CN108445601B - Method and device for improving supporting effect of passive large-aperture primary mirror - Google Patents
Method and device for improving supporting effect of passive large-aperture primary mirror Download PDFInfo
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- CN108445601B CN108445601B CN201810134713.5A CN201810134713A CN108445601B CN 108445601 B CN108445601 B CN 108445601B CN 201810134713 A CN201810134713 A CN 201810134713A CN 108445601 B CN108445601 B CN 108445601B
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
- G02B7/18—Mountings, adjusting means, or light-tight connections, for optical elements for prisms; for mirrors
- G02B7/182—Mountings, adjusting means, or light-tight connections, for optical elements for prisms; for mirrors for mirrors
- G02B7/185—Mountings, adjusting means, or light-tight connections, for optical elements for prisms; for mirrors for mirrors with means for adjusting the shape of the mirror surface
Abstract
the invention belongs to the technical field of large-caliber astronomical telescopes, and particularly relates to a method and a device for improving the supporting effect of a passive large-caliber main mirror, wherein a preloading array is applied, and a comprehensive compensation force is obtained by calculating according to a system installation and adjustment error and a gravity surface shape error; and mapping the compensation force to each compensation mechanism unit to compensate the support stress of the main mirror support system. The preloading array is based on the microcosmic elastomer characteristics of a main mirror body material, on the basis of the continuity, uniformity and isotropy hypothesis of the mirror body material and based on the generalized Hooke's law volume strain theory, the preloading array compensation mechanism is applied to the non-optical surface of the large main mirror through a mechanical method, and the preloading array causes the change of the optical surface of the main mirror according to the calculation result on the premise of not damaging the basic form of passive support of the main mirror so as to compensate the influence of gravity deformation and the installation and adjustment stress on the surface shape precision of the main mirror.
Description
Technical Field
The invention belongs to the technical field of large-caliber astronomical telescopes, and particularly relates to a method and a device for improving the supporting effect of a passive large-caliber primary mirror.
Background
with the intensive research of astronomical physics and the development of space exploration, the traditional 1-2 level telescope system based on a passive primary mirror support system is difficult to meet the requirements because the surface shape precision of the primary mirror is difficult to break through the bottleneck of the influence of gravity deformation and adjustment errors. The newly-built foundation astronomical optical telescope is continuously built in a large-scale and ultra-large-scale direction, the caliber of a single main mirror reaches more than 8 meters, meanwhile, the active optical technology is continuously developed for overcoming the self gravity deformation and assembly errors of the large main mirror, but the system is too complex and bloated, and the manufacturing cost is high. The observed celestial body target is limited by time and space due to the limitation of a fixed station address of the large-scale equipment; space optical telescopes are available for the observation condition limitation, but due to the characteristics of high manufacturing cost, high risk and difficult maintenance (the maintenance of the Hubbo telescope forces NASA to move expensive equipment including space shuttle for many times), the large-scale space telescope establishment is difficult to realize.
The telescope system passively supported by the 1-2 meter-level primary mirror has the comprehensive advantages of mature technology, low manufacturing cost and small construction risk, so that the telescope system can be constructed on a relatively large scale, and the function of the telescope system cannot be completely replaced by an 8-meter-level foundation large telescope and a space telescope.
Disclosure of Invention
In view of the above problems, the present invention aims to provide a method and an apparatus for improving the supporting effect of a passive large-aperture primary mirror.
In order to solve the technical problems, the invention adopts a technical scheme that: the method for improving the supporting effect of the passive large-aperture primary mirror comprises the following steps:
S1, applying a preloading array on the original passive primary mirror supporting system; the preload array includes a plurality of compensation mechanism units;
S2, calculating based on the system installation and adjustment error and the gravity surface shape error to obtain a surface shape error, and resolving the surface shape error into corresponding comprehensive compensation force;
And S3, mapping the calculated compensation force to each compensation mechanism unit, and carrying out support stress compensation on the main mirror support system by each compensation mechanism unit.
