Optical window thermal deformation compensation device and compensation method of airborne photoelectric pod

Abstract

This invention provides a thermal deformation compensation device and method for the optical window of an airborne optoelectronic pod, belonging to the field of aerospace optical imaging technology. It solves the problem that there is currently no direct method to measure and correct image quality degradation caused by uneven temperature distribution in the window glass. The airborne optoelectronic pod's optical window thermal deformation compensation device is installed inside the pod and includes a forward telescope system, a microbolometer, a deformable mirror, multiple beam splitters, and multiple reflectors. The forward telescope system is located inside the pod, and the microbolometer is mounted on the forward telescope system to generate a thermal image of the pod's first optical window glass. The deformable mirror is located at the rear end of the forward telescope system. Multiple beam splitters and multiple reflectors divide the light rays passing through the deformable mirror into multiple imaging optical paths. This device can perform real-time dynamic correction of image quality changes in the optical system caused by thermal deformation.

Description

Technical Field

[0001] This invention belongs to the field of aerospace optical imaging technology, and in particular relates to a thermal deformation compensation device and method for the optical window of an airborne optoelectronic pod. Background Technology

[0002] Optical window glass, as a crucial component of airborne optical imaging equipment, is typically installed on the outer surface of the fuselage and at the light-transmitting windows of the optical imaging equipment. It ensures both functional light transmission and flight safety. The window glass isolates the pod from the external environment, preventing smoke, dust, moisture, and other contaminants from entering the optical system. During different phases of flight, the optical window glass will inevitably experience differences in temperature and atmospheric pressure between the interior and exterior. The application conditions for airborne windows installed on high-speed aircraft are even more complex, requiring them to withstand severe aerodynamic and thermal shocks.

[0003] When a thermal gradient exists in the window glass of an airborne optoelectronic pod, it leads to a refractive index gradient in the glass material, causing optical path distortion and a decrease in the system transfer function. Simultaneously, localized temperature differences in the window glass result in uneven distribution of transmitted light intensity, reducing imaging contrast. Thermal deformation of the window glass introduces harmful wavefront errors, degrading imaging performance.

[0004] In the prior art, patent announcement number CN221049430U, concerning a heated, anti-frost, low-reflection window glass for an in-vehicle optoelectronic sensing system, proposes a window glass structure with a conductive layer on the window glass. Heating the conductive layer solves the problem of reduced window transmittance due to frost formation and fogging in cold conditions. Patent announcement number CN118042656B, concerning an electrically heated film for sapphire windows and its preparation method, proposes an electrically heated film for sapphire windows that improves optical transmittance and reduces the impact of window thermal deformation on the optical imaging system by heating the window glass.

[0005] However, there is currently no direct method to measure and correct the image quality degradation caused by uneven temperature distribution in window glass. Summary of the Invention

[0006] In view of this, in order to solve the problem that there is currently no direct method to measure and correct the image quality degradation caused by uneven temperature distribution of window glass, this invention proposes an airborne optoelectronic pod optical window thermal deformation compensation device and its compensation method.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A thermal deformation compensation device for the optical window of an airborne optoelectronic pod, installed inside the pod, includes:

[0009] The forward-mounted telescope system is located inside the pod;

[0010] A microbolometer, mounted on the front telescope system, is used to generate a thermal image of the first optical window glass of the pod;

[0011] The deformable mirror is located at the rear of the front telescope system;

[0012] Multiple beam splitters and multiple reflectors are used to split the light rays passing through the deformable mirror into multiple imaging optical paths.

[0013] As a preferred embodiment of the aforementioned thermal deformation compensation device for the optical window of the airborne optoelectronic pod, the number of beam splitters is two, namely a first beam splitter and a second beam splitter; the number of reflectors is three, namely a first reflector, a second reflector, and a third reflector; and the number of imaging optical paths is three, namely a first imaging optical path, a second imaging optical path, and a third imaging optical path. Light rays passing through the deformable mirrors are first reflected by the first beam splitter and then by the first reflector to form the first imaging optical path; light rays passing through the deformable mirrors are sequentially transmitted through the first beam splitter, reflected by the second beam splitter, and reflected by the second reflector to form the second imaging optical path; light rays transmitted through the first beam splitter are first transmitted through the second beam splitter and then reflected by the third reflector to form the third imaging optical path.

[0014] As a preferred embodiment of the aforementioned airborne optoelectronic pod optical window thermal deformation compensation device, the airborne optoelectronic pod optical window thermal deformation compensation device further includes two air pressure monitoring devices, which are used to monitor the air pressure inside and outside the pod in real time, respectively.

