  The LAMP (Lightweight Asymmetry and Magnetism Probe) X-ray telescope is a
mission concept to measure the polarization of X-ray astronomical sources at
250 eV via imaging mirrors that reflect at incidence angles near the
polarization angle, i.e., 45 deg. Hence, it will require the adoption of
multilayer coatings with a few nanometers d-spacing in order to enhance the
reflectivity. The nickel electroforming technology has already been
successfully used to fabricate the high angular resolution imaging mirrors of
the X-ray telescopes SAX, XMM-Newton, and Swift/XRT. We are investigating this
consolidated technology as a possible technique to manufacture focusing mirrors
for LAMP. Although the very good reflectivity performances of this kind of
mirrors were already demonstrated in grazing incidence, the reflectivity and
the scattering properties have not been tested directly at the unusually large
angle of 45 deg. Other possible substrates are represented by thin glass foils
or silicon wafers. In this paper we present the results of the X-ray
reflectivity campaign performed at the BEAR beamline of Elettra - Sincrotrone
Trieste on multilayer coatings of various composition (Cr/C, Co/C), deposited
with different sputtering parameters on nickel, silicon, and glass substrates,
using polarized X-rays in the spectral range 240 - 290 eV.