Further, the compensation force calculating method of step S2 includes:
discretizing the surface of the optical reflecting surface of the primary mirror, and obtaining a stiffness matrix [ K ] of the primary mirror by using a finite element method]Establishing a unit value information matrix [ Z ] of each discrete pointi]The Zernike terms are calibrated to obtain the corresponding calibration force calibration matrix [ Fi](ii) a The inverse number of the surface shape error is brought into each discrete point to obtain a surface shape error compensation matrix [ X ]]The error matrix is decomposed into Sigma a by least squaresi[Zi]The linear combination of (1), and the resulting preload array compensation force is Σ ai[Fi]。
Furthermore, the system installation and adjustment error in the step S2 specifically refers to an actual surface shape precision error after the installation and adjustment of the original passive primary mirror support system is completed;
The calculation mode of the system installation and adjustment error compensation force is as follows: by adopting the compensation force calculation method, the opposite number of the system installation and adjustment errors is substituted to obtain a system installation and adjustment surface shape error compensation matrix, and the system installation and adjustment error compensation force is obtained.
Furthermore, the gravity surface shape error in step S2 specifically refers to a gravity surface shape error of the primary mirror at different pitch angles;
the calculation mode of the gravity surface shape error compensation force is as follows: by adopting the compensation force calculation method, the deformation of the most common pitch angle interval of the primary mirror is selected as the compensation basis, the opposite number of the gravity surface shape error of the corresponding angle is introduced, the gravity surface shape error compensation matrix is obtained, and the gravity surface shape error compensation force is obtained.
and synthesizing the system installation and adjustment error compensation force and the gravity surface shape error compensation force to obtain the comprehensive compensation force.
as an improvement, the step of "selecting the most common pitch angle interval of the primary mirror" specifically includes recording the historical use pitch angle of the primary mirror, making a pitch angle use frequency chart, and selecting the most common pitch angle interval of the primary mirror according to a preset threshold.
And as a further improvement, selecting a median corresponding to the pitch angle interval as the corresponding angle for calculating the gravity surface shape error compensation force.
A passive large-aperture primary mirror supporting effect improving device applies a preloading array on an original passive primary mirror supporting system; the preload array includes a plurality of compensation mechanism units; the compensation mechanism unit is fixedly arranged in the main mirror chamber and is arranged in parallel or in series with the passive main mirror supporting system; the compensation mechanism unit comprises a mechanical Whiffletree supporting mechanism, a lever counterweight supporting mechanism, a hydraulic Whiffletree supporting mechanism and a passive pneumatic supporting mechanism.
the invention relates to a method and a device for improving the supporting effect of a passive large-aperture primary mirror, which are characterized in that a preloading array is applied, and a comprehensive compensation force is obtained by calculating according to a system installation and adjustment error and a gravity surface shape error; and mapping the compensation force to each compensation mechanism unit to compensate the support stress of the main mirror support system. The preloading array is based on the microcosmic elastomer characteristics of a main mirror body material, on the basis of the continuity, uniformity and isotropy hypothesis of the mirror body material and based on the generalized Hooke's law volume strain theory, the preloading array compensation mechanism is applied to the non-optical surface of the large main mirror through a mechanical method, and the preloading array causes the change of the optical surface of the main mirror according to the calculation result on the premise of not damaging the basic form of passive support of the main mirror so as to compensate the influence of gravity deformation and the installation and adjustment stress on the surface shape precision of the main mirror. Each unit mechanism of the preloading array compensation mechanism outputs force, so that freedom degree coupling cannot be generated on the original passive support system, namely the kinematic balance state of the original support system cannot be influenced.
Drawings
FIG. 1 is a schematic diagram of the compensation principle of the preload array of the passive large-aperture primary mirror supporting effect enhancing apparatus according to the present invention;
Fig. 2 is a schematic diagram of a gravity deformation compensation mechanism of a method and a device for improving the supporting effect of a passive large-aperture primary mirror according to the present invention.
Detailed Description
The following describes a method and an apparatus for improving the supporting effect of a passive large-aperture primary mirror according to the present invention with reference to fig. 1-2.
