A turning type miniaturized long-wave infrared continuous zoom optical system

Abstract

The present application relates to a kind of turning type miniaturization long-wave infrared continuous zoom optical system, by first meniscus positive lens, double-concave negative lens, biconvex positive lens, second meniscus positive lens, meniscus negative lens, plane turning mirror, third meniscus positive lens are sequentially arranged from object side to image side, it is composed, the optical system is realized by the reasonable distribution of the power of each lens, 30mm~150mm continuous zoom, and in the process of zooming, motion curve is smooth, continuous, there is no inflection point, by introducing mirror in imaging light path, after being folded and turned by mirror, form "type optical structure form L ", effectively shorten the length of optical system, it is conducive to the miniaturization design of system whole structure.

Description

Technical Field

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

[0002] Infrared thermal imaging systems have been widely used in both military and civilian fields due to their advantages such as strong anti-interference capabilities, long operating range, and all-weather, all-time operation. In the military, they enable the search, reconnaissance, identification, and tracking of military targets; precision guidance using infrared imaging; and the driving and navigation of weapon platforms. In the civilian sector, infrared imaging technology has become the most effective detection tool for preventative maintenance, enabling rapid and accurate detection of faults before equipment failure occurs. It also finds wide application in many other fields, including industry, remote sensing, medicine, power equipment inspection, and scientific research.

[0003] Optoelectronic systems used for target search and identification require infrared thermal imaging systems to achieve both wide-field-of-view target search and narrow-field-of-view identification of distant targets. Therefore, single-field-of-view infrared optical systems cannot meet this requirement. The optical system of an infrared thermal imager needs to be designed as a zoom optical system to achieve this function. Continuous zoom infrared optical systems offer wide coverage with a wide field of view at short focal lengths and high resolution with a narrow field of view at long focal lengths. The wide field of view can be used for searching a large area of ​​targets, while the narrow field of view can be used for target identification. The target image remains clear throughout the zoom process, allowing for any field of view transition within the zoom range. The system does not lose track of the target during continuous zooming and can select an appropriate working field of view based on the scene and target characteristics, greatly improving human-machine interface efficiency.

[0004] To improve the temperature sensitivity of an uncooled infrared continuous zoom optical system, i.e., to reduce the minimum resolvable temperature difference, it is necessary to reduce the system's f-number and increase its transmittance and transfer function. During optical system design, maximizing the system's aperture is crucial, resulting in a larger aperture and longer length for the uncooled infrared continuous zoom optical system. For infrared optical systems mounted in a spherical space, controlling the overall length is essential; a shorter overall length facilitates miniaturization of the entire system.

[0005] Chinese patent application No. 201520063577.7 discloses a continuous zoom uncooled telephoto thermal imaging lens. The focal length of the telephoto end of the zoom optical system is 150mm, and the total length of the optical system is 244mm.

[0006] Chinese patent application No. 201510415786.8 discloses a continuous zoom uncooled infrared thermal imager with a zoom optical system having a focal length of 30-150mm and a total length of 286.88mm.

[0007] Chinese patent application No. 201921561612.2 discloses a 5x long-wave infrared continuous zoom lens. The zoom optical system has a focal length of 150mm at the telephoto end and is compatible with a detector with a resolution of 640×512 and 17μm×17μm. According to the disclosed parameters, the lens has a length of 194.54mm, excluding the distance from the last lens element to the imaging plane.

[0008] Chinese patent application No. 201821510740.X discloses a portable long-focal-length economical long-wave infrared continuous lens. The lens has an effective focal length (EFL) of 30-150mm, an F-number of 1.15@f150mm, an F-number of 0.81@f30mm, a total optical system length of 235mm, and is compatible with a detector with a resolution of 640×480 and a pixel size of 17μm.

