| 空间光学遥感器精密次镜调整机构设计及试验 |
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| 引用本文： | 武永见,杨大伟,孙欣,刘涌,胡永力.空间光学遥感器精密次镜调整机构设计及试验[J].红外与激光工程,2023,52(4):20220635-1-20220635-7. |
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| 作者姓名： | 武永见 杨大伟 孙欣 刘涌 胡永力 |
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| 作者单位： | 北京空间机电研究所 先进光学遥感技术北京市重点实验室，北京 100094 |
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| 摘 要： | 随着空间光学遥感器地面分辨率逐步提高，长焦距、大口径相机成为重点研究方向。为了克服重力变化、复合材料变形等因素带来的天地不一致性的问题，次镜调整成为校正光学遥感器离焦和主次镜相对位置变化的关键技术之一。将次镜柔性支撑、精密直线驱动与柔性铰链传动技术相结合，设计了一套高精度次镜调整机构。首先介绍了该套机构的光机构成、工作原理及传动链路，然后对超轻次镜、高精度直线致动、高精度调焦传动等设计分别进行了阐述，最后介绍了力学环境试验后的调整精度测试情况。试验结果表明，该套精密调整机构实测调整行程大于±120μm，轴向调整步距精度0.18μm (3σ值)，调整行程内次镜的最大平移误差为1.30μm，最大倾斜误差为1.93″，具有调整范围宽、调整精度高的特点，满足空间光学遥感器精密次镜调整的要求，已成功在轨应用于北京三号B卫星0.5 m级高分辨率空间相机。
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| 关 键 词： | 大口径 空间光学 调整机构 遥感器 次镜 柔性支撑 |
| 收稿时间： | 2022-09-07 |
Design and test of precision secondary mirror adjustment mechanism for space optical remote sensor |
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| Affiliation: | Beijing Key Laboratory of Advanced Optical Remote Sensing Technology, Beijing Institute of Mechanics & Electricity, Beijing 100094, China |
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| Abstract: | Objective Vertical assembly and adjustment is one of the key technologies of long focal length and large aperture space camera. In order to overcome the inconsistency between the on-orbit and the ground caused by gravity change, material deformation and other factors, the secondary mirror adjustment has become one of the key technologies to correct the defocus of the optical remote sensor and the relative position change of the primary mirror and the secondary mirror. Precision secondary mirror adjustment technology has been widely used in high-resolution space optical remote sensors. For example, Stewart platform 6-DOF parallel mechanism, which has been successfully applied in Hubble telescope and reconnaissance camera, has the advantages of high accuracy, high bearing capacity and high rigidity, and has the ability to precisely adjust the secondary mirror components in the optical system. Many theoretical analysis and engineering research have been done on the 6-DOF adjustment mechanism in China, but the 6-DOF adjustment mechanism also has the disadvantages of complex structure and control system, high cost and relatively large weight. Therefore, it is necessary to develop a single-degree-of-freedom secondary mirror adjustment mechanism with high accuracy, high integration and high reliability to solve the inconsistency between heaven and earth faced by the current high-resolution space optical remote sensor. Methods In order to meet the secondary mirror adjustment requirements of a high-resolution camera, a high-precision and high-stability secondary mirror adjustment mechanism combining precision linear transmission, flexible transmission and flexible support technology is built in this paper (Fig.1). The linear transmission device （Fig.4） adopts the redundancy design of one main and one standby, and has precision position telemetry capability. The flexible transmission hinge with transmission ratio of 10∶1 is used for motion transmission. Compared with the traditional gear reducer, it has the advantages of small impact, no wear, stable transmission, and high reliability. At the same time, the flexible hinge has the advantages of high-precision transmission in the range of small displacement. The secondary mirror uses bipod flexible support to design unloading force thermal deformation, and ensures its flexibility along the optical axis direction (focusing direction) through three pairs of 120° flexible guide hinges. Results and Discussions This set of precision adjustment mechanism has carried out adjustment precision test after completing the mechanical environment assessment. The test is carried out according to 0.088° rotation of step motor (corresponding theoretical step distance of secondary mirror 8.858 μm). The initial position of the secondary mirror is zero. The secondary mirror is drived to complete the whole adjustment cycle of "zero position→positive limit position→zero position→negative limit position→zero position". The adjustment accuracy test results after the mechanical environment assessment of the optical and mechanical products of the adjustment mechanism show that the mechanism has the ability to achieve high-precision adjustment in a large range (Fig.8-11), and meets the requirements of the on-orbit application of space optical remote sensor. Conclusions In this paper, a set of high-precision secondary mirror adjustment mechanism is designed by combining the flexible support, precision linear drive and flexible hinge transmission technology of the second mirror. This paper first introduces the optical and mechanical structure, working principle and transmission link of the mechanism, then describes the design of ultra-light secondary mirror assembly, high-precision linear actuation and high-precision focusing transmission, and finally introduces the adjustment accuracy test after the vibration test. The test results show that the measured adjustment stroke of the set of precision adjustment mechanism is more than ±120 μm, the axial adjustment step precision is 0.18 μm, the maximum translation error of the secondary mirror within the adjustment stroke is 1.3 μm, and the maximum tilt error is 1.9″. It has the characteristics of wide adjustment range and high adjustment accuracy, and meets the requirements of the precision secondary mirror adjustment of the space optical remote sensor. |
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