CN215219301U

CN215219301U - Large-zoom-ratio high-resolution uncooled infrared objective lens

Info

Publication number: CN215219301U
Application number: CN202120671766.8U
Authority: CN
Inventors: 张洪升; 贾耘
Original assignee: Kunming Nan Xu Photoelectric Technologies Co ltd
Current assignee: Kunming Nan Xu Photoelectric Technologies Co ltd
Priority date: 2021-04-01
Filing date: 2021-04-01
Publication date: 2021-12-17
Anticipated expiration: 2031-04-01

Abstract

The utility model discloses a large zoom ratio high resolution uncooled infrared objective lens, belonging to the technical field of infrared optics; it includes from the object space to the image space in proper order: the zoom lens comprises a front fixed group, a zoom group, a first compensation group, a second compensation group and a rear fixed group, wherein the front fixed group, the zoom group, the first compensation group, the second compensation group and the rear fixed group are arranged from left to right in a coaxial manner, in the zooming process, the zoom group, the first compensation group and the second compensation group move along an optical axis to convert long focus, middle focus and short focus, and the front fixed group and the rear fixed group are kept in situ; the utility model discloses be applied to resolution ratio 1280 x 1024, pixel size 12 mu m's non-refrigeration type infrared detector, the zoom ratio is 10.7 times, comprises 6 lens, and lens are small in quantity, and simple structure adopts an infrared optical material, and reasonable distribution light focal power has realized performance requirements such as high resolution, big zoom ratio, and objective has the function of becoming doubly in succession, realizes the observation of distance through the focusing, has higher imaging quality.

Description

Large-zoom-ratio high-resolution uncooled infrared objective lens

Technical Field

The utility model relates to an uncooled infrared objective especially relates to a big non-refrigerated infrared objective of zoom ratio high resolution ratio, belongs to infrared optics technical field.

Background

The uncooled infrared detector has the advantages of low price, small volume, light weight, low power consumption, high reliability and the like, so the uncooled infrared detector is widely applied, and is widely applied to various fields such as monitoring, warning, monitoring, reconnaissance, forest fire prevention and the like due to the all-weather day and night observation capability. Compared with refrigeration infrared products, the non-refrigeration infrared detector does not need to refrigerate the detector, the cost of devices is greatly reduced, the starting time is greatly shortened, the use is convenient, and the application range is wider. With the continuous development and maturation of the non-refrigeration detector technology and the continuous expansion of the application range thereof, the demand on the non-refrigeration detector technology is increasingly enhanced. Currently, with the continuous progress of the uncooled infrared technology, the uncooled infrared detector is also rapidly developed towards two directions of high performance and low cost. However, the design of the continuous variable-magnification uncooled infrared objective optical system has the problems of large relative aperture, small F number, generally small variable-magnification ratio and few continuous variable-magnification objectives with the variable-magnification ratio larger than 10. The traditional continuous zooming uncooled infrared objective optical system is complex in structure and large in lens quantity, so that the system is low in transmittance and resolution, long in total optical length, large in overall dimension, heavy in weight, large in size, greatly influenced by temperature and poor in regional applicability.

The zoom ratio of the infrared zoom system disclosed by the prior art is not large, and the Chinese utility model patent with the application number of 201821919649.3 discloses a continuous zoom infrared lens with large zoom ratio, which comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens, wherein the focal length of the continuous zoom lens is 25-225mm, the focal length of the continuous zoom lens is 9 times, the working wavelength is 8-12um, and the focusing range is 15m to infinity. But the zoom ratio is still not high, so that the applicability and the application range are limited.

SUMMERY OF THE UTILITY MODEL

In order to overcome the deficiencies of the prior art, the utility model provides a big zoom ratio high resolution ratio uncooled infrared objective.

The utility model adopts the technical proposal that: designing a big zoom ratio high resolution ratio uncooled infrared objective lens, it includes from the object space to the image space in proper order: the zoom lens comprises a front fixed group, a zoom group, a first compensation group, a second compensation group and a rear fixed group, wherein the front fixed group, the zoom group, the first compensation group, the second compensation group and the rear fixed group are arranged from left to right in a coaxial manner, in the zooming process, the zoom group, the first compensation group and the second compensation group move along an optical axis to convert long focus, middle focus and short focus, and the front fixed group and the rear fixed group are kept in situ; the front fixing group comprises a first lens, the variable-power group comprises a second lens, the first compensation group comprises a third lens, the second compensation group comprises a fourth lens, the rear fixing group comprises a fifth lens and a focusing group, and the focusing group comprises a sixth lens.

