Large-zoom-ratio medium-wave infrared optical system for zoom compensation group cross movement zoom

Abstract

The invention discloses a large-zoom-ratio medium-wave infrared optical system for zoom compensation group cross movement zooming. The large-zoom-ratio medium-wave infrared optical system sequentially comprises an objective lens group, a double-zoom group, a double-compensation group, an eyepiece group, a reflector group and a rear lens group from an object space to an image space, wherein the double-zoom group comprises a first zoom lens and a second zoom lens, the double-compensation group comprises a first compensation lens and a second compensation lens, and the first zoom lens, the first compensation lens, the second zoom lens and the second compensation lens are sequentially arranged along the same center line. Double zoom groups and double compensation groups are arranged in the medium-wave infrared optical system for continuous zooming, the zoom ratio of the medium-wave infrared optical system is improved, meanwhile, a mechanical compensation zooming mode that the zoom groups and the compensation groups move in a crossed mode is adopted during moving zooming, the distance between the two zoom lenses and the distance between the two compensation lenses are fixed respectively, and the zoom ratio of the medium-wave infrared optical system is increased. The zoom stroke is reduced, the complexity in the zoom process is reduced, the installation and adjustment difficulty of the medium-wave infrared optical system is reduced, and the sensitivity of the medium-wave infrared optical system is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of medium wave infrared optics, in particular to a large zoom ratio medium wave infrared optical system with cross-moving zooming of variable compensation groups. BACKGROUND

[0002] The infrared optical system has many advantages such as passive working mode, good concealment, not easy to be disturbed, intuitive image, easy to observe, high precision, and good low-altitude detection performance, and is widely used in various photoelectric equipment systems.

[0003] When the medium wave infrared optical system is in a short focus state, it works in a large field of view state to achieve the purpose of searching for a target, and when it is in a long focus state, it works in a high resolution state to achieve the purpose of distinguishing the target. Compared with an infrared multi-step zoom optical system, an infrared continuous zoom optical system can ensure image continuity while changing the focal length, and target monitoring will not be interrupted. Therefore, for an infrared continuous zoom system, a high zoom ratio means that the system has a larger search range and higher observation precision. Therefore, a high zoom ratio infrared continuous zoom system is an inevitable trend of the development of infrared systems.

[0004] Due to the limitation of the composition mode, the zoom ratio of a traditional infrared continuous zoom system is generally not more than 30 times, and more lenses are used. In the past, a double-group or triple-group linkage was used, and in the entire zooming movement process, the moving curve of the zooming group and the compensation group is gentle. To achieve a high zoom ratio, the zooming stroke increases, which is not suitable for the development trend of lightness and compactness. SUMMARY

[0005] In order to solve the problem of low zoom ratio in the prior art, the present application mainly provides a large zoom ratio medium wave infrared optical system with cross-moving zooming of variable compensation groups, which can achieve a high zoom ratio while reducing the zooming stroke, and has the characteristics of long focal length, high zoom ratio, and good imaging quality.

[0006] To this end, the technical scheme adopted by the present application is as follows: A large zoom ratio medium wave infrared optical system with cross-moving zooming of variable compensation groups is provided, which comprises, in order from the object side to the image side, an objective lens group, a double zooming group, a double compensation group, an eyepiece lens group, a reflecting mirror group, and a rear lens group. The double zooming group comprises a first zooming lens and a second zooming lens, and the double compensation group comprises a first compensation lens and a second compensation lens. The first zooming lens, the first compensation lens, the second zooming lens, and the second compensation lens are placed in order along the optical axis. The object side imaging light beam passes through the objective lens group, the double zooming group, the double compensation group, and the eyepiece lens group in order, is converged to perform first imaging, is folded by the reflecting mirror group, and is second imaged on the detector image plane after passing through the rear lens group. The mobile zoom is realized by relative movement of the double variable magnification group and the double compensation group along the central line optical axis, and the distance between the first variable magnification lens and the second variable magnification lens is fixed, and the distance between the first compensation lens and the second compensation lens is fixed.

