An embedded full-solar-face guiding device for a horizontal solar telescope

Abstract

The application provides an embedded full-solar-face guiding device for a horizontal solar telescope, and relates to the field of precise tracking control of a solar telescope. The device comprises a full-solar-face imaging optical system and an embedded full-solar-face guiding system. The full-solar-face imaging optical system images the sun in a white light wave band and is composed of a front neutral light reducer, a complex achromatic imaging mirror and a filter. The embedded full-solar-face guiding system is integrated on a circuit board and is composed of six parts, namely, a CMOS image sensor chip, an FPGA core processor chip, an image buffer chip, a power distribution and management system, a USB communication serial port and a GigE communication network port. The optical axis of the embedded full-solar-face guiding device is parallel to the optical axis of the horizontal solar telescope and is installed in the lens barrel of the horizontal solar telescope. The application can improve the tracking precision of the horizontal solar telescope on the sun.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of precise tracking control of solar telescope, in particular to an embedded full-disk guiding device for a horizontal solar telescope. BACKGROUND

[0002] With the deepening of solar physics research, many large-scale solar telescopes with meter-level aperture have been built at home and abroad to achieve high spatial and temporal resolution imaging, spectrum, and magnetic field observation. These large-scale solar telescopes are generally tracking frames with horizontal structure, also commonly known as horizontal solar telescopes, and all need to track the sun with high precision. Photoelectric guiding is one of the technical means to achieve this goal.

[0003] During the tracking of the sun, the image of the sun will gradually drift in the observation field of view due to the influence of factors such as manufacturing and installation errors caused by imperfections in the manufacture and installation of the optical-mechanical system, atmospheric refraction changes with atmospheric temperature, humidity and air pressure, and encoder detection errors, thereby reducing the tracking ability of the telescope on the sun. If not corrected in time, the sun will run out of the field of view of the telescope, causing the telescope to malfunction. The commonly used technical means to solve this problem are: one is to establish a pointing model by measuring the pointing error of the running sky area of the telescope in advance, and to make a theoretical correction to improve the pointing and tracking accuracy of the telescope, but the accuracy of this method is limited, and the model will become inaccurate over time and with environmental changes, so it needs to be modeled regularly, which will affect the operation efficiency of the telescope and increase the operation cost; the other is to detect the movement of the sun image in real time and feed back to the pointing and tracking control system for closed-loop correction, which has high accuracy but increases the additional software and hardware system and the development cost of the telescope. Real-time correction of image closed loop can be divided into local image closed loop correction and full-disk image closed loop correction. Local image closed loop correction is called correlation tracking in solar telescopes. Due to the limited travel of this system, it is usually used to correct the high-frequency image jitter caused by atmospheric turbulence, and is a very complex and expensive technology, which is only equipped on some special large solar telescopes. Since the field of view of a large solar telescope is usually about 3'x3', only about 1% of the solar disk is observed, if the imaging quality of the telescope or the atmospheric seeing of the place where the telescope is placed is not good, the image is blurred, it is difficult to detect the movement of the sun image through the local image of the sun, and it is often only applicable to sunspots, which are active targets on the solar disk. Full-disk image correction is called full-disk guiding in solar telescopes. It is to install a small telescope of about ten centimeters in diameter on the barrel of a large solar telescope to image the sun, and to collect images through a camera and process the images through an industrial computer to calculate the tracking error and feed back to the pointing and tracking control system of the telescope for image closed loop. This technology is relatively simple in software and hardware and technology compared with correlation tracking, and its main function is to correct slow and large tracking errors. The full-disk guiding technology has been applied to the one-meter New Vacuum Solar Telescope (NVST) of Yunnan Observatory, the one-meter off-axis solar telescope (AIMS) of the National Astronomical Observatory for the measurement of mid-infrared solar magnetic fields, the Huairou Solar Magnetic Field Telescope, and the Dunn Solar Telescope (DST) of the United States.

[0004] The full-disk guiding technology is a kind of precision detection and control technology integrating optics, mechanics and electronics, which benefits from the development of camera technology, computer technology and network technology. It mainly includes a full-disk imaging telescope (a guiding telescope), a plane array camera, an image acquisition computer, image processing software and a feedback signal transmission network. The full-disk imaging telescope is used for imaging the entire sun, i.e. a full-disk image. The image acquisition camera in the early stage adopts a CCD camera, i.e. a full-disk guiding based on a CCD. With the development of CMOS camera technology, its performance, frame size and readout speed can meet the requirements of a full-disk camera. The hardware platform of image acquisition, error calculation and signal feedback adopts an industrial computer, and the software runs on a WINDOWS platform. The full-disk imaging telescope is placed on the main rack of a large solar telescope, and the optical axis needs to be strictly parallel to the main optical axis of the main optical system. The CMOS camera is tightly coupled and installed at the rear end of the full-disk imaging telescope. The image of the camera is transmitted to the image acquisition and error calculation computer in the observation room 30 meters away through a USB extension line or an Ethernet. After the computer calculates the tracking error, the error signal is transmitted back to the pointing and tracking system near the telescope for fine adjustment of the telescope, so as to realize closed-loop control.