Further, the first lens is a meniscus positive lens, the object side surface of the first lens is a convex surface, the image side surface of the first lens is a concave surface, and the diopter of the first lens is positive.

Further, the second lens is a double-concave negative lens, the object side surface of the second lens is a concave surface, the image side surface of the second lens is a concave surface, and the diopter of the second lens is negative.

Further, the third lens element is a biconvex positive lens element, an object-side surface of the third lens element is a convex surface, an image-side surface of the third lens element is a convex surface, and diopter of the third lens element is positive.

Further, the fourth lens is a concave-convex negative lens, the object-side surface of the fourth lens is a concave surface, the image-side surface of the fourth lens is a convex surface, and the diopter of the fourth lens is negative.

Further, the fifth lens is a concave-convex negative lens, the object-side surface of the fifth lens is a concave surface, the image-side surface of the fifth lens is a convex surface, and the diopter of the fifth lens is negative.

Further, the sixth lens element is a meniscus positive lens element, the object-side surface of the sixth lens element is convex, the image-side surface of the sixth lens element is concave, and the diopter of the sixth lens element is positive.

Furthermore, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens are respectively provided with an aspheric surface; the second lens has a diffractive surface.

Compared with the prior art, the beneficial effects of the utility model are that: the utility model provides a big zoom ratio high resolution non-refrigeration infrared objective adopts the type optical structure of taking a photograph of far away, and objective first lens focal power is positive, as preceding fixed group; the focal power of the second lens is negative, and the second lens is used as a zoom group to perform linear movement to realize zoom; the focal power of the third lens is positive, and the third lens is used as a zoom group of the first compensation group to perform nonlinear linear movement to realize zoom compensation; the focal power of the fourth lens is negative, and the fourth lens is used as a second compensation group to perform nonlinear linear movement to realize zoom compensation; the focal power of the fifth lens is negative, the focal power of the sixth lens is positive, the fifth lens and the sixth lens jointly form a rear fixed group, wherein the sixth lens is used as a focusing group, and the imaging effect and the temperature compensation of the object at the distance are adjusted. Meanwhile, the refraction/diffraction surface is mixed in the system, so that the system ensures the image quality and simplifies the optical structure form, the number of lenses is small, the volume of the whole objective lens is small, and the use, the operation and the application range are more convenient.

The utility model discloses objective has important effect in the aspect of field control, fire prevention monitoring and policeman, frontier defense warning etc. can be all-weather, on a large scale the control peripheral condition. The diffraction optical element has negative dispersion characteristics and negative temperature characteristics, so that phase modulation on an optical wave surface can be realized; and the system is matched with a refraction element, so that the imaging quality of the system is greatly improved, the volume and the weight of the system are reduced, the cost is reduced, and the like. The utility model discloses objective introduces the second compensation group under the requirement of big zoom ratio, high resolution, improves the system and looks like the matter, shortens the total length of system. The utility model provides a technical problem be to resolution ratio 1280 x 1024, the uncooled type infrared detector of the 12 mu m of pixel size, provide a big zoom ratio, high resolution uncooled infrared objective. The system has a field of view of 30.6 degrees multiplied by 24.7 degrees multiplied by 2.9 degrees multiplied by 2.3 degrees, a zoom ratio of 10.7 times, and good image quality within the range of-40 ℃ to +50 ℃.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a schematic diagram of the short-focus optical structure of the present invention;

FIG. 2 is a schematic diagram of the optical structure of the present invention in the middle of focus;

FIG. 3 is a schematic view of the optical structure of the present invention in long focus;

FIG. 4 is a diagram of the transfer function at 20 ℃ in the case of short focus of the present invention;

FIG. 5 is a graph showing the transfer function at 20 ℃ in the middle scorching time of the present invention;

FIG. 6 is a diagram showing the transfer function at 20 ℃ in the case of long coke according to the present invention;

FIG. 7 is a speckle pattern of the utility model at 20 ℃ in short-focus;

FIG. 8 is a diffuse speckle pattern of the present invention at 20 ℃ in middle-jiao;

FIG. 9 is a speckle pattern at 20 ℃ for long-focus of the present invention;

FIG. 10 is a diagram of the distortion at 20 ℃ during short scorching of the present invention.

FIG. 11 is a diagram showing the distortion at 20 ℃ in the middle scorching of the present invention.

FIG. 12 is a diagram showing the distortion at 20 ℃ in the case of the present invention.

