CN112230402B - Double-view-field fisheye lens - Google Patents

Abstract

The invention provides a double-field fish-eye lens which can realize a short-focus 160-degree large field of view and a long-focus 80-degree field of view under a large relative aperture with the F/no less than 3, and can realize over 91% relative illumination at 160 degrees, so that a target can be found in the large field of view, and the target can be identified in the small field of view. The double-view-field fisheye lens has high resolution and a simple and compact structure, has a function of quickly converting double view fields, and solves the problems that the conventional domestic fisheye optical system has low resolution, large volume and heavy weight and does not have the function of quickly converting double view fields.

Description

Double-view-field fisheye lens

Technical Field

The invention belongs to the technical field of fisheye lenses, and particularly relates to a double-view-field fisheye lens.

Background

The fisheye lens is an ultra-wide angle lens having a focal length of 16mm or less. The front lens of the lens is large in diameter and is in a parabolic shape, protrudes towards the front of the lens, is quite similar to the fish eye, and is commonly called as a fish eye lens. At present, the fisheye lens is widely applied to the fields of security monitoring, vehicle-mounted monitoring and the like, so the requirements on the fisheye lens are higher and higher, but the existing common fisheye lens has a small image plane and a low utilization rate of a sensor. Therefore, the development of a miniaturized fisheye optical system with double fields of view and multiple performances is very important. At present, the domestic fish eye optical system has low resolution, large volume and heavy weight and does not have the function of quickly converting double fields of view.

Disclosure of Invention

In view of this, the invention provides a double-field fisheye lens, which can realize a short-focus 160-degree large field of view and a long-focus 80-degree field of view under a large relative aperture with an F/no smaller than 3, and can realize more than 91% relative illumination at 160 degrees, so that a target can be found in the large field of view, and the target can be identified in the small field of view.

In order to achieve the purpose, the technical scheme of the invention is as follows:

the invention discloses a double-field-of-view fish-eye lens which comprises a first lens, a second lens group, a third lens, a fourth lens group, a fifth lens, a sixth lens, a seventh lens, an eighth lens, a ninth lens, a tenth lens, an eleventh lens and a twelfth lens which are coaxial and are sequentially arranged from an object space to an image space;

the second lens group and the fourth lens group are double-cemented lenses;

the first lens, the second lens group, the third lens, the fourth lens group and the fifth lens are fixed groups, the two fields of view are kept static when switched, and the fixed group focal length f1 is negative;

the sixth lens, the seventh lens, the eighth lens, the ninth lens, the tenth lens, the eleventh lens and the twelfth lens are variable power groups, and the focal length f2 of the variable power groups is positive; the zoom group realizes two fields of view by axially moving to two positions;

the ratio of the fixed group focal length F1, the variable magnification group focal length F2 and the double-view-field fisheye lens integral short focus F1 is respectively as follows: -5< F1/F1< -0.5, 0.5< F2/F1< 5; the focal length ratio of the whole short-focus F1 and long-focus F2 of the double-field fisheye lens is 0.2< F1/F2< 0.8.

Wherein parameters of the first lens, the second lens group, the third lens, the fourth lens group, the fifth lens, the sixth lens, the seventh lens, the eighth lens, the ninth lens, the tenth lens, the eleventh lens and the twelfth lens satisfy the following relations:

1.72<nd1<2.05，27<vd1<45，1.55<nd2₁<1.80，24<vd2₁<34，1.70<nd2₂<1.90，30<vd2₂<50，1.55<nd3<1.80，20<vd3<30，1.65<nd4₁<1.80，45<vd4₁<60，1.70<nd4₂<1.80，20<vd4₂<30，1.50<nd5<1.66，55<vd5<65，1.75<nd6<1.85，50<vd6<55，1.80<nd7<1.85，22<vd7<30，1.80<nd8<1.85，22<vd8<30，1.70<nd9<1.85，20<vd9<30,1.55<nd10<1.65，55<vd10<65，1.80<nd11<1.85，22<vd11<30，1.50<nd12<1.60，60<vd12<70；

wherein nd1-nd12 sequentially represent refractive indexes of the first lens to the twelfth lens in a d line, vd1-vd12 sequentially represent abbe numbers of the first lens to the twelfth lens in the d line, and the corresponding parameter number of the second lens group is nd2₁And nd2₂The fourth lens group corresponding parameter number nd4₁And nd4₂(ii) a nd denotes the d-light refractive index of the lens material, and vd denotes the d-light abbe constant of the lens material.

