Calibration device and method

Abstract

The invention relates to the field of remote sensing cameras, provides a calibration device and method, is applied to a remote sensing camera, and comprises a circuit board and a calibration light source. The circuit board is arranged in a lens cone of the remote sensing camera; the calibration light sources are arranged on the side, facing the imaging end of the remote sensing camera, of the circuit board. The number of the calibration light sources is at least two, and the calibration light sources are located on an imaging light path of the lens cone. The array LED is adopted as a calibration light source, free switching between a calibration mode and an imaging mode on a satellite is achieved, the array LED can provide a stable and controllable light source, the high-precision calibration process is ensured, and system errors are reduced. And free switching between an on-satellite calibration mode and an imaging mode can be realized, so that the use flexibility and multifunctionality of the observation equipment are improved. The device is compact in structure, small in size and light in weight, so that the device is suitable for being used in a space environment, and the burden on a detector is reduced.

Description

Technical Field

[0001] The present invention relates to the field of remote sensing cameras, and in particular to a calibration device and method. Background Art

[0002] As optical remote sensing technology expands across various fields, the need for precise and accurate acquisition and analysis of target information is placing higher demands on satellite remote sensing data. As spatial and temporal resolution continue to improve, enhancing the quantitative application capabilities of remote sensing data is a critical challenge that needs to be addressed across all areas of remote sensing. High-precision on-orbit radiometric calibration is the prerequisite and foundation for the quantitative application of optical remote sensing data.

[0003] On-board calibration is an important means of on-orbit radiation calibration, which is achieved by using an on-board calibration system carried by a satellite. However, the calibration devices in the existing technology are large in size and difficult to apply to platforms with high volume and weight requirements. Summary of the Invention

[0004] In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to propose a calibration device and method to achieve free switching between on-board calibration mode and imaging mode, thereby improving the flexibility and versatility of observation equipment.

[0005] To achieve the above and other related objectives, the present invention provides a calibration device for a remote sensing camera, comprising:

[0006] A circuit board is arranged in the lens barrel of the remote sensing camera;

[0007] A calibration light source is provided on a side of the circuit board facing the imaging end of the remote sensing camera. There are at least two calibration light sources provided and located on the imaging light path of the lens barrel.

[0008] In a specific embodiment of the present invention, an aperture stop is further provided in the lens barrel, and the circuit board is provided on a side of the aperture stop facing the imaging end of the remote sensing camera.

[0009] In a specific embodiment of the present invention, the calibration light source is an LED light source and a plurality of them are arranged in a circular array around the axis of the lens barrel.

[0010] In a specific embodiment of the present invention, a light-through hole coaxial with the axis of the lens barrel is provided at the center of the aperture stop, and the distance from the calibration light source to the axis of the lens barrel is greater than the radius of the light-through hole.

[0011] In a specific embodiment of the present invention, the difference between the distance from the calibration light source to the axis of the lens barrel and the radius of the light hole is less than or equal to 6 mm.

[0012] In a specific embodiment of the present invention, the operating wavelength of at least one of the calibration light sources is different from the operating wavelength of another of the calibration light sources.

[0013] In a specific embodiment of the present invention, the operating wavelength of each calibration light source is in the visible light to near infrared range.

[0014] In a specific embodiment of the present invention, the aperture stop is made of a material having a thermal expansion coefficient greater than 1.6×10 -5 / K material.

[0015] In a specific embodiment of the present invention, the reflectivity of the exposed surface of the aperture stop is less than 3%.

[0016] The present invention also provides a calibration method, which is applied to the calibration device as described above, and comprises the following steps:

[0017] Turning on the calibration light source;

[0018] Collecting a plurality of initial images by the remote sensing camera, and obtaining an on-board calibration image according to the plurality of initial images;

[0019] Turn off the calibration light source;

[0020] Collecting multiple background images by the remote sensing camera, and obtaining a dark current image based on the background images;

[0021] Obtaining a low-frequency normalized image according to the on-board calibration image and the dark current image;

[0022] Repeat the above steps to obtain the low-frequency normalized images at time t0 and time t respectively;

[0023] The absolute responsivity of the remote sensing camera after correction is obtained according to the low-frequency normalized images at time t0 and time t to complete calibration.