[0009] Chinese patent application No. 202123050114.1 discloses an infrared continuous zoom lens with a magnification of 5x, an effective focal length of 30-150mm, a field of view of 5.2°-26.8°, a compatible detector resolution of 640×512, 17μm×17μm, and a total optical system length of 222.98mm. Summary of the Invention

[0010] To address the technical problem of the excessive length of current continuous zoom long-wave infrared lenses, this invention provides a miniaturized, angled long-wave infrared continuous zoom optical system.

[0011] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0012] A miniaturized long-wave infrared continuous zoom optical system with a folding mechanism is disclosed. The optical system comprises a first meniscus positive lens, a biconcave negative lens, a biconvex positive lens, a second meniscus positive lens, a meniscus negative lens, a planar folding mirror, and a third meniscus positive lens arranged coaxially from the object side to the image side. The normal of the planar folding mirror makes an angle of 45° with the optical axis. The angle between the outgoing light ray from the meniscus negative lens and the incident light ray from the third meniscus positive lens is 90° through the planar folding mirror. The focal length of the optical system is changed by axially moving the biconcave negative lens and the biconvex positive lens.

[0013] Furthermore, the concave surfaces of the first meniscus positive lens, the second meniscus positive lens, and the meniscus negative lens are all arranged facing the reflecting surface of the planar folding mirror, while the concave surface of the third meniscus positive lens is arranged facing away from the reflecting surface of the planar folding mirror.

[0014] Furthermore, when the system focal length changes from short focal length to long focal length, the biconcave negative lens moves axially away from the first meniscus positive lens, and the biconvex positive lens moves axially towards the first meniscus positive lens.

[0015] Furthermore, the center-to-center distance between the biconcave negative lens and the first meniscus positive lens is 12.21–49.38 mm, and the center-to-center distance between the biconvex positive lens and the second meniscus positive lens is 5.5–43.63 mm. During the change from a large field of view to a small field of view, the travel distance of the biconcave negative lens is 37.17 mm, and the travel distance of the biconvex positive lens is 38.13 mm.

[0016] Furthermore, the optical system employs an axially movable third meniscus positive lens to compensate for defocus caused by changes in object distance or temperature.

[0017] Furthermore, the first meniscus positive lens, the biconcave negative lens, the biconvex positive lens, the second meniscus positive lens, the meniscus negative lens, and the third meniscus positive lens are all made of single-crystal germanium (Ge), and the planar folding mirror is made of quartz.

[0018] Furthermore, the first meniscus positive lens satisfies the following condition: 0.7≤f1 / f≤0.9, 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;

[0019] 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 at full focal length;

[0020] The biconvex positive lens satisfies the following condition: 0.2≤f3 / f≤0.4, where f is the focal length of the optical system in its telephoto state and f3 is the effective focal length of the biconvex positive lens;

[0021] The second meniscus positive lens satisfies the following condition: 0.6≤f4 / f≤0.7, where f is the focal length of the optical system in its telephoto state and f4 is the effective focal length of the second meniscus positive lens;

[0022] The meniscus negative lens satisfies the following condition: -0.3≤f5 / f≤-0.2, where f is the focal length of the optical system in telephoto mode and f5 is the effective focal length of the meniscus negative lens;

[0023] The third meniscus positive lens satisfies the following condition: 0.2≤f6 / f≤0.3, where f is the focal length of the optical system in its telephoto state and f6 is the effective focal length of the third meniscus positive lens;

[0024] Furthermore, the object-side surface S3 of the biconcave negative lens, the object-side surface S7 of the second meniscus positive lens, and the object-side surface S11 of the third meniscus positive lens are all aspherical surfaces.

[0025] Furthermore, the surface S9 of the meniscus negative lens facing the object side is a diffractive aspherical surface.

[0026] Furthermore, the technical parameters achieved by the optical system are as follows: operating wavelength: 8μm~12μm; F # : 1.2; Focal length: 30mm~150mm; Field of view: 14.6°×11.7°~2.93°×2.35°; Adapted to 640×512, 12μm long-wave infrared detector; 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.