[0007] According to the scheme, the objective lens group specifically comprises a first objective lens, the eyepiece group specifically comprises a first eyepiece and a second eyepiece placed in the horizontal direction in sequence, the mirror group specifically comprises a first mirror and a second mirror placed in the vertical direction in sequence, and the rear lens group specifically comprises a first rear lens group, a second rear lens group and a third rear lens group placed in the horizontal direction in sequence.

[0008] According to the scheme, the first variable magnification lens and the second variable magnification lens perform linear motion, and the first compensation lens and the second compensation lens perform nonlinear motion during the mobile zoom.

[0009] According to the scheme, the objective lens, the first compensation lens, the second compensation lens, the second eyepiece, the first rear lens group and the third rear lens group are specifically made of silicon material, the first variable magnification lens, the second variable magnification lens, the first eyepiece and the second rear lens group are specifically made of germanium material, and the mirror material is specifically made of HK9L glass material.

[0010] According to the scheme, the first objective lens is specifically a convex moon-shaped silicon positive lens facing the object side, the first variable magnification lens is specifically a double-concave germanium negative lens, the first compensation lens is specifically a double-convex silicon positive lens, the second variable magnification lens is specifically a double-concave germanium negative lens, the second compensation lens is specifically a double-convex silicon positive lens, the first eyepiece is specifically a double-concave germanium negative lens, the second eyepiece is specifically a convex moon-shaped silicon positive lens facing the image side, the first rear lens group is specifically a convex moon-shaped silicon positive lens facing the object side, the second rear lens group is specifically a convex moon-shaped germanium negative lens facing the object side, and the third rear lens group is specifically a convex moon-shaped silicon positive lens facing the object side.

[0011] According to the scheme, the object side is specifically an incident direction of the object side imaging light beam, and the image side is specifically an exit direction of the object side imaging light beam.

[0012] According to the scheme, the aperture F number of the infrared optical system is 4, and the lens focal length range is 10mm-800mm continuous zoom.

[0013] According to the scheme, the first variable magnification lens, the second variable magnification lens, the second compensation lens, the second eyepiece and the second rear lens group are designed by using aspheric surface.

[0014] A middle wave refrigeration detector is also provided, and the detector is used for sensing the exit light of the large variable magnification ratio middle wave infrared optical system with the variable compensation group cross mobile zoom.

[0015] According to the scheme, the resolution of the detector is 640*512, and the pixel is 15μm.

[0016] The beneficial effects of this invention are as follows: By setting up dual zoom groups and dual compensation groups in the mid-wave infrared optical system for continuous zooming, this invention improves the zoom ratio of the mid-wave infrared optical system. At the same time, during zooming, a mechanical compensation zoom form with cross-movement of zoom groups and compensation groups is adopted, fixing the distance between the two zoom lenses and the two compensation lenses respectively, reducing the zoom travel, reducing the complexity of the zooming process, reducing the difficulty of assembling and adjusting the mid-wave infrared optical system, and reducing its sensitivity.

[0017] Furthermore, by employing two folding mirrors, the present invention enables the object-side imaging beam to undergo secondary imaging, thereby shortening the size of the mid-wave infrared optical system, reducing the system volume, and making its structure more compact.

[0018] Furthermore, by selecting appropriate optical materials and shapes for each lens in the mid-wave infrared optical system and introducing multiple aspherical lenses, the present invention effectively corrects aberrations across the entire zoom range, thereby improving the imaging quality of the mid-wave infrared optical system. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of a large zoom ratio mid-wave infrared optical system with cross-movement zoom of the zoom compensation group according to an embodiment of the present invention; Figure 2 This is a schematic diagram of a short focal length two-dimensional view of a mid-wave infrared optical system according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the mid-focal distance of the mid-wave infrared optical system according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the long focal length two-dimensional view of the mid-wave infrared optical system according to an embodiment of the present invention; Figure 5 This is a 32lp / mm resolution MTF diagram for a short focal length according to an embodiment of the present invention; Figure 6 This is a 32lp / mm resolution MTF image of the medium focal length in an embodiment of the present invention; Figure 7 This is a 32lp / mm resolution MTF image for a long focal length according to an embodiment of the present invention; Figure 8 This is a short focal length diagram of the mid-wave infrared optical system according to an embodiment of the present invention; Figure 9 This is a focal point array diagram of the mid-wave infrared optical system according to an embodiment of the present invention; Figure 10 This is a long focal point array diagram of a mid-wave infrared optical system according to an embodiment of the present invention.

