Image stabilization system and method for solar polar orbit telescope

Abstract

The invention discloses an image stabilization system and method for a solar polar orbit telescope, solves the problem that images formed by the solar polar orbit telescope are integrally offset and aliasing due to satellite jitter and the sun cannot be clearly imaged, and specifically comprises an incident unit, an image stabilization lens unit, an image stabilization zoom lens unit, a detector and a numerical control unit. The incidence unit is used for being arranged at the incidence end of the sun polar orbit telescope to be subjected to image stabilization; the image stabilizer unit is used for being arranged at the emergent end of the sun polar orbit telescope to be subjected to image stabilization; the image stabilization zoom lens unit is arranged on the light path of the sunlight of which the angle is adjusted by the image stabilization lens unit; the detector is arranged at the emergent end of the image stabilization zoom lens unit; the numerical control unit is respectively connected with the detector, the image stabilizer unit and the image stabilization zoom lens unit, is used for calculating the adjusting angle of the image stabilizer unit according to the light intensity output by the detector so as to control and adjust the image stabilizer unit, and is also used for controlling and adjusting the focal length of the image stabilization zoom lens unit according to the sun distance detected by a satellite.

Description

Technical Field

[0001] The present invention relates to a solar telescope, and more particularly to a image stabilization system and method for a solar polar orbiting telescope. Background Art

[0002] The space full-disk solar polar orbiting telescope can remotely detect targets such as the solar photosphere, chromosphere, sunspots, magnetic fields, and flares. The solar polar orbiting telescope generally has a relatively long focal length and high requirements for image resolution. When the solar polar orbiting telescope is in orbit, the jitter of the satellite will cause the image to shift as a whole, resulting in pixel aliasing and a decrease in imaging quality. In addition, during the rocket launch and orbit transformation processes, the relative distance between the solar polar orbiting telescope and the sun changes, resulting in a change in the spot size of the solar image. When the distance between the solar polar orbiting telescope and the sun gradually increases from 0.9 AU to 2.6 AU, the spot size on the image stabilization detector decreases from 18.6 mm to 6.7 mm. Since the size of each photodiode on the image stabilization detector is less than 3 mm, the change in the spot exceeds the detectable range of the photodiode, resulting in the failure of the image stabilization function, where 1 AU represents one solar-earth distance.

[0003] For the correction of image offset caused by high-frequency satellite jitter, generally, an image processing method is adopted. Multiple frames of images are obtained using a traditional area array detector, the feature area of the image is extracted using a correlation filtering algorithm, and the centroid position of the image is confirmed using a centroid algorithm. However, the frame rate of the area array detector in this scheme is low, and the imaging quality recovery effect is poor.

[0004] Therefore, in order to avoid the influence of the overall image offset caused by high-frequency satellite jitter and ensure the imaging quality of the space full-disk solar polar orbiting telescope, there is an urgent need to provide an image stabilization system for the solar polar orbiting telescope. Summary of the Invention

[0005] In order to solve the technical problems that the overall offset and aliasing of the image formed by the solar polar orbiting telescope caused by satellite jitter make it impossible to clearly image the sun, and for the solar polar orbiting satellite with multiple orbit transformations, the change range of the diameter of the solar image in the image stabilization optical path is large and exceeds the detectable range, resulting in the inability to perform detection, the present invention provides an image stabilization system and method for a solar polar orbiting telescope. The image stabilization system can ensure that the size of the solar image on the edge detector of the solar polar orbiting telescope remains unchanged during the orbit transformation process when the distance between the satellite and the sun changes from 0.95 AU to 2.64 AU, avoiding the failure of the image stabilization function due to exceeding the range.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A image stabilization system for a solar polar orbiting telescope, which is installed on a satellite. The special features are as follows: it includes an incident unit, an image stabilization mirror unit, an image stabilization zoom lens unit, a detector, and a numerical control unit;

[0008] The incident unit is used to be installed at the incident end of the solar polar orbiting telescope to be image-stabilized, so as to screen the sunlight wavelength and isolate ultraviolet and infrared radiation;

[0009] The image stabilization mirror unit is used to be installed at the exit end of the solar polar orbiting telescope to be image-stabilized, so as to adjust the angle of sunlight;

[0010] The image stabilization zoom lens unit is installed on the optical path of the sunlight after the angle is adjusted by the image stabilization mirror unit. Its incident end corresponds to the image stabilization mirror unit and is used to adjust the zoom of the image stabilization system;

[0011] The detector is installed at the exit end of the image stabilization zoom lens unit and is used to detect the light intensity of the sunlight after zooming by the image stabilization zoom lens unit;

[0012] The numerical control unit is respectively connected to the detector, the image stabilization mirror unit, and the image stabilization zoom lens unit. It is used to calculate the adjustment angle of the image stabilization mirror unit according to the light intensity output by the detector, and control the adjustment of the image stabilization mirror unit according to the adjustment angle. It is also used to control the adjustment of the focal length of the image stabilization zoom lens unit according to the solar distance detected by the satellite.

