An electron microscope includes: an electron source, which is configured to generate an electron beam; a first beam conduit, which is configured to accelerate the electron beam; a second beam conduit, which is configured to accelerate the electron beam; a first detector, which is disposed between the first beam conduit and the second beam conduit and configured to receive secondary electrons generated by the electron beam acting on a sample to be tested; and a control electrode, which is disposed between the first detector and an optical axis of the electron beam and configured to change the direction of movement of backscattered electrons and the secondary electrons generated by the electron beam acting on said sample.