Under the use state of the passive large-caliber primary mirror at different pitch angles, the surface shape of the passive large-caliber primary mirror is continuously changed under the influence of gravity, and the essential reason is that the axial support and the lateral support are different; generally, as axial support is more sufficient than lateral support in terms of available mechanism space and more reasonable support point distribution, the support effect is better than the lateral support effect, namely the main mirror optical axis points to the zenith with the best precision and points to the horizontal plane with the worst precision, and the deformation of the main mirror optical surface in the process of the optical axis pointing from the zenith to the horizontal surface shows the increasing trend from small to large (as shown in a curve 1 in fig. 2), while the frequency of the main mirror pointing to the zenith in the astronomical optical telescope is relatively low, namely the surface precision is wasted on a working mode with low use frequency in the design concept of the corresponding passive support system in the prior art; meanwhile, the performance of the whole main mirror supporting system is measured by a barrel effect, namely the worst surface shape precision in different pitch angle states is used as the standard. When the optical axis of the primary mirror points to the horizontal direction, the Poisson effect generated by the primary mirror under the action of gravity is most obvious, the deformation generated by the optical surface of the primary mirror is the largest, and the influence on the imaging effect of the primary optical system is the largest; the mechanism of applying the preloading array to compensate the gravity to the surface shape precision of the main mirror support system is that the reasonable preloading array is applied, the surface shape precision of the main mirror when the optical axis with lower frequency in the running working state points to the zenith is sacrificed, so that the surface shape precision of the main mirror in the pitch angle section with higher frequency in the working state is improved, the problem of surface shape precision reduction caused by the influence of self gravity when the main mirror is laterally supported to play a leading role (namely the optical axis points to be close to the horizontal state and reaches the horizontal state) is compensated, and further the comprehensive performance of the whole pitch angle working state range of the main mirror support system under the action of gravity is improved, as shown in a curve 2 in fig.
based on the principle, the invention provides a method for improving the supporting effect of a passive large-aperture primary mirror, which comprises the following steps:
S1, applying a preloading array on the original passive primary mirror supporting system; the preload array includes a plurality of compensation mechanism units;
S2, calculating based on the system installation and adjustment error and the gravity surface shape error to obtain a surface shape error, and resolving the surface shape error into corresponding comprehensive compensation force;
And S3, mapping the calculated compensation force to each compensation mechanism unit, and carrying out support stress compensation on the main mirror support system by each compensation mechanism unit.
For the adjusting stress, the preloading array compensation method of the invention can basically eliminate the main mirror surface shape error caused by the adjusting stress as a constant system error through compensation. The output force of each unit mechanism of the preloading array compensation mechanism is constant and does not change along with the state change of the main mirror.
Further, the compensation force calculating method of step S2 includes:
discretizing the surface of the optical reflecting surface of the primary mirror, and obtaining a stiffness matrix [ K ] of the primary mirror by using a finite element method]Establishing a unit value information matrix [ Z ] of each discrete pointi]The Zernike terms are calibrated to obtain the corresponding calibration force calibration matrix [ Fi](ii) a The inverse number of the surface shape error is brought into each discrete point to obtain a surface shape error compensation matrix [ X ]]The error matrix is decomposed into Sigma a by least squaresi[Zi]The linear combination of (1), and the resulting preload array compensation force is Σ ai[Fi]。
furthermore, the system installation and adjustment error in the step S2 specifically refers to an actual surface shape precision error after the installation and adjustment of the original passive primary mirror support system is completed;
the calculation mode of the system installation and adjustment error compensation force is as follows: by adopting the compensation force calculation method, the opposite number of the system installation and adjustment errors is substituted to obtain a system installation and adjustment surface shape error compensation matrix, and the system installation and adjustment error compensation force is obtained.
