| 摘要 |
PURPOSE:To make it possible to display the magnification of a sample image, and also to measure the length of the sample image at any point. CONSTITUTION:After circuit A is selected 21, voltage VB of variable DC power supply 22 is compared 23 with scanning signal VX to generate a pulse with VX to generate a pulse with VX less than VB, gating 24 is done by a pulse generated at the time when scanning signal VY is between reference voltages V1 and V2, and the signal is added to secondary-electron detection signal 4 for brightness moudulation, so that scale 25 will be displayed on CRT7. By VB and the output of magnification control circuit 14, the actual length of mark length (l) on CRT is measured 31 and displayed 20. Further, horizontal and vertical scanning signals are compared with several variable reference signals and the length of the mark and its dislay position are changed. Once a conversion value on the sample surface of the mark length is assigned 33 after circuit B is selected 21, assigned length 33 is controlled automatically and displayed 20 by magnification control output 14. It is convenient to display the contents of display 20 on the CRT screen. |
