CN111929868A - Small-size large-aperture high-low temperature confocal optical device - Google Patents

Abstract

The invention discloses a small-sized large-aperture high-low temperature confocal optical device, which comprises a first plastic non-surface lens L1 with convex-concave negative focal power, a second glass spherical lens L2 with double-concave negative focal power and a third glass spherical lens L3 with double-convex positive focal power which are sequentially arranged along the light incidence direction and are glued together to form a first cemented lens J1, a fourth plastic non-surface lens L4 with double-concave negative focal power, a fifth glass spherical lens L5 with double-convex positive focal power, a sixth plastic non-surface lens L6 with double-convex positive focal power, a seventh plastic non-surface lens L7 with double-concave negative focal power and an eighth plastic non-surface lens L8 with double-convex positive focal power; the lens adopts a 3G5P structure, so that the cost is reduced. And the lens has compact structure by reasonably distributing focal power, so that the tolerance sensitivity is greatly reduced, various aberrations are well corrected by reasonably adopting the plastic aspheric lens, and the imaging quality is greatly improved.

Description

Small-size large-aperture high-low temperature confocal optical device

Technical Field

The invention mainly aims at security monitoring and ensures that the small-sized large-aperture optical device is not defocused at the temperature of-40-85 ℃.

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. Considering the circuit heating factor of the monitoring camera, it becomes necessary to design an optical imaging device with a large aperture and a non-offset focal plane within-40 deg.C to 85 deg.C. 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.

Disclosure of Invention

The invention mainly provides a small-sized large-aperture optical device which is not defocused at the temperature of-40-85 ℃ during security monitoring.

In order to meet the design requirements, the technical scheme provided by the invention is as follows:

A3G 5P glass-plastic mixed structure high-low temperature confocal optical device with a focal length of 4mm comprises a first plastic non-planar lens L1 with convex-concave negative focal power, a second glass spherical lens L2 with double-concave negative focal power and a third glass spherical lens L3 with double-convex positive focal power which are sequentially arranged along the light incidence direction and are glued together to form a first cemented lens J1, a fourth plastic non-planar lens L4 with double-concave negative focal power, a fifth glass spherical lens L5 with double-convex positive focal power, a sixth plastic non-planar lens L6 with double-concave positive focal power, a seventh plastic non-planar lens L7 with double-concave negative focal power and an eighth plastic non-planar lens L8 with double-convex positive focal power; the focal lengths and the refractive indexes of the eight lenses and the curvature radiuses of the three glass lenses of the optical device respectively meet the following conditions:

f1＝-8.3±5％	n1＝1.54±5％
				f2＝-7.0±5％	n2＝1.6±5％	R21＝-6.6±5％	R22＝12.2±5％
f3＝6.25±5％	n3＝2.0±5％	R31＝12.2±5％	R32＝-12.2±5％
				f4＝-11±5％	n4＝1.64±5％
f5＝-9.1±5％	n5＝1.59±5％	R51＝16.8±5％	R52＝-7.4±5％
				f6＝7.4±5％	n6＝1.54±5％
f7＝-7.8±5％	n7＝1.64±5％
				f8＝8.5±5％	n8＝1.54±5％

TABLE 1

In the above table: f. of₁-f₈The focal lengths of the first plastic aspheric lens L1 and the eighth plastic aspheric lens L8 respectively correspond to the first plastic aspheric lens L1 and the eighth plastic aspheric lens L8 in sequence; n is₁-n₈The refractive indexes of the first plastic aspheric lens L1 and the eighth plastic aspheric lens L8 respectively correspond in sequence; the R is₂₁And R₂₂Corresponding to the radius of curvature of the second spherical lens L2, R₃₁And R₃₂Corresponding to the curvature radius of the third spherical glass lens L3, R₅₁And R₅₂Corresponds to the radius of curvature of the fourth aspherical lens L4, wherein "-" indicates that the direction is a negative direction.

