| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem wherein, when detecting scattered light from an inspection object by using a pulse laser as a light source, a noise is increased, if a sampling period of an A/D converter is not determined correlatively with a pulse oscillation frequency of the light source. SOLUTION: The sampling period of the A/D converter is set (1) to be equal to or integer-fold of the pulse oscillation frequency of the light source, to be thereby synchronized with oscillation of the light source, or (2) to be half-integer-fold of the pulse oscillation frequency of the light source, hereby, even if a ripple component originated in an emission pulse from the light source remains in a scattered light signal given to the A/D converter, an influence thereof can be removed or reduced. COPYRIGHT: (C)2008,JPO&INPIT |
