New types of mirrors for the soft x-ray range (review)

A review is given of the published experimental and theoretical work on the development of mirrors in rotation devices for the soft X-ray range 2-100 nm. Two types of reflectors are considered: (1) multilayer periodic structures capable of reflecting efficiently soft X rays incident at near-normal angles; (2) concave grazing-incidence mirrors rotating continuously the incident rays through large angles. A comparative analysis is made of the methods used to prepare multilayer coatings that reflect X rays. The parameters of the existing X-ray mirrors are given and their main applications are discussed. The known optical constants of the materials used in various mirrors are used in theoretical estimates of the likely reflectivity of mirrors of both kinds.