[0013] Furthermore, it also includes a polarization analyzer;

[0014] The polarization analyzer is installed on the optical path between the solar polar orbiting telescope to be image-stabilized and the image stabilization mirror unit, and is used to perform polarization modulation on sunlight.

[0015] Furthermore, the image stabilization zoom lens unit includes a variable magnification lens group, a compensating lens group, and a fixed lens group that are arranged in sequence along the propagation of sunlight, and also includes a first driving mechanism and a second driving mechanism;

[0016] The variable magnification lens group is installed at the driving end of the first driving mechanism and is used to change the focal length of the image stabilization system;

[0017] The compensating lens group is installed at the driving end of the second driving mechanism and is used to compensate the focal plane positions of each zoom gear to make the image planes coincide;

[0018] The position of the fixed lens group is fixed and is used for aberration correction;

[0019] The first driving mechanism is connected to the numerical control unit and is used to receive the control signal of the numerical control unit to drive and change the position of the variable magnification lens group relative to the fixed lens group;

[0020] The second driving mechanism is connected to the numerical control unit and is used to receive the control signal of the numerical control unit to drive and change the position of the compensating lens group relative to the fixed lens group.

[0021] Further, the variable magnification lens group includes a first lens, a second lens, and a third lens that are sequentially arranged on its optical path along the sunlight propagation direction; the first lens, the second lens, and the third lens are all mounted on the driving end of the first driving mechanism; the first lens is a biconvex glass lens with a positive optical power; the second lens is a biconcave glass lens with a negative optical power; the third lens is a biconcave glass lens with a negative optical power;

[0022] The compensation lens group includes a fourth lens and a fifth lens that are sequentially arranged on its optical path along the sunlight propagation direction; the fourth lens and the fifth lens are both mounted on the driving end of the second driving mechanism; the fourth lens is a biconvex glass lens with a positive optical power; the fifth lens is a concavo-convex glass lens with a negative optical power;

[0023] The fixed lens group includes a sixth lens and a seventh lens that are sequentially arranged on its optical path along the sunlight propagation direction; the sixth lens is a concavo-convex glass lens with a negative optical power; the seventh lens is a concavo-convex glass lens with a positive optical power.

[0024] Further, the optical power range of the first lens is 0.02 to 0.03;

[0025] The optical power range of the second lens is -0.015 to -0.025;

[0026] The optical power range of the third lens is -0.025 to -0.035;

[0027] The optical power range of the fourth lens is 0.005 to 0.015;

[0028] The optical power range of the fifth lens is -0.0005 to -0.001;

[0029] The optical power range of the sixth lens is -0.001 to -0.005;

[0030] The optical power range of the seventh lens is 0.003 to 0.006.

[0031] Further, it further includes a beam splitting prism;

[0032] The beam splitting prism is arranged on the sunlight optical path between the image stabilization lens unit and the image stabilization zoom lens unit, and is used to split the sunlight into S light and P light. The S light is reflected to the image stabilization zoom lens unit, and the P light is transmitted for imaging in other optical paths.

[0033] Further, the incident unit includes a first filter lens and a second filter lens that are sequentially arranged on its optical path along the sunlight propagation direction;

[0034] The central thickness of the first filter is 16 mm, its refractive index is 1.4585, and its linear Abbe number is 67.7963;

[0035] The central distance between the near object surface of the second filter and the near image surface of the first filter is 5 mm, its refractive index is 1.4585, and its linear Abbe number is 67.7963.

[0036] Furthermore, the radius of curvature of the near object surface of the first mirror is 42.17 mm, the radius of curvature of its near image surface is -281.75, its central thickness is 7.5 mm, its refractive index is 1.7880, and its linear Abbe number is 47.4917;

[0037] The radius of curvature of the near object surface of the second mirror is -855.45 mm, the radius of curvature of its near image surface is 50.7 mm, the central distance between its near object surface and the near image surface of the first mirror is 4 mm, its central thickness is 6 mm, its refractive index is 1.9459, and its linear Abbe number is 17.9420;

[0038] The radius of curvature of the near object surface of the third mirror is -71.12 mm, the radius of curvature of its near image surface is 60.95 mm, the central distance between its near object surface and the near image surface of the second mirror is 6 mm, its central thickness is 6 mm, its refractive index is 1.9459, and its linear Abbe number is 17.9420;

[0039] The radius of curvature of the near object surface of the fourth mirror is 281.75 mm, the radius of curvature of its near image surface is -128.82 mm, its central thickness is 11 mm, its refractive index is 1.9459, and its linear Abbe number is 17.9420;

[0040] The radius of curvature of the near object surface of the fifth mirror is 72.95 mm, the radius of curvature of its near image surface is 64.54 mm, the central distance between its near object surface and the near image surface of the fourth mirror is 1.5 mm, its central thickness is 10 mm, its refractive index is 1.9459, and its linear Abbe number is 17.9420;

[0041] The radius of curvature of the near object surface of the sixth mirror is -65.01 mm, the radius of curvature of its near image surface is -128.53 mm, its central thickness is 9 mm, its refractive index is 1.4585, and its linear Abbe number is 67.7963;

[0042] The radius of curvature of the near object surface of the seventh mirror is 116.41 mm, the radius of curvature of its near image surface is 273.5 mm, the central distance between its near object surface and the near image surface of the sixth mirror is 1.5 mm, its central thickness is 9 mm, its refractive index is 1.7880, and its linear Abbe number is 47.4917.

