CN115032778B

CN115032778B - Variable-magnification assembly of industrial lens

Info

Publication number: CN115032778B
Application number: CN202210708311.8A
Authority: CN
Inventors: 吴帅; 吴沛林
Original assignee: Guangzhou Changbudao Optical Technology Co ltd
Current assignee: Guangzhou Changbudao Optical Technology Co ltd
Priority date: 2022-06-21
Filing date: 2022-06-21
Publication date: 2023-06-02
Anticipated expiration: 2042-06-21
Also published as: CN115032778A

Abstract

The invention relates to a zoom component of an industrial lens of a large target surface industrial lens, which is arranged in the object space or the image space of the industrial lens to change the magnification of a system. When placed in image space, the assembly is composed of a positive lens H1, a negative lens H2, a 1 st doublet lens group H34 and a 2 nd doublet lens group H56 in sequence from left to right. The construction layout in the case of object space is the inverse of the image space construction layout. The variable magnification element provided by the invention has the working wave band of visible light, and when the variable magnification element is matched with a specific large-target industrial lens for use, the use magnification of an optical system can be widened, the magnification use cost of the industrial lens is reduced, and the wide application of a machine vision detection system is further promoted.

Description

Variable-magnification assembly of industrial lens

Technical Field

The invention belongs to the technical field of industrial lenses, and particularly relates to a magnification-changing element device which is detachably arranged at the front end (object side) or the rear end (image side) of a large-target industrial lens to enlarge or reduce the magnification of an overall system.

Background

As an optical system that needs to be incorporated in a main lens so as to change the focal length of the entire system, it is necessary to realize conversion between the lens and the camera. A rear-mounted conversion mirror mounted between a main lens and a camera is known, and a rear-mounted distance-increasing mirror having excellent optical performance and an image pickup apparatus provided with the rear-mounted distance-increasing mirror are disclosed in patent document CN 109507790A. The rear distance-increasing lens is composed of a 1 st lens group (RG 1), a 2 nd lens group (RG 2) and a 3 rd lens group (RG 3) in order from the object side, wherein the 1 st lens group (RG 1) is composed of a joint lens formed by jointing a negative lens (RL 1 a) with a concave surface facing the image side and a positive lens (RL 1 b) with a convex surface facing the object side, the 2 nd lens group (RG 2) is composed of a joint lens formed by jointing a negative lens (RL 2 a) with a concave surface facing the image side, a positive lens (RL 2 b) with a convex surface facing both sides and a negative lens (RL 2 c) with a concave surface facing the object side, and the 3 rd lens group (RG 3) is composed of a joint lens formed by jointing a positive lens (RL 3 a) with a convex surface facing the object side and a negative lens (RL 3 b) and satisfies prescribed conditional expressions (1 and (2). However, focusing on the field of consumer use, because the viewing distance is relatively long (usually 1.5m to infinity), the focal length is a key parameter for representing the shooting range of the lens under the same frame, so that the detachable optical system in this field is generally described by calibrating the focal length of the system.

Industrial lenses used in the machine vision field usually have very close working distances, so that the use of magnification and the size of the target surface of an industrial camera to describe the detection range is more intuitive. The research results of a detachable optical device similar to a main lens in the field of machine vision are not much, and magnification sections capable of meeting the expected optical performance under the condition of large target surface imaging are narrow. Therefore, the optical element of the specific combination is required to greatly distinguish the magnification of the composite optical system from the magnification of the main lens, and the object distance and the back focus are not changed at the same time, so that certain optical performance can be further realized. The cost of the whole optical system which is needed to be customized again due to insufficient multiplying power of the main lens can be saved to a certain extent.

Disclosure of Invention

In order to solve the above-mentioned problems, a primary object of the present invention is to provide a zoom assembly for industrial lenses, which is applied to large-target industrial lenses to change the magnification of an optical system and meet the detection requirement of the required magnification at a specific working distance.

Another object of the present invention is to provide a zoom assembly for an industrial lens, which can widen the use magnification of an optical system, reduce the magnification use cost of the industrial lens, and promote the wide application of a machine vision detection system.

