| 摘要 |
<p>PURPOSE:To detect granular foreign matters at high precision and detect phase substances, which are stains, etc., as foreign matters by combining a light projecting and receiving system which receives back scattering light by making the incidence angle large with a light projecting and receiving system which receives weak scattering light by making the incidence angle small. CONSTITUTION:After laser beam from a light source 1 is expanded by expanders 2, 3, reflected by oscillation mirror 4, ad led to impinge on the surface of a reticle 9 at wide incident angle Q; 45 deg.<=Q<90 deg.; through a scanning lens 5. The scanning spot is scanned in X-direction and the back scattering light of scattering light due to foreign matters on the reticle 9 is received by a two-dimensional image sensor 15 through reflecting mirror 11 to detect granular foreign matters. Meanwhile, laser beam from a light source 21 is expanded by expanders 22, 23, reflected by oscillation mirror 24, and led to impinge on the surface of the reticle 9 at narrow incidence angle Q; 2 deg.<Q2<45 deg.; and scanning is carried out in X-direction. Weak diffraction light attributed to the foreign matters is received by the two-dimensional image sensor 35 to detect stains, such as spots, etc.</p> |
