| 摘要 |
PROBLEM TO BE SOLVED: To provide a projection-type charged particle optical system in which a projection magnification can be changed while suppressing deterioration in measurement accuracy of a mass-to-charge ratio.SOLUTION: A projection-type charged particle optical system according to the present invention includes: a first electrode facing a sample and having an opening for allowing a charged particle to pass therethrough; a second electrode disposed on a side of the first electrode opposite to where the sample is disposed and having an opening for allowing a charged particle to pass therethrough; and a flight-tube electrode configured to allow a charged particle, which has been emitted from the sample and has passed through the second electrode, to enter the flight-tube electrode, and having a substantially equipotential space at the inside thereof. A principal plain is formed on at least two or more positions in a travel path of a charged particle. |
