A miniaturized long-wave infrared continuous zoom optical system

Abstract

This invention relates to a miniaturized long-wave infrared continuous zoom optical system, comprising a first meniscus positive lens, a biconcave negative lens, a first biconvex positive lens, a meniscus negative lens, a second biconvex positive lens, and a second meniscus positive lens arranged coaxially from the object side to the image side. The biconcave negative lens is the zoom group, and the first biconvex positive lens is the compensation group. The optical system achieves continuous zoom within the range of 20mm to 120mm, with a zoom ratio of 6x. By selecting the curvature of each lens and the spacing between the lenses, the system length is effectively shortened. The total optical length from the front surface of the first meniscus positive lens to the image plane is 170mm. This achieves a miniaturized design while being compatible with current new large-area array detectors with a resolution of 1024x768 and a pixel pitch of 12μm. The zoom process has a smooth and continuous motion curve without abrupt changes, resulting in high imaging quality.

Description

Technical Field

[0001] This invention relates to the field of long-wave infrared optical systems, and more specifically to a long-wave infrared continuous zoom optical system. Background Technology

[0002] All objects in nature with temperatures above absolute zero (-273°C) emit infrared radiation, and infrared image sensors convert this detected infrared radiation into image information visible to the human eye. Uncooled infrared imaging systems, with their advantages of small size, low power consumption, fast startup, and low cost, have been widely used in automotive, security monitoring, and other fields.

[0003] With the rapid development of infrared imaging technology, the demand for infrared zoom optical systems in airborne optoelectronic systems is constantly increasing. 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 lies in maintaining image continuity during field-of-view changes, ensuring the target image remains clearly visible, and not losing observation of the target during magnification changes. It is the optimal choice for modern observation systems to solve the problem of switching between large and small fields of view.

[0004] Because uncooled systems have low temperature resolution and poor detection capabilities, infrared optical systems require large relative apertures to improve these properties, thereby increasing the system's light transmission diameter. Appropriately increasing the relative aperture can improve the system's signal-to-noise ratio. However, a large relative aperture and system miniaturization are contradictory; a large relative aperture means a larger size and weight for the uncooled infrared zoom optical system. Traditional long-wave infrared lenses, for the same focal length, suffer from long length and large size, often failing to meet the requirements of system focal length, resolution, and miniaturization simultaneously.

[0005] For example, Chinese patent application No. 201420346448.4 discloses a long-wave infrared motorized continuous zoom lens. The system has a focal length of 30-120mm, a zoom ratio of 4x, and is compatible with a detector with a resolution of 640×480 and a pixel size of 25μm. It cannot be compatible with the current new long-wave detector with a resolution of 1024×768 and a pixel size of 12μm. In addition, the total length of the optical system of this system is 220mm, which is not conducive to miniaturization.

[0006] Chinese patent application No. 201911044515.0 discloses a miniaturized uncooled infrared continuous zoom optical system with a large target area. The system has a focal length of 30-90mm, a zoom ratio of 3x, and can be adapted to long-wavelength detectors with a resolution of 1024×768 and a pixel size of 14μm. It achieves a miniaturized design with a large target area, but it has the problems of a small zoom ratio and short long-focal resolution.

[0007] Chinese patent application number 201810040650.7 discloses a high-definition long-focal-length long-wave infrared lens. The system has a focal length of 25-300mm and can be paired with high-resolution, large-area long-wave infrared detectors of 1024×768 and 1280×1280. However, the system is relatively long and bulky, making it suitable for ground systems where size and weight requirements are less stringent, but difficult to apply in airborne optoelectronic systems where both size and weight are strictly limited. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention provides a miniaturized long-wave infrared continuous zoom optical system.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0010] A miniaturized long-wave infrared continuous zoom optical system comprises a first meniscus positive lens, a biconcave negative lens, a first biconvex positive lens, a meniscus negative lens, a second biconvex positive lens, and a second meniscus positive lens arranged coaxially from the object side to the image side. The radii of curvature of each surface of the first and second meniscus positive lenses are positive, while the radii of curvature of each surface of the meniscus negative lens are negative. The optical system changes its focal length by axially moving the biconcave negative lens and the first biconvex positive lens. During the change from a large field of view to a small field of view, the movement distance of the biconcave negative lens in the zoom group is 33.64 mm, and the movement distance of the first biconvex positive lens in the compensation group is 27.8 mm.

