Axial moving type diaphragm-variable double-view-field long-wave infrared zoom optical system

Abstract

The utility model discloses an axial moving type diaphragm-variable double-view-field long-wave infrared zoom optical system. The optical system. The optical system comprises a lens I (1), a zoom lens (2), a rear group lens I (3) and a focusing lens (4), the zoom lens moves towards the first lens to form a wide field of view and moves towards the first lens of the rear group to form a narrow field of view, and the zoom ratio of the wide field of view to the narrow field of view is 3. The total length of the axial moving type variable diaphragm double-view-field long-wave infrared zoom optical system is 163mm, and the optical system is suitable for a 64051217 [mu] m infrared detector. The optical system is small in number of lenses, high in transmittance, light in weight, good in imaging quality, short in wide and narrow view field switching time and capable of imaging clearly within the temperature range of-40 DEG C to 60 DEG C in a focusing compensation mode.

Description

Technical Field

[0001] The utility model discloses an axially movable variable aperture dual - field long - wave infrared zoom optical system. This optical system realizes the switching between wide and narrow fields of view by moving the zoom lens back and forth, and realizes clear imaging of the wide and narrow fields of view in a wide temperature range of - 40°C to 60°C by moving the focusing lens, belonging to the field of optical design. Background Technique

[0002] In recent years, infrared thermal imaging products have developed rapidly. Due to their all - weather observation ability, they are widely used in many military and civilian fields such as warning, reconnaissance, and forest fire prevention. Compared with ordinary fixed - focus thermal imagers, variable - focal - length infrared thermal imagers can quickly change the system focal length within a certain range and obtain images with different scales, so they are widely used in thermal imager products.

[0003] Variable - focal - length infrared optical systems are divided into continuous - zoom infrared optical systems, dual - field zoom infrared optical systems, and triple - field zoom infrared optical systems. The dual - field zoom infrared optical system has the advantages of simple structure, fast zoom speed, and short switching time, so it has a wide range of applications in various fields.

[0004] The existing variable - focal - length infrared optical systems cannot achieve clear imaging of the wide and narrow fields of view in a wide temperature range of - 40°C to 60°C, and cannot meet the use requirements of large - field - of - view search and small - field - of - view reconnaissance. Summary of the Invention

[0005] The purpose of the utility model is to provide an axially movable variable aperture dual - field long - wave infrared zoom optical system. This optical system can realize the switching between wide and narrow fields of view by moving the zoom lens back and forth, and realize clear imaging of the wide and narrow fields of view in a wide temperature range of - 40°C to 60°C by moving the focusing lens. The variable magnification ratio of the wide and narrow fields of view is 3, and it has the advantages of fast zoom speed, light weight, and good imaging quality.

[0006] In order to achieve the above - mentioned technical purpose, the utility model adopts the following technical solutions:

[0007] An axially movable variable aperture dual - field long - wave infrared zoom optical system, the optical system includes a first lens, a zoom lens, a first rear - group lens, and a focusing lens. The first lens, the zoom lens, the first rear - group lens, and the focusing lens are arranged in sequence from the object side to the image side; when the zoom lens moves towards the first lens, it is a wide field of view, and when the zoom lens moves towards the first rear - group lens, it is a narrow field of view.

[0008] Further, when the optical system switches from the wide field of view to the narrow field of view, the aperture changes from the front surface of the first rear - group lens to the front surface of the first lens.

[0009] Further, the variable magnification ratio of the wide and narrow fields of view of the optical system is 3.

[0010] Further, the first lens of the optical system is a meniscus positive lens, the zoom lens is a double concave negative lens, the first rear group lens is a double convex positive lens, and the focusing lens is a meniscus positive lens.

[0011] Further, the focal length of the first lens is f1, where 90 mm < f1 < 100 mm; the focal length of the zoom lens is f2, where -25 mm < f2 < -15 mm; the focal length of the first rear group lens is f3, where 35 mm < f3 < 45 mm; the focal length of the focusing lens is f4, where 50 mm < f4 < 60 mm.

