| 摘要 |
PURPOSE:To enable the axis of an electron beam to be adjusted in a short time by utilizing the correlation between the vector of the positional shift of a discharged beam caused when the current of the electron lens is changed and the position on the electron lens upon which the elctron beam becomes incident. CONSTITUTION:The axis of an electron beam 11 is adjusted to coincide with the center of an electron lens 12 by means of a deflecting means 13 installed in front of the electron lens 12 of an electro-optical mirror tube. The current of the electron lens 12 is changed for each of three positions (Ax, Ay) upon which the electron beam 11 becomes incident and the X-direction component (u) and the Y-direction component (v) of the vector (X) for the positional shift of the electron beam 11 are detected. Then K1-K6 are calculated according to the formulae u=K1.Ax+K2Ay+K3 and v=K4Ax+K5.Ay+K6. Besides, the incidence position for which (u) and (v) become zero are calculated and then a corresponding input is supplied to the deflecting means 13. Consequently, it is possible to efficiently adjust the axis of the electron beam 11 in a short time. |