[0005] The full-disk guiding system has the characteristics of technical discretization, system discretization, large hardware volume, large installation space span and deep coupling dependence on the original system of the telescope. First, it needs to consider whether the full-disk imaging telescope of company A is matched with the camera of company B in terms of field of view, resolution, focal length and light reduction multiple. Then, it needs to consider whether the camera of company B can be used for the industrial computer of company C. Finally, it needs to consider whether the image offset detection can be realized on the industrial computer and whether the de-rotation algorithm of the horizontal solar telescope can be realized. There are many deficiencies in the specific implementation: first, the image data between the imaging camera and the image processing and error calculation computer needs to be transmitted through a long line. When passing through the complex telescope driving control system and the large driving motor nearby, the image is easily interfered by electromagnetic interference; second, the entire system is relatively dispersed in space and is tightly coupled with the telescope system, which is not conducive to system maintenance and application promotion; third, the hardware and driver program depend on external manufacturers. For example, if the camera or the driving software is updated or discontinued, the software of the guiding system needs to be redeveloped; fourth, the entire system is realized based on the network architecture of the industrial computer. The full-disk image sensing, image acquisition and error calculation are distributed in several systems and different spatial positions, which is not conducive to independent operation, modularization and miniaturization. SUMMARY

[0006] In view of this, in order to solve the problems of the current full-sky guiding technology, such as dispersion, system dispersion, large volume and large space span, deep coupling dependence with the original telescope system, low integration, difficult to transplant, promote application, operation and maintenance, and unable to use other space and satellite-borne solar telescopes, the application provides an embedded full-sky guiding device for a horizontal solar telescope, which integrates a full-sky imaging lens, an image sensor, a control circuit of the image sensor, image acquisition, image storage and processing, image despun and tracking error calculation into an electronic system, directly realizes tracking error calculation of the telescope to the sun, feeds back the tracking error signal to a pointing and tracking control system of the telescope through a communication interface, and realizes precise tracking of the horizontal solar telescope to the sun. The device directly calculates the tracking error of the horizontal solar telescope through a modular embedded electronic system, feeds back the tracking error to the pointing and tracking control system of the horizontal telescope, guides the tracking movement of the telescope, and improves the tracking precision of the horizontal solar telescope to the sun.

[0007] The technical scheme of the application is as follows:

[0008] The embedded full-sky guiding device for the horizontal solar telescope comprises a full-sky imaging optical system and an embedded full-sky guiding system.

[0009] The full-sky imaging optical system images the sun in a white light band, and is composed of a front neutral light reducer, a complex achromatic imaging lens and a filter.

[0010] The embedded full-sky guiding system is integrated on a circuit board and comprises six parts, namely a CMOS image sensor chip, an FPGA core processor chip, an image buffer chip, a power distribution and management system, a USB communication serial port and a GigE communication network port. The CMOS image sensor chip is located on the focal plane of the full-sky imaging optical system, performs photoelectric conversion, and converts the full-sky optical image into an electrical signal. The FPGA core processor chip and the CMOS image sensor chip adopt SPI serial communication to set control words and chip working parameters, and the image buffer chip is connected to the FPGA core processor chip through an IO port.

[0011] The optical axis of the embedded full-sky guiding device is parallel to the optical axis of the horizontal solar telescope and is installed in the lens barrel of the horizontal solar telescope.

[0012] As a further scheme of the present application, the front neutral light-reducing lens is used to reduce the energy of the sun, and the light-reducing multiple is 10,000 to 100,000 times.

[0013] As a further scheme of the present application, the front neutral light-reducing lens is a neutral light-reducing lens, and a Kodak ND82MM light-reducing lens is used.

[0014] As a further scheme of the present application, the complex apochromatic imaging lens uses an ED80 lens, the diameter is 8-10 cm, the focal length is 55-66 cm, and the field of view is ≥70′.

[0015] As a further scheme of the present application, the filter has a bandwidth of 10-100 nm, a center wavelength of 500 nm-600 nm, and a diameter of 2.5-5 cm.

[0016] As a further scheme of the present application, the CMOS image sensor chip uses a CMOS image sensor with a long light path, and the CMOS image sensor transmits data to the FPGA through 16 LVDS data pairs and 1 LVDS clock, the size of the CMOS image sensor chip is 2K×2K, the number of pixels is 2048×2048, the bit depth is 16 bit, the pixel size is 5.5 um or 6.5 um, the field of view is 70′, the focal length matched with the full-disk imaging optical system is 55 cm and 66 cm, the field of view of the guidance system is 70.3′×70.3′, and the pixel resolution is 2.06″.

[0017] As a further scheme of the present application, the FPGA core processor chip includes an image data acquisition module, a CMOS chip logic control module, a CMOS chip timing control module, an image processing and tracking error solving module, a memory logic and timing control module, and a communication logic control module.

[0018] The image data acquisition module realizes the hardware interface and image data transmission with the CMOS chip, transmits the 2K×2K data in the CMOS image chip to the FPGA chip, and divides the data into two paths, one of which is used for the image processing and tracking error solving module, and the other of which is transmitted to the image buffer chip.

[0019] The CMOS chip logic control module is used to realize the initialization, exposure, gain, and start-stop control of the CMOS chip.

[0020] The CMOS chip timing control module provides the control timing for the CMOS chip, and is used for data reading and transmission.

