Local spectra of spatial frequencies of Bessel beams

Local spatial spectra of Bessel beams fragments limited by the radial-shifted circular diaphragms have been investigated. It has been shown theoretically and experimentally that in case when circular diaphragm is placed on the axis of zero-order Bessel beam or includes its central maximum, the spectrum of such Bessel beam fragment is annular. When shifting the diaphragm behind the limits of the axial maximum, the spectrum takes the form of an arc. It has been established that the detected properties of spatial spectra occur independently of the technique and optical scheme of Bessel beams formation.