| 摘要 |
PURPOSE:To display images free from blurs by comparing detection signals with the signal stored in an image memory and multiplying the detection signals according to an address relationship corresponding to the minimum level of the result of the comparison before the multiplication result is stored in the image memory. CONSTITUTION:Electron rays are scanned over an intended area of a sample 3 several times and a detector 9 is used to detect secondary electrons produced during scanning. Then, the result of each detection is converted into a digital signal. Next, thus generated digital signals are multiplied and the multiplication result is stored in an image memory 16 before being displayed on a displayer 19. An operation part 14 is used to compare the signals stored in one-line memories 12 and 13 with the signal generated by reading out a line of data stored in the image memory 16 by the use of a circuit 17 and stored in a one-line memory 18. The above multiplication is performed in accordance with an address relationship corresponding to the minimum level of the result of the above comparison. Accordingly, accurate multiplication can be performed even when electron rays drift, thereby producing images of high SN ratio free from blurs. |
