| 摘要 |
PURPOSE:To reduce deflection astigmation without the needs to make complicated adjustment by a structure in which two electron lenses and one deflector are jointly arranged in such a way that the electromagnetic fields of the light source side lens and the deflector are superposed on each other. CONSTITUTION:The focusing deflector consists of two electron lenses 8 and 9 and one deflector 10 provided inside or in the neighborhood of the lens 8 on the light source side. The deflection astigmation on the sample surface 2, although it becomes greater by the lens 8 and the deflector 10, can be made smaller by the lens 8 and the deflector 10 are arranged in such a way that the electromagnetic fields of the lenses 8 and 9 are inversed from each other so as to negate off-axis astigmation produced by the lens 9. Also, vertical incidence against the sample surface 12 of the charged particle orbit 12 can be made possible by forming the image focusing point 14 of the lens 8 on the opposite side of the lens 9 with regard to the sample surface 2 and by forming the point 13 near the frontal focusing position of the lens 9. Thus, adjustment can be made easier and the deflecting astigmation can be reduced. |
