A micro-industrial lens suitable for 40mm-2m and imaging method thereof

Abstract

The present application relates to a kind of macro industrial lens suitable for 40mm-2m and its imaging method, the optical system of the lens has 6 pieces of lens with optical power, in the order of incident direction along optical path, it is first lens, second lens, third lens, fourth lens, fifth lens and sixth lens, and diaphragm is arranged between first lens and second lens;First lens is meniscus positive lens, its object side is convex, and image side is concave;Second lens is double-convex positive lens;Third lens is double-concave negative lens;Fourth lens is meniscus positive lens, its object side is concave, and image side is convex;Fifth lens is meniscus negative lens, its object side is concave, and image side is convex;Sixth lens is meniscus positive lens, its object side is concave, and image side is convex;All lenses are spherical lens and made of glass material, wherein second lens, third lens constitute first cemented lens group, and fifth lens, sixth lens constitute cemented lens group.

Description

Technical Field

[0001] This invention relates to the field of lens technology, and in particular to a macro industrial lens suitable for 40mm-2m and its imaging method. Background Technology

[0002] Industrial macro lenses are specialized lenses used for macro photography, primarily for capturing extremely small objects. In machine vision inspection systems, they can be used for close-up observation of workpieces. To ensure accurate focusing even at very close distances, industrial macro lenses are typically designed to extend further, maximizing the optical center's distance from the sensor. Furthermore, the lens group design must prioritize controlling distortion and chromatic aberration at close range. Most industrial macro lenses are fixed-focus, ranging from 50mm to 200mm, with a maximum aperture generally of f / 2.8. The focal length does not affect magnification. Industrial macro lenses are designed for precise macro imaging, providing clear images at short working distances and exhibiting low distortion, comparable to telecentric lenses. However, as the applications of industrial lenses broaden, the market demands even closer-focusing industrial macro lenses. Summary of the Invention

[0003] In view of this, the purpose of this invention is to provide a macro industrial lens and imaging method suitable for 40mm-2m, which takes into account the optical characteristics of high resolution, low distortion and 40mm-2m macro, and can perform more comprehensive inspection.

[0004] This invention is achieved using the following scheme: a macro industrial lens suitable for 40mm-2m, wherein the optical system of the lens has 6 lenses with optical power, arranged sequentially along the incident direction of the light path as a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens, with an aperture stop between the first lens and the second lens; the first lens is a meniscus positive lens with a convex object-side surface and a concave image-side surface; the second lens is a biconvex positive lens; the third lens is a biconcave negative lens; the fourth lens is a meniscus positive lens with a concave object-side surface and a convex image-side surface; the fifth lens is a meniscus negative lens with a concave object-side surface and a convex image-side surface; the sixth lens is a meniscus positive lens with a concave object-side surface and a convex image-side surface; all lenses are spherical lenses and made of glass material, wherein the second and third lenses constitute a first cemented lens group, and the fifth and sixth lenses constitute a cemented lens group.

[0005] Furthermore, the focal length of the optical system is f, and the focal lengths of the first lens, second lens, third lens, fourth lens, fifth lens, and sixth lens are f1, f2, f3, f4, f5, and f6, respectively, where f1, f2, f3, f4, f5, and f6 satisfy the following ratio with f: 0.1 <f1 / f <1.0,0.1<f2 / f <1.0,-1.0<f3 / f<-0.154,0.1<f4 / f <1.0,-1.0<f5 / f <-0.398,0.1<f6 / f <1.0。

[0006] Furthermore, the first lens satisfies the relationship: 1.5 ≤ N d ≤1.8, V d ≥50.0; The second lens satisfies the relationship: 1.4≤N d ≤1.7, V d ≥50.0; The third lens satisfies the relationship: 1.7≤N d ≤2.0, V d ≤50.0; The fourth lens satisfies the relation: 1.7≤N d ≤2.0, V d ≤50.0; The fifth lens satisfies the following relationship: V d ≤50.0; The sixth lens satisfies the relation: 1.7≤N d ≤2.0, V d ≥50.0; where N d V is the refractive index. d Let be Abbe's constant.

[0007] Furthermore, the air gap between the first lens and the aperture stop is 0.1~0.5mm; the air gap between the aperture stop and the second lens is 0.1~0.5mm; the second lens and the third lens form a first cemented lens group with an air gap of 0; the air gap between the third lens and the fourth lens is 2.0~2.5mm; the air gap between the fourth lens and the fifth lens is 2.5~3.0mm; and the fifth lens and the sixth lens form a cemented lens group with an air gap of 0.

[0008] Furthermore, the total optical length (TTL) of the optical system and the focal length (f) of the optical system satisfy the following condition: TTL / f ≤ 2.0.

[0009] Furthermore, the image height H of the optical system and the focal length f of the optical system satisfy the following condition: H / f≤1.0.

[0010] Furthermore, a filter is provided on the rear side of the sixth lens.

[0011] Another technical solution of the present invention: an imaging method applicable to macro industrial lenses of 40mm-2m as described above, wherein light passes through a first lens, an aperture, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens and a filter in sequence to form an image.

