Long wave continuous zoom infrared lens and imaging device

Abstract

This application provides an imaging device, including a long-wavelength continuous zoom infrared lens and a detector capable of receiving the image captured by the lens. The lens comprises a first lens, a second lens, a third lens, a fourth lens, and a fifth lens arranged sequentially along the optical axis from the object side to the image side. The first lens is a meniscus lens with its convex surface facing the object side; the second lens is a biconcave lens; the third lens is a biconvex lens; the fourth lens is a meniscus lens with its convex surface facing the image side; and the fifth lens is a biconvex lens. The second and third lenses are movable along the optical axis. The air gap between the first and second lenses is 10.2–22.87 mm, between the second and third lenses is 4.49–29.41 mm, between the third and fourth lenses is 5–17.25 mm, and between the fourth and fifth lenses is 18.69 mm. The focal length of the lens can be flexibly varied between 15–75 mm, accommodating both wide-area monitoring and long-distance identification. Furthermore, it exhibits excellent aberration correction during zooming, resulting in clear and stable imaging across the entire focal length range.

Description

Technical Field

[0001] This application belongs to the field of infrared optical equipment technology, specifically relating to a long-wavelength continuous zoom infrared lens and imaging device. Background Technology

[0002] Traditional fixed-focal-length optical systems can only provide a single focal length and field of view, and cannot expand the search range while maintaining image quality. The advantage of continuous zoom systems is that they maintain image continuity during field of view changes, and the target image remains clearly visible. They do not lose observation of the target during magnification changes, making them the optimal choice for modern observation systems to solve the problem of switching between large and small fields of view. Summary of the Invention

[0003] Based on this, this application provides a long-wavelength continuous zoom infrared lens and imaging device capable of continuous zoom.

[0004] The technical solution proposed in this application is as follows: A long-wavelength continuous zoom infrared lens with a focal length of 15-75mm is provided. The lens is composed of a first lens, a second lens, a third lens, a fourth lens, and a fifth lens arranged sequentially along the optical axis from the object side to the image side. The first lens is a meniscus lens with its convex surface facing the object side, the second lens is a biconcave lens, the third lens is a biconvex lens, the fourth lens is a meniscus lens with its convex surface facing the image side, and the fifth lens is a biconvex lens. The second and third lenses are movable along the optical axis. The air gap between the first and second lenses is 10.2-22.87 mm, the air gap between the second and third lenses is 4.49-29.41 mm, the air gap between the third and fourth lenses is 5-17.25 mm, and the air gap between the fourth and fifth lenses is 18.69 mm.

[0005] Further, the first lens has a center thickness of 6.5 mm, an object-side radius of curvature of 57.06 mm, and an image-side radius of curvature of 86.47 mm; the second lens has a center thickness of 1.8 mm, an object-side radius of curvature of -92.09 mm, and an image-side radius of curvature of 59.56 mm; the third lens has a center thickness of 4.5 mm, an object-side radius of curvature of 100.59 mm, and an image-side radius of curvature of -125.14 mm; the fourth lens has a center thickness of 1.6 mm, an object-side radius of curvature of -23.97 mm, and an image-side radius of curvature of -27.92 mm; and the fifth lens has a center thickness of 2.3 mm, an object-side radius of curvature of 94 mm, and an image-side radius of curvature of -1218.96 mm.

[0006] Furthermore, the lens also includes an aperture stop, which is disposed between the third lens and the fourth lens. The air gap between the third lens and the aperture stop is 2.5-14.75mm, and the air gap between the aperture stop and the fourth lens is 2.5mm.

[0007] Furthermore, the relative aperture of the lens is 1.2, and the operating wavelength is 8~12μm.

[0008] Furthermore, when the focal length of the lens is 15mm, the air gap between the first lens and the second lens is 10.2mm, the air gap between the second lens and the third lens is 29.41mm, and the air gap between the third lens and the fourth lens is 2.5mm; When the focal length of the lens is 75mm, the air gap between the first lens and the second lens is 22.87mm, the air gap between the second lens and the third lens is 4.49mm, and the air gap between the third lens and the fourth lens is 14.75mm.

