the present application.

[0037] The "lens has positive (or negative) refractive power" as used herein means that the paraxial refractive power of the lens calculated according to the Gaussian optical theory is positive (or negative). The "object side (or image side) of the lens" is defined as the specific range of the lens surface through which the imaging light passes. The concave-convex judgment of the lens surface shape can be made by the judgment method of those skilled in the art, i.e. by the sign of the radius of curvature (abbreviated as R value). The R value is commonly used in optical design software such as Zemax or CodeV. The R value is also commonly found in the lens data sheet of the optical design software. In terms of the object side, when the R value is positive, it is determined that the object side is convex; when the R value is negative, it is determined that the object side is concave. Conversely, in terms of the image side, when the R value is positive, it is determined that the image side is concave; when the R value is negative, it is determined that the image side is convex.

[0038] Referring to Figure 1 As shown in the drawings, the present application discloses a wide working distance wide-angle line scan lens, comprising a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, a diaphragm 10, a fifth lens 5, a sixth lens 6, a seventh lens 7, and an eighth lens 8, a ninth lens 9 arranged in sequence along an optical axis from the object side to the image side, wherein each of the first lens 1 to the ninth lens comprises an object side surface facing the object side and allowing imaging light to pass through, and an image side surface facing the image side and allowing imaging light to pass through.

[0039] The first lens 1 has a negative refractive power, and the object side surface of the first lens 1 is convex, and the image side surface is concave;

[0040] The second lens 2 has a positive refractive power, and the object side surface of the second lens 2 is convex;

[0041] The third lens 3 has a negative refractive power, and the image side surface of the third lens 3 is concave;

[0042] The fourth lens 4 has a positive refractive power, and the image side surface of the fourth lens 4 is convex;

[0043] The fifth lens 5 has a positive refractive power, and the object side surface of the fifth lens 5 is concave, and the image side surface is convex;

[0044] The sixth lens 6 has a negative refractive power, and the object side surface of the sixth lens 6 is concave, and the image side surface is convex;

[0045] The seventh lens 7 has a positive refractive power, and the image side surface of the seventh lens 7 is convex;

[0046] The eighth lens 8 has positive refractive power, and the image side surface of the eighth lens 8 is convex;

[0047] The ninth lens 9 has negative refractive power, and the object side surface of the ninth lens 9 is concave, and the image side surface is concave;

[0048] The lens satisfies BFL / TTL≥0.28, wherein BFL is the optical back focal length of the lens, and TTL is the total optical length of the lens. The above relationship is satisfied, the optical back focal length of the lens is controlled, the overall weight and cost of the lens are reduced, the CRA (chief ray angle) is reduced, the resolution is improved, and the relative illumination is improved.

[0049] The lens satisfies 1<|FG1 / f|<1.5, 2.5<|FG2 / f|<4, wherein FG1 is the combined focal length of the first lens 1 to the fourth lens 4, FG2 is the combined focal length of the fifth lens 5 to the ninth lens 9, and f is the focal length of the lens.

[0050] The lens satisfies 0.5<|BFL / f|<1.12, wherein f is the focal length of the lens.

[0051] The lens satisfies 0.6<|y / f|<1.2, wherein y is the image height of the lens, and f is the focal length of the lens.

[0052] The lens satisfies 0.44<|f2 / f|<1, 0.3<|f7 / f|<0.65, and 0.45<|f9 / f|<0.86, wherein f2, f7, and f9 are the focal lengths of the second lens 2, the seventh lens 7, and the ninth lens 9 respectively.

[0053] The lens satisfies 0.8<nd2 / nd8<1.3, wherein nd2 and nd8 are the refractive indices of the second lens 2 and the eighth lens 8 respectively. 1.85<nd2, 1.8<nd8<2.06. The above relationship is satisfied to achieve high resolution of the lens.

[0054] The image side surface of the third lens 3 and the object side surface of the fourth lens 4 are mutually cemented, and the image side surface of the fifth lens 5 and the object side surface of the sixth lens 6 are mutually cemented, and satisfy |vd4-vd3|>30,

[0055] |vd5-vd6|>30, wherein vd3, vd4, vd5, and vd6 are the dispersion coefficients of the third lens 3, the fourth lens 4, the fifth lens 5, and the sixth lens 6 respectively. The high and low dispersion coefficients of the cemented lenses are matched, which is beneficial to eliminate the system chromatic aberration, optimize the system aberration, and improve the image quality.

[0056] The lens satisfies: dn4 / Dt<0, dn5 / Dt<0, wherein dn4 / Dt and dn5 / Dt are the refractive index temperature coefficients of the fourth lens 4 and the fifth lens 5 respectively. By satisfying the above relationship, the lens can satisfy high resolution output in an environment of low temperature-40 degrees Celsius to high temperature 80 degrees Celsius, and realize athermalization design.

