A large target surface, wide spectrum ultraviolet imaging lens for machine vision

Abstract

The present application relates to a kind of large target surface, wide spectrum ultraviolet imaging lens for machine vision, especially optical instrument technical field is related to.The present application includes nine pieces of spherical lens, nine pieces of lens are sequentially arranged as first lens, second lens, third lens, fourth lens, fifth lens, sixth lens, seventh lens, eighth lens and ninth lens from object side to image side, the target surface of this lens is 45mm, wide spectrum ultraviolet imaging has high resolution, low distortion, long focal length, high contrast and the like advantages, suitable for the fingerprint display of the surface of glass, plastic, photo and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical instruments, in particular to a large-target wide-spectrum ultraviolet imaging lens for machine vision. BACKGROUND

[0002] In the field of machine vision, ultraviolet imaging technology can expand the wavelength range that visible light cameras cannot cover, providing more information and features, thereby providing more comprehensive and accurate visual support for image processing, target recognition and scene understanding tasks.

[0003] Ultraviolet imaging technology has important applications in plastic sorting, battery product detection, fingerprint detection and other fields. Ultraviolet lenses are an important part of ultraviolet imaging technology. The existing ultraviolet lenses have a spectrum of 200nm to 400nm and can only be used for skin surface fingerprint detection. For fingerprint display on different materials, the imaging contrast will be severely reduced. Existing wide-spectrum ultraviolet lenses are mostly suitable for 2 / 3 inch COMS and cannot be applied to situations that require observation of a larger range and simultaneous capture of multiple targets. SUMMARY

[0004] (1) Technical solution

[0005] To solve the above technical problems, the present application provides a large-target wide-spectrum ultraviolet imaging lens for machine vision, comprising a first lens, a second lens, a third lens, an aperture stop, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens and a ninth lens along the optical axis direction.

[0006] The first lens is a positive focal power meniscus lens, the second lens is a negative focal power double concave lens, the third lens is a negative focal power meniscus lens, the fourth lens is a positive focal power double convex lens, the fifth lens is a negative focal power double concave lens, the sixth lens is a positive focal power double convex lens, the seventh lens is a positive focal power meniscus lens, the eighth lens is a positive focal power meniscus lens, and the ninth lens is a negative focal power plano-concave lens.

[0007] Preferably, the object side of the first lens is convex, and the image side is concave; the object side of the eighth lens is concave, and the image side is convex; the object side of the ninth lens is convex, and the image side is flat.

[0008] Preferably, the air gap between the first lens and the second lens is 4.7mm, the air gap between the second lens and the third lens is 7.5mm, the air gap between the third lens and the aperture stop is 3.0mm, the air gap between the aperture stop and the fourth lens is 1.6mm, the air gap between the fourth lens and the fifth lens is 6.6mm, the air gap between the fifth lens and the sixth lens is 5.6mm, the air gap between the sixth lens and the seventh lens is 0.3mm, the air gap between the seventh lens and the eighth lens is 4.0mm, the air gap between the eighth lens and the ninth lens is 11.0mm, and the air gap between the ninth lens and the imaging surface is 52.5mm.

[0009] Preferably, the first lens, the third lens, the fourth lens, the sixth lens, the eighth lens and the ninth lens are all made of calcium fluoride material, and the second lens, the fifth lens and the seventh lens are all made of fused quartz material.

[0010] Preferably, the system focal lengths of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens and the ninth lens are F1, F2, F3, F4, F5, F6, F7, F8 and F9 respectively, and the focal length F of the optical system composed of them satisfies the following focal length relationship: 0.5<F1 / F<0.7; -0.4<F2 / F<-0.2; 1.4<F3 / F<1.6; 0.2<F4 / F<0.4; -0.4<F5 / F<-0.2; 0.5<F6 / F<0.7; 2<F7 / F<4; 1.6<F8 / F<1.8; -1.3<F9 / F<1.1.

[0011] Preferably, the total length TTL of the ultraviolet imaging lens and the maximum image height IH corresponding to the maximum field of view angle of the ultraviolet imaging lens satisfy: 3.5≤TTL / IH≤4.2.

[0012] Preferably, the back focal length BFL of the ultraviolet imaging lens and the total focal length F of the ultraviolet imaging lens satisfy: 0.3≤BFL / F≤0.5.

