CN218181196U

CN218181196U - Industrial macro lens

Info

Publication number: CN218181196U
Application number: CN202222613356.5U
Authority: CN
Inventors: 贺艳芳; 曾振煌
Original assignee: Guangdong OPT Machine Vision Co Ltd
Current assignee: Guangdong OPT Machine Vision Co Ltd
Priority date: 2022-09-30
Filing date: 2022-09-30
Publication date: 2022-12-30
Anticipated expiration: 2032-09-30

Abstract

The utility model relates to the technical field of optical imaging, in particular to an industrial macro lens, which is provided with a front group T1 with positive focal power, a diaphragm S and a rear group T2 with positive focal power in sequence from an object space to an image space; wherein the focal length of the industrial macro lens is f, and the focal length of the front group T1 is f _T1 The focal length of the rear group T2 is f _T2 The following relational expression is satisfied: 0.65<|f _T1 /f|<0.75，1.8<|f _T2 /f|<1.9. The utility model provides an industryThe macro lens has higher resolution ratio during short-distance imaging, and is beneficial to improving the imaging precision of products.

Description

Industrial macro lens

Technical Field

The utility model relates to an optical imaging technical field especially relates to an industry macro lens.

Background

In the precision machining process, an industrial lens is often required to be adopted to acquire images of a product so as to complete the positioning and detection work of the product. With the wide application of machine vision systems in the field of precision detection, the existing industrial lenses have difficulty in meeting the detection requirements. For example, when an existing industrial lens is used for image acquisition, the working distance is generally long (greater than 120 mm), and when the industrial lens is used for close-range imaging (the working distance is less than 120 mm), the imaging definition is suddenly reduced, so that the positioning accuracy and the detection accuracy of a product are affected.

Therefore, there is a need for an improvement of the existing industrial lens to solve the problem of low definition in the close-range imaging.

The above information disclosed in this background section is only included to enhance understanding of the background of the disclosure and, thus, may contain information that does not form the prior art that is currently known to those of ordinary skill in the art.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide an industry macro lens, can have higher resolution ratio when closely forming images, be favorable to improving the imaging precision of product.

In order to achieve the above object, the present invention provides an industrial macro lens, which is sequentially provided with a front group T1 having positive focal power, a diaphragm S and a rear group T2 having positive focal power from an object space to an image space;

wherein the focal length of the industrial macro lens is f, and the focal length of the front group T1 is f _T1 The focal length of the rear group T2 is f _T2 The following relational expression is satisfied: 0.65<|f _T1 /f|<0.75，1.8<|f _T2 /f|<1.9。

Optionally, the front group T1 includes, in order from the object side to the image side, a biconvex first lens G1 with positive focal power, a biconcave second lens G2 with negative focal power, a biconvex third lens G3 with positive focal power, a biconvex fourth lens G4 with positive focal power, and a biconcave fifth lens G5 with negative focal power;

the first lens G1 and the second lens G2 are combined into a first cemented lens group U1 with negative focal power, and the fourth lens G4 and the fifth lens G5 are combined into a second cemented lens group U2 with negative focal power.

Optionally, the rear group T2 includes, in order from the object side to the image side, a meniscus sixth lens G6 with negative focal power, a meniscus seventh lens G7 with positive focal power, and a double-convex eighth lens G8 with positive focal power;

the sixth lens G6 and the seventh lens G7 are combined into a third cemented lens group U3 with negative focal power.

Optionally, a distance L from a vertex of a front surface of the first lens G1 to a vertex of a rear surface of the eighth lens G8 of the industrial macro lens and a focal length f of the industrial macro lens satisfy a relation: 1.0< | L/f | <1.2.

Optionally, a ratio of the optical back focal length BFL to the focal length f of the industrial macro lens satisfies a relation: 0.5< | BFL/f | is less than 0.9.

Optionally, the focal length f of the first cemented lens group U1 _U1 And the ratio of the focal length f of the industrial macro lens satisfies the relation: 10 < | f _U1 /f|＜12。

Optionally, the focal length f of the third lens G3 _G3 The ratio of the focal length f of the industrial macro lens to the focal length f of the industrial macro lens satisfies the relation: 0.4 < | f _G3 /f|＜0.6。

Optionally, the focal length f of the second cemented lens group U2 _U2 The ratio of the focal length f of the industrial macro lens to the focal length f of the industrial macro lens satisfies the relational expression: 0.9 < | f _U2 /f|＜1.1。

Optionally, the focal length f of the third cemented lens group U3 _U3 The ratio of the focal length f of the industrial macro lens to the focal length f of the industrial macro lens satisfies the relation: 0.7 < | f _U3 /f|＜1.0。

Optionally, the focal length f of the eighth lens G8 _G8 The ratio of the focal length f of the industrial macro lens to the focal length f of the industrial macro lens satisfies the relational expression: 0.7 < | f _G8 /f|＜1.0。

The beneficial effects of the utility model reside in that, a industry macro lens is provided, be applicable to the applied scene of closely forming images, carry out reasonable optimization through the focal parameter to the front and back group of mirror and match, can have higher resolution ratio when having guaranteed closely forming images, be favorable to improving the imaging accuracy of product.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without inventive exercise.