[0012] Compared with the prior art, the present invention has the following beneficial effects: (1) The lens has an imaging angle of more than 16 degrees for objects, and has the advantages of 40mm-2m macro, low distortion, high resolution, high relative illumination, low tolerance sensitivity and good high and low temperature stability, thus enabling more comprehensive detection. (2) By reasonably matching the optical lenses, the system structure is compact and reasonable, easy to assemble, has low tolerance sensitivity, and is more suitable for large-scale high-yield production; (3) All glass spherical lenses are used, which reduces costs to a certain extent while adapting to the environment; (4) It can compensate for focal plane displacement at high and low temperatures and has adaptability to complex environments; (5) The chromatic aberration along each axis, the vertical axis, and the higher-order chromatic aberrations have been corrected to ensure that the imaging system can have high imaging quality even at large angles.

[0013] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below through specific embodiments and related drawings. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the optical system structure according to an embodiment of the present invention; Figure 2 This is the axial chromatic aberration diagram of the optical system of this embodiment across the entire operating band; Figure 3 This is a transverse chromatic aberration diagram of the optical system of this embodiment across the entire operating band; Figure 4 This is a field curvature distortion diagram of the optical system in the embodiment of the present invention across the entire operating band; In the diagram: STO - aperture stop; L1 - first lens; L2 - second lens; L3 - third lens; L4 - fourth lens; L5 - fifth lens; L6 - sixth lens; L7 - equivalent glass plate; L8 - equivalent glass plate; IMA - imaging plane. Detailed Implementation

[0015] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0016] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0017] like Figure 1 As shown, a macro industrial lens suitable for 40mm-2m is described. The optical system of the lens has six lenses with optical power, arranged sequentially along the incident direction of the light path as a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens. An aperture stop is provided between the first lens and the second lens. Ignoring the curvature caused by aspherical coefficients, the first lens is a meniscus positive lens with a convex object-side surface and a concave image-side surface; the second lens is a biconvex positive lens with a convex object-side surface and a convex image-side surface; the third lens is a biconcave negative lens with a concave object-side surface and a concave image-side surface; the fourth lens is a meniscus positive lens with a concave object-side surface and a convex image-side surface; the fifth lens is a meniscus negative lens with a concave object-side surface and a convex image-side surface; and the sixth lens is a meniscus positive lens with a concave object-side surface and a convex image-side surface. All lenses are spherical lenses made of glass. The second and third lenses constitute a first cemented lens group, and the fifth and sixth lenses constitute a cemented lens group.

[0018] The optical system employs a combination of positive and negative lens power, significantly reducing optical aberrations such as spherical aberration. The second and third lenses are achromatic cemented doublet groups, as are the fifth and sixth lenses. This optimized lens configuration enables the optical system to achieve macro capabilities from 40mm to 2m, suitability for high-temperature environments, and excellent correction of on-axis and off-axis aberrations, resulting in superior image quality. Figures 2 to 4 As shown.

[0019] In this embodiment, the focal length of the optical system is f, and the focal lengths of the first lens, second lens, third lens, fourth lens, fifth lens, and sixth lens are f1, f2, f3, f4, f5, and f6, respectively. The ratios of f1, f2, f3, f4, f5, and f6 to f satisfy the following ratio: 0.1 <f1 / f <1.0,0.1<f2 / f <1.0,-1.0<f3 / f<-0.154,0.1<f4 / f <1.0,-1.0<f5 / f <-0.398,0.1<f6 / f <1.0。

[0020] In this embodiment, the first lens satisfies the relationship: 1.5 ≤ N d ≤1.8, Vd ≥50.0; The second lens satisfies the relationship: 1.4≤N d ≤1.7, V d ≥50.0; The third lens satisfies the relationship: 1.7≤N d ≤2.0, V d ≤50.0; The fourth lens satisfies the relation: 1.7≤N d ≤2.0, V d ≤50.0; The fifth lens satisfies the following relationship: V d ≤50.0; The sixth lens satisfies the relation: 1.7≤N d ≤2.0, V d ≥50.0; where N d V is the refractive index. d Let be Abbe's constant.

[0021] In this embodiment, the air gap between the first lens and the aperture stop is 0.1~0.5mm; the air gap between the aperture stop and the second lens is 0.1~0.5mm; the second lens and the third lens form a first cemented lens group with an air gap of 0; the air gap between the third lens and the fourth lens is 2.0~2.5mm; the air gap between the fourth lens and the fifth lens is 2.5~3.0mm; the fifth lens and the sixth lens form a cemented lens group with an air gap of 0. Reducing the distance between each lens while meeting imaging requirements is beneficial to the overall optical length of the lens.

[0022] In this embodiment, the total optical length (TTL) of the optical system and the focal length (f) of the optical system satisfy the following condition: TTL / f ≤ 2.0.

[0023] In this embodiment, the image height H of the optical system and the focal length f of the optical system satisfy the following condition: H / f≤1.0.

[0024] In this embodiment, a filter is provided on the rear side of the sixth lens.

[0025] The technical specifications achieved by the optical system in this embodiment are as follows: (1) Focal length: EFFL = 22mm; (2) Operating band: Visible light band.

