Patent ID: 9373491
Filing Date: 2016-06-21
CPC Classification: H01J

Claim Text:
1. A mass spectrometer comprising: an ionizer configured to ionize a measurement gas; a filter configured to selectively pass therethrough an ion of a target gas having a predetermined mass-to-charge ratio among components of the measurement gas ionized by the ionizer; an ion detector configured to detect an ion detection value based on the ion of the target gas that passes through the filter; a light detector configured to detect a light detection value based on vacuum ultraviolet light generated when the ionizer ionizes the measurement gas; and an arithmetic unit configured to calculate a partial pressure of the target gas by using the light detection value and the ion detection value, wherein the light detector comprises: a vacuum ultraviolet light detector configured to detect a photoelectric current value according to the vacuum ultraviolet light incident thereon; and an ion blocking electrode configured to block ions from entering the vacuum ultraviolet light detector.