Proc. SPIE. 9685, 8th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Design, Manufacturing, and Testing of Micro- and Nano-Optical Devices and Systems; and Smart Structures and Materials
With the gradual development of micro-satellite technology and the extension of application field of earth observation technology, researchers show more concern and attention on how to obtain high-resolution images with microsatellite platform equipped with space telescope. Such microsatellites require the space telescopes with small volume, low mass, and low cost. Deployable telescope is a good choice to meet these requirements, and it has the same capabilities as the traditional space telescope. We investigate a space telescope with smart self-deployable structure. The telescope is folded before launch, the distance between primary mirror and secondary mirror becomes short and the volume of the telescope becomes small, and the telescope extends to its working configuration after it is in orbit. The deployable structure is one of the key techniques of deployable space telescope, and this paper focuses on the design of a self-deployable structure of the secondary mirror. There are mainly three parts in this paper. Firstly, the optics of the telescope is presented, and a Ritchey-Chretien (RC) type optical system is designed. Secondly, the self-deployable structure is designed and the finite element method (FEM) is used to analyze dynamics of the extended telescope. Thirdly, an adjusting mechanism with six degrees of freedom to correct the misalignment of the secondary mirror is investigated, and the kinematics is discussed.
Benefiting from low cost, light weight and reduced volume in launch, deployable optical telescopes will be extensively applied in microsatellites. As a result of manufactured tolerance and external disturbance, the secondary mirror can’t arrive at designed position precisely after a deployable telescope is unfolded. We investigate an adjustment system with six degrees of freedom based on hexapod structure to solve this problem. There are mainly four parts in this paper. Firstly, the adjustment methods of deployable telescopes for microsatellites are introduced. Generally several kinds of optical components can be adjusted to align a deployed telescope: primary mirror, tip/tilt mirror and secondary mirror. Due to its high sensitivity and convenience, the secondary mirror is chosen to collimate the optical system of the telescope. Secondly, an adjustment system with hexapod structure is designed for a secondary mirror with 85 mm diameter. After comparing the characteristics of step motors, piezo actuators and voice coil motors (VCMs), VCMs are selected as the linear actuators. By using optical gratings as displacement sensors in the system, we can make closed-loop control come true. The hexapod structure mainly consists of 6 VCMs, 6 optical gratings and 6 oblique legs with flexible hinges. The secondary mirror adjustment system is 83 mm in diameter and 55 mm high. It has tip/tilt rotational ranges of ±2.205° with resolution of better than ±0.007°, and translational ranges of ±1.545 mm with resolution of better than ±0.966 μm. Thirdly, the maximum stress and the maximum deformation in the adjustment system are computed with finite element method. At last, the kinematics problems of the adjustment system are discussed.
Microsatellites will be widely applied as an earth-observing platform in coming future for their low costs. Such satellite
missions require optical payloads with low cost, low mass and small volume. In order to meet these requirements, one
way is to develop deployable telescopes. They not only maintain the capabilities of the traditional non-deployable
telescopes, but also have compacter launch volume and lighter weight. We investigate a telescope with precise
deployable structure based on coilable tensegrity. Before launch, the secondary mirror support structure is coiled, and
when the satellite is in orbit, the secondary mirror is deployed with the elastic strain energy from the coiled longerons.
There are mainly three parts in this paper. Firstly, the telescope optics is presented. A Ritchey-Chretien (RC) type optical
system with 150mm aperture is designed. Secondly, the deployable telescope structure is designed for the RC system.
The deployable structure mainly consists of coilable longerons, batten rings, and diagonal stringers. The finite element
method (FEM) is used to analyze the dynamics of the unfolded telescope structure. Thirdly, the adjusting mechanism for
secondary mirror is discussed. Piezoelectric actuators can be used to achieve remote alignment to improve the
performance of the imaging system.