Radiation Resistant Capacitive Edge Sensors for Segmented Space Telescopes

Future segmented space telescope needs to work at larger aperture and shorter wavelength, and the co-phasing state will rapidly deteriorate due to environmental interference. To avoid co-phasing drift during the observation period, it is necessary to use edge sensors for real-time correction of phasing error. The unshielded edge sensors installed on the primary mirrors are exposed to the outermost place of the satellite. During working periods of more than ten years, the impact of irradiation effects on sensors is particularly obvious. We have developed a radiation resistant capacitive edge sensor with foundry-based components. After a total ionizing dose (TID) test of $1.6\times 10^{{9}}$ rad (Si), analyses were conducted on the appearance, roughness, surface composition, detection range, and accuracy. The results show that the relative error of the irradiated sensor within the displacement range of 6 nm– $20 \mu \text{m}$ is between 0.85% and 7.65%, indicating that the irradiated sensor still meets the requirements for detection range and accuracy.