In the figure: 1-first lens, 2-second lens, 3-third lens, 4-fourth lens, 5-fifth lens, 6-sixth lens.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.

In the description of the present invention, unless otherwise indicated, the terms "first", "second", and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

Example 1

As shown in fig. 1-3: the utility model provides a big zoom ratio high resolution ratio uncooled infrared objective, it includes from the object space to the image space in proper order: the zoom lens comprises a front fixed group, a zoom group, a first compensation group, a second compensation group and a rear fixed group, wherein the front fixed group, the zoom group, the first compensation group, the second compensation group and the rear fixed group are arranged from left to right in a common optical axis mode, in the zooming process, the zoom group, the first compensation group and the second compensation group move along the optical axis to convert long focus, middle focus and short focus, and the front fixed group and the rear fixed group are kept in the original position.

The front fixing group comprises a first lens 1, the first lens 1 is a meniscus positive lens, the object side surface of the first lens 1 is a convex surface, the image side surface of the first lens is a concave surface, and the diopter of the first lens is positive. The zoom group comprises a second lens 2, the second lens 2 is a double-concave negative lens, the object side surface of the second lens 2 is a concave surface, the image side surface of the second lens is a concave surface, and the diopter of the second lens is negative, so that the zoom group can effectively correct curvature of field and distortion. The first compensation group comprises a third lens 3, the third lens 3 is a biconvex positive lens, the object side surface of the third lens 3 is a convex surface, the image side surface is a convex surface, and the diopter of the third lens is positive, so that the first compensation group can effectively correct spherical aberration. The second compensation group comprises a fourth lens 4, the fourth lens 4 is a concave-convex negative lens, the object side surface of the fourth lens 4 is a concave surface, the image side surface of the fourth lens is a convex surface, and diopter of the fourth lens is negative, and the second compensation group can effectively correct chromatic aberration. The rear fixing group comprises a fifth lens 5 and a focusing group, the fifth lens 5 is a concave-convex negative lens, the object side surface of the fifth lens 5 is a concave surface, the image side surface is a convex surface, and the diopter of the fifth lens is negative; the focusing group comprises a sixth lens 6, the sixth lens 6 is a meniscus positive lens, the object side surface of the sixth lens 6 is a convex surface, the image side surface of the sixth lens is a concave surface, and diopter of the sixth lens is positive, so that the focusing group can be used for adjusting the imaging effect and temperature compensation of a far and near distance target.

The second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5 and the sixth lens 6 are all high-order aspheric surfaces; the object side surface of the second lens 2 adopts a diffraction surface on an aspheric substrate.

In this embodiment, for an uncooled infrared detector with a pixel size of 12 μm of 1280 × 1024, the focal length f of the optical system is designed: 28 mm-300 mm, F number: 1.2, field of view: 30.6 ° × 24.7 ° to 2.9 ° × 2.3 °. More specifically, in order to improve the image quality and the influence of temperature change on the image quality, high-order aspheric surfaces are adopted in the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5 and the sixth lens 6. Table 1 lists the aspheric coefficients of the object-side surface S3 of the second lens 2, the image-side surface S6 of the third lens 3, the object-side surface S7 of the fourth lens 4, the object-side surface S9 of the fifth lens 5, and the object-side surface S11 of the sixth lens 6.

TABLE 1 aspheric coefficients of surfaces S3, S6, S7, S9, S11

Surface of	K	A	B	C	D
						S3	0	9.40065E-08	-3.82867E-12	-8.79029E-16	2.38085E-19
S6	0	8.22541E-08	-5.29249E-12	5.99378E-16	-7.22309E-20
						S7	0	-8.09047E-08	1.92253E-10	-1.48613E-13	5.38476E-17
S9	0	5.14333E-07	-2.68765E-10	2.54044E-13	-1.26238E-16
						S11	0	-1.86732E-07	-3.12247E-11	-9.77041E-15	1.67308E-18

The aspherical surfaces in the above lenses satisfy the relational expression (the even-order aspherical surface equation is defined as follows):

wherein Z is the distance rise from the vertex of the aspheric surface when the aspheric surface is at the position with the height of y along the optical axis direction; c is 1/R, R represents the paraxial radius of curvature of the mirror surface; k is the cone coefficient; A. b, C, D are high-order aspheric coefficients.

Table 2 lists the coefficients of the diffraction surfaces on the object side of the second lens 2.

TABLE 2 diffraction surface coefficients of the second lens 2 on the object side

Surface of	Diffraction order	Center wavelength (mum)	C1	C2
					S3
	1	10	-3.0998E-05	3.3874E-10

Wherein C1 and C2 are respectively the 2-order item and the 4-order item coefficients of the diffraction surface.