The focal lengths of the first lens, the second lens group, the fourth lens group, the fifth lens, the sixth lens, the ninth lens and the eleventh lens are all negative; the focal powers of the third lens, the seventh lens, the eighth lens and the twelfth lens are all positive.

And a diaphragm is arranged between the eighth lens and the ninth lens.

Has the advantages that:

the double-view-field fisheye lens has high resolution and a simple and compact structure, has a function of quickly converting double view fields, and solves the problems that the conventional domestic fisheye optical system has low resolution, large volume and heavy weight and does not have the function of quickly converting double view fields.

Drawings

Fig. 1 is a schematic short-focus diagram of a dual-field fisheye lens device according to the invention.

Fig. 2 is a schematic telephoto view of the dual-field fisheye lens device of the invention.

Fig. 3 is a short-focus MTF curve of the dual-field fisheye lens device of the invention.

Fig. 4 is a long-focus MTF graph of the dual-field fisheye lens device of the invention.

The lens comprises a lens body, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, a ninth lens, a tenth lens, an eleventh lens and a twelfth lens, wherein the lens body comprises 1-the first lens, 2-the second lens, 3-the third lens, 4-the fourth lens, 5-the fifth lens, 6-the sixth lens, 7-the seventh lens, 8-the eighth lens, 9-the ninth lens, 10-the tenth lens, 11-the eleventh lens and 12-the twelfth lens.

Detailed Description

The invention is described in detail below by way of example with reference to the accompanying drawings.

The double-field-of-view fisheye lens comprises a first lens 1, a second lens group 2, a third lens 3, a fourth lens group 4, a fifth lens 5, a sixth lens 6, a seventh lens 7, an eighth lens 8, a ninth lens 9, a tenth lens 10, an eleventh lens 11 and a twelfth lens 12 which are coaxial and sequentially arranged from an object side to an image side;

wherein, the second lens group 2 and the fourth lens group 4 are double cemented lenses;

the first lens 1, the second lens group 2, the third lens 3, the fourth lens group 4 and the fifth lens 5 are fixed groups, when the two fields of view are switched, the fixed groups are kept still, and the fixed group focal length f1 is negative;

the sixth lens 6, the seventh lens 7, the eighth lens 8, the ninth lens 9, the tenth lens 10, the eleventh lens 1, and the twelfth lens 12 are a variable power group, and a focal length f2 of the variable power group is positive; the zoom group realizes two fields of view by axially moving to two positions;

the ratio of the fixed group focal length F1, the variable magnification group focal length F2 and the double-view-field fisheye lens integral short focus F1 is respectively as follows: -5< F1/F1< -0.5; 0.5< F2/F1< 5; the focal length ratio of the whole short-focus F1 and long-focus F2 of the double-field fisheye lens is 0.2< F1/F2< 0.8.

In order to further achromatize and improve the imaging quality, the parameters of each lens satisfy the following relations:

1.72<nd1<2.05，27<vd1<45，1.55<nd2₁<1.80，24<vd2₁<34，1.70<nd2₂<1.90，30<vd2₂<50，1.55<nd3<1.80，20<vd3<30，1.65<nd4₁<1.80，45<vd4₁<60，1.70<nd4₂<1.80，20<vd4₂<30，1.50<nd5<1.66，55<vd5<65，1.75<nd6<1.85，50<vd6<55，1.80<nd7<1.85，22<vd7<30，1.80<nd8<1.85，22<vd8<30，1.70<nd9<1.85，20<vd9<30,1.55<nd10<1.65，55<vd10<65，1.80<nd11<1.85，22<vd11<30，1.50<nd12<1.60，60<vd12<70；

wherein nd1-nd12 sequentially represent refractive indexes of the first lens to the twelfth lens in a d line, vd1-vd12 sequentially represent abbe numbers of the first lens to the twelfth lens in the d line, and the corresponding parameter number of the second lens group is nd2₁And nd2₂The fourth lens group corresponding parameter number nd4₁And nd4₂(ii) a nd denotes the d-light refractive index of the lens material, and vd denotes the d-light abbe constant of the lens material.

