A time-of-flight mass spectrometer includes a pulsed ion source that generates a pulse of ions from a sample to be analyzed. An ion lens focuses the pulse of ions into an ion beam. An ion deflector deflects the ion beam into a deflected ion beam path. An ion mirror is positioned in the deflected ion beam path so that a plane of constant ion flight time is parallel to an input surface of the ion mirror. The ion mirror decelerates and then accelerates ions so that ions of like mass and like charge exit the ion mirror in a reflected ion beam and reach an ion detector at substantially the same time. An ion detector is positioned in the path of the reflected ion beam so that a plane of constant ion flight time is substantially parallel to an input surface of the ion detector. The ion detector detects a time-of-flight of ions from the pulsed ion source to the ion detector that is substantially independent of a path traveled.