| 摘要 |
PURPOSE:To improve time resolution by shifting a phase and performing an adding/averaging process in such a way that, with respect to data rows of voltage measurement values obtained by means of repeating a plurality of phase scanning processes, correlation in phases between the data rows every scanning process is made to be maximum. CONSTITUTION:A clock 72 synchronized with repeated periodic operations a sample 5 is processed by a delay unit 9 so as to generate an electron beam pulse, which is emitted to the sample 5 so that a voltage at an emitted point is measured with the secondary electron 61. In this case, a correlation function value between data rows in voltage measurement value obtained by scanning while sequentially changing emitting phases and data rows obtained at the predetermined one of times is computed so that a deviation in phases corresponding to the maximum value may be found. And the phase is shifted based on said deviation so as to perform an adding/averaging process for correcting a take-in operation of the data rows and said processes are repeated by plural times. Therefore, it is possible to prevent the lowering of time resolution in observation voltage wave form by the drift of a circuit.
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