Method for manufacturing a primary reflector and observation device

Abstract

To observe the earth or a space object with high accuracy, while achieving a reduction in size and cost of an observation satellite.SOLUTION: A main reflection mirror manufacturing method 600 for manufacturing a main reflection mirror formed of three or more segmented mirrors is as follows. With a target value of a surface shape in which the focal distances of all the segmented mirrors match each other and the wave front aberration of every segmented mirror becomes equal to or less than an allowable value as a processing target value, grinding and polishing a base material to be material of the main reflection mirror, subsequently measuring the wave front aberration and the surface shape of every segmented mirror, and deriving the difference between the processing target value and a measured value due to manufacturing variation. Setting the target value of the surface shape in which the amount of variation in the focal distances of all the segmented mirrors becomes minimum and the wave front aberration of every segmented mirror becomes equal to or less than the allowable value as a corrected processing target value, and executing corrected polishing processing of polishing every segmented mirror.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present disclosure relates to techniques for observing Earth or space objects, and more particularly to a method for manufacturing a primary reflector and an observation device. [Background technology]

[0002] Remote sensing technology, which uses optical observation equipment mounted on low-earth orbit satellites to observe the ground, has become established in society. In recent years, there has been a desire to realize optical observation equipment that can continuously observe the ground from a geostationary orbit at an altitude of approximately 36,000 km. For this reason, there are high expectations for improvements in the performance of optical observation equipment that can observe the ground from a distance with high resolution and high definition. Increasing the effective aperture diameter is an effective means for improving optical performance such as resolution or SN ratio (signal-to-noise ratio).

[0003] Patent Document 1 discloses a method for observing space objects such as space debris. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-218834 Summary of the Invention [Problem to be solved by the invention]

[0005] The method of Patent Document 1 requires a laser transmitter for irradiating the space debris with laser light in addition to a camera, which makes it difficult to reduce the size and cost of the observation satellite.

[0006] The present disclosure aims to manufacture a high-performance main reflector, thereby enabling observation satellites to be made smaller and less expensive while still enabling highly accurate observation of the Earth or space objects. [Means for solving the problem]

[0007] A primary reflector manufacturing method according to the present disclosure, which is a primary reflector manufacturing method for manufacturing a primary reflector provided in an optical observation device that observes the Earth or a space object from space, comprising: The main reflector is composed of three or more segmented mirrors, The target processing value is set to a target value for the surface shape that will make the focal lengths of all the mirror segments the same and that will make the wavefront aberration of each mirror segment below an allowable value. After grinding and polishing the base material that will be the material for the main reflector, the wavefront aberration and surface shape of each mirror segment are measured, and the difference between the target processing value and the actual measured value due to manufacturing variations is calculated. The target values for the surface shape that minimize the amount of variation in focal length of all the segmented mirrors and make the wavefront aberration of each segmented mirror below an allowable value are set as correction processing target values, and correction polishing is performed to polish each segmented mirror. [Effects of the Invention]

[0008] According to the present disclosure, a high-performance main reflector composed of segmented mirrors can be manufactured, enabling observation satellites to be made smaller and less expensive while still enabling highly accurate observation of the Earth or space objects. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of an observation system according to the first embodiment. [Figure 2] FIG. 1 is a diagram showing an example of the configuration of an observation satellite according to the first embodiment. [Figure 3] FIG. 1 is a diagram showing a configuration example of ground equipment according to a first embodiment. [Figure 4] FIG. 2 is a diagram showing an example of the configuration of a main reflector according to the first embodiment. [Figure 5] FIG. 1 is a diagram showing an example of the configuration of a main reflector manufacturing system according to the first embodiment. [Figure 6] FIG. 1 is a diagram showing an example of the configuration of a main reflector manufacturing system according to the first embodiment. [Figure 7] 3 is a diagram showing the flow of a method for manufacturing a main reflector according to the first embodiment. [Figure 8]5A to 5C are diagrams showing examples of different radii of curvature in the manufacturing stage according to the first embodiment. [Figure 9] FIG. 10 is a diagram showing a state in which correction polishing has been performed in the manufacturing stage according to the first embodiment to eliminate the curvature radius error. [Figure 10] FIG. 10 is a diagram showing a configuration example of an observation device according to a second embodiment. [Figure 11] 10A and 10B are diagrams showing an example of a method for adjusting a main reflector in an observation device according to the second embodiment. [Figure 12] FIG. 10 is a diagram showing a state in which the curvature radius error has been eliminated by correction polishing on the orbit in the observation device according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In each drawing, identical or corresponding parts are designated by the same reference numerals. In the description of the embodiments, the description of identical or corresponding parts will be omitted or simplified as appropriate. In addition, the size relationships of the components in the following drawings may differ from the actual size relationships. In addition, in the description of the embodiments, directions or positions such as "upper," "lower," "left," "right," "front," "rear," "front," and "back" may be indicated. These notations are used merely for the convenience of explanation and do not limit the arrangement or orientation of components such as devices, instruments, or parts.

