Infrared lens and imaging device

Abstract

The utility model discloses an infrared lens, the focal length is 15mm, the infrared lens comprises a first lens, a diaphragm and a second lens which are sequentially arranged along the optical axis transmission direction, both the first lens and the second lens are positive lenses, the air gap between the first lens and the diaphragm is 2.6 mm, and the air gap between the second lens and the diaphragm is 2.6 mm. And the air interval between the diaphragm and the second lens is 6.48 mm. The infrared lens provided by the utility model has the advantages of large target surface and clear imaging.

Description

Technical Field

[0001] This application belongs to the field of infrared optical technology, and particularly relates to an infrared lens and an imaging device. Background Art

[0002] Infrared imaging technology identifies targets and obtains image information of targets by detecting the temperature difference between the target and the background. Due to the advantages of strong camouflage recognition ability, non-stop day and night, passive imaging, and being not easily interfered, the infrared system is widely used in many aspects such as military anti-camouflage shielding, space remote sensing, medical diagnosis, and security systems. The existing infrared lenses applied to security systems generally have low resolution. In order to obtain clear images, it is usually necessary to increase the number of lenses. Therefore, it is necessary to develop an infrared lens with a large target surface and clear imaging. Utility Model Content

[0003] In order to solve the above problems, the present utility model provides an infrared lens and an imaging device with a large target surface and clear imaging.

[0004] The technical solution proposed in this application is as follows:

[0005] An infrared lens with a focal length of 15 mm, the infrared lens includes a first lens, a diaphragm, and a second lens arranged in sequence along the optical axis transmission direction. Both the first lens and the second lens are positive lenses. The air gap between the first lens and the diaphragm is 2.6 mm, and the air gap between the diaphragm and the second lens is 6.48 mm.

[0006] Further, the central thickness of the first lens is 3.3 mm, the curvature radius of the object side surface is 14 mm, and the curvature radius of the image side surface is 12 mm; the central thickness of the second lens is 2.5 mm, the curvature radius of the object side surface is 127.27 mm, and the curvature radius of the image side surface is 53.94 mm.

[0007] Further, both the first lens and the second lens are germanium single crystals.

[0008] Further, both the object side surface and the image side surface of the first lens are aspherical surfaces and satisfy the aspherical formula:

[0009]

[0010] Where Z is the distance sagitta from the vertex of the aspherical surface when the aspherical surface is at a position with a height r along the optical axis direction; c = 1 / R; R is the paraxial curvature fitting radius of the mirror surface; k is the conic coefficient; A, B, C, D, and E are high-order aspherical coefficients.

[0011] Further, the working wavelength band of the lens is 8 μm - 12 μm, and the F number is 1.0.

[0012] Further, the lens further includes an outer lens barrel, a main lens barrel, a first sleeve, an adapter, and a second sleeve. The first lens and the lens are both disposed within the main lens barrel, the main lens barrel is disposed within the outer lens barrel, the first sleeve, the adapter, and the second sleeve are disposed between the main lens barrel and the outer lens barrel, and the first sleeve is sleeved outside the main lens barrel, the adapter is sleeved outside the first sleeve, and the second sleeve is sleeved outside the adapter;

[0013] Wherein, the expansion coefficients of the first sleeve and the second sleeve are higher than the expansion coefficient of the adapter.

[0014] Further, the lens further includes an intermediate lens barrel and an elastic member. The intermediate lens barrel is disposed between the outer lens barrel and the main lens barrel, the first sleeve, the adapter, and the second sleeve are disposed between the main lens barrel and the intermediate lens barrel, and the elastic member is disposed between the intermediate lens barrel and the main lens barrel for providing a force that causes the main lens barrel to have a tendency to move toward the object side along the optical axis direction.

[0015] An imaging device includes the infrared lens as described above and a detector for receiving the image formed by the infrared lens.

[0016] Further, the detector includes a protection window and a detector focal plane array arranged in sequence, and the air gap between the second lens and the protection window is 9.29 mm.

[0017] Further, the number of pixels of the detector is 640×512, and the pixel size is 12 μm.

[0018] The infrared lens provided by the present utility model has the advantages of a large target surface, clear imaging, and a small number of lens elements. Description of the Drawings

[0019] The drawings are used to provide a further understanding of the present application, and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the present application, and do not constitute a limitation to the present application.

