To provide a focusing method and device by which focusing is quickly performed even on a rugged sample with a plurality of focal planes and on a sample with an unclear contour.
A maximum focal position is detected by making laser slit light from laser spot light by a laser diode or the like, projecting the laser slit light onto the surface of the sample, imaging the laser slit light reflected from the sample on a line sensor arranged vertically to the optical axis via a half mirror, shifting the line sensor in the direction of the optical axis, characterizing a moving distance and a high-frequency component amount of the line sensor image, and detecting a moving distance at which the high-frequency component amount of the line sensor image is maximized.
OTSUKA SHIGENOBU
SHIMIZU TAKAHIRO
