Secondary mirror pose adjusting mechanism for large-aperture large-field-of-view telescope

Abstract

The invention relates to the technical field of optical instruments, and particularly provides a secondary mirror pose adjusting mechanism for a large-aperture large-field-of-view telescope. The secondary mirror pose adjusting mechanism comprises a base and supporting legs, one end of each supporting leg is connected with the upper surface of the base, and the other end of each supporting leg is connected with a rack of the telescope; and the lower surface of the base is connected with the secondary mirror assembly. And the posture of the secondary mirror is adjusted by adjusting the lengths of the supporting legs. The number of the supporting legs is six, the supporting legs comprise three first supporting legs which are vertically arranged and three second supporting legs which are horizontally arranged, and the first supporting legs and the second supporting legs act independently on secondary mirror pose adjustment and are not affected by coupling. The secondary mirror pose adjusting mechanism provided by the invention has a new structure, realizes convenient and effective connection with the rack of the telescope, and meets the installation space requirements of a correction lens group and a detector. The secondary mirror pose adjusting mechanism has a simpler resolving method, and the design and implementation of the driving control system are simpler.

Description

Technical Field

[0001] The present disclosure relates to the technical field of optical instruments, and more particularly, to a secondary mirror pose adjustment mechanism for a large-aperture and large-field-of-view telescope. Background Art

[0002] Astronomical optical telescopes are important instruments for observing celestial bodies, and large-field-of-view astronomical telescopes are a current research and development hotspot. Large-aperture and large-field-of-view telescopes play an important role in astronomical observations and space monitoring. First, large-aperture and large-field-of-view telescopes are important equipment for carrying out large-sky-area multi-spectral surveys. Through high-efficiency, high-quality, and high-throughput observation data, combined with multi-band and multi-methods for in-depth large-sky-area surveys, it plays a very important role in answering basic questions of cosmology. Second, large-aperture and large-field-of-view telescopes provide a large amount of observational information for astronomers to explore the influence of gravitational lenses in galaxy clusters; understand the properties of gravitational waves and X-ray burst sources, etc. In addition, in the aspect of asteroid detection, a large-aperture and large-field-of-view telescope with high sensitivity and fast scanning is also required to continuously and accurately observe the threat of near-Earth asteroids to the Earth. Therefore, building a new generation of large-field-of-view survey telescopes, providing large-scale digital image survey capabilities, and continuously breaking through in the sensitivity and time resolution of image observations has become one of the main trends in the development of ground-based optical equipment. Summary of the Invention

[0003] The purpose of the present disclosure is to provide a secondary mirror pose adjustment mechanism for a large-aperture and large-field-of-view telescope to address the technical problems in the related art. The specific solutions are as follows: An embodiment of the present application provides a secondary mirror pose adjustment mechanism for a large-aperture and large-field-of-view telescope, characterized in that it is used for the pose adjustment of the secondary mirror, including: a base, the base is a circular flat plate with parallel upper and lower surfaces, and the lower surface is connected to the secondary mirror through a secondary mirror chamber; legs, one end of the legs is connected to the upper surface, and the other end is connected to the frame of the telescope, configured to adjust the pose of the secondary mirror. Among them, there are six legs, including three first legs and three second legs. The axis direction of the first legs is perpendicular to the upper surface, and the axis direction of the second legs is parallel to the upper surface; the first legs and the second legs act independently in the secondary mirror pose adjustment without coupling effects.

[0004] In some embodiments, adjusting the lengths of the three first legs is configured to control the axial translation and tilting in two directions of the secondary mirror; adjusting the lengths of the three second legs is configured to control the axial rotation and lateral translation in two directions of the secondary mirror.

[0005] In some embodiments, the leg includes: a transmission assembly configured to provide the leg with a degree of freedom of translation along the leg axis and a degree of freedom of rotation about the leg axis; and two flexible hinges respectively disposed at both ends of the transmission assembly, each flexible hinge being configured to provide the leg with two degrees of freedom of rotation.

