A long-wave athermal infrared lens

Abstract

The invention relates to the technical field of infrared lens production, and provides a long-wave athermal infrared lens, which is characterized in that a first lens, a second lens, a third lens and a fourth lens are sequentially arranged along an optical axis from an object side to an image side, the first lens is a meniscus lens, the second lens is a meniscus lens, the third lens is a biconvex lens, and the fourth lens is a biconvex lens. Only the above four lenses of the lens have optical power, and a focal length of 7.8 mm, a resolution of 1280X1024 and a maximum field of view of 120° are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of infrared lens production, and in particular to a long-wave athermal infrared lens. Background Art

[0002] The infrared thermal imaging system has many advantages such as good concealment, strong anti-electronic interference ability, intuitive image, easy observation, high precision, good low-altitude detection performance, etc. At the same time, it also has strong ability to penetrate smoke, fog, haze, snow and other restrictions and identify camouflage. It is particularly suitable for detecting targets at night and under complex meteorological conditions, making it have a wide range of application prospects in the fields of alert, reconnaissance and security, and it has received increasing attention from various scientific research units and enterprises. Compared with the refrigerated staring infrared thermal imager, although there is still a big gap in sensitivity such as temperature resolution, the non-refrigerated one has some outstanding advantages, such as no need to cool the detector, greatly reduced device cost, low power consumption, light weight, miniaturization, fast startup, easy to use, flexible, wide range of applications, and high cost performance.

[0003] Generally speaking, infrared lenses usually use long-wave and medium-wave wavelengths. The long-wave lens uses a wavelength of 8-14um, and the medium-wave lens uses a wavelength of 3-5um. Currently, many long-wave infrared lenses have complex designs and a large number of lenses, resulting in a complex optical system architecture, obvious image distortion, and a small field of view. Summary of the invention

[0004] The object of the present invention is to provide a long-wave athermal infrared lens, which is realized by using four lenses, has a focal length of 7.8 mm, a resolution of 1280X1024, and a maximum field of view of 120°.

[0005] To achieve the above object, the technical solution adopted by the present invention is: a long-wave athermal infrared lens, characterized in that: an objective lens first lens, an objective lens second lens, an objective lens third lens, and an objective lens fourth lens are sequentially arranged from the object side to the image side along the optical axis direction;

[0006] The first lens of the objective lens is a meniscus lens with the convex surface facing the object side, the second lens of the objective lens is a meniscus lens with the convex surface facing the object side, the third lens of the objective lens is a biconvex lens, and the fourth lens of the objective lens is a biconvex lens. Only the above four lenses of the lens have optical power.

[0007] As a further improvement of the present invention, the object side curvature radius of the first lens of the objective lens is 44.57mm, the image side curvature radius is 23.139mm, and the center thickness is 3.6m; the object side curvature radius of the second lens of the objective lens is 17.378mm, the image side curvature radius is 15.344mm, and the center thickness is 4.5mm; the object side curvature radius of the third lens of the objective lens is 60.81mm, the image side curvature radius is -126.022mm, and the center thickness is 7mm; the object side curvature radius of the fourth lens of the objective lens is 46.134mm, the image side curvature radius is -123.03mm, and the center thickness is 7mm.

[0008] As a further improvement of the present invention, along the optical axis direction, the distance between the first lens and the second lens of the objective lens is 6.73 mm, the distance between the second lens and the third lens of the objective lens is 12.78 mm, and the distance between the third lens and the fourth lens of the objective lens is 10.617 mm.

[0009] As a further improvement of the present invention, the diameter of the first lens of the objective lens is 45 mm, the diameter of the second lens of the objective lens is 28 mm, the diameter of the third lens of the objective lens is 38.5 mm, and the diameter of the fourth lens of the objective lens is 38.5 mm.

[0010] As a further improvement of the present invention, the object side of the first lens of the objective lens is coated with a DLC film, and the image side is coated with an AR film.

