CN204855922U - Wide -angle camera lens - Google Patents

Abstract

The utility model discloses a wide-angle lens, which comprises a front mirror group, a diaphragm and a rear mirror group. The front mirror group sequentially includes a first lens, a second lens, a third lens and a fourth lens, with the object side as the front, The first lens is a front-convex and back-concave aspheric glass lens, the second lens is a meniscus glass aspheric lens with front and back concave, the third lens is a front-convex and back-convex glass lens, and the first The four lenses are front convex and rear flat glass lenses; the rear mirror group includes the fifth lens, the sixth lens, the seventh lens and the eighth lens in sequence, with the object side as the front, and the fifth lens is front flat and rear convex glass lens, the sixth lens is a front concave and back convex glass lens, the fifth lens and the sixth lens are cemented together, the seventh lens is a front convex and back concave glass lens, and the eighth lens is front convex and back convex And the aspherical glass lens; the utility model is high temperature resistant, high humidity resistant, scratch resistant, has a super large viewing angle, no optical distortion, and low chromatic aberration.

Description

a wide-angle lens

technical field

The utility model relates to a monitoring lens, in particular to a wide-angle lens.

Background technique

With the continuous improvement of people's attention to social security, monitoring systems are widely used in various fields. At present, security monitoring lenses generally have a small field of view, which is difficult to meet the requirements of large-scale monitoring; on the other hand, the lens is affected by the use environment, for example, the performance of the lens is reduced in a high-temperature and high-humidity environment, and the service life will also be affected.

Utility model content

The technical problem to be solved by the utility model is to provide a wide-angle lens, which is high temperature resistant, high humidity resistant, scratch resistant, has a super large viewing angle, no optical distortion, and low chromatic aberration.

In order to achieve the above object, the technical solution of the utility model is: a wide-angle lens, including a front mirror group, a diaphragm and a rear mirror group, and the front mirror group includes a first lens, a second lens, and a second lens in sequence along the optical axis from the object side The lens, the third lens and the fourth lens, with the object side as the front, the first lens is an aspheric glass lens with a front convex and a concave back, and the second lens is a meniscus glass aspheric lens with a concave front and a back concave, The third lens is a front convex back convex glass lens, and the fourth lens is a front convex back flat glass lens;

The optical axis direction of the rear mirror group includes the fifth lens, the sixth lens, the seventh lens and the eighth lens in order from the object side, with the object side as the front, and the fifth lens is a front flat back convex glass lens, so The sixth lens is a front concave and back convex glass lens, the fifth lens and the sixth lens are cemented together, the seventh lens is a front convex and back concave glass lens, and the eighth lens is a front convex back convex and an aspheric surface glass lens.

Preferably, the refractive index of the third lens is N ₃ , and N ₃ satisfies the following condition: 1.90<N ₃ <1.92.

Preferably, the dispersion coefficient of the fifth lens is V _d , and V _d satisfies the following condition: 80<V _d <81.

Preferably, the focal length of the front lens group is f _L1 , and the focal length of the rear lens group is f _L2 , and f _L1 and f _L2 satisfy the following condition: 1.0<|f _L1 /f _L2 |<1.2.

Preferably, the focal length of the first lens is f _a , the focal length of the eighth lens is f _b , and f _a and f _b satisfy the following condition: 0.7<|f _a /f _b |<0.8.

Preferably, the focal length of the first lens is f _a , and f _a satisfies the following condition: |f _a |>7.5 mm; the focal length of the eighth lens is f _b , and f _b satisfies the following condition: |f _b |>10 mm.

Preferably, the refractive index of the first lens is N ₁ , and N ₁ satisfies the following condition: 1.65<N ₁ <1.80; the refractive index of the eighth lens is N ₈ , and satisfies the following condition: 1.65<N ₈ <1.80.

Preferably, the distance between the first lens and the second lens is 3.5 mm to 4.5 mm.

Preferably, the distance between the seventh lens and the eighth lens is 0.1 mm to 1.1 mm.

The front mirror group of the utility model includes four lenses, and the rear mirror group includes four lenses; the first lens adopts an aspherical glass lens with a front convex and a back concave to ensure a large viewing angle of the lens; the second lens is a front lens The meniscus glass aspheric lens with concave back concave eliminates astigmatism, field curvature and optical distortion; cooperates with the fifth lens and the sixth lens to glue each other to eliminate chromatic aberration; cooperates with the eighth lens to be a biconvex aspheric glass lens, further Eliminate astigmatism, aberration and F-Theta distortion; further, the structural strength of the lens is improved after all the lenses are made of glass lenses. The lens is resistant to high temperature, high humidity and scratches. The utility model also has the characteristics of high resolution.

Description of drawings

Fig. 1 is the structural representation of the utility model.

Detailed ways

The utility model will be described in further detail below in conjunction with the accompanying drawings and specific embodiments.

As shown in Fig. 1, a kind of wide-angle lens comprises front mirror group 10, diaphragm 20 and rear mirror group 30 from object side along optical axis direction, and described front mirror group 10 comprises first along optical axis direction from object side successively. Lens 1, second lens 2, third lens 3 and fourth lens 4, with the object side as the front, the first lens 1 is an aspheric glass lens with front convex and back concave, and the second lens 2 is front concave Rear concave meniscus glass aspheric lens, the third lens 3 is a front convex back convex glass lens, the fourth lens 4 is a front convex back flat glass lens; the first lens 1 and the second lens 2 The distance between them is 3.5mm to 4.5mm; the refractive index of the first lens 1 is N ₁ , preferably N ₁ satisfies the following conditions: 1.65<N ₁ <1.80; with the object side as the front, the first lens 1 is far away from the object The square refraction surface is the second surface of the first lens 1, the angle of the second surface is between 53° and 56°, and the viewing angle of the lens can reach 112°; the refractive index of the third lens 3 is N ₃ , preferably N ₃ satisfies the following condition: 1.90<N ₃ <1.92, and the third lens 3 is made of a material with a high refractive index to improve resolution.

