| 摘要 |
PROBLEM TO BE SOLVED: To accurately detect a focus position without depending on the state of a plane where a focusing beam enters on a sample. SOLUTION: This method is based on the fact that the horizontal distance between an image forming pint Z0 on a sample 7 and the reflecting point Zd of the focusing beam can be preliminarily estimated from the vertical displacementΔZ of the sample by using an oblique incidence focusing beam PB. Therefore, the sample 7 is shifted by (ΔX,ΔY) in the horizontal direction according to the vertical displacementΔZ so that the reflection point Zd of the focusing beam is forcedly made coincide with the image forming Z0 . Thus, accurate focusing can be realized. |
