Metrics for focusing in extremely noisy scanning electron microscopy condition.
Finding a best focused image in very noisy condition is an extremely difficult task for the SEM user. If a performance, which is much higher than that of an expert in focusing, can be achieved in a computer-controlled scanning electron microscope (SEM), it will be very helpful for our field due to the many possible applications. To accomplish this work, we employ a powerful metric-the covariance obtained by a special scanning method. It can select the best focused image from a series of SEM images acquired by altering the focus of the objective lens under an extremely noisy SEM image condition. The noise immunity of the present method is quantitatively evaluated, and it is further improved based on the obtained evaluation result.
Oho
Eisaku
E
Department of Electrical Engineering, Kogakuin University, Tokyo, Japan. oho@sin.cc.kogakuin.ac.jp
Kawamura
Kazunari
K
Hatakeyama
Toshiaki
T
Suzuki
Kazuhiko
K