Furthermore, the gravity surface shape error in step S2 specifically refers to a gravity surface shape error of the primary mirror at different pitch angles;
The calculation mode of the gravity surface shape error compensation force is as follows: by adopting the compensation force calculation method, the deformation of the most common pitch angle interval of the primary mirror is selected as the compensation basis, the opposite number of the gravity surface shape error of the corresponding angle is introduced, the gravity surface shape error compensation matrix is obtained, and the gravity surface shape error compensation force is obtained.
And synthesizing the system installation and adjustment error compensation force and the gravity surface shape error compensation force to obtain the comprehensive compensation force.
As an improvement, the step of "selecting the most common pitch angle interval of the primary mirror" specifically includes recording the historical use pitch angle of the primary mirror, making a pitch angle use frequency chart, and selecting the most common pitch angle interval of the primary mirror according to a preset threshold.
And as a further improvement, selecting a median corresponding to the pitch angle interval as the corresponding angle for calculating the gravity surface shape error compensation force.
as shown in fig. 1, the present invention further provides a device for improving the supporting effect of a passive large-aperture primary mirror, wherein a preload array is applied to the original passive primary mirror supporting system; the preload array includes a plurality of compensation mechanism units; the compensation mechanism unit is fixedly arranged in the main mirror chamber and is arranged in parallel or in series with the passive main mirror supporting system; the compensation mechanism unit comprises a mechanical Whiffletree supporting mechanism, a lever counterweight supporting mechanism, a hydraulic Whiffletree supporting mechanism and a passive pneumatic supporting mechanism.
The invention relates to a method and a device for improving the supporting effect of a passive large-aperture primary mirror, which are characterized in that a preloading array is applied, and a comprehensive compensation force is obtained by calculating according to a system installation and adjustment error and a gravity surface shape error; and mapping the compensation force to each compensation mechanism unit to compensate the support stress of the main mirror support system. The preloading array is based on the microcosmic elastomer characteristics of a main mirror body material, on the basis of the continuity, uniformity and isotropy hypothesis of the mirror body material and based on the generalized Hooke's law volume strain theory, the preloading array compensation mechanism is applied to the non-optical surface of the large main mirror through a mechanical method, and the preloading array causes the change of the optical surface of the main mirror according to the calculation result on the premise of not damaging the basic form of passive support of the main mirror so as to compensate the influence of gravity deformation and the installation and adjustment stress on the surface shape precision of the main mirror. Each unit mechanism of the preloading array compensation mechanism outputs force, so that freedom degree coupling cannot be generated on the original passive support system, namely the kinematic balance state of the original support system cannot be influenced.
The beneficial effects of the invention at least comprise the following aspects:
(1) based on the traditional 1-2 meter level primary mirror passive support system, the method has clear thought and simple structure, can provide a compensation thought reference for the design scheme of new equipment, and can also provide a simple and feasible compensation improvement method for improving the primary mirror support effect for the original equipment.
(2) the method for improving the supporting effect of the passive large-aperture primary mirror adopts a compensation method of output force, so that the degree of freedom of the original supporting system is not coupled, the kinematic balance state of the original supporting system is not damaged, and the thermal decoupling capacity and the supporting capacity of the original supporting system are not influenced.
(3) The compensation force output by the preloading array compensation mechanism is constant, a manual adjusting mechanism can be adopted, a complex force actuator mechanism similar to active optics is avoided, the system is simple in structure, stable and reliable, the original support rigidity of the support system is not influenced, and the preloading array compensation method is suitable for being used in a fixed astronomical station and is particularly suitable for being used in a movable carrier astronomical station.
The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes performed by the present specification and drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.