[0013] (2) Beneficial effects

[0014] The application provides a large-target wide-spectrum ultraviolet imaging lens for machine vision, which has a target surface of 45mm and wide-spectrum ultraviolet imaging with high resolution, low distortion, long focal length, high contrast and the like, and is suitable for fingerprint display on surfaces of glass, plastic, photos and the like. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1is the optical structure schematic diagram of a large target surface, wide spectrum ultraviolet imaging lens for machine vision provided by the embodiment of the application;

[0016] Figure 2 is Figure 1 the modulation transfer function curve diagram of the large target surface, wide spectrum ultraviolet imaging lens for machine vision;

[0017] Figure 3 is Figure 1 the distortion curve diagram of the large target surface, wide spectrum ultraviolet imaging lens for machine vision;

[0018] Figure 4 is Figure 1 the relative luminance curve diagram of the large target surface, wide spectrum ultraviolet imaging lens for machine vision;

[0019] The figure mark is: 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-aperture diaphragm, 11-imaging surface. DETAILED DESCRIPTION

[0020] The application is further illustrated in combination with the drawings and embodiments.

[0021] As Figures 1 to 4 shown, the large target surface, wide spectrum ultraviolet imaging lens for machine vision comprises nine spherical lenses, and the nine lenses are arranged in order from the object side to the image side as the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5, the sixth lens 6, the seventh lens 7, the eighth lens 8 and the ninth lens 9, the first lens 1 is a positive focal length meniscus lens, the second lens 2 is a negative focal length double concave lens, the third lens 3 is a negative focal length meniscus lens, the fourth lens 4 is a positive focal length double convex lens, the fifth lens 5 is a negative focal length double concave lens, the sixth lens 6 is a positive focal length double convex lens, the seventh lens 7 is a positive focal length meniscus lens, the eighth lens 8 is a positive focal length meniscus lens, and the ninth lens is a negative focal length plano-concave lens, wherein the first lens 1, the third lens 3, the fourth lens 4, the sixth lens 6, the eighth lens 8 and the ninth lens 9 all adopt calcium fluoride material, the second lens 2, the fifth lens 5 and the seventh lens 7 all adopt fused quartz material, and all the above lenses adopt spherical lenses, which is convenient for processing and detection.

[0022] As Figure 1As shown, a large-target-surface, wide-spectrum ultraviolet imaging lens for machine vision of the present invention comprises a large-target-surface, wide-spectrum ultraviolet imaging lens, an aperture stop 10, and an imaging surface 11. Arranged from the object side to the image side are a first lens 1, a second lens 2, a third lens 3, an aperture stop 10, a fourth lens 4, a fifth lens 5, a sixth lens 6, a seventh lens 7, an eighth lens 8, a ninth lens 9, and the imaging surface 11. The surfaces of the first lens 1, the second lens 2, the third lens 3, the aperture stop 10, the fourth lens 4, the fifth lens 5, the sixth lens 6, the seventh lens 7, the eighth lens 8, and the ninth lens 9 are all spherical. In this embodiment, the spacing between the lenses is air. The first lens 1 and the second lens 2 are arranged in sequence. The air spacing between the second lens 2 and the third lens 3 is 4.7mm, the air spacing between the second lens 2 and the third lens 3 is 7.5mm, the air spacing between the third lens 3 and the aperture stop 10 is 3.0mm, the air spacing between the aperture stop 10 and the fourth lens 4 is 1.6mm, the air spacing between the fourth lens 4 and the fifth lens 5 is 6.6mm, the air spacing between the fifth lens 5 and the sixth lens 6 is 5.6mm, the air spacing between the sixth lens 6 and the seventh lens 7 is 0.3mm, the air spacing between the seventh lens 7 and the eighth lens 8 is 4.0mm, the air spacing between the eighth lens 8 and the ninth lens 9 is 11.0mm, and the air spacing between the ninth lens 9 and the imaging plane 11 is 52.5mm.

[0023] The large-area, wide-spectrum UV imaging lens in this embodiment has an effective focal length of 113 mm, a relative numerical aperture of F / 4.5, a full field of view of 22°, a diagonal dimension of the imaging surface 11 of 45 mm, and a total optical length of 83.3 mm, the distance from the first lens element 1 to the ninth lens element 9. The operating wavelength range is 250 nm to 850 nm. The optical parameters of each lens are shown in the table below.