[0043] Further, the detector includes a circular bracket, photodiodes S11, S12, S13, and S14 evenly installed around the circumference of the circular bracket, and a light cone M installed at the center of the circular bracket;

[0044] The photodiodes S11, S12, S13, and S14 all face the image stabilization zoom lens unit and are respectively connected to the numerical control unit;

[0045] The small end of the light cone M faces the image stabilization zoom lens unit.

[0046] An image stabilization method for a solar polar orbiting telescope, based on the above-mentioned image stabilization system for a solar polar orbiting telescope, is characterized in that it includes the following steps:

[0047] A. When the detector can receive sunlight and the received sunlight intensity is uniform, the detector directly outputs the sunlight image;

[0048] B. When the detector can receive sunlight and the received sunlight intensity is non-uniform, different light intensity signals are sent to the numerical control unit. The numerical control unit calculates the adjustment angle of the image stabilization lens unit according to the received sunlight intensity, and then controls the adjustment of the image stabilization lens unit according to the adjustment angle until the detector receives uniform sunlight intensity, and then outputs the sunlight image;

[0049] C. When the detector cannot receive sunlight, the numerical control unit controls the adjustment of the image stabilization zoom lens unit according to the sun distance detected by the satellite, thereby changing the focal length of the image stabilization system, so that the detector can receive sunlight, and then steps A or B are executed.

[0050] Advantages of the present invention:

[0051] 1. The image stabilization system and method for a solar polar orbiting telescope provided by the present invention set an image stabilization lens unit and an image stabilization zoom lens unit in the optical path. On the one hand, when the satellite shakes, it can timely adjust the angle of sunlight to perform corresponding compensation, stabilize the solar image, and improve the imaging quality. On the other hand, when the satellite is far from the sun, it can also adjust the system focal length through the image stabilization zoom lens unit to clearly image the sun, thereby overcoming the technical bottleneck that the prior art cannot achieve image stabilization during the process of the satellite using the gravity of Jupiter for long-distance orbit change, and ensuring high-resolution imaging at different satellite-sun distances.

[0052] 2. The image stabilization system and method for a solar polar orbiting telescope provided by the present invention can, through the cooperation among a detector, a numerical control unit, an image stabilization mirror unit, and an image stabilization zoom lens unit, combine spot intensity detection and system zooming to compensate for spot jitter in real time and at high frequency, ensure that the imaging quality is not affected, avoid additional errors introduced by complex algorithms, and achieve the target requirement of clear imaging of the sun under any orbital conditions.

[0053] 3. The image stabilization system for a solar polar orbiting telescope provided by the present invention is provided with a polarization analyzer between the solar polar orbiting telescope and the image stabilization mirror unit, which can perform polarization modulation on the incident sunlight and measure the polarization state of the sunlight.

[0054] 4. The image stabilization system for a solar polar orbiting telescope provided by the present invention is provided with an image stabilization zoom lens unit, which includes a variable magnification lens group, a compensating lens group, and a fixed lens group. By adjusting the positions of the variable magnification lens group and the compensating lens group, the focal length of the image stabilization optical path can be changed in real time according to the orbital position, ensuring that the spot size received by the detector remains unchanged during the orbit change of the solar polar orbiting telescope. When the distance between the solar polar orbiting telescope and the sun increases, the focal length of the image stabilization zoom lens needs to be increased; when the distance between the solar polar orbiting telescope and the sun decreases, the focal length of the image stabilization zoom lens needs to be decreased, so as to achieve image stabilization detection under any orbital conditions. By translating the distance between the variable magnification lens group and the compensating lens group from being far apart to approaching each other, the focal length of the image stabilization optical path changes from small to large, the size of the solar image on the detector is constant, and the focal plane position remains unchanged, ensuring clear images.