[0024] The present invention proposes a calibration device and method. In the above scheme, an array of LEDs is used as a calibration light source to achieve free switching between the on-board calibration mode and the imaging mode. The array of LEDs can provide a stable and controllable light source, ensuring a high-precision calibration process and reducing system errors. It is possible to switch freely between the on-board calibration mode and the imaging mode, which improves the flexibility and versatility of the observation equipment. The compact structure, small size and light weight make the device suitable for use in a space environment, reducing the burden on the detector. The LED light source has a long service life and stability, which reduces the maintenance requirements of the equipment and improves the overall reliability of the system. In on-board calibration, the array of LEDs can provide a light environment similar to the actual observation conditions, enhancing the practicality and accuracy of the calibration process. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0026] Figure 1 is a schematic structural diagram of a calibration device in one embodiment of the present invention;

[0027] Figure 2 FIG. 4 is a flow chart of a calibration method in one embodiment of the present invention.

[0028] Explanation of the accompanying reference numerals: 1. Remote sensing camera; 2. Lens barrel; 10. Circuit board; 20. Calibration light source; 30. Aperture stop; 31. Light hole; 40. Pressing ring; 50. Connector mounting plate; 60. Connector. DETAILED DESCRIPTION

[0029] The following describes the embodiments of the present invention through specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. The details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other unless they conflict.

[0030] It should be noted that the illustrations provided in the following embodiments are merely schematic illustrations of the basic concept of the present invention. Therefore, the illustrations only show components related to the present invention and are not drawn according to the number, shape, and size of components in actual implementation. During actual implementation, the type, quantity, and proportion of each component may be changed arbitrarily, and the component layout may also be more complex.

[0031] Optical remote sensing technology plays a vital role in modern scientific research and applications. With the continuous improvement of spatial and temporal resolution, the ability to quantitatively apply remote sensing data has become increasingly important. To achieve high-precision analysis of optical remote sensing data, on-orbit radiometric calibration has become a key technology. On-board calibration, the core method of on-orbit radiometric calibration, utilizes a specialized calibration system aboard satellites to calibrate remote sensing instruments in real time, ensuring accurate and reliable data.

[0032] Currently, there are two main approaches to onboard calibration. One is the "diffuse reflector + sunlight" calibration method. This method utilizes a diffuse reflector and a solar light source within the device. The diffuse reflector scatters sunlight onto the remote sensor, establishing a relationship between the diffuse reflector's radiant brightness and the sensor's output signal, thereby obtaining a calibration coefficient. This method's advantages lie in its maturity and widespread application, making it suitable for spaceborne imaging spectrometers and radiometers. However, this method faces the issue of diffuse reflector degradation caused by the complexity of the space environment, and the calibration device itself is bulky, making it unsuitable for platforms with strict size and weight requirements.

[0033] Another method uses a standard calibration lamp as a light source for calibration. This method includes a standard lamp power supply system, a light source, a light homogenizer, an imaging system, and a monitoring optical path. Light from the light source is processed by the homogenizer and then enters the monitoring optical path. This light is compared with the output data of the remote sensing instrument to establish a relationship between input and output. This method offers advantages in performance stability and comprehensive functionality, but the long back focus distance required to install the prism makes it unsuitable for onboard calibration of wide-field-of-view remote sensing cameras.

[0034] like Figure 1 As shown, in order to solve the above technical problems, the present invention provides a calibration device, which is applied to a remote sensing camera 1, specifically to a large-field-of-view focal plane polarization remote sensing camera 1 with a focal length of 4 mm and a field of view of 88°. The calibration device includes a circuit board 10 and a calibration light source 20. The circuit board 10 is arranged in the lens barrel 2 of the remote sensing camera 1; the calibration light source 20 is arranged on the side of the circuit board 10 facing the imaging end of the remote sensing camera 1. At least two calibration light sources 20 are provided and are located in the imaging optical path of the lens barrel 2. The power of the calibration light source 20 is less than 300 mW. The circuit board 10 and the calibration light source 20 are integrated in the lens barrel 2, saving space and being suitable for satellite platforms with high volume and weight requirements. It can freely switch between orbit calibration mode and imaging mode, thereby improving the flexibility and efficiency of calibration. The imaging end refers to the end away from the lens of the remote sensing camera 1.