[0006] In some embodiments, the transmission assembly includes: a motor configured to drive the transmission assembly; and a lead screw configured to convert the rotational motion of the motor into linear motion. Wherein, the motor and the lead screw enable the transmission assembly and the leg to extend and contract, and the leg can be driven by the motor to adjust its length.

[0007] In some embodiments, along the axis of the leg, the difference between the maximum length and the minimum length that the leg can adjust is less than .

[0008] In some embodiments, both ends of the leg are respectively connected to the telescope frame and the base, and the base is connected to the secondary mirror through the secondary mirror chamber. Therefore, in response to the movement of the leg, the pose of the secondary mirror changes relative to the frame; wherein, the frame includes a central cylinder, and the axis of the central cylinder coincides with the telescope optical axis, and one end of the leg is connected to the central cylinder of the frame.

[0009] In some embodiments, the relationship between the leg length change amount and the secondary mirror pose change amount is: ; , where the Jacobian matrix is and , the length change amount of the first leg is , the length change amount of the second leg is , and the pose change amount of the secondary mirror is , , where , , represent translations in three directions, , , represent rotations in three directions.

[0010] Compared with the related art, the above solution of the embodiment of the present disclosure has at least the following beneficial effects: The secondary mirror pose adjustment mechanism for a large-aperture and large-field-of-view telescope provided by the present disclosure has a new configuration, that is, a new leg arrangement method. This new configuration enables the legs of the pose adjustment mechanism to be conveniently and effectively connected to the large-aperture and large-field-of-view telescope, meeting the installation space requirements of the corrector lens group and the detector. Compared with the existing hexapod mechanism, the design and implementation of the drive control system of the secondary mirror pose adjustment mechanism of the present invention are also simpler.

[0011] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The accompanying drawings herein are incorporated into the specification and constitute a part of this specification, showing embodiments consistent with the present disclosure and used together with the specification to explain the principles of the present disclosure. Obviously, the accompanying drawings in the following description are only some embodiments of the present disclosure. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts. In the drawings: Figure 1 is a schematic diagram of a secondary mirror pose adjustment mechanism for a large-aperture and large-field-of-view telescope shown according to an exemplary embodiment.

[0013] Figure 2 is a schematic diagram of a leg shown according to an exemplary embodiment.

[0014] Figure 3 is an internal structural schematic diagram of a transmission component in a leg shown according to an exemplary embodiment.

[0015] Figure 4 is a connection schematic diagram of a secondary mirror pose adjustment mechanism for a large-aperture and large-field-of-view telescope with the four-wing beam and the secondary mirror assembly of the telescope shown according to an exemplary embodiment.

[0016] Figure 5 is Figure 4 an exploded view of.

[0017] Figure 6 is a structural schematic diagram of a secondary mirror pose adjustment mechanism for a large-aperture and large-field-of-view telescope shown according to an exemplary embodiment.

[0018] Reference numerals: Secondary mirror pose adjustment mechanism 100; base 110, upper surface 112, wedge block 113; Leg 120, first leg 121, second leg 122; Flexible hinge 1210, transmission component 1220, roller screw shaft 1221, roller screw nut 1222, transmission plate 1223, transmission shaft 1224, harmonic reducer 1225, motor 1226, limit switch 1227, bearing 1228, bearing seat 1229, support column 1230; Secondary mirror assembly 130, secondary mirror 131, secondary mirror chamber 132; Four-wing beam 140, central cylinder 141, outer ring 142, blade 143; Detector assembly 150. Specific embodiments

[0019] In order to make the objectives, technical solutions and advantages of the present disclosure clearer, the present disclosure will be further described in detail below with reference to the accompanying drawings. Apparently, the described embodiments are only a part of the embodiments of the present disclosure, rather than all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present disclosure.

[0020] The terms used in the embodiments of the present disclosure are only for the purpose of describing specific embodiments, and are not intended to limit the present disclosure. The singular forms of "a", "the" and "said" used in the embodiments of the present disclosure and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise. "Plural" generally includes at least two, and other quantifiers are similar thereto.

