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[en] Si/Gd multilayers designed as narrowband reflective coatings near 63 nm were developed. The highest peak reflectance of 26.2% at a 5 incident angle was obtained at 62 nm, and the spectral bandwidth was 7.3 nm FWHM. The fits for x-ray and extreme ultraviolet reflectance data of Si/Gd multilayers indicate the possibility of silicide formation at the Si-Gd interfaces. B4C, W, and SiN were deposited as interface barrier layers to improve the reflectance of Si/Gd multilayers. More than an 8% increase in reflectance was observed from the interface-engineered Si/W/Gd and Si/B4C/Gd multilayers.
[en] A correlation between laser-induced damage and the height of a coating defect was found from an examination of HfO2/SiO2 mirrors made by three different coating vendors. The nodular defects in these reactive e-beam deposited mirrors were studied using the combination of SEM, optical microscopy, FIB and AFM techniques. Each vendor had small defects in common, but characteristically different large defects. Also the majority of seeds that caused the defects were made of hafnia, not silica. The apparent mechanical stability of the defects within the coating plays a major role in the laser resistance (1064 nm and l0ns) of a high damage threshold coating
[en] In this work Co thin films were deposited using MBE at room temperature and transported to MARIA reflectometer for PNR measurements without breaking vacuum with the help of UHV portable transfer chamber. Data evaluation of the PNR curves shows that surface of Co film is free from contamination. After the PNR measurements in UHV conditions, the sample was exposed to air and ex-situ PNR measurement was performed on the same sample. The comparison of quasi in-situ and ex-situ PNR measurements proves that our portable transfer chamber can be successfully used for PNR measurements of air sensitive thin films in UHV conditions. Booking of the access to the MBE system as well as the transport chamber is possible via the MLZ user office system in combination with an application for a beam time at neutron instruments like MARIA
[en] The properties of axisymmetric and cylindrical optical concentrations in the wavelength region where all the substances possess low reflectivity are considered. The losses related to radiation leaving the system through side faces and reflective walls are found, and the ultimate efficiency of the concentrator is determined. On the basis of available data on optical constants the dependence of the efficiency on the choice of the reflective coating material is analyzed. The role of the roughness of the reflective surface is discussed and the principal requirements on the accuracy of concentrator fabrication are stated
[en] Laser induced damage in optical coatings is a complicated problem, which is attributed to a lot of factors including environment parameters, laser parameters and thin film production parameters. Among the three factors, production parameters interest us most. We produce a series of samples with different roughness levels of the substrates, thin film material and vacuum environment within the chamber, etc. Using 1.06 μm Nd-YAG laser as our test laser, we make 1-on-1 laser damage test to these samples. Some interesting phenomena are found. We calculate the laser induced local heating within the thin film multilayers, and make analysis to the experimental phenomena. Conclusions are given