Design and experimental research of a new type focus mechanism used in space-based telescope

The position of focal plane will be changed because of temperature fluctuation and vacuum environment. In order to make the telescope work well, a focusing mechanism is needed. To majority of large space-based telescopes, the general way to do this would be to use a reflector, which was located in the backfocal distance. One of typical schemes of this mechanism was introduced, however, because of the big axial size, the mechanism can´t be used when the size of the enclosure was limited. A new type of focusing mechanism was introduced, which has such advantages of small size, high accuracy and low mass. The design and test methods had been discussed. According to the results, the repeatability positioning accuracy is 0.0025mm; positioning accuracy of the mechanism is 0.008mm. The performance satisfies the need of precision, and the scheme design is reasonable and practicable.