[0020] Figure 1 It is a schematic structural diagram of an imaging device provided by an embodiment of the present application;

[0021] Figure 2 For Figure 1 The optical path diagram of the imaging device shown;

[0022] Figure 3 It is a spot diagram of an infrared lens provided by another embodiment of the present application;

[0023] Figure 4 It is an MTF diagram of an infrared lens provided by another embodiment of the present application;

[0024] Figure 5 Schematic structural diagram of an infrared lens provided in another embodiment of the present application.

[0025] Reference numeral description:

[0026] 1. First lens; 2. Diaphragm; 3. Second lens; 4. Protection window; 5. Detector focal plane array; 110. Outer lens barrel; 120. Main lens barrel; 121. Weight reduction hole; 130. First sleeve; 140. Adapter; 150. Second sleeve; 160. Intermediate lens barrel; 170. Elastic member. Specific implementation manner

[0027] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0028] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. is the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application.

[0029] The present utility model provides an imaging device, which includes an infrared lens and a detector for receiving the image formed by the lens. Among them, the focal length of the lens is 15 mm, and it has advantages such as a large target surface and clear imaging. Hereinafter, taking the lens applied to a detector with a resolution of 640×512 and 12 μm as an example, and the working wavelength band is 8 μm - 12 μm.

[0030] As Figure 1 shown, the lens includes a first lens 1, a diaphragm 2, and a second lens 3 arranged in sequence along the optical axis transmission direction. The air gap between the first lens 1 and the diaphragm 2 is 2.6 mm, and the air gap between the diaphragm 2 and the second lens 3 is 6.48 mm.

[0031] As Figure 2 shown, the light beam passes through the first lens 1, the diaphragm 2, and the second lens 3 in sequence from left to right, and then forms an image on the detector focal plane array 5 through the protection window 4.

[0032] As shown in Table 1, as an example, the center thickness of the first lens 1 is 3.3mm, the object side curvature radius is 14mm, and the image side curvature radius is 12mm; the center thickness of the second lens 3 is 2.5mm, the object side curvature radius is 127.27mm, and the image side curvature radius is 53.94mm. It can be determined that from left to right along the optical axis, the left side is the object side and the right side is the image side. For example, the S1 surface of the first lens 1 is the object side surface, and the S2 surface is the image side surface. Other lenses are not described here.

[0033] Furthermore, the air gap between the second lens 3 and the protection window 4 is 9.29 mm.

[0034] Table 1

[0035]

[0036] In one embodiment, both the object side surface and the image side surface of the first lens 1 are aspherical surfaces and satisfy the aspherical surface formula:

[0037]

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

[0039] Table 2

[0040]

[0041] Figure 3 and Figure 4 These are the spot diagram and MTF diagram of the infrared lens. In the MTF diagram, the horizontal axis represents different spatial frequencies, and the vertical axis represents the modulation degree. 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.

[0042] In summary, it should be noted that the working band of the infrared lens in the utility model is 8μm-12μm, the F number is 1.0, the resolution of the detector used to receive the image formed by the lens is 640×512, and the pixel size is 12μm. The lens provided by the utility model has the advantages of large target surface, clear imaging, and small number of lenses.

[0043] See also Figure 5, the lens further includes an outer lens barrel 110, a main lens barrel 120, a first sleeve 130, an adapter 140, and a second sleeve 150. The first lens 1, the diaphragm 2, and the second lens 3 are all disposed within the main lens barrel 120 and are fixed by retaining rings. The main lens barrel 120 is disposed within the outer lens barrel 110, and the first sleeve 130, the adapter 140, and the second sleeve 150 are disposed between the main lens barrel 120 and the outer lens barrel 110. The first sleeve 130 is sleeved outside the main lens barrel 120, the adapter 140 is sleeved outside the first sleeve 130, and the second sleeve 150 is sleeved outside the adapter 140.

[0044] Among them, the expansion coefficients of the first sleeve 130 and the second sleeve 150 are higher than that of the adapter 140. Thus, by adopting structures with different expansion coefficients, when the temperature changes, the first sleeve 130, the adapter 140, and the second sleeve 150 expand and contract, driving the main lens barrel 120 and the first lens 1 and the second lens 3 on the main lens barrel 120 to move along the optical axis direction, thereby compensating for the image plane shift caused by temperature. Preferably, the first sleeve 130 and the second sleeve 150 are plastic parts with a high expansion coefficient, and the adapter 140 is a metal part with a low expansion coefficient.

