高分辨率空间相机受发射段恶劣的力学环境以及空间复杂的温度环境影响, 光学系统会产生微小的离焦量。为保证相机成像质量, 本文设计了一种由蜗轮蜗杆与凸轮滑块机构组成的新型高精度调焦机构来修正离焦量。该设计通过蜗轮蜗杆实现第一级减速, 并且使驱动器旋转轴与光轴正交, 使机构更紧凑。通过凸轮滑块机构进一步进行减速, 同时将旋转运动转化为直线运动, 并通过直线导轨保证滑块的直线运动精度。该机构体积小、精度高, 并且能实现断电自锁。机构运动副上溅射固体润滑涂层, 防止发生真空冷焊。结合机构自身的特点, 分析了机构调焦的分辨率与误差。对该机构开展了力学与热真空循环试验, 试验前后对机构的精度指标进行了对比测试。试验与测试结果表明: 该机构环境试验后性能参数正常, 其调焦位移误差优于5.8 μm, 线性度优于0.3%, 偏摆角优于14″。在热光试验中通过调整焦面, 成像质量有显著的提升。该调焦机构能够满足光学系统的精度与环境适应性要求。

A small amount of defocus is generated in the optical system of high-resolution space cameras owing to the harsh mechanical environment of the launch section and the complex temperature environment of the orbit. To ensure the image quality of the camera and correct the defocus, a new high-precision focusing mechanism, consisting of a worm gear and a cam slider, was designed. The first stage of deceleration was achieved through the worm gear in this design. The drive's rotary axis was orthogonal to the optical axis, hence, the mechanism was more compact. Further deceleration was performed by the cam slider mechanism, and the rotary motion was converted into a linear motion; the linear motion accuracy of the slider was provided by a linear guide. The mechanism is small, has high precision, and is capable of self-locking in the case of a power failure. The mechanism motion pair was coated with a solid lubricant to prevent vacuum cold welding. According to the characteristics of the mechanism, the resolution and error of the focusing mechanism were analyzed. Mechanical and thermal vacuum cycle tests were carried out on the mechanism. Various precision indicators of the mechanism were compared and tested before and after the experiments. The results show that the mechanism performance is normal after the environmental test, the focus shift error is better than 5.8 μm, the linearity is better than 0.3%, and the yaw angle is better than 14″. In the thermo-optical test, the focal plane was adjusted by the focusing mechanism, and the image quality was significantly improved. The focusing mechanism can meet the accuracy and environmental adaptability requirements of the optical system.