Fig. 1 is a schematic structural diagram of an industrial macro lens according to an embodiment;

FIG. 2 is a distortion curve of an industrial macro lens according to an embodiment;

fig. 3 is a MTF graph of an industrial macro lens according to an embodiment.

Detailed Description

In order to make the objects, features and advantages of the present invention more obvious and understandable, the embodiments of the present invention are clearly and completely described with reference to the drawings in the embodiments of the present invention, and obviously, the embodiments described below are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.

In the description of the present invention, it is to be understood that when an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. When a component is referred to as being "disposed on" another component, it can be directly on the other component or intervening components may also be present.

Furthermore, the terms "long", "short", "inner", "outer", and the like indicate orientations or positional relationships based on the orientations or positional relationships illustrated in the drawings, and are only for convenience of describing the present invention, but do not indicate or imply that the device or element referred to must have the specific orientation, operate in the specific orientation configuration, and thus, should not be construed as limiting the present invention.

The present invention will be described in detail below with reference to specific embodiments shown in the drawings. However, these embodiments are not intended to limit the present invention, and structural, methodical, or functional changes that may be made by one of ordinary skill in the art based on these embodiments are all included in the scope of the present invention.

The utility model provides an industry macro lens is applicable to the application scene at closely clear formation of image, and it still can clear formation of image when working distance is less than 120mm, is favorable to improving the imaging precision of product.

Referring to fig. 1, in the present embodiment, the industrial macro lens is sequentially provided with a front group T1 with positive focal power, a diaphragm S, and a rear group T2 with positive focal power from an object side to an image side;

Optionally, the front group T1 includes, in order from the object side to the image side, a biconvex first lens G1 having positive focal power, a biconcave second lens G2 having negative focal power, a biconvex third lens G3 having positive focal power, a biconvex fourth lens G4 having positive focal power, and a biconcave fifth lens G5 having negative focal power;

Optionally, the focal length f of the second cemented lens group U2 _U2 The ratio of the focal length f of the industrial macro lens to the focal length f of the industrial macro lens satisfies the relation: 0.9 < | f _U2 /f|＜1.1。

Optionally, the focal length f of the eighth lens G8 _G8 The ratio of the focal length f of the industrial macro lens to the focal length f of the industrial macro lens satisfies the relation: 0.7 < | f _G8 /f|＜1.0。

Specific parameters are selected as examples for explanation. In an alternative example, the physical parameters of each lens or cemented lens group are shown in table 1 below:

TABLE 1 summary of physical parameters of selected lens or cemented lens group

Surface of	Radius (mm)	Thickness (mm)	Refractive index
				Article surface	Plane surface	93
U1 front surface	30.1	8.1	1.61
				U1 cemented surface	-30.1	2.6	1.85
U1 rear surface	49.9	7.1
				G3 front surface	29.4	8.0	1.92
G3 rear surface	-116.8	0.8
				U2 front surface	11.2	3.9	1.66
U2 cemented surface	-1201.9	1.9	1.81
				U2 rear surface	8.3	3.5
Diaphragm S	Plane surface	4.7
				U3 front surface	-11.1	1.2	1.74
U3 cemented surface	-173.4	2.3	1.65
				U3 rear surface	-17.4	11.1
G8 front surface	253.7	2.5	1.66
				G8 rear surface	-30.5	33.3
Image plane	Plane surface

In the above-mentioned selection example, the focal length f =50mm, and the aperture is D/f =1/2.8; focal length f of front group T1 _T1 =34.9mm; focal length f of rear group T2 _T2 =92.9mm; the distance L =57.5mm from the front surface vertex of the first lens G1 to the rear surface vertex of the eighth lens G8; optical back intercept BFL =33.3mm; focal length of the first cemented lens group is f _U1 = -574.3mm; the third lens G3 has a focal length f _G3 =25.8mm; focal length f of the second cemented lens group _U2 = 50.7mm; the eighth lens G8 has a focal length f _G8 ＝41.3mm。