[0012] Further, for the optical system, the distance from the front surface of the first lens to the image plane is 163 mm.

[0013] Further, the optical system can achieve clear imaging of wide and narrow fields of view in the wide temperature range of -40°C to 60°C by moving the focusing lens.

[0014] The beneficial effects of the optical system of the present utility model are as follows:

[0015] 1. The axially movable variable aperture dual-field long-wave infrared zoom optical system of the present utility model can achieve rapid switching between wide and narrow fields of view by moving the zoom lens back and forth;

[0016] 2. The axially movable variable aperture dual-field long-wave infrared zoom optical system of the present utility model includes four lenses, has a compact structure, a small number of lenses, high transmittance, light weight, and is easy to process and align;

[0017] 3. The axially movable variable aperture dual-field long-wave infrared zoom optical system of the present utility model has good imaging quality and small distortion, and can be applied to a 640×512×17μm high-resolution infrared detector. Description of the Drawings

[0018] Figure 1 It is a schematic diagram of the axially movable variable aperture dual-field long-wave infrared zoom optical system of the present utility model;

[0019] Figure 2 It is a three-dimensional model diagram of the wide field of view of the axially movable variable aperture dual-field long-wave infrared zoom optical system of the present utility model;

[0020] Figure 3 It is a three-dimensional model diagram of the narrow field of view of the axially movable variable aperture dual-field long-wave infrared zoom optical system of the present utility model;

[0021] Figure 4 It is an MTF diagram of the wide field of view @30 lp / mm of the axially movable variable aperture dual-field long-wave infrared zoom optical system of the present utility model;

[0022] Figure 5MTF graph of the narrow field of view of the axially movable aperture diaphragm dual-field long-wave infrared zoom optical system of the present utility model @ 30 lp / mm;

[0023] Figure 6 Spot diagram of the wide field of view of the axially movable aperture diaphragm dual-field long-wave infrared zoom optical system of the present utility model;

[0024] Figure 7 Spot diagram of the narrow field of view of the axially movable aperture diaphragm dual-field long-wave infrared zoom optical system of the present utility model;

[0025] Figure 8 Distortion diagram of the wide field of view of the axially movable aperture diaphragm dual-field long-wave infrared zoom optical system of the present utility model;

[0026] Figure 9 Distortion diagram of the narrow field of view of the axially movable aperture diaphragm dual-field long-wave infrared zoom optical system of the present utility model. Specific embodiments

[0027] The following uses specific embodiments to further illustrate the present utility model:

[0028] The present utility model discloses an axially movable aperture diaphragm dual-field long-wave infrared zoom optical system, which includes four parts: a first lens 1, a zoom lens 2, a rear lens group 1 3, and a focusing lens 4. The first lens 1, the zoom lens 2, the rear lens group 1 3, and the focusing lens 4 are arranged in sequence from the object side to the image side along the optical axis of the entire optical system.

[0029] When the zoom lens 2 moves towards the first lens 1, it is a wide field of view. When the zoom lens 2 moves towards the rear lens group 1 3, it is a narrow field of view. The zoom ratio of the wide and narrow fields of view is 3.

[0030] See Figure 1 , the first lens 1 is a meniscus positive lens with a focal length of f1, 90 mm < f1 < 100 mm; the zoom lens 2 is a double concave negative lens with a focal length of f2, -25 mm < f2 < -15 mm; the rear lens group 1 3 is a double convex positive lens with a focal length of f3, 35 mm < f3 < 45 mm; the focusing lens 4 is a meniscus positive lens with a focal length of f4, 50 mm < f4 < 60 mm.

[0031] In the optical system of the present utility model, when switching from the wide field of view to the narrow field of view, the aperture diaphragm changes from the front surface of the rear lens group 1 3 to the front surface of the first lens 1.