[0009] Furthermore, the image-side surface of the first lens, the object-side surface of the second lens, the two side surfaces of the third lens, the object-side surface of the fourth lens, and the two side surfaces of the fifth lens are all aspherical surfaces, and satisfy the aspherical surface 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.

[0010] An imaging device includes the aforementioned long-wavelength continuous zoom infrared lens and a detector capable of receiving the image captured by the lens.

[0011] Furthermore, the detector has a resolution of 640*512 and a pixel size of 12μm.

[0012] Furthermore, the detector includes a protective window and an image plane arranged sequentially, the air gap between the fifth lens and the protective window is 10 mm, and the air gap between the protective window and the image plane is 1.5 mm.

[0013] The focal length of the lens provided in this application can be flexibly changed between 15-75mm, taking into account both wide-area monitoring and long-distance recognition. Moreover, the aberration correction is excellent during zooming, and the imaging is relatively clear and stable across the entire focal length. Attached Figure Description

[0014] The accompanying drawings are provided to further understand this application and form part of the specification. They are used together with the embodiments of this application to explain this application and do not constitute a limitation thereof.

[0015] Figure 1 This is a schematic diagram of the optical path structure of an imaging device provided in an embodiment of this application; Figure 2 A dot plot of the long-wave continuous zoom infrared lens provided in this application at a focal length of 15mm; Figure 3 MTF diagram of the long-wave continuous zoom infrared lens provided in this application at a focal length of 15mm; Figure 4 A dot plot of the long-wave continuous zoom infrared lens provided in this application at a focal length of 35mm; Figure 5 MTF diagram of the long-wave continuous zoom infrared lens provided in this application at a focal length of 35mm; Figure 6 A dot plot of the long-wave continuous zoom infrared lens provided in this application at a focal length of 55mm; Figure 7 MTF diagram of the long-wave continuous zoom infrared lens provided in this application at a focal length of 55mm; Figure 8 A dot plot of the long-wave continuous zoom infrared lens provided in this application at a focal length of 75mm; Figure 9 MTF diagram of the long-wave continuous zoom infrared lens provided in this application at a focal length of 75mm.

[0016] Label Explanation: 11. First lens; 12. Second lens; 13. Third lens; 14. Fourth lens; 15. Fifth lens; 16. Aperture stop; 21. Protective window; 22. Image plane. Detailed Implementation

[0017] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0018] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0019] This application provides an imaging device, including a long-wavelength continuous zoom infrared lens (hereinafter referred to as the lens) and a detector capable of receiving the image captured by the lens. The lens has a focal length of 15-75mm, a zoom ratio of 5x, a relative aperture of 1.2, and an operating wavelength of 8-12μm. The detector has a resolution of 640*512 and a pixel size of 12μm.

[0020] like Figure 1 As shown, in one embodiment, the lens comprises a first lens 11, a second lens 12, a third lens 13, a fourth lens 14, and a fifth lens 15 arranged sequentially along the optical axis from the object side to the image side. The first lens 11 is a meniscus lens with its convex surface facing the object side, the second lens 12 is a biconcave lens, the third lens 13 is a biconvex lens, the fourth lens 14 is a meniscus lens with its convex surface facing the image side, and the fifth lens 15 is a biconvex lens. The second lens 12 and the third lens 13 are movable along the optical axis, thereby achieving continuous zoom of the lens.

[0021] Furthermore, the detector includes a protective window 21 and an image plane 22 arranged sequentially, that is, the protective window 21 and the image plane 22 are arranged sequentially behind the lens along the optical axis. The light beam is imaged on the image plane 22 after passing through the lens and the protective window 21.

