CN210376831U - Large-aperture high-low temperature confocal imaging system - Google Patents

Abstract

The utility model discloses a confocal imaging system of big light ring height low temperature, this system includes the first glass spherical lens L1 of the convex-concave negative focal power that sets gradually along light incident direction, the second glass spherical lens L2 of concave-convex negative focal power, the third plastic aspheric lens L3 of concave-convex positive focal power, the fourth glass spherical lens L4 of biconvex positive focal power, the fifth glass spherical lens L5 of biconvex positive focal power, the sixth plastic aspheric lens L6 of convex-concave negative focal power, the sixth plastic aspheric lens L7 of biconvex positive focal power; the lens adopts a 4G3P structure, so that the cost is reduced. And the lens structure is compact by reasonably distributing focal power, so that the tolerance sensitivity is greatly reduced.

Description

Large-aperture high-low temperature confocal imaging system

Technical Field

The utility model discloses mainly to the security protection control and guarantee at-40 ℃ -85 ℃ big light ring imaging system not out of focus.

Background

At present, the domestic closed circuit monitoring industry (CCTV) is developed towards miniaturization, multifunction and strong environment adaptability, and under the form of extremely intense domestic competition, the fixed focus lens cannot meet the requirements of customers in different regions, for example, the northeast market of China requires a designed monitoring device which is placed outdoors and is not defocused all the year round, the temperature of the northeast of China is often minus 30 ℃ in winter, and the highest temperature of the northeast of China can reach about 31 ℃ in summer. If the circuit heating factor of the monitoring camera is considered, it becomes necessary to design an imaging system with a large aperture and a focal plane which is not deviated within-40 ℃ to 85 ℃. Performing data statistics according to authority statistics of public security organs: nearly 70% of crimes occur at night or in dark regions, and darkness becomes a natural protective umbrella for criminals, and in view of color loss, unclear details and insufficient brightness under the infrared light supplement of the existing camera, the imaging quality of the current front-end camera under the weak light is difficult to find out to become a short plate for security and protection big data development, so that a large-aperture camera capable of realizing bright, clean and colorful pictures under low illumination is very necessary.

SUMMERY OF THE UTILITY MODEL

The utility model mainly provides a security protection monitoring is at big light ring imaging system of-40 ℃ -85 ℃ not out of focus.

In order to meet the design requirements, the utility model provides a technical scheme as follows:

a large-aperture high-low temperature confocal imaging system comprises a first glass spherical lens L1 with convex-concave negative focal power, a second glass spherical lens L2 with convex-concave negative focal power, a third plastic aspheric lens L3 with convex-concave positive focal power, a fourth glass spherical lens L4 with double convex positive focal power, a fifth glass spherical lens L5 with double convex positive focal power, a sixth plastic aspheric lens L6 with convex-concave negative focal power and a seventh plastic aspheric lens L7 with double convex positive focal power, which are sequentially arranged along the light incidence direction; the focal length and the refractive index of seven lenses and the curvature radius of four glass lenses of the system respectively satisfy the conditions of the following table 1:

f1＝-17.46±5％	n1＝1.517±5％	R11＝34.93±5％	R12＝7.11±5％
				f2＝-37.27±5％	n2＝1.523±5％	R21＝-7.84±5％	R22＝-15.11±5％
f3＝47.62±5％	n3＝1.535±5％
				f4＝30.32±5％	n4＝1.497±5％	R41＝17.76±5％	R42＝-93.45±5％
f5＝21.18±5％	n5＝1.497±5％	R51＝13.66±5％	R52＝-40.49±5％
				f6＝-12.55±5％	n6＝1.636±5％
f7＝12.72±5％	n7＝1.535±5％

TABLE 1

In the above table: f. of₁-f₇The focal lengths of the first glass spherical lens L1 and the seventh plastic aspheric lens L7 respectively correspond to the first glass spherical lens L1 and the seventh plastic aspheric lens; n is₁-n₇The refractive indexes of the first glass spherical lens L1 and the seventh plastic aspheric lens L7 respectively correspond in sequence; the R is₁₁And R₁₂Corresponding to the curvature radius of the first glass spherical lens L1, R₂₁And R₂₂Corresponding to the radius of curvature of the second spherical glass lens L2, R₄₁And R₄₂Corresponding to the radius of curvature of the fourth spherical glass lens L4, R₅₁And R₅₂Corresponds to the radius of curvature of the fifth aspherical lens L5, wherein "-" indicates that the direction is a negative direction.

