Infrared lens and imaging device

Abstract

This invention provides an imaging device, including an infrared lens and a detector for receiving the image captured by the infrared lens. The infrared lens has an effective focal length of 35mm and includes a first lens and a second lens arranged sequentially along the optical axis. Both the first and second lenses are meniscus lenses, and their convex surfaces face the object side. The second lens is movable along the optical axis, and the air gap between the first and second lenses is 26.79~27.09mm. Using the above-described infrared lens, imaging at different distances can be achieved by adjusting the position of the second lens along the optical axis. Furthermore, it only requires two lenses, resulting in a simple structure and lower cost. Additionally, the second lens has a travel distance of 0.3mm, which is moderate and convenient for adjustment using a knob.

Description

Technical Field

[0001] This invention belongs to the field of optical technology, specifically relating to an infrared lens and imaging device. Background Technology

[0002] Infrared imaging technology identifies targets and obtains their image information by detecting the temperature difference between the target and the background. Because infrared systems have advantages such as strong camouflage detection capabilities, uninterrupted day and night operation, passive imaging, and resistance to interference, they are widely used in many fields such as military anti-camouflage and concealment, space remote sensing, medical diagnosis, and security systems.

[0003] To enable a single lens to clearly see both near and far objects, existing imaging devices typically employ zoom lenses. However, zoom lenses require a large number of lenses, resulting in higher costs. Summary of the Invention

[0004] The technical problem to be solved by the present invention is that the cost of using a zoom lens to see both near and far scenes is relatively high. In order to solve the above technical problem, an infrared lens and imaging device with a lower cost that can see both near and far scenes are provided.

[0005] The technical solution proposed in this invention is as follows:

[0006] An infrared lens with an effective focal length of 35mm, the infrared lens includes a first lens and a second lens arranged sequentially along the optical axis transmission direction, the first lens and the second lens are both meniscus lenses, and the convex surfaces of both lenses face the object side.

[0007] The second lens is movable along the optical axis, and the air gap between the first lens and the second lens is 26.79~27.09mm.

[0008] Furthermore, the first lens has a center thickness of 4 mm, an object-side radius of curvature of 34.2 mm, and an image-side radius of curvature of 40.63 mm. The second lens has a center thickness of 3 mm, an object-side radius of curvature of 62 mm, and an image-side radius of curvature of 106.05 mm.

[0009] Furthermore, the object-side surface and image-side surface of the first lens, as well as the object-side surface of the second lens, are all aspherical surfaces and satisfy the aspherical formula:

[0010]

[0011] Where Z is the distance vector from the vertex of the aspherical surface at a height r along the optical axis; c = 1 / R; R is the paraxial curvature fitting radius of the mirror; k is the conic coefficient; A, B, C, D, and E are higher-order aspherical coefficients.

[0012] Furthermore, the infrared lens operates in the wavelength range of 8μm to 12μm and has an F-number of 1.0.

[0013] Furthermore, the horizontal field of view of the infrared lens is 12.52°.

[0014] Furthermore, both the first lens and the second lens are coated with a diamond-like carbon film.

[0015] An imaging device includes an infrared lens as described above and a detector for receiving images from the infrared lens.

[0016] Furthermore, the detector includes a protective window and a detector focal plane array arranged sequentially, the air gap between the second lens and the protective window is 9.11~9.41mm, and the air gap between the protective window and the detector focal plane array is 10.21mm.

[0017] Furthermore, the detector is an uncooled infrared detector with a resolution of 640×512 and a pixel size of 12μm.

[0018] Furthermore, the total length of the optical system of the imaging device is 45.5 mm, and the maximum aperture is 40 mm.

[0019] Using the aforementioned infrared lens, imaging at different distances can be achieved by adjusting the position of the second lens along the optical axis. Furthermore, with only two lenses, the structure is simple and cost-effective. Additionally, the second lens has a travel distance of 0.3mm, which is moderate and convenient for adjustment using a knob. Attached Figure Description

[0020] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0021] Figure 1 This is a schematic diagram of the structure of an imaging device provided in an embodiment of the present invention;

[0022] Figure 2 for Figure 1 The optical path diagram of the imaging device is shown below;

[0023] Figure 3 MTF image of the infrared lens provided in this application at 20°C;

[0024] Figure 4 MTF diagram of the infrared lens provided in this application at -40℃;

[0025] Figure 5MTF diagram of the infrared lens provided in this application at 60°C.

[0026] Label Explanation:

[0027] 110, First lens; 120, Second lens; 210, Protective window; 220, Detector focal plane array. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] This invention provides an imaging device, including an infrared lens and a detector for receiving the image captured by the infrared lens. The total length of the optical system of the imaging device is 45.5 mm; the effective focal length of the infrared lens is 35 mm, and the horizontal field of view is 12.52°; the detector is an uncooled infrared detector with a resolution of 640×512 and a pixel size of 12 μm.

[0030] Please see Figure 1 The infrared lens includes a first lens 110 and a second lens 120 arranged sequentially along the optical axis transmission direction. Both the first lens 110 and the second lens 120 are meniscus lenses, and their convex surfaces both face the object side. The second lens 120 is movable along the optical axis direction, and the air gap between the first lens 110 and the second lens 120 is 26.79~27.09mm.

