Abstract: The present invention relates generally to ion beam handling in mass spectrometers, and more specifically to a method and apparatus for focusing ions in time-of-flight mass spectrometers (TOFMS). This invention focuses ions using one or more electrodes bound on at least one side by an electrically conducting grid. Electric fields generated by the electrodes focus the ions. With electric fields of the proper strength and geometry, ions may be focused onto a point some desired distance from the source. According to the preferred embodiment of the present invention, a shielded lens, in the form of an electrically conducting cylinder and two conducting grids, is used to produce and adjust the position of an ion focal point.