[0057] The working object distance range of the lens is 130mm-1200mm, and when the object distance changes, the first lens 1 to the ninth lens 9 are focused as a whole.

[0058] The maximum image surface of the lens can support a 64mm target surface, and the maximum field of view reaches more than 1700mm. At present, the same specification lens on the market can only reach a 60mm maximum target surface and less than 1600mm maximum field of view with large distortion. The lens of the present application can simultaneously consider large target surface, large field of view, low distortion and high image quality.

[0059] The wide working distance wide-angle line scanning lens of the present application will be described in detail below with specific embodiments.

[0060] Embodiment 1

[0061] The present application discloses a wide working distance wide-angle line scanning lens, comprising a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, a diaphragm 10, a fifth lens 5, a sixth lens 6, a seventh lens 7, an eighth lens 8 and a ninth lens 9 arranged in sequence along an optical axis from an object side to an image side, wherein the first lens 1 to the ninth lens each comprise an object side surface facing the object side and allowing imaging light to pass through, and an image side surface facing the image side and allowing imaging light to pass through.

[0062] The first lens 1 has a negative refractive power, and the object side surface of the first lens 1 is a convex surface and the image side surface is a concave surface;

[0063] The second lens 2 has a positive refractive power, and the object side surface of the second lens 2 is a convex surface;

[0064] The third lens 3 has a negative refractive power, and the image side surface of the third lens 3 is a concave surface;

[0065] The fourth lens 4 has a positive refractive power, and the image side surface of the fourth lens 4 is a convex surface;

[0066] The fifth lens 5 has a positive refractive power, and the object side surface of the fifth lens 5 is a concave surface and the image side surface is a convex surface;

[0067] The sixth lens 6 has a negative refractive power, and the object side surface of the sixth lens 6 is a concave surface and the image side surface is a convex surface;

[0068] The seventh lens 7 has a positive refractive power, and the image side surface of the seventh lens 7 is a convex surface;

[0069] The eighth lens 8 has positive refractive power, and the image-side surface of the eighth lens 8 is convex;

[0070] The ninth lens 9 has negative refractive power, and the object-side surface of the ninth lens 9 is concave, and the image-side surface is concave.

[0071] The detailed optical data of the embodiment are shown in Table 1-1.

[0072] Table 1-1 Detailed optical data of Example 1

[0073]

[0074] Part of the parameter data in the embodiment is shown in Table 1-2.

[0075] Table 1-2 Partial parameter data of Example 1

[0076]

[0077] The field curvature and distortion diagram of the lens under visible light are shown in Figure 2 As can be seen from the figure, the field curvature of each wavelength is basically coincided, the chromatic aberration is small, and the optical distortion of the system is less than 0.4%, the distortion is small, the wide-angle distortion is controlled, and the image quality is improved.

[0078] The resolution curve diagram of the lens under visible light is shown in Figure 3 The abscissa is the field angle, and the unit is degree. The ordinate is the MTF value, and the unit is dimensionless. As can be seen from the figure, when the 17 line pair is used, the overall MTF is about 0.85, when the 35 line pair is used, the overall MTF is about 0.7, and when the 71 line pair is used, the overall MTF is about 0.4.

[0079] In the embodiment, the maximum target surface of the lens is 64mm, and the maximum field of view is 1701mm, which takes into account the large target surface, large field of view, low distortion and high image quality.

[0080] Example 2

[0081] Compared with Example 1, the embodiment mainly differs in that the radius of curvature, lens thickness and other optical parameters of each lens surface are different.

[0082] The detailed optical data of the embodiment are shown in Table 2-1.

[0083] Table 2-1 Detailed optical data of Example 2

[0084]

[0085] Part of the parameter data in the embodiment is shown in Table 2-2.

[0086] Table 2-2 Partial parameter data of Example 2

[0087]

[0088] The field curvature and distortion of the lens under visible light are shown in Figure 4 As can be seen from the figure, the field curvature of each wavelength is basically coincided, the chromatic aberration is small, and the optical distortion of the system is <|-0.4%|, the distortion is small, the wide-angle distortion is controlled, and the image quality is improved.

[0089] The resolution curve of the lens under visible light is shown in Figure 5 The abscissa is the field angle, and the unit is degree. The ordinate is the MTF value, and the unit is dimensionless. As can be seen from the figure, when the 17 line pair is used, the overall MTF is about 0.85, when the 35 line pair is used, the overall MTF is about 0.7, and when the 71 line pair is used, the overall MTF is about 0.4.

[0090] In this embodiment, the maximum target surface of the lens is 64mm, and the maximum field of view is 1700mm, and the large target surface, large field of view, low distortion and high image quality are considered.

[0091] Example 3

[0092] Compared with Example 1, the main difference of this embodiment is that the radius of curvature, lens thickness and other optical parameters of each lens surface are different.

[0093] The detailed optical data of this embodiment is shown in Table 3-1.