[0032] The optical system of the present utility model realizes the switching of the wide and narrow fields of view by moving the zoom lens 2 back and forth. The moving distance of the zoom lens 2 is small, and the field of view switching speed is fast.

[0033] For the optical system of the present utility model, the distance from the front surface of lens 1 to the image plane of detector FPA6 is 163 mm, which is relatively short. There is a detector protection window 5 in front of the detector FPA6.

[0034] For the optical system of the present utility model, it can achieve clear imaging of wide and narrow fields of view in the wide temperature range of -40°C to 60°C by moving the focusing lens 4.

[0035] The optical system of the present utility model has good imaging quality and small distortion, and is applicable to 640×512×17μm infrared detectors.

[0036] The optical system of the present utility model has few lenses, high transmittance, light weight, and is easy to process and align. It can be widely applied to many military and civilian fields such as warning, reconnaissance, forest fire prevention, etc.

[0037] See Figures 2 to 9 , from Figures 2 to 9 As can be seen from the MTF curve graph and the spot diagram shown in

[0038] For the parameters of the optical system of the present utility model, please refer to Table 1:

[0039] Table 1 Parameters of the axially movable variable aperture dual-field long-wave infrared zoom optical system of the present utility model

[0040]

[0041]

[0042] The aspheric surface satisfies the following expression:

[0043]

[0044] Table 2 Aspheric surface parameters

[0045] Aspherical k A B C D Lens 1 0 -8.626e-009 -6.233e-010 2.790e-017 0 Zoom lens 0 -4.036e-007 1.719e-009 -7.350e-012 7.538e-016

[0046] The above are only the preferred embodiments of the present utility model, and are not used to limit the protection scope of the present utility model. Therefore, any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present utility model shall be included in the protection scope of the present utility model.

Claims

1. An axially movable variable aperture dual-field long-wave infrared zoom optical system, characterized in that: The optical system includes a first lens (1), a zoom lens (2), a first rear lens group (3), and a focusing lens (4). The first lens (1), the zoom lens (2), the first rear lens group (3), and the focusing lens (4) are arranged in sequence from the object side to the image side. When the zoom lens (2) moves towards the first lens (1), it is a wide field of view, and when the zoom lens (2) moves towards the first rear lens group (3), it is a narrow field of view.

2. According to claim 1, the axially movable variable aperture dual-field long-wave infrared zoom optical system is characterized in that: When the optical system switches from the wide field of view to the narrow field of view, the aperture changes from the front surface of the first rear lens group (3) to the front surface of the first lens (1).

3. The axially movable variable aperture dual-field long-wave infrared zoom optical system according to claim 1, characterized in that: The magnification ratio of the wide and narrow fields of view of the optical system is 3.

4. The axially movable variable aperture dual-field long-wave infrared zoom optical system according to claim 1, characterized in that: The first lens (1) of the optical system is a meniscus positive lens, the zoom lens (2) is a double concave negative lens, the first rear lens group (3) is a double convex positive lens, and the focusing lens (4) is a meniscus positive lens.

5. The axially movable variable aperture dual-field long-wave infrared zoom optical system according to claim 4, characterized in that: The focal length of the first lens (1) is f1, where 90mm < f1 < 100mm; the focal length of the zoom lens (2) is f2, where -25mm < f2 < -15mm; the focal length of the first rear lens group (3) is f3, where 35mm < f3 < 45mm; the focal length of the focusing lens (4) is f4, where 50mm < f4 < 60mm.

6. The axially movable variable aperture dual-field long-wave infrared zoom optical system according to claim 1, characterized in that: For the optical system, the distance from the front surface of the first lens (1) to the image plane is 163mm.

7. The axially movable variable aperture dual-field long-wave infrared zoom optical system according to claim 1, characterized in that: The optical system can achieve clear imaging of the wide and narrow fields of view in a wide temperature range of -40°C to 60°C by moving the focusing lens (4).

Images