[0011] Furthermore, by using an axially moving second meniscus lens, the system achieves image plane defocus compensation within a temperature range of -40℃ to +60℃, as well as system defocus compensation caused by changes in the distance of the observed object, thereby ensuring clear imaging of objects at different distances.

[0012] Preferably, the first meniscus positive lens, the biconcave negative lens, the first biconvex positive lens, the meniscus negative lens, the second biconvex positive lens, and the second meniscus positive lens are all made of single-crystal germanium (Ge).

[0013] Furthermore, the thickness of the second biconvex positive lens on the optical axis is CT5, the thickness of the second meniscus positive lens on the optical axis is CT6, and the distance on the optical axis between the second biconvex positive lens and the second meniscus positive lens is T. 56 The following condition must be met: 0.18 ≤ (CT5 + CT6) / T 56 ≤0.22.

[0014] The optical system satisfies 0.10≤BFL / f≤0.16, where f is the focal length of the optical system in its telephoto state, and BFL is the back intercept of the optical system, which is the distance from the vertex of the back surface of the second meniscus positive lens to the image plane.

[0015] Furthermore, the surface of the biconcave negative lens facing the image side (i.e., the exit surface), the surface of the first biconvex positive lens facing the object side (i.e., the incident surface), and the surface of the second biconvex positive lens facing the object side (i.e., the incident surface) are all aspherical.

[0016] The surface of the crescent-shaped negative lens facing the image side, i.e. the exit surface, is aspherical, and a continuous relief structure is formed on the aspherical substrate by diamond turning to create a diffraction surface.

[0017] The first meniscus positive lens satisfies the following condition: 0.75 ≤ f1 / f ≤ 0.95, where f is the focal length of the optical system in its telephoto state and f1 is the effective focal length of the first meniscus positive lens.

[0018] The biconcave negative lens satisfies the following condition: -0.3≤f2 / f≤-0.2, where f is the focal length of the optical system in its telephoto state and f2 is the effective focal length of the biconcave negative lens;

[0019] The first biconvex positive lens satisfies the following condition: 0.3≤f3 / f≤0.5, where f is the focal length of the optical system in its telephoto state and f3 is the effective focal length of the first biconvex positive lens;

[0020] The meniscus negative lens satisfies the following condition: -0.4≤f4 / f≤-0.2, where f is the focal length of the optical system in its telephoto state and f4 is the effective focal length of the meniscus negative lens;

[0021] The second biconvex positive lens satisfies the following condition: 0.35≤f5 / f≤0.45, where f is the focal length of the optical system in its telephoto state and f5 is the effective focal length of the second biconvex positive lens;

[0022] The second meniscus positive lens satisfies the following condition: 0.30≤f6 / f≤0.45, where f is the focal length of the optical system in telephoto mode and f6 is the effective focal length of the second meniscus positive lens.

[0023] The technical parameters achieved by the optical system are: operating wavelength: 8μm~12μm; F # Lens: 1.0~1.2; Focal length: 20mm~120mm; Field of view: 34.15°×25.95°~5.86°×4.40°; Image plane diameter: Φ15.4mm; Total optical length: The distance from the front surface of the first meniscus positive lens to the image plane is 170mm; Wherein, F # The calculation formula is f / D, where f is the focal length of the optical system and D is the diameter of the entrance pupil.

[0024] Beneficial effects:

[0025] 1. This invention achieves continuous zoom within the range of 20mm to 120mm, with a zoom ratio of 6x. By selecting the curvature of each lens and the spacing between lenses, the system length is effectively shortened. The total optical length from the front surface of the first meniscus positive lens to the image plane is 170mm. This achieves a miniaturized design while being compatible with the current new domestic large-area array detector with a resolution of 1024×768 and a pixel pitch of 12μm.

[0026] 2. The present invention rationally sets the aspherical positions of each lens in the system, which improves the imaging quality of the optical system and ensures that the optical system can maintain clear imaging throughout the zoom process. The motion curve during the zoom process is smooth and continuous, without abrupt changes, which can effectively avoid the system from jamming during the zoom process.