[0011] ***Configuration Description*** Embodiment 1 An example of the configuration of an observation system 100 according to this embodiment will be described with reference to FIG. The observation system 100 is a system for observing the Earth 101 or a space object 110 . "Observation" includes concepts such as "monitoring" or "photography." A space object 110 is an object that exists in space. For example, the space object 110 orbits the Earth 101 in a geostationary orbit 103.

[0012] The observation system 100 includes an observation satellite 200 . The observation satellite 200 is an artificial satellite that orbits the Earth 101 . The observation satellite 200 orbits the Earth 101 in or near the geostationary orbit 103 . The observation satellite 200 optically photographs the space object 110 from an altitude different from the altitude at which the space object 110 is located. The observation satellite 200 also optically photographs the Earth 101.

[0013] The altitude of geostationary orbit 103 is approximately 36,000 kilometers. Artificial satellites called geostationary satellites orbit in a geostationary orbit 103 in synchronization with the rotation of the Earth 101. That is, a geostationary satellite orbits the geostationary orbit 103 once per day. In other words, a geostationary satellite orbits the geostationary orbit 103 once every 24 hours. Space object 110, like a geostationary satellite, orbits geostationary orbit 103 once per day. The observation satellite 200 orbits the geostationary orbit 103 or in the vicinity of the geostationary orbit 103 once a day. The directions in which the space object 110 and the observation satellite 200 orbit are the same as the directions in which geostationary satellites orbit.

[0014] Light from the sun 102 is called sunlight. The side of the Earth 101 that is exposed to sunlight is referred to as the near side of the Earth 101 . The side of the Earth 101 that is not exposed to sunlight is referred to as the far side of the Earth 101. In FIG. 1, a space object 110 and an observation satellite 200 each orbit around the near side of the Earth 101 .

[0015] An example of the configuration of an observation satellite 200 according to this embodiment will be described with reference to FIG. The observation satellite 200 includes an observation device 201 , a satellite control device 202 , a communication device 203 , a propulsion device 204 , an attitude control device 205 , and a power supply device 206 .

[0016] The observation device 201 is a device for observing the Earth 101 or a space object 110 from space. The observation device 201 optically photographs the Earth 101 or a space object 110 flying at an altitude different from the orbital altitude of the observation satellite 200. Specifically, the observation device 201 is a visible optical sensor. The observation device 201 is also called an optical observation device. The observation device 201 generates observation data. The observation data is data obtained by observations performed by the observation device 201. For example, the observation data corresponds to data representing an image of the Earth 101 or a space object 110.

[0017] The satellite control device 202 is a computer that controls the observation satellite 200 . The satellite control device 202 controls the observation device 201, the propulsion device 204, and the attitude control device 205 according to a predetermined procedure or in accordance with various commands transmitted from the ground facility 500, which will be described later.

[0018] The communication device 203 is a device that communicates with the ground equipment 500 . The communication device 203 transmits the observation data to the ground equipment 500. The communication device 203 also receives various commands transmitted from the ground equipment 500.

[0019] The propulsion device 204 is a device that provides thrust to the observation satellite 200 and changes the velocity of the observation satellite 200 . Specifically, the propulsion device 204 is an electric propulsion device, for example, an ion engine or a Hall thruster.

