| 摘要 |
<p>PURPOSE:To enhance detection sensitivity while preventing contamination clue to dust by providing a stray light shielding member for lowering noise due to scattering light. CONSTITUTION:A laser beam emitted from a light source 13 passes through a vacuum window 11 at an introduction port 9 and an opening 16 of a stray light shielding member 15 and introduced onto a substrate 4 set on a movable table 3 thus scanning the substrate in a desired direction. The laser beam is scattered on the vacuum window 11 and tire scattering light is shielded by the shielding member 15. Stray light produced through diffuse reflection on the inner wall of a vacuum vessel 1 is also shielded by the shielding member 15 thus suppressing the back ground from increasing. If a dust particle is present on the substrate 4, the laser beam is scattered by the dust particle and detected by a detector 14. A ball screw 6 and a rotary mechanism 2 are driven, when necessary, by a drive mechanism 7 disposed on the outside of the vessel 1 thus shifting the table 3. The movable parts are covered with a cover 5 and a dust- proof bellows 8 in order to protect the substrate 4 against contamination with dust.</p> |
