An Er‐doped LaP₅O₁₄ ferroelastic crystal has been studied by synchrotron radiation white beam x‐ray topography. A set of normal ferroelastic domains is revealed in topographs by the intense contrast at the domain walls and the temperature dependence of the wall contrast is shown to be in good agreement with that expected from the structural consideration. In addition to growth bands and growth sector boundaries, a type of abnormal boundary is observed, and the contrast varies with the occurrence of phase transitions. A detailed discussion on experimental results is given in terms of structural and symmetry analyses.

Future segmented space telescope needs to work at larger aperture and shorter wavelength, 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 test of 1.6×10₉ 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 6nm to 20μm is between 0.85% and 7.65%, indicating that the irradiated sensor still meets the requirements for detection range and accuracy.

In optical systems, diffraction limits significantly impact spot simulations. This study addresses this problem by applying the Fourier transform to calculate spots in imaging systems. Typically, a 1 mm image plane suffices; however, mosaic aperture telescopes with notable wavefront discontinuities require an approximately 10 mm simulation image plane. This necessitates high sampling rates for pupils, posing challenges for conventional methods. Our model overcomes this challenge by leveraging an interpolation technique to align multiwavelength spots on a uniform image plane grid, thus effectively analyzing spot translation and spreading in imaging systems with diffraction limits.

The structural deformations induced by rocket launch vibrations, on-orbit thermal gradients, and gravitation fluctuations can lead to significant deployment errors for large-aperture, segmented space telescopes. As the size and number of segments increase in future telescopes, the optical-based methods for detecting deployment errors suffer from the range limitations of the millimeter scale and time-consuming processes of the month scale. To address this, we propose a new method for rapid-deployment error detection based on long-range, high-precision capacitive edge sensors. These sensors feature a measurement range of ±13 mm, with a precision better than 7.3 nm, enabling efficient and simultaneous error detection across all segments. This approach significantly reduces the time and steps required compared to traditional optical methods. Through experimental validation, the designed system demonstrated the ability to detect and correct large deployment errors and maintain co-phasing precision, meeting the stringent requirements for future space telescopes. The proposed sensor system enhances deployment efficiency, offering a viable solution for the next generation of segmented space telescopes.