[0027] 3. The diffraction surface used to eliminate system chromatic aberration in this invention is set on the exit surface of the meniscus negative lens. Since the lens is a fixed lens, the meniscus negative lens remains fixed during continuous zooming, thereby effectively avoiding the diffraction ring aperture phenomenon that occurs during system zooming. Attached Figure Description

[0028] Figure 1 This is the optical path diagram of the optical system at a focal length of 120mm.

[0029] Figure 2 This is the optical path diagram of the optical system at a focal length of 60mm.

[0030] Figure 3 This is the optical path diagram of the optical system in the short focal length (20mm) state.

[0031] Figure 4 Transfer function graph of the optical system at a telephoto focal length of 120mm;

[0032] Figure 5 Transfer function diagram of the optical system at a focal length of 60mm;

[0033] Figure 6 Transfer function graph of the optical system at a short focal length of 20mm;

[0034] Figure 7 A dot plot of the optical system at a telephoto focal length of 120mm;

[0035] Figure 8 Dot diagram of the optical system at a focal length of 60mm;

[0036] Figure 9 Dot plot of the optical system at a short focal length of 20mm;

[0037] Figure 10 Zoom curve of the optical system.

[0038] Wherein, 1 is the first meniscus positive lens, 2 is the biconcave negative lens, 3 is the first biconvex positive lens, 4 is the meniscus negative lens, 5 is the second biconvex positive lens, 6 is the second meniscus positive lens, and 7 is the image plane. Detailed Implementation

[0039] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. In the description of the present invention, it should be understood that the terms "upper," "lower," "front," "rear," "left," and "right," etc., indicating orientation or positional relationships, are merely for the purpose of describing the present invention and do not indicate or imply that the device or element referred to must have a specific orientation. The terms "first," "second," and "third" are used for descriptive purposes only, referring to the order in which lenses of this type appear, and should not be construed as indicating or implying relative importance. In the accompanying drawings, the figures are merely illustrative and not strictly drawn to scale.

[0040] As is common knowledge, the direction closer to object space is called the object side, and the direction closer to image space is called the image side. From the object side to the image side, the two sides of the lens are the incident surface and the exit surface, respectively.

[0041] In one embodiment of the present invention, the zoom lens is a miniaturized long-wave infrared continuous zoom optical system with a total length of 170mm and a focal length range of 20-120mm. Its focal length zoom ratio is 6x, and its F-number is 1.0 in short focal length mode and 1.2 in long focal length mode. The image plane diameter is Φ15.4mm, which can be adapted to the current new domestic large-area array detector with a resolution of 1024×768 and a pixel pitch of 12μm.

[0042] like Figures 1-3 The 20-120mm miniaturized long-wave infrared continuous zoom optical system shown consists of a first meniscus positive lens 1, a biconcave negative lens 2, a first biconvex positive lens 3, a meniscus negative lens 4, a second biconvex positive lens 5, and a second meniscus positive lens 6 arranged sequentially from the object side to the image side.

[0043] Furthermore, the first meniscus positive lens 1, the biconcave negative lens 2, the first biconvex positive lens 3, the meniscus negative lens 4, the second biconvex positive lens 5, and the second meniscus positive lens 6 are arranged coaxially from the object side to the image side.

[0044] Furthermore, the radii of curvature of each surface of the first meniscus positive lens 1 and the second meniscus positive lens 6 are positive; the radii of curvature of each surface of the meniscus negative lens 4 are negative.

[0045] In this invention, the biconcave negative lens 2 is a zoom group, and the first biconvex positive lens 3 is a compensation group. The focal length of the optical system is changed by axially moving the biconcave negative lens 2 and the first biconvex positive lens 3. When the biconcave negative lens 2 is close to the first meniscus positive lens 1, and the first biconvex positive lens 3 is close to the meniscus negative lens 4, the optical system is in a short focal length, large field of view state. During the change from a large field of view to a small field of view, the biconcave negative lens 2 moves towards the image side, and the first biconvex positive lens 3 moves towards the object side. When the biconcave negative lens 2 and the first biconvex positive lens 3 are closest, the optical system is in a long focal length, small field of view state.

[0046] Furthermore, during the transition from a large field of view to a small field of view, the moving stroke of the variable magnification group biconcave negative lens 2 is 33.64 mm, and the moving stroke of the compensation group first biconvex positive lens 3 is 27.8 mm.