[0021] It should be understood that although terms such as first, second, and third may be used in the embodiments of the present disclosure for description, these descriptions should not be limited to these terms. These terms are only used to distinguish the described objects. For example, without departing from the scope of the embodiments of the present disclosure, the first may also be referred to as the second, and similarly, the second may also be referred to as the first. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0022] It should be understood that the term " / and" used herein is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this article generally represents an "or" relationship between the associated objects before and after. The singular forms of "a", "the" and "said" are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0023] It can be further understood that the orientation or positional relationship indicated by terms such as "center", "longitudinal", "lateral", "front", "rear", "upper", "lower", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing this embodiment and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention.

[0024] In the description of the present disclosure, it should be noted that, unless otherwise clearly specified and defined, the terms "connected" and "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0025] Depending on the context, the words "if" and "when" as used herein can be interpreted as "when" or "while" or "in response to determining" or "in response to detecting". Similarly, depending on the context, the phrase "if determined" or "if detected (stated condition or event)" can be interpreted as "when determined" or "in response to determining" or "when detected (stated condition or event)" or "in response to detecting (stated condition or event)".

[0026] It should also be noted that the term "comprising", "including" or any other variation thereof is intended to cover non-exclusive inclusion, so that a commodity or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such commodity or device. Without further limitation, an element defined by the statement "comprising one..." does not exclude the presence of another identical element in the commodity or device comprising said element.

[0027] Large-aperture and large-field-of-view telescopes generally consist of a primary mirror assembly, a secondary mirror assembly, a tertiary mirror assembly, a corrector lens group, a detector, a mount, etc. The primary mirror is the main light-gathering surface of a reflecting telescope, and light is reflected by the primary mirror and reaches the secondary mirror; the secondary mirror is the second mirror that converges light, and then the light reaches the detector through the tertiary mirror, the corrector lens group, etc., to achieve imaging. The primary mirror assembly, secondary mirror assembly, tertiary mirror assembly, corrector lens group, detector, etc. are all fixed on the mount. To ensure excellent imaging quality, the optical elements such as the primary mirror, secondary mirror, and tertiary mirror in the telescope must maintain precise relative poses. However, due to the effects of structural gravity deformation, thermal loads, wind loads, etc., the mount will deform, resulting in the misalignment of the optical system, and further causing the inclination and eccentricity of each optical element, generating pose errors. The primary mirror is the heaviest in the optical system and has the most complex support system. Therefore, to maintain the relative positions between the optical elements, it is necessary to move other optical elements based on the primary mirror as a reference. Therefore, the secondary mirror, tertiary mirror, and corrector lens group all require a secondary mirror pose adjustment mechanism to achieve active adjustment and alignment. The Stewart hexapod platform widely used in many industries can be used for pose adjustment.

[0028] The prime focus structure adopted by large-aperture and large-field-of-view telescopes has certain particularities. The corrector lens group and the detector must pass through the central hole of the secondary mirror, and the corrector lens group, detector, and secondary mirror assembly are all connected to the four-wing beams of the telescope mount. This leaves rather limited space for the secondary mirror pose adjustment mechanism, especially in the radial direction. There are strict restrictions on the radial envelope size of the adjustment mechanism: the outer envelope size cannot be too large, otherwise it will affect the light-gathering area of the primary mirror; the inner envelope size cannot be too small, otherwise there will be interference with the corrector lens group and the detector in terms of structure. The complex structure and the limitation of the radial installation space result in that the traditional 3 "V" configuration Stewart hexapod platform cannot be used for the pose adjustment of the secondary mirror assembly. Therefore, the secondary mirror assembly requires a non-traditional secondary mirror pose adjustment mechanism.

[0029] To ensure the accurate pose of the secondary mirror, the adjustment mechanism needs to have precise kinematic accuracy; in addition, since there is no fast steering mirror in the large-field-of-view prime focus telescope system, there are strict vibration restrictions, which require the adjustment mechanism to have high stiffness to generate a high natural frequency.

[0030] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a secondary mirror pose adjustment mechanism for large-aperture and large-field-of-view telescopes, which meets the installation structure requirements and radial space requirements of the secondary mirror assembly of large-aperture and large-field-of-view telescopes, and at the same time has high positioning accuracy and stiffness to achieve precise adjustment of the secondary mirror pose.