[0055] 5. The present invention is provided with a double-layer filter window including a first filter and a second filter, that is, an incident unit, which can realize the preliminary selection of the wavelengths transmitted by the solar polar orbiting telescope and can also play the role of isolating ultraviolet and infrared radiation, further improving the imaging quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 is a schematic structural diagram of an embodiment of the image stabilization system for a solar polar orbiting telescope of the present invention;

[0057] Figure 2 is a schematic structural diagram of the detector in the embodiment of the present invention;

[0058] Figure 3 is an optical path diagram of the short focal length state (focal length 1900.22 mm) of the image stabilization zoom lens unit in the embodiment of the present invention;

[0059] Figure 4 is a modulation transfer function (MTF) diagram of the short focal length state (focal length 1900.22 mm) of the image stabilization zoom lens unit in the embodiment of the present invention;

[0060] Figure 5It is the optical path diagram of the medium focal length state 1 (focal length 2523.32 mm) of the image stabilization zoom lens unit in the embodiment of the present invention;

[0061] Figure 6 It is the modulation transfer function (MTF) diagram of the medium focal length state 1 (focal length 2523.32 mm) of the image stabilization zoom lens unit in the embodiment of the present invention;

[0062] Figure 7 It is the optical path diagram of the medium focal length state 2 (focal length 3855.37 mm) of the image stabilization zoom lens unit in the embodiment of the present invention;

[0063] Figure 8 It is the modulation transfer function (MTF) diagram of the medium focal length state 2 (focal length 3855.37 mm) of the image stabilization zoom lens unit in the embodiment of the present invention;

[0064] Figure 9 It is the optical path diagram of the long focal length state (focal length 5280.83 mm) of the image stabilization zoom lens unit in the embodiment of the present invention;

[0065] Figure 10 It is the modulation transfer function (MTF) diagram of the long focal length state (focal length 5280.83 mm) of the image stabilization zoom lens unit in the embodiment of the present invention.

[0066] Reference numerals in the drawings:

[0067] 10 - Incident unit, 11 - First filter, 12 - Second filter, 20 - Image stabilization solar polar orbiting telescope to be stabilized, 21 - Primary mirror, 22 - Secondary mirror, 23 - Tertiary mirror, 24 - Band - pass filter, 30 - Polarization analyzer, 40 - Image stabilization lens unit, 50 - Beam - splitting prism, 60 - Image stabilization zoom lens unit, 601 - Zoom lens group, 602 - Compensation lens group, 603 - Fixed lens group, 61 - First lens, 62 - Second lens, 63 - Third lens, 64 - Fourth lens, 65 - Fifth lens, 66 - Sixth lens, 67 - Seventh lens. Detailed implementation manners

[0068] Next, the technical solutions of the present invention will be clearly and completely described in conjunction with the accompanying drawings and embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0069] An image stabilization system for a solar polar orbiting telescope provided by an embodiment of the present invention is disposed on a satellite. As Figure 1 shown, the system includes an incident unit 10, a polarization analyzer 30, an image stabilization lens unit 40, a beam - splitting prism 50, an image stabilization zoom lens unit 60, a detector, and a numerical control unit;

[0070] The incident unit 10 is used to be set at the incident end of the image-stabilized solar polar orbiting telescope 20 to screen the sunlight wavelength and isolate ultraviolet and infrared radiation. Specifically, the incident unit 10 includes a first filter 11 and a second filter 12 that are sequentially arranged on its optical path along the sunlight propagation direction. The central thickness of the first filter 11 is 16 mm, its refractive index is 1.4585, and its linear Abbe number is 67.7963. The central distance between the near object surface of the second filter 12 and the near image surface of the first filter 11 is 5 mm, its refractive index is 1.4585, and its linear Abbe number is 67.7963. The double-layer filter window composed of the first filter 11 and the second filter 12 can realize the preliminary selection of the transmission wavelength of the solar polar orbiting telescope and can play the role of isolating ultraviolet and infrared radiation.

[0071] The image-stabilized solar polar orbiting telescope unit 20 includes a primary mirror 21, a secondary mirror 22, a tertiary mirror 23, and a band-pass filter 24 that are sequentially arranged along the sunlight propagation direction. The optical structures of the primary mirror 21, the secondary mirror 22, and the tertiary mirror 23 are respectively double-convex, double-convex, and double-concave lens structures. The entrance pupil is installed on the front end face of the primary mirror 21, which limits the aperture of the full-disk solar telescope. By adjusting the focal length of the image-stabilized solar polar orbiting telescope unit 20, the compression angle of the incident solar rays can be controlled, and the aperture of the rays entering the subsequent image-stabilized zoom unit 60 can be compressed.

[0072] The polarization analyzer 30 is arranged on the optical path between the image-stabilized solar polar orbiting telescope 20 and the image-stabilized mirror unit 40 to perform polarization modulation on the sunlight. The polarization analyzer 30 can realize the polarization modulation of the incident sunlight and measure the polarization state of the incident light.

[0073] The image-stabilized mirror unit 40 is used to be set at the exit end of the image-stabilized solar polar orbiting telescope 20 to adjust the angle of the sunlight. The image-stabilized mirror unit 40 can shorten the length of the image-stabilized solar polar orbiting telescope 20 and can cooperate with the detector to eliminate the high-frequency jitter of the satellite and improve the image resolution.

[0074] The beam-splitting prism 50 is arranged on the sunlight optical path between the image-stabilized mirror unit 40 and the image-stabilized zoom mirror unit 60 to divide the sunlight into S light and P light. The S light is reflected to the image-stabilized zoom mirror unit 60, and the P light is transmitted for imaging in other optical paths.

