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The physical investigation of surfaces and their properties crucially depends on their quality. Such investigations are commonly performed in an ultra-high vacuum environment. Thereby, the transfer of samples among different setups and under ambient conditions is desirable. The usage of a capping layer for the protection of surfaces against contaminations during long-time storage and transfer, and the subsequent temperature-controlled decapping is an established approach. However, a residual-free removal of the capping layer may present a challenge. Here, we systematically investigate the decapping process of a tellurium protected topological insulator Bi2Te3. We give evidence for the material segregation from the contaminated capping layer surface to the substrates. Therefore, a simple, temperature controlled decapping is not sufficient. We demonstrate that near perfect surfaces can be reliably obtained even after long-time storage through a combination of an initial argon ion sputtering process and a following heating for decapping. This approach is suitable for dedicated analysis systems as well as for industrial applications, large throughput of samples of arbitrary shapes, and is easily implemented in existing setups.

Magnetic couplings possess no mechanical contact and permit higher assembly tolerance for transmitting torque from a primary driver to a follower by magnetic force. This paper investigates the eVects of misalignment on the transmission characteristics of synchronous magnetic couplings. The misalignment can be categorized into the following three types: transverse, angular and a combination of these two misalignments. Without loss of generality, an axial synchronous magnetic coupling is adopted in the present because of its simplicity both in design and fabrication. The phenomenon and in¯uence of shafts with assembly misalignment are described ®rst. The mathematical model for the magnetic coupling with misalignment is then constructed for the purpose of deriving the equations governing the torque transmission and force interaction characteristics. The method of equivalent magnetic charge is employed to calculate the variations in the transmitted torque owing to each type of misalignment. Finally, a test apparatus is constructed for verifying the static and dynamic characteristics of the designed coupling under various misalignment conditions. Good agreement between numerical simulation and experimental results is obtained.

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We show experimentally and theoretically that the spectral profile of the seed pulse of an Yb-doped fibre-based chirped pulse amplifier (CPA) plays a dominant role for achieving an ultrashort compressed pulse. The picosecond seed pulse from an all-normal dispersion Yb-doped fibre laser can be compressed to 350 fs with a peak power of 25 MW. Better compressed pulse quality and a shorter pulse was achieved by the spectrally shaped CPA system as opposed to the system without spectral shaping.