Medium-long wave double-color composite infrared lens

Abstract

The invention discloses a medium-long wave double-color composite infrared lens, the applicable spectral range of the lens is 3-5 [mu] m and 8-12 [mu] m, and the lens comprises a first lens, a second lens, a third lens, a fourth lens and a fifth lens which are sequentially arranged along the optical axis transmission direction; the first lens and the fourth lens are meniscus positive lenses with convex surfaces facing the object side, the second lens is a plano-concave negative lens, and the third lens and the fifth lens are meniscus negative lenses with convex surfaces facing the object side. The lens provided by the invention is simple in structure, large in target surface, clear in imaging, capable of being applied to a medium-long wave spectral range, and large in application range.

Description

Technical Field

[0001] The present application belongs to the technical field of infrared optical equipment, and specifically relates to a medium- and long-wave dual-color composite infrared lens. Background Art

[0002] With the development of science and technology, infrared imaging technology has been widely used in defense, industry, medical treatment, power detection and other fields, with broad application prospects and use value. Infrared detection can be done without contacting the detected target, which can be a high-temperature object or a very low-temperature object; infrared instruments can detect very small temperature differences on the surface of objects. According to the abnormal surface temperature of the object, the abnormal points of the object can be detected, which is convenient for investigation. However, the existing short-range detection instruments are usually long-wave detection, which has a small scope of application. Summary of the invention

[0003] Based on this, the present application provides a medium- and long-wave dual-color composite infrared lens with a wide range of applications.

[0004] The technical solution proposed in this application is: A medium- and long-wave dual-color composite infrared lens, the applicable spectral range of the lens is: 3~5μm and 8~12μm, the lens comprises a first lens, a second lens, a third lens, a fourth lens and a fifth lens arranged in sequence along the transmission direction of the optical axis; the first lens and the fourth lens are both positive meniscus lenses with convex surfaces facing the object side, the second lens is a plano-concave negative lens, and the third lens and the fifth lens are both negative meniscus lenses with convex surfaces facing the object side.

[0005] Furthermore, the air gap between the object plane and the first lens is 720 mm, the air gap between the first lens and the second lens is 5.488 mm, the air gap between the second lens and the third lens is 6.607 mm, the air gap between the third lens and the fourth lens is 177.889 mm, the air gap between the fourth lens and the fifth lens is 6.416 mm, and the air gap between the fifth lens and the image plane is 25 mm.

[0006] Further, the center thickness of the first lens is 32.6mm, the object side curvature radius is 163.732mm, and the image side curvature radius is 7304.96mm; the center thickness of the second lens is 15mm, the object side is a plane, and the image side curvature radius is 1201.752mm; the center thickness of the third lens is 15mm, the object side curvature radius is 3294.154mm, and the image side curvature radius is 185.775mm; the center thickness of the fourth lens is 21mm, the object side curvature radius is 71.381mm, and the image side curvature radius is 190mm; the center thickness of the fifth lens is 20mm, the object side curvature radius is 90mm, and the image side curvature radius is 47.953mm.

[0007] Furthermore, it also includes an aperture, which is arranged between the object plane and the first lens.

[0008] Furthermore, the first lens and the lens meet the following condition: 0<f1 / f<1, wherein f1 is the effective focal length of the first lens, and f is the effective focal length of the lens.

[0009] Furthermore, the fifth lens and the lens satisfy the following condition: 0<f5 / f<1, wherein f5 is the effective focal length of the fifth lens, and f is the effective focal length of the lens.

[0010] Furthermore, the focal length of the lens is 170 mm and the field of view angle is 8°.

[0011] Furthermore, the entrance pupil diameter of the lens is 70 mm.

[0012] Furthermore, the material of the first lens is CVD zinc selenide, the materials of the second lens and the fifth lens are both germanium single crystal, the material of the third lens is CVD zinc sulfide, and the material of the fourth lens is chalcogenide glass.

[0013] The lens provided in the present application has a simple structure, a large target surface, clear imaging, and is applicable to the medium and long wave spectral range, with a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The accompanying drawings are used to provide further understanding of the present application and constitute a part of the specification. They are used to explain the present application together with the embodiments of the present application and do not constitute a limitation of the present application.

