An ion source for a mass spectrometer comprising: one or more optical components arranged and adapted to focus, in use, a laser beam so as to impinge directly upon an upper surface of a target substrate in order to cause the release of ions from said upper surface, wherein said one or more optical components have an effective focal length ≤ 300 mm and wherein, in use, said one or more optical components direct said laser beam onto the target substrate at an angle θ with respect to the perpendicular to the target substrate, wherein θ ≤ 3°; one or more ion guides arranged and adapted to receive ions released from said upper surface of said target substrate, wherein said one or more ion guides comprise a plurality of electrodes; and a device arranged and adapted to apply an AC or RF voltage to at least some of said plurality of electrodes in order to create a pseudo-potential which acts to confine ions radially within said one or more ion guides; wherein said one or more optical components are arranged and adapted to direct said laser beam along a longitudinal axis of said one or more ion guides; wherein said one or more ion guides are arranged and adapted to onwardly transmit said ions away from said longitudinal axis along an ion path which substantially bypasses said one or more optical components by radially transferring ions from an ion guide which has a relatively larger cross-sectional profile to an ion guide which has a relatively smaller cross-sectional profile to transfer ions to a secondary ion optic axis parallel to the incident laser optic axis; wherein said one or more ion guides are arranged to guide said ions along said secondary ion optic axis into an ion inlet of a mass spectrometry system; and wherein said one or more ion guides comprises a conjoined ion guide comprising: (i) a first ion guide section comprising a plurality of electrodes each having an aperture through which ions are transmitted and wherein a first ion guiding path is formed within the first ion guide section; and (ii) a second ion guide section comprising a plurality of electrodes each having an aperture through which ions are transmitted and wherein a second ion guiding path is formed within the second ion guide section. one or more optical components arranged and adapted to focus, in use, a laser beam so as to impinge directly upon an upper surface of a target substrate in order to cause the release of ions from said upper surface, wherein said one or more optical components have an effective focal length ≤ 300 mm and wherein, in use, said one or more optical components direct said laser beam onto the target substrate at an angle θ with respect to the perpendicular to the target substrate, wherein θ ≤ 3°; one or more ion guides arranged and adapted to receive ions released from said upper surface of said target substrate, wherein said one or more ion guides comprise a plurality of electrodes; and a device arranged and adapted to apply an AC or RF voltage to at least some of said plurality of electrodes in order to create a pseudo-potential which acts to confine ions radially within said one or more ion guides; wherein said one or more optical components are arranged and adapted to direct said laser beam along a longitudinal axis of said one or more ion guides; wherein said one or more ion guides are arranged and adapted to onwardly transmit said ions away from said longitudinal axis along an ion path which substantially bypasses said one or more optical components by radially transferring ions from an ion guide which has a relatively larger cross-sectional profile to an ion guide which has a relatively smaller cross-sectional profile to transfer ions to a secondary ion optic axis parallel to the incident laser optic axis; wherein said one or more ion guides are arranged to guide said ions along said secondary ion optic axis into an ion inlet of a mass spectrometry system; and wherein said one or more ion guides comprises a conjoined ion guide comprising: (i) a first ion guide section comprising a plurality of electrodes each having an aperture through which ions are transmitted and wherein a first ion guiding path is formed within the first ion guide section; and (ii) a second ion guide section comprising a plurality of electrodes each having an aperture through which ions are transmitted and wherein a second ion guiding path is formed within the second ion guide section.