[0015] As a preferred embodiment of the aforementioned airborne optoelectronic pod optical window thermal deformation compensation device, the microbolometer is a thermistor microbolometer.

[0016] As a preferred embodiment of the aforementioned airborne optoelectronic pod optical window thermal deformation compensation device, the forward-mounted telescope system includes a primary mirror, a secondary mirror, a corrective mirror, and a support cylinder. The support cylinder is fixedly installed inside the pod, and the microbolometer is fixedly installed in the support cylinder. The primary mirror, secondary mirror, and corrective mirror are all fixedly installed in the support cylinder. The primary mirror is located at the rear end of the secondary mirror, and light passes through the primary mirror, secondary mirror, corrective mirror, and deformable mirror in sequence.

[0017] As a preferred embodiment of the aforementioned airborne optoelectronic pod optical window thermal deformation compensation device, the pod includes a front cover, a middle frame, and a rear cover. One end of the middle frame is fixedly connected to the front cover, and the other end is fixedly connected to the rear cover.

[0018] As a preferred embodiment of the aforementioned airborne optoelectronic pod optical window thermal deformation compensation device, the pod front cover is provided with a first window, the front-mounted telescope system is correspondingly provided with the first window, and the glass of the first optical window is fixedly provided in the first window.

[0019] As a preferred embodiment of the aforementioned airborne optoelectronic pod optical window thermal deformation compensation device, the pod front cover is further provided with four second windows, each of which is fixed with a second optical window glass, and the four second windows are respectively located around the first window.

[0020] As a preferred embodiment of the aforementioned airborne optoelectronic pod optical window thermal deformation compensation device, the first optical window glass is made of fused silica, calcium fluoride, or sapphire material.

[0021] The present invention also provides a method for compensating for thermal deformation of the optical window of an airborne optoelectronic pod, employing the aforementioned airborne optoelectronic pod optical window thermal deformation compensation device, comprising:

[0022] S1: Image the first optical window glass using a microbolometer to generate a thermal image of the first optical window glass;

[0023] S2: Convert the thermal image into a thermal gradient image and analyze the thermal gradient of the first optical window glass;

[0024] S3: Correct the transmitted wavefront distortion caused by the window thermal gradient using a deformable mirror;

[0025] S4: Monitor the air pressure inside the pod in real time, and analyze the deformation of the first optical window glass based on the relationship between air pressure, air speed parameters and optical window deformation.

[0026] S5: Corrects the transmitted wavefront distortion caused by window air pressure and aerodynamic impact using a deformable mirror;

[0027] S6: Complete the wavefront error correction caused by the deformation of the first optical window glass.

[0028] As a preferred embodiment of the above-mentioned method for compensating for thermal deformation of the optical window of an airborne optoelectronic pod, the pressure-speed parameter-optical window deformation relationship diagram is pre-stored in the aircraft's compensation system.

[0029] Compared with the prior art, the beneficial effects of the thermal deformation compensation device and compensation method for the optical window of the airborne optoelectronic pod provided by the present invention are as follows:

[0030] This invention provides a thermal deformation compensation device and method for the optical window of an airborne optoelectronic pod. The device generates a thermal image using a microbolometer, converts the thermal image into a thermal gradient image, calculates the wavefront error, and then uses a deformable mirror to compensate for thermal deformation after the imaging light is incident from infinity onto the front telescope system. The deformation of the deformable mirror corrects and compensates for the image quality of the image formed by the imaging optical path. It can measure the thermal distribution of the first optical window glass in real time and dynamically correct for changes in image quality caused by thermal deformation of the first optical window glass. It can also correct for image quality degradation caused by changes in material refractive index and absorptivity, and improve the imaging quality of the airborne optoelectronic pod in extreme environments. Attached Figure Description

[0031] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0032] Figure 1 This is a schematic diagram of the structure of the thermal deformation compensation device for the optical window of the airborne optoelectronic pod provided in a specific embodiment of the present invention;

[0033] Figure 2 This is a structural diagram of the pod;

[0034] Figure 3 This is a schematic diagram of the front telescope system of the airborne optoelectronic pod optical window thermal deformation compensation device provided in a specific embodiment of the present invention;

[0035] Figure 4 This is a structural diagram of the pod's front cover;

[0036] Figure 5 This is a schematic diagram of the light path along a first viewing angle of the airborne optoelectronic pod optical window thermal deformation compensation device provided in a specific embodiment of the present invention;

[0037] Figure 6 This is a schematic diagram of the light path along a second perspective of the thermal deformation compensation device for the optical window of the airborne optoelectronic pod provided in a specific embodiment of the present invention.