[0015] Figure 1 A schematic diagram of the structure of a medium- and long-wave dual-color composite infrared lens provided in one embodiment of the present application; Figure 2 This is an MTF diagram of a medium- and long-wave dual-color composite infrared lens provided in an embodiment of the present application at a wavelength of 3 to 5 μm; Figure 3 This is a point diagram of a medium- and long-wave dual-color composite infrared lens provided in an embodiment of the present application at a wavelength of 3 to 5 μm; Figure 4 This is an MTF diagram of a medium- and long-wave dual-color composite infrared lens provided in an embodiment of the present application at a wavelength of 8 to 12 μm; Figure 5 This is a point diagram of a medium- and long-wave dual-color composite infrared lens provided in an embodiment of the present application at a wavelength of 8-12 μm.

[0016] Description of labels: 11. Object plane; 12. First lens; 13. Second lens; 14. Third lens; 15. Fourth lens; 16. Fifth lens; 17. Image plane. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0018] An embodiment of the present application provides a medium- and long-wave dual-color composite infrared lens, the focal length of which is 170 mm, the applicable spectral range is 3-5 μm and 8-12 μm, and the field of view is 8°. At the same time, the lens adopts a large aperture design, and the entrance pupil diameter is 70 mm.

[0019] See also Figure 1 The lens comprises a first lens 12, a second lens 13, a third lens 14, a fourth lens 15 and a fifth lens 16 which are arranged in sequence along the transmission direction of the optical axis. The first lens 12 and the fourth lens 15 are both positive meniscus lenses with convex surfaces facing the object side, the second lens 13 is a plano-concave negative lens, and the third lens 14 and the fifth lens 16 are both negative meniscus lenses with convex surfaces facing the object side.

[0020] As shown in Table 1, as an example, the air interval between the object plane 11 and the first lens 12 is 720 mm, the air interval between the first lens 12 and the second lens 13 is 5.488 mm, the air interval between the second lens 13 and the third lens 14 is 6.607 mm, the air interval between the third lens 14 and the fourth lens 15 is 177.889 mm, the air interval between the fourth lens 15 and the fifth lens 16 is 6.416 mm, and the air interval between the fifth lens 16 and the image plane 17 is 25 mm. It can be understood that the above-mentioned air intervals are air intervals on the optical axis.

[0021] Further, the center thickness of the first lens 12 is 32.6 mm, the radius of curvature of the object side is 163.732 mm, and the radius of curvature of the image side is 7304.96 mm; the center thickness of the second lens 13 is 15 mm, the object side is a plane, and the radius of curvature of the image side is 1201.752 mm; the center thickness of the third lens 14 is 15 mm, the radius of curvature of the object side is 3294.154 mm, and the radius of curvature of the image side is 185.775 mm; the center thickness of the fourth lens 15 is 21 mm, the radius of curvature of the object side is 71.381 mm, and the radius of curvature of the image side is 190 mm; the center thickness of the fifth lens 16 is 20 mm, the radius of curvature of the object side is 90 mm, and the radius of curvature of the image side is 47.953 mm.

[0022] It is understandable that in Figure 1 In the embodiment shown, the optical axis transmission direction is from left to right, the left side of the lens is the object side, and the right side is the image side, such as the S1 surface of the first lens 12 is the object side surface, and the S2 surface is the image side surface. Other lenses are not described in detail.

[0023] In one embodiment, the lens further includes an aperture stop, which is disposed between the object plane 11 and the first lens 12 .

[0024] In one embodiment, the first lens 12, the fifth lens 16 and the lens meet the following conditions: 0<f1 / f<1, 0<f5 / f<1; wherein f is the effective focal length of the lens, f1 is the effective focal length of the first lens 12 , and f5 is the effective focal length of the fifth lens 16 .

[0025] Table 1 Component parameters As shown in Table 1, the material of the first lens 12 is CVD (Chemical Vapor Deposition) zinc selenide, the materials of the second lens 13 and the fifth lens 16 are both germanium single crystals, the material of the third lens 14 is CVD zinc sulfide, and the material of the fourth lens 15 is chalcogenide glass. It should be noted that the above lenses are all made of domestic optical materials. At the same time, in a specific embodiment, the fourth lens 15 is made of IRG207 material.

