[en] System of ion focusing in a laser source with application of a single lens is calculated and studied in detail. Ions were accelerated in the uniform field in a gap between two parallel grids. The beam focusinng was accomplished usig the conical electrode. The second grid, conical electrode, and outlet diaphragm formed single lens, in the field of which ions were decelerated to 10 keV energy, and then accelerated again up to 24 keV. At total beam current of 10 mA the beam crossover is 1-2 mm. It is shown that the crossover size does not depend on total beam current, but is defined by the magnitude of phase volume and the system aberrations. The current density varies directly with the laser radiation focusing spot square