[0075] The image-stabilized zoom mirror unit 60 is arranged on the optical path of the sunlight after the angle is adjusted by the image-stabilized mirror unit 40. Its incident end corresponds to the image-stabilized mirror unit 40 and is used to adjust the zoom of the image-stabilized system. Specifically, the image-stabilized zoom mirror unit 60 includes a variable magnification lens group 601, a compensating lens group 602, and a fixed lens group 603 that are sequentially arranged along the sunlight propagation direction, and also includes a first driving mechanism and a second driving mechanism.

[0076] The zoom lens group 601 is installed at the driving end of the first driving mechanism and is used to change the focal length of the image stabilization system; the zoom lens group 601 includes a first lens 61, a second lens 62, and a third lens 63 that are sequentially arranged on its optical path along the direction of sunlight propagation; the first lens 61, the second lens 62, and the third lens 63 are all installed at the driving end of the first driving mechanism; the first lens 61 is a double-convex glass lens with a positive optical power; the second lens 62 is a double-concave glass lens with a negative optical power; the third lens 63 is a double-concave glass lens with a negative optical power; the optical power range of the first lens 61 is 0.02 to 0.03; the curvature radius of the near object surface of the first lens 61 is 42.17 mm, the curvature radius of its near image surface is -281.75, its central thickness is 7.5 mm, its refractive index is 1.7880, and its linear Abbe number is 47.4917; the optical power range of the second lens 62 is -0.015 to -0.025; the curvature radius of the near object surface of the second lens 62 is -855.45 mm, the curvature radius of its near image surface is 50.7 mm, the central distance between its near object surface and the near image surface of the first lens 61 is 4 mm, its central thickness is 6 mm, its refractive index is 1.9459, and its linear Abbe number is 17.9420; the optical power range of the third lens 63 is -0.025 to -0.035; the curvature radius of the near object surface of the third lens 63 is -71.12 mm, the curvature radius of its near image surface is 60.95 mm, the central distance between its near object surface and the near image surface of the second lens 62 is 6 mm, its central thickness is 6 mm, its refractive index is 1.9459, and its linear Abbe number is 17.9420;

[0077] The compensation lens group 602 is installed at the driving end of the second driving mechanism and is used to compensate the focal plane positions of each zoom gear to make the image planes coincide; the compensation lens group 602 includes a fourth lens 64 and a fifth lens 65 that are sequentially arranged on its optical path along the direction of sunlight propagation; the fourth lens 64 and the fifth lens 65 are both installed at the driving end of the second driving mechanism; the fourth lens 64 is a double-convex glass lens with a positive optical power; the fifth lens 65 is a concave-convex glass lens with a negative optical power; the optical power range of the fourth lens 64 is 0.005 to 0.015; the curvature radius of the near object surface of the fourth lens 64 is 281.75 mm, the curvature radius of its near image surface is -128.82 mm, its central thickness is 11 mm, its refractive index is 1.9459, and its linear Abbe number is 17.9420; the optical power range of the fifth lens 65 is -0.0005 to -0.001; the curvature radius of the near object surface of the fifth lens 65 is 72.95 mm, the curvature radius of its near image surface is 64.54 mm, the central distance between its near object surface and the near image surface of the fourth lens 64 is 1.5 mm, its central thickness is 10 mm, its refractive index is 1.9459, and its linear Abbe number is 17.9420;

[0078] The position of the fixed lens group 603 is fixed and is used for aberration correction. The fixed lens group 603 includes a sixth lens 66 and a seventh lens 67 that are sequentially arranged on its optical path along the propagation direction of sunlight. The sixth lens 66 is a concavo-convex glass lens with a negative focal power. The seventh lens 67 is a concavo-convex glass lens with a positive focal power. The focal power range of the sixth lens 66 is -0.001 to -0.005. The radius of curvature of the near object surface of the sixth lens 66 is -65.01 mm, its central thickness is 9 mm, its refractive index is 1.4585, and its linear Abbe number is 67.7963. The focal power range of the seventh lens 67 is 0.003 to 0.006. The radius of curvature of the near object surface of the seventh lens 67 is 116.41 mm, the radius of curvature of its near image surface is 273.5 mm, the central distance between its near object surface and the near image surface of the sixth lens 66 is 1.5 mm, its central thickness is 9 mm, its refractive index is 1.7880, and its linear Abbe number is 47.4917.

[0079] The first driving mechanism is connected to the numerical control unit and is used to receive the control signal of the numerical control unit to drive and change the position of the variable magnification lens group 601 relative to the fixed lens group 603.

[0080] The second driving mechanism is connected to the numerical control unit and is used to receive the control signal of the numerical control unit to drive and change the position of the compensation lens group 602 relative to the fixed lens group 603.