[0047] The 20-120mm miniaturized long-wave infrared continuous zoom optical system uses an axially moving second meniscus lens 6 to achieve image plane defocus compensation within a temperature range of -40℃ to +60℃, as well as system defocus compensation caused by changes in the distance of the observed object, thereby ensuring clear imaging of objects at different distances.

[0048] When the optical system is in short focal length mode, the F-number of the optical system is 1.0, and when the optical system is in long focal length mode, the F-number of the optical system is 1.2.

[0049] Preferably, the first meniscus positive lens 1, the biconcave negative lens 2, the first biconvex positive lens 3, the meniscus negative lens 4, the second biconvex positive lens 5, and the second meniscus positive lens 6 are all made of single-crystal germanium (Ge).

[0050] Preferably, the first meniscus positive lens 1 satisfies the following condition: 0.75≤f1 / f≤0.95, where f is the focal length of the optical system in telephoto mode and f1 is the effective focal length of the first meniscus positive lens 1;

[0051] The biconcave negative lens 2 satisfies the following condition: -0.3≤f2 / f≤-0.2, where f is the focal length of the optical system in its telephoto state and f2 is the effective focal length of the biconcave negative lens 2;

[0052] The first biconvex positive lens 3 satisfies the following condition: 0.3≤f3 / f≤0.5, where f is the focal length of the optical system in the telephoto state and f3 is the effective focal length of the first biconvex positive lens 3;

[0053] The meniscus negative lens 4 satisfies the following condition: -0.4≤f4 / f≤-0.2, where f is the focal length of the optical system in telephoto mode and f4 is the effective focal length of the meniscus negative lens 4;

[0054] The second biconvex positive lens 5 satisfies the following condition: 0.35≤f5 / f≤0.45, where f is the focal length of the optical system in its telephoto state and f5 is the effective focal length of the second biconvex positive lens 5;

[0055] The second meniscus positive lens 6 satisfies the following condition: 0.30≤f6 / f≤0.45, where f is the focal length of the optical system in telephoto mode and f6 is the effective focal length of the second meniscus positive lens 6.

[0056] In the 20-120mm miniaturized long-wave infrared continuous zoom optical system, the thickness of the second biconvex positive lens 5 on the optical axis is CT5, the thickness of the second meniscus positive lens 6 on the optical axis is CT6, and the distance between the second biconvex positive lens 5 and the second meniscus positive lens 6 on the optical axis is T. 56 The following condition must be met: 0.18 ≤ (CT5 + CT6) / T 56 ≤0.22.

[0057] The long-wave infrared continuous zoom optical system satisfies the condition 0.10≤BFL / f≤0.16, where f is the focal length of the optical system in its long focal state and BFL is the back focal length of the optical system, which is the distance from the vertex of the back surface of the second meniscus positive lens 6 to the image plane 7.

[0058] Table 1 shows the technical specifications of the present invention, where F # The formula for calculating the F-number of an optical system is f / D, where f is the focal length of the optical system and D is the diameter of the entrance pupil.

[0059] Table 1 Technical Specifications of the Optical System of the Invention

[0060] parameter Technical indicators detector 1024×768 uncooled infrared detector Pixel size 12μm Operating band 8μm~12μm <![CDATA[F # (F-number of the optical system) 1.0～1.2 focal length 20mm~120mm Field of view 34.15°×25.95°～5.86°×4.40°

[0061] Table 2 lists detailed data for an optical system embodiment according to the present invention, including the surface shape, radius of curvature, thickness, and material of each lens. The units for the radius of curvature and thickness of the lens are mm. The radius of curvature of spherical and aspherical surfaces refers to the radius of curvature at the intersection of the lens surface and the optical axis.

[0062] The “serial number” in Table 2 is counted along the direction of light propagation. For example, the incident surface of the first meniscus positive lens 1 is numbered S1, and the exit surface is numbered S2. The serial numbers of other mirror surfaces are similar. The curved surfaces of the first meniscus positive lens 1, the biconcave negative lens 2, the first biconvex positive lens 3, the meniscus negative lens 4, the second biconvex positive lens 5, and the second meniscus positive lens 6 along the object-to-image direction are respectively marked as S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, and S12.