[0020] In the diagram, 1-first objective lens; 2-first zoom lens; 3-first compensating lens; 4-second zoom lens; 5-second compensating lens; 6-first eyepiece; 7-second eyepiece; 8-first reflecting mirror; 9-second reflecting mirror; 10-first rear lens group; 11-second rear lens group; 12-third rear lens group; L1-objective lens group; L2-double zoom group; L3-double compensating group; L4-eyepiece group; L5-reflecting mirror group; L6-rear lens group. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0022] This invention provides a large zoom ratio mid-wave infrared optical system with cross-shift zoom and zoom compensation group, including an objective lens group L1, a dual zoom group L2, a dual compensation group L3, an eyepiece group L4, a mirror group L5, and a rear lens group L6; wherein, the dual zoom group L2 includes a first zoom lens 2 and a second zoom lens 4, and the dual compensation group L3 includes a first compensation lens 3 and a second compensation lens 5, and the first zoom lens 2, the first compensation lens 3, the second zoom lens 4, and the second compensation lens 5 are placed sequentially along the optical axis.

[0023] In use, the object-side imaging beam passes sequentially through objective lens group L1, double zoom group L2, double compensation group L3, and eyepiece group L4 before converging to form an image. Then, it is refracted by mirror group L5 and then imaged a second time on the detector image plane after passing through rear lens group L6. The moving zoom is achieved by the relative movement of the dual zoom group L2 and the dual compensation group L3 along the central optical axis. During the moving zoom, the distance between the first zoom lens 2 and the second zoom lens 4 is fixed, and the distance between the first compensation lens 3 and the second compensation lens 5 is fixed. At the same time, during the moving zoom, the first zoom lens 2 and the second zoom lens 4 perform linear movement, while the first compensation lens 3 and the second compensation lens 5 perform non-linear movement. When the second zoom lens 4 and the first compensation lens 3 are close together, it is a short focal length, and when the second zoom lens 4 and the first compensation lens 3 are far apart, it is a long focal length.

[0024] Specifically, in this embodiment, the objective lens group L1 specifically includes a first objective lens 1, the eyepiece group L4 specifically includes a first eyepiece 6 and a second eyepiece 7 placed sequentially in the horizontal direction, the mirror group L5 specifically includes a first mirror 8 and a second mirror 9 placed sequentially in the vertical direction, and the rear lens group L6 specifically includes a first rear lens 10, a second rear lens 11 and a third rear lens 12 placed sequentially in the horizontal direction.

[0025] Preferably, the objective lens, the first compensating lens 3, the second compensating lens 5, the second eyepiece 7, the first rear lens group 10, and the third rear lens group 12 are made of silicon material, the first zoom lens 2, the second zoom lens 4, the first eyepiece 6, and the second rear lens group 11 are made of germanium material, and the reflector is made of HK9L glass material.

[0026] Preferably, the first objective lens 1 is a meniscus positive silicon lens with a convex object-side orientation; the first zoom lens 2 is a biconcave germanium negative lens; the first compensating lens 3 is a biconvex silicon positive lens; the second zoom lens 4 is a biconcave germanium negative lens; the second compensating lens 5 is a biconvex silicon positive lens; the first eyepiece 6 is a biconcave germanium negative lens; the second eyepiece 7 is a meniscus positive silicon lens with a convex image-side orientation; the first rear lens group 10 is a meniscus positive silicon lens with a convex object-side orientation; the second rear lens group 11 is a meniscus negative germanium lens with a convex object-side orientation; and the third rear lens group 12 is a meniscus positive silicon lens with a convex object-side orientation. Furthermore, the first zoom lens 2, the second zoom lens 4, the second compensating lens 5, the second eyepiece 7, and the second rear lens group 11 are aspherical. The object-side orientation specifically refers to the incident direction of the object-side imaging beam, and the image-side orientation specifically refers to the exit direction of the object-side imaging beam.