[0026] To achieve the above design parameters, the specific design of the optical system adopted in this embodiment is shown in the table below:

[0027] This invention, through a reasonable lens combination, enables the optical system to achieve a balance of high resolution, low distortion, macro capability (40mm-2m), and suitability for high-temperature environments. Furthermore, by effectively correcting on-axis and off-axis aberrations, the lens exhibits superior image quality. Figures 2 to 4 As shown.

[0028] An imaging method applicable to macro industrial lenses of 40mm-2m as described above, wherein light passes sequentially through a first lens, an aperture, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a filter before forming an image.

[0029] Unless otherwise stated, if any of the technical solutions disclosed in this invention specify a numerical range, then the disclosed numerical range is a preferred numerical range. Anyone skilled in the art should understand that the preferred numerical range is merely one among many feasible numerical values ​​that has a more obvious or representative technical effect. Because there are many numerical values, it is impossible to list them all. Therefore, this invention discloses only some numerical values ​​to illustrate the technical solutions of this invention. Furthermore, the numerical values ​​listed above should not constitute a limitation on the scope of protection of this invention.

[0030] If this invention discloses or relates to mutually fixedly connected components or structural parts, then, unless otherwise stated, a fixed connection can be understood as: a detachable fixed connection (e.g., using bolts or screws), or a non-detachable fixed connection (e.g., riveting, welding). Of course, mutually fixed connections can also be replaced by an integral structure (e.g., manufactured in one piece using a casting process) (except where it is obviously impossible to use an integral molding process).

[0031] In addition, unless otherwise stated, the terms used in any of the technical solutions disclosed in this invention to indicate positional relationships or shapes include states or shapes that are similar to, close to, or approximate with those states or shapes.

[0032] Any component provided by this invention can be assembled from multiple individual components or can be a single component manufactured by a one-piece molding process.

[0033] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A macro industrial lens suitable for 40mm-2m distances, characterized in that: The optical system of the lens comprises six lenses with optical power, arranged sequentially along the incident light path as a first lens, second lens, third lens, fourth lens, fifth lens, and sixth lens. An aperture stop is positioned between the first and second lenses. The first lens is a meniscus positive lens with a convex object-side surface and a concave image-side surface. The second lens is a biconvex positive lens. The third lens is a biconcave negative lens. The fourth lens is a meniscus positive lens with a concave object-side surface and a convex image-side surface. The fifth lens is a meniscus negative lens with a concave object-side surface and a convex image-side surface. The sixth lens is a meniscus lens with a concave object side and a convex image side. All lenses are spherical lenses made of glass. The second and third lenses form the first cemented lens group, and the fifth and sixth lenses form the third cemented lens group. The focal length of the optical system is f. The focal lengths of the first, second, third, fourth, fifth, and sixth lenses are f1, f2, f3, f4, f5, and f6, respectively, where f1, f2, f3, f4, f5, and f6 satisfy the following ratio with f: 0.1 <f1 / f <1.0,0.1< f2 / f <1.0,-1.0< f3 / f <-0.154,0.1< f4 / f <1.0,-1.0< f5 / f <-0.398,0.1< f6 / f <1.0。 2. The macro industrial lens suitable for 40mm-2m as described in claim 1, characterized in that: The first lens satisfies the relationship: 1.5 ≤ N d ≤1.8, V d ≥50.0; The second lens satisfies the relationship: 1.4≤N d ≤1.7, V d ≥50.0; The third lens satisfies the relationship: 1.7≤N d ≤2.0, V d ≤50.0; The fourth lens satisfies the relation: 1.7≤N d ≤2.0, V d ≤50.0; The fifth lens satisfies the following relationship: V d ≤50.0; The sixth lens satisfies the relation: 1.7≤N d ≤2.0, V d ≥50.0; where N d V is the refractive index. d Let be Abbe's constant.

3. The macro industrial lens suitable for 40mm-2m as described in claim 1, characterized in that: The air gap between the first lens and the aperture stop is 0.1~0.5mm; the air gap between the aperture stop and the second lens is 0.1~0.5mm; the second lens and the third lens form the first cemented lens group with an air gap of 0; the air gap between the third lens and the fourth lens is 2.0~2.5mm; the air gap between the fourth lens and the fifth lens is 2.5~3.0mm; the fifth lens and the sixth lens form the cemented lens group with an air gap of 0.

4. The macro industrial lens suitable for 40mm-2m as described in claim 1, characterized in that: The total optical length (TTL) of an optical system and the focal length (f) of the optical system satisfy the following condition: TTL / f ≤ 2.

0.

5. The macro industrial lens suitable for 40mm-2m as described in claim 1, characterized in that: The image height H of the optical system and the focal length f of the optical system satisfy the following condition: H / f≤1.

0.

6. The macro industrial lens suitable for 40mm-2m as described in claim 1, characterized in that: A filter is provided on the rear side of the sixth lens.

7. An imaging method for macro industrial lenses of 40mm-2m as described in claim 6, characterized in that: The light rays pass through the first lens, the aperture, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the filter in sequence to form an image.

Images