CN107247323B

CN107247323B - Two-group zoom lens, method of using the same, and imaging apparatus including the same

Info

Publication number: CN107247323B
Application number: CN201710641267.2A
Authority: CN
Inventors: 杨敏; 林佳敏; 王火红; 林正
Original assignee: Fujian Hao Lan Photoelectric Co Ltd
Current assignee: Fujian Hao Lan Photoelectric Co Ltd
Priority date: 2017-07-31
Filing date: 2017-07-31
Publication date: 2020-01-31
Anticipated expiration: 2037-07-31
Also published as: GB2573928A; WO2019024798A1; GB2573928B; GB201911608D0; DE112018000720B4; DE112018000720T5; CN107247323A

Abstract

The invention relates to two-group zoom lens which is characterized by comprising a lens group with negative focal power, an aperture stop and a second lens group with positive focal power, wherein the lens group with negative focal power, the aperture stop and the second lens group with positive focal power are coaxially arranged in sequence from an object side to an image side, the lens group comprises a crescent lens with negative focal power, a double-concave lens with negative focal power and a double-convex lens with positive focal power, the crescent lens with negative focal power, the double-concave lens with negative focal power and the double-convex lens with positive focal power are coaxially arranged in sequence from the object side to the image side, and the second lens group comprises a second double-convex lens with positive focal power, a second February lens with negative focal power, a third double-concave lens with positive focal power, a third double-convex lens with negative focal power, a fourth double-convex lens with negative focal power and a fourth lens with positive focal power.

Description

Two-group zoom lens, method of using the same, and imaging apparatus including the same

Technical Field

The invention relates to the field of optical imaging, in particular to two-group zoom lenses, a using method thereof and imaging equipment comprising the zoom lenses.

Background

The development trend of machine vision lens is that the fewer the lenses, the lower the cost, the compact structure, the small size and the high image quality. When no aspheric lens is used, the imaging quality of the lens with a small number of lenses is not high, and the requirement of light and small size is difficult to achieve by a high lens group. So far, the zoom lens in the field mostly adopts four components and two groups or three groups to realize zooming, and has complex structure and high cost.

Disclosure of Invention

The invention aims to solve the technical problem of realizing double-group zoom lenses with simple structures and low cost.

In order to solve the technical problems, the invention adopts the technical scheme that:

A two-group zoom lens comprises a lens group with negative focal power, an aperture stop and a second lens group with positive focal power, which are coaxially arranged in sequence from an object side to an image side, wherein the lens group comprises a crescent lens with negative focal power, a double-concave lens with negative focal power and a double-convex lens with positive focal power, which are coaxially arranged in sequence from the object side to the image side, and the second lens group comprises a second double-convex lens with positive focal power, a second crescent lens with positive focal power, a second double-concave lens with negative focal power, a third double-convex lens with positive focal power, a third crescent lens with negative focal power, a fourth crescent lens with negative focal power and a fourth double-convex lens with positive focal power, which are coaxially arranged in sequence from the object side to the image side.

In an alternative example, the third double convex lens and the third meniscus lens are joined to each other to form an th cemented lens having a positive optical power as a whole, and the fourth meniscus lens and the fourth double convex lens are joined to each other to form a second cemented lens having a positive optical power as a whole.

In an alternative example, the zoom lens satisfies the condition of 1.2< | fG1|/fG2<2.0, where "fG 1" denotes a focal length of the lens group and "fG 2" denotes a focal length of the second lens group.

In an alternative example, the zoom lens satisfies the following condition: 1.8< | fG1|/ft <2.6, 0.9< fG2/ft <1.8, where "ft" denotes the focal length of the zoom lens at the telephoto position.

In an alternative example, the zoom lens satisfies the following condition:

2.4< fs/fG2<3.2, wherein "fs" represents an effective focal length of the L21 to L23 lenses of the second lens group G2.

In an alternative example, an aperture stop of the zoom lens is disposed between the th lens group and the second lens group and is fixed.

The present invention also relates to methods of using the zoom lens as described above, which performs zooming by moving the lens group toward the object side and/or the second lens group toward the image side.

The invention also relates to imaging apparatuses comprising a zoom lens according to the above.

The invention has the beneficial effects that: this scheme adopts two formulas to realize zooming, under the prerequisite of guaranteeing that the imaging quality is good, makes numerous and diverse structure simplify greatly, and the lens is all spherical glass, and the imaging quality is good, and is small to compact structure.

