“…The spherical mean operator R and its dual t R play an important role and have many applications, for example, in image processing of so-called synthetic aperture radar (SAR) data [14,15], or in the linearized inverse scattering problem in acoustics [9]. Many aspects of such operator have been studied [1,3,6,18,21]. In particular, in [18] the first author with the others associated to the spherical mean operator the Fourier transform defined by ∀(µ, λ) ∈ Γ, F (f)(µ, λ) = r n dr ⊗ dx.…”