[0027] Specifically, the mid-wave infrared optical system with a large zoom ratio and cross-movement zoom in this embodiment has an aperture of F-number of 4, enabling continuous zoom with a lens focal length range of 10mm to 800mm. Simultaneously, the system employs a mechanical compensation zoom method with cross-movement of dual zoom groups L2 and dual compensation groups L3, achieving a zoom ratio of up to 80x, thus shortening the system size and reducing its volume.

[0028] Specifically, in one embodiment of the present invention, the high zoom ratio mid-wave infrared optical system with cross-shift zoom compensation group includes 12 optical elements, specifically including 10 lenses and 2 mirrors: the first objective lens 1 is a meniscus silicon positive lens with a convex surface facing the object side; the first zoom lens 2 is a biconcave germanium negative lens with an aspherical coefficient of A = -7.4315 × 10⁻⁶. -6 B = 1.5894 × 10 -9 C = -4.5424 × 10 -12 The first compensating lens 3 is a biconvex silicon positive lens; the second zoom lens 4 is a biconcave germanium negative lens with an aspherical coefficient of A = 8.1245 × 10⁻⁶. -5 B = -5.6371 × 10 -7 C = 6.3126 × 10 -9 The second compensating mirror 5 is a biconvex silicon positive lens with an aspherical coefficient of A = 4.1698 × 10⁻⁶. -5 B = -8.3549 × 10 -7 C = 7.9635 × 10 -9The first eyepiece 6 is a biconcave germanium negative lens, and the second eyepiece 7 is a meniscus positive silicon lens with a convex image-side surface and an aspherical coefficient of A = 9.6395 × 10⁻⁶. -9 B = -4.1596 × 10 -13 C = 6.3692 × 10 -16 The first rear lens group 10 is a meniscus positive silicon lens with a convex object-side orientation; the second rear lens group 11 is a meniscus negative germanium lens with a convex object-side orientation and an aspheric coefficient of A = -1.5689 × 10⁻⁶. -5 B = 7.1896 × 10 -7 The third rear lens 12 is a meniscus silicon positive lens with its convex surface facing the object side.

[0029] Specifically, the optical system design parameters of this embodiment are shown in the table below:

[0030] Furthermore, the system lens in this embodiment shares the Cassegrain reflection system, front lens group, prism, two-dimensional fast-reflecting mirror, and rear three-element lens group for both medium-wave and long-wave frequencies, which greatly reduces the complexity of the system and makes the structure compact.

[0031] When initially setting up the mid-wave infrared optical system of this embodiment of the invention, along the optical axis, the distance from the center point of the front surface of the first objective lens 1 to the center point of the front surface of the first reflector 8 is 350mm, the distance from the center point of the first reflector 8 to the center point of the second reflector 9 is 60mm, and the distance from the center point of the second reflector 9 to the image plane of the detector is 80mm.

[0032] Continuous zoom is performed using the mid-wave infrared optical system of this invention, wherein the two-dimensional diagrams of the short focal length, medium focal length, and long focal length of the mid-wave infrared optical system are respectively as follows: Figure 2 , Figure 3 and Figure 4 As shown, the focal length of the short focal length is 10mm, the focal length of the medium focal length is 400mm, and the focal length of the long focal length is 800mm.

[0033] Among them, when the focal length of the mid-wave infrared optical system is 10mm, its MTF diagram with a resolution of 32lp / mm and the transmission curves of each field of view are as follows: Figure 5 As shown.

