| 摘要 |
PURPOSE:To prevent degradation of an extinction factor E.F. by arranging a cross-shaped aperture stop in the pupil of an object lens or a position conjugate to it and permitting only rays, where the polarization direction is not rotated, to pass through efficiently but intercepting rays where the polarization direction will be rotated or is rotated. CONSTITUTION:When an exit pupil 23 of an object lens 16 is observed through an analyzer 19, a dark cross line 22 is observed. A harmful light which reduces the E.F. is the luminous flux which passes through a light part which is seen in the exit pupil 23 when it is observed through the analyzer 19, and the luminous flux which passes through the part of the dark cross line 22 is intercepted by the analyzer 19 and does not reduce the E.F. A cross-shaped aperture stop 13 is arranged in the conjugate position in the front of a condenser lens 14. The aperture stop 13 can be rotated around the optical axis in accordance with rotation of a polarizer 12 and the analyzer 19 so that the dark cross line 22 and the aperture of the cross-shaped aperture stop 13 coincide with each other. |
