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An important challenge for the X-ray astronomy of the new millennium is represented by the implementation of an Xray
telescope able to maintain the exquisite angular resolution of Chandra (with a sub-arcsec HEW, on-axis) but, at the
same time, being characterized by a much larger throughput and grasp. A mission with similar characteristics is
represented by the X-ray Surveyor Mission. The project has been recently proposed in USA and is being currently
studied by NASA. It will host an X-ray telescope with an effective area of more than 2 square meters at 1 keV (i.e. 30
times greater than Chandra) and a 15-arcminutes field-of-view, with 1-arcsecond or better half-power diameter (versus
the 4 arcmin diameter of Chandra). While the scientific reasons for implementing a similar mission are clear, being
related to compelling problems like e.g. the formation and subsequent growth of black hole seeds at very high redshift or
the identification of the first galaxy groups and proto-clusters, the realization of a grazing-angle optics system able to
fulfil these specs remain highly challenging. Different technologies are being envisaged, like e.g. the use of adjustable
segmented mirrors (with use of piezoelectric or magneto-restrictive film actuators on the back surface) or the direct
polishing of a variety of thin substrates or the use of innovative correction methods like e.g. differential deposition, ionfiguring
or the correction of the profile via controlled stress films. In this paper we present a possible approach based on
the direct polishing (with final ion figuring correction of the profile) of thin SiO2 segmented substrates (typically 2 mm
thick), discussing different aspects of the technology under implementation and presenting some preliminary results.
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