Drawings

FIG. 1 is a schematic diagram of a dual zoom lens configuration according to an embodiment of the present invention;

FIG. 2 is a schematic structural diagram of the two-group zoom lens system at angle in the embodiment of the present invention;

FIG. 3 is a schematic structural diagram of the two-group zoom lens in an intermediate state according to the embodiment of the present invention;

FIG. 4 is a schematic structural diagram of the two-group zoom lens in the telephoto state according to the embodiment of the present invention;

FIG. 5 is a spherical aberration curve diagram of the two-group zoom lens in the angle state in the embodiment of the present invention;

FIG. 6 is a spherical aberration curve diagram of the two-group zoom lens in the intermediate state in the embodiment of the present invention;

FIG. 7 is a spherical aberration diagram of the two-group zoom lens in the telephoto state according to the embodiment of the present invention ;

FIG. 8 is an MTF chart of the angular state for the two-group zoom lens of the embodiment of the present invention.

FIG. 9 is an MTF graph of the two-group zoom lens in the intermediate state according to the embodiment of the present invention.

FIG. 10 is an MTF chart of the two-group zoom lens in the telephoto state according to the embodiment of the present invention .

Description of reference numerals:

g1, a lens group, G2, a second lens group, L11, a crescent lens, L12, a biconcave lens, L13, a biconvex lens, L21, a second biconvex lens, L22, a second crescent lens, L23, a second biconcave lens, L24, a third biconvex lens, L25, a third crescent lens;

l26, fourth crescent lens; l27, fourth lenticular lens; s, an aperture diaphragm; H. a flat glass.

Detailed Description

In order to explain technical contents, achieved objects, and effects of the present invention in detail, the following description is made with reference to the accompanying drawings in combination with the embodiments.

As shown in fig. 1, the zoom lens according to the embodiment of the present invention includes an th lens group G1 having negative optical power, and a second lens group G2. having positive optical power, which are coaxially disposed in order from left to right along an axial ray from an object side to an image side, and in use, the second lens group G2 is moved toward the image side by moving the th lens group G1 toward the object side, so as to perform zooming on the zoom lens, fig. 2 is a schematic structural view of the two-group zoom lens according to the embodiment of the present invention at an angle of , fig. 3 is a schematic structural view of the two-group zoom lens according to the embodiment of the present invention in an intermediate state, and fig. 4 is a schematic structural view of the two-group zoom lens according to the embodiment of the.

The two-group zoom lens provided by the embodiment of the invention adopts two groups of dynamic zooming transmission type structures, as shown in FIG. 1, a th lens group G1 with negative focal power, an aperture stop S, a second lens group G2. with positive focal power and a th lens group G1 with negative focal power which are coaxially arranged in sequence from an object side to an image side comprise a th crescent lens L11 with negative focal power, a th biconcave lens L12 with negative focal power and a th biconvex lens L13 with positive focal power which are coaxially arranged in sequence from the object side to the image side, and the second lens group G2 with positive focal power comprises a second biconvex lens L21 with positive focal power, a second crescent lens L22 with positive focal power, a second biconcave lens L2 with negative focal power, a third biconvex lens L8 with positive focal power, a third biconvex lens L24 with negative focal power, a third biconvex lens L59692 with positive focal power, a fourth biconvex lens L638 and a fourth biconvex lens L24 with positive focal power which are coaxially arranged in sequence from the object side to the image side.

Further , the third double convex lens L24 and the third meniscus lens L25 are joined to each other to form a cemented lens having a positive optical power as a whole, and the fourth meniscus lens L26 and the fourth double convex lens L27 are joined to each other to form a cemented lens having a positive optical power as a whole.

Further , the zoom lens satisfies the condition that 1.2< | fG1|/fG2<2.0, wherein "fG 1" denotes a focal length of the th lens group, and "fG 2" denotes a focal length of the second lens group.

Further , the zoom lens satisfies the conditions of 1.8< | fG1|/ft <2.6, 0.9< fG2/ft <1.8, where "ft" denotes the focal length of the zoom lens at the telephoto position.

Further , the focus lens is changed to satisfy the condition 2.4< fs/fG2<3.2, where "fs" represents the effective focal length of the L21 to L23 lenses of the second lens group G2.

Further , an aperture stop of the zoom lens is disposed between the third lens group G1 and the second lens group G2 and fixed.

This scheme adopts two formulas to realize zooming, under the prerequisite of guaranteeing that the imaging quality is good, makes numerous and diverse structure simplify greatly, and the lens is all spherical glass, and the imaging quality is good, and is small to compact structure.