[0035] like Figure 1As shown, the system also includes an aperture stop 30 disposed within the lens barrel 2 and secured thereto by a pressure ring 40. The circuit board 10 is disposed on the side of the aperture stop 30 facing the imaging end of the remote sensing camera 1 and is fixed to the aperture stop 30 via screws. The calibration device integrates a calibration light source 20 onto the circuit board 10 and mounts it directly to the aperture stop 30. Because the calibration light source 20 is integrated onto the circuit board 10 and mounted directly to the aperture stop 30, this design eliminates the moving parts common in traditional calibration systems. This simplified structure not only reduces manufacturing costs but also reduces potential points of failure, thereby improving overall system reliability. The integrated design of the calibration light source and circuit board 10 makes the entire calibration device more compact. This compact design is particularly important for space-constrained remote sensing camera systems 1, as it allows for efficient utilization of limited space. The integrated design of the calibration light source 20 and circuit board 10 results in a high level of integration. This high level of integration improves device performance and reduces external connection points, reducing system complexity and maintenance. With no moving parts or complex structure, this calibration device consumes minimal resources. This not only reduces system weight but also saves space and energy. Its simple structure and lack of moving parts also ensure high reliability. Mechanical failures are less likely to occur during the calibration process, ensuring long-term stable operation.

[0036] like Figure 1 As shown, the lens barrel 2 also includes a connector 60, which is mounted on the connector mounting plate 50. A cable connects the connector 60 to the circuit board 10. The connector 60 is located inside the lens barrel 2. The connector 60, circuit board 10, and aperture stop 30 are removable and installable as a whole. Mounting holes are provided on the lens barrel 2, and positioning holes are provided on one side of the aperture stop 30. Threaded holes are provided in corresponding positions on the lens barrel 2 to ensure that the connector 60 is always aligned with the mounting holes when the calibration light source 20 is installed in the lens barrel 2. The lens barrel 2 uses a stopper to connect the object to be calibrated to the instrument camera to ensure coaxiality between the two. The connector 60 serves as the power interface for the circuit board 10.

[0037] In a specific embodiment of the present invention, the calibration light source 20 is an LED light source and a plurality of them are arranged in a circular array around the axis of the lens barrel 2. The calibration light source 20 is specifically an LED light source. The specific LED model is SMA10CU407-5551050, and the power is 200mW. By adopting an array of LEDs as the calibration light source 20, it is possible to freely switch between the on-orbit calibration mode and the imaging mode, which is beneficial to increasing the frequency of on-orbit calibration. There are specifically ten LED light sources. The calibration light sources 20 are centrally symmetrically distributed, that is, the operating wavelengths of the two centrally symmetrical calibration light sources 20 are the same. The circular array arrangement can ensure that the light source provides uniform illumination throughout the entire field of view, reducing image errors caused by uneven light sources. The centrally symmetrical distribution of the LED light sources and maintaining the same wavelength help to ensure the stability and consistency of the light source output and reduce system errors in the optical system.

[0038] In one specific embodiment of the present invention, a light hole 31 is defined at the center of the aperture stop 30, coaxial with the axis of the lens barrel 2. The distance between the calibration light source 20 and the axis of the lens barrel 2 is greater than the radius of the light hole 31. The greater distance between the calibration light source 20 and the axis of the lens barrel 2 and the radius of the light hole 31 means that the light source is positioned with a certain margin from the edge of the light hole 31. This effectively reduces optical distortion caused by an off-center light source, thereby maintaining high imaging quality and accuracy. Because the light source is positioned farther from the center of the light hole 31, the light beam maintains good alignment accuracy when entering the light hole 31. This design ensures that the light spot of the light beam does not deviate excessively from the center of the light hole 31, thereby reducing the impact of beam deviation. A light source position greater than the radius of the light hole 31 helps avoid edge effects in the light beam, thereby providing more uniform illumination. Uniform illumination helps improve the stability and consistency of imaging and measurement.

