title: Micro-focusing of attosecond pulses by grazing-incidence toroidal mirrors.
abstract: The design of optical systems for micro-focusing of extreme-ultraviolet (XUV) attosecond pulses through grazing-incidence toroidal mirrors is presented. Aim of the proposed configuration is to provide a micro-focused image through a high demagnification of the XUV source with the following characteristics: i) almost negligible aberrations; ii) long exit arm to easily accommodate at the output the experimental setups required for the applications of the focused attosecond pulses; iii) possibility to have an intermediate region where the XUV beam is collimated, in order to insert a plane split-mirror for the generation of two XUV pulse replicas to be used in a XUV-pump/XUV-probe setup. We present the analytical and numerical study of two optical configurations characterized by two sections based on the use of toroidal mirrors. The first section provides a demagnified image of the source in an intermediate focus that is free from defocusing but has a large coma aberration. The second section consists of a relay mirror that is mounted in Z-shaped geometry with respect to the previous one, in order to give a stigmatic image with a coma that is opposite to that provided by the first section. An example is provided to demonstrate the capability to achieve spot sizes in the 5-15 μm range with a demagnification higher than 10 in a compact envelope.
authors.affiliation: National Council for Research of Italy, Institute of Photonics and Nanotechnologies, Padova, Italy. poletto@dei.unipd.it
authors.forename: L
authors.initials: L
authors.lastname: Poletto
authors.forename: F
authors.initials: F
authors.lastname: Frassetto
authors.forename: F
authors.initials: F
authors.lastname: Calegari
authors.forename: S
authors.initials: S
authors.lastname: Anumula
authors.forename: A
authors.initials: A
authors.lastname: Trabattoni
authors.forename: M
authors.initials: M
authors.lastname: Nisoli