Each relation:

l/f | =1.14, satisfying 1.0< | L/f | <1.2;

i BFL/f I =0.66, which satisfies 0.5< | BFL/f | less than 0.9;

|f _T1 (| = 0.69), satisfy 0.65<|f _T1 /f|<0.75；

|f _T2 The (| = 1.85) meets 1.8<|f _T2 /f|<1.9；

|f _U1 (| = 11.4) |, satisfies 10 < | f _U1 /f|＜12；

|f _G3 F | =0.51, satisfy 0.4 < | f _G3 /f|＜0.6；

|f _U2 F | =1.01, satisfy 0.9 < | f _U2 /f|＜1.1；

|f _U3 F | =0.83, satisfy 0.7 < | f _U3 /f|＜1.0；

|f _G8 F | =0.82, satisfy 0.7 < | f _G8 /f|＜1.0。

Experiments show that the industrial macro lens in the selection example can achieve the following technical indexes:

A. distortion: <0.1%, see in particular fig. 2, maximum optical distortion over the full field of view is below 0.1%;

B. aperture: f2.8;

C. image height: 17.6mm;

D. the multiplying power range is as follows: -0.5x to-0.8 x;

E. variation range of back focus: 23.9 mm-39.9 mm;

F. resolution ratio: referring to FIG. 3, the central field MTF is greater than 0.3 at 145lp/mm, and the MTFs for the full field are each greater than 0.2 at 145 lp/mm.

Compared with the prior art, the beneficial effects of the industrial macro lens that this embodiment provided include:

(1) the focal parameters of the front and rear lens groups are reasonably optimized and matched, so that higher resolution ratio is ensured during short-distance imaging, and the imaging precision of a product is improved;

specifically, when the working distance is between 80mm and 120mm, the industrial macro lens can still clearly image, and when the working distance is 80mm, the MTF of the full field of view is greater than 0.2 at 145lp/mm, so that higher resolution is ensured;

(2) the structural composition of the front group T1 is optimized, the aberration of the industrial macro lens is corrected, the resolution and the brightness of an image are further improved, the integral distortion of the industrial macro lens is lower than 0.1%, the requirement of low distortion of the industrial lens is met, and the integral relative illumination of the lens is uniform;

(3) eight spherical lenses are used totally, the system structure is simple, and the cost is low.

It should be understood that although the present description refers to embodiments, not every embodiment contains only a single technical solution, and such description is for clarity only, and those skilled in the art should make the description as a whole, and the technical solutions in the embodiments can also be combined appropriately to form other embodiments understood by those skilled in the art.

The above list of detailed descriptions is only for the specific description of the feasible embodiments of the present invention, and they are not intended to limit the scope of the present invention, and all equivalent embodiments or modifications that do not depart from the technical spirit of the present invention should be included within the scope of the present invention.

Claims

1. An industrial macro lens is characterized in that a front group T1 with positive focal power, a diaphragm S and a rear group T2 with positive focal power are sequentially arranged from an object space to an image space;

2. The industrial macro lens according to claim 1, wherein the front group T1 includes, in order from an object side to an image side, a double convex first lens G1 having positive power, a double concave second lens G2 having negative power, a double convex third lens G3 having positive power, a double convex fourth lens G4 having positive power, a double concave fifth lens G5 having negative power;

3. The industrial macro lens according to claim 2, characterized in that said rear group T2 comprises, in order from the object side to the image side, a meniscus sixth lens G6 with negative power, a meniscus seventh lens G7 with positive power and a biconvex eighth lens G8 with positive power;

4. The industrial macro lens according to claim 3, wherein a distance L from a vertex of a front surface of the first lens G1 to a vertex of a rear surface of the eighth lens G8 of the industrial macro lens and a focal length f of the industrial macro lens satisfy a relation: 1.0< | L/f | <1.2.

5. The industrial macro lens according to claim 1, wherein a ratio of an optical back intercept BFL to a focal length f of the industrial macro lens satisfies a relation: 0.5< | BFL/f | is less than 0.9.

6. The industrial macro lens according to claim 2, wherein the focal length f of the first cemented lens group U1 _U1 And the ratio of the focal length f of the industrial macro lens satisfies the relation: 10 < | f _U1 /f|＜12。

7. Industrial macro lens according to claim 6, characterized in that the focal length f of the third lens G3 _G3 The ratio of the focal length f of the industrial macro lens to the focal length f of the industrial macro lens satisfies the relation: 0.4 < | f _G3 /f|＜0.6。

8. The industrial macro lens according to claim 2, wherein the focal length f of the second cemented lens group U2 _U2 The ratio of the focal length f of the industrial macro lens to the focal length f of the industrial macro lens satisfies the relation: 0.9 < | f _U2 /f|＜1.1。

9. The industrial macro lens according to claim 3, wherein the focal length f of the third cemented lens group U3 _U3 The ratio of the focal length f of the industrial macro lens to the focal length f of the industrial macro lens satisfies the relation: 0.7 < | f _U3 /f|＜1.0。

10. The industrial macro lens of claim 9, wherein the eighth lens G8 has a focal length f _G8 Focal distance with the industrial macro lensThe ratio of the distances f satisfies the relation: 0.7 < | f _G8 /f|＜1.0。