[0038] In the picture:

[0039] 1. Microbolometer;

[0040] 2. Front-mounted telescope system; 201. Primary mirror; 202. Secondary mirror; 203. Correcting mirror; 204. Support cylinder;

[0041] 3. Pod front cover; 301. First optical window glass; 302. Second optical window glass;

[0042] 4. Pod middle frame;

[0043] 5. Rear cover of the pod;

[0044] 6. Deformable mirror;

[0045] 7. First beam splitter;

[0046] 8. Second beam splitter;

[0047] 9. First reflecting mirror;

[0048] 10. Second reflecting mirror;

[0049] 11. Third reflecting mirror;

[0050] 12. First imaging optical path;

[0051] 13. Second imaging optical path;

[0052] 14. Third imaging optical path. Detailed Implementation

[0053] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other, and the described embodiments are only some embodiments of the present invention, not all embodiments.

[0054] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0055] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0056] In the description of this embodiment, the terms "upper," "lower," "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0057] When a thermal gradient exists in the window glass of an airborne optoelectronic pod, it leads to a refractive index gradient in the window glass material, causing optical path distortion, introducing harmful wavefront errors, uneven distribution of transmitted light intensity, reduced imaging contrast, and ultimately a decrease in the system transfer function. Therefore, this invention provides a thermal deformation compensation device and method for the optical window of an airborne optoelectronic pod, see [link to relevant documentation]. Figure 1-6 In this embodiment, the airborne optoelectronic pod's optical window thermal deformation compensation device is installed inside the pod. This device includes a front-mounted telescope system 2, a microbolometer 1, a deformable mirror 6, multiple beam splitters, and multiple reflectors. The front-mounted telescope system 2 is installed inside the pod, and the microbolometer 1 is mounted on it to generate a thermal image of the pod's first optical window glass 301. The deformable mirror 6 is located at the rear end of the front-mounted telescope system 2. Multiple beam splitters and multiple reflectors divide the light passing through the deformable mirror 6 into multiple imaging optical paths.

[0058] The airborne optoelectronic pod's optical window thermal deformation compensation device generates a thermal image using a microbolometer 1. This thermal image is converted into a thermal gradient image, and wavefront error is calculated. The imaging light rays are incident from infinity onto the front telescope system 2 and then pass through a deformable mirror 6. The deformable mirror 6 compensates for thermal deformation, and its deformation corrects and compensates for the image quality of the imaging optical path. It can measure the thermal distribution of the first optical window glass 301 in real time and dynamically correct for changes in image quality caused by thermal deformation of the first optical window glass 301. It can also correct for image quality degradation caused by changes in material refractive index and absorptivity, and improve the imaging quality of the airborne optoelectronic pod in extreme environments.

[0059] Optionally, there are two beam splitters, namely a first beam splitter 7 and a second beam splitter 8, and three reflectors, namely a first reflector 9, a second reflector 10 and a third reflector 11. There are three imaging optical paths, namely a first imaging optical path 12, a second imaging optical path 13 and a third imaging optical path 14. The light rays passing through the deformable mirror 6 are first reflected by the first beam splitter 7 and then by the first reflector 9 to form the first imaging optical path 12. The light rays passing through the deformable mirror 6 are transmitted through the first beam splitter 7, reflected by the second beam splitter 8 and then reflected by the second reflector 10 to form the second imaging optical path 13. The light rays transmitted through the first beam splitter 7 are first transmitted through the second beam splitter 8 and then reflected by the third reflector 11 to form the third imaging optical path 14.

[0060] Optionally, the airborne optoelectronic pod's optical window thermal deformation compensation device further includes two air pressure monitoring devices, used to monitor the air pressure inside and outside the pod in real time. By monitoring the air pressure inside the pod in real time and analyzing the deformation of the first optical window glass 301 based on the air pressure-speed parameter-optical window deformation relationship diagram, the device corrects the transmission wavefront distortion caused by window air pressure and aerodynamic impact through the deformation of the deformable mirror 6. This airborne optoelectronic pod's optical window thermal deformation compensation device can also correct transmission wavefront distortion caused by window air pressure and aerodynamic impact.