[0039] In a specific embodiment of the present invention, the difference between the axial distance between the calibration light source 20 and the lens barrel 2 and the radius of the light-through hole 31 is less than or equal to 6 mm. Specifically, the axial distance between the calibration light source 20 and the lens barrel 2 is 6 mm, and the radius of the light-through hole 31 is 0.5 mm. The difference between the position of the calibration light source 20 and the radius of the light-through hole 31 is small, ensuring the consistency of the light source position during the calibration process. This helps to ensure the stability of the light source position in each calibration operation and improve the reliability and consistency of the calibration process. The precise setting of the light source from the axial center of the lens barrel 2 ensures that the light beam can be correctly aligned with the light-through hole 31. This helps to reduce the imaging error caused by the light beam deviating from the center of the light-through hole 31 and ensures the alignment accuracy of the light beam.

[0040] In a specific embodiment of the present invention, the operating wavelength of at least one of the calibration light sources 20 is different from the operating wavelength of another calibration light source 20. The operating wavelength of each calibration light source 20 is in the visible light to near-infrared band. The specific wavelengths of the calibration light sources 20 can be 555nm, 670nm, 865nm, 910nm and 1050nm respectively. The operating wavelength of each calibration light source 20 ranges from the visible light band (555nm, 670nm) to the near-infrared band (865nm, 910nm, 1050nm), covering a wide range of the spectrum. This ensures that the system can adapt to and calibrate light of different wavelengths, thereby improving the performance and accuracy of the system over the entire spectral range. Using multiple light sources of different wavelengths allows for multi-point calibration, thereby more comprehensively evaluating and adjusting the performance of the optical system at different wavelengths. This helps to improve the calibration accuracy and consistency of the system, ensuring its stability and reliability in various application scenarios.

[0041] In a specific embodiment of the present invention, the aperture stop 30 is made of a material having a thermal expansion coefficient greater than 1.6×10 -5 The iris diaphragm is made of a material with a high coefficient of thermal expansion (CTE). Specifically, it can be stainless steel. Selecting a material with a high CTE allows for specific design features to allow for predictable adjustment of the aperture with temperature changes, thereby compensating for distortion or deviation in the optical system due to temperature fluctuations. This helps maintain optical system alignment accuracy and image quality.

[0042] In a specific embodiment of the present invention, the reflectivity of the exposed surface of the aperture stop 30 is less than 3%. The emissivity requirement can be achieved through blackening treatment, specifically by chemical blackening. Blackening treatment can significantly improve the emissivity of the aperture surface. Emissivity refers to the ability of an object's surface to emit thermal radiation. Through blackening treatment, the surface becomes darker, thereby making its emissivity higher. This helps to reduce the reflection of thermal radiation in the optical system and reduce the impact of temperature drift of the optical system on system performance. In high-precision optical applications, reflected light may interfere with measurement results or affect optical performance. Through blackening treatment, the reflected light on the surface is reduced, which can significantly improve the anti-interference performance of the system.

[0043] like Figure 2 As shown, the present invention also provides a calibration method, which is applied to the calibration device as described above, comprising the following steps:

[0044] S1. Turn on the calibration light source 20. Turn on the calibration light source 20 when the camera is in on-orbit calibration mode. Set the onboard calibration timing to when the remote sensing camera 1 is observing the Earth's dark side over the ocean or toward cold space. Instruct the light source control module to power on the calibration light source 20, turning it on and preheating it until it stabilizes. Light emitted by the calibration light source 20 is collimated by the optical elements behind the aperture stop 30, achieving quasi-uniform illumination of the camera.

[0045] S2. Collect multiple initial images through remote sensing camera 1, and obtain the on-board calibration image based on the multiple initial images. Let the first on-board calibration time be the initial time t0. Taking time t0 as an example, the on-board calibration image at time t0 is obtained by averaging the multiple initial images. Where k represents the band, i and j represent the row and column of the camera detector respectively.

[0046] S3. Turn off the calibration light source 20. When the remote sensing camera 1 is in the on-board imaging mode, the calibration light source 20 is controlled to be turned off.

[0047] S4. Collect multiple background images through remote sensing camera 1 and obtain dark current image based on the background images. After averaging multiple background images, obtain dark current image at time t0.

[0048] S5. Obtain a valid image based on the onboard calibration image and dark current image. and After subtraction, the effective image at time t0 is obtained

[0049] S6. Obtain a normalized image based on the valid image. The normalized image at time t0 is obtained using the following formula:

[0050]

[0051] Where n represents the number of pixels in the central area of ​​the detector in the camera, i0 and j0 represent the row and column where the central pixel of the detector is located, respectively.