[0031] The optional embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0032] A secondary mirror position and attitude adjustment mechanism 100 provided by the present invention is used for adjusting the position and attitude of the secondary mirror of a large-aperture and large-field-of-view telescope, as Figure 1 shown. The secondary mirror position and attitude adjustment mechanism 100 includes a base 110 and six legs 120. The base 110 has an upper surface 112 and a lower surface facing away from each other, and the lower surface is configured to be connected to the secondary mirror assembly 130 of the telescope. The legs 120 are disposed on the upper surface 112.

[0033] In some embodiments, the base 110 is a circular ring structure. The lower surface of the base 110 is used to connect the secondary mirror assembly 130, and the upper surface 112 of the base 110 is used to connect the legs 120. Both the upper surface 112 and the lower surface of the base 110 are perpendicular to the optical axis, which refers to the rotation symmetry center of the telescope optical system.

[0034] In some embodiments, in the secondary mirror position and attitude adjustment mechanism 100, there are also 6 legs 120 with adjustable lengths, including three first legs 121 and the remaining three are second legs 122. The axial direction of the first leg 121 is perpendicular to the upper surface 112; the axial directions of the second legs 122 are parallel to the upper surface 112.

[0035] In some embodiments, the end of the first leg 121 is directly connected to the upper surface 112, so the axial direction of the first leg 121 is perpendicular to the upper surface 112. A wedge block 113 is provided on the upper surface 112. The wedge block 113 has two mutually perpendicular planes, one of which is directly connected to the upper surface 112, and the other is connected to the end of the second leg 122. In response to the connection between the second leg 122 and the wedge block 113, the axial direction of the second leg 122 is perpendicular to the upper surface 112.

[0036] The connection manner of the first leg 121 and the second leg 122 to the base 110 is not specifically limited. The connection manner can be bolt connection, electromagnetic induction connection, or any connection manner that can achieve the fixed connection between the two.

[0037] In the present disclosure, the secondary mirror position and attitude adjustment mechanism 100 with the above configuration occupies less radial space. Therefore, it can meet the installation structure requirements and radial space requirements of the secondary mirror assembly 130 of the large-aperture and large-field-of-view telescope.

[0038] In some embodiments, as Figure 4As shown, one end of the first leg 121 is directly connected to the upper surface 112 of the base 110, and the other end is fixedly connected to the central cylinder 141 of the telescope four-wing beam 140; one end of the second leg 122 is connected to the upper surface 112 of the base 110 through the wedge block 113, and the other end is fixedly connected to the central cylinder 141 of the telescope four-wing beam 140. The four-wing beam 140 and the central cylinder 141 are part of the telescope frame and are fixed. Therefore, by adjusting the lengths of the first leg 121 and the second leg 122, the spatial position and attitude of the base 110 and the secondary mirror assembly 130 can be adjusted, and further the position and attitude adjustment of the secondary mirror 131 can be achieved.

[0039] The difference between the maximum length and the minimum length that the leg 120 can adjust is called the stroke of the leg 120. Compared with the axial dimension of the leg 120, the stroke of the leg 120 is very small, less than of the axial dimension of the leg 120. Therefore, when the secondary mirror position and attitude adjustment mechanism 100 adjusts the position and attitude of the secondary mirror, the overall configuration change of the secondary mirror position and attitude adjustment mechanism 100 is very small.

[0040] In some embodiments, the structures of the 6 legs 120 are the same. As Figure 2 shown, the leg 120 is composed of a transmission component 1220 and two flexible hinges 1210.

[0041] In some embodiments, as Figure 2 shown, the flexible hinges 1210 are arranged on both sides of the transmission component 1220. The flexible hinge 1210 can generate bending deformation in two mutually perpendicular directions, and its structural design allows it to have a certain degree of flexibility in two directions in the plane. Therefore, the flexible hinge 1210 can provide two-direction rotational degrees of freedom for the first leg 121.