Table lists the detailed parameters of the specific example of the zoom lens according to the present invention, which includes the curvature radius, thickness, refractive index, Abbe number, etc. of each lens, wherein the surface numbers of the lenses are arranged in order from the object side to the image side, for example, "S1" represents the surface of lens L11 toward the object side, "S2" represents the surface of lens L11 toward the image side, "S" represents the stop surface, and the object side and image side surfaces of the flat glass H are "S20" and "S21", respectively, etc.

TABLE

Wherein the thickness or pitch values are designated as "D1", "D2", "D3", and represent the distance between the two surfaces at the corner end (wide), middle end (middle) and telescoping end (tele) of , and the distance is shown in Table two.

Watch two

The above examples of the present invention are shown in table three in for the angular end, the middle end, the focal length f of the telephoto end, the f-number FNO, the half field angle ω (halfangulev), and the image height Y.

Watch III

Parameter(s)	corner end	Intermediate terminal	Telescope end
				f(mm)	8.0	10	12.0
FNO	2.48	2.57	2.69
				ω(°)	20.727	19.295	16.355
Y(mm)	7.01	7.02	7.02

The wavelength data for the above example of the present invention is shown in table four.

Watch four

Parameter(s)	Wavelength (nm)
		1	436
2	486
		3	546
4	588
		5	656

Of course, the respective transparencies of the zoom lens according to the embodiment of the present invention may also have parameters other than those listed in the above table.

Fig. 5 to 7 show graphs of spherical aberration (longitudinal spherical aberration) at angular end, intermediate end and telephoto end of a zoom lens according to an embodiment of the present invention, respectively, where A, B, C, D, E shows test curves for wavelengths 436, 486, 546, 588 or 656nm, respectively.

The spherical aberration of the beams with wavelengths of 436nm and 656nm at angular end, middle end and telephoto end are controlled within 0.004 mm.

In addition, experiments show that the zoom lens according to the embodiment of the present invention has the tangential field curvature value and the sagittal field curvature value of a light beam with a wavelength of 546nm both controlled within a range of (-0.027mm, 0.003mm) and the distortion rate both controlled within a range of (-4.1%, 0%) at an angular end of degrees, the tangential field curvature value and the sagittal field curvature value both controlled within a range of (-0.025mm, 0.008mm) and the distortion rate both controlled within a range of (-2.5%, 0%) at a middle end, and the tangential field curvature value and the sagittal field curvature value both controlled within a range of (-0.020mm, 0.022mm and the distortion rate both controlled within a range of (-1.6%, 0%) at a far end.

In addition, fig. 8 to 10 show Modulation Transfer Function (MTF) test curves of the zoom lens of the embodiment of the present invention at angular end, middle end and telephoto end, respectively, it can be seen that the MTF of the zoom lens of the embodiment of the present invention is greater than 0.3 at 215lp/mm in all of angular end, middle end and telephoto end.

From the above, the zoom lens according to the embodiment of the present invention has the advantages that the spherical aberration, curvature of field and distortion at the angle end, the middle end and the telephoto end of can be well corrected, and the transfer function has good flatness and sharpness.

Although the present invention has been described with reference to a preferred embodiment, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

The two-group zoom lens is characterized by consisting of a lens group with negative focal power, an aperture stop and a second lens group with positive focal power which are coaxially arranged in sequence from an object side to an image side, wherein the lens group consists of a crescent lens with negative focal power, a biconcave lens with negative focal power and a biconvex lens with positive focal power which are coaxially arranged in sequence from the object side to the image side;

the third double convex lens and the third meniscus lens are joined to each other to form an th cemented lens having a positive power as a whole, and the fourth meniscus lens and the fourth double convex lens are joined to each other to form a second cemented lens having a positive power as a whole;

wherein the zoom lens satisfies the condition of 1.2< | fG1|/fG2<2.0, wherein "fG 1" represents the focal length of the third lens group , and "fG 2" represents the focal length of the second lens group;

wherein, the zoom lens satisfies the following conditions: 1.8< | fG1|/ft <2.6, 0.9< fG2/ft <1.8, where "ft" denotes the focal length of the zoom lens at the telephoto position;

wherein, the zoom lens satisfies the following conditions: 2.4< fs/fG2<3.2, wherein "fs" represents the effective focal length of the second biconvex (L21) to second biconcave (L23) lens of the second lens group (G2).
2. The two-group zoom lens according to claim 1, wherein an aperture stop of the zoom lens is disposed between the th lens group and the second lens group and is fixed.
3, a method of using the two-group zoom lens system as claimed in any of claims 1-2, wherein zooming is performed by moving the first lens group toward the object side and/or moving the second lens group toward the image side.
An imaging apparatus of , comprising the two-group zoom lens according to any of claims 1-2, .