The optical axis direction of the rear mirror group 30 includes the fifth lens 5, the sixth lens 6, the seventh lens 7 and the eighth lens 8 from the object side, with the object side as the front, and the fifth lens 5 is the front plane. Back convex glass lens, the sixth lens 6 is a front concave back convex glass lens; for achromatism, the dispersion coefficient of the fifth lens 5 is V _d , preferably V _d satisfies the following conditions: 80<V _d <81, The fifth lens 5 and the sixth lens 6 are cemented together; the seventh lens 7 is a front-convex and rear-concave glass lens, and the eighth lens 8 is a front-convex and back-convex aspheric glass lens to eliminate astigmatism and image difference and F-Theta distortion; the distance between the seventh lens 7 and the eighth lens 8 is 0.1 mm to 1.1 mm; the refractive index of the eighth lens 8 is N ₈ , preferably 1.65<N ₈ <1.80.

Preferably, the focal length of the front mirror group 10 is f _L1 , and the focal length of the rear mirror group 30 is f _L2 , f _L1 and f _L2 satisfy the following condition: 1.0<|f _L1 /f _L2 |<1.2.

Preferably, the focal length of the first lens 1 is f _a , the focal length of the eighth lens 8 is f _b , and f _a and f _b satisfy the following conditions: 0.7<|f _a /f _b |<0.8.

Preferably, the focal length of the first lens 1 is fa, and fa satisfies the following condition: |f _a |>7.5 mm; the focal length of the eighth lens 8 is f _b , and _{f b satisfies} the following condition: | _{f b |} >10 mm.

This embodiment can achieve the following parameters: the total length of the lens is less than 26mm, which meets the market's increasingly shorter requirements for consumer lenses; the FOV is greater than 112° when the image plane is 1/2.3", and the optical distortion is less than 5%, which meets the market requirements Requirements for wide-angle distortion-free lenses; in order to meet the high temperature resistance, high humidity resistance, and scratch resistance of security and consumer lenses, the first lens is made of lanthanide glass; the resolution of security lenses on the market is generally in the million Level, the resolution of this lens reaches the level of 8M; in order to reduce costs, the lens uses 8 lenses, all of which are glass lenses, to meet the needs of security and consumer lenses for stable use in harsh environments.

The above is only a preferred embodiment of the utility model, and equivalent changes made by those skilled in the art according to the claims all fall within the protection scope of the present case.

Claims (9)

1. a wide-angle lens, comprise front lens group, diaphragm and rear mirror group, it is characterized in that: described front lens group comprises the first lens, the second lens, the 3rd lens and the 4th lens successively along optical axis direction from object space, take object space as front, described first lens are lordosis recurve aspherical glass lens, described second lens are the falcate glass aspheric lenses of front recessed recurve, and described 3rd lens are convex glass lens after lordosis, and described 4th lens are flat glass lens after lordosis;

Described rear mirror group comprises the 5th lens, the 6th lens, the 7th lens and the 8th lens successively along optical axis direction from object space, take object space as front, described 5th lens are front flat rear convex glass lens, described 6th lens are front recessed rear convex glass lens, described 5th lens and the 6th lens glue together mutually, described 7th lens are lordosis recurve glass lens, and described 8th lens are convex after lordosis and aspherical glass lens.

2. a kind of wide-angle lens according to claim 1, is characterized in that: the refractive index of described 3rd lens is N ₃, N ₃meet the following conditions: 1.90 < N ₃< 1.92.

3. a kind of wide-angle lens according to claim 1, is characterized in that: the abbe number of described 5th lens is V _d, V _dmeet the following conditions: 80 < V _d< 81.

4. a kind of wide-angle lens according to claim 1, is characterized in that: described front lens group focal length is f _l1, described rear mirror group focal length is f _l2, f _l1and f _l2meet the following conditions: 1.0 < | f _l1/ f _l2| < 1.2.

5. a kind of wide-angle lens according to claim 1, is characterized in that: described first focal length of lens is f _a, described 8th focal length of lens is f _b, f _awith f _bmeet the following conditions: 0.7 < | f _a/ f _b| < 0.8.

6. a kind of wide-angle lens according to claim 1, is characterized in that: described first focal length of lens is f _a, f _ameet the following conditions: | f _a| > 7.5mm; Described 8th focal length of lens is f _b, f _bmeet the following conditions: | f _b| > 10mm.

7. a kind of wide-angle lens according to claim 1, is characterized in that: the refractive index of described first lens is N ₁, N ₁meet the following conditions: 1.65 < N ₁< 1.80; The refractive index of described 8th lens is N ₈, meet the following conditions: 1.65 < N ₈< 1.80.

8. a kind of wide-angle lens according to claim 1, is characterized in that: the spacing of described first lens and the second lens is 3.5mm to 4.5mm.

9., according to the arbitrary described a kind of wide-angle lens of claim 1 to 8, it is characterized in that: the spacing between described 7th lens and the 8th lens is 0.1mm to 1.1mm.