CN104048620B - A kind of Radio Telescope Antenna face shape absolute calibration apparatus and method - Google Patents

Abstract

The invention relates to a radio telescope antenna surface shape absolute calibration device and method. A radio telescope antenna surface shape absolute calibration device is composed of a PSD position sensor array, a support shaft, a ring laser and a control circuit. The PSD position sensor array is composed of several coaxial PSD position sensor rings, and each PSD position sensor ring is composed of several It is composed of a PSD position sensor unit with multiple points on the central axis as the center of the circle, and the photosensitive surface is facing and parallel to the central axis; the supporting shaft is set on the central axis, and the supporting shaft is equipped with a ring laser, and the emitting surface of the ring laser is perpendicular to the center axis. The device of the invention has the advantages of simple structure, low cost and easy manufacture and assembly. The method of the invention is convenient for upgrading the active reflection surface of the radio telescope, ensures the performance of the radio telescope in real time, and has simple implementation process.

Description

A radio telescope antenna surface absolute calibration device and method

technical field

The invention relates to a radio telescope antenna surface absolute calibration device and method based on a ring laser and a PSD array, which is very suitable for the absolute stitching calibration detection and correction of the radio panel of the radio telescope.

Background technique

A radio telescope usually has a large aperture, and its antenna (main panel) is usually spliced by a large number of small panels. For example, a 65-meter-caliber radio telescope antenna is composed of thousands of one-meter panels. During the formal operation, under the influence of external loads such as gravity and wind, it is necessary to ensure that the overall surface shape of the paraboloid is within the allowable range. In addition to considering the support shape-keeping design of the antenna back frame, mass panel splicing detection is also a key part of the design and operation of radio telescopes, especially the absolute calibration detection method of the core surface shape, which realizes the theory required by the entire main reflector The designed surface shape, not just the maintenance measurement of the relative change of the surface shape of the main reflector at a certain time.

Radio telescopes are increasingly required to develop from passive control based on mathematical models to dynamic real-time surface adjustment, which requires a real-time detection technology that can evaluate the real-time surface shape at any zenith distance. The panel inspection of radio telescopes is one of the key technologies for real-time radio telescope panel splicing. However, due to the different wavelength bands of radio telescopes and optical infrared telescopes, the surface shape accuracy requirements of the primary mirror (antenna) are also very different. According to the diffraction conditions, the surface shape accuracy is required to be 20 to 1 wavelength, and the shortest wavelength in the submillimeter band is about 0.2 mm. The common phase requirement for panel splicing is the root mean square value of 20 to 1 wavelength, that is, the surface shape accuracy is 10 microns. . This is hundreds of times more relaxed than the optical infrared band (such as the surface accuracy requirement of 27.5 nanometers for the visible light wavelength of 550 nanometers). Usually radio telescopes use the above method during installation and commissioning, and adjust and calibrate the panel at the middle zenith distance/elevation angle, so that the accuracy of the panel can reach one-twentieth of a wavelength. In official use, real-time measurement of the panel accuracy is no longer required. and adjustments, but are only guaranteed by the telescope's support design.

Common radio telescope panel detection and adjustment methods mainly include optical methods, radio holography methods, and laser measurement methods. Among them, methods such as theodolite, laser tracker, laser total station, laser rangefinder, etc., all have the ability to detect and adjust the panel when the telescope is fixed in a certain posture (such as the panel facing the sky or vertically facing the horizontal). , so that the panel reaches the design tolerance index, it is mainly used for the detection and calibration of the overall panel shape after the panel is installed and before it is put into use. Using geostationary satellites, astronomical or artificial radio sources to measure the wavefront of the entire antenna, you only need to use the receiver of the telescope itself (the best frequency is close to the upper limit of the antenna frequency), the hardware equipment requirements are simple, but it is not real-time, and can only be used in a few It takes a long time to match at a height angle; while the accuracy of other photographic methods can only reach about 0.1 mm, the imaging detection method in the visible light band is due to the large scale of the antenna panel in the radio band, relatively low precision and field seeing problems. Also not applicable here;

