Fabrication And Characterization Of Soft X-Ray Beamsplitters

Abstract

ABSTRACT : Conception, fabrication and characterization of a beamsplitter working in the soft X-ray range at oblique incidence are presented. A large area beamsplitter is fabricated using microfabrication technology and an inorganic film carrier. Reflectivity and transmission results are compared with calculations. 1. INTRODUCTION The use of layered synthetic microstructures ( LSM ) enables the design of new optical elements working in the soft X-ray range, such as beamsplitters which possess both a large transmission and reflectivity coefficient. These qualities permit to extend the use of the semitransparent plates from the visible range into a higher energy range. Applications in X-ray laser cavity, plasma diagnostics and synchrotron radiation beamlines could, in particular, be considered.The first experimental results with semitransparent multilayer reflectors were obtained with a Mo / Si multilayer used in a soft X-ray laser cavity at normal incidence at 130 and 208 A at the Lawrence Livermore National Laboratory by A.M. Hawryluk et al.1' 2, 3. More recently a C / W beamsplitter was tested at 12.4 A at oblique incidence on the LURE 4. Those results showed good agreement between the calculated and experimental reflectivity and transmission values, but the bad state of the surface of the multilayer resulted in an important lack of intensity of both the reflected and transmitted beam. A new method was therefore developed in order to control better the flatness of the multilayer reflector. The outlines of the fabrication process of a large area beamsplitter and the preliminary tests are reported here.