[0020] The attitude control device 205 is a device for controlling the attitude elements of the observation satellite 200 . The attitude control device 205 changes the attitude elements of the observation satellite 200 in a desired direction, or maintains the attitude elements of the observation satellite 200 in a desired direction. Specifically, the attitude elements of the observation satellite 200 are the attitude of the observation satellite 200, the angular velocity of the observation satellite 200, and the line of sight of the observation device 201. The attitude control device 205 includes an attitude sensor, an actuator, and a controller. The attitude sensor is a device such as a gyroscope, an earth sensor, a sun sensor, a star tracker, a thruster, or a magnetic sensor. The actuator is a device such as an attitude control thruster, a momentum wheel, a reaction wheel, or a control moment gyro. The controller controls the actuator by executing a control program based on measurement data obtained by the attitude sensor or in accordance with control commands from the ground facility 500.

[0021] The power supply unit 206 includes a solar cell, a battery, a power control device, and the like, and supplies power to each device of the observation satellite 200 .

[0022] The satellite control device 202 will now be described in more detail. The satellite controller 202 includes processing circuitry. The processing circuit may be dedicated hardware or a processor that executes a program stored in a memory. The processing circuit functions as an observation control unit that controls the propulsion device 204. In the processing circuit, some functions may be realized by dedicated hardware and the remaining functions may be realized by software or firmware, i.e., the processing circuit may be realized by hardware, software, firmware, or a combination thereof. Dedicated hardware may be, for example, a single circuit, a complex circuit, a programmed processor, parallel programmed processors, an ASIC, an FPGA, or a combination thereof. ASIC is an abbreviation for Application Specific Integrated Circuit. FPGA is an abbreviation for Field Programmable Gate Array.

[0023] The pointing function of the observation satellite 200 will now be explained in more detail. The observation satellite 200 has a pointing function for directing the observation direction toward the observation target. For example, the observation satellite 200 is equipped with a reaction wheel. The reaction wheel is a device for controlling the attitude of the observation satellite 200. The reaction wheel controls the attitude of the observation satellite 200, thereby realizing body pointing. For example, the observation device 201 is equipped with a pointing mechanism. The pointing mechanism is a mechanism for changing the line of sight of the observation device 201. For example, a drive mirror is used for the pointing mechanism.

[0024] The observation function of the observation device 201 will be explained in more detail. The observation device 201 has a variable resolution function and an autofocus function. The variable resolution function is a function that changes the resolution during observation. The autofocus function is a function for focusing on an object to be observed.

[0025] An example of the configuration of the ground facility 500 according to this embodiment will be described with reference to FIG. The ground equipment 500, for example, controls the program of the observation satellite 200. The ground equipment 500 is an example of a ground device. The ground equipment is composed of a ground station such as a ground antenna device, a communication device connected to the ground antenna device, or a computer, and ground equipment as a server or terminal connected to the ground station via a network. The ground equipment may also include a communication device mounted on a moving object such as an aircraft, a self-propelled vehicle, or a mobile terminal.

[0026] The ground facility 500 is a computer that controls the observation satellite 200 by communicating with the observation satellite 200. The ground facility 500 includes a processor 910, as well as other hardware such as a memory 921, an auxiliary storage device 922, an input interface 930, an output interface 940, and a communication device 950. The processor 910 is connected to the other hardware via signal lines and controls this other hardware.

[0027] The ground facility 500 includes, for example, as functional elements, an orbit control command generation unit 510 and an analysis and prediction unit 520. The functions of the orbit control command generation unit 510 and the analysis and prediction unit 520 are realized by hardware or software.

[0028] The communication device 950 transmits and receives signals for tracking and controlling the observation satellite 200. The communication device 950 also transmits an orbit control command 55 to the observation satellite 200. The analysis and prediction unit 520 analyzes and predicts the orbit of the observation satellite 200 . The orbit control command generator 510 generates an orbit control command 55 to be transmitted to the observation satellite 200 .

[0029] The ground equipment 500 includes a processor 910, as well as other hardware such as a memory 921, an auxiliary storage device 922, an input interface 930, an output interface 940, and a communication device 950. The processor 910 is connected to the other hardware via signal lines and controls the other hardware.

[0030] The processor 910 is a device that executes a control program, which is a program that realizes the function of controlling the observation satellite 200. The processor 910 is an integrated circuit (IC) that performs arithmetic processing. Specific examples of the processor 910 include a central processing unit (CPU), a digital signal processor (DSP), and a graphics processing unit (GPU).

