公开(公告)号：US3924156A

公开(公告)日：1975-12-02

申请号：US48326674

申请日：1974-06-26

Applicant: IBM

Inventor： DORAN SAMUEL K ,  PERKINS MERLYN H

IPC: E01C11/26 ,  H01J37/153 ,  H01J37/21 ,  H01J37/244 ,  H01J37/30 ,  H01J37/305 ,  H01L21/027 ,  H05B3/36 ,  H05B3/56 ,  H01J29/70

CPC classification number: H01J37/21 ,  E01C11/265 ,  H01J37/153 ,  H01J37/244 ,  H01J2237/24578 ,  H05B3/36 ,  H05B3/56 ,  H05B2203/003 ,  H05B2203/017 ,  H05B2203/026

Abstract: A beam of charged particles is deflected in a closed path such as a square, for example, over a cross wire grid at a constant velocity by an X Y deflection system. A small high frequency jitter is added at both axes of deflection to cause oscillation of the beam at 45* to the X and Y axes. From the time that the leading edge of the oscillating beam passes over the wire until the trailing edge of the beam passes over the wire, an envelope of the oscillations produced by the jitter is obtained. A second envelope is obtained when the leading edge of the beam exits from being over the wire until the trailing edge of the beam ceases to be over the wire. Thus, a pair of envelopes is produced as the beam passes over each wire of the grid. The number of pulses exceeding ten per cent of the peak voltage in the eight envelopes produced by the beam completing a cycle in its closed path around the grid are counted and compared with those counted during the previous cycle of the beam moving in its closed path over the grid. As the number of pulses decreases, the quality of the focus of the beam increases so that correction signals are applied to the focus coil in accordance with whether the number of pulses is increasing or decreasing.

Abstract translation: 带电粒子束通过X Y偏转系统以恒定速度在闭合路径（例如正方形）中偏转，例如在十字线格栅上。 在两个偏转轴处增加了一个小的高频抖动，使得光束在X轴和Y轴处45度的振荡。 从振荡光束的前沿通过导线直到光束的后沿通过导线的时间为止，获得由抖动产生的振荡的包络。 当光束的前缘从导线上退出直到光束的后缘停止在导线上时，获得第二个包络。 因此，当光束通过网格的每条线时，产生一对信封。 对于在其围绕网格的闭合路径中完成周期的波束产生的八个信封中的峰值电压的十分之一以上的脉冲数量进行计数，并与在其闭合路径中移动的波束的前一周期中计数的脉冲数进行比较 电网。 随着脉冲数量的减少，光束的焦点质量增加，根据脉冲数是增加还是减少，校正信号被施加到聚焦线圈。