  We present a simple diode laser-based photoionization scheme for generating
electrons and ions with well-defined spatial and energetic (<2 eV) structures.
This scheme can easily be implemented into ion or electron imaging
spectrometers for the purpose of off-line characterization and calibration. The
low laser power ~1$ mW needed from a passively stabilized diode laser and the
low flux of potassium atoms in an effusive beam make our scheme a versatile
source of ions and electrons for applications in research and education.