In order to achieve the above object, the technical scheme of the present invention is as follows.

The variable magnification component HL of the industrial lens has positive focal power and comprises a positive lens H1, a negative lens H2, a 1 st double-cemented lens group H34 and a 2 nd double-cemented lens group H56 which are arranged along the transmission direction of incident light when placed in an image space; the 1 st double-cemented lens group H34 is formed by a negative lens H3 and a positive lens H4, and the 2 nd double-cemented lens group H56 is formed by a positive lens H5 and a negative lens H6; the structural layout in the case of object space is the exact opposite of the image space structural layout; the focal lengths f (H34) and f (H56) of the 1 st and 2 nd cemented lens groups and the focal length f (HL) of the magnification varying assembly HL satisfy the following relational expressions (1) and (2):

0.2＜f(H34)/f(HL)＜0.4； (1)

0.55＜-f(H56)/f(HL)＜0.75。 (2)

when the component HL is placed in the object space of the industrial lens, different multiplying powers of the optical system can be realized under specific object distance and main lens distance, and at the moment, the focal plane position of the synthetic optical system is consistent with that of the main lens. When the assembly HL is placed in the image space of an industrial lens, there is a separation from the main lens that optimizes the optical performance of the composite optical system.

Further, in the zoom module of the present invention, the following conditional expressions (3) (4) (5) (6) (7) (8) (9) are also satisfied:

0.05＜N(p-avg)-N(n-avg)＜0.25。(3)

0.04＜∑(air)/f(HL)＜0.08。 (4)

0.3＜f(H4)/f(H34)＜0.5。 (5)

0.5＜f(H6)/f(H56)＜0.6。 (6)

4.5＜[(1/f(H34)-1/f(H56)]*f(HL)＜5.5。 (7)

1.8＜[(1/f(H34)+1/f(H56)]*f(HL)＜2.1。 (8)

0.3＜-f(H34)/f(H56)＜0.6。 (9)

wherein N (p-avg) is the average value of the refractive index of all positive lenses in the variable magnification assembly with respect to the d-line; n (N-avg) is the average value of the refractive index of d-line of all negative lenses in the variable magnification block, Σ (air) is the sum of all air intervals on the optical axis included in the variable magnification block, and f (H4) is the positive lens focal length of the 1 st cemented lens group; f (H6) is the negative lens focal length of the second cemented lens group, and f (H34) is the focal length of the 1 st cemented lens group; f (H56) is the focal length of the second cemented lens group; f (HL) is the focal length of the entire zoom assembly.

In the zoom assembly of the present invention, when the zoom lens is placed on the image side of the main lens, the positive lens H1 comprises a first curved surface and a second curved surface from the object side to the image side; the negative lens H2 comprises a third curved surface and a fourth curved surface; the first double-cemented lens comprises a fifth curved surface, a sixth curved surface and a seventh curved surface; the second double-cemented lens includes an eighth curved surface, a ninth curved surface, and a tenth curved surface.

The preferred radii of curvature (unit mm, the same applies below) of the first curved surface and the second curved surface are 83.427 and 139.982, respectively; the preferred radii of curvature of the third and fourth curved surfaces are 801.649, 76.338, respectively; preferred radii of curvature for the fifth, sixth and seventh curved surfaces are 224.175, 59.447, -105.158, respectively; preferred radii of curvature of the eighth curved surface, the ninth curved surface, and the tenth curved surface are-90.923, -59.631, and-379.509, respectively.

In the variable magnification assembly of the present invention, the positive lens H1 preferably has a center thickness of 8.98mm; the preferred center thickness of the negative lens H2 is 3mm; the preferred center thickness of the first cemented lens is 33.94mm; the preferred center thickness of the second cemented lens is 24.05mm.

The invention has the beneficial effects that:

the variable magnification element provided by the invention has the working wave band of visible light, and when the variable magnification element is matched with a specific large-target industrial lens for use, the use magnification of an optical system can be widened, the magnification use cost of the industrial lens is reduced, and the wide application of a machine vision detection system is further promoted.

Drawings

FIG. 1 is a ray trace of a magnification varying assembly placed in the object side of the main lens with a synthetic system magnification of 1.05.

