MPO focusing imaging non-uniformity-based detection device and positioning method

Abstract

The invention discloses a detection device based on MPO focusing imaging non-uniformity and a positioning method. The detection device comprises a main detector, a vertical arm detector, a horizontal arm detector and a background detector which are deployed on a focal plane of a lobster eye X-ray micropore optical device MPO; the imaging information of a target source on the focal plane when the target source normally enters the lobster eye X-ray micropore optical device MPO comprises a cross arm and a plurality of diffuse scattering plaque areas. During positioning, the data processing unit judges the position of the target source according to the relative counting change rate of the main detector, the vertical arm detector and the horizontal arm detector. According to the invention, the positioning capability of the single-pixel SDD main detector is greatly improved, the positioning precision can reach seven points, and the positioning capability of a large-field-of-view sky patrol telescope can be matched. The invention also provides a meaningful and heuristic thought for improving the positioning capability for other satellites.

Description

Technical Field

[0001] The invention belongs to the field of X-ray astronomical observation, and in particular relates to a detection device and a positioning method based on MPO focusing imaging inhomogeneity. Background Art

[0002] In the field of X-ray astronomical observation, people are very concerned about how to improve the ability of astronomical satellites to locate target sources. The improvement of this ability can provide scientists with clearer and more accurate astronomical data, thereby promoting in-depth research on various X-ray sources in the universe. The observation capability of X-ray astronomical satellites depends on the two scientific payloads they carry: focusing mirrors and detectors. At present, Chandra is the X-ray astronomical satellite with the best angular resolution. It uses precision-machined focusing mirrors and large-area detector arrays, and the angular resolution can reach 0.5 arc seconds. However, Chandra's development cycle is very long, the large-area detector array is expensive, and the technology for manufacturing such a precise focusing mirror is difficult to replicate. In addition, the focusing mirror weighs 956.4kg and requires a large satellite platform to carry it. Due to the constraints or influence of factors such as price, technology, payload mass, development time, and scientific goals, each satellite has certain trade-offs in the selection of detectors and focusing mirrors. For example, smaller satellite platforms are usually not equipped with focusing mirrors, and only use collimators to collimate the light.

[0003] The "All-Variable Source Tracking Hunter Constellation" (CATCH) program is a space astronomy project that plans to establish an intelligent control constellation consisting of 126 microsatellites. CATCH-1 is the first test satellite of CATCH. As a microsatellite, the focusing mirror equipped with CATCH-1 is a new type of lightweight X-ray focusing mirror: lobster-eye X-ray micro-aperture optics (MPO), and the focusing mirror weighs only 536.9g. The scientific goal of CATCH-1 is time-varying observation, so the silicon drift detector (SDD) with advantages in observing strong sources was selected. Due to the technical difficulty of the SDD detector array and considering the cost factor, the focal plane detector of CATCH-1 consists of 4 SDD probes. The SDD detector has no imaging capability and can only record the counts in each detector. If the traditional uniform arrangement method is used, it can only be judged whether the observed target source is within or outside the field of view. Summary of the invention

[0004] In order to overcome the insufficient positioning capability of small satellite platforms, the present invention provides a detection device and a positioning method based on MPO focusing imaging non-uniformity, which can greatly improve the positioning capability using a focal plane detector.

[0005] The technical solution of the present invention is:

[0006] A detection device based on MPO focusing imaging non-uniformity, characterized in that it comprises a main detector, a vertical arm detector, a horizontal arm detector and a background detector deployed on the focal plane of a lobster eye X-ray micro-hole optical device MPO; when a target source is incident on the lobster eye X-ray micro-hole optical device MPO, the imaging information on the focal plane comprises a cross arm and a plurality of diffuse scattering patch areas; wherein,

[0007] The main detector is arranged at the center of the focal plane;

[0008] The vertical arm detector and the horizontal arm detector are respectively located on the cross arm;

[0009] The background detector is arranged in any of the diffuse scattering patch areas.

[0010] Furthermore, the vertical arm detector is located on the vertical arm of the cross arm, and the horizontal arm detector is located on the horizontal arm of the cross arm; the vertical arm detector and the horizontal arm detector are at the same distance from the center of the cross arm.

[0011] Furthermore, the vertical arm detector is located above the main detector, the horizontal arm detector is located on the left side of the main detector, and the background detector is located in the lower right area of ​​the main detector.

[0012] Furthermore, the main detector, the vertical arm detector, the horizontal arm detector and the background detector are all SDD detectors.

[0013] A positioning system, characterized in that it comprises a lobster eye X-ray micro-hole optical device MPO, a detection device and a data processing unit; wherein,

[0014] The lobster eye X-ray micro-aperture optical device MPO is used to receive the rays from the target source and image them onto the focal plane;

[0015] The detection device is arranged at the focal plane of the lobster eye X-ray micro-aperture optical device MPO, and is used to detect the imaging information of the lobster eye X-ray micro-aperture optical device MPO on the target source and send it to the data processing unit;

[0016] The data processing unit is used to locate the position of the target source according to the counts of the main detector, the vertical arm detector, and the horizontal arm detector.