The aspherical equations of the aspherical lenses L3, L6, and L7 satisfy:

in the above formula, the parameter c is a curvature radius, y is a radial coordinate, and k is a conic coefficient, wherein the third plastic aspheric lens L3 includes an R element₃₁Face and R₃₂The sixth plastic aspheric lens L6 includes opposite R₆₁Face and R₆₂The seventh plastic aspheric lens L7 includes opposite R₇₁Face and R₇₂Wherein R is₃₁Flour, R₃₂Flour, R₆₁Flour, R₆₂Flour, R₇₁Face and R₇₂The parameters of the face are:

TABLE 2

The utility model discloses mainly through the focal power of controlling 3 pieces of plastic aspheric surface lens two pieces of positive lens and the value that adds with the focal power of a piece of negative lens.

Namely, it is

Wherein f is₃，f₆，f₇See table 1.

The value of FNO of the utility model is in the following range

Where f is the system focal length and D is the entrance pupil diameter.

The utility model provides an imaging system is effectual guarantees the utility model discloses can not defocus in-40 ℃ -85 ℃ temperature variation. And reasonable adoption of the plastic aspheric surface can well improve the edge image quality and ensure high imaging quality. The large aperture makes the lens form clear image under weak light.

Drawings

Fig. 1 is a lens assembly diagram according to a first embodiment of the present invention.

Fig. 2 is a schematic view of an optical path according to a first embodiment of the present invention;

FIG. 3 is a MTF chart of the present invention under a low temperature of 20 deg.C;

FIG. 4 is a MTF chart of the present invention under the environment of normal temperature-40 deg.C;

fig. 5 is an MTF graph of the present invention at a high temperature of 85 ℃.

Detailed Description

The technical solution of the present invention is further explained by the following embodiments with reference to the accompanying drawings. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some but not all of the relevant portions of the present invention are shown in the drawings.

Referring to fig. 1 and 2, the present invention includes a first glass spherical lens L1 with convex-concave negative focal power, a second glass spherical lens L2 with convex-concave negative focal power, a third plastic aspheric lens L3 with convex-concave positive focal power, a fourth glass spherical lens L4 with double convex positive focal power, a fifth glass spherical lens L5 with double convex positive focal power, a sixth plastic aspheric lens L6 with convex-concave negative focal power, and a sixth plastic aspheric lens L7 with double convex positive focal power, which are sequentially arranged along the light incident direction; wherein the lens L1 comprises opposite R₁₁Face and R₁₂The lens L2 includes opposite R₂₁Face and R₂₂The lens L3 includes opposite R₃₁Face and R₃₂The lens L4 includes opposite R₄₁Face and R₄₂The lens L5 includes opposite R₅₁Face and R₅₂The lens L6 includes opposite R₆₁Face and R₆₂The lens L7 includes opposite R₇₁Face and R₇₂And (5) kneading.

The focal length and the refractive index of seven lenses and the curvature radius of four glass lenses of the system respectively meet the following conditions:

TABLE 1

The aspherical equations of the aspherical lenses L3, L6, and L7 satisfy:

in the above formula, the parameter c is a curvature radius, y is a radial coordinate, and k is a conic coefficient, wherein the third plastic aspheric lens L3, L6, and L7 include opposite surfaces: r₃₁Flour, R₃₂Flour, R₆₁Flour, R₆₂Flour, R₇₁Face and R₇₂The parameters of the face are:

TABLE 2

When the utility model discloses a seven lens's focus, refracting index and two pieces of glass lens's curvature radius, thickness satisfy above-mentioned table 1 condition respectively, can see that the MTF curve does not all appear serious out of focus phenomenon under extreme conditions such as 20 degrees centigrade normal atmospheric temperature, 40 ℃ low temperature below zero, 85 ℃ high temperature above zero by figure 3, figure 4, figure 5.