[0021] The image processing and tracking error solving module is used for image dark processing, image barycenter calculation, and spin elimination calculation, and finally obtains the offset of the full-disk image and performs tracking error feedback.

[0022] The memory logic and timing control module is used for realizing hardware connection, timing control and image transmission of the image buffer chip;

[0023] The communication logic control module is used for realizing hardware connection, protocol and data transmission of the FPGA and USB communication serial chip and GigE network interface chip.

[0024] As a further scheme of the present application, the image buffer chip adopts 4 pieces of DDR3 memory chips with a total capacity of 2GB, the power distribution and management system is a power supply system with input of DC 12V and output of 1.8V, 3.3V and 5.0V, the DC-DC power chip TLV62130RGTR of the power distribution and management system generates the power required by the FPGA chip, and the power chip TLV76701DRVR generates the power required by the CMOS chip; the USB communication serial port adopts the CYUSB3014-BZXC chip; and the GigE communication network interface adopts the KSZ9031RNXIC-TR chip.

[0025] As a further scheme of the present application, the altazimuth solar telescope comprises a telescope pointing and tracking control system, a main optical system and an altazimuth frame, an observation and data system and a focal plane scientific instrument system, the optical axis of the embedded full-sun guiding device is parallel to the optical axis of the altazimuth frame, the USB communication serial port is connected to the telescope pointing and tracking control system and is used for feeding back tracking errors, and the GigE communication network interface is connected to the observation and data system and is used for transmitting original images.

[0026] As a further scheme of the present application, the image processing and tracking error solving module executes the following algorithms:

[0027] (1) Binaryzation of the image:

[0028] ; wherein, is the image gray threshold, represents the gray value of a pixel point before binaryzation, represents the gray value of a pixel point after binaryzation, and is unified as 1;

[0029] (2) Calculation of the image gravity center:

[0030] , ; wherein, m and n represent m rows and n columns of the CMOS output image; , is the full-sun image gravity center;

[0031] (3) Image field rotation of full-disk in alt-azimuth solar telescope:

[0032] , ; wherein: image field rotation angle, altitude angle, geographic latitude, solar right ascension, solar hour angle;

[0033] (4) Coordinates of the center of gravity relative to the center of the field of view of the photoelectric guide system: , ;

[0034] Formula for rotation of plane coordinates of racemization: , , and is the formula for the center of gravity of the full-disk image, and the error change is obtained by subtracting the starting time; after multiple averaging, the average tracking error in a control period is obtained, which is converted into the azimuth tracking error and the altitude tracking error of the alt-azimuth telescope according to the pixel scale of the embedded full-disk guide device, and is fed back to the telescope pointing and tracking control system.

[0035] Compared with the prior art, the embedded full-disk guide device for an alt-azimuth solar telescope has the following beneficial effects:

[0036] Since the traditional full-disk guide technology has the problems of system dispersion, large volume, and deep coupling with the original telescope system, the present application integrates the full-disk imaging lens, image sensor, control circuit, image processing, and error calculation into a single embedded electronic system through high integration design, forms an independent device, can eliminate the maintenance difficulty problem caused by the dispersion of multiple modules, avoids deep coupling with the telescope system, and can realize plug and play through USB and Ethernet connection, has small volume and is suitable for space-limited scenes. The modular independent design of the present application decouples the device from the telescope main body, only needs to be installed in parallel with the optical axis and connected in communication, can be directly popularized to other alt-azimuth systems without the need for re-design, and supports ground-based, space-based, and satellite-borne solar telescopes.

[0037] The application also solves tracking errors through real-time closed-loop control, feeds back to a telescope pointing system, so that the precision reaches sub-arcsecond, meets the high-precision requirement of the altazimuth telescope, enhances the anti-interference ability, and significantly improves the tracking precision; through the FPGA core processor, image acquisition, despun, error solving and other tasks are executed in parallel, so that from image acquisition to error feedback, no manual intervention is needed, and the operation complexity is reduced; the optical axis alignment only needs two steps of coarse alignment and sunspot fine alignment, so that the deployment can be quickly completed, the debugging time is shortened, the FPGA concurrently processes communication, image processing and data transmission tasks, the image transmission and error solving are synchronously performed, the exposure time, gain and N value are set through the upper computer, different atmospheric conditions are adapted, and the core pain point problem of the altazimuth solar telescope guiding technology is solved.

[0038] These aspects or other aspects of the present application will be more apparent in the following description of the embodiments. It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present application. BRIEF DESCRIPTION OF DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the related art, the drawings needed to be used in the exemplary embodiments or the related art description will be briefly introduced below. The drawings are used to provide further understanding of the present application, and constitute a part of the specification. The drawings are used together with the embodiments of the present application to explain the present application, and do not constitute a limitation on the present application. In the drawings:

[0040] Fig. 1 A structure schematic diagram of an embedded full-solar-face guiding device for an altazimuth solar telescope according to an embodiment of the present application.

[0041] Fig. 2 An application schematic diagram of an embedded full-solar-face guiding device for an altazimuth solar telescope according to an embodiment of the present application on a two-meter altazimuth solar telescope (2MRST).

[0042] Fig. 3 A control flowchart of an experiment of an embedded full-solar-face guiding device for an altazimuth solar telescope according to an embodiment of the present application on a 2MRST.