[0031] The memory 921 is a storage device that temporarily stores data. Specific examples of the memory 921 include a static random access memory (SRAM) and a dynamic random access memory (DRAM). The auxiliary storage device 922 is a storage device that stores data. A specific example of the auxiliary storage device 922 is a HDD. The auxiliary storage device 922 may also be a portable storage medium such as an SD (registered trademark) memory card, CF, NAND flash, a flexible disk, an optical disk, a compact disk, a Blu-ray (registered trademark) disk, or a DVD. Note that HDD is an abbreviation for Hard Disk Drive. SD (registered trademark) is an abbreviation for Secure Digital. CF is an abbreviation for CompactFlash (registered trademark). DVD is an abbreviation for Digital Versatile Disk.

[0032] The input interface 930 is a port connected to an input device such as a mouse, a keyboard, or a touch panel. Specifically, the input interface 930 is a USB (Universal Serial Bus) terminal. Note that the input interface 930 may also be a port connected to a LAN (Local Area Network). The output interface 940 is a port to which a cable of a display device such as a display is connected. Specifically, the output interface 940 is a USB terminal or an HDMI (registered trademark) (High Definition Multimedia Interface) terminal. Specifically, the display is an LCD (Liquid Crystal Display).

[0033] The communication device 950 includes a receiver and a transmitter, and is specifically a communication chip or a network interface card (NIC).

[0034] The control program is read into the processor 910 and executed by the processor 910. The memory 921 stores not only the control program but also an OS (Operating System). The processor 910 executes the control program while running the OS. The control program and the OS may be stored in an auxiliary storage device 922. The control program and the OS stored in the auxiliary storage device 922 are loaded into the memory 921 and executed by the processor 910. Note that part or all of the control program may be incorporated into the OS.

[0035] The ground equipment 500 may include multiple processors that replace the processor 910. These multiple processors share the task of executing a program. Each processor is a device that executes a program, just like the processor 910.

[0036] Data, information, signal values and variable values used, processed or output by the program are stored in memory 921, secondary storage device 922, or registers or cache memory within processor 910.

[0037] The "part" of each part of the ground equipment may be read as "processing," "procedure," "means," "step," "process," or "circuitry." Also, the "processing" of control processing may be read as "program," "program product," or "computer-readable recording medium on which a program is recorded." The control program causes a computer to execute each process, procedure, means, stage, process, or circuitry of the ground equipment, where the "part" of each part is read as "process," "procedure," "means," "stage," "process," or "circuitry." Also, the control method is a method performed by the ground equipment executing the control program. The control program may be provided by being stored in a computer-readable recording medium, or each program may be provided as a program product.

[0038] ***Explanation of the main reflector and its manufacturing method*** FIG. 4 is a schematic diagram showing an example of the configuration of the main reflector 21 according to this embodiment. FIG. 5 shows an example of the configuration of a main reflector manufacturing system 501 according to this embodiment. FIG. 6 shows an example of the configuration of a main reflector manufacturing system 501 according to this embodiment. FIG. 7 is a diagram showing the flow of a main reflector manufacturing method 600 according to this embodiment. FIG. 8 is a diagram showing an example in which the radius of curvature is different in the manufacturing stage according to this embodiment. FIG. 9 is a diagram showing a state in which the curvature radius error has been eliminated by corrective polishing in the manufacturing stage according to this embodiment.

[0039] The main reflector 21 provided in the observation device 201 and the main reflector manufacturing method 600 for manufacturing the main reflector 21 will be described. 4, the observation device 201 includes a main reflecting mirror 21. The main reflecting mirror 21 is made up of, for example, three or more segmented mirrors 211.

[0040] 5, the main reflecting mirror manufacturing system 501 includes a wavefront aberration measurement device 810 that measures the wavefront aberration of the segmented mirror 211, and a surface shape measurement device 820 that measures the surface shape of the segmented mirror 211. The wavefront aberration of the segmented mirror 211 measured by the wavefront aberration measurement device 810 and the surface shape of the segmented mirror 211 measured by the surface shape measurement device 820 are output to a processing target value deriving device 830. The processing target value deriving device 830 derives the processing target value or the corrected processing target value.

[0041] 6, the main reflector manufacturing system 501 also includes a polishing device 840 that grinds and polishes the base material that will be the material for the main reflector 21. The polishing device 840 polishes the mirror segments 211 in accordance with the processing target values or corrected processing target values transmitted from the processing target value deriving device 830. The processing target value derivation device 830 is a computer that transmits processing target values or corrected processing target values to the polishing device 840 based on the wavefront aberration and surface shape of the segmented mirror 211 received from the wavefront aberration measuring device 810 and the surface shape measuring device 820. The primary reflector manufacturing method 600 is performed by the primary reflector manufacturing system 501 .