Fig. 2 is a ray trace in the state of main lens magnification=0.5×state.

FIG. 3 is a ray trace of a magnification varying assembly placed in the image side of the main lens with a combined system magnification of 0.35.

Fig. 4 is an aberration diagram of the synthetic optical system ii corresponding to the state of fig. 1.

Fig. 5 is an aberration diagram of the main lens corresponding to the state of fig. 2.

Fig. 6 is an aberration diagram of the synthetic optical system i corresponding to the state of fig. 3.

Detailed Description

The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.

For convenience of description, the whole system in which the variable magnification element group is installed at the object side of the main lens is simply referred to as a synthetic optical system i. The whole system in which the variable magnification element group is installed at the image side is simply referred to as a synthetic optical system ii.

The illustrated aperture stop does not necessarily indicate a size and a shape, but indicates a position on the optical axis z. Referring to fig. 1, the magnification varying component of the present invention is disposed on the object side of the main lens, and belongs to the type i synthetic optical system, wherein the magnification is 1×. In fig. 1, the space where the dashed box is located is the object side of the main lens. The magnification varying component HL has positive focal power, and is mounted on the object side of the main lens to amplify the magnification of the system. The mounting positions shown in the figures are not the only mounting positions for pattern i, and in each mounting position the combined optical system i still maintains the same optical back focus as the main lens.

Fig. 2 is a diagram showing a layout structure of a single main lens, wherein the optimum working magnification of the main lens is set to 0.5×, and generally, the lens can be designed to work in a narrow magnification section with 0.5× as the center under the condition of changing the conjugate distance, and still maintain good optical performance.

Fig. 3 shows the magnification varying assembly of the present invention placed on the image side of the main lens, in the form of a synthetic optical system ii, which is at a magnification of 0.35 x while ensuring the same object distance as the main lens. Obviously, the magnification of the system is reduced by installing the magnification changing component HL on the image side of the main lens, at this time, the position of the magnification changing component HL on the image side of the main lens is the optimal position for suppressing the aberration, and the optical performance may be reduced when the magnification changing component HL is placed on other positions, so that the magnification changing component HL cannot be used.

When the variable magnification component HL is placed in the object space of the industrial lens, different magnifications of the optical system can be realized under the specific object distance and the main lens distance, and at the moment, the focal plane position of the composite optical system is consistent with that of the main lens. When the assembly HL is placed in the image space of an industrial lens, there is a separation from the main lens that optimizes the optical performance of the composite optical system. The zoom lens is characterized by comprising a positive focal power, a positive lens H1 and a negative lens H2, wherein the positive lens H1 and the negative lens H2 are arranged along the transmission direction of incident light when the zoom lens is placed in an image space, the 1 st double-cemented lens group H34 is formed by cementing a negative lens H3 and a positive lens H4, and the 2 nd double-cemented lens group H56 is formed by cementing a positive lens H5 and a negative lens H6. The construction layout in the case of object space is the inverse of the image space construction layout.

When the detachable zoom component HL is used as a detachable component arranged on the object side of the main lens, the optimal image quality under the corresponding magnification can be obtained within the object distance range of 25mm-250mm with the main lens on the optical axis:

first, a description will be given of a main lens numerical embodiment. Specific lens data corresponding to the monomers are shown in table 1, and table 1 is a numerical example of the monomer structure of the main lens; and data related to the specifications are shown in table 2, table 2 is a numerical example of the structure of the composite system in which the magnification varying component is placed in the image side of the main lens; and each aberration diagram of the main lens at 0.5 x magnification is given in fig. 5.

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TABLE 1

In the lens data of table 1, the left surface of the lens closest to the object surface in fig. 2 is set to be the 1 st surface, and the surface number gradually increases from left to right. The radius of curvature of each surface is given in a radius of curvature column, and the interval on the optical axis of each surface from the surface below is given in a surface interval column. Also, the refractive index at d-line (λ=587.6 nm) of each optical element is given in n columns, and the abbe coefficient at d-line (λ=587.6 nm) of each optical element is given in V columns. The sign of the radius of curvature follows the sign rule, and the case where the surface shape is convex to the object side is positive and the case where the surface shape is convex to the image side is negative.