[0043] Reference signs:

[0044] 10- full-disk imaging optical system, 101- front neutral density filter, 102- complex achromatic imaging mirror, 103- filter, 20- embedded full-disk guiding system, 201- CMOS image sensor chip, 202- FPGA core processor chip, 20201- image data acquisition module, 20202- CMOS chip logic control module, 20203- CMOS chip timing control module, 20204- image processing and tracking error solving module, 20205- memory logic and timing control module, 20206- communication logic control module, 203- image buffer chip, 204- power distribution and management system, 205- USB communication serial port, 206- GigE communication network port, 30- altazimuth solar telescope, 301- telescope pointing and tracking control system, 302- main optical system and altazimuth mount, 303- observation and data system, 304- focal plane scientific instrument system. DETAILED DESCRIPTION

[0045] The application will be further described below in conjunction with the drawings and specific embodiments. It should be noted that the following described embodiments or technical features can be combined in any manner to form new embodiments.

[0046] To make the objectives, technical solutions and advantages of the present application clearer, the embodiments of the present application will be further described in detail below with reference to the drawings and in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and should not be used to limit the present application.

[0047] It should be noted that all the expressions of "first" and "second" in the embodiments of the present application are used to distinguish two non-identical entities or non-identical parameters with the same name. It can be seen that "first" and "second" are only used for the convenience of description and should not be understood as a limitation of the embodiments of the present application. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, the process, method, system, product or device inherently includes other steps or units.

[0048] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0049] The flow chart shown in the drawing is only an example and does not necessarily include all the contents and operations / steps, nor does it have to be executed in the order described. For example, some operations / steps can be further divided, combined or partially merged, so the actual execution order can be changed according to the actual situation.

[0050] Some embodiments of the present application will be described in detail below with reference to the accompanying drawings. The following examples and features in the examples can be combined with each other without conflict.

[0051] Referring to Figs. 1 to 3 As shown, the embodiment of the present application provides an embedded full-disk guiding device for a horizontal solar telescope, which comprises a full-disk imaging optical system 10 and an embedded full-disk guiding system 20; the full-disk imaging optical system 10 images the sun in the white light band and is composed of a front neutral density filter 101, a complex achromatic imaging lens 102 and a filter 103; the front neutral density filter 101 is a neutral density filter, the complex achromatic imaging lens 102 is a lens imaging lens group for imaging the entire sun, and the filter 103 is a filter 103 installed in front of the focal plane for filtering to obtain a sunspot image. During the tracking process of the horizontal solar telescope, there will be an image field rotation, and when the telescope observes the edge of the solar disk, the full-disk image in the full-disk imaging optical system 10 rotates around the optical axis (i.e. the center of the field of view). In order to ensure that the sun image does not rotate out of the full-disk guiding system during the tracking process, the field of view must be able to accommodate four full-disk images. The apparent diameter of the sun is about 32', which requires that the field of view of the full-disk guiding system must be greater than 64', plus a certain amount of redundancy, the field of view of the full-disk imaging optical system 10 is designed to be 70'. The embedded full-disk guiding system 20 is integrated on a circuit board and consists of six parts, namely a CMOS image sensor chip 201, an FPGA core processor chip 202, an image buffer chip 203, a power distribution and management system 204, a USB communication serial port 205 and a GigE communication network port 206. The CMOS image sensor chip 201 is located at the focal plane of the full-disk imaging optical system 10 and performs photoelectric conversion to convert the full-disk optical image into an electrical signal; the FPGA core processor chip 202 and the CMOS image sensor chip 201 use SPI serial communication to set the control word and chip working parameters, and the image buffer chip 203 is connected to the FPGA core processor chip 202 through the IO port; the optical axis of the embedded full-disk guiding device is parallel to the optical axis of the horizontal solar telescope 30 and is installed in the lens barrel of the horizontal solar telescope 30.

[0052] The embedded full-solar guiding device for the horizontal solar telescope integrates a full-solar imaging lens, an image sensor, a control circuit of the image sensor, image acquisition, image storage and processing, image despun and tracking error calculation into an electronic system, and directly realizes tracking error calculation of the telescope on the sun. The device can feed back the tracking error signal to the pointing and tracking control system of the telescope through the communication interface, and realize precise tracking of the horizontal solar telescope on the sun. The electronic system is a small circuit board in hardware, and the whole system is designed as an embedded system with FPGA as the core. The device is characterized by miniaturization, modularization, light weight and intelligence, and the system software and hardware are highly integrated, complete in function, and independent of the application object, and is connected only through the necessary communication line. It is a complete and independent device. The device of the application needs to be installed on the lens barrel of the optical system of the telescope, and the optical axis of the system needs to be kept parallel to the optical axis of the optical system of the telescope. The error signal of the device is fed back to the pointing and tracking control system of the telescope through the USB serial port, the pointing and tracking control system of the telescope sends start-stop commands, the attitude information of the telescope and the motion information of the sun to the device, and the attitude information and the motion information of the sun are used to calculate the rotation change amount of the barycenter of the full-solar sun around the optical axis. The original image information of the device is returned to the observation and data system of the telescope through Ethernet, and the full-solar image information is provided for the observer.