[0042] As Figure 2 , Figure 3 shown, the transmission component 1220 can be equivalent to a linear displacement actuator with high axial stiffness, and can adjust and maintain the length of the leg 120. Figure 3 is a typical design of the transmission component 1220, which is structurally composed of a roller screw shaft 1221, a roller screw nut 1222, a transmission plate 1223, a transmission shaft 1224, a harmonic reducer 1225, a motor 1226, a limit switch 1227, a bearing 1228, a bearing housing 1229, and a support column 1230. The bearing housing 1229 is fixed on the harmonic reducer 1225 through the support column 1230, and the outer ring of the bearing 1228 is fixed on the bearing housing 1229. The inner ring of the bearing 1228 is fixed to the transmission plate 1223 and the transmission shaft 1224. The function of the bearing 1228 is to support the roller screw nut 1222.

[0043] In some embodiments, Figure 3 As shown, the transmission assembly 1220 is driven by the motor 1226, and the rotational motion of the motor 1226 is transmitted to the roller screw nut 1222 through the harmonic reducer 1225, the transmission shaft 1224, and the transmission plate 1223. The roller screw shaft 1221 and the roller screw nut 1222 convert the rotational motion into linear motion, and the roller screw shaft 1221 outputs the linear motion to adjust the length of the leg 120. When the motor 1226 is locked, the length of the transmission assembly 1220 remains unchanged, so that the length of the leg 120 is maintained.

[0044] The driving system of the motor 1226 is composed of power supply, drive, control, sensor and other parts to realize the control of the six motors 1226. The control system mainly realizes trajectory planning, motor drive, sensor acquisition, and position control. The hardware includes a motor drive board, a control board, and a power board. The rotation of the six motors 1226 is controlled by the above-mentioned driving system, thereby controlling the position and posture of the secondary mirror 131.

[0045] In some embodiments, the transmission assembly 1220 also has a degree of freedom to rotate around its central axis. Specifically, the roller screw shaft 1221 is used as an output shaft, and the transmission assembly 1220 does not limit its axial rotation, so the transmission assembly 1220 provides a degree of freedom of rotation. The two ends of the transmission assembly 1220 are respectively fixed to the central tube 141 and the base 110 through the flexible hinge 1210, so the degree of freedom of the transmission assembly 1220 to rotate around its central axis is limited and controllable.

[0046] The secondary mirror position adjustment mechanism 100 provided by the present invention is applied to large-aperture and large-field telescopes, such as Figure 4 , Figure 5 As shown, the large-aperture and large-field-of-view telescope includes: a secondary mirror assembly 130 , four-wing beams 140 and a secondary mirror position adjustment mechanism 100 , and the secondary mirror position adjustment mechanism 100 is connected to the secondary mirror assembly 130 and the four-wing beams 140 .

[0047] In some embodiments, Figure 4 The four-wing beam 140 includes an outer ring 142, the diameter of the outer ring 142 is greater than the diameter of the secondary mirror assembly 130, and the four-wing beam 140 also includes a central tube 141, the axis of the central tube 141 coincides with the optical axis. The four-wing beam 140 also includes blades 143, a plurality of blades 143 are provided, and the two ends of the blades 143 are respectively connected to the central tube 141 and the outer ring 142, that is, the central tube 141 is fixedly connected to the outer ring 142 through the blades 143, and the outer ring 142 is further fixed to the primary mirror assembly through structures such as a lens tube and a cross.

[0048] In some embodiments, the secondary mirror assembly 130 includes a secondary mirror 131 and a secondary mirror chamber 132. The secondary mirror chamber 132 is fixedly connected to the secondary mirror pose adjustment mechanism 100. The secondary mirror chamber 132 provides stable support and protection for the secondary mirror 131 to ensure that the secondary mirror 131 can function properly.

[0049] In some embodiments, the four-wing beam 140 is a common structure in modern ground-based large-aperture telescopes. It is located at the front end of the telescope tube and is usually only used to fix the secondary mirror assembly 130. Compared with the four-wing beam in the related art, in a large-aperture and large-field-of-view telescope, the four-wing beam 140 is also used to fix the corrector lens group and the detector assembly 150. Therefore, it has a central tube 141 with a larger size and a more complex structure. The secondary mirror pose adjustment mechanism 100 of the present disclosure can meet the installation structure requirements and radial space requirements of the secondary mirror assembly 130 in a large-aperture and large-field-of-view telescope, and has a space for accommodating the corrector lens group and the detector assembly 150.

