Monitoring of Dimensional Stability of CFRP Mirrors for Space Telescopes by Using Embedded FBG Sensors

Space telescopes for Earth observation will require data of increasingly high quality. The resolution of Earth observation has reached several tens of cm. Because resolution is proportional to the diameter of mirrors, larger and larger mirrors are required. Space astronomy telescopes also require increasingly high resolution and large mirrors. The James Webb Space Telescope has been already advanced to the developing phases and the deployable main mirror of 6 m in diameter is being manufactured [1]. Although the structure of telescopes is based mainly on system design, the selection of material is a key issue on points of high dimensional accuracy and stability, especially with regard to weight. Carbon fiber-reinforced composite (CFRP) has a high stiffness-to-weight ratio and can be designed to have nearly zero thermal expansion [2]. That makes CFRP one of the most promising materials for optical mirrors of space telescopes.