[0053] In the embodiment, the front neutral density filter 101 is used to reduce the energy of the sun, and the light reduction multiple is 10,000 to 100,000. The front neutral density filter 101 is a neutral density filter, and a Kodak ND82MM light reduction filter is used. The apochromatic imaging lens 102 uses an ED80 lens, the diameter is 8-10 cm, the focal length is 55-66 cm, and the field of view is greater than or equal to 70'. The bandwidth of the filter 103 is 10-100 nm, the center wavelength is 500 nm-600 nm, the diameter is 2.5-5 cm.

[0054] For example, the full-solar imaging optical system 10 is composed of the front neutral density filter 101, the apochromatic imaging lens 102 and the filter 103. The apochromatic imaging lens 102 can be machined by itself or corresponding devices on the market. In the embodiment of the application, an ED80 lens with a diameter of 8 cm and a focal length of 65 cm is used on the market, and then the device is modified according to the application. The front neutral density filter 101 is installed at the front end, and the front neutral density filter 101 is a Kodak ND82MM light reduction filter. The filter 103 at the rear end is a filter with a diameter of 2.5 cm, a wavelength of 500 nm to 600 nm and M2.5.

[0055] In this embodiment, the CMOS image sensor chip 201 uses a long optical CMOS image sensor, and the CMOS image sensor transmits data to the FPGA through 16 LVDS data pairs and 1 LVDS clock. The size of the CMOS image sensor chip 201 is 2Kx2K, the number of pixels is 2048x2048, the bit depth is 16bit, the pixel size is 5.5um or 6.5um, the field of view is 70', the focal length of the full-disk imaging optical system 10 matched therewith is 55cm and 66cm, the field of view of the guiding system is 70.3'x70.3', and the pixel resolution is 2.06".

[0056] The embedded full-disk guiding system 20 is exemplarily a highly integrated circuit board as an electronic system. The embedded full-disk guiding system 20 is composed of six parts, i.e., the CMOS image sensor chip 201, the FPGA core processor chip 202, the image buffer chip 203, the power distribution and management system 204, the USB communication serial port 205, and the GigE communication network port 206. The CMOS image sensor chip 201 is located at the focal plane of the full-disk imaging optical system 10, and performs photoelectric conversion to convert the full-disk optical image into an electrical signal. The CMOS image sensor chip 201 uses a CMOS image sensor of long optical, model GSENSE2020BSI, size 2Kx2K, bit depth 16bit, pixel size 6.5um, and can realize a field of view of 70.3'x70.3' of the guiding system and a pixel resolution of 2.06" in cooperation with the full-disk imaging optical system 10. The FPGA core processor chip 202 uses a Kintex-7 chip of XILINX. The FPGA core processor chip 202 and the CMOS image sensor chip 201 adopt SPI serial communication to set control words and chip working parameters, and the CMOS image sensor transmits data to the FPGA through 16 LVDS data pairs and 1 LVDS clock. The image buffer chip 203 uses four DDR3 memory chips with a total capacity of 2GB, which are connected to the FPGA through IO ports. The power distribution and management system 204 is a power supply system with an input of DC 12 volts and outputs of 1.8 volts, 3.3 volts and 5.0 volts, etc. A DC-DC power chip TLV62130RGTR generates the power required by the FPGA chip, and a power chip TLV76701DRVR generates the power required by the CMOS chip. The USB communication serial port 205 uses a CYUSB3014-BZXC chip. The GigE communication network port 206 uses a KSZ9031RNXIC-TR chip.

[0057] In the embodiment, the FPGA core processor chip 202 comprises an image data acquisition module 20201, a CMOS chip logic control module 20202, a CMOS chip timing control module 20203, an image processing and tracking error solving module 20204, a memory logic and timing control module 20205, and a communication logic control module 20206; wherein:

[0058] The image data acquisition module 20201 realizes hardware interface and image data transmission with the CMOS chip, transmits 2Kx2K data in the CMOS image chip to the FPGA chip, and divides the data into two paths, one of which is supplied to the image processing and tracking error solving module 20204, and the other of which is transmitted to the image buffer chip 203; the CMOS chip logic control module 20202 is used to realize the initialization, exposure, gain, and start-stop control of the CMOS chip; the CMOS chip timing control module 20203 provides control timing for the CMOS chip, which is used for data readout and transmission; the image processing and tracking error solving module 20204 is used for image flat dark processing, image barycenter calculation, and spin elimination calculation, and finally obtains the offset of the full-disk image and performs tracking error feedback; the memory logic and timing control module 20205 is used to realize hardware connection, timing control, and image transmission with the image buffer chip 203; and the communication logic control module 20206 is used to realize hardware connection, protocol, and data transmission of the FPGA with the USB communication serial port 205 chip and the GigE network port chip.

[0059] In the embodiment, the image buffer chip 203 adopts four pieces of DDR3 memory chips, with a total capacity of 2GB; the power distribution and management system 204 is a power supply system with input DC 12V and output 1.8V, 3.3V, and 5.0V; the DC-DC power chip TLV62130RGTR of the power distribution and management system 204 generates the power required by the FPGA chip, and the power chip TLV76701DRVR generates the power required by the CMOS chip; the USB communication serial port 205 adopts the CYUSB3014-BZXC chip; and the GigE communication network port 206 adopts the KSZ9031RNXIC-TR chip.