Chinese patent ZL200910212710.X "Radio telescope co-phase detection method based on four-point support of quadrilateral sub-panel", the target is placed on the sub-panel of at least one entire row and one entire column in the center of the antenna, and the laser receiving device is scanned by high-precision rotation tracking Or track and scan the laser emitting and receiving device, at least scan the target on the sub-panel of a whole row and a whole column in the center of the antenna, and record the position of the laser emitting device aligned with different targets through a high-precision encoder, and through alignment with the laser reflection device The angle data is obtained by measuring the image spot position information of the spliced target surface that is translated and rotated together, and the position deviation of all panels, the surface shape accuracy of the entire spliced antenna, and the support point displacement required to correct the surface shape accuracy are directly derived. That is, the correction amount of the actuator. This method requires high-precision rotation tracking scanning. It is difficult to achieve high repeat tracking and pointing accuracy. There are too many positions in each scan, and the design of splicing target surfaces is also difficult. Installation, alignment adjustment and implementation are very complicated and difficult; In addition, the bigger problem is that it is easily affected by the ambient background light and cannot achieve the calibration measurement of the absolute surface shape of the main reflective surface. It can only measure relative changes, which are used for real-time relative maintenance of the surface shape after the absolute calibration of the main reflective surface. Measurement.

The common disadvantage of the above radio telescope reflective surface detection methods is that it is only suitable for the detection and review of reflective surfaces at a single or certain height positions, and it is impossible to detect in real time during the working process of the radio telescope and ensure that it is installed and adjusted on the calibrated surface. shape accuracy, the workload of batch real-time detection is particularly heavy.

Contents of the invention

In order to overcome the disadvantages of low precision, poor anti-interference ability, or high cost, not real-time and heavy, and easily affected by ambient background light in the prior art methods for detecting and adjusting the reflecting surface of the above-mentioned antenna, the present invention aims at the main antenna of the radio telescope through a simple Easy process design, real-time splicing absolute calibration detection and adjustment of its batch panels at a relatively low cost, the invention provides a radio telescope antenna surface absolute calibration device based on ring lasers and PSD arrays and based on the device calibration method.

The technical solution for completing an inventive object of the present invention is: a radio telescope antenna surface shape absolute calibration device, which is made up of a PSD position sensor array, a support shaft, a ring laser and a control circuit, and the PSD position sensor array is composed of several coaxial Composed of PSD position sensor circles, each PSD position sensor circle is composed of a number of PSD position sensor units centered on multiple position points on the central axis, the photosensitive surface is facing and parallel to the central axis; the support shaft is located at the center On the axis, the support shaft is provided with the ring laser, and the emission direction of the ring laser is perpendicular to the central axis; the control circuit is used to control the PSD position sensor unit and the ring laser to collect and process the signals.

In the above technical solution, the PSD position sensor in the PSD position sensor array is installed on each panel of the main reflection surface of the radio telescope, the ring laser slides along the linear guide rail, and emits laser light to the PSD position sensor unit, and through the PSD position sensor, each The height error of the panels where different PSD position sensors are located on the circle; by obtaining the position of the PSD position sensor on each PSD position sensor circle, plus the absolute accurate position of the ring laser, the panel splicing error of the entire antenna can be obtained.

As a further improvement of the present invention, more than one ring laser is provided on the central axis, and the number and position of the ring laser correspond to the circle of the PSD position sensor.

As a further improvement of the present invention, the support shaft is a linear guide rail, the PSD position sensor is slidably connected to the linear guide rail, and the PSD position sensor is connected to a driving device.

As a further improvement of the present invention, a positioning mechanism for setting the position of the ring laser is provided on the linear guide rail.

A radio telescope antenna surface absolute calibration method, the steps are as follows:

1) Install a PSD position sensor unit on the monitoring position on each panel of the main reflective surface. The photosensitive surface of the PSD position sensor is parallel to the central axis of the main reflective surface to form several PSD position sensor circles. The detection zero position of each PSD position sensor Consistent calibration in the laboratory before installation;

2) Install a ring laser on the central axis of the antenna parallel to the axis. The emission direction of the ring laser is perpendicular to the central axis. The laser forms a light circle on the same height circle panel, and the light circle is of the same height along the central axis of the antenna, and is imaged on the corresponding PSD position sensor circle;

3) Control the ring laser and the PSD position sensor to emit and collect signals at the same time;

4) According to the different positions of the ring laser along the direction of the central axis, the pre-calibrated position error is calculated, and the imaging position of each ring laser in the direction perpendicular to the central axis based on the calibration is obtained through calculation of the theoretical surface shape of the antenna;

5) Collect the position of each PSD position sensor in each circle, and obtain the height error of the panel at the position of each PSD position sensor in each circle;

6) Compare the position of the PSD position sensor on all circles with the absolute accurate position of each corresponding ring laser to obtain the panel splicing error of the entire antenna.