[0061] Optionally, the microbolometer 1 is a thermistor microbolometer 1. The microbolometer 1 contains a thermistor material. When the thermistor material absorbs infrared radiation, its temperature rises and its resistance changes accordingly, realizing the conversion from infrared radiation to an electrical signal, thereby generating a thermal image and detecting the temperature value.

[0062] Optionally, the front telescope system 2 includes a primary mirror 201, a secondary mirror 202, a corrective mirror 203, and a support cylinder 204. The support cylinder 204 is fixedly installed inside the pod. The microbolometer 1 is fixedly installed in the support cylinder 204. The primary mirror 201, the secondary mirror 202, and the corrective mirror 203 are all fixedly installed in the support cylinder 204. The primary mirror 201 is located at the rear end of the secondary mirror 202. The light passes through the primary mirror 201, the secondary mirror 202, the corrective mirror 203, and the deformable mirror 6 in sequence.

[0063] In this embodiment, there are two beam splitters, namely the first beam splitter 7 and the second beam splitter 8, and three reflectors, namely the first reflector 9, the second reflector 10 and the third reflector 11. The beam passing through the deformable mirror 6 is divided into three imaging optical paths by the two beam splitters and the three reflectors, namely the first imaging optical path 12, the second imaging optical path 13 and the third imaging optical path 14. Specifically, the imaging light rays are incident on the primary mirror 201 from infinity, reflected by the primary mirror 201 to the secondary mirror 202, reflected by the secondary mirror 202 to the corrector mirror 203, transmitted through the corrector mirror 203 to the deformable mirror 6, and the light rays passing through the deformable mirror 6 are first reflected by the first beam splitter 7 and then by the first reflector mirror 9 to form the first imaging light path 12; the light rays passing through the deformable mirror 6 are transmitted through the first beam splitter 7, reflected by the second beam splitter 8, and reflected by the second reflector mirror 10 in sequence to form the second imaging light path 13; the light rays transmitted through the first beam splitter 7 are first transmitted through the second beam splitter 8 and then reflected by the third reflector mirror 11 to form the third imaging light path 14.

[0064] Optionally, the pod includes a front cover 3, a middle frame 4, and a rear cover 5. One end of the middle frame 4 is fixedly connected to the front cover 3, and the other end is fixedly connected to the rear cover 5.

[0065] Optionally, the pod front cover 3 is provided with a first window, the front telescope system 2 is provided corresponding to the first window, and the first optical window glass 301 is fixedly provided in the first window.

[0066] Optionally, the pod front cover 3 is also provided with four second windows, each of which is fixed with a second optical window glass 302, and the four second windows are respectively around the first window.

[0067] Optionally, the first optical window glass 301 is made of fused silica, calcium fluoride, or sapphire. Other materials with low thermo-optical coefficients can also be used for the first optical window glass 301.

[0068] The present invention also provides a method for compensating for thermal deformation of the optical window of an airborne optoelectronic pod, employing the aforementioned airborne optoelectronic pod optical window thermal deformation compensation device, comprising:

[0069] S1: Image the first optical window glass 301 using the microbolometer 1 to generate a thermal image of the first optical window glass 301.

[0070] S2: Convert the thermal image into a thermal gradient image and analyze the thermal gradient of the first optical window glass 301. Correction must be performed whenever a thermal gradient exists.

[0071] S3: The transmitted wavefront distortion caused by the window thermal gradient is corrected by deformable mirror 6. The wavefront of the optical path is corrected by deforming the deformable mirror 6. The deformation method of the deformable mirror 6 is a conventional setting in this field and will not be described in detail here.

[0072] S4: Real-time monitoring of the air pressure inside the pod; analysis of the deformation of the first optical window glass 301 based on the air pressure-speed parameter-optical window deformation relationship diagram. The aircraft's compensation system pre-stores the air pressure-speed parameter-optical window deformation relationship diagram during the flight of the electro-optical pod, which has been pre-calibrated through multiple experiments.

[0073] S5: The distortion of the transmitted wavefront caused by window air pressure and aerodynamic impact is corrected by deformable mirror 6. The deformation of the first optical window glass 301 is analyzed based on the measured air pressure and air speed information inside and outside the pod during flight. Then, the optical system is corrected by deformable mirror 6 according to the corresponding pre-stored correction values.

[0074] S6: Complete the wavefront error correction caused by the deformation of the first optical window glass 301.

[0075] The present invention also provides an aircraft, including the above-mentioned airborne optoelectronic pod optical window thermal deformation compensation device.

