| 摘要 |
PROBLEM TO BE SOLVED: To provide a focusing device which actualizes proper focusing even if reflected light from a sample which is used for focusing includes an unnecessary reflected light component other than a laser beam source and a dark current of a photodetecting element. SOLUTION: This device is equipped with a laser beam driver 16 and difference signal detectors 17 and 21 and detects the reflected light from the sample when a measurement light source is turned on and off respectively to decide a focusing point only by the reflected light component of measurement light even if the reflected light from the sample includes the component other than the measurement light and the dark current component of the photodetecting element, thereby adjusting the focus. |