[0031] Using the aforementioned infrared lens, imaging at different distances can be achieved by adjusting the position of the second lens 120 along the optical axis. Furthermore, with only two lenses, the structure is simple and cost-effective. Additionally, the second lens 120 has a travel distance of 0.3mm, which is moderate and convenient for adjustment using a knob.

[0032] It should be noted that the detector includes a protective window 210 and a detector focal plane array 220 arranged sequentially, i.e. Figure 2 As shown, the light beam passes through the first lens 110 and the second lens 120 sequentially from left to right, and then images onto the detector focal plane array 220 through the protective window 210. The air gap between the second lens 120 and the protective window 210 is 9.11~9.41 mm; the thickness of the protective window 210 is 0.7 mm; and the air gap between the protective window 210 and the detector focal plane array 220 is 2.16 mm.

[0033] As shown in Table 1, as an example, the center thickness of the first lens 110 is 4 mm, the object-side radius of curvature is 34.2 mm, and the image-side radius of curvature is 40.63 mm; the center thickness of the second lens 120 is 3 mm, the object-side radius of curvature is 62 mm, and the image-side radius of curvature is 106.05 mm. It can be determined that, along the optical axis from left to right, the left side is the object side, and the right side is the image side. For example, the S1 surface of the first lens 110 is the object-side surface, and the S2 surface is the image-side surface. Other lenses will not be described in detail here.

[0034] Table 1

[0035]

[0036] In one embodiment, the object-side surface and image-side surface of the first lens 110, and the object-side surface of the second lens 120 are all aspherical surfaces, and satisfy the aspherical formula:

[0037]

[0038] Where Z is the distance vector from the vertex of the aspherical surface at a height r along the optical axis; c = 1 / R; R is the paraxial curvature fitting radius of the mirror; k is the conic coefficient; A, B, C, D, and E are higher-order aspherical coefficients. The aspherical data of the first lens 1101 are shown in Table 2.

[0039] Table 2

[0040]

[0041] In one embodiment, the imaging device has a maximum aperture of 40 mm, and the maximum aperture is located at the first lens 110.

[0042] In one embodiment, the surfaces of both the first lens 110 and the second lens 120 are coated with a diamond-like carbon film to enhance hardness and wear resistance while ensuring light transmittance.

[0043] Figures 3 to 5 The images show the MTF (Mean Transformation Factor) of the infrared lens at 20℃, -40℃, and 60℃. In the MTF images, the horizontal axis represents different spatial frequencies, and the vertical axis represents the modulation index. It can be seen that the MTF is close to the diffraction limit, the root mean square diameter of the diffuse spot is smaller than the Airy disk diameter, and the image quality is good.

[0044] In summary, it should be noted that the infrared lens in this invention operates in the 8μm~12μm wavelength range, has an F-number of 1.0, and the detector used to receive the image from this lens has a resolution of 640×512 and a pixel size of 12μm. The infrared lens provided by this invention can clearly see both near and far scenes and has advantages such as fewer lenses, lighter weight, and lower cost. Furthermore, by using a second lens 120 to move and focus, the imaging distance is greater than or equal to 2m, solving the defocusing problem and compensating for defocusing caused by temperature changes.

[0045] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An infrared lens, characterized in that, The effective focal length is 35mm. The infrared lens consists of a first lens and a second lens arranged sequentially along the optical axis transmission direction. Both the first lens and the second lens are meniscus lenses, and their convex surfaces face the object side. The second lens is movable along the optical axis, and the air gap between the first lens and the second lens is 26.79~27.09mm. The first lens has a center thickness of 4 mm, an object-side radius of curvature of 34.2 mm, and an image-side radius of curvature of 40.63 mm. The second lens has a center thickness of 3 mm, an object-side radius of curvature of 62 mm, and an image-side radius of curvature of 106.05 mm.

2. The infrared lens according to claim 1, characterized in that, The object-side and image-side surfaces of the first lens, as well as the object-side surface of the second lens, are all aspherical and satisfy the aspherical formula: Where Z is the distance vector from the vertex of the aspherical surface at a height r along the optical axis; c = 1 / R; R is the paraxial curvature fitting radius of the mirror; k is the conic coefficient; A, B, C, D, and E are higher-order aspherical coefficients.

3. The infrared lens according to claim 1, characterized in that, The infrared lens operates in the wavelength range of 8μm to 12μm and has an F-number of 1.

0.

4. The infrared lens according to claim 1, characterized in that, The horizontal field of view of the infrared lens is 12.52°.

5. The infrared lens according to claim 1, characterized in that, Both the first lens and the second lens are coated with a diamond-like carbon film.

6. An imaging device, characterized in that, It includes the infrared lens as described in any one of claims 1 to 5 and a detector for receiving the image formed by the infrared lens.

7. The imaging apparatus according to claim 6, characterized in that, The detector includes a protective window and a detector focal plane array arranged sequentially. The air gap between the second lens and the protective window is 9.11~9.41mm, and the air gap between the protective window and the detector focal plane array is 10.21mm.

8. The imaging apparatus according to claim 6, characterized in that, The detector is an uncooled infrared detector with a resolution of 640×512 and a pixel size of 12μm.

9. The imaging apparatus according to claim 8, characterized in that, The total length of the optical system of the imaging device is 45.5 mm, and the maximum aperture is 40 mm.

Images