[0063] In Table 2, "Radius" represents the radius of curvature of the surface. Its sign is determined by taking the intersection of the surface and the principal optical axis as the starting point and the center of the surface as the ending point. If the direction of the connecting line is the same as the direction of light propagation, it is positive; otherwise, it is negative. If the surface is planar, its radius of curvature is infinite. In Table 2, "Thickness" gives the distance between two adjacent surfaces on the optical axis. Its sign is determined by taking the vertex of the current surface as the starting point and the vertex of the next surface as the ending point. If the direction of the connecting line is the same as the direction of light propagation, it is positive; otherwise, it is negative. If the material between the two surfaces is infrared material, the thickness represents the lens thickness; if there is no material between the two surfaces, it represents the air gap between the two lenses.

[0064] Table 2 Detailed data of the optical system in the embodiments of the present invention

[0065]

[0066] The 20-120mm miniaturized long-wave infrared continuous zoom optical system described herein has aspherical surfaces on the surface of the biconcave negative lens 2 facing the image side (emission surface S4), the surface of the first biconvex positive lens 3 facing the object side (incident surface S5), and the surface of the second biconvex positive lens 5 facing the object side (incident surface S9).

[0067] Furthermore, the surface equations of the above-mentioned aspherical surfaces are as follows:

[0068]

[0069] Where z is the distance vector from the vertex of the aspherical surface at a height of r along the optical axis, c is the curvature, c = 1 / R, R represents the radius of curvature of the lens surface, r is the radial coordinate perpendicular to the optical axis, k is the quadratic curve constant, A is the fourth-order aspherical coefficient, B is the sixth-order aspherical coefficient, C is the eighth-order aspherical coefficient, and D is the tenth-order aspherical coefficient.

[0070] Table 3 lists the aspherical coefficients of the image-side surface (exit surface S4) of the biconcave negative lens 2, the object-side surface (incident surface S5) of the first biconvex positive lens 3, and the object-side surface (incident surface S9) of the second biconvex positive lens 5 according to the present invention. The coefficients are expressed in scientific notation; for example, -7.169982e-007 represents -7.169982 × 10⁻⁶. -7 .

[0071] Table 3 Aspheric coefficients of the present invention

[0072]

[0073] Furthermore, the surface of the meniscus negative lens 4 facing the image side, i.e., the exit surface S8, is aspherical. A continuous relief structure is machined on the aspherical substrate using diamond turning to form a diffraction surface, which satisfies the following equation:

[0074]

[0075] Where z is the distance vector from the vertex of the aspherical surface at a height of r along the optical axis, c is the curvature (c = 1 / R), where R represents the radius of curvature of the lens surface, r is the radial coordinate perpendicular to the optical axis, k is the quadratic curve constant, A is the fourth-order aspherical coefficient, B is the sixth-order aspherical coefficient, and C is the eighth-order aspherical coefficient; HOR is the diffraction order, C1, C2, and C3 are the diffraction surface coefficients, λ0 is the design center wavelength, n is the refractive index of the lens, and n0 is the air refractive index.

[0076] Table 4 lists the diffraction aspherical coefficients of the surface of the meniscus negative lens 4 facing the image side, i.e., the exit surface S8, according to the present invention.

[0077] Table 4. Diffraction aspheric coefficients of the present invention

[0078]

[0079] After simulation using optical design software, such as Figure 4 , Figure 5 , Figure 6 As shown, when an uncooled detector with a pixel size of 12μm and a pixel count of 1024×768 is selected, corresponding to a spatial frequency of 42lp / mm, the transfer function of the optical system of this invention is greater than 0.2 in the long focal length, medium focal length, and short focal length states; Figure 7 , Figure 8 , Figure 9 The figure shows a dot plot of the optical system at long, medium, and short focal lengths. As can be seen from the figure, the diameter of the blur spot is smaller than the Airy disk diameter at different focal lengths. Figure 10 The figure shows the zoom curve of the continuous zoom optical system. As can be seen from the figure, the zoom curve of the system is smooth and continuous, without any abrupt change points, which can effectively avoid the system from getting stuck during the zoom process.