[0022] Please also refer to Table 1. In one embodiment, the air gap between the first lens 11 and the second lens 12 is 10.2-22.87 mm, the air gap between the second lens 12 and the third lens 13 is 4.49-29.41 mm, the air gap between the third lens 13 and the fourth lens 14 is 5-17.25 mm, and the air gap between the fourth lens 14 and the fifth lens 15 is 18.69 mm. Further, the lens also includes an aperture stop 16, which is disposed between the third lens 13 and the fourth lens 14. The air gap between the third lens 13 and the aperture stop 16 is 2.5-14.75 mm, and the air gap between the aperture stop 16 and the fourth lens 14 is 2.5 mm.

[0023] As an example, when the focal length of the lens is 15mm, the air gap between the first lens 11 and the second lens 12 is 10.2mm, the air gap between the second lens 12 and the third lens 13 is 29.41mm, and the air gap between the third lens 13 and the fourth lens 14 is 5mm; when the focal length of the lens is 75mm, the air gap between the first lens 11 and the second lens 12 is 22.87mm, the air gap between the second lens 12 and the third lens 13 is 4.49mm, and the air gap between the third lens 13 and the fourth lens 14 is 17.25mm.

[0024] Specifically, when the focal length of the lens is 15mm, the air gap between the third lens 13 and the aperture 16 is 2.5mm; when the focal length of the lens is 75mm, the air gap between the third lens 13 and the aperture 16 is 14.75mm.

[0025] In one embodiment, the first lens 11 has a center thickness of 6.5 mm, an object-side radius of curvature of 57.06 mm, and an image-side radius of curvature of 86.47 mm; the second lens 12 has a center thickness of 1.8 mm, an object-side radius of curvature of -92.09 mm, and an image-side radius of curvature of 59.56 mm; the third lens 13 has a center thickness of 4.5 mm, an object-side radius of curvature of 100.59 mm, and an image-side radius of curvature of -125.14 mm; the fourth lens 14 has a center thickness of 1.6 mm, an object-side radius of curvature of -23.97 mm, and an image-side radius of curvature of -27.92 mm; and the fifth lens 15 has a center thickness of 2.3 mm, an object-side radius of curvature of 94 mm, and an image-side radius of curvature of -1218.96 mm.

[0026] It should be explained that, in Table 1, the first lens 11 is used as an example. Figure 1 The left surface of the first lens 11 is the object-side surface, numbered S1, and the right surface is the image-side surface, numbered S2. The same applies to the other lenses. The aperture stop 16 is not included in the surface numbering.

[0027] Table 1 Lens Parameters In one embodiment, the image-side surface of the first lens 11, the object-side surface of the second lens 12, the two side surfaces of the third lens 13, the object-side surface of the fourth lens 14, and the two side surfaces of the fifth lens 15 are all aspherical surfaces and satisfy the aspherical surface 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. The above aspherical data are shown in Table 2.

[0028] Table 2 Aspherical Data In one embodiment, the object-side surface of the third lens 13 is a binary surface and satisfies the equation for a binary surface in Zemax: M(B1ρ) 2 +B2ρ 4 ); where M is the diffraction order, B1 and B2 are the phase coefficients of the binary surface, and ρ is the normalized radius. The binary surface data are shown in Table 3.

[0029] Table 3 Binary Surface Data Please see Figures 2 to 9 , Figure 2 and Figure 3 The image shows the dot plot and MTF chart when the lens focal length is 15mm. Figure 4 and Figure 5 The image shows a dot plot and MTF chart when the lens focal length is 35mm. Figure 6 and Figure 7 The image shows the dot plot and MTF chart when the lens focal length is 55mm. Figure 8 and Figure 9 The attached figures show the dot plot and MTF diagram when the lens focal length is 75mm. As can be seen from the figures, the focal length of the lens provided in this application can be flexibly changed between 15-75mm, taking into account both wide-area monitoring and long-distance recognition. Moreover, the aberration correction is excellent during zooming, and the imaging is relatively clear and stable across the entire focal length.

