| 摘要 |
PURPOSE:To perform an accurate sample observation that is not affected by the radiation of an electron beam and the excitation of a sample by providing a data collector section with two circuits that differ in characteristics so as to obtain specified analog data from the output of a secondary electron detector and freely selecting the two circuits depending upon the properties of an observed sample. CONSTITUTION:A secondary electron detector 2 consisting of photomultipliers that detect the secondary electrons emitted from a sample is provided in a stroboscope SEM1. The output of the secondary electron detector 2 is input to a CRT8 that performs the picture display of the sample surface. At the same time, it is also input to a data collection circuit 9 that obtains specified analog data depending upon the properties of the sample, converts it into digital data, and issues it. This data collection circuit 9 consists of the first circuit in which a passive type RC integration circuit 11 and an A/D conversion circuit 12 are coupled directly and the second circuit in which a diode coupling integration circuit 13 and an A/D conversion circuit 14 are coupled directly. Since both of these circuits can optionally be selected by a multiplexer circuit 15, the optimum integration circuit can be selected depending upon the properties of an observed sample, such as fluctuations of oscillating frequencies and the grade of the effect affected by the radiation of the electron beam. |