[0045] In one embodiment, the lens further includes an intermediate lens barrel 160 and an elastic member 170. The intermediate lens barrel 160 is disposed between the outer lens barrel 110 and the main lens barrel 120. The first sleeve 130, the adapter 140, and the second sleeve 150 are disposed between the main lens barrel 120 and the intermediate lens barrel 160. The elastic member 170 is disposed between the intermediate lens barrel 160 and the main lens barrel 120 and is used to provide a force that causes the main lens barrel 120 to move along the optical axis direction towards the object side. Thus, it can cooperate with the first sleeve 130, the adapter 140, and the second sleeve 150 to achieve the movement of the main lens barrel 120 along the optical axis direction to compensate for the image plane shift caused by temperature. Preferably, the elastic member 170 is a wave spring.

[0046] It should be noted that the above-mentioned first sleeve 130, adapter 140, and second sleeve 150 constitute a mechanical athermalization component, one end of which abuts against the main lens barrel 120, Figure 5 wherein the right end of the first sleeve 130 abuts against the main lens barrel 120, and the other end of this component abuts against the intermediate lens barrel 160, Figure 5 wherein the left end of the second sleeve 150 abuts against the intermediate lens barrel 160. When the image plane shifts due to temperature, the mechanical athermalization component generates compensation.

[0047] In one embodiment, a weight reduction hole 121 is further formed inside the main lens barrel 120, and the weight reduction hole 121 is located between the first lens 1 and the second lens 3.

[0048] Although embodiments of the present application have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present application. The scope of the present application is defined by the appended claims and their equivalents.

Claims

1. An infrared lens, characterized in that, The focal length is 15 mm. The infrared lens includes a first lens, a diaphragm, and a second lens arranged in sequence along the optical axis transmission direction. Both the first lens and the second lens are positive lenses. The air gap between the first lens and the diaphragm is 2.6 mm, and the air gap between the diaphragm and the second lens is 6.48 mm.

2. The infrared lens according to claim 1, wherein The central thickness of the first lens is 3.3 mm, the curvature radius of the object side surface is 14 mm, and the curvature radius of the image side surface is 12 mm; the central thickness of the second lens is 2.5 mm, the curvature radius of the object side surface is 127.27 mm, and the curvature radius of the image side surface is 53.94 mm.

3. The infrared lens according to claim 1, wherein Both the first lens and the second lens are made of germanium single crystal.

4. The infrared lens according to claim 1, characterized in that Both the object side surface and the image side surface of the first lens are aspherical surfaces and satisfy the aspherical formula: Where Z is the distance sagitta from the vertex of the aspherical surface when the aspherical surface is at the position of height r along the optical axis direction; c = 1 / R; R is the paraxial curvature fitting radius of the mirror surface; k is the conic coefficient; A, B, C, D, E are high-order aspherical coefficients.

5. The infrared lens according to claim 1, characterized in that, The working wavelength band of the lens is 8 μm - 12 μm, and the F number is 1.

0.

6. The infrared lens according to claim 1, wherein The lens further includes an outer lens barrel, a main lens barrel, a first sleeve, an adapter, and a second sleeve. The first lens and the lens are both arranged in the main lens barrel, the main lens barrel is arranged in the outer lens barrel, the first sleeve, the adapter, and the second sleeve are arranged between the main lens barrel and the outer lens barrel, and the first sleeve is sleeved outside the main lens barrel, the adapter is sleeved outside the first sleeve, and the second sleeve is sleeved outside the adapter; Wherein, the expansion coefficients of the first sleeve and the second sleeve are higher than the expansion coefficient of the adapter.

7. The infrared lens according to claim 6, characterized in that, The lens further includes an intermediate lens barrel and an elastic member. The intermediate lens barrel is arranged between the outer lens barrel and the main lens barrel, the first sleeve, the adapter, and the second sleeve are arranged between the main lens barrel and the intermediate lens barrel, and the elastic member is arranged between the intermediate lens barrel and the main lens barrel to provide a force for making the main lens barrel have a tendency to move towards the object side along the optical axis direction.

8. An imaging device, characterized in that, It includes the infrared lens according to any one of claims 1 - 7 and a detector for receiving the image formed by the infrared lens.

9. The imaging device according to claim 8, wherein The detector includes a protection window and a detector focal plane array arranged in sequence. The air gap between the second lens and the protection window is 9.29 mm.

10. The imaging device according to claim 8, characterized in that, The number of pixels of the detector is 640 × 512, and the pixel size is 12 μm.

Images