[0026] It can be further determined from Table 1 that the image side surfaces of the third lens 14, the fourth lens 15 and the fifth lens 16 are all aspherical surfaces, and all aspherical surfaces satisfy the aspherical surface formula: Among them, z represents the distance of the surface from the vertex of the surface in the direction of the optical axis, c represents the curvature of the vertex of the surface, K represents the quadratic surface coefficient, h represents the distance from the optical axis to the surface, and B, C, D, E and F represent the fourth-order, sixth-order, eighth-order, tenth-order and twelfth-order surface coefficients respectively. At the same time, the aspherical data of each lens are shown in Table 2.

[0027] Table 2 Aspheric surface data Figure 2 and Figure 3 They are the MTF diagram and point diagram of the medium- and long-wave dual-color composite infrared lens at a wavelength of 3~5μm; Figure 4 and Figure 5 These are the MTF diagram and point diagram of the medium- and long-wave dual-color composite infrared lens at wavelengths of 8 to 12 μm. In the MTF diagram, the horizontal axis represents different spatial frequencies, and the vertical axis represents the modulation degree. Combined with the drawings, it can be seen that the lens corrects various aberrations in each band, so that both the center and the edge of the field of view have sufficient resolution.

[0028] In summary, the medium- and long-wave dual-color composite infrared lens provided by the present application has an operating band of 3-5μm and 8-12μm; a focal length of f=170mm, and a field of view of 8°. The lens provided by the present application has a simple structure, a large target surface, and clear imaging, and can be applied to the medium- and long-wave spectrum range, with a wide range of applications.

[0029] Although the embodiments of the present application have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A medium- and long-wave dual-color composite infrared lens, characterized in that: The applicable spectral range of the lens is: 3~5μm and 8~12μm. The lens includes a first lens, a second lens, a third lens, a fourth lens and a fifth lens which are sequentially arranged along the transmission direction of the optical axis; the first lens and the fourth lens are both positive meniscus lenses with convex surfaces facing the object side, the second lens is a plano-concave negative lens, and the third lens and the fifth lens are both negative meniscus lenses with convex surfaces facing the object side.

2. The medium- and long-wave dual-color composite infrared lens according to claim 1, characterized in that: The air gap between the object plane and the first lens is 720 mm, the air gap between the first lens and the second lens is 5.488 mm, the air gap between the second lens and the third lens is 6.607 mm, the air gap between the third lens and the fourth lens is 177.889 mm, the air gap between the fourth lens and the fifth lens is 6.416 mm, and the air gap between the fifth lens and the image plane is 25 mm.

3. The medium- and long-wave dual-color composite infrared lens according to claim 1, characterized in that: The center thickness of the first lens is 32.6mm, the radius of curvature of the object side is 163.732mm, and the radius of curvature of the image side is 7304.96mm; the center thickness of the second lens is 15mm, the object side is flat, and the radius of curvature of the image side is 1201.752mm; the center thickness of the third lens is 15mm, the radius of curvature of the object side is 3294.154mm, and the radius of curvature of the image side is 185.775mm; the center thickness of the fourth lens is 21mm, the radius of curvature of the object side is 71.381mm, and the radius of curvature of the image side is 190mm; the center thickness of the fifth lens is 20mm, the radius of curvature of the object side is 90mm, and the radius of curvature of the image side is 47.953mm.

4. The medium- and long-wave dual-color composite infrared lens according to claim 1, characterized in that: Also included is an aperture stop, which is disposed between the object plane and the first lens.

5. The medium- and long-wave dual-color composite infrared lens according to claim 1, characterized in that: The first lens and the lens meet the following condition: 0<f1 / f<1, wherein f1 is the effective focal length of the first lens, and f is the effective focal length of the lens.

6. The medium- and long-wave dual-color composite infrared lens according to claim 1, characterized in that: The fifth lens and the lens meet the following condition: 0<f5 / f<1, wherein f5 is the effective focal length of the fifth lens, and f is the effective focal length of the lens.

7. The medium- and long-wave dual-color composite infrared lens according to claim 1, characterized in that: The focal length of the lens is 170 mm and the field of view angle is 8°.

8. The medium- and long-wave dual-color composite infrared lens according to claim 1, characterized in that: The entrance pupil diameter of the lens is 70 mm.

9. The medium- and long-wave dual-color composite infrared lens according to claim 1, characterized in that: The material of the first lens is CVD zinc selenide, the materials of the second lens and the fifth lens are both germanium single crystal, the material of the third lens is CVD zinc sulfide, and the material of the fourth lens is chalcogenide glass.

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