[0050] In some embodiments, since the secondary mirror assembly 130, the corrector lens group, and the detector all need to be connected to the central tube 141 of the four-wing beam 140, therefore, in a large-aperture and large-field-of-view telescope, the radial dimension of the secondary mirror pose adjustment mechanism 100 should be limited. The radial envelope dimension of the secondary mirror pose adjustment mechanism 100 is less than or equal to 1.2 times the radial envelope dimension of the secondary mirror assembly 130.

[0051] In some embodiments, to facilitate the description of the principle of the secondary mirror pose adjustment mechanism 100, a spatial rectangular coordinate system is set up, as Figure 1 and Figure 6 shown. The center of the coordinate system is located at the geometric center of the upper surface 112 of the base. The z-axis is perpendicular to the upper surface 112 and points upward. The x-axis and the y-axis are coplanar with the upper surface 112. The directions of the x, y, and z axes conform to the right-hand rule of the spatial rectangular coordinate system.

[0052] In some embodiments, the principle of pose adjustment is described through kinematic analysis, as Figure 6 shown. One end of the leg 120 is connected to the base 110, and the connection point is set as ; the other end of the leg 120 is connected to the central tube 141 of the four-wing beam, and the connection point is set as . If the pose of the central tube 141 is fixed, the position of the connection point remains unchanged. Let the spatial coordinates of the connection point be .

[0053] Since the length of the leg 120 changes during the pose adjustment process, the position of the connection point changes. Let the position of the connection point before the change be , the changed position is , according to the geometric relationship, there is , where t is the position adjustment amount of the secondary mirror assembly 130 and the base 110; R is the rotation matrix calculated according to the attitude adjustment amount of the secondary mirror assembly 130 and the base 110.

[0054] Subtract the position of the connection point after change from the position of the connection point , and a vector representing the length and direction of the support leg 120 can be obtained , that is . The equation represents the relationship between the position and attitude adjustment amounts of the secondary mirror assembly 130 and the base 110 and the length of the support leg 120, indicating that the position and attitude of the secondary mirror 131 can be adjusted by adjusting the length of the support leg 120.

[0055] In terms of the degrees of freedom of the mechanism, according to the Gruebler equation for calculating the degrees of freedom of the mechanism: , when the length of the support leg 120 of the secondary mirror position and attitude adjustment mechanism 100 of the large-aperture and large-field-of-view telescope remains unchanged, , the secondary mirror position and attitude adjustment mechanism 100 can just completely restrict the six degrees of freedom of the secondary mirror 131, so that the relative position and attitude between the secondary mirror 131 and the primary mirror remain unchanged; when the length of the support leg 120 is changed by controlling the rotation of the motor 1226, , the number of degrees of freedom is just equal to the number of support legs 120, indicating that the secondary mirror position and attitude adjustment mechanism 100 can adjust the position and attitude of the secondary mirror 131. The secondary mirror 131 has 6 degrees of freedom in space, and the first support leg 121 and the second support leg 122 respectively independently control 3 spatial degrees of freedom of the secondary mirror. Since the axial direction of the first support leg 121 is perpendicular to the upper surface, the axial direction of the second support leg 122 is parallel to the upper surface 112, and the stroke of the support leg 120 is much smaller than the axial dimension of the support leg, therefore, by controlling the lengths of the 3 first support legs 121, the translation of the secondary mirror 131 along the z-axis and the rotation around the x-axis and y-axis can be independently controlled; by controlling the lengths of the 3 second support legs 122, the translation of the secondary mirror 131 along the x-axis and y-axis and the rotation around the z-axis can be independently controlled. The secondary mirror 131 has 6 degrees of freedom in space, 3 of which are controlled by the first support leg 121 and the other 3 are controlled by the second support leg 122, that is, the first support leg 121 and the second support leg 122 act independently in the adjustment of the secondary mirror position and attitude and do not affect each other.