[0060] In the embodiment, the equatorial solar telescope 30 comprises a telescope pointing and tracking control system 301, a main optical system and equatorial rack 302, an observation and data system 303, and a focal plane scientific instrument system 304; the optical axis of the embedded full-disk guiding device is parallel to the optical axis of the main optical system and equatorial rack 302; the USB communication serial port 205 is connected to the telescope pointing and tracking control system 301 and is used for feedback of tracking error; and the GigE communication network port 206 is connected to the observation and data system 303 and is used for transmission of original images.

[0061] The application is used for the embedded full-solar surface guiding device of the horizontal type solar telescope. In the tracking process, due to the existence of the telescope manufacturing and installation errors and other factors, the image in the field of view will change slowly, which is called tracking error. The pointing position of the telescope gradually deviates from the observation target with the lapse of time, which will eventually lead to the telescope not working normally. At this time, if the application device is used, the offset of the full-solar surface image is continuously obtained, the tracking error is calculated, and the pointing position of the telescope is continuously corrected, so that the observation target remains in the field of view and the closed-loop control is realized, which can greatly improve the tracking accuracy of the solar telescope. The application device needs to be installed on the lens barrel of the large horizontal type solar telescope to be applied before work, and the optical axes of the two are parallel. Next, the application device starts to work.

[0062] The application firstly images the sun through the full-disk imaging optical system 10, and then controls the image sensor, collects the image, stores the image and calculates the tracking error in the embedded full-disk guiding system 20. After the embedded full-disk guiding system 20 is powered on, the main steps are image collection, image processing and error calculation, and image storage and transmission. In the first step, the FPGA first initializes each module, and each module runs in parallel in the FPGA. After initializing each module, the FPGA receives the instructions of the host computer and parses the instructions, and then schedules the corresponding modules to complete the corresponding tasks. After receiving the start image collection, camera exposure time, gain and other parameter settings, the FPGA starts the CMOS chip logic control module 20202 to write the corresponding control word and parameters to the CMOS image sensor chip 201, and then the FPGA starts the CMOS chip timing control module 20203 to start the exposure and readout of the CMOS image sensor. In the second step, after the FPGA receives the image, it is placed in the cache, and the current frame of image is processed, the order is to judge the effectiveness of the image, to process the flat dark field of the image, to binarize the image to reduce the sensitivity of the barycenter to sunspots, to calculate the barycenter of the image, to calculate the rotation amount of the barycenter to the optical axis point and to deduct it, to calculate the offset of the image relative to the starting time of the closed-loop control. The second frame of image is read, and the above process is continued to obtain the offset of the second frame of image, and the third frame, the fourth frame, and so on, until the offset calculation of the Nth frame of image is completed, and finally the average offset of N frames of image is calculated, which is expressed by two components X and Y in the CMOS image plane coordinate system, and is converted into tracking error according to the pixel scale. N frames of images are used to detect tracking error in order to eliminate the influence of random atmospheric turbulence. The value of N can be set by the host computer, and is usually between 20 and 100. One frame of image is collected and processed in 0.1 seconds, and the working period of the device of the application is between 2 seconds and 10 seconds. In the third step, the FPGA starts the communication logic control module 20206, feeds back the tracking error to the telescope pointing and tracking control system 301 through the USB communication serial port 205, and transmits the original image to the observation and data system 303 through the GigE communication network port 206. The image transmission can be parallel to the image processing and tracking error calculation module 20204, that is, parallel to the second step in the process.

[0063] The application solves the problem of real-time detection of tracking error of high-precision tracking of the sun in the horizontal type solar telescope, and highly integrates, miniaturizes and individualizes the system to become an embedded full-sun guiding system, which is convenient for popularization and application. After adopting the device, when developing a large horizontal type solar telescope in the future, the device can be directly used as an independent system without the need to design and develop such a system again. The device can be used for real measurement experiment on a two-meter horizontal type solar telescope, and can directly provide tracking error feedback signal for the telescope. Limited by the progress of the observation and data system and the terminal scientific instrument system engineering in the two-meter horizontal type solar telescope, simulation data is used for part of the system during testing.

[0064] After the device is installed on the two-meter horizontal type solar telescope 30, the specific working process is as follows:

[0065] The first step is installation and optical axis alignment. The device is installed on the lens barrel of the large horizontal type solar telescope 30, and then the optical axis of the device is roughly adjusted to be substantially parallel to the optical axis of the telescope. This step is rough alignment of the optical axis, and the next step is fine alignment of the optical axis. The telescope is pointed to a certain active area of the sun, and the target is a small sunspot. The sunspot is adjusted to the center of the field of view of the telescope, and then the image of the device is obtained through the observation system. The device is continuously adjusted so that the small sunspot is also in the center of the field of view of the guiding system, which is fine alignment of the optical axis. The second step is to power the device and start the guiding device. The guiding device is started through the telescope pointing and tracking control system 301, and the device provides the sun observation target and the attitude information of the telescope. The device starts the working processes of image acquisition, image processing, image despun, error calculation and image and signal transmission. The working process diagram is shown in Fig. 3 The FPGA is a multi-task concurrent processing system, Fig. 3 three main tasks are given, one communication task, one image processing and error calculation task, and one image transmission task. The specific process and logical relationship are given in Fig. 3 The image processing and error calculation task in Fig. 3 is for full-sun image and despun of the horizontal type telescope. In this embodiment, the image processing and tracking error calculation module 20204 performs the following algorithm:

[0066] (1) Binaryzation of the image:

[0067] ; wherein, is the image gray threshold value, represents the gray value of the pixel point before binaryzation, represents the pixel point The gray value after binarization is unified as 1; in the embodiment, the binarization is to solve the image center calculation error caused by the sunspot and other active areas.