[0076] Obviously, the above-disclosed embodiments of the present invention are merely illustrative of the invention. The embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. It is neither necessary nor possible to exhaustively describe all embodiments herein.

Claims

1. A method for compensating for thermal deformation of the optical window of an airborne optoelectronic pod, comprising an airborne optoelectronic pod optical window thermal deformation compensation device, wherein the airborne optoelectronic pod optical window thermal deformation compensation device is disposed inside the pod, characterized in that... The airborne optoelectronic pod's optical window thermal deformation compensation device includes: A forward-mounted telescope system (2) is installed inside the pod; A microbolometer (1) is installed on the front telescope system (2) to generate a thermal image of the first optical window glass (301) of the pod; the microbolometer (1) is a thermistor microbolometer (1). The deformable mirror (6) is located at the rear end of the front telescope system (2); Multiple beam splitters and multiple reflectors are used to split the light rays passing through the deformable mirror (6) into multiple imaging optical paths. Two air pressure monitoring devices are used to monitor the air pressure inside and outside the pod in real time, respectively; Methods for compensating for thermal deformation of the optical window of an airborne optoelectronic pod include: S1: The first optical window glass (301) is imaged by a microbolometer (1) to generate a thermal image of the first optical window glass (301); S2: Convert the thermal image into a thermal gradient image and analyze the thermal gradient of the first optical window glass (301); S3: Correct the transmission wavefront distortion caused by the window thermal gradient by using the deformable mirror (6); S4: Monitor the air pressure inside the pod in real time, and analyze the deformation of the first optical window glass (301) based on the air pressure-speed parameter-optical window deformation relationship diagram; the air pressure-speed parameter-optical window deformation relationship diagram is pre-stored in the aircraft's compensation system; S5: Correct the transmission wavefront distortion caused by window air pressure and aerodynamic impact by using a deformable mirror (6); S6: Complete the wavefront error correction caused by the deformation of the first optical window glass (301).

2. The method for compensating for thermal deformation of the optical window of an airborne optoelectronic pod according to claim 1, characterized in that: The number of beam splitters is two, namely the first beam splitter (7) and the second beam splitter (8). The number of reflectors is three, namely the first reflector (9), the second reflector (10) and the third reflector (11). The number of imaging optical paths is three, namely the first imaging optical path (12), the second imaging optical path (13) and the third imaging optical path (14). The light rays passing through the deformable mirror (6) are first reflected by the first beam splitter (7) and then reflected by the first reflector (9) to form the first imaging optical path (12). The light rays passing through the deformable mirror (6) are transmitted through the first beam splitter (7), reflected by the second beam splitter (8) and reflected by the second reflector (10) in sequence to form the second imaging optical path (13). The light rays transmitted through the first beam splitter (7) are first transmitted through the second beam splitter (8) and then reflected by the third reflector (11) to form the third imaging optical path (14).

3. The method for compensating for thermal deformation of the optical window of an airborne optoelectronic pod according to claim 1, characterized in that: The front telescope system (2) includes a primary mirror (201), a secondary mirror (202), a corrector mirror (203), and a support cylinder (204). The support cylinder (204) is fixedly installed in the pod. The microbolometer (1) is fixedly installed in the support cylinder (204). The primary mirror (201), secondary mirror (202), and corrector mirror (203) are all fixedly installed in the support cylinder (204). The primary mirror (201) is located at the rear end of the secondary mirror (202). The light passes through the primary mirror (201), secondary mirror (202), corrector mirror (203), and deformable mirror (6) in sequence.

4. The method for compensating for thermal deformation of the optical window of an airborne optoelectronic pod according to claim 1, characterized in that: The pod includes a front cover (3), a middle frame (4), and a rear cover (5). One end of the middle frame (4) is fixedly connected to the front cover (3), and the other end is fixedly connected to the rear cover (5). The front cover (3) is provided with a first window. The front telescope system (2) is correspondingly provided with the first window. The first optical window glass (301) is fixedly provided in the first window.

5. The method for compensating for thermal deformation of the optical window of an airborne optoelectronic pod according to claim 4, characterized in that: The pod front cover (3) is also provided with four second windows, each of which is fixed with a second optical window glass (302), and the four second windows are respectively around the first window.

6. The method for compensating for thermal deformation of the optical window of an airborne optoelectronic pod according to claim 1, characterized in that: The first optical window glass (301) is made of fused silica, calcium fluoride or sapphire.

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