[0027] Beneficial effects:

[0028] 1. The optical system of this invention adopts a mechanical positive group compensation zoom form. Through the reasonable distribution of the optical power of each lens, a continuous zoom of 30mm to 150mm is achieved. By introducing a reflector in the imaging optical path, an "L"-shaped optical structure is formed after the reflector is turned, which effectively shortens the length of the optical system. The dimensions of the optical system are 190mm (length) × 138mm (width) × 138mm (height), which is conducive to the miniaturization design of the overall system structure.

[0029] 2. The optical system of this invention has a smooth and continuous motion curve without inflection points during the zoom process, thereby ensuring clear imaging throughout the zoom process without any jamming. Attached Figure Description

[0030] Figure 1 Optical path diagram of the optical system of the present invention in the short focal length (30mm) state;

[0031] Figure 2 Optical path diagram of the optical system of the present invention at a focal length of 90mm;

[0032] Figure 3 Optical path diagram of the optical system of the present invention in the 150mm telephoto state;

[0033] Figure 4 The transfer function diagram of the optical system of the present invention in the short focal length state of 30mm;

[0034] Figure 5 The transfer function diagram of the optical system of the present invention at a focal length of 90mm;

[0035] Figure 6The transfer function diagram of the optical system of the present invention at a focal length of 150mm;

[0036] Figure 7 A dot plot of the optical system of the present invention in a short focal length (30mm) configuration;

[0037] Figure 8 A dot diagram of the optical system of the present invention at a focal length of 90mm.

[0038] Figure 9 A dot plot of the optical system of the present invention at a focal length of 150mm;

[0039] Figure 10 Field curvature and distortion curves of the optical system of this invention at a short focal length of 30mm;

[0040] Figure 11 Field curvature and distortion curves of the optical system of this invention at a central focal length of 90mm;

[0041] Figure 12 Field curvature and distortion curves of the optical system of this invention at a focal length of 150mm;

[0042] Figure 13 Zoom curve diagram of the optical system of this invention.

[0043] Wherein, 1 is the first meniscus positive lens, 2 is the biconcave negative lens, 3 is the biconvex positive lens, 4 is the second meniscus positive lens, 5 is the meniscus negative lens, 6 is the plane mirror, 7 is the third meniscus positive lens, and 8 is the image plane. Detailed Implementation

[0044] To make the above-mentioned features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings. The purpose of disclosing the present invention is to protect all technical improvements within the scope of the present invention. In the description of the present invention, it should be understood that the terms "upper," "lower," "front," "rear," "left," "right," etc., indicating orientation or positional relationships, are only used to correspond to the accompanying drawings of this application for the convenience of describing the present invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation.

[0045] Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only, referring to the order in which lenses of this type appear. They are used to distinguish between them in description and have no special meaning. They should not be interpreted as indicating or implying relative importance.

[0046] Throughout the manual, the same reference numerals refer to the same components. The accompanying drawings are for illustrative purposes only and are not drawn to scale.

[0047] 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, respectively, the incident surface and the exit surface. The object side refers to the side where the light rays enter, and the image side refers to the side where they exit. "From the object side to the image side along the optical axis" means... Figure 1 The direction from left to right. Of the two surfaces of each lens, the surface facing the object is called the object surface, and the surface facing the image is called the image surface.

[0048] like Figures 1-3 The illustrated miniaturized long-wave infrared continuous zoom optical system consists of a first meniscus positive lens 1, a biconcave negative lens 2, a biconvex positive lens 3, a second meniscus positive lens 4, a meniscus negative lens 5, a planar folding mirror 6, and a third meniscus positive lens 7 arranged sequentially from the object side to the image side.

[0049] The first meniscus positive lens 1, the biconcave negative lens 2, the biconvex positive lens 3, the second meniscus positive lens 4, the meniscus negative lens 5, the planar folding mirror 6, and the third meniscus positive lens 7 are arranged sequentially along the optical axis. The planar folding mirror 6 is positioned between the meniscus negative lens 5 and the third meniscus positive lens 7, and the angle between the normal of the planar folding mirror 6 and the optical axis is 45°. The planar folding mirror ensures that the angle between the outgoing ray from the meniscus negative lens 5 and the incident ray from the third meniscus positive lens 7 is 90°.