[0030] In summary, the lens provided in this application has a focal length of 15-75mm, a relative aperture of 1.2, and an operating wavelength of 8-12μm. The detector resolution is 640*512, and the pixel size is 12μm. This optical imaging device can achieve switching between a large field of view and a small field of view, and can maintain the continuity of the image and the clarity and stability of the target image during the switching process, without losing observation of the target during the change of magnification.

[0031] Although embodiments of this application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A long-wavelength continuous zoom infrared lens, characterized in that, The focal length is 15-75mm. The lens is composed of a first lens, a second lens, a third lens, a fourth lens and a fifth lens arranged sequentially along the optical axis from the object side to the image side. The first lens is a meniscus positive lens with its convex surface facing the object side, the second lens is a biconcave lens, the third lens is a biconvex lens, the fourth lens is a meniscus positive lens with its convex surface facing the image side, and the fifth lens is a biconvex lens. The second and third lenses are movable along the optical axis. The air gap between the first and second lenses is 10.2-22.87 mm, the air gap between the second and third lenses is 4.49-29.41 mm, the air gap between the third and fourth lenses is 5-17.25 mm, and the air gap between the fourth and fifth lenses is 18.69 mm.

2. The long-wavelength continuous zoom infrared lens according to claim 1, characterized in that, The first lens has a center thickness of 6.5 mm, an object-side radius of curvature of 57.06 mm, and an image-side radius of curvature of 86.47 mm; the second lens has a center thickness of 1.8 mm, an object-side radius of curvature of -92.09 mm, and an image-side radius of curvature of 59.56 mm; the third lens has a center thickness of 4.5 mm, an object-side radius of curvature of 100.59 mm, and an image-side radius of curvature of -125.14 mm; the fourth lens has a center thickness of 1.6 mm, an object-side radius of curvature of -23.97 mm, and an image-side radius of curvature of -27.92 mm; and the fifth lens has a center thickness of 2.3 mm, an object-side radius of curvature of 94 mm, and an image-side radius of curvature of -1218.96 mm.

3. The long-wavelength continuous zoom infrared lens according to claim 1, characterized in that, The lens also includes an aperture stop, which is disposed between the third lens and the fourth lens. The air gap between the third lens and the aperture stop is 2.5-14.75mm, and the air gap between the aperture stop and the fourth lens is 2.5mm.

4. The long-wavelength continuous zoom infrared lens according to claim 1, characterized in that, The lens has a relative aperture of 1.2 and an operating wavelength of 8~12μm.

5. The long-wavelength continuous zoom infrared lens according to claim 1, characterized in that, When the focal length of the lens is 15mm, the air gap between the first lens and the second lens is 10.2mm, the air gap between the second lens and the third lens is 29.41mm, and the air gap between the third lens and the fourth lens is 2.5mm. When the focal length of the lens is 75mm, the air gap between the first lens and the second lens is 22.87mm, the air gap between the second lens and the third lens is 4.49mm, and the air gap between the third lens and the fourth lens is 14.75mm.

6. The long-wavelength continuous zoom infrared lens according to claim 1, characterized in that, The image-side surface of the first lens, the object-side surface of the second lens, the two side surfaces of the third lens, the object-side surface of the fourth lens, and the two side surfaces of the fifth lens are all aspherical surfaces and satisfy the aspherical surface 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.

7. An imaging device, characterized in that, It includes the long-wave continuous zoom infrared lens as described in any one of claims 1-6 and a detector capable of receiving the image formed by the lens.

8. The imaging apparatus according to claim 7, characterized in that, The detector has a resolution of 640*512 and a pixel size of 12μm.

9. The imaging apparatus according to claim 7, characterized in that, The detector includes a protective window and an image plane arranged sequentially. The air gap between the fifth lens and the protective window is 10 mm, and the air gap between the protective window and the image plane is 1.5 mm.

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