[0081] The detector is arranged at the exit end of the image stabilization zoom lens unit 60 and is used to detect the light intensity of sunlight after zooming by the image stabilization zoom lens unit 60. As Figure 2 shown, the detector includes a circular bracket with an inner diameter of φ18.6 mm, photodiodes S11, S12, S13, and S14 that are evenly installed around the circumference of the circular bracket and are all square, and a light cone M installed at the center of the circular bracket. The photodiodes S11, S12, S13, and S14 all face the image stabilization zoom lens unit 60 and are respectively connected to the numerical control unit for detecting the energy in the sun's edge area. The small end of the light cone M faces the image stabilization zoom lens unit 60 and is used to reflect the sunlight at the center of the detector out of the field of view. When the sunlight intensities received by the photodiodes S11, S12, S13, and S14 are the same, the detector does not detect a deviation, and at this time, the sun image is at the exact center of the detector. When a deviation occurs due to satellite jitter and the incident angle, the sunlight intensities received by the photodiodes S11, S12, S13, and S14 are different, and the deviation d of the sun image can be obtained through the differential signal, and the image stabilization mirror unit 40 is swung to ensure that the sun image is always at the exact center of the detector.

[0082] The numerical control unit is respectively connected to the detector, the image stabilization mirror unit 40, and the image stabilization zoom mirror unit 60, and is used to calculate the adjustment angle of the image stabilization mirror unit 40 according to the light intensity output by the detector, control the adjustment of the image stabilization mirror unit 40 according to the adjustment angle, and is also used to control the adjustment of the image stabilization zoom mirror unit 60 according to the solar distance detected by the satellite. Table 1 gives the detailed parameters of each optical element of the image stabilization system in the short focal state.

[0083] Table 1

[0084]

[0085]

[0086] Figure 3 The short focal state (focal length 1900.22 mm) of the image stabilization zoom optical path of the solar polar orbiting telescope is shown. Table 1 shows the detailed parameters of the short focal state (focal length 1900.22 mm) of the image stabilization zoom optical path. Figure 4 It is the modulation transfer function (MTF) graph of the short focal state (focal length 1900.22 mm). The vertical direction represents the contrast, and the horizontal direction represents the spatial frequency. From the curves in the figure, it can be seen that the MTF values of each field of view are all higher than 0.4 at a frequency of 30 lp / mm. Among them, the MTF curve of the 0 field of view is close to the diffraction limit, indicating that its contrast is good and the imaging quality is high. Moving the variable magnification lens group 601 and the compensating lens group 602 can adjust the focal length f of the image stabilization zoom optical path so that the diameter of the solar image on the detector is constantly φ18.6 mm.

[0087] Translating the variable magnification lens group 601 12 mm along the direction of sunlight propagation and translating the compensating lens group 602 8.26 mm in the opposite direction of sunlight propagation can obtain Figure 5 The first intermediate focal state (focal length 2523.32 mm) of the image stabilization zoom optical path of the solar polar orbiting telescope. Figure 6 It is the modulation transfer function (MTF) graph of the first intermediate focal state (focal length 2523.43 mm). The vertical direction represents the contrast, and the horizontal direction represents the spatial frequency. From the curves in the figure, it can be seen that the MTF values of each field of view are all higher than 0.4 at a frequency of 30 lp / mm. Among them, the MTF curve of the 0 field of view is close to the diffraction limit, indicating that its contrast is good and the imaging quality is high.

[0088] Continuing to translate the variable magnification group 601 12 mm along the direction of sunlight propagation and translating the compensating group 602 20.97 mm in the opposite direction of sunlight propagation can obtain Figure 7 The second intermediate focal state (focal length 3855.37 mm) of the image stabilization zoom optical path of the solar polar orbiting telescope. Figure 8It is the modulation transfer function (MTF) graph for the second state of the middle focal length (focal length: 3855.37 mm). The contrast is represented in the vertical direction, and the spatial frequency is represented in the horizontal direction. From the curves in the graph, it can be seen that the MTF values of each field of view are all higher than 0.3 at a frequency of 30 lp / mm. Among them, the MTF curve of the 0th field of view is close to the diffraction limit, indicating good contrast and high imaging quality.

[0089] Continue to translate the variable magnification group 601 by 7.2 mm along the direction of sunlight propagation, and translate the compensation group 602 by 18.67 mm in the opposite direction of sunlight propagation to obtain Figure 9 The long focal length state (focal length: 5280.83 mm) of the image stabilization zoom optical path of the solar polar orbiting telescope. Figure 10 It is the modulation transfer function (MTF) graph for the long focal length state (focal length: 5280.83 mm). The contrast is represented in the vertical direction, and the spatial frequency is represented in the horizontal direction. From the curves in the graph, it can be seen that the MTF values of each field of view are all higher than 0.12 at a frequency of 30 lp / mm. Among them, the MTF curve of the 0th field of view is close to the diffraction limit, indicating good contrast and high imaging quality.

[0090] Table 2 gives the detailed parameters of the four zoom states corresponding to the image stabilization zoom optical path at different solar distances.

[0091] Table 2

[0092]

[0093] The method for image stabilization using the above image stabilization system for the solar polar orbiting telescope includes the following steps:

[0094] A. When the detector can receive sunlight and the received sunlight intensity is uniform, the detector directly outputs the sunlight image.