The imaging quality is good due to the fact that the imaging device adopts 5 aspheric surfaces and 1 diffraction surface, manufacturability is good, the number of lenses can be reduced, and cost is reduced.

Fig. 4 to 12 are graphs of imaging optical simulation data of the uncooled high resolution and large zoom ratio infrared objective of the present invention at 20 ℃, wherein fig. 4 to 6 are graphs of optical transfer function (MTF) curves, the horizontal axis is logarithm per millimeter (lp/mm), and the vertical axis is contrast value; fig. 7 to 9 are graphs of the scattered spots (dot columns), fig. 10 to 12 are distortion graphs, and it can be seen from the graph curves of fig. 4 to 12 that the MTF, the root mean square value and the distortion of the scattered spots are all within the standard range at the temperature of 20 ℃, and the system requirements are met. Therefore, the utility model provides a big zoom ratio, high resolution uncooled infrared objective have good image quality.

The utility model discloses be applied to resolution ratio 1280 x 1024, the uncooled type infrared detector of 12 mu m of pixel size, the zoom ratio is 10.7 times. The objective lens is composed of 6 lenses in total, the number of the lenses is small, and the structure is simple. The infrared optical material is adopted, the focal power is reasonably distributed, the performance requirements such as high resolution, large zoom ratio and the like are met, the objective lens has a continuous zoom function, the long-distance and short-distance observation is realized through focusing, and the high imaging quality is achieved.

While the present invention has been described in detail with reference to the embodiments shown in the drawings, the present invention is not limited to the embodiments, and various changes can be made without departing from the spirit of the present invention within the knowledge of those skilled in the art.

Claims

1. The utility model provides a big zoom ratio is high resolution ratio uncooled infrared objective which characterized in that includes from the object space to the image space in proper order: the zoom lens comprises a front fixed group, a zoom group, a first compensation group, a second compensation group and a rear fixed group, wherein the front fixed group, the zoom group, the first compensation group, the second compensation group and the rear fixed group are arranged from left to right in a coaxial manner, in the zooming process, the zoom group, the first compensation group and the second compensation group move along an optical axis to convert long focus, middle focus and short focus, and the front fixed group and the rear fixed group are kept in situ; the front fixed group comprises a first lens (1), the variable-power group comprises a second lens (2), the first compensation group comprises a third lens (3), the second compensation group comprises a fourth lens (4), the rear fixed group comprises a fifth lens (5) and a focusing group, and the focusing group comprises a sixth lens (6).

2. The large zoom ratio high resolution uncooled infrared objective lens of claim 1, wherein: the first lens (1) is a meniscus positive lens, the object side surface of the first lens (1) is a convex surface, the image side surface of the first lens is a concave surface, and the diopter of the first lens is positive.

3. The large zoom ratio high resolution uncooled infrared objective lens of claim 2, wherein: the second lens (2) is a double-concave negative lens, the object side surface of the second lens (2) is a concave surface, the image side surface of the second lens is a concave surface, and the diopter of the second lens is negative.

4. The large zoom ratio high resolution uncooled infrared objective lens of claim 3, wherein: the third lens (3) is a biconvex positive lens, the object side surface of the third lens (3) is a convex surface, the image side surface of the third lens is a convex surface, and the diopter of the third lens is positive.

5. The large zoom ratio high resolution uncooled infrared objective lens of claim 4, wherein: the fourth lens (4) is a concave-convex negative lens, the object side surface of the fourth lens (4) is a concave surface, the image side surface of the fourth lens is a convex surface, and the diopter of the fourth lens is negative.

6. The large zoom ratio high resolution uncooled infrared objective lens of claim 5, wherein: the fifth lens (5) is a concave-convex negative lens, the object side surface of the fifth lens (5) is a concave surface, the image side surface of the fifth lens is a convex surface, and the diopter of the fifth lens is negative.

7. The large zoom ratio high resolution uncooled infrared objective lens of claim 6, wherein: the sixth lens (6) is a meniscus positive lens, the object side surface of the sixth lens (6) is a convex surface, the image side surface is a concave surface, and the diopter of the sixth lens is positive.

8. The large zoom ratio uncooled infrared objective lens according to any one of claims 1 to 7, wherein: the second lens (2), the third lens (3), the fourth lens (4), the fifth lens (5) and the sixth lens (6) are respectively provided with an aspheric surface; the second lens (2) has a diffraction surface.