[0042] The main reflector manufacturing method 600 by the main reflector manufacturing system 501 for manufacturing the main reflector 21 is as follows. In step S101, the processing target value deriving device 830 sets, as the processing target value, the target value of the surface shape where the focal lengths of all the segmented mirrors 211 are the same and the wavefront aberration of each segmented mirror 211 is equal to or less than the allowable value.

[0043] FIG. 8 is a diagram showing an example in which the radius of curvature is different in the manufacturing stage according to this embodiment. Based on the wavefront aberration and surface shape of the split mirror 211 received from the wavefront aberration measuring device 810 and the surface shape measuring device 820, the processing target value derivation device 830 sets, as the processing target value, a target value for the surface shape at which the focal lengths of all the split mirrors 211 are the same and the wavefront aberration of each split mirror 211 is below the allowable value.

[0044] In step S102, the main reflector manufacturing system 501 uses the polishing device 840 to grind and polish the base material that will be the material for the main reflector 21. After the main reflector manufacturing system 501 has used the polishing device 840 to grind and polish the base material that will be the material for the main reflector, the system proceeds to step S103.

[0045] In step S103, the processing target value deriving device 830 measures the wavefront aberration and surface shape of each of the segmented mirrors 211, and derives the difference between the processing target value and the actual measurement value due to manufacturing variations. In step S104, the processing target value deriving device 830 sets, as the corrected processing target value, the target value of the surface shape that minimizes the amount of variation in the focal lengths of all the segmented mirrors 211 and makes the wavefront aberration of each segmented mirror 211 equal to or less than the allowable value. Then, the processing target value deriving device 830 transmits a corrected polishing command including the corrected processing target value to the polishing device 840. In step S104, the polishing device 840 performs the correction polishing process to polish each of the mirror segments 211 using the correction target value.

[0046] Through the above process, as shown in FIG. 9, a main reflecting mirror 21 is obtained in a state in which the curvature radius error has been eliminated by correction polishing during the manufacturing stage.

[0047] The observation device 201 according to this embodiment is equipped with a main reflector 21 made up of a plurality of mirror segments 211 that have been polished and corrected using the main reflector manufacturing method 600.

[0048] Optical observation instruments mounted on satellites generally have a single main reflector. However, efforts are being made to enlarge the main reflector in order to improve resolution or signal-to-noise ratio. It is difficult to further enlarge a single main reflector due to limitations in material manufacturability, restrictions on processing equipment such as grinding and polishing, and limitations on the ability to withstand the vibration environment during rocket launch when optical observation instruments are launched into space. Therefore, a main reflector that combines segmented mirrors to perform aperture synthesis is desired.

[0049] In the case of a main reflecting mirror manufactured by combining mirror segments, it is rational to first grind and polish the base material of each mirror segment, and then combine the mirror segments to form the main reflecting mirror. In instruments with a single primary reflector, the primary reflector is polished during manufacture to suppress wavefront aberrations, and manufacturing errors in focal length can be adjusted by adjusting the relative positions of optical components such as secondary mirrors. On the other hand, in the case of the segmented mirror system, the deterioration of optical performance caused by the relative difference in focal length of the segmented mirrors that make up the main reflector cannot be resolved by adjusting the relative positions of optical system components such as the secondary mirror.

[0050] For a single mirror, wavefront measurement is performed using an interferometer after polishing with the sole aim of correcting wavefront aberration, and then correction polishing is carried out. In contrast, the main reflector manufacturing method according to this embodiment adds measurement of the surface shape of the segmented mirrors, minimizes the variation in focal length of all the segmented mirrors, and resets the correction target value to keep the wavefront aberration within the allowable range before carrying out correction polishing.

[0051] A contact-type 3D measuring device is one of the candidates for measuring the surface shape of the segmented mirror. However, in order to measure large mirror surfaces at high density, it is also effective to use a contact-type line profiler, which enables continuous measurement in one direction based on the principle of a 3D measuring device.

[0052] The main reflector manufacturing method according to this embodiment has the advantage of realizing a main reflector with excellent optical performance by eliminating errors in the focal length of each segment of the main reflector in advance during the manufacturing stage.

