公开(公告)号：US20080237461A1

公开(公告)日：2008-10-02

申请号：US12079166

申请日：2008-03-25

申请人： Jong-Deok Kim ,  Byung-Am Lee ,  Kyung-Ho Kim ,  Byung-Seol Ahn ,  Young-Hun Park ,  Kong-Jung Sa

发明人： Jong-Deok Kim ,  Byung-Am Lee ,  Kyung-Ho Kim ,  Byung-Seol Ahn ,  Young-Hun Park ,  Kong-Jung Sa

IPC分类号： G21K7/00

CPC分类号： H01J37/21 ,  H01J37/222 ,  H01J37/28 ,  H01J2237/216

摘要： In an autofocus method, an electron beam is scanned onto a subject through a condensing member. A setting condition of the condensing member is changed within a first range. An image evaluation value is measured using a secondary electron current from the subject according to the setting condition within the first range. A second range adjacent to the first range and including the setting condition corresponding to the first maximum is set when a first maximum of the image evaluation value is not a peak value. The setting condition is changed within the second range. An image evaluation value is measured using a secondary electron current according to the setting condition within the second range. The condensing member is set with the setting condition corresponding to a second maximum of the image evaluation value when the second maximum value is the peak value.

摘要翻译： 在自动聚焦方法中，电子束通过聚光部件被扫描到被摄体上。 聚光部件的设定状态在第一范围内变化。 根据第一范围内的设定条件，使用来自被检体的二次电子流测定图像评价值。 当图像评估值的第一最大值不是峰值时，设置与第一范围相邻并且包括与第一最大值相对应的设置条件的第二范围。 设定条件在第二范围内变化。 根据第二范围内的设定条件，使用二次电子电流测定图像评价值。 当第二最大值是峰值时，聚光构件被设置为与图像评估值的第二最大值相对应的设置条件。