[0056] Therefore, in terms of pose solution, compared with the existing Stewart platform and other six-legged mechanisms, the secondary mirror position and attitude adjustment mechanism 100 of the present invention has a simpler pose solution method, and the first support leg and the second support leg are independent of each other in the control of the secondary mirror position and attitude and there is no coupling.

[0057] To compare the secondary mirror pose adjustment mechanism 100 of the present invention with the existing Stewart platform, the calculation methods are briefly introduced respectively. Without loss of generality, it is assumed that the diameters of the bases of both mechanisms are , and the lengths of the legs are both 600 mm. The widely used calculation method for the Stewart platform is: establish the mathematical model of the Stewart platform, and calculate the Jacobian matrix according to the configuration parameters : The relationship between the change in leg length and the change in base pose is: , where , , where is the displacement, is the rotation angle.

[0058] The calculation method for the secondary mirror pose adjustment mechanism 100 of the present invention is: according to Figure 6 establish the mathematical model of the pose adjustment mechanism, and calculate the Jacobian matrix according to the configuration parameters: , The relationship between the change in leg length and the change in base pose is: , , where , , , .

[0059] Comparing the above two calculation methods, the Jacobian matrix of the Stewart platform is a 6×6 matrix, and the Jacobian matrices and of the secondary mirror pose adjustment mechanism 100 of the present invention are both 3×3 matrices. The present invention reduces the number of elements in the Jacobian matrix from 36 to 18, improves the calculation efficiency of the Jacobian matrix, and thus simplifies the calculation method.

[0060] The following further illustrates the benefits of the present invention through two examples: (1) When it is necessary to move the base 1 mm in the x direction, according to the above calculation method, the adjustment amount of the legs of the Stewart platform is ; the adjustment amount of the leg 120 of the secondary mirror pose adjustment mechanism 100 of the present invention is , , and only the second leg 122 needs to be adjusted.

[0061] (2)For another example, when the base rotates 0.1° about the x-axis, the adjustment amount of the leg 120 of the Stewart platform is ; the adjustment amount of the leg 120 of the secondary mirror pose adjustment mechanism 100 of the present invention is , , and only the first leg 121 needs to be adjusted.

[0062] Compared with the existing six-legged mechanisms such as the Stewart platform, the secondary mirror pose adjustment mechanism 100 of the present invention has a simpler pose calculation method. When it is necessary to adjust the secondary mirror 131 to translate in any direction, only the adjustment amounts of three legs 120 need to be calculated, and the other three legs 120 do not need to be calculated and adjusted; when it is necessary to adjust the secondary mirror to rotate in any direction, similarly, only the adjustment amounts of three legs 120 need to be calculated, and the other legs 120 do not need to be calculated and adjusted. Compared with the existing six-legged mechanisms such as the Stewart platform, the secondary mirror pose adjustment mechanism 100 of the present invention has great advantages in aspects such as the calculation method and the design of the drive control system.

[0063] The above solution of the embodiments of the present disclosure has at least the following beneficial effects compared with the related art: Compared with the existing six-legged mechanisms such as the Stewart platform, the secondary mirror pose adjustment mechanism 100 provided by the present disclosure has a new configuration, that is, a new arrangement method of the legs 120. This new configuration enables the legs 120 of the pose adjustment mechanism 100 to be conveniently and effectively connected to the central cylinder 141 of the four-wing beam 140 of the large-aperture large-field-of-view telescope, so that the pose adjustment mechanism meets the installation space requirements of the correction lens group and the detector.

[0064] The secondary mirror pose adjustment mechanism 100 of the present invention has a simpler pose calculation method. The secondary mirror 131 has 6 degrees of freedom in space. The first leg 121 and the second leg 122 respectively independently control 3 spatial degrees of freedom of the secondary mirror. The first leg and the second leg have no coupling in the secondary mirror pose adjustment. Therefore, only two 3×3 Jacobian matrices are needed to establish the mathematical model of the secondary mirror pose adjustment mechanism, reducing the number of elements in the Jacobian matrix from 36 to 18, realizing the simplification of the calculation method and improving the calculation efficiency.

