Patent ID: 9275843
Filing Date: 2016-03-01
CPC Classification: H01J

Claim Text:
1. An orthogonal acceleration time-of-flight mass spectrometer comprising: an orthogonal acceleration unit for accelerating incident ions in a direction orthogonal to an incident axis of the ions; and an ion-injecting optical system for sending the ions into the orthogonal acceleration unit, wherein the ion-injecting optical system comprises: an electrostatic lens composed of five or more cylindrical electrodes arranged along an ion-optical axis; a voltage supplier for applying voltages to the respective cylindrical electrodes so that the electrostatic lens becomes an afocal system; and a restrictor having an aperture of a predetermined size on the ion-optical axis, the restrictor being located on a common focal plane of a first-stage virtual convex lens formed by a portion of the five or more cylindrical electrodes and a second-stage virtual convex lens formed by a portion of the five or more cylindrical electrodes under a condition that the voltages for making the electrostatic lens become an afocal system are applied from the voltage supplier, wherein the restrictor sets the angular distribution of ions.