As a further improvement of the present invention, the optimization scheme of the present invention has:

In the step 2), several ring lasers are provided on the central axis of the antenna, and one ring laser corresponds to one PSD position sensor ring ring laser.

In the step 2), a ring laser is provided on the central axis of the antenna, and the ring laser can move up and down along the central axis to be precisely aligned with each PSD position sensor circle turn by turn.

The working principle of the present invention is:

The main reflector antenna of a radio telescope is spliced by a large number of panels. At the same time, the panel itself, like the support truss of the main reflector, is subjected to gravity deformation, thermal deformation, processing inspection and installation adjustment during the observation operation of the radio telescope pointing and tracking. The impact of errors may not only be the main reflector technology that tightly includes spliced panels, but also the combined main reflector technology that combines both spliced panels and panel deformation. This is the most difficult technological frontier and bottleneck in the main reflector technology.

The conventional theodolite can only measure the height of the target on each panel point by point at different heights along the central axis when the telescope stops observing and is placed facing the sky, and adjust the position one by one, so that the accuracy of the spliced main reflector surface is within a certain accuracy. within range. At each key position of the main reflector, parallel to the axis of the main reflector, install a highly consistent PSD that has been calibrated at the zero-crossing point in the laboratory in advance, through the control logic of simultaneous emission and acquisition of the ring laser and PSD , to eliminate the influence of background light, the ring laser is imaged on the PSD, and the PSD can obtain the linear position measurement accuracy of the ring laser image on the order of microns, which is fully capable of the diffraction limit for submillimeter waves, millimeter waves and even longer wave bands The high precision of the following shape measurement (one-fortieth wavelength), in the direction parallel to the central axis, by using the ring laser, can realize the simultaneous aiming of all PSDs on a circle and the position measurement of the laser image at one time. The precise movement of the ring laser in the direction parallel to the central axis, or the installation and fixing of multiple ring lasers, respectively pointing to the PSD target of each circle, wherein the mobile positioning of a single ring laser or the distance between multiple ring lasers can be Calculated by the theoretical surface shape formula of the antenna, the ring laser also carries out distributed pre-error calibration on different circumferential radius distances inside and outside the laboratory, so as to realize the height error measurement of each circle of panels and the height difference measurement of all panels on the main reflective surface , and compared with the theoretical design, processing and detection surface shape of the main reflecting surface, it lays a technical foundation for realizing the surface shape evaluation of the main reflecting surface, and even the subsequent active correction of the active reflecting surface.

The advantages of the present invention are:

The present invention provides a design of a radio telescope antenna surface absolute calibration method based on a ring laser and a PSD array, which is very suitable for all real-time detection of splicing calibration and splicing maintenance of the main reflector of a radio telescope, and overcomes the current antenna reflective surface detection and The existing technology of the adjustment method has the disadvantages of low precision, poor anti-interference ability, or high cost, not real-time and heavy, and easily affected by ambient background light, which eliminates the heavy installation and adjustment of the laser scanning method, and is extremely convenient for assembly and debugging. For the main reflector antenna of the radio telescope, the absolute calibration and absolute maintenance detection of the main reflector of the radio telescope are realized through a simple geometric principle and a simple process method. The device of the invention has the advantages of simple structure, low cost and easy manufacture and assembly. The method of the invention is convenient for upgrading the active reflection surface of the radio telescope, ensures the performance of the radio telescope in real time, has simple implementation process and reduces labor intensity.

Description of drawings

Fig. 1 is the structural representation of the radio telescope antenna profile absolute calibration device of embodiment 1 of the present invention;

Fig. 2 is a schematic structural diagram of an absolute calibration device for radio telescope antenna surface shape in Example 2 of the present invention.

detailed description

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be described in further detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

Example 1

As shown in Figure 1, a radio telescope antenna surface absolute calibration device is composed of a PSD position sensor array 20, a linear guide rail 3, a ring laser 4 and a control circuit (not shown in the figure), and the PSD position sensor array 20 consists of several The coaxial PSD position sensor ring 21 is composed of the linear guide rail 3 located at the central axis 6 of the main reflection surface, and each PSD position sensor ring 21 is composed of several PSD position sensors with the linear guide rail 3 as the center and the photosensitive surface parallel to the central axis 6 Composed of unit 211; linear guide rail 3 is provided with ring laser 4, and the emission direction of ring laser 4 is perpendicular to central axis 6; the control circuit is used to control PSD position sensor 211 and ring laser 4 to collect and process signals.