The system parameters of the main lens shown in fig. 2 are working f.no=5.8, multiplying power pmag=0.5, and the maximum supporting phi 66mm of the imaging target surface.

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TABLE 2

In the lens data given in table 2, the unit of length is mm, but the optical system can be scaled and thus other suitable units are also applicable.

Table 3 shows the relationship between the magnification of the synthesizing system and the magnification of the synthesizing system when the magnification varying unit is placed in the object space of the main lens, and in the lens data of table 3, the left surface of the lens closest to the object surface in fig. 1 is set to be the 1 st surface, and the surface numbers are gradually increased from left to right. The radius of curvature of each surface is given in a radius of curvature column, and the interval on the optical axis of each surface from the surface below is given in a surface interval column. Also, the refractive index at d-line (λ=587.6 nm) of each optical element is given in n columns, and the abbe coefficient at d-line (λ=587.6 nm) of each optical element is given in V columns. The sign of the radius of curvature follows the sign rule, and the case where the surface shape is convex to the object side is positive and the case where the surface shape is convex to the image side is negative.

Face numbering	Radius of curvature	Thickness of (L)	Refractive index	Abbe number
					Object plane	Infinite number of cases	139.6
1	379.509	3.00	1.73	28.3
					2	59.631	21.05	1.92	20.8
3	90.923	2.71
					4	105.158	30.94	1.75	52.3
5	-59.447	3.00	1.76	27.5
					6	-224.175	7.12
7	-76.338	3.00	1.67	32.1
					8	-801.649	10.34
9	-139.982	8.98	1.92	20.8
					10	-83.427	23.93
11	40.710	7.06	1.92	20.8
					12	143.957	2.00	1.74	28.2
13	33.966	3.35
					14	69.873	6.15	1.65	33.8
15	-109.884	1.50
					16	-100.780	2.00	1.85	23.7
17	29.246	7.66	1.83	7.22
					18	Infinite number of cases	2.50
19 diaphragm	Infinite number of cases	3.63
					20	-102.905	6.03	1.68	55.5
21	-28.758	5.05	1.67	32.1
					22	140.352	3.42
23	-420.497	11.28	1.83	42.7
					24	-53.488	0.80
25	-44.308	2.00	1.74	28.2
					26	189.378	16.76	1.92	20.8
27	-83.537	187.12
					Image plane

TABLE 3 Table 3

The numerical examples shown in table 3 correspond to the cross-sectional structure of fig. 1, and the system parameters are working f.no=5.8, multiplying power pmag=1, and imaging target surface maximum support phi 58mm.

In the case of an optical back focus of 187.12mm, table 4 is a list of system parameters for the variable magnification assembly HL placed at different positions on the object side of the main lens. Table 4 gives the system magnification for different object distances and spacings d.

Object distance	60	81	99.3	112.8	126.4	139.6
							Interval d	259.5	213.8	166.3	125.4	77.8	23.9
Multiplying power	0.7	0.77	0.84	0.9	0.97	1.05

TABLE 4 Table 4

Fig. 4 shows aberration diagrams corresponding to the numerical examples shown in table 3. Fig. 4 is an aberration diagram (envelope energy diagram, distortion curve, spherical aberration curve) corresponding to the synthetic optical system ii in the state of fig. 1.

Further, the envelope energy map of each field of view and the spherical aberration and distortion curves of the system are shown in order from the left side of fig. 4. In the aberration diagram represented as an envelope energy diagram, the fields of view are distinguished by lines of different colors. In the aberration diagram showing distortion, aberration with d-line (λ=587.6 nm) as a reference wavelength is shown. In the spherical aberration diagram, aberrations on d-line (λ=587.6 nm), C-line (λ=656.3 nm), F-line (λ= 486.1 nm), g-line (λ=435.8 nm) are respectively represented by different colors. In addition, f.no of the spherical aberration diagram represents an F value, and ω of the other aberration diagrams represents a half field angle. The meaning of these symbols is described with reference to fig. 4 as an example, but the same applies to fig. 5 and 6. Fig. 5 is an aberration diagram (envelope energy diagram, distortion curve, spherical aberration curve) corresponding to the main lens of fig. 2. Fig. 6 is an aberration diagram (envelope energy diagram, distortion curve, spherical aberration curve) corresponding to the synthetic optical system i in the state of fig. 3.