[0095] B. When the detector can receive sunlight and the received sunlight intensity is non-uniform, different light intensity signals are sent to the numerical control unit. The numerical control unit calculates the adjustment angle of the image stabilization mirror unit 40 based on the received sunlight intensity, and then controls the adjustment of the image stabilization mirror unit 40 according to the adjustment angle until the detector receives uniform sunlight intensity, and then outputs the sunlight image.

[0096] C. When the detector cannot receive sunlight, the numerical control unit controls the adjustment of the image stabilization zoom mirror unit 60 according to the solar distance detected by the satellite, thereby changing the focal length of the image stabilization system so that the detector can receive sunlight, and then execute step A or B.

[0097] As described above, it is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims described.

Claims

1. An image stabilization system for a solar polar orbit telescope, arranged on a satellite, characterized in that: It comprises an incident unit (10), an image stabilizing mirror unit (40), an image stabilizing zoom mirror unit (60), a detector and a digital control unit; The incident unit (10) is used to be arranged at the incident end of the stabilized solar polar orbit telescope (20) to screen the wavelength of sunlight and isolate ultraviolet and infrared radiation; The image stabilizing mirror unit (40) is used to be arranged at the emission end of the solar polar orbit telescope (20) to be stabilized, so as to adjust the angle of sunlight; The image stabilizing zoom lens unit (60) is arranged on the optical path of the sunlight after the angle is adjusted by the image stabilizing lens unit (40), and its incident end corresponds to the image stabilizing lens unit (40), and is used to adjust the zoom of the image stabilizing system; The detector is arranged at the emission end of the image stabilizing zoom lens unit (60) and is used to detect the light intensity of sunlight after being zoomed by the image stabilizing zoom lens unit (60); The numerical control unit is respectively connected to the detector, the image stabilizing mirror unit (40) and the image stabilizing zoom mirror unit (60), and is used to calculate the adjustment angle of the image stabilizing mirror unit (40) according to the light intensity output by the detector, and to control the image stabilizing mirror unit (40) to adjust the angle according to the adjustment angle, and is also used to control the focal length of the image stabilizing zoom mirror unit (60) according to the distance of the sun detected by the satellite.

2. The image stabilization system for a solar polar orbit telescope according to claim 1, characterized in that: Also included is a polarization analyzer (30); The polarization analyzer (30) is arranged on the optical path between the solar polar orbit telescope (20) to be stabilized and the image stabilization mirror unit (40) and is used for performing polarization modulation on sunlight.

3. The image stabilization system for a solar polar orbit telescope according to claim 2, characterized in that: The image stabilizing zoom lens unit (60) comprises a variable magnification lens group (601), a compensation lens group (602) and a fixed lens group (603) which are sequentially arranged along the propagation of sunlight, and also comprises a first driving mechanism and a second driving mechanism; The variable magnification lens group (601) is installed at the driving end of the first driving mechanism and is used to change the focal length of the image stabilization system; The compensating lens group (602) is installed at the driving end of the second driving mechanism and is used to compensate the focal plane positions of each zoom gear to make them share the same image plane; The fixed mirror group (603) is fixed in position and is used for aberration correction; The first driving mechanism is connected to the numerical control unit and is used to receive a control signal from the numerical control unit to drive and change the position of the variable magnification lens group (601) relative to the fixed lens group (603); The second driving mechanism is connected to the numerical control unit and is used to receive a control signal from the numerical control unit to drive the change of the position of the compensation mirror group (602) relative to the fixed mirror group (603).

4. The image stabilization system for a solar polar orbit telescope according to claim 3, characterized in that: The variable power lens group (601) comprises a first mirror (61), a second mirror (62) and a third mirror (63) which are sequentially arranged on the optical path of sunlight along the propagation direction thereof; the first mirror (61), the second mirror (62) and the third mirror (63) are all mounted on the driving end of the first driving mechanism; the first mirror (61) is a biconvex glass lens with positive optical power; the second mirror (62) is a biconcave glass lens with negative optical power; and the third mirror (63) is a biconcave glass lens with negative optical power; The compensation mirror group (602) comprises a fourth mirror (64) and a fifth mirror (65) which are sequentially arranged on the optical path of the sunlight along the propagation direction thereof; the fourth mirror (64) and the fifth mirror (65) are both mounted on the driving end of the second driving mechanism; the fourth mirror (64) is a biconvex glass lens with positive optical power; the fifth mirror (65) is a concave-convex glass lens with negative optical power; The fixed mirror group (603) comprises a sixth mirror (66) and a seventh mirror (67) which are sequentially arranged on the optical path of the sunlight along the propagation direction thereof; the sixth mirror (66) is a concave-convex glass lens with negative optical power; and the seventh mirror (67) is a concave-convex glass lens with positive optical power.