[0050] The concave surfaces of the first meniscus positive lens 1, the second meniscus positive lens 4, and the meniscus negative lens 5 are all positioned facing the planar reversing mirror 6, while the concave surface of the third meniscus positive lens 7 is positioned away from the planar reversing mirror 6.

[0051] Furthermore, such as Figures 1-3 As shown, the focal length of the optical system is changed by axially moving the biconcave negative lens 2 and the biconvex positive lens 3. When the focal length changes from short focal length to long focal length, the biconcave negative lens 2 moves axially away from the first meniscus positive lens 1, and the biconvex positive lens 3 moves axially towards the first meniscus positive lens 1. When the distance between the biconcave negative lens 2 and the first meniscus positive lens 1 is the closest, and the distance between the biconvex positive lens 3 and the second meniscus positive lens 4 is the closest, the field of view is large, and the optical system is at its shortest focal length of 30mm. When the distance between the biconcave negative lens 2 and the first meniscus positive lens 1 is the farthest, and the distance between the biconvex positive lens 3 and the second meniscus positive lens 4 is the farthest, the field of view is small, and the optical system is at its longest focal length of 150mm.

[0052] The center-to-center distance between the biconcave negative lens 2 and the first meniscus positive lens 1 is 12.21–49.38 mm, and the center-to-center distance between the biconvex positive lens 3 and the second meniscus positive lens 4 is 5.5–43.63 mm. During the change from a large field of view to a small field of view, the travel of the biconcave negative lens 2 is 37.17 mm, and the travel of the biconvex positive lens 3 is 38.13 mm.

[0053] The optical system employs an axially movable third meniscus lens 7 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.

[0054] Preferably, the first meniscus positive lens 1, the biconcave negative lens 2, the biconvex positive lens 3, the second meniscus positive lens 4, the meniscus negative lens 5, and the third meniscus positive lens 7 are all made of single-crystal germanium (Ge), and the planar folding mirror 6 is made of quartz.

[0055] The specific light transmission path of the above optical system is as follows: the light emitted by the infrared radiation of the external scene is converged by the first meniscus positive lens 1 and then reaches the biconcave negative lens 2. After being diverged by the biconcave negative lens 2, it reaches the biconvex positive lens 3. After being converged by the biconvex positive lens 3, it reaches the second meniscus positive lens 4. After being converged by the second meniscus positive lens 4, it reaches the meniscus negative lens 5. After being diverged by the meniscus negative lens 5, it reaches the plane reversing mirror 6. After being reflected by the plane reversing mirror 6, it reaches the third meniscus positive lens 7. After being converged by the third meniscus positive lens 7, it is imaged on the image plane 8.

[0056] Preferably, the first meniscus positive lens 1 satisfies the following condition: 0.7≤f1 / f≤0.9, 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;

[0057] 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 at full focal length;

[0058] The biconvex positive lens 3 satisfies the following condition: 0.2≤f3 / f≤0.4, where f is the focal length of the optical system in the telephoto state and f3 is the effective focal length of the biconvex positive lens;

[0059] The second meniscus positive lens 4 satisfies the following condition: 0.6≤f4 / f≤0.7, where f is the focal length of the optical system in its telephoto state and f4 is the effective focal length of the second meniscus positive lens;

[0060] The meniscus negative lens 5 satisfies the following condition: -0.3≤f5 / f≤-0.2, where f is the focal length of the optical system in telephoto mode and f5 is the effective focal length of the meniscus negative lens;

[0061] The third meniscus positive lens 7 satisfies the following condition: 0.2≤f6 / f≤0.3, where f is the focal length of the optical system in its telephoto state and f6 is the effective focal length of the third meniscus positive lens;

[0062] The technical specifications achieved by this invention are shown in Table 1, wherein 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.