The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the invention.

Claims

1. The zoom component of the industrial lens is characterized in that the working wave band of the zoom component is visible light, and the zoom component has positive focal power and is composed of a positive lens H1, a negative lens H2, a 1 st double-cemented lens group H34 and a 2 nd double-cemented lens group H56 which are arranged along the transmission direction of incident light when being placed in the image space of the industrial lens; the 1 st double-cemented lens group H34 is formed by a negative lens H3 and a positive lens H4, and the 2 nd double-cemented lens group H56 is formed by a positive lens H5 and a negative lens H6; the focal length f (H34) of the 1 st doublet lens group, the focal length f (H56) of the 2 nd doublet lens group, and the focal length f (HL) of the magnification varying assembly satisfy the following relation:

0.2＜f（H34）/ f(HL)＜0.4；

0.55＜-f（H56）/ f(HL)＜0.75。

2. the variable magnification assembly of an industrial lens according to claim 1, wherein the variable magnification assembly satisfies the following conditional expression:

0.05＜N（p-avg）- N（n-avg）＜0.25

wherein N (p-avg) is the average value of the refractive index of all positive lenses in the variable magnification assembly with respect to the d-line; n (N-avg) is the average of all negative lenses in the variable power assembly with respect to the d-line refractive index.

3. The variable magnification assembly of an industrial lens according to claim 1, wherein the variable magnification assembly satisfies the following conditional expression:

0.04＜∑（air）/ f(HL)＜0.08

wherein Σ (air) is the sum of all air intervals on the optical axis included in the magnification varying block.

4. The variable magnification assembly of an industrial lens according to claim 1, wherein the variable magnification assembly satisfies the following conditional expression:

0.3＜f（H4）/ f（H34）＜0.5

0.5＜f（H6）/ f（H56）＜0.6

wherein f (H4) is the positive lens focal length of the 1 st double cemented lens group; f (H6) is the negative lens focal length of the 2 nd doublet lens group.

5. The variable magnification assembly of an industrial lens according to claim 1, wherein the variable magnification assembly satisfies the following conditional expression:

4.5＜[（1/f（H34）-1/f（H56）]*f（HL）＜5.5 。

6. the variable magnification assembly of an industrial lens according to claim 1, wherein the variable magnification assembly satisfies the following conditional expression:

1.8＜[（1/f（H34）+1/f（H56）]*f（HL）＜2.1。

7. the variable magnification assembly of an industrial lens according to claim 1, wherein the variable magnification assembly satisfies the following conditional expression:

0.3＜-f（H34）/ f（H56）＜0.6。

8. the zoom assembly of claim 1, wherein the positive lens H1 comprises a first curved surface and a second curved surface from an object side to an image side; the negative lens H2 comprises a third curved surface and a fourth curved surface; the 1 st double-cemented lens group comprises a fifth curved surface, a sixth curved surface and a seventh curved surface; the 2 nd double-cemented lens group comprises an eighth curved surface, a ninth curved surface and a tenth curved surface;

the curvature radiuses of the first curved surface and the second curved surface are 83.427mm and 139.982mm respectively;

the curvature radiuses of the third curved surface and the fourth curved surface are 801.649mm and 76.338mm respectively;

the curvature radiuses of the fifth curved surface, the sixth curved surface and the seventh curved surface are 224.175mm, 59.447mm and-105.158 mm respectively;

the curvature radiuses of the eighth curved surface, the ninth curved surface and the tenth curved surface are respectively-90.923 mm, -59.631mm and-379.509 mm.

9. The variable magnification assembly of an industrial lens according to claim 1, wherein the center thickness of the positive lens H1 is 8.98mm; the center thickness of the negative lens H2 is 3mm; the center thickness of the 1 st double-cemented lens group H34 is 33.94mm; the center thickness of the 2 nd double cemented lens group H56 was 24.05mm.