Mass spectrometer

Abstract

A sample S is irradiated with a two-dimensionally spread ray of laser light to simultaneously ionize substances within a two-dimensional area on the sample. The resultant ions are mass-separated by a TOF mass separatorwithout changing the interrelationship of the emission points of the ions. The separated ions are then directed to a two-dimensional detector sectionthrough a deflection electric field created by deflection electrodesand. The two-dimensional detector sectionconsists of a plurality of detection unitsarranged in parallel, each unit including an MCP, fluorescent plateand two-dimensional array detector. The magnitude of deflecting the flight path of the ions by the deflection electric field is changed in a stepwise manner with the lapse of time from the generation of the ions so that a plurality of mass analysis images are sequentially projected on each detection unit. When the mass analysis image shifts from one detection unit to another, the data acquisition operation by the two-dimensional array detector in the previous detection unit is discontinued. As a result, a predetermined number of the latest images are held inside the detector. Thus, the measurement time can be extended to widen the measurable mass-to-charge ratio range, while ensuring a high mass resolution.