[0024]

[0025]

[0026] like Figure 2 As shown, Figure 1 The large-target, wide-spectrum UV imaging lens shown has a cutoff frequency of 50 line pairs / mm across the entire field of view, and the corresponding modulation transfer function value is better than 0.6. The modulation transfer function curves for each field of view are relatively concentrated, indicating that this large-target, wide-spectrum UV imaging lens can achieve high-precision target detection.

[0027] like Figure 3 As shown, Figure 1 The large-target, wide-spectrum ultraviolet imaging lens shown has a distortion value of less than 0.19% over the entire field of view, achieving high fidelity of ultraviolet imaging.

[0028] As Figure 4 shown, Figure 1 The relative illumination values of the large target surface, wide spectrum and ultraviolet imaging lens in the full field of view are all greater than 78.4%, avoiding the appearance of dark corners.

[0029] The above-described embodiments only express the preferred embodiments of the present application, which are described in more detail and in more detail, but the present application is not limited to these embodiments. It should be noted that for those skilled in the art. Any improvement made without departing from the purpose of the present application falls within the scope of the present application. Therefore, the protection scope of the present application patent should be subject to the appended claims.

Claims

1. A large target, wide spectral ultraviolet imaging lens for machine vision, characterized in that, The first lens, the second lens, the third lens, the aperture stop, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens and the ninth lens are arranged along the optical axis direction; The first lens is a positive meniscus lens, the second lens is a negative double-concave lens, the third lens is a positive meniscus lens, the fourth lens is a positive double-convex lens, the fifth lens is a negative double-concave lens, the sixth lens is a positive double-convex lens, the seventh lens is a positive meniscus lens, the eighth lens is a positive meniscus lens, and the ninth lens is a negative plano-concave lens; The object side surface of the first lens is a convex surface, and the image side surface is a concave surface; the object side surface of the eighth lens is a concave surface, and the image side surface is a convex surface; and the object side surface of the ninth lens is a convex surface, and the image side surface is a plane surface; The system focal lengths of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens and the ninth lens are F1, F2, F3, F4, F5, F6, F7, F8 and F9 respectively, and the focal length F of the optical system formed by the lenses satisfies the following focal length relationship: 0.5<F1 / F<0.7; -0.4<F2 / F<-0.2; 1.4<F3 / F<1.6; 0.2<F4 / F<0.4; -0.4<F5 / F<-0.2; 0.5<F6 / F<0.7; 2<F7 / F<4; 1.6<F8 / F<1.8; and -1.3<F9 / F≤-1.

21.

2. The large target, wide spectral ultraviolet imaging lens for machine vision according to claim 1, characterized in that, The air gap between the first lens and the second lens is 4.7mm, the air gap between the second lens and the third lens is 7.5mm, the air gap between the third lens and the aperture stop is 3.0mm, the air gap between the aperture stop and the fourth lens is 1.6mm, the air gap between the fourth lens and the fifth lens is 6.6mm, the air gap between the fifth lens and the sixth lens is 5.6mm, the air gap between the sixth lens and the seventh lens is 0.3mm, the air gap between the seventh lens and the eighth lens is 4.0mm, the air gap between the eighth lens and the ninth lens is 11.0mm, and the air gap between the ninth lens and the imaging surface is 52.5mm.

3. The large target, wide spectral ultraviolet imaging lens for machine vision according to claim 1, characterized in that, The first lens, the third lens, the fourth lens, the sixth lens, the eighth lens and the ninth lens are made of calcium fluoride material, and the second lens, the fifth lens and the seventh lens are made of fused quartz material.

4. The large target, wide spectral ultraviolet imaging lens for machine vision according to claim 1, characterized in that, The total optical length TTL of the ultraviolet imaging lens and the maximum image height IH corresponding to the maximum field angle of the ultraviolet imaging lens satisfy: 3.5≤TTL / IH≤4.

2.

5. The large target, wide spectral ultraviolet imaging lens for machine vision according to claim 1, characterized in that, The back focal length BFL of the ultraviolet imaging lens and the focal length F of the optical system satisfy: 0.3≤BFL / F≤0.5.

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