[0017] Furthermore, the method for locating the position of the target source by the data processing unit is as follows: the data processing unit stores the relative count T of the vertical arm detector and the count of the main detector when the target source is incident on the lobster eye X-ray micro-hole optical device MPO. 10 , the relative count of the horizontal arm detector and the main detector T20 The data processing unit calculates the relative count T of the vertical arm detector and the main detector based on the counts of the main detector, the vertical arm detector, and the horizontal arm detector. 11 , the relative count of the horizontal arm detector and the main detector T 21 The data processing unit is based on the relative count T 11 Relative count T 10 The rate of change, relative count T 21 Relative count T 20 The rate of change of determines the deflection angle and deflection direction of the target source within the field of view.

[0018] A positioning method based on the detection device, the steps of which include:

[0019] 1) The detection device is arranged at the focal plane of the lobster eye X-ray micro-hole optical device MPO to detect the imaging information of the lobster eye X-ray micro-hole optical device MPO on the target source and send it to the data processing unit; the data processing unit stores the relative count T of the vertical arm detector and the count of the main detector when the target source is incident on the lobster eye X-ray micro-hole optical device MPO. 10 , the relative count of the horizontal arm detector and the main detector T 20 ;

[0020] 2) The data processing unit calculates the relative count T of the count of the vertical arm detector and the count of the main detector based on the counts of the main detector, the vertical arm detector, and the horizontal arm detector. 11 , the relative count of the horizontal arm detector and the main detector T 21 ;

[0021] 3) The data processing unit calculates the relative count T 11 Relative count T 10 The rate of change, relative count T 21 Relative count T 20 The rate of change of determines the deflection angle and deflection direction of the target source within the field of view.

[0022] Further, the data processing unit simulates the relative counts T between the counts of the vertical arm detector and the counts of the main detector when the target source is incident on the lobster eye X-ray micro-hole optical device MPO. 10 , the relative count of the horizontal arm detector and the main detector T 20 , and the relative counts T1 of the vertical arm detector and the main detector when simulating the target source at each non-normal incidence detection of the lobster eye X-ray micro-aperture optical device MPO ’, the relative count of the horizontal arm detector and the main detector T2 ’ ; Then determine the relative count T1 corresponding to the target source at various deflection angles and deflection directions in the field of view ’ Relative count T 10 The rate of change, relative count T2 ’ Relative count T 20 Then generate a positioning table or positioning map according to the simulation results; in step 3), the data processing unit according to the relative count T 11 Relative count T 10 The rate of change, relative count T 21 Relative count T 20 Refer to the positioning table or positioning map to determine the deflection angle and deflection direction of the target source in the field of view.

[0023] Furthermore, the data processing unit is based on the relative count T 11 Relative count T 10 The rate of change of determines the deflection angle and deflection direction of the target source in the horizontal direction of the field of view. According to the relative count T 21 Relative count T 20 The rate of change of the vertical deflection angle and the deflection direction of the target source in the field of view are determined; then the deflection angle and the deflection direction of the target source in the field of view are determined according to the vertical and horizontal deflection angles and the deflection directions of the target source in the field of view.

[0024] The advantages of the present invention are as follows:

[0025] The present invention realizes the positioning of target sources by low-cost, short-period, and light-mass micro-satellites. Specifically, the present invention enables detectors without positioning capabilities to have positioning capabilities, and the positioning accuracy can reach 7 arc minutes, which matches the positioning capability of large-field survey telescopes. The present invention also provides a meaningful and inspiring idea for improving the positioning capability of other satellites. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Typical cross-shaped imaging of the MPO focusing mirror used for CATCH-1 and the positions of the four SDD detectors.

[0027] Figure 2 These are the results of simulated observations of target sources from four different positions within the field of view.

[0028] Figure 3 It is the change rate of the relative counts of the two cross-arm detectors when the target source is located at various off-axis angles and off-axis directions.

[0029] Figure 4 This is a flowchart for positioning analysis and processing.

[0030] Figure 5 This is the structural principle diagram of the detection device. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention but not to limit the scope of the present invention.