[0065] Since the solution of the secondary mirror position and attitude adjustment mechanism 100 of the present invention is simpler, the drive control of the mechanism of the present invention is also simpler. When it is necessary to adjust the secondary mirror 131 to translate in any direction, only the adjustment amounts of 3 out of the 6 legs 120 need to be calculated, and the other 3 legs 120 do not need to be calculated and adjusted; when it is necessary to adjust the secondary mirror 131 to rotate in any direction, only the adjustment amounts of 3 legs 120 need to be calculated, and the other legs 120 do not need to be calculated and adjusted. Therefore, compared with the existing six-legged mechanisms such as the Stewart platform, the design and implementation of the drive control system of the secondary mirror position and attitude adjustment mechanism 100 of the present invention are also simpler.

[0066] For the specific structure, working principle, and beneficial effects of the secondary mirror position and attitude adjustment mechanism provided in the embodiments of the present disclosure, reference may be made to the secondary mirror position and attitude adjustment mechanism described in any of the foregoing embodiments, and details are not repeated herein.

[0067] Finally, it should be noted that the embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts among the embodiments may be referred to each other. For the systems or devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple, and reference may be made to the description of the method part for related parts.

[0068] The above embodiments are only used to illustrate the technical solutions of the present disclosure, rather than to limit them; although the present disclosure has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present disclosure.

Claims

1. A secondary mirror position adjustment mechanism for a large-aperture and large-field-of-view telescope, characterized in that: Used for posture adjustment of the secondary mirror, including: A base, the base is a circular flat plate, having an upper surface and a lower surface parallel to each other, the lower surface being connected to the secondary mirror through a secondary mirror chamber; A leg, one end of which is connected to the upper surface, and the other end of which is connected to the frame of the telescope, and is configured to adjust the posture of the secondary mirror, There are six legs, including three first legs and three second legs. The axial direction of the first legs is perpendicular to the upper surface, and the axial direction of the second legs is parallel to the upper surface. The first legs and the second legs act independently on the secondary mirror posture adjustment without coupling influence.

2. The secondary mirror position adjustment mechanism according to claim 1, characterized in that: The lengths of the three first legs are adjusted to control the axial translation and tilt in two directions of the secondary mirror; the lengths of the three second legs are adjusted to control the axial rotation and lateral translation in two directions of the secondary mirror.

3. The secondary mirror position adjustment mechanism according to claim 1, characterized in that: The legs include: A transmission assembly, wherein the transmission assembly is configured to provide the support leg with a degree of freedom of translation along the support leg axis and a degree of freedom of rotation about the support leg axis; Two flexible hinges are respectively arranged at two ends of the transmission assembly, and each of the flexible hinges is configured to provide two rotational degrees of freedom for the supporting leg.

4. The secondary mirror position adjustment mechanism according to claim 3, characterized in that: The transmission assembly comprises: a motor configured to drive the transmission assembly; a lead screw configured to convert the rotational motion of the motor into a linear motion, The motor and the lead screw enable the transmission assembly and the legs to be extended and shortened, and the legs can be adjusted in length under the drive of the motor.

5. The secondary mirror position adjustment mechanism according to claim 4, characterized in that: In the axial direction of the leg, the difference between the maximum length and the minimum length of the leg that can be adjusted is less than the minimum length of the leg. .

6. The secondary mirror position adjustment mechanism according to claim 1, characterized in that: The two ends of the support leg are connected to the telescope frame and the base respectively, and the base is connected to the secondary mirror through the secondary mirror chamber. Therefore, in response to the movement of the support leg, the secondary mirror changes its posture relative to the frame. Wherein, the frame comprises a central tube, the axis of the central tube coincides with the optical axis of the telescope, and one end of the support leg is connected to the central tube of the frame.

7. The secondary mirror position adjustment mechanism according to any one of claims 1 to 6, characterized in that: The relationship between the change in the length of the legs and the change in the posture of the secondary mirror is: ； ， The Jacobian matrix is and , the length change of the first leg is , the length change of the second leg is , the position change of the secondary mirror is , ,in , , Represents translation in three directions, , , Indicates rotation in 3 directions.

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