PURPOSE: To enable high-speed and highly accurate observation of a specimen having a rough surface by providing a scattered-ray-filter means with an opening at the focusing point of the reflected ray which has passed through a condenser.

CONSTITUTION: A ray 9 reflected on the surface of a cantilever 5 is collected with a condenser 6. A scattered-ray-filter means 7 has a small opening, at which the ray collected with the lens 6 focuses. Then, the ray focuses at the small opening and is projected on a ray detector 8. A ray 10 falling not on the cantilever 5 but on a specimen does not focus at the opening or is projected on the ray detector 8, because it is blocked with the scattered-ray-filter means 7. Thus, a ray that could be a noise is not projected the ray detector 8.