[0032] Figure 1 It is the image of the parallel light incident on the positive axis after being focused by the MPO focusing lens used by CATCH-1 on the focal plane. The brighter the color, the more photons are gathered here. It can be seen that the image of the MPO focusing lens has a typical cross-shaped feature. The image on the focal plane consists of three parts: a bright focal spot in the center, two mutually perpendicular cross arms, and diffuse scattering patches. Figure 1 The four red circles in the figure are the layout positions of the four SDD detectors. The one located on the central focal spot is the main detector, the ones located on the two cross arms are cross arm detectors, which are used to assist in positioning, and the one placed in the diffuse scattering patch in the lower right corner is the background detector, which is used to measure the background. Since the SDD detector cannot form an image, in actual observations, only the total count in each detector can be known. The field of view of CATCH-1 is 0.4°×0.4°. If only the main detector is used, it can only be determined whether the target source is within or outside the field of view, and more accurate positioning cannot be performed. Based on the unevenness of MPO imaging, the satellite's positioning capability can be improved by using the detectors on the two cross arms.

[0033] Figure 2 This is the result of simulating observations of a target source at four different positions in the field of view. The first position is normal axis incidence, and the next three positions are off-axis incidence. The off-axis angles are all 9 arc minutes, but the off-axis directions are different. Figure 2 Describe how to locate the target source using this layout of detectors. Figure 2 The first row shows the simulated imaging results of the target sources incident at four different positions at the four detector positions after being focused by the MPO focusing lens; since the SDD detector cannot provide position information, only the total count of each detector is known, so Figure 2 The second row of shows the total counts in each detector for these four cases; for ease of comparison, Figure 2The third row shows the relative counts of each detector: the relative count of the central main detector is set to 1, and the relative counts of the three surrounding detectors are the ratio of their counts to the count of the central detector. Based on the non-uniformity of MPO focusing imaging, the principle that the two detectors placed on the cross arm can improve the satellite's ability to locate the target source is that when the target source is off-axis incident, the relative counts of the cross arm detectors will change compared to the on-axis incidence of the target source. In order to intuitively reflect the changes in the relative counts of the detectors, Figure 2 The rate of change of the relative counts is marked below the relative counts in the third row: the rate of change is the percentage change in the relative counts of the detector compared to the positive axis incidence. In actual observation, the position of the target source can be determined based on the rate of change of the relative counts. Specifically, when the target source is offset in the horizontal direction, the vertical cross arm will move out of the vertical arm detector, causing the count detected by the vertical arm detector to be significantly reduced; when the target source is offset in the vertical direction, the horizontal cross arm will move out of the horizontal arm detector, causing the count detected by the horizontal arm detector to be significantly reduced; when the target source is offset in both the vertical and horizontal directions, the counts of the two cross arm detectors will change. We make inferences and judgments based on the changes in the relative counts of the two cross arm detectors, and can use simulations for comparison when necessary to roughly determine the off-axis angle and off-axis direction of the target source. Figure 2 Take the second column as an example. At this time, the relative count of the horizontal arm detector has decreased significantly, while the relative count of the vertical arm detector has not changed significantly. We can judge that the target source is offset in the vertical direction, that is, 0° or 180°, causing the horizontal cross arm to move out of the horizontal arm detector. The count detected by the detector is significantly reduced. The off-axis angle of the target source can be judged based on the relative count change rate of the horizontal arm detector. At the same time, since the cross arm formed by focusing has larger counts closer to the center focal spot, even if the off-axis angle is the same, the relative count change rate of the vertical cross arm at 0° and 180° in the off-axis direction is different. Therefore, the off-axis direction of the target source can be judged based on the relative count change rate of the vertical arm detector. We simulated the situation where the target source is located at various off-axis angles and off-axis directions. The change rates of the two cross arm detectors at various off-axis angles and off-axis directions are as follows. Figure 3 As shown in Figure 1, considering the statistical error, the conclusion is that the positioning accuracy can reach 7 arc minutes using this layout of detectors. In actual observation, the relative counts of the two cross-arm detectors are calculated, and the location of the target source can be determined by reasoning and comparing with the simulation results. The analysis and processing flow is as follows: Figure 4 shown.

[0034] The present invention has been applied to the first test satellite CATCH-1 of the CATCH project. Figure 5 It is the structural principle diagram of the detection device. Figure 5 In the figure, the main detector 1 is located in the center and can detect the central focal spot; the vertical cross arm detector 2 and the horizontal arm detector 3 are located on the two cross arms respectively, and the angle between the vertical arm detector 2 and the horizontal arm detector 3 and the main detector position is 90°, which is used to assist positioning; the background detector 4 can be placed in any diffuse scattering patch, does not detect the focused signal, and is used to measure the background. The second test satellite CATCH-2 in the future is also planned to adopt the same detector layout method.

[0035] Although the specific embodiments of the present invention are disclosed for the purpose of illustration, the purpose is to help understand the content of the present invention and implement it accordingly, those skilled in the art will understand that various substitutions, changes and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the present invention should not be limited to the content disclosed in the best embodiment, and the scope of the present invention is subject to the scope defined in the claims.

