First observation of Moire fringes in a proton beam generated by a 100 fs laser pulse

High contrast Moire fringes have been observed when two gratings were inserted into a proton beam produced from the interaction of a 100 TW laser beam with a thin solid foil. Moire fringes with modulation close to 20% were observed in protons with energies between 4 and 7 MeV. The fringes were rotated with respect to a collimated optical test beam, a finding consistent with the protons originating from a point source close to the original target surface. These important results indicate that proton Moire can be used as a high precision diagnostic of proton beam deflections from electric and magnetic fields in plasmas.