5. The image stabilization system for a solar polar orbit telescope according to claim 4, characterized in that: The focal power of the first mirror (61) is in the range of 0.02 to 0.03; The focal power of the second mirror (62) ranges from -0.015 to -0.025; The focal power of the third mirror (63) is in the range of -0.025 to -0.035; The focal power of the fourth mirror (64) is in the range of 0.005 to 0.015; The focal power range of the fifth mirror (65) is -0.0005 to -0.001; The focal power range of the sixth mirror (66) is -0.001 to -0.005; The focal power of the seventh mirror (67) is in the range of 0.003 to 0.

006.

6. The image stabilization system for a solar polar orbit telescope according to claim 5, characterized in that: Also includes a beam splitter prism (50); The beam splitter prism (50) is arranged on the sunlight light path between the image stabilizing lens unit (40) and the image stabilizing zoom lens unit (60) and is used to split the sunlight into S light and P light, the S light being reflected to the image stabilizing zoom lens unit (60) and the P light being transmitted for imaging in other light paths.

7. The image stabilization system for a solar polar orbit telescope according to claim 5, characterized in that: The incident unit (10) comprises a first filter (11) and a second filter (12) which are sequentially arranged on the optical path of the sunlight along the propagation direction of the sunlight; The center thickness of the first filter (11) is 16 mm, its refractive index is 1.4585, and its linear Abbe number is 67.7963; The center distance between the near object surface of the second filter (12) and the near image surface of the first filter (11) is 5 mm, its refractive index is 1.4585, and its linear Abbe number is 67.7963.

8. The image stabilization system for a solar polar orbit telescope according to claim 7, characterized in that: The first mirror (61) has a near object surface curvature radius of 42.17 mm, a near image surface curvature radius of -281.75, a center thickness of 7.5 mm, a refractive index of 1.7880, and a linear Abbe number of 47.4917; The curvature radius of the near object surface of the second mirror (62) is -855.45 mm, the curvature radius of the near image surface is 50.7 mm, the center distance between the near object surface and the near image surface of the first mirror (61) is 4 mm, the center thickness is 6 mm, the refractive index is 1.9459, and the linear Abbe number is 17.9420; The radius of curvature of the near object surface of the third mirror (63) is -71.12 mm, the radius of curvature of the near image surface is 60.95 mm, the center distance between the near object surface and the near image surface of the second mirror (62) is 6 mm, the center thickness is 6 mm, the refractive index is 1.9459, and the linear Abbe number is 17.9420; The fourth mirror (64) has a near object surface curvature radius of 281.75 mm, a near image surface curvature radius of -128.82 mm, a center thickness of 11 mm, a refractive index of 1.9459, and a linear Abbe number of 17.9420; The fifth mirror (65) has a near object surface curvature radius of 72.95 mm, a near image surface curvature radius of 64.54 mm, a center distance between the near object surface and the near image surface of the fourth mirror (64) of 1.5 mm, a center thickness of 10 mm, a refractive index of 1.9459, and a linear Abbe number of 17.9420; The sixth mirror (66) has a near object surface curvature radius of -65.01 mm, a near image surface curvature radius of -128.53 mm, a center thickness of 9 mm, a refractive index of 1.4585, and a linear Abbe number of 67.7963; The curvature radius of the near object surface of the seventh mirror (67) is 116.41 mm, the curvature radius of the near image surface is 273.5 mm, the center distance between the near object surface and the near image surface of the sixth mirror (66) is 1.5 mm, the center thickness is 9 mm, the refractive index is 1.7880, and the linear Abbe number is 47.4917.

9. The image stabilization system for a solar polar orbit telescope according to any one of claims 1 to 8, characterized in that: The detector comprises a circular bracket, a photodiode S11, a photodiode S12, a photodiode S13 and a photodiode S14 uniformly mounted on the circular bracket around the circumference, and a light cone M mounted at the center of the circular bracket; The photodiode S11, the photodiode S12, the photodiode S13 and the photodiode S14 are all facing the image stabilizing zoom lens unit (60) and are respectively connected to the digital control unit; The small end of the light cone M faces the image stabilizing zoom lens unit (60).

10. An image stabilization method for a solar polar orbit telescope, based on the image stabilization system for a solar polar orbit telescope according to any one of claims 1 to 9, characterized in that: The following steps are involved: A. When the detector can receive sunlight and the received sunlight intensity is uniform, the detector directly outputs the sunlight image; B. When the detector is able to receive sunlight and the intensity of the received sunlight is uneven, different intensity signals are sent to the numerical control unit, and the numerical control unit calculates the adjustment angle of the image stabilizing mirror unit (40) according to the intensity of the received sunlight, and then controls and adjusts the image stabilizing mirror unit (40) according to the adjustment angle until the detector receives uniform sunlight intensity, and then outputs a sunlight image; C. When the detector cannot receive sunlight, the numerical control unit controls and adjusts the image stabilization zoom lens unit (60) according to the distance of the sun detected by the satellite, thereby changing the focal length of the image stabilization system so that the detector can receive sunlight, and then executes step A or B.

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