Claims

1. A detection device based on MPO focusing imaging inhomogeneity, characterized in that: It includes a main detector, a vertical arm detector, a horizontal arm detector and a background detector deployed on the focal plane of a lobster eye X-ray micro-hole optical device MPO; when a target source is incident on the lobster eye X-ray micro-hole optical device MPO, the imaging information on the focal plane includes a cross arm and a plurality of diffuse scattering patch areas; wherein, The main detector is arranged at the center of the focal plane; The vertical arm detector and the horizontal arm detector are respectively located on the cross arm; The background detector is arranged in any of the diffuse scattering patch areas.

2. The detection device according to claim 1, characterized in that: The vertical arm detector is located on the vertical arm of the cross arm, and the horizontal arm detector is located on the horizontal arm of the cross arm; the vertical arm detector and the horizontal arm detector are at the same distance from the center of the cross arm.

3. The detection device according to claim 2, characterized in that: The vertical arm detector is located above the main detector, the horizontal arm detector is located on the left side of the main detector, and the background detector is located in the lower right area of ​​the main detector.

4. The detection device according to claim 1, 2 or 3, characterized in that: The main detector, the vertical arm detector, the horizontal arm detector and the background detector are all SDD detectors.

5. A positioning system, characterized in that: It comprises a lobster eye X-ray micro-hole optical device MPO, a detection device as claimed in claim 1 and a data processing unit; wherein, The lobster eye X-ray micro-aperture optical device MPO is used to receive the rays from the target source and image them onto the focal plane; The detection device is arranged at the focal plane of the lobster eye X-ray micro-aperture optical device MPO, and is used to detect the imaging information of the lobster eye X-ray micro-aperture optical device MPO on the target source and send it to the data processing unit; The data processing unit is used to locate the position of the target source according to the counts of the main detector, the vertical arm detector, and the horizontal arm detector.

6. The positioning system according to claim 5, characterized in that: The method for locating the position of the target source by the data processing unit is as follows: the data processing unit stores the relative count T of the vertical arm detector and the main detector when the target source is incident on the lobster eye X-ray micro-aperture optical device MPO. 10 , the relative count of the horizontal arm detector and the main detector T 20 The data processing unit calculates the relative count T of the vertical arm detector and the main detector based on the counts of the main detector, the vertical arm detector, and the horizontal arm detector. 11 , the relative count of the horizontal arm detector and the main detector T 21 The data processing unit is based on the relative count T 11 Relative count T 10 The rate of change, relative count T 21 Relative count T 20 The rate of change of determines the deflection angle and deflection direction of the target source within the field of view.

7. A positioning method based on the detection device according to claim 1, the steps comprising: 1) The detection device of claim 1 is arranged at the focal plane of the lobster eye X-ray micro-hole optical device MPO, for detecting the imaging information of the lobster eye X-ray micro-hole optical device MPO on the target source and sending it to a data processing unit; the data processing unit stores the relative count T of the count of the vertical arm detector and the count of the main detector when the target source is incident on the lobster eye X-ray micro-hole optical device MPO. 10 , the relative count of the horizontal arm detector and the main detector T 20 ; 2) The data processing unit calculates the relative count T of the count of the vertical arm detector and the count of the main detector based on the counts of the main detector, the vertical arm detector, and the horizontal arm detector. 11 , the relative count of the horizontal arm detector and the main detector T 21 ; 3) The data processing unit calculates the relative count T 11 Relative count T 10 The rate of change, relative count T 21 Relative count T 20 The rate of change of determines the deflection angle and deflection direction of the target source within the field of view.

8. The method according to claim 7, characterized in that The data processing unit simulates the relative counts of the vertical arm detector and the main detector when the target source is incident on the lobster eye X-ray micro-aperture optical device MPO. 10 , the relative count of the horizontal arm detector and the main detector T 20 , and the relative counts T1 of the vertical arm detector and the main detector when simulating the target source at each non-normal incidence detection lobster eye X-ray micro-aperture optical device MPO ’ , the relative count of the horizontal arm detector and the main detector T2 ’ ; Then determine the relative count T1 corresponding to the target source at various deflection angles and deflection directions in the field of view ’ Relative count T 10 The rate of change, relative count T2 ’ Relative count T 20 Then generate a positioning table or positioning map according to the simulation results; in step 3), the data processing unit according to the relative count T 11 Relative count T 10 The rate of change, relative count T 21 Relative count T 20 Refer to the positioning table or positioning map to determine the deflection angle and deflection direction of the target source in the field of view.

9. The method according to claim 7, characterized in that: The data processing unit is based on the relative count T 11 Relative count T 10 The rate of change of determines the deflection angle and deflection direction of the target source in the horizontal direction of the field of view. According to the relative count T 21 Relative count T 20 The rate of change of the vertical deflection angle and the deflection direction of the target source in the field of view are determined; then the deflection angle and the deflection direction of the target source in the field of view are determined according to the vertical and horizontal deflection angles and the deflection directions of the target source in the field of view.

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