[0068] (2) Image center calculation:

[0069] , ; wherein m and n represent m rows and n columns of the CMOS output image; , is the image center of the full-disk image;

[0070] (3) Image field rotation of the full-disk in the alt-azimuth solar telescope 30:

[0071] , ; wherein: image field rotation angle, is the altitude angle, is the geographic latitude, is the solar right ascension, is the solar hour angle;

[0072] (4) Center coordinate of the image center relative to the field center of the photoelectric guide system: , ;

[0073] The plane coordinate rotation formula of the racemization:

[0074] , , and is the image center formula of the full-disk image, and the error change amount is obtained by subtracting the starting time; the average tracking error in a control period is obtained through multiple averaging, the azimuth tracking error and the altitude tracking error of the alt-azimuth telescope are converted according to the pixel scale of the embedded full-disk guide device, and the converted azimuth tracking error and the altitude tracking error are fed back to the telescope pointing and tracking control system 301.

[0075] Since the traditional full-disk guide technology has the problems of system dispersion, large volume, and deep coupling with the original system of the telescope, the full-disk imaging lens, the image sensor, the control circuit, the image processing and error solving are integrated in a single embedded electronic system through high integration design, forming an independent device, which can eliminate the maintenance difficulty problem caused by the dispersion of multiple modules, avoid deep coupling with the telescope system, and realize plug and play through USB and Ethernet connection, has small volume and is suitable for space limited scenes. The modular independent design of the application decouples the device from the telescope main body, only needs optical axis parallel installation and communication connection, and is directly popularized to other alt-azimuth systems without the need for re-design, supports ground-based, space and satellite-borne solar telescopes.

[0076] The application also solves tracking errors through real-time closed-loop control, feeds back to a telescope pointing system, so that the precision reaches sub-arcsecond, meets the high-precision requirement of the altazimuth telescope, enhances the anti-interference ability, and significantly improves the tracking precision; through the FPGA core processor, image acquisition, despun, error solving and other tasks are executed in parallel, so that from image acquisition to error feedback, no manual intervention is needed, and the operation complexity is reduced; the optical axis alignment only needs two steps of coarse alignment and sunspot fine alignment, so that the deployment can be quickly completed, the debugging time is shortened, the FPGA concurrently processes communication, image processing and data transmission tasks, the image transmission and error solving are synchronously performed, the exposure time, gain and N value are set through the upper computer, different atmospheric conditions are adapted, and the core pain point problem of the 30 guide technology of the altazimuth solar telescope is solved.

[0077] The above is the exemplary embodiment disclosed by the application, but it should be noted that various changes and modifications can be made without departing from the scope of the embodiment disclosed by the application defined by the claims. The functions, steps and / or acts of the method claims described herein need not be performed in any particular order. Furthermore, although the elements of the embodiment disclosed by the application can be described or claimed in individual form, unless explicitly restricted, they can also be implemented in multiple forms.

[0078] It should be understood that, as used herein, the singular forms "a", "an" and "the" are intended to include plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising", when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0079] Those skilled in the art should understand that the above discussion of any embodiment is only exemplary, and is not intended to limit the scope of the embodiment disclosed by the application (including claims) to these examples; under the idea of the embodiment of the application, the technical features in the above embodiment or different embodiments can also be combined, and there are many other changes of different aspects of the above embodiment of the application, which are not provided in detail for the sake of brevity. Therefore, any omissions, modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the embodiment of the application shall be included in the protection scope of the embodiment of the application.

Claims

1. An embedded full-solar tracking device for a horizon-type solar telescope, characterized in that, It comprises a full-disk imaging optical system (10) and an embedded full-disk guiding system (20). The full-disk imaging optical system (10) images the sun in the white light band and is composed of a front neutral density filter (101), a complex achromatic imaging lens (102) and a filter (103); the front neutral density filter (101) is a neutral density filter, the complex achromatic imaging lens (102) is a lens imaging lens group for imaging the whole sun, and the filter (103) is a filter (103) installed in front of the focal plane for filtering to obtain a sunspot image. The embedded full-disk guiding system (20) is integrated on a circuit board and consists of six parts, namely a CMOS image sensor chip (201), a FPGA core processor chip (202), an image buffer chip (203), a power distribution and management system (204), a USB communication serial port (205) and a GigE communication network port (206); the CMOS image sensor chip (201) is located on the focal plane of the full-disk imaging optical system (10) and converts the full-disk optical image into an electrical signal through photoelectric conversion. SPI serial communication is used between the FPGA core processor chip (202) and the CMOS image sensor chip (201) to set the control word and chip working parameters, and the image buffer chip (203) is connected to the FPGA core processor chip (202) through an IO port. The optical axis of the embedded full-disk guiding device is parallel to the optical axis of the equatorial solar telescope (30) and is installed in the lens barrel of the equatorial solar telescope (30).