The aspherical equations of the aspherical lenses L1, L3, L6, L7, and L8 satisfy:

in the above formula, the parameter c is the curvature radius, y is the radial coordinate, and k is the conic coefficient, wherein the first plastic aspheric lens L1 includes the relative R₁₁Face and R₁₂The fourth plastic aspheric lens L4 includes opposite R₄₁Face and R₄₂The sixth plastic aspheric lens L6 includes opposite R₆₁Face and R₆₂The seventh plastic aspheric lens L7 includes opposite R₇₁Face and R₇₂The eighth plastic aspheric lens L8 includes opposite R₈₁Face and R₈₂Wherein R is₁₁Flour, R₁₂Flour, R₄₁Flour, R₄₂Flour, R₆₁Face and R₆₂、R₇₁Flour, R₇₂Flour, R₈₁Flour, R₈₂The parameters of the face are as follows:

TABLE 2

The invention mainly controls the sum of the focal powers of two positive lenses and the focal power of three negative lenses in the focal powers of 5 plastic non-spherical lenses to be in the following range:

wherein f is₁，f₃，f₆，f₇，f₈See table 1.

Values for fno. of the invention are in the following ranges:

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

The total optical length TTL of the invention meets the following range:

TTL≤23mm

wherein, TTL is the distance from the most front end of the lens to the image plane.

The optical device provided by the invention can effectively ensure that the optical device can not defocus in the temperature change of-40-85 ℃. 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 invention.

FIG. 2 is a MTF graph of the present invention at a low temperature of 20 ℃;

FIG. 3 is a MTF graph of the present invention at room temperature to 40 deg.C;

FIG. 4 is a MTF graph of the present invention at a high temperature of 85 ℃.

Detailed Description

The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached 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 aspects of the present invention are shown in the drawings.

Referring to fig. 1 and 2, the present invention includes a first plastic aspheric lens L1 with convex-concave negative power, a second glass spherical lens L2 with double-concave negative power, and a third glass spherical lens L3 with double-convex positive power, which are sequentially arranged along the light incidence direction, and are glued together to form a first cemented lens J1, a fourth plastic aspheric lens L4 with double-concave negative power, a fifth glass spherical lens L5 with double-convex positive power, a sixth plastic aspheric lens L6 with double-convex positive power, a seventh plastic aspheric lens L7 with double-concave negative power, and an eighth plastic aspheric lens L8 with double-convex positive power; the focal lengths and the refractive indexes of the eight lenses and the curvature radiuses of the three glass lenses of the optical device respectively meet the following conditions:

f1＝-8.3±5％	n1＝1.54±5％
				f2＝-7.0±5％	n2＝1.6±5％	R21＝-6.6±5％	R22＝12.2±5％
f3＝6.25±5％	n3＝2.0±5％	R31＝12.2±5％	R32＝-12.2±5％
				f4＝-11±5％	n4＝1.64±5％
f5＝-9.1±5％	n5＝1.59±5％	R51＝16.8±5％	R52＝-7.4±5％
				f6＝7.4±5％	n6＝1.54±5％
f7＝-7.8±5％	n7＝1.64±5％
				f8＝8.5±5％	n8＝1.54±5％

TABLE 1

In the above table: f. of₁-f₈The focal lengths of the first plastic aspheric lens L1 and the eighth plastic aspheric lens L8 respectively correspond to the first plastic aspheric lens L1 and the eighth plastic aspheric lens L8 in sequence; n is₁-n₈The refractive indexes of the first plastic aspheric lens L1 and the eighth plastic aspheric lens L8 respectively correspond in sequence; the R is₂₁And R₂₂Corresponding to the radius of curvature of the second spherical lens L2, R₃₁And R₃₂Corresponding to the curvature radius of the third spherical glass lens L3, R₅₁And R₅₂Corresponds to the radius of curvature of the fourth aspherical lens L4, wherein "-" represents a squareThe direction is negative.

The aspherical equations of the aspherical lenses L1, L3, L6, L7, and L8 satisfy:

in the above formula, the parameter c is the curvature radius, y is the radial coordinate, and k is the conic coefficient, wherein the first plastic aspheric lens L1 includes the relative R₁₁Face and R₁₂The fourth plastic aspheric lens L4 includes opposite R₄₁Face and R₄₂The sixth plastic aspheric lens L6 includes opposite R₆₁Face and R₆₂The seventh plastic aspheric lens L7 includes opposite R₇₁Face and R₇₂The eighth plastic aspheric lens L8 includes opposite R₈₁Face and R₈₂Wherein R is₁₁Flour, R₁₂Flour, R₄₁Flour, R₄₂Flour, R₆₁Face and R₆₂、R₇₁Flour, R₇₂Flour, R₈₁Flour, R₈₂The parameters of the face are as follows:

TABLE 2

When the focal length and the refractive index of the 8 lenses and the curvature radius and the thickness of the two glass lenses respectively meet the conditions in the table 1, the MTF curves do not have serious defocusing phenomenon under the limit conditions of 20 ℃ normal temperature, minus 40 ℃ low temperature, minus 85 ℃ high temperature and the like as can be seen from fig. 2, 3 and 4.