[0034] When the focal length of the mid-wave infrared optical system is 400mm, its MTF plot at 32lp / mm resolution and the transmission curves for each field of view are as follows: Figure 6 As shown.

[0035] When the focal length of the mid-wave infrared optical system is 800mm, its MTF plot at 32lp / mm resolution and the transmission curves for each field of view are as follows: Figure 7 As shown.

[0036] Among them, when the focal length of the mid-wave infrared optical system is 10mm, the short focal point array diagram of the system and the size of the blur spots in each field of view are as follows: Figure 8 As shown.

[0037] When the focal length of the mid-wave infrared optical system is 400mm, the focal point array and the size of the blur spots in each field of view are as follows: Figure 9 As shown.

[0038] When the focal length of the mid-wave infrared optical system is 800mm, the system's long focal point array diagram and the size of the blur spots in each field of view are as follows: Figure 10 As shown.

[0039] Furthermore, this embodiment of the invention also provides a mid-wave cooled detector, which is used to sense the emitted light of the large zoom ratio mid-wave infrared optical system with cross-shift zoom of the zoom compensation group described in this embodiment; and the detector has a resolution of 640×512 and a pixel size of 15μm.

[0040] Currently, the zoom mechanisms of airborne, shipborne, or vehicle-mounted infrared zoom optical systems are mainly dual-component or triple-component linkages, which limit the zoom ratio and can lead to excessively long zoom travel. Zoom structures with more linkages are more difficult to assemble and adjust, making the system more sensitive. This invention employs a mechanically compensated zoom structure with cross-moving zoom compensation groups. The zoom group uses two lenses, and the compensation group uses two lenses, fixedly connected to each other. The distance between the first and second zoom lenses remains constant, resulting in linear motion, while the distance between the first and second compensation lenses remains constant, resulting in non-linear motion. This achieves a high zoom ratio while shortening the zoom travel. Furthermore, the secondary imaging structure compresses the front lens aperture, achieving 100% cold stop efficiency. Two folding mirrors compress the axial and radial dimensions of the system, reducing volume and making the system structure compact. The use of suitable material combinations and aspherical surfaces ensures good image quality throughout the entire zoom travel.

[0041] This invention provides a high zoom ratio mid-wave infrared optical system with cross-movement zoom using zoom compensation groups. By setting up dual zoom groups and dual compensation groups in the mid-wave infrared optical system for continuous zooming, the zoom ratio of the mid-wave infrared optical system is improved. At the same time, a mechanical compensation zoom form with cross-movement of zoom compensation groups is adopted during zooming, fixing the distance between the two zoom lenses and the two compensation lenses respectively, reducing the zoom stroke, reducing the complexity of the zoom process, reducing the difficulty of assembling and adjusting the mid-wave infrared optical system, and reducing its sensitivity, so that its zoom range is 10mm to 800mm and the zoom ratio can reach 80x.

[0042] Furthermore, by employing two folding mirrors, the present invention enables the object-side imaging beam to undergo secondary imaging, thereby shortening the size of the mid-wave infrared optical system, reducing the system volume, and making its structure more compact.

[0043] Furthermore, by selecting appropriate optical materials and shapes for each lens in the mid-wave infrared optical system and introducing multiple aspherical lenses, the present invention effectively corrects aberrations across the entire zoom range, thereby improving the imaging quality of the mid-wave infrared optical system. Simultaneously, the use of an eyepiece group for focusing results in good focusing performance, providing excellent imaging quality for close-range target observation and over a wide temperature range.

[0044] In summary, the large zoom ratio mid-wave infrared optical system of the present invention, through the mechanical compensation zoom of the cross-movement of the zoom compensation group, establishes a suitable initial structure, uses materials with different dispersion characteristics for matching, rationally allocates optical power, and introduces multiple aspherical surfaces to effectively correct aberrations across the entire focal length.

[0045] It should be noted that, depending on the implementation needs, the various steps / components described in this application can be broken down into more steps / components, or two or more steps / components or parts of the operation of steps / components can be combined into new steps / components to achieve the purpose of this invention.

