2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/94057We study a novel optical setup which is able to select a specific Fock component from a generic input state. The device allows to synthesize number states and superpositions of few number states, and to measure the photon distribution and the density matrix of a generic input signal.7 pages LaTeX, contribution to proceedings of 6th central-european workshop on quantum optics (actaps.sty included)Quantum Physicstext