The present invention is not limited to the above preferred embodiments, and any modifications, equivalent replacements, improvements, etc. within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (5)

1. The small-sized large-aperture high-low temperature confocal optical device is characterized by comprising a first plastic non-surface lens L1 with convex-concave negative focal power, a second glass spherical lens L2 with double-concave negative focal power and a third glass spherical lens L3 with double-convex positive focal power which are sequentially arranged along the light incidence direction and glued together to form a first cemented lens J1, a fourth plastic non-surface lens L4 with double-concave negative focal power, a fifth glass spherical lens L5 with double-convex positive focal power, a sixth plastic non-surface lens L6 with double-convex positive focal power, a seventh plastic non-surface lens L7 with double-concave negative focal power and an eighth plastic non-surface lens L8 with double-convex positive focal power; the focal lengths and the refractive indexes of the eight lenses and the curvature radiuses of the three glass lenses of the optical device respectively meet the following conditions:

f₁＝-8.3±5％ n₁＝1.54±5％ f₂＝-7.0±5％ n₂＝1.6±5％ R₂₁＝-6.6±5％ R₂₂＝12.2±5％ f₃＝6.25±5％ n₃＝2.0±5％ R₃₁＝12.2±5％ R₃₂＝-12.2±5％ f₄＝-11±5％ n₄＝1.64±5％ f₅＝-9.1±5％ n₅＝1.59±5％ R₅₁＝16.8±5％ R₅₂＝-7.4±5％ f₆＝7.4±5％ n₆＝1.54±5％ f₇＝-7.8±5％ n₇＝1.64±5％ f₈＝8.5±5％ n₈＝1.54±5％

in the above table: f. of₁-f₈The focal lengths of the first plastic aspheric lens L1 and the eighth plastic aspheric lens L8 respectively correspond to the first plastic aspheric lens L1 and the eighth plastic aspheric lens L8 in sequence; n is₁-n₈The refractive indexes of the first plastic aspheric lens L1 and the eighth plastic aspheric lens L8 respectively correspond in sequence; the R is₂₁And R₂₂Corresponding to the radius of curvature of the second spherical lens L2, R₃₁And R₃₂Corresponding to the curvature radius of the third spherical glass lens L3, R₅₁And R₅₂Corresponds to the radius of curvature of the fourth aspherical lens L4, wherein "-" indicates that the direction is a negative direction.

2. The small-sized large-aperture high-low temperature confocal optical device as claimed in claim 1, wherein: the aspheric surface equations of the first plastic aspheric lens L1 with the concave-convex positive focal power, the fourth plastic aspheric lens L4 with the double-concave negative focal power, the sixth plastic aspheric lens L6 with the double-convex positive focal power, the seventh plastic aspheric lens L7 with the double-concave negative focal power and the eighth plastic aspheric lens L8 with the double-convex positive focal power satisfy that:

in the above formula, the parameter c is the curvature radius, y is the radial coordinate, and k is the conic coefficient, wherein the first plastic aspheric lens L1 includes the relative R₁₁Face and R₁₂The fourth plastic aspheric lens L4 includes opposite R₄₁Face and R₄₂The sixth plastic aspheric lens L6 includes opposite R₆₁Face and R₆₂The seventh plastic aspheric lens L7 includes opposite R₇₁Face and R₇₂The eighth plastic aspheric lens L8 includes opposite R₈₁Face and R₈₂Wherein R is₁₁Flour, R₁₂Flour, R₄₁Flour, R₄₂Flour, R₆₁Face and R₆₂、R₇₁Flour, R₇₂Flour, R₈₁Flour, R₈₂The parameters of the face are as follows:

3. the small large aperture high and low temperature confocal optical device of claim 1, wherein: the sum of the focal powers of two positive lenses and the focal power of three negative lenses in the focal powers of the 5 plastic non-spherical lenses is in the following range:

4. the large aperture high and low temperature confocal optical device of claim 1, wherein: it also satisfies that the value of FNO is in the following range:

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

5. The small large aperture high and low temperature confocal optical device of claim 1, wherein: the total optical length TTL satisfies the following range:

TTL≤23mm

wherein, TTL is the distance from the most front end of the lens to the image plane.

Images