[0080] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A miniaturized long-wave infrared continuous zoom optical system, characterized in that, The optical system consists of a first meniscus positive lens (1), a biconcave negative lens (2), a first biconvex positive lens (3), a meniscus negative lens (4), a second biconvex positive lens (5), and a second meniscus positive lens (6) arranged coaxially from the object side to the image side. The convex surfaces of the first meniscus positive lens (1) and the second meniscus positive lens (6) are on the object side, and the radii of curvature of each surface are positive. The convex surface of the meniscus negative lens (4) is on the image side, and the radii of curvature of each surface are negative. The optical system changes its focal length by axially moving the biconcave negative lens (2) and the first biconvex positive lens (3). During the change from a large field of view to a small field of view, the moving stroke of the variable magnification group biconcave negative lens (2) is 33.64 mm, and the moving stroke of the compensation group first biconvex positive lens (3) is 27.8 mm.

2. The miniaturized long-wave infrared continuous zoom optical system according to claim 1, characterized in that, The system achieves image plane defocus compensation within the temperature range of -40℃ to +60℃ and system defocus compensation caused by changes in the distance of the observed scene by using an axially moving second meniscus positive lens (6), thereby ensuring clear imaging of objects at different distances.

3. The miniaturized long-wave infrared continuous zoom optical system according to claim 1, characterized in that, The first meniscus positive lens (1), the biconcave negative lens (2), the first biconvex positive lens (3), the meniscus negative lens (4), the second biconvex positive lens (5), and the second meniscus positive lens (6) are all made of single-crystal germanium (Ge).

4. The miniaturized long-wave infrared continuous zoom optical system according to claim 1, characterized in that, The thickness of the second biconvex positive lens (5) on the optical axis is CT5, the thickness of the second meniscus positive lens (6) on the optical axis is CT6, and the distance between the second biconvex positive lens (5) and the second meniscus positive lens (6) on the optical axis is T. 56 The following condition must be met: 0.18 ≤ (CT5 + CT6) / T 56 ≤0.

22.

5. A miniaturized long-wave infrared continuous zoom optical system according to claim 1, characterized in that, 0.10≤BFL / f≤0.16, where f is the focal length of the optical system in its long focal state, and BFL is the back intercept of the optical system, which is the distance from the vertex of the back surface of the second meniscus positive lens (6) to the image plane.

6. A miniaturized long-wave infrared continuous zoom optical system according to claim 1, characterized in that, The surface of the biconcave negative lens (2) facing the image side, i.e. the exit surface, the surface of the first biconvex positive lens (3) facing the object side, i.e. the incident surface, and the surface of the second biconvex positive lens (5) facing the object side, i.e. the incident surface, are all aspherical.

7. A miniaturized long-wave infrared continuous zoom optical system according to claim 1, characterized in that, The surface of the meniscus negative lens (4) facing the image side, i.e. the exit surface, is a diffractive aspherical surface, and the aspherical surface and the diffractive surface act on the same lens surface.

8. A miniaturized long-wave infrared continuous zoom optical system according to claim 1, characterized in that, The focal lengths of the lenses mentioned above must meet the following conditions: 0.75≤f1 / f≤0.95, -0.3≤f2 / f≤-0.2, 0.3≤f3 / f≤0.5, -0.4≤f4 / f≤-0.2, 0.35≤f5 / f≤0.45, 0.30≤f6 / f≤0.45; where f is the focal length of the optical system in telephoto mode. f1 is the effective focal length of the first meniscus positive lens (1). f2 is the effective focal length of the biconcave negative lens (2). f3 is the effective focal length of the first biconvex positive lens (3). f4 is the effective focal length of the meniscus negative lens (4). f5 is the effective focal length of the second biconvex positive lens (5). f6 is the effective focal length of the second meniscus positive lens (6).

9. A miniaturized long-wave infrared continuous zoom optical system according to claim 1, characterized in that, The technical parameters achieved by the optical system are as follows: operating wavelength: 8μm~12μm; F-number: 1.0~1.2; focal length: 20mm~120mm; Field of view: 34.15°×25.95°~5.86°×4.40°, image plane diameter: Φ15.4mm; total optical length, i.e., the distance from the front surface of the first meniscus positive lens (1) to the image plane, is 170mm; where, F # The calculation formula is f / D, where f is the focal length of the optical system and D is the diameter of the entrance pupil.

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