Transient liquid phase bonding technique for ultrahigh-vacuum compatible bimorph mirrors used in soft x-ray beamlines

Abstract

Bimorph mirrors place stringent requirements on the welding technology of silicon substrates and piezoelectric ceramics to ensure their ultrahigh-vacuum compatibility. Conventional welding techniques usually require high temperature and pressure, which have a high impact on the welding substrate, while the use of organic adhesives for bonding does not guarantee their stability in ultrahigh vacuum. Here, the transient liquid phase bonding technology based on an Au–In metal system was studied to meet the requirement for ultrahigh-vacuum application. The microstructure, chemical composition, and related mechanical properties of the bonding at different welding conditions were investigated. Meanwhile, the piezo ceramics and the bond were baked at 150 °C to test the stability. The results show that a stable bonding was achieved between centimeter-scaled single crystal silicon and lead zirconate titanate ceramics at 200 °C temperature and 2.5 MPa pressure, and the piezo ceramics and the bond are not damaged by baking to 150 °C for 48 h.

An active piezoelectric plane X-ray focusing mirror with a linearly changing thickness

“…Subsequently, they also developed a bimorph mirror with multi-segmented electrodes to compensate for the low-frequency figure errors of a long mirror (Signorato et al, 1998). Until now, with the development of X-ray focusing and the commercialization of SESO and JTEC, bimorph mirrors have been widely applied at many synchrotron radiation and free-electron laser (FEL) sources around the world, including SPring-8 (Signorato et al, 2001), DLS (Nistea et al, 2019;Alcock et al, 2023), APS (Shi et al, 2022), ALS (Sanchez del Rio et al, 2020), NSRL (Yuan et al, 2023) and EU-FEL (Vannoni et al, 2016). The high-precision manipulation ability enables the focusing element to obtain a high-precision surface figure with a larger numerical aperture, even without improving the polishing processing.…”