| 摘要 |
PURPOSE:To detect the rotation error of apperture with high accuracy, with the position of the changing point of the signal waveform, by scanning the rectangular electron beam with crossing the knife edge, and detecting the transmission electron strength at that time. CONSTITUTION:The electron rays emitted from the electron gun 1 is collected with the collective lens 2, the electron rays collected are projected on the apperture plate 3, and they are passed through the rectangular apperture 4 of the apperture plate 3, and image is formed with the electron lens 5 and the shrinked image is formed on the test piece. The knife edge 6 is located at the position along the electron path after the apperture 4 and the electron ray detector 7 is placed under the knife edge 6. Further, the deflection power supply 9 is placed on the knife edge 6 and the electron ray deflector 8 is operated with the deflection power supply 9 so that the beam passed through the apperture 4 crosses the knife edge 6, and different information is given to the detector 7 taking boundary at a line, the output of the detector 7 is fed to the display unit 4 via the differentiation circuits 11, 12 and 13, detecting the rotation error. |
