| 摘要 |
PROBLEM TO BE SOLVED: To provide a focus adjustment device which attains a suitable focus adjustment regardless of a sample to be observed. SOLUTION: The focus adjustment device comprises: a photodetector means which has a photodetector for focus detection to receive reflected light from the object to be observed at a position of different optical path length; an amplifier means which has an amplifier circuit to amplify an output signal from the photodetector means; a focus detection means which generates a defocus signal showing deviation in an optical axis direction between the focal position of an objective lens and the object from an image formed on a light receiving surface arranged at the position of the different optical path length based on the output signal from the amplifier means; and an adjusting means which adjusts space between the objective lens and the object based on the defocus signal. The amplifier means amplifies the output signal from the photodetector means by first gain within a first range in the optical axis direction, and amplifies the output signal from the photodetector means by second gain different from the first gain within a second range different from the first range. COPYRIGHT: (C)2009,JPO&INPIT |