[0094] Table 3-1 Detailed optical data of Example 3

[0095]

[0096] Part of the parameter data in this embodiment is shown in Table 3-2.

[0097] Table 3-2 Partial parameter data of Example 3

[0098]

[0099] The field curvature and distortion of the lens under visible light are shown in Figure 6 As can be seen from the figure, the field curvature of each wavelength is basically coincided, the chromatic aberration is small, and the optical distortion of the system is <|-0.4%|, the distortion is small, the wide-angle distortion is controlled, and the image quality is improved.

[0100] The resolution curve of the lens under visible light is shown in Figure 7The horizontal coordinate is the field angle in degree, and the vertical coordinate is the MTF value in non-dimensional. It can be seen from the figure that the overall MTF is about 0.85 when the line pair is 17, the overall MTF is about 0.7 when the line pair is 35, and the overall MTF is about 0.4 when the line pair is 71.

[0101] In the embodiment, the maximum target surface of the lens is 64 mm, and the maximum field of view is 1705 mm, and the large target surface, large field of view, low distortion and high image quality are considered.

[0102] The above merely describes the preferred embodiments of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A wide working distance, wide angle line-scan lens characterized by: The lens comprises a first lens, a second lens, a third lens, a fourth lens, a diaphragm, a fifth lens, a sixth lens, a seventh lens, an eighth lens, and a ninth lens arranged in sequence along an optical axis from an object side to an image side, wherein each of the first lens to the ninth lens comprises an object side surface facing the object side and allowing imaging light to pass through and an image side surface facing the image side and allowing imaging light to pass through; The first lens has a negative refractive power, and the object side surface of the first lens is a convex surface and the image side surface is a concave surface; The second lens has a positive refractive power, and the object side surface of the second lens is a convex surface; The third lens has a negative refractive power, and the image side surface of the third lens is a concave surface; The fourth lens has a positive refractive power, and the image side surface of the fourth lens is a convex surface; The fifth lens has a positive refractive power, and the object side surface of the fifth lens is a concave surface and the image side surface is a convex surface; The sixth lens has a negative refractive power, and the object side surface of the sixth lens is a concave surface and the image side surface is a convex surface; The seventh lens has a positive refractive power, and the image side surface of the seventh lens is a convex surface; The eighth lens has a positive refractive power, and the image side surface of the eighth lens is a convex surface; The ninth lens has a negative refractive power, and the object side surface of the ninth lens is a concave surface and the image side surface is a concave surface; The lens satisfies BFL / TTL≥0.28, wherein BFL is the optical back focal length of the lens, and TTL is the total optical length of the lens; the lens satisfies 1<|FG1 / f|<1.5 and 2.5<|FG2 / f|<4, wherein FG1 is the combined focal length of the first lens to the fourth lens, FG2 is the combined focal length of the fifth lens to the ninth lens, and f is the focal length of the lens.

2. A wide working distance, wide angle line scan lens as claimed in claim 1, characterized in that: The lens satisfies 0.5<|BFL / f|<1.12, wherein f is the focal length of the lens.

3. A wide working distance, wide angle line scan lens as claimed in claim 1, characterized in that: The lens satisfies 0.6<|y / f|<1.2, wherein y is the image height of the lens, and f is the focal length of the lens.

4. A wide working distance, wide angle line scan lens as in claim 1, wherein: The lens satisfies 0.44<|f2 / f|<1, 0.3<|f7 / f|<0.65, and 0.45<|f9 / f|<0.86, wherein f2, f7, and f9 are the focal lengths of the second lens, the seventh lens, and the ninth lens, respectively.

5. A wide working distance, wide angle line scan lens as claimed in claim 1, characterized in that: The lens satisfies 0.8<nd2 / nd8<1.3, wherein nd2 and nd8 are the refractive indices of the second lens and the eighth lens, respectively.

6. A wide-swath wide-angle line scan lens according to claim 1 or 5, wherein: The lens satisfies 1.85<nd2 and 1.8<nd8<2.06, wherein nd2 and nd8 are the refractive indices of the second lens and the eighth lens, respectively.

7. The wide working distance and wide angle line scan lens according to claim 1, characterized in that: The image side surface of the third lens and the object side surface of the fourth lens are mutually cemented, the image side surface of the fifth lens and the object side surface of the sixth lens are mutually cemented, and satisfy |vd4-vd3|>30 and |vd5-vd6|>30, wherein vd3, vd4, vd5, and vd6 are the dispersion coefficients of the third lens, the fourth lens, the fifth lens, and the sixth lens, respectively.

8. The wide-working-distance, wide-angle line-scan lens according to claim 1, wherein: The lens satisfies dn4 / Dt<0 and dn5 / Dt<0, wherein dn4 / Dt and dn5 / Dt are the refractive index temperature coefficients of the fourth lens and the fifth lens, respectively.

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