[0052] S7, obtain a low-frequency normalized image based on the normalized image. Perform least square surface fitting on the normalized image to obtain the low-frequency normalized image at time t0

[0053] S8. Repeat the above steps to obtain the low-frequency normalized images at time t0 and time t respectively. and

[0054] S9. Obtain the relative radiation correction coefficient based on the low-frequency normalized images at time t0 and time t. The radiation correction coefficient is obtained using the following formula:

[0055]

[0056] S10, obtain the absolute radiation correction coefficient according to the relative radiation correction coefficient. The absolute radiation correction coefficient a is obtained using the following formula: k .

[0057]

[0058] S11. Obtain the absolute responsivity of the remote sensing camera 1 after correction based on the absolute radiation correction coefficient to complete the calibration. The absolute responsivity is obtained using the following formula:

[0059]

[0060] in, represents the absolute radiation calibration coefficient of band k before correction, Represents the relative radiation calibration coefficient of band k before correction; W k It represents the nonlinear correction coefficient of band k, where K is the gain coefficient.

[0061] This calibration method, through least-squares fitting of the image, can correct for inconsistencies (i.e., high-frequency signals) between pixels in the focal plane detector of remote sensing camera 1 during on-orbit operation, without being affected by the decay of calibration light source 20. Combined with on-board field calibration, subtracting high-frequency signal errors from the image helps reduce the root mean square error of the remote sensing image, thereby improving the accuracy of on-orbit radiometric calibration.

[0062] Least squares fitting optimizes parameters by minimizing the squared error of the fitted function, resulting in more accurate correction results. For inter-pixel inconsistencies (high-frequency signals) in remote sensing camera 1, this method can precisely adjust the response differences of each pixel, thereby improving the overall uniformity and accuracy of the image. Correcting high-frequency signal errors through least squares fitting helps reduce image noise and errors caused by inconsistencies between pixels. This correction effectively removes high-frequency error components from the image, resulting in higher quality and clearer details in the final image.

[0063] In summary, the present invention proposes a calibration device and method. In the above scheme, an array of LEDs is used as a calibration light source 20 to achieve free switching between the on-board calibration mode and the imaging mode. The array of LEDs can provide a stable and controllable light source, ensuring a high-precision calibration process and reducing system errors. It is possible to switch freely between the on-board calibration mode and the imaging mode, which improves the flexibility and versatility of the observation equipment. The compact structure, small size and light weight make the device suitable for use in a space environment, reducing the burden on the detector. The LED light source has a long service life and stability, which reduces the maintenance requirements of the equipment and improves the overall reliability of the system. In on-board calibration, the array of LEDs can provide a light environment similar to the actual observation conditions, enhancing the practicality and accuracy of the calibration process.

[0064] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

[0065] In the description herein, numerous specific details, such as examples of components and / or methods, are provided to provide a complete understanding of the embodiments of the present invention. However, those skilled in the art will recognize that embodiments of the present invention may be practiced without one or more of the specific details or with other devices, systems, assemblies, methods, components, materials, parts, etc. In other cases, well-known structures, materials, or operations are not specifically shown or described in detail to avoid obscuring aspects of the embodiments of the present invention.

[0066] Reference throughout this specification to "one embodiment," "an embodiment," or "a specific embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention, and not necessarily in all embodiments. Thus, various appearances of the phrases "in one embodiment," "in an embodiment," or "in a specific embodiment" in different places throughout this specification are not necessarily referring to the same embodiment. Furthermore, the particular features, structures, or characteristics of any specific embodiment of the invention may be combined with one or more other embodiments in any suitable manner. It should be understood that other variations and modifications of the embodiments of the invention described and illustrated herein are possible in light of the teachings herein and are considered part of the spirit and scope of the invention.

[0067] It should also be understood that one or more of the elements shown in the figures may also be implemented in a more separate or more integrated manner, or even removed because they are inoperable in certain circumstances or provided because they may be useful depending on the application.

[0068] In addition, unless otherwise expressly indicated, any marking arrows in the drawings should be regarded as illustrative only and not limiting. Furthermore, unless otherwise indicated, the term "or" as used herein is generally intended to mean "and / or." Where a term is unclear in providing separation or combination capabilities, the combination of components or steps will also be considered as indicated.