In order to further eliminate aberration, focal lengths of the first lens, the second lens group, the fourth lens group, the fifth lens, the sixth lens, the ninth lens and the eleventh lens are all negative; the focal powers of the third lens, the seventh lens, the eighth lens and the twelfth lens are all positive.

In order to further improve the imaging quality, a diaphragm is arranged between the eighth lens 8 and the ninth lens 9. The table 1 is adopted for simulation, and the simulation shows that the fisheye lens is practical and effective.

TABLE 1

Wherein L1 and L2 are intervals between the fifth lens 5 and the sixth lens 6, L1 is an interval in the case of a long focus, and L2 is an interval in the case of a short focus; h1 and H2 are distances between the twelfth lens element 12 and the image plane, H1 is a distance in the telephoto range, and H2 is a distance in the short focus range.

In summary, the above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (3)

1. A double-field-of-view fisheye lens is characterized by comprising a first lens, a second lens group, a third lens, a fourth lens group, a fifth lens, a sixth lens, a seventh lens, an eighth lens, a ninth lens, a tenth lens, an eleventh lens and a twelfth lens which are coaxial and sequentially arranged from an object space to an image space;

the second lens group and the fourth lens group are double-cemented lenses;

the first lens, the second lens group, the third lens, the fourth lens group and the fifth lens are fixed groups, the two fields of view are kept static when switched, and the fixed group focal length f1 is negative;

the sixth lens, the seventh lens, the eighth lens, the ninth lens, the tenth lens, the eleventh lens and the twelfth lens are variable power groups, and the focal length f2 of the variable power groups is positive; the zoom group realizes two fields of view by axially moving to two positions;

the ratio of the fixed group focal length F1, the variable magnification group focal length F2 and the double-view-field fisheye lens integral short focus F1 is respectively as follows: -5< F1/F1< -0.5, 0.5< F2/F1< 5; the focal length ratio of the whole short focus F1 and the whole long focus F2 of the double-field fisheye lens is 0.2< F1/F2< 0.8;

focal lengths of the first lens, the second lens group, the fourth lens group, the fifth lens, the sixth lens, the ninth lens and the eleventh lens are all negative; the focal powers of the third lens, the seventh lens, the eighth lens, the tenth lens and the twelfth lens are all positive.

2. The dual field of view fish-eye lens of claim 1, wherein the parameters of the first lens, the second lens group, the third lens, the fourth lens group, the fifth lens, the sixth lens, the seventh lens, the eighth lens, the ninth lens, the tenth lens, the eleventh lens, and the twelfth lens satisfy the following relationships:

1.72<nd1<2.05，27<vd1<45，1.55<nd2₁<1.80，24<vd2₁<34，1.70<nd2₂<1.90，30<vd2₂<50，1.55<nd3<1.80，20<vd3<30，1.65<nd4₁<1.80，45<vd4₁<60，1.70<nd4₂<1.80，20<vd4₂<30，1.50<nd5<1.66，55<vd5<65，1.75<nd6<1.85，50<vd6<55，1.80<nd7<1.85，22<vd7<30，1.80<nd8<1.85，22<vd8<30，1.70<nd9<1.85，20<vd9<30,1.55<nd10<1.65，55<vd10<65，1.80<nd11<1.85，22<vd11<30，1.50<nd12<1.60，60<vd12<70；

wherein nd1-nd12 sequentially represent refractive indexes of the first lens to the twelfth lens in a d line, vd1-vd12 sequentially represent abbe numbers of the first lens to the twelfth lens in the d line, and the corresponding parameter number of the second lens group is nd2₁And nd2₂The fourth lens group corresponding parameter number nd4₁And nd4₂(ii) a nd denotes the d-light refractive index of the lens material, and vd denotes the d-light abbe constant of the lens material.

3. The dual field of view fisheye lens of claim 1, characterised in that a stop is arranged between the eighth lens and the ninth lens.

Images