2. The embedded full-hemispheric guiding device for altazimuth solar telescopes according to claim 1, characterized in that, The front neutral density filter (101) is used to reduce the energy of the sun, and the light reduction multiple is 10,000 to 100,000 times.

3. The embedded full-hemispheric guiding device for altazimuth solar telescopes according to claim 2, characterized in that, The front neutral density filter (101) is a neutral density filter, which uses a Kodak ND82MM light reduction lens.

4. The embedded full-hemispheric guiding device for altazimuth solar telescopes according to claim 3, characterized in that, The complex achromatic imaging lens (102) uses an ED80 lens with a diameter of 8-10 cm, a focal length of 55-66 cm and a field of view of ≥70′.

5. The embedded full-hemispheric guiding device for alt-azimuth solar telescopes according to claim 4, characterized in that, The bandwidth of the filter (103) is 10-100 nm, the center wavelength is 500-600 nm, and the diameter is 2.5-5 cm.

6. The sun-tracking device for a altazimuth solar telescope according to claim 1, wherein The CMOS image sensor chip (201) uses a CMOS image sensor of Changguanchen, which transmits data to the FPGA through 16-way LVDS data and 1-way LVDS clock; the size of the CMOS image sensor chip (201) is 2K×2K, the number of pixels is 2048×2048, the bit depth is 16bit, the pixel size is 5.5um or 6.5um, the field of view is 70′, the focal length matched with the full-disk imaging optical system (10) is 55cm and 66cm, the field of view of the guiding system is 70.3′×70.3′, and the pixel resolution is 2.06″.

7. The embedded full-hemispheric guiding device for alt-azimuth solar telescopes according to claim 6, characterized in that, The FPGA core processor chip (202) comprises an image data acquisition module (20201), a CMOS chip logic control module (20202), a CMOS chip timing control module (20203), an image processing and tracking error solving module (20204), a memory logic and timing control module (20205) and a communication logic control module (20206); The image data acquisition module (20201) realizes hardware interface and image data transmission with the CMOS chip, transmits 2K*2K data in the CMOS image chip to the FPGA chip, and divides the data into two paths, one of which is used for the image processing and tracking error solving module (20204), and the other of which is transmitted to the image buffer chip (203); The CMOS chip logic control module (20202) is used for realizing initialization, exposure, gain and start-stop control of the CMOS chip; The CMOS chip timing control module (20203) provides control timing for the CMOS chip, which is used for data reading and transmission; The image processing and tracking error solving module (20204) is used for image dark processing, image center of gravity calculation, spin elimination calculation, and finally obtains the offset of the full-disk image and performs tracking error feedback; The memory logic and timing control module (20205) is used for realizing hardware connection, timing control and image transmission with the image buffer chip (203); The communication logic control module (20206) is used for realizing hardware connection, protocol and data transmission of the FPGA and the USB communication serial port (205) chip and the GigE network port chip.

8. The embedded full-hemispheric guiding device for alt-azimuth solar telescope according to claim 7, characterized in that, The image buffer chip (203) adopts four DDR3 memory chips with a total capacity of 2GB, the power distribution and management system (204) is a power supply system with input DC 12V and output 1.8V, 3.3V and 5.0V, the DC-DC power chip TLV62130RGTR of the power distribution and management system (204) generates the power required by the FPGA chip, and the power chip TLV76701DRVR generates the power required by the CMOS chip; the USB communication serial port (205) adopts a CYUSB3014-BZXC chip; the GigE communication network port (206) adopts a KSZ9031RNXIC-TR chip.

9. The embedded full-hemispheric guiding device for alt-azimuth solar telescopes according to claim 8, characterized in that, The horizontal solar telescope (30) comprises a telescope pointing tracking control system (301), a main optical system and a horizontal frame (302), an observation and data system (303) and a focal plane scientific instrument system (304), the optical axis of the embedded full-disk guiding device is parallel to the optical axis of the main optical system and the horizontal frame (302), the USB communication serial port (205) is connected to the telescope pointing tracking control system (301) and is used for feeding back tracking error, and the GigE communication network port (206) is connected to the observation and data system (303) and is used for transmitting original images.

10. The sun-tracking device for alt-azimuth solar telescopes according to claim 8, characterized in that, The image processing and tracking error solving module (20204) executes the following algorithms: 1) Binary processing of the image: ; wherein, is the image gray threshold, represents the gray value of the pixel point before binarization, represents the gray value of the pixel point after binarization, which is uniformly 1; 2) Calculation of the image barycenter: , ; wherein m and n represent m rows and n columns of the CMOS output image; , is the center of the full-disk image; 3) Rotation of the image field of the full sun in the altazimuth solar telescope (30): , ; where: image field rotation angle, is the altitude angle, geographic latitude, is the solar right ascension, is the solar hour angle; 4) Coordinates of the barycenter relative to the field center of the photoconductive line system: , , the plane coordinate rotation formula of racemic: , , and is the formula of the center of gravity of the full-disk image, and the error change is obtained by subtracting the starting time, and the average tracking error in a control period is obtained by averaging several times. According to the pixel scale of the embedded full-disk guide device, the azimuth tracking error and the altitude tracking error of the equatorial telescope are converted, and feedback is given to the telescope pointing and tracking control system (301).

Images