Claims (7)
1. A method for improving the supporting effect of a passive large-aperture primary mirror is characterized by comprising the following steps:
S1, applying a preloading array on the original passive primary mirror supporting system; the preload array includes a plurality of compensation mechanism units;
s2, calculating based on the system installation and adjustment error and the gravity surface shape error to obtain a surface shape error, and resolving the surface shape error into corresponding comprehensive compensation force;
S3, mapping the calculated compensation force to each compensation mechanism unit, and carrying out support stress compensation on the main mirror support system by each compensation mechanism unit;
The compensation force calculation method of step S2 includes:
Discretizing the surface of the optical reflecting surface of the primary mirror, and obtaining a stiffness matrix [ K ] of the primary mirror by using a finite element method]establishing a unit value information matrix [ Z ] of each discrete pointi]The Zernike terms are calibrated to obtain the corresponding calibration force calibration matrix [ Fi](ii) a The inverse number of the surface shape error is brought into each discrete point to obtain a surface shape error compensation matrix [ X ]]the error matrix is decomposed into Sigma a by least squaresi[Zi]By linear combination of the two, the preload array compensation force is found to be ∑ ai[Fi]。
2. The method according to claim 1, wherein the system adjustment error in step S2 is specifically an actual surface shape accuracy error after the adjustment of the original passive primary mirror support system is completed;
The calculation mode of the system installation and adjustment error compensation force is as follows: by adopting the compensation force calculation method, the opposite number of the system installation and adjustment errors is substituted to obtain a system installation and adjustment surface shape error compensation matrix, and the system installation and adjustment error compensation force is obtained.
3. The method according to claim 2, wherein the gravity surface shape error in step S2 is specifically a gravity surface shape error of the primary mirror at different pitch angles;
the calculation mode of the gravity surface shape error compensation force is as follows: by adopting the compensation force calculation method, the deformation of the most common pitch angle interval of the primary mirror is selected as the compensation basis, the opposite number of the gravity surface shape error of the corresponding angle is introduced, the gravity surface shape error compensation matrix is obtained, and the gravity surface shape error compensation force is obtained.
4. The method according to claim 3, wherein the system setup error compensation force and the gravity surface shape error compensation force are combined to obtain the comprehensive compensation force.
5. the method according to claim 3, wherein the step of selecting the most common pitch angle interval of the primary mirror includes recording historical pitch angles of the primary mirror, creating a pitch angle usage frequency map, and selecting the most common pitch angle interval of the primary mirror according to a predetermined threshold.
6. The method according to claim 5, wherein a median corresponding to the pitch angle interval is selected as the corresponding angle for calculating the gravity surface error compensation force.
7. A passive large-aperture primary mirror supporting effect improving apparatus using the passive large-aperture primary mirror supporting effect improving method according to any one of claims 1 to 6, wherein a preload array is applied to an original passive primary mirror supporting system; the preload array includes a plurality of compensation mechanism units; the compensation mechanism unit is fixedly arranged in the main mirror chamber and is arranged in parallel or in series with the passive main mirror supporting system; the compensation mechanism unit comprises a mechanical Whiffletree supporting mechanism, a lever counterweight supporting mechanism, a hydraulic Whiffletree supporting mechanism and a passive pneumatic supporting mechanism.
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| CN109932804B (en) * | 2019-03-04 | 2021-06-01 | 杭州电子科技大学 | Flexible memory alloy supporting device of small-caliber light reflector |
| CN111352208B (en) * | 2020-04-07 | 2021-06-15 | 中国科学院长春光学精密机械与物理研究所 | Machining, assembling and adjusting device and method for large-diameter reflector |
| CN112731619A (en) * | 2020-12-30 | 2021-04-30 | 中国工程物理研究院激光聚变研究中心 | Surface shape compensation system |
| CN113253415B (en) * | 2021-06-01 | 2022-02-11 | 中国科学院长春光学精密机械与物理研究所 | Main mirror lateral support structure and assembling and adjusting method |
| CN114002805B (en) * | 2021-11-02 | 2023-11-07 | 中国工程物理研究院激光聚变研究中心 | Optical element gravity deformation inhibition method |
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| FR2875607B1 (en) * | 2004-09-20 | 2006-11-24 | Cit Alcatel | LOCAL DEFORMATION MIRROR THROUGH THICKNESS VARIATION OF AN ELECTRICALLY CONTROLLED ELECTRO-ACTIVE MATERIAL |
| DE102008014615A1 (en) * | 2008-03-17 | 2009-10-01 | Friedrich-Schiller-Universität Jena | Adaptive deformable mirror to compensate for wavefront errors |
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