On the main reflective surface 1 formed by a large number of panel splicing, place PSD position sensor unit 21 on the contour circles along the direction of the central axis on the position to be measured. PSD position sensor unit 21 includes PSD position sensor, its The support mechanism and packaging have highly consistent structural dimensions and installation and positioning interfaces, and the zero-crossing point is uniformly calibrated in the laboratory, and on the linear guide rail 3 parallel to the central axis of the main reflection surface, a linear-driven circular motion is installed. Laser 4, through the surface shape formula of the main reflection surface 1, the height position of the PSD position ring and the moving position of the ring laser on the linear guide rail can be calculated, and multiple positioning mechanisms are set on the position, so that the position along the central axis Above, by moving the ring laser 4, accurate positioning is carried out to align the PSD position sensor units of each ring, and the control logic of simultaneous emission and measurement of laser and PSD eliminates the influence of ambient background light, and realizes the PSD position of each position sensor unit Absolutely scaled measurements on and across the entire primary reflector surface.

As shown in Fig. 1, the radio telescope antenna surface shape absolute calibration method of the present embodiment, the steps are as follows:

1) Install a PSD position sensor unit on the monitoring position on each panel of the main reflective surface. The photosensitive surface of the PSD position sensor is parallel to the central axis of the main reflective surface to form several PSD position sensor circles. The detection zero position of each PSD position sensor Consistent calibration in the laboratory before installation;

2) A linear guide rail 3 is installed on the central axis 6 of the antenna, and a ring laser 4 is installed on the linear guide rail 3. The emission direction of the ring laser 4 is perpendicular to the central axis 6, and can slide up and down along the linear guide rail 3, so as to be consistent with each circle. The target surface position of the PSD position sensor is precisely aligned, and the ring laser 4 emits a circle of laser light 7 to form a light circle on the circle panel at the same height. upper imaging;

3) Controlling the ring laser 4 and the PSD position sensor 211 to transmit and collect signals simultaneously;

4) According to the different positions of the ring laser 4 along the central axis, the pre-calibrated position error is calculated based on the theoretical surface shape of the antenna, and the imaging position of each ring laser 4 in the direction perpendicular to the central axis 6 based on the calibration is obtained ;

5) Collect the position of each PSD position sensor 211 in each circle, and obtain the height error of the panel 11 at the position of each PSD position sensor in each circle;

6) Compare the positions 211 of the PSD position sensors on all circles with the absolute accurate positions of the corresponding ring lasers 4 to obtain the splicing error of the panel 11 of the entire antenna.

Example 2

As shown in Figure 2, the difference between this embodiment and the previous example is that a support shaft 5 is provided at the central axis 6, and six ring lasers 4 are arranged along the height direction on the support shaft 5, and each ring laser 4 corresponds to a PSD position Sensor circle 21.

On the main reflective surface 1 formed by splicing a large number of panels 11, place a PSD position sensor unit 211 on the contour circles along the direction of the central axis 6 at the position to be measured, and place the PSD position sensor unit 211. The PSD position sensor unit 211 includes PSD, The support mechanism and packaging have highly consistent structural dimensions and installation positioning interfaces, and the zero-crossing point is uniformly calibrated in the laboratory, and on the fixed support shaft 5 at a fixed position parallel to the central axis of the main reflection surface, how accurate is the installation? A fixable ring laser 4, through the surface shape formula of the main reflection surface, the height position of the PSD position circle and multiple installation positions of the ring laser on the high-precision fixed support frame can be calculated, so as to be in the direction along the central axis 6 On the other hand, align the whole circle of PSD units with multiple accurately positioned ring lasers, and use the control logic of simultaneous emission and measurement of the ring laser 4 and the PSD position sensor 211 to eliminate the influence of ambient background light and realize the absolute position of each PSD. Scaled measurements and absolute scaled measurements of the entire primary reflector.

