| 摘要 |
PROBLEM TO BE SOLVED: To change the numerical aperture of an objective lens selectively by providing an opening means changing area of an opening part transmitting luminous flux according to the polarizing state of the luminous flux incident of the objective lens from a light source side. SOLUTION: The semiconductor 2 of the light source emits the laser luminous flux of a linearly polarized light, and the luminous flux enters a beam splitter 3 through an electrooptical element 7 as a polarizing state variable means. The electrooptical element 7 is formed into a transparent planar shape, and its both side parts are held between transparent electrodes 13, 14. The electrooptical element 7 changes the polarizing direction of the transmitting laser luminous flux by applying a voltage between respective transparent electrodes 13, 14. The laser luminous flux reflected by the beam splitter 3 is made incident on the objective lens through a wire grid aperture 12 as the opening means. The wire grid aperture 12 changes the area of the opening part transmitting through the laser luminous flux according to the polarizing state of the laser luminous flux made incident on a wire grid aperture plate. |