The above description is only for the preferred embodiment of the present invention, and should not be construed as limiting the present invention, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention should be included within the protection scope of the present invention.

Claims (4)

1. The large-aperture high-low-temperature confocal imaging system is characterized by comprising a first glass spherical lens L1 with convex-concave negative focal power, a second glass spherical lens L2 with convex-concave negative focal power, a third plastic aspheric lens L3 with convex-concave positive focal power, a fourth glass spherical lens L4 with double convex positive focal power, a fifth glass spherical lens L5 with double convex positive focal power, a sixth plastic aspheric lens L6 with convex-concave negative focal power and a sixth plastic aspheric lens L7 with double convex positive focal power, which are sequentially arranged along the light incidence direction; the focal length and the refractive index of the seven lenses of the imaging system and the curvature radius of the four glass lenses respectively meet the following conditions:

f₁＝-17.46±5％ n₁＝1.517±5％ R₁₁＝34.93±5％ R₁₂＝7.11±5％ f₂＝-37.27±5％ n₂＝1.523±5％ R₂₁＝-7.84±5％ R₂₂＝-15.11±5％ f₃＝47.62±5％ n₃＝1.535±5％ f₄＝30.32±5％ n₄＝1.497±5％ R₄₁＝17.76±5％ R₄₂＝-93.45±5％ f₅＝21.18±5％ n₅＝1.497±5％ R₅₁＝13.66±5％ R₅₂＝-40.49±5％ f₆＝-12.55±5％ n₆＝1.636±5％ f₇＝12.72±5％ n₇＝1.535±5％

in the above table: f. of₁-f₇The focal lengths of the first glass spherical lens L1 and the seventh plastic aspheric lens L7 respectively correspond to the first glass spherical lens L1 and the seventh plastic aspheric lens; n is₁-n₇The refractive indexes of the first glass spherical lens L1 and the seventh plastic aspheric lens L7 respectively correspond in sequence; the R is₁₁And R₁₂Corresponding to the curvature radius of the first glass spherical lens L1, R₂₁And R₂₂Corresponding to the radius of curvature of the second spherical glass lens L2, R₄₁And R₄₂Corresponding to the radius of curvature of the fourth spherical glass lens L4, R₅₁And R₅₂Corresponds to the radius of curvature of the fifth aspherical lens L5, wherein "-" indicates that the direction is a negative direction.

2. The large aperture high and low temperature confocal imaging system of claim 1, wherein: the aspheric surface equations of the third plastic aspheric lens with concave-convex positive focal power L3, the sixth plastic aspheric lens with concave-convex negative focal power L6 and the seventh plastic aspheric lens with double convex positive focal power L7 satisfy that:

in the above formula, the parameter c is a curvature radius, y is a radial coordinate, and k is a conic coefficient, wherein the third plastic aspheric lens L3 includes an R element₃₁Face and R₃₂The sixth plastic aspheric lens L6 includes opposite R₆₁Face and R₆₂The seventh plastic aspheric lens L7 includes opposite R₇₁Face and R₇₂Wherein R is₃₁Flour, R₃₂Flour, R₆₁Flour, R₆₂Flour, R₇₁Face and R₇₂The parameters of the face are as follows:

3. the large aperture high and low temperature confocal imaging system of claim 1, wherein: it is also satisfied that the sum of the powers of the fifth glass spherical lens L5 having a biconvex positive refractive power, the sixth plastic aspherical lens L6 having a convex-concave negative refractive power, and the sixth plastic aspherical lens L7 having a biconvex positive refractive power is in the following range

4. The large aperture high and low temperature confocal imaging system of claim 1 further satisfying FNO

Where f is the system focal length and D is the entrance pupil diameter.

Images