[0011] The beneficial effects of the present invention are mainly embodied in:

[0012] Through reasonable optical system design, the focal length of the lens is 7.8mm, the maximum field of view is 120°, the effective imaging surface diameter is 20mm, the weight is less than 221 grams, the resolution is 1280X1024, and the wavelength is 8-12um. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the structure of the present invention;

[0014] Figure 2 is a field curvature distortion diagram of the present invention;

[0015] Figure 3 It is the MTF diagram of the present invention. DETAILED DESCRIPTION

[0016] The present invention will be further described below in conjunction with the accompanying drawings. Figure 1-3 As shown, a long-wave athermal infrared lens is characterized in that: an objective lens first lens 1, an objective lens second lens 2, an objective lens third lens 3, and an objective lens fourth lens 4 are sequentially arranged from the object side to the image side along the optical axis direction;

[0017] The first lens 1 of the objective lens is a meniscus lens with the convex surface facing the object side, the second lens 2 of the objective lens is a meniscus lens with the convex surface facing the object side, the third lens 3 of the objective lens is a biconvex lens, and the fourth lens 4 of the objective lens is a biconvex lens. Only the above four lenses of the lens have optical power.

[0018] The first lens 1 of the objective lens has an object side curvature radius of 44.57 mm, an image side curvature radius of 23.139 mm, and a center thickness of 3.6 mm. The second lens 2 of the objective lens has an object side curvature radius of 17.378 mm, an image side curvature radius of 15.344 mm, and a center thickness of 4.5 mm. The third lens 3 of the objective lens has an object side curvature radius of 60.81 mm, an image side curvature radius of -126.022 mm, and a center thickness of 7 mm. The fourth lens 4 of the objective lens has an object side curvature radius of 46.134 mm, an image side curvature radius of -123.03 mm, and a center thickness. The diameter of the first lens 1 of the objective lens is 45 mm, the diameter of the second lens 2 of the objective lens is 28 mm, the diameter of the third lens 3 of the objective lens is 38.5 mm, and the diameter of the fourth lens 4 of the objective lens is 38.5 mm. The object side of the first lens 1 of the objective lens is coated with DLC film, and the image side is coated with AR film.

[0019] The focal length of the lens is 7.8mm, the maximum field of view is 120°, the effective imaging surface diameter is 20mm, the weight is less than 221 grams, the resolution is 1280X1024, and the wavelength is 8-12um. Figure 2 is the field curvature distortion diagram of this application, from Figure 2 We can see that this application has no obvious chromatic aberration, no obvious lines, high imaging quality, and very little distortion, less than 3%, and almost no deformation at the edge of the image. In simple terms, the edge of the image plane does not deform after imaging. Figure 3 It is the MTF diagram of this application, that is, the modulation transfer function diagram, from Figure 3 We can see that the lens transmits a lot of information, has good imaging quality, and the image is relatively clear.

Claims

1. A long-wave athermal infrared lens, characterized in that: An objective lens first lens (1), an objective lens second lens (2), an objective lens third lens (3), and an objective lens fourth lens (4) are arranged in sequence from the object side to the image side along the optical axis; The first lens (1) of the objective lens is a meniscus lens with a convex surface facing the object side, the second lens (2) of the objective lens is a meniscus lens with a convex surface facing the object side, the third lens (3) of the objective lens is a biconvex lens, and the fourth lens (4) of the objective lens is a biconvex lens, and only the above four lenses have optical power; The first lens (1) of the objective lens has an object side curvature radius of 44.57 mm, an image side curvature radius of 23.139 mm, and a center thickness of 3.6 mm; the second lens (2) of the objective lens has an object side curvature radius of 17.378 mm, an image side curvature radius of 15.344 mm, and a center thickness of 4.5 mm; the third lens (3) of the objective lens has an object side curvature radius of 60.81 mm, an image side curvature radius of -126.022 mm, and a center thickness of 7 mm; the fourth lens (4) of the objective lens has an object side curvature radius of 46.134 mm, an image side curvature radius of -123.03 mm, and a center thickness of 7 mm.

2. The long-wave athermal infrared lens according to claim 1, characterized in that: Along the optical axis direction, the distance between the first lens (1) of the objective lens and the second lens (2) of the objective lens is 6.73 mm, the distance between the second lens (2) of the objective lens and the third lens (3) of the objective lens is 12.78 mm, and the distance between the third lens (3) of the objective lens and the fourth lens (4) of the objective lens is 10.617 mm.

3. The long-wave athermal infrared lens according to claim 1, characterized in that: The diameter of the first lens (1) of the objective lens is 45 mm, the diameter of the second lens (2) of the objective lens is 28 mm, the diameter of the third lens (3) of the objective lens is 38.5 mm, and the diameter of the fourth lens (4) of the objective lens is 38.5 mm.

4. The long-wave athermal infrared lens according to claim 1, characterized in that: The object side of the first lens (1) of the objective lens is coated with a DLC film, and the image side is coated with an AR film.

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