[0069] As used in the description herein and throughout the claims that follow, “a,” “an,” and “the” include plural references unless otherwise indicated. Likewise, as used in the description herein and throughout the claims that follow, the meaning of “in” includes “in” and “on” unless otherwise indicated.

[0070] The above description of the illustrated embodiments of the present invention (including that described in the Abstract) is not intended to be exhaustive or to limit the invention to the precise forms disclosed herein. Although specific embodiments of the present invention and examples of the present invention are described herein for illustrative purposes only, as those skilled in the art will recognize and appreciate, various equivalent modifications are possible within the spirit and scope of the present invention. As noted, modifications may be made to the present invention in light of the above description of the illustrated embodiments of the present invention, and such modifications will be within the spirit and scope of the present invention.

[0071] Systems and methods have been generally described herein in detail to facilitate understanding of the present invention. In addition, various specific details have been given to provide an overall understanding of embodiments of the present invention. However, those skilled in the relevant art will recognize that embodiments of the present invention may be practiced without one or more of these specific details, or with other devices, systems, accessories, methods, components, materials, parts, etc. In other cases, well-known structures, materials, and / or operations are not specifically shown or described in detail to avoid obscuring aspects of embodiments of the present invention.

[0072] Thus, although the invention has been described herein with reference to specific embodiments thereof, freedom of modification, various changes and substitutions are contemplated within the foregoing disclosure, and it should be understood that in some cases, some features of the invention will be employed without the corresponding use of other features without departing from the scope and spirit of the claimed invention. Thus, many modifications may be made to adapt a particular environment or material to the true scope and spirit of the invention. The invention is not intended to be limited to the specific terminology used in the claims below and / or to the specific embodiments disclosed as the best mode contemplated for carrying out the invention, but the invention is intended to include any and all embodiments and equivalents falling within the scope of the appended claims. Thus, the scope of the invention will be determined solely by the appended claims.

Claims

1. A calibration device, applied to a remote sensing camera, characterized in that: include: A circuit board is arranged in the lens barrel of the remote sensing camera; A calibration light source is arranged on a side of the circuit board facing the imaging end of the remote sensing camera. At least two calibration light sources are provided and are located on the imaging light path of the lens barrel.

2. The calibration device according to claim 1, characterized in that: It also includes an aperture diaphragm arranged in the lens barrel, and the circuit board is arranged on a side of the aperture diaphragm facing the imaging end of the remote sensing camera.

3. The calibration device according to claim 2, characterized in that: The calibration light source is an LED light source and a plurality of them are arranged in a circular array around the axis of the lens barrel.

4. The calibration device according to claim 3, characterized in that: A light-through hole coaxial with the axis of the lens barrel is provided at the center of the aperture stop, and a distance from the calibration light source to the axis of the lens barrel is greater than a radius of the light-through hole.

5. The calibration device according to claim 4, characterized in that: The difference between the axial distance from the calibration light source to the lens barrel and the radius of the light-through hole is less than or equal to 6 mm.

6. The calibration device according to claim 1, characterized in that: The operating wavelength of at least one of the calibration light sources is different from the operating wavelength of another of the calibration light sources.

7. The calibration device according to claim 1, characterized in that: The operating wavelength of each calibration light source is in the visible light to near infrared range.

8. The calibration device according to claim 2, characterized in that: The aperture stop has a thermal expansion coefficient greater than 1.6×10 -5 / K material.

9. The calibration device according to claim 2, characterized in that: The exposed surface reflectivity of the aperture stop is less than 3%.

10. A calibration method, applied to the calibration device according to any one of claims 1 to 9, characterized in that: The steps include: Turning on the calibration light source; Collecting a plurality of initial images by the remote sensing camera, and obtaining an on-board calibration image according to the plurality of initial images; Turn off the calibration light source; Collecting a plurality of background images by the remote sensing camera, and obtaining a dark current image according to the background images; Obtaining a low-frequency normalized image according to the on-board calibration image and the dark current image; Repeat the above steps to obtain the low-frequency normalized images at time t0 and time t respectively; The absolute responsivity of the remote sensing camera after correction is obtained according to the low-frequency normalized images at time t0 and time t to complete calibration.

Images