| 摘要 |
PURPOSE:To immediately correct the rotation of the picture pattern of a picture storage device that stores the secondary electron from a sample by Fourier- transforming the picture pattern, calculating the rate of rotation from it, and correcting a deflector. CONSTITUTION:A sample 1 is irradiated with an electron beam 4 and the secondary electron 5 from the sample 1 is detected by a detector 6. Besides, the output is digitalized by an A/D converter 8 and is stored in a picture storage device 9 that synchronizes with scanning. The picture is Fourier-transformed by a Fourier-transformation processor 10 and is supplied to a rate of rotation detector circuit 11. The Fourier-transformed pattern is linearly approximated and the angle made by an X axis is output as the rate of rotation. Then the output is supplied to a revolution corrector circuit 12 and controls a deflector 3. As a result, the rotation of the picture pattern can immediately be corrected and the operation time can sharply be shortened. |
