| 摘要 |
PURPOSE:To provide aim alignment apparatus free from fluctuation of air securing freedom of the arrangement of an alignment mark. CONSTITUTION:First diffraction gratings RM1 and RM2 provided on a first object are irradiated with light beams LB1 and LB2 from two specified directions to detect primary diffraction light LBr1 and LBr2 to be diffracted with the first diffraction gratings while a second diffraction grating WM is irradiated with 0-order light LBW1 and LBW2 through the first diffraction gratings to detect the primary diffraction light BTW1 to be diffracted with the second diffraction grating. |