[0053] ***Other Configurations*** <Variation 1> Main reflector manufacturing method 600 according to this embodiment may be applied to a main reflector 21 made up of six or more segmented mirrors 211. Main reflector manufacturing method 600 is performed using main reflector manufacturing system 501, for example. The main reflector manufacturing system 501 manufactures a main reflector 21 composed of six or more mirror segments 211. First, the wavefront aberration and surface shape of each mirror segment 211 are measured. The main reflector manufacturing system 501 then sets target values for the surface shape that will improve the wavefront aberration and minimize the variation in focal length of all mirror segments as processing target values. The main reflector manufacturing system 501 then performs correction polishing on each mirror segment using the processing target values.

[0054] In instruments with a single primary reflector, the primary reflector is polished during manufacture to suppress wavefront aberrations, and manufacturing errors in focal length can be adjusted by adjusting the relative positions of optical components such as secondary mirrors. On the other hand, in the case of the segmented mirror system, the deterioration of optical performance caused by the relative difference in focal length of the segmented mirrors that make up the main reflector cannot be resolved by adjusting the relative positions of optical system components such as the secondary mirror. The main reflector manufacturing method according to this embodiment has the advantage of realizing a main reflector with excellent optical performance by eliminating errors in the focal length of each segment of the main reflector in advance during the manufacturing stage.

[0055] <Variation 2> In this embodiment, the functions of the ground equipment 500 are realized by software. As a modification, the functions of the ground equipment 500 may be realized by hardware.

[0056] The ground equipment 500 includes an electronic circuit in place of the processor 910 . The electronic circuit is a dedicated electronic circuit that realizes the functions of the ground equipment 500. The electronic circuit may be specifically a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, a logic IC, a GA, an ASIC, or an FPGA. GA is an abbreviation for Gate Array. ASIC is an abbreviation for Application Specific Integrated Circuit. FPGA is an abbreviation for Field-Programmable Gate Array. The functions of the ground equipment 500 may be realized by one electronic circuit, or may be realized by distributing the functions across multiple electronic circuits. As another modification, some functions of the ground equipment 500 may be realized by electronic circuits, and the remaining functions may be realized by software.

[0057] Each of the processor and the electronic circuit is also called processing circuitry. That is, in the ground equipment 500, the functions of the ground equipment 500 are realized by the processing circuitry. The wavefront aberration measuring device 810, the surface shape measuring device 820, the processing target value deriving device 830, and the polishing device 840 also include at least a part of the hardware described in this embodiment.

[0058] Embodiment 2 In this embodiment, the following mainly describes differences or additions from embodiment 1. Note that the same components as those in embodiment 1 are given the same reference numerals, and the description thereof may be omitted.

[0059] FIG. 10 is a schematic diagram showing an example of the configuration of an observation device 201 according to this embodiment. FIG. 11 is a diagram showing an example of a main reflector adjustment method 601 in the observation device 201 according to this embodiment. FIG. 12 is a diagram showing a state in which the curvature radius error is eliminated by on-orbit correction polishing in the observation device 201 according to this embodiment.

[0060] The observation device 201 according to this embodiment has a main reflecting mirror 21 made up of six or more segmented mirrors 211, and observes the Earth 101 or a space object 110 from space.

[0061] The observation device 201 includes a wavefront measuring device 213 . Each of the six or more segmented mirrors 211 is provided with a pointing direction changing device 212 . The pointing direction changing device 212 adjusts the relative position and relative angle of the split mirror 211 in a direction that improves the wavefront aberration of the main reflecting mirror 21 acquired by a wavefront measuring device in the visible wavelength band installed near the detection image plane.

[0062] The left diagram in Fig. 11 shows an example in which wavefront aberration deteriorates on the trajectory, while the right diagram in Fig. 11 shows an example in which wavefront aberration is improved by adjusting the segmented mirror 211.

[0063] According to the main reflector adjustment method 601 for the observation device 201 of this embodiment, as shown in FIG. 12, the main reflector 21 is obtained in a state in which the curvature radius error has been eliminated by correction polishing on orbit.

