| 摘要 |
PROBLEM TO BE SOLVED: To provide a focus detecting apparatus that realizes stable focusing with a fixed height on a rugged sample surface, even if the ruggedness has periodicity. SOLUTION: The focus detector has a laser beam source, a collimating means of collimating a laser beam, a knife edge to intercept the half of the parallel beams to thereby make the parallel beams semicircular, an objective lens for projecting the beams made semicircular to the surface of an observation object to thereby form the image thereon and restore the reflected light to be parallel, a means of transmitting either the projected beam or the reflected beam and reflect the other, to thereby separate the beams to two optical axes, a means to make the beam from the separated reflected light form the image on a focal plane that is conjugate to the focal plane of the objective lens, and a means placed on the focal plane conjugate to the focal plane of the objective lens and outputing the luminance of the formed image, and the focus detector is equipped with a means arranged on a side where the laser beam is made incident on or emitted from the collimating means and to divide the laser beam made the parallel beams by the collimating means to a plurality of parallel beam groups, whose propagating directions are somewhat different from each other. When the parallel beam groups are projected to the sample surface by the objective lens, they form an images as a plurality of points arranged at unequal intervals. COPYRIGHT: (C)2006,JPO&NCIPI |