[0063] Table 1 Technical Specifications of the Optical System of the Invention

[0064] parameter Technical indicators detector 640×512 long-wave infrared detector Pixel size 12μm Operating band 8μm~12μm <![CDATA[F # (F-number of the optical system) 1.2 focal length 30mm~150mm Field of view 14.6°×11.7°～2.93°×2.35°

[0065] Table 2 lists detailed data for embodiments of the optical system of the present invention with focal lengths of 30mm to 150mm, 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. In Table 2, the "Surface Number" is counted along the direction of light propagation. For example, the incident surface of the first meniscus positive lens 1 is number S1, and the exit surface is number S2, and so on for other mirror surfaces. The "Radius" in Table 2 represents the radius of curvature of the surface. Its positive or negative 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 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. The "Thickness" in Table 2 gives the distance between two adjacent surfaces on the optical axis. Its positive or negative 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, then the thickness represents the lens thickness; if there is no material between the two surfaces, it represents the air gap between the two lenses.

[0066] Table 2 Detailed data of the optical system in the embodiments of the present invention

[0067]

[0068]

[0069] The aforementioned miniaturized long-wave infrared continuous zoom optical system with a folding mirror has the following surfaces along the object-to-image direction: the first meniscus positive lens 1, the biconcave negative lens 2, the biconvex positive lens 3, the second meniscus positive lens 4, the meniscus negative lens 5, and the third meniscus positive lens 7 are respectively labeled as S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, and S12. Among them, the surface S3 of the biconcave negative lens 2 facing the object side, the surface S7 of the second meniscus positive lens 4 facing the object side, and the surface S11 of the third meniscus positive lens 7 facing the folding mirror are all aspherical surfaces.

[0070] Furthermore, the surface equations of the above-mentioned aspherical surfaces are as follows:

[0071]

[0072] 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, and C is the eighth-order aspherical coefficient.

[0073] Table 3 lists the aspherical coefficients of the object-side surface S3 of the biconcave negative lens 2, the object-side surface S7 of the second meniscus positive lens 4, and the object-side surface S11 of the third meniscus positive lens 7 according to the present invention. The coefficients are expressed in scientific notation; for example, -2.398381e-007 represents -2.398381 × 10⁻⁶. -7 .

[0074] Table 3 Aspheric coefficients of the present invention

[0075]

[0076] Furthermore, the surface S9 of the meniscus negative lens 5 facing the object side 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:

[0077]

[0078] 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 refractive index of air.

[0079] Table 4 lists the diffraction aspherical coefficients of the surface S9 of the meniscus negative lens 5 facing the object side according to the present invention.

[0080] Table 4. Diffraction aspheric coefficients of the present invention

[0081]

[0082] Based on the aforementioned optical system, and after simulation using optical design software, such as Figure 4 , Figure 5 , Figure 6 As shown, in short-focal, medium-focal, and long-focal states, the transfer function is greater than 0.3 across the entire field of view at the detector's characteristic frequency of 42 lp / mm; Figure 7 , Figure 8 , Figure 9 As shown, the dot plots are displayed under short-focus, medium-focus, and long-focus conditions. The diameter of the blur spot in this system is comparable to the size of the detector pixel. Figure 10 , Figure 11 , Figure 12 As shown, the field curvature and distortion curves are displayed for short, medium, and long focal lengths. The distortion of this system is less than 2% at short focal length and less than 0.1% at long focal length. Figure 13 The figure shows the zoom curve of this continuous zoom optical system. The horizontal axis represents the focal length of the continuous zoom optical system, and the vertical axis represents the axial movement distance of the zoom group and the compensation group. As can be seen from the figure, the zoom curve of this system is smooth and continuous, without any abrupt changes, which can effectively avoid the system from jamming during the zoom process.