[0046] The order of the steps in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0047] It should be understood that those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A high zoom ratio mid-wave infrared optical system with cross-shift zoom compensation group, characterized in that, From the object side to the image side, the components are: objective lens group, double zoom group, double compensation group, eyepiece group, reflecting mirror group, and rear lens group. The dual zoom group includes a first zoom lens and a second zoom lens, and the dual compensation group includes a first compensation lens and a second compensation lens. The first zoom lens, the first compensation lens, the second zoom lens and the second compensation lens are placed sequentially along the optical axis. The object-side imaging beam passes sequentially through the objective lens group, double zoom group, double compensation group, and eyepiece group before converging to form an image. It is then refracted by the mirror group and re-imaged onto the detector image plane by the rear lens group. The moving zoom is achieved by the relative movement of the dual zoom group and the dual compensation group along the central optical axis. During the moving zoom, the distance between the first zoom lens and the second zoom lens is fixed, and the distance between the first compensation lens and the second compensation lens is fixed.

2. The large zoom ratio mid-wave infrared optical system with cross-movement zoom according to claim 1, characterized in that, The objective lens group specifically includes a first objective lens; the eyepiece group specifically includes a first eyepiece and a second eyepiece placed in sequence in the horizontal direction; the reflecting mirror group specifically includes a first reflecting mirror and a second reflecting mirror placed in sequence in the vertical direction; and the rear lens group specifically includes a first rear lens group, a second rear lens group, and a third rear lens group placed in sequence in the horizontal direction.

3. The large zoom ratio mid-wave infrared optical system with cross-movement zoom according to claim 1, characterized in that, During zooming, the first and second zoom lenses move linearly, while the first and second compensating lenses move non-linearly.

4. The large zoom ratio mid-wave infrared optical system with cross-movement zoom according to claim 2, characterized in that, The objective lens, the first compensating lens, the second compensating lens, the second eyepiece, the first rear lens group, and the third rear lens group are specifically made of silicon material; the first zoom lens, the second zoom lens, the first eyepiece, and the second rear lens group are specifically made of germanium material; and the reflector is specifically made of HK9L glass material.

5. The large zoom ratio mid-wave infrared optical system with cross-movement zoom according to claim 2, characterized in that, The first objective lens is specifically a meniscus positive silicon lens with a convex object-facing orientation; the first zoom lens is specifically a biconcave germanium negative lens; the first compensating lens is specifically a biconvex silicon positive lens; the second zoom lens is specifically a biconcave germanium negative lens; the second compensating lens is specifically a biconvex silicon positive lens; the first eyepiece is specifically a biconcave germanium negative lens; the second eyepiece is specifically a meniscus positive silicon lens with a convex image-facing orientation; the first rear lens group is specifically a meniscus positive silicon lens with a convex object-facing orientation; the second rear lens group is specifically a meniscus negative germanium lens with a convex object-facing orientation; and the third rear lens group is specifically a meniscus positive silicon lens with a convex object-facing orientation.

6. The large zoom ratio mid-wave infrared optical system with cross-movement zoom according to claim 5, characterized in that, The object side specifically refers to the incident direction of the object-side imaging beam, and the image side specifically refers to the exit direction of the object-side imaging beam.

7. The large zoom ratio mid-wave infrared optical system with cross-movement zoom according to claim 1, characterized in that, The infrared optical system has an aperture of F-number of 4 and a lens focal length range of 10mm to 800mm with continuous zoom.

8. The large zoom ratio mid-wave infrared optical system with cross-movement zoom according to claim 2, characterized in that, The first zoom lens, the second zoom lens, the second compensating lens, the second eyepiece, and the second rear lens group are all aspherical.

9. A medium-wave cooled detector, characterized in that, The detector is used to sense the emitted light of the large zoom ratio mid-wave infrared optical system with cross-movement zoom according to any one of claims 1-8.

10. The medium-wave cooled detector according to claim 1, characterized in that, The detector has a resolution of 640×512 and a pixel size of 15μm.

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