Multilayer Reflectors for Improving the Primary Beam Intensity: Reflectivity Measurements on Coated Glasses

Abstract
Periodic muitilayers are commonly used in various X-ray applications as primary beam conditioners. The newly designed secailed Goebel-mirror is a special type of multilayer which is used to convert a diverging incoming beam into e.g. parallel one. The Goebel-mirror is bent parabolicaily or ellipticaily with the X-ray source lying in the focus of the parabola. The period of the multilayer is matched laterally to the incident angle so that the fkst order Bragg-condition is fulfilled for a specific wavelength band. About 75% of the incoming Kα radiation is reflected whereas Kβ radiation is suppressed totally. In the case of the X-ray reflectometry technique the properties of a parabollically bent Goebel-mirrror can be used to get an intensity gain up to about two orders of magnitude. This intensity gain can either be used to increase the measured angular range or to reduce the overall measurement time drastically. Investigations on thin film glass coatings will be presented which show the advantages which can be achieved by using the Goebel-mirror technique.