[0083] 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 with a turning point, characterized in that, The optical system consists of a first meniscus positive lens (1), a biconcave negative lens (2), a biconvex positive lens (3), a second meniscus positive lens (4), a meniscus negative lens (5), a plane-shaped reflex mirror (6), and a third meniscus positive lens (7), arranged sequentially along the optical axis from the object side to the image side. The angle between the normal of the plane-shaped reflex mirror (6) and the optical axis is 45°. The plane-shaped reflex mirror (6) makes the angle between the outgoing ray from the meniscus negative lens (5) and the incident ray from the third meniscus positive lens (7) 90°. By axially moving the biconcave negative lens (2) and the biconvex positive lens (3), the optical system can achieve the desired optical path. The mirror (3) realizes the change of the focal length of the optical system; the first meniscus positive lens (1), the biconcave negative lens (2), the biconvex positive lens (3), the second meniscus positive lens (4), the meniscus negative lens (5) and the third meniscus positive lens (7) are all made of single crystal germanium, and the planar convoluted mirror (6) is made of quartz; the concave surfaces of the first meniscus positive lens (1), the second meniscus positive lens (4) and the meniscus negative lens (5) are all set facing the reflecting surface of the planar convoluted mirror (6), and the concave surface of the third meniscus positive lens (7) is set away from the reflecting surface of the planar convoluted mirror (6); The focal lengths of each lens in the optical system must meet the following conditions: 0.7≤ f 1 / f ≤0.9，-0.3≤ f 2 / f ≤-0.2，0.2≤ f 3 / f ≤0.4，0.6≤ f 4 / f ≤0.7，-0.3≤ f 5 / f ≤-0.2，0.2≤ f 6 / f ≤0.3； in: f The focal length of the optical system in its telephoto state; f 1 is the effective focal length of the first meniscus positive lens (1); f 2 is the effective focal length of the biconcave negative lens (2); f 3 is the effective focal length of the biconvex positive lens (3); f 4 is the effective focal length of the second meniscus positive lens (4); f 5 is the effective focal length of the meniscus negative lens (5); f6 The effective focal length of the third crescent-shaped positive lens (7) is given.

2. The miniaturized long-wave infrared continuous zoom optical system with a turning point according to claim 1, characterized in that, When the system focal length changes from short focal length to long focal length, the biconcave negative lens (2) moves away from the first meniscus positive lens (1) along the axial direction, and the biconvex positive lens (3) moves towards the first meniscus positive lens (1) along the axial direction.

3. The miniaturized long-wave infrared continuous zoom optical system with a turning point according to claim 1, characterized in that, The center-to-center distance between the biconcave negative lens (2) and the first meniscus positive lens (1) is 12.21 to 49.38 mm, and the center-to-center distance between the biconvex positive lens (3) and the second meniscus positive lens (4) is 5.5 to 43.63 mm. During the change from a large field of view to a small field of view, the travel of the biconcave negative lens (2) is 37.17 mm, and the travel of the biconvex positive lens (3) is 38.13 mm.

4. The miniaturized long-wave infrared continuous zoom optical system with a turning point according to claim 1, characterized in that, The optical system uses an axially moving third meniscus positive lens (7) to compensate for defocus caused by changes in object distance or temperature.

5. The miniaturized long-wave infrared continuous zoom optical system with a turning point according to claim 1, characterized in that, The object-side surface S3 of the biconcave negative lens (2), the object-side surface S7 of the second meniscus positive lens (4), and the object-side surface S11 of the third meniscus positive lens (7) are all aspherical.

6. The miniaturized long-wave infrared continuous zoom optical system with a turning point according to claim 1, characterized in that, The surface S9 of the meniscus negative lens (5) facing the object side is a diffractive aspherical surface.

7. The miniaturized long-wave infrared continuous zoom optical system with a turning point according to claim 1, characterized in that, The technical parameters achieved by the optical system are: operating wavelength: 8μm~12μm; F # Lens: 1.2; Focal length: 30mm~150mm; Field of view: 14.6° 11.7°~2.93° 2.35°; Compatible resolution 640 512, 12μm long-wave infrared detector; among which, F # The calculation formula is f / D , f The focal length of the optical system. D The diameter is the entrance pupil.

Images