[0064] Observation devices with a single main reflector are widely used in space, but there is a limit to the maximum size that can be manufactured. Since the performance of an optical system depends on the effective aperture diameter, an observation device equipped with a larger diameter main reflector has long been awaited, with a main reflector composed of segmented mirrors. When aperture synthesis is performed on the reflected light from the segmented mirrors, positional and angular errors between the segmented mirrors cause deterioration of wavefront aberration, which is an index of optical performance. In the observation device according to this embodiment, the wavefront measurement device measures wavefront aberration in the visible wavelength band, and the mechanical adjustment device adjusts the relative position and angle of the segmented mirrors. Therefore, the observation device according to this embodiment can realize a segmented mirror-based monitoring device that suppresses wavefront aberration, which has the effect of enabling high-resolution, high-sensitivity monitoring from space. As the wavefront measuring device, a wavefront sensor such as a Shack-Hartmann sensor is used.

[0065] In the above first and second embodiments, each unit of each system and each device has been described as an independent functional block. However, the configuration of each system and each device does not have to be the same as that of the above-described embodiments. The functional blocks of each system and each device may have any configuration as long as they can realize the functions described in the above-described embodiments. Furthermore, each system and each device may be a single device or a system composed of multiple devices. Furthermore, it is possible to combine multiple parts of the first and second embodiments. Alternatively, it is possible to implement only one part of these embodiments. In addition, it is possible to implement any combination of these embodiments, either as a whole or in part. That is, in the first and second embodiments, the embodiments can be freely combined, or any of the components in each embodiment can be modified, or any of the components in each embodiment can be omitted.

[0066] It should be noted that the above-described embodiments are essentially preferred examples and are not intended to limit the scope of the present disclosure, the scope of application of the present disclosure, and the scope of use of the present disclosure. The above-described embodiments can be modified in various ways as necessary. [Explanation of symbols]

[0067] 55 Orbit control command, 100 Observation system, 101 Earth, 102 Sun, 103 Geostationary orbit, 110 Space object, 200 Observation satellite, 201 Observation equipment, 202 Satellite control device, 203 Communication equipment, 204 Propulsion device, 205 Attitude control device, 206 Power supply device, 21 Main reflector, 211 Segmented mirror, 212 Pointing direction change device, 213 Wavefront measurement device, 500 Ground equipment, 501 Main reflector manufacturing system, 510 Orbit control command generation unit, 520 Analysis prediction unit, 600 Main reflector manufacturing method, 601 Main reflector adjustment method, 810 Wavefront aberration measurement device, 820 Surface shape measurement device, 830 Processing target value derivation device, 840 Polishing device, 910 Processor, 921 Memory, 922 Auxiliary storage device, 930 Input interface, 940 Output interface, 950 communication device.

Claims

1. A method for manufacturing a main reflector provided in an optical observation device that observes the Earth or a space object from space, comprising the steps of: The main reflector is composed of three or more segmented mirrors, The target processing value is set to the target surface shape value that will make the focal lengths of all the mirror segments the same and the wavefront aberration of each mirror segment below the allowable value. After grinding and polishing the base material that will be the material for the main reflector, the wavefront aberration of each mirror segment is measured, and the surface shape is measured with a contact-type three-dimensional measuring device or a contact-type line profiler, and the difference between the target processing value and the actual measured value due to manufacturing variations is derived. A method for manufacturing a main reflector in which a target surface shape value is set as a correction processing target value so that the variation in focal length of all the segmented mirrors is minimized and the wavefront aberration of each segmented mirror is within an allowable value, and correction polishing is performed to polish each segmented mirror.

2. 2. An observation device comprising a main reflector comprising a plurality of segmented mirrors that have been polished and corrected by the method for manufacturing a main reflector according to claim 1.

3. An observation device for observing the Earth or a space object from space, comprising a main reflector composed of six or more segmented mirrors, Each of the six or more segmented mirrors is provided with a pointing direction changing device; The pointing direction changing device is An observation device that acquires the wavefront aberration of the main reflector using a wavefront measurement device in the visible wavelength band installed near the detection image plane, and adjusts the relative positions and angles of the segmented mirrors in a direction that improves the acquired wavefront aberration.

4. A method for manufacturing a main reflector comprising six or more segmented mirrors, A method for manufacturing a main reflector in which the wavefront aberration of each segment mirror is measured, and the surface shape is measured using a contact-type three-dimensional measuring device or a contact-type line profiler, to improve the wavefront aberration and perform corrective polishing, using the target value for the surface shape that minimizes the variation in focal length of all the segment mirrors as the processing target value.

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