As shown in Figure 2, the radio telescope antenna surface shape absolute calibration method of the present embodiment, the steps are as follows:

1) Install a PSD position sensor unit on the monitoring position on each panel of the main reflective surface. The photosensitive surface of the PSD position sensor is parallel to the central axis of the main reflective surface to form several PSD position sensor circles. The detection zero position of each PSD position sensor Consistent calibration in the laboratory before installation;

2) Install the support shaft 5 at the central axis 6 of the antenna, and install ring lasers 4 sequentially on the support shaft 5 along the height direction. The emission direction of each ring laser 4 is perpendicular to the central axis 6, and corresponds to a PSD position sensor circle 21 . Each ring laser 4 emits a circle of laser light 7 to form a light circle on the same height circle panel, and the light circle is of the same height along the central axis of the antenna, and is imaged on the corresponding PSD position sensor circle;

3) Controlling the ring laser 4 and the PSD position sensor 211 to transmit and collect signals simultaneously;

4) According to the different positions of the ring laser 4 along the central axis, the pre-calibrated position error is calculated based on the theoretical surface shape of the antenna, and the imaging position of each ring laser 4 in the direction perpendicular to the central axis 6 based on the calibration is obtained ;

5) Collect the position of each PSD position sensor 211 in each circle, and obtain the height error of the panel 11 at the position of each PSD position sensor in each circle;

6) Compare the positions 211 of the PSD position sensors on all circles with the absolute accurate positions of the corresponding ring lasers 4 to obtain the splicing error of the panel 11 of the entire antenna.

What is not described in detail in the present invention belongs to the known technology in the art.

Claims (7)

1. a radio telescope antenna surface shape absolute calibration device is characterized in that the device is made up of a PSD position sensor array, a support shaft, a ring laser and a control circuit, and the PSD position sensor array is composed of some coaxial PSD position sensors Each PSD position sensor circle is composed of several PSD position sensor units centered on multiple position points on the central axis, and the photosensitive surface is facing and parallel to the central axis; the support shaft is arranged on the central axis, The support shaft is provided with the ring laser, and the laser emission direction of the ring laser is perpendicular to the central axis; the control circuit is used to control the PSD position sensor unit and the ring laser to collect and process the signals. 2 . The device according to claim 1 , wherein more than one ring laser is arranged on the central axis, and the number and position of the ring laser correspond to the circle of the PSD position sensor. 3. The device according to claim 1, wherein the supporting shaft is a linear guide rail, the ring laser is slidably connected to the linear guide rail, and the ring laser is connected to a driving device. 4. The device according to claim 3, wherein a positioning mechanism for setting the position of the ring laser is provided on the linear guide rail. 5. a radio telescope antenna surface absolute calibration method is characterized in that the steps are as follows: 1) Install a PSD position sensor on the monitoring position on each panel of the main reflective surface. The photosensitive surface of the PSD position sensor is parallel to the central axis of the main reflective surface to form a number of PSD position sensor circles. The detection zero position of each PSD position sensor is at Consistent calibration in the laboratory before installation; 2) A ring laser is installed on the central axis of the antenna. The emission direction of the ring laser is perpendicular to the central axis, and the height along the axis is precisely aligned with the target surface position of all PSD position sensors in each circle. The ring laser emits a circle of laser light at the same A light circle is formed on the height circle panel, and the light circle is at the same height along the central axis of the antenna, and is imaged on the corresponding PSD position sensor circle; 3) Control the ring laser and the PSD position sensor to emit and collect signals at the same time; 4) According to the different positions of the ring laser along the direction of the central axis, the pre-calibrated position error is calculated, and the imaging position of each ring laser in the direction perpendicular to the central axis based on the calibration is obtained through calculation of the theoretical surface shape of the antenna; 5) Collect the position of each PSD position sensor in each circle, and obtain the height error of the panel at the position of each PSD position sensor in each circle; 6) Compare the position of the PSD position sensor on all circles with the absolute accurate position of each corresponding ring laser to obtain the panel splicing error of the entire antenna. 6 . The method according to claim 5 , wherein in step 2), several ring lasers are provided on the central axis of the antenna, and one ring laser corresponds to one PSD position sensor circle. 7. The method according to claim 5, characterized in that, in the step 2), a ring laser is provided on the central axis of the antenna